JPH1012602A - Vapor growth device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deposition of a large amount of silicon oxide on an outer tube made of quartz provided above an exhaust port and the breakage of the outer tube due to a strain when the outer tube is heated and cooled by providing a flow rate regulating plate which distributes the gas flow to an inner tube and the outer tube. SOLUTION: A vapor growth device is provided with an inner tube 15 which houses a boat 12 holding wafers 11 and has an opened top and an outer tube 16 which houses the inner tube 15 and has a ceiling. The device is also provided with a gas inlet port 14b for supplying gas to the inner tube 15 and an exhaust port 14d for discharging the gas through the space between the tubes 15 and 16. In such a vapor growth device, a flow rate regulating plate 17 which distributes the gas flow to the tubes 15 and 16 is provided. For example, the plate 17 is put between a pedestal 14 above the exhaust port 14d and inner tube 15 and small through holes are formed through an exhaust port section to reduce the gas flow, with the diameters of the through holes being larger from the port 14d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth apparatus for preventing a vapor growth material from being intensively deposited in a specific region of a vapor phase growth apparatus.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a method of forming an oxide film, a nitride film and the like by a gas phase reaction and depositing the oxide film and the nitride film on a semiconductor substrate has been used.

As an example of a conventional vapor phase growth apparatus, LP-
A CVD apparatus (low-pressure chemical vapor deposition apparatus) will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a semiconductor wafer, 2 denotes a quartz boat on which a plurality of semiconductor wafers 1 are horizontally placed one by one with the main surface facing upward, and 3 denotes a boat which holds the semiconductor wafer 1 horizontally. The holding table 4 which moves up and down while holding the cylindrical base 4 has a small diameter lower part 4a having a reaction gas inlet 4b at a large diameter upper part 4c and a reaction gas exhaust port 4d at a large diameter upper part 4c, and a lower end face 4e. When the table 3 rises, it comes into airtight contact with the holding table 3. Reference numeral 5 denotes a quartz inner cylindrical tube which surrounds the boat 2 and is mounted substantially vertically above the boat 2 in a substantially horizontal manner, surrounding the boat 2 at an intermediate horizontal portion 4f connecting the lower portion 4a and the upper portion 4c of the base 4. 4 is an outer tube made of quartz which is concentrically mounted on the upper end surface 4g of the inner tube 5 in an airtight manner. Outer pipe inner wall 6 above exhaust port
In this case, silicon oxide is concentrated on a.

[0005] A method of operating the present apparatus will be described below.

The holding table 3 is lowered by a vertical mechanism (not shown), and the boat 2 on which the semiconductor wafer 1 is mounted is mounted at the center. Subsequently, the holding table 3 is raised so that the boat 2 does not touch the inner tube 5, and is brought into close contact with the lower end surface 4 e of the pedestal 4. Subsequently, an exhaust pump (not shown) is provided from the exhaust port 4d.
After evacuating, the semiconductor wafer 1 is continuously exhausted.
A neutral gas (argon gas) that does not react with the gas flows through the inlet 4b, and a heater (not shown) wound around the outer tube 6 is energized to heat the semiconductor wafer 1 to a predetermined reaction temperature.
Hold at a predetermined temperature. Subsequently, the supply of the neutral gas is stopped, and several types of reaction gases are supplied at a predetermined ratio from the inflow port 4b to deposit silicon oxide, which is a reaction product, on the semiconductor wafer 1 by about 1 μm. Subsequently, the supply of the reaction gas is stopped, and the power of the vacuum pump and the heater is turned off to return to the normal pressure and the cooling is performed. Then, the holding table 3
Is lowered to take out the semiconductor wafer 1.

At the time of deposition of silicon oxide on the semiconductor wafer 1, silicon oxide also precipitates at a high temperature portion which is higher than the reaction temperature of the vapor phase growth apparatus in contact with the reaction gas.

One example of the reaction formula at this time is SiH ₄ + 4N ₂ O = SiO ₂ + 2H ₂ O + 4N ₂ . Here, the left side of the equation is the unreacted gas, and the right side is the gas after the reaction. However, unless otherwise specified, all the above gases were used as reaction gases in the description.

[0009]

In this vapor phase growth apparatus, since the gas is forcibly exhausted from the exhaust port by the pump, the flow rate of the gas flowing between the inner pipe and the outer pipe near the exhaust port increases. . For this reason, unreacted gas in the exhausted gas reacts on the inner wall of the outer tube above the exhaust port, and a large amount of silicon oxide precipitates, causing distortion, and is made of quartz due to thermal stress during heating and cooling. This caused the outer tube to crack.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems, and has an inner tube for accommodating a boat holding a wafer and having an opening at an upper portion, and a covered ceiling for accommodating the inner tube. A gas inlet for supplying gas into the inner tube, and an exhaust port for exhausting gas in the inner tube from above the inner tube through between the inner tube and the outer tube. , A vapor phase growth apparatus provided with a flow rate adjusting plate for dispersing a gas flow between an inner pipe and an outer pipe.

[0011] Further, a holding table on which the boat holding the wafer is mounted and which moves up and down, a pedestal whose lower end is in airtight contact with the holding table when the holding table is raised, and a boat is mounted on the pedestal substantially airtightly and surrounds the boat. A tubular inner pipe higher than the boat, an outer pipe with a ceiling placed airtightly on the pedestal and surrounding the inner pipe, a gas exhaust port connected between the inner pipe and the outer pipe from the outer wall of the pedestal, A gas inlet connected from the outer wall of the inner tube to the inside of the inner tube, the gas in the space between the wall of the inner tube or the base on the extension thereof and the wall of the outer tube or the base on the extension thereof. A vapor phase growth apparatus provided with a flow rate adjusting plate for dispersing a flow.

[0012] The flow rate control plate has a larger through hole as it goes away from the exhaust port, and is arranged in a space between the wall of the pedestal on the inner tube or its extension and the wall of the pedestal on the outer tube or its extension. An installed vapor phase growth apparatus is provided.

The flow rate adjusting plate is disposed in a space between a wall of the pedestal on the inner tube or its extension and a wall of the pedestal on the outer tube or its extension. As the distance from the exhaust port increases, the inner tube or its extension extends. Provided is a vapor phase growth apparatus in which a gap between the upper pedestal wall and / or the outer tube or the pedestal wall on the extension thereof is increased.

The flow rate adjusting plate is disposed in a space between the inner pipe or the pedestal wall on the extension thereof and the outer pipe or the pedestal wall on the extension thereof, and controls the flow of gas to the exhaust port. In the vicinity of the upper part, a cut-off vapor phase growth apparatus is provided.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG.

In the figure, 11 is a semiconductor wafer, 12
Is a quartz boat on which a plurality of semiconductor wafers 11 are placed one by one horizontally with the main surface facing upward, 13 is a holding table which moves the boat 12 up and down while keeping the semiconductor wafers 11 horizontal, and 14 is a pedestal. The lower portion 14a of the small diameter has an inlet 14b for the reaction gas and the upper portion 14c of the upper portion 14c has an outlet 14d for the reaction gas. The lower end surface 14e is in airtight contact with the holding table 13 when the holding table 13 is raised. 15 is a cylindrical inner tube made of quartz which is placed substantially vertically above the boat 12 and substantially airtightly surrounding the boat 12 at a horizontal portion 14f connecting the lower portion 14a and the upper portion 14c of the pedestal 14, and 16 is an upper end surface of the pedestal 14. 14g
Is an outer tube with a ceiling made of quartz placed concentrically with the inner tube 15 in an airtight state. Reference numeral 17 denotes a flow rate adjusting plate which is a feature of the present invention, and is mounted between the inner pipe 15 and the extension wall 14h of the outer pipe near the upper end face 14g of the exhaust port 14d of the pedestal 14. 14i is an extension wall of the inner tube.

FIG. 2 is a plan view showing an example of the flow control plate 17.
Shown in

In FIG. 1, reference numeral 17a denotes an exhaust port of the flow rate adjusting plate, in which through holes 17b of various diameters which become larger as the distance from the exhaust port 17a of the flow rate adjusting plate increases.
The through hole 17b is not limited to a circular shape. Except for the through hole 17b, the reaction gas is placed so as not to flow from the upper part to the lower part of the flow control plate 17.

The operation of the apparatus shown in FIG. 1 provided with the flow rate adjusting plate shown in FIG. 2 will be described below.

The vertical mechanism (not shown) on which the holding table 13 is mounted is lowered, and the boat 12 on which the semiconductor wafer 11 is mounted is mounted at the center. Subsequently, the holding table 13 is raised so that the boat 12 does not touch the inner pipe 15, and the pedestal 14
In close contact with the lower end surface 14e. Then, the exhaust port 14d
After the exhaust gas is exhausted by an exhaust pump (not shown), a neutral gas that does not react with the semiconductor wafer 11 flows through the inlet 14 b while continuing the exhaust, and is fed to a heater (not shown) wound around the outer tube 16. Electricity is applied to heat the semiconductor wafer 11 to a predetermined reaction temperature, and is maintained at the predetermined temperature. Then,
The supply of the neutral gas is stopped, and several kinds of reaction gases are supplied from the inflow port 14b at a predetermined ratio.
A silicon oxide, which is a reaction product, is deposited on the substrate 1 at about 1 μm. Subsequently, the supply of the reaction gas is stopped, and the power of the vacuum pump and the heater is turned off to return to the normal pressure and the cooling is performed. Subsequently, the holding table 13 is lowered to take out the semiconductor wafer 11.

At the time of depositing silicon oxide on the semiconductor wafer 11, silicon oxide is also deposited at a high temperature portion which is higher than the reaction temperature of the vapor phase growth apparatus in contact with the reaction gas.

At this time, the flow rate adjusting plate 17 is placed between the pedestal 14 above the exhaust port 14d and the inner pipe 15, and the exhaust port 17a of the flow rate adjusting plate 17 has a small air flow to reduce the gas flow. A hole 17b is drilled, and a large through hole 17b is drilled away from the hole. For this reason, the reaction gas is dispersed in the circumferential direction between the inner pipe 15 and the outer pipe 16 and flows to the pedestal 14, and then is exhausted from the exhaust port 14d, so that silicon oxide is concentrated on the outer pipe 16 above the exhaust port 14b. To prevent precipitation. As a result, the outer tube 16 does not break due to thermal stress caused by heating and cooling.

The flow control plate 17 may be provided in the space between the inner pipe 15 or the pedestal wall 14i on the extension of the inner pipe and the outer pipe 16 or the pedestal wall 17h on the extension of the outer pipe. ,
There is no need to place it horizontally. Further, the height of the pedestal 14 may be higher under the inner tube 15 than under the outer tube 16. However,
When inclined, the flow control plate 17 needs to be formed in a truncated cone shape.

The flow rate adjusting plate 17 is disposed at the same place as described above, and the inner pipe 1 is moved away from the exhaust port 14d.
The gap between the pedestal wall 14i on the extension of the inner pipe 5 or the inner pipe and the outer pipe 16 or the pedestal wall 14h on the extension of the outer pipe may be increased, or a gap may be provided on both sides.

FIG. 3 shows another example of the flow control plate, and a case where the flow control plate 17 is used instead of the flow control plate 17 in FIG. 1 will be described with reference to FIG.

In the drawing, reference numeral 18 denotes a flow rate adjusting plate which has an exhaust port 18a disposed on the exhaust port 14d.

This flow control plate 18 is connected to the flow control plate 1 of FIG.
1 and 3 will be described with reference to FIGS.

The flow control plate 18 allows the exhaust port 14 d
No reaction gas flows into the pedestal 14 from between the nearby inner tube 15 and outer tube 16. The flow of the gas is dispersed in a region away from the exhaust port 14d and without the flow control plate 18. For this reason, the silicon oxide is prevented from being intensively deposited on the outer tube 16 above the exhaust port 14b, and the outer tube 16 is not cracked by thermal stress due to heating and cooling.

The flow control plate 18 may be provided in the space between the inner pipe 15 or the pedestal wall 14h on the extension of the inner pipe and the outer pipe 16 or the pedestal wall 14h on the extension of the outer pipe. ,
There is no need to place it horizontally. Further, the height of the pedestal 14 may be higher under the inner tube 15 than under the outer tube 16. However,
When inclined, the flow control plate 17 needs to be formed in a truncated cone shape.

The inner pipe 1 is controlled by the flow rate adjusting plates 17 and 18.
The reaction gas between the outer tube 5 and the outer tube 16 is dispersed into the pedestal 14 and flows into the pedestal 14 from a region widened as the distance from the outlet 14d increases, and the inner tube 15 and the outer tube 1 close to the outlet 14d.
6 is dispersed and made to flow in such a manner as not to flow to the pedestal 14 so as to prevent abnormal deposition. Therefore, the outer tube 1 made of quartz due to thermal distortion caused by heating and cooling
No cracking of No. 6 occurs.

[0031]

According to the present invention, a flow regulating plate for dispersing a gas flow is disposed near an exhaust port where a reaction gas is concentrated so that the gas flow is not concentrated. Accordingly, since the gas flow is dispersed, a large amount of silicon oxide can be prevented from being deposited on the outer tube on the exhaust port, and damage to the quartz outer tube during heating and cooling due to generation of distortion can be prevented.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a vapor phase growth apparatus of the present invention.

FIG. 2 is a plan view of an example of a flow rate adjusting plate attached to the vapor phase growth apparatus of the present invention.

FIG. 3 is a plan view of an example of a flow rate adjustment plate different from FIG. 2 attached to the vapor phase growth apparatus of the present invention.

FIG. 4 is a side sectional view of a conventional vapor phase growth apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Wafer (semiconductor wafer) 12 Boat 13 Holder 14 Pedestal 14b Inlet 14c Upper part 14d Exhaust port 14h Wall on extension of outer pipe 14h Wall on extension of inner pipe 15 Inner pipe 16 Outer pipe 17, 18 Flow rate adjustment Board

Claims (5)

[Claims] 1. An inner tube accommodating a boat holding a wafer and having an opening at an upper part, an outer tube having a ceiling accommodating the inner tube, a gas inlet for supplying gas into the inner tube, and an inner tube. In a vapor phase growth apparatus having an exhaust port for exhausting gas in a tube from above the inner tube through the space between the inner tube and the outer tube, a gas flow between the inner tube and the outer tube is dispersed. A vapor phase growth apparatus, wherein a flow rate adjusting plate to be operated is provided. 2. A holding table on which a boat holding wafers is placed and which moves up and down, a pedestal having a lower end in airtight contact with the holding table when the holding table is raised, and a boat mounted on the pedestal substantially airtightly. And a tubular inner pipe higher than the boat, an outer pipe with a ceiling mounted airtightly on the pedestal and surrounding the inner pipe, and a space between the inner pipe and the outer pipe from the outer wall of the pedestal. A gas exhaust port connected to the inner tube, and a gas inlet connected from the outer wall of the pedestal to the inside of the inner tube. The pedestal wall and the outer tube or an extension thereof on the inner tube or its extension A vapor phase growth apparatus, further comprising a flow rate adjusting plate for dispersing a gas flow in a space between the pedestal and the upper wall. 3. The flow rate control plate has a through hole that gradually increases as the distance from the exhaust port increases, and the wall of the pedestal on the inner tube or its extension and the pedestal wall on the outer tube or its extension. The vapor phase growth apparatus according to claim 2, wherein the apparatus is disposed in a space between the two. 4. The flow control plate is disposed in a space between a wall of the pedestal on the inner tube or its extension and a wall of the pedestal on the outer tube or its extension, and moves away from the exhaust port. 4. The air gap according to claim 2, wherein a gap between the inner pipe or the pedestal wall on the extension thereof and / or the outer pipe or the pedestal wall on the extension thereof is increased. Phase growth equipment. 5. The flow control plate is provided in a space between the wall of the pedestal on the inner pipe or its extension and the wall of the pedestal on the outer pipe or its extension, and the flow control plate is connected to the exhaust port. 3. The vapor phase growth apparatus according to claim 2, wherein the flow of the gas is shut off near the upper part of the exhaust port.