JPH0448722A - Plasma cvd device - Google Patents

Abstract

PURPOSE:To prevent the deposition of a reaction product on a wafer holder electrode, to improve the quality of a product, to reduce maintenance operation and to enhance operating efficiency by installing a reaction-product adhesion preventive plate, to which a window hole corresponding to the size of a wafer is bored, between both electrodes and equalizing the potential of the reaction- product adhesion preventive plate and one electrode. CONSTITUTION:When high-frequency voltage is applied to reaction-gas leading- out electrodes 4, plasma is generated among the reaction-gas leading-out electrodes 4 and a wafer holder electrode 2 while plasma is also generated among the reaction-gas leading-out electrodes 4 and reaction-product adhesion preventive plates 7. No plasma is generated around wafers 3 in the presence of the reaction-product adhesion preventive plates 7, and reaction products deposit only on the wafers 3. The reaction products deposit on the peripheral section of the wafer holder electrode 2 by the creeping of plasma, but the quantity is a trace quantity in an insignificant extent. The peripheral section of the wafer holder electrode 2 is extruded from the wafers 3, thus obviating the deviate deposition of the reaction products in the peripheries of the wafers 3, then forming uniform reaction product films on the wafers 3.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to plasma CVD, which is one of semiconductor manufacturing equipment.
It is related to the device.

[Conventional technology] Semiconductors are deposited on silicon wafers,
They are manufactured through a multi-step process, and one of the processing devices is a plasma CVD (chemical vapor deposition) device.

Conventional plasma CVD system! This will be briefly described in FIGS. 5 and 6.

In the figure, reference numeral 1 denotes an airtight reaction vessel, and a wafer holder electrode 2 electrically insulated from the reaction vessel 1 is provided at the center of the reaction vessel 1 . The wafer holder electric 1II2 is connected to a high frequency power source for plasma generation (not shown). Further, the wafer holder electrode 2 is configured to hold the wafer 3 on both sides thereof.

Reaction gas lead-out electrodes 4 and 4 are provided facing each other on both sides of the wafer holder electrode 12, and the reaction gas lead-out electrodes 4 are grounded via the reaction vessel 1. Further, the reactive gas deriving electrode 4 has a large number of reactive gas deriving holes 5 on the surface facing the wafer holder electrode, so that a reactive gas from a reactive gas supply source (not shown) is blown into the reaction vessel 1. ing.

Note that 6 in the figure is a gas exhaust port.

A heater (not shown) is provided on the wafer holder electrode 2 and the reaction gas lead-out electrode 4 to heat the wafer 3.

In the CVD process, with the wafer 3 mounted on both sides of the wafer holder electrode 2, a low-pressure reaction gas heating atmosphere is created in the reaction vessel 1, and a high frequency voltage is applied between the wafer holder electrode 2 and the reaction gas lead-out electrode 4. Then, plasma is generated on the picture electrode 2.4.

Due to the generation of plasma, t# of reaction products accumulate on the surface of the wafer 3, and CVD processing is performed.

[Problems to be Solved by the Invention] However, since plasma is also generated in the wafer holder electrode 2 portion around the wafer 3, reaction products are also deposited on the wafer holder electrode 2.

The amount of reaction products deposited on the wafer holder electrode 2 increases with the number of wafers processed, and each wafer processing involves heating and cooling. It peels off from the wafer holder electrode 2 due to expansion and contraction due to thermal fluctuations of the holder electrode 2,
The particles become particles and contaminate the inside of the reaction vessel 1.

Then, such particles adhere to the wafer 3,
This causes problems such as deterioration of product quality or multi-layer structure.

Therefore, conventionally, wafers after processing are inspected periodically or at appropriate times to check the amount of particles attached to the wafer, and when the amount of particles exceeds a certain amount, the wafer holder electrode is cleaned.

For this reason, maintenance work has become troublesome and has caused a decrease in the operating rate of the device.

In view of these circumstances, the present invention aims to prevent reaction products from accumulating on the wafer holder electrode, thereby improving product quality, reducing maintenance work, and improving operating efficiency.

[Means for Solving the Problems] The present invention provides a plasma CVD apparatus in which a wafer is attached to one of electrodes arranged facing each other, plasma is generated between both electrodes, and reaction products are deposited on the wafer. , both′
! & A reaction product adhesion prevention plate having a window hole corresponding to the size of the wafer is provided between the electrodes, and the reaction product adhesion prevention plate and the one electrode are set at the same potential. It is.

[Function] When plasma is generated between both electrodes, plasma is also generated between the other electrode on which the wafer is not attached and the reactant product adhesion prevention plate. Therefore, plasma around the wafer is absorbed by the reaction product deposition prevention plate, no plasma is generated around the wafer, and no reaction product is deposited around the wafer on one electrode.

“Implementation ρ1” Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Components in FIGS. 1 and 2 that are the same as those shown in FIGS. 5 and 6 are designated by the same reference numerals, and their explanations will be omitted.

A reaction product deposition prevention plate 7 is provided between the wafer holder electrode 2 and the reactive gas outlet electrode 4. The reaction product adhesion prevention plate 7 is made of a conductive material (for example, metal), and has a window hole 8 formed in a portion facing the wafer 3 . Further, the reaction product adhesion prevention plate 7 is electrically connected to the reaction vessel 1 and has the same potential (including substantially the same potential) as the wafer holder electrode 2.

The wafer holder electrode 2 is made larger than the outer shape of the wafer 3 so that the peripheral part of the wafer holder electrode 2 is exposed around the wafer 3 and faces the reaction product adhesion prevention plate 7. .

The effect will be explained below.

When a high frequency voltage is applied to the reactive gas deriving electrode 4, plasma is generated between the reactive gas deriving electrode 4 and the wafer holder electrode 2, and plasma is generated between the reactive gas deriving electrode 4 and the reaction product adhesion prevention plate 7. plasma is also generated.

Due to the presence of the reaction product deposition prevention plate 7, no plasma is generated around the wafer 3, and reaction products are deposited only on the wafer 3. Incidentally, reaction products are deposited around the wafer holder electrode 2 due to the circulation of the plasma, but the amount is
The amount is so small that it is not a problem.

Furthermore, since the peripheral portion of the wafer holder electrode 2 protrudes from the wafer 3, reaction products are prevented from being deposited unevenly on the peripheral edge of the wafer 3.

Thus, a uniform reaction product film can be formed on the wafer 3 without the reaction products being deposited on the wafer holder electrode h electrode 2.

By preventing reaction products from depositing on the wafer holder electrode 2, the generation of particles, that is, the amount of particles adhering to the wafer, is significantly reduced. As shown in FIG. 7, in the conventional method, the number of particles of 25 μm or more attached to the wafer reaches 100 or more after 40 hours, but in the case of the present example, 8
Even after 0 hours, the amount of attached particles remains almost the same as at the beginning (see Fig. 4).

It goes without saying that the present invention can also be practiced in cases where a wafer is mounted on only one side of the wafer holder electrode, or where the reactive gas outlet is provided at a position below the reactive gas outlet electrode. do not have.

[Effects of the Invention] As described above, according to the present invention, it is possible to prevent reaction products from accumulating on the wafer holder electrode, thereby significantly reducing the generation of particles, improving product quality, improving maintainability, Various excellent effects can be achieved, such as improving the operating rate.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram showing one embodiment of the present invention, Fig. 2 is a view taken along the line A-A in Fig. 1, Fig. 3 is an explanatory diagram of a reaction product adhesion prevention plate, and Fig. 4 is a wafer Figure 5 is a basic configuration diagram showing a conventional example, Figure 6 is a view taken along the line B-B in Figure 5, and Figure 7 shows the amount of particles attached to a wafer. FIG. 1 is a reaction vessel, 2 is a wafer holder tS, 3 is a wafer, 4 is a reaction gas outlet electrode, 5 is a reaction gas outlet hole, 6 is a gas outlet, 7 is a reaction product adhesion prevention plate, and 8 is a window hole. . Figure 1 Figure 2

Claims (1)

[Claims] 1) In plasma CVD equipment, a wafer is attached to one of the electrodes arranged facing each other, plasma is generated between the two electrodes, and reaction products are deposited on the wafer. A plasma CVD apparatus characterized in that a reaction product adhesion prevention plate is provided with a window hole formed therein, and the reaction product adhesion prevention plate and the one electrode are at the same potential.