JP3193178B2 - Thin film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a method of forming a thin film based on a microwave plasma CVD method using electron cyclotron resonance, and more particularly, to a method of forming a thin film excellent in mass productivity by increasing the film forming speed. About.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a thin film on a predetermined substrate surface, a chemical vapor deposition method (CVD method) is known. Among them, a microwave CVD method is long because of electrodeless discharge. It is widely used because it is stable over time and has good reproducibility. Recently, the conventional microwave C
In the VD method, an electron cyclotron resonance plasma CVD method (hereinafter, simply referred to as an ECR method) has been known for the purpose of suppressing contamination of impurities and improving plasma generation efficiency.

The conventional ECR method will now be described with reference to FIGS. 6 and 7, 2
1 is a generation chamber, 22 is a microwave waveguide, 23 is a microwave oscillator, and 24 is an electromagnetic coil. According to the ECR method, the microwave output from the microwave oscillator 23 is applied to the microwave waveguide 22 and the microwave introduction window 25.
Through the plasma generation chamber 21. Generation room 21
, A gas for generating plasma (raw material gas) is introduced from a gas introduction port 26 and exhausted from a vacuum exhaust port 27 so that the pressure in the production chamber 21 is kept constant. A magnetic field having a magnetic field intensity (0.0875 T (tessler) when the microwave frequency is 2.45 GHz) that causes electron cyclotron resonance in the plasma is applied by an electromagnetic coil 24 provided around the generation chamber 21. As a result, when microwaves enter the magnetic field and plasma is generated, electron cyclotron waves are induced and propagate in the plasma. Generated.

[0004] Further, the gas pressure is 10 ^{-2 to} 10 ^-1 Pa.
According to FIG. 6, when a film is deposited on the surface of the substrate 28 under the low pressure of the order, the plasma generation chamber 21 and the film deposition chamber 2 are formed.
9 are often separated from each other with the plasma extraction window 30 interposed therebetween.
As shown in (1), a substrate 28 is set in the plasma generation chamber 21 and film deposition is performed in the generation chamber 21.

[0005]

However, when the frequency of the microwave incident into the generation chamber 21 is 2.45 GHz in the above-mentioned conventional ECR method,
Microwave oscillators used for the purpose are generally commercially available and have a maximum rated power of only 5 kW. Oscillator exceeding 5 kW is very expensive, and the microwave input power cannot be increased. for that reason,
There are problems such as a low deposition rate of the film, a large number of substrates not being able to be disposed structurally, and lack of mass productivity. Accordingly, it is an object of the present invention to provide a method for forming a thin film that increases the power supplied to a microwave into a plasma generation chamber and is excellent in mass productivity.

[0006]

Means for Solving the Problems The present inventors have examined the above problems, and found that increasing the power supplied to the microwave into the plasma generation chamber increased the plasma density, thereby increasing the film density. We have obtained findings that the deposition rate of the plasma is greatly improved, and as a result of repeated studies based on the findings, we found that using at least two microwave oscillators, the microwaves were applied in a direction parallel to the magnetic field lines of the magnetic field applied to the plasma generation region. It has been found that, by facing incident light, a high plasma density can be obtained without using an expensive microwave oscillator, a plasma generation region can be expanded, and mass productivity can be improved.

That is, according to the thin film forming method of the present invention, a raw material gas is introduced into a reaction chamber, microwaves are made to enter through a microwave waveguide, and an external magnetic field exceeding a condition under which electron cyclotron resonance occurs in the reaction chamber. , A plasma is generated in the reaction chamber, and a thin film is deposited on a substrate placed in or near the plasma generation region. The magnetic flux density in a region outside the central portion of the reaction chamber that satisfies the condition for causing resonance is higher than that in the central portion of the reaction chamber, and the microwave is applied to a magnetic field line of a magnetic field applied to a plasma generation region. From the direction parallel to the reaction chamber.

[0008]

According to the thin film forming method of the present invention, since microwaves are incident from two opposite directions into the reaction chamber, it is possible to apply microwave power twice the maximum rated power per microwave oscillator. it can. Further, as shown in FIG. 4, the plasma density increases as the microwave input power increases. Further, the higher the plasma density, the higher the deposition rate of the film.

Further, according to the method of the present invention, the film is deposited on both surfaces of the substrate even when the plasma is divided by arranging the substrate so that the film deposition surface is perpendicular to the microwave incident direction. Can be performed, the film formation area can be doubled, and the substantial film deposition amount can be increased.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic layout diagram of a thin film forming apparatus used in the present invention. According to FIG. 1, microwave oscillators 2 and 3 are installed on opposite sides of a reaction chamber 1, and are supplied from microwave oscillators 2 and 3 via microwave waveguides 4 and 5 and microwave introduction windows 6 and 7. It is arranged such that microwaves are introduced into the reaction chamber 1. On the other hand, electromagnetic coils 8, 9, 1 for applying a magnetic field such that electron cyclotron resonance occurs inside the reaction chamber 1 are provided around the reaction chamber 1.
0 and 11 are provided. Further, a gas inlet 12 for introducing a reaction gas into the reaction chamber 1 and a vacuum exhaust port 13 for maintaining the inside of the reaction chamber 1 at a predetermined pressure are provided. A substrate 1 on which a film is to be deposited is provided inside the reaction chamber 1.
4 and 15 are installed.

According to the thin film forming method of the present invention, a reaction gas is introduced into a reaction chamber 1 at a predetermined flow rate from a gas inlet 12 in FIG. 5 and microwave introduction windows 6, 7
The plasma is generated in the reaction chamber 1 by introducing a microwave into the reaction chamber 1 through the. Further, with respect to the plasma generation region 16 in the reaction chamber 1, the electromagnetic coil 8,
A magnetic field is applied so as to satisfy the electron cyclotron resonance conditions according to 9, 10 and 11. At this time, when the frequency of the microwave is set to, for example, 2,45 GHz, 0.087 near the plasma generation region 16 located at the center of the reaction chamber 1.
A magnetic field is applied so that 5T (Tessler) = 875 Gauss.

In such a configuration, according to FIG. 2 showing the magnetic field configuration in the thin film forming apparatus of FIG. 1, the lines of magnetic force (solid lines in FIG. 1) in the microwave introduction windows 6 and 7 of the reaction chamber 1 correspond to the microwave incident direction. It is controlled to be parallel. According to the present invention, the microwave introduced into the reaction chamber 1 needs to be introduced from a direction parallel to the magnetic field lines. This is based on the reason that only the clockwise circularly polarized component of the electromagnetic wave incident parallel to the magnetic field has no cutoff density and can propagate in high-density plasma. If not parallel, the microwave cannot propagate into the plasma, and the plasma density cannot be increased.

FIG. 3 shows the relationship between the distance from the left end of the reaction chamber 1 and the magnetic flux density.

As is apparent from FIG. 3, the ECR condition is satisfied in the center of the reaction chamber 1, and the magnetic field in the region outside the center is higher than 875 gauss.

According to this method, the input power in the reaction chamber 1 can be greatly improved. For example, even if the maximum rated power of the microwave oscillator to be used is 5 kW, up to 10 kW can be introduced into the reaction chamber 1. The input power can be increased.

For example, as is clear from FIG. 4 showing the relationship between the microwave input power and the plasma density, a hydrogen gas is introduced into the reaction chamber at a pressure of 13.3 Pa to generate hydrogen plasma, and a Langmuir probe is used. When the plasma density was measured, it was at most 6 × 10 ¹¹ cm ⁻³ in the conventional method shown in FIGS.

On the other hand, according to the method of the present invention, FIG.
As shown in the figure, as the input power of the microwave is improved, the plasma density can be increased to 10 × 10 ¹¹ cm ⁻³ or more, and the input power of 10 kW increases the plasma density to about 15 × 10 ¹¹ cm ^−3.
Was obtained.

Ar and Xe are used instead of hydrogen gas.
When the plasma density was measured under the same pressure using Ar, 1.6 × 10 ¹³ Ar was applied at a microwave input power of 10 kW.
cm ^-3, it could be obtained about twice the plasma density compared to 5 × 10 ¹³ cm ^-3 and either the conventional method in Xe.

Further, a diamond film was formed according to the present invention. CH ₄ gas was introduced as a reaction gas at a concentration of 5% together with hydrogen gas. The pressure in the reaction chamber is 4 to 4
As shown in FIG. 5, which shows the relationship between the reaction chamber pressure and the growth rate when the pressure was changed at 0 Pa, the lower the pressure, the higher the film formation rate (Growth Rate). , The film formation rate also improved. When a microwave of 10 kW was applied according to the present invention, the film formation rate under a pressure of 4 Pa was 1.
It was improved to about 3.4 times at 4 μkW at 2 μm / hr.

Further, as shown in FIG. 1, a substrate on a disk having a diameter of 100 mm in the reaction chamber 1 is placed back to back so that the film deposition surface is perpendicular to the microwave incident direction. When placed in such a state, an equivalent diamond film could be formed on the surface of each substrate at a high film forming rate of 0.6 μm / hr.

[0021]

As described in detail above, according to the present invention, it is possible to increase the power supplied to the microwave into the reaction chamber, thereby increasing the plasma density in the reaction chamber and increasing the film formation rate on the substrate. Can be improved. In addition, the area for forming the thin film on the substrate can be expanded, and the mass productivity of forming the thin film can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic layout view of a thin film forming apparatus used in the present invention.

FIG. 2 is a diagram showing a magnetic field configuration in the thin film forming apparatus of FIG.

FIG. 3 is a diagram showing a relationship between a distance from a left end of a reaction chamber and a magnetic flux density in the thin film forming apparatus of FIG.

FIG. 4 is a diagram showing a relationship between microwave input power and plasma density.

FIG. 5 is a diagram showing a relationship between a reaction chamber pressure and a growth rate.

FIG. 6 is a schematic layout diagram for explaining a conventional thin film forming method.

FIG. 7 is a schematic layout diagram for explaining another conventional thin film forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction chamber 2, 3 Microwave oscillator 4, 5 Microwave waveguide 6, 7 Microwave introduction window 8, 9, 10, 11 Electromagnetic coil 12 Gas introduction port 13 Vacuum exhaust port 14, 15 Substrate 16 Plasma generation area

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C23C 16/511 H01L 21/205 H01L 21/31 H05H 1/46

Claims (1)

(57) [Claims] 1. A raw material gas is introduced into a reaction chamber, microwaves are made incident through a microwave waveguide, and an external magnetic field exceeding an electron cyclotron resonance condition is applied to the reaction chamber. Generate plasma,
In the thin film forming method of depositing a thin film on a substrate provided in or near the plasma generation region, a magnetic flux density at a central portion in the reaction chamber satisfies a condition under which electron cyclotron resonance occurs, and The magnetic flux density in a region outside the central portion is made higher than that in the central portion of the reaction chamber, and the microwaves are oppositely incident on the reaction chamber from a direction parallel to the magnetic field lines of the magnetic field applied to the plasma generation region. A method for forming a thin film, comprising: