METHOD FOR PROCESSING SUBSTRATE

Abstract

A method for processing a substrate includes dispensing isopropyl alcohol (IPA) onto the substrate, providing the substrate into a processing chamber, pressurizing the processing chamber to a pressure above 5 MPa, removing the IPA on the substrate by displacing the IPA with liquid carbon dioxide (CO.sub.2), and removing the liquid CO.sub.2 as gaseous CO.sub.2 by venting the processing chamber.

Claims

1. A method for processing a substrate, the method comprising: dispensing isopropyl alcohol (IPA) onto the substrate; providing the substrate into a processing chamber; pressurizing the processing chamber to a pressure above 5 MPa; removing the IPA on the substrate by displacing the IPA with liquid carbon dioxide (CO.sub.2); and removing the liquid CO.sub.2 as gaseous CO.sub.2 by venting the processing chamber.

2. The method of claim 1, further comprising recycling the IPA after removing it from the substrate.

3. The method of claim 1, further comprising further pressurizing the processing chamber with N.sub.2 gas to a pressure above 7 MPa after removing the IPA.

4. The method of claim 3, wherein pressurizing the processing chamber with N.sub.2 gas to a pressure above 7 MPa brings the liquid CO.sub.2 to a supercritical state.

5. The method of claim 1, wherein pressurizing the processing chamber to a pressure above 5 MPa is performed with nitrogen (N.sub.2) gas.

6. The method of claim 1, wherein pressurizing the processing chamber to a pressure above 5 MPa is performed with CO.sub.2 gas and IPA vapor.

7. The method of claim 1, wherein the processing chamber is pressurized to a pressure above 7 MPa with CO.sub.2 gas and IPA vapor.

8. The method of claim 1, wherein the processing chamber is at room temperature while displacing the IPA with liquid CO.sub.2.

9. The method of claim 1, wherein the liquid CO.sub.2 is removed without reaching a supercritical condition.

10. A method for processing a substrate, the method comprising: providing the substrate into a processing chamber; dispensing isopropyl alcohol (IPA) onto the substrate; pressurizing the processing chamber with nitrogen (N.sub.2) gas to a pressure above 7 MPa; removing the IPA on the substrate by displacing the IPA with supercritical carbon dioxide (CO.sub.2); and removing the supercritical CO.sub.2 as gaseous CO.sub.2 by venting the processing chamber.

11. The method of claim 10, further comprising recycling the IPA after removing it from the processing chamber.

12. The method of claim 10, further comprising injecting liquid CO.sub.2 into the processing chamber before pressurizing the processing chamber with N.sub.2 gas to a pressure above 7 MPa.

13. The method of claim 12, further comprising pressurizing the processing chamber with N.sub.2 gas to a pressure in a range of 4.5 MPa to 5.5 MPa before injecting liquid CO.sub.2 into the processing chamber.

14. The method of claim 12, wherein the processing chamber is maintained at room temperature while injecting liquid CO.sub.2 into the processing chamber.

15. A method for processing a substrate, the method comprising: dispensing isopropyl alcohol (IPA) onto the substrate; providing the substrate into a processing chamber; pressurizing the processing chamber with carbon dioxide (CO.sub.2) gas to a supercritical pressure while dispensing IPA vapor into the processing chamber; removing the IPA on the substrate by displacing the IPA with supercritical carbon dioxide (CO.sub.2); and removing the supercritical CO.sub.2 as gaseous CO.sub.2 by venting the processing chamber.

16. The method of claim 15, further comprising removing the IPA from the processing chamber after removing the IPA from the substrate.

17. The method of claim 16, further comprising recycling the IPA after removing the IPA from the processing chamber.

18. The method of claim 15, wherein IPA is dispensed onto the substrate before providing the substrate into the processing chamber.

19. The method of claim 15, wherein the substrate is provided into the processing chamber before dispensing IPA onto the substrate.

20. The method of claim 15, wherein pressurizing the processing chamber with CO.sub.2 gas to a supercritical pressure comprises pressurizing the processing chamber to a pressure of 7 MPa or above.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0013] FIG. 1A illustrates an example processing system for processing of a substrate;

[0014] FIG. 1B illustrates an example processing chamber with top and bottom plates adjusted to increase a gap between the top and bottom plates;

[0015] FIG. 1C illustrates an example processing chamber with top and bottom plates adjusted to decrease a gap between the top and bottom plates;

[0016] FIGS. 2 and 3 illustrate cross-sectional views of a substrate;

[0017] FIGS. 4-10 illustrate cross-sectional views of a processing system during intermediate stages of a method for cleaning a substrate, in accordance with some embodiments;

[0018] FIG. 11 illustrates a cross-sectional view of a processing system during an intermediate stage of a method for cleaning a substrate, in accordance with some embodiments;

[0019] FIG. 12 illustrates a cross-sectional view of a processing system during an intermediate stage of a method for cleaning a substrate, in accordance with some embodiments;

[0020] FIGS. 13-15 illustrate cross-sectional views of a processing system during intermediate stages of a method for cleaning a substrate, in accordance with some embodiments;

[0021] FIG. 16 illustrates a process flow chart diagram of a method for processing a substrate, in accordance with some embodiments;

[0022] FIG. 17 illustrates a process flow chart diagram of a method for processing a substrate, in accordance with some embodiments; and

[0023] FIG. 18 illustrates a process flow chart diagram of a method for processing a substrate, in accordance with some embodiments.

[0024] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale. The edges of features drawn in the figures do not necessarily indicate the termination of the extent of the feature.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0025] The making and using of various embodiments are discussed in detail below. It should be appreciated, however, that the various embodiments described herein are applicable in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use various embodiments, and should not be construed in a limited scope.

[0026] According to one or more embodiments of the present disclosure, this application relates to methods of wet and dry processing of a substrate, such as a semiconductor wafer. In conventional semiconductor manufacturing processes, liquid or supercritical carbon dioxide (CO.sub.2) may be used for cleaning and drying wafers. Current supercritical chambers may use CO.sub.2 to pressurize the chamber above 7 MPa, thereby allowing supercritical CO.sub.2 to be dispensed onto the wafer. However, this approach consumes large amounts of CO.sub.2, which can be costly and environmentally concerning. Additionally, when isopropyl alcohol (IPA) is used in the process, there is a risk of IPA evaporating from the wafer while the chamber is being pressurized, potentially leading to incomplete cleaning or drying. Furthermore, liquid IPA may cause pattern collapse if the surface of the fluid crosses a fine feature due to its surface tension.

[0027] Embodiments of the disclosure address these challenges by introducing novel approaches to substrate processing. In some embodiments, nitrogen (N.sub.2) gas is used to pressurize the chamber above 7 MPa instead of CO.sub.2, allowing for more efficient use of supercritical CO.sub.2. Other embodiments include dispensing IPA vapor during chamber pressurization to saturate the environment and reduce IPA evaporation from the substrate. Further embodiments utilize liquid CO.sub.2 to displace IPA on the substrate, followed by pressurization to supercritical conditions using N.sub.2. In yet another approach, liquid CO.sub.2 is used for drying at lower pressures, thereby avoiding the use of supercritical conditions.

[0028] These novel approaches offer several advantages over conventional methods. They significantly reduce CO.sub.2 consumption in the supercritical process, leading to cost savings and reduced environmental impact. The use of IPA vapor during pressurization helps maintain consistent IPA coverage on the wafer, potentially improving cleaning efficacy. The liquid CO.sub.2 displacement method allows for IPA recovery and recycling, further enhancing process efficiency. Additionally, the liquid CO.sub.2 drying method operates at lower pressures and room temperature, potentially increasing throughput and reducing equipment costs. Importantly, the lower surface tension of liquid CO.sub.2 compared to IPA may reduce the risk of pattern collapse in delicate semiconductor structures, addressing a significant challenge in advanced semiconductor manufacturing.

[0029] Embodiments of the disclosure are described in the context of the accompanying drawings. An example of a processing chamber for wet and dry processing of a substrate will be described using FIGS. 1A, 1B, and 1C. Embodiments of a method for cleaning a substrate using nitrogen gas to pressurize a processing chamber in preparation for treatment with a supercritical fluid will be described using FIGS. 2-10. Embodiments of a method for cleaning a substrate using nitrogen gas to pressurize a processing chamber in preparation for a drying process with a dry fluid will be described using FIG. 11. Embodiments of a method for cleaning a substrate using nitrogen gas to pressurize a processing chamber to bring a dry fluid to a supercritical condition will be described using FIG. 12. Embodiments of a method for substrate cleaning using a processing vapor during chamber pressurization will be described using FIGS. 13 through 15. Embodiments of methods for processing a substrate will be described using FIGS. 16, 17, and 18.

[0030] FIG. 1A schematically illustrates a cross-sectional view of an example processing system 100 (also referred to as a substrate processing system or a wafer processing system) for processing of a substrate. The processing system 100 is described as a non-limiting example for illustrative purposes. In addition to the processing system 100, any suitable processing system and processing chamber may be used as part of embodiments of the current disclosure, and all such methods using any suitable processing systems and processing chambers are within the scope of the disclosed embodiments.

[0031] The processing system 100 illustrated by FIG. 1A includes a processing chamber 105 in which a substrate 50 (e.g., a semiconductor wafer) is processed. The processing chamber 105 includes a bottom plate 110 having portions making up a lower working surface 120 inside the processing chamber 105 and a top plate 115 having portions making up an upper working surface 125 inside the processing chamber 105. A processing space 106 is formed between the upper working surface 125 and the lower working surface 120 of the processing chamber 105. In some embodiments, the processing space 106 has a diameter in a range of 50 mm to 460, such as 300 mm.

[0032] The upper working surface 125 inside the processing chamber 105 is spaced above the lower working surface 120 and separated by a gap (g). FIG. 1B illustrates a cross-sectional view of an optional example of the processing chamber 105 with top plate 115 and bottom plate 110 adjusted to increase the gap g between the top plate 115 and bottom plate 110, and FIG. 1C illustrates a cross-sectional view of an optional example of the processing chamber 105 with top plate 115 and bottom plate 110 adjusted to decrease the gap g between the top plate 115 and bottom plate 110.

[0033] The processing chamber 105 further includes one or more structure(s) for supporting the substrate 50 in the processing space 106. In various examples, the one or more structure(s) for supporting the wafer includes a plurality of pins 123 that extend through the bottom plate 110 into the processing space 106 and supports the substrate 50 from the bottom, as shown in FIG. 1A. In one example, the substrate 50 is supported by at least three circumferentially spaced pins 123 projecting from the bottom plate 110 and extending above the lower working surface 120. In other examples, a plurality of pins 123 can support the substrate 50 by contacting the edge of the substrate 50. Although either example may be utilized, a plurality of pins 123 that support the substrate 50 from the bottom may prevent sagging of the substrate 50, and thus, the formation of a non-uniform gap between the upper/lower working surfaces of the processing chamber 105 and the top/bottom surfaces of the wafer.

[0034] When a substrate 50 to be processed is inserted and mounted within the processing space 106, an upper gap (g U) is present between the upper working surface 125 of the processing chamber 105 and the top surface of the wafer, and a lower gap (g L) is present between the lower working surface 120 of the processing chamber 105 and the bottom surface of the wafer. It may be desirable that the upper gap (g U) and the lower gap (g L) be substantially equal to maintain a similar distance (or uniform gap) between the upper working surface 125 and the top surface of the substrate 50 and the lower working surface 120 and the bottom surface of the substrate 50. In some examples, the upper gap (g U) and the lower gap (g L) may be in a range between 0.01 mm and 10.0 mm.

[0035] In some examples, the upper gap (g U) and the lower gap (g L) can be adjusted before or during a process to increase the gap (g) between the upper working surface 125 and the lower working surface 120, and thus, increase the interior volume of the processing space 106, as shown in FIG. 1B. In other examples, the upper gap (g U) and the lower gap (g L) can be adjusted before or during a process to decrease the gap (g) between the upper working surface 125 and the lower working surface 120, and thus, decrease the interior volume of the processing space 106, as shown in FIG. 1C.

[0036] As shown in FIG. 1A, the bottom plate 110 has at least one opening 130 that passes through the lower working surface 120 of the processing chamber 105. When processing a substrate 50 mounted within the processing space 106, the at least one opening 130 passing through the lower working surface 120 may be in fluid flow communication with at least one processing fluid (e.g., a liquid and/or a gas), and may be configured to direct the at least one processing fluid into the processing space 106 above the lower working surface 120 for processing a bottom surface of the substrate 50.

[0037] In some examples, the at least one opening 130 passing through the lower working surface 120 includes one or more backside nozzles for dispensing a processing fluid into the processing space 106 above the lower working surface 120. In one example, the at least one opening 130 includes a backside nozzle, which is centered in the bottom plate 110 for dispensing the processing fluid into the processing space 106 near a center of the substrate 50, as shown in FIG. 1A. In some examples, the at least one opening 130 includes one or more auxiliary backside nozzles, which are positioned between the center of the bottom plate 110 and the edge of the substrate 50 for dispensing the processing fluid (or a different processing fluid) onto other areas of the substrate 50. Regardless of the number of backside nozzles utilized, the processing fluid(s) dispensed from the backside nozzle(s) is/are directed onto the bottom surface of the substrate 50 and thereafter flow radially towards the edge of the wafer. According to one substrate 50, the backside nozzle(s) may be coupled to a controller (such as controller 160) configured for selecting a first processing fluid (e.g., a liquid or a gas) that is introduced into the processing space.

[0038] The top plate 115 also includes at least one opening 135 that passes through the upper working surface 125 of the processing chamber 105. When processing a substrate 50 mounted within the processing space 106, the at least one opening 135 passing through the upper working surface 125 may be in fluid flow communication with at least one processing fluid (e.g., a liquid and/or a gas), and may be configured to direct the at least one processing fluid into the processing space 106 below the upper working surface 125 for processing a top surface of the substrate 50.

[0039] In some examples, the at least one opening 135 passing through the upper working surface 125 includes one or more frontside nozzles for dispensing the processing fluid into the processing space 106 below the upper working surface 125. In one example, the at least one opening 135 includes a frontside nozzle, which is centered in the top plate 115 for dispensing the processing fluid into the processing space 106 near a center of the substrate 50, as shown in FIG. 1A. The at least one opening 135 may include one or more auxiliary frontside nozzles, which are positioned between the center of the top plate 115 and the edge of the wafer for dispensing the processing fluid (or a different processing fluid) onto other areas of the wafer. Regardless of the number of frontside nozzles utilized, the processing fluid(s) dispensed from the frontside nozzle(s) is/are directed onto the top surface of the substrate 50 and thereafter flow radially towards the edge of the substrate 50. Similar to the backside nozzle(s), the frontside nozzle(s) may be coupled to a controller (such as controller 160) that is configured for selecting a second processing fluid (e.g., a liquid or a gas) that is introduced into the processing space.

[0040] Although FIG. 1A illustrates the at least one opening 130 as being through a midline of the bottom plate 110 and the at least one opening 135 as being through a midline of the top plate 115, any suitable number of openings 130 and 135 may be present in any suitable positions through the bottom plate 110, top plate 115, or through the drainage system 190.

[0041] In some examples, the processing system 100 shown in FIG. 1A is further configured for supercritical processing to be performed within the processing chamber 105. A first set of valves 200 is provided within the processing chamber 105 between the processing space 106 and the drainage system 190. The first set of valves 200 may be closed to seal processing fluid(s) within the processing space 106 or opened to allow the processing fluid(s) to drain out of the processing space through the conduits 195 contained within the drainage system 190. A second set of valves 202 is provided within the processing chamber 105 between gas inlets 204 and the conduits 195 contained within the drainage system 190. The gas inlets 204 are coupled to one or more sources of a pressurized gas, such as the one or more gases 150 and gas supply valves 155. The second set of valves 202 may be closed when injecting processing fluid(s) into the processing space 106 or opened to allow a gas (such as, e.g., air, nitrogen, carbon dioxide, or the like) injected into the gas inlets 204 to push any remaining processing fluid(s) through the conduits 195 and out of the drainage system 190.

[0042] According to one example, the processing system 100 shown in FIG. 1A is configured for wet processing a substrate 50 in the processing space 106. The wet processing can include introducing a first liquid into the processing space through the at least one opening 130 in the lower working surface 120, introducing a second liquid into the processing space through the at least one opening 135 in the upper working surface 125, or both. The first liquid and the second liquid may be the same liquid, or may be different liquids. In one example, the wet processing is a cleaning process where a top surface of the wafer, a bottom surface of the wafer, or both, are cleaned of residues and contaminants.

[0043] According to one example, the processing system 100 shown in FIG. 1A may be configured for dry processing a substrate 50 in the processing space 106. The dry processing can include introducing a first gas into the processing space through the at least one opening 130 in the lower working surface 120, introducing a second gas into the processing space through the at least one opening 135 in the upper working surface 125, or both. The first gas and the second gas may be the same gas, or may be different gases. In one example, the dry processing is a drying process where a top surface of the wafer, a bottom surface of the wafer, or both, are dried of liquids.

[0044] According to one example, the processing system 100 shown in FIG. 1A may be configured for wet processing, followed by dry processing, of a substrate 50 in the processing space 106. In one example, the wet processing may be a cleaning process where a top surface of the wafer, a bottom surface of the wafer, or both, are cleaned of residues and contaminants by injecting one or more liquids onto the wafer surface(s). The dry processing may be a drying process where a top surface of the wafer, a bottom surface of the wafer, or both, are dried by injecting one or more gases onto the wafer surface(s) to remove a liquid from the wafer surface(s).

[0045] According to one example, the substrate 50 is not rotated during wet or dry processing. According to another example, the processing system 100 comprises means for rotating the wafer (not shown) and the wafer is rotated during wet processing, dry processing or both wet and dry processing.

[0046] In some examples, the at least one opening 130 passing through the upper working surface 125 of the processing chamber 105 and the at least one opening 135 passing through the lower working surface 120 of the processing chamber 105 are in fluid flow communication with supply lines for one or more liquids 140 and liquid supply valves 145, as shown further in FIG. 1A. In other examples, the at least one opening 130 passing through the upper working surface 125 of the processing chamber 105 and the at least one opening 135 passing through the lower working surface 120 of the processing chamber 105 are also in fluid flow communication with supply lines for one or more gases 150 (e.g., nitrogen (N.sub.2), carbon dioxide (CO.sub.2), IPA vapor, air, or the like) and gas supply valves 155.

[0047] In some examples, the processing system 100 includes a controller 160 that is coupled to the liquid supply valves 145 and gas supply valves 155 for selectively providing the one or more liquids 140 and/or the one or more gases 150 to the processing space 106 defined within the processing chamber 105. A wide variety of liquids and gases may be selectively provided to the processing space 106 depending on the process, or process step, being performed within the processing chamber 105.

[0048] During a cleaning process, for example, the controller 160 may supply control signals to the liquid and gas supply valves 145/155 to selectively provide a cleaning solution and/or a rinse solution to the processing space 106 for cleaning and/or rinsing at least one surface of the substrate 50. Examples of cleaning solutions include, but are not limited to, an ammonia/peroxide mixture (APM), a hydrochloric/peroxide mixture (HPM) and a sulfuric peroxide mixture (SPM). Examples of rinse solutions include, but are not limited to, deionized (DI) water and isopropyl alcohol (IPA). Other cleaning solutions and rinse solutions may also be utilized. After cleaning and/or rinsing the surface(s) of the substrate 50, the controller 160 may supply control signals to the liquid and gas supply valves 145/155 to selectively provide a gas (such as, but not limited to, air, nitrogen, carbon dioxide, or the like) to the processing space 106 to remove any remaining liquid the wafer surface(s), thereby drying the wafer surface(s). The gas may be vented to outside the processing chamber through the openings 130, 135, or any other suitable opening or vent that couples the processing space 106 to the outside of the processing chamber 105.

[0049] In some examples, the controller 160 supplies control signals to the liquid and gas supply valves 145/155 to selectively provide a low surface tension liquid (such as IPA) to the processing space 106, before the cleaning step is performed, to pre-wet the wafer surface, as well as the upper working surface 125 and the lower working surface 120 of the processing chamber 105.

[0050] In some optional examples, the controller 160 (or another controller included within the processing system 100) may be configured to adjust a vertical position of the top plate 115, a vertical position of the bottom plate 110 and/or the gap (g) between the top and bottom plates. In the example shown in FIG. 1A, controller 160 is coupled to supply control signals to an optional lifting mechanism 170 coupled to the bottom plate 110 and an optional lifting mechanism 175 coupled to the top plate 115. The placement and configuration of the lifting mechanisms 170/175 is exemplary and provided herein merely for explanatory purposes.

[0051] The control signals supplied from the controller 160 to the lifting mechanisms 170/175 can be used to adjust a vertical position of the top plate 115 and/or a vertical position of the bottom plate 110. In some examples, for example, the controller 160 may supply a control signal to the lifting mechanism 175 to raise the top plate 115, so that a substrate 50 may be inserted with the processing space 106, as illustrated for example in FIG. 2. In other examples, the controller 160 may supply control signals to the lifting mechanisms 170/175 to adjust the upper gap (g U) between the upper working surface 125 of the processing chamber 105 and the top surface of the substrate 50 and/or to adjust the lower gap (g L) between the lower working surface 120 of the processing chamber 105 and the bottom surface of the substrate 50, as shown for example in FIGS. 1B and 1C. It is recognized that the controller 160 and the lifting mechanisms 170/175 represent only one means for adjusting the vertical position of the top plate 115, the vertical position of the bottom plate 110, and/or the gap (g) between the top and bottom plates. Other means for adjustment may also be used.

[0052] The upper gap (g U) and the lower gap (g L) can be adjusted for a wide variety of purposes. In some examples, the upper gap (g U) and the lower gap (g L) can be decreased, as shown in FIG. 1C, to decrease the interior volume of the processing space 106, increase the fluid velocity of the processing fluid(s) spreading radially across the wafer surface(s) and/or decrease the amount of processing fluid(s) needed to perform a particular process or process step. On the other hand, the upper gap (g U) and the lower gap (g L) can be increased, as shown in FIG. 1B, to increase the interior volume of the processing space 106, decrease the fluid velocity of the processing fluid(s) spreading radially across the wafer surface(s) and/or increase the amount of processing fluid(s) needed to perform a particular process or process step. In some examples, the upper gap (g U) and the lower gap (g L) can be adjusted together, or independently, for different processes (e.g., different cleaning processes), or different steps (e.g., cleaning and rinse steps) within the same process.

[0053] In some examples, additional feature(s) may be added to the top plate 115 and/or the bottom plate 110 of the processing chamber 105. For example, a sonic transducer may be added to the top plate 115 and/or the bottom plate 110 to enhance the wet (e.g., cleaning) process. The sonic transducer can be embedded within the entire top/bottom plate, or within only a portion of the top/bottom plate. In another example, the top plate 115 and/or the bottom plate 110 include one or more heating element(s) to control the temperature of the substrate 50 and heat the liquid/gas dispensed onto the surface of the substrate 50. The one or more heating element(s) may be used, such as in conjunction with pressurized gas through the gas inlets 204 and valves 202 or other suitable valves and inlets, to bring a fluid (e.g., liquid carbon dioxide) within the processing space 106 to a supercritical state. Alternatively, an additional nozzle may be embedded within the top plate 115 and/or the bottom plate 110 to inject steam into the processing space to heat the liquid/gas dispensed onto the wafer surface. In yet another example, the top plate 115 and/or the bottom plate 110 may include one or more sensors used to inspect the wafer and/or the liquids dispensed onto the wafer surface(s). For example, a conductive meter may be added to the top/bottom plate to monitor the liquids dispensed onto the wafer surface.

[0054] The processing system 100 illustrated by FIG. 1A further includes a drainage system 190 for directing processing fluids out of the processing chamber 105. According to one example, drainage system 190 contains a conduit 195 that is in fluid communication with, and downstream from, the processing space 106. The conduit 195 includes a first portion 192, which is coupled to the processing space 106 and positioned below the lower working surface 120 of the processing chamber 105. According to one example, the first portion 192 of the conduit 195 is implemented with a U-shape, as shown in FIG. 1A. A bottom of the U-shaped conduit is positioned below the lower working surface 120 of the processing chamber 105.

[0055] The processing system 100 and processing chamber 105 illustrated by FIGS. 1A, 1B, and 1C is included as a non-limiting example for illustrative purposes. Further examples of suitable processing chambers for embodiments of the current disclosure may be found in U.S. Patent Application No. 18/192,279, which is hereby incorporated by reference in its entirety. Any suitable processing system and processing chamber may be used to perform embodiments of the current disclosure, and all such methods using any suitable processing systems and processing chambers are within the scope of the disclosed embodiments.

[0056] FIGS. 2 through 10 illustrate cross-sectional views of intermediate stages of methods for cleaning a substrate using nitrogen gas to pressurize a processing chamber in preparation for treatment with a supercritical fluid, in accordance with some embodiments. Using nitrogen (N.sub.2) gas is pressurize the chamber above may be advantageous by allowing for more efficient use of the supercritical fluid.

[0057] FIG. 2 illustrates a cross-sectional view of a substrate 50. In various embodiments, the substrate 50 may be a part of, or including, a semiconductor device, and may have undergone a number of steps of processing following, for example, a conventional process. The substrate 50 accordingly may comprise layers of semiconductors and/or device regions useful in various microelectronics. In one or more embodiments, the substrate 50 is a silicon wafer or a silicon-on-insulator (SOI) wafer. In certain embodiments, the substrate 50 may comprise a silicon germanium wafer, silicon carbide wafer, gallium arsenide wafer, gallium nitride wafer or other compound semiconductor. In other embodiments, the substrate 50 comprises heterogeneous layers such as silicon germanium on silicon, gallium nitride on silicon, silicon carbon on silicon, or layers of silicon on a silicon or SOI substrate. In various embodiments, the substrate 50 is patterned or embedded in other components of the semiconductor device.

[0058] In FIG. 3, following from FIG. 2, a processing fluid 250 (also referred to as a rinsing fluid) is poured onto the substrate 50. In various embodiments, the processing fluid 250 is a cleaning solution and/or a rinse solution used for cleaning and/or rinsing at least one surface of the substrate 50, such as a low surface tension fluid (e.g., isopropyl alcohol (IPA), the like, or a combination thereof). In some embodiments, the processing fluid 250 may form a convex meniscus shape over the substrate 50. The processing fluid 250 may be delivered to the substrate 50 by any suitable apparatus, such as a spigot, showerhead, or the like. In some embodiments, the processing fluid 250 is supplied to the substrate 50 after the substrate 50 is put into a processing chamber (e.g., the processing chamber 105; see above, FIG. 1A).

[0059] FIGS. 4 through 10 illustrate cross-sectional views of a processing system (e.g., the example processing system 100), in accordance with some embodiments. FIGS. 4 and 5 illustrate the substrate 50 being inserted within a processing space 106 and supported substantially parallel to the upper and lower working surfaces of the enclosed processing chamber 105.

[0060] As illustrated in FIG. 4, a control signal is supplied to the lifting mechanism 175 to raise the top plate 115, enabling the substrate 50 to be inserted into the processing space 106 formed between the bottom plate 110 and the top plate 115 of the processing chamber 105. However, the substrate 50 may be inserted into the processing space 106 by any suitable process. Once inserted, the substrate 50 is supported substantially parallel to the upper working surface 125 and the lower working surface 120 of the processing chamber 105. The processing fluid 250 may be over the top surface of the substrate 50 while the substrate is inserted into the processing space 106.

[0061] Next, in FIG. 5, the substrate 50 is supported on a plurality of pins 123, which extend from the lower working surface 120 of the enclosed processing chamber 105 to support the substrate 50 from the bottom of the substrate 50. In other embodiments, the substrate 50 may be supported by a plurality of pins 123 that support the substrate 50 by contacting the edge of the substrate 50.

[0062] After the substrate 50 is inserted within the processing space 106 and mounted on the plurality of pins 123, a control signal may be supplied to the lifting mechanism 175 to lower the top plate 115 and enclose the processing chamber 105. In some optional embodiments, additional control signals may be supplied to the lifting mechanisms 170/175 to adjust the upper gap (g U) between the upper working surface 125 of the processing chamber 105 and the top surface of the wafer and the lower gap (g L) between the lower working surface 120 of the processing chamber 105 and the bottom surface of the wafer. In some embodiments, the processing fluid 250 remains over the top surface of the substrate 50, such as in a convex meniscus shape.

[0063] In various embodiments, the substrate 50 is not treated with the processing fluid 250 prior to being inserted into the processing space 106. Rather, the processing fluid 250 is injected into the processing space 106 after the substrate 50 is inserted into the processing space 106, and the processing fluid 250 may fill the processing space 106, thereby covering top and bottom surfaces of the substrate 50. As such, the processing chamber 105 and supply lines may all filled with liquid with no gas presence and therefore no meniscus. This may provide the advantage of single chamber processing with the processing fluid 250 and one or more subsequent drying steps, which may be useful for increasing throughput and efficiency and thereby reducing costs. Additionally, excessive processing fluid (e.g., IPA) mixed with gas from a dry or supercritical fluid (e.g., CO.sub.2) can negatively affect the pressures and temperatures desirable to reach and maintain a supercritical state. As such, it may be advantageous to keep the processing chamber 105 filled with liquid until a supercritical stage.

[0064] In FIG. 6, following from FIG. 5, the processing space 106 is pressurized with nitrogen (N.sub.2) gas 255. In various embodiments, the N.sub.2 gas 255 is provided through the gas inlets 204 and valves 202. However, the N.sub.2 gas 255 may be provided to pressurize the processing space 106 through any suitable inlets and/or valves. In some embodiments, the processing space 106 is pressurized to a pressure above 5 MPa.

[0065] In some embodiments, the N.sub.2 gas 255 is used to pressurize the processing space 106 to allow a supercritical fluid (e.g., supercritical CO.sub.2; see below, FIG. 7) to be added to the processing space 106. For example, the pressure in the processing space 106 may be increased to 7 MPa or above using the pressurized N.sub.2 gas 255, such as 7.38 MPa or above. In embodiments where the processing chamber 105 is filled with a liquid such as the processing fluid 250, the liquid may be minimally compressed so that only a small volume of pressurized N.sub.2 gas 255 is needed.

[0066] Using nitrogen (N.sub.2) gas to pressurize the chamber above 7 MPa instead of CO.sub.2 may be advantageous by allowing for more efficient use of supercritical CO.sub.2 and thus reducing the amount of CO.sub.2, which can be beneficial for reducing costs and environmental impact. For example, CO.sub.2 is a greenhouse gas, while N.sub.2 is not a greenhouse gas; in fact, N.sub.2 is more prevalent in the atmosphere and can be isolated and provided as a gas supply at a lower cost. CO.sub.2 feed stock is hydrocarbon or ammonia based, while the feed stock for N.sub.2 is atmospheric air, allowing for onsite production on demand, which can further reduce cost. High purity N.sub.2 cylinders and tanks are usually charged to a higher pressure (23.6 MPa) as compared to CO.sub.2 (5.9 MPa) which may be better suited to this specific use case due to the pressure required. N.sub.2 chamber pressurization with the chamber filled with a liquid (e.g., liquid CO.sub.2), which, unlike a gas, is minimally compressible, can be performed with only a small amount of N.sub.2. As such, facility delivered N.sub.2 is a viable option for this method. Furthermore, N.sub.2 pressurization can be done in the supply line, if properly configured, so that the N.sub.2 remains outside the processing chamber 105. In some embodiments, this supply line is then be valved off and vented independently of the chamber so that the introduction of N.sub.2 to the processing chamber 105 may be greatly limited. This may be advantageous because excess N.sub.2 and other chemistries such as IPA, when mixed with the CO.sub.2, environment can affect the temperature and pressures for reaching and maintaining a supercritical state.

[0067] In some embodiments, the temperature in the processing space 106 is increased to 30.98 C or above, such as one or more heating element(s) of the top plate 115 and/or the bottom plate 110, as described above with respect to FIG. 1A. However, any suitable methods or mechanisms may be used to adjust the temperature in the processing chamber 105 to allow for supercritical fluid to be subsequently added.

[0068] Next, in FIG. 7, a supercritical fluid 260 is dispensed into the processing space 106. In various embodiments, the supercritical fluid 260 is a cryogenic liquid for a dry process such as liquid carbon dioxide (CO.sub.2), the like, or a combination thereof. The supercritical fluid 260 may be injected into the processing chamber 105 through, for example, the at least one openings 130/135. However, the supercritical fluid 260 may be injected into the processing chamber 105 through any suitable inlets. The supercritical fluid 260 (e.g., liquid CO.sub.2) may have a lower surface tension than the processing fluid 250 (e.g., IPA), which may reduce the risk of pattern collapse on the substrate.

[0069] In embodiments in which the processing chamber 105 is filled with the processing fluid 250 as described above with respect to FIG. 5, N.sub.2 gas 255 may be used to pressurize the liquid environment (see above, FIG. 6) so that when a supercritical fluid 260 or a dry fluid 258 (see below, FIG. 11) is delivered into the processing chamber 105, the supercritical fluid 260 or dry fluid 258 remains in a liquid (or supercritical liquid) state. As such, a boundary may be present between the processing fluid 250 and the supercritical fluid 260 or dry fluid 258, but the miscibility of these liquids may prevent a detrimental meniscus from forming between them. This may advantageously reduce or prevent damage to structures of the processing system 100 (e.g., in supply lines or valves) or fine structures on the substrate 50 by detrimental meniscuses. For example, an area of exposure to N.sub.2 gas 255 in the supply line may be valved off and purged with supercritical fluid 260 or dry fluid 258. The valve may then be opened to the processing chamber 105 and the supercritical fluid 260 or dry fluid 258 may be used to push the processing fluid 250 out of the processing chamber 105, as described below. As such, a bulk of the processing fluid 250 may be eliminated from the processing chamber 105 by displacing it with supercritical fluid 260 or dry fluid 258. Since the processing chamber 105 is always filled with fluid, there is not a meniscus of processing fluid 250 with air that might collapse fine features on the substrate 50. Residual amounts of processing fluid 250 remaining in the processing chamber 105 may be much lower than in the processing fluid 250 puddle process previously described above with respect to FIGS. 2-4. This may lower the overall operating pressure desirable for achieving a supercritical state, thereby decreasing the amount of dry fluid (e.g., CO.sub.2) used to complete the process.

[0070] While the supercritical fluid 260 is injected into the processing chamber 105, the processing fluid 250 may be drained from the processing chamber 105, such as through the conduits 195 of the drainage system 190. The processing fluid 250 may be recovered and reused. This is advantageous for recycling the processing fluid 250 and thereby saving costs. Removing the rinsing fluid (e.g., IPA) without bringing it to a supercritical state (also referred to as a supercritical condition) may allow the processing chamber to operate at lower pressures, thereby reducing cost.

[0071] In FIG. 8, following from FIG. 7, the supercritical fluid 260 fills the processing space 106 of the processing chamber 105 after the processing fluid 250 has been removed. The supercritical fluid 260 may have a lower surface tension than the processing fluid 250 (e.g., IPA), which may reduce the risk of pattern collapse on the substrate 50. For example, liquid CO.sub.2 has a surface tension of 1.37 mN/m at 20 C and 0.59 mN/m at 25 C. Using a supercritical fluid to treat the substrate 50 may be advantageous to improve substrate drying and avoiding pattern collapse that sometimes occurs when using a processing fluid (e.g., IPA) to dry substrate surfaces. Since supercritical fluids have zero surface tension, pattern collapse may not occur when the wafer is dried in a supercritical fluid environment. The supercritical dry process may allow for uniform clearing of the processing chamber 105 after processing. In some embodiments, the processing space 106 is filled with a dry fluid 258 (see below, FIG. 11) that is subsequently brought to a supercritical state by heating the processing chamber 105.

[0072] Next, in FIG. 9, the processing chamber 105 is depressurized and the supercritical fluid 260 is vented out (in other words, released from the processing chamber) in a gaseous phase. In other words, the supercritical fluid 260 (e.g., supercritical CO.sub.2) undergoes a phase transition to a gas 270 (e.g., gaseous CO.sub.2). The processing chamber 105 may be lowered in pressure in a controlled fashion allowing for a transition from, for example, supercritical to gas phase CO.sub.2, reducing or eliminating the possibility of pattern collapse on the substrate 50. The gas 270 is then vented outside of the processing chamber 105, such as through the open valves 202. However, any valves and/or gas outlets may be used to vent the gas 270 out of the processing chamber 105, such as the one or more openings 130/135.

[0073] In FIG. 10, following from FIG. 9, the gas 270 has exited the processing chamber 105 and the process on the substrate 50 is complete. In some embodiments, the substrate 50 is then be removed from the processing chamber 105. In other embodiments, additional liquids and/or gases may be injected into the processing chamber 105 in order to perform additional wet and/or dry processes on the substrate 50.

[0074] Embodiments of a method for cleaning a substrate using nitrogen gas to pressurize a processing chamber in preparation for a drying process with a dry fluid (e.g., liquid CO.sub.2) are described using FIG. 11. Displacing a processing fluid (e.g., IPA) with the dry fluid allows for recovery and recycling of the processing fluid, further enhancing process efficiency. The dry fluid drying method may operate at lower pressures (e.g., around 5 MPa) and at room temperature (e.g., around 25 C), potentially increasing throughput and reducing equipment costs. The lower surface tension of the dry fluid (e.g., liquid CO.sub.2) compared to the processing fluid (e.g., IPA) may reduce the risk of pattern collapse in delicate semiconductor structures.

[0075] FIG. 11 illustrates a cross-sectional view of the processing system 100 following from FIG. 6, in which a substrate 50 covered by a processing fluid 250 is in a processing space 106 which has been pressurized with nitrogen (N.sub.2) gas 255 to a pressure sufficient to maintain a liquid state of a dry fluid (e.g., liquid CO.sub.2), such as a pressure in a range of 4.5 MPa to 6.5 MPa, or 4.5 MPa to 5.5 MPa, or a pressure above 5 MPa. In some embodiments, the temperature in the processing space is kept at room temperature, such as around or at 25 C.

[0076] Next, a dry fluid 258 is dispensed into the processing space 106. In various embodiments, the dry fluid 258 is a cryogenic liquid for a dry process such as liquid carbon dioxide (CO.sub.2), the like, or a combination thereof. The dry fluid 258 may be injected into the processing chamber 105 through, for example, the at least one openings 130/135. However, the dry fluid 258 may be injected into the processing chamber 105 through any suitable inlets. The dry fluid 258 (e.g., liquid CO.sub.2) may have a lower surface tension than the processing fluid 250 (e.g., IPA), which may reduce the risk of pattern collapse on the substrate.

[0077] The dry fluid 258 may be added to the processing chamber 105 at a temperature that supports liquid CO.sub.2, such as under supercritical temperature, for example in a range of -56.4 C to 31.1 C, and under a pressure sufficient to support a liquid CO.sub.2 state at -56.4 C, for example in a range of 0.52 MPa (or a minimum pressure to support a liquid CO.sub.2 state at -56.4 C) to 7.38 MPa (or a maximum pressure to support a liquid CO.sub.2 state at 31.1 C). However, temperature and/or pressure may exceed this range (such as a temperature above 31.1 C) so that the dry fluid 258 enters a supercritical state while being used to fill the processing chamber 105 and push out the processing fluid 250. Injecting the dry fluid 258 at a lower pressure (e.g., less than a pressure needed for the processing fluid 250, such as IPA, to be supercritical) and at a lower temperature (e.g., room temperature) may be advantageous by increasing throughput. Removing the processing fluid 250 (e.g., IPA) without bringing it to a supercritical state may allow the processing chamber 105 to operate at lower pressures, thereby reducing cost. For example, liquid CO.sub.2 at room temperature (e.g., around 25 C) needs to be at a pressure above 4.5 MPa, while IPA does not reach a supercritical state until 235.6 C at 5.37 MPa. By inserting the dry fluid 258 without bringing it to a supercritical state, the pressure in the processing chamber 105 may be kept at 5 MPa or less, such as in a range of 4.5 MPa to 5 MPa, while adding the dry fluid 258 and recovering the processing fluid 250, thereby allowing the processing chamber 105 to have a lower tolerance for high pressures. As tolerances may be, for example, three times the desired pressure, the processing chamber 105 could have a tolerance of 15 MPa, which could reduce costs.

[0078] While the dry fluid 258 is injected into the processing chamber 105, the processing fluid 250 may be drained from the processing chamber 105, such as through the conduits 195 of the drainage system 190. The processing fluid 250 may be recovered and reused. This is advantageous for recycling the processing fluid 250 and thereby saving costs. Removing the rinsing fluid (e.g., IPA) without bringing it to a supercritical state (also referred to as a supercritical condition) may allow the processing chamber to operate at lower pressures, thereby reducing cost.

[0079] After the substrate 50 is treated with the dry fluid 258, the processing chamber 105 may be depressurized and the dry fluid 258 may be vented out (in other words, released from the processing chamber) in a gaseous phase. In some embodiments, the dry fluid 258 is removed without reaching a supercritical condition. Removing the dry fluid 258 may be performed as described above with respect to FIG. 9 and the details are not repeated herein. The substrate 50 may then be removed from the processing chamber 105. This may be performed as described above with respect to FIG. 10 and the details are not repeated herein.

[0080] Embodiments of a method for cleaning a substrate using nitrogen gas to pressurize a processing chamber to bring a dry fluid (e.g., liquid CO.sub.2) to a supercritical condition are described using FIG. 12. Using the dry fluid liquid to displace a processing fluid (e.g., IPA) on the substrate followed by pressurization to supercritical conditions using N.sub.2 may be advantageous for reducing dry fluid consumption in the supercritical process, leading to cost savings and reduced environmental impact.

[0081] FIG. 12 illustrates a cross-sectional view of the processing system 100 following from FIG. 11, in which the processing fluid 250 has been removed (such as for recovery and recycling) and the dry fluid 258 is brought to a supercritical condition by further pressurizing the processing space 106 with N.sub.2 gas. The processing space 106 may be brought to a pressure sufficient to bring the dry fluid 258 to a supercritical state and become a supercritical fluid 260 using similar methods as described above with respect to FIG. 6, and the details are not repeated herein.

[0082] After the substrate 50 is treated with the supercritical fluid 260, the processing chamber 105 may be depressurized and the supercritical fluid 260 may be vented out (in other words, released from the processing chamber) in a gaseous phase. This may be performed as described above with respect to FIG. 9 and the details are not repeated herein. The substrate 50 may then be removed from the processing chamber 105. This may be performed as described above with respect to FIG. 10 and the details are not repeated herein.

[0083] Embodiments of a method for substrate cleaning using a processing vapor (e.g., IPA vapor) during chamber pressurization are described using FIGS. 13 through 15. Dispensing processing vapor during chamber pressurization may be advantageous by saturating the environment and reducing processing fluid (e.g., IPA) evaporation from the substrate. This may be useful for maintaining consistent processing fluid coverage on the wafer, potentially improving cleaning efficacy.

[0084] FIG. 13 illustrates a cross-sectional view of the processing system 100 following from FIG. 5, in which the processing space 106 is pressurized with a gas 254 (e.g., carbon dioxide (CO.sub.2)) while processing vapor 252 (e.g., IPA vapor) is also dispensed into the processing space 106. As illustrated by FIG. 13, the processing vapor 252 is provided through a left gas inlet 204 and valve 202 and the CO.sub.2 gas 254 is provided through a right gas inlet 204 and valve 202. However, the processing vapor 252 and gas 254 may be provided through any suitable inlets and/or valves. The processing vapor 252 is dispensed into the processing space 106 while it is pressurized to supercritical pressures in order to reduce evaporation from the processing fluid 250 (e.g., liquid IPA) on the substrate 50. In some embodiments, the pressure in the processing space 106 is increased to 7 MPa or above using the pressurized gas 254, such as 7.38 MPa or above, and the temperature in the processing space 106 is increased to 31.1 C or above, such as with one or more heating element(s) of the top plate 115 and/or the bottom plate 110, as described above with respect to FIG. 1A in order to sustain supercriticality in a subsequently provided supercritical fluid (see below, FIG. 14). However, any suitable methods or mechanisms may be used to adjust the temperature in the processing chamber 105 to allow for supercritical fluid to be subsequently added.

[0085] Next, in FIG. 14, a supercritical fluid 260 is dispensed into the processing space 106. In various embodiments, the supercritical fluid 260 is a cryogenic liquid for a dry process such as liquid carbon dioxide (CO.sub.2), the like, or a combination thereof. In some embodiments, the gas 254 and the supercritical fluid 260 are a same substance (e.g., carbon dioxide (CO.sub.2) or the like). The supercritical fluid 260 may be injected into the processing chamber 105 through, for example, the at least one openings 130/135. However, the supercritical fluid 260 may be injected into the processing chamber 105 through any suitable inlets. The supercritical fluid 260 (e.g., liquid CO.sub.2) may have a lower surface tension than the processing fluid 250 (e.g., IPA), which may reduce the risk of pattern collapse on the substrate.

[0086] While the supercritical fluid 260 is injected into the processing chamber 105, the processing fluid 250 may be drained from the processing chamber 105, such as through the conduits 195 of the drainage system 190. The processing fluid 250 may be recovered and reused. This is advantageous for recycling the processing fluid 250 and thereby saving costs. Removing the rinsing fluid (e.g., IPA) without bringing it to a supercritical state (also referred to as a supercritical condition) may allow the processing chamber to operate at lower pressures, thereby reducing cost.

[0087] In FIG. 15, following from FIG. 14, the supercritical fluid 260 fills the processing space 106 of the processing chamber 105 after the processing fluid 250 has been removed. The supercritical fluid 260 may have a lower surface tension than the processing fluid 250 (e.g., IPA), which may reduce the risk of pattern collapse on the substrate 50. For example, liquid CO.sub.2 has a surface tension of 1.37 mN/m at 20 C and 0.59 mN/m at 25 C. Using a supercritical fluid to treat the substrate 50 may be advantageous to improve substrate drying and avoiding pattern collapse that sometimes occurs when using a processing fluid (e.g., IPA) to dry substrate surfaces. Since supercritical fluids have zero surface tension, pattern collapse may not occur when the wafer is dried in a supercritical fluid environment. The supercritical dry process may allow for uniform clearing of the processing chamber 105 after processing.

[0088] After the substrate 50 is treated with the supercritical fluid 260, the processing chamber 105 may be depressurized and the supercritical fluid 260 may be vented out (in other words, released from the processing chamber) in a gaseous phase. This may be performed as described above with respect to FIG. 9 and the details are not repeated herein. The substrate 50 may then be removed from the processing chamber 105. This may be performed as described above with respect to FIG. 10 and the details are not repeated herein.

[0089] FIG. 16 illustrates a process flow chart diagram of a method 800 for processing a substrate, in accordance with some embodiments. In step 802, isopropyl alcohol (IPA) is dispensed onto the substrate, as described above with respect to FIG. 3. In step 804, the substrate is provided into a processing chamber, as described above with respect to FIG. 4. In step 806, the processing chamber is pressurized to a pressure above 5 MPa, as described above with respect to FIG. 6. In step 808, the IPA on the substrate is removed by displacing the IPA with liquid carbon dioxide (CO.sub.2), as described above with respect to FIG. 11. In step 810, the liquid CO.sub.2 is removed as gaseous CO.sub.2 by venting the processing chamber, as described above with respect to FIG. 9.

[0090] FIG. 17 illustrates a process flow chart diagram of a method 900 for processing a substrate, in accordance with some embodiments. In step 902, a substrate is provided into a processing chamber, as described above with respect to FIG. 4. In step 904, isopropyl alcohol (IPA) is dispensed onto the substrate, as described above with respect to FIG. 5. In step 906, the processing chamber is pressurized with nitrogen (N.sub.2) gas to a pressure above 7 MPa, as described above with respect to FIG. 6. In step 908, the IPA on the substrate is removed by displacing the IPA with supercritical carbon dioxide (CO.sub.2), as described above with respect to FIG. 7. In step 910, the supercritical CO.sub.2 is removed as gaseous CO.sub.2 by venting the processing chamber, as described above with respect to FIG. 9.

[0091] FIG. 18 illustrates a process flow chart diagram of a method 1000 for processing a substrate, in accordance with some embodiments. In step 1002, isopropyl alcohol (IPA) is dispensed onto the substrate, as described above with respect to FIG. 3. In step 1004, the substrate is provided into a processing chamber, as described above with respect to FIG. 4. In step 1006, the processing chamber is pressurized with carbon dioxide (CO.sub.2) gas to a supercritical pressure while dispensing IPA vapor into the processing chamber, as described above with respect to FIG. 13. In step 1008, the IPA on the substrate is removed by displacing the IPA with supercritical carbon dioxide (CO.sub.2), as described above with respect to FIG. 14. In step 1010, the supercritical CO.sub.2 is removed as gaseous CO.sub.2 by venting the processing chamber, as described above with respect to FIG. 9.

[0092] Example embodiments of the invention are described below. Other embodiments can also be understood from the entirety of the specification as well as the claims filed herein.

[0093] Example 1. A method for processing a substrate, the method including: dispensing isopropyl alcohol (IPA) onto the substrate; providing the substrate into a processing chamber; pressurizing the processing chamber to a pressure above 5 MPa; removing the IPA on the substrate by displacing the IPA with liquid carbon dioxide (CO.sub.2); and removing the liquid CO.sub.2 as gaseous CO.sub.2 by venting the processing chamber.

[0094] Example 2. The method of example 1, further including recycling the IPA after removing it from the substrate.

[0095] Example 3. The method of one of examples 1 or 2, further including further pressurizing the processing chamber with N.sub.2 gas to a pressure above 7 MPa after removing the IPA.

[0096] Example 4. The method of example 3, where pressurizing the processing chamber with N.sub.2 gas to a pressure above 7 MPa brings the liquid CO.sub.2 to a supercritical state.

[0097] Example 5. The method of one of examples 1 to 4, where pressurizing the processing chamber to a pressure above 5 MPa is performed with nitrogen (N.sub.2) gas.

[0098] Example 6. The method of one of examples 1 or 2, where pressurizing the processing chamber to a pressure above 5 MPa is performed with CO.sub.2 gas and IPA vapor.

[0099] Example 7. The method of one of examples 1, 2, or 6, where the processing chamber is pressurized to a pressure above 7 MPa with CO.sub.2 gas and IPA vapor.

[0100] Example 8. The method of one of examples 1 to 7, where the processing chamber is at room temperature while displacing the IPA with liquid CO.sub.2.

[0101] Example 9. The method of one of examples 1 to 3, 5, 6, or 8, where the liquid CO.sub.2 is removed without reaching a supercritical condition.

[0102] Example 10. A method for processing a substrate, the method including: providing the substrate into a processing chamber; dispensing isopropyl alcohol (IPA) onto the substrate; pressurizing the processing chamber with nitrogen (N.sub.2) gas to a pressure above 7 MPa; removing the IPA on the substrate by displacing the IPA with supercritical carbon dioxide (CO.sub.2); and removing the supercritical CO.sub.2 as gaseous CO.sub.2 by venting the processing chamber.

[0103] Example 11. The method of example 10, further including recycling the IPA after removing it from the processing chamber.

[0104] Example 12. The method of one of examples 10 or 11, further including injecting liquid CO.sub.2 into the processing chamber before pressurizing the processing chamber with N.sub.2 gas to a pressure above 7 MPa.

[0105] Example 13. The method of example 12, further including pressurizing the processing chamber with N.sub.2 gas to a pressure in a range of 4.5 MPa to 5.5 MPa before injecting liquid CO.sub.2 into the processing chamber.

[0106] Example 14. The method of one of examples 12 or 13, where the processing chamber is maintained at room temperature while injecting liquid CO.sub.2 into the processing chamber.

[0107] Example 15. A method for processing a substrate, the method including: dispensing isopropyl alcohol (IPA) onto the substrate; providing the substrate into a processing chamber; pressurizing the processing chamber with carbon dioxide (CO.sub.2) gas to a supercritical pressure while dispensing IPA vapor into the processing chamber; removing the IPA on the substrate by displacing the IPA with supercritical carbon dioxide (CO.sub.2); and removing the supercritical CO.sub.2 as gaseous CO.sub.2 by venting the processing chamber.

[0108] Example 16. The method of example 15, further including removing the IPA from the processing chamber after removing the IPA from the substrate.

[0109] Example 17. The method of example 16, further including recycling the IPA after removing the IPA from the processing chamber.

[0110] Example 18. The method of one of examples 15 to 17, where IPA is dispensed onto the substrate before providing the substrate into the processing chamber.

[0111] Example 19. The method of one of examples 15 to 17, where the substrate is provided into the processing chamber before dispensing IPA onto the substrate.

[0112] Example 20. The method of one of examples 15 to 19, where pressurizing the processing chamber with CO.sub.2 gas to a supercritical pressure includes pressurizing the processing chamber to a pressure of 7 MPa or above.

[0113] While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.