JPH06333855A - Atmosphere inclusion preventive mechanism for vapor growth device - Google Patents

Abstract

PURPOSE:To provide an atmosphere inclusion preventive mechanism for a verti cal vapor growth device so as to shield the atmosphere in a bell jar from the external atmosphere when the bell jar is released for wafer loading and unloading. CONSTITUTION:A bell jar 1 is permitted to have a double structure composed of an outer bell jar 1a formed of a stainless steel plate and an inner bell jar 1b formed of quartz glass. A pipe 3 is connected at the summit of the outer jell jar 1a, and sufficiently dried clean air is introduced into a space between the outer bell jar 1a and the inner bell jar 1b through the pipe 3. When the bell jar 1 is lifted for loading and unloading wafers 4, the dry air is permitted to blow out downward from the bottom edge of the bell jar 1. Thus, temperature increase on the inner plane of the inner bell jar 1b is prevented and the flow of the atmosphere into the bell jar 1 is prevented by surrounding the space at the bottom of the bell jar 1 by the air curtain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for preventing atmospheric contamination of a vapor phase growth apparatus.

[0002]

2. Description of the Related Art Epitaxial wafers are manufactured in which silicon is grown on a silicon wafer substrate by epitaxial growth. As one of such an epitaxial wafer manufacturing apparatus, a vertical gas phase growth in which a reaction gas supply nozzle is installed at the center of a bell jar and a susceptor for holding a silicon wafer and an RF coil are concentrically arranged around the nozzle. The device is being used.

[0003]

By the way, in a normal vertical type vapor phase growth apparatus, the bell jar must be opened at the time of loading and unloading of the wafer. At this time, the atmosphere is mixed into the atmosphere inside the bell jar, and water is mainly adsorbed on the inner surface of the bell jar. Then, during the epitaxial growth, the water content is desorbed as the temperature rises, so that the partial pressure of water vapor in the atmosphere inside the bell jar rises. It is known that when the partial pressure of water vapor in the atmosphere inside the bell jar is high, a defect called haze, which is a rough surface of the wafer during epitaxial growth, frequently occurs. The present invention has been made focusing on such conventional problems,
When the bell jar is opened at the time of wafer loading and unloading in a vertical vapor phase growth apparatus,
It is an object of the present invention to provide an atmosphere mixing prevention mechanism for a vapor phase growth apparatus that can shut off the atmosphere in the bell jar from the atmosphere.

[0004]

In order to achieve the above-mentioned object, the atmospheric mixture preventing mechanism of the vapor phase growth apparatus according to the present invention comprises:
In a vertical vapor phase growth apparatus, the bell jar has a double structure consisting of an outer bell jar and an inner bell jar, and when the bell jar is raised, the dry air introduced into the gap between the outer bell jar and the inner bell jar is jetted from the lower end of the bell jar. Thus, an air curtain is formed, and the inside of the bell jar is shielded from the atmosphere. In such a structure, the dry air ejected from the lower end of the bell jar is sufficiently dry and clean. Further, in the vertical vapor phase growth apparatus, an atmosphere blocking cover surrounding the lower portion of the bell jar is provided, and when the bell jar is raised, a purge gas or a dry gas is introduced into the space formed by the bell jar and the atmosphere blocking cover connected to the lower end of the bell jar. The air may be filled with a positive pressure to block the invasion of the atmosphere into the space through a wafer loading window provided in the atmosphere blocking cover. Furthermore, a bellows which is fixed between the flange fixed to the upper part of the outer periphery of the bell jar and the upper end of the atmosphere blocking cover that surrounds the lower part of the bell jar is sealed by an expandable bellows, and a space surrounded by the outer periphery of the bell jar and the bellows, At least one ventilation hole communicating with the lower inner circumference of the shutoff cover is provided, and by the space formed by the belljar and the atmosphere shutoff cover connected to the lower end of the belljar when the belljar is raised, and the belljar outer circumference and the bellows. The enclosed space may be filled with a purge gas or dry air to a positive pressure to block the invasion of the atmosphere into the respective spaces through a wafer loading window provided in the atmosphere blocking cover.

[0005]

According to the above construction, in the vertical type vapor phase growth apparatus, the bell jar having the double structure consisting of the outer bell jar and the inner bell jar is used, and when the bell jar is raised, it is clean from the lower end of the bell jar and sufficiently dried. Since the air curtain is formed by ejecting air, it is possible to prevent the atmospheric air from being mixed into the bell jar at the time of loading and unloading the wafer, and to prevent moisture and the like from adsorbing to the inner wall of the bell jar. Further, by mounting an atmosphere blocking cover under the bell jar, when the bell jar is raised, the space below the bell jar is surrounded by the atmosphere blocking cover, and if this space is filled with the purge gas or the dry air to a positive pressure, When the wafer loading window provided in the atmosphere blocking cover is opened at the time of loading or unloading the wafer, it is possible to block the invasion of the atmosphere into the space.

When the bellows is sealed between the upper part of the outer periphery of the bell jar and the upper end of the atmosphere blocking cover surrounding the lower part of the bell jar with the expandable bellows, the space below the bell jar extends with the atmosphere blocking cover when the bell jar is raised. It is surrounded by the bellows and can completely prevent atmospheric air from entering these spaces from these parts. Then, by filling the space with a purge gas or the dry air to a positive pressure, when the wafer loading window provided in the atmosphere blocking cover is opened at the time of loading and unloading the wafer, the air is prevented from entering the space. It becomes possible to cut off.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an air pollution preventing mechanism of a vapor phase growth apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of an air intrusion prevention mechanism according to claim 1, and a bell jar 1 of this vapor phase growth apparatus has a double structure of an outer bell jar 1a made of a stainless steel plate and an inner bell jar 1b made of quartz glass. The outer bell jar 1a is connected to a bell jar lifting mechanism 2, and the bell jar 1 is moved up and down by driving a motor 2a. A pipe 3 is connected to the top of the outer bell jar 1a, and the air introduced into the gap between the outer bell jar 1a and the inner bell jar 1b from the pipe 3 raises the bell jar 1 for loading and unloading the wafer 4. At this time, the bell jets downward from the lower end of the bell jar 1. Since the air is sufficiently dry and clean air and is heated to a predetermined temperature range, the air curtain using such air causes the inflow of the atmosphere into the bell jar 1 and the decrease in the temperature of the inner surface of the inner bell jar 1b. Can be prevented. Reference numeral 5 is a susceptor for holding the wafer 4.

FIG. 2 is a perspective view of the atmosphere mixture preventing mechanism according to claim 3, showing a state in which the bell jar is raised. FIG. 3 is a sectional view of a portion P of FIG. The bell jar 1 can be moved up and down by attaching a hanging device (not shown) to the hanging device mounting portion 1c attached to the top. A cylindrical atmosphere blocking cover 6 is attached to the outside of the bell jar 1 so as to surround the bell jar 1, and the bell jar 1 is vertically movable along the inner circumference of the atmosphere blocking cover 6. The atmosphere blocking cover 6 is detachable from the bell jar 1 and is provided with a wafer loading window 6a for loading and unloading wafers. When loading and unloading the wafer, the bell jar 1 is raised. At this time, the flow rate of the purge gas such as nitrogen gas introduced into the bell jar 1 from the pipe 3 attached to the top of the bell jar 1 is increased. The outer periphery of the lower end of the bell jar 1 rises while sliding on the inner periphery of the atmosphere blocking cover 6 and reaches the upper end of the atmosphere blocking cover 6 as shown in FIG.
As shown in, the upper surface of the flange portion provided at the lower end of the bell jar 1 and the lower surface of the flange portion provided at the upper end of the atmosphere blocking cover 6 come into contact with each other to substantially seal the atmosphere. Even if the wafer loading window 6a is opened for loading and unloading the wafer, the purge gas filled in the space surrounded by the bell jar 1 and the atmospheric shutoff cover 6 at a positive pressure causes the bell jar 1 to pass through the loading window 6a. Atmosphere does not flow inside. When the bell jar 1 is lowered after the loading and unloading of the wafer are completed, the purge gas filled in the bell jar 1 is discharged to the outside from the exhaust hole of the vapor phase growth apparatus. When the wafer is loaded or unloaded, clean dry air may be filled instead of the purge gas. Further, when the atmosphere blocking cover 6 is not used, the atmosphere blocking cover 6 can be removed from the bell jar 1.

FIG. 4 is a side view of the atmosphere mixture preventing mechanism according to claim 4, showing a state in which the bell jar is raised. An annular flange 7 is fixed to the upper part of the outer periphery of the bell jar 1, and an atmosphere blocking cover 8 is provided outside the lower part of the bell jar 1 so as to surround the bell jar 1. A space between the flange 7 and the upper end of the atmosphere blocking cover 8 is sealed by an expandable bellows-like bellows 9, and the outer periphery of the bell jar 1 and the flange 7 are
A space surrounding the bell jar 1 is formed by the atmosphere blocking cover 8 and the bellows 9. Further, the atmosphere blocking cover 8 is provided with a vent hole 8a extending from the lower inner periphery to the upper end surface. At the time of wafer loading and unloading, the flow rate of the purge gas or dry air introduced into the bell jar 1 from the pipe 3 attached to the top of the bell jar 1 is increased, and the lower end outer circumference of the bell jar 1 is set along the inner circumference of the atmosphere blocking cover 8. When the lower end of the bell jar 1 reaches the vicinity of the upper end of the atmosphere blocking cover 8, the bell jar 1 is stopped. During this time, the bellows 9 expands, but since the purge gas or the dry air is supplied into the bellows 9 through the ventilation holes 8a extending from the lower inner circumference of the atmosphere blocking cover 8 to the upper end surface, the bellows 9 expands smoothly. Even if the wafer loading window 8b is opened by the purge gas or the dry air filled in the space surrounded by the bell jar 1 and the atmosphere blocking cover 8 at a positive pressure, the atmosphere can flow into the bell jar 1 through the loading window 8b. There is no. When the bell jar 1 is lowered, the purge gas or dry air supplied into the bellows 9 flows into the bell jar 1 through the ventilation holes 8a, and together with the purge gas or dry air filled in the bell jar 1, the vapor phase growth apparatus It is discharged to the outside through the exhaust hole.

[0010]

As described above, according to the present invention, in the vertical vapor phase growth apparatus, wafer loading,
As a means to prevent the invasion of the atmosphere into the bell jar during unloading, clean dry air was ejected from the lower end of the bell jar to form an air curtain, or the space formed below the bell jar was surrounded by an atmosphere blocking cover. In addition, since the space is filled with the purge gas or the clean dry air at a positive pressure, it is possible to prevent the atmosphere from being mixed into the atmosphere inside the bell jar. Therefore, it is possible to prevent the roughness of the wafer surface due to the adsorption of moisture or the like on the inner wall of the bell jar, which has been a problem in the past, and obtain a silicon wafer substrate of good quality. Also, if a bellows that can be expanded and contracted is installed between the outer periphery of the bell jar and the upper end of the atmosphere blocking cover, the gap between the bell jar and the atmosphere blocking cover is completely sealed, further preventing the atmosphere from entering the atmosphere inside the bell jar. Be certain.

[Brief description of drawings]

FIG. 1 is a perspective view of an atmosphere mixing prevention mechanism in a vapor phase growth apparatus according to claim 1.

FIG. 2 is a perspective view of an atmosphere mixing prevention mechanism in the vapor phase growth apparatus according to claim 3;

FIG. 3 is a sectional view of a P part in FIG.

FIG. 4 is a side view of an atmosphere mixing prevention mechanism in the vapor phase growth apparatus according to claim 4;

[Explanation of symbols]

 1 bell jar 1a outer bell jar 1b inner bell jar 6,8 atmosphere blocking cover 6a, 8b wafer loading window 7 flange 8a vent hole 9 bellows

Claims (4)

[Claims] 1. In a vertical vapor phase growth apparatus, the bell jar has a double structure consisting of an outer bell jar and an inner bell jar, and dry air introduced into a gap between the outer bell jar and the inner bell jar when the bell jar is raised. An air contamination preventing mechanism for a vapor phase growth apparatus, characterized in that an air curtain is formed by jetting the air from the lower end of the bell jar to shut off the inside of the bell jar from the atmosphere. 2. The dry air ejected from the lower end of the bell jar is
2. The atmospheric contamination preventing mechanism for a vapor phase growth apparatus according to claim 1, wherein the mechanism is sufficiently dry and clean. 3. A vertical type vapor phase growth apparatus, wherein an atmosphere blocking cover surrounding a lower portion of a bell jar is provided, and a space formed by the bell jar and an atmosphere blocking cover connected to a lower end of the bell jar is provided when the bell jar is raised. An atmosphere mixing prevention mechanism for a vapor phase growth apparatus, characterized in that the purge gas or the dry air according to claim 1 is filled to a positive pressure to block the invasion of the atmosphere into the space from a wafer loading window provided in the atmosphere blocking cover. 4. A space surrounded by a bellows outer periphery and a bellows while sealing between a flange fixed to an upper outer periphery of the bell jar and an upper end of an atmosphere blocking cover surrounding the lower portion of the bell jar, and a bellows outer periphery. And a space formed by the bell jar and the atmosphere shut cover connected to the lower end of the bell jar when the bell jar is raised, and at least one vent hole communicating with the lower inner circumference of the air shut cover is provided. A gas phase characterized in that the space surrounded by the bellows is filled with a purge gas or the dry air according to claim 1 to a positive pressure to block the invasion of the atmosphere into the respective spaces from a wafer loading window provided in the atmosphere blocking cover. Air growth prevention mechanism for growth equipment.