JP2765788B2 - Plasma CVD equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for exciting and decomposing a reaction gas by glow discharge to cause a substrate to react in a low temperature range to deposit a film. For example, a substrate such as Si ₃ N ₄ or SiO _{2 is} deposited on the surface of the substrate. The present invention relates to a plasma CVD apparatus for forming an insulating film and a protective film.

[0002]

2. Description of the Related Art Conventional capacitively coupled plasma CVD apparatus
Are, for example, as shown in FIG.
A high frequency is applied to the flat plate 22 to cause discharge, and the reaction gas is applied.
Reaction gas (SiH)_Four+ NH_Three, Si
H_Four+ N_TwoO, etc.) to excite, ionize,
Creates isolated ions and highly reactive neutral molecules. So
Then, the reaction gas is disposed in parallel below the flat plate 22.
Is heated by the heater 25 on the ground electrode 24
Reacts with the surface of the substrate 26_XN_YAnd SiO _xSuch
Is deposited to form an insulating thin film.

[0003]

However, in the above configuration, 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 toward the flat plate 22. At the same time, a sheath region where the potential drops also exists on the ground electrode 24 side. Then, positive ions are accelerated by the electric field in the sheath region, and the ground electrode 2 is accelerated.
There is a problem that ion collision colliding with the surface of the substrate 26 on the substrate 4 has a bad influence on the formation of a thin film.

SUMMARY OF THE INVENTION The present invention solves the above problems, prevents ion collision with the substrate caused by the sheath electric field on the ground electrode side, improves 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 capable of performing the above.

[0005]

In order to solve the above-mentioned problems, a plasma CVD apparatus according to the present invention comprises a plasma electrode in which a high frequency or microwave is applied in a reaction chamber opposite a ground electrode which is a ground potential. The plasma electrode was placed outside the sheath region of the generated plasma, facing the ground electrode on the ground electrode side of the substrate holder with the built-in heater and the substrate placed on the substrate holder. 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 structure, the film is formed on the substrate on the plasma electrode side of the strong electric field having a potential gradient much larger than that on the ground electrode side, and the film formation rate is improved by utilizing the accelerated electrons having a large reaction. can do. In addition, since the accelerated positive ions are collected by the mesh electrode outside the sheath region where electrons are accelerated to increase energy, ion collision is prevented to prevent adverse effects on film formation and obtain good film quality. be able to.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a 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 vessel 1a at a ground potential, and a counter electrode (ground electrode) 2 at a ground potential is provided in an upper portion of the reaction chamber 1.
And an RF electrode (plasma electrode) 4 (which may be a high-frequency electrode or a microwave discharge electrode) provided with a substrate holder 3 at a lower portion inside the reaction chamber 1 and outside the sheath region. I have.

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

[0010] The RF electrode 4 is made of an insulating material and is held in a holding box 7 having an upper surface opening by a substrate 9 on an upper surface via an insulating plate 8.
And a mesh electrode 11 electrically connected to the substrate holder 3 is arranged on the opening surface of the holding box 7, and is connected to the substrate holder 3 so that the reaction chamber 1 is placed. Into a conduit 12 that passes through
High frequency power is applied from the high frequency electrode 10 via the matching circuit 13. Further, a heater 1 for heating the substrate 9 is provided in a hollow portion 3a formed below 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 denotes a gas discharge pipe connected to a lower part 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 the discharge region is always kept to a higher plasma potential V _P ground potential. The RF electrode 4 has a self-bias potential V _DC
(The normal ground electrode is not only the counter electrode 2,
(Because the inner wall of the reaction chamber 1 is also considered a ground electrode.)
The RF electrode 4 has a small ground electrode area and a negative potential. Here, V _S is a voltage applied to the RF electrode 5.

In addition, it occurs near the RF electrode 4 and the counter electrode 2.
Potential gradient is the sheath region C₁, C _TwoA strong electric field is formed
Have been. In this region, electrons are accelerated, and high energy
The electrons that have turned into energy cause various reactions. Normal film formation
The reaction is performed with the substrate placed on the land potential side.
In consideration of this, a stronger electric field (large potential gradient) is formed.
When the reaction is performed on the RF electrode side, the reaction due to the accelerated electrons is larger.
The film formation rate can be improved. However, the strong electric field
Since positive ions also accelerate, ion collisions that collide with the electrode
And adversely affect the film formation.
Is thought to be much larger. Therefore, in the present invention,
Ion collision with mesh electrode 11 arranged above plate 9
Solves this problem by collecting positive ions
doing.

In the above configuration, the high frequency power supply 10
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 a gas inflow chamber 6 of a counter electrode 2 through a gas injection hole 6 a to excite and ionize the reaction gas in the plasma, The ions ionized in the inside and neutral molecules having high reactivity are formed, and this reactive gas is carried on the substrate 9 through the mesh electrode 11 and reacted on the surface of the substrate 17 heated by the heater 14. And Si _{X NY} 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 with a stronger electric field than the sheath region C ₁
Since the film is formed on the substrate 9 at the electrode 4, the film forming speed can be further improved, and the productivity can be improved. Moreover, since the placing mesh electrode 11 to the outer sheath region C ₂ in the RF electrode 4, it is possible to collect the positive ions produced ion bombardment, it is possible to prevent an adverse effect on the film by the ion bombardment.

[0015]

As described above, the plasma C of the present invention is used.
According to the VD apparatus, 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 of the ground electrode side, it is possible to improve the film formation rate by using accelerated electrons having a large reaction. it can. In addition, since the accelerated positive ions are collected by the mesh electrode outside the sheath region where electrons are accelerated to increase energy, ion collision is prevented to prevent adverse effects on film formation and obtain good film quality. be able to.

[Brief description of the 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 Heater 15 Heater power supply 17 Gas discharge pipe V voltage C ₁ according to the _P plasma potential V _DC self-bias potential V _S RF electrodes, C ₂ sheath region

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-278131 (JP, A) JP-A-58-124223 (JP, A) JP-A-59-8609 (JP, A) JP-A-59-8609 72126 (JP, A) JP-A-59-88821 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/205 H01L 21/31 C23C 16/50

Claims (1)

(57) [Claims] 1. A plasma electrode to which a high frequency or microwave is applied is disposed in a reaction chamber so as to face a counter electrode at a ground potential. 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.