JPH1154488A - Electrode plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance productivity and the quality of a semiconductor wafer while increasing the yield of etching by forming a long life electrode plate in which the drilling work can be facilitated and the etching rate is constant even after a long time operation. SOLUTION: In a small diameter electrode plate for straightening a reaction gas, the bore diameter is set larger in the inner circumferential region than in the outer circumferential region. The outer circumferential region of the electrode plate is an annular region except one half of a radius connecting the center of a bore made in the vicinity of the outer circumference of the electrode plate and the center thereof and the inner circumferential region is the circular region within one half of the radius. Maximum bore diameter in the inner circumferential region is set larger by 25 μm or more that that in the outer circumferential region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as an apparatus for dry-etching a semiconductor wafer, an electrode plate is provided above a wafer to be processed in a reaction chamber, and a high frequency is applied to the electrode plate to generate plasma. For example, a plasma etching apparatus for etching an insulating film, a wiring, and the like on a wafer is used. As disclosed in Japanese Patent Application Laid-Open No. Hei 4-73936, an electrode plate used in this apparatus is usually provided with a large number of small holes having the same diameter for introducing a reaction gas into a reaction chamber. .

However, as the electrode plate is used, the thickness of the portion facing the wafer is etched and thinned, and the corner of the small-diameter hole on the side facing the wafer is also etched, causing dripping. As a result, the hole diameter becomes large. The change in the hole diameter is different between the central portion and the outer peripheral portion of the electrode plate. As a result, a phenomenon occurs that the flow rate of the etching gas is relatively different between the central portion and the outer peripheral portion of the wafer.

Therefore, if all the small diameter holes of the electrode plate are formed to have the same diameter, the non-uniformity of the etching rate that the etching rate of the wafer differs between the central portion and the outer peripheral portion as the use time of the electrode plate becomes longer. This has caused a decrease in the yield of the wafer etching process and a decrease in the wafer quality.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and the drilling process is easy, the service life is long, and the etching rate can be maintained even after a long operation. An object of the present invention is to form an electrode plate that does not change and to improve the yield and quality of the etching process of a semiconductor wafer.

[0006]

According to a first aspect of the present invention, there is provided an electrode plate having a small-diameter hole for rectifying a reaction gas. An electrode plate wherein the diameter of the small diameter hole in the inner peripheral area is larger than the diameter of the small diameter hole in the outer peripheral area.

With this arrangement, the flow rate of the etching gas ejected from the small-diameter holes in the outer peripheral area becomes substantially equal to the flow rate of the etching gas ejected from the small-diameter holes in the inner peripheral area on the surface of the workpiece. As a result, the etching rate on the surface of the object to be processed is kept uniform over the entire surface, and a uniformly etched semiconductor wafer can be obtained at a high yield.

Although the small diameter holes of the electrode plate are also etched with time, the difference between the small diameter holes in both regions is maintained for a long time and the electrode plate becomes durable, so that the frequency of replacing the electrode plate is reduced. Thus, the productivity of the etching process is improved.

The outer peripheral area of the electrode plate is defined as an inner annular area other than 1/2 of the radius connecting the center of the small diameter hole formed near the outer periphery of the electrode plate and the center of the electrode plate. When the area is set to be a circular area within 1/2 of the radius (claim 2), the ratio of the annular area of the outer peripheral area to the circular area of the inner peripheral area becomes about 3: 1, and The flow rates of the etching gas passing through the small-diameter holes are substantially equalized, and uniform etching can be performed on the entire surface of the wafer, and the durability is improved.

The invention described in claim 3 of the present invention is characterized in that the maximum pore diameter in the small diameter hole group in the inner peripheral region is larger than the maximum pore diameter in the small diameter hole group in the outer peripheral region by 25 μm or more. More specifically, the maximum hole diameter in the small diameter hole group in the inner peripheral region is 0.2 to 1.0 mm (claim 4), and the maximum diameter in the small diameter hole group in the outer peripheral region is The hole diameter is 0.175 to 0.975 mm (Claim 5)
It can be an electrode plate.

As described above, when the maximum hole diameter is more specifically defined, the etching gas flow rates in the two regions become substantially equal over a long period of time, and the etching rates on the surface of the workpiece corresponding to the two regions hardly change. Also, since there is almost no difference, a uniformly etched semiconductor wafer can be manufactured with high yield and high productivity.

In particular, the maximum hole diameter in the small hole group in the inner peripheral region is
It is better to make the hole larger than the maximum hole diameter in the small hole group in the outer peripheral region by 25 μm or more. If it is less than 25 μm, the difference in hole diameter is too small, the difference in the flow rate of the etching gas becomes large, and uniform etching can be performed. Hateful. If the maximum pore diameter is less than the above range (<0.2 mm in the inner peripheral region or <0.175 mm in the outer peripheral region), the flow rate of the etching gas is reduced, and the etching rate of the wafer is reduced. If it exceeds (in the inner area>
(1.0 mm or> 0.975 mm in the outer peripheral area) The flow rate of the etching gas is increased, which causes a problem that the etching rate is too large.

[0013] In this case, the size of the electrode plate is 200 to 400 mm in outer diameter and 2 to 400 mm in thickness.
It may be a 15 mm disk and the number of small diameter holes drilled in the electrode plate is in the range of 150 to 5000.

When the size of the electrode plate is within the above range, in recent years, the shape of the wafer to be processed, such as silicon, used particularly in the production of advanced devices is well matched, and the uniformity of the etching rate is increased. Can hold for hours. Further, if the number of small diameter holes is out of this range, even if the maximum hole diameter value of the outer peripheral region and the inner peripheral region is set within the specified range, the uniformity of the flowing gas flow rate is impaired, and the etching rate becomes uneven. Sex becomes noticeable.

According to the present invention, the material of the electrode plate is made of any one of silicon, carbon, aluminum and silicon carbide.

This is because if other materials are used as an electrode plate of a plasma etching apparatus, they tend to become heavy metals and other impurities which cause deterioration of device characteristics when manufacturing a semiconductor device. In this case, if the wafer to be processed is semiconductor silicon, it is preferable to select silicon among the above materials, since the same material as the semiconductor material to be processed is obtained.

According to an eighth aspect of the present invention, the electrode plate can be used for a plasma etching apparatus, a reactive ion etching apparatus, a plasma ashing apparatus, or a plasma CVD apparatus.

This is because the electrode plates manufactured in accordance with the above-mentioned various specified values become the opposite electrode plates for plasma generation in any of these devices, and serve as rectifiers for the reaction gas. Can work effectively.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings using plasma dry etching as an example, but the present invention is not limited thereto.

The present inventors have repeatedly studied various conditions for improving the uniformity of the etching rate in the dry etching, and as a result, established various conditions by paying attention to the hole diameter distribution and arrangement of the small holes in the electrode plate. Thus, the present invention has been completed. Here, FIG. 1 is an explanatory diagram showing an arrangement state of small-diameter holes as an example of the present invention, and FIG. 2 is a schematic diagram of a plasma dry etching apparatus.

The electrode plate of the present invention will be described with reference to FIG. 1 for plasma dry etching.
A large number of small-diameter holes 3 and 4 are drilled into the reaction chamber, and a reaction gas is injected from the small-diameter holes toward the object to be processed, and a high frequency is applied to generate plasma, which reacts with the object to be processed. Will be etched.

FIG. 2 shows a state in which the electrode plate 1 is set in the plasma dry etching apparatus 20, and a semiconductor wafer 5 and a flat electrode 6 which are the objects to be processed are set at positions facing the electrode plate 1. Then, a high frequency is applied between both electrodes. On the other hand, the etching gas enters the internal gas container 7 from the gas supply system 9 and is rectified by the small diameter hole of the electrode plate 1,
Plasma is generated and is ejected toward the wafer 5 to etch the wafer surface.

As for the electrode plate of the present invention, the relationship between the arrangement of these small-diameter hole groups and the hole diameter was first determined. As a result, empirically, in the disk-shaped electrode plate having the small-diameter hole for rectifying the reaction gas, It has been found that the region in which the hole is formed is divided into two large parts, the outer peripheral region and the inner peripheral region are set, and the diameter of the small diameter hole 4 in the inner peripheral region is larger than that of the small diameter hole 3 in the outer peripheral region.

By doing so, the small-diameter hole 3 in the outer peripheral region is formed.
The flow rate of the etching gas spouted from the group and the flow rate of the etching gas spouted from the group of small-diameter holes 4 in the inner peripheral region become substantially equal on the surface of the object to be processed. , And a uniformly etched semiconductor wafer can be obtained at a high yield.

In this case, the small-diameter holes of the electrode plate are also etched with the lapse of time with use. However, by providing a difference in the hole diameter in advance, the difference in the hole diameters of the small-diameter hole groups in both regions is maintained for a long time. In addition, since the electrode is durable, the frequency of replacing the electrode plate is reduced, and the productivity of the etching process is improved.

The outer peripheral area of the electrode plate is defined as an inner ring area [R- (1) other than 1/2 of the radius connecting the center of the small diameter hole formed near the outer periphery of the electrode plate and the center of the electrode plate. / 2 ・
R)] and the inner peripheral region is set to be a circular region [１ ／ · R] within １ ／ of the radius, the ratio of the annular area of the outer peripheral region to the circular area of the inner peripheral region becomes The ratio is about 3: 1, and the flow rates of the etching gas passing through the small-diameter hole groups in both regions become substantially equal, so that uniform etching can be performed over the entire surface of the wafer, and the durability of the electrode plate is also improved.

Further, it is preferable that the maximum pore diameter in the small diameter hole group in the inner peripheral region is larger than the maximum pore diameter in the small diameter hole group in the outer peripheral region by 25 μm or more. By setting the maximum diameter of such small diameter holes, the flow rate of the etching gas introduced into the center of the wafer corresponding to the small diameter holes in the inner peripheral region of the electrode plate and the small diameter holes in the outer peripheral region are reduced. The flow rate of the etching gas introduced into the outer peripheral portion of the wafer is relatively changed as compared with the case where the diameters of the small-diameter hole groups in both regions are the same, become substantially equal, and the etching rate of the wafer becomes uniform. The properties are extremely good, and a uniformly etched semiconductor wafer can be manufactured.

Further, the durability of the electrode plate is also improved, and the deterioration of the uniformity of the etching rate due to the change in the hole diameter due to the etching of the electrode plate itself when used for a long time is reduced. Also decreases, thus
Production efficiency will also be significantly improved.

As for the average pore diameter and the minimum pore diameter, there may be a difference between the small hole group in the inner peripheral region and the small hole group in the outer peripheral region, or they may be equal. This is because the maximum hole diameter has a large effect on the uniformity of the etching rate of the wafer. However, the average pore diameter and the minimum pore diameter are preferably in the range of 0.15 to 0.90 mm.
Even if the thickness is less than 0.15 mm or exceeds 0.90 mm, it is difficult to control the pressure and flow rate of the etching gas, and the uniformity of the wafer etching rate is deteriorated.

As a result of further detailed studies on conditions for improving the uniformity of the etching rate,
The number of small-diameter holes formed in the electrode plate is set to 150 to 5000, and the maximum diameter of the small-diameter hole group in the inner peripheral region is set to 0.2 to
It was found that the diameter should be 1.0 mm, and the maximum hole diameter in the small hole group in the outer peripheral region should be 0.175 to 0.975 mm. If the number of the small holes is less than 150, the etching gas hardly reaches the entire surface of the wafer. As a result, the uniformity of the wafer etching rate is impaired.

Further, the maximum hole diameter in the inner peripheral area is 0.2 to 0.2.
1.0 mm range, maximum hole diameter in the outer peripheral area is 0.175
If the diameter is smaller than the range of about 0.975 mm, the flow rate of the etching gas is reduced, and a problem that the etching rate of the wafer is reduced occurs. If the diameter is larger than this range, the flow rate of the etching gas is increased, and There is a problem that the etching rate becomes too large.

Further, the electrode plate has a disk shape in plan view, an outer diameter of 200 to 400 mm, and a thickness of 2 to 15 mm.
When the thickness is in the range of mm, the shape of the electrode plate is well adapted to the wafer to be processed, and the electrode plate itself is consumed by plasma etching.However, the life of the electrode plate determined by the progress of the consumption may be prolonged. it can.

When the electrode plate of the present invention is used for plasma etching, the electrode plate itself is also etched and consumed because the electrode plate itself is made of silicon, carbon, aluminum, and silicon carbide. If any one of the above is selected and used, no heavy metal or alkali metal which becomes an impurity in the semiconductor process and lowers the yield is generated from the electrode plate, and the amount of impurities on the wafer to be etched is reduced. In this case, if the wafer to be processed is semiconductor silicon, the same material as the semiconductor material will be obtained if silicon is selected among the above materials,
The amount of impurities is extremely small, which is preferable.

If the small-diameter hole of the electrode plate is formed by ultrasonic machining, electric discharge machining, laser machining, or diamond drilling, a small-diameter hole having a desired diameter can be obtained very easily and accurately.

[0035]

EXAMPLES The present invention will now be described specifically with reference to examples of the present invention, but the present invention is not limited to these examples.
(Example 1) First, the outer diameter is 300 mm and the resistivity is 0.1Ω.
cm single crystal silicon ingot was prepared. From now on, it is sliced to a thickness of 6mm, and the diameter is 280m
The outer periphery was processed to have an outer diameter of m. Thereafter, twelve mounting holes provided with a counterbore for mounting the electrode plate to the apparatus were formed in the outermost periphery of the electrode plate.

Next, this material was attached to a machining center, and 158 holes were diamond-formed at a pitch interval of 7 mm using a single-crystal diamond tool having an outer diameter of 0.55 mm in an inner peripheral region of 100 mmφ from the center of the electrode plate. When the diameter of the small diameter hole in the inner peripheral area was measured,
It was in the range of 6 to 0.58 mmφ.

Thereafter, an outer diameter of 0.50 mm is set in an outer peripheral region exceeding 100 mmφ from the center of the electrode plate to 200 mmφ.
7 mm pitch using a single-crystal diamond tool
475 holes were diamond processed in mm. When the hole diameter of the small-diameter hole in the outer peripheral area was measured, it was 0.51 to 0.535 m.
mφ range.

The electrode plate manufactured as described above is attached to a plasma dry etching apparatus as shown in FIG.
A CF ₄ gas was ejected from the small-diameter hole to etch a silicon oxide film of a circuit formed on a silicon wafer. As a result, even when the plasma processing time exceeded 250 hours, the in-plane uniformity of the etching rate of the silicon wafer was as good as 4.0%.

(Comparative Example 1) For comparison, an electrode plate was prepared by using the electrode plate of the above-described embodiment, in which all the small holes were bored at 0.50 mmφ in diameter. Only the wafer was replaced, and the silicon wafer was etched. As a result, the plasma processing time is 100
If the time is exceeded, the in-plane uniformity of the etching rate of the silicon wafer deteriorates to 10.0%, so that it becomes impossible to manufacture a device.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same effect. Within the technical scope of

For example, in the application of the present invention, it has been described that the present invention is suitable as a reaction gas rectifying electrode plate in a plasma etching apparatus. However, the present invention is not limited to such an example. An electrode plate for an active ion etching apparatus, a plasma ashing apparatus, or a plasma CVD apparatus has substantially the same function and effect, and is effectively used.

[0042]

According to the present invention, an electrode plate which is easy to perform a boring process, has a long service life, and does not change its plasma etching rate even after a long operation, is formed, and the plasma etching yield and production of a semiconductor wafer are formed. The quality and quality can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an arrangement state of small-diameter holes in an electrode plate of the present invention.

FIG. 2 is a schematic diagram of a plasma dry etching apparatus to which the present electrode plate is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrode plate, 2 ... Mounting hole, 3 ... Small diameter hole in outer peripheral area, 4 ... Small diameter hole in inner peripheral area, 5 ... Semiconductor wafer, 6 ... Flat electrode, 7 ... Internal gas container, 8 ... Chamber, 9 ... Gas Introducing system, 10: gas exhaust system, 20: plasma dry etching apparatus, R: radius to the center of the small-diameter hole near the outer periphery, C: center of the electrode plate.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Keiichi Goto 2-13-1 Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Industry Co., Ltd.

Claims (8)

[Claims] 1. An electrode plate having a small-diameter hole for rectifying a reaction gas, wherein a diameter of a small-diameter hole in an inner peripheral region is larger than a small-diameter hole in an outer peripheral region in a region where the small-diameter hole is formed. An electrode plate characterized by the above-mentioned. 2. An outer peripheral area of the electrode plate is an inner annular area other than 1/2 of a radius connecting a center of a small-diameter hole formed near an outer periphery of the electrode plate and a center of the electrode plate. 2. The electrode plate according to claim 1, wherein the peripheral region is a circular region within 1/2 of the radius. 3. The maximum hole diameter in the small diameter hole group in the inner peripheral region is 25 μm larger than the maximum hole diameter in the small diameter hole group in the outer peripheral region.
3. The method according to claim 1, wherein the distance is greater than m.
2. The electrode plate according to 1. 4. The electrode plate according to claim 1, wherein a maximum hole diameter in the group of small diameter holes in the inner peripheral region is 0.2 to 1.0 mm. . 5. The electrode plate according to claim 1, wherein the maximum hole diameter in the small hole group in the outer peripheral region is 0.175 to 0.975 mm. 6. The electrode plate has an outer diameter of 200 to 400 m.
m, a circular plate having a thickness of 2 to 15 mm, and the number of small-diameter holes formed in the electrode plate is 150 to 5000. Item 8. The electrode plate according to Item. 7. The electrode plate according to claim 1, wherein a material of the electrode plate is any one of silicon, carbon, aluminum, and silicon carbide. . 8. The plasma processing apparatus according to claim 1, wherein the electrode plate is used for a plasma etching apparatus, a reactive ion etching apparatus, a plasma ashing apparatus, or a plasma CVD apparatus. Item 8. The electrode plate according to Item.