JPH0598447A - Photo assisted cvd device - Google Patents

Abstract

PURPOSE:To obtain a stable light intensity and thereby a stable film forming rate by preventing the temp. rise of a light source itself with a relatively simple means. CONSTITUTION:A gaseous reactant inlet 23 and outlet 24 are provided in a reaction chamber 21 contg. a substrate 22 to be treated so that the gaseous reactant flows almost in parallel with the substrate 22 surface. A light- transissive first gas injection plate 27 having many tiny holes 28 for passing an inert gas is arranged between the reaction chamber 21 and a light source chamber 29, the light source chamber 29 is divided by a second gas injection plate 31 having high reflectivity to the UV or vacuum UV and having many tiny holes, and a light-source lamp 30 is arranged between the plates 27 and 31. Since the light source 30 is cooled by the gas introduced from the plate 31, a definite illuminance is reached in a short time, and an effective and stable cycle time is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus used for manufacturing semiconductors, liquid crystal displays and the like.

[0002]

2. Description of the Related Art In recent years, silane,
Development of an optical CVD apparatus that decomposes a compound gas such as disilane to form a thin film on a silicon wafer or a glass substrate has been actively made. An optical CVD apparatus using such light can be processed at a low temperature and does not cause deterioration of a substrate or a formed film due to charged particles, and thus has attracted a great deal of attention as a next-generation device manufacturing method. However, in such a photo-CVD apparatus, there is a big problem that the reaction product stains the light-transmitting window and the surface of the lamp and the light amount is reduced. In order to deal with such a problem, for example, as shown in JP-A-60-209248, the reaction chamber and the light source chamber are partitioned by a UV-permeable porous plate, and an inert gas is discharged from the porous plate. By purging,
Proposals have been made to prevent contamination of the light transmission window and the lamp surface.

FIG. 3 is a sectional view showing an example of a photo-CVD apparatus which has been conventionally used. In the figure, 1 is a reaction chamber for accommodating a substrate 2 to be processed, and a reaction gas introduction system and an exhaust system are connected to an introduction port 3 and an exhaust port 4, respectively. A stage 5 on which the substrate 2 is mounted is installed in the reaction chamber 1 and is usually controlled to a constant temperature by a heater 6 or the like. The reaction chamber 1 is also connected to a light source chamber 9 via a quartz gas ejection plate 7 having a large number of small holes. As shown in FIG. 4, the quartz gas ejection plate 7 having a large number of small holes has small holes 8 having a uniform diameter distributed almost uniformly over the entire surface. On the other hand, the light source room 9
Is provided with a light source 10 that emits a wavelength suitable for a photochemical reaction so that the substrate 2 can be irradiated with light. An inert gas introducing system is also connected to the introducing port 11.

During operation, the reaction gas is introduced in a sheet form from the reaction gas introduction system through the introduction port 3 substantially in parallel to the surface of the substrate 2, decomposes or reacts with light having a suitable wavelength, and is introduced onto the substrate 2. Deposit a thin film. At this time, the inert gas introduced through the inert gas introduction port 11 is introduced into the reaction chamber 1 so as to face the surface of the substrate 2 through the quartz gas ejection plate 7 having a large number of small holes, and then to the light source 10. It is configured to prevent film adhesion.

[0005]

However, when film formation is performed for a long time by using the conventional photo-CVD apparatus configured as described above, the illuminance on the substrate gradually increases as the film formation time increases. It was found that there was a big problem that a constant film formation time could not be obtained during the actual production. It is presumed that this is because the light source is placed in a vacuum, so that the light source is not sufficiently cooled and the temperature of the light source itself rises. As a means to solve such a problem, controlling the electric power so that the illuminance of the light source is always constant can be considered, but it is not a good idea because it requires an illuminance meter and a control unit, which leads to high cost of the device. it is conceivable that.

The present invention solves the above problems,
It is an object of the present invention to provide an optical CVD apparatus capable of preventing a temperature rise of a light source itself by a relatively simple means and obtaining a stable light intensity and a stable film forming rate thereby.

[0007]

In order to achieve the above object, the photo-CVD apparatus of the present invention comprises a reaction chamber for accommodating a substrate to be processed, a means for introducing and exhausting a reaction gas into the reaction chamber, A light source for photochemically reacting a reaction gas to form a thin film on the substrate, a light source chamber for accommodating the light source, and a light-transmitting material having a large number of small holes between the reaction chamber and the light source chamber. A first gas jet plate is arranged, a first gas flow is introduced in a sheet form from a gas inlet port substantially parallel to the surface of the substrate housed in the reaction chamber, and the surface on the substrate is provided with this surface. A photo-CVD apparatus in which a second gas flow is introduced from the direction perpendicular to the above from the first gas jet plate to maintain the first gas flow in a laminar flow state in the vicinity of the surface of the substrate. , The light source chamber has a high reflectance for ultraviolet light or vacuum ultraviolet light, and more It is partitioned by a second gas ejection plate having small holes, a light source is arranged between the second gas ejection plate and the first gas ejection plate, and a second gas flow is generated from the second gas ejection plate. It is characterized in that the light source is introduced and cooled by the second gas flow.

[0008]

In the photo-CVD apparatus according to the present invention constructed as described above, the inert gas is first introduced from the second gas ejection plate,
Used to cool the light source. Then, by introducing the gas through the first gas jet plate into the reaction chamber, it is possible to prevent the conventional function, that is, the contamination of the light transmissive first gas jet plate and the lamp surface. Thus, stable film forming conditions can be obtained.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view of an optical CVD apparatus showing an embodiment of the present invention. In the figure, 21 is a reaction chamber made of aluminum for accommodating a 6-inch glass substrate 22, and a reaction gas introduction system and an exhaust system are respectively an introduction port 23 and an exhaust port 24.
It is connected to the. A stage 25 on which a 6-inch glass substrate 22 is mounted is installed in the reaction chamber 21, and the temperature is controlled to 250 ° C. by an infrared lamp heater 26.
The reaction chamber 21 has a large number of small holes 28 having a diameter of 0.6 mm, and is connected to a light source chamber 29 made of aluminum through a first gas ejection plate 27 made of quartz and having a size of 200 mm × 250 mm and a thickness of 2 mm. Has been done. A large-area low-pressure mercury lamp 30 that emits a wavelength suitable for a photochemical reaction is arranged in the light source chamber 29 so that the glass substrate 22 can be irradiated with light with a uniform illuminance.

The light source chamber 29 has a large number of small holes each having a diameter of 0.6 mm, and has a size of 300 mm × 300 mm and a thickness of 2 mm.
It is connected to an inert gas introduction chamber 32 made of aluminum through a second gas ejection plate 31 made of aluminum of mm. The inert gas introducing chamber 32 is provided with an inert gas introducing port 33, and is connected to an inert gas introducing system. A cooling water pipe (34) is arranged on the outer surfaces of the light source chamber 29 and the inert gas introducing chamber 32, and is constantly cooled.

Next, the operation (operation) will be described.
In the apparatus configured as described above, argon is used as the inert gas, and the flow rate is 0.5 and 10 slm (= 1 / min).
Then, the illuminance on the substrate surface was measured. FIG. 2 shows the relationship between the purge flow rate, the lighting time, and the relative illuminance obtained by the above measurement.

As shown in this figure, when the flow rate is 5, 10 slm as compared with 0 slm, a certain illuminance is reached in a relatively short time, and the illuminance also increases as the purge flow rate increases. ..

According to this embodiment, the inert gas is introduced into the inert gas introduction chamber 32 through the introduction port 33, and the low pressure mercury lamp 30 in the light source chamber 29 is purged through the second gas ejection plate 31. Therefore, the low-pressure mercury lamp 30
Is cooled, a certain illuminance is reached in a relatively short time, and a large illuminance is obtained, so that an efficient and stable cycle time can be obtained.

In the above embodiment, the inert gas is introduced from the second gas ejection plate 31 into the light source chamber 29 through the introduction port 33 and then into the reaction chamber 21 through the first gas ejection plate 27. Then, a structure is adopted in which the exhaust gas is exhausted together with the reaction gas. However, in order to effectively remove heat from the low-pressure mercury lamp 30, when a large amount of purge gas is used, it may adversely affect the film forming process in the reaction chamber 21, for example, the film forming rate and the film thickness distribution. Be done. Therefore, in such cases, the first
In order to keep the purge flow rate blown out from the gas jetting plate 27 constant, a structure may be adopted in which the excess gas is partially exhausted using the differential exhaust port 35 provided in the light source chamber 29. By doing so, the light source can be effectively cooled, and more stable illuminance and film forming speed can be obtained without changing the process in the reaction chamber.

[0015]

As described above, according to the present invention,
A light-transmissive first gas jet plate having a large number of small holes is arranged between the reaction chamber and the light source chamber, and the first gas injection port is provided substantially parallel to the surface of the substrate housed in the reaction chamber. A gas flow is introduced in a sheet form, and a second gas flow is introduced into the surface of the substrate from a direction perpendicular to the surface from the first gas ejection plate to bring the gas near the surface of the substrate. In a photo-CVD apparatus adapted to maintain the first gas flow in a laminar state, a second gas having a high reflectance in the light source chamber for ultraviolet light or vacuum ultraviolet light and having a large number of small holes. Since the light source can be cooled relatively easily by partitioning with the ejection plate and arranging the light source between the second gas ejection plate and the first gas ejection plate, the light source can be cooled in a short time and stable. A large illuminance can be obtained. Therefore, since the film forming rate is stable, the apparatus cost is not so high and the production cycle time can be stable.

[Brief description of drawings]

FIG. 1 is a sectional view of a photo-CVD apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram showing an illuminance measurement result when the flow rate of purge Ar obtained in an example of the present invention is changed.

FIG. 3 is a cross-sectional view showing a conventional example.

FIG. 4 is a plan view of a conventional gas ejection plate.

[Explanation of symbols]

 21 Reaction Chamber 22 Glass Substrate 23 Reaction Gas Inlet 24 Exhaust Port 25 Stage 26 Infrared Lamp Heater 27 First Gas Ejection Plate 28 Small Hole 29 Light Source Chamber 30 Low Pressure Mercury Lamp 31 Second Gas Ejection Plate 32 Inert Gas Induction Chamber 33 Inert gas inlet 34 Cooling water piping 35 Differential exhaust port

Claims (1)

[Claims] 1. A reaction chamber for accommodating a substrate, means for introducing and exhausting a reaction gas into the reaction chamber, and a light source for photochemically reacting the reaction gas to form a thin film on the substrate. A light source chamber for accommodating the light source, and a light-transmitting first gas ejection plate having a large number of small holes between the reaction chamber and the light source chamber, and the surface of the substrate accommodated in the reaction chamber. A first gas flow is introduced in a sheet shape from the gas introduction port substantially parallel to the substrate, and a second gas flow is introduced onto the surface of the substrate from a direction perpendicular to the surface from the first gas ejection plate. In the photo-CVD apparatus in which the first gas flow is maintained in a laminar state near the surface of the substrate, the light source chamber has a high reflectance for ultraviolet light or vacuum ultraviolet light, Moreover, it is partitioned by a second gas ejection plate having a large number of small holes, and is separated from the second gas ejection plate by the upper part. Note that the light source is arranged between the first gas jet plate and the second gas flow is introduced from the second gas jet plate to cool the light source by the second gas flow. Optical CVD equipment.