JPS6187869A - Sputter device - Google Patents

Abstract

PURPOSE:To make possible the sputtering under a low pressure and to prevent the destruction of a cathode by forming a Miller magnetic field in a treating chamber for film formation and introducing a microwave into the magnetic field. CONSTITUTION:The microwave is introduced into a vacuum chamber 1 and resonance motion is induced in electrons at the approximate center P between a substrate holder 4 and the cathode 6 so that the energy from the microwave is efficiently absorbed by the electrons. The electrons are confined in the Miller magnetic field 10. The electrons obtaining the high energy ionize the Ar atoms around the same and therefore the high-density plasma 14 is obtd. under the low Ar pressure. The plasma density can be controlled by the energy of the microwave to be impressed and consequently the discharge voltage at which the sputter rate of the target can be maximized can be set. The efficient sputtering is thus made possible.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention uses microwaves to generate plasma, and in particular,
The present invention relates to a sputtering apparatus suitable for forming wiring films and insulating films for VLSIs including megabit memories.

[Background of the invention]

Magnetron sputtering equipment, which is widely used as a sputtering equipment today, is equipped with a magnet on the back side of a cathode made of a film-forming material as described in Japanese Patent Publication No. 55-19319, and a magnetic field is formed on the surface of the cathode to emit light from the cathode. The secondary electrons are captured near the cathode, ionize atmospheric gas such as Ar, and form plasma.

Normally, the power supply connected to the cathode is a constant current power supply when the film forming material is a conductive material, and an RF (Ra
dio Frequency) power source is used.

In this type of sputtering equipment, the energy of t to turn atmospheric gas such as Ar into plasma and the energy of
Energy for extracting ions such as r and sputtering the target is supplied from the same power source.

Now, in VLSI devices such as 1 megabit DRAM, it is necessary to fill minute through holes and contact holes with a film, but in conventional magnetron type sputtering equipment, the Ar pressure is high (several mtorr), and the film forming material emitted from the cathode. is scattered before reaching the substrate, and the micro holes (13~
It was difficult to embed the membrane in the area (0.8 μm). For example, A
The mean free path at an r pressure of 5 mTorr F is 16 rm, and if the substrate-cathode distance is assumed to be jDOm, collisions will be repeated nearly eight times. Therefore, in order for the film-forming substance to reach the substrate without collision, the Ar pressure must be increased to 10-'
It is necessary to keep it below mTorr. In conventional magnetron type sputtering equipment, the secondary electrons released when Ar ions collide with the cathode surface generate consumed Ar ions and sustain the discharge, so when the Ar pressure decreases,
There is a lack of Ar ions and electrons necessary to sustain the discharge,
Discharge stops. Moreover, even if the discharge continues,
Since there are fewer Ar ions and electrons, the discharge impedance increases, and as a result, the discharge voltage also increases. As the discharge voltage increases, the impact force of the Ar ions on the cathode increases, but the energy of the Ar ions not only gives energy to the ejected film-forming material particles, but also is mostly consumed by increasing the temperature of the cathode surface. . As a result, the cathode may develop a large internal stress and break.

[Purpose of the invention]

The object of the present invention is to: under a pressure of 10 mTorr or less,
An object of the present invention is to provide a sputtering device that can perform sputtering. Another object of the present invention is to provide a sputtering device that maintains the discharge voltage low even under low pressure and prevents the cathode made of the film-forming material from being destroyed.

[Summary of the invention]

In order to generate a discharge under a low pressure of 10-4 or less, microwaves are introduced into the space between the target and the substrate, and a magnetic field is applied using a magnet so that the microwave frequency matches the specific imaging of electrons in the space. , creating an electronic resonance state. Electrons in a resonant state effectively absorb microwave energy and have high energy, so even though the pressure is lower than before,
High-density plasma can be formed. Furthermore, since the plasma density can be controlled by the energy of the supplied microwave, the discharge voltage can be set to an appropriate value.

[Embodiments of the invention]

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

The vacuum chamber 1 is connected to an exhaust port 2 by an exhaust device (not shown).
The gas is evacuated to a predetermined pressure, and then Ar gas is introduced through the conduit 3 so that the predetermined Ar pressure is reached. A coated substrate 5 placed on a substrate holder 4 and a cathode 6 which is a film forming material
are placed facing each other. Two electromagnetic coils 8.9 are wound around the axis 7 to form a mirror magnetic field 10, and the intensity of the a field at a position P approximately in the center of the space between the substrate holder and the sputtering electrode is adjusted to a predetermined microwave frequency. The resonant frequencies of the electrons are determined to match. For example, in the case of microwaves of 2°45 GHz, the required density for electrons to perform resonant motion is approximately 875 Gauss. Microwaves are introduced into the vacuum chamber by waveguides 11.12. The microwave source is not shown.

A power source 13 is connected to the cathode 6, and if the target material is an insulator, an RF power source is connected, and if the target material is a four-electric material, a DC power source or an RF power source is connected. The substrate holder 4 is connected to ground. The operation of the sputtering apparatus of this embodiment will be explained.

Microwaves are introduced into a vacuum chamber that has been evacuated to a high vacuum (10 Torr or less) and supplied with Ar gas to a predetermined pressure (10 to 1 Torr), and the space between the substrate holder 4 and the cathode 6 is The electrons are caused to undergo resonant motion at approximately the center P, and the energy from the microwave is efficiently absorbed by the electrons. Furthermore, this electron is mirror appearance 1
Trapped within 0. The electrons that have obtained high energy in this way ionize the surrounding Ar atoms, so even though the Ar pressure is lower than before, the high-density plasma 1
It is possible to obtain 4. Furthermore, since the plasma density can be controlled by the applied microwave energy, the discharge impedance during sputtering can be controlled, and as a result, it is possible to set the discharge voltage to maximize the sputtering rate of the target. Therefore, sputtering can be performed efficiently.

In this example, microwaves were introduced from two directions, but this was to make the plasma uniform on the cathode surface.In order to make the plasma more uniform, it is recommended to introduce microwaves from multiple directions. desirable.

A second embodiment of the invention is shown in FIG. This example is the first
In this embodiment, the coil arrangement is perpendicular to the microwave introduction direction. This embodiment has the same effect as the first embodiment, but since the substrate is exposed to plasma,
Possible damage from charged particles. However, it can be used as a bias sputtering apparatus that applies a bias voltage to the substrate and sputters the substrate with lightly charged particles before forming a film.

In this embodiment, a power supply 16 is also connected to the substrate side so that the bias voltage can be appropriately selected.

〔Effect of the invention〕

According to the present invention, high-density plasma can be formed even under a pressure of 10 to 10 Torr, and a film can be formed by sputtering, so it is possible to form a film even in minute holes of 0.8 to 13 μm. be.

In addition, since the plasma density can be controlled by the energy of the microwave being emitted, it is possible to control the discharge voltage during sputtering. As a result, a discharge voltage suitable for the cathode material can be set, and sputtering efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a sputtering apparatus according to the present invention;
FIG. 2 is a diagram showing another embodiment of the sputtering apparatus according to the present invention. 1...Makabe chamber, 2...Exhaust port, 3...
Ar inlet, 4... Substrate holder, 5... Substrate, 6... Cathode, 7... Shaft,
8.9... Coil, 10... Mirror magnetic field, 11, 12... Magnetic field, 13, IS...
Power supply, 14... plasma, 15... glass window.

Claims (1)

[Scope of Claims] 1. A high frequency or direct current sputtering apparatus, characterized in that a mirror magnetic field is formed in a sputter film forming processing chamber, and microwaves are introduced into the mirror magnetic field. 2. In the sputtering apparatus according to claim 1, a film-forming substrate and a cathode made of a film-forming material are installed facing each other in the sputter film-forming processing chamber, and the mirror magnetic field is formed between them. A sputtering device characterized by: 3. In the sputtering apparatus according to claim 1 or 2, the mirror magnetic field is a plurality of coils wound on the same axis, and the cycloton frequency of electrons in the magnetic field and the micro A sputtering device characterized in that the magnetic flux density necessary to match the frequency of waves is provided by a generator.