JPH059720A - Bias sputtering method - Google Patents

Abstract

PURPOSE:To provide a bias sputtering method which can easily control a sputtering speed and an etching speed. CONSTITUTION:A gas introducing pipe 14 is provided with two introducing pipes 14a, 14b. The introducing pipe 14a introduces gaseous argon (Ar) and the introducing pipe 14b introduces gaseous xenon (Xe). The gaseous argon and the gaseous xenon are mixed at a prescribed volumetric ratio and the gaseous mixture composed thereof is fed into a static chamber 12 by opening valves 16a, 16b. The gaseous mixture is ionized to generate a glow discharge, by which sputtering is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bias sputtering method for forming a thin film for electrode wiring on a semiconductor device.

[0002]

2. Description of the Related Art A sputtering method is mainly used as a metallization technique for semiconductor integrated circuits. The sputtering method has a feature that a metal film can be easily formed, but has a drawback that the step coverage is poor. Among the sputtering methods, the bias sputtering method is an effective method for improving this drawback,
By applying a negative bias voltage to the substrate, the film deposited on the substrate is etched and formed.

[0003]

By the way, the number of atoms (sputtering rate) jumping out from the target surface when one ion is incident on the target depends on the type of ion and the energy, the ion incident angle, the target material, and It changes depending on the target crystal structure and plane orientation.
If the sputtering rate is different, naturally, the sputtering rate (film formation film thickness per unit time) and the etching rate using the ion sputtering effect also differ. In the conventional bias sputtering method, one type of positive ions sputters the target and etches the film deposited on the substrate, so if you decide the type of ions to make the sputtering rate optimal, Correspondingly, the etching rate was also determined, and the etching rate could not be controlled. As described above, in the conventional method, it is not possible to individually control each of the sputtering rate and the etching rate to be the optimum rate,
Therefore, even in the bias sputtering method, the problem of step coverage remains.

The present invention has been made under the above circumstances, and an object thereof is to provide a bias sputtering method capable of easily controlling the sputtering rate and the etching rate.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention is directed to discharging ions in a vacuum chamber to cause ions to collide with a target to deposit particles constituting the target on a substrate and to bias the substrate. In the bias sputtering method in which the thin film is etched by applying a voltage, a plurality of kinds of rare gases are introduced into the vacuum chamber to perform the discharge.

[0006]

According to the present invention, as the discharge gas, a mixture of plural kinds of rare gases is used. When a plurality of types of rare gases are used, the sputtering rate and the etching rate depend on the volume ratio of the rare gas. Therefore, the sputtering rate and the etching rate can be easily controlled by changing the volume ratio of the rare gas used.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a bias sputtering apparatus used in a bias sputtering method which is an embodiment of the present invention.

The bias sputtering apparatus shown in FIG. 1 includes a sputtering chamber (vacuum chamber) 12 and a gas introducing pipe 14 for introducing a discharge gas into the sputtering chamber 12.
An exhaust pipe 18 for exhausting the discharge gas in the sputtering chamber 12, a substrate 24 having a silicon dioxide film deposited on a silicon wafer, a substrate holder 26 for holding the substrate 24, and a target formed of aluminum (Al). Two
8 and a target holder 3 for holding the target 28
2, an anode 34 having an opening, a DC power supply 36,
And 38.

The gas introducing pipe 14 can introduce two kinds of mixed gas, and the introducing pipe 14a introduces argon (Ar) gas and the introducing pipe 14b introduces xenon (Xe) gas. Valves 16a and 1 for adjusting the flow rates of argon gas and xenon gas are provided in the introduction pipes 14a and 14b, respectively.
6b is provided. The exhaust pipe 18 is connected to a vacuum pump 22, and the vacuum pump 22 reduces the pressure in the stack chamber 12 to maintain a predetermined vacuum state.

The substrate holder 26, the target 28 and the anode 34 are arranged parallel to each other, and the substrate holder 26
The target 28 serves as a cathode. The DC power supply 36 is a power supply for generating glow discharge, and is connected to the anode 34 and the target 28. The anode 34 is grounded. On the other hand, the DC power source 38 is connected to the anode 34 and the substrate holder 26 and applies a negative bias voltage to the substrate holder 26. Further, in order to prevent the temperature of the substrate 24 and the target 28 from rapidly rising due to collision of ions and atoms, the substrate holder 26 and the target holder 32 are provided with a cooling device (not shown). The substrate holder 26 may be rotatable.

Next, the operation of forming a thin film on a substrate using the bias sputtering apparatus of this embodiment will be described. First, the valves 16a and 16b are opened, argon gas and xenon gas are mixed at a predetermined volume ratio, and this mixed gas is sent into the sputtering chamber 12. The gas pressure in the sputtering chamber 12 is set to 10 ⁻² to 1 by the vacuum pump 22.
Direct current power is applied between the anode 34 and the target 28 and between the anode 34 and the substrate holder 26 at 0 ⁻¹ Torr. Glow discharge is generated between the substrate holder 26 and the target 28, and the argon gas and the xenon gas are dissociated. Most of the positive ion argon ions (Ar ⁺ ) and xenon ions (Xe ⁺ ) collide with the surface of the target 28 which is the cathode, and repel aluminum atoms. The ejected aluminum atoms obtain sufficient energy by the argon ions and the xenon ions, fly toward the substrate 24, and adhere to the surface of the substrate 24 as a film. Since a negative bias voltage is applied to the substrate holder 26 with respect to the anode 34, part of the argon ions and the xenon ions flow into the substrate holder 26. These ions collide with the surface of the substrate 24 and etch the aluminum film deposited on the substrate 24 due to the sputtering effect. As described above, in the bias sputtering method, the film formation process proceeds while the aluminum film is formed on the substrate 24 and simultaneously etched. The discharge gas is limited to the rare gas because the other types of gas react with the atoms forming the target 28, and the sputtering rate is low.

In the bias sputtering method of this embodiment, a discharge gas containing two kinds of rare gases mixed at a predetermined volume ratio is used. The sputtering rate changes depending on the type of ions, has a maximum in a rare gas, and tends to increase as the atomic number increases. When a plurality of gases are mixed, the sputtering rate is the sum of the sputtering rate of each ion multiplied by the volume ratio of each gas as a weight. Therefore, by changing the type of each rare gas or the volume ratio of the rare gas, the sputtering rate, which is the film thickness of the aluminum film per unit time, and the etching rate of the aluminum film can be changed. Moreover,
The sputter rate and the etching rate have different dependences on the type of each rare gas and the volume ratio of the rare gas. Therefore, the sputtering rate and etching rate can be easily controlled by changing the volume ratio of the rare gas in the film forming operation.
The overall deposition rate can be adjusted to the optimum rate. That is, according to the present embodiment, by selecting an appropriate rare gas and adjusting the volume ratio of each rare gas, it is possible to control the etching rate to an optimum rate, so that compared to the conventional bias sputtering method. The step coverage can be improved.

Further, in this embodiment, since the substrate holder, the target and the anode are arranged in parallel with each other,
Aluminum atoms repelled by argon ions and xenon ions are evenly attached to the substrate. Further, since the aluminum film is uniformly etched by the argon ions and the xenon ions, the uniformity of film formation can be further improved. Furthermore, in order to carry out the bias sputtering method of the present embodiment, it is only necessary to provide a conventional bias sputtering apparatus with a gas introducing pipe having a plurality of introducing pipes, so that the present invention can be easily implemented with a simple configuration. it can.

In the present embodiment, the case where the magnetic field is not applied to the cathode part has been described, but the present invention is not limited to this, and a magnetron type cathode in which a magnet is arranged inside the cathode is used. May be.

In the above embodiment, the case where the discharge gas is a mixture of two kinds of rare gases has been described, but the present invention is not limited to this, and three or more kinds of discharge gases are used. You may use the mixture of these rare gases.

Further, in the above embodiment, the case where the bias sputtering apparatus for applying the DC voltage between the electrodes is used to generate the glow discharge has been described, but the present invention is not limited to this. Alternatively, a sputtering device that applies a high frequency voltage between the electrodes may be used.

[0017]

As described above, according to the present invention, by using a mixture of several kinds of rare gases as the discharge gas, the volume ratio of the rare gases can be changed to facilitate the sputtering rate and the etching rate. Since it can be controlled, it is possible to provide a bias sputtering method capable of controlling the overall film formation rate and forming a thin film more uniformly than in the conventional apparatus.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a bias sputtering apparatus used in a bias sputtering method which is an embodiment of the present invention.

[Explanation of symbols]

 12 sputter chamber 14 gas introduction pipe 14a, 14b introduction pipe 16a, 16b valve 18 exhaust pipe 22 vacuum pump 24 substrate 26 substrate holder 28 target 32 target holder 34 anode 36, 38 DC power supply

Claims (1)

Claim: What is claimed is: 1. Discharge in a vacuum chamber to collide ions with a target to deposit particles constituting the target on a substrate and to apply a bias voltage to the substrate to etch the thin film. In the bias sputtering method, the discharge is performed by introducing a plurality of kinds of rare gases into the vacuum chamber, and the discharge is performed.