A method for controlling the etching uniformity of glass wafers
By using PECVD coating and dry etching technology, the depth and morphology of the etched holes in glass wafers are controlled, solving the problem of poor hole depth uniformity in micro-nano grating devices, improving product sensitivity, and eliminating chuck marks in bottom light source inspection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 杭州邦齐州科技有限公司
- Filing Date
- 2024-02-22
- Publication Date
- 2026-07-17
AI Technical Summary
In the fabrication of micro/nano grating devices, existing technologies suffer from poor hole depth uniformity during glass wafer etching, which affects product sensitivity.
The process involves PECVD deposition, coating with antireflective adhesive and photoresist layers, photolithography to form a periodic array of holes, and then using a dry etching machine for oxygen plasma hole enlargement etching and fluorine-containing gas etching to control the depth, morphology, and perpendicularity of the etched holes, while adjusting the RF/LF power and etching time.
It improves the uniformity of hole depth in glass wafers from the traditional 12% to less than 5%, enhances product sensitivity, and avoids suction cup marks in bottom light source inspection.
Smart Images
Figure CN118307209B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of semiconductor manufacturing, and particularly relates to a method for controlling the etching uniformity of glass wafers. Background Technology
[0002] In the fabrication of micro / nano grating devices, a periodic array of holes needs to be created. The uniformity of hole depth affects the product's sensitivity, and as sensitivity requirements increase, so does the requirement for hole depth uniformity. Currently, conventional methods for controlling hole depth uniformity all start with the etching process, which results in relatively poor hole depth uniformity. Summary of the Invention
[0003] The purpose of this invention is to solve the problems in the background art and to propose a method for controlling the etching uniformity of glass wafers.
[0004] To achieve the above objectives, this invention proposes a method for controlling the etching uniformity of glass wafers, comprising the following steps:
[0005] A silicon dioxide film is deposited on the surface of a glass wafer using the PECVD coating method, and the glass wafer is then cleaned after coating.
[0006] A narrow-slit suction cup is used to place the glass wafer to be coated into the coating chamber of the coating machine. An anti-reflective adhesive layer and a photoresist layer are coated sequentially from bottom to top on the surface of the silicon dioxide film. During the coating process, the deformation of the glass wafer is controlled to not exceed 1µm.
[0007] Photolithography is performed on the photoresist layer to form a periodic array of holes on the photoresist layer;
[0008] The photolithographically etched glass wafer is placed into the cavity of a dry etching machine. Oxygen is introduced to perform oxygen plasma etching on the anti-reflective layer that has lost the protection of the photoresist layer, and the corresponding anti-reflective layer is removed, so that etching holes are formed at the etched locations of the anti-reflective layer.
[0009] The silicon dioxide film layer below the etching hole is etched using a fluorine-containing gas, so that the silicon dioxide film layer forms a periodic array of holes.
[0010] The depth, morphology, and perpendicularity of the etched holes are controlled by adjusting the RF / LF power and etching time. The RF power is 50W-200W, the LF power is 100W-500W, and the etching time for plasma hole enlargement etching is 20s-50s.
[0011] It should be noted that, under the same conditions, the longer the etching time, the deeper the hole; when other conditions remain unchanged, the perpendicularity first increases and then decreases with the LF power, and the etching morphology becomes worse and worse with the increase of LF power, while the etching depth becomes deeper and deeper; when other conditions remain unchanged, the etching depth increases with the increase of RF power, and the morphology of the etched hole becomes worse and worse.
[0012] Preferably, the thickness of the anti-reflective adhesive layer is controlled such that the reflectivity of the glass wafer after coating the anti-reflective adhesive layer does not exceed 5%.
[0013] Preferably, the thickness of the antireflective adhesive layer is 210±30nm.
[0014] Preferably, the thickness of the photoresist layer is 750±40nm.
[0015] Preferably, the uniformity of the periodic array apertures does not exceed 5%.
[0016] Preferably, the glass wafer is 4 inches in size.
[0017] Preferably, the glass wafer is subjected to acid washing and cleaning treatment after coating.
[0018] Preferably, the photoresist layer is exposed and then baked to obtain a periodic array of holes.
[0019] Preferably, the etching time of the silicon dioxide film by the fluorine-containing gas is 200s-250s.
[0020] The beneficial effects of the present invention are as follows: Without adding additional testing equipment, the present invention can improve the uniformity of hole depth on glass wafers from the traditional 12% to less than 5%, and after etching and removing the resist, the appearance of the bottom light source inspection is free of suction cup marks, which significantly improves the sensitivity of the product.
[0021] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the structure of a glass wafer after a silicon dioxide film layer is deposited on its surface, according to an embodiment of the present invention.
[0023] Figure 2 This is a schematic diagram of the structure after coating the silicon dioxide film surface with an antireflective adhesive layer and a photoresist layer according to an embodiment of the present invention.
[0024] Figure 3 This is a schematic diagram of the structure of the photoresist layer after development according to an embodiment of the present invention.
[0025] Figure 4 This is a schematic diagram of the structure of the anti-reflective adhesive layer after etching and removal, according to an embodiment of the present invention.
[0026] Figure 5 This is a schematic diagram of the structure of the silicon dioxide film after dry etching according to an embodiment of the present invention.
[0027] In the figure: 1-glass wafer, 2-silicon dioxide film, 3-antireflective adhesive layer, 4-photoresist layer, 21-periodic array aperture. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.
[0029] See Figures 1 to 5 This embodiment provides a method for controlling the etching uniformity of glass wafers, including the following steps:
[0030] After cleaning the 4-inch glass wafer, a silicon dioxide film layer 2 is deposited on the surface of the glass wafer 1 using the PECVD coating method. The coated glass wafer 1 and silicon dioxide film layer 2 are then acid-washed and cleaned.
[0031] A narrow-slit suction cup is used to place the glass wafer 1 to be coated into the coating chamber of the coating machine. The anti-reflective adhesive layer 3 and the photoresist layer 4 are coated sequentially from bottom to top on the surface of the silicon dioxide film layer 2. During the coating process, the deformation of the glass wafer 1 is controlled to not exceed 1µm to ensure the uniformity of the anti-reflective adhesive layer 3.
[0032] Photolithography is performed on the photoresist layer 4, which includes exposure followed by baking and development, so that a periodic array of holes is formed on the photoresist layer 4.
[0033] The photolithographically etched glass wafer 1 is placed into the cavity of the dry etching machine. Oxygen is introduced to perform oxygen plasma hole enlargement etching on the anti-reflective adhesive layer 3 that has lost the protection of the photoresist layer 4 and remove the corresponding anti-reflective adhesive layer 3, so that the etched position of the anti-reflective adhesive layer 3 forms an etched hole. The etched hole is formed by further vertical etching downward on the basis of the periodic array hole pattern.
[0034] The silicon dioxide film layer 2 below the etching hole is etched using a fluorine-containing gas, so that the silicon dioxide film layer 2 forms a periodic array of holes 21, wherein the periodic array of holes 21 is formed by further vertically etching downward based on the etching hole;
[0035] The depth of the etched holes is controlled by adjusting the etching time, and the morphology and perpendicularity of the etched holes are controlled by adjusting the power of the RF / LF. The glass wafer 1 is a quartz substrate, the RF power is 50W-200W, the LF power is 100W-500W, and the etching time of the plasma hole enlargement etching is 20s-50s. This etching time can ensure that the anti-reflective adhesive layer 3 is completely removed, so that the bottom surface of the etched hole just reaches the surface of the silicon dioxide film layer 2.
[0036] The thickness of the anti-reflective adhesive layer 3 is controlled such that the reflectivity of the glass wafer 1 after coating the anti-reflective adhesive layer 3 does not exceed 5%, and the thickness of the anti-reflective adhesive layer 3 is 210±30nm, preferably 210nm.
[0037] The thickness of the photoresist layer 4 is 750±40nm, preferably 750nm.
[0038] The uniformity of hole depth in the periodic array of holes 21 does not exceed 5%.
[0039] The etching time of the silicon dioxide film by the fluorine-containing gas is 200s-250s.
[0040] This method controls the uniformity of hole depth through two stations: photolithography and etching, achieving a bottom light source appearance free of suction cup marks. Specifically, during the anti-reflective coating and photoresist coating processes, the anti-reflective coating thickness is controlled at 200±30nm, and the photoresist thickness is controlled at 750±40nm. A narrow-slit suction cup is used in the coating cavity to reduce the adsorption area, thereby reducing glass wafer variation and ensuring uniform photoresist coating. A periodic array of holes is formed on the photoresist layer through exposure / development, followed by dry etching of the anti-reflective coating layer. During etching, the oxygen plasma RF / LF power and hole expansion time are controlled to ensure that the hole diameter after oxygen plasma expansion is within the process requirements. The anti-reflective coating layer at the bottom of the etched holes is completely removed. Then, the silicon dioxide film layer is dry etched using a fluorine-containing etching gas. This method will not cause differences in the microscopic hole depth of the periodic array holes due to incomplete removal of the bottom anti-reflective adhesive layer in some opening areas, thus preventing the presence of suction cup marks on the macroscopic surface during bottom light source inspection.
[0041] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.
Claims
1. A method for controlling the etching uniformity of glass wafers, characterized in that, It includes the following steps: A silicon dioxide film is deposited on the surface of a glass wafer using the PECVD coating method, and the glass wafer is then cleaned after coating. A narrow-slit suction cup is used to place the glass wafer to be coated into the coating chamber of the coating machine. An anti-reflective adhesive layer and a photoresist layer are coated sequentially from bottom to top on the surface of the silicon dioxide film. During the coating process, the deformation of the glass wafer is controlled to not exceed 1µm. Photolithography is performed on the photoresist layer to form a periodic array of holes on the photoresist layer; The photolithographically etched glass wafer is placed into the cavity of a dry etching machine. Oxygen is introduced to perform oxygen plasma etching on the anti-reflective layer that has lost the protection of the photoresist layer, and the corresponding anti-reflective layer is removed, so that etching holes are formed at the etched locations of the anti-reflective layer. The silicon dioxide film layer below the etching hole is etched using a fluorine-containing gas, so that the silicon dioxide film layer forms a periodic array of holes. The depth, morphology, and perpendicularity of the etched holes are controlled by adjusting the RF / LF power and time. The RF power is 50W-200W, the LF power is 100W-500W, the plasma enlargement etching time is 20s-50s, the thickness of the antireflective adhesive layer is 210±30nm, and the thickness of the photoresist layer is 750±40nm.
2. The method for controlling the etching uniformity of glass wafers as described in claim 1, characterized in that: The thickness of the anti-reflective adhesive layer is controlled such that the reflectivity of the glass wafer does not exceed 5% after the anti-reflective adhesive layer is applied.
3. The method for controlling the etching uniformity of glass wafers as described in claim 1, characterized in that: The uniformity of the hole depth in the periodic array of holes does not exceed 5%.
4. The method for controlling the etching uniformity of glass wafers as described in claim 1, characterized in that: The glass wafer is 4 inches in size.
5. The method for controlling the etching uniformity of glass wafers as described in claim 1, characterized in that: After coating, the glass wafer undergoes acid washing and cleaning.
6. The method for controlling the etching uniformity of glass wafers as described in claim 1, characterized in that: The photoresist layer is exposed and then baked to obtain a periodic array of holes.
7. The method for controlling the etching uniformity of glass wafers as described in claim 1, characterized in that: The etching time of the silicon dioxide film by the fluorine-containing gas is 200s-250s.