EDGE ZONE COATING REMOVAL WITH WARPAGE COMPENSATION

Abstract

An apparatus to remove at least a portion of a coating from a coated surface of a substrate may include a nozzle assembly and one or more nozzle-heads. Each nozzle-head may include at least one nozzle tip and a cavity configured to receive a portion of the coated surface of the substrate. The nozzle tip may be configured to direct an angled stream of an etchant on the substrate as the nozzle assembly moves along the length of the substrate. One or more sensors may measure a warpage of the substrate along the length of the substrate, and a controller may move the nozzle-head orthogonal to the direction of nozzle-head movement based on the measured warpage.

Claims

1. An apparatus to remove at least a portion of a coating from a coated surface of a substrate, comprising: a nozzle assembly configured to travel in a first direction along a length of the substrate, the nozzle assembly including one or more nozzle-heads, wherein each nozzle-head of the one or more nozzle-heads includes, a body having a cavity, the cavity being configured to receive at least a portion of the coated surface of the substrate therein; and at least one nozzle tip supported on the body and inclined at an obtuse angle with respect to the coated surface of the substrate received in the cavity, wherein the at least one nozzle tip is configured to direct an angled stream of an etchant to impinge on the coated surface of the substrate received in the cavity as the nozzle assembly travels in the first direction along the length of the substrate; one or more sensors configured to measure a warpage of the substrate along at least a portion of the length of the substrate; and a controller configured to move at least one nozzle-head of the one or more nozzle-heads in a second direction orthogonal to the first direction based on the measured warpage as the nozzle assembly travels in the first direction with the angled stream of the etchant impinging on the coated surface of the substrate received in the cavity.

2. The apparatus of claim 1, wherein the at least one nozzle tip is inclined at an angle between 40-50 degrees with respect to the coated surface of the substrate.

3. The apparatus of claim 1, wherein the one or more sensors are configured to measure the warpage of the substrate as the nozzle assembly travels in the first direction with the angled stream of the etchant impinging on the coated surface of the substrate.

4. The apparatus of claim 1, wherein the controller is configured to continuously move the at least one nozzle-head in the second direction as the nozzle assembly travels in the first direction.

5. The apparatus of claim 1, wherein the one or more sensors include a pair of sensors positioned on opposite sides of the substrate, wherein the pair of sensors are collectively configured to measure a variation in thickness of the substrate along at least the portion of the length of the substrate.

6. The apparatus of claim 5, wherein the controller is further configured to move the at least one nozzle-head in a third direction orthogonal to the first direction and the second direction based on the measured variation in thickness of the substrate as the nozzle assembly travels in the first direction with the angled stream of the etchant impinging on the coated surface of the substrate.

7. The apparatus of claim 1, wherein the at least one nozzle tip includes a pair of nozzle tips configured to direct angled streams of the etchant to impinge on opposite sides of the substrate received in the cavity.

8. The apparatus of claim 1, wherein the one or more sensors are positioned ahead of the nozzle assembly in the first direction.

9. The apparatus of claim 1, wherein the one or more sensors extend from the nozzle assembly in a third direction orthogonal to the first direction and the second direction.

10. The apparatus of claim 1, wherein the nozzle assembly further includes an annular duct defined around the at least one nozzle tip, wherein the annular duct is configured to discharge a pressurized gas to form a gas shroud around the angled stream of the etchant impinging on the coated surface.

11. The apparatus of claim 1, wherein the nozzle assembly further includes a suction cup coupled to a vacuum pump, wherein the suction cup is positioned within the cavity and configured to extract the etchant impinging on the coated surface from the nozzle assembly.

12. The apparatus of claim 1, wherein the one or more nozzle-heads of the nozzle assembly includes multiple nozzle-heads stacked in the first direction.

13. The apparatus of claim 12, wherein the controller is configured to move at least one nozzle-head of the multiple nozzle-heads in the second direction independent of another nozzle-head of the multiple nozzle-heads.

14. A method of etching a coating from an edge of a coated surface of a substrate, comprising: measuring warpage of the substrate along a length of the substrate; positioning the edge of the coated surface of the substrate in a cavity of a nozzle assembly, wherein the nozzle assembly includes one or more nozzle-heads with each nozzle head of the one or more nozzle-heads including at least one nozzle tip inclined at an obtuse angle with respect to the coated surface positioned in the cavity; moving the nozzle assembly in a first direction along the length of the substrate with the at least one nozzle tip directing an angled stream of an etchant to impinge on the coated surface positioned in the cavity to etch the coating on the coated surface along the length of the substrate; and moving at least one nozzle-head of the one or more nozzle-heads in a second direction orthogonal to the first direction based on the measured warpage while etching the coating along the length of the substrate.

15. The method of claim 14, wherein measuring the warpage occurs while the at least one nozzle tip is discharging etchant to etch the coating.

16. The method of claim 14, further including moving the nozzle assembly in the first direction along the length of the substrate to measure the warpage of the substrate while the at least one nozzle tip is not discharging etchant.

17. The method of claim 14, wherein measuring the warpage of the substrate along the length of the substrate includes measuring a variation in thickness of the substrate along the length of the substrate, and the method further includes moving the at least one nozzle-head in a third direction orthogonal to the first direction and the second direction based on the measured variation in thickness of the substrate while etching the coating along the length of the substrate.

18. The method of claim 14, wherein moving the at least one nozzle-head in the second direction includes continuously moving the at least one nozzle-head in the second direction while etching the coating along the length of the substrate.

19. The method of claim 14, wherein the one or more nozzle-heads of the nozzle assembly includes multiple nozzle-heads stacked in the first direction, and wherein moving the at least one nozzle-head in the second direction includes moving a first nozzle-head of the multiple nozzle-heads in the second direction independent of a second nozzle-head of the multiple nozzle-heads.

20. The method of claim 14, wherein the at least one nozzle tip includes a pair of nozzle tips positioned on opposite sides of the substrate positioned in the cavity, and wherein moving the nozzle assembly in the first direction includes the pair of nozzle tips simultaneously directing angled streams of the etchant to impinge on opposite surfaces of substrate positioned in the cavity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings, which are incorporated herein and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, are used to explain the disclosed principles. In these drawings, where appropriate, reference numerals that illustrate the same or similar structures, components, materials, and/or elements in different figures are labeled similarly. It is understood that various combinations of the structures, components, and/or elements, other than those specifically shown, are contemplated and are within the scope of the present disclosure.

[0011] For simplicity and clarity of illustration, the figures depict the general structure of the various described embodiments. Details of well-known components or features may be omitted to avoid obscuring other features, since these omitted features are well-known to those of ordinary skill in the art. Further, features in the figures are not necessarily drawn to scale. The dimensions of some features may be exaggerated relative to other features to improve understanding of the exemplary embodiments. One skilled in the art would appreciate that the features in the figures are not necessarily drawn to scale and, unless indicated otherwise, should not be viewed as representing dimensions or proportional relationships between different features in a figure. Additionally, even if it is not expressly mentioned, aspects described with reference to one embodiment or figure may also be applicable to, and may be used with, other embodiments or figures.

[0012] FIG. 1A is a schematic illustration of a top view of an exemplary coated substrate;

[0013] FIG. 1B is a depiction of the non-linearity of the edge of an etched coating in the substrate of FIG. 1A;

[0014] FIG. 1C is a schematic illustration of a side view of the exemplary coated substrate of FIG. 1A;

[0015] FIG. 2A is a perspective view of an exemplary apparatus having a multi-head nozzle assembly that may be used to etch the coating at a keep-out-zone of the substrate of FIG. 1A;

[0016] FIG. 2B is a perspective view of a single nozzle-head of the nozzle assembly of FIG. 2A, consistent with some embodiments of the current disclosure;

[0017] FIG. 2C is a cross-sectional side view of the single nozzle-head of FIG. 2B, consistent with some embodiments of the current disclosure;

[0018] FIGS. 3A-3C are schematic illustrations of exemplary nozzle-heads, consistent with some embodiments of the current disclosure;

[0019] FIGS. 4A-4B are side views of exemplary coated substrates, consistent with some embodiments of the current disclosure;

[0020] FIGS. 5A-5C are schematic illustrations of Z-axis compensation of nozzle-heads, consistent with some embodiments of the current disclosure;

[0021] FIGS. 6A-6B are schematic illustrations showing the effect of thickness variation of the coated substrate on edge non-linearity;

[0022] FIG. 7-9B are illustrations of exemplary apparatus that may be used to etch the coated substrate of FIG. 1A, consistent with some embodiments of the current disclosure; and

[0023] FIG. 10 is a flow chart illustrating an exemplary method of using an apparatus of the current disclosure, consistent with some embodiments of the current disclosure.

DETAILED DESCRIPTION

[0024] All relative terms such as about, substantially, approximately, etc., indicate a possible variation of 10% (unless noted otherwise or another degree of variation is specified). In some cases, the specification also provides context to some of the relative terms used. For example, a coating edge (or another feature) described as being substantially linear means that, the edge may not be perfectly linear due to possible practical imperfections and part-part variations, but the coating edge follows a mostly straight or nearly straight path. For instance, a coating edge that is substantially linear may have some deviations or fluctuations from a perfectly straight line, but the overall trend of the edge will be predominantly linear. In other words, edge may follow a general linear pattern, although there could be some variability present. Further, a range described as varying from, or between, 5 to 10 (5-10), includes the endpoints (i.e., 5 and 10).

[0025] Unless otherwise defined, all terms of art, notations, and other scientific terms or terminology used herein have the same meaning as commonly understood by persons of ordinary skill in the art to which this disclosure belongs. Some components, structures, and/or processes described or referenced herein are well understood and commonly employed using conventional methodology by those skilled in the art. These components, structures, and processes will not be described in detail. All patents, applications, published applications and other publications referred to herein as being incorporated by reference are incorporated by reference in their entirety. If a definition or description set forth in this disclosure is contrary to, or otherwise inconsistent with, a definition and/or description in these references, the definition and/or description set forth in this disclosure controls over those in references incorporated by reference. None of the references described or referenced herein is admitted as prior art relative to the current disclosure.

[0026] The discussion below describes an exemplary apparatus and method used to simultaneously remove a coating from the top and bottom surfaces of a substrate (e.g., wafer, panel, etc.) from an edge (or the edge zone) of the substrate. It should be noted that the specific features of the described apparatus are not limitations. Instead, embodiments of the described apparatus may be used to remove any coating(s) from any substrate in any suitable application. For example, the disclosed apparatus and method may be used to remove any type of coating (organic, inorganic, metallic, etc.) from any type of substrate.

[0027] The term substrate refers to the base material on which semiconductor or photonic devices or circuits are fabricated. In the discussion below, the term substrate is used broadly to refer to any component having a relatively flat surface upon which a coating may be disposed (conformally, as patches, in regions, etc.). For example, as used herein, a substrate includes a plate, a panel (e.g., a glass panel used in LCD manufacturing, photomask manufacturing, semiconductor packaging etc.), a semiconductor wafer (e.g., a silicon wafer used to fabricate IC devices), a wafer with multiple IC devices formed thereon, a single IC device, a part (e.g., ceramic, organic, metallic, etc.) with one or more coatings formed or disposed thereon, etc.

[0028] In the discussion below, an exemplary apparatus and method will be described with reference to a substrate in the form of a panel having a 4-sided polygonal (e.g., square, rectangular, etc.) shape. However, this is only exemplary, and as explained above, the apparatus and methods of the current disclosure may be applied to other configurations of substrates as well.

[0029] FIGS. 1A and 1B illustrate a top view and a side view, respectively, of an exemplary substrate 10 with a double-sided coating 12A, 12B. As best seen in FIG. 1B, substrate 10 includes coatings 12A, 12B on its opposite surfaces. For ease of reference, surface of the substrate 10 with coating 12A will be referred to as its top (or front) surface and the surface of the substrate 10 with coating 12B will be referred to as its bottom (or back) surface. In the discussion below, coatings 12A, 12B may be collectively referred to as coating(s) 12.

[0030] A coating is a thin layer of material formed on the surface of the substrate. The coating may serve various purposes such as protection, insulation, conductivity enhancement, or altering surface properties for specific applications. The coating material depends on the desired function and may include metals, oxides, polymers, or other specialized compounds. The coatings 12 may be formed using techniques like physical vapor deposition, chemical vapor deposition, spin coating, or sputtering, ensuring uniform coverage and adherence to the substrate surface. The term double-sided coating is used to refer to a coating formed on the top and bottom surfaces (or the front and back surfaces) of the substrate 10.

[0031] Coatings 12A and 12B may be made of the same or of different materials and may have the same or different thickness. Although illustrated as a single layer coating, coatings 12A and/or 12B may also be multi-layer coatings. As used herein, the term coating collectively refers to a coating formed of a single material and a multi-layer coating with multiple layers formed of different materials. Coatings 12A, 12B on the top and bottom surfaces may be formed of the same material or of different materials.

[0032] As best seen in FIG. 1A, substrate 10 includes keep-out-zones (KOZs) 20. KOZs 20 refer to areas of the substrate 10 where components or features (such as, for example, coatings 12) are not disposed (placed, fabricated, etc.) for a variety of reasons. KOZs 20 are typically defined based on the specific requirements of the semiconductor devices being manufactured and the processes involved in their fabrication. They are often specified in design guidelines and manufacturing specifications to ensure compliance throughout the production process. For example, KOZs 20 may the provided to facilitate the assembly process by providing clear areas for handling while the substrate 10 is transported between process steps. Although FIG. 1A illustrates KOZs 20 at the edges and the center of substrate 10, this is only exemplary.

[0033] During processing, coatings 12 are normally formed (e.g., deposited) over the entire top and bottom surfaces of the substrate 10. The deposited materials are then etched or removed from the KOZs 20, for example, along the edges of the substrate 10. The process of coating removal from the KOZs 20 at the edges of substrate 10 is referred to as the edge zone removal (EZR) process. It is desirable to remove the coating from the edges such that the retained coating (on substrate 10) has a substantially straight or substantially linear edge 22 as illustrated in FIG. 1B. This is to ensure that the processing area on the substrate 10 is not affected by the particles of the coatings present in the KOZ 20 during wafer handling. It is desirable that the EZR process be done with precision, accuracy, and repeatability to ensure desired straightness or linearity of the KOZ edge-lines on every substrate 10 being processed. It is also desirable that coatings 12 from both sides of the substrate 10 be simultaneously removed without contacting areas of the substrate 10 outside KOZ 20.

[0034] As best seen in FIG. 1C, substrate 10 with the double-sided coating 12 may have a warped configuration. Substrate warpage refers to the distortion or bending of the substrate. Substrate warpage may be caused due to a variety of factors. For example, differential heating and cooling during processing steps, such as deposition, curing, or annealing, can result in uneven thermal expansion and contraction across substrate 10 resulting in warpage. Differences in coefficients of thermal expansion (CTE) between the material(s) of the coatings 12 and the materials of the substrate 10 can also lead to warpage as the temperature changes during processing. The geometry and structure of the substrate, including its thickness, shape, and dimensions, may also contribute to warpage. For example, large and thin substrates may tend to sag or droop down at the edges and corners when it is supported by a fixture during the EZR process.

[0035] When a substrate is warped, its surface may not be perfectly flat, and this can affect various processes involving the substrate, including coating deposition and removal. For example, when a coating is applied to a warped substrate, the thickness of the coating may vary across the surface of the substrate 10. The warped nature of the substrate 10 makes achieving good linearity of etch along the edges of the substrate 10 challenging. FIG. 1B is a schematic illustration of a portion A (see also FIG. 1A) of the KOZ 20 at an edge of substrate 10. Line 22 schematically illustrates the desired substantially linear edge of the coating 12A after EZR process. Line 24 shows the possible non-linear profile of the coating edge after EZR process because of substrate warpage. Substrate warpage can lead to uneven or jagged edges where the coating has been removed, creating a non-linear edge. The apparatus and methods of the current disclosure are configured to reduce the non-linearity of the coating edge at the KOZ 20 resulting from substrate warpage (or variations in thickness of the coated substrate) during an EZR process.

[0036] FIG. 2A is a perspective view of an exemplary apparatus 30 that may be used to remove a double-sided coating 12 from an edge of a substrate 10 during an EZR process. Apparatus 30 may be configured to simultaneously remove (e.g., etch) the coating 12 from the top and bottom surfaces of the substrate 10 along the edges such that the edge of the coating post etching is substantially linear. Apparatus 30 includes a multi-head nozzle assembly 40 with multiple nozzle-heads 50 configured to simultaneously direct a chemical composition (e.g., a liquid etchant) to the top and bottom surfaces of the substrate 10 to simultaneously remove the coatings 12 from both sides of the substrate 10 at the substrate edge.

[0037] FIG. 2B illustrates a single nozzle-head 50 of nozzle assembly 40. Each nozzle-head 50 includes an upper nozzle-head 50A spaced apart (e.g., in the Z direction) from a lower nozzle-head 50B to form a gap 52 therebetween. As will be explained in more detail later, during an EZR process when coating 12 from an edge of the substrate 10 is removed, the edge of the substrate 10 is positioned in the gap 52 (see, e.g., FIG. 2C). FIG. 2C illustrates a cross-sectional side view of the single nozzle-head 50 of FIG. 2B. With reference to FIGS. 2B and 2C, nozzle-head 50 includes a nozzle body 66 that defines the gap 52 between the upper and lower nozzle-heads 50A, 50B. When multiple nozzle-heads 50 are assembled to form nozzle assembly 40 (see, e.g., FIG. 2A), the gaps 52 of the different nozzle-heads 50 align to form a slot that is configured to receive the edge of the substrate 10 therein.

[0038] With specific reference to FIG. 2C, nozzle-head 50 includes a pair of nozzle tips 64A, 64B (or nozzles) positioned on opposite sides of the gap 52. Nozzle tips 64A and 64B may be collectively referred to a nozzle tips 64. Nozzle tips 64 are configured to direct a pressurized stream (or jet) of the etchant on opposite surfaces of the substrate 10 received in the gap 52 between the upper and lower nozzle-heads 50A, 50B. For example, nozzle tip 64A supported by the upper nozzle-head 50A directs a stream of the etchant to the top surface of the substrate 10 to etch the coating 12A (at the edge) on the top surface, and nozzle tip 64B directs a stream of the etchant on the bottom surface of substrate 10 to similarly etch the coating 12B on the bottom surface. The nozzle tips 64A, 64B include conduits configured to direct the liquid etchant therethrough and discharge a stream of the etchant (e.g., a pressurized stream) on the substrate 10. It should be noted that, although described as an etchant, any suitable liquid (e.g., DI water, etchant, etc.) may discharged through the nozzle tips 64 of nozzle-head 50.

[0039] An annular space between each nozzle tip 64A, 64B and the nozzle body 66 defines a duct 76A, 76B (collectively referred to as duct 76) that is configured to direct a shroud (or a curtain) of high-pressure gas (e.g., nitrogen gas) around the stream of etchant (or chemical composition) emanating from each nozzle tip 64A, 64B. A conduit 78 extending through the body 66 directs a supply of nitrogen gas discharged through the duct 76 around the etchant. Discharging a shroud of high-pressure gas around the liquid etchant stream emanating from the nozzle tip 64 assists in etching the coating along a straight line with a sharp, well-defined edge. The high-pressure gas shroud may form a protective and confining barrier around the liquid etchant stream as it exits the nozzle tip 64 and help to contain and focus the liquid etchant to defined region of the coating 12, thereby preventing it from spreading beyond the desired etching area. As a result, the etchant may be guided along a more controlled and defined path. The gas shroud may also apply additional force and directionality to the etchant stream through aerodynamic effects. For example, the high-pressure gas may surround and push the liquid stream, thereby enhancing its momentum and directing it toward the substrate 10 in a more concentrated manner. This aerodynamic assistance may contribute to achieving a straighter and more uniform etching line. Enveloping the liquid etchant stream with high-pressure gas may also help to minimize edge smearing or feathering that can occur due to fluid turbulence or diffusion. For example, the gas barrier maintains the integrity of the etchant stream and allows it to maintain a sharp and well-defined edge profile as it contacts the surface of the substrate 10.

[0040] Nozzle-head 50 also includes a suction cup 82 disposed within the central gap 52. The suction cup 82 may be connected to a drainpipe 84 coupled to a vacuum pump. During operation of apparatus 30, the suction provided by the in-build suction cup 82 removes the etchants (and the removed coating) sprayed on the substrate through the nozzle tip 64. The nitrogen curtain around the liquid etchant stream helps in pushing the spent etchant towards and into the suction cup 82. It should be noted that although nitrogen gas is described as being used as a shroud to surround the etchant stream (discharged through the nozzle tip 64), this is only exemplary. In general, any suitable gas (e.g., air, an inert gas, etc.) may be used.

[0041] As can be seen in FIG. 2C, the nozzle tips 64 of nozzle-head 50 are inclined with respect to the coated surfaces of the substrate 10 such that the liquid stream emanating from these nozzle tips 64 impinge on the coated top and bottom surfaces of substrate 10 at an angle (e.g., an obtuse angle) to push the liquid along with the removed coating material (e.g., debris) towards the suction cup 82. In general, nozzle tips 64 may be inclined at any angle such that the liquid stream from these tips are angled (or directed) towards the suction cup 82. A longitudinal axis 130 of each nozzle tip 64 may be inclined at an angle () with a plane 120 of the substrate surface (top or bottom surface). In general, the angle of inclination () may be between about 30-60 degrees. In some embodiments, the angle of inclination () may be between about 40-50 degrees (or about 45 degrees in some embodiments). Directing a stream of the etchant (on the substrate surface) angled towards the suction cup 82 assists in removal of the etching waste products (via suction cup 82) without splashing and spreading on the surface of the substrate 10. Additionally, directing an angled jet of the etchant onto a coated substrate surface may offer a more controlled, efficient, and precise method of coating removal and may be particularly beneficial for applications requiring intricate surface treatment and uniform results.

[0042] Although an etchant is described as being discharged through the nozzle tips 64, this is only exemplary. In general, any liquid may be discharged through the nozzle tips 64. For example, in some embodiments, DI water may be discharged through the nozzle tips 64 of some nozzle-heads 50 (of nozzle assembly 40) while a suitable etchant may be discharged through other nozzle-heads 50. For example, with reference to the nozzle assembly 40 of FIG. 2A, in some exemplary embodiments, the outermost nozzle-head 50 (marked A) may discharge DI water while the other nozzle-heads 50 (marked B-E) may discharge an etchant. In such an embodiment, when the nozzle assembly 40 traverses along the substrate edge (e.g., in the Y direction) while removing the coatings 12, the etchant discharged by the nozzle tips 64 of nozzle-heads B-E will etch the coating on the substrate surface and the DI water discharged through nozzle-head A will rinse the etched substrate surface. Nozzle assembly 40 also includes a pair of air nozzles 70A, 70B positioned on one side of its multiple nozzle-heads 50 (e.g., beside nozzle-head A) to dry the substrate surface after rinsing. As will be described in more detail later, in some embodiments, the opposite side of the nozzle assembly 40 (e.g., besides nozzle-head E) includes one or more sensors 60 (see, e.g., FIG. 3A) configured to measure warpage of different regions of the substrate 10 just before it enters the nozzle assembly 40 for processing. It should be noted that the above-described scenario is only exemplary.

[0043] Typically, the type of liquid etchant (or chemical composition) discharged through a nozzle-head 50 depends on the application (e.g., the coating to be removed). For example, when a copper coating is to be removed from substrate 10, the chemical composition used may be one or more (e.g., a combination) ofa combination of sulfuric acid and hydrogen peroxide, nitric acid, citric acid, ammonium persulfate, cupric chloride, ferric chloride, or another commercially available etchant. As another example, when a titanium coating is to be removed, the chemical composition directed through the nozzle-head 50 may be one or more ofhydrofluoric acid, nitric acid with hydrofluoric acid, potassium hydroxide, ammonium fluoride, chlorine-based etchants, or another commercially available etchant. It should be noted that the specific chemistries described above are merely exemplary. In some embodiments, the etchant used may provide high selectivity to different coatings and other materials that may be present in the substrate 10 (e.g., Si, EMC, Polyimide, SiO.sub.2, etc.).

[0044] The type of gas discharged through the duct 76 to form a shroud around the liquid stream emanating from the nozzle tip 64 may also depend on the application. In general, any gas (e.g., air, N.sub.2, an inert gas, etc.) may be discharged through the duct 76. In some embodiments, the liquid etchant (or DI water) discharged through the nozzle tips 64 may be heated. Additionally, or alternatively, in some embodiments, the gas discharged through duct 76 may be heated. In some embodiments, heaters may be coupled to the nozzle-heads 50 to heat the etchant (and/or DI water) discharged through the nozzle tips 64 and/or the gas discharged through ducts 76. In some embodiments, the liquid (e.g., etchant and DI water) and the gas discharged through the nozzle-heads 50 may be pressurized.

[0045] With reference to FIG. 2A, to remove coating 12 from an edge of substrate 10, with the edge positioned in the gap 52 between the upper and lower nozzle-heads 50, and the nozzle tips 64A, 64B discharging a pressurized etchant stream on the substrate with the ducts 76 discharging a pressurized gas shroud around the etchant stream, the nozzle assembly 40 moves (e.g., in the +Y direction in FIG. 2A) along the edge of the substrate 10 (or scans the substrate). As the etchant impinges on the coating 12 of the substrate 10, the coating gets etched and removed from the substrate surface. The discharged etchant along with removed coatings gets removed via the suction cup 82. To achieve a high degree of linearity of the coating edge, as will be described in more detail below, the nozzle-heads 50 of the multi-head nozzle assembly 40 are configured to follow (e.g., move up and down, etc.) the substrate warpage such that the substrate 10 is substantially centered between the upper and lower nozzle-heads 50A, 50B of nozzle-head 50 during the etching process.

[0046] FIGS. 3A and 3C illustrate a side view and a top view, respectively, of an exemplary apparatus 30. In the discussion that follows, reference will be made to FIGS. 2A-2C, 3A, and 3C. As best seen in FIGS. 2A and 3C, the multiple nozzle-heads 50 of nozzle assembly 40 are arranged side-side (e.g., arranged in parallel) such that the gaps 52 of the different nozzle-heads 50 align to form a slot that is adapted to receive an edge of the substrate 10 therein. In the exemplary embodiment illustrated, five nozzle-heads 50 are stacked along the Y-axis. However, this is only exemplary, and in some embodiments, nozzle assembly 40 may have a different number of nozzle-heads 50 (e.g., 2-12 nozzle-heads). It is also contemplated that, in some embodiments, nozzle assembly 40 may only include a single nozzle-head 50.

[0047] As explained previously, the nozzle tips 64A, 64B (see FIG. 2C) of the upper and lower nozzle-heads 50A, 50B of each nozzle-head 50 are inclined (e.g., is between 30-60 degrees, between 40-50 degrees, about 45 degrees, etc.) with the coated surface of the substrate 10 positioned in the gap 52. In some embodiments, as illustrated in FIGS. 3A and 3C, the inclined nozzle tips 64A, 64B may be arranged such that the etchant stream that emanates from these nozzle tips 64A, 64B impinge on the top and bottom surfaces of the substrate at a common X-axis contact location 54. In some embodiments, the one or more sensors 60 of nozzle assembly 40 may also be arranged to measure the warpage of the substrate 10 in the vicinity of the contact location 54 (see FIG. 3C).

[0048] In the exemplary embodiment illustrated in FIG. 3A, two vertically spaced-apart sensors 60A, 60B are positioned on one side of the nozzle-heads 50 of nozzle assembly 40. The sensors 60A, 60B may be positioned on nozzle assembly 40 such that, as the nozzle assembly 40 scans a substrate 10 during the EZR process, a region of the substrate 10 passes between the sensors 60A, 60B before it is processed by (e.g., enters the gap 52 between) the nozzle-heads 50. As illustrated in FIG. 3A, the two sensors 60A and 60B are positioned on opposite sides of the substrate 10 being processed by apparatus 30, and each sensor 60A, 60B may be configured to measure the distance of the substrate 10 from the sensor. The warpage of the substrate 10 may be determined based on the readings of the sensors 60A, 60B. For example, as the substrate 10 moves between the two vertically spaced apart distance sensors 60A, 60B, the distance from each sensor to the substrate surface is measured by each sensor, and the difference between the measurements may be used as an indication of the degree of warpage or curvature in the substrate 10 at the location of measurement 56.

[0049] As best seen in FIG. 3C, in some embodiments, the sensors 60A, 60B may be arranged such that the location of warpage measurement 56 is aligned with (e.g., in the same location as, or in the vicinity of) the etchant contact location 54. In some embodiments, the location of warpage measurement 56 may be at substantially the same X-axis location as the etchant contact location 54. In some embodiments, the distance between the location of warpage measurement 56 and the etchant contact location 54 may be less than or equal to about 10 mm (or 5 mm in some embodiments). In general, the sensors 60A, 60B may be positioned relative to the nozzle assembly 40 such that the coating 12 of the substrate 10 is etched at substantially the same region as where the substrate warpage is measured. In some embodiments, when measured along the X-axis, the distance of the etchant contact location 54 and the warpage measurement location 56 from the edge of the substrate 10 may be substantially the same.

[0050] It should be noted that the use of two sensors 60A, 60B to measure substrate warpage is only exemplary. In some embodiments, as illustrated in FIG. 3B, a single sensor 60 (e.g., a distance sensor) may be used to determine the warpage of the substrate 10. Sensor 60 may measure the distance of the substrate 10 (e.g., in the Z direction) from the sensor 60, and based on the detected change in this distance as the nozzle assembly 40 scans the substrate 10, the warpage of the substrate 10 may be determined. Typically, as illustrated in FIG. 4A, when the thickness of the coating 12 and the thickness of the substrate 10 is known and substantially uniform, a single distance sensor 60 (see FIG. 3B) may be sufficient to measure the substrate warpage. However, as illustrated in FIG. 4B, in embodiments where the coating thickness and/or the substrate thickness is not uniform (or not known), it may be desirable to use two sensors 60A, 60B (see FIG. 3A) to measure the warpage and the thickness of the coated substrate at different regions.

[0051] In some embodiments of the current disclosure, during an EZR process, the measured warpage of the substrate 10 (by the one or more sensors) is used to adjust the position (or location) of the nozzle-heads 50 to compensate for the substrate warpage while etching the coating 12. For example, a controller or a control system of apparatus 30 may activate motors associated with the nozzle assembly 40 based at least partly on signals from the one or more sensors to move (or translate) the nozzle-heads 50 (in one or more directions) to account for the substrate warpage while etching the coating 12.

[0052] For example, if the measured warpage of the substrate 10 at a particular location (of the substrate 10) is A units (in the +Z direction), when the coating 12 at that location is being etched (or that location enters the gap 52 between the nozzle-heads 50), the nozzle-heads 50 may be translated upwards (e.g., in the +Z direction) by A units, or a function of A units (f(A)), to account for the warpage of the substrate 10 at that location. Similarly, if the warpage of the substrate 10 at a location is A units (in the Z direction), the nozzle-heads 50 may be translated downwards (e.g., in the Z direction) when etching the coating at that location. In general, the amount by which the nozzle-heads 50 are translated (or the Z-axis compensation applied to the nozzle-heads 50 to account for substrate warpage) is calculated based on the substrate warpage determined by the sensor(s) and the nozzle geometry.

[0053] In some embodiments, as illustrated in FIG. 5A, the nozzle assembly 40 may be translated (e.g., in the Z direction) such that all the nozzle-heads 50 of the nozzle assembly 40 moves up and down as a single unit. For example, the nozzle assembly 40 may move upwards (e.g., in the +Z direction) to account for an upward warpage of a region of the substrate 10 and may move downwards (e.g., in the Z direction) to account for a downward warpage of a region of the substrate 10. As illustrated in FIG. 5A, a controller or control system 80 of apparatus 30 may control the movement of the nozzle-heads 50 based on input from the one or more sensors (e.g., sensors 60, 60A, 60B, etc.). For example, with reference to FIG. 5A, the sensors 60A, 60B may determine the warpage of the substrate 10 at a location R, and control system 80 may control the translation of the nozzle-heads 50 in the Z direction such that the region of substrate 10 at location R remains centered in the gap 52 (between the upper and the lower nozzle-heads 50A, 50B of nozzle assembly 40) when the coating at that region (region R) is being etched so that the etched edge of the coating remains substantially linear along the entire etched length.

[0054] In some embodiments, at least some of the individual nozzle-heads 50 of the nozzle assembly 40 may be configured to be translated individually (e.g., separate from other nozzle-heads). FIG. 5B illustrates an exemplary embodiment where each nozzle-head 50 of nozzle assembly 40 is configured to be translated upwards or downwards in the Z direction individually. Each nozzle-head 50 may be translated in the Z direction such that the gap 52 between the upper and lower nozzle-heads 50A, 50B of that nozzle-head 50 remains unchanged. In some embodiments, the individual nozzle-heads 50 (of the nozzle assembly 40) may be moved up or down to track the measured warpage (or change in the Z-axis location) of a location R on the substrate 10. For example, when location R is positioned in the gap 52 between the upper and lower nozzle-heads of the nozzle-head 50 marked E (in FIG. 5B), that nozzle-head 50 may be translated in the Z direction such that the substrate at location R is centrally positioned in the gap 52. And when the nozzle assembly 40 moves (in the Y direction) relative to the substrate 10, and location R is positioned between nozzle-head D, that nozzle-head is translated such that the substrate at location R is centrally positioned between this nozzle-head, and so on.

[0055] In some embodiments, as illustrated in FIG. 5C, some nozzle-heads 50 of nozzle assembly 40 may be connected to translate together as one unit. For example, nozzle-heads E and D may be connected together such that they translate upwards or downwards as one single unit, and nozzle-heads A-C may be connected together such that they translate as one unit separate from nozzle-heads D and E. Any of the nozzle-heads 50 of nozzle assembly 40 may be connected together to translate as a single unit.

[0056] In some cases, the thickness of the deposited coatings 12A, 12B on the top and bottom sides on the substrate 10 may not be the same. Also, there may be a significant non-uniformity in the thickness of the coatings on each side (see, e.g., FIG. 4B). In such cases, it may be desirable to measure the thickness as well as the warpage along the length (e.g., along the scanning direction) of the substrate 10. Both the thickness and the warpage may be determined based on the measurements of sensors 60A and 60B. In such embodiments, the thickness and the warpage may be used to calculate the compensation to be applied to the nozzle-heads 50 to achieve etch linearity. The non-uniformity in the thickness of the substrate 10 and/or the coating 12 along the Y-axis (which is the etching direction) also affects etch linearity. The dimension of the substrate 10 in the etching direction is referred to herein as the length of the substrate 10.

[0057] As illustrated in FIG. 6A, the change in thickness (t) of the coated substrate from t.sub.1 to t.sub.2 (<t.sub.1) causes a change in the width (w) of etched zone from w.sub.1 to w.sub.2 (<w.sub.1) even if the substrate 10 is well centered between the nozzle-heads 50. For example, the width of the etched region becomes smaller when the thickness of the coated substrate decreases and increases when the thickness of the coated substrate increases. Thus, variations in the thickness of the substrate (and/or the coating) along the length (or the etching direction) of the substrate 10 affects etch linearity even if the substrate 10 is centered in the gap 52 of a nozzle-head 50. FIG. 6B plots the computed variation in the etch width (w) with the thickness variation (t) of a coated substrate for an exemplary case (e.g., when the angle of inclination of the nozzle tips 64 of the nozzle-heads 50 is 45 degrees).

[0058] Therefore, in some embodiments, X-axis compensation may additionally or alternatively be applied to the nozzle-heads 50 to reduce the edge non-linearity resulting from variations in thickness. In other words, the nozzle-heads 50 may additionally (or alternatively) be moved in the X direction to account for the variation in the thickness of the coated substrate (e.g., substrate-substrate thickness variation) along the length of the substrate 10. It should be noted that the different nozzle-heads 50 may be translated (e.g., in addition to, or as an alternative to, their Z direction translation) in the X direction in a similar manner as described above with reference to FIGS. 5A-5C to account for the variations in thickness of the coated substrate. For example, in embodiments where the thickness of the coated substrate is not uniform, based on input from a pair of sensors 60A, 60B, the control system 80 (see FIG. 5A) may apply X-axis compensation by moving the nozzle-heads 50 (collectively or individually) in the X direction to account for variations in thickness of the coated substrate along the length. Additionally, the control system may also apply Z-axis compensation by moving the nozzle-heads 50 (collectively or individually) in the Z direction also to account for the warpage of the substrate along the length. The nozzle-heads 50 of nozzle assembly 40 may be connected to one or more motors configured to translate the nozzle-heads 50 (individually or collectively) in the Z and/or X directions as described.

[0059] It should be noted that, although embodiments with a single sensor and a pair of sensors have been described, these are only exemplary. In general, any number (e.g., 1-6) sensors may be used. Moreover, any type of contact or non-contact sensor (e.g., ultrasonic sensor, infrared sensor, laser sensor, time-of-flight sensor, inductive sensor, capacitive sensor, optical sensor, camera-based sensor, etc.) may be used.

[0060] In some embodiments, an exemplary apparatus 30 of the current disclosure may include multiple nozzles assemblies 40 to increase throughput. Each of these multiple nozzle assemblies 40 may be controlled as described previously (e.g., translated in the Z and/or the X direction) such that the nozzle assembly 40 tracks substrate warpage and/or its thickness variation, and as a result, the edge of the etched coating is substantially linear along the entire etched length. For example, FIG. 7 illustrates an exemplary apparatus 30 where a pair of nozzle assemblies 40 are positioned on opposite sides of a substrate 10 to simultaneously etch the opposite sides of the substrate. Each of these nozzle assemblies 40 includes multiple nozzle-heads and are controlled as described previously to achieve a substantially linear edge of the etched coating. For example, as each nozzle assembly 40 scans the substrate 10 (e.g., moves along the edge of the substrate 10 along the Y-axis or the etching direction), the sensors 60A and 60B associated with each nozzle assembly 40 measures the substrate warpage ahead of the nozzle assembly 40, and the control system 80 (see FIG. 5A) of apparatus 30 determines and applies Z-axis compensation to keep the substrate 10 centered between the nozzle-heads 50 as the etchant is directed to the top and bottom sides of the substrate 10. In embodiments where the thickness of the coated substrate varies in the etching direction, the control system 80 also determines and applies X-axis compensation to achieve a substantially linear edge of the etched coating.

[0061] In the embodiments described above, warpage and/or thickness measurement, compensation determination, and compensation application are all done in a single pass of the nozzle assembly 40. For example, the sensors positioned ahead of the nozzle assembly 40 (in the etching direction) measures the substrate warpage and/or thickness, and the control system calculates the required Z-axis and/or X-axis compensation and applies the compensation to the nozzle-heads as the coating 12 on the substrate 10 is being etched. Such a single pass approach helps to increase the throughput due to the on-the-fly (or ad-hoc) compensation application. However, this approach may require low latency communication between the sensors, motors, and the control system.

[0062] In some embodiments of the current disclosure, the warpage and/or thickness variation of the substrate 10 may be determined a priori, and these predetermined values may be used to apply compensation (Z-axis and/or X-axis compensation) when the coating is etched later. For example, in an exemplary two-pass approach of the current disclosure, a first pass is used only to measure the warpage (and/or thickness variation). Etchant is not sprayed during this pass. The required compensation (Z-axis and/or X-axis compensation) to produce a substantially linear coating edge is determined using the measured data and applied to the nozzle-heads when etching is carried out during a second pass.

[0063] FIGS. 8A-9B illustrate an exemplary two-pass method. FIGS. 8A and 8B illustrate the first pass where the warpage and/or the thickness variation along the substrate length is measured. In some such embodiments, as illustrated in these figures, sensors 60A, 60B may be positioned ahead of the nozzle-heads in x-direction so that the warpage can be measured at any location in the KOZ of the substrate 10 without having to position the substrate 10 between the upper nozzle-head 50A and the lower nozzle-head 50B. In other words, the sensors 60A, 60B may project or extend from the nozzle assembly 40 towards the substrate 10. This may prevent accidental bumping of the substrate against the nozzle-heads 50 (e.g., when a substrate is highly warped).

[0064] The required compensation is calculated using the measured data and applied to move the nozzle-heads 50 in the Z direction and/or the X direction during the second pass when the edge of the substrate is inserted between the upper and lower nozzle-heads 50A, 50B and etchant is sprayed on the substrate 10. In some embodiments, the calculated compensation profile from measurements taken during the first pass may be stored for use while etching multiple similarly warped substrates (e.g., same lot of substrates) in the second pass. FIGS. 9A and 9B schematically illustrate the second pass. As described previously (e.g., with reference to FIGS. 5A-5C), the nozzle-heads 50 may be moved individually or collectively in the Z and/or the X direction based on the measured warpage (and/or thickness variation) to produce a substantially linear edge after etching.

[0065] FIG. 10 illustrates an exemplary disclosed method 100 that may be used to produce a substantially linear edge of an etched coating on a substrate. In step 110, the warpage and/or thickness variation of the substrate along the length of the substrate is measured. The warpage and/or thickness variation of step 110 may be measured using one or more sensors using a one-pass or a two-pass approach as described previously. In step 120, the nozzle-head compensation needed to produce a substantially linear edge of the etched coating in step 130 may be determined using the data measured in step 110. As explained previously, this step may involve determining the required amount of vertical displacement or movement (or vertical compensation) of the nozzle-heads to track (or account for) the warpage of the substrate as the nozzle-heads etch the coating along the length of the substrate (in step 130). In some embodiments, step 120 may additionally or alternatively include determining the required amount of horizontal displacement (or horizontal compensation) of the nozzle-heads to account for the thickness variation of the coated substrate as the nozzle-heads etch the coating along the length of the substrate (in step 130).

[0066] In step 130, as explained previously, the coating on the top and bottom surfaces of the substrate may be simultaneously etched by scanning the nozzle-heads along the length of the substrate while spraying a suitable etchant on the substrate to etch the coating on the opposite surfaces. As the nozzle-heads traverse the length of the substrate in step 130, the nozzle-heads may be moved in the vertical direction (e.g., in a first direction orthogonal to the direction of travel of the nozzle-heads) and/or the horizontal direction (e.g., in a second direction orthogonal to both the direction of travel of the nozzle-heads and the first direction) based on the calculated vertical and/or horizontal compensation in step 120. Compensating for the warpage and thickness variation of the substrate while etching the coating produces a substantially linear edge of the etched coating.

[0067] It should be emphasized that method 100 of FIG. 10 may be applied while using a one-pass approach (see, e.g., FIGS. 3A-3C) or a two-pass approach (see, e.g., FIGS. 8A-8C). Moreover, although method 100 is described with reference to a specific apparatus (apparatus 30 having multiple nozzle-heads 50), this is not a requirement. Method 100 may be applied to any apparatus used to remove coating from a keep-out-zone (or any other region) of a substrate. For example, an exemplary apparatus may include a single nozzle that ejects a stream of a high-pressure etchant on one surface (e.g., the top surface) of a substrate to remove a coating from a region (e.g., a KOZ) on the top surface. The warpage of that substrate may be measured (a priori or in situ) and used to apply a compensation on the etching nozzle to account for substrate warpage during the etching so that a substantially linear etched edge can be realized in spite of the warpage.

[0068] In some embodiments, an exemplary method of using the etching apparatus may include additional steps not illustrated in method 100. For example, after etching one edge, the substrate and/or the apparatus may be rotated to etch other edges of the substrate 10. As another example, when apparatus 30 (or another apparatus used to etch coatings at a KOZ) is incorporated in a tool, the method may include steps, such as, a pick-and-place robot picking a substrate from a load port and placing it on a support fixture of apparatus in preparation for etching, a robot removing the substrate after etching in apparatus and moving it another process module for additional processing.

[0069] Although the current disclosure is described as being used to remove a coating from the KOZ at an edge of a substrate, this is only exemplary. For example, the disclosed apparatus and method may be used to remove a coating from any region (e.g., center, side, etc.) of a coated substrate. Persons of ordinary skill in the art would recognize that the disclosed apparatus can be used for any application (e.g., to remove paint from the surface of a component, a metallic or polymeric coating from the surface of a ceramic/organic substrate or a semiconductor wafer, etc.). Furthermore, although in the description above, some features were disclosed with reference to specific embodiments, a person skilled in the art would recognize that this is only exemplary, and the features are applicable to all disclosed embodiments. Other embodiments of the apparatus, its features and components, and related methods will be apparent to those skilled in the art from consideration of the disclosure herein.