JPH0722332A - Plasma cvd device - Google Patents

Abstract

PURPOSE:To provide a plasma CVD device capable of adopting ICP as a plasma producing means as well as forming high quality films. CONSTITUTION:When a specific CVD processing gas is introduced in a vacuum vessel 2 from a gas blowing nozzle 10 while an antena 4 arranged near a dielectric window 3 is fed with high-frequency power, a high-frequency field is induced in the vacuum vessel 2 by the electromagnetic waves from the antena 4 so as to turn the CVD processing gas into plasma by the high-frequency field. A specimen 5 can be arranged in the position not to be exposed in the plasma due to the plasma produced near the antena 4 side in the vacuum vessel 2 so that the decomposed product of the CVD processing gas produced by the plasma may be deposited on the surface of the specimen 5 mounted on a specimen base to be formed into a film. At this time, the mounting part 7 of the specimen base 6 for mounting the specimen 5 is formed of a quartz glass so that the mixing of any impurities with the deposited film may be avoided thereby enabling the heating temperature of the mounted specimen 5 to be set up at high degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma CVD apparatus used in a semiconductor integrated circuit manufacturing process, and more particularly, to an ICP (Inductively Coupling) as a plasma generating means.
The present invention relates to an ICP plasma CVD apparatus that realizes film formation with less contamination of impurities, while configuring a plasma CVD apparatus using led plasma).

[0002]

2. Description of the Related Art A plasma CVD (Chemical Vapor Deposition) processing technique in a semiconductor integrated circuit manufacturing process is used for forming a pre-wiring insulating film on a semiconductor substrate, filling a via hole, and forming a passivation film. It is used for etc. As a plasma CVD apparatus used for such a CVD process, a parallel plate electrode type plasma CVD apparatus or an ECR plasma C is conventionally used.
VD devices have been adopted. The parallel plate electrode type plasma CVD apparatus is configured as shown in FIG. 3 as a schematic configuration diagram. In FIG. 3, parallel plate electrode type plasma CV
In the D device 20, an upper electrode 22 and a lower electrode 23 formed in a flat plate shape are arranged in parallel in a vacuum container 21 so as to face each other, and high frequency power is applied to the upper electrode 22 from a high frequency power supply. A sample 24 to be subjected to the CVD process on the lower electrode 23
Is placed and the lower electrode 23 is connected to the ground potential.
As shown in the drawing, from the channel provided in the upper electrode 22, C
When the VD processing gas is introduced into the vacuum container 21, plasma is generated between the electrodes 22 and 23 to which high frequency power is applied, and the decomposition product of the CVD processing gas generated by the plasma is deposited on the sample 24. The sample 24 is deposited and a film is formed on the surface of the sample 24. Further, as a plasma CVD apparatus, in addition to the parallel plate electrode type plasma CVD apparatus, an ECR (Electron
An ECR plasma CVD apparatus using a Cyclotron Resonance (Electron Cyclotron Resonance) plasma is known. The characteristic of this ECR plasma CVD apparatus is that high density plasma (electron density of about 1 × 10 ¹¹ to 10 ¹² / cm ³ ) can be obtained in a vacuum environment of relatively low pressure of several tens to several hundreds Torr. The advantage of the CVD using the plasma generated under the low pressure condition is that the mean free path of the material gas can be lengthened and the film can be formed with good step coverage. This ECR plasma CVD apparatus is configured as shown in a schematic configuration diagram in FIG. In FIG. 4, an ECR plasma CVD apparatus 26 includes a dielectric window 28 provided in an axial direction of a vacuum container 27 formed in a cylindrical shape.
Microwave is introduced into the vacuum container 27 from
A magnetic field is applied to the inside of the vacuum container 27 from the magnetic field generation coil 31 arranged coaxially with the vacuum container 27. The sample 29 is placed on the sample table 30 arranged at a predetermined position in the axial direction of the vacuum container 27.
And the CVD processing gas is introduced into the vacuum container 27, ECR plasma is generated in the vacuum container 27, and a decomposition product of the CVD processing gas generated by the plasma is deposited on the sample 29. A film is formed on the surface of the sample 29.

[0003]

In order to meet the recent demand for higher integration of semiconductor integrated circuits, fine and high quality film formation is required. However, in the above parallel plate electrode type plasma CVD apparatus, the plasma is generated between the electrodes, so that the sample comes into contact with the plasma, and it is preferable to use various compounds generated by the plasma regardless of whether it is preferable or not. Mixed in. For example, when forming a silicon oxide film (SiO), silane gas (SiH ₄ ) and nitrous oxide gas (N ₂ ) are generally used as a CVD processing gas.
O) is used. In addition, the organic liquid material ethyl silicate (T
EOS) may be used as a processing gas by using a vaporizer such as a bubbler. Ideally, in the silicon oxide film to be deposited, silanol (-OH) components, hydrocarbons, hydrogen components, nitrides that deteriorate the electrical properties of the film (electric breakdown withstand voltage, leakage current resistance) , Organic matter, heavy metals, etc. should not be contained at all. However, even in the case where the material gas is the silane gas and the nitrous oxide gas as described above, most of the compounds formed by the combination of the elements of Si, H, N and O are present in the plasma. Therefore, impurities such as O, H, and N are mixed in the silicon oxide film actually deposited by plasma CVD, and the film density and electrical characteristics are deteriorated. It is well known that a silicon oxide film formed by a parallel plate electrode type plasma CVD apparatus generally contains a large amount of hydrogen. The above problems are not limited to silicon oxide films, but silicon nitride films,
The same applies to the amorphous silicon film, the tungsten film, the tungsten silicide film, and the like. As described above, in the parallel plate electrode type plasma CVD apparatus, since the sample surface is in contact with the plasma, there is a problem that side reaction products generated in the plasma are inevitably mixed in the deposited film. Further, in the parallel plate electrode type plasma CVD apparatus, since carbon graphite, aluminum oxide, stainless steel, etc. are used for each electrode, there is a concern of heavy metal contamination of the sample. In such a plasma CVD processing technique in which impurities may be mixed in during film formation, there are obstacles to miniaturization and high quality that meet the demand for high integration.

On the other hand, in the above ECR plasma CVD apparatus, since the sample is not exposed to plasma, there is no mixing of side reaction products into the film as seen in the parallel plate electrode type plasma CVD apparatus. However, there is a problem in the device configuration. That is, ECR is generated by the action of the magnetic field and microwave.
It is not easy to generate uniformly, and it is required to have a considerably large magnetic field generating coil in order to make a device that can process an 8-inch wafer (sample), which is the mainstream of the current semiconductor manufacturing process. Problems such as cost increase and installation space increase due to the increase in size. Further, in the ECR plasma CVD apparatus, the plasma uniformity is easily influenced by the environment of the dielectric window, and when the CVD film is deposited and contaminated on the dielectric window, the deposition rate of the film formation is on the sample surface or the sample. There was a problem that it was not uniform between the two. The contamination of the dielectric window can be solved by cleaning the dielectric window at any time, but the cleaning is not easy because the magnetic field generating coil is arranged around the dielectric window. Therefore, the inventors of the present application have used ICP as a plasma generation means capable of performing a CVD process without exposing a sample to plasma and capable of generating a high-density plasma with a large diameter with a simple structure. I paid attention to the plasma. The conventional ICP has a problem in using it as a plasma CVD apparatus, but it is possible to generate a large-diameter high-density plasma by improving an antenna for applying high-frequency power for plasma generation. It was The inventors of the present application can configure a plasma CVD apparatus by using this ICP, keep impurities less mixed during film formation on the sample, and keep the sample heating temperature required for the CVD process higher. The present invention has been configured so that the present invention can be made. Therefore, it is an object of the present invention to provide a plasma CVD apparatus which employs an ICP as a plasma generating means and enables high quality film forming processing.

[0005]

In order to achieve the above-mentioned object, the means adopted by the present invention is to introduce a required CVD processing gas into a vacuum container to which high frequency power is applied to generate plasma, and generate by the plasma. CVD for depositing decomposed decomposition products on a sample placed in the vacuum container
In the apparatus, a vacuum container having a gas introduction nozzle for introducing the CVD processing gas, a dielectric window for introducing the high frequency power, and a vacuum container provided at a close position outside the dielectric window,
An antenna for inducing a high-frequency electric field in the vacuum container by applying high-frequency power from the outside of the dielectric window to the inside of the vacuum container, and a sample mounting portion which is arranged at a predetermined position in the vacuum container and is made of quartz glass. A plasma CV characterized by comprising a sample table formed of the above-mentioned and provided with a heating means for heating the mounted sample to a predetermined temperature.
It is configured as a D device. The plasma CVD apparatus is a plasma CVD apparatus in which a gas introducing nozzle for introducing a CVD processing gas into the vacuum container is made of quartz glass.
It can be configured as a device.

[0006]

According to the present invention, the required C from the gas introduction nozzle is
When VD processing gas is introduced into a vacuum container and high frequency power is supplied to an antenna arranged in the vicinity of a dielectric window, a high frequency electric field is induced in the vacuum container by an electromagnetic wave from the antenna, and the CVD processing is performed by the high frequency electric field. The gas is turned into plasma. Since the generation of plasma by ICP is less affected by the propagation state of electromagnetic waves, the contamination of the dielectric window is not immediately affected by the uniformity of plasma as in the case of ECR plasma. Since this plasma is generated in the vacuum container on the side close to the antenna, the sample can be placed at a position not exposed to the plasma, and the decomposition products of the CVD processing gas generated by the plasma are placed on the sample table. A film is formed by depositing on the surface of the sample. Therefore, the sample is not exposed to the plasma as described above, and since the mounting portion of the sample table on which the sample is mounted is made of quartz glass, the contamination of impurities in the deposited film is prevented. Is eliminated. Further, by forming the mounting portion of the sample table with quartz, the heating temperature of the mounted sample can be set high. Since the chemical reaction of CVD proceeds depending on the temperature, and in many cases the reaction is at a high temperature, a high upper limit of the heating temperature is effective for the CVD apparatus. Further, by forming the gas introduction nozzle with quartz glass, it is possible to prevent impurities from being mixed into the introduced CVD processing gas.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and do not limit the technical scope of the present invention. 1 is a schematic diagram showing the configuration of a plasma CVD apparatus according to an embodiment of the present invention, and FIG. 2 is an example of an antenna shape according to the embodiment.
It is a top view of the antenna shown in FIG. In FIG. 1, a plasma CVD apparatus 1 according to the present embodiment is formed in a cylindrical shape, and has a vacuum container 2 having a gas introduction port 10 and an exhaust port 11 for vacuum exhaust, and a central axis of the vacuum container 2. A dielectric window 3 provided on the line, an antenna 4 arranged outside the dielectric window 3 in the vicinity thereof, a high frequency power supply 9 for supplying high frequency power to the antenna 4 through a matching circuit 8,
A susceptor (mounting portion) that is movably arranged at a position on the central axis of the vacuum container 2 and that mounts the sample 5 thereon.
7 and a sample stage 6 including a heater (heating means) 12 for heating the sample 5 to a predetermined temperature via the susceptor 7.
And is configured. The antenna 4 is, for example, an antenna 4 formed in a spiral shape as shown in FIG.
The high frequency power supplied from the high frequency power source 9 is radiated into the vacuum container 2 to induce a high frequency electric field in the vacuum container 2. Further, the susceptor 7 is formed of quartz glass so that impurities are not mixed into the mounted sample 5 and the upper limit of the heating temperature of the sample 5 by the heater 12 provided on the back surface can be set high. Has been done. Furthermore, the gas introduction nozzle 10a for ejecting the CVD processing gas from the gas introduction port 10 into the vacuum container 2 is also made of quartz glass, and the inclusion of impurities in the CVD processing gas is eliminated.

In this embodiment, the plasma CV having the above structure is used.
The D device 1 is used to form a CVD film on a 6-inch silicon wafer used as the sample 5.
The sample 5 is placed on the susceptor 7 of the sample table 6 and evacuated from the exhaust port 11 by a vacuum pump (not shown) to supply silane (SiH ₄ ) and nitrous oxide gas (N ₂ O).
After individually controlling the flow rate of each gas, the gas introduction port 10
Is introduced into the vacuum container 2. Under the film forming process conditions in this embodiment, a high frequency of 13.56 MHz is supplied from the high frequency power source to the antenna 4 at 10 W to 1000 W, and silane and nitrous oxide gas are 100 sccm and 500, respectively.
It was introduced into the vacuum container 2 at a flow rate of sccm. Also, sample 5
The temperature of the 6-inch silicon wafer is 300 degrees
400 degrees, pressure 10mTorr ~ 1000mTorr
Then, the sample stage 6 was moved to change the distance between the sample 5 and the dielectric window 3 to 1 cm to 30 cm, and the CVD process was performed. In the above configuration, the required CV from the gas introduction nozzle 10a
When the D processing gas is introduced into the vacuum container 2 and high frequency power is supplied to the antenna arranged near the dielectric window 3, a high frequency electric field is induced in the vacuum container by the electromagnetic waves from the antenna. This high-frequency electric field accelerates electrons generated in the vacuum chamber 2 by natural radiation or the like, collides with neutral atoms in the CVD processing gas and ionizes the neutral atoms to generate ions and electrons, and initial plasma To occur. The newly generated electrons are accelerated by the high-frequency electric field, and the process of generating ions and electrons is repeated. When the plasma density rises above a certain level in this way, the electron density in the plasma rises and the response frequency of the electrons in the plasma rises. As a result, the plasma acts as a conductor and a current flows as if to block the high-frequency electric field, and begins to block the electromagnetic waves. At this time, electromagnetic waves do not enter inside the plasma except in a special mode peculiar to the plasma, so only the plasma on the surface obtains the energy of the electromagnetic waves from the antenna to further increase the plasma density and diffuse inside the plasma.

Decomposition products produced by the plasma generated as described above are deposited on the sample 5. Sample 5
Since the sample surface (the portion where the deposited film is to be formed) can be arranged at a position where the sample table 6 is not moved to be directly exposed to plasma, the dense C that does not contain impurities during film formation
A VD film is formed. In addition, since the conductor is not disposed at the position exposed to the plasma in the vacuum container 2, the sample 5 is not contaminated, and the nozzle of the gas introduction port 10 is formed of quartz glass so that impurities in the CVD processing gas can be prevented. Dense CV free from the above impurities by eliminating the inclusion
The formation of the D film is ensured. Under the process conditions in the above-mentioned embodiment, the heating temperature of the sample 5 is set to 300 to 400 degrees, but the upper limit temperature in the conventional configuration was about 500 degrees because the susceptor 7 was made of quartz glass. It is possible to raise the temperature to about 1100 ° C., the processing temperature can be set high depending on the condition for performing the CVD process, and the inclusion of impurities is eliminated, and the high-quality CVD process is achieved. Further, since the apparatus structure is simple as compared with the ECR plasma CVD apparatus, the inside of the vacuum container can be easily cleaned.

[0010]

As described above, according to the present invention, when the required CVD processing gas is introduced into the vacuum container from the gas introduction nozzle, high frequency power is supplied to the antenna arranged near the dielectric window. , An electromagnetic wave from an antenna induces a high frequency electric field in the vacuum container, and the high frequency electric field causes CVD.
The processing gas is turned into plasma. Since the generation of plasma by ICP is less affected by the propagation state of electromagnetic waves, the contamination of the dielectric window is not immediately affected by the uniformity of plasma as in the case of ECR plasma. Since this plasma is generated in the vacuum container on the side close to the antenna, the sample can be placed at a position not exposed to the plasma, and the decomposition products of the CVD processing gas generated by the plasma are placed on the sample table. A film is formed by depositing on the surface of the sample. Therefore, as described above, the sample is not exposed to the plasma, and since the mounting portion of the sample table on which the sample is mounted is made of quartz glass, impurities are not mixed in the deposited film. Is eliminated. Further, by forming the mounting portion of the sample table with quartz, the heating temperature of the mounted sample can be set high. Since the chemical reaction of CVD proceeds depending on the temperature, and in many cases the reaction is at a high temperature, a high upper limit of the heating temperature is effective for the CVD apparatus.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a plasma CVD apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of an antenna configuration according to an embodiment.

FIG. 3 is a parallel plate electrode type plasma CVD according to a conventional example.
The schematic diagram which shows the structure of an apparatus.

FIG. 4 is a schematic diagram showing a configuration of an ECR plasma CVD apparatus according to a conventional example.

[Explanation of Codes] 1 ... Plasma CVD apparatus 2 ... Vacuum container 3 ... Dielectric window 4 ... Antenna 5 ... Sample 6 ... Sample stand 7 ... Susceptor (placement portion) 10 ... Gas introduction port 10a ... Gas introduction nozzle 11 ... Exhaust Port 12 ... Heating heater (heating means)

Claims (2)

[Claims] 1. A required CVD processing gas is introduced into a vacuum container to which high frequency power is applied to generate plasma, and a decomposition product generated by the plasma is deposited on a sample arranged in the vacuum container. In the plasma CVD apparatus, a gas introduction nozzle for introducing the above CVD processing gas,
A vacuum container provided with a dielectric window for introducing the high frequency power and a proximity position outside the dielectric window, and by applying high frequency power into the vacuum container from outside the dielectric window, a vacuum is obtained. An antenna for inducing a high frequency electric field in the container,
The sample container is provided at a predetermined position in the vacuum container, the sample mounting portion is made of quartz glass, and the sample table is provided with a heating means for heating the mounted sample to a predetermined temperature. And a plasma CVD apparatus. 2. The plasma CVD by ICP according to claim 1, wherein the gas introduction nozzle is made of quartz glass.
apparatus.