JPH0570956A - Microwave absorption plasma treating device having magnetic field - Google Patents

Abstract

PURPOSE:To obtain the ECR microwave plasma treating device which can subject a sample substrate to a uniform plasma treatment by uniformizing the gaseous pressure distribution in a plasma forming chamber to uniformize plasma densities. CONSTITUTION:A gas distributor 10 for an annular plasma chamber introduced with treating gases through a treating gas introducing pipe 4a is attachably and detachably mounted to the position of the corner part which is the dead angle of a microwave introducing window 2 on the inside wall surface of the plasma forming chamber 1b of a vacuum vessel 1. The gas distributor 10 has a sectional space part 10a as the gas pool larger than the sectional space part of the treating gas introducing pipe 4a with the inside wall surface of the above- mentioned corner part of the plasma forming chamber 1b and is provided with plural pieces of treating gas ejection holes 10b having the hole diameter size smaller than the inside diameter of the treating gas introducing pipe 4a at prescribed intervals in its circumferential direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron cyclotron resonance (electron cyclotron resonance) by a magnetic field and microwave energy.
lotron Resonance, hereinafter referred to as ECR. ) Is used to turn the processing gas into plasma, and the sample substrate such as a semiconductor substrate is irradiated with ions or radicals in the plasma to perform plasma processing such as etching, CVD (Chemical Vapor Deposition) and sputtering. More specifically, the present invention relates to a plasma processing apparatus, in which a processing gas is uniformly distributed in a plasma generation chamber so that a plasma density in the plasma generation chamber is made uniform and a uniform plasma treatment can be performed on a sample substrate. The present invention relates to a magnetic field microwave absorption plasma processing apparatus.

[0002]

2. Description of the Related Art Conventionally, as a typical plasma processing apparatus of this kind for performing plasma processing such as etching and CVD on a sample substrate by utilizing ECR plasma, there is shown a configuration explanatory view of FIG. A magnetic field microwave absorption plasma processing apparatus for etching a sample substrate is known.

In FIG. 4, reference numeral 51 is a vacuum container, and the vacuum container 51 is a chamber for forming a cylindrical space therein, and a sample chamber 51a is formed above the chamber 51a and communicates with the sample chamber 51a to form a cylindrical space. It has a plasma generation chamber 51b which is a chamber. A microwave introduction window 52 made of quartz glass is provided in the upper opening of the plasma generation chamber 51b so as to cover it, and a rectangular waveguide 53 is connected thereto.

A processing gas introduction pipe 54, a cooling water supply pipe 55a and a cooling water discharge pipe 55b are connected to the upper wall surface of the plasma generation chamber 51b of the vacuum chamber 51, and the processing gas is introduced into the plasma generation chamber 51b from above. While the gas is introduced through the processing gas introduction pipe 54, the inside of the peripheral wall of the plasma generation chamber 51b is supplied through the cooling water supply pipe 55a and the cooling water discharge pipe 55b.
It is designed to be cooled by cooling water discharged through.

Around the plasma generation chamber 51b of the vacuum chamber 51, annular magnetic coils 56 and 57 for generating a magnetic field having an intensity satisfying the ECR condition are arranged in the plasma generation chamber 51b. An exhaust port 58 is provided in the lower portion of the sample chamber 51a of the vacuum container 51, and the sample substrate W is held on a sample table 59 arranged in the sample chamber 51a.

In the magnetic field microwave absorption plasma processing apparatus configured as described above, the plasma generation chamber 51b
And the sample chamber 51a is exhausted by a vacuum pump (not shown).
Then, the processing gas is introduced into the plasma generation chamber 51b through a processing gas introduction pipe 54 from a gas introduction port at one location above the plasma generation chamber 51b, and a low gas pressure of about 10 ^-2 Pa to several Pa is obtained. A microwave having a frequency of 2.45 GHz from a microwave source (not shown) is passed through the waveguide 53 and the microwave introduction window 52 to form the plasma generation chamber 51b.
Introduced into the inside, and ECR by magnetic coils 56 and 57
Applying a magnetic flux density of 875 Gauss, which is the condition, plasma generation chamber
The processing gas is turned into plasma in 51b.

The generated plasma is supplied in the form of plasma flow onto the sample table 59 in the sample chamber 51a along the magnetic field.
In this way, the sample substrate W is etched. The process gas is introduced into the plasma generation chamber 51b through one gas introduction port or several gas introduction ports that are simply branched pipes. Regarding this, the CV is applied to the sample substrate W by using the ECR plasma.
The same applies to D and an apparatus for performing plasma processing of sputtering.

[0008]

[Problems to be Solved by the Invention] As described above, 10 ^-2 Pa
Plasma treatment by ECR plasma is performed at a low gas pressure of about several Pa. At such a low gas pressure, the process gas flow has a small number of molecules, so the Knudsen number (Kn
udsen number) Molecular flow region defined by K (K> 1)
The gas molecules of the processing gas introduced from the gas inlet are distributed in the plasma generation chamber while repeatedly colliding with the inner wall surface of the plasma generation chamber with almost no collision between the gas molecules. become.

However, in the conventional magnetic field microwave absorption plasma processing apparatus, the processing gas is introduced into the plasma generation chamber from one gas introduction port or several gas introduction ports which are simply branched pipes. Therefore, when the plasma processing is performed by increasing the exhaust capacity to prevent the reattachment of impurities to the sample substrate W, the collision between the gas molecules of the processing gas and the inner wall surface of the plasma generation chamber is not sufficiently repeated. As a result of being exhausted, the distribution of the processing gas in the plasma generation chamber becomes non-uniform as shown in FIG. Even when the pipe is simply branched to introduce the process gas from two gas introduction ports, as shown in FIG. 6, a difference in conductance occurs due to a difference in pipe length, so that a non-uniform gas is generated. Be distributed. Therefore, the distribution of gas pressure in the plasma generation chamber becomes non-uniform,
As a result, the plasma density is not made uniform, and there is a problem in terms of plasma processing uniformity.

The present invention has been made in order to solve the above-mentioned conventional problems. By providing a gas distributor in the plasma generation chamber so that the processing gas is uniformly distributed, It is an object of the present invention to provide a magnetic field microwave absorption plasma processing apparatus capable of uniformizing plasma density in a plasma generation chamber and performing uniform plasma processing on a sample substrate.

[0011]

In order to achieve the above object, a magnetic field microwave absorption plasma processing apparatus according to the present invention comprises a vacuum container having a plasma generation chamber into which a processing gas is introduced through a processing gas introduction pipe. A plasma generating chamber, a magnetic field generating unit for generating a magnetic field in the plasma generating chamber, a microwave introducing unit for introducing a microwave into the plasma generating chamber, and a sample stage for holding a sample substrate in the vacuum container. In a magnetic field microwave absorption plasma processing apparatus that performs plasma processing such as etching, CVD, and sputtering on a sample substrate by establishing an electron cyclotron resonance condition in the chamber and converting the processing gas into plasma, in the plasma generation chamber, At the position where the microwave introduced into the plasma generation chamber does not hit, the process gas guide is placed. The processing gas has a cross-sectional space portion larger than the cross-sectional space portion of the tube and a plurality of processing gas ejection holes having a hole diameter size smaller than the inner diameter of the processing gas introduction pipe, and the processing gas is introduced through the processing gas introduction pipe. It is characterized in that a gas distributor is attached in a replaceable manner.

[0012]

In the plasma processing apparatus having the above structure, when the processing gas is introduced into the gas distributor through the processing gas introducing pipe, the gas distributor has a cross-sectional space portion larger than the cross-sectional space portion of the processing gas introducing pipe. Therefore, the cross-sectional space portion acts as a gas reservoir. Therefore, in the processing gas introduced into the gas distributor, the gas molecules repeatedly collide with the wall surface and are uniformly diffused in the gas reservoir space portion including the cross-sectional space portion. The processing gas uniformly diffused in the gas reservoir space is uniformly ejected from a plurality of processing gas ejection holes having a hole diameter size smaller than the inner diameter of the processing gas introduction pipe. As a result, since the processing gas is uniformly introduced into the plasma generation chamber, the distribution of gas pressure in the plasma generation chamber becomes uniform, and the density of plasma generated in the plasma generation chamber becomes uniform.

Further, the gas distributor is located in a position inside the plasma generation chamber where microwaves introduced into the plasma generation chamber do not hit, for example, at a position which is a blind spot with respect to a microwave introduction window for introducing microwaves. Since it is attached, microwaves are introduced into the plasma generation chamber without any trouble.

The gas distributor is replaceably attached so that the number of process gas ejection holes, the shape and direction of the process gas, and the size of the cross-sectional space can be changed. It can be appropriately selected and attached depending on the type of plasma treatment, the object to be plasma treated, and the like.

[0015]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is a configuration explanatory view of a magnetic field microwave absorption plasma processing apparatus for performing CVD using ECR plasma according to an embodiment of the present invention, and FIG. 2 is a plan view of a gas distributor for a plasma chamber shown in FIG. ..

In FIG. 1, reference numeral 1 denotes a vacuum container. The vacuum container 1 is a chamber for forming a columnar space therein, and a sample chamber 1a is formed above the sample chamber 1a and communicates with the sample chamber 1a to form a columnar space. It has a plasma generation chamber 1b which is a chamber. A microwave introduction window 2 made of quartz glass is provided in the upper opening of the plasma generation chamber 1b so as to cover it, and a rectangular waveguide 3 is connected thereto. The waveguide 3 and the microwave introduction window 2 constitute a microwave introduction means for introducing a microwave (frequency 2.45 GHz) from a microwave source (not shown) into the plasma generation chamber 1b.

A first process gas introduction pipe 4a, a cooling water supply pipe 5a and a cooling water discharge pipe 5b are connected to the upper wall surface of the plasma generation chamber 1b of the vacuum chamber 1 while the microwave of the plasma generation chamber 1b is connected. An annular plasma chamber gas distributor 10 to be described later is replaceably (detachably) attached to the inner wall surface of the corner portion on the introduction window 2 side. The first processing gas (for example, O ₂ gas) is introduced into the plasma generation chamber 1b via the first processing gas introduction pipe 4a and the plasma chamber gas distributor 10, and the inside of the peripheral wall of the plasma generation chamber 1b is The cooling water discharge pipe supplied through the cooling water supply pipe 5a
It is designed to be cooled by the cooling water discharged through 5b.

Around the plasma generation chamber 1b of the vacuum container 1, an annular magnetic coil 6 as a magnetic field generating means for generating a magnetic field having an intensity (magnetic flux density 875 Gauss) satisfying the ECR condition in the plasma generation chamber 1b, 7 are arranged. Further, an exhaust port 8 is provided in the lower portion of the sample chamber 1a of the vacuum container 1, and the sample substrate W is held on a sample table 9 which also serves as an electrode and is arranged in the sample chamber 1a.

Further, while the second processing gas introducing pipe 4b is connected to the peripheral wall of the sample chamber 1a, the inner wall surface of the corner portion of the sample chamber 1a on the plasma generation chamber 1b side has an annular sample chamber described later. A gas distributor 11 is replaceably (detachably) attached. It is installed. Second
The processing gas (for example, SiH ₄ gas) is introduced into the sample chamber 1a through the second processing gas introduction pipe 4b and the sample chamber gas distributor 11.

As shown in FIGS. 1 and 2, the plasma chamber gas distributor 10 has an annular shape having a vertical wall portion, an inclined wall portion and a horizontal wall portion, and has a plasma generating chamber 1b. A peripheral portion of a vertical wall portion having a surface parallel to the central axis of the (vacuum container 1) and a horizontal wall portion having a surface perpendicular to the central axis is a corner of the plasma generation chamber 1b on the microwave introduction window 2 side. While being fixed to the inner wall surface of the portion, a gas reservoir space portion 10a having a cross-sectional space portion larger than the cross-sectional space portion of the first processing gas introduction pipe 4a is provided between the inner wall surface of the corner portion and the inner wall surface of the corner portion, and its inclination A plurality of processing gas ejection holes 10b having a hole diameter size smaller than the inner diameter of the first processing gas introduction pipe 4a are provided in the wall portion at predetermined intervals in the circumferential direction. In this embodiment, the processing gas ejection hole 10
In b, the direction of the hole is the plasma generation chamber 1b (vacuum container 1).
It is the direction intersecting with the central axis line of.

Further, as shown in FIG. 1, the sample chamber gas distributor 11 has a vertical wall portion and a horizontal wall portion and has an annular shape, and the peripheral portions of both wall portions are sample chambers. A cross-sectional space portion larger than the cross-sectional space portion of the second processing gas introduction pipe 4b is fixed to the inner wall surface of the corner portion of the plasma generation chamber 1b side of 1a along with the inner wall surface of the corner portion. In addition to having a gas reservoir space portion 11a, a plurality of processing gas ejection holes 11b having a hole diameter size smaller than the inner diameter of the second processing gas introducing pipe 4b are provided in the vertical wall portion at a predetermined interval in the circumferential direction. .. In this embodiment, the processing gas ejection hole 11b is oriented so that the direction of the hole is the sample chamber 1a.
The direction intersects with the central axis of the (vacuum container 1).

In the above-structured magnetic field microwave absorption plasma processing apparatus, when the first processing gas is introduced into the plasma chamber gas distributor 10 through the first processing gas introducing pipe 4a, the gas distributor 10 is introduced into the gas distributor 10. The introduced first processing gas has its gas molecules repeatedly colliding with the inner wall surface of the corner portion of the plasma generation chamber 1b and the surface of the gas distributor 10 opposite thereto, and is uniformly diffused in the gas storage space portion 10a. .. The first processing gas uniformly diffused in the gas reservoir space 10a is evenly ejected from the respective processing gas ejection holes 10b.

As a result, since the first processing gas is radially and uniformly introduced into the plasma generation chamber 1b from its peripheral portion, the gas pressure distribution in the plasma generation chamber 1b becomes uniform,
The density of the plasma generated in the plasma generation chamber 1b is made uniform. Similarly, the sample chamber gas distributor 11 radially and uniformly introduces the second processing gas into the sample chamber 1a from its peripheral portion. In this way, the density of the plasma generated in the plasma generation chamber 1b can be made uniform,
It is possible to form a thin film having a uniform film thickness on the sample substrate W as compared with the conventional one.

FIG. 3 shows an EC according to another embodiment of the present invention.
It is a structure explanatory view of a magnetic field microwave absorption plasma processing apparatus which performs etching using R plasma. In the figure, 21 is a vacuum container that also serves as a plasma generation chamber and a sample chamber, 22 is a microwave introduction window, 23 is a waveguide, 24 is a processing gas introduction pipe through which chlorine gas, for example, is supplied as a processing gas, and 25a.
Is a cooling water supply pipe, 25b is a cooling water discharge pipe, 26 and 27 are Helmholtz type magnetic coils, 28 is an exhaust port of a vacuum container, and 29 is a sample table which also serves as an electrode for holding the sample substrate W. 30
Is a gas distributor that is replaceably (detachably) attached to the inner wall surface of the corner portion of the vacuum container 1 on the microwave introduction window 22 side. The gas distributor 30 has the same configuration as the plasma chamber gas distributor 10 described above.

Also in the above-structured magnetic field microwave absorption plasma processing apparatus, since the processing gas is uniformly introduced radially into the plasma generation space of the vacuum container 21 from its peripheral portion by the gas distributor 30, the vacuum container
The gas pressure distribution in the plasma generation space 21 becomes uniform, and the density of the generated plasma becomes uniform. As a result, it is possible to perform uniform etching on the sample substrate W without lateral asymmetry in the outer peripheral portion of the substrate as compared with the conventional case.

As the shape of the gas distributor, in each of the above embodiments, an annular shape along the wall surface of the plasma generating chamber is illustrated, but the shape is not limited to this, and an appropriate length dimension may be used. The plasma distributor may be provided with a gas distributor at a mounting position which is not limited to the corner portion on the microwave introducing side of the plasma generating chamber illustrated in each of the above-mentioned embodiments, and is not limited to the microwave introducing window. It only needs to be a position that is a blind spot. Further, in the above-mentioned embodiment, an example of performing CVD and etching using ECR plasma has been described, but the magnetic field microwave absorption plasma processing apparatus according to the present invention is also applicable to those performing sputtering using ECR plasma. is there.

[0027]

The magnetic field microwave absorption plasma processing apparatus according to the present invention is a gas in which a processing gas is introduced through a processing gas introduction pipe to a position in the plasma generation chamber where microwaves introduced into the plasma generation chamber do not hit. -A distributor is replaceably attached, and this gas distributor has a cross-sectional space portion larger than the cross-sectional space portion of the processing gas introduction pipe and a plurality of processing gas ejection holes having a hole diameter size smaller than the inner diameter of the processing gas introduction pipe. It is supposed to have one.

Therefore, while microwaves can be introduced into the plasma generation chamber without any trouble due to the presence of the gas distributor, the cross-sectional space portion of the gas distributor acts as a gas reservoir and is introduced into the gas distributor. The gas molecules of the processing gas repeatedly collide with the wall surface and are uniformly diffused in the gas reservoir space portion including the cross-sectional space portion. The processing gas uniformly diffused in this gas reservoir space is uniformly ejected from each processing gas ejection hole, and the processing gas is uniformly introduced into the plasma generation chamber, so that the gas pressure distribution in the plasma generation chamber is uniform. Therefore, the density of plasma generated in the plasma generation chamber can be made uniform. As a result, according to the magnetic field microwave absorption plasma processing apparatus of the present invention, when performing plasma processing such as etching, CVD, and sputtering on the sample substrate, it is possible to perform more uniform plasma processing than in the past.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a magnetic field microwave absorption plasma processing apparatus for performing CVD using ECR plasma according to an embodiment of the present invention.

FIG. 2 is a plan view of the gas distributor for the plasma chamber shown in FIG.

FIG. 3 is a structural explanatory view of a magnetic field microwave absorption plasma processing apparatus for performing etching using ECR plasma according to another embodiment of the present invention.

FIG. 4 is a diagram illustrating the configuration of a conventional magnetic field microwave absorption plasma processing apparatus that performs etching using ECR plasma.

FIG. 5 is a diagram for explaining a conventional gas distribution state in a plasma chamber.

FIG. 6 is a diagram for explaining a gas distribution state due to a conventional pipe branch in the plasma chamber.

[Explanation of symbols]

1, 21 ... Vacuum container 1a ... Sample chamber 1b ... Plasma generation chamber
2, 22 ... Microwave introduction window 3, 23 ... Waveguides 4a, 4b,
24 ... Process gas introduction pipe 5a, 25a ... Cooling water supply pipe 5b, 25b ... Cooling water discharge pipe 6, 7, 26, 27 ... Magnetic coil 8, 28 ... Exhaust port 9, 29 ... Sample stage 10 ... Plasma chamber gas・ Distributor 10a ... Gas reservoir space
10b ... Processing gas ejection hole 11 ... Sample chamber gas distributor 11a ... Gas reservoir space 11b ... Processing gas ejection hole 30 ... Gas distributor W ... Sample substrate

Claims (1)

[Claims] 1. A vacuum container having a plasma generating chamber into which a processing gas is introduced through a processing gas introducing pipe, a magnetic field generating means for forming a magnetic field in the plasma generating chamber, and a microwave for introducing a microwave into the plasma generating chamber. The sample substrate is provided with a wave introducing unit and a sample table for holding a sample substrate in the vacuum container, and an electron cyclotron resonance condition is established in the plasma generation chamber to turn the processing gas into plasma, thereby etching and CVD the sample substrate. In a magnetic field microwave absorption plasma processing apparatus that performs plasma processing such as sputtering, the cross-section space of the processing gas introduction pipe is larger than the cross-sectional space of the processing gas introduction pipe at a position in the plasma generation chamber where microwaves introduced into the plasma generation chamber do not hit. A hole diameter dimension that has a cross-sectional space and is smaller than the inner diameter of the processing gas introduction pipe. 2. A magnetic field microwave absorption plasma processing apparatus having a plurality of processing gas ejection holes each having the above-mentioned, and a gas distributor into which the processing gas is introduced through the processing gas introduction pipe are exchangeably attached.