Etching equipment
By designing an inclined edge ring structure in the etching equipment, the problem of excessive difference in etching between the wafer center and the edge was solved, thereby improving etching uniformity and enhancing product performance stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUA HONG SEMICONDUCTOR MANUFACTURING (WUXI) LTD
- Filing Date
- 2026-04-17
- Publication Date
- 2026-06-02
AI Technical Summary
Existing etching equipment exhibits excessively large etching differences between the wafer center and edges, failing to meet production requirements and resulting in unstable product performance.
In the etching equipment, an edge ring structure is designed so that the top surface of the outer ring region is inclined relative to the top surface of the inner ring region and gradually increases along the first direction. This is used to compensate for the attenuation of plasma density and electric field intensity at the edge of the wafer and improve etching uniformity.
Without adjusting the plasma distribution, etching uniformity was significantly improved, the etching rate difference between the wafer center and edge was reduced, and the stability of product performance was enhanced.
Smart Images
Figure CN122138634A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor manufacturing technology, and more particularly to an etching apparatus. Background Technology
[0002] Etching is a crucial step in semiconductor manufacturing, working in conjunction with photolithography to achieve patterning. In the etching process, photoresist is first exposed using photolithography to form a pattern, and then the unprotected material layer is removed through etching, thus completing the pattern transfer.
[0003] As device feature sizes continue to shrink, advanced processes are placing increasingly higher demands on etching uniformity and performance requirements on existing etching equipment. Summary of the Invention
[0004] The technical problem solved by this invention is to provide an etching apparatus to improve etching uniformity.
[0005] To solve the above-mentioned technical problems, the present invention provides an etching device, comprising: an electrostatic chuck for carrying a wafer to be etched, wherein when the wafer to be etched is placed on the surface of the electrostatic chuck, the edge of the wafer to be etched protrudes from the sidewall of the electrostatic chuck; and an edge ring surrounding the electrostatic chuck, the edge ring comprising an inner ring area and an outer ring area, the outer ring area surrounding the inner ring area, the top surface of the inner ring area being lower than the top surface of the outer ring area, the top surface of the inner ring area being parallel to the surface of the electrostatic chuck, the top surface of the outer ring area being inclined relative to the top surface of the inner ring area, and the height of the top surface of the outer ring area gradually increasing along a first direction, the first direction being parallel to the surface of the electrostatic chuck and away from the electrostatic chuck.
[0006] Optionally, the angle between the top surface of the outer ring region and the top surface of the inner ring region ranges from 1° to 3°.
[0007] Optionally, the electrostatic chuck includes a main body area and a peripheral area, the peripheral area surrounding the main body area, and the surface of the peripheral area being lower than the surface of the main body area; the edge ring is disposed on the peripheral area and outside the peripheral area.
[0008] Optionally, when the wafer to be etched is placed on the surface of the main area, the edge of the wafer to be etched protrudes from the sidewall of the main area; the top surface of the inner ring area is lower than the surface of the main area, and the top surface of the outer ring area is higher than the surface of the main area.
[0009] Optionally, the edge ring has an annular groove at the bottom near the electrostatic chuck, the annular groove being located at the bottom of the inner ring area and adapted to the outer area of the electrostatic chuck for mounting the edge ring on the outer area of the electrostatic chuck.
[0010] Optionally, the annular slot may also extend to the bottom edge of the outer ring area.
[0011] Optionally, the height difference between the top surface of the inner ring area and the surface of the main body area ranges from 0.2 mm to 0.5 mm.
[0012] Optionally, when the wafer to be etched is placed on the surface of the electrostatic chuck, there is a first gap between the wafer to be etched and the outer ring area, the first gap being in the range of 1 mm to 2 mm.
[0013] Optionally, a second gap is provided between the edge ring and the electrostatic chuck, the size of which ranges from 0.3 mm to 0.5 mm.
[0014] Optionally, the inner ring of the edge ring has a pretreatment groove, which is located below the edge of the wafer to be etched or outside the edge of the wafer to be etched when the wafer to be etched is placed on the surface of the electrostatic chuck.
[0015] Optionally, it may also include: a protective layer located within the pretreatment tank; the material of the protective layer includes yttrium trioxide.
[0016] Optionally, the surface roughness of the edge ring is less than 2 μm.
[0017] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects: In the etching equipment provided by the technical solution of the present invention, it has been found through actual research that the etching rate of the wafer edge is strongly correlated with the thickness of the edge ring when the etching equipment is working. This causes the top surface of the outer ring area to be tilted relative to the top surface of the inner ring area, and the height of the top surface of the outer ring area gradually increases along a first direction. The first direction is parallel to the surface of the electrostatic chuck and away from the electrostatic chuck. This can effectively improve the etching uniformity without adjusting the plasma distribution. Attached Figure Description
[0018] Figures 1 to 2 This is a schematic diagram of the steps in a method for forming a semiconductor structure. Figure 3 This is a schematic diagram of a plasma etching machine. Figures 4 to 7 This is a schematic diagram of an etching apparatus according to an embodiment of the present invention, wherein, Figure 4 This is a top view of the etching equipment. Figure 5 for Figure 4 A schematic diagram of the cross-sectional structure along the EE1 direction. Figure 6 for Figure 5 Enlarged view of the local structure, Figure 7 for Figure 5 A magnified view of the edge ring in the image. Detailed Implementation
[0019] It should be noted that the terms "surface" and "on" in this specification are used to describe the relative spatial position and are not limited to whether there is direct contact.
[0020] As described in the background section, advanced manufacturing processes place increasingly higher demands on the performance of existing etching equipment. A semiconductor structure etching method will now be explained and analyzed.
[0021] Figures 1 to 2 This is a schematic diagram of the steps in a method for forming a semiconductor structure.
[0022] Please refer to Figure 1 A wafer 10 to be etched is provided, the wafer 10 to be etched includes an interlayer dielectric layer 100, a titanium nitride / titanium material layer 101 located on the surface of the interlayer dielectric layer 100, and an aluminum material layer 102 located on the surface of the adhesion layer 101. The wafer 10 to be etched includes a central region I and an edge region II surrounding the central region I. A patterned photoresist layer 103 is formed on the surface of the aluminum material layer 102.
[0023] Please refer to Figure 2 Using the photoresist layer 103 as a mask, the aluminum material layer 102 is etched to form an aluminum pad layer 104.
[0024] Figure 3 This is a schematic diagram of a plasma etching machine.
[0025] Please refer to Figure 3 In the above method for forming a semiconductor structure, the etching process of the aluminum material layer 102 is completed by a plasma etching machine. The plasma etching machine includes: a cavity 20; an electrostatic chuck 201 placed in the cavity 20, the electrostatic chuck 201 being used to support the wafer 10 to be etched; and an edge ring 202 placed at the edge of the electrostatic chuck 201.
[0026] Here, etching gases such as Cl2 and BCl3 are used to form plasma 203 to etch the aluminum material layer 102. The edge ring 202 is used to compensate for the attenuation of plasma density and electric field intensity at the edge of the wafer 10 to be etched, thereby improving the uniformity of etching.
[0027] However, the existing edge ring 202 structure still cannot meet production requirements. When the aluminum material layer 102 is too thick and the etching time is long, the difference in etching rate between the wafer edge and the center becomes more obvious, making it difficult to accurately determine the etching termination time using the EPD (Endpoint Detection) curve. Possible phenomena include: the aluminum material layer 102 on the edge region II is completely etched, while the center region I experiences over-etching, even reaching the interlayer dielectric layer 100; or, the aluminum material layer 102 on the center region I is completely etched, while the aluminum material layer 102 on the edge region II is not fully etched.
[0028] In addition, for certain models of equipment, such as the Lam Research 2300 Versys Metal model, the etching chamber 20 has a large volume and limited adjustable parameters (the distribution ratio of etching gas flow rate and power), making it difficult to improve etching uniformity by adjusting the plasma distribution.
[0029] In summary, in existing technologies, the etching difference between the wafer center and the edge is too large, which cannot meet production requirements and may even lead to product scrap, seriously affecting product performance.
[0030] To address the aforementioned issues, the present invention provides an etching apparatus in which, based on actual research, it has been found that the etching rate at the wafer edge is strongly correlated with the thickness of the edge ring during operation. This causes the top surface of the outer ring region to tilt relative to the top surface of the inner ring region, and the height of the top surface of the outer ring region gradually increases along a first direction, which is parallel to the surface of the electrostatic chuck and away from the electrostatic chuck. This effectively improves etching uniformity without requiring adjustments to the plasma distribution.
[0031] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0032] Figures 4 to 7 This is a schematic diagram of the structure of an etching device according to an embodiment of the present invention.
[0033] Please refer to Figures 4 to 7 , Figure 4 This is a top view of the etching equipment (the wafer 31 to be etched is omitted). Figure 5 for Figure 4 A schematic diagram of the cross-sectional structure along the EE1 direction. Figure 6 for Figure 5 Enlarged view of the local structure, Figure 7 for Figure 5The enlarged view of the edge ring in the image shows that the etching apparatus includes: an electrostatic chuck 30 for holding a wafer 31 to be etched, wherein when the wafer 31 is placed on the surface of the electrostatic chuck 30, the edge of the wafer 31 protrudes from the sidewall of the electrostatic chuck 30; and an edge ring 32 surrounding the electrostatic chuck 30, the edge ring 32 including an inner ring region a and an outer ring region b, the outer ring region b surrounding the inner ring region a, the top surface of the inner ring region a being lower than the top surface of the outer ring region b, the top surface of the inner ring region a being parallel to the surface of the electrostatic chuck 30, the top surface of the outer ring region b being inclined relative to the top surface of the inner ring region a, and the height of the top surface of the outer ring region b gradually increasing along a first direction X, the first direction X being parallel to the surface of the electrostatic chuck 30 and away from the electrostatic chuck 30.
[0034] Actual research revealed that during operation, the etching rate at the wafer edge is strongly correlated with the thickness of the edge ring 32. Therefore, by tilting the top surface of the outer ring region b relative to the top surface of the inner ring region a, and gradually increasing the height of the top surface of the outer ring region b along the first direction X, the etching uniformity can be effectively improved without adjusting the plasma distribution.
[0035] It should be noted that when the etching equipment is working, the plasma generated by the reactive gas bombards the surface of the wafer 31 to be etched, thereby etching the wafer 31. The edge ring 32 is used to compensate for the attenuation of plasma density and electric field intensity at the edge of the wafer 31 to be etched, thereby improving the uniformity of etching (see details). Figure 3 The technical solution of this invention improves etching uniformity by tilting the top surface of the outer ring region b of the edge ring 32. Under the premise that other conditions (such as etching process parameters) remain unchanged, the top surface of the outer ring region b is relatively set to a horizontal direction. It has been verified that the etching uniformity of the wafer can be reduced from 15% to 6% during the etching process of the material film.
[0036] It should be further noted that the technical solution of the present invention is not only applicable to the Lam Research 2300 Versys Metal model, but also to other etching machines.
[0037] The tilt angle α between the top surface of the outer ring region b and the top surface of the inner ring region a ranges from 1° to 3°. Under this tilt angle α range, better etching uniformity can be obtained.
[0038] In this embodiment, the tilt angle α between the top surface of the outer ring region b and the top surface of the inner ring region a is 1.5°.
[0039] In this embodiment, the electrostatic chuck 30 includes a main body area i and a peripheral area ii, the peripheral area ii surrounds the main body area i, and the surface of the peripheral area ii is lower than the surface of the main body area i.
[0040] Specifically, when the wafer 31 to be etched is placed on the surface of the main body region i, the edge of the wafer 31 to be etched protrudes from the sidewall of the main body region i.
[0041] In this embodiment, the edge ring 32 is disposed on the outer periphery region ii and outside the outer periphery region ii.
[0042] In this embodiment, the top surface of the inner ring region a is lower than the surface of the main body region i, and the top surface of the outer ring region b is higher than the surface of the main body region i.
[0043] In this embodiment, the height difference Δh between the top surface of the inner ring region a and the surface of the main body region i ranges from 0.2 mm to 0.5 mm. The purpose of selecting this height difference Δh is that, when the etching equipment is working, the electrostatic chuck 30 can change the distribution of plasma near the edge of the wafer 31 to be etched.
[0044] In this embodiment, when the wafer 31 to be etched is placed on the surface of the electrostatic chuck 30, a first gap g1 is formed between the wafer 31 to be etched and the outer ring region b. The range of the first gap g1 is 1 mm to 2 mm. The purpose of selecting the range of the first gap g1 is to concentrate the energy of the plasma while reducing adverse effects on the wafer.
[0045] In this embodiment, a second gap g2 is provided between the edge ring 32 and the electrostatic chuck 30, and the size of the second gap g2 ranges from 0.3 mm to 0.5 mm. Specifically, a second gap g2 is provided between the inner ring region a and the main body region i. The purpose of selecting the range of the second gap g2 is to concentrate the energy of the plasma while reducing the problem of abnormal discharge between the plasma and the electrostatic chuck 30.
[0046] In this embodiment, when the wafer 31 to be etched is placed on the surface of the electrostatic chuck 30, the inner ring region a extends into the space below the wafer 31 by a first width L1, which ranges from 1 mm to 1.5 mm. The purpose of selecting the first width L1 is to enable the edge ring 32 to effectively control the plasma density near the edge of the wafer 31 to be etched, thereby further improving the etching uniformity.
[0047] In this embodiment, the edge ring 32 has an annular groove 321 at the bottom of the side near the electrostatic chuck 30. The annular groove 321 is located at the bottom of the inner ring area a. The annular groove 321 is adapted to the outer periphery area ii of the electrostatic chuck 30 and is used to install the edge ring 32 on the outer periphery area ii of the electrostatic chuck 30.
[0048] In this embodiment, the annular slot 321 also extends to the bottom edge of the outer ring area ii.
[0049] The inner ring region has a first thickness D1.
[0050] In this embodiment, the first thickness D1 is 3.88 mm.
[0051] The top surface of the outer ring region b has a first height h1 relative to the top surface of the inner ring region a at the end near the inner ring region a, and a second height h2 relative to the top surface of the inner ring region a at the end away from the inner ring region a.
[0052] In this embodiment, the difference between the second height h2 and the first height h1 is 0.474 mm.
[0053] In this embodiment, the inner ring area a of the edge ring 32 has a pretreatment groove 322. When the wafer 31 to be etched is placed on the surface of the electrostatic chuck 30, the pretreatment groove 322 is located below the edge of the wafer 31 to be etched, or located outside the edge of the wafer 31 to be etched.
[0054] It should be noted that the plasma generated by the etching equipment during operation etches the edge ring 32 below the edge of the wafer 10 to be etched. Over time, etching grooves will form on the surface of the edge ring 32. The depth and morphology of the etching grooves are not stable, and the instability of the etching environment will affect the stability of product performance. In the technical solution of this invention, the pretreatment groove 322 is formed in the inner ring area a beforehand, so that the edge ring 32 can reach a relatively stable state in the early stage of use, thereby improving the stability of the etching environment and thus improving the stability of product performance.
[0055] In this embodiment, no protective layer is provided in the pretreatment tank 322.
[0056] In another embodiment, a protective layer is further provided in the pretreatment tank. When the etching equipment is in operation, the protective layer can reduce the erosion of the edge ring by the plasma, improve the durability of the edge ring, and improve the stability of the etching environment, thereby improving the stability of product performance.
[0057] In this embodiment, the material of the protective layer includes yttrium trioxide.
[0058] In this embodiment, the electrostatic chuck 30 is made of ceramic.
[0059] In this embodiment, the surface roughness of the edge ring 32 is less than 2 μm. The purpose of selecting this surface roughness is to reduce polymer buildup on the surface of the edge ring 32 during the etching process, thereby reducing wear on the edge ring 32 and improving the stability of the etching environment.
[0060] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.
Claims
1. An etching apparatus, characterized in that, include: An electrostatic chuck is used to hold a wafer to be etched. When the wafer to be etched is placed on the surface of the electrostatic chuck, the edge of the wafer to be etched protrudes from the side wall of the electrostatic chuck. An edge ring is provided surrounding the electrostatic chuck, the edge ring including an inner ring area and an outer ring area, the outer ring area surrounding the inner ring area, the top surface of the inner ring area being lower than the top surface of the outer ring area, the top surface of the inner ring area being parallel to the surface of the electrostatic chuck, the top surface of the outer ring area being inclined relative to the top surface of the inner ring area, and the height of the top surface of the outer ring area gradually increasing along a first direction, the first direction being parallel to the surface of the electrostatic chuck and away from the electrostatic chuck.
2. The etching apparatus as described in claim 1, characterized in that, The angle between the top surface of the outer ring area and the top surface of the inner ring area ranges from 1° to 3°.
3. The etching apparatus as described in claim 1, characterized in that, The electrostatic chuck includes a main area and a peripheral area, the peripheral area surrounds the main area, and the surface of the peripheral area is lower than the surface of the main area; the edge ring is disposed on the peripheral area and outside the peripheral area.
4. The etching apparatus as described in claim 3, characterized in that, When the wafer to be etched is placed on the surface of the main area, the edge of the wafer to be etched protrudes from the sidewall of the main area; the top surface of the inner ring area is lower than the surface of the main area, and the top surface of the outer ring area is higher than the surface of the main area.
5. The etching apparatus as described in claim 3, characterized in that, The edge ring has an annular groove at its bottom near the electrostatic chuck. The annular groove is located at the bottom of the inner ring area and is adapted to the outer area of the electrostatic chuck to allow the edge ring to be mounted on the outer area of the electrostatic chuck.
6. The etching apparatus as described in claim 5, characterized in that, The annular slot also extends to the bottom edge of the outer ring area.
7. The etching apparatus as described in claim 3, characterized in that, The height difference between the top surface of the inner ring area and the surface of the main body area ranges from 0.2 mm to 0.5 mm.
8. The etching apparatus as described in claim 3, characterized in that, When the wafer to be etched is placed on the surface of the electrostatic chuck, there is a first gap between the wafer to be etched and the outer ring area, the first gap being 1 mm to 2 mm.
9. The etching apparatus as described in claim 3, characterized in that, There is a second gap between the edge ring and the electrostatic chuck, the size of which ranges from 0.3 mm to 0.5 mm.
10. The etching apparatus as claimed in claim 1, characterized in that, The inner ring of the edge ring has a pretreatment groove. When the wafer to be etched is placed on the surface of the electrostatic chuck, the pretreatment groove is located below the edge of the wafer to be etched, or located outside the edge of the wafer to be etched.
11. The etching apparatus as described in claim 10, characterized in that, Also includes: A protective layer located within the pretreatment tank; the material of the protective layer includes yttrium oxide.
12. The etching apparatus as described in claim 1, characterized in that, The surface roughness of the edge ring is less than 2 μm.