JPS5847464B2 - Aluminum tree - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for depositing aluminum in a vapor phase, and more particularly to a method for depositing an electrode on a semiconductor substrate by depositing aluminum in a vapor phase. This invention relates to a method of chemically vapor-extending aluminum onto a semiconductor substrate by reaction.

Conventionally, the so-called method of elongating aluminum to form electrodes or wiring on a semiconductor substrate is as follows.
Vapor deposition methods were common.

However, since the evaporation source is point-like in the vapor deposition method, there is a problem that the surface to be vapor-deposited has directionality, which may cause defects in the aluminum film at the edges of the surface to be vapor-deposited, leading to the risk of wire breakage. There was a drawback that there was.

Further, the vapor deposition method has problems in terms of mass production and cost as a method for forming an aluminum layer on a semiconductor substrate or an insulating film.

Other methods of growing aluminum on the surface to be deposited include chemical vapor deposition, such as aluminum chloride (A
There is a method of heating aluminum (lCl3) and hydrogen (H2) to 1000°C or more to react and elongate aluminum in the gas phase, but this method requires high-temperature operation and therefore eliminates unnecessary impurities in the semiconductor substrate. Diffusion may occur, which may change the resistance of the diffusion region or cause aluminum to form an alloy with silicon, which is undesirable.

Therefore, an object of the present invention is to eliminate the drawbacks of the conventional method of depositing aluminum vapor phase on a semiconductor substrate or insulating film, and to use a low-temperature aluminum vapor deposition method that does not cause disconnection at the edges of the surface to be deposited. The purpose of this invention is to provide a method of reversal.

The method of vapor phase vaporization of aluminum according to the present invention involves exciting an organic aluminum compound with high frequency under reduced pressure of 0.1 to 30 mmHg to bring it into a plasma state, and forming aluminum on a semiconductor substrate at low temperature in vapor phase. It is constructed by making it longer.

The organoaluminum compound used in the present invention is about 10
It contains organoaluminum compounds having a vapor pressure of about 1 nrILHg at a temperature of 0° C. Examples include trimethylaluminum, triethylaluminum, triisobutylaluminum, trisdimethylaminoaluminum, and the like.

Hereinafter, the method of the present invention will be explained with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing an example of a plasma reactor used in the vapor phase elongation method of aluminum according to the present invention.
A semiconductor substrate 1 on which aluminum is to be deposited in a vapor phase is inserted inside.

For example, a reaction tube 2 made of quartz glass has a high frequency coil 3 wound around its outer periphery.

The high frequency coil 3 is connected to a suitable high frequency power source 4.

The inlet of the reaction tube 2 is connected through a pipe 5 to a storage cylinder 7 containing an organoaluminum compound 6, and the storage cylinder 7 is held in a suitable constant temperature heating tank 8.

The storage cylinder 7 is further passed through a pipe 9 and a flow meter 10,
It is connected to a carrier gas supply device (not shown) such as N2 or ■2.

On the other hand, an appropriate vacuum pump (not shown) is connected to the outlet of the reaction tube 2 through a pipe 13, and the reaction tube 2 is evacuated during the operation of vaporizing aluminum onto the semiconductor substrate.

The reaction tube 2 also has a carrier gas supply device (not shown).
A carrier gas such as N2 or H2 from a flowmeter 11,
It is directly supplied to the reaction tube 2 through the piping 12, and the reaction tube 2
The aluminum film is equipped to remove impurity gases inside the aluminum film, to clean it, and to make the thickness of the elongated aluminum film uniform.

In FIG. 1, reference numeral 14 indicates a twenty-one dollar valve.

An example of a method for vaporizing aluminum on a semiconductor substrate using a plasma reaction apparatus as shown in FIG. 1 is as follows: triethylaluminum Al(C2H5)3 is put in a storage cylinder 7 as an organic aluminum compound,
The temperature of the constant temperature heating tank 8 is set to 60°C.

At this temperature, the vapor pressure of triethylaluminum is 6 mm.
It becomes Hg.

The heating temperature varies depending on the type of organoaluminum compound used, but trimethylaluminum Al(CH,)
3 is practical at about 35°C, and the vapor pressure at this temperature is 20mmH9.

Also, triisobutylaluminum l-kl (iC4
H4)3 is practical at about 700G, and its vapor pressure at this temperature is 10mmHg.

Next, the sample semiconductor substrate 1 is inserted into the reaction tube 2, and the internal pressure of the reaction system is sucked to a vacuum of 1 mmHg using a vacuum pump.
Approximately 15M from the high frequency coil 3 using the W high frequency power supply 4
While applying a high frequency electromagnetic field of l{z, the carrier gas flows into the reaction tube 2 through the flowmeter 10, piping 9, storage cylinder 7, and piping 5, and Al(C2H5)3 vapor is introduced into the reaction tube 2.

Al(C2H5)3 that has entered the reaction tube 2 is excited by a high frequency electromagnetic field and becomes a plasma state, causing a chemical reaction shown by the following formula (1), and aluminum is deposited on the semiconductor substrate 1 in a vapor phase. do.

? The temperature of the semiconductor substrate during the vapor phase elongation operation is 100°C.

This temperature varies depending on the type of organoaluminum compound used, but generally trimethylaluminum can be carried out at 80 to 400°C.

Triisobutyl alcohol and triethylaluminum can also be used at similar temperatures.

Above, we have described a method in which the organoaluminum compound is held in a liquid state in a container (cylinder) and a carrier gas is passed through it to introduce the organoaluminum compound vapor into the reaction tube. A method of preparing a gas mixture of about 1% of an organic alumium compound and nitrogen or argon gas and supplying this directly to the reaction tube 2 can also be used.

Figures 2 and 3 show a case where an aluminum film is deposited on a semiconductor substrate with an insulating film selectively formed on the surface using conventional vacuum deposition (Fig. 2) and an aluminum film of the present invention. FIG. 3 is an explanatory diagram showing a typical example of a case (FIG. 3) in which an aluminum film is grown in a vapor phase on a semiconductor substrate with an insulating film formed on the surface using the phase growth method; A case is shown in which an aluminum film 17 is formed on the insulating film (Sin2) 16 on the insulation film 15.

As is clear from the figure, in the conventional vacuum evaporation method, a complete aluminum coating is formed on a part shaped like part B, but some wire breakage may occur in a part shaped like part A. In the case of a shape like part C, the edge portion D of the insulating film becomes a hindrance, resulting in a defective portion of the aluminum film.

On the other hand, in the vapor phase growth method of the present invention, a complete aluminum film is formed on all of the A, B and C parts.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a plasma reaction apparatus used in the vapor phase elongation method of aluminum according to the present invention. Figure 2 shows hair on a semiconductor substrate using the conventional vacuum evaporation method!
FIG. 3 is an explanatory view showing a typical example when reminium is vapor-deposited, and FIG. 3 is an explanatory view showing a typical example when the vapor phase elongation method of the present invention is used. 1...Semiconductor substrate, 2...Reaction tube, 3
...High frequency coil, 4...High frequency power supply, 5,9.12 and 13...Piping, 6...
... Organoaluminum compound, 7 ... Storage cylinder, 8 ... Constant temperature heating tank, 10 and 11 ...
...Flowmeter, 14...21 dollar valve, 15...
... Substrate, 16 ... Insulating film, 17 ... Curved aluminum film.

Claims (1)

[Claims] 1. In a method of growing aluminum on a semiconductor substrate in a vapor phase, an organoaluminum compound is grown in an O. l~30mm
Excite Hg with high frequency under reduced pressure to create a plasma state,
A method for vapor phase growth of aluminum, characterized by vapor phase growth of aluminum on a semiconductor substrate at low temperatures.