JPH08185997A - Microwave plasma device - Google Patents

Abstract

PURPOSE: To prevent the deformation or breakage due to thermal expansion of an adhesion preventing cylinder in a microwave plasma device having a prescribed configuration and improve the reproducibility of plasma treatment by holding the adhesion preventing cylinder by a specified means. CONSTITUTION: This microwave plasma device has a plasma generating chamber 3, a microwave guide window 2 for guiding a microwave into the plasma generating chamber 3, and an adhesion preventing cylinder 7 for covering the inner wall of the plasma generating chamber 3 provided on the inner part of the plasma generating chamber 3. In this device, the lower end of the adhesion preventing cylinder 7 is held by an elastic adhesion preventing cylinder holding means 8 to make the clearance between the adhesion preventing cylinder 7 and the microwave guide window 3 constant. Consequently, the removal and replacement of the adhesion preventing cylinder 7 are also facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma device used for etching a semiconductor element substrate, forming a thin film and the like.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, plasma is generated by introducing microwaves into a vacuum vessel under reduced pressure, and the surface of a sample is irradiated with this plasma to perform etching, thin film formation, and other processing. A microwave plasma device is used.

FIG. 9 is a schematic vertical sectional view showing a microwave plasma device utilizing electron cyclotron resonance excitation, which is one type of microwave plasma device. In the figure, 3 is a plasma generation chamber, and a microwave introduction port 5 is opened at the center of the upper part of the plasma generation chamber 3 and is vacuum-sealed by a microwave introduction window 2 such as quartz. A waveguide 1 whose other end is connected to a microwave oscillator (not shown) is attached to the microwave introduction port 5. The plasma generation chamber wall 4 has a double structure and is provided with a flow chamber 6 for allowing cooling water to flow therethrough.

A sample chamber 10 is connected to the lower side of the plasma generation chamber 3, and a sample table 14 is arranged in the sample chamber 10. On the sample table 14, a wafer or the like is placed. The sample S is detachably mounted by means such as electrostatic adsorption. Further, a gas inlet pipe 12 is connected to the sample chamber wall 11, and an exhaust port 13 is connected to an exhaust device (not shown).
Is provided.

An exciting coil 9 is provided outside the plasma generating chamber 3. Inside the plasma generation chamber 3, an anti-sticking cylinder 7 covering the upper wall and the side wall is provided in the lower wall of the plasma generation chamber so that each wall of the plasma generation chamber 3 is not directly irradiated with the generated plasma. It is attached by means of the attachment prevention cylinder holding means 8. This point will be described later.

FIG. 10 is an enlarged view of the plasma generating chamber 3 portion. The deposition-inhibiting cylinder 7 faces the microwave introduction window 2 and covers the upper wall of the plasma generation chamber 3 and the upper surface portion 7a and the plasma generation chamber 3
And a cylindrical portion 7b that covers the side wall of the upper surface portion 7a.
Is usually made of quartz or alumina which is a microwave transmitting material, and the cylindrical portion 7b is usually made of quartz, alumina or aluminum. The upper surface portion 7a and the tubular portion 7b may be integrally formed. The deposition-inhibiting cylinder 7 is mounted on the deposition-inhibiting cylinder holding ring 8a, and
It is fixedly held on the plasma generating chamber wall 4 by a bolt 8c through a hole 8b opened in the.

A method of performing etching using the microwave plasma device having the above-described structure will be described (see FIG. 9).

First, the inside of the plasma generating chamber 3 is evacuated to a predetermined pressure, and then a gas for etching is introduced from the gas introduction pipe 12 to a predetermined pressure. Then, the microwave is introduced into the plasma generation chamber 3 through the microwave introduction window 2 while forming a magnetic field by the exciting coil 9. Then, plasma is generated by electron cyclotron resonance excitation in the plasma generation chamber. The generated plasma is formed by the exciting coil 9 and is projected onto the sample S in the sample chamber 10 by the divergent magnetic field whose magnetic field decreases toward the sample chamber 10, and the sample S is etched.

However, in the microwave plasma device having the above-mentioned structure, when microwaves are introduced to generate plasma for a long time, the deposition-preventing cylinder 7 is heated by the plasma and a dimensional change occurs due to thermal expansion. There is a problem that the gap between 7a and the microwave introduction window 2 changes, which changes the state of plasma generation and deteriorates the reproducibility of plasma processing.

On the other hand, the present applicant provides a gap holding member 21 between the upper surface portion 7a of the deposition-inhibitory cylinder and the upper wall of the plasma generation chamber 3 as shown in FIG. There has been proposed a device for maintaining the gap between the portion 7a and the microwave introduction window 2 at a predetermined value (see Japanese Patent Laid-Open No. 6-252100).

[0011]

However, a gap holding member 21 is provided in the gap between the upper surface portion 7a of the deposition-inhibiting cylinder and the upper wall of the plasma generation chamber 3 described in JP-A-6-252100.
In the apparatus described in the publication, the attachment-preventing cylinder 7 is held by placing the lower end of the tubular portion 7b of the attachment-preventing cylinder on the attachment-preventing cylinder holding ring 8a.
Since the deposition-prevention cylinder holding ring 8a is fixed to the lower wall of the plasma generation chamber wall 4 with the bolt 8c, when the plasma is generated for a long time, the deposition-prevention cylinder 7 is thermally expanded and deformed by plasma heating. In the extreme case, there is a problem that it is cracked or the thermal barrier expansion of the deposition-inhibiting barrel 7 deforms the deposition-inhibiting barrel holding ring 8a, making it difficult to remove the deposition-proof barrel 7 when it is replaced.

It is an object of the present invention to provide a microwave plasma device which improves the reproducibility of plasma processing and does not cause deformation or crack damage due to thermal expansion of the deposition-inhibiting cylinder or removal of the deposition-inhibiting cylinder. .

[0013]

According to the present invention, there is provided a plasma generation chamber, a microwave introduction window for introducing a microwave into the plasma generation chamber, and an inside wall of the plasma generation chamber for covering an inner wall of the plasma generation chamber. A microwave plasma device including a cylinder, wherein the deposition-proof cylinder is held at its lower end by an elastic deposition-proof cylinder holding means, and the gap between the deposition-proof cylinder and the microwave introduction window is constant. In addition, there is a space larger than the thermal expansion amount of the deposition-inhibiting cylinder between the lower end of the deposition-inhibiting cylinder and the sample table, and the deposition-inhibiting cylinder is held in the plasma generation chamber near the upper end thereof. It is held by means.

[0014]

In the device of the present invention, since the deposition-preventing cylinder is held at its lower end by the elastic deposition-protection-cylinder holding means, the thermal expansion of the deposition-prevention cylinder during plasma generation while the upper end of the deposition-prevention cylinder is fixed. It can be absorbed by expansion and contraction of the elastic part. This allows
The gap between the deposition shield and the microwave introduction window can be maintained at a constant value, which improves the reproducibility of plasma generation and also prevents deformation of the deposition shield or damage to the breakage or deformation of the deposition shield holding ring. It is possible to prevent the attachment-preventing cylinder from being difficult to remove due to the above.

Further, since the deposition-proof cylinder is held in the plasma generating chamber near the upper end thereof by the deposition-proof cylinder holding means, the expansion due to the thermal expansion of the deposition-proof cylinder appears at the lower end of the deposition-proof cylinder and becomes There is almost no influence of elongation on the gap with the microwave introduction window. Also, since the lower end of the deposition-inhibiting cylinder is not fixed and there is a sufficient space between the lower end of the deposition-inhibiting cylinder and the sample table, which is more than the amount of thermal expansion of the deposition-inhibiting cylinder, the lower end of the deposition-inhibiting cylinder is not heated. Even if it expands due to expansion, there is no risk of deformation or breakage of the deposition-prevention cylinder. Further, since the deposition-prevention tube holding ring is not used, it is not difficult to remove the deposition-prevention tube due to the deformation of the ring.

[0016]

Embodiments of the microwave plasma apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a portion of a plasma generation chamber 3 of the microwave plasma apparatus of the first embodiment. The deposition-inhibiting cylinder 7 is composed of a cylindrical portion 7b made of aluminum and an upper surface portion 7a made of alumina. The upper end portion of the cylindrical portion 7b is formed to have a step with an outer periphery protruding. It is configured to hold. The deposition-prevention tube 7 is fixed to the lower wall of the plasma generation chamber wall 4 by the deposition-prevention tube holding means 8 so that the upper end of the tubular portion 7b contacts the upper wall of the plasma generation chamber 3. There is.

The attachment-preventing cylinder holding means 8 and the method for holding the attachment-preventing cylinder will be described in detail. FIG. 2 shows the attachment prevention cylinder holding portion A in FIG.
4 is an enlarged view of FIG. 4, and FIG. 4 is a schematic cross-sectional view of the BB ′ cross section as seen from the direction of the arrow, and FIG. 3 is a protection cylinder before being attached to the lower wall of the plasma generation chamber wall 4 by the bolt 8c. It is a schematic diagram of holding means 8.

As shown in FIG. 3, the attachment-prevention cylinder holding means 8 is mainly constituted by an aluminum attachment-prevention cylinder holding ring 8a in which four leaf springs 8d having bolt holes 8e are arranged. Both ends of the leaf spring 8d are fixed to the deposition-inhibiting cylinder holding ring 8a by bolts 8f. The hole 8b is
When attaching the deposition-inhibitory cylinder holding ring 8a to the lower wall of the plasma generation chamber wall 4 with the bolt 8c, the deposition-proof cylindrical holding ring 8a
It is for attaching the bolt 8c from below.

As shown in FIG. 2, the cylinder portion 7b of the deposition-inhibiting cylinder is placed on the inner peripheral portion of the deposition-inhibiting cylinder holding ring 8a, and
The attachment-prevention cylinder holding ring 8a is attached to the leaf spring 8 by a bolt 8c.
It is fixed to the lower wall of the plasma generation chamber wall 4 through a bolt hole 8e opened in d. This fixing is performed so that the upper end of the tubular portion 7b of the deposition-inhibiting cylinder contacts the upper wall of the plasma generation chamber 3.

As shown in FIG. 4, the deposition-prevention tube holding ring 8a on which the deposition-prevention tube is placed is lifted up by a bolt 8c fixed to the lower wall of the plasma generation chamber wall 4 via a leaf spring 8d. It is in the state of being held. Therefore, when the tubular portion 7b of the deposition-inhibitory barrel expands and extends, a force is applied downward to the deposition-inhibitory barrel holding ring 8a, but the leaf spring 8d
Can be absorbed by the deflection of the.

That is, with the above-mentioned structure, even when plasma is generated for a long time, the deposition-inhibiting cylinder 7 is held by the deposition-inhibiting cylinder holding means 8 so that the upper end of the tubular portion 7b contacts the upper wall of the plasma generating chamber 3. Therefore, the upper surface portion 7a of the protection cylinder is
The gap between the microwave introduction window 2 and the microwave introduction window 2 is kept constant at a length defined by the protruding length of the cylindrical portion 7b and does not change. Further, when the lower end of the tubular portion 7b extends downward due to the expansion of the tubular portion 7b of the deposition-inhibitory barrel due to plasma heating, the deflection of the leaf spring 8d causes the deposition-proof tubular holding ring 8a to move in the downward direction. No large force is applied to the cylinder and the attachment-prevention tube holding ring, and as a result, the deformation of the attachment-prevention tube and the deformation of the attachment-prevention tube holding ring are prevented.

It was confirmed by the apparatus of this embodiment that the reproducibility of the plasma treatment and the deformation of the deposition-prevention tube and the deformation of the deposition-prevention tube holding ring were not generated by long-time plasma generation by Ar gas plasma.

A coil-shaped spring may be used instead of the leaf spring to supply the elastically pushing force. FIG. 5 shows an example of this, and the attachment-preventing cylinder holding ring 8a
A coil-shaped spring 8g is provided between the support plate 8h and the support plate 8h such that both ends of the spring are fixed. The plasma generation chamber wall is formed by a bolt 8c through a bolt hole 8i formed in the support plate 8h. 4 is fixed to the lower wall. In this case, the attachment prevention cylinder holding ring 8a includes the support plate 8h and the coiled spring 8
It is held so as to be lifted up via g.
As in the previous embodiment, when the tubular portion of the deposition-inhibitory barrel expands and expands, a downward force is applied to the deposition-proof barrel holding ring 8a, but this can be absorbed by the extension of the coiled spring 8g.

FIG. 6 is a schematic sectional view of the plasma generating chamber 3 portion of the microwave plasma apparatus of the second embodiment. The deposition-inhibiting cylinder 7 is composed of a quartz cylindrical portion 7b and a quartz upper surface portion 7a, and the upper end portion of the cylindrical portion 7b is formed to have a step with an outer periphery protruding. It is configured to hold. In the present embodiment, the tubular portion 7 of the deposition-inhibitory cylinder
Instead of holding it at the lower end of b, it is fixed to the plasma generating chamber wall 4 near the upper end and the deposition-inhibiting cylinder 7 is suspended and held. In order to suspend the plasma generation chamber wall 4, four retaining projections 4c are provided toward the inside, and correspondingly, as shown in FIG. 7, also on the upper end portion of the cylindrical portion 7b of the deposition-inhibitory cylinder. Four protruding portions 7c for holding were provided toward the outside. As shown in FIG. 8, the attachment method is to push up the deposition-inhibiting cylinder 7 from the lower side, insert it into the plasma generation chamber 3, and rotate it so that the overhanging portion 7c of the deposition-inhibiting cylinder is the plasma generation chamber wall. Mount it on the protruding portion 4c of No. 4 and attach it. In this embodiment, there is nothing from the lower end of the deposition-inhibiting cylinder 7 to the sample table 14 that prevents thermal expansion of the tubular portion 7b of the deposition-inhibiting cylinder 7.

With the above structure, even when plasma is generated for a long time, the fixing point of the deposition-inhibiting cylinder 7 with the plasma generation chamber is near the upper end of the cylindrical portion 7b, so the cylindrical portion 7b of the deposition-inhibiting cylinder by plasma heating. Of the deposition-preventing cylinder mainly appears as the extension of the lower end of the tubular portion 7b of the deposition-preventing cylinder. rare. Further, since the deposition-preventing cylinder 7 is suspended and there is nothing from the lower end of the deposition-preventing cylinder 7 to the sample stand 14, even if the lower end of the tubular portion 7b of the deposition-preventing cylinder expands due to thermal expansion, There is no risk of deformation or breakage of the deposition-inhibiting cylinder 7.

Also in the apparatus of this embodiment, the reproducibility of the plasma treatment and the deformation and crack damage of the deposition-prevention cylinder are
It could be confirmed by long-time plasma generation by r gas plasma.

[0028]

As described above in detail, in the microwave plasma device of the present invention, the reproducibility of plasma processing is improved, and the deformation and crack damage due to the thermal expansion of the deposition-inhibiting cylinder or the removal of the deposition-inhibiting cylinder is difficult. Can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a plasma generation chamber portion of a microwave plasma device according to a first embodiment.

FIG. 2 is an enlarged view of an attachment-prevention cylinder holding portion A in FIG. 1 of the first embodiment.

FIG. 3 is a schematic diagram showing an attachment-preventing cylinder holding means 8 of the first embodiment.

FIG. 4 is a schematic cross-sectional view of an attachment-preventing cylinder holding portion when the BB ′ cross-section in FIG. 2 of the first embodiment is viewed from the arrow direction.

FIG. 5 is a schematic cross-sectional view of an attachment-preventing cylinder holding portion when the coiled spring of the first embodiment is used.

FIG. 6 is a schematic cross-sectional view showing a plasma generation chamber portion of the microwave plasma device according to the second embodiment.

FIG. 7 is a schematic view of an attachment-prevention cylinder according to a second embodiment.

FIG. 8 is a schematic diagram illustrating how to attach the deposition-inhibitory cylinder of the second embodiment.

FIG. 9 is a schematic cross-sectional view of a conventional microwave plasma device.

FIG. 10 is a schematic cross-sectional view showing a plasma generation chamber portion of a conventional microwave plasma device.

FIG. 11 is a schematic cross-sectional view showing a plasma generation chamber portion of another conventional microwave plasma device.

[Explanation of symbols]

 2 microwave introduction window 7 anti-stick cylinder 7a upper surface part of anti-stick cylinder 7b tubular part of anti-stick cylinder 8 anti-stick cylinder holding means 8a anti-stick cylinder holding ring 8b hole 8c bolt 8d leaf spring 8e bolt hole 8f bolt 8g coiled Spring 8h Support plate 8i Bolt hole

Claims (2)

[Claims] 1. A microwave plasma apparatus comprising: a plasma generation chamber; a microwave introduction window for introducing microwaves into the plasma generation chamber; and a deposition-inhibiting cylinder that covers the inner wall of the plasma generation chamber inside the plasma generation chamber. A microwave plasma apparatus, characterized in that the protection tube is held at its lower end by a protection tube holding means having elasticity, and the gap between the protection tube and the microwave introduction window is constant. . 2. A microwave plasma device comprising a plasma generation chamber, a microwave introduction window for introducing microwaves into the plasma generation chamber, and a deposition-inhibiting cylinder for covering the inner wall of the plasma generation chamber inside the plasma generation chamber. There is a space larger than the thermal expansion amount of the deposition-inhibiting cylinder between the lower end of the deposition-inhibiting cylinder and the sample table, and the deposition-inhibiting cylinder is held in the plasma generation chamber near the upper end thereof by the deposition-inhibiting cylinder holding means. A microwave plasma device characterized by being provided.