JP2000058510A - Electrode plate for plasma etching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of foreign matters in an electrode plate for plasma etching, by forming the plasma face-side end sections or both end sections of a plurality of through holes formed through the electrode plate in tapered shapes having large-diameter sections at the ends of the holes. SOLUTION: A plurality of through holes formed through an electrode plate for plasma etching for blowing an etching gas are formed to have tapered end sections having large-diameter sections at the ends of the holes. At the time of forming the tapered end sections, the surface of the electrode plate around the through holes is polished with a loose abrasive of alumina, cerium oxide, etc. Consequently, foreign matters are prevented from falling down from the electrode plate, because the concentration of discharge to the surface of the electrode is prevented and the local wear of the electrode surface is eliminated. Since the end sections of the through holes on the rear surface of the electrode plate which comes into contact with a back plate are formed in the tapered shapes, the etching gas is made to flow smoothly and the creeping of plasma can be suppressed. In addition, the amount of resulted deposits of reaction can be reduced and the deposits can be prevented from coming off the electrode plate and falling onto a wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching electrode plate suitably used for a dry etching apparatus in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art One of the semiconductor device manufacturing processes includes an etching process for forming a circuit pattern on a silicon wafer. As an apparatus for performing this etching, a plasma etching apparatus is used. In the plasma etching apparatus, as shown in FIG. 1, an upper electrode 2 and a lower electrode 3 are provided in a vacuum vessel 1 at an interval, and a silicon wafer 4 is mounted on the lower electrode 3 as a material to be processed. It is location. The upper electrode 2 is composed of a back plate 5 and a plasma etching electrode plate 6, each having a through hole 7 for blowing out an etching gas.

A high-frequency power is applied between the upper electrode 2 and the lower electrode 3 by a high-frequency power supply 8 while flowing an etching gas toward the silicon wafer 4 through the through-hole 7 to form a plasma 10. The silicon wafer 4 is etched by the plasma 10 to form a device having a predetermined pattern. The shield ring 9 is made of an insulating material such as alumina or quartz, and is installed so as to cover the outer peripheral portion of the plasma etching electrode plate 6 in order to protect the mounting screw of the plasma etching electrode plate 6 from the plasma 10.

As the plasma etching electrode plate 6 is used, a portion where plasma is generated, that is, a portion having substantially the same area as the silicon wafer 4 facing the portion is etched by the plasma. As described above, the electrode itself is etched by the plasma, or the reaction deposits are separated by the etching gas, so that the foreign matter falls on the silicon wafer, and a desired etching pattern is not formed and a wiring defect is caused. Or cause device malfunction. In addition, the yield of the device is reduced. For this reason, the plasma etching electrode plate is required to minimize the generation of foreign matter.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma etching electrode plate capable of minimizing the generation of the above-mentioned foreign substances in order to improve the yield of devices.

[0006]

In order to achieve the above-mentioned object, as a result of studying the shape of a through-hole through which an etching gas provided in a plasma etching electrode plate is passed and diffused, the both ends of the through-hole are tapered. As a result, the above-mentioned object is achieved, and the present invention has been completed based on this finding.

That is, according to the present invention, in a plasma etching electrode plate provided with a plurality of through holes for blowing an etching gas at a central portion, the plasma surface side end or both ends of the through hole is formed at the end surface of the through hole. And a tapered shape having a large diameter portion.

[0008] The present invention also relates to a plasma etching electrode plate in which the material of the electrode plate is glassy carbon, single crystal silicon, polycrystalline silicon or silicon carbide.

Further, according to the present invention, when the tapered shape at the end of the through hole is such that the horizontal distance from the start point to the end point of the taper is T ₁ and the vertical distance is T ₂ , T ₁ and T ₂ are: 0.0
1 μm ≦ T ₁ ≦ 200 μm, 0.1 μm ≦ T ₂ ≦ 10 μm
And a plasma etching electrode plate.

Further, according to the present invention, when the taper shape at the end of the through hole is such that the horizontal distance from the start point to the end point of the taper is T ₁ and the vertical distance is T ₂ , T ₁ and T ₂ are: 10μ
The present invention relates to a plasma etching electrode plate in which m ≦ T ₁ ≦ 100 μm and 1 μm ≦ T ₂ ≦ 5 μm.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to a plasma etching electrode plate in which at least the end of the through hole on the plasma surface side, that is, the end of the through hole facing the wafer has a tapered shape. To prevent local depletion of the electrode surface and to prevent foreign matter from falling off. More preferably, by forming the end of the through hole on the back surface in contact with the back plate into a tapered shape, the flow of the etching gas is improved, the flow of the plasma is suppressed, the reaction deposit is reduced, and the reaction deposit is reduced. It prevents peeling and falling on the wafer.

[0012] The shape of the plasma etching electrode plate of the present invention is determined according to the structure of the plasma etching apparatus.
Although not particularly limited, it is generally disk-shaped. The material is preferably made of glassy carbon, single crystal silicon, polycrystalline silicon, silicon carbide or the like. More preferably, those composed of glassy carbon are used.

[0013] Glassy carbon is a carbon material obtained by carbonizing a high-temperature cured thermosetting resin and subjecting it to a high temperature treatment. The thermosetting resin used is not particularly limited, but may be a phenol resin, an epoxy resin or an unsaturated resin. Examples thereof include polyester resins, furan resins, melamine resins, alkyd resins, and xylene resins. Further, a mixture of these resins may be used. Preferably, it is a furan resin and / or a phenol resin or a mixed resin thereof.

A curing agent is used according to the type of the thermosetting resin. Examples of the curing agent include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; organic sulfonic acids such as p-toluenesulfonic acid and methanesulfonic acid; and carboxylic acids such as acetic acid, trichloroacetic acid, and trifluoroacetic acid. The curing agent is preferably used in an amount of 0.001 to 20% by weight based on the thermosetting resin.

The thermosetting resin is added with the curing agent as needed, molded by various molding methods according to the desired shape, and then cured. This curing is 60-20
The heat treatment is preferably performed at a temperature of 0 ° C, more preferably 70 to 100 ° C.

If necessary, after further performing predetermined processing as a plasma etching electrode plate, a highly purified jig and a furnace are used in an inert atmosphere (usually, an inert gas such as helium or argon, nitrogen, An oxygen-free atmosphere composed of at least one kind of non-oxidizing gas such as hydrogen or halogen gas or under vacuum), preferably 800
It is calcined at a temperature of ３3000 ° C., more preferably 1100-2800 ° C., and carbonized. Then preferably 1300
High temperature treatment at a temperature of 3500 ° C. can obtain glassy carbon.

Although the size and shape of the plasma etching electrode plate of the present invention are not particularly limited,
A disk-shaped one having a thickness of 3 to 400 mm and a thickness of 3 to 10 mm is preferable. It is preferable to provide 8 to 24 mounting holes on the outer peripheral portion for mounting the electrode plate to the plasma etching apparatus. It is preferable that the through-hole for blowing out the etching gas for dispersing the etching gas in a shower shape is provided on the inner peripheral portion than the mounting hole. The size of this through-hole varies depending on the etching conditions and the like, but the diameter of the through-hole is 0.3 to 2.0.
mm is preferable, and the number of holes is preferably 100 to 3000. The holes can be processed by machining, electric discharge machining, ultrasonic machining, or the like.

In order to form the end of the through hole into a tapered shape, for example, the surface of the electrode around the through hole is polished using a free abrasive such as alumina or cerium oxide to form a tapered shape.
There is also a method in which the end of the through hole is tapered by using a drill having a desired tapered tip. The method of forming both ends of the through hole into a tapered shape is not particularly limited.

The tapered shape at both ends of the through hole is such that the horizontal distance (with respect to the plane direction of the electrode plate surface) from the start point to the end point of the taper is T ₁ , and the vertical distance (with respect to the plane direction of the electrode plate surface). ) when was the T ₂ Te, T ₁ and T ₂ is, 0.01 [mu] m
≦ T ₁ ≦ 200 μm, preferably 0.1 μm ≦ T ₂ ≦ 10 μm, preferably 10 μm ≦ T ₁ ≦ 100 μm, 1 μm
It is more preferable that ≦ T ₂ ≦ 5 μm. FIG. 2 is a partial cross-sectional view around the through-hole for clarifying the definitions regarding T ₁ and T ₂ .

In the present invention, the term "tapered shape" refers to the shape of the widened portion where the through hole expands from the inside toward the end, and the shape is only linear as shown in FIG. Instead, it may be curved and spread as shown in FIGS. 3 (a) and 3 (b). Also,
The spread may be uniform in all directions or non-uniform (for example, when the end face of the through-hole becomes elliptical).

The proportion of the through hole having a tapered shape is not limited as long as the effects of the present invention are achieved, but is preferably 50% or more, more preferably 70% or more, and 90 to 100%. More preferably,

The plasma etching apparatus is not particularly limited except that the above-mentioned plasma etching electrode plate is used. One example of the apparatus is shown in FIG. 1 described above. In the plasma etching apparatus of FIG. 1, the above-described plasma etching electrode plate of the present invention may be used as the plasma etching electrode plate 6.

[0023]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 11 and Comparative Examples Furan resin (VF-302 manufactured by Hitachi Chemical Co., Ltd.) 10
To 0 parts by weight, 0.3 parts by weight of paratoluenesulfonic acid and 0.3 parts by weight of ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.) were added, and after sufficient mixing, the resin was poured into a mold.
After drying and curing at 70 ° C. for 3 days, 70 ° C. for 3 days and 90 ° C. for 3 days, the temperature was raised to 160 ° C. at 5 ° C./hour, and kept at 160 ° C. for 3 days to perform a curing treatment, 5 mm in thickness and 400 mm in diameter. Was obtained. After processing the formed body into a shape having a size that allows for dimensional shrinkage (20% shrinkage) of firing, the temperature is raised to 160 ° C. at a rate of 5 ° C./hour.
4 days thickness and 285mm
mm was obtained. The molded body was placed in an electric furnace and calcined and carbonized at a temperature of 1000 ° C. in a nitrogen gas stream. I got carbon. Three through holes with a diameter of 0.8 mm were formed in the glassy carbon.
Many holes were drilled at a pitch of mm.

Next, loose abrasive grains (made of alumina, 1200 #,
All the through-holes were polished using 2000 #) to produce a plasma-etched electrode plate having tapered through-holes at both ends shown in Table 1 as shown in FIG. Next, an evaluation sample of 65 mm × 65 mm × 4 mm was manufactured from this electrode plate, attached to a plasma etching apparatus for sample evaluation of the electrode plate, and a mixed gas of oxygen, argon, and fluorocarbon gas was flowed as a reaction gas, and the inside of the reaction chamber was Gas pressure: 1 Torr, power frequency: 13.5M
Plasma was generated at a frequency of Hz, and foreign particles dropped on an 8-inch silicon wafer mounted on the lower electrode were measured. Table 1 shows the results.

As is clear from the results in Table 1, the tapered shape of the end of the through hole of the electrode is 10 μm ≦ T ₁ ≦ 100 μm.
m, 1 μm ≦ T ₂ ≦ 5 μm, the generation of foreign matter was the least.

[0027]

[Table 1] * Average value measured at the center of the sample and a total of 5 through holes

[0028]

By using the plasma etching electrode plate of the present invention, it is possible to reduce foreign substances falling on the silicon wafer during etching by the plasma etching apparatus, and to suppress a decrease in yield in semiconductor wafer production. became.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a plasma etching apparatus.

FIG. 2 is a partial sectional view of a plasma etching electrode plate of the present invention.

FIG. 3 is a partial sectional view of the plasma etching electrode plate of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Upper electrode 3 Lower electrode 4 Silicon wafer 5 Back plate 6 Plasma etching electrode plate 7 Through hole 8 High frequency power supply 9 Shield ring 10 Plasma

Claims (4)

[Claims] 1. A plasma etching electrode plate having a plurality of through-holes for blowing an etching gas at a central portion, wherein the plasma-side end or both ends of the through-hole have a large-diameter portion at the end surface of the through-hole. A plasma etching electrode plate having a tapered shape. 2. The material of the electrode plate is glassy carbon, single crystal silicon, polycrystalline silicon or silicon carbide.
The electrode plate according to any one of the preceding claims. 3. The tapered shape at the end of the through hole is such that the horizontal distance from the start point to the end point of the taper is T ₁ , and the vertical distance is T _2.
When T ₁ and T ₂ are 0.01 μm ≦ T ₁ ≦ 20
3. The plasma-etched electrode plate according to claim 1, wherein 0 μm and 0.1 μm ≦ T ₂ ≦ 10 μm. It is wherein T ₁ and _{T 2, 10μm ≦ T 1 ≦} 100
4. The plasma-etched electrode plate according to claim 3, wherein μm, 1 μm ≦ T ₂ ≦ 5 μm.