JPH0250955A - High-efficiency sheet plasma sputtering method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a sputtering method that provides high efficiency and high film formation speed.

[Prior art] A pressure gradient type plasma gun and a method for transforming plasma into a sheet shape are described in Shinku Vol. 25, No. 10 (published in 1982).
It is described in JP-A-59-27499, page 660, etc. A pressure gradient type plasma gun has an intermediate electrode interposed between the cathode and anode, and discharges while maintaining the cathode region at about I Torr and the anode region at about 10-3 Torr. In addition to not damaging the cathode due to ion backflow, the gas efficiency of the carrier gas used to create the discharge electron flow is dramatically higher than that of a discharge type without an intermediate electrode (large current discharge is possible). Sheet plasma, which is produced by ejecting plasma from such a pressure gradient plasma gun and deforming it into a sheet shape using magnetic means, is highly dense and can be made into a large area, so it is suitable for the ion blating method. It can be applied to thin film forming methods such as , CVD method, vacuum evaporation method, etc. In such cases, a highly reactive sheet is used as a means to ionize or excite the particles evaporated from the evaporation source or the gas introduced. Because plasma is used, the film formation process is not affected by fluctuations in the output of the plasma generation DC power supply (hereinafter referred to as plasma generation power supply) applied to the pressure gradient plasma gun. do not have.

[Problems to be Solved by the Invention] However, when applying such a sheet plasma to a sputtering method, the sheet plasma is used not only as an ionization or excitation means as described above (but also as a means for supplying ions for sputtering a target). Therefore, fluctuations in the output of the plasma generation power source have a great effect on the sputtering process.In other words, in the sheet plasma sputtering method, high-density ions existing in the sheet plasma are connected to the anode, which has a negative potential with respect to the plasma. If a plasma generation power source with large ripples and no stabilization measures is used in order to accelerate toward the target placed in the target and sputter the target material at high speed, abnormal discharges will occur frequently. The electric current a (hereinafter referred to as sputtering power supply) used to keep the target at a negative potential with respect to the plasma is affected by output fluctuations of the plasma generation power supply, and the sputtering current and voltage fluctuate, effectively achieving high efficiency sputtering. The problem was that it was not carried out.

[Means for Solving the Problems] When a DC power source with large output fluctuations is used as a plasma generation power source, the impedance of the generated plasma also fluctuates accordingly. When a sputtering power source is applied to this plasma, the sputtering current and voltage vary greatly due to variations in plasma impedance. As a result, the sputtering speed also fluctuates as the sputtering current and voltage fluctuate, making it difficult to control the sputtering speed and making it impossible to obtain a high-quality thin film. moreover,
Abnormal discharges also occur frequently, sputtering becomes intermittent, and efficient film formation is not performed. Thus, the inventor
In order to realize high-speed sputtering using high-density sheet plasma, it was revealed that stabilization of the plasma generation power supply, that is, stabilization of plasma impedance, was essential.As a result of intensive research, the output fluctuation of the plasma generation power supply was found to be indispensable. By reducing the output to less than 10% of the output, the plasma impedance is significantly stabilized, and fluctuations in the sputtering power source are suppressed. As a result, sputtering power can be effectively applied to the target, and sputtering can be performed at an unprecedented high speed. It has been found that highly efficient sputtering is possible.

The present invention was made as a result of such research to solve the problems that the conventional sputtering method described above had.
Generate plasma by applying a DC power supply of 0% or less, transform the plasma into a sheet, accelerate the ions in the sheet plasma to a target, perform sputtering three times, and place it facing the target. The present invention provides a highly efficient sheet plasma sputtering method characterized by forming a film on a substrate.

FIG. 1 shows an example of an apparatus for carrying out the highly efficient sheet plasma sputtering method of the present invention.

1 is a pressure plate Otsu type 1 plasma gun having a cathode 20 and intermediate electrodes 21 and 22, which forms an arc discharge between the anode 3 which is placed at a positive potential by a plasma generation power source 5, and has a cylindrical shape. Generates plasma flow. This cylindrical plasma flow is deformed into a sheet shape by a pair of magnets 2.
A sheet plasma 4 is formed toward the anode 3 by the magnetic field 11 generated by the air-core coil 10.

Sputtering is performed by direct current power source (hereinafter referred to as a sputtering power source) 8 that maintains the target 7 at a negative potential with respect to the sheet plasma to a target 7 that is kept at a negative potential with respect to the sheet plasma. This is accomplished by accelerating ions, colliding with the target as sputtering gas ions, and sputtering the target material. The sputtered particles adhere to the substrate 9, forming a thin film.

A feature of the present invention is that a DC power source whose output fluctuation is within 10% of the output is used as the plasma generation power source 5.

Furthermore, a DC power supply with a desired smoothing circuit added to a normal DC power supply with an output fluctuation of 10% or more to improve the overall output fluctuation to 10% or less can also be used as a plasma generation power supply. Such a smoothing circuit is not particularly limited, but as shown in FIG. 1, an effective means is to connect a capacitor O in parallel to a DC power source 51 to form the plasma generation power source 5.

In addition to suppressing the output fluctuation of the plasma generation power source within 10% in this manner, it is more preferable to add a desired smoothing circuit to the sputtering power source.

[Function] In the present invention, by using a plasma generation power source with small ripples that suppresses output fluctuations to 10% or less, plasma impedance can be stabilized and fluctuations in the sputtering power source can be reduced. As a result, the sputtering power to the target can be reduced. can now be applied effectively, realizing a sputtering method with unprecedented speed and efficiency.

[Comparative example] A DC power supply (Max 250 A, 10
0V) was set to 60V, an output fluctuation of about 150% was observed (see Figure 4).

When sputtering was performed using this power source as a plasma generation power source, abnormal discharge occurred frequently and the impedance of the generated plasma also varied.As a result, the target placed on the top surface of the sheet plasma
When a negative voltage was applied, the sputtering voltage varied greatly as shown in FIG. When an ITO film was formed on a glass substrate using indium oxide (ITO) containing tin as a target, the film formation rate was 2500 persons/min. (See Table 1 above) [Example 1] A DC power supply similar to the comparative example with a total capacity of 400 as a smoothing circuit.
When the plasma generation power source was set to 60V using mF capacitors connected in parallel, the output fluctuation was 10
% (see Figure 2). When sputtering was performed using such a plasma generating power source, almost no abnormal discharge was observed. Further, the fluctuation rate of the sputtering voltage was also about 6% (see FIG. 3). When an ITO film was deposited in this state, the deposition rate was 400%.
The speed was 0 people/minute. (See Table 1 above) [Example 2] A DC power supply similar to the comparative example with a total capacity of 470 as a smoothing circuit.
Table 1 shows the results of forming an ITO film using a parallel-connected mF capacitor as a plasma generation power source.

[Example 3] A DC power supply similar to the comparative example with a total capacity of 560 as a smoothing circuit.
Table 1 shows the results of forming an ITO film using a parallel-connected mF capacitor as a plasma generation power source.

As described above, according to the present invention, sputtering power can be applied effectively, making it possible to perform highly efficient sputtering in which the ITO film formation rate is twice as fast as when the sputtering voltage fluctuates greatly. Understood.

[Effects of the Invention] As a result of the present invention, it becomes possible to effectively input sputtering power to the target, and it becomes possible to fully utilize the characteristics of high-efficiency sputtering using sheet plasma. That is, in sheet plasma using arc discharge, the degree of ionization of the sputtering gas is about 100 times higher than in glow discharge used in conventional sputtering, so a very high sputtering rate can be obtained even with the same applied voltage. At the same time, the sputtered particles pass through a highly ionized plasma and reach the substrate, increasing their chemical activation. As a result, it is possible to obtain a film formation rate that is unprecedentedly high, and it also becomes possible to form a film on a low-temperature substrate.

This effect is even more pronounced in reactive sputtering.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of an apparatus for performing the high-efficiency sheet plasma sputtering method of the present invention, FIG. 2 is an output voltage waveform of the plasma generation power source of Example 1, and FIG. 3 is the output of the sputtering power source of Example 1. Voltage waveforms; FIG. 4 shows the output voltage waveform of a plasma generation power source of a comparative example, and FIG. 5 shows an output voltage waveform of a sputtering power source of a comparative example.

Claims (1)

[Claims] 1. In a pressure gradient type plasma gun, the output fluctuation is 1 of the output.
A DC power supply of 0% or less is applied to generate plasma, the plasma is transformed into a sheet shape, ions in the sheet plasma are accelerated to a target, sputtering is performed, and a substrate placed opposite the target is sputtered. A highly efficient sheet plasma sputtering method characterized by forming a film. 2. High-efficiency sheet plasma sputtering according to claim 1, characterized in that a smoothing circuit is added to the DC power supply applied to the pressure gradient type plasma gun, and sputtering is performed with output fluctuations reduced to within 10% of the output. Method. 3. The high-efficiency sheet plasma according to claim 2, characterized in that a capacitor is connected in parallel to a DC power supply applied to a pressure gradient type plasma gun, and sputtering is performed with output fluctuations reduced to within 10% of the output. Sputtering method.