JPS62151561A - Sputtering device - Google Patents

Abstract

PURPOSE:To provide a sputtering device which forms a film having good quality onto a substrate without taking in an atmosphere gas during the sticking and depositing of said film by utilizing the electric discharge in which microwaves and static magnetic field are combined to confine the plasma generated in a high vacuum atmosphere onto a target by a magnetic device. CONSTITUTION:The microwaves generated from a microwave generating source 15 are introduced in parallel with magnetic lines 21, 25 of force of the static magnetic field into a plasma generating chamber 11 of the above-mentioned device. The intensity of the static magnetic field is increased to the electron cyclotron resonance condition or above to generate the stable plasma in the high vacuum atmosphere of 10<-4>-10<-5>Torr order. The plasma is then transported and confined onto the target 1 by a magnetic device 16 and the transport distance thereof is made shortest to eliminate the plasma loss by the diffusion during the transfer and to form the high- density plasma on the target 1. The average free travel of the particles released from the target 1 is made larger in the high vacuum atmosphere by 1-2 digits than in the conventional method, by which these particles are stuck and deposited on the substrate 2 without allowing the particles to collide against the atmosphere gas. The film is thus formed on the substrate.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a sputtering apparatus used in a thin film forming process for semiconductor devices, etc., and particularly to a sputtering device used for forming thin films on devices having fine grooves and holes such as highly integrated devices. The present invention relates to a sputtering apparatus suitable for film formation and improvement of film quality.

[Background of the invention]

In sputter deposition, a target material placed on a cathode is
By bombarding ions with energy exceeding a predetermined level (threshold value for sputtering), the constituent atoms or particles of the target material that are ejected by this bombardment adhere to the semiconductor substrate to form a thin film. It will be done.

For sputtering film formation, the
There is one described in Publication No. 19. According to this device, a line of magnetic C4 is placed on the back side of the target material surface of the cathode.
Eight poles (↑) are provided, and arc-shaped lines of magnetic force are formed by the magnetic device by penetrating the gap pole surface. By applying a voltage to the cathode to generate plasma, the charged particles are caused to move in a cyclotron and are restrained by the magnetic field lines, thereby generating a high-density plasma compared to a two-pole sputtering device, resulting in a high film-forming rate and a 'A low film forming pressure on the Torr level can be obtained.

However, in this method, the distance between the target and the substrate is set at a distance of about 6011 m to 70 m in order to make the thickness distribution of the thin film formed by adhering and depositing on the substrate uniform, so ions are emitted from the target by collision. The atoms or particles thus produced collide with molecules of an atmospheric gas (generally an inert gas such as Ar) about five to six times before reaching the substrate. Therefore, atmospheric gas is mixed into the film deposited on the substrate, resulting in poor film quality. In addition, the angle of incidence of atoms or particles emitted from the target onto the substrate (the angle between the substrate normal and the direction of incidence of the incident atoms/particles) becomes large due to collisions with atmospheric gas molecules, resulting in the formation of fine grooves, etc. If the particles are located underneath the substrate, the incident particles will adhere to the entrance corners of these grooves (this is called an overhang), and the groove width will be small (1.0 μm or less according to experiments).
In this case, due to the adhesion to the corners of the groove entrance, there is a problem in that the films deposited at both corners of the entrance join together before the inside of the groove is completely filled with incident particles, creating a cavity inside the groove. Ta.

[Purpose of the invention]

The purpose of the present invention is to stably generate plasma in a high vacuum atmosphere, turn the target into high-density plasma even at 10' to 10-' Torr, and deposit the film onto the substrate without reducing the film formation rate. A sputtering method that allows film formation without introducing atmospheric gas into the film (and without creating cavities inside the grooves of a substrate with fine grooves as the base).
Our goal is to provide the following.

[Summary of the invention]

In the present invention, stable plasma generation is performed in a high vacuum atmosphere using a discharge that combines microwaves and a quiet magnetic field, and the plasma is confined on a target by the above-mentioned plasma generation magnetic device. The main idea is to turn the target into high-density plasma even under high vacuum.

That is, in the present invention, microwave and microwave waves are introduced into the plasma generation part in parallel with the magnetic field lines of the static magnetic field, and the strength of the static magnetic field is controlled under electron cyclotron resonance conditions (microwave frequency 2.
At 45GHz, the seed water strength is 875 Gauss) or higher, and 1
It is possible to generate stable plasma in a high vacuum atmosphere on the o-4 to 10-' Torr level, and the plasma generated here is transported onto the target and confined by the magnetic device used for plasma generation, resulting in plasma transport. By minimizing the distance and eliminating plasma loss due to diffusion during transportation, high-density plasma is created on the target. Then, sputtering film formation was performed in the above-mentioned high vacuum atmosphere, and the mean free path of the particles released from the target was compared with that of the conventional method. - Increase the digit 7) C,! :, Eyori Ku 1. Wow, Eka 84 has a structure that allows sputtering to be deposited on the substrate without colliding with the surrounding gas.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a longitudinal sectional view showing the structure of the sputter film forming section of the sputtering apparatus of this embodiment.

In the figure, a target 1 and a substrate 2 are in a plane pair, the target 1 is placed in close contact with an I-pole 4 through a backing plate 3 on its back surface, and the cathode 4 is connected to an insulator 5.
Installed on flange 6 through! 11, and the seven lunges 6 are installed in a vacuum chamber 7. An insulating ring 8 is placed around the front target 1, backing plate 3, and cathode 4.
An earth shield 9 is installed in the vacuum/empty tank 7 via the earth shield 9 . Here, the center part 10 of the target 1 is hollow, and a plasma generation chamber 11 is installed in this part, and a waveguide 12 is provided around the outer periphery of the plasma generation chamber 11 to hold the plasma generation chamber 11. It is installed on the flange 6 as shown. Another waveguide 14 is attached to the waveguide 12 by a flange 13, and a microwave source cover is installed at the other end of the waveguide 14. Furthermore, a magnetic device 16 is installed on the outer periphery of the plasma generation chamber 11 and on the outer periphery of the waveguide 12, and a yoke 17 is installed on the outer periphery of the magnetic device 16 and the ml that covers the microwave generation source.

Further, the substrate 2 is dtf&ed on a substrate holder 18, and the substrate holder 18 is installed with a shaft 19 in such a manner that the vacuum of the tank 7 can be maintained. Roughly, an eaves source 20 is connected to the cathode 4.

As shown in FIG. 2, a magnetic device 1 having the configuration shown in FIG.
6, the magnetic field lines 21 exit from the end 22 of the yoke 17, enter the plasma generation chamber 11, become in the same direction as the axis of the plasma generation chamber 11, and spread from there onto the target 1,
It is configured to pass through the target 1 at the outer circumference of the target 1 and enter the other end 23 of the yoke 17. Here, the film forming chamber 24 is kept in a predetermined vacuum state (10'' to 10'' Torr) of atmospheric gas (for example, an inert gas such as argon gas).

Now, when the microwave source is covered and the microwave is oscillated, the microwave is guided by the waveguide 14, and the waveguide 'u1
2, and further passes through the plasma generation chamber 11 to Ia.

At this time, due to the static magnetic field created by the magnetic device 16,
The microwave is transmitted from 10 to 10 in the plasma generation chamber 11.
'The atmospheric gas on the Torr table is separated by 71 mm to create a plasma state. This plasma is transported onto the target 1 by the magnetic lines of force 21 and generates plasma on the surface of the target 10.

Here, regarding the plasma in the plasma generation chamber 11, it has a stray field, the output line 21 is along the direction of microwave propagation, and the magnetic field strength is set to electron cyclotron resonance conditions (microwave frequency 2.45G
By increasing the Mi magnetic field strength to a magnetic 4T strength of 875 Gauss (at Hz) or higher, plasma can be stably generated even in a high vacuum atmosphere of 10-4 to 10-6 Torr.

Also, the output line 25 on the surface of target 1
Since the radial planes are substantially parallel over a wide range, the electric field on the surface of the target 1 generated by the voltage applied to the cathode 4 causes the charged particles in the plasma to move in a cyclotron manner along the magnetic force $25, causing them to rotate around the target 10. Since the plasma drifts and is confined to the surface of the target 1, the plasma on the surface of the target 1 becomes denser.

Furthermore, a negative electric field generated on the surface of the target 1 by applying power from the source 20 to the cathode 4 accelerates ions in the plasma on the surface of the target 1, causing them to collide with the surface of the target 1. The atoms or particles ejected from the surface of the target 1 by the collision with the substrate 2
deposits on the surface of the material to form a thin film.

In the above-described film formation, whether atoms or particles ejected from the surface of the target 1 collide with atmospheric gas molecules before reaching the surface of the substrate 20 can be determined from the mean free path of the molecules. The mean free path λ is the diameter of the molecule,
It is determined by the temperature increase and atmospheric pressure, and is expressed by the following formula.

λ-2,331X 10-'' T/Pδ where T is the molecular temperature (0K) and P is the pressure (To r r ).

δ is the molecular diameter (m). Cover with argon gas °
G, mean free path λ = 6.66X10 at 760 Torr
-' m, and the atmospheric pressure is I X 10-' To
If rr, then λ = 5.06 x 10-' m, that is, it can be seen that in argon gas it moves about 500 M without collision.

The distance that particles ejected from the surface of the target 1 can travel without colliding with the atmospheric gas varies depending on the material of the target 1, that is, the movement of the molecules that make up the target 1, or the atmospheric pressure I x 10' Tor
r, it is thought to be about 100N.

Therefore, according to this embodiment, most of the particles ejected from the target reach the substrate without colliding with atmospheric gas molecules. The angle between the incident direction and the incident direction is also small, making it easier for sputtered particles to enter the fine grooves on the substrate. The uptake of molecules is also small.
(Become.

〔Effect of the invention〕

According to the present invention, in order to generate plasma using a combination of microwaves and a magnetic field, transport this to the target surface over a short distance, and confine charge particles by the magnetic field for plasma generation, Since a plasma of X'1E degrees can be generated stably under the atmospheric pressure of the table, the particles ejected from the target are deposited on the substrate without colliding with atmospheric gas molecules, and the incident angle of the sputtered particles on the substrate is adjusted. The performance of forming a film on a substrate having small grooves is improved, and there is an effect that less atmospheric gas is taken into the thin film deposited on the substrate (the film quality is improved).

[Brief explanation of drawings]

FIG. 1 is a radial sectional view showing the structure of a film forming section of a sputtering apparatus according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing lines of magnetic force in the film forming section of FIG. 1...Target, 2...Substrate, 4...Cathode, 7
...Vacuum chamber, 11...Plasma generation chamber, 12i4-
...Waveguide, cover...Microwave source, 16...
Magnetic device, 17...Yoke, 21.25...Magnetic field lines, 24...Spactor formation odor chamber.躬 1 solid 4P↑ne 73 7,9. -7! ! 2
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Claims (1)

[Claims] 1. A sputtering apparatus having a target made of a sputtered material facing the deposition surface of a sample substrate, a cathode on which the target is placed, and a power source for applying power to the cathode, comprising: an opening for introducing microwave plasma from the microwave generation source into the target and the cathode, and arcuate lines of magnetic force are formed at the opening along the direction of propagation of the microwave and covering the target. 1. A sputtering device comprising a magnetic device including a magnetic coil for generating electricity. 2. In the sputtering apparatus according to claim 1, the strength of the magnetic field lines by the magnetic device is set to be equal to or higher than the magnetic field strength that satisfies an electron cyclotron resonance condition according to the frequency of the microwave from the microwave generation source. Characteristic sputtering equipment.