Wafer chuck ring for dry etching and dry etching apparatus

Abstract

A wafer pressing ring for dry etching and a dry etching device, wherein the wafer pressing ring for dry etching has a ring shape formed by an inner ring and an outer ring, and the wafer pressing ring for dry etching comprises: a back surface, the back surface has a first step, the first step is arranged along the edge of the inner ring, and the first step extends along the circumference to form a ring step structure, the position of the first step is suitable for corresponding to the edge position of the wafer to fix the wafer, and the maximum cross-sectional diameter D of the inner ring is in the range of 143.7mmD145.7mm. The maximum cross-sectional diameter of the inner ring of the wafer pressing ring is larger, so that the area of the edge covering part of the wafer pressing ring to the wafer is smaller, the area of the edge of the wafer that cannot be etched is reduced, the probability that the edge of the wafer cannot be etched due to too much covering of the wafer pressing ring to the edge of the wafer is reduced, and the yield of the product is improved. Moreover, the maximum cross-sectional diameter D of the inner ring is not too large, avoiding the situation that the wafer pressing ring cannot press the wafer, reducing the probability that the position of the wafer changes, the etching precision decreases, and even affecting the yield of the product.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor technology, and in particular to a wafer clamping ring and dry etching equipment for dry etching. Background Technology

[0002] Vacuum chamber dry etching is a core process in semiconductor manufacturing that uses plasma to precisely remove materials in a vacuum environment. It is widely used in chip patterning (such as gate, via, and trench fabrication).

[0003] In dry etching processes, wafer clamping rings directly impact chip yield, process stability, and device performance. The core impact lies in three key dimensions: "fixation, protection, and process optimization," specifically: 1. Ensuring wafer mechanical stability and preventing process failure. Dry etching relies on high-energy plasma bombardment. If the wafer is not securely fixed, it can shift, warp, or even fly away due to the impact force, causing misalignment between the photolithography pattern and the etching result, directly resulting in chip scrap. The clamping ring, through mechanical clamping or vacuum adsorption, fixes the wafer edge to the support platform, ensuring the wafer remains flat under high vacuum and plasma impact conditions, providing a foundation for precise pattern transfer. 2. Protecting wafer edges and improving overall yield. Wafer edges are weak points in the process: during photoresist coating, edges are prone to "thick edges" or "insufficient resist." Without protection during etching, excessive plasma bombardment can lead to over-etching, edge chipping, or residual contaminants affecting subsequent processes.

[0004] However, current wafer clamping rings used for dry etching still have shortcomings. Utility Model Content

[0005] The technical problem solved by this invention is how to improve the structure of the wafer retaining ring used in dry etching in order to improve the yield of semiconductor devices.

[0006] To solve the above-mentioned technical problems, this utility model provides a wafer retaining ring for dry etching. The wafer retaining ring for dry etching has a radial cross-section that is annular, formed by an inner ring and an outer ring. The wafer retaining ring for dry etching includes a back surface, which has a first step. The first step is disposed along the edge of the inner ring and extends circumferentially to close and form an annular step structure. The position of the first step is suitable to correspond to the edge position of the wafer to fix the wafer. The maximum cross-sectional diameter D of the inner ring is in the range of 143.7 mm < D < 145.7 mm.

[0007] Optionally, the back surface includes a first portion, a second portion, and a third portion distributed radially in sequence. The first portion, the second portion, and the third portion all extend circumferentially and close together. The second portion connects the first portion and the third portion. The surface of the first portion is recessed into the third portion. A first step is formed between the first portion and the third portion.

[0008] Optionally, it also includes: a front surface having a second step, the position of which corresponds to the position of the first step.

[0009] Optionally, the inner ring of the wafer clamping ring used for dry etching is formed by an arc and a chord.

[0010] Optionally, the inner circle is circular.

[0011] Optionally, the minimum cross-sectional diameter d of the inner ring is in the range of 137.5 mm < d < 139.5 mm.

[0012] Optionally, the maximum ring width R of the wafer clamping ring used for dry etching is in the range of 90.1 mm < R < 91.1 mm.

[0013] Optionally, the minimum ring width r of the wafer retaining ring used for dry etching is in the range of 84.9 mm < r < 85.9 mm.

[0014] Accordingly, this utility model embodiment also provides a dry etching apparatus, comprising: a reaction chamber; a wafer retaining ring for dry etching as described in any of the preceding claims, the wafer retaining ring for dry etching being located within the reaction chamber, the back side of the wafer retaining ring for dry etching facing a first side of the wafer; and an air intake mechanism configured to introduce gas into the reaction chamber, the air intake mechanism having an outlet facing a second side of the wafer.

[0015] Compared with the prior art, the technical solution of this utility model embodiment has the following beneficial effects:

[0016] In the wafer retaining ring for dry etching of this invention, the first step is disposed along the edge of the inner ring, and the first step extends circumferentially to close and form an annular step structure. The position of the first step is suitable to correspond to the edge position of the wafer to fix the wafer. The maximum cross-sectional diameter D of the inner ring is in the range of 143.7 mm < D < 145.7 mm. The larger maximum cross-sectional diameter of the inner ring of the wafer retaining ring results in a smaller area of ​​the wafer edge covered by the wafer retaining ring, reducing the area of ​​the wafer edge that cannot be etched, reducing the probability of the wafer edge not being etched due to excessive coverage of the wafer edge by the wafer retaining ring, and improving the product yield. Furthermore, the maximum cross-sectional diameter D of the inner ring is not too large, avoiding the situation where the wafer retaining ring cannot hold the wafer, reducing the probability of wafer position changes, decreased etching accuracy, or even affecting product yield. Attached Figure Description

[0017] Figure 1 This is a top view of a wafer clamping ring;

[0018] Figure 2 This is a top view of the back side of the wafer retaining ring used for dry etching according to an embodiment of the present invention;

[0019] Figure 3 yes Figure 2 A schematic diagram of the cross-sectional structure of the wafer retaining ring used for dry etching at position A1A2;

[0020] Figure 4 This is a top view of the front of the wafer retaining ring used for dry etching according to an embodiment of the present invention. Detailed Implementation

[0021] As can be seen from the background technology, the wafer clamping rings used in existing dry etching techniques still have shortcomings. The reasons for these problems are analyzed below:

[0022] Wafer retainer rings are accessories required for the dry etching process of silicon nitride. The dry etching process on the wafer surface requires the use of wafer retainer rings on the wafer surface (to prevent back helium).

[0023] Please refer to Figure 1 A wafer clamping ring, wherein the cross-section of the wafer clamping ring along the radial direction is an annular shape formed by an inner ring 101 and an outer ring 102, the wafer clamping ring comprising:

[0024] The back surface 100a has a first step, which is provided along the edge of the inner ring 101 and extends circumferentially to close and form an annular step structure. The position of the first step is suitable to correspond to the edge position of the wafer to fix the wafer. The maximum cross-sectional diameter D of the inner ring 101 is 143.7 mm.

[0025] The minimum cross-sectional diameter d of the inner ring 101 is 137.5 mm.

[0026] Currently, the wafer retainer rings used in the silicon nitride dry etching process cover a large area of ​​the wafer edge. The die portion covered by the wafer retainer ring cannot be etched or completely etched, resulting in a decrease in the yield of semiconductor devices.

[0027] To solve the aforementioned technical problem, this utility model provides a wafer retaining ring for dry etching. The wafer retaining ring for dry etching has a radial cross-section that is annular, formed by an inner ring and an outer ring. The wafer retaining ring for dry etching includes a back surface, which has a first step. The first step is disposed along the edge of the inner ring and extends circumferentially to close and form an annular step structure. The position of the first step is suitable to correspond to the edge of the wafer to fix the wafer. The maximum cross-sectional diameter D of the inner ring is in the range of 143.7 mm < D < 145.7 mm.

[0028] In the wafer retaining ring for dry etching of this utility model, the first step is disposed along the edge of the inner ring, and the first step extends circumferentially to close and form an annular step structure. The position of the first step is suitable to correspond to the edge position of the wafer to fix the wafer. The maximum cross-sectional diameter D of the inner ring is in the range of 143.7mm < D < 145.7mm. The larger maximum cross-sectional diameter of the inner ring of the wafer retaining ring results in a smaller area of ​​the wafer edge covered by the wafer retaining ring, reducing the area of ​​the wafer edge that cannot be etched, reducing the probability of the wafer edge not being etched due to excessive coverage of the wafer edge by the wafer retaining ring, and improving the product yield.

[0029] To make the above-mentioned objectives, features and beneficial effects of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0030] Dry etching processes are typically performed within a vacuum reaction chamber. When helium gas is introduced between the mechanical electrodes and the wafer (i.e., back helium), a back pressure is created between the wafer and the mechanical electrodes. Without a wafer clamping ring to hold the wafer in place, this back pressure can easily push the wafer upwards or even blow it away. This can cause the wafer's position to change during etching, affecting the etching accuracy and uniformity, and may even cause the wafer to fall off, resulting in equipment damage and wafer scrap.

[0031] The wafer retaining ring used in dry etching is used to hold the edge of the wafer in the dry etching process.

[0032] The wafer clamping ring used for dry etching has a radial cross-section that is an annular shape formed by the inner ring 201 and the outer ring 202.

[0033] Please refer to the reference. Figure 2 and Figure 3 The wafer retaining ring for dry etching includes: a back surface 200a, the back surface 200a having a first step 203, the first step 203 being disposed along the edge of the inner ring 201, and the first step 203 extending circumferentially to close and form an annular step structure, the position of the first step 203 being suitable to correspond to the edge position of the wafer to fix the wafer, and the maximum cross-sectional diameter D of the inner ring 201 being in the range of 143.7mm < D < 145.7mm.

[0034] Specifically, in some embodiments of this utility model, the back side 200a is the side facing the wafer during the dry etching process.

[0035] Specifically, in the embodiments of this utility model, the wafer clamping ring used for dry etching is suitable for 6-inch wafers.

[0036] The position of the first step 203 is suitable to correspond to the edge position of the wafer, that is, the first step 203 is suitable to contact the edge position of the wafer.

[0037] The first step 203 is disposed along the edge of the inner ring 201, and the first step 203 extends circumferentially to close and form an annular step structure. The first step 203 is adapted to correspond to the edge position of the wafer to fix the wafer and prevent the wafer position from changing when helium gas is introduced between the mechanical electrode and the wafer (i.e., back helium).

[0038] The diameter is a line segment passing through a circular plane, with both endpoints of the diameter on the circle, and the diameter is the maximum distance between the two endpoints of the shape. Specifically, in this embodiment, the maximum cross-sectional diameter D of the inner ring 201 is the maximum distance between line segments with one end on the arc of the wafer retainer ring and the other end also on the arc of the wafer retainer ring. Specifically, in some embodiments of this utility model, the maximum cross-sectional diameter D of the inner ring 201 is in the range of 143.7mm < D < 145.7mm. The larger maximum cross-sectional diameter D of the inner ring 201 results in a smaller area of ​​the wafer retainer ring covering the edge of the wafer, reducing the area of ​​the wafer edge that cannot be etched, reducing the probability of the wafer edge not being etched due to excessive coverage of the wafer edge by the wafer retainer ring, and improving the product yield; furthermore, the maximum cross-sectional diameter D of the inner ring 201 will not be too large, avoiding the situation where the wafer retainer ring cannot hold the wafer, reducing the probability of wafer position changes, decreased etching accuracy, or even affecting product yield.

[0039] Please refer to Figure 2 and Figure 3The back surface 200a includes a first part I, a second part II, and a third part III distributed radially in sequence. The first part I, the second part II, and the third part III all extend and close in the circumferential direction. The second part II connects the first part I and the third part III. The surface of the first part I is recessed in the third part III. The first step 203 is formed between the first part I and the third part III.

[0040] The circumferential direction refers to the circumferential direction around the center of the wafer clamping ring.

[0041] The first part I, the second part II, and the third part III are integrally formed.

[0042] The surface of the first portion I is recessed into the third portion III to form the first step 203, the first step 203 and the first portion I being adapted to contact the edge of the wafer.

[0043] Please refer to Figure 3 The wafer retaining ring used for dry etching further includes a front side 200b, which has a second step 204, the position of which corresponds to the position of the first step 203.

[0044] Specifically, in some embodiments of this utility model, the front side 200b is the side away from the wafer during the dry etching process.

[0045] The position of the second step 204 corresponds to the position of the first step 203, that is, the projection of the first step 203 in a plane parallel to the wafer surface and the projection of the second step 204 in a plane parallel to the wafer surface at least partially overlap.

[0046] Specifically, in some embodiments of this utility model, the position where the second step 204 is located is thinned to remove part of the mass of the wafer retaining ring, thereby reducing the total mass of the wafer retaining ring used for dry etching and reducing the probability that the wafer retaining ring used for dry etching will crush the wafer.

[0047] Please continue to refer to this. Figure 2 In some embodiments of this utility model, the inner ring 201 of the wafer clamping ring used for dry etching is formed by an arc and a chord.

[0048] For small-sized wafers (e.g., 6 inches and below), flat edges are typically ground to serve as positioning edges. These edges provide a reference for wafer crystal orientation alignment and mechanical positioning, ensuring that the photolithographic pattern aligns with the crystal's cleavage direction and enabling precise wafer positioning during exposure, coating, and development processes. The inner ring 201 is formed by an arc and a chord, with the chord positioned to correspond to the positioning edge of the wafer.

[0049] The minimum cross-sectional diameter d of the inner ring 201 is in the range of 137.5 mm < d < 139.5 mm.

[0050] The diameter is a line segment passing through a planar circle, with both endpoints of the diameter on the circle, and the diameter is the maximum distance between the two endpoints of the shape. Specifically, in this embodiment, the minimum cross-sectional diameter d of the inner ring 201 is the maximum distance between the line segments with one end on the chord of the wafer retainer ring and the other end on the arc of the wafer retainer ring. Specifically, in some embodiments of this utility model, the minimum cross-sectional diameter d of the inner ring 201 is in the range of 137.5mm < d < 139.5mm. The larger minimum cross-sectional diameter d of the inner ring 201 results in a smaller area of ​​the wafer retainer ring covering the edge of the wafer, reducing the area of ​​the wafer edge that cannot be etched, lowering the probability of the wafer edge not being etched due to excessive coverage of the wafer edge by the wafer retainer ring, and improving product yield; furthermore, the minimum cross-sectional diameter d of the inner ring 201 is not too large, avoiding the situation where the wafer retainer ring cannot hold the wafer, reducing the probability of wafer position changes, decreased etching accuracy, or even affecting product yield.

[0051] Please continue to refer to this. Figure 2 The maximum ring width R of the wafer clamping ring used for dry etching is in the range of 90.1 mm < R < 91.1 mm.

[0052] The maximum ring width R of the wafer retaining ring used for dry etching is half the difference between the diameter E of the outer ring 202 of the wafer retaining ring and the minimum cross-sectional diameter d of the inner ring 201 of the wafer retaining ring, i.e., R = (Ed) / 2.

[0053] Please continue to refer to this. Figure 2 The minimum ring width r of the wafer clamping ring used for dry etching is in the range of 84.9 mm < r < 85.9 mm.

[0054] The minimum ring width r of the wafer retaining ring used for dry etching is half the difference between the diameter E of the outer ring 202 of the wafer retaining ring and the maximum cross-sectional diameter D of the inner ring 201 of the wafer retaining ring, i.e., r = (ED) / 2.

[0055] In other embodiments, the inner ring may also be circular. When the inner ring is circular, the wafer retaining ring is suitable for wafers without flat edges. In this case, the cross-sectional diameter D of the inner ring is in the range of 143.7 mm < D < 145.7 mm; and the ring width r of the wafer retaining ring used for dry etching is in the range of 84.9 mm < r < 85.9 mm.

[0056] Specifically, in the embodiments of this utility model, the material of the wafer retaining ring is polytetrafluoroethylene (PTFE). Using PTFE as the wafer material has a coefficient of friction of only 0.04 and a surface with extremely strong non-stick properties. When in contact with the wafer edge, it can minimize friction and avoid scratching the photolithographic patterns or thin film layers on the wafer surface.

[0057] Accordingly, embodiments of the present invention also provide a dry etching apparatus, comprising: a reaction chamber; a wafer clamping ring for dry etching as described in embodiments of the present invention, wherein the wafer clamping ring for dry etching is located within the reaction chamber, and the back surface 200a of the wafer clamping ring for dry etching faces the first surface of the wafer; and an air intake mechanism configured to introduce gas into the reaction chamber, wherein the air outlet of the air intake mechanism faces the second surface of the wafer.

[0058] The dry etching equipment includes a reaction chamber.

[0059] The reaction chamber is suitable for dry etching processes.

[0060] The dry etching equipment is a silicon nitride dry etching equipment.

[0061] Specifically, in some embodiments of this invention, the reaction chamber is suitable for performing a silicon nitride dry etching process.

[0062] The dry etching equipment includes a wafer retainer ring for dry etching as described in the present invention, wherein the back side 200a of the wafer retainer ring faces the first side of the wafer to hold the wafer in place during the dry etching process and prevent the wafer from changing position.

[0063] The dry etching apparatus includes an air intake mechanism configured to introduce gas into a reaction chamber, the air intake mechanism having an outlet facing the second side of the wafer.

[0064] Specifically, in some embodiments of this invention, the air intake mechanism is configured to introduce helium gas into the reaction chamber.

[0065] In summary, the first step is disposed along the edge of the inner ring, and extends circumferentially to form a ring-shaped step structure. The position of the first step is suitable to correspond to the edge of the wafer to fix the wafer. The maximum cross-sectional diameter D of the inner ring is in the range of 143.7 mm < D < 145.7 mm. The larger maximum cross-sectional diameter of the inner ring of the wafer retaining ring results in a smaller area of ​​the wafer edge covered by the wafer retaining ring, reducing the area of ​​the wafer edge that cannot be etched, and lowering the probability of the wafer edge not being etched due to excessive coverage of the wafer edge by the wafer retaining ring, thus improving product yield. Furthermore, the maximum cross-sectional diameter D of the inner ring is not too large, avoiding the situation where the wafer retaining ring cannot hold the wafer, reducing the probability of wafer position changes, decreased etching accuracy, or even affecting product yield.

[0066] Although 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 present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A wafer retaining ring for dry etching, wherein the wafer retaining ring for dry etching has a radial cross-section that is annular, formed by an inner ring and an outer ring, characterized in that... The wafer retaining ring used for dry etching includes: The back side has a first step, which is provided along the edge of the inner ring and extends circumferentially to close and form an annular step structure. The position of the first step is suitable to correspond to the edge position of the wafer to fix the wafer. The maximum cross-sectional diameter D of the inner ring is in the range of 143.7 mm < D < 145.7 mm.

2. The wafer retaining ring for dry etching as described in claim 1, characterized in that, The back side includes a first part, a second part, and a third part distributed radially in sequence. The first part, the second part, and the third part all extend and close in the circumferential direction. The second part connects the first part and the third part. The surface of the first part is recessed into the third part. A first step is formed between the first part and the third part.

3. The wafer retaining ring for dry etching as described in claim 1, characterized in that, Also includes: The front side has a second step, the position of which corresponds to the position of the first step.

4. The wafer retaining ring for dry etching as described in claim 1, characterized in that, The inner ring of the wafer clamping ring used for dry etching is formed by an arc and a chord.

5. The wafer retaining ring for dry etching as described in claim 1, characterized in that, The inner circle is circular.

6. The wafer retaining ring for dry etching as described in claim 4, characterized in that, The minimum cross-sectional diameter d of the inner ring is in the range of 137.5 mm < d < 139.5 mm.

7. The wafer retaining ring for dry etching as described in claim 4, characterized in that, The maximum ring width R of the wafer clamping ring used for dry etching is in the range of 90.1 mm < R < 91.1 mm.

8. The wafer retaining ring for dry etching as described in claim 4, characterized in that, The minimum ring width r of the wafer clamping ring used for dry etching is in the range of 84.9 mm < r < 85.9 mm.

9. A dry etching apparatus, characterized in that, include: reaction chamber; The wafer retaining ring for dry etching as described in any one of claims 1 to 8, wherein the wafer retaining ring for dry etching is located within the reaction chamber, and the back side of the wafer retaining ring for dry etching faces the first side of the wafer; An air intake mechanism is configured to introduce gas into a reaction chamber, with the air outlet of the air intake mechanism facing the second side of the wafer.

10. The dry etching apparatus as described in claim 9, characterized in that, The dry etching equipment is a silicon nitride dry etching equipment.

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