JP2001223204A - Electrode plate for plasma etching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode plate of a plasma etching device, where the electrode plate can be lessened in frequency of cleaning, elongated in service life, and enhanced enough in mechanical strength, restraining plasma from penetrating into the gas flow straightening holes board in it and reaction produces from adhering to the inner walls of the holes in an etching operation. SOLUTION: This electrode plate is used as the upper electrode of a plasma etching device and provided with gas flow straightening holes 2 board in it. When the diameter of the gas inlet-side opening of the gas flow straightening hole 2 is represented by d1, the diameter of the gas outlet-side opening is represented by d2, and a center distance between the adjacent holes 2 is represented by L, these elements d1, d2, and L are so set as to satisfy a formula, d2<d1<<=L/2. It is preferable that the diameter of the gas outlet-side opening of the hole is set at 0.1 to 1.5 mm, and the electrode plate is formed of silicon 0.001 to 50 Ω.cm in resistivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrode plate for a plasma etching apparatus, and more particularly to an electrode plate for a plasma etching apparatus suitably used for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art As one of semiconductor device manufacturing apparatuses, there is known a plasma etching apparatus for etching a semiconductor wafer by using active gas plasma under reduced pressure. FIG. 4 is a schematic view showing an example of such a plasma etching apparatus. The apparatus 20 includes a lower electrode plate 23 on which a silicon wafer 27 to be processed is placed in a reaction chamber 29, and an electrode plate for a plasma etching apparatus as an upper electrode at a position facing the lower electrode 23. 2
The upper electrode plate 21 is provided with a number of gas rectification holes 22.

At the time of etching, a high-frequency voltage is applied from a high-frequency power source 26 to an electrode plate 21 for a plasma apparatus and a lower electrode plate 23, and an etching gas is supplied to a gas supply system 24.
To the internal gas container 28. The etching gas is rectified by the gas rectifying holes 22 of the upper electrode plate 21, and is jetted toward the silicon wafer 27 to generate plasma between the upper electrode plate 21 and the silicon wafer 27, thereby performing a desired dry etching process. It is supposed to be. The surplus gas in the reaction chamber is discharged by a gas discharge system 25.

[0004] With the recent increase in the degree of integration and miniaturization of semiconductor devices, the performance required for electrode plates has become even more severe. In order to reduce the generation of particles and contamination, for example, conventional carbon and aluminum materials have been used. Instead of the electrode described above, an electrode plate made of silicon, which is the same material as the wafer, has been developed.

Since the plasma etching apparatus 20 performs an etching process by generating plasma between the wafer 27 and the upper electrode plate 21 as described above, in principle, not only the wafer but also the upper electrode plate 21 is gradually removed. Will be etched. Therefore, if an electrode plate is manufactured using silicon as described above, contamination does not occur even if the electrode plate is etched, so that the electrode plate itself does not adversely affect the device, thereby improving productivity and yield. Plays a big role.

However, even when the electrode plate is made of silicon, the reaction product adheres to the inner wall of the rectification hole and the surface on the gas introduction side due to the plasma flowing into the gas rectification hole, and the reaction product is charged up. Therefore, there is a problem that abnormal discharge occurs, so that frequent cleaning is required.

Japanese Patent Application Laid-Open No. Hei 10-270418 discloses that the gas rectifying hole of the gas head (upper electrode plate) has a maximum diameter at one opening end, and the inside or the other, so that this cleaning can be performed efficiently. A method is disclosed in which the shape is reduced at the open end. By adopting the rectifying hole having such a shape, when the cleaning product is injected into the rectifying hole from the opening end having the largest diameter when the reaction product adhered to the inside of the rectifying hole is wet-cleaned, it flows toward the smaller opening diameter. As the pressure increases and the flow rate increases, the reaction product can be efficiently removed.

[0008]

However, when cleaning is actually performed, the electrode plate needs to be attached to and detached from the apparatus in wet cleaning. Therefore, it is necessary to release the reaction chamber rather than to remove the reaction product. The loss required for fine adjustment of the device is greater. Therefore, not only efficiency,
It is important to reduce the number of cleaning operations as much as possible.

Japanese Patent Application Laid-Open No. Hei 10-270418 discloses that in dry cleaning in which plasma is cleaned while the upper electrode is mounted on the apparatus, if the opening end having the largest diameter is mounted facing the reaction chamber, radicals are incident. It is said that the corner becomes larger and the cleaning efficiency is improved. However, if the opening end having the largest diameter is attached to the reaction chamber side, the plasma easily enters the rectifying hole even in the actual process, and the adhesion of the reaction product increases. However, there is a problem that productivity cannot be improved. Further, if the opening end having the maximum diameter is excessively large, there is a problem that the mechanical strength of the electrode plate cannot be maintained.

In a conventional general electrode plate for a plasma etching apparatus having a rectifying hole of the same diameter, the diameter increases on the gas ejection side and becomes tapered as the electrode plate itself is consumed. There is a problem that the plasma easily enters, and the amount of the reaction product attached also increases. Therefore, the electrode plate having such rectifying holes of the same diameter also has a problem that the life is shortened as a result.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and suppresses the invasion of plasma into gas rectification holes during etching, prevents reaction products from adhering to the holes, and reduces the number of cleaning operations. It is another object of the present invention to provide an electrode plate for a plasma etching apparatus which can be used for a long time and has sufficient mechanical strength.

[0012]

Means for Solving the Problems The present inventors have studied to solve the above problems, and as a result, have obtained an electrode plate provided with a plurality of gas rectification holes used as an upper electrode of a plasma etching apparatus, When the hole diameter of the gas rectification hole is d1 on the gas introduction side, the hole diameter on the gas ejection side is d2, and the distance between the centers of adjacent gas rectification holes is L, d2 <d1.
An electrode plate for a plasma etching apparatus characterized by being formed so as to satisfy <L / 2 has been developed (Claim 1).

As described above, the diameter (d2) of the gas rectifying hole on the gas ejection side is smaller than the diameter (d1) of the gas introduction side (d2 <
By adopting the shape d1), the pressure is higher on the gas ejection side than on the gas introduction side, so that the entry of plasma can be suppressed, and the amount of reaction products attached to the inner wall of the gas rectification hole also decreases.

Further, in the electrode plate for a plasma etching apparatus according to the present invention, the gas rectifying holes are formed such that the distance L between adjacent gas rectifying holes (pitch) satisfies d1 <L / 2. A sufficient gap is provided between adjacent rectifying holes to maintain mechanical strength. Therefore, even if the surface of the electrode plate is consumed by etching, adjacent rectifying holes do not come into contact with each other or are not connected by a part of the rectifying holes. Can be used for a period.

[0015] The diameter of the gas rectification hole on the ejection side is 0.1
Preferably, it is 1.5 mm (claim 2). 0.
If a rectifying hole smaller than 1 mm is formed, it is difficult to form it.
In addition to the cost, the reaction product adheres to the inside of the hole and the hole is easily closed, but the cleaning is difficult. Also, 1.5mm
When the rectifying holes exceeding the number of rectifying holes are formed, the original gas rectifying action may be weakened.

The electrode plate is preferably made of silicon (claim 3), and has a specific resistance of 0.001.
It is preferably about 50 Ω · cm (claim 4). By using the electrode plate made of silicon in this way, contamination does not occur when the object to be processed is a silicon wafer. Further, those having a specific resistance in the above-mentioned range are also used as wafers, so that they have an advantage that they can be easily obtained and the cost can be reduced.

Further, the thickness of the electrode plate according to the present invention is 2
It is preferably about 20 mm (claim 5). If the thickness of the electrode plate is less than 2 mm, the strength of the electrode plate is weak, and if it exceeds 20 mm, it may be difficult to form a rectifying hole, and the material cost may increase, so that the thickness is within the above range. Is preferred.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings, but the present invention is not limited to these embodiments.

In the electrode plate according to the present invention, a plurality of gas flow regulating holes are formed at predetermined intervals. In the present invention,
It is characterized by the shape of the rectifying holes and the distance between the rectifying holes. That is, in the electrode plate for a plasma etching apparatus of the present invention, the diameter of the gas rectification hole is d1, the diameter of the gas introduction side is d2, the diameter of the gas ejection side is d2, and the distance between the centers of adjacent gas rectification holes is L. Then, d2 <d1 <
L / 2 is formed.

FIG. 1 schematically shows a partial cross section of an example of an electrode plate for a plasma etching apparatus according to the present invention. In the illustrated electrode plate 1, the maximum diameter (d
1) A tapered gas rectifying hole 2 having a minimum diameter (d2) is formed on the gas ejection side. The gas supplied from the internal gas supply system is ejected from a large number of gas rectification holes 2 provided in the electrode plate 1 into the reaction chamber.

In each gas rectification hole 2, gas flows from the inlet side with the largest diameter (d1) to the ejection side with the smallest diameter (d2), and is ejected at a pressure higher than the pressure at which the gas enters on the introduction side. Will be done. Therefore, it is possible to suppress the plasma generated in the reaction chamber from entering from the ejection side of the gas rectification hole 2, so that the reaction products can be prevented from adhering to the gas rectification hole 2, and the original rectification action can be maintained for a long time. Therefore, the number of times of cleaning the electrode plate 1 can be reduced. In addition, if the shape of the gas ejection side is reduced in this way, the diameter of the ejection side is unlikely to increase even after long-term use.

In the electrode plate for a plasma etching apparatus according to the present invention, a plurality of gas rectifying holes are formed at a sufficient interval so as to satisfy the relationship (d1 <L / 2). More specifically, in the electrode plate 1 shown in FIG. 1, the distance L between the centers of the adjacent rectifying holes 2a and 2b is represented by L = S + d1. Therefore, the relationship of d1 <L / 2 is equal to the relationship of d1 <S, that is, the rectification holes 2a and 2b are formed with an interval S larger than the diameter d1 on the introduction side. If the rectification holes are formed at such a sufficient interval, the mechanical strength can be sufficiently maintained even if a large number of rectification holes are provided. Also,
Even if the electrode plate itself is etched somewhat after long use, the rectifying holes do not touch each other or are not connected at any part of them. The amount is also kept uniform.

FIG. 2 schematically shows a partial cross section of another example of the electrode plate for a plasma etching apparatus according to the present invention. In the electrode plate 11 of FIG. 2, similarly to the electrode plate 1 shown in FIG. 1, a plurality of gas rectification holes 12 are formed so as to satisfy the relationship of d2 <d1 <L / 2. A two-stage cylindrical rectifying hole 12 having a diameter different from that on the ejection side is formed. Also in such an embodiment, since the gas is ejected from the introduction side to the ejection side at a high pressure, the plasma in the reaction chamber is suppressed from entering the gas rectification hole 12. Therefore, it is possible to prevent reaction products from adhering in the holes, reduce the number of times of cleaning, and prolong the life of the electrode plate.

Also, as with the embodiment shown in FIG. 1, the intervals between adjacent gas flow regulating holes are formed with sufficient intervals so that d2 <d1 <L / 2. Therefore, the mechanical strength is sufficiently maintained, the rectifying action is stabilized even after long-term use, and the gas ejection amount is also kept uniform. Note that the shape of the gas rectifying holes and the interval between adjacent rectifying holes are not limited to those shown in FIGS. 1 and 2, and may be, for example, a combination of a tapered shape and a cylindrical shape.

Regarding the specific size of the gas rectifying hole of the electrode plate according to the present invention as exemplified in FIGS. 1 and 2, the hole diameter on the ejection side should be 0.1 to 1.5 mm. preferable. As described above, forming a rectifying hole smaller than 0.1 mm is costly and difficult to form, and the reaction product adheres to the inside of the hole, and the hole is likely to be closed. On the other hand, when a rectifying hole exceeding 1.5 mm is formed, the original gas rectifying function may be weakened.

There is no particular limitation on the material of the electrode plate. However, if the electrode plate is made of the same material as the material to be processed, even if particles generated by etching the electrode plate adhere to the material to be processed, Since it is of the same quality, contamination can be effectively prevented. Therefore, for example, when etching a silicon wafer, it is preferable to use an electrode plate made of silicon.

When the silicon electrode plate is formed as described above, the specific resistance is preferably 0.001 to 50 Ω · cm, and particularly preferably 0.001 to 10 Ω · cm. Since the specific resistance of the silicon wafer to be processed is often within the above range, the wafer to be processed with the electrode plate is not only a material but also has very close electrical properties, and the electrode plate itself is Even if it is etched, contamination is more effectively suppressed. The wafer to be processed is usually obtained by slicing a silicon ingot. By cutting such an ingot into a thickness for an electrode plate, an electrode plate having the same properties as the wafer can be easily obtained at low cost. be able to.

The thickness of the electrode plate is preferably 2 to 20 mm. When the plate thickness is less than 2 mm, the mechanical strength becomes insufficient, and there is a possibility that it cannot be used for a long time. Further, when the thickness is more than 20 mm, it is difficult to form the rectifying hole, so that the cost of forming the rectifying hole becomes high. Wasting money.

[0029]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. (Examples and Comparative Examples) Cut a semiconductor ingot to 6 m
An m-thick silicon disk was obtained. After grinding the outer circumference, a gas rectifying hole on a taper as shown in FIG. 1 was formed by a diamond drill, and the surface was polished to a diameter of 280 m.
m, an electrode plate having a thickness of 5 mm was produced. In addition, the gas rectification hole formed by the diamond drill has a pitch of 7 m.
m, the opening diameter on the gas introduction side was 1 mm, and the opening diameter on the ejection side was 0.5 mm (Example 1).

In the same manner, a total of three types of electrode plates were prepared with only the opening diameter on the gas introduction side being 1.5 mm (Example 2) and 0.8 mm (Example 3), respectively. on the other hand,
As a comparative example, a straight straightening hole (diameter: 0.5 mm, pitch: 7 m) having the same opening diameter on the conventional gas introduction side and ejection side
The electrode plate having m) was used as a comparative example.

These electrode plates were attached to a plasma etching apparatus to etch a silicon wafer, and the number of particles generated when reaction products adhered to and separated from the rectification holes was compared with the operation time of the apparatus. The results are shown in FIG. 3 (the particle specification was 16
And up to pieces).

As is clear from the results shown in FIG. 3, when the conventional electrode plate (comparative example) having the same opening diameter on the gas introduction side and the ejection side is used, the number of particles increases and the specification deviates. About 35 hours later, whereas in the case of using the electrode plates of Examples 1 to 3, 60,
After 50 and 70 hours, both are longer. From these results, it can be seen that the electrode plates of Examples 1 to 3 can take a long operation time until the electrode plates need to be cleaned.

The present invention is not limited to the above embodiment. The above embodiment is merely an example, and has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same function and effect,
Anything is included in the technical scope of the present invention.

In the electrode plate for a plasma etching apparatus according to the present invention, as described above, the adhesion of reaction products is suppressed by the characteristics of the shape and the interval therebetween, so that contamination can be prevented as a result. Therefore, for example, even when a silicon wafer is etched, the material of the electrode plate is not particularly limited, and carbon, aluminum, silicon carbide, and the like which are conventionally used can also be used.

[0035]

As described above, the electrode plate according to the present invention is characterized by the shape of the rectifying holes and the distance between the rectifying holes.
The gas rectifying holes have a relationship of d2 <d1 <L / 2, which is the relationship between the hole diameter (d1) on the gas introduction side, the hole diameter (d2) on the gas ejection side, and the center distance (L) between adjacent gas rectifying holes. It is formed so that it becomes. By forming the gas rectification hole in this way, it is suppressed that plasma enters the gas rectification hole,
The adhesion of the reaction product to the pores is effectively prevented, and the mechanical strength and the like of the electrode plate are maintained for a long time.

Therefore, when the electrode plate according to the present invention is used in a plasma etching apparatus, the number of times of cleaning the electrode plate is greatly reduced, and the electrode plate itself can be used for a long period even if it is gradually etched and consumed. Furthermore, since the diameter is large on the gas introduction side of the electrode plate, the diameter is unlikely to be large on the gas ejection side, the rectifying action is stable for a long time, the gas ejection amount is kept uniform, and the productivity is improved. You can also.

[Brief description of the drawings]

FIG. 1 is a schematic partial sectional view of an example of an electrode plate for a plasma etching apparatus according to the present invention.

FIG. 2 is a schematic partial sectional view of another example of the electrode plate for a plasma etching apparatus according to the present invention.

FIG. 3 is a graph showing the relationship between the device operating time and the number of generated particles.

FIG. 4 is a schematic view showing an example of a plasma etching apparatus.

[Explanation of symbols]

1,11,21 ... electrode plate for plasma device (upper electrode plate), 2,2a, 2b, 12,22 ... gas rectification hole, 2
0: plasma etching apparatus, 23: lower electrode plate, 2
4 gas supply system, 25 gas discharge system, 26 high frequency voltage source, 27 silicon wafer, 28 internal gas container, 29 reaction chamber.

Continuation of the front page (72) Inventor Kazuyoshi Tamura 2-13-1, Isobe, Annaka-shi, Gunma F-term in the Shin-Etsu Kagaku Kogyo Co., Ltd. Precision Functional Materials Laboratory 4K057 DA01 DB06 DD01 DM03 DM06 DM09 DM37 DN01 5F004 AA01 AA16 BA04 BB13 BB28 BB29 5F045 BB01 DP03 EB03 EB05 EB06 EF05 EF08 EF11 EF14 EH13

Claims (5)

[Claims] 1. An electrode plate provided with a plurality of gas rectifying holes used as an upper electrode of a plasma etching apparatus, wherein the gas rectifying holes have a hole diameter on the gas introduction side of d.
1. A plasma etching apparatus characterized by being formed such that d2 <d1 <L / 2, where d2 is the hole diameter on the gas ejection side and L is the center-to-center distance between adjacent gas rectification holes. Electrode plate. 2. The gas rectifying hole having a diameter on the ejection side of 0.
The electrode plate for a plasma etching apparatus according to claim 1, wherein the electrode plate has a thickness of 1 to 1.5 mm. 3. The electrode plate for a plasma etching apparatus according to claim 1, wherein said electrode plate is made of silicon. 4. The specific resistance of said electrode plate is 0.001 to 5
4. The electrode plate for a plasma etching apparatus according to claim 3, wherein the resistance is 0 Ω · cm. 5. The electrode plate for a plasma etching apparatus according to claim 1, wherein the thickness of the electrode plate is 2 to 20 mm.