JPH0722405A - Method and device for chemical vapor growth - Google Patents

Abstract

PURPOSE:To improve the coating ratio of a vertical step part by absorbing the monomer, dimer and trimer formed from raw material gas when a thin film is formed on a semiconductor substrate, and irradiating with an ion beam on the semiconductor substrate at the same time. CONSTITUTION:The deposition reaction of a semiconductor step part is indicated when a thin film is deposited on a semiconductor substrate and an ion beam is cast is indicated. At a flat part 13, etching reaction is accelerated and the formation of the thin film is suppressed because ion 16 is cast at high energy. Since the irradiation of the ion 16 is less at a vertical step part 12, the etching reaction is slow in comparison with the flat part. Since the thin film formed at the flat part is constituted of a monomer, a dimer and a trimer, the stable film quality is maintained even if the ion beam is applied. Thus, the thin film satisfying the characteristics of the semiconductor device is formed, and the coating rate of the vertical step part can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical vapor deposition method for a thin film used for manufacturing a semiconductor device and the apparatus therefor, and more particularly to a chemical vapor deposition method for increasing the coverage rate of the thin film on a step portion of a semiconductor substrate. Law and its equipment.

[0002]

2. Description of the Related Art In a conventional chemical vapor deposition method, when a steep step exists on a fine pattern of a semiconductor device for forming a thin film, the coverage of the thin film decreases at this step,
The thickness of the thin film is insufficient in the vertical portion of the step, and desired semiconductor device characteristics cannot be obtained. Therefore, it is important to improve the step coverage of the thin film. Therefore, in order to form a thin film with good coverage on the step vertical portion, a bias application CV for depositing an ion beam on the semiconductor device substrate during thin film formation.
There is D method.

However, when a thin film formed on a semiconductor substrate, for example, a silicon oxide film or a silicon nitride film is formed by using the above method, precursors of the silicon oxide or silicon nitride are formed in a vapor phase. Since tetraethoxysilane, which is a body, and an organic silicon compound are deposited on a semiconductor device substrate while adsorbing, a thin film is formed, and thus Si--Si and Si-- which are unstable bonds in the polymer in the thin film. When a thin film containing a large amount of C is irradiated with an ion beam, the film quality of the thin film is significantly deteriorated due to the formation of a dangling bond due to the dissociation of this unstable bond. Therefore, there is a problem that the characteristics of the semiconductor device cannot be satisfied.

[0004]

Therefore, an object of the present invention is to form a thin film satisfying the characteristics of a semiconductor device,
It is an object of the present invention to provide a chemical vapor deposition method and an apparatus for improving the coverage of a step vertical portion.

[0005]

Means for Solving the Problems The above-described objects are to adsorb monomers, dimers and trimers produced from a raw material gas during thin film formation on a semiconductor device substrate and at the same time to apply an ion beam to the semiconductor substrate. It is achieved by a chemical vapor deposition method which is characterized by incidence.

According to the present invention, in order to adsorb a monomer, a dimer and a trimer on a semiconductor device substrate, the pressure in plasma is close to the saturated vapor pressure of the monomer, the dimer and the trimer. As described above, the chemical vapor deposition method is characterized in that the temperature of the semiconductor substrate is controlled to be cooled between room temperature and −70 ° C.,
Further, the present invention is a chemical vapor deposition method characterized in that plasma for producing monomers, dimers and trimers from a source gas is formed by electron cyclotron resonance.

The above objects are also achieved by a chemical vapor deposition apparatus characterized in that a means for cooling the temperature of a semiconductor substrate between room temperature and -70 ° C. is provided.

[0008]

According to the present invention, the semiconductor substrate on which the film is formed is kept at room temperature.
By using a plasma enhanced chemical vapor deposition apparatus provided with a means for controlling cooling between 70 ° C., a semiconductor substrate on which a thin film is deposited has a pressure in the apparatus saturated with a monomer, a dimer and a trimer. By cooling to a temperature such that the vapor pressure is obtained, a film having a relatively low degree of polymerization such as a monomer, a dimer and a trimer is adsorbed on the cooled semiconductor device substrate to form a thin film. It is formed. Then, the irradiation of the ion beam suppresses the deposition of the thin film on the step portion due to the etching reaction of the formed thin film. On the other hand, since the ion beam does not enter the step vertical portion, the deposition of the thin film proceeds. As a result, the thin film coverage in the step vertical portion is improved.

At this time, since the thin film in the flat portion irradiated with the ion beam is composed of the monomer, the dimer and the trimer, it has a stable film quality and the film quality of the film irradiated by the ion beam. It is possible to improve the coverage ratio of the step vertical portion while forming a thin film that does not deteriorate and satisfies the characteristics of the semiconductor device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the drawings.

FIG. 1 shows a schematic view of a chemical vapor deposition apparatus according to the present invention. In this embodiment, electron cyclotron resonance is used for plasma formation. For forming a thin film, after decompressing the chamber 3 with the vacuum pump 4, the raw material gas and the diluting gas are introduced into the chamber 3 through the gas flow rate control device 2 from the gas introduction port 1. Then, while evacuating the inside of the chamber 3 with the vacuum pump 4, the pressure control device 5 is used to maintain a constant pressure. After that, a microwave is introduced from the magnetron 6 through the waveguide 7, a magnetic field is formed by the coil 8, plasma is formed, and a thin film is deposited on the semiconductor device substrate 9. At this time, the semiconductor device substrate 9 is loaded on the electrode 10, and a high frequency is applied to the electrode 10 to attract the ions 16 from the plasma. The temperature of the electrode 10 is controlled by the temperature controller 11. The electrode 10 is a means for controlling the temperature of the semiconductor substrate to be cooled from room temperature to −70 ° C., and is cooled from room temperature to about −70 ° C., for example, by controlling cooling and heating with liquid nitrogen and an electric heater. You can

FIG. 2 shows the deposition reaction of the step portion of the semiconductor device when the thin film is deposited on the semiconductor device substrate 9 and the ion beam is not irradiated. Substrate 9 in which the pressure in the plasma is near the saturated vapor pressure of the monomer or dimer
Since the temperature is achieved by cooling the electrode 10, the deposition reaction of the monomer 14 and the dimer 15 occurs in the step vertical portion 12 and the flat portion 13. In this state, since the vertical portion of the step is steep, the deposition rate is slower than that of the flat portion, and the coverage is low.

FIG. 3 shows the deposition reaction of the step portion of the semiconductor device when the thin film is deposited on the semiconductor device substrate 9 and is irradiated with an ion beam. Flat part 13 is ion 16
However, the incidence of ions 16 on the step-difference vertical portion 12 is slower than that on the flat portion because the ion 16 is less incident on the step-vertical portion 12. Further, since the thin film formed on the flat portion is composed of a monomer, a dimer and a trimer, the stable film quality is maintained even when irradiated with an ion beam. It is possible to improve the coverage of the step vertical portion while forming a thin film that satisfies the above condition.

As a further specific example, a method of forming a silicon oxide film on a semiconductor substrate at a step having an aspect ratio of 1.6 (opening 0.5 μm, depth 0.8 μm) by an oxide film will be described.

The pressure of the plasma formed in the chamber 3 when depositing a silicon oxide film using the above-mentioned apparatus is about 1 × 10 ^-5 Torr. The temperature is about −50 to −70 ° C. because this pressure is near the saturated vapor pressure of the monomer, dimer and trimer. Therefore, the temperature of the electrode 10 on which the substrate 9 is loaded is set to -50 to -70 ° C.
The temperature is controlled by the controller 11. Then, when the substrate temperature reaches −50 to −70 ° C., the pressure is set to 1 × 1.
While maintaining at 0 ^-5 Torr, tetraethoxysilane was introduced into the chamber 3 as a source gas, microwaves were introduced from the magnetron 6 through the waveguide 7, and a magnetic field was formed by the coil 8 to form plasma. , Ionize silicon oxide from the raw material gas, SiO ₂ monomer,
The thin films of the dimer 14 and the trimer 15 are attached to the semiconductor device substrate 9
To deposit. At this time, a high frequency is applied to the electrode 10,
The semiconductor substrate 9 is irradiated with an ion beam by drawing in the ions 16 from the plasma. Thus, the silicon oxide film can be deposited on the step portion on the semiconductor substrate with good step coverage.

[0016]

As described above, according to the present invention, in a chemical vapor deposition apparatus using electron cyclotron resonance for plasma formation, a thin film coating on a step portion does not occur without deterioration of the thin film quality due to ion beam irradiation. It is possible to improve the rate.

[Brief description of drawings]

FIG. 1 is a drawing for explaining a chemical vapor deposition apparatus in an example of the present invention.

FIG. 2 is a diagram showing a deposition reaction of a semiconductor device step portion when an ion beam is not irradiated.

FIG. 3 is a diagram showing a deposition reaction of a semiconductor device step portion when an ion beam is irradiated.

[Explanation of symbols]

1 ... Gas inlet, 2 ... Gas flow control device,
3 ... Chamber, 4 ... Vacuum pump, 5 ... Pressure control device, 6 ... Magnetron, 7 ... Waveguide,
8 ... Coil, 10 ... Electrode, 11 ... Temperature controller, 11 ... Vertical step portion, 12 ... Vertical portion, 13 ... Flat portion, 14 ... Monomer,
15 ... Dimer, 16 ... Ion.

Claims (4)

[Claims] 1. A chemical vapor characterized by adsorbing a monomer, a dimer and a trimer produced from a raw material gas at the time of forming a thin film onto a semiconductor device substrate and at the same time making an ion beam incident on the semiconductor substrate. Phase growth method. 2. The pressure in plasma is near the saturated vapor pressure of the monomer, dimer and trimer in order to adsorb the monomer, dimer and trimer onto the semiconductor device substrate. The chemical vapor deposition method according to claim 1, wherein the temperature of the semiconductor substrate is controlled to be cooled from room temperature to -70 ° C. 3. The chemical vapor deposition method according to claim 1 or 2, wherein plasma for producing monomers, dimers and trimers from the raw material gas is formed by electron cyclotron resonance. . 4. A chemical vapor deposition apparatus provided with means for controlling cooling of the temperature of a semiconductor substrate between room temperature and −70 ° C.