TMBS photolithography process can prevent the photoresist on the silver film surface from peeling off during development.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-15
- Publication Date
- 2026-03-10
AI Technical Summary
In the silver film layer photolithography process of TMBS semiconductor devices, the photoresist is prone to peeling off during the development process, resulting in pattern defects and subsequent process failures, which is difficult to solve effectively with existing technologies.
By adjusting the photoresist wash width and depositing an intermetallic adhesion layer, the adhesion between the silver and aluminum film layers is improved. A titanium film layer is then applied to the edge of the silver film layer to increase the adhesion of the photoresist and prevent galvanic cell reactions. EBR and WEE processes are used to control the photoresist edge, and a stable electrode structure is formed by combining dry or wet etching techniques.
It effectively prevents photoresist from falling off during the development process, ensuring smooth operation of subsequent processes, reducing rework, improving product yield, and saving manpower and resources.
Smart Images
Figure CN119846904B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor device manufacturing technology. Background Technology
[0002] In the electrode fabrication process of TMBS (Trench MOS Barrier Schottky) semiconductor devices, a process structure of depositing a silver film layer on an aluminum film layer is often used. Silver has excellent conductivity and is a commonly used welding material in semiconductor packaging. Using silver as an electrode can ensure extremely low resistance and good welding strength during packaging, greatly improving device performance.
[0003] However, in the silver film lithography process, due to the large size of the aluminum grains, the silver film has a poor surface roughness, which affects the adhesion between the photoresist and the silver film surface. This makes the photoresist prone to detachment during subsequent development. Furthermore, during development, the silver on the surface of the silver film in the developing solution and the aluminum at the edge of the wafer substrate that is not completely covered by the silver film can easily form a galvanic cell pattern. That is, when both are immersed in the developing solution, aluminum, being more reactive than silver, easily loses electrons and is oxidized to trivalent aluminum, which enters the developing solution. Electrons flow to the silver, and hydrogen ions in the developing solution gain electrons from the silver, are reduced to hydrogen atoms, and hydrogen gas is released. This results in the photoresist detaching from the silver film surface.
[0004] Therefore, a large number of wafer substrates experience photoresist detachment during development, resulting in pattern defects that prevent subsequent wet etching processes and necessitate rework. To prevent defective products from being shipped out, all wafer substrates must be inspected, consuming significant manpower and time. Even if the photoresist on the wafer substrate does not detach during development, there is still a risk of photoresist detachment during subsequent wet etching. Summary of the Invention
[0005] In order to prevent the photoresist on the surface of the silver film layer from peeling off during development in the TMBS lithography process, this invention provides a technical solution entitled "TMBS lithography process capable of preventing the photoresist on the surface of the silver film layer from peeling off during development".
[0006] This invention includes the following steps:
[0007] S1: As Figure 1 As shown, an aluminum film layer 2 is deposited on a wafer substrate 1. The thickness of the aluminum film layer 2 is 3μm to 5μm, and the distance between the aluminum film layer 2 and the boundary of the wafer substrate 1 at the edge of the wafer substrate 1 is i = 1.2mm to 1.4mm.
[0008] S2: As Figure 2As shown, a first layer of photoresist 3 is coated on the surface of the aluminum film layer 2. The trimming width j of the first layer of photoresist 3 is 2.5 mm to 3 mm, and the error of the trimming width j is within the range of ±0.1 mm. The first layer of photoresist 3 is exposed and developed to form an electrode pattern.
[0009] S3: As Figure 3 shown, under the masking of the first layer of photoresist 3, the aluminum film layer 2 is etched to form the electrode pattern. The edge of the aluminum film layer 2 is etched synchronously. The distance i is equal to the distance j. After that, the first layer of photoresist 3 is removed, as Figure 4 shown;
[0010] S4: As Figure 5 shown, a titanium layer with a thickness of and a nickel layer with a thickness of are sequentially deposited on the aluminum film layer 2. The titanium layer and the nickel layer form an intermetallic bonding layer 4. Then, a silver film layer 5 is deposited. The silver film layer 5 covers the surface of the intermetallic bonding layer 4 and the side circumferential surfaces of the intermetallic bonding layer 4 and the aluminum film layer 2. The thickness of the silver film layer 5 is The distance k between the part of the silver film layer 5 covering the side circumferential surface and the boundary of the wafer substrate 1 is < j, and k = 0 mm to 2 mm;
[0011] S5: As Figure 6 shown, a titanium film layer 6 with a thickness of is continuously deposited on the surface of the silver film layer 5;
[0012] S6: As Figure 7 shown, a second layer of photoresist 7 is coated on the surface of the titanium film layer 6. The trimming width of the second layer of photoresist 7 is equal to the distance k. The second layer of photoresist 7 is exposed and developed to form an electrode pattern;
[0013] S7: Under the masking of the second layer of photoresist 7, the titanium film layer 6, the silver film layer 5, and the intermetallic bonding layer 4 are sequentially etched to form the electrode pattern;
[0014] S8: As Figure 8 shown, the second layer of photoresist 7 is removed, and then the titanium film layer 6 is etched away.
[0015] This invention adjusts the edge width of the first photoresist layer 3 to j to ensure that the edge of the aluminum film layer 2 is etched away in the subsequent etching process. The intermetallic adhesive layer 4 serves as an intermediate transition layer between the aluminum film layer 2 and the silver film layer 5, improving their adhesion. The deposited silver film layer 5 is located at a distance k from the edge of the wafer substrate 1, completely covering the aluminum film layer 2 and forming a cover for the silver-aluminum metal electrode structure. No aluminum is exposed at the edge of the wafer substrate 1, thus preventing the formation of a galvanic cell reaction between silver and aluminum in the developing solution. After the silver film layer 5 is deposited, a titanium film layer 6 is deposited. Since titanium easily forms natural oxides in air at room temperature, it readily undergoes a displacement reaction with HMDS during the photolithography hydrophobic treatment process to form hydrophobic groups, increasing the adhesion between the silver film layer 5 and the photoresist 7. Furthermore, because the deposited titanium film layer 6 is very thin, it is easily etched away without affecting the conductivity of the silver film layer 5. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of S1 of the present invention.
[0017] Figure 2 This is a schematic diagram of S2 of the present invention.
[0018] Figure 3 This is a schematic diagram showing the synchronous corrosion of the edge of the aluminum film layer 2 in S3 of the present invention.
[0019] Figure 4 This is a schematic diagram of removing the first layer of photoresist 3 in step S3 of the present invention.
[0020] Figure 5 This is a schematic diagram of S4 of the present invention.
[0021] Figure 6 This is a schematic diagram of S5 of the present invention.
[0022] Figure 7 This is a schematic diagram of S6 of the present invention, which also serves as an abstract drawing.
[0023] Figure 8 This is a schematic diagram of S8 of the present invention. Detailed Implementation
[0024] The first layer of photoresist 3 and the second layer of photoresist 7 are washed in the same way, using EBR (Edge Bead Removal) or WEE (Wafer Edge Exposure) process methods.
[0025] The aluminum film layer 2 and the silver film layer 5 are deposited in the same way, using sputtering or evaporation processes.
[0026] The corrosion and development of the aluminum film layer 2 and the silver film layer 5 are carried out in the same way, using dry etching or wet etching methods.
[0027] A specific example of the TMBS lithography process of the present invention that can prevent the photoresist on the surface of the silver film layer from falling off during development is described as follows.
[0028] As Figure 1 shown, an aluminum film layer 2 is deposited on the wafer substrate 1. The thickness of the aluminum film layer 2 is 3 μm, and the distance from the edge of the aluminum film layer 2 to the boundary of the wafer substrate 1 at the edge of the wafer substrate 1 is i = 1.2 mm; as Figure 2 shown, a first layer of photoresist 3 is coated on the surface of the aluminum film layer 2, and the trimming width of the photoresist 3 is adjusted to j = 2.5 mm, and the error of the trimming width j is within the range of ±0.1 mm, and the electrode pattern is exposed and developed; as Figure 3 shown, under the masking of the first layer of photoresist 3, the aluminum film layer 2 is etched, and the edge of the aluminum film layer 2 is also etched to a position where the distance from the boundary of the wafer substrate 1 is j = 2.5 mm, and then the first layer of photoresist 3 is removed, as Figure 4 shown; as Figure 5 shown, a titanium layer with a thickness of and a nickel layer with a thickness of are sequentially deposited on the aluminum film layer 2 to form an intermetallic adhesion layer 4, and then a silver film layer 5 is deposited. The silver film layer 5 covers the surface of the intermetallic adhesion layer 4 and the side circumferential surfaces of the intermetallic adhesion layer 4 and the aluminum film layer 2. The thickness of the silver film layer 5 is The distance from the edge position of the silver film layer 5 to the boundary of the wafer substrate 1 at the edge of the wafer substrate 1 is k < j, and k = 1 mm; as Figure 6 shown, a titanium film layer 6 with a thickness of is continuously deposited on the silver film layer 5; as Figure 7 shown, a second layer of photoresist 7 is coated on the surface of the titanium film layer 6. The trimming width of the second layer of photoresist 7 is k = 1 mm, and the electrode pattern is exposed and developed; under the masking of the second layer of photoresist 7, the titanium film layer 6, the silver film layer 5, and the adhesion layer 4 are sequentially etched to form the electrode pattern; as Figure 8 shown, the second layer of photoresist 7 is removed and the surface titanium film layer 6 is etched off.
Claims
1. A TMBS photolithography process capable of preventing the silver film layer from peeling off during the development of the photoresist on the surface, characterized in that, The method comprises the following steps: S1: depositing an aluminum film layer (2) on a wafer substrate (1), the thickness of the aluminum film layer (2) being 3-5 μm, and the distance between the aluminum film layer (2) and the edge of the wafer substrate (1) being i=1.2-1.4 mm; S2: coating a first layer of photoresist (3) on the surface of the aluminum film layer (2), the edge width of the first layer of photoresist (3) being j=2.5-3 mm, and the error of the edge width being within ±0.1 mm, and exposing and developing the first layer of photoresist (3) to form an electrode pattern; S3: etching the aluminum film layer (2) to form the electrode pattern under the mask of the first layer of photoresist (3), the edge of the aluminum film layer (2) being etched synchronously, the distance i being equal to the distance j, and then removing the first layer of photoresist (3); S4: depositing successively on the aluminum film layer (2) a thick titanium layer, a thick nickel layer, forming an intermetallic adhesion layer (4) with the titanium layer and the nickel layer, and then depositing a silver film layer (5) covering the surface of the intermetallic adhesion layer (4) and the side circumferential surface of the intermetallic adhesion layer (4) and the aluminum film layer (2), the thickness of the silver film layer (5) being the distance k of the part of the silver film layer (5) covering the side circumferential surface from the boundary of the wafer substrate (1) being k = 0 mm to 2 mm; S5: continue deposition on the surface of the silver film layer (5) a titanium film layer (6) having a thickness of S6: coating a second layer of photoresist (7) on the surface of the titanium film layer (6), the edge width of the second layer of photoresist (7) being equal to the distance k, and exposing and developing the second layer of photoresist (7) to form an electrode pattern; S7: etching the titanium film layer (6), the silver film layer (5) and the intermetallic adhesion layer (4) to form the electrode pattern under the mask of the second layer of photoresist (7); S8: removing the second layer of photoresist (7), and then etching the titanium film layer (6).
2. The TMBS photolithography process capable of preventing the silver film layer surface from peeling off during the development of the photoresist according to claim 1, characterized in that, The edge width of the first layer of photoresist (3) and the second layer of photoresist (7) is the same, and EBR or WEE process is used.
3. The TMBS photolithography process capable of preventing the silver film layer surface from peeling off during the development of the photoresist according to claim 1, characterized in that, The deposition of the aluminum film layer (2) and the silver film layer (5) is the same, and sputtering or evaporation process is used.
4. The TMBS photolithography process capable of preventing the silver film layer surface from peeling off during the development of the photoresist according to claim 1, characterized in that, The etching and developing of the aluminum film layer (2) and the silver film layer (5) is the same, and dry etching or wet etching is used.
Citation Information
Patent Citations
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