Film pasting method of substrate and preparation method of power device

Abstract

The invention provides a film pasting method of a substrate and a preparation method of a power device. According to the film pasting method, before the protective film is pasted, the filling material is preferentially arranged at the bottom corner position of the step, so that the slit between the protective film and the step can be filled with the filling material, the risk of the slit generated by the protective film at the step position due to poor fitting degree is reduced, and even the slit at the bottom corner position of the step can be eliminated; the chemical reagent is effectively prevented from permeating into the internal area of the substrate, the problem that the surface, attached with the protective film, in the substrate is in contact with the chemical reagent is solved, and the yield of products can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a substrate film pasting method and a power device preparation method. Background Art

[0002] Chemical plating is a new type of metal surface treatment technology. In many fields, chemical plating technology has replaced electroplating technology and become an environmentally friendly surface treatment process. For example, in the field of new energy vehicles, automotive IGBTs have high reliability requirements. The interconnection of IGBTs in traditional application fields usually adopts aluminum wire bonding, which has the problem of electromigration effect. Long-term use is prone to form voids, resulting in poor reliability of IGBTs. Therefore, in order to meet the high reliability requirements of the automotive field, the industry generally adopts chemical plating process to grow the surface metal of IGBT (for example, Ni / Au or Ni / Pd / Au, etc.) to meet the requirements of automotive IGBT interconnection.

[0003] Among them, chemical plating is a common process in semiconductor manufacturing, which can be divided into single-sided plating and double-sided plating. For the single-sided plating process, it is necessary to attach a protective film (for example, a UV film) to the surface of the substrate that does not need to be plated, so as to use the protective film to prevent the back of the substrate from contacting with the chemical agent, and then remove the protective film after the chemical plating is completed. For example, refer to Figure 1 As shown, before chemical plating is performed on one surface of the substrate 10, a Taiko thinning process is usually used to thin the other surface of the substrate 10. The Taiko thinning process does not thin the entire surface of the substrate 10, but only thins the middle part of the substrate 10, thereby forming a thicker support ring at the edge of the substrate 10. The support ring is usually called a Taiko ring; then, a protective film 30 is attached to the surface of the substrate 10, and the protective film 30 is attached to the entire surface.

[0004] However, in the case of Figure 1 During the chemical plating process of the substrate 10 with the protective film 30 attached, as the chemical agent circulates, the chemical agent is very likely to penetrate from the edge of the protective film 30. In particular, when attaching the protective film 30, since the Taiko ring protrudes relative to the middle part of the substrate 10 and a step difference is generated, the protective film 30 cannot be well attached to the substrate 10 at the step position, and a large slit 30a is easily generated. At this time, the chemical agent is easy to enter the slit 30a, and the chemical agent in the slit 30a will further diffuse inward along the protective film 30 to the internal area, which will have a certain impact on the appearance of the product and the reliability of application. Summary of the invention

[0005] One of the purposes of the present invention is to provide a film-attaching method for a substrate, so as to solve the problem that the film-attaching method in the prior art is prone to chemical reagent infiltration in the subsequent manufacturing process.

[0006] In order to solve the above technical problems, the present invention provides a method for laminating a substrate, comprising: providing a substrate, wherein an edge ring area and an internal area surrounded by the edge ring area are defined in the substrate, and a surface of the edge ring area protrudes by at least one step relative to a surface of the internal area; a filling material is arranged at a bottom corner position of the step; and a protective film is attached to the surface of the substrate, wherein the protective film is attached to the surface of the internal area and covers the filling material until it extends to cover the edge ring area.

[0007] Optionally, the filling material is adhesive and adhered to the bottom corner of the step.

[0008] Optionally, the viscosity of the filling material is lower than the viscosity of the protective film.

[0009] Optionally, the filling material is a plastic material. And after attaching the protective film, the method further includes: performing a lamination process to attach the protective film to the substrate and causing the filling material to deform under pressure to adapt to the morphology of the step and the protective film.

[0010] Optionally, the method for setting the filling material includes: spraying a first fluid material to a bottom corner position of the step, and performing a curing process to solidify the first fluid material.

[0011] Optionally, the filling material is hot-melt glue or thermosetting glue.

[0012] Optionally, the method of setting the filling material and attaching the protective film includes: spraying a first fluid material to the bottom corner of the step; covering the protective film on the surface of the substrate, and performing a lamination process to attach the protective film to the substrate; and performing a curing process to solidify the first fluid material.

[0013] Optionally, the film attaching method further includes: providing a sealing material at the end of the protective film to seal the end of the protective film.

[0014] Optionally, the method of setting the sealing material includes: spraying a second fluid material onto an end portion of the protective film, and performing a curing process to solidify the second fluid material.

[0015] Optionally, the fluidity of the sealing material is lower than the fluidity of the filling material.

[0016] Another object of the present invention is to provide a method for preparing a power device, comprising: using the film attaching method as described above to attach a protective film on the first surface of a substrate; performing a chemical plating process to form a chemically plated metal on the second surface of the substrate; and removing the protective film.

[0017] Optionally, when the protective film is removed, the protective film also drives the filling material at the bottom corner of the step to be removed.

[0018] In the film-laminating method for a substrate provided by the present invention, before attaching the protective film, a filling material is preferentially arranged at the bottom corner position of the step, so that when attaching the protective film, the slit between the protective film and the step can be filled with the filling material accordingly, thereby reducing the risk of slits caused by poor fitting of the protective film at the step position, and even eliminating the slits at the bottom corner position of the step, effectively blocking chemical reagents from penetrating into the internal area of ​​the substrate, effectively alleviating the problem of contact between the surface of the substrate to which the protective film is attached and the chemical reagents, and helping to improve the yield of the product.

[0019] Furthermore, a sealing material may be provided at the end of the protective film to seal the end of the protective film, so as to prevent the end of the protective film from being washed away by chemical reagents and increase the difficulty of chemical reagents penetrating. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a substrate with a protective film attached.

[0021] Figure 2 The figure is a schematic flow chart of a method for laminating a substrate in one embodiment of the present invention.

[0022] Figure 3-Figure 6 It is a schematic diagram of the substrate in the film-attaching process in the first embodiment of the present invention.

[0023] Figure 7 It is a schematic diagram of the substrate in the second embodiment of the present invention after film bonding.

[0024] The reference numerals are as follows:

[0025] 10 / 100-substrate;

[0026] 100A-marginal ring region;

[0027] 100B - internal area;

[0028] 200-filling material;

[0029] 30 / 300-protective film;

[0030] 400- Sealing material. DETAILED DESCRIPTION

[0031] The core idea of ​​the present invention is to provide a film-attaching method for a substrate, in which the corners of the steps are filled with materials to reduce or even avoid the generation of slits under the protective film, thereby reducing the risk of chemical reagents penetrating into the slits and further diffusing into the inner area of ​​the substrate, thereby improving the protection of the substrate. Figure 2 As shown, a film attaching method for a substrate in one embodiment of the present invention includes the following steps.

[0032] Step S100 , providing a substrate, wherein an edge ring area and an inner area surrounded by the edge ring area are defined in the substrate, and a surface of the edge ring area protrudes by at least one step relative to a surface of the inner area.

[0033] Step S200: placing a filling material at a bottom corner of the step.

[0034] Step S300 , attaching a protective film on the surface of the substrate, wherein the protective film is attached to the surface of the inner region and covers the filling material until it extends to cover the edge ring region.

[0035] That is, in the film-sticking method provided by the present invention, before attaching the protective film, a filling material (such as a sprayable filling material) is preferentially set at the bottom corner position of the step. The filling material can fill the slits at the corner position of the protective film due to poor fitting, thereby reducing the slits between the protective film and the bottom corner position of the step, and even eliminating the slits at the bottom corner position, thereby effectively blocking chemical reagents from penetrating into the internal area of ​​the substrate.

[0036] Furthermore, a sealing material may be provided at the end of the protective film to seal the end of the protective film, so as to prevent the end of the protective film from being washed away by chemical reagents and increase the difficulty of chemical reagents penetrating.

[0037] The following is a further detailed description of the film-attaching method for the substrate and the preparation method of the power device proposed in the present invention in conjunction with specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. It should be recognized that relative terms such as "above", "below", "top", "bottom", "above" and "below" shown in the drawings can be used to describe the relationship between various elements. These relative terms are intended to cover different orientations of elements other than the orientations depicted in the drawings. For example, if the device is inverted relative to the view in the drawing, an element described as being "above" another element will now be below the element.

[0038] <Example 1>

[0039] In step S100, refer to Figure 3 As shown, a substrate 100 is provided, and the substrate 100 includes, for example, a wafer. The substrate 100 has a first surface and a second surface opposite to each other, one of the first surface and the second surface is a back surface, and the other surface is a front surface. In this embodiment, the front surface of the substrate 100 is a surface to be chemically plated, and the back surface is a surface to be attached with a protective film.

[0040] Furthermore, the substrate 100 is defined with an edge ring region 100A and an inner region 100B surrounded by the edge ring region, and a semiconductor device may be formed in the inner region 100B, such as a power device, and the power device may further include an IGBT device, etc. Also, the surface of the edge ring region 100A (specifically, the surface to be attached with a protective film, such as the second surface) protrudes at least one step relative to the surface of the inner region 100B, Figure 3 In the example, the surface of the edge ring area 100A protrudes one step relative to the surface of the inner area 100B. However, in other examples, the surface of the edge ring area 100A can also protrude at least two steps, and the step heights of the at least two steps in the edge ring area 100A increase step by step from the inner ring to the outer ring.

[0041] In a specific example, the method of forming the surface of the edge ring area 100A to protrude at least one step relative to the surface of the inner area 100B may include: performing at least one thinning process (e.g., Taiko thinning process) on the surface of the substrate 100, the thinning area is smaller than the substrate area, and only the inner area 100B of the substrate is thinned, so that the thickness of the inner area 100B is reduced and recessed relative to the edge ring area 100A, and correspondingly the surface of the edge ring area 100A is protruded to present a ring structure (e.g., a Taiko ring). The thinning process used may include, for example, a mechanical grinding process, that is, grinding the surface of the substrate 100 using a mechanical grinding process to achieve the thinning process.

[0042] In step S200, continue to refer to Figure 3 As shown, a filling material 200 is disposed at the bottom corner of the step. The disposition method can be various according to the material selection, such as coating the filling material, placing the filling material, etc. The filling material 200 is used to fill the gap between the protective film attached later and the bottom corner. The filling material 200 can be any material as long as it can play a filling role, for example, it can be formed of materials such as polyimide, rubber or resin, or other materials that can fill the bottom corner of the step.

[0043] In one embodiment, the filling material 200 is a viscous glue, so that it can adhere to the bottom corner of the step, and further adhere to the protective film after the protective film is attached, so that the filling material does not move, thereby better filling the narrow space at the bottom corner of the step. Furthermore, the viscosity of the filling material 200 on the substrate 100 is lower than the viscosity of the subsequently attached protective film on the substrate, so that when the protective film is removed, the filling material 200 can be taken away by the protective film at the same time, simplifying the film tearing process. In a specific example, the viscous glue is, for example, polyimide, resin glue, hot melt glue, thermosetting glue, UV glue or organic silicone.

[0044] For example, the filling material 200 used may be a plastic material, so that the filling material 200 can adapt to the morphology of the step and avoid generating a large stress on the substrate. In particular, in the subsequent process of attaching the protective film, when the protective film needs to be laminated, the filling material 200 can deform with the morphology of the laminated body, adapt to the shape of the slit and fill the slit, so as to more fully fill the slit between the protective film and the step and avoid the existence of possible slits.

[0045] Exemplarily, the method of setting the filling material 200 may include: spraying the first fluid material to the bottom corner of the step, and forming the filling material 200 after the first fluid material is solidified. The first fluid material may, for example, be naturally solidified to form the filling material 200; or, the first fluid material needs to be solidified to form the filling material 200; or, the first fluid material may be naturally solidified or solidified to form the filling material 200. For example, the filling material 200 may be a hot melt adhesive, that is, it has strong fluidity at a higher temperature, and its fluidity decreases after cooling to achieve solidification; or, the filling material 200 may also be a thermosetting adhesive, that is, it has strong fluidity at a lower temperature, and its fluidity decreases after heating to achieve solidification.

[0046] Specifically, before the first fluid material solidifies, it can adaptively fill the bottom corner area of ​​the step due to its strong fluidity, so that the morphology of the filling material can better match the morphology of the bottom corner. In a specific example, when the first fluid material is sprayed by a sprayer, the shape of the spray port of the sprayer can also be adjusted so that the shape of the first fluid material sprayed matches the shape of the bottom corner, for example, the shape of the first fluid material sprayed can be close to a triangle, so as to fill the space at the bottom corner.

[0047] In step S300, refer to Figure 4 and Figure 5 As shown, a protection film 300 is attached to the surface of the substrate 100 , and the protection film 300 is attached to the inner area 100B of the substrate and covers the filling material 200 at the corner position until it extends to cover the edge ring area 100A.

[0048] In a specific example, the method of attaching the protective film 300 may include: first, referring to Figure 4 As shown, the protective film 300 is covered on the substrate 100. At this time, the protective film 300 located at the step position covers the filling material 200 and overlaps the step without completely fitting the step; Figure 5 As shown, a lamination process is performed to apply pressure to the protective film 300 in a direction toward the substrate 100, so that the protective film 300 adheres to the substrate 100. In this process, the lamination body can be used to apply pressure to the surface of the inner area 100B, the side wall of the step and the top surface of the step (i.e., the surface of the edge ring area 100A), so that the protective film 300 has a high degree of fit on the substrate 200. It should be noted that since the filling material 200 used is a plastic material, the filling material 200 can be deformed under pressure to adapt to the morphology of the protective film and the step after being pressed by the lamination body, so that the slits generated by the protective film 300 at the step position can be more fully filled.

[0049] In the above example, the method of setting the filling material 200 and attaching the protective film 300 is: spraying the first fluid material to the bottom corner of the step, and performing a curing treatment to form the filling material 200; thereafter, covering the surface of the substrate 100 with the protective film 300, and performing a lamination treatment to attach the protective film 300 to the substrate 100.

[0050] However, in other examples, before the first fluid material is solidified, the step of attaching the protective film 300 can be implemented, and the protective film 300 can be subjected to a lamination process, and then a curing process can be performed to solidify the first fluid material to form the filling material 200. That is, the method of setting the filling material 200 and attaching the protective film 300 includes: spraying the first fluid material to the bottom corner position of the step; then, covering the surface of the substrate 100 with the protective film 300, and performing a lamination process to attach the protective film 300 to the substrate 100. During the lamination process, the first fluid material can better adapt to the bottom corner morphology of the step under the action of the lamination body, so as to more fully fill the slit generated by the protective film 300 at the step position, and achieve better filling of the space at the bottom corner of the step; then, a curing process is performed to solidify the first fluid material to form the filling material 200.

[0051] For further details, please refer to Figure 6As shown, after attaching the protective film 300, it also includes: setting a sealing material at the end of the protective film 300, for example, applying a sealing material 400 to seal the end of the protective film 300. In this way, the problem that the end of the protective film 300 is easily washed away by chemical reagents can be effectively improved, and the chemical reagents are prevented from penetrating from the end. In a specific example, the sealing material 400 can be a viscous material to facilitate sealing and adhering the end of the protective film 300 to the substrate.

[0052] The sealing material 400 may be formed of the same material as the filling material 200, for example, the sealing material 400 may be formed of materials such as polyimide, rubber or resin; or, the sealing material 400 may be formed of a material different from the filling material 200. In one embodiment, the sealing material 400 may be a viscous material, such as an adhesive, so as to facilitate sealing and adhering the end of the protective film 300 to the substrate 100 to achieve better sealing. In a specific example, the adhesive is, for example, a resin adhesive, a hot melt adhesive, a thermosetting adhesive, a UV adhesive or an organic silicone.

[0053] In one embodiment, the method for forming the sealing material 400 includes, for example, spraying the second fluid material to the end of the protective film 300, and forming the sealing material 400 after the second fluid material is cured. The second fluid material, for example, can be naturally cured to form the sealing material 400; or, the second fluid material needs to be cured to form the sealing material 400; or, the second fluid material can be cured naturally or cured to form the sealing material 400. For example, the sealing material 400 can be a hot melt adhesive, that is, it has strong fluidity at a higher temperature, and its fluidity decreases after cooling to achieve curing; or, the sealing material 400 can also be a thermosetting adhesive, that is, it has strong fluidity at a lower temperature, and its fluidity decreases after heating to achieve curing.

[0054] In this example, the second fluid material with strong fluidity is sprayed to the end of the protective film 300, so that the morphology of the formed sealing material 400 fits the end morphology of the protective film 300, so as to achieve sealing protection of the end of the protective film 300. In a specific example, when the second fluid material is sprayed by a sprayer, the shape of the spray port of the sprayer can also be adjusted so that the shape of the sprayed second fluid material matches the shape of the end of the protective film 300, so as to better cover the end of the protective film 300.

[0055] Exemplarily, the fluidity of the sealing material 400 may be further lower than the fluidity of the filling material 200 to ensure that the sealing material 400 can be firmly adhered to the end of the protective film 300, while the filling material 200 with relatively greater fluidity can more fully fill the bottom corner gap of the step.

[0056] <Example 2>

[0057] The difference from the first embodiment is that the protective film in this embodiment is not only attached to the first surface of the substrate, but also further extends to the outer wall of the substrate to increase the coverage area of ​​the protective film on the substrate and improve the protection of the substrate.

[0058] Specific reference Figure 7 As shown, in this embodiment, the protective film 300 is attached to the surface of the inner area 100B of the substrate and the surface of the edge ring area 100A, and further extends to the outer side wall of the substrate 100. This is to prevent the infiltration of chemical agents. In this example, the sealing material 400 can also be sprayed on the end of the protective film 300. In this case, the sealing material 400 is formed on the outer side wall of the substrate 100 to seal and protect the end of the protective film 300.

[0059] The present disclosure also provides a method for preparing a power device, comprising: using the film attaching method as described above to attach a protective film on the first surface of a substrate; performing a chemical plating process to form a chemically plated metal on the second surface of the substrate; and, after completing the chemical plating process, removing the protective film.

[0060] Specifically, the power device includes, for example, an IGBT device, and in this case, for example, a chemically plated metal can be formed on the front side (corresponding to the second surface as described above) of a substrate (such as a wafer, etc.) by a chemical plating process. Before attaching the protective film, the back side (corresponding to the first surface as described above) of the substrate is processed so that the first surface of the edge ring region protrudes at least one step relative to the first surface of the inner region. On this basis, a protective film is attached to at least the first surface of the substrate.

[0061] Specific combination Figure 6 and Figure 7 As shown, before attaching the protective film 300, the bottom corner of the step is filled with a filling material 200, which improves the fit of the protective film 300 on the substrate 100 and avoids the formation of a slit between the protective film 300 and the substrate 100 at the bottom corner. In this way, when performing the chemical plating process, the problem of the chemical plating solution infiltrating into the slit and further diffusing into the interior of the substrate can be effectively improved. In an optional solution, the end of the protective film 300 can also be covered with a sealing material 400 to reduce the risk of the end of the protective film being washed open by the chemical plating solution, further solving the problem of chemical plating seepage, and greatly improving the yield of the product.

[0062] Furthermore, when removing the protective film 300, the sealing material 400 can be used as a fulcrum to drive the protective film 300 to be removed from the substrate 100. As described above, the viscosity of the protective film 300 is greater than that of the filling material 200, so the protective film 300 can drive the filling material 200 to be removed, simplifying the film peeling process. Of course, in other examples, the viscous material 400 can be removed first, and then the protective film 300 can be peeled off, and the filling material 200 can be removed at the same time during this process.

[0063] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. Although the present invention has been disclosed as above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified to equivalent embodiments of equivalent changes. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

[0064] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, rather than to represent the logical relationship or sequential relationship between the various components, elements, steps, etc. It should also be recognized that the terms described herein are only used to describe specific embodiments, rather than to limit the scope of the present invention. It must be noted that the singular forms "one" and "a kind" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or", rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite meaning.

Claims

1. A method for laminating a substrate, characterized in that: include: Providing a substrate, wherein an edge ring region and an inner region surrounded by the edge ring region are defined in the substrate, and a surface of the edge ring region protrudes at least one step relative to a surface of the inner region; Disposing a filling material at the bottom corner of the step; as well as, A protection film is attached to the surface of the substrate, the protection film is attached to the surface of the inner region and covers the filling material until it extends to cover the edge ring region.

2. The film attaching method for a substrate as claimed in claim 1, characterized in that: The filling material is a sticky glue and is adhered to the bottom corner of the step.

3. The film attaching method for a substrate as claimed in claim 2, characterized in that: The viscosity of the filling material is lower than the viscosity of the protection film.

4. The film attaching method for a substrate as claimed in claim 1, characterized in that: The filling material is a plastic material; as well as, After the protective film is attached, the method further includes: performing a lamination process to attach the protective film to the substrate, and causing the filling material to deform under pressure to adapt to the morphology of the step and the protective film.

5. The film attaching method for a substrate as claimed in claim 1, characterized in that: The method of setting the filling material comprises: A first fluid material is sprayed to the bottom corner of the step, and a curing process is performed to solidify the first fluid material.

6. The film attaching method for a substrate as claimed in claim 5, characterized in that: The filling material is hot-melt glue or thermosetting glue.

7. The film attaching method for a substrate as claimed in claim 5, characterized in that: The method of setting the filling material and attaching the protective film includes: Spraying the first fluid material to the bottom corner of the step; covering the protective film on the surface of the substrate, and performing a lamination process to attach the protective film to the substrate; and, A curing process is performed to solidify the first fluid material.

8. The film attaching method for a substrate as claimed in claim 1, characterized in that: Also includes: A sealing material is provided at the end of the protective film to seal the end of the protective film.

9. The film attaching method for a substrate as claimed in claim 8, characterized in that: The method of providing the sealing material comprises: A second fluid material is sprayed onto an end portion of the protective film, and a curing process is performed to cure the second fluid material.

10. The film attaching method for a substrate as claimed in claim 8, characterized in that: The fluidity of the sealing material is lower than the fluidity of the filling material.

11. A method for preparing a power device, characterized in that: include: Adopting the film attaching method as described in any one of claims 1 to 10, attaching the protective film on the first surface of the substrate; performing a chemical plating process to form a chemically plated metal on the second surface of the substrate; and removing the protective film.

12. The method for preparing a power device according to claim 11, characterized in that: When the protective film is removed, the protective film also drives the filling material to be removed.

Images