Silicon wafer crystal orientation confirmation method for contact type photoetching machine
By fabricating a silicon oxide protective layer and a photoresist intermediate on a silicon wafer, forming crystal orientation positioning holes on the silicon wafer using a positioning mask and photolithography, and forming octagonal grooves through wet etching, the problem of insufficient V-groove precision and crystal orientation alignment in the prior art is solved, and high-precision V-groove processing is achieved.
Patent Information
- Application Number
- CN202511066070.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-31
- Publication Date
- 2025-10-31
AI Technical Summary
In the existing technology, the accuracy of V-grooves produced by mechanical cutting cannot meet the high-precision requirements below ±0.5um, and the alignment accuracy error of the existing silicon wafer crystal orientation confirmation method is relatively large, which cannot meet the requirements of high-precision V-groove etching.
The silicon wafer crystal orientation confirmation method using a contact lithography machine involves fabricating a silicon oxide protective layer and a photoresist intermediate on the silicon wafer, creating crystal orientation positioning holes using a positioning mask and photolithography, and determining the crystal orientation by forming an octagonal groove through wet etching. The position of the V-groove mask is then adjusted to achieve high-precision crystal orientation alignment.
The machining accuracy of the V-groove has been improved, ensuring that the V-groove is etched along a specific crystal orientation, thus achieving higher crystal orientation alignment and V-groove quality.
Smart Images
Figure CN120878619A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor processing and manufacturing, and in particular to a method for confirming the crystal orientation of silicon wafers using a contact lithography machine. Background Technology
[0002] In the optical communication industry, fiber optic arrays primarily rely on precisely etched V-grooves for positioning. Current V-grooves are mainly one-dimensional, and the mainstream V-grooves on the market are produced through mechanical cutting. However, the precision of mechanically cut V-grooves is above ±1µm, which cannot meet the precision requirements below ±0.5µm. Due to the high precision and miniaturization characteristics of semiconductor processing technology, the fabrication of V-grooves on silicon wafers using semiconductor processing technology is gradually gaining popularity.
[0003] V-grooves on silicon wafers are formed using wet etching, and the quality of the wet-etched V-grooves is highly dependent on the crystal orientation of the silicon wafer. Therefore, in the production of V-grooves using semiconductor processes, confirming the crystal orientation of the silicon wafer becomes a crucial step in V-groove manufacturing.
[0004] However, in the silicon wafer processing method using semiconductor technology, the main method for confirming the silicon wafer crystal orientation is to use the wafer positioning edge as a reference to distinguish the three crystal planes 100, 110 and 111. However, since the wafer positioning edge is obtained by mechanical cutting and polishing, the alignment accuracy error with the crystal orientation is relatively large, which cannot meet the high alignment accuracy requirements of V-groove etching. Therefore, a new method is needed to confirm the crystal orientation in order to achieve higher precision crystal orientation alignment. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method for confirming the crystal orientation of silicon wafers for contact lithography machines that can achieve high-precision crystal orientation alignment, in light of the current state of the prior art.
[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a method for confirming the crystal orientation of silicon wafers for contact lithography machines, characterized by comprising the following steps:
[0007] Step 1: Select a silicon wafer with 100 crystal orientation, produce a silicon oxide protective layer on the silicon wafer, and then spin-coat photoresist on the silicon oxide protective layer to obtain the first intermediate;
[0008] Step 2: Place the pre-designed positioning mask with crystal orientation positioning holes directly above the photoresist of the obtained first intermediate, and then expose and develop the photoresist sequentially, so that the crystal orientation positioning holes of the positioning mask are transferred to the photoresist of the silicon wafer, thereby obtaining the second intermediate;
[0009] Step 3: Etch the second intermediate to transfer the crystal orientation positioning holes on the photoresist to the silicon oxide protective layer, thus obtaining the third intermediate;
[0010] Step 4: Remove the photoresist from the surface of the third intermediate, and then immerse the third intermediate after photoresist removal in a KOH solution for etching to obtain the fourth intermediate; wherein, an octagonal groove that can display the crystal orientation of the silicon wafer is formed on the fourth intermediate and on the silicon wafer at the corresponding crystal orientation positioning hole; in the octagonal groove, the intersection line between each groove sidewall and the groove bottomwall is a crystal orientation mark.
[0011] Preferably, in step 1, the silicon wafer is a lightly doped P-type silicon wafer or an N-type silicon wafer.
[0012] Preferably, in step 1, the thickness of the silicon oxide protective layer is 2-3 μm; and the thickness of the photoresist is 1-2 μm.
[0013] Preferably, in step 2, the edge of the silicon wafer is provided with a wafer positioning edge, and the positioning mask is provided with a rectangular hole corresponding to the wafer positioning edge, the rectangular hole having an edge aligned with the wafer positioning edge. By adopting the above-described scheme, the rectangular hole on the mask is aligned with the wafer positioning edge, facilitating positioning between the mask and the silicon wafer, thereby setting the crystal orientation positioning hole at a specific position on the silicon wafer.
[0014] Preferably, in step 2, the mask has two crystal orientation positioning holes; the crystal orientation positioning holes are circular holes. In other embodiments, the crystal orientation positioning holes may also be elliptical holes.
[0015] Preferably, in step 3, the etching process for the second intermediate is BOE wet etching or dielectric etching machine dry etching.
[0016] Preferably, in step 4, the surface of the third intermediate is cleaned with acetone or NMP to remove the photoresist.
[0017] Preferably, in step 2, the edge of the silicon wafer is provided with a wafer positioning edge, and the positioning mask is provided with a rectangular hole corresponding to the wafer positioning edge, the rectangular hole having an edge aligned with the wafer positioning edge. Wet etching is slower from the center of the positioning hole toward the sidewall of the first trench; wet etching is faster from the center of the positioning hole toward the sidewall of the second trench.
[0018] Preferably, the silicon wafer crystal orientation confirmation method for contact lithography machines further includes the following steps after step 4:
[0019] Step 5: Place the pre-designed V-groove mask with V-groove pattern and V-groove mark on the silicon wafer; wherein the length direction of the V-groove on the V-groove mask is parallel or perpendicular to the V-groove mark;
[0020] Step 6: Adjust the V-groove mask so that the V-groove Mark is parallel to at least one of the crystal orientation markings.
[0021] Compared with the prior art, the advantages of the present invention are as follows: before processing V-grooves on the silicon wafer, a smaller area is selected for wet etching, and the octagonal grooves that appear during the wet etching process are used to determine the crystal orientation markings on the silicon wafer; the position of the V-groove mask is adjusted with reference to the crystal orientation markings, and the V-groove is etched along the crystal orientation during the V-groove processing, resulting in higher precision of the processed V-groove. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the structure after a positioning mask is placed on a silicon wafer in an embodiment of the present invention;
[0023] Figure 2 This is a diagram showing the result of KOH etching of the circular crystal orientation positioning hole in an embodiment of the present invention;
[0024] Figure 3 This is a schematic diagram of the structure after placing a V-groove mask on a silicon wafer in an embodiment of the present invention;
[0025] Figure 4 for Figure 3 Enlarged view of point A in the middle. Detailed Implementation
[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0027] like Figures 1-4 The figure shown is a preferred embodiment of the silicon wafer crystal orientation confirmation method for a contact lithography machine according to the present invention. This silicon wafer crystal orientation confirmation method for a contact lithography machine includes the following steps:
[0028] Step 1: Select a silicon wafer 1 with a 100-degree crystal orientation. The edge of the silicon wafer 1 is provided with a wafer positioning edge 11. A silicon oxide protective layer is produced on the silicon wafer 1. Then, photoresist is spin-coated on the silicon oxide protective layer to obtain the first intermediate. The silicon wafer 1 is a low-doped P-type or N-type silicon wafer. The thickness of the silicon oxide protective layer is 2-3 μm. The photoresist is MIR701 photoresist with a thickness of 1-2 μm. In other embodiments, other corrosion-resistant or etching-resistant positive or negative photoresist can be used.
[0029] Step 2: Place the pre-designed positioning mask 2 directly above the photoresist of the first intermediate. The positioning mask 2 has a rectangular hole 21 and two circular crystal orientation positioning holes 22. Align the upper edge of the rectangular hole 21 with the wafer positioning edge 11 on the silicon wafer 1. Figure 1As shown; then the photoresist is exposed and developed sequentially, so that the two crystal orientation positioning holes 22 on the positioning mask 2 are transferred to the photoresist on the silicon wafer 1, thereby obtaining the second intermediate; wherein the diameter of the circular crystal orientation positioning hole 22 is greater than 50um, the two crystal orientation positioning holes 22 are distributed on the left and right sides of the silicon wafer 1, and the center distance between the two crystal orientation positioning holes 22 is greater than 50mm; the length of the rectangular hole 21 is 58mm (corresponding to the 57.5mm wafer positioning edge 11) or 48mm (corresponding to the 48mm wafer positioning edge 11), and the width of the rectangular hole 21 is 20um;
[0030] Step 3: Etch the second intermediate to transfer the crystal orientation positioning hole 22 on the photoresist to the silicon oxide protective layer, thus obtaining the third intermediate; the etching process for the second intermediate is either BOE wet etching or dielectric etching machine dry etching.
[0031] Step 4: Clean the surface of the third intermediate with acetone or NMP to remove the photoresist. Then, immerse the photoresist-free third intermediate in a 10-45% KOH solution for etching at a temperature of 70-80℃ for 15-20 minutes to obtain the fourth intermediate. On the fourth intermediate and on the silicon wafer 1 corresponding to the crystal orientation positioning hole 22, an octagonal groove 3 that reveals the crystal orientation of the silicon wafer 1 is formed through etching in the KOH solution. Figure 2 As shown; in KOH solution of the same concentration, the presence of crystal orientations 100, 110, and 111 results in different corrosion rates for each facet, with V(110) > V(111). The 111 facet gradually becomes a limiting crystal facet during corrosion, its area gradually increases, while the 110 facet's area gradually decreases. Following the above KOH solution corrosion process, after 15-20 minutes, the octagonal groove 3 will have four longer first groove sidewalls 31 and four shorter second groove sidewalls 32, spaced apart. From the center of the crystal orientation positioning hole 22 towards the first groove sidewall 31, the wet etching speed is slow; from The center of the crystal orientation positioning hole 22 faces the second trench sidewall 32. Due to the fast wet etching speed, the distance between the longer first trench sidewall 31 and the center of the crystal orientation positioning hole 22 is smaller than the distance between the shorter second trench sidewall 32 and the center of the crystal orientation positioning hole 22. The intersection line between the longer first trench sidewall 31 and the trench bottom wall 30 is the crystal orientation mark 4. There are 4 crystal orientation marks 4 in total, and the straight lines containing the 4 crystal orientation marks 4 form a square. The intersection line between the shorter second trench sidewall 32 and the trench bottom wall 30 is also the crystal orientation mark 4. In order to make it easier to clearly identify the crystal orientation mark 4, the intersection line between the longer first trench sidewall 31 and the trench bottom wall 30 is usually chosen as the crystal orientation mark 4. Figure 2In the process, the crystal orientation positioning hole 22 is set on the silicon oxide protective layer. Since the silicon oxide protective layer is thin, the octagonal groove 3 etched on the silicon wafer 1 can be clearly seen. The distance between the longer first groove sidewall 31 and the center of the crystal orientation positioning hole 22 is less than the radius of the crystal orientation positioning hole 22, and the distance between the shorter second groove sidewall 32 and the center of the crystal orientation positioning hole 22 is greater than the radius of the crystal orientation positioning hole 22.
[0032] Step 5: As Figure 3 As shown, a pre-designed V-groove mask 5 is placed on a silicon wafer 1. The V-groove mask 5 has a V-groove pattern 51 and V-groove marks 52, with a total of 4 V-groove marks 52 (see Figure 1). Figure 4 The four V-groove Marks 52 are arranged in a straight line that can form a square. The V-groove Marks 52 are set on the periphery of the crystal orientation Mark 4. The length of the V-groove is parallel to at least one V-groove Mark 52. The closest distance between the V-groove Mark 52 and the crystal orientation positioning hole 22 is h, where h ranges from 2 to 10 μm. The length of the V-groove Mark 52 is equal to the diameter of the crystal orientation positioning hole 22. The width of the V-groove Mark 52 is 2 to 30 μm. The line connecting the centers of the upper and lower V-groove Marks 52 and the two V-groove Marks 52 all pass through the center of the crystal orientation positioning hole 22.
[0033] Step 6: Adjust the V-groove mask 5 so that each V-groove Mark 52 is parallel to at least one crystal orientation mark 4. When the V-groove Mark 52 is parallel to the crystal orientation mark 4, the V-groove can be etched along a specific direction of the crystal orientation, so that the etching speed is the same in the width direction of the V-groove, resulting in higher precision and better quality V-groove.
[0034] Compared with the prior art, the advantages of the present invention are as follows: before processing the V-groove on the silicon wafer 1, a smaller area is selected for wet etching, and the octagonal groove 3 that appears during the wet etching process is used to determine the crystal orientation markings 4 on the silicon wafer 1; with reference to the crystal orientation markings 4, the position of the V-groove mask 5 is adjusted, and the V-groove is etched along a specific crystal orientation during the V-groove processing, so that the V-groove processed has higher precision.
Claims
1. A method for confirming the crystal orientation of silicon wafers in a contact lithography machine, characterized in that, Includes the following steps: Step 1: Select a silicon wafer (1) with 100 crystal orientation, produce a silicon oxide protective layer on the silicon wafer (1), and then spin-coat photoresist on the silicon oxide protective layer to obtain the first intermediate; Step 2: Place the pre-designed positioning mask (2) with crystal orientation positioning holes (22) directly above the photoresist of the obtained first intermediate, and then expose and develop the photoresist in sequence so that the crystal orientation positioning holes (22) of the positioning mask (2) are transferred to the photoresist of the silicon wafer (1) to obtain the second intermediate; Step 3: Etch the second intermediate to transfer the crystal orientation positioning hole (22) on the photoresist to the silicon oxide protective layer, thereby obtaining the third intermediate; Step 4: Remove the photoresist from the surface of the third intermediate, and then etch the third intermediate after removing the photoresist into a KOH solution to obtain the fourth intermediate; wherein, an octagonal groove (3) that can display the crystal orientation of the silicon wafer (1) is formed on the fourth intermediate and on the silicon wafer (1) at the corresponding crystal orientation positioning hole (22); in the octagonal groove (3), the intersection line between each groove sidewall and the groove bottom wall (30) is a crystal orientation mark (4).
2. The method for confirming the crystal orientation of silicon wafers for a contact lithography machine according to claim 1, characterized in that: In step 1, the silicon wafer (1) is a lightly doped P-type silicon wafer or an N-type silicon wafer.
3. The method for confirming the crystal orientation of silicon wafers for a contact lithography machine according to claim 1, characterized in that: In step 1, the thickness of the silicon oxide protective layer is 2-3 μm; the thickness of the photoresist is 1-2 μm.
4. The method for confirming the crystal orientation of silicon wafers for a contact lithography machine according to claim 1, characterized in that: In step 2, the edge of the silicon wafer (1) is provided with a wafer positioning edge (11), and the positioning mask (2) is provided with a rectangular hole (21) corresponding to the wafer positioning edge (11). The rectangular hole (21) has an edge aligned with the wafer positioning edge (11).
5. The method for confirming the crystal orientation of silicon wafers for a contact lithography machine according to claim 4, characterized in that: In step 2, two crystal orientation positioning holes (22) are formed on the positioning mask (2); the crystal orientation positioning holes (22) are circular holes.
6. The method for confirming the crystal orientation of silicon wafers for a contact lithography machine according to claim 1, characterized in that: In step 3, the etching process for the second intermediate is either BOE wet etching or dielectric etching dry etching.
7. The method for confirming the crystal orientation of silicon wafers for a contact lithography machine according to claim 1, characterized in that: In step 4, the surface of the third intermediate is cleaned with acetone or NMP to remove the photoresist.
8. The method for confirming the crystal orientation of silicon wafers for a contact lithography machine according to claim 1, characterized in that: In step 4, the octagonal groove (3) includes 4 first groove sidewalls (31) and 4 second groove sidewalls (32). The first groove sidewalls (31) and the second groove sidewalls (32) in the octagonal groove (3) are spaced apart and the length of the first groove sidewall (31) is greater than the length of the second groove sidewall (32). The intersection line between each first groove sidewall (31) and the bottom wall (30) of the groove is a crystal orientation mark (4).
9. The method for confirming the crystal orientation of a silicon wafer for a contact lithography machine according to claim 1, characterized in that: After step 4 is completed, the following steps are also included: Step 5: Place the pre-designed V-groove mask (5) with V-groove pattern (51) and V-groove Mark (52) on the silicon wafer (1); wherein the length direction of the V-groove on the V-groove mask (5) is parallel or perpendicular to the V-groove Mark (52); Step 6: Adjust the V-groove mask (5) so that the V-groove Mark (52) is parallel to at least one of the crystal orientation marks (4).