Heating element CVD system

Details Heating element CVD system Heating element CVD system

2002-05-14

2003-07-15

Walberg, Teresa (Department: 3742)

Electric heating

Heating devices

Combined with container, enclosure, or support for material...

C219S409000, C219S541000, C118S725000, C118S728000

Reexamination Certificate

active

06593548

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a heating element CVD system in which a heating element kept at a specified temperature is disposed in a vacuum chamber (processing container) and in which a raw material gas is decomposed and/or activated by the said heating element to deposit a thin film on a substrate placed in the vacuum chamber (processing container).
BACKGROUND ART
In manufacturing various kinds of semiconductor devices including a LSI (large scale integrated circuit), a LCD (liquid crystal display) and the like, a CVD (chemical vapor deposition) method has been widely used as one process for forming a predetermined thin film on a substrate
In CVD method, there are several methods, that is, a plasma CVD method in which a raw material gas is decomposed and/or activated in discharged plasma to form a thin film, a thermal CVD method in which a substrate is heated to induce a chemical reaction to form a thin film and so on. In addition, a CVD method in which a raw material gas is decomposed and/or activated by a heating element kept at a predetermined high temperature to form a thin film (hereinafter referred to as a heating element CVD method).
In a film forming system for performing the heating element CVD method (hereinafter referred to as a heating element CVD system), a heating element made of a refractory metal such as tungsten or the like is disposed in a processing chamber. The processing chamber is capable of being evacuated to a vacuum. A raw material gas is introduced into the evacuated processing chamber while the heating element is kept at high temperatures from about 1000° C. to 2000° C.
The introduced raw material gas is decomposed and/or activated when it passes over the surface of the heating element and reaches a substrate to deposit a thin film of the material, which is a final objective material, on the surface of the substrate. In the heating element CVD methods, a CVD method using a wire-shaped heating element is called as a Hot Wire CVD method, and a CVD method utilizing the catalytic reaction of a heating element for decomposing and/or activating the raw material gas is called as a catalytic CVD (or Cat-CVD) method.
In the heating element CVD method, the raw material gas is decomposed and/or activated when it passes over the surface of the heating element. For this reason, this method has an advantage of reducing the temperature of the substrate as compared with the thermal CVD method in which reaction is induced only by the heat of the substrate. Further, in the heating element CVD method, plasma is not produced, as it is produced in the plasma CVD method. For this reason, there is no worry that plasma causes damage to the substrate. Accordingly, the heating element CVD method is thought to be a promising candidate as a film forming method for a semiconductor device, a display device and the like of the next generation in which high integration and high functionality have been increasingly required.
FIG. 10
shows conceptional view of a conventional heating element CVD system. In a processing container
1
, a predetermined processing of forming a thin film is performed to a substrate (not shown). An evacuation system
11
for evacuating the processing container
1
to a vacuum and a raw material gas supply system
21
for supplying a raw material gas into the processing container
1
for forming a thin film are connected to the processing container
1
.
In the processing container
1
, a heating element
3
is disposed such that the raw material gas supplied into the processing container
1
passes over the surface of it. A power supply mechanism
30
for supplying electric power is connected to the heating element
3
, thereby the heating element
3
is heated and kept at a predetermined temperature (a high temperature of about from 1600° C. to 2000° C.) required for the heating element CVD method. Further, in the processing container
1
, a gas supply unit
2
and the heating element
3
are arranged facing each other.
Further, in the processing container
1
, a predetermined thin film is formed on the substrate (not shown) by the raw material gas decomposed and/or activated by the heating element
3
that is kept at the predetermined high temperature described above. For this reason, in the processing container
1
, a substrate holder
4
is provided for holding the above-mentioned substrate (not shown).
In
FIG. 10
, it is a gate valve for carrying the substrate into or out of the processing container
1
that is denoted by a reference character
5
. Further, the substrate holder
4
is provided with, as is conventionally known, a heating mechanism for heating the substrate, but this heating mechanism will not be shown or described because it is not important in the present invention.
In the embodiment shown in
FIG. 10
, although it is not shown, the raw material gas supply system
21
includes a cylinder filled with the raw material gas, a supply pressure regulator, a flow regulator, a supply/stop switching valve, and the like. The raw material gas is supplied by the raw material gas supply system
21
into the processing container
1
via the gas supply unit
2
provided in the processing container
1
.
Further, in a process using two or more kinds of raw material gases, the raw material gas supply systems
21
of the number equal to the number of kinds of gases used are connected in parallel to the gas supply unit
2
.
The gas supply unit
2
, as described above, is arranged in face with the heating element
3
in the processing container
1
. Further, the gas supply unit
2
has a hollow structure and many gas blowing holes
210
on a surface facing the substrate holder
4
.
On the other hand, the evacuation system
11
is connected to the processing container
1
via a main valve
12
having an evacuation speed regulating function. The pressure of the processing container
1
is controlled by this evacuation speed regulating function.
In the heating element CVD method, the substrate (not shown) is a substance to be subjected to a predetermined processing of forming a thin film. This substrate (not shown) is carried in and out of the processing container
1
via the gate valve
5
. And a heating mechanism (not shown) for heating the substrate (not shown) to a predetermined temperature is built in the substrate holder
4
.
The heating element
3
is generally formed of a wire-shaped member and is bent in the shape of sawteeth and is held by a support body
31
, the surface of which is at least made of insulator. Further, a power supply line
32
from the power supply mechanism
30
is connected to the heating element
3
by a connection terminal
33
. An electric power is supplied to the heating element
3
via this connection terminal
33
to heat the heating element
3
to the predetermined temperature required for the heating element CVD method and to keep it at the predetermined temperature.
Usually, a direct current power source or an alternating current power source is used as the power supply mechanism
30
. The heating element
3
is supplied with electric power from the power source and is set at the predetermined temperature by the passage of the electric current. By heating the heating element
3
to a high temperature, the raw material gas is decomposed and/or activated to effectively form a thin film.
Usually, the heating element
3
is heated to a predetermined temperature (usually, at a film forming process, a high temperature of from about 1600° C. to 2000° C.) by the passage of the electric current, so a refractory metal is used as the material for the heating element
3
and, in general, tungsten is used.
A case where a silicon film is formed and a case where silicon nitride film is formed are explained as examples of forming a thin film by the heating element CVD system shown in FIG.
10
. The processes are proceeded as follows.
First, a mixed gas of silane (SiH
4
) and hydrogen (H
2
) is used in the case where the silicon film is formed. A mixed gas of silane and ammonia (NH
3
) is used in the case where th

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