JPH01298158A - Sputtering device - Google Patents

Abstract

PURPOSE:To prevent the adhesion of a film to a microwave-introducing window by providing a plasma-drawing window to the inside of a specimen chamber, providing a target between the above window and a substrate in a manner not to be opposed to a microwave-introducing window, and also providing an auxiliary exciting coil between the above target and a susceptor. CONSTITUTION:A microwave-introducing window 1b is provided to the center of the upper wall of a plasma production chamber 1, and a plasma-drawing window 1c is provided to the center of the lower wall. A susceptor 5 is provided to the position opposed to the plasma-drawing window 1c, and a specimen substrate S is placed on the above. A sputtering target 6 is provided on the periphery of the opening on the specimen chamber 3 side of the plasma-drawing window 1c, and an auxiliary exciting coil 8 is provided to the outside periphery of the intermediate part between the target 6 and the specimen stand 5 in a manner surrounding the intermediate part. The angle of inclination of the inside peripheral surface of the target 6 relative to a perpendicular is set up so that none of the parts of the inside peripheral surface are directly opposed to the microwave-introducing window 1a linearly. By this method, the adhesion of sputter atoms to the plasma-introducing window can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sputtering apparatus that uses plasma generated by electron cyclotron resonance excitation using microwaves.

[Prior art]

Generally, chemical vapor deposition (CVD), which uses plasma generated by high-frequency discharge, is used to form silicon-based thin films as a method for forming thin rotors on sample substrates in the manufacturing process of electronic devices such as semiconductor integrated circuits.
The apor deposition method has been used, and the Svanta method has been mainly used for forming thin films of metals or metal compounds.

However, in the high-frequency plasma CVD method, the sample substrate is heated to 250°C.
It is necessary to heat the film to ~400''C, and there is a problem with film quality in terms of film density.

As a countermeasure to this problem, electron cyclotron resonance (ECR: El
ectron Cyclotron Resonance
) has been proposed.

This method does not require heating the sample substrate, and
It has the advantage of providing dense film quality comparable to the icvo method. - Although the Kasbatta method can easily supply metal atoms, it is difficult to control the film, and there are also problems with the density of the film.

Therefore, as a method to solve this problem, an ECRC sputtering method combining ECR plasma technology and sputtering method has been proposed (Japanese Patent Laid-Open No. 47728/1989).

FIG. 4 is a schematic vertical sectional view of a conventional ECRC sputtering apparatus, in which 1 is a plasma generation chamber, 2 is a plasma generation chamber, and 2 is a plasma generation chamber.
3 indicates a microwave waveguide, 3 a sample chamber, and 4 an excitation coil.

The plasma generation chamber 1 is equipped with a microwave introduction window 1b closed with quartz glass 1a at the center of the upper wall, and a plasma extraction window 1c at the center of the lower wall opposite to this. One end of the microwave waveguide 2 is connected, and a sample chamber 3 is arranged facing the plasma extraction window 1c, and furthermore, a plasma generation chamber 1 and one end of the microwave waveguide 2 connected thereto are arranged around the plasma generation chamber 1. An excitation coil 4 is disposed around the parts so as to surround them.

In the sample chamber 3, there is a sample stage 5 on which a sample substrate S is placed facing the plasma extraction window 1c, and a sample stage 5 for sputtering facing the periphery immediately below the opening of the plasma extraction window IC in the sample chamber 3. A target 6 is disposed surrounded by a shield case 6a. The target 6 is formed into a short cylindrical shape, and the upper and lower end surfaces and the outer peripheral surface except for the inner peripheral surface are covered with a shield case 6a. The negative electrode is connected.

In such a conventional device, after the pressure inside the plasma generation chamber 1 and the sample chamber 3 is reduced to a predetermined value, gas is supplied to these through a gas supply system (not shown), and a microwave waveguide is Microwaves are introduced into the plasma generation chamber 1 through the plasma generator 2, and the excitation coil 4 is energized to form a magnetic field, thereby establishing an electron cyclotron resonance condition within the plasma generation chamber 1 and generating plasma. Plasma is introduced into the sample chamber 3 through the plasma extraction window 1c as shown in FIG. 5 by a divergent magnetic field formed by the excitation coil 4.

FIG. 5 is an explanatory diagram of the lines of magnetic force of the diverging magnetic field. When ions in the plasma are introduced into the sample chamber 3 through the plasma extraction core 1c, they are accelerated by the negative voltage applied to the target 6. The atoms of the target 6 are sputtered into the surface of the target 6 and impact it, and the atoms of the target 6 are sputtered and ejected into the plasma flow, and then enter the sample substrate S as they are or some of them have lost electrons in the plasma, forming a film. will be done.

[Problem to be solved by the invention]

By the way, in such conventional equipment, target 6
Among the atoms sputtered from the microwave, some of the atoms that are not ionized are scattered without being affected by the electric field or magnetic field and adhere to the quartz glass 1a of the microwave introduction window 1b. Therefore, when the target 6 is a metal or other conductive metal compound, the sputtered metal atoms adhere to the microwave introduction window and function as a shield against the microwaves, allowing the microwaves to be introduced into the plasma generation chamber l. Therefore, frequent inspection and maintenance of the quartz glass 1a is required. Another problem is that most of the ECR plasma generated in the plasma generation chamber 1 is transported to the sample chamber 3 without being incident on the target due to the divergent magnetic field.

The present invention has been made in view of the above circumstances, and its purpose is to provide a sputtering apparatus which suppresses film adhesion to the microwave introduction window and which is highly efficient in utilizing ECR plasma.

[Means to solve the problem]

In the sputtering apparatus according to the present invention, a sputtering target is provided between a plasma extraction window and the sample substrate in the sample chamber so as not to face the microwave introduction window, and a sputtering target is provided between the target and the sample stage. An auxiliary excitation coil is provided to form a magnetic field for guiding the target toward the target.

[Effect]

In the present invention, this prevents the film from adhering to the microwave introduction window. Furthermore, the target current density increases, the plasma utilization efficiency increases, and the growth rate also increases.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 is a schematic longitudinal sectional view of a sputtering apparatus according to the present invention (referred to as the present invention apparatus), in which 1 is a plasma generation chamber, 2 is a microwave waveguide, 3 is a sample chamber, 4 is an excitation coil, S indicates a sample substrate.

The plasma generation chamber 1 is configured to function as a microwave cavity resonator, and has a microwave introduction window 1b sealed with quartz glass 1a in the center of its upper wall, and a plasma drawer in the center of the upper wall. One end of the microwave waveguide 2 is connected to the microwave introduction window 1b, and a sample chamber 3 is provided facing the plasma extraction window 1c. An excitation coil 4 is disposed so as to surround the chamber 1 and one end of the microwave waveguide 2 connected thereto.

The other end of the microwave waveguide 2 is connected to a high frequency oscillator (not shown), and microwaves emitted from the high frequency oscillator are introduced into the plasma generation chamber 1.

The excitation coil 4 is connected to a DC power source (not shown), and forms a magnetic field that satisfies electron cyclotron resonance conditions in the plasma generation chamber 1, and also forms a diverging magnetic field whose magnetic flux density decreases toward the sample chamber 3 side. That's how it is.

A sample stage 5 is disposed in the sample chamber 3 at a position facing the plasma extraction window C, and a sample substrate S is placed on this stage.

In addition, the sample chamber 3 of the plasma extraction window 1c is located inside the sample chamber 3.
Sputtering target 6 facing the periphery of the opening in the example
However, an auxiliary excitation coil 8 is disposed around the outer periphery of the intermediate portion between the target 6 and the sample stage 5 so as to surround this.

The target 6 is formed in the shape of a cylindrical truncated cone whose inner and outer diameters increase from the upper end toward the lower end. It is held concentrically with and directly below the plasma extraction window 1c, and is connected to the negative electrode side of the DC power supply 7.

(
The oblique angle is set so that no part of the inner circumferential surface directly faces the microwave introduction window 1a in a straight line.

The auxiliary excitation coil 8 is set to have an inner diameter substantially equal to that of the excitation coil 4, and is connected to a DC power source (not shown) so that the direction of its magnetic lines of force is opposite to that of the excitation coil 4.

In the apparatus of the present invention, after the plasma generation chamber 1 and the sample chamber 3 are evacuated and the pressure is reduced to a predetermined value, a gas (for example, Ar gas) is supplied into the plasma generation chamber 1 from a gas supply system (not shown). At the same time, microwaves are introduced into the plasma generation chamber 1 through the microwave waveguide 2, and a magnetic field is formed by the excitation coil 4 to establish electron cyclotron resonance conditions in the plasma generation chamber 1 to generate plasma. This is generated and introduced into the sample chamber 3 through the plasma extraction window IC as shown in FIG. 2 by the divergent magnetic field formed by the excitation coil 4.

FIG. 2 is an explanatory diagram showing the lines of magnetic force of the magnetic field produced by the excitation coil 4 and the auxiliary excitation coil 8. In the sample chamber 3, the auxiliary excitation coil 8 forms a magnetic field in the opposite direction to the magnetic field produced by the excitation coil 4. As shown in FIG. 2, the lines of magnetic force of the diverging magnetic field formed by the EII coil 4 are bent toward the target 6 at a position passing through the plasma extraction window 1c, and as a result, the plasma introduced into the sample chamber 3 also follows this direction toward the target 6. collide with the surface of

A negative voltage is applied to the target 6 by a DC power source 7, and ions are attracted to the target 6.
collides with the surface in an accelerated state and sputters it.

The sputtered atoms ejected from the target 6 remain as they are, and some of them lose electrons in the surrounding plasma and are ionized, guided to the surface of the sample substrate S, and attached thereto to form a film.

In such an embodiment, the position and shape of the target 6 are set so that it does not face the microwave introduction window 1b, which can of course prevent the spattered atoms from adhering to the microwave introduction window 1b. Since the plasma flow is guided toward the surface of the target 6 by the magnetic field of the auxiliary excitation coil 8, the plasma density around the target 6 is high, the target current density is reduced, the film formation rate is increased, and the plasma utilization efficiency is improved.

FIG. 3 is a schematic vertical cross-sectional view showing another embodiment of the present invention, in which the cross-sectional area of the sample chamber 13 is defined as the cross-sectional area of the plasma generation chamber 1 from its upper end to the vicinity directly above the sample stage 5. A stepped portion 3a is formed on the outer periphery of the sample chamber 3 so as to be approximately equal to each other, and an auxiliary excitation coil 8 is installed here.

In such an embodiment, by disposing the auxiliary excitation coil 8 outside the sample chamber 3, it is possible to reduce the contamination of impurities and also to prevent damage to the auxiliary excitation coil 8 itself. .

The other configurations and operations are substantially the same as those of the embodiment shown in FIG. 1, and corresponding members are given the same numbers and their explanations will be omitted.

〔effect〕

As described above, in the apparatus of the present invention, the sputtering target is installed between the plasma extraction window and the sample stage at a position not facing the plasma introduction window, and the sputtering target is installed between the target and the sample stage. Since an auxiliary excitation coil is provided to guide the plasma toward the target, it is possible to reliably prevent sputtered atoms from adhering to the plasma introduction window, greatly simplifying maintenance and inspection work, and increasing operating efficiency. The present invention has excellent effects such as improved performance.

[Brief explanation of the drawing]

Fig. 1 is a schematic vertical sectional view of the device of the present invention, Fig. 2 is an explanatory diagram showing the mode of magnetic lines of force formed by the excitation coil and the auxiliary excitation coil, and Fig. 3 is a schematic diagram showing another embodiment of the invention. FIG. 4 is a schematic longitudinal sectional view of a conventional device, and FIG. 5 is an explanatory diagram showing the aspect of six force lines due to an excitation coil. 1... Plasma generation chamber 2... Plasma waveguide 3.
・・Sample chamber 4・Excitation coil 5・Sample chamber 6・
...Target 7...Power supply 8...Auxiliary excitation coil No. I

Claims (1)

[Scope of Claims] 1. A plasma generation chamber that generates plasma by electron cyclotron resonance excitation by forming an electric field by microwaves introduced from a microwave introduction window and a magnetic field by an excitation coil, and a plasma extraction window from the plasma generation chamber. In a sputtering apparatus having a sample chamber into which plasma is introduced through, a sample substrate and a sputtering target in the sample chamber, a plasma extraction window in the sample chamber and a space between the sample substrate so as not to face the microwave introduction window. A sputtering apparatus characterized in that a sputtering target is provided, and an auxiliary excitation coil is provided between the target and a sample stage to form a magnetic field for guiding plasma toward the target.