JP3167390B2 - Chemical vapor deposition equipment - Google Patents

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 apparatus used for manufacturing semiconductors and the like.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional chemical vapor deposition apparatus. The infrared lamp 1 in the atmosphere is passed through the quartz window 11 airtightly attached to the vacuum chamber 50.
2, and the backside of the substrate support 14 is heated by irradiating heat rays from the heat ray reflecting mirror 13 behind the board. Then, the substrate 10 is pressed against the substrate support 14 by the fixture 16, the temperature of the substrate 10 is increased by conduction heating from the substrate support 14, and the substrate 10 is removed from the entire upper surface of the gas supply unit 18 opposed to the substrate 10. A desired thin film is formed on the substrate 10 (lower surface in the figure) by chemical vapor reaction. Unreacted gas and generated gas are exhausted by the exhaust unit 20.
It is configured to exhaust from.

In order to prevent the film from being formed on the surface of the fixture 16, a cooling medium passage 21 is provided inside the fixture 16, and a cooling medium 22 is supplied to the cooling medium passage 21 to constantly cool the fixture. 40 is an inlet of the cooling medium, and 42 is an outlet. Film formation is usually performed at a substrate temperature of 300 ° C. to 500 ° C. and a gas pressure of 0.
The temperature and pressure range is from 01 Torr to 100 Torr.

[0004]

However, in the above-described conventional apparatus, a reactive gas is introduced into a high-vacuum vacuum chamber 50, the pressure of which rises to 1 Torr or more, and the thermal conductivity of the gas increases. Then, due to heat conduction using the introduced gas as a medium, the temperature distribution on the surface of the substrate 10 is affected by the temperature of the fixture 16 as well as the temperature distribution of the substrate support 14 in contact with the substrate behind. .

Accordingly, in order to make the temperature distribution of the substrate 10 uniform, it is necessary not only to make the temperature distribution of the substrate support 14 uniform, but also to make the temperature distribution of the fixture 16 uniform.

In the conventional chemical vapor deposition apparatus, the fixture 1
Since the flow of the cooling medium 22 flowing through the cooling medium passage 21 in the inside 6 is fixed in only one direction, a large difference occurs in the temperature of the cooling medium 22 between a part near the cooling medium inlet 40 and a part near the outlet 42, The temperature distribution of the fixture is biased, which deteriorates the temperature distribution of the substrate 10 and the film thickness distribution of the film formation.

For example, a thin film of W (tungsten) is formed on the surface of a Si (silicon) substrate 10 at a gas pressure of 1 to 100 Torr and 350 to 500 ° C. using H ₂ (hydrogen) and WF ₆ (tungsten fluoride) gas. To keep the fixture at a temperature where the film does not adhere to its surface when making it,
Although it was necessary to flow cooling water at 20 to 100 ° C. and a flow rate of 0.1 to 3 liters / minute through the cooling medium passage, the W film formed on the substrate surface at this time had a thickness of 1.0 μm. In the case of, it was as poor as ± 15%.

If the flow rate of the cooling medium is increased, the temperature difference between the entrance and the exit can be reduced, and the above-mentioned bias in the temperature of the fixture 16 can be reduced. But if you do this,
It increases the heat absorption of the fixture, which worsens the temperature distribution of the substrate. In order to reduce heat absorption, the temperature of the cooling medium must be increased to a maximum temperature (for example, around 200 ° C. in the above case) at which film formation is not performed. Causes a new problem of increasing the cost of the vapor phase growth apparatus.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a chemical vapor deposition apparatus which can make a substrate temperature distribution uniform with a cooling medium having a relatively low temperature and a small flow rate and obtain a good film thickness distribution.

[0010]

The chemical vapor deposition apparatus according to the present invention comprises a flow direction switching unit for periodically reversing the flow direction of the cooling medium in the cooling medium passage provided inside the fixture. It is characterized by having.

[0011]

According to the chemical vapor deposition apparatus of this construction, the cooling medium inside the fixture is inverted periodically as appropriate, so that the heat capacity of the fixture is skillfully used to achieve a small flow rate and With a relatively low temperature cooling medium, the temperature distribution of the fixture can be made uniform to the extent practically acceptable. In other words, the temperature at the inlet and outlet of the cooling medium of the fixture periodically rises and falls somewhat, but the maximum temperature in the temperature change cycle is kept within the film formation limit, and the substrate temperature distribution is made uniform. And a good film thickness distribution can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the drawings merely schematically show the shapes, sizes, and arrangements of the components so that the present invention can be understood. FIG. 1 is a sectional view of a main part showing a configuration of a chemical vapor deposition apparatus according to an embodiment of the present invention. FIG. 2 schematically shows only the flow of the cooling medium in the apparatus of FIG. The same reference numerals are given to members common to FIG. 3 described above, and detailed description thereof will be omitted unless otherwise specified.

In the structure of this embodiment, unlike the conventional example described above, a film is not formed on the surface of the fixture 16 so as to prevent the film from being formed.
The cooling medium 22 flows through a cooling medium passage 21 provided inside the fixture 16 to constantly cool the fixture 16.
However, in this embodiment, a flow direction switching unit 60 is provided between the cooling medium supply ports 52 and 54 of the fixture 16 and the cooling medium inlet 40 and outlet 42. This flow direction switching unit 60 is newly provided with switching valves 26, 28, 30, 32,
A switching controller 34 for controlling them is provided. The switching valves 26 and 32 and the switching valves 28 and 3
0, are pairs, for example, one pair (26 and 3)
When 2) is open, the valve is controlled to periodically open and close such that the other pair (28 and 30) is closed or vice versa. That is, at first, the switching valves 26 and 32 are opened, and the switching valves 28 and 30 are closed, and the traveling direction of the cooling medium 22 is in the direction of the arrow A. The direction of travel is arrow B
Direction. This inversion is repeated at a constant cycle.

In this case, each time the switching valve is repeatedly opened and closed, the inlet and outlet of the cooling medium are alternated, and the flow direction is reversed. For this reason, the temperature distribution of the fixture 16 having a thermal inertia (time constant of temperature rise / fall) longer than the repetition period depends on the inlet and outlet of the cooling medium 22 and the fixture 16.
The temperature difference becomes extremely small between the whole of the inside and the temperature rises and falls repeatedly within the small temperature range. By adjusting the flow rate so that the maximum value of the temperature range is equal to or lower than the film forming limit temperature, the fixture 1 can be fixed.
6 can be completely suppressed from being formed on the surface.

The optimum value of the opening / closing repetition cycle varies depending on the film material for film formation, the film material, the temperature and pressure conditions of each member, but is generally selected to be considerably smaller than the film formation time. When 100 seconds or more, the repetition cycle is 1
It takes about 0 to 20 seconds.

When the gas pressure is 1 Torr or more, the flow rate is generally selected to be a relatively small value of 0.01 liter / min to 0.1 liter / min. The temperature of the cooling medium 22 is
In general, when the cooling medium 22 is water, it is supplied at 90 ° C. to 50 ° C., and when the cooling medium 22 is of an oil type, it is supplied at a temperature of 100 ° C. or higher.

As an example, H ₂ (hydrogen) and WF
₆ Si (tungsten fluoride) gas as reactive gas
When a 1.0 μm W film is formed on the substrate, the temperature of the substrate support 14 is maintained at 400 ° C. with respect to the reactive gas pressure of 50 Torr and the optimum substrate temperature of 400 ° C.
6, hot water of 90 ° C. and 0.1 liter / min was flowed at a cycle of opening and closing for 10 seconds. At this time, the inlet temperature of the cooling medium was 90 ° C. and the outlet temperature was 91 ° C., and the temperature of the fixture was 150 ° C. throughout the film formation time of 2.0 minutes.
Below, there was no film adhering to the fixture. The thickness distribution of the formed film on the substrate could be maintained at ± 5% or less at a film thickness of 1 μm.

The heating device for the substrate supporting device of the present invention may be a resistance wire, a high-frequency heating device, in addition to an infrared lamp.
Other various things can be adopted.

[0019]

According to the chemical vapor deposition apparatus of the present invention, the temperature distribution of the fixture is made uniform with a relatively low temperature and small flow rate of a cooling medium, and even under high temperature and high pressure film forming conditions, The maximum temperature of the fixture can be kept within the film forming limit, and the temperature distribution of the substrate can be made uniform to obtain a good film thickness distribution.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a chemical vapor deposition apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing only the flow of the cooling medium of FIG. 1 taken out.

FIG. 3 is a schematic sectional view of a conventional chemical vapor deposition apparatus.

[Explanation of symbols]

10: substrate, 11: quartz window, 1
2: Infrared lamp 13: Heat ray reflecting mirror, 14: Substrate support, 1
6: Fixture 18: Gas supply unit, 20: Gas exhaust unit, 2
1: cooling medium passage 22: cooling medium 26, 28, 30, 32: switching valve 34: switching controller 40: cooling medium inlet 4
2: cooling medium outlet 50: vacuum chamber 52, 54: cooling medium supply port 60: flow direction switching unit.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 16/00-16/56 C23C 14/00-14/58 H01L 21/205 H01L 21/285

Claims (1)

(57) [Claims] 1. A vacuum chamber comprising a gas supply unit, an exhaust unit, a substrate support for heating by a heating device, and a fixture having a cooling medium passage therein. In a chemical vapor deposition apparatus in which a pressure is applied by the fixture and a reactive gas is supplied from the gas supply unit to form a thin film on the substrate surface, the flow direction of the cooling medium flowing through the cooling medium passage is periodically changed. A chemical vapor deposition apparatus comprising a flow direction switching unit for reversing the flow direction.