Compensation ring structure for compensating edge effect and improving etching uniformity
By using the compensation ring structure in dry etching, the problem of reducing etch uniformity caused by edge effect is solved, and higher etch uniformity and higher wafer utilization are achieved.
Patent Information
- Application Number
- CN202420233812.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-31
- Publication Date
- 2025-02-25
- Estimated Expiration
- 2034-01-31
AI Technical Summary
During dry etching, edge effect leads to a reduction in etching uniformity, especially on small-sized wafers, where etching uniformity sometimes even exceeds 5%, affecting process efficiency and product quality.
A compensation ring structure is adopted, and its ring is placed on the periphery of the wafer to be etched to expand the equivalent area of the wafer, thereby compensating for edge effects and improving etch uniformity. The inner diameter of the compensation ring is slightly larger than the outer diameter of the wafer to be etched, and the height is the same as the wafer to be etched. The material can be selected as the etching tray, mask or wafer.
By using the compensation ring structure, the etch uniformity is significantly improved, from 2.5% to 1.1%, reducing the negative impact of edge effect on etch uniformity, and improving wafer utilization and etch efficiency.
Smart Images
Figure CN222530373U_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of micro-nano processing, and in particular relates to a compensation ring structure for compensating edge effects and improving etching uniformity. Background Art
[0002] Dry etching is a micro-nano processing technology that uses plasma to etch materials. Compared with wet etching, dry etching has good etching directionality and the pattern size is easy to accurately control. Dry etching mainly includes reactive ion etching and inductively coupled plasma etching. The basic principle of reactive ion etching is that the reactive gas generates plasma between the plate electrodes, and the material is etched by plasma bombardment and reaction. The basic principle of inductively coupled plasma etching is that the reactive gas forms a high-density plasma in the induced electric field of the spiral coil, and then reaches the material surface through the parallel electric field of the plate to bombard and react to achieve material etching. Therefore, the etching rate of inductively coupled plasma can be significantly improved.
[0003] Etching uniformity is an important indicator of dry etching and is affected by many factors. For example, the gas flow distribution of the reaction gas, the uniformity of substrate heating, the distribution of the induced electric field, the distribution of the parallel electric field, etc. By reasonably designing the structural parameters of the etching equipment, the influence of these factors can be effectively reduced. At present, the etching uniformity of the mainstream dry etcher reaches less than 5% in the 6-inch area. In theory, the smaller the wafer size, the better the etching uniformity. However, in the actual etching process, the etching uniformity of small-sized wafers sometimes even exceeds 5%. This is mainly caused by the edge effect. During the etching process, the etched surface in the middle area can only receive plasma supply from directly above, while the edge part has a more sufficient supply concentration due to multiple supply directions, and the plasma supply concentration shows an edge effect that increases from the center to the edge. Therefore, the center and the edge show differences in etching rate due to the difference in plasma supply concentration. The edge effect further reduces the etching uniformity, and the smaller the wafer size, the greater the impact of the edge effect.
[0004] In the journal article "Xie Xiaoqiang et al. Edge Effect and Compensation Method in Reactive Ion Etching. Vacuum Electronic Technology. 2005(02): 41-44", for a specific etching pattern, an etching compensation band of a certain width is introduced in a surrounding manner, and the relative position of the required etching pattern is adjusted to the center of the overall etching area, so that the etching rate of each part is kept at the same level, thereby obtaining a uniform etching result. However, in actual production, this type of compensation band directly set on the wafer will waste a large amount of wafer area and have a low wafer utilization rate.
[0005] The above method of directly introducing the etching compensation band on the wafer through mask design will result in low wafer area utilization, greatly waste wafer materials, and is not suitable for actual production.
[0006] In order to solve the above problems, a compensation ring structure was developed to compensate for the edge effect and improve etching uniformity. Summary of the invention
[0007] The above object of the present invention is achieved by the following technical solution: a compensation ring structure for compensating edge effect and improving etching uniformity. The height of the compensation ring is consistent with the height of the wafer to be etched, the inner diameter of the compensation ring is slightly larger than the outer diameter of the wafer to be etched and the difference between the two is as small as possible, the outer diameter of the compensation ring does not exceed the diameter of the etching tray, and the material of the compensation ring can be the same as that of the etching tray, etching mask or wafer to be etched.
[0008] The material of the compensation ring can be the same as that of the etching tray, etching mask or wafer to be etched.
[0009] The compensation ring is not limited to a circular ring structure, and a special polygonal surrounding structure can be customized according to the shape of the wafer to be engraved.
[0010] During etching, the compensation ring is placed around the periphery of the wafer to be etched, so as to spatially expand the equivalent area of the wafer to be etched, thereby compensating for the edge effect and improving the etching uniformity.
[0011] Among them: the steps of using the compensation ring mainly include:
[0012] S1: Using SENTECH SI500 ICP dry etching system, the etching experiment of GaAs wafer to be etched is carried out;
[0013] S2: using laser cutting method to make etched compensation ring;
[0014] S3: Apply thermal conductive silicone oil on the back of the GaAs wafer to be etched, and then place it in the center area of the 6-inch Si etching tray;
[0015] S4: Putting an etching compensation ring around the GaAs wafer to be etched;
[0016] S5: placing the entire etching tray together with the GaAs wafer to be etched and the etching compensation ring into the etching system for dry etching;
[0017] S6: Remove the etching compensation ring.
[0018] Preferably, the specific values of the etching system described in step 1 include that the diameter of the 2-inch GaAs wafer to be etched is 50.8 mm and the thickness is 500 μm, the etching tray uses a 6-inch single-throw Si wafer, and the etching gas uses a mixed gas of BCl3, H2, CH4, and Ar, which basically does not etch Si.
[0019] Preferably, in step 2, a 4-inch single-polished Si wafer with a thickness of 500 μm is selected as the etching compensation ring, and a high-power laser scanning is used to cut off a 2-inch area in the center to form an etching compensation ring. The size of the GaAs wafer to be etched has a certain error, and laser cutting also has a processing error. Considering these factors, in order to be able to place the 2-inch GaAs wafer to be etched into the etching compensation ring, the inner diameter of the etching compensation ring needs to be larger than 2 inches. The inner diameter of the compensation ring finally cut is 51.3 mm, which is 0.5 mm larger than the diameter of the GaAs wafer to be etched.
[0020] Preferably, in step three, the height of the etched compensation ring and the GaAs wafer to be etched are consistent, and the gap between the two does not exceed 500 μm.
[0021] Preferably, no obvious etching marks appear on the surfaces of the etching tray Si wafer and the etching compensation ring, and the etching compensation ring can be reused as many times as the etching tray Si wafer.
[0022] In summary, the present invention includes at least one of the following beneficial technical effects:
[0023] The present invention provides a compensation ring structure for compensating edge effects and improving etching uniformity. During etching, the compensation ring is placed around the periphery of a wafer to be etched, so as to expand the equivalent area of the etched wafer and achieve the effect of compensating edge effects and improving etching uniformity. The compensation ring structure is simple to manufacture and customize, has low cost, does not require additional process steps, and can be effectively used to improve etching uniformity. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is the main schematic diagram of the compensation ring of the utility model used in the etching device;
[0025] Figure 2 It is a schematic diagram of the side of the compensation ring of the utility model used in the etching device;
[0026] Figure 3 It is a schematic diagram of the test point distribution diagram of the etched wafer of the utility model.
[0027] In the figure: 1 etching tray, 2 GaAs wafer to be etched, 3 compensation ring. DETAILED DESCRIPTION
[0028] The above-mentioned object of the present invention is achieved through the following technical solutions:
[0029] A compensation ring structure for compensating edge effects and improving etching uniformity, wherein: the method steps mainly include:
[0030] S1: Using SENTECH SI500 ICP dry etching system, the etching experiment of GaAs wafer 2 to be etched is carried out;
[0031] S2: using a laser cutting method to produce an etched compensation ring 3;
[0032] S3: The back side of the GaAs wafer 2 to be etched is coated with thermal conductive silicone oil, and then placed in the center area of the 6-inch Si etching tray;
[0033] S4: Putting an etching compensation ring around the GaAs wafer 2 to be etched;
[0034] S5: placing the entire etching tray 1 together with the GaAs wafer 2 to be etched and the etching compensation ring 3 into the etching system for dry etching;
[0035] S6: Remove the etching compensation ring 3.
[0036] Specifically, the specific values of the etching system described in step 1 include that the diameter of the 2-inch GaAs wafer 2 to be etched is 50.8 mm and the thickness is 500 μm, the etching tray 1 uses a 6-inch single-throw Si wafer, and the etching gas uses a mixed gas of BCl3, H2, CH4, and Ar. This mixed gas basically does not etch Si.
[0037] Specifically, in step 2, the etching compensation ring 3 uses a 500 μm thick 4-inch single-polished Si wafer, and then uses high-power laser scanning to cut off a 2-inch area in the center to form an etching compensation ring 3. The size of the GaAs wafer 2 to be etched has a certain error, and laser cutting also has a processing error. Considering these factors, in order to be able to place the 2-inch GaAs wafer 2 to be etched into the etching compensation ring 3, the inner diameter of the etching compensation ring 3 needs to be larger than 2 inches. The inner diameter of the compensation ring finally cut is 51.3 mm, which is 0.5 mm larger than the diameter of the GaAs wafer 2 to be etched.
[0038] Specifically, in step 3, the etched compensation ring 3 and the GaAs wafer 2 to be etched are in the same height, and the gap between the two does not exceed 500 μm.
[0039] Specifically, no obvious etching marks appear on the surfaces of the etching tray 1 Si wafer and the etching compensation ring 3, and the etching compensation ring 3 can be reused as many times as the etching tray 1 Si wafer.
[0040] First, the etching compensation ring is customized according to the size of the wafer to be etched. The inner diameter of the compensation ring is slightly larger than the outer diameter of the wafer to be etched. In order to achieve the best effect, the difference between the inner diameter of the compensation ring and the outer diameter of the GaAs wafer to be etched should be as small as possible, and the difference range is preferably 100~500μm. The height of the compensation ring is consistent with the wafer to be etched. The outer diameter of the compensation ring is smaller than the outer diameter of the etching tray. In order not to contaminate the GaAs wafer to be etched and the etching system, the material of the etching compensation ring can be selected from the same material as the etching tray, etching mask or GaAs wafer to be etched. The compensation ring processing method can be laser cutting, wet etching, dry etching, etc.
[0041] Place the GaAs wafer to be etched in the middle area of the etching tray, and apply thermal conductive silicone oil on the back of the GaAs wafer to be etched. Then put the etching compensation ring around the GaAs wafer to be etched, and put the entire etching tray, the wafer to be etched, and the compensation ring into the etching system for dry etching. Since the compensation ring and the GaAs wafer to be etched are highly consistent, and there is only a gap of hundreds of microns between the two, the purpose of expanding the equivalent area of the wafer in space is achieved, and the effect of compensating the edge effect and improving the etching uniformity is achieved.
[0042] After etching is completed, remove the etching compensation ring from the etching tray and reuse it after cleaning. The number of reuses is determined by the material selected for the etching compensation ring, the etching depth, and the surface cleanliness. For example, if the material of the compensation ring is the same as the material of the wafer to be etched, the material will be etched and lost quickly, and the number of reuses will be relatively small. If the material of the compensation ring is the same as the etching tray, the material will be etched and lost less, and the number of reuses will be relatively large.
[0043] Comparative example: In order to verify the effect of the etching compensation ring, an etching control experiment without the etching compensation ring was also carried out, and other etching parameters remained unchanged. The etching time was 15 minutes, and the etching depth was measured using a step profiler after the etching was completed. Figure 3 This is the distribution diagram of the test points of the 2-inch GaAs wafer step profiler. The 9 test points are evenly distributed horizontally and vertically on the surface of the 2-inch wafer. Table 1 shows the etching depth of the GaAs wafer without and with the etching compensation ring. It can be seen that the etching depth generally increases from the center to the edge. After adding the compensation ring, the etching uniformity is significantly improved from 2.5% to 1.1%.
[0044] Table 1 Etching depth of GaAs wafer without and with etching compensation ring
[0045] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A compensation ring structure for compensating edge effects and improving etching uniformity, comprising an etching tray, characterized in that: A GaAs wafer to be etched is fixed at the center of the etching tray through heat-conducting silicone oil, an etching compensation ring is sleeved on the outer side of the GaAs wafer to be etched, and a mixed gas is filled in the etching structure environment.
2. The compensation ring structure for compensating edge effect and improving etching uniformity according to claim 1, characterized in that: The etching tray is 6 inches in size, the etching compensation ring is a 4-inch single-throw Si wafer with a thickness of 500 μm, and the GaAs wafer to be etched is 2 inches in size, with a diameter of 50.8 mm and a thickness of 500 μm.
3. The compensation ring structure for compensating edge effect and improving etching uniformity according to claim 1, characterized in that: The etching tray is made of single-polished Si wafer.
4. The compensation ring structure for compensating edge effect and improving etching uniformity according to claim 1, characterized in that: The material of the compensation ring can be the same as that of the etching tray, etching mask or wafer to be etched.