JPH06151334A - Plasma cvd apparatus - Google Patents

Abstract

PURPOSE:To enhance the film formation speed of an apparatus and to prevent a bad influence, on a film formation operation, which is caused by the collosion of ions. CONSTITUTION:An RF electrode 4 to which a high frequency or microwaves are applied is arranged inside a reaction chamber 1 so as to face a counter electrode 2 at a grounding potential. The RF electrode 4 is constituted of a substrate holder 3 in which a heater 14 for heating a substrate 9 has been built and of a mesh electrode 11 which is arranged at the outside of the sheath region of a generated plasma on the side of the RF electrode 4 of the substrate 9 arranged on the substrate holder 3. A gas inflow pipe 5 which supplies a reaction gas into the reaction chamber 5 via gas-jetting holes 6a from the side of the counter electrode 2 is installed. Thereby, when a film is formed on the side of a plasma electrode at a strong electric field, the film formation velocity of the title apparatus is enhanced, positive ions are captured and gathered by the mesh electrode, and the collision of ions is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention excites and decomposes a reaction gas by glow discharge to cause a reaction in a low temperature region of a substrate to deposit a film, for example, Si ₃ N ₄ or SiO _{2 on} the surface of the substrate. The present invention relates to a plasma CVD apparatus that forms an insulating film and a protective film.

[0002]

2. Description of the Related Art A conventional capacitively coupled plasma CVD apparatus.
Are parallel to each other in the reaction chamber 21 as shown in FIG.
A high frequency is applied to the flat plate 22 to cause discharge, and the reaction gas
Reaction gas (SiH_Four＋ NH₃, Si
H_Four＋ N₂(For example, O) to excite and ionize the
Creates separated ions and highly reactive neutral molecules. So
Then, the reaction gas is arranged in parallel below the flat plate 22.
Heated by the heater 25 on the ground electrode 24
Reacting on the surface of the substrate 26_XN_YAnd SiO _xSuch
The insulating thin film is deposited and formed.

[0003]

However, in the above structure, the substrate 26 is usually disposed on the ground electrode 24 to form a thin film, and there is a sheath region where the potential drops on the side of the flat plate 22. At the same time, there is a sheath region where the potential drops on the ground electrode 24 side. Then, the positive ions are accelerated by the electric field in this sheath region and the ground electrode 2
There is a problem in that ion collisions that collide with the surface of the substrate 26 on the No. 4 substrate occur, which adversely affects the formation of the thin film.

The present invention solves the above problems, prevents ion collision with the substrate caused by the sheath electric field on the side of the ground electrode to improve the film quality, and increases the film formation speed to improve the productivity. It is an object of the present invention to provide a plasma CVD apparatus that can be manufactured.

[0005]

In order to solve the above problems, a plasma CVD apparatus according to the present invention is a plasma electrode to which a high frequency wave or a microwave is applied in a reaction chamber, facing a ground electrode having a ground potential. The plasma electrode is disposed outside the sheath region of the generated plasma, facing the ground electrode on the substrate holder with the heater built in and the ground electrode side of the substrate disposed on the substrate holder. And a reaction gas supply pipe configured to supply a reaction gas to the ground electrode.
The substrate holder is provided with a heater for heating the substrate.

[0006]

According to the above construction, by forming a film on the substrate on the plasma electrode side of a strong electric field having a potential gradient much larger than that on the ground electrode side, the film formation rate is improved by utilizing accelerated electrons that have a large reaction. can do. Moreover, since the accelerated positive ions are collected by the mesh electrode outside the sheath region where the electrons are accelerated to increase the energy, the ion collision is prevented, the adverse effect on the film formation is prevented, and a good film quality is obtained. be able to.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the plasma CVD apparatus according to the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a reaction chamber formed by a reaction container 1a having a ground potential, and an upper portion of the reaction chamber 1 has a counter electrode (ground electrode) 2 having a ground potential.
And an RF electrode (plasma electrode) 4 (which may be a high frequency electrode or a microwave discharge electrode) equipped with a substrate holder 3 is arranged outside the sheath region in the lower part of the reaction chamber 1. There is.

The counter electrode 2 is connected to a gas inflow pipe 5 for supplying a reaction gas, and has a gas inflow chamber 6 inside.
And a large number of gas injection holes 6a are formed on the lower surface facing the RF electrode 4.

The RF electrode 4 is made of an insulating material and is provided in a holding box 7 having an opening on the upper surface.
The substrate holder 3 on which the substrate holder 3 is placed is arranged, and the mesh electrode 11 electrically connected to the substrate holder 3 is arranged on the opening surface of the holding box 7. To the conduit 12 passing through
High frequency power is applied from the high frequency electrode 10 through the matching circuit 13. Further, the heater 1 for heating the substrate 9 in the hollow portion 3a formed in the lower portion of the substrate holder 3.
4, a conductor 16 from a heater control power supply 15 is connected to the heater 14 through the conduit 12.

Reference numeral 17 is a gas discharge pipe connected to the lower portion of the reaction chamber 1. FIG. 2 shows an average potential distribution near the discharge region between the counter electrode 2 and the RF electrode 4. The potential of this discharge region is always kept at the plasma potential V _P higher than the ground potential. The RF electrode 4 has a self-bias potential V _DC.
And (the normal ground electrode is not only the counter electrode 2,
(Because the inner wall of the reaction chamber 1 is also considered to be the ground electrode)
The RF electrode 4 has a small ground electrode area and has a negative potential. Here, V _S is the voltage applied to the RF electrode 5.

In addition, near the RF electrode 4 and the counter electrode 2,
Potential gradient is₁, C ₂Creates a strong electric field
Has been. Electrons are accelerated in this region,
The geated electrons cause various reactions. Normal film formation is
The substrate is placed on the land potential side, but the reaction energy
When considered, a stronger electric field (large potential gradient) is formed.
The reaction due to accelerated electrons is greater when performed on the RF electrode side.
The film forming speed can be improved. However, the strong electric field
Positive ions also accelerate, so collisions with ions that collide with the electrode
It has an adverse effect on the film formation, which is caused by the RF electrode 4 side.
Is considered to be much larger. Therefore, in the present invention,
The mesh electrode 11 arranged above the plate 9 causes ion collision.
Solves this problem by collecting positive ions that cause
is doing.

In the above configuration, the high frequency power source 10 to R
While applying a high frequency to the F electrode 4 to cause discharge,
A reaction gas (SiH ₄ + NH ₃ , SiH ₄ + N ₂ O, etc.) as a raw material is ejected from the gas inflow chamber 6 of the counter electrode 2 through the gas injection hole 6a to excite and ionize the reaction gas in the plasma. Ions ionized therein and neutral molecules with high reactivity are formed, and this reactive gas is carried to the substrate 9 through the mesh electrode 11 and reacted on the surface of the substrate 17 heated by the heater 14. , Si _X N _Y and SiO
An insulating thin film such as _x is deposited and formed.

Therefore, the counter electrode 2 (ground electrode)
RF on the sheath region C ₂ side of a stronger electric field than the sheath region C _{1 of}
Since the electrode 4 is used to form a film on the substrate 9, the film forming rate can be further improved, and the productivity can be improved. Moreover, since the mesh electrode 11 is arranged outside the sheath region C ₂ in the RF electrode 4, it is possible to collect positive ions that cause ion bombardment and prevent the ion bombardment from adversely affecting the film formation.

[0015]

As described above, the plasma C of the present invention is used.
According to the VD device, by forming a film on the substrate on the plasma electrode side having a strong electric field in which the potential gradient is much larger than on the ground electrode side, it is possible to improve the film forming rate by utilizing accelerated electrons having a large reaction. it can. Moreover, since the accelerated positive ions are collected by the mesh electrode outside the sheath region where the electrons are accelerated to increase the energy, the ion collision is prevented, the adverse effect on the film formation is prevented, and a good film quality is obtained. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a plasma CVD apparatus according to the present invention.

FIG. 2 is a graph showing an average potential distribution in a discharge region in the plasma CVD apparatus.

FIG. 3 is a sectional view showing a conventional plasma CVD apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Counter electrode 3 Substrate holder 4 RF electrode 5 Gas inflow pipe 6 Gas inflow chamber 6a Gas injection hole 7 Holding box 8 Insulating plate 9 Substrate 10 High frequency power supply 11 Mesh electrode 14 Heating heater 15 Heating heater power supply 17 Gas exhaust pipe V _P plasma potential V _DC self-bias potential V _S voltage applied to RF electrode C ₁ and C ₂ sheath region

Claims (1)

[Claims] 1. A substrate holder, in which a plasma electrode to which a high frequency or a microwave is applied is arranged in the reaction chamber so as to face a counter electrode having a ground potential, a heater is built in the plasma electrode, and the substrate. And a mesh electrode arranged on the ground electrode side of the substrate arranged on the holder and outside the sheath region of the generated plasma, and a reaction gas supply pipe for supplying a reaction gas to the counter electrode is provided. Plasma CVD apparatus.