KR20040016693A - Wafer supporting device - Google Patents

Abstract

PURPOSE: A wafer support unit is provided to minimize consumption of parts and a cover ring functioning as an insulator by making a portion directly exposed to radio frequency formed of a focus ring composed of only a silicon material. CONSTITUTION: A chuck(110) supports and fixes a wafer. The focus ring(115) forms an extended area in the periphery of the chuck, disposed on the side surface of the chuck. The cover ring(120) surrounds and intercepts the chuck, disposed to contact the bottom surface of the focus ring wherein the upper portion of the cover ring is covered with the focus ring.

Description

Wafer Support {WAFER SUPPORTING DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer support mounted on a dry etching apparatus among apparatuses used in the manufacturing process of a semiconductor device. More particularly, the focus ring and the cover ring can be efficiently disposed to extend the life of a component and to provide a wafer edge. It relates to a wafer support of a dry etching apparatus that can increase the critical dimension (CD) of the edge portion.

Etching processes performed to form a fine pattern in the manufacturing process of a semiconductor device are largely wet etching (dry etching) and dry etching (dry etching). Wet etching has the advantage that the process is relatively simple and inexpensive, while undercutting may occur. Therefore, in recent years, dry etching has been widely used to etch highly integrated semiconductor devices that can solve these disadvantages.

Dry etching equipment is used to form fine patterns on wafers using plasma. Currently, dry etching equipment such as TEL SCCM TERIUS, which is used for dry etching, is used for etching by placing a wafer on the lower electrode inside the chamber and forming a plasma in the chamber. Perform the process.

A dry etching apparatus uses a chuck as a component for supporting a wafer when a dry etching process is performed, and generally, an electrostatic chuck (ESC) using an electrostatic force is used.

The electrostatic chuck is arranged with various components according to the process needs. For example, a focus ring made of silicon (Si) is disposed outside the electrostatic chuck so as to concentrate the plasma on the wafer or to enlarge the effective area of the lower electrode. In addition, a cover ring made of an insulator is disposed along the outer side of the focusing ring. According to a conventional wafer support, the cover ring is generally composed of quartz.

1 is a partial cross-sectional view for explaining a conventional wafer support.

Referring to FIG. 1, a conventional wafer support is disposed outwardly along an outer circumference of the electrostatic chuck 10, the focus ring 15 arranged around the electrostatic chuck 10 to expand the area of the electrode, and the focus ring 15. Quartz cover ring 20 to be included.

It has a cylindrical upper portion of the electrostatic chuck 10 and is mainly composed of ceramic. The focus ring 15 is disposed adjacent to the upper surface of the electrostatic chuck 10 corresponding to the shape of the electrostatic chuck 10. The focus ring 15 forms a first upper surface located at the same height as the upper surface of the electrostatic chuck 10 on the inside, and a second upper surface higher than the first upper surface on the outer side of the first upper surface. As shown in the drawing, the wafer is positioned on the electrostatic chuck 10 and the first upper surface in the process of performing dry etching.

The cover ring 20 is disposed in contact with the outside of the focus ring 15, and the upper surface of the cover ring 20 is disposed at the same height as the upper surface of the focus ring 15. The outside of the cover ring 20 is cylindrical and accommodates the side of the electrostatic chuck 10 and is made of quartz to function as an insulator.

As shown, after the wafer is placed on the wafer support of the dry etching apparatus, about 60 MHz from the top and about 2 MHz from the bottom from the RF generator (not shown) disposed above and below the dry etching apparatus. As the high frequency (RF) is generated, a dry etching process using plasma is performed. At this time, a part of the high frequency RF passes along the contact surface of the focus ring 15 and the cover ring 20 formed on the upper surface of the wafer support to penetrate into the lower electrode.

As the etching process continues, plasma attack by radio frequency (RF) is performed between the contact surface gaps between the focus ring 15 and the cover ring 20, so that etching occurs around the contact surface gaps. At this time, since the etching proceeds intensively on the contact surface, the amount of etching around the contact surface is larger than the amount of etching around the contact surface. As a result, the life of the lower electrode component is shortened, and the reduction of the critical dimension (CD) at the wafer edge portion causes process failure.

In addition, the first upper surface and the second upper surface are distinguished by the step of the focus ring 15, and the two upper surfaces are connected by the step surface perpendicular to the surface. As already mentioned, the stepped surface is formed around the wafer so that the plasma introduced on the wafer can float for a longer time on the upper side of the wafer so that the plasma is concentrated on the wafer. However, as the dry etching process proceeds, plasma and reaction by-products may be deposited near the wafer, that is, near the lower portion of the stepped surface, and the deposited by-products may rise to the wafer edge and fall into flakes. In this way, a large amount of reaction byproduct particles may be generated due to by-products falling to the edge of the wafer, resulting in a decrease in yield.

These reaction by-products mainly include carbon, fluorine or oxygen, and are generated from an etching medium or an etching target used in a dry etching process.

Accordingly, by improving the components and arrangement of the wafer support, the necessity of extending the life time of each component and reducing the process defect of the critical dimension (CD) has been discussed.

It is therefore an object of the present invention to provide a wafer support that can extend the life of a part by efficiently placing the focus ring and cover ring to extend the life of the part.

1 is a partial cross-sectional view for explaining a conventional wafer support.

2 is a partially enlarged cross-sectional view for comparing the amount of dry etching according to a material.

3 is a cross-sectional view of the wafer support according to the first embodiment of the present invention.

4 is a cross-sectional view of the wafer support according to the second embodiment of the present invention.

5 is a cross-sectional view of the wafer support according to the third embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100, 200, 300: wafer support 110, 210, 310: electrostatic chuck

115, 215, 315: focus ring 120, 220, 320: cover ring

According to a preferred embodiment of the present invention to achieve the above object of the present invention, a wafer support disposed below the plasma forming region of the dry etching apparatus is disposed on the side of the chuck and the chuck to support and fix the wafer, around the chuck. A focus ring forming an enlarged area therein, and a cover ring disposed to contact the bottom surface of the focus ring, the top surface being covered by the focus ring and blocking around the side of the chuck.

An electrostatic chuck (ESC) is commonly used as a chuck, and the focus ring includes a flat focus ring without stages and a two-stage focus ring forming stages along an inner surface. The focus ring is made of the same material as the wafer, that is, silicon or is provided in a surface-covered form of silicon.

The cover ring is disposed on the bottom surface of the focus ring along the outer circumference thereof, so that the focus ring covers the top surface of the cover ring. At this time, the contact surfaces of the focus ring and the cover ring are formed exposing the gap on the side of the wafer support. At this time, since the gap of the contact surface is directed to the side, it is possible to significantly prevent the entry of high frequency (RF) passing through the contact surface.

As shown in FIG. 1, it is very difficult for high frequency RF to penetrate through the gap formed in the side surface as compared with the case where the gap between the contact surface of the focus ring and the cover ring is formed on the upper surface adjacent to the wafer.

Preferably, the cover ring has a cylindrical shape with an outer diameter equal to the outer diameter of the focus ring, but the present invention provides a cover that makes the top surface of the cover ring wider than the top surface of the focus ring and at the same time faces the contact surface. It also includes the structure of the ring. That is, the top surface of the cover ring may form a step having a higher inner side than the outer side, and the focus ring may cover the high inner upper surface to form a wafer support. The focus ring is generally composed of expensive silicon, and the manufacturing cost of the silicon increases significantly as the size of the silicon increases, so that the wafer support can be formed with the above-described efficient structure.

When the focus ring is formed into a flat plate, reaction by-products generated by plasma or dry etching may be prevented from being deposited around the wafer, thereby reducing process defects due to the critical dimension (CD).

Comparison of etching amount of silicon and quartz

FIG. 2 is a partially enlarged cross-sectional view illustrating the amount of dry etching according to a material, and compares the amount of etching of parts disposed around the wafer support of the dry etching apparatus.

The parts arranged around the focus ring and the cover ring, which are formed in a ring shape and made of silicon and quartz. In actuality, the etching amount of the focus ring made of silicon and the cover ring made of quartz were compared while etching the wafer.

Referring to FIG. 2, an electrostatic chuck region is formed on an upper surface of the wafer support, and a focus ring 30 made of silicon (Si) is disposed around the electrostatic chuck, and a cover ring made of quartz (Quartz) is disposed on the outside thereof. 35) were placed sequentially.

Like the actual dry etching process, the plasma formation region is disposed on the lower electrode. A high frequency of 60 MHz was scanned into the wafer support at the top and a high frequency of 2 MHz was scanned from the bottom.

The dry etching process was performed for about 120 hours, and the etching amount of each part of the wafer support, that is, the focus ring 30 and the cover ring 35, was measured for each part after the dry etching process. The etching amount for each part of each part measured is shown in Table 1 below.

division ① ② ③ ④ ⑤ ⑥ Part Name Cover ring Focus ring material Quartz Silicon Etching amount 0.009mm 0.330mm 1.650mm 0.612mm 0.465 mm 0.133mm

Referring to Table 1, when comparing the areas ③ and ④ adjacent to the contact surfaces of the cover ring 35 and the focus ring 30, the cover ring 35 made of quartz was etched by 1.650 mm in the almost adjacent area. The focus ring 30 made of silicon was etched by 0.612 mm. The etching amount of silicon is about one third of the etching amount of quartz under the same conditions, and it can be seen that the etching amount of silicon is significantly smaller than the etching amount of quartz under the same conditions.

In addition, the most amount of the same material was etched adjacent to the contact surfaces of the cover ring 35 and the focus ring 30, and thus the amount of etching at the point ④ adjacent to the contact surface was larger than the amount of etching at the point ⑥ adjacent to the wafer. Therefore, in the dry etching process, the amount of etching of peripheral parts varies depending on the distance from the center of the electrostatic chuck, but if there is a contact surface facing upward, the etch amount of the peripheral parts increases relatively regardless of the distance from the electrostatic chuck. have. That is, it can be seen that the high frequency penetrates into the contact surface gap of both parts, so that the etching is relatively concentrated on the contact surface.

In addition, when comparing the points ①, ② and ③ of the cover ring 35 made of quartz, the etching amount decreased as the distance from the center. That is, in general, it can be seen that the etching amount of the peripheral component decreases as it is located far from the center.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or restricted by the embodiments.

Example 1

3 is a cross-sectional view of the wafer support according to the first embodiment of the present invention.

Referring to FIG. 3, the wafer support 100 according to the first embodiment is disposed on the upper outer periphery of the electrostatic chuck 110 in correspondence with the outer circumferential surface of the electrostatic chuck 110 and the electrostatic chuck 110, so that the wafer support 100 is provided. It includes a focus ring 115 to cover the top surface of the cover ring 120 is formed in contact with the bottom of the focus ring 115 to support the focus ring 115.

In the present embodiment, the focus ring 115 is made of silicon, and has a flat disk shape without forming a step on the upper surface. The inner hole of the focus ring 115 is formed corresponding to the outer circumferential shape of the electrostatic chuck 110 so that the inner surface of the focus ring 115 is disposed on the side surface of the electrostatic chuck 110 in contact with the electrostatic chuck 110.

The upper surfaces of the focus ring 115 and the electrostatic chuck 110 are located at the same height, and the focus ring 115 and the electrostatic chuck 110 form one horizontal plane. By forming an upper surface of the wafer support 100 on which the wafer WF is placed, a plasma and reaction by-products that may be deposited around the wafer WF may be easily removed.

According to the present embodiment, the cover ring 120 is made of quartz, and supports the bottom surface of the focus ring 115 as the upper surface, and accommodates the electrostatic chuck 110 therein to function as an insulator.

As shown, since the contact surfaces of the focus ring 115 and the cover ring 120 are formed on the side of the wafer support 100, a high frequency RF scanned up and down with respect to the wafer support 100 is transmitted through the contact surface. It cannot penetrate easily and as a result significantly reduces the etch concentration at the contact gap openings.

In this embodiment, although the silicon and quartz are used as the materials of the focus ring 115 and the cover ring 120, the present invention is not limited to this material, and those skilled in the art will be aware of other materials within the scope and spirit of the present invention. The focus ring and the cover ring can be applied.

In addition, the shape of the focus ring 115 and the cover ring 120 may be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims.

Example 2

4 is a cross-sectional view of the wafer support according to the second embodiment of the present invention.

Referring to FIG. 4, the wafer support 200 according to the second embodiment is disposed on the upper circumference of the electrostatic chuck 210 in correspondence to the outer surface of the electrostatic chuck 210 and the electrostatic chuck 210, so that the wafer support 200 is provided. It includes a two-stage focus ring 215 covering the upper surface of the cover ring and a cover ring 220 formed along the outer lower surface of the focus ring 215 to support the focus ring 215.

In this embodiment, the focus ring 215 is made of silicon, and has a two-stage structure that forms a step on the upper surface. The focus ring 215 forms a first upper surface 216 inward, and a second upper surface 217 higher than the first upper surface 216 to form a step. Stepped surfaces perpendicular to the upper surfaces 216 and 217 are formed between the first and third upper surfaces 216 and 217.

The first upper surface 216 of the focus ring 215 and the upper surface of the electrostatic chuck 210 are positioned at the same height to form one horizontal surface, and the wafer WF is placed on the horizontal surface. By the step surface of the focus ring 215, a disk-shaped empty space is formed therein, and the wafer WF is placed in the empty space.

The empty space formed by the focus ring 215 and the correction chuck 210 facilitates the mounting of the wafer WF and allows the plasma required for dry etching to stay around the wafer WF for a relatively long time.

Since the material of the focus ring 215 except the shape of the focus ring 215, the structure and the material of the cover ring 220 are substantially the same as the corresponding elements of the first embodiment, repeated descriptions of the corresponding matters are omitted. do.

In this embodiment, the material and shape of the focus ring 215 and the cover ring 220 does not fundamentally limit the present invention, and those skilled in the art can focus ring of different materials and shapes without departing from the spirit and scope of the present invention. And a cover ring can be applied.

Example 3

5 is a cross-sectional view of the wafer support according to the third embodiment of the present invention.

Referring to FIG. 5, the wafer support 300 according to the third embodiment is disposed on the upper outer periphery of the electrostatic chuck 310 in correspondence with the outer circumferential surface of the electrostatic chuck 310 and the electrostatic chuck 310, so that the wafer support 300 is provided. Focus ring 315 covering a portion of the upper surface of the upper surface of the first upper surface 321 is formed in contact with the bottom of the focus ring 315 and the second upper surface 322 lower than the first upper surface 321 to the outside Cover ring 320 is formed.

In the present embodiment, the focus ring 315 is made of silicon, and has a flat disk shape without forming a step on the upper surface. The inner hole of the focus ring 315 is formed corresponding to the outer circumferential shape of the electrostatic chuck 310 so that the inner surface of the focus ring 315 is disposed above the side of the electrostatic chuck 310 in contact with the electrostatic chuck 310.

In the cover ring 320, a stepped surface is formed between the first upper surface 321 and the second upper surface 322, and preferably, the stepped surface is perpendicular to the first upper surface 321 and the second upper surface 322. do. The focus ring 315 is placed on the first upper surface 321, and the stepped surface and the side surfaces of the focus ring 315 coincide to form one cylindrical surface.

By forming the top surface of the focus ring 315 and the electrostatic side 310 into one horizontal plane, plasma and reaction byproducts that may be deposited around the wafer WF placed thereon can be easily removed.

According to the present embodiment, the cover ring 320 is made of quartz, and the first upper surface 321 of the cover ring 320 supports the bottom of the focus ring 315 and simultaneously accommodates the electrostatic chuck 310 therein. Function as an insulator

As shown, since the contact surfaces of the focus ring 315 and the cover ring 320 are formed on the side of the wafer support 300, a high frequency RF scanned up and down with respect to the wafer support 300 is transmitted through the contact surface. It cannot penetrate easily and as a result significantly reduces the etch concentration at the contact gap openings.

In the present embodiment, the material and shape of the focus ring 315 and the cover ring 320 do not fundamentally limit the present invention, and those skilled in the art may focus ring of different materials and shapes without departing from the spirit and scope of the present invention. And a cover ring can be applied.

According to the present invention, by limiting the portion directly exposed to the high frequency to the focus ring made of silicon material, it is possible to minimize the consumption of the component, it is possible to minimize the consumption of the cover ring to function as an insulator.

In addition, it is possible to reduce the overall consumable parts cost by periodically using the focus ring, and to limit or reduce the abnormal state in the process and equipment caused by the parts (worn-out).

In addition, the area of the focus ring exposed from the lower electrode may be increased to increase the plasma area, and the defect of the critical dimension (CD) of the wafer edge may be minimized.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that it can be changed.

Claims (9)

In the wafer support mounted to the etching apparatus, A chuck for supporting and fixing the wafer; A focus ring disposed on an upper side of the chuck to form an enlarged area around the chuck; And And a cover ring disposed to contact a bottom surface of the focus ring, the top surface of which is covered by the focus ring and is closed around the side of the chuck. The wafer support of claim 1, wherein the chuck is an electrostatic chuck. The wafer support of claim 1, wherein the cover ring is cylindrical having an outer diameter equal to an outer diameter of the focus ring. The wafer support of claim 1, wherein the focus ring is flat. 5. The wafer support according to claim 4, wherein the upper surface of the focus ring and the upper surface of the electrostatic chuck are disposed at the same height to form one horizontal surface. The wafer support according to claim 1, wherein the focus ring has a first upper surface formed therein and a second upper surface formed higher than the first upper surface formed therein to form a seating portion for accommodating the wafer therein. The wafer support according to claim 1, wherein the focus ring is flat, and the cover ring forms a first upper surface on an inner side and a second upper surface lower than the first upper surface on an outer side thereof. The wafer of claim 7, wherein the cover ring forms a stepped surface perpendicular to the first and second upper surfaces, and the stepped surface forms a cylindrical surface coincident with a side surface of the focus ring. support fixture. The wafer support of claim 1, wherein the focus ring is made of silicon and the cover ring is made of quartz.