Edge ring for etching and plasma etching equipment
By designing an annular edge ring to support and align with the wafer edge, the problem of edge non-uniformity during wafer etching is solved, resulting in higher etching uniformity and extended edge ring lifespan.
Patent Information
- Application Number
- CN202422891648.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-26
- Publication Date
- 2025-11-04
- Estimated Expiration
- 2034-11-26
AI Technical Summary
During wafer etching, the uneven etching depth at the wafer edge and the edge effect lead to an increase in the defect rate, mainly due to the edge effect of the upper and lower plates and the fact that the plasma is not perpendicular to the wafer surface.
Design an edge ring, a ring structure surrounding the wafer, with an inwardly protruding support section and an outwardly recessed docking section. The support surface is parallel to the end face to support the wafer, reduce the gap between the wafer edge and the plasma chamber, and improve etching uniformity through a stepped design.
It effectively reduces excessive etching at the wafer edges, improves etching uniformity, reduces defect rate, extends the lifespan of the edge ring, and reduces the generation of impurities at the wafer edges.
Smart Images
Figure CN223513907U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of plasma etching technology, specifically to an edge ring for etching and a plasma etching device. Background Technology
[0002] Plasma etching is one of the main processes in semiconductor manufacturing. Figure 1 This is a schematic diagram of plasma etching, showing a plasma etching chamber defined by an upper electrode 1, a lower electrode 2, and a defining ring 3. A wafer 4 is placed on the surface of the lower electrode within the chamber to receive plasma bombardment, resulting in the etching of a corresponding pattern on its surface.
[0003] The uniformity of wafer etching depth is a key quality concern in etching operations. Besides factors such as gas supply and electrode conditions causing uneven wafer etching, another systemic reason is the edge effect of the upper and lower electrodes, which leads to electric field distortion at the edges and the plasma at the edges no longer being perpendicular to the wafer surface. These factors result in uneven etching depth distribution at the wafer edges, increasing the number of defective wafers etched at the edges. Utility Model Content
[0004] In order to reduce the occurrence of edge defects during wafer etching in the prior art, this application provides an edge ring for etching and a plasma etching apparatus.
[0005] The technical solution of this utility model provides an edge ring for etching.
[0006] The edge ring is ring-shaped to surround the wafer; one side of the edge ring along the axial direction has a support section protruding towards the center, and the other side of the inner ring surface along the axial direction has a mating section recessed outward; the support surface engages the support section and the mating section, and the support surface is parallel to the end face of the edge ring to support the wafer.
[0007] Preferably, the distance between the bottom edge of the docking segment and the edge of the wafer is between 0.5 and 1.5 mm.
[0008] Preferably, the height of the mating segment is not less than the thickness of the wafer.
[0009] Preferably, the height of the docking section is 0.85-1.1 mm above the upper surface of the wafer.
[0010] Preferably, the mating section and the supporting surface form an obtuse angle. tilt.
[0011] Preferably, the angle between the docking section and the supporting surface is 140-145 degrees.
[0012] Preferably, the docking section is perpendicular to the supporting surface.
[0013] Preferably, it has a plasma etching chamber, and an edge ring as described in any of the above is provided in the support surface of the plasma etching chamber, the edge ring being used to support the wafer.
[0014] The etching edge ring of this application can be used to support the wafer, and improves the wafer etching effect through stepped mating sections and support surfaces when supporting the wafer. Its mating sections can fill the side space of the wafer, thereby avoiding excessive etching of the wafer edge and achieving the purpose of optimizing the uniformity of wafer etching. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of a plasma etching chamber in the prior art;
[0016] Figure 2 This is a schematic diagram of the edge ring for etching according to the present invention;
[0017] Figure 3 This is a partially enlarged schematic diagram of the edge ring for etching according to this utility model;
[0018] Figure 4 This is a schematic diagram illustrating the application of the etching edge ring of this utility model.
[0019] In the picture:
[0020] 1: Upper electrode; 2: Lower electrode; 3: Limiting ring; 4: Wafer; 5: Edge ring; 51: Inner ring surface; 511: Support segment; 512: Docking segment; 513: Support surface. Detailed Implementation
[0021] The present patent type will be described in detail below with reference to the accompanying drawings and specific embodiments. In this specification, the dimensions in the drawings do not represent actual size ratios. The drawings are only used to illustrate the relative positional and connection relationships between the components. Components with the same name or the same reference numerals represent similar or identical structures and are limited to illustrative purposes.
[0022] The technical solution of this application is to provide an edge ring used in the etching process to support and align the wafer edge, thereby reducing the gap and height difference between the wafer edge and the plasma chamber, and thus reducing the occurrence of etching defects at the wafer edge due to this structure.
[0023] Figure 2 This is a schematic diagram of the edge ring structure of this application. Figure 3This is an enlarged schematic diagram of a portion of the edge ring of this application. To reduce the exposed gap at the edge of wafer 4 and decrease the height difference of the exposed wafer edge, the edge ring has a specially designed inner ring surface 51. On one side of the inner ring surface 51 along the axial direction, there is a support section 511 protruding towards the center of the ring; on the other side of the inner ring surface 51 along the axial direction, there is a correspondingly recessed mating section 512. (Reference) Figure 4 The diagram illustrates the application of the edge ring, where the support segment 511 protrudes inward to form a support surface 513. During etching, the edge ring 5 is placed on the lower electrode plate, with the support segment 511 positioned below the wafer 4. The support surface 513 supports the wafer 4, and the edge of the wafer 4 falls into the mating segment 512. The key is the design of the mating segment 512, which brings its surface close to the surface of the wafer 4, thereby compressing the gap between the mating segment 512 and the edge of the wafer 4. This avoids large side gaps around the edge of the wafer 4, reducing the possibility of poor etching at the wafer edge. The distance between the bottom edge of the mating segment 512 and the edge of the wafer should be approximately 0.5-1.5 mm. This distance should not be further reduced because sufficient space needs to be reserved for the wafer 4 to avoid direct contact between the wafer and the mating segment 51 during placement, preventing collisions and tilting of the wafer resting on the mating segment 512. Preferably, the height of the mating segment 512 should not be less than the thickness of the wafer to avoid the upper surface of the wafer 4 being higher than the mating segment 512 when it is placed in the mating segment 512, thus still exposing a large side space. The mating segment 512 may be formed perpendicular to the support surface 513 on the inner annular surface 51.
[0024] During the etching process, both the mating section 512 and the wafer 4 are directly exposed to the plasma environment and are simultaneously subjected to the corrosive effects of the plasma. As a result, the shape and size of the mating section 512 will gradually degrade. To ensure the edge ring 5 has a service life of 800 hours, the height of the mating section 512 is preferably 0.85-1.1 mm higher than the upper surface of the wafer 4. As etching occurs, the higher portion is gradually etched and thinned, thereby extending its service life.
[0025] Because the thickness of the mating section 512 is slightly higher than that of wafer 4, it has an additional side effect on the etching of the edge of wafer 4, resulting in a significant decrease in the etching amount at the edge, and the etching material of the mating section 512 may also remain at the edge of wafer 4, forming impurities. Therefore, it is preferable that the mating section 512 forms an obtuse angle with the support surface 513. The tilt angle compensates for the increased height on etching uniformity by widening the gap between the edges of the upper surface, and also makes the upper part of the mating section 512 farther away from the edge of wafer 4, reducing the incidence of edge impurities. Considering both the etching rate and lifespan of the mating section 512, this angle is preferably between 140 and 145 degrees.
[0026] This application also claims protection for a plasma etching apparatus comprising a plasma etching chamber defined by an upper electrode 1, a lower electrode 2, and a defining ring 3. To improve the etching uniformity of the wafer 4, an edge ring 5 is additionally installed on the inner surface of the lower electrode 2 for supporting and positioning the wafer 4. The presence of the wafer 4 avoids the problem of a large amount of plasma-filled space on the sides of the wafer 4, thereby preventing over-etching of the edges of the wafer 4.
[0027] The above description is merely a preferred embodiment of this patent type and is not intended to limit the scope of this patent type. Without departing from the design spirit of this patent type, all modifications and improvements made by those skilled in the art to the technical solutions of this patent type should fall within the protection scope defined by the claims of this patent type.
Claims
1. An edge ring for etching, characterized in that, The edge ring is annular to surround the wafer (4); the edge ring (5) has an inner ring surface (51); the inner ring surface (51) has a support section (511) protruding towards the center on one side along the axial direction, and a mating section (512) recessed outward on the other side along the axial direction; the support surface (513) engages the support section (511) and the mating section (512), and the support surface (513) is parallel to the end face of the edge ring to support the wafer (4).
2. The edge ring for etching as described in claim 1, characterized in that, The distance between the bottom edge of the docking section (512) and the edge of the wafer (4) is between 0.5 and 1.5 mm.
3. The edge ring for etching as described in claim 1, characterized in that, The height of the docking section (512) is not less than the thickness of the wafer (4).
4. The edge ring for etching as described in claim 3, characterized in that, The height of the docking section (512) is 0.85-1.1 mm higher than the upper surface of the wafer (4).
5. The edge ring for etching as described in claim 3, characterized in that, The docking section (512) and the supporting surface (513) form an obtuse angle. tilt.
6. The edge ring for etching as described in claim 5, characterized in that, The angle between the docking section (512) and the supporting surface (513) is 140-145 degrees.
7. The edge ring for etching as claimed in claim 1, characterized in that, The docking section (512) is perpendicular to the supporting surface (513).
8. A plasma etching apparatus, characterized in that, It has a plasma etching chamber, and an edge ring (5) as described in any one of claims 1-7 is provided in the support surface of the plasma etching chamber, the edge ring (5) being used to support the wafer (4).