Etching device and etching method for improving etching uniformity

Abstract

According to the etching device and the etching method for improving the etching uniformity provided by the invention, the top surface of the focusing ring is arranged to be lower than the top surface of the wafer borne on the wafer bearing table, so that the lower side of the inclined surface of the wafer can be exposed, deep ion penetration is realized, the ion flow speed of the edge part of the wafer can be increased, and the etching rate of the edge part of the wafer can be increased; the plasma distribution uniformity is improved, and the etching uniformity is improved. Furthermore, the shape of the focusing ring step is optimized, so that the focusing ring step has an arc corner, the rebounding effect of the plasma can be further improved, and the edge of the wafer can be effectively etched.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and relates to an etching device and an etching method for improving etching uniformity. Background Art

[0002] In the semiconductor field, the main function of the focus ring of the etching reaction chamber is to provide balanced plasma for the wafer etching process. In addition to fixing the wafer, the focus ring also has functions such as maintaining the density of the plasma. Among them, the focus ring plays a very important role in adjusting the sheath profile of the wafer edge and maintaining the uniformity of the plasma. The trajectory of the incident ion will be controlled by the sheath, and the sheath is determined by the coupling of the plasma and the focus ring.

[0003] As the etching process continues, during a maintenance cycle of the etching equipment, the focus ring is gradually consumed, and the plasma sheath and ion movement direction at the edge of the wafer will be distorted and deflected to a certain extent, resulting in uneven etching. Therefore, in order to obtain good device performance, how to control the etching uniformity of the wafer edge in large-scale mass production has become an urgent problem to be solved in this field.

[0004] Therefore, it is necessary to provide an etching device and an etching method for improving etching uniformity. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an etching device and an etching method for improving etching uniformity, so as to solve the problem of wafer edge etching uniformity in the prior art.

[0006] In order to achieve the above-mentioned object and other related objects, the present invention provides an etching device for improving etching uniformity, the etching device comprising:

[0007] A wafer carrying platform, used to carry a wafer, wherein the edge of the wafer extends out of the wafer carrying platform;

[0008] A focusing ring, wherein the focusing ring is located at the periphery of the wafer supporting platform, and a focusing ring step is provided on a side of the focusing ring adjacent to the wafer supporting platform, and the wafer located on the wafer supporting platform extends into the focusing ring step and a gap is left between the focusing ring step and the top surface of the focusing ring is lower than the top surface of the wafer carried on the wafer supporting platform.

[0009] Optionally, a height difference between a top surface of the focus ring and a top surface of the wafer carried on the wafer carrying table ranges from 2.5 mm to 6.0 mm.

[0010] Optionally, the focusing ring step includes a horizontal wall, a vertical wall, and a rounded corner connecting the horizontal wall and the vertical wall.

[0011] Optionally, the focus ring step includes a horizontal wall and an inclined wall away from the wafer supporting platform, and an angle formed by connecting the horizontal wall and the inclined wall is an obtuse angle.

[0012] Optionally, the focus ring step includes a horizontal wall, an inclined wall away from the wafer supporting platform, and a rounded corner connecting the horizontal wall and the inclined wall.

[0013] Optionally, the focusing ring includes a silicon focusing ring or a polysilicon focusing ring; and the wafer supporting platform includes an electrostatic chuck.

[0014] The present invention also provides an etching method for improving etching uniformity, comprising the following steps:

[0015] An etching device is provided, the etching device comprising a wafer carrier and a focusing ring, the focusing ring is located at the periphery of the wafer carrier, and a focusing ring step is provided on a side of the focusing ring adjacent to the wafer carrier;

[0016] Providing a wafer to be etched, and placing the wafer on the wafer carrier, wherein the edge of the wafer extends out of the wafer carrier, and extends into the focus ring step with a gap between the focus ring step, and the top surface of the focus ring is lower than the top surface of the wafer;

[0017] The wafer is etched.

[0018] Optionally, the height difference between the top surface of the focus ring and the top surface of the wafer ranges from 2.5 mm to 6.0 mm.

[0019] Optionally, the focusing ring step includes a horizontal wall, a vertical wall, and a rounded corner connecting the horizontal wall and the vertical wall.

[0020] Optionally, the focusing ring step includes a horizontal wall and an inclined wall away from the wafer supporting platform, and the angle formed by the connection between the horizontal wall and the inclined wall is an obtuse angle; or the focusing ring step includes a horizontal wall, an inclined wall away from the wafer supporting platform, and a rounded corner connecting the horizontal wall and the inclined wall.

[0021] As described above, the etching device and etching method for improving etching uniformity of the present invention can expose the lower side of the wafer bevel by setting the top surface of the focus ring lower than the top surface of the wafer carried on the wafer carrier, achieve deep ion penetration, increase the ion flow speed at the edge of the wafer, increase the etching rate at the edge of the wafer, improve the uniformity of plasma distribution, and improve etching uniformity. Furthermore, by optimizing the morphology of the focus ring step so that the focus ring step has a rounded corner, the plasma rebound effect can be further improved to effectively etch the edge of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is a structural schematic diagram of an etching device for improving etching uniformity in an embodiment of the present invention.

[0023] Figure 2 Another schematic diagram of the structure of an etching device for improving etching uniformity in an embodiment of the present invention is shown.

[0024] Figure 3 Shown is another structural schematic diagram of an etching device for improving etching uniformity in an embodiment of the present invention.

[0025] Figure 4 Shown is another structural schematic diagram of an etching device for improving etching uniformity in an embodiment of the present invention.

[0026] Figure 5 Shown is a process flow chart of an etching method for improving etching uniformity in an embodiment of the present invention.

[0027] Figure 6 Shown is a schematic diagram of plasma density distribution in an embodiment of the present invention.

[0028] Figure 7 Shown is a schematic diagram of the ion movement direction of the plasma in an embodiment of the present invention.

[0029] Description of Reference Numerals

[0030] 100 Wafer carrier

[0031] 200 Focus ring

[0032] 300 Wafer

[0033] 400 Plasma DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0036] For ease of description, spatial relational terms such as “under”, “below”, “below”, “below”, “over”, etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other orientations of the device in use or operation in addition to the orientation depicted in the drawings, and may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, so that the first and second features may not be in direct contact. In addition, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or one or more intervening layers may also be present.

[0037] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0038] This embodiment provides an etching device for improving etching uniformity, the etching device comprising:

[0039] A wafer carrying platform, used to carry a wafer, wherein the edge of the wafer extends out of the wafer carrying platform;

[0040] A focusing ring, wherein the focusing ring is located at the periphery of the wafer supporting platform, and a focusing ring step is provided on a side of the focusing ring adjacent to the wafer supporting platform, and the wafer located on the wafer supporting platform extends into the focusing ring step and a gap is left between the focusing ring step and the top surface of the focusing ring is lower than the top surface of the wafer carried on the wafer supporting platform.

[0041] Specifically, Figure 1The schematic diagram of the structure of an etching device in this embodiment is shown, wherein it should be noted that Figure 1 The structure is a cross-sectional view, and the focus ring 200 shown in the figure includes two parts, left and right parts. In fact, the focus ring 200 is an integrated structure, and its specific shape is a circular ring.

[0042] The wafer carrier 100 is used to carry the wafer 300 to be processed, wherein the wafer carrier 100 may include an electrostatic chuck (ESC) but is not limited thereto. The focus ring 200 may include, for example, a silicon focus ring or a polysilicon focus ring, and the specific selection may be made according to needs.

[0043] Regarding the size of the wafer carrier 100 and the focusing ring 200, it is preferably selected according to the size of the wafer 300 to be processed. For example, the size of the wafer 300 may include 6 inches, 8 inches, 12 inches, etc., and the corresponding size of the wafer carrier 100 and the focusing ring 200 can be changed following the size of the wafer 300 to ensure a good etching effect and improve product quality.

[0044] Specifically, during the working process, the plasma 400 is required to be used to dry etch the wafer 300 to be processed, and the main function of the focusing ring 200 is to make the distribution direction of the plasma 400 more balanced. Among them, the edge of the wafer 300 protrudes out of the wafer carrier 100, and the wafer carrier 100 can be effectively covered by the wafer 300, so that the wafer carrier 100 can be protected by the wafer 300 to prevent the wafer carrier 100 from being exposed to the plasma 400.

[0045] In the etching device of this embodiment, the focus ring 200 is set so that its top surface is lower than the top surface of the wafer 300 located on the wafer carrier 100, so that the lower side of the inclined surface of the wafer 300 can be exposed, and deep ion penetration can be achieved, so that when performing the etching process, Figure 6 As shown, the edge of the wafer 300 has a relatively uniform ion density, and Figure 7 , there is a better ion running direction at the edge of the wafer 300, so that the etching device of this embodiment can increase the ion flow speed at the edge of the wafer 300, increase the etching rate of the edge of the wafer 300, and improve the uniformity of plasma distribution, thereby improving the etching uniformity, which can effectively solve the problem of uneven etching caused by the gradual consumption of the focusing ring in the etching process, such as the focusing ring and the wafer are located on the same horizontal plane, and the plasma sheath and the direction of ion movement at the edge of the wafer are twisted and deflected to a certain extent.

[0046] The height difference Δh between the top surface of the focus ring 200 and the top surface of the wafer 300 carried on the wafer carrying table 100 may range from 2.5 mm to 6.0 mm, such as 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 5.0 mm, 6.0 mm, etc. The specific selection of the height difference Δh is not overly limited here.

[0047] like Figure 1 In this embodiment, the focus ring step includes a horizontal wall and a vertical wall, but is not limited thereto. Figure 2 In another embodiment, the focusing ring step may include a horizontal wall and an inclined wall away from the wafer carrier 100, and the angle θ formed by the horizontal wall and the inclined wall is an obtuse angle, so that the electric field component orthogonal to the magnetic field in the area above the edge of the wafer 300 can be further enhanced by the inclined wall, and the amount of the plasma 400 at the edge of the wafer 300 can be increased, so that the wafer 300 can have a more uniform etching speed.

[0048] As a further embodiment of this embodiment, Figure 3 The focusing ring step may further include a horizontal wall, a vertical wall and a rounded corner connecting the horizontal wall and the vertical wall, so that the setting of the rounded corner can further improve the rebound effect of the plasma 400, so as to effectively etch the edge of the wafer 300, increase the uniformity of etching the edge of the wafer 300, and avoid uneven etching in some areas.

[0049] In yet another embodiment, Figure 4 The focus ring step may also be configured to include a horizontal wall, an inclined wall away from the wafer supporting platform, and a rounded corner connecting the horizontal wall and the inclined wall, so that the focus ring 200 has the characteristics of the inclined wall and the rounded corner at the same time, so as to increase the amount of the plasma 400 at the edge of the wafer 300, so that the wafer 300 has a more uniform etching speed, and can further improve the rebound effect of the plasma 400, so as to effectively etch the edge of the wafer 300, increase the uniformity of etching the edge of the wafer 300, and avoid uneven etching in some areas.

[0050] See also Figure 5 This embodiment also provides an etching method for improving etching uniformity, comprising the following steps:

[0051] S1: providing an etching device, wherein the etching device comprises a wafer carrying platform and a focusing ring, wherein the focusing ring is located at the periphery of the wafer carrying platform, and a focusing ring step is provided on a side of the focusing ring adjacent to the wafer carrying platform;

[0052] S2: providing a wafer to be etched, and placing the wafer on the wafer carrier, wherein the edge of the wafer extends out of the wafer carrier, and extends into the focus ring step with a gap between the focus ring step, and the top surface of the focus ring is lower than the top surface of the wafer;

[0053] S3: etching the wafer.

[0054] As an example, the height difference between the top surface of the focus ring and the top surface of the wafer carried on the wafer carrying table may range from 2.5 mm to 6.0 mm, such as 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 5.0 mm, 6.0 mm, etc. The specific selection of the height difference is not overly limited here.

[0055] In this embodiment, the focus ring is set so that its top surface is lower than the top surface of the wafer on the wafer carrier, so that the lower side of the inclined surface of the wafer can be exposed, and deep ion penetration can be achieved, so that when performing the etching process, Figure 6 As shown, there is a relatively uniform ion density at the edge of the wafer, and Figure 7 , there is a better ion running direction at the edge of the wafer, so that the ion flow speed at the edge of the wafer can be increased in the etching process, the etching rate at the edge of the wafer can be increased, the uniformity of plasma distribution can be improved, and thus the etching uniformity can be improved. It can effectively solve the problem of uneven etching caused by the gradual consumption of the focusing ring in the etching process, such as the focusing ring and the wafer are located in the same horizontal plane, and the plasma sheath and the direction of ion movement at the edge of the wafer are twisted and deflected to a certain extent.

[0056] As an example, the focusing ring step may include a horizontal wall, a vertical wall, and a rounded corner connecting the horizontal wall and the vertical wall, so that the setting of the rounded corner can further improve the rebound effect of the plasma, so as to effectively etch the edge of the wafer, increase the uniformity of etching the edge of the wafer, and avoid uneven etching in some areas.

[0057] As an example, the focusing ring step may also include a horizontal wall and an inclined wall away from the wafer supporting platform, and the angle formed by the connection between the horizontal wall and the inclined wall is an obtuse angle, so that the electric field component orthogonal to the magnetic field in the area above the edge of the wafer can be further enhanced through the inclined wall, and the amount of the plasma in the edge portion of the wafer is increased, so that the wafer can have a more uniform etching speed; or the focusing ring step includes a horizontal wall, an inclined wall away from the wafer supporting platform and a rounded corner connecting the horizontal wall and the inclined wall, so that the focusing ring has the characteristics of the inclined wall and the rounded corner at the same time, so as to increase the amount of the plasma in the edge portion of the wafer, so that the wafer has a more uniform etching speed, and can further improve the rebound effect of the plasma, so as to effectively etch the edge of the wafer, increase the uniformity of etching the edge portion of the wafer, and avoid uneven etching in some areas.

[0058] In summary, the etching device and etching method for improving etching uniformity of the present invention can expose the lower side of the wafer bevel by setting the top surface of the focus ring lower than the top surface of the wafer carried on the wafer carrier, achieve deep ion penetration, increase the ion flow speed at the edge of the wafer, increase the etching rate at the edge of the wafer, improve the uniformity of plasma distribution, and improve etching uniformity. Furthermore, by optimizing the morphology of the focus ring step so that the focus ring step has a rounded corner, the plasma rebound effect can be further improved to effectively etch the edge of the wafer.

[0059] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An etching device for improving etching uniformity, characterized in that: The etching device comprises: A wafer carrying platform, used to carry a wafer, wherein the edge of the wafer extends out of the wafer carrying platform; A focusing ring, wherein the focusing ring is located at the periphery of the wafer supporting platform, and a focusing ring step is provided on a side of the focusing ring adjacent to the wafer supporting platform, and the wafer located on the wafer supporting platform extends into the focusing ring step and a gap is left between the focusing ring step and the top surface of the focusing ring is lower than the top surface of the wafer carried on the wafer supporting platform.

2. The etching device according to claim 1, characterized in that: The height difference between the top surface of the focus ring and the top surface of the wafer carried on the wafer carrying table ranges from 2.5 mm to 6.0 mm.

3. The etching device according to claim 1, characterized in that: The focus ring step includes a horizontal wall, a vertical wall, and a rounded corner connecting the horizontal wall and the vertical wall.

4. The etching device according to claim 1, characterized in that: The focus ring step includes a horizontal wall and an inclined wall away from the wafer carrying platform, and the angle formed by connecting the horizontal wall and the inclined wall is an obtuse angle.

5. The etching device according to claim 1, characterized in that: The focus ring step includes a horizontal wall, an inclined wall away from the wafer carrying platform, and a rounded corner connecting the horizontal wall and the inclined wall.

6. The etching device according to claim 1, characterized in that: The focusing ring comprises a silicon focusing ring or a polysilicon focusing ring; The wafer carrying platform includes an electrostatic chuck.

7. An etching method for improving etching uniformity, characterized in that: The following steps are involved: An etching device is provided, the etching device comprising a wafer carrier and a focusing ring, the focusing ring is located at the periphery of the wafer carrier, and a focusing ring step is provided on a side of the focusing ring adjacent to the wafer carrier; Providing a wafer to be etched, and placing the wafer on the wafer carrier, wherein the edge of the wafer extends out of the wafer carrier, and extends into the focus ring step with a gap between the focus ring step, and the top surface of the focus ring is lower than the top surface of the wafer; The wafer is etched.

8. The etching method according to claim 7, characterized in that: The height difference between the top surface of the focus ring and the top surface of the wafer ranges from 2.5 mm to 6.0 mm.

9. The etching method according to claim 7, characterized in that: The focus ring step includes a horizontal wall, a vertical wall, and a rounded corner connecting the horizontal wall and the vertical wall.

10. The etching method according to claim 7, characterized in that: The focusing ring step includes a horizontal wall and an inclined wall away from the wafer supporting platform, and the angle formed by the connection between the horizontal wall and the inclined wall is an obtuse angle; or the focusing ring step includes a horizontal wall, an inclined wall away from the wafer supporting platform, and a rounded corner connecting the horizontal wall and the inclined wall.

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