JPS61256640A - Plasma chemical vapor deposition apparatus - Google Patents

Abstract

PURPOSE:To reduce defects in a plasma CVD film on a specimen and improve the quality by a method wherein a negative DC voltage is applied to an electrode and the voltage is so controlled as to generate a sputtering phenomenon on the electrode surface in order to remove deposited substances adhering to the electrode surface. CONSTITUTION:The internal pressure of a vacuum container 101 is reduced to not higher than 30mTorr by a vacuum pump 108. Then gaseous compounds, i.e. monosilane, ammonium and nitrogen, which contain constituents of thin film, are introduced through a gas flow control apparatus 112 from a gas inlet 111 with flows of 10SCCM, 32SCCM and 80SCCM respectively onto the surface of a specimen 102 and the internal pressure control unit 110. The specimen 102 is heated and maintained at the temperature of 350 deg.C by a specimen table 103. Then a negative DC voltage of -300V is applied to the electrode 106 and, under this condition, further a high-frequency power of 0.33W/cm<2> with a frequency of 50KHz is supplied in order to generate a low-temperature plasma. With the process described above, a silicon nitride film is formed on the surface of the specimen 102.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention applies to PRADA? CV D (Chemical
VaporD41PO! The present invention relates to a plasma vapor phase epitaxy apparatus for forming a thin film using the lit ion method.

In the conventional plasma CVD method, a sample is held in a vacuum container, and while a compound gas containing the constituent elements of the thin film to be formed is supplied, the compound gas is excited by high frequency energy, and the sample surface is exposed to the plasma. This method forms a thin film on the surface of a sample by placing it in an atmosphere. This method utilizes the activity of plasma, so it is possible to
There is a main component that allows film formation at low temperatures down to about 0°C.

A problem in forming thin films by plasma CVD is controlling the quality and thickness distribution of the formed thin film.

Therefore, in order to form a high-quality plasma CVD film on the sample surface, the plasma distribution during thin film formation must be adjusted.

It is necessary to consider process conditions such as sample heating distribution and sample holding temperature.

Hereinafter, an example of the above-mentioned conventional plasma vapor phase growth apparatus will be described with reference to the drawings.

FIG. 3 shows a conventional plasma vapor phase growth apparatus.

In FIG. 3, 1 is a vacuum container that can maintain a vacuum state, 2 is a sample on which a plasma CVD film is formed, and 3 is a sample 2.
and has an internal heater for heating sample 2.
A sample stand capable of heating the sample stand, 4 a heater mounted inside the sample stand 3, 6 an AC power source, and 6 a 50 KHz high frequency power supplied to the space containing at least the sample 2;
An electrode for generating low-temperature plasma, 7 a high-frequency power source for supplying high-frequency power at a frequency of 50 KHz to the electrode 6 via a matching circuit, and 8 evacuating the pressure inside the vacuum container 1 to a degree of vacuum below atmospheric pressure. 9 is a vacuum exhaust pipe that airtightly connects the vacuum container 1 and the vacuum pump 8, 10 is a butterfly valve that controls the pressure inside the vacuum container 1 by varying the resistance inside the pipe, and 11 is a vacuum pump. A gas introduction pipe 12 is a gas flow rate control device for supplying a compound gas containing the constituent elements of the thin film formed on the surface of the sample 2 into the container 1.

The operation of the plasma vapor deposition apparatus configured as described above will be described below.

First, the inside of the vacuum container 1 is pumped with the vacuum pump 8, and the pressure is 50 mTo.
After evacuation to a vacuum level below rr, a compound gas containing the constituent elements of the thin film to be formed on the surface of the sample 2 is introduced from the gas introduction pipe 11 while controlling the flow rate with the gas flow rate controller 12.
Introduced into vacuum container 1. In addition, butterfly valve 1
o to adjust the pressure that is the thin film forming condition, i.e. 100~
The inside of the vacuum container 1 is controlled to 400 mTorr. Also,
The sample 2 is heated and controlled to a temperature of about 300° C. by the sample stage 3.

Next, by supplying high frequency power with a frequency of 50 KHz to the electrode 6, the compound gas is excited, and the surface of the sample 2 is exposed to the plasma atmosphere, thereby depositing a plasma CVD film on the surface of the sample 2.

Problems to be Solved by the Invention However, with the above configuration, plasma CVD
When forming a film, in addition to depositing a plasma CVD film on the surface of the sample 2, a porous film with a low density or a large amount of particulate or lump-like deposits also adheres to the surface of the electrode 6.

These deposits on the surface of the electrode 6 have a weak adhesion to the electrode 6, fall or float on the surface of the sample 2 in the form of particles or lumps, and are formed on the surface of the desired sample 2 due to plasma CVD.
Causes defects in the membrane. That is, if they adhere during low-temperature plasma generation, pinholes or protrusions will occur in the plasma CVD film, causing quality problems.

In addition, if a plasma CV film is formed on the surface of the sample 2, and if it falls or floats and then adheres to the surface,
This causes problems in the photolithography process, which is a post-process for forming contact holes, etc., particularly in the resist coating process and the exposure process.

In view of the above-mentioned problems, the present invention suppresses the formation of deposits adhering to the surface of the electrode 6, can significantly reduce defects in plasma CVD films, and makes it possible to improve the quality of plasma CVD films. A plasma vapor phase growth apparatus is provided.

Means for Solving the Problems In order to solve the above problems, the plasma vapor phase growth apparatus of the present invention includes a vacuum container capable of maintaining a vacuum state, and a vacuum pump for creating a reduced pressure atmosphere inside the vacuum container. , a pipe that airtightly connects the vacuum container and vacuum pump, and a plasma CV
A sample stage that holds a sample on which the D film is to be formed on at least one surface; a heating device that directly or indirectly controls the heating of the sample; a source gas that is introduced into a vacuum container; An electrode for generating low-temperature plasma at least in a space containing a sample while controlling the pressure inside the container to a predetermined level, a high-frequency power source for supplying high-frequency power to the electrode via a matching circuit, and high-frequency power to the electrode. Additionally, it is equipped with a DC power supply that controls and supplies a negative DC voltage of rsoV to 10oOV via a filter circuit.

Effect of the Invention With the above-described configuration, the present invention applies a negative DC voltage to the electrode, accelerates and attracts positive ion atoms or molecules in the low-temperature plasma toward the electrode, and causes a sputtering phenomenon to occur on the electrode surface. By controlling
By removing deposits that adhere to the electrode surface in atomic or molecular form while depositing the plasma CVD film on the sample, defects in the plasma CVD film on the sample can be reduced and the quality of the plasma CVD film can be improved. It will make it possible.

EXAMPLE Hereinafter, a plasma vapor phase growth apparatus according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of a plasma vapor phase growth apparatus in a first embodiment of the present invention.

In FIG. 1, 1o1 is a vacuum container capable of maintaining a vacuum state, 102 is a sample on which a plasma CVD film is formed, 1
03 is a sample stand 10 that holds the sample 102 and has a heating device inside and is capable of heating the sample stand 102;
4 is a heating device mounted inside the sample stage 103; 106;
106 is an electrode for generating low-temperature plasma in the space containing the sample; 107 is a high-frequency power supply for supplying high-frequency power to the electrode 108 via a matching circuit;
108 is a vacuum pump for evacuating the pressure inside the vacuum container 101 to a degree of vacuum below atmospheric pressure; 109 is the vacuum container 1;
01 is an evacuation pipe that airtightly connects the vacuum pump 108; 11° is a pressure control device for controlling the pressure in the vacuum container 101; 112 is a gas flow rate control device; 113 is a gas flow control device for supplying a compound gas containing the compositional elements of the thin film;
This is a DC power supply that controls and supplies negative DC voltage from 0V to 1o00V via a filter circuit.

The operation of the plasma vapor deposition apparatus configured as described above will be explained below with reference to FIGS. 1 and 2.

First, the inside of the vacuum container 101 is pumped by the vacuum pump 10B.
After evacuation to a vacuum level of 30 mTorr or less, a compound gas containing the constituent elements of the thin film to be formed on the surface of the sample 102, that is, monosilane (SiH4), ammonia (
NH3) and nitrogen (N2) mixed gas at 108 CCM each.
, 31 SCCM, 80 SCCM of gas is introduced into the vacuum vessel 101 through the gas introduction pipe 111 through the gas flow rate control device 112, and the pressure inside the vacuum vessel 101 is controlled by operating the pressure control device 11o. 0.30 Tor
hold at r. Further, the sample 102 is heated to a temperature of 350°C by the sample stage 103. Next, the electrode 1
A negative DC voltage of -300V is applied to 06, and in this state, high frequency power with a frequency of 50KHz is applied at 0.33W/
By supplying d (1ooW), sample 102
generates low-temperature plasma in a space containing Through the above operations, a silicon nitride film with a refractive index of 1.99±0.02° and a film thickness distribution of within ±3 degrees could be formed on the surface of the sample 102. Here, 0.3μ on the surface of sample 102
When measuring the number of particles of m or more with a laser surface inspection device, it was over 300 with the conventional device, but by applying a negative DC voltage of -200V to -1600V, the number of particles was significantly reduced to less than 40. Deposits on the surface of the electrode 106 were hardly observed in #1.

FIG. 2 shows the results of an experiment on the dependence of film deposition rate and refractive index on negative DC voltage values. As shown in FIG. 2, the negative DC voltage did not change the formation conditions during deposition on sample 102.

In this embodiment, the gas supplied into the vacuum container 101 is monosilane (S I H4) (!: ammonia (N
By adding an inert gas such as argon (Ar) or xenon to these compound gases, the sputtering phenomenon on the surface of the electrode 1061 can be reduced to a negative direct current. Easier to control with voltage. Also, depending on the material of the electrode 106, the surface of the sample 102 may be made of the same material as the plasma CVD film deposited on the surface of the sample 102, or the plasma CVD film may be made of the same material as the plasma CVD film deposited on the surface of the sample 102. A material containing the constituent elements may be used. That is, the material of the electrode 106 may be silicon, silicon nitride, or the like.

As described above, according to this embodiment, the vacuum container 101 capable of maintaining a vacuum state, the vacuum pump 108 for creating a reduced pressure atmosphere inside the vacuum container, and the vacuum container 1o1 and the vacuum pump 108 are connected airtightly. pipe 109 and plasma C
Sample 102 on which a VD film is formed on at least one surface
a sample stage 103 for holding the sample 102; a heating device 104 for directly or indirectly heating the sample 102;
A source gas is introduced into the vacuum container 1o1, and while the pressure inside the vacuum container 1o1 is controlled to a predetermined pressure, an electrode 106 that generates low-temperature plasma and a matching circuit are connected to the electrode 106 in a space that includes at least the sample 102. A high frequency power source 107 for supplying high frequency power and an electrode 10
6 is provided with a DC power supply 113 that controls and supplies a negative DC voltage of 50V to 10oOv through a filter circuit together with high-frequency power, and applies the negative DC voltage to the electrode 106 to generate positive ions in the low-temperature plasma. By accelerating atoms or molecules in the direction of the electrode 106 and controlling the sputtering phenomenon to occur on the surface of the electrode 106, the deposits attached to the surface of the electrode 106 can be reduced while depositing a plasma CVD film on the surface of the sample 102. By removing the objects, defects in the plasma CVD film on the surface of the sample 102 can be reduced and the quality of the plasma CVD film can be improved.

Effects of the Invention As described above, the present invention provides a vacuum container that can maintain a vacuum state, a vacuum pump that creates a reduced pressure atmosphere inside the vacuum container, a pipe that airtightly connects the vacuum container and the vacuum pump,
A sample stage that holds a sample on which a plasma CVD film is to be formed on at least one surface; a heating device that directly or indirectly controls the heating of the sample; a source gas that is introduced into a vacuum container; With the inside of the container controlled to a predetermined pressure, an electrode that generates low-temperature plasma in at least a space containing the sample, and a matching circuit to the electrode,
By providing a high frequency power supply for supplying high frequency power to the electrodes and a DC power supply for controlling and supplying a negative DC voltage of 50 V to 1 ooov through a filter circuit together with the high frequency power to the electrodes, plasma can be generated on the sample. When forming a CVD film, it is possible to prevent deposits from adhering to the electrode, and after they peel off and fall or float on the sample,
Preventing adhesion and reducing defects in plasma CVD films,
That is, the quality of the plasma CVD film can be improved.

Note that in the first embodiment, the electrode 106 is connected to the sample 10.
Although the electrode 106 is disposed opposite to the sample stage 103 holding the electrode 2 and has a disk shape, the electrode 106 may have a cylindrical shape.

Further, although the shape of the sample stage 103 is a disk shape, it may be made into a cylindrical shape and the sample 102 may be placed on the inner or outer surface thereof.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a plasma vapor phase growth apparatus in an embodiment of the present invention, and FIG. 2 is a diagram showing the experimental results of investigating the dependence of film deposition rate, refractive index, and negative DC voltage value.
FIG. 3 is a schematic cross-sectional view of a conventional plasma vapor phase growth apparatus. 101... Vacuum container, 103... Sample stand, 104... Heating device, 106...
Electrode, 107... High frequency power supply, 108...
...Vacuum pump, 113...DC power supply. Name of agent: Patent attorney Toshio Nakao and 1 other person/l
l/-Empty container shuku--Ikkaku (produced e3---m@/17---High school 11 pullout (source! 2 figures)

Claims (4)

[Claims] (1) A vacuum container that can maintain a vacuum state, an exhaust means to create a reduced pressure atmosphere inside the vacuum container, and plasma CVD
A sample holding means for holding a sample on which a film is to be deposited on at least one surface, a heating means for controlling heating of the sample, a gas supply means for introducing a raw material gas into the vacuum vessel, and a sample holding means for holding a sample on which a film is to be deposited on at least one surface; a pressure control means for maintaining the pressure at the pressure of A plasma vapor phase growth apparatus comprising a plasma generating means, and a DC power source that supplies a negative DC voltage of 50V to 1000V to the electrodes together with high frequency power through a filter circuit. (2) The plasma vapor phase according to claim 1, wherein the composition of the source gas is a mixed gas of a compound gas containing the constituent elements of the plasma CVD film to be formed on the sample surface and at least argon gas or xenon gas. growth equipment. (3) The material of the electrode is such that at least the part located in the low-temperature plasma atmosphere is formed on the sample surface by plasma CVD.
2. The plasma vapor phase growth apparatus according to claim 1, wherein the main component is at least one of the compositional elements of the film. (4) The plasma vapor phase epitaxy apparatus according to claim 1, wherein the electrode is made of the same material as the plasma CVD film, at least in the portion located in the low-temperature plasma atmosphere.