JPH024674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a sputtering apparatus capable of improving the purity of a sputtered film.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, sputtering has been widely used to form thin films on various members including semiconductor devices, magnetic recording media, and the like. As is well known, sputtering involves applying a voltage of several hundred volts between an anode and a cathode to generate a glow discharge, and the target metal placed around the cathode is blasted out by ions in the plasma. Metal atoms are attached to the top. In particular, magnetron sputtering can generate high-density plasma, and the movement of electrons can be restrained by magnetic and electric fields, so the amount of electrons flowing into the substrate can be suppressed and the temperature of the substrate can be increased. It has the advantage of suppressing the rise.

By the way, in order to increase the purity of film formation in sputtering, high purity Ar gas with low partial pressures such as O ₂ and H ₂ O is used, and the partial pressures of O ₂ , N ₂ , CO, and H ³ in the sputtering chamber are need to be lowered. This is because these gases react with the sputtered metal, resulting in a decrease in the purity of the film formed.

However, there is always a limit to reducing background pressure. Especially under vacuum, O ₂ ,
Gases such as H ₂ O often adhere to the inner surface of the vacuum container and are not completely evacuated.

Therefore, it may be possible to reduce the proportion of the gas components incorporated into the film by forming the film at a rate faster than the reaction rate between the residual gas and the sputtered metal. In order to increase the film formation rate, it is sufficient to increase the power input during sputtering.

However, in normal sputtering, more than 90% of the sputtering power turns into heat on the target surface, causing a rise in the temperature of the target, so if the input power is increased, the target cannot be cooled in time, causing problems such as bonding peeling. It was hot. Furthermore, as the temperature of the target atoms increases, the amount of heat transferred to the substrate also increases, resulting in a significant rise in the temperature of the substrate, resulting in the problem that it cannot be used for forming thin films on plastics, precision parts, etc.

[Purpose of the invention]

The present invention has been made based on this problem, and its object is to provide a sputtering apparatus that can form a sputtered film of high purity without raising the temperature of the target or substrate.

[Summary of the invention]

The present invention includes a nozzle that intermittently discharges an inert gas onto a target placed between a cathode and an anode, and a voltage that is intermittently applied between the cathode and anode in synchronization with a gas pulse from the nozzle. It is characterized by being equipped with a sputter power supply that applies .

〔Effect of the invention〕

In conventional continuous sputtering, the limit value of the film formation rate was 1 to 2 μm/min, but according to the present invention, intermittent sputtering is performed, so that By inputting approximately 10 times more power than conventional methods, it is possible to increase the deposition rate during sputtering by approximately 10 times while keeping the average deposition rate to the conventional limit value that does not cause damage to the substrate or target. can. Therefore, a sputtered film can be formed at a faster rate than the reaction rate between the residual gas in the vacuum container and the sputtered metal, so the residual gas components introduced into the film can be kept low, resulting in the formation of a highly pure film. can.

In addition, according to the present invention, it is only necessary to create gas pulses in the amount necessary for discharge on the target, so the amount of gas required is about 1/10 or less compared to conventional methods, and the average sputtering pressure is reduced from 1 to 0.1 Pa compared to conventional methods. The pressure can be lowered to 0.1 to 0.01 Pa, which has the effect of extending the life of the vacuum pump.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a sputtering apparatus according to this embodiment.

That is, inside the vacuum container 1, a cathode 2 and an anode 3 are arranged facing each other. The cathode 2 is connected to a sputter power source 4, and the anode 3 is grounded. A target 5 is fixed to the upper surface of the cathode 2 by, for example, soldering. A substrate 6 is supported by a substrate holder 7 and is disposed at a position facing the target 5 with the anode 3 interposed therebetween.

On the other hand, Ar gas supplied from an Ar gas supply source (not shown) is introduced into a gas container 10 disposed inside the vacuum container 1 via an introduction pipe 8 and a flow rate control valve 9. The gas contained in the gas container 10 is injected onto the target 5 via a solenoid valve 11 and an injection nozzle 12. Further, the gas inside the vacuum container 1 is removed from the exhaust pipe 13 and the exhaust valve 1.
Exhaust via 4.

Additionally, this device is equipped with a pulse controller 15. This pulse output from the pulse controller 15 is given to the solenoid valve 11 and the sputter power source 4.

In the sputtering device configured in this way,
Ar gas introduced through the introduction pipe 8 and the control valve 9 is stored inside the gas container 10. The pulse signal from the pulse controller 15 is transmitted to the solenoid valve 11.
Therefore, the solenoid valve 11 opens according to the pulse signal and injects Ar gas onto the target 5 through the nozzle 12. This creates a gas pulse with the pressure required for the sputter (1 to 0.1 Pa for a magnetron sputter). In the case of a magnetron sputter, it exhibits voltage-current characteristics as shown in FIG. 2, so it is better to have a high gas pulse pressure in order to flow a large current at a low voltage.

On the other hand, since a pulse signal is also given to the sputter power source 4, the sputter power source 4 synchronizes with the gas pulse and applies 3 to 10 times the power (for example, 50 to 100 KW) to the cathode 2 during normal continuous operation. throw into.
As a result, a high-density plasma is generated between the anode 2 and the cathode 3, and the target metal ejected by the ions in the plasma adheres to the substrate 6. The film forming speed is about 10 times that of the conventional method (for example, 10 to 20 μm/min) because the input power is large.
The duty of the pulse is determined by taking into account the melting point of the substrate 6, the volume of the vacuum container 1, the capacity of the exhaust pump, etc., and the pulse interval is set between 1 millisecond and 1 second. The gas inside the vacuum container 1 is discharged through the exhaust pipe 13.
It is discharged intermittently or continuously through.

In this way, according to this embodiment, high power is applied intermittently to increase the film formation rate during sputtering, so a sputtered film with high purity can be produced without causing a significant temperature rise of the substrate or target. can be formed.

Note that the sputter power source can be applied to either DC or RF, and the input power is not limited to the above-mentioned values.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a sputtering apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between target voltage and discharge current. 1... Vacuum container, 2... Cathode, 3... Anode, 5
...Target, 6...Substrate, 7...Substrate holder, 8...Introduction pipe, 9...Control valve, 10...Gas container, 11...Solenoid valve, 12...Nozzle, 13...
...Discharge pipe, 14...Discharge valve.

Claims (1)

[Claims] 1. A cathode, an anode, and a target disposed between them;
The sputtering device is equipped with a nozzle that intermittently discharges an inert gas onto the target, and a sputtering power source that intermittently applies a voltage between the cathode and the anode in synchronization with the gas pulse from the nozzle. Characteristic sputtering equipment. 2 The nozzle has 1 to 1 on the target.
The sputtering apparatus according to claim 1, wherein the sputtering apparatus applies a pressure of 0.1 Pa. 3. The sputtering apparatus according to claim 1, wherein the sputtering power supply supplies sputtering power of 50 to 100 kW between the cathode and the anode.