JPH02305967A - Electrode plate for plasma cvd device - Google Patents

Abstract

PURPOSE:To prevent the deterioration in the quality of an SiO2 thin film by the generation of SiO2 dust by using a specifically composed Mo-Ta alloy as electrode plates at the time of forming the SiO2 thin film, etc., on a substrate by a plasma CVD device. CONSTITUTION:The inside of a vacuum chamber 1 which has the upper electrode 2a and the lower electrode 2b and is imposed with the substrate 7 on the lower electrode 2b is evacuated to a vacuum by a discharge pipe. Gaseous SiH4 and gaseous N2O are supplied as gaseous raw materials from a gas introducing pipe 5 into the chamber. A high-frequency voltage is simultaneously impressed to generate the plasma by a glow discharge between the two electrodes 2a and 2b to form the thin film of the SiO2 on the surface of the substrate 7 heated by a heater 4. The two electrodes 2a, 2b are formed of the Mo-Ta alloy consisting of 12.3 to 62.9wt.% Mo and 37.2 to 87.8wt.% Ta in this case, by which the deterioration of the SiO2 thin film generated with the SiO2 dust during the formation of the SiO2 thin film is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electrode plate used in a plasma CVD apparatus.

(Prior Art) A plasma CVD apparatus generally has a structure shown in FIG. That is, 1 in the figure is a vacuum chamber. In this chamber 1, an upper electrode plate 2a and a lower electrode plate 2b are arranged parallel to each other. The upper electrode plate 2a
A high frequency power source 3 is connected to. Further, the lower electrode plate 2b has a built-in heater 4, and the lower electrode plate 2b is grounded. Further, two gas introduction pipes 5 for introducing a reaction gas into the chamber 1 are connected to the side wall of the chamber 1 so as to face each other. An exhaust pipe 6 is connected to the lower part of the chamber 1 to maintain a predetermined degree of vacuum in the chamber 1.

In the plasma CVD apparatus described above, the lower electrode plate 2a
After setting a desired substrate 7 thereon and evacuating the gas in the vacuum chamber 1 by operating a vacuum pump (not shown) connected to the exhaust pipe 6, a desired reaction gas (for example, S
iH4 and N20) and apply high frequency power from the high frequency power source 3 to the upper electrode plate 2a, the upper and lower electrode plates 2a
, generation of plasma by glow discharge between 2b, Si
A 3 t O* thin film is formed on the substrate 7 by the reaction between H4 and N20. By the way, the electrode plate incorporated in the plasma CVD apparatus has conventionally been made of stainless steel such as 5O8304. However, in a plasma CVD apparatus incorporating an electrode plate made of such a material, dust is generated during film formation of Sin and adheres to the substrate surface, resulting in an abnormal film formation phenomenon of the S L Ox thin film with the dust as a core. There have been problems such as generation of oxidation and deterioration of film quality. This kind of dust generation occurs when a SiOx thin film is formed not only on the substrate but also on the electrode plate when a thin film of Si is deposited on the substrate by plasma CVD. S i
It is thought that the Ox thin film 8 cracks, and then peels off and scatters as dust 9, as shown in FIG. 2(b).

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems, and is an electrode for a plasma CVD apparatus that suppresses dust generation caused by a thin film attached to the surface during plasma CVD. It is intended to provide a board.

(Means for Solving the Problems) The present invention is an electrode plate for plasma CVD characterized by being made of a Mo-Ta alloy.

As the above Mo-Ta alloy, Mo 12.3
~62.9% by weight, Ta 37.2~87.8% by weight
It is desirable to use one with a composition of

(Function) According to the present invention, by using an electrode plate made of a Mo-Ta alloy, an Si
Dust generation can be suppressed when forming a thin film of Ox or the like.

That is, the ease with which dust is generated can be estimated by examining the adhesion strength of the SiOx thin film to the electrode plate and the internal stress of the thin film depending on the material of the electrode plate. The plasma CVD electrode plate is in an unwarped state with the attached SiOx thin film,
Focusing on the thermal stress when restrained, the approximate S
The internal stress (σ, ) of iOx is expressed by the following equation (1).

However, E: longitudinal elastic modulus of the electrode plate E: longitudinal elastic modulus of attached thin film to; Thickness of electrode plate tl, thickness of thin film attached to electrode plate α　; Thermal expansion coefficient of electrode plate −α　; Thermal expansion coefficient of attached thin film T1: Substrate temperature during film formation To; normal temperature The fracture strength of SiO* is determined by σ being the tensile strength and σ being the compressive strength. If the intensity is σ, then σ is σ. It is 1/40 of that.

The ratio (k) to the internal stress is expressed as k-1σ/σ (2) t (and k is expressed by the following equation (3) from the relationship with the above equation (1).

Currently used stainless steel (5US304)ζ
Regarding the electrode plate and the electrode plate made of Mo-Ta of the present invention, Tl in the above formula (2) is 350°C, tr: 5I01 - 3
The ratio (k) to the internal stress in the case of 0 μm is calculated as follows.

E -7,14X 10' kg/as2,l
0x E = 1.97X 10'kg/'sa2,
E M 0-Ta-4×lO' kg/■2, α
SiOx -0,48XlO-h/'C1α5Us3
04-17.3X 10-6/'C1αNoi, -
5,99X 1G"/"C2! e；308304'″
2IIlゝL e, Mo-Ta-2'ar#s σc -5kg g! ' / s ta 2, by substituting each numerical value into the above equations (1) and (3), I';S
iOx/5US304-39' kgr/””・σl
';510x/Mo-Ta-''kgr/ll11'
,k;5IOx/5IJS304- ”ゝni;SiOx
/Mo-Ta" 2°6, and the ratio (k) to the internal stress is smaller than that of the conventional electrode plate made of Mo-Ta. The electrode plate consisting of a is made of Sin, and the attachment force of the thin film is 470 kgr/s+a2, and the attachment force of the SiOI thin film on the glass is 150 kgr/n+m2.
(1) About three times larger.

Therefore, the electrode plate made of the Mo-Ta alloy of the present invention is S
Because the iOm thin film has a strong adhesion force and low internal stress, it can be incorporated into a plasma CVD device to produce SiOw.
When depositing a thin film such as
n. Since the generation of cracks in the thin film can be suppressed, the generation of dust accompanying the generation of cracks can be suppressed. As a result, plasma CVD
In this method, a good and uniform 510 m thin film without deterioration of film quality due to dust adhesion can be formed on the substrate fixed to the electrode plate.

(Example) Examples of the present invention will be described in detail below.

Electrode plates made of 35wL96M o -65vt% Ta were incorporated as the upper and lower electrode plates 2a and 2b shown in FIG. After operating and exhausting the gas in the vacuum chamber l, the S from the gas introduction pipe 5
i H, and N20 are introduced, and high frequency power is applied from the high frequency power source 3 to the upper electrode plate 2a to separate the upper and lower electrode plates 2a,
Generation of plasma due to glow discharge between 2b, Sin,
A SiOm thin film was formed on the glass substrate 7 by the reaction between the SiOm and N20.

As a result, a 510W thin film with a good and uniform thickness can be formed on the glass substrate 7 without deterioration of the film quality due to the occurrence of dust due to Sin attached to the upper and lower electrode plates 2a and 2b, cracks in the thin film, and dust generated by peeling. was confirmed.

[Effects of the Invention] As detailed above, according to the electrode plate for a plasma CVD apparatus according to the present invention, it is possible to suppress the generation of dust caused by the thin film attached to the surface during plasma CVD. A film of good quality and uniform thickness is deposited on the substrate to be processed.
It has remarkable effects such as being able to form thin films such as .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a general plasma CVD apparatus, and FIGS. 2(a) and 2(b) are perspective views for explaining problems when using a conventional electrode plate. l... Vacuum chamber S 2a, 2b... Electrode plate,
3...High frequency power supply, 5...Gas introduction pipe, 6...Exhaust pipe.

Claims (1)

[Claims] Plasma CV characterized by being made of Mo-Ta alloy
Electrode plate for D.