JPS61272372A - Sputtering device - Google Patents

Abstract

PURPOSE:To reduce the thermal stress of a target, to increase the film forming speed and to form a thin film having uniform thickness on a substrate by retaining density plasma generated by a microwave on the whole surface of the target with a magnet and controlling the density distribution of the plasma. CONSTITUTION:Magnets 3 and 16 constitute a mirror field and the lines magnetic of force 17 are dense at the center of the magnet 16, coarse at a plasma generating chamber 12 and dense at the center of the magnet 3. The lines magnetic of force 18 on the surface of the target 1 connected to the lines 17 are compacted in the vicinity of the target 1 by a magnetic body 4. A microwave from a microwave generator 15 is introduced into the chamber 12 to generate high-density plasma with the magnetostatic fields of the magnets 3 and 16, the whole surface of the target 1 is covered with the plasma by the diffusion of the plasma along the line of magnetic force 18, high density is kept at this place and the number of sputtered particles is increased. Consequently, a film can be formed at high speed without an increase in the thermal load on the target 1. Furthermore, plural magnets 3a and 3b are used to change the intensity distribution of the magnetic field and to control the density distribution of the plasma and a uniform thin film is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to semiconductor manufacturing, particularly to a sputtering apparatus used for forming semiconductor thin films.

[Background of the invention]

As a conventional sputter film forming apparatus, there is a magnetron type sputtering apparatus. This device is, for example, published in Japanese Patent Publication No. 55-1.
As described in Japanese Patent No. 9319, a cathode having a surface made of the target material and a pair of magnetic poles are provided on opposite sides of the limb surfaces, and a portion of the magnetic field lines appearing between the pair of magnetic poles forms an arc on the target surface. It is configured to form magnetic lines of force, and electrons perform toroidal motion due to the magnetic field caused by the lines of magnetic force and the electric field caused by the voltage applied between the anode and cathode.

As a result, the plasma generated by the voltage applied between the anode and cathode is maintained without spreading. Therefore, compared to the above-mentioned magnetron sputtering apparatus Fi2-pole sputtering apparatus, not only the plasma density is increased but also high-speed film formation is possible. However, in the magnetron type sputtering apparatus, the plasma generation region is a narrow region surrounded by the arcuate lines of magnetic force, and the electric power applied to the cathode simultaneously maintains the plasma and supplies energy to the particles entering the target from the plasma. Is going. Therefore, in order to increase the plasma density with the aim of increasing the film formation rate, when the voltage applied between the anode and cathode is increased, the incident energy of ions increases significantly compared to the increase in the number of ions incident on the target from the plasma. do. Since most of the incident energy is converted into heat at the target, local concentration of heat occurs at the target. As a result, a large temperature stress is generated and the target is destroyed, which limits the power applied to the cathode and also limits the film formation rate.

As a method of increasing the film formation rate while suppressing the rise in target temperature, a method has been proposed in which plasma is generated using microwaves, as described in, for example, Japanese Patent Application Laid-Open No. 75859/1983. This proposal consists of a structure in which the sputtering device is equipped with a microwave oscillator, and since the plasma density is increased by the microwave power, it is possible to increase only the number of incident particles while the incident particle energy to the target is constant. Therefore, the film formation rate can be increased.

However, since the plasma generation region is limited to a closed region surrounded by arc-shaped lines of magnetic force, similar to the sputtering device described above, the target is destroyed due to temperature stress, and only a portion of the target is sputtered, resulting in a consumption region of the target. However, there are also narrow problems.

Furthermore, as a film forming apparatus that uses plasma generation by microwaves and sputtering principles, for example, Japanese Patent Laid-Open No. 59
As described in Publication No. 47728, plasma generated by microwaves is transported by a divergent magnetic field, and a DC electric field is applied to a target placed on the outer periphery of the divergent magnetic field to draw in ions in the plasma. Jump into Prada 1 by sputtering target particlesft!
It has been proposed that nuclear target particles are ionized by plasma, transported in a plasma flow, and deposited on a substrate.

The above proposal allows only ionized particles of target particles sputtered from a target to contribute to thin film formation in order to deposit a high quality thin film on a substrate at a low temperature. The emission angle distribution of particles sputtered from the target follows the cosine law ζ, whereas the target and the substrate are not facing each other, i.e. the normal on the target surface is significantly deviated from the substrate, so it is difficult to directly target the target. Because the amount of particles that reach the substrate from the sputtering device contributes only a small amount to the formation of the thin film, the rate of thin film deposition on the substrate is inferior compared to conventional sputtering equipment. Therefore, the utilization efficiency of target particles (the proportion of particles sputtered from the target that contribute to thin film formation) decreases.

In the above proposal, in order to increase the deposition rate,
A case will be considered in which the target size is increased, the voltage for drawing in positive ions in the plasma is increased, and the number of particles ejected from the target is increased.

In the sample chamber where the film is formed, there is only a divergent magnetic field from the magnets installed around the outer periphery of the plasma deposition chamber, making it impossible to confine the plasma on the target surface, making it difficult to maintain plasma at high density over a large area. In addition, since the number of particles incident on the target does not increase, the incident energy increases, causing a thermal stress problem on the target as described above.

[Purpose of the invention]

This Komei solves the problems of the above-mentioned rice promotion technology, and generates high-density plasma over the entire surface of the target without damaging the M plate due to plasma, thereby reducing the thermal stress on the target and increasing the deposition rate. The purpose of this is to increase the target utilization rate.

[Summary of the invention]

In order to achieve the above object, the present invention includes a sample substrate provided in a film formation chamber, a target placed opposite to the substrate, a cathode on which the target is placed, and a power supply that applies power to the cathode. A sputtering apparatus comprising: an opening for introducing microwaves into the target and the cathode; a magnet for generating lines of magnetic force in the same direction as the traveling direction of the microwaves outside the opening; and an arc-shaped sputtering device covering the target. It is characterized by being equipped with a magnet that generates magnetic lines of force.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings. 1st
Figures 4 to 4 are cross-sectional views of the main parts (sputtering film forming parts) of each embodiment, and the same reference numerals in the figures indicate the same or corresponding parts. A cathode 2 connected to a DC power source 10 is attached to the lower end of the sputter film forming chamber 9 via an insulating material 8, 8', and the center of the cathode 2 is hollow. A plasma generation chamber 12 is provided in the chamber.

A waveguide 13 is provided outside the plasma generation chamber 12, one end of the waveguide 15 is fixed to the cathode 2 via an insulating material 14, and the other end is fixed to a microwave generation source 15. The plasma generation chamber 12 is kept in a vacuum and made of a material that transmits microwaves, such as quartz.

It is made of alumina porcelain, and a magnet 16 is provided near the microwave generation source 15 of the plasma generation chamber 12 .

A flat target 1 is provided on the upper and lower surfaces of the cathode 2.
and an arbitrary number (two in the figure) of magnets 5, w' 5
A magnet 3 consisting of b is attached, and the magnet 3
a and 3b are provided concentrically. A magnetic body 4 is provided on the outside of the magnet 3b concentrically therewith.

An anode 19 is provided outside the insulating material 8 provided outside the cathode 2 and the target 1 .

A holder 6 for holding a sample substrate 5 facing the target 1 is provided at an appropriate position above the target 1, and the holder 6 has a holder shaft 6A projecting into the sputter film forming chamber 9. It is attached to the tip. An insulating material 7 is provided at a portion where the holder shaft 6A penetrates the wall of the sputter film forming chamber 9. The sputtering film forming chamber 9 and the plasma generation chamber 12 are evacuated in advance to a high vacuum, and then
An atmospheric gas such as argon gas is introduced to maintain a predetermined degree of vacuum.

Next, the operation of this embodiment configured as described above will be explained.

The magnet 3.16 constitutes a mirror magnetic field, and its magnetic lines of force 17 are narrowed at the center of the magnet 16 to become dense, then diffused in the plasma generation chamber 12 to become coarse, and narrowed again at the center of the magnet 3 to become quiet. becomes. The magnetic lines of force 18 on the surface of the target 1 connected to the above lines of magnetic force 17 are generated almost uniformly along the magnet 6. The lines of magnetic force 18 become dense in the vicinity of the target 1 due to the magnetic body 4, and are diffused along one surface of each target to become almost parallel.

Now, the microwaves oscillated by the microwave source 15 are guided to the waveguide 15 and introduced into the plasma generation chamber 12, where the static magnetic field formed by the magnet 3.16 ionizes the atmospheric gas and generates plasma. Generate 0 In this case, if the center magnetic field strength of the magnet 3 is made smaller than the center magnetic field strength of the magnet 16, most of the plasma generated in the plasma generation chamber 12 will proceed along the magnetic lines of force 17 and will be placed in the center of the cathode 2. The plasma is introduced into the sputter film forming chamber 9 through the cavity.Then, the plasma introduced into the sputter film forming chamber 9 diffuses along the magnetic lines of force 18, so that the plasma spreads to the vicinity of the substrate 5. The power source 10 applies power between the anode 19 and the cathode 2 to generate negative pressure on the target 1, accelerating the positively charged particles from the plasma to cover the entire surface of the target 1. This collision causes target particles to fly out from the surface of the target 1, and the target particles are deposited on the opposing substrate 5 to form a thin film.

The plasma in the plasma generation chamber 12 becomes highly dense. The plasma generation chamber 12 and the target 1 are close to each other, and the electrons in the plasma on the surface of the target 1 are affected by a magnetic field component parallel to the surface of the target 1 from the magnet 3 and an electric field applied between the anode 19 and the cathode 2. The effect causes toroidal motion to promote reionization of the plasma, so that the high-density plasma is maintained at a high density even on the surface of the target.

Therefore, the amount of ions incident on the surface of the target 1 from the plasma increases regardless of the accelerating voltage of ions from the plasma applied to the cathode 2) by the power source 10, and the number of sputtered particles increases. 16. When a plurality of magnets 5ae3b are used like the magnet 6, the magnetic field strength or position (distance # from the cathode 2) can be Since the plasma density distribution can be easily controlled by arbitrarily setting and changing the magnetic field intensity distribution on the surface of the target 1, it is possible to form a thin WX8 film with a uniform thickness on the substrate 5.

When using microwaves as a means to increase the density of plasma, the plasma density is Z4X1 in the absence of a magnetic field.
It increases only up to 010/cIrL.

However, as in the first embodiment described above, in the case of a magnetic field strength (2.45 GHz) higher than that at which electrons cause cycloton resonance, it is set to 875 G or higher), and the direction of the magnetic field is made to match the traveling direction of the microwave. By doing so, the plasma density can be increased to 1012/d or more.

Furthermore, since the charged particles in the plasma predominantly move along the magnetic force l1118, the magnetic force ! 9! By providing a means to uniformly generate 1B parallel to the surface of the target 1 without spreading it to the substrate 5 side, the charged particles can be moved in a cyclotron to maintain a high-density plasma over the entire surface of the target 1, thereby improving film formation. It is possible to increase the speed and improve the utilization efficiency of the target material, that is, the percentage of the target material that is consumed when replacing the target.

The second embodiment shown in FIG. 2 differs from the first embodiment shown in FIG. 1 in that a magnet 20 that generates magnetic lines of force 21 is incorporated into the holder 6 of the substrate 5, and the other structures are the same, so a description will be given here. omitted.

With this configuration, since the magnetic force [18 is biased toward the target 1 side, the plasma is confined more closely to the target 1 than in the W11 embodiment. This has the advantage of reducing plasma damage to.

Said 15th j! Example (Figure 1) and Second Example (Second Example)
In Figure), the target 1 was formed into a flat plate shape, but this is also possible! l) Third embodiment (Figure 6) and fourth embodiment (Fourth embodiment)
The structure shown in FIG. 1 differs in that one target is formed into a conical shape, and the other structures are the same as those of the first and second embodiments, so a description thereof will be omitted.

With this configuration, the ratio of target particles facing the substrate 5 to the target particles flying out from the surface of one target increases, which has the advantage of increasing the film forming rate.

〔Effect of the invention〕

As explained above, according to the present invention, the density plasma (plasma density 10117
d or more) on the entire surface of the target without spatially spreading it with a magnet installed on the target side, it is possible to apply a large amount of power to the electrode without causing excessive heat concentration on the target, which makes it possible to achieve successful results. Film speed can be increased.

In addition, by changing the magnetic strength and position of the magnet and magnetic material provided on the opposite side of the cathode and changing the magnetic field distribution on the target surface, the plasma density distribution on the target surface can be controlled and the plasma density distributed uniformly on the substrate. Forms a thin film with a thickness of
It is possible to

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing essential parts (film forming parts) of each embodiment of the sputtering apparatus of the present invention. 1.1A...Target 2...Cathode 5.16.20...Magnet 4
...Magnetic material 5...Substrate 6...Holder
9... Sputter film formation chamber 10... Power supply 15.
...My, chromatic wave generation source R, 1B... Lines of magnetic force

Claims (1)

[Claims] 1. A sample substrate attached to a holder protruding into a sputter film forming chamber, a target provided opposite to the substrate, a cathode on which the target is placed, and an electric power applied to the cathode. A sputtering apparatus is provided with an opening for introducing microwaves into the target and the cathode, and a magnet and the target that generate lines of magnetic force in the same direction as the traveling direction of the microwave are provided outside the opening. A sputtering device characterized by being provided with a magnet that generates covering arc-shaped lines of magnetic force. 2. The sputtering apparatus according to claim 1, characterized in that a magnetic material is combined with a magnet that generates arcuate lines of magnetic force that cover the target. 3. The sputtering apparatus according to claim 1 or 2, wherein a magnet is provided near the substrate of the holder that holds the substrate so as to face the cathode. 4. The sputtering apparatus according to any one of claims 1 to 3, wherein the target is formed in a conical shape.