System and Method for Sintering Structures on a Base

Abstract

A system and a method for sintering one or more structures on a base includes at least one sinter unit that is configured to sinter the structures on the base. The sinter unit is further configured to position at least one film layer to be in proximity to the structures on the base, and apply force and provide heat to the film layer and the structures on the base for the structures to sinter. A corresponding method is further described.

Claims

1. A system for sintering one or more structures on a base, comprising at least one sinter unit, configured to sinter the one or more structures on the base; wherein the sinter unit is further configured to position at least one film layer to be in proximity to the one or more structures on the base; and apply force and provide heat to the film layer and the one or more structures on the base for the one or more structures to sinter.

2. The system according to claim 1, wherein the sinter unit comprises a thermal-pressure module, which comprises a presser, which is configured to apply the force via its press surface; a platform, in which the base rests thereupon; and a heating sub-module, which is configured to provide heat to any one or both the presser and the platform.

3. The system according to claim 2, wherein the presser is configured to move along one or more directions, which include any one or both of: a first direction for applying the force against the one or more structures on the base, with the film layer being between the presser and the one or more structures on the base; and a second direction for relieving the force against the one or more structures on the base.

4. The system according to claim 2, wherein the press surface of the presser is contoured to include one or more cavities, which are each adapted to substantially enclose and to be substantially adjacent to each of the one or more structures on the base as the presser applies the force.

5. The system according to claim 2, wherein the film layer is heat resistant; and the presser has a coating that substantially prevents adhesion between the presser, and any one or both the film layer and the one or more structures on the base.

6. The system according to claim 2, further comprising a film handler module that is configured to prepare and handle a tray, the tray being formed by the film layer being supported by a support structure, for the tray to be actuated for the film layer to be between the presser and the one or more structures on the base.

7. The system according to claim 1, further comprising a first material application unit configured to position a stencil to be adjacent to the base, and dispose a first material onto the stencil to be spread, for the one or more structures to be formed on the base.

8. The system according to claim 7, further comprising a second material application unit configured to dispose second material onto the one or more structures on the base.

9. The system according to claim 1, wherein the one or more structures are of a material composition that is selected from a group of metals that comprises copper, silver, gold, palladium, tin, or platinum.

10. A method for sintering one or more structures on a base, comprising the step of sintering the one or more structures on the base, by a sinter unit; wherein the sinter unit is further configured to position at least one film layer to be in proximity to the one or more structures on the base; and apply force and provide heat to the film layer and the one or more structures on the base for the one or more structures to sinter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To facilitate an understanding of the invention, there are illustrated in the accompanying drawings the preferred embodiments from an inspection of which when considered in connection with the following description, the invention, its construction and operation and many of its advantages would be readily understood and appreciated.

[0019] FIG. 1 is a schematic diagram illustrating an example system of the present invention for sintering structures on a base.

[0020] FIG. 2 is a flowchart illustrating example steps of the method of the present invention for sintering structures on a base.

[0021] FIG. 3 is a schematic diagram illustrating the base being applied with a first material, more specifically, electrically-conductive material, thereupon for forming the first structures on the base, according to an example implementation of the present invention.

[0022] FIG. 4 is a schematic diagram illustrating the base having first structures formed thereupon, according to an example embodiment of the present invention.

[0023] FIG. 5 is a schematic diagram illustrating the base having the first structures thereon, undergoing drying by a heating module for the first structures to sinter, according to an example implementation of the present invention.

[0024] FIG. 6 is a schematic diagram illustrating the base having second structures thereupon, which are sintered from the first structures, according to an example embodiment of the present invention.

[0025] FIG. 7 is a schematic diagram illustrating the base having second structures thereupon, which is to receive a pressure force exerted by a heated presser, with a film layer being in-between the presser and the second structures, according to an example implementation of the present invention.

[0026] FIG. 8 is a schematic diagram illustrating the base having third structures thereupon, which are sintered from the second structures, according to an example embodiment of the present invention.

[0027] FIG. 9 is a schematic diagram illustrating the base having the third structures, each having the second material, being cleaned by one or more cleaners, according to an example implementation of the present invention.

DETAILED DESCRIPTION

[0028] The present invention primarily relates to a system and method for sintering one or more structures on a base. The structures that are sintered may be electrically conductive. More specifically, the structures may be copper pillars.

[0029] From hereon, in the context of the present invention, it is to be stated that the term base may refer to an item that is to be used as (i) a base layer in which at least one electronic component or electronic circuit is fabricated therefrom, (ii) a base layer that supports at least one electrical and/or electronic component attached thereto, (iii) contact pads of an electronic component that may be a die or a chip, (iv) contact pads of a circuit board, or (v) a combination thereof. The base may broadly also be any form of item that is capable of providing support. It is preferred that the base may be in the form of a substrate, such as a wafer. Furthermore, the base may be electrically conductive, electrically semi-conductive or an electrical insulator. The composition of the base may be of a single element, a compound, an alloy, or a composite. By way of example, the composition of the base may be of silicon, germanium, FR-4, or the like.

[0030] The invention will now be described in greater detail, by way of example, with reference to the drawings.

[0031] FIG. 1 is a schematic diagram illustrating an example system of the present invention for sintering structures on a base. As shown in FIG. 1, a base 10 is to be provided to the system of the present invention for structures to be formed and sintered thereon.

[0032] The system of the present invention may comprise at least one first material application unit 30, at least one first sinter unit 40, at least one second sinter unit 50, at least one second material application unit 60, and at least one cleaning unit 70. It is to be noted that the second material application unit 60, and the cleaning unit 70 may be optionally included in the aforementioned system.

[0033] These aforementioned units may be substantially in communication with each other via wired or wireless means. These aforementioned units may also be substantially connected with each other via one or more conveying units which may carry objects (i.e. the base 10 having structures or without structures) from one unit to another. Furthermore, the aforementioned units may be located at different locations, or alternatively, they may be housed within a single machine.

[0034] As shown in FIG. 1, the base 10 is to be provided to the first material application unit 30 for one or more first structures 21 to be formed thereon. Then, the base 10, having the first structures 21 thereon, may be provided to the first sinter unit 40 for the first structures 21 to be sintered into second structures 22. Then, the base 10, having the second structures 22 thereon, may then be provided to the second sinter unit 50 for the second structures 22 to be sintered into the third structures 23.

[0035] The base 10 having the third structures 23 may then optionally be provided to a second material application unit 60, and subsequently, a cleaning unit 70. With this, the base 10 shall have its third structures 23 disposed or deposited with a second material 61 while being cleaned accordingly for subsequent downstream processing.

[0036] Regarding the first material application unit 30 as shown in FIG. 1, it may generally comprise at least one stencil 31, at least one squeegee 32, and at least one first material supply 33 that supplies first material. In particular, the first material supplied by the first material supply 33 is to be disposed or deposited onto the base 10 and be spread across a stencil 31 through the squeegee 32 for filling apertures of the stencil 31. The squeegee 32 may apply a force to ensure that the apertures of the stencil 31 are each compactly filled with the first material. With that, the base 10 may be formed with the first structures 21. It is to be noted that stencil 31 may be made from metallic material, or any other suitable material.

[0037] Regarding the first material application unit 30, in one embodiment where the base 10 has one or more contact pads, the stencil 31 may be positioned for its apertures to be aligned with these contact pads so that the first material to be disposed or deposited thereon for the first structures 21 to be formed upon each contact pad.

[0038] Whilst not shown in FIG. 1, the first material application unit 30 may generally further comprise at least one manipulator module and at least one processor. In particular, the manipulator may manipulate any one or a combination of the substrate 10, the stencil 31, the squeegee 32 and the first material supply 33 for their intended operations. Whereas, the processor may run at least one software application to operate one or more software modules that execute instructions related to the operation of the first material application unit 30, and it may be substantively interfaced with any one or a combination of the manipulator and the first material supply 33.

[0039] Regarding the first sinter unit 40 as shown in FIG. 1, it may generally comprise a heating module 41 that is configured to heat an enclosed environment. Whilst not shown in FIG. 1, the first sinter unit 40 may generally further comprise an accessible enclosure, which may define the enclosed environment especially when it is in a closed condition. The heating module 41 may further be configured to provide heat to the enclosure either by means of conduction, convection, radiation, or any combination thereof. Also, the heating module 41 may further be configured to substantially enable the enclosure to be evenly heated to a preset temperature. Sinter U

[0040] Regarding the second sinter unit 50 as shown in FIG. 1, it may generally be configured to sinter the second structures 22 on the base 10 into the third structures 23. In particular, it may be further configured to position at least one film layer to be in proximity to the structures (i.e. the second structures 22) on the base 10, and apply force and provide heat to the film layer and the structures (i.e. the second structures 22) on the base 10 for them to sinter.

[0041] Regarding the second sinter unit 50 as shown in FIG. 1, it may generally comprise a thermal-pressure module 51 and a film handler module 52. In particular, the thermal-pressure module is configured to provide heat while exerting a force, in the form of a pressure force, to an object (i.e. the base 10 having the second structures 22) that is provided to the second sinter unit 50. Whereas, the film handler module 52 is to handle a film layer that is to be used as an intermediary between the aforementioned object and the thermal-pressure module 51.

[0042] Regarding the thermal-pressure module 51 as shown in FIG. 1, it may generally comprise a presser 511, a platform 512, and a heating sub-module 513. In particular, the presser 511 is configured to apply the pressure force via its press surface, the platform is where the object (i.e. the base 10 having the second structures 22) rests thereupon, and the heating sub-module 513 is configured to provide heat to any one or both the presser 511 and the platform 512.

[0043] In particular, regarding the presser 511, it may be configured to move along one or more directions. These directions may include any one or both a first direction and a second direction. As the presser 511 moves along the first direction, it applies the pressure force against the structures on the base 10, with the film layer being between the presser and the second structures 22 on the base 10. As the presser 511 moves along the second direction, it relieves the pressure force applied against the second structures 22 on the base 10.

[0044] In particular, regarding the presser 511, it is to be noted that its press surface may be contoured to have one or more cavities. These cavities may be concave-shaped. As the presser 511 applies the pressure force, these cavities may each substantially enclose and be substantially adjacent to a second structure 22 on the base 10 that is resting on the platform 512. Moreover, as the presser 511 applies the pressure force, these cavities may each substantially mould a shape of a structure on the object (i.e. the second structures 22 of the base 10), which rests on the platform 512, for them to substantially conform to the shape of the cavity.

[0045] In particular, regarding the presser 511, it is to be noted that its press surface may be coated with a non-stick or anti-stick coating to enable the presser 211 to disengage from the object (i.e. the base 10 having the second structures 22) resting on the platform 512, while preventing adhesion between the presser 511, and any one or both the film layer and the second structures 22 on the base 10.

[0046] In particular, regarding the heating sub-module 513, it may further be configured to substantially heat either one or both the presser 511 and the platform 512 evenly or unevenly to a preset temperature. Also, the heating sub-module 513 may heat the presser 511 and the platform 512 for them to have a different temperature, or a temperature of the same.

[0047] Regarding the film handler module 52 as shown in FIG. 1, it preferably facilitates the handling of a film layer that is to be positioned between the presser 511 and the object (i.e. the base 10 having the second structures 22) resting on the platform 512, with the film layer being proximity with the second structures 22 of the base 10. Whilst not shown, the film handler module 52 may comprise its own manipulator module for preparing and handling a tray having the film layer. The aforementioned tray may comprise a substantially frame-like or annular-like support structure having an inner perimeter and an outer perimeter.

[0048] Regarding the film handler module 52, it is to be noted that the film layer may be manipulated to be overlaid across the support structure for it to be substantially defined with an outer portion and an inner portion. The outer portion may be portions of the film layer along a first area, which is defined to be an area between the inner perimeter and the outer perimeter of the support structure. The inner portion may be portions of the film layer within a second area, which is defined to be an area within the inner perimeter of the support structure, in which the film layer is unsupported by the support structure.

[0049] Regarding the film handler module 52, it is to be noted that the characteristics of the film layer may include that it is substantially flexible, resilient (i.e. having elasticity), and heat resistant. As such, when the heated presser 511 exerts a pressure force against the film layer of the tray and the object (i.e. the base 10 having the second structures 22) on the platform 512, the film layer may substantially conform to the contours of the heated presser 511 as well as the overall shape of the second structures 22 while withstanding heat from the heated presser 511. In particular, the film layer may be made of composite material, and may be, by way of example, made of polymers, polyimide (e.g. Kapton), polytetrafluoroethylene (e.g. Teflon), or the like. Furthermore, the film layer may be capable of withstanding temperatures of at least 250 C. or more.

[0050] Whilst not shown, the second sinter unit 50 may further comprise a processor that may run at least one software application to operate one or more software modules that execute instructions related to the operation of the second sinter unit 50, and it may be substantively interfaced with, or allows interfacing of, any one or a combination of the thermal-pressure module 51 and the film handler module 52, and their related components.

[0051] Regarding the second material application unit 60 as shown in FIG. 1, it is configured to dispose or deposit second material upon an object (i.e. the third structures 23 of the base 10) that is provided thereto. Whilst not shown, it may substantially comprise components similar to the first material application unit 30. By way of example, it may generally comprise a second material disposition means, a second material supply, and a corresponding processor that operates software modules for its intended operations.

[0052] Regarding the cleaning unit 70 as shown in FIG. 1, it is configured to perform cleaning upon at least one object (i.e. the base 10 having the third structures 22 each disposed or deposited with a second material) that is provided thereto. The cleaning unit 70 may generally comprise one or more cleaners 71 for cleaning the entirety of the object. The cleaning performed by these cleaners 71 may be any type of cleaning known in the art of cleaning semiconductor components during their manufacturing.

[0053] With this, it is to be noted that the first material that is applied by the first material application unit 30 onto the base 10 is preferably electrically conductive. The composition of the first material may be of a single element, and it may most preferably be copper, but it may be any other element selected from a group of elements that comprise aluminium, silver, gold, palladium, tin, platinum, or the like, and it should be noted that they may not be limited to as such. Alternatively, the first material may have a composition that of an alloy, a compound, or a composite.

[0054] In the case where the first material has a material composition that is copper, the first structures may be regarded as first copper pillar precursors, the second structures may be regarded as second copper pillar precursors, and the third structures may be regarded as the final product being copper pillars.

[0055] With this, it is to be noted that the second material that is applied by the second material application unit 60 onto the third structures 23 on the base 10 may be bonding material having adhesive properties. More specifically, the second material shall substantially promote bonding between third structures 23 on the base 10 and other components or objects. The second material may be bonding agents such as solder, or the like.

[0056] As for processors that may be present in each of the units of the system of the present invention, they may be, but shall not be limited to, a conventional processor, application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a graphics processing unit (GPU), or a combination thereof.

[0057] It is noted that for the rest of the description, the described hardware and software components of the system may not be directly implicated. However, it is to be understood by a skilled person that the descriptions of the hardware and software components above provide support for the rest of the description.

[0058] FIG. 2 illustrates an example flowchart describing the method for sintering structures on a base as provided by the present invention. It is noted that the steps described in this flowchart are not to be interpreted as non-limiting, and minor modifications to the steps (e.g. additions, repetitions, omissions, or swaps) are permissible by a skilled person without substantial deviation from as described.

[0059] Furthermore, it is to be noted that the descriptions relating to FIG. 2 shall be further complemented by FIG. 3-9, and they may further complement the system of the present invention as described in FIG. 1.

[0060] FIG. 2 may begin with step 201. Step 201 may involve providing at least one of the base 10 to the first material application unit 30. In particular, the base 10 had been prepared accordingly for it to be formed with structures. By way of example, base 10 may be a disc of silicon wafer, a piece of silicon die singulated from a silicon wafer, or the like.

[0061] Steps 202 to 205 may be subsequent steps of Step 201. Steps 202 to 205 shall be described in relation to FIGS. 2 and 3. More specifically, these steps may relate to operations performed by the first material application unit 30.

[0062] In particular, following step 201 may be step 202. Step 202 may involve actuating a stencil 31, having one or more apertures 311, to be adjacent to the base 10.

[0063] In particular, following step 202 may be step 203. Step 203 may involve disposing or depositing first material 20 onto the stencil 30. In particular, the first material 20 may be supplied and deposited by the first material supply 33.

[0064] In particular, following step 203 may be step 204. Step 204 may involve actuating a squeegee 32 to spread the first material 20 across the stencil 10. While doing so, apertures 311 of the stencil 31 may be filled.

[0065] In particular, following step 204 may be step 205. Step 205 may involve actuating the stencil 31 to be lifted away from the base 10. p 206 with FIG. 4

[0066] With this, as per step 206 and as shown in FIG. 4, the base 10 shall now be formed with one or more first structures 21 thereon. These first structures 21 may be pillar-like formations on the base 10, wherein the first structures 21 may each have a volume that may correspond to a volume of the apertures 311 of the stencil 31.

[0067] Following step 206 may be step 207. Step 207 may involve providing the base 10, which has the first structures 21 thereon, to the first sinter unit 40.

[0068] Following step 207 may be step 208. Step 208 shall be described in relation to FIGS. 2 and 5. More specifically, step 208 may relate to operations performed by the first sinter unit 40. In particular, step 208 may involve heating the first structures 21 that are on the base 10 for them to dry or sinter, by a heating module 41. In particular, the heating module 41 shall heat the surroundings of the first structures 21.

[0069] With this, as per step 209 and as shown in FIG. 6, the base 10 shall now have one or more second structures 22 thereon, which are transformed from, or sintered from, the first structures 21. In particular, these second structures 22 may have shrunk, and each of them may have an overall volume that may be lesser than previous when each of them was in the form of the first structures 21, due to their particles becoming fused after being provided to the first sinter unit 40.

[0070] Following step 209 may be step 210. Step 210 may involve providing the base 10, which has the second structures 22 thereon, to the second sinter unit 50.

[0071] Steps 211 to 216 may be subsequent steps of Step 210. Steps 211 to 216 shall be described in relation to FIGS. 2 and 7. More specifically, these steps may relate to operations performed by the second sinter unit 50.

[0072] In particular, following step 210 may be step 211. Step 211 may involve positioning the base 10 for its second structures 22 to be in the proximity of the presser 511 of the thermal-pressure module 51.

[0073] In particular, following step 211 may be step 212. Step 212 may involve heating either one or both the presser 511 and the platform 512 for them to be at a preset temperature.

[0074] In particular, following step 212 may be step 213. Step 213 may involve actuating the film handler module 52 to position a film layer 522 to be in the proximity to the second structures 22 on the base 10. In particular, the film layer 522 may be supported by a support structure 521 in the form of a prepared tray. More specifically, the prepared tray is positioned for its film layer 522 to be between the presser 511 and the second structures 22 on the base 10.

[0075] In particular, following step 213 may be step 214. Step 214 may involve actuating the presser 511, which is heated to the preset temperature, to move in a first direction. The first direction may be a downward direction. Movement of the presser 511 along the first direction shall enable it to apply a pressure force against the film layer 522, as well as the second structures 22 on the base 10, with the film layer 522 being made to adhere between cavities 5111 of the presser 511 and the second structures 22. It is to be noted that the film layer 522 may further conform to the shape of the second structures 22 under the pressure force applied by the presser 511. Moreover, it is to be noted that the platform 512 shall substantially support the base 10 to withstand the pressure force applied by the presser 511.

[0076] In particular, following step 214 may be step 215. Step 215 may involve maintaining the pressure force applied by the presser 511 for a preset duration for the second structures 22 on the base 10 to sinter.

[0077] In particular, following step 215 may be step 216. Step 216 may involve actuating the presser 511 to move in a second direction. The second direction may be the opposite of the first direction, and it may be an upward direction. Movement of the presser 511 along the second direction shall enable it to relieve the pressure force applied against the film layer 522, as well as the second structures 22 on the base 10.

[0078] In particular, following step 216 may be step 217. Step 217 may involve removing the film layer 522 (i.e. the tray the film layer 522) from the proximity of the presser 511 and the second structures 22 on the base 10. The film layer 522 may be disposed or reused.

[0079] It is to be noted that, in relation to steps 211 to 216, the film layer 522 shall prevent the second structures 22 from adhering with the presser 511. As such, the overall shape of the second structures 22 may be substantially maintained or preserved during or after being pressed by the presser 511. Furthermore, the film layer 522 may also substantially allow second structures 22 to sinter and join to designated locations on the base 10, if any (e.g. contact pads, etc.).

[0080] It is to be noted that, in relation to steps 211 to 216, since the press surface of the presser 511 being coated with a non-stick or anti-stick coating, as the presser 511 disengages from the second structures 22, particle adhesion of the second structures 22 to the presser 511 is avoided. Hence, no bits/pieces of the second structures 22 will be stuck onto the presser 511, thereby maintaining the overall shape of the second structures 22.

[0081] With this, as per step 218 and as shown in FIG. 8, the base 10 shall now have one or more third structures 23 thereon, which are transformed from, or sintered from, the second structures 22. In particular, these third structures 23 may have further shrunk, and each of them may have an overall volume that may be lesser than when they were in the form of the second structures 22. This is due to the second sinter unit 50 further causing the particles of these structures to fuse and become compacted.

[0082] Following step 218 may be step 219. Step 219 may involve providing the base 10, having the third structures 23, to a second material application unit 60 for its third structures 23 to each be disposed or deposited with second material 61 thereupon.

[0083] Finally, following step 219 may be step 220. Step 220 shall be described in relation to FIGS. 2 and 9. More specifically, step 220 may involve providing the base 10, having the third structures 23, each with the second material 61 thereupon, to a cleaning unit 70, for them to be cleaned by one or more cleaners 71.

[0084] In relation to the system described as per FIG. 1, the steps described as per FIG. 2, and the other figures FIG. 3-9, it may be stated that the two or more sinter units (first sinter unit 40 and the second sinter unit 50) consecutively sinters the structures on the base 10 for them to eventually have a desired structural integrity in the form of third structures 23.

[0085] With this, a system and method for sintering structures on a base have been described. While it has been described that the invention is generally applicable to items or objects related to the semiconductor fabrication such as fabrication of copper pillars, it is to be noted that the application of the invention may further be generally applicable for other applications that involve sintering structures on a base.

[0086] The present disclosure includes as contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form, it is understood that the present disclosure of the preferred form has been made only by way of example and numerous changes in the details of the construction, combination and arrangements of parts may be resorted to without departing from the scope of the invention.