JPH11219932A - Electrode plate for plasma etching and plasma etching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it easy to feed stably an electrode plate for plasma etching and also to contrive to raise evenness in an etching rate within the surface of a wafer by a method wherein the electrode plate for plasma etching is constituted of an electrode main body part, which consists of a polycrystalline silicon material, and mounted parts, which consist of a carbon material. SOLUTION: An electrode plate 6, for plasma etching has an electrode main body part 61, which is subjected to plasma irradiation, and mounted parts 63 provided on the outsides of the main body part 61. The main body part 61 is constituted of a polycrystalline silicon material and the mounted parts 63 are constituted of a glassy carbon material or glassy carbon-coated carbon material. Both of the main body part 61 and the mounted parts 63 are combined with each other utilizing steps 66 and are mutually fixed with a fixed seal made of a resin. Gas blow-off holes 62 for making etching gas scatter into a shower shape are provided in the main body part 61, while mounting holes 64 for incorporating and fixing the electrode plate 6 in a plasma etching device as one part of an upper electrode are respectively provided in the parts 63.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode plate for plasma etching and a plasma etching apparatus using the same, and more particularly, to a gas for applying high-frequency power to a reaction chamber and dispersing an etching gas into a shower. The present invention relates to an electrode plate to which the high-frequency power is applied in a parallel plate type plasma etching apparatus having an electrode having a blowout hole and an electrode on which a silicon wafer is placed facing the electrode.

[0002]

2. Description of the Related Art An electrode plate for plasma etching is used as an upper electrode of a plasma etching apparatus used in a fine pattern forming process in a semiconductor device manufacturing process.

In a conventional plasma etching apparatus, for example, as shown in FIG. 4, an upper electrode 2 and a lower electrode 3 are provided in a vacuum vessel 1 at an interval. A silicon wafer 4 is placed on the wafer. The upper electrode 2 is composed of a back plate 5 and an electrode plate 6, each of which is provided with a gas blowing hole 7 for flowing an etching gas. A high-frequency power is applied between the upper electrode 2 and the lower electrode 3 by the high-frequency power supply 8 while flowing the etching gas toward the silicon wafer 4 through the gas blowing holes 7 to form the plasma 11. The silicon wafer 4 is etched by this plasma to form a device having a predetermined pattern.

The shield ring 9 is made of an insulating material such as alumina or quartz, and has a screw 10 for mounting the electrode plate 6.
Is installed so as to cover the outer periphery of the electrode plate 6 in order to protect the electrode plate from plasma.

As the electrode plate 6 is used, a portion where a plasma is generated, that is, a portion having substantially the same area as the silicon wafer 4 facing the electrode plate 6 is etched and consumed by plasma. Therefore, when the electrode plate 6 is consumed to some extent and the etching characteristics (such as foreign particles attached to the silicon wafer 4 during the etching) deviate from the standard, the use of the electrode plate 6 is stopped and replaced with a new electrode plate.

The electrode plate for plasma etching is required to be a highly purified material in addition to characteristics such as conductivity, low dust generation and plasma resistance.

[0007] Materials currently used as electrode plates for plasma etching include silicon-based materials such as single crystal silicon and polycrystalline silicon, carbon materials such as graphite and glassy carbon, and conductive ceramics such as silicon carbide. Is mentioned.

These materials have advantages and disadvantages in some of the characteristics required for an electrode plate for etching, but have various characteristics in terms of high purity, low dust generation, low consumption rate, and easy control of plasma. Silicon-based materials such as crystalline silicon and single-crystal silicon are considered to be excellent.

[0009] The electrode plate for plasma etching includes an electrode body portion exposed to plasma and a mounting portion to be attached to the etching apparatus. Therefore, the target wafer is 6
If it is inch, the size of the electrode plate for plasma etching is 8
The electrode plate for plasma etching needs a material larger in size than the target wafer by the mounting portion, such as 12 inches if the wafer is 8 inches or 8 inches.

In recent semiconductor manufacturing, silicon wafers have become larger in diameter, and the use of 12-inch wafers has been studied. A 16-inch size material is required for the corresponding electrode plate for plasma etching.
At present, when inch wafers are not mass-produced, the supply of silicon material for electrodes is very unstable.

Although the electrode plate is mounted in close contact with the back plate, the back plate needs to be provided with a gas hole through which the etching gas passes, so that only the outer peripheral portion is cooled. ing. For this reason, the cooling effect of the electrode plate becomes greater toward the outer periphery. In addition, since the plasma density is high at the central part of the electrode plate, the heating effect by the plasma is greater than that at the peripheral part. Therefore, a difference tends to occur in the temperature distribution between the central portion and the outer peripheral portion of the electrode plate.

The temperature difference generated in the electrode plate causes the etching rate in the wafer surface to be non-uniform, and as a result, the etching rate tends to be higher in the central portion where the temperature of the electrode plate is higher. This tendency becomes remarkable as the size of the electrode plate increases. Further, when only the central portion is heated to a high temperature, warpage occurs in a state where the entire electrode plate is convex on the mounting surface due to a partial difference in thermal expansion, and a gap is formed between the electrode plate and the back plate. This gap is not desirable because it causes abnormal discharge and accumulation of thermal decomposition products of the etching gas and induces frequent discharge foreign substances.

[0013] From the background described above, as the diameter of the wafer increases, it becomes necessary to ensure the stability of the silicon material as the electrode material, improve the uniformity of the etching rate, and reduce the generation of discharge foreign matter. .

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to cope with an increase in the diameter of a wafer based on the above-mentioned requirements, to facilitate the stable supply of an electrode plate for plasma etching, and to reduce the etching rate in the wafer surface. An object of the present invention is to provide a plasma etching electrode plate and a plasma etching apparatus which can improve uniformity.

[0015]

Means for Solving the Problems To achieve the above object, the present inventors provide a plasma etching electrode plate made of polycrystalline silicon for an electrode main body exposed to plasma and a carbon material as a mounting part. It has been found that the object of the present invention has been achieved, and the present invention has been completed.

That is, the present invention relates to a disk-shaped electrode plate for plasma etching, comprising: an electrode body portion exposed to plasma; and a mounting portion provided outside the electrode body. The present invention relates to an electrode plate for plasma etching, wherein an electrode body portion is made of polycrystalline silicon, and the mounting portion is made of glassy carbon or a glassy carbon-coated carbon material.

The present invention also relates to a parallel plate type plasma etching apparatus in which an upper electrode and a lower electrode are provided in a vacuum vessel at an interval, wherein a disk-shaped plasma etching electrode used for the upper electrode is provided. A plate having an electrode body portion exposed to plasma and a mounting portion provided outside the electrode body, wherein the electrode body portion is made of polycrystalline silicon, and the mounting portion is made of glassy carbon or glassy carbon. The present invention relates to a plasma etching apparatus comprising a coated carbon material.

[0018]

According to the present invention, advantages of polycrystalline silicon, such as low dust generation and ease of plasma control, are utilized in the electrode body. In addition, since the mounting portion is made of glassy carbon or a glassy carbon-coated carbon material, the deformation caused by depletion of the silicon in the central portion of the plasma can be absorbed by the slip of the coupling portion with the outer peripheral portion. The amount can be reduced. Therefore, the distance between the electrode plate and the silicon wafer to be etched can be kept substantially constant over the entire surface. As a result, the uniformity of the etching rate in the wafer surface is ensured, and an electrode plate for plasma etching that can easily cope with an increase in diameter can be provided at relatively low cost.

In addition, since the plasma irradiating portion and the mounting portion are separated from each other, the influence of the cooling effect of the mounting portion is suppressed, and a temperature difference is less likely to occur in a portion where the electrode plate is used (a portion corresponding to a wafer). As a result, the uniformity of the etching rate is improved.

According to the present invention, furthermore, by forming the electrode plate mounting portion from high-purity glassy carbon or glassy carbon-coated carbon material, the metal generated when another material such as aluminum is used is used. It does not lower the yield of semiconductor manufacturing due to contamination.

The raw material of the glassy carbon used in the present invention is not particularly limited, but a thermosetting resin such as a phenol resin, an epoxy resin, a melamine resin, a furan resin or a mixed resin thereof is used.

As the base material of the glassy carbon-coated carbon material, all general carbon materials produced from pitch, tar, natural graphite and the like can be used.

The ash content of the electrode mounting portion made of glassy carbon or a glassy carbon-coated carbon material is preferably 20 ppm or less, more preferably 10 ppm or less, in order to eliminate the influence of metal contamination such as iron and copper. Ash content is measured by the graphite ash measurement method of JIS.

The electrode plate for plasma etching of the present invention comprises:
The plasma irradiating section stably supplies an etching electrode plate using polycrystalline silicon having excellent etching characteristics, and also makes the temperature distribution of the portion where the electrode is used (corresponding to the wafer) uniform, resulting in in-plane etching of the wafer. This has the effect of improving the uniformity of the rate.

Hereinafter, the electrode plate for plasma etching of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an electrode plate 6 for plasma etching which is an example of the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is an enlarged view of a main part of FIG. The electrode plate for plasma etching 6 has an electrode body portion 61 that receives irradiation of plasma, and a mounting portion 63 provided outside the electrode body portion 61. The electrode body portion 61 is made of polycrystalline silicon, and the mounting portion 6
Reference numeral 3 is made of glassy carbon or a glassy carbon-coated carbon material. Both are combined using step 66,
They are mutually fixed by a fixed resin seal 65. The electrode main body 61 is provided with a gas blowing hole 62 for dispersing the etching gas in a shower shape. On the other hand, the mounting portion 63 is provided with a mounting hole 63 as a part of the upper electrode for mounting and fixing the plasma etching electrode plate 6 in the plasma etching apparatus.

By separately configuring the electrode main body portion (plasma irradiated portion) and the mounting portion as described above, the influence of the cooling effect of the mounting portion is suppressed, and the electrode plate using portion (a portion corresponding to a wafer) is provided. A temperature difference hardly occurs, and as a result, the uniformity of the etching rate is improved.

Further, by forming the electrode plate mounting portion 63 from high-purity glassy carbon or glassy carbon-coated carbon material, it is possible to manufacture semiconductors due to metal contamination caused when other materials such as aluminum are used. There is no such thing as lowering the yield.

The size of the plasma etching electrode plate 6 is determined according to the size of the silicon wafer to be etched. The size of the silicon wafer to be etched is 6
For inches to 12 inches, outer diameter is 200 to 400m
m and a thickness of 3 to 10 mm are preferable. The size of the electrode body portion made of polycrystalline silicon is almost the same as the size of the silicon wafer to be etched, or larger in the range of 0 to 50 mm as compared with this, so that etching can be performed uniformly and the electrode is hardly deformed. So preferred, 6
For inches to 12 inches, the outer diameter is 150 to 30
The one with 0 mm is preferable. Further, it is preferable that the difference between the outer diameter of the electrode main body portion and the outer diameter of the mounting portion is 20 to 100 mm, since the electrode is less likely to be deformed. It is preferable that 8 to 24 mounting holes for mounting the electrodes are provided on the outer peripheral portion. The size of the gas blowing holes for dispersing the etching gas in a shower shape varies depending on the etching conditions and the like, but the hole diameter is preferably 0.3 to 2.0 mm, and the number of holes is 1
00 to 300 are preferred.

[0029]

The present invention will be described below in detail with reference to examples. (Example 1) As the electrode plate 6 for plasma etching, a 5 mm thick, 8 mm
Inch (φ200 mm) polycrystalline silicon (manufactured by Sumitomo Citix Co., Ltd.), glassy carbon (outer diameter φ2
80 mm, thickness 5 mm, manufactured by Hitachi Chemical Co., Ltd., trade name P
XG-3S) was used. The ash content of the attachment part was 3 ppm.

The electrode body portion 61 and the mounting portion 63 are arranged as shown in FIG.
As described above, the combination is fixed by providing a step 66 on the outer periphery of the polycrystalline silicon and the inner periphery of the glassy carbon. 2 and 3 in order to fix the relative positions of the mounting hole 63 provided in the mounting portion and the gas hole 62 (633 Φ0.5 mm holes with a pitch of 7 mm) formed in the plasma irradiation section. As described above, the resin-made seal 65 was stuck at several places, and the central part and the outer peripheral part were fixed.

The portion where the resin seal 65 is to be adhered is positioned so as not to interfere with the gas holes 62, and a concave portion having a thickness not less than the thickness of the seal (0.5 mm) is provided so that the adhesion between the electrode plate 6 and the back plate is not impaired. did.

Using this electrode, an 8-inch wafer was etched, and the uniformity of the etching rate in the wafer surface was measured. For the etching of the wafer, trifluoromethane was used as a reactive gas, and the uniformity of the etching rate was measured at a total of 17 points at the center, middle, and outer periphery of the wafer, and the maximum (max) and small (min) points of the etching rate were measured. ) Was calculated by the following equation. Table 1 shows the evaluation results. Etching rate = ((max−min) / (max + min)) × 100
(%)

(Embodiment 2) 8 inches (φ200 mm) of polycrystalline silicon (manufactured by Sumitomo Citix Co., Ltd.) for the electrode body portion 61 (plasma irradiated portion), and isotropic graphite coated with glassy carbon for the mounting portion 63 Using the material (manufactured by Hitachi Chemical Co., Ltd., trade name: PD-600), an electrode plate for plasma etching having the same size as in Example 1 was prepared. The ash content of the attachment was 10 ppm.

The coating of the glassy carbon is performed by using isotropic graphite material and furan resin (Hitafuran V, manufactured by Hitachi Chemical Co., Ltd.).
F302) was stirred and mixed with p-toluenesulfonic acid, spray-coated, and cured at 90 ° C. for 5 hours.
Thereafter, the temperature was raised to 900 ° C. at 1 ° C./hour, and further increased to 5 ° C./hour.
The graphitization treatment was performed at a maximum of 2800 ° C. for a long time.

The combination of the electrode body portion 61 and the mounting portion 63 was fixed in the same manner as in the first embodiment.

Using this electrode, the uniformity of the etching rate was measured in the same manner as in Example 1. Table 1 shows the evaluation results.

Comparative Example 1 An integrated single-crystal silicon electrode plate of the same size as in Example 1 (manufactured by Hitachi Chemical Co., Ltd.)
And the uniformity of the etching rate was measured in the same manner as in Example 1. Table 1 shows the evaluation results.

Comparative Example 2 Using a glassy carbon electrode plate (manufactured by Hitachi Chemical Co., Ltd.) having the same size as in Example 1, the etching rate uniformity was measured in the same manner as in Example 1.
Table 1 shows the evaluation results.

[0039]

[Table 1]

As is clear from Table 1, according to the present invention, the uniformity of the etching rate is better than that of the comparative example. This is because the advantages of polycrystalline silicon such as low dust generation and ease of plasma control are utilized in the electrode body. In addition, since the mounting portion is made of glassy carbon or a glassy carbon-coated carbon material, the deformation caused by depletion of the silicon in the central portion of the plasma can be absorbed by the slip of the coupling portion with the outer peripheral portion. This is also because the distance between the electrode plate and the silicon wafer to be etched can be kept substantially constant over the entire surface because the amount can be reduced. As a result, the uniformity of the etching rate in the wafer surface is ensured, and an electrode plate for plasma etching that can easily cope with an increase in diameter can be provided at relatively low cost.

[0041]

As described above, when the etching process is performed by using the electrode plate for plasma etching according to the present invention, nonuniformity of the etching rate in the plane of the wafer hardly occurs and the uniformity of the etching rate is improved. is there.

Further, since the silicon in the plasma irradiated portion is almost the same as the size of the target wafer, the etching electrode plate can be supplied stably.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electrode plate for plasma etching according to one embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a view showing a longitudinal section of a conventional plasma etching apparatus.

[Explanation of symbols]

2 ... upper electrode, 3 ... lower electrode, 4 ... silicon wafer, 5
... back plate, 6 ... electrode plate for plasma etching,
Reference numeral 61: electrode body portion, 62: gas blowing hole, 63: mounting portion, 65: fixed resin seal, 66: step

Claims (2)

[Claims] 1. A disk-shaped electrode plate for plasma etching, comprising: an electrode body portion exposed to plasma; and a mounting portion provided outside the electrode body.
An electrode plate for plasma etching, wherein said electrode body portion is made of polycrystalline silicon and said mounting portion is made of glassy carbon or glassy carbon-coated carbon material. 2. A parallel plate type plasma etching apparatus in which an upper electrode and a lower electrode are provided at an interval in a vacuum vessel, wherein a disk-shaped plasma etching electrode plate used for the upper electrode is a plasma etching apparatus. An electrode body portion exposed to the electrode body and a mounting portion provided outside the electrode body, wherein the electrode body portion is made of polycrystalline silicon, and the mounting portion is made of glassy carbon or glassy carbon-coated carbon material. A plasma etching apparatus, comprising: