JP2650326B2 - Plasma processing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, and more particularly, to an ECR (Ele).
ctron Cyclotron Resonance)
Diamond and DLC (Diamond using plasma CVD method)
(Thin Carbon).

[Conventional technology]

Conventionally, as a method of forming a diamond film or a DLC film, there are a hot filament CVD method, a microwave CVD method, and the like.
In the hot filament CVD method, a vacuum device (reaction chamber)
A substrate and a filament placed on the substrate holder are provided. Then, the reaction chamber is maintained at several tens of Torr, and methane, hydrogen, and the like are introduced as a reaction gas. Thereafter, the reaction chamber is heated from the outside, and the substrate is heated by the filament provided inside the reaction chamber to form a film.

In the microwave CVD method, a substrate is placed in a reaction chamber in the same manner as described above, and a microwave and a reaction gas are introduced. The reaction gas, that is, methane and hydrogen is decomposed by the plasma generated by using the microwave to form a film.

[Problems to be solved by the invention]

However, it is difficult to form a uniform diamond film or the like on a substrate having a large area or a plurality of substrates by the conventional method as described above, and is not suitable for mass production. That is, there is a case where it is desired to simultaneously form a film on a plurality of silicon wafers in order to increase the efficiency of film formation. However, in the conventional method as described above, a diamond film is simultaneously formed on a plurality of substrates. Is very difficult to form.

For example, when simultaneously forming a diamond film or the like on a plurality of substrates in the hot filament CVD method, a uniform filament having a shape capable of covering all of the plurality of substrates is formed, and this is uniformly heated. is necessary. However, it is very difficult to realize such an apparatus. In the microwave CVD method, the part where plasma is generated is limited due to its structure.
It is difficult to control the plasma state by the CVD method.

Also, in the ECR plasma CVD method, it is considered to increase the area of a substrate on which a film can be formed by forming a divergent magnetic field. However, forming a diamond film requires a particularly high plasma density, and it is extremely difficult to form a diamond film by the method of forming a film using a divergent magnetic field as described above.

The present invention has been made in view of the above points, and provides a plasma processing apparatus capable of easily forming a uniform thin film such as a diamond film and a DLC film on a large-area substrate or a plurality of substrates. With the goal.

[Means for solving the problem]

A plasma processing apparatus according to the present invention is a cavity configured to receive a sample to be processed and to introduce a reaction gas, a cavity configured to generate a plasma by introducing a microwave, and the reaction chamber. And a magnetic circuit for forming an electron cyclotron resonance magnetic field inside the chamber, wherein the plasma chamber is formed in the reaction chamber. A sample is arranged on an inner wall of a chamber, and a high-density plasma region is generated in a region where the sample is arranged.

[Action]

In the present invention, in the microwave plasma CVD method,
It utilizes the fact that plasma can be controlled by applying a magnetic field. That is, as shown in FIG.
When the reaction chamber is kept in a predetermined low pressure state, a discharge is generated with a small electric field intensity at a certain fixed magnetic flux density, and plasma is generated. Therefore, if this characteristic is used, a high-density plasma region can be generated only in a predetermined region using a magnetic field. In this high-density plasma region, compared with a conventional film forming method using a divergent magnetic field, etc. To easily form a diamond film or the like.

Therefore, for example, a plurality of substrates are disposed on the inner wall of the annular reaction chamber, or a substrate having a large area is disposed, and the high-density plasma region is formed in a portion where the substrates are disposed. Can be formed uniformly and efficiently.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First
FIG. 1 is a configuration diagram showing a film forming apparatus as a plasma processing apparatus according to a first embodiment of the present invention. In the drawing, reference numeral 1 denotes a reaction chamber, the main body 1c of which is formed in an annular shape, and a partial cross section thereof is shown in FIG. The reaction chamber 1 has a cavity structure. In the reaction chamber 1,
Magnetron 6 as microwave source (frequency 2.45GH
Microwave is introduced from z) through the waveguide 4 and the microwave introduction window 5, and the reaction gas (for example, methane, such as H ₂ , CO, CO ₂ , CH _4, etc.) is supplied through the reaction gas supply port 1a. Alcohols, ketones, amines) are introduced.

On the inner wall of the reaction chamber 1, a plurality of silicon wafers 3 are arranged as substrates on which a film is to be formed, and each of these silicon wafers 3 is mounted on a substrate holder 2 mounted on the inner wall of the reaction chamber 1. ing. Each of the substrate holders 2 is provided with a heater, and each heater is connected to a heater power supply (not shown) provided outside the reaction chamber 1. The reaction chamber 1 is provided with an exhaust port 1b, and an exhaust system (not shown) including a vacuum pump or the like is connected to the exhaust port 1b.

Electromagnets 7a and 7b as magnetic circuits are arranged around the main body 1c of the reaction chamber 1, and the electromagnets 7a and 7b
Is determined so that the conditions of electron cyclotron resonance by microwaves are satisfied inside the reaction chamber 1. Here, the magnetic flux density for causing the electron cyclotron resonance with respect to the microwave having the frequency of 2.45 GHz is 875 G. In the present embodiment, the magnetic flux density is about twice as large as, for example, 2 k.
Using an electromagnet having a strength of G, as shown in FIG. 13,
A magnetic field gradient is provided at the position of 875G.

 Next, the operation will be described.

After evacuation of the inside of the reaction chamber 1, a reaction gas is introduced and the pressure is kept constant (30 to 0.01 Torr). Next, magnetron 6
Generates a microwave, introduces the microwave into the reaction chamber 1 through the waveguide 4 and the introduction window 5, and generates a magnetic field by passing a current through the electromagnets 7a and 7b. Then, plasma discharge occurs in the reaction chamber 1. At this time, when the silicon wafer 3 heated to about 600 to 1000 ° C. by the heater is placed in or near the plasma, a diamond film is formed on the silicon wafer 3.

At this time, the discharge region, that is, the high-density plasma region changes depending on how the magnetic field is applied. Now, the case where the pressure is maintained at a relatively high state (about 10 Torr or more) will be described. The frequency of the microwave introduced into the reaction chamber 1 is 2.45
GHz, the strength of the magnetic field applied by the electromagnets 7a and 7b is represented by the magnetic field curve shown in FIG.
Plasma discharge occurs in the region A shown in FIG. 1 centering on 875G satisfying the conditions, and a high-density plasma region is formed in this region. In this case, no discharge occurs in other places.

Therefore, if the region A is formed in the portion where the silicon wafer 3 is arranged, a plurality of silicon wafers 3
, A diamond film is formed uniformly.

When the pressure is low (about 10 Torr or less), the above-mentioned plasma clumps are not clearly seen, and the plasma spreads as a whole. By arranging a plurality of silicon wafers 3 in this region, it is possible to form a uniform film on each silicon wafer 3.

Here, as is clear from the magnetic field curve shown in FIG.
The other A 'point of 875G by the electromagnets 7a and 7b is:
Since it is outside the reaction chamber 1, the high-density plasma region is limited to only one inside the reaction chamber. In addition, high pressure at which the effect of the magnetic field is reduced (curve in Fig. 12 (30 Torr))
In this case, since the magnetic field gradient in the reaction chamber 1 is always higher on the microwave introduction side, the high-density plasma region is always limited to one in this case as well.

In this embodiment, a plurality of silicon wafers 3 are arranged on the inner wall of the reaction chamber 1 and a high-density plasma region is formed at a position where the silicon wafers 3 are arranged. A uniform diamond film can be easily formed on the silicon wafer 3 at one time.

Further, as shown in FIG. 3, since the magnetic field gradient is formed at the position of 875 G, the energy of the microwave is concentrated and converted in the predetermined region which is the high-density plasma region, and the sharpness is increased. A high-density plasma region can be formed, and in particular, the formation of a diamond film becomes easy.

Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. The main body 1c of the reaction chamber 1 of this embodiment is formed in a cylindrical shape, and a silicon wafer 3 is provided on a plurality of rows on its inner wall as a substrate on which a film is to be formed, as shown in the cross section of FIG. Have been. Each silicon wafer 3 is mounted on a substrate holder 2 mounted on the inner wall of the reaction chamber 1, and each substrate holder 2 is provided with a heater 13.

Electromagnets 7a and 7b as magnetic circuits are arranged around the main body 1c of the reaction chamber 1 as in the above-described embodiment, and the electromagnets 7a and 7b are both mounted and fixed on the moving table 8. It can be moved by an electromagnet moving mechanism. The electromagnet moving mechanism includes a rack 8a fixed to the moving table 8, a pinion 9 meshing with the rack 8a, and a motor 10 for rotating the pinion 9 via a belt 11.

The conditions such as the microwave frequency and the magnetic flux density are the same as those in the above-described embodiment, and an electromagnet having a strength of 2 kG is used. As shown in FIG. 13, a magnetic field gradient is applied at the position of 875 G. It is also the same. FIG. 6 shows the magnetic field characteristics applied to the device.

Next, the operation of the second embodiment will be described. The operation up to the formation of the high-density plasma region is the same as in the above embodiment. The high-density plasma region corresponds to A in FIG.
(Corresponding to A in FIG. 6)
The motor 10 is operated to move the movable base 8 by the pinion 9 and the rack 8a to move the electromagnets 7a and 7b to the right (indicated by a two-dot chain line) in the figure. Then, the discharge region moves with the movement of 875G, and the high-density plasma region moves to the position B in FIG.
(Corresponding to B in FIG. 6).

By moving the electromagnets 7a and 7b in this manner, the high-density plasma region scans over a plurality of rows of silicon wafers 3 arranged on the inner wall of the reaction chamber 1, and uniformly scans each silicon wafer 3 at once. Thus, a natural diamond film is formed.

The same applies to the state where the pressure is low (about 10 Torr or less). It is possible to move the high-density plasma region and form a uniform film on each silicon wafer 3.

In this embodiment, since the high-density plasma region formed at a predetermined position in the reaction chamber 1 can be moved, the silicon wafers 3 arranged in a plurality of rows can be moved at a time.
In addition, a uniform diamond film can be easily formed, and high efficiency of film formation can be achieved.

Further, in this embodiment, even when the high-density plasma region is moved, the magnetic field gradient does not change, and the control relating to film formation can be stably performed.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is a modification of the electromagnet moving mechanism in the second embodiment. That is, in this embodiment,
In order to move the high-density plasma region, the electromagnet is moved electrically, not mechanically.

In the figure, the same reference numerals as those in FIG.
A large number of electromagnets 7c to 7i are arranged on the outer periphery of the main body 1c of the reaction chamber 1. Then, by adjusting the current supplied to each of the electromagnets 7c to 7i, the magnetic field characteristic (the position of 875G) is moved as shown by the solid line (C) and the broken line (D) in FIG. The high-density plasma region formed in the region is moved.

According to such an embodiment, the same effects as those of the above embodiment can be obtained, and a mechanical moving mechanism is not required.
The configuration can be simplified. In this embodiment, by adjusting the current supplied to each of the electromagnets, the magnetic field gradient can be reduced as shown by a two-dot chain line E in FIG. Magnetic field curves C and D
Unlike this, a somewhat widened plasma region can be formed.

FIG. 9 shows a fourth embodiment of the present invention. In this embodiment, the magnetic field is moved only by increasing or decreasing the current applied to the electromagnets 7a and 7b. In this embodiment, as shown by F and G in FIG. 10, the gradient of the magnetic field characteristic changes, but the configuration for mechanically moving the electromagnets 7a and 7b also controls the electrical movement. No circuit is required, and the configuration becomes very simple.

In each of the above embodiments, the formation of the diamond film and the DLC film has been described. However, for example, only H ₂ or O ₂ is used, and impurities (for example, graphite) adhered to the substrate by the same operation as the above embodiment. , Amorphous carbon) and the like can be removed by etching. Further, the sample is not limited to the silicon wafer as in each of the above embodiments. For example, a plate material 14 such as a molybdenum (Mo) plate is set on a heater 15 as shown in FIG. It is also possible to form a film on the plate material 14.

In the second to fourth embodiments, the high-density plasma region is made variable by a magnetic field. However, the high-density plasma region may be made variable by other parameters such as a reaction gas supply method or a microwave introduction method. Good.

In the above embodiment, the reaction chamber has a resonator structure.
For example, the present invention can be applied to a reaction chamber in which one of the reaction chambers is tapered and one of the reaction chambers is opened.

Further, the present invention can be widely applied to a film forming apparatus that performs electrodeless discharge using a microwave.

〔The invention's effect〕

As described above, according to the present invention, in particular, a diamond film and a DLC film can be uniformly and stably formed over a wide area or on a large number of samples such as a substrate. This has the effect of increasing the efficiency of film formation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a plasma processing apparatus according to a first embodiment of the present invention, FIG. 2 is a partial cross-sectional configuration diagram of a reaction chamber thereof,
FIG. 3 is a diagram showing a magnetic field characteristic applied to the plasma processing apparatus, FIG. 4 is a cross-sectional view of a plasma processing apparatus according to a second embodiment of the present invention, FIG. FIG. 6 is a diagram showing a magnetic field characteristic applied to the plasma processing apparatus shown in FIG. 4, FIG. 7 is a partial cross-sectional view of a plasma processing apparatus according to a third embodiment of the present invention, and FIG. FIG. 9 is a diagram showing a magnetic field characteristic applied to the apparatus, FIG. 9 is a partial cross-sectional configuration diagram of a plasma processing apparatus according to a fourth embodiment of the present invention, FIG. 11
The figure shows a modified example of the sample, FIG. 12 shows the relationship between the strength of the magnetic field and the pressure and the electric field strength at the start of discharge, and FIG. 13 shows the general characteristics of the magnetic field applied to the apparatus of the present invention. FIG. 1 ... reaction chamber, 3 ... silicon wafer (sample), 6 ...
Magnetron, 7a-7i ... Electromagnet (magnetic circuit).

Claims (1)

(57) [Claims] The present invention relates to a cavity in which a microwave is introduced to generate a plasma, a reaction chamber configured to accommodate a sample to be processed and to introduce a reaction gas, and to be arranged around the reaction chamber. A magnetic circuit for forming a magnetic field for electron cyclotron resonance provided inside the chamber, wherein a plasma region is formed in the reaction chamber. A plasma processing apparatus wherein the sample is arranged, and a high-density plasma region is formed in a region where the sample is arranged.