JPH04196221A - Chemical vapor growth apparatus - Google Patents

Abstract

PURPOSE:To supply a carrier gas which contains a reaction material always in definite quantities and to stably form a thin film by a method wherein the amount of the reaction material is measured in a state that it has been diluted with an alcohol. CONSTITUTION:Ethyl alcohol-diluted liquid tetraethoxysilane TEOS inside a material tank 2 is pressure-fed to a liquid mass-flow controller 3 by means of the pressure of N2 gas. By utilizing heat is removed according to a mass flow rate at the liquid mass-flow controller 3, the mass flow rate of the ethyl alcohol-diluted liquid TEOS is measured and fed accurately. Since the amount of the reaction material is measured in a state that it has been diluted with the alcohol, the liquid mass-flow controller 3 can be used near its full scale. As a result, the flow rate of the liquid reaction material can be supplied with good accuracy, and the carrier gas in which a definite amount is always contained can be supplied to the inside of a chamber. Thereby, the reaction gas can be supplied stably and a thin film having the same thickness can be formed on each semiconductor wafer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a chemical vapor deposition apparatus used in a semiconductor manufacturing process, and in particular to an alcoholate (salt of metal and alcohol)-based liquid reaction which is liquid at room temperature. The present invention relates to a chemical vapor deposition apparatus that forms a film on a semiconductor wafer using a gas that vaporizes a material.

[Conventional technology]

Figure 3 is a block diagram showing the reaction gas supply system of a conventional chemical vapor deposition apparatus.
5) Below 4 is abbreviated as TEO3], an example is shown in which N2 gas is used as a carrier gas and 03 gas is used as a gas to be reacted with TE01. In the figure, (1) is an ozone generator that partially converts supplied 02 into 03 by silent discharge;
) is a material tank that holds liquid TEO3 inside. (3)
(4) is a liquid mass flow controller that accurately measures the mass flow rate of the pumped liquid TEO8 and sends it out; (4) is a vaporizer that vaporizes the liquid TEO3 that has been accurately measured and sent out by heating a certain amount; (5) is the N2 gas containing TE01 from the vaporizer (4) and the ozone generator (1).
), a gas head that mixes 02 gas containing 03 from
(6) is a gas ejection surface of the heated semiconductor wafer (7) having a gas ejection port (not shown) for supplying the mixed gas.

Next, the operation will be explained. Thin film formation using a chemical vapor deposition apparatus is performed as follows.

The liquid TEO3 in the tank (2) is pumped to the liquid mass flow controller (3) by the pressure of N2 gas.

The liquid mass flow controller accurately measures and supplies the mass flow rate of the liquid TEO3 by utilizing the phenomenon in which heat is removed in accordance with the mass flow rate. In this example, the required amount of TE01 in liquid state is approximately 0.05 c c 7 min. The accurately metered and supplied liquid TEO3 is heated to a constant temperature in the vaporizer (4), and carrier N2 is added to sufficiently vaporize it to become N2 gas containing TEOS gas, which is then transferred to the pipe (8).
is fed into the gas head (5). In addition, piping (
8) is heated to prevent the vaporized TE01 from being reliquefied (not shown). In addition, the ozone generator (1) is supplied with 02 gas that is accurately measured by a mass flow meter (9).
A portion was changed to 03 and the same was sent to Suhesod (5).

As described above, the N2 gas containing TE01 and the 02 gas containing TE03 are supplied to the gas head (5), and the mixed gas is blown onto the heated and held semiconductor wafer (7) from the gas ejection surface (6). A thin film is formed by chemical vapor deposition.

In order to form the same thin film on each wafer, it is necessary to keep the supplied reaction gas (TE01 and TE03 concentration) constant. Regarding 03, it is sufficient to keep the supplied 0□ flow rate and the discharge power of the ozone generator (1) constant. TE0
In order to keep the gas flow rate of 1 constant, it is necessary to accurately meter and supply the liquid TEO 8 using the liquid mass flow controller (3).

(Problem to be solved by the invention) Since the conventional chemical vapor deposition apparatus is configured as described above, in order to keep the gas flow rate of TE01 constant, liquid TEOS must be accurately metered and supplied by a liquid mass flow controller. Is it necessary to do so?Currently, it is technically difficult to create a liquid mass flow controller with an extremely low flow rate.
The full scale is too large compared to the required amount. Second
The figure shows an example of the specifications of a commercially available liquid mass flow controller.
/min, accuracy or full scale ±2%, for example TE0
1, the required amount or liquid state is approximately 0.05 c c 7
minutes (lcc/min x O,02=0.02cc
/min] and 0.05±0.02 c c 7 minutes. Since the supply amount of liquid TEO3 fluctuates greatly in this way, the gas flow rate of vaporized TE01 fluctuates, resulting in a problem in that a thin film of the same thickness cannot be formed on each semiconductor wafer, causing a decrease in yield.

This invention was made to solve the above-mentioned problems, and it is possible to stably supply a reactive gas, thereby forming a thin film of the same thickness on each semiconductor wafer.
The purpose is to obtain a chemical vapor deposition device.

[Means to solve the problem]

The chemical vapor deposition apparatus according to the present invention measures the alcoholate-based liquid reaction material, which is liquid at room temperature, in the liquid phase, heats it, vaporizes it, and supplies the reaction material to the chamber. It was designed to be measured in a diluted state.

[Effect]

The reaction gas supply system of the chemical vapor deposition apparatus according to this invention includes:
Since the reaction material is measured diluted with alcohol, it can be used close to the full scale of the liquid mass flow controller, resulting in good accuracy (it can supply the flow rate of the liquid return material and always supply a constant amount of carrier gas into the chamber) It was used for

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to the drawings. In addition, in the embodiment of the present invention, tetraethoxysilane (S i (OC2H5)a hereinafter abbreviated as TEO3) is used as a liquid source.
An example will be explained in which N2 gas is used as a carrier gas and 03 gas is used as a gas to be reacted with TE01. In Figure 1,
In (1), the supplied 02 is partially 0 by silent discharge etc.
．． Ozone generator (2) has liquid TEO3 inside.
A material tank that holds. (3) is the pumped liquid TEO
(3) is a liquid mass flow controller that accurately measures and sends out the mass flow rate; (4) is a vaporizer that vaporizes the liquid TEOS that has been accurately measured and sent out by heating and carrier N2; (5) is a vaporizer (4) ) containing TE01 from
2 gas, and 0.2 gas from the ozone generator (1). 0 containing
A gas head (6) for mixing two gases is a gas ejection surface having a gas ejection port (not shown) for supplying the mixed gas to the heated and held semiconductor wafer (7). The full scale of the liquid mass flow controller is lcc/min, and the accuracy is ±2% of the full scale, and the liquid TEO3 in the material tank (2) is diluted to exactly 10% with ethyl alcohol (C2Hs OH).

Next, the operation will be explained. Thin film formation using a chemical vapor deposition apparatus is performed as follows.

Ethyl alcohol dilution liquid TEO in material tank (2)
S is pumped to the liquid mass flow controller (3) by the pressure of N2 gas. The liquid mass flow controller accurately measures and supplies the mass flow rate of the ethyl alcohol diluent liquid TEO3 by utilizing the phenomenon in which heat is removed in accordance with the mass flow rate. As mentioned above, in this example, the required amount or TEO3
Since the liquid state is approximately 0.05 cc 7 minutes, liquid TEO3 diluted to 10% with ethyl alcohol (
0.05 ccZ minute 10, l = 0.5 cc /
All you have to do is pour out the amount. Also, the full scale of the liquid mass flow controller is lcc/min, and if the accuracy is ±2% of the full scale, then (Icc/min x 0.02 = 0.02
It can be accurately metered and dispensed at c c /dose of 0.05±0.02 c c 7 minutes. Accurately measured ethyl alcohol diluent liquid TEO3 is heated to a constant temperature in a vaporizer (4), becomes carrier N2 gas, and is sent to a gas head (5) through a pipe (8). Note that the pipe (8) is heated to prevent the vaporized material from being reliquefied (not shown). In addition, the ozone generator (1) is supplied with 0° gas that is accurately measured by a mass flow meter (9), and a portion of the gas is changed to 03, which is also supplied to the gas head (5).
sent to. As above, gas head (5)
N2 gas containing accurate amounts of TE01 and ethyl alcohol, and 02 gas containing 03 are supplied and mixed, and the semiconductor wafer (7) heated and held from the gas ejection surface (6) is blown with the mixed gas, Chemical vapor deposition forms a thin film of equal thickness on each semiconductor wafer. Note that, like TE01, ethyl alcohol has an alkyl group and a very similar structure, so the dilution effect does not adversely affect film formation.

In the above embodiment, the required amount of the material or the liquid state is about 0.
05 Cc/min, full scale of liquid mass flow controller or Icc/min, accuracy or full scale ±296, so liquid TEO8 should be diluted to 10% with alcohol, or the dilution amount may be different than actual conditions. It's okay. In short, it is a good idea to dilute the liquid reaction material so that it can be used close to the full scale of the liquid mass flow controller. - Further, in the above embodiment, TE01 (
Tetraethoxysilane) or a liquid material that can be vaporized and reacted is sufficient. A liquid material for doping impurities into the film, such as trimethyl orthophosphate (PO(
OCH,), abbreviation TMP), trimethyl oxalate CB (
OCR, ), abbreviated as TMOB) requires even less flow rate and is highly effective.

Further, in the above embodiment, ethyl alcohol was used as the alcohol to be diluted, but since alcoholade-based liquid materials are generally soluble in alcohol, any alcohol may be used.

Furthermore, although N2 gas was used as the carrier gas, any inert gas suitable for chemical vapor deposition may be used.

Also, 03 gas was used as the gas to react with the reaction material,
There is no need for this, and there may be cases where it is not necessary.

〔Effect of the invention〕

As described above, according to the present invention, an alcoholate-based liquid reaction material that is liquid at room temperature is measured in the liquid phase, and then heated, vaporized, and a chemical vapor deposition system having a reaction gas supply system that supplies the gas to the chamber. In this method, since the reaction material is measured diluted with alcohol, a carrier gas containing a constant amount of the reaction material can be constantly supplied into the chamber, and a thin film can be stably formed. As a result, a thin film having the same thickness can be formed on each semiconductor wafer, and an improvement in yield can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a chemical vapor deposition apparatus according to the present invention. In the figure, (2) is a material tank, (3) is a liquid mass flow controller, (4) is a vaporizer, (5) is a gas head, (6) is a gas ejection surface, and (7) is a semiconductor wafer. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a chemical vapor deposition system with a reaction gas supply system, the alcoholate-based liquid reaction material, which is a liquid at room temperature, is measured in its liquid phase, then heated, vaporized, and supplied to the chamber, and the reaction material is measured diluted with alcohol. A chemical vapor deposition apparatus characterized by: