Method for reducing photoresist usage and application thereof

Abstract

The present invention provides a method for reducing photoresist usage, comprising the following steps: providing a substrate, forming a first photoresist wet film on the substrate; heating the first photoresist wet film to obtain a first photoresist layer; printing on the first photoresist layer using a first printing screen to obtain a second photoresist wet film; heating the second photoresist wet film to obtain a second photoresist layer, wherein the second photoresist layer has openings; and aligning and exposing the overlapping area of the second photoresist layer and the first photoresist layer using a photomask, and then developing the area so that the developed second photoresist layer and the developed first photoresist layer together form a patterned photoresist layer, wherein the patterned photoresist layer has pores. The present invention can reduce the amount of photoresist used. The present invention also provides an application of the method for reducing photoresist usage in a semiconductor advanced packaging process.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing and photovoltaic cells, and in particular to a method for reducing the amount of photoresist used and an application thereof. Background Art

[0002] Photoresist is often used in semiconductor manufacturing and photovoltaic cell technology. However, the high cost of photoresist leads to high production costs. Therefore, reducing the amount of photoresist used is a feasible method to reduce production costs.

[0003] In advanced semiconductor packaging, the Re-Distribution Layer (RDL), a core technology in wafer-level packaging, provides electrical extension and interconnection in the XY plane. The RDL fabrication process involves first applying a layer of photoresist to the entire substrate surface and drying it. The dried photoresist is then exposed and developed to create pores. Finally, copper wires of a certain thickness are formed within the pores through electroplating. The photoresist in the unexposed areas acts as a protective layer, preventing penetration of the plating solution during the subsequent electroplating process.

[0004] However, in the aforementioned RDL (redistribution layer) fabrication process, copper lines occupy less than 30% of the total substrate area. This means that the photoresist is actually performing its photolithographic function in less than 30% of the area. The photoresist in the remaining non-exposed areas serves only as a barrier during the electroplating process and is subsequently removed. This undoubtedly increases chip manufacturing costs. Furthermore, since the copper lines in the RDL are typically 5μm to 10μm high, the corresponding photoresist coating thickness ranges from 10μm to 15μm. Furthermore, in the Bμmp process, the copper pillar height ranges from 40μm to 80μm, corresponding to a photoresist coating thickness of 60μm to 100μm. This further increases chip manufacturing costs. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for reducing the amount of photoresist used. The method can significantly reduce the amount of photoresist used without affecting the use effect of the photoresist layer, thereby reducing production costs.

[0006] The present invention also provides the application of the method for reducing the amount of photoresist used in a semiconductor advanced packaging process, in particular, the application of the method for reducing the amount of photoresist used in an RDL redistribution layer.

[0007] The present invention provides a method for reducing the amount of photoresist used, comprising the following steps:

[0008] providing a substrate, and forming a first photoresist wet film on the substrate;

[0009] heating the first photoresist wet film to obtain a first photoresist layer;

[0010] Printing on the first photoresist layer through a first printing screen to obtain a second photoresist wet film;

[0011] heating the second photoresist wet film to obtain a second photoresist layer, wherein the second photoresist layer has an opening, and a portion of the first photoresist layer is exposed in the opening; and

[0012] The overlapping area of the second photoresist layer and the first photoresist layer is aligned and exposed through a photomask, and then developed, so that the developed second photoresist layer and the developed first photoresist layer together form a patterned photoresist layer, wherein the patterned photoresist layer has pores, and part of the substrate is exposed to the pores.

[0013] In some embodiments of the present invention, the method includes at least one of the following (1) to (2):

[0014] (1) The thickness of the first photoresist wet film is 8 μm to 10 μm;

[0015] (2) The thickness of the second photoresist wet film is 30 μm to 50 μm.

[0016] In some embodiments of the present invention, the method includes at least one of the following (1) to (2):

[0017] (1) Heating the first photoresist wet film specifically includes the following steps:

[0018] baking the first photoresist wet film on a side of the substrate away from the first photoresist wet film;

[0019] The baking temperature is 80°C to 90°C, and the baking time is 60s to 120s.

[0020] (2) heating the second photoresist wet film specifically comprises the following steps:

[0021] baking the second photoresist wet film on a side of the substrate away from the second photoresist wet film;

[0022] The baking temperature is 90° C. to 110° C., and the baking time is 180s to 240s.

[0023] In some embodiments of the present invention, forming a first photoresist wet film on the substrate specifically includes the following steps:

[0024] The first photoresist wet film is obtained by printing on one entire surface of the substrate using a full-hole printing screen.

[0025] In some embodiments of the present invention, printing on the entire surface of the substrate using a full-hole printing screen specifically includes the following steps:

[0026] Laminating the full-through-hole printing screen having the same shape and size as the substrate to one surface of the substrate, and aligning the full-through-hole printing screen with the substrate through alignment marks; and

[0027] The photoresist is coated on the full-hole printing screen, and a scraper is pulled on the full-hole printing screen to squeeze the photoresist so that the photoresist passes through the mesh of the full-hole printing screen and reaches the substrate.

[0028] In some embodiments of the present invention, printing on the first photoresist layer using a first printing screen specifically includes the following steps:

[0029] Laminating the first printing screen having the same shape and size as the substrate on the surface of the first photoresist layer, and aligning the first printing screen with the first photoresist layer through alignment marks; and

[0030] A photoresist is coated on the first printing screen, and a scraper is pulled on the first printing screen to squeeze the photoresist so that the photoresist passes through the mesh of the first printing screen and reaches the first photoresist layer.

[0031] In some embodiments of the present invention, the printing screen is divided into a full-through-hole printing screen and a partial-through-hole printing screen.

[0032] The present invention uses the fully transparent printing screen to prepare the first photoresist wet film, which can achieve the use of a photoresist wet film with a relatively low thickness, thereby completely covering structures of different heights on the substrate and blocking the electroplating solution in the subsequent process to protect the substrate.

[0033] The present invention uses the partially through-hole printing screen (i.e., the first printing screen) to prepare the second photoresist wet film, which can achieve photoresist coating in areas where electroplating process is required on a high-thickness photoresist layer, thereby achieving the high thickness requirement of the photoresist and providing support for subsequent electroplating process.

[0034] Therefore, the present invention can use different printing screens in a targeted manner according to different needs, thereby effectively controlling the amount of photoresist used.

[0035] The present invention provides a method for reducing the amount of photoresist used, comprising the following steps:

[0036] Providing a substrate, and forming a photoresist wet film on the substrate using a first printing screen;

[0037] heating the photoresist wet film to obtain a photoresist layer, wherein the photoresist layer has openings, and a portion of the substrate is exposed to the openings;

[0038] forming a resin wet film in the openings by a second printing screen;

[0039] heating the resin wet film to obtain a resin layer; and

[0040] The area where the photoresist layer is located is subjected to alignment exposure and then developed to obtain a patterned photoresist layer, wherein the patterned photoresist layer has pores, and a portion of the substrate is exposed in the pores.

[0041] In some embodiments of the present invention, the method includes at least one of the following (1) to (2):

[0042] (1) The thickness of the photoresist wet film is 40 μm to 50 μm;

[0043] (2) The thickness of the resin wet film is 8 μm to 10 μm.

[0044] In some embodiments of the present invention, the method includes at least one of the following (1) to (2):

[0045] (1) Heating the photoresist wet film specifically comprises the following steps:

[0046] baking the photoresist wet film on a side of the substrate away from the photoresist wet film;

[0047] The baking temperature is 80°C to 90°C, and the baking time is 180s to 240s.

[0048] (2) Heating the resin wet film specifically comprises the following steps:

[0049] baking the resin wet film on a side of the substrate away from the resin wet film;

[0050] The baking temperature is 90° C. to 110° C., and the baking time is 180s to 240s.

[0051] In some embodiments of the present invention, the first printing screen includes a first covering area and a first mesh area, the second printing screen includes a second covering area and a second mesh area, and the second covering area corresponds to the position of the first mesh area, and the second mesh area corresponds to the position of the first covering area.

[0052] In some embodiments of the present invention, the area of the second covering area is larger than the area of the first mesh area.

[0053] In some embodiments of the present invention, the method includes at least one of the following (1) to (2):

[0054] (1) forming a photoresist wet film on the substrate by a first printing screen specifically comprises the following steps:

[0055] Laminating the first printing screen having the same shape and size as the substrate to one surface of the substrate, and aligning the first printing screen with the substrate through alignment marks; and

[0056] Applying photoresist on the first printing screen, and squeezing the photoresist by pulling a scraper on the first printing screen so that the photoresist passes through the mesh of the first printing screen and reaches the substrate;

[0057] (2) forming a resin wet film in the opening by a second printing screen specifically comprises the following steps:

[0058] Laminating a second printing screen having the same shape and size as the substrate to one surface of the substrate, and aligning the second printing screen with the substrate through alignment marks; and

[0059] A photoresist is coated on the second printing screen, and a scraper is pulled on the second printing screen to squeeze the photoresist so that the photoresist passes through the mesh of the second printing screen and reaches the opening.

[0060] In some embodiments of the present invention, the printing screen may have an optional mesh size of 100-800 meshes.

[0061] In some embodiments of the present invention, the printing screen may have an optional mesh size of 100-500 meshes.

[0062] In some embodiments of the present invention, the printing screen may have an optional mesh size of 100 mesh, 150 mesh, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh or 500 mesh.

[0063] The present invention also provides an application of the method for reducing the amount of photoresist used in a semiconductor advanced packaging process, in particular, an application of the method for reducing the amount of photoresist used in an RDL redistribution layer.

[0064] The present invention provides two methods for reducing the amount of photoresist used. Multiple layers of colloids of different thicknesses are prepared by using different types of printing screens. A photoresist layer of lower thickness or a resin layer of lower cost is used in non-exposure areas that do not require photosensitivity. The adhesive layer coated by the method of the present invention significantly reduces the amount of photoresist used while ensuring the use effect of the photoresist layer, thereby reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 A cross-sectional view of a substrate provided in accordance with an embodiment of the present invention;

[0066] Figure 2 For Figure 1 A cross-sectional view of the substrate after forming a first photoresist wet film;

[0067] Figure 3 A top view of a fully transparent printing screen provided in one embodiment of the present invention;

[0068] Figure 4 For the general Figure 2 A cross-sectional view of the first photoresist wet film after heating is shown;

[0069] Figure 5 For Figure 4 A cross-sectional view of the first photoresist layer after the first printing screen is attached thereto;

[0070] Figure 6 To pass Figure 5 The cross-sectional view of the first printing screen after printing and forming a second photoresist wet film on the first photoresist layer;

[0071] Figure 7 For the general Figure 6 A cross-sectional view showing the first printing screen removed;

[0072] Figure 8 For the general Figure 7 A cross-sectional view of the second photoresist wet film after heating is shown;

[0073] Figure 9 For Figure 8 A cross-sectional view of the overlapped area of the second photoresist layer and the first photoresist layer when alignment exposure is performed;

[0074] Figure 10 For Figure 9 A cross-sectional view of the second photoresist layer after exposure and the first photoresist layer after development;

[0075] Figure 11 A cross-sectional view of a substrate provided in accordance with another embodiment of the present invention;

[0076] Figure 12 For Figure 11 A cross-sectional view of the substrate after the first printing screen is attached to the substrate;

[0077] Figure 13 To pass Figure 12 A cross-sectional view of the first printing screen after printing to form a photoresist wet film on a substrate;

[0078] Figure 14 for Figure 13 A top view of the first printing screen is shown;

[0079] Figure 15 For the general Figure 13 A cross-sectional view of the wet photoresist film after heating is shown;

[0080] Figure 16 For Figure 15 A cross-sectional view of the substrate after the second printing screen is attached to the substrate;

[0081] Figure 17 To pass Figure 16 A cross-sectional view of the second printing screen after printing to form a resin wet film in the openings;

[0082] Figure 18 for Figure 17 A top view of the second printing screen is shown;

[0083] Figure 19 For the general Figure 17 A cross-sectional view of the printing screen after removal and heating of the resin wet film is shown;

[0084] Figure 20 For Figure 19 A cross-sectional view of the region where the photoresist layer is located when alignment exposure is performed;

[0085] Figure 21 For Figure 20 The cross-sectional view of the exposed photoresist layer after development is shown.

[0086] Figure numerals: 10, 11-substrate; 20-first photoresist wet film; 21, 22-first photoresist layer; 23-photoresist; 30-full-hole printing screen; 31, 32-first printing screen; 321-first covering area; 322-first mesh area; 33-second printing screen; 331-second covering area; 332-second mesh area; 40-second photoresist wet film; 41-second photoresist layer; 42-resin wet film; 43-resin layer; 231, 411-opening; 50, 51-patterned photoresist layer; 501, 511-pores; 60, 61-photomask; 601, 611-through hole. DETAILED DESCRIPTION

[0087] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0088] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0089] At least one embodiment of the present invention provides a method for reducing photoresist usage, comprising the following steps:

[0090] Step S11, please refer to Figure 1 , providing a substrate 10.

[0091] In one embodiment, the substrate 10 may be a wafer substrate. In another embodiment, the substrate 10 may also be any substrate that needs to be provided with metal structure lines (such as copper lines).

[0092] Step S12, please refer to Figure 2 , forming a first photoresist wet film 20 on the substrate 10 .

[0093] The substrate 10 includes a front surface and a back surface opposite to the front surface, and the first photoresist wet film 20 is formed on the entire front surface, that is, the first photoresist wet film 20 completely covers the front surface.

[0094] In one embodiment, the first photoresist wet film 20 may be formed by screen printing. In another embodiment, the first photoresist wet film 20 may be formed by spin coating, dip coating, spray coating, roller coating, etc.

[0095] When the first photoresist wet film 20 is formed by screen printing, the specific steps are as follows:

[0096] (1) Place a fully perforated printing screen 30 (e.g. Figure 3 As shown in FIG. 1 , the fully transparent printing screen 30 is tightly attached to the front surface of the substrate 10 , and the full-hole printing screen 30 is strictly aligned with the substrate 10 through alignment marks.

[0097] In order to prevent misalignment between the full-through-hole printing screen 30 and the substrate 10 , 8 to 12 alignment marking points may be provided between the full-through-hole printing screen 30 and the substrate 10 .

[0098] In one embodiment, the mesh number of the full-through-hole printing screen 30 may be about 500 meshes.

[0099] (2) A certain amount of photoresist is coated on the fully transparent printing screen 30, and a scraper is pulled on the fully transparent printing screen 30 to squeeze the photoresist so that it passes through the mesh of the screen of the fully transparent printing screen 30 and reaches the substrate 10 below the fully transparent printing screen 30, thereby obtaining the first photoresist wet film 20.

[0100] The thickness of the first photoresist wet film 20 can be controlled by controlling the number and aperture of the screen mesh in the fully transparent printing screen 30. It will be appreciated that the fewer the number of screen meshes and the larger the aperture in the fully transparent printing screen 30, the greater the amount of photoresist that flows onto the substrate 10 in the same amount of time, and the thicker the resulting first photoresist wet film 20. This approach allows the preparation of first photoresist wet films 20 of varying thicknesses.

[0101] In one embodiment, the thickness of the first photoresist wet film 20 is 8 μm to 10 μm.

[0102] In one embodiment, the photoresist may be a positive photoresist. Specifically, the photoresist may be a phenolic resin-photosensitizer PAC system photoresist. Because the photoresist subsequently needs to be exposed to developer and plating solutions, a positive photoresist is required as a barrier. For example, the positive photoresist may be KX150, a positive photoresist produced by Shanghai Feikai Materials Technology Co., Ltd.

[0103] In one embodiment, the photoresist comprises the following components, by weight: 70% to 80% of a solvent, 15% to 25% of a phenolic resin, 3% to 6% of a photosensitizer, and 0.1% to 2% of an additive.

[0104] Step S13, please refer to Figure 4 , heating the first photoresist wet film 20 to obtain a first photoresist layer 21.

[0105] Specifically, the first photoresist wet film 20 is baked on the back side of the substrate 10 using a hot plate to obtain the first photoresist layer 21. In another embodiment, the substrate 10 and the first photoresist wet film 20 can also be placed in an oven to bake the first photoresist wet film 20 to obtain the first photoresist layer 21.

[0106] In one embodiment, the baking temperature is 80° C. to 90° C. In one embodiment, the baking time is 60 seconds to 120 seconds.

[0107] Step S14, please refer to Figure 5 and Figure 6 , a second photoresist wet film 40 is obtained by printing on the first photoresist layer 21 through a first printing screen 31 .

[0108] The first printing screen 31 is a partially perforated printing screen with a pattern. That is, the first printing screen 31 includes a masking area and a mesh area. Specifically, the first printing screen 31, which has the same shape and size as the substrate 10, is tightly attached to the first photoresist layer 21. The first printing screen 31 and the first photoresist layer 21 are strictly aligned using alignment marks. A certain amount of photoresist is then applied to the first printing screen 31. A scraper is pulled across the first printing screen 31 to squeeze the photoresist through the holes in the first printing screen 31 and onto the first photoresist layer 21 below the first printing screen 31, thereby forming the second photoresist wet film 40.

[0109] In one embodiment, the mesh size of the first printing screen 31 may be about 150 meshes.

[0110] The thickness of the second photoresist wet film 40 can be controlled by controlling the number and aperture of the screen mesh in the aperture region of the first printing screen 31. It will be appreciated that the fewer the number of screen mesh holes and the larger the aperture diameter in the aperture region of the first printing screen 31, the greater the amount of photoresist that flows onto the first photoresist layer 21 in the same amount of time, and the thicker the resulting second photoresist wet film 40. This approach allows the preparation of second photoresist wet films 40 of varying thicknesses.

[0111] In one embodiment, the thickness of the second photoresist wet film 40 is 30 μm to 50 μm. In another embodiment, the thickness of the second photoresist wet film 40 may be greater than 50 μm. It should be noted that the present invention does not impose any limitation on the thickness of the second photoresist wet film 40 and can be adjusted as needed.

[0112] In one embodiment, the photoresist may be a positive photoresist. Specifically, the photoresist may be a phenolic resin-photosensitizer PAC system photoresist. Because the photoresist subsequently needs to be exposed to developer and plating solutions, a positive photoresist is required as a barrier. For example, the positive photoresist may be KX150, a positive photoresist produced by Shanghai Feikai Materials Technology Co., Ltd.

[0113] In one embodiment, the photoresist comprises the following components, by weight: 70% to 80% of a solvent, 15% to 25% of a phenolic resin, 3% to 6% of a photosensitizer, and 0.1% to 2% of an additive.

[0114] It is understandable that Figure 7 As shown, after obtaining the second photoresist wet film 40 , the first printing screen 31 needs to be removed.

[0115] Step S15, please refer to Figure 8 , heating the second photoresist wet film 40 to obtain a second photoresist layer 41.

[0116] Specifically, the second photoresist wet film 40 is baked on the back side of the substrate 10 using a hot plate to obtain the second photoresist layer 41. In another embodiment, the substrate 10, the first photoresist layer 21, and the second photoresist wet film 40 can also be placed in an oven to bake the second photoresist wet film 40 to obtain the second photoresist layer 41.

[0117] In one embodiment, the baking temperature is 90° C. to 110° C. In one embodiment, the baking time is 180 seconds to 240 seconds.

[0118] The second photoresist layer 41 has an opening 411 , and a portion of the first photoresist layer 21 is exposed in the opening 411 .

[0119] Step S16, please refer to Figure 9 and Figure 10 , the overlapping area of the second photoresist layer 41 and the first photoresist layer 21 is aligned and exposed, and then developed to obtain a patterned photoresist layer 50.

[0120] Specifically, a photomask 60 is placed above the second photoresist layer 41 , wherein 8 to 12 alignment marking points may be set between the photomask 60 and the substrate 10 to prevent misalignment between the photomask 60 and the substrate 10 .

[0121] The light emitted by the exposure machine is irradiated onto the overlapping area of the second photoresist layer 41 and the first photoresist layer 21 through the through hole 601 of the photomask 60 to align and expose the second photoresist layer 41 and the first photoresist layer 21. Then, the photomask 60 is removed, and the exposed second photoresist layer 41 and the exposed first photoresist layer 21 are developed with a developer to obtain the patterned photoresist layer 50.

[0122] It can be understood that the developed second photoresist layer 41 and the developed first photoresist layer 21 together constitute the patterned photoresist layer 50 .

[0123] The patterned photoresist layer 50 has pores 501, and a portion of the substrate 10 is exposed in the pores 501. Figure 10 As shown, the pore 501 sequentially penetrates the developed second photoresist layer 41 and the developed first photoresist layer 21 , and the bottom surface of the pore 501 is the front surface of the substrate 10 .

[0124] It is understandable that after obtaining the patterned photoresist layer 50 , operations such as electroplating and removal of the patterned photoresist 50 are required to prepare a redistribution layer to obtain the final product.

[0125] The present invention defines the method of reducing the amount of photoresist used described above as a first method of reducing the amount of photoresist used, and defines the method of reducing the amount of photoresist used described below as a second method of reducing the amount of photoresist used.

[0126] At least one embodiment of the present invention provides a method for reducing photoresist usage, comprising the following steps:

[0127] Step S21, please refer to Figure 11 , providing a substrate 11.

[0128] In one embodiment, the substrate 11 may be a wafer substrate. In another embodiment, the substrate 11 may also be any substrate that needs to be provided with metal structure lines (such as copper lines).

[0129] Step S22, refer to Figure 12 and Figure 13 , a photoresist wet film 22 is formed on the substrate 11 through a first printing screen 32 .

[0130] Among them, such as Figure 14 As shown, the first printing screen 32 is a partially perforated printing screen with a pattern. Specifically, the first printing screen 32 includes a first masking area 321 and a first mesh area 322. Specifically, the first printing screen 32, which has the same shape and size as the substrate 11, is tightly attached to the substrate 11 and strictly aligned with the substrate 11 using alignment marks. A certain amount of photoresist is then applied to the first printing screen 32. A squeegee is pulled across the first printing screen 32 to squeeze the photoresist through the first mesh area 322 and onto the substrate 11 below the first printing screen 32, thereby forming the photoresist wet film 22.

[0131] In order to prevent misalignment between the first printing screen 32 and the substrate 11 , 8 to 12 alignment marking points may be provided between the first printing screen 32 and the substrate 11 .

[0132] In one embodiment, the mesh number of the first printing screen 32 may be about 100 meshes.

[0133] The thickness of the photoresist wet film 22 can be controlled by controlling the number and aperture of the screen mesh in the first mesh area 322. It will be appreciated that the fewer the number of screen mesh holes and the larger the aperture in the first mesh area 322, the greater the amount of photoresist that flows onto the substrate 11 in the same amount of time, and the thicker the resulting photoresist wet film 22. This approach allows the preparation of photoresist wet films 22 of varying thicknesses.

[0134] In one embodiment, the thickness of the photoresist wet film 22 is 40 μm to 50 μm. In another embodiment, the thickness of the photoresist wet film 22 may be greater than 50 μm. It should be noted that the present invention does not limit the thickness of the photoresist wet film 22 and can be adjusted as needed.

[0135] In one embodiment, the photoresist may be a positive photoresist. Specifically, the photoresist may be a phenolic resin-photosensitizer PAC system photoresist. Because the photoresist subsequently needs to be exposed to developer and plating solutions, a positive photoresist is required as a barrier. For example, the positive photoresist may be KX150, a positive photoresist produced by Shanghai Feikai Materials Technology Co., Ltd.

[0136] In one embodiment, the photoresist comprises the following components, by weight: 70% to 80% of a solvent, 15% to 25% of a phenolic resin, 3% to 6% of a photosensitizer, and 0.1% to 2% of an additive.

[0137] It is understandable that after obtaining the photoresist wet film 22 , the first printing screen 32 needs to be removed.

[0138] Step S23, refer to Figure 15 , heating the photoresist wet film 22 to obtain a photoresist layer 23.

[0139] Specifically, the photoresist wet film 22 is baked on the back side of the substrate 11 by a hot plate to obtain the photoresist layer 23. In another embodiment, the substrate 11 and the photoresist wet film 22 can also be placed in an oven to bake the photoresist wet film 22 to obtain the photoresist layer 23.

[0140] In one embodiment, the baking temperature is 80° C. to 90° C. In one embodiment, the baking time is 180 s to 240 s.

[0141] The photoresist layer 23 has an opening 231 , and a portion of the substrate 11 is exposed in the opening 231 .

[0142] Step S24, please refer to Figure 16 and Figure 17 , a resin wet film 42 is formed in the opening 231 through the second printing screen 33 .

[0143] Among them, such as Figure 18 As shown, the second printing screen 33 is a partially perforated printing screen with a pattern. That is, the second printing screen 33 includes a second masking area 331 and a second mesh area 332, wherein the second masking area 331 corresponds to the position of the first mesh area 322, and the second mesh area 332 corresponds to the position of the first masking area 321.

[0144] Specifically, the second printing screen 33 having the same shape and size as the substrate 11 is tightly attached to the substrate 11, and the second printing screen 33 is strictly aligned with the substrate 11 through alignment marks; then a certain amount of resin solution is coated on the second printing screen 33, and a scraper is pulled on the second printing screen 33 to squeeze the resin solution through the second mesh area 332 to reach the opening 231 below the second printing screen 33, thereby obtaining the resin wet film 42.

[0145] The area of the second masking area 331 is larger than the area of the first mesh area 322. Specifically, when the first printing screen 32 and the second printing screen 33 are aligned with the substrate 11, the distance between the projection of the edge of the second masking area 331 on the substrate 11 and the projection of the corresponding edge of the first mesh area 322 on the substrate 11 is 2μm to 3μm. This ensures that the resin solution that has just been squeezed into the opening 231 will not come into contact with the photoresist layer 23, but because the resin solution has a certain fluidity, it can subsequently come into contact with the photoresist layer 23. That is, the resin solution will eventually completely cover the substrate 11 that is not covered by the photoresist layer 23.

[0146] In order to prevent misalignment between the second printing screen 33 and the substrate 11 , 8 to 12 alignment marking points may be provided between the second printing screen 33 and the substrate 11 .

[0147] In one embodiment, the mesh size of the second printing screen 33 can be selected as needed.

[0148] The thickness of the wet resin film 42 can be controlled by controlling the number and pore size of the mesh in the second mesh area 332. It will be appreciated that the fewer the mesh holes and the larger the pore size in the second mesh area 332, the greater the amount of resin solution that flows into the openings 231 in the same amount of time, and the thicker the resulting wet resin film 42. This approach allows the production of wet resin films 42 of varying thicknesses.

[0149] In one embodiment, the thickness of the resin wet film 22 is 8 μm to 10 μm. It should be noted that the present invention does not limit the thickness of the resin wet film 42 and can be adjusted as needed.

[0150] In one embodiment, the resin solution may be formed by mixing a positive photoresist main resin with a solvent. Specifically, the resin solution may be a phenolic resin solution.

[0151] Step S25, please refer to Figure 19 , heating the resin wet film 42 to obtain a resin layer 43.

[0152] Specifically, the resin wet film 42 is baked on the back side of the substrate 11 by a hot plate to obtain the resin layer 43. In another embodiment, the substrate 11 and the resin wet film 42 can also be placed in an oven to bake the resin wet film 42 to obtain the resin layer 43.

[0153] In one embodiment, the baking temperature is 90° C. to 110° C. In one embodiment, the baking time is 180 seconds to 240 seconds.

[0154] Step S26, please refer to Figure 20 and Figure 21 , the area where the photoresist layer 23 is located is aligned and exposed, and then developed to obtain a patterned photoresist layer 51.

[0155] In order to prevent misalignment between the photomask 61 and the substrate 11 , 8 to 12 alignment marking points may be provided between the photomask 61 and the substrate 11 .

[0156] Specifically, a photomask 61 is placed above the photoresist layer 23, and the light emitted by the exposure machine is irradiated onto the area where the photoresist layer 23 is located through the through hole 611 of the photomask 61 to perform alignment exposure on the area where the photoresist layer 23 is located. Thereafter, the photomask 61 is removed, and the exposed photoresist layer 23 is developed with a developer to obtain the patterned photoresist layer 51.

[0157] like Figure 21As shown, the patterned photoresist layer 51 has a pore 511, and a portion of the substrate 10 is exposed in the pore 511. The pore 511 penetrates the patterned photoresist layer 51, and the bottom surface of the pore 511 is the front surface of the substrate 10.

[0158] It is understandable that after obtaining the patterned photoresist layer 51 , electroplating and removal of the patterned photoresist 51 and the resin layer 43 are required to prepare a redistribution layer to obtain the final product.

[0159] At least one embodiment of the present invention provides an application of the method for reducing photoresist usage in a semiconductor advanced packaging process, and in particular, an application of the method for reducing photoresist usage in an RDL redistribution layer.

[0160] The present invention provides two methods for reducing the amount of photoresist used. By preparing multiple layers of colloids with different thicknesses, a lower-thickness photoresist layer or a lower-cost resin layer is used in non-exposed areas that do not require photosensitivity. While ensuring that the resolution of the photoresist is not affected, the amount of photoresist used is greatly reduced, thereby reducing production costs.

[0161] The present invention is described in detail below through examples and comparative examples.

[0162] Example 1:

[0163] For an 8-inch copper sheet (20.3 cm in diameter), assuming the required photoresist dry film thickness is 20 μm and the colloidal solid content is 40%, the required wet film thickness is about 50 μm. The copper sheet area is 10.152*π=323.65 cm 2 , then the amount of photoresist used to coat the entire copper sheet is 323.65*50 / 1000=16.18cm 3 =16.18ml.

[0164] If method 1 of reducing the amount of photoresist used is adopted, assuming that the area where the photoresist patterning capability needs to be exerted accounts for 50% of the copper sheet, then the photoresist wet film thickness of the other 50% only needs to be 10μm. Then the amount of photoresist used in the area that exerts the photoresist effect is 16.18 / 2=8.09ml, and the amount used in the area that only plays a protective role is 8.09 / 50*10=1.62ml. The sum of the two is 8.09+1.62=9.71ml. Due to the use of screen printing, some of the residual photoresist on the screen can be used for the next copper sheet, so the loss is small and can be ignored.

[0165] Example 2:

[0166] For an 8-inch copper sheet (20.3 cm in diameter), assuming the required photoresist dry film thickness is 20 μm and the colloidal solid content is 40%, the required wet film thickness is about 50 μm. The copper sheet area is 10.152*π=323.65 cm 2 , then the amount of photoresist used to coat the entire copper sheet is 323.65*50 / 1000=16.18cm 3 =16.18ml.

[0167] If the second method of reducing the amount of photoresist used is adopted, assuming that the area where the photoresist patterning capability needs to be exerted accounts for 50% of the copper sheet, then the wet film thickness of the other 50% of the photoresist only needs to be 10μm. Then the amount of photoresist used in the area that exerts the photoresist effect is 16.18 / 2=8.09ml, and the amount of resin solution that only plays a protective role is 1.61ml. Therefore, the actual amount of photoresist used is 8.09ml. Due to the use of screen printing, some of the residual photoresist on the screen can be used for the next copper sheet, so the loss is small and can be ignored.

[0168] Comparative Example 1:

[0169] For an 8-inch copper sheet (20.3 cm in diameter), assuming the required photoresist dry film thickness is 20 μm and the colloidal solid content is 40%, the required wet film thickness is about 50 μm. The copper sheet area is 10.152*π=323.65 cm 2 , then the amount of photoresist used to coat the entire copper sheet is 323.65*50 / 1000=16.18cm 3 =16.18ml.

[0170] In the standard semiconductor manufacturing process, in the process of coating-baking-exposure-development-electroplating, spin coating is used to cover an entire surface of the copper sheet. Considering that the spin-coated colloid will have a throw-out loss of at least 1 / 5, the amount of photoresist used in this method is 20.23 ml.

[0171] Therefore, the method for reducing the amount of photoresist of the present invention can reduce the amount of photoresist by more than 50%, that is, can reduce it by about 60%.

[0172] The two methods for reducing photoresist usage provided by the present invention are applied to semiconductor manufacturing processes. Compared with the conventional standard semiconductor process of spin coating, baking, exposure, development, and electroplating, the resulting photoresists maintain the same resolution. For example, the positive photoresist KX150 produced by Shanghai Feikai Materials Technology Co., Ltd. achieves a resolution of 10-15 μm using the former method, while the latter achieves a resolution of 10-12 μm using the standard semiconductor process, given a dry film thickness of 20 μm.

[0173] In addition, compared with the direct printing method, which is limited in resolution by the aperture size of the printing screen and has a resolution of more than 30 μm (referring to directly using conductive ink or paste to print conductive circuits on an insulating substrate to form the required circuits), the present invention uses photoresist to prepare conductive circuits with higher resolution.

[0174] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0175] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for reducing the amount of photoresist used, characterized in that: The following steps are involved: providing a substrate, and forming a first photoresist wet film on the substrate; heating the first photoresist wet film to obtain a first photoresist layer; Printing on the first photoresist layer through a first printing screen to obtain a second photoresist wet film; heating the second photoresist wet film to obtain a second photoresist layer, wherein the second photoresist layer has an opening, and a portion of the first photoresist layer is exposed in the opening; and The overlapping area of the second photoresist layer and the first photoresist layer is aligned and exposed through a photomask, and then developed, so that the developed second photoresist layer and the developed first photoresist layer together form a patterned photoresist layer, wherein the patterned photoresist layer has pores, and part of the substrate is exposed to the pores.

2. The method for reducing the amount of photoresist used according to claim 1, wherein: The method comprises at least one of the following (1) to (2): (1) The thickness of the first photoresist wet film is 8 μm to 10 μm; (2) The thickness of the second photoresist wet film is 30 μm to 50 μm.

3. The method for reducing the amount of photoresist used according to claim 1, wherein: The method comprises at least one of the following (1) to (2): (1) Heating the first photoresist wet film specifically includes the following steps: baking the first photoresist wet film on a side of the substrate away from the first photoresist wet film; The baking temperature is 80°C to 90°C, and the baking time is 60s to 120s. (2) heating the second photoresist wet film specifically comprises the following steps: baking the second photoresist wet film on a side of the substrate away from the second photoresist wet film; The baking temperature is 90° C. to 110° C., and the baking time is 180s to 240s.

4. The method for reducing the amount of photoresist used according to any one of claims 1 to 3, wherein: Forming a first photoresist wet film on the substrate specifically includes the following steps: The first photoresist wet film is obtained by printing on one entire surface of the substrate using a full-hole printing screen.

5. The method for reducing the amount of photoresist used according to claim 4, wherein: Printing on one entire surface of the substrate by using a full-hole printing screen specifically comprises the following steps: Laminating the full-through-hole printing screen having the same shape and size as the substrate to one surface of the substrate, and aligning the full-through-hole printing screen with the substrate through alignment marks; and The photoresist is coated on the full-hole printing screen, and a scraper is pulled on the full-hole printing screen to squeeze the photoresist so that the photoresist passes through the mesh of the full-hole printing screen and reaches the substrate.

6. The method for reducing the amount of photoresist used according to any one of claims 1 to 3, wherein: Printing on the first photoresist layer through a first printing screen specifically includes the following steps: Laminating the first printing screen having the same shape and size as the substrate on the surface of the first photoresist layer, and aligning the first printing screen with the first photoresist layer through alignment marks; and A photoresist is coated on the first printing screen, and a scraper is pulled on the first printing screen to squeeze the photoresist so that the photoresist passes through the mesh of the first printing screen and reaches the first photoresist layer.

7. A method for reducing the amount of photoresist used, characterized in that: The following steps are involved: Providing a substrate, and forming a photoresist wet film on the substrate using a first printing screen; heating the photoresist wet film to obtain a photoresist layer, wherein the photoresist layer has openings, and a portion of the substrate is exposed to the openings; forming a resin wet film in the openings by a second printing screen; heating the resin wet film to obtain a resin layer; and The area where the photoresist layer is located is subjected to alignment exposure and then developed to obtain a patterned photoresist layer, wherein the patterned photoresist layer has pores, and a portion of the substrate is exposed in the pores.

8. The method for reducing the amount of photoresist used according to claim 7, wherein: The method comprises at least one of the following (1) to (2): (1) The thickness of the photoresist wet film is 40 μm to 50 μm; (2) The thickness of the resin wet film is 8 μm to 10 μm.

9. The method for reducing the amount of photoresist used according to claim 7, wherein: The method comprises at least one of the following (1) to (2): (1) Heating the photoresist wet film specifically comprises the following steps: baking the photoresist wet film on a side of the substrate away from the photoresist wet film; The baking temperature is 80°C to 90°C, and the baking time is 180s to 240s. (2) Heating the resin wet film specifically comprises the following steps: baking the resin wet film on a side of the substrate away from the resin wet film; The baking temperature is 90° C. to 110° C., and the baking time is 180s to 240s.

10. The method for reducing the amount of photoresist used according to any one of claims 7 to 9, characterized in that: The first printing screen includes a first covering area and a first mesh area, and the second printing screen includes a second covering area and a second mesh area, and the second covering area corresponds to the position of the first mesh area, and the second mesh area corresponds to the position of the first covering area.

11. The method for reducing the amount of photoresist used according to claim 10, wherein: The area of the second covering area is larger than that of the first mesh area.

12. The method for reducing the amount of photoresist used according to any one of claims 7 to 9, wherein: The method comprises at least one of the following (1) to (2): (1) forming a photoresist wet film on the substrate by a first printing screen specifically comprises the following steps: Laminating the first printing screen having the same shape and size as the substrate to one surface of the substrate, and aligning the first printing screen with the substrate through alignment marks; and Applying photoresist on the first printing screen, and squeezing the photoresist by pulling a scraper on the first printing screen so that the photoresist passes through the mesh of the first printing screen and reaches the substrate; (2) forming a resin wet film in the opening by a second printing screen specifically comprises the following steps: Laminating a second printing screen having the same shape and size as the substrate to one surface of the substrate, and aligning the second printing screen with the substrate through alignment marks; and A photoresist is coated on the second printing screen, and a scraper is pulled on the second printing screen to squeeze the photoresist so that the photoresist passes through the mesh of the second printing screen and reaches the opening.

13. Use of the method for reducing photoresist usage according to any one of claims 1 to 12 in a semiconductor advanced packaging process.

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