JP2012235074A - Barrel-type vapor-phase growth apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barrel-type vapor-phase growth apparatus which can reduce the amount of a reaction product peeled from the inside of a bellows pipe, and can suppress the amount of particles loaded from an exhaust passage to a reaction chamber.SOLUTION: A sleeve having a smaller diameter than a bellows pipe is inserted into the bellows pipe in a cantilevered state only with an upstream-side pipe section. Therefore, most of a reaction product is attached to an inner peripheral surface of the sleeve of a gas exhaust pipe in the region of the bellows pipe. Even if the bellows pope is deformed due to a vibration of the apparatus or the like, the amount of particles peeled from the bellows pipe is small, thereby decreasing the amount of the particles loaded into the reaction chamber than that in a conventional apparatus. Consequently, the amount of the particles attached to a semiconductor wafer can be reduced.

Description

  The present invention relates to a barrel-type vapor phase growth apparatus, and more particularly to a barrel-type vapor phase growth apparatus for vapor-phase growing an epitaxial film on the surface of a semiconductor wafer.

A barrel type (cylinder type) vapor phase growth apparatus has been developed as an apparatus for producing a silicon epitaxial wafer by vapor phase growth of an epitaxial film made of silicon on the surface of a silicon wafer.
In this apparatus, a susceptor having a polygonal frustum is disposed in a reaction chamber of a batch type barrel furnace (Belger) so as to be rotatable about a vertical rotation axis. On each side of the susceptor, counterbores for wafer storage are provided vertically. In addition, a halogen lamp as a heating means is provided around the reaction chamber.
At the time of vapor phase growth, vapor phase growth gas (reaction gas, carrier gas) is supplied from an upper gas supply pipe to a reaction chamber heated by a halogen lamp. As a result, the vapor growth gas flows along the outer peripheral surface of the rotating susceptor, and an epitaxial film is vapor grown on the surface of each silicon wafer. Unused vapor phase growth gas is discharged to the outside through a gas exhaust pipe at the bottom of the reaction chamber.

By the way, in the barrel furnace, reaction products (silicon) are also generated on the inner peripheral surfaces of the bell jar and the gas exhaust pipe. The reaction product is in the form of a film, and peeling occurs due to apparatus vibration, pressure fluctuation, temperature change, and the like. This exfoliated matter became particles and adhered to the silicon wafer, and was detected as a bright spot on the wafer surface during particle inspection after vapor phase growth.
In particular, when the vapor phase growth condition is under reduced pressure (80 Torr or more and less than 760 Torr), pressure fluctuations occur, so that particles tend to flow from the exhaust path of the barrel type vapor phase growth apparatus.

  Thus, for example, Patent Document 1 is known as a conventional technique for solving this problem. In this method, a funnel-shaped baffle is provided at the connection portion between the gas exhaust pipe and the reaction chamber, and the opening on the gas exhaust pipe side is made smaller than the opening on the reaction chamber side of the baffle. Thereby, the backflow of the particles from the gas exhaust pipe to the reaction chamber can be suppressed.

Japanese Patent No. 2503128

  However, in patent document 1, the structure which covers only the outer peripheral part of the connection part of a gas exhaust pipe and a reaction chamber in this way with the funnel-shaped baffle was employ | adopted. For this reason, the gas flowing through the central portion of the gas pipe directly passes through the exhaust port of the baffle, and the backflow of particles to the reaction chamber cannot be sufficiently suppressed.

Thus, as a result of intensive studies, the inventor has confirmed that the generation of particles due to the separation of reactive organisms is particularly large in the bellows piping portion that connects the upstream piping portion and the downstream piping portion. This is presumably because the bellows pipe is flexibly deformed by vibration and the like, and the product attached to the inner peripheral surface is easily peeled off. Therefore, if a sleeve smaller in diameter than the bellows pipe is attached to the bellows pipe passage in a cantilever state so that the reaction product does not directly adhere to the inner peripheral surface of the bellows pipe, the reaction product is discharged during reaction gas exhaust. Most of the inner peripheral surface of the sleeve is generated. As a result, even if the bellows piping expands or contracts due to vibration of the device, the amount of particles that peel from the bellows piping is small, and as a result, the amount of particles introduced into the reaction chamber can be suppressed compared to the conventional device. The present invention has been completed.
This invention can reduce the amount of particles generated due to the reaction product peeled off from the inner peripheral surface of the bellows pipe, and as a result, the amount of particles introduced from the exhaust path into the reaction chamber can be suppressed. An object of the present invention is to provide a barrel type vapor phase growth apparatus that can be used.

  The invention according to claim 1 is a barrel-type reaction chamber containing a susceptor for a semiconductor wafer, discharges a vapor phase growth gas supplied to the reaction chamber, and an upstream piping portion, a downstream piping portion, In the barrel type vapor phase growth apparatus provided with a gas exhaust pipe having a bellows pipe for communicating them flexibly, a sleeve having an outer diameter smaller than the inner diameter of the bellows pipe is provided inside the bellows pipe, It is a barrel type vapor phase growth apparatus in which only the upstream opening portion of the sleeve is inserted in a cantilever state in which the upstream opening portion is fixed to the downstream opening portion.

  The invention according to claim 2 is the barrel type vapor phase growth apparatus according to claim 1, wherein the entire inner peripheral surface of the sleeve is flush with the inner peripheral surface of the upstream-side piping portion. .

  According to the first aspect of the present invention, a sleeve having an outer diameter smaller than the inner diameter of the bellows pipe is inserted into the bellows pipe (pipe) in a cantilever state in which one end is fixed only to the upstream pipe section. Therefore, during the passage of the vapor phase growth gas discharged from the reaction chamber, most of the reaction products adhere to the bellows piping region on the inner peripheral surface of the sleeve of the gas exhaust pipe. It will not be the inner peripheral surface of. Therefore, even if the bellows pipe is deformed due to apparatus vibration or the like, the amount of particles peeled off from the bellows pipe is small. Thereby, the amount of particles introduced into the reaction chamber is reduced as compared with the conventional apparatus, and the amount of particles adhering to the semiconductor wafer can be reduced.

  In particular, according to the invention described in claim 2, since the entire inner peripheral surface of the sleeve is flush with the inner peripheral surface of the upstream pipe portion, there is no difference in level over the entire inner peripheral surface of the sleeve. The reaction product can be produced with a thickness. As a result, it is possible to reduce the amount of reaction product particles that peel from the inner peripheral surface of the sleeve, for example, compared to the case where the diameter-expanded portion is provided on the upstream pipe portion side of the sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view which shows the whole structure of the barrel type vapor phase growth apparatus which concerns on Example 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged longitudinal sectional view of a main part of a barrel type vapor phase growth apparatus according to Embodiment 1 of the present invention. It is a principal part expanded longitudinal cross-sectional view of the barrel type vapor phase growth apparatus which concerns on the other form of Example 1 of this invention. It is a principal part expanded vertical sectional view which shows the normal use state of the bellows piping of the barrel type vapor phase growth apparatus which concerns on Example 1 of this invention. It is a principal part expanded vertical sectional view which shows the contraction state of the bellows piping of the barrel type vapor phase growth apparatus which concerns on Example 1 of this invention.

  According to the present invention, a barrel type reaction chamber containing a susceptor for a semiconductor wafer, a vapor phase growth gas supplied to the reaction chamber is discharged, and an upstream side piping unit and a downstream side piping unit are connected in a flexible manner. In a barrel type vapor phase growth apparatus having a gas exhaust pipe having a bellows pipe for carrying out, a sleeve having an outer diameter smaller than the inner diameter of the bellows pipe is provided inside the bellows pipe, and only an opening on the upstream side of the sleeve is provided. It is a barrel type vapor phase growth apparatus inserted in a cantilever state fixed to an opening on the downstream side of the upstream piping section.

  According to the present invention, since the sleeve having a smaller diameter than the bellows pipe is inserted into the bellows pipe in a cantilevered state at the downstream side opening of the upstream pipe section, the vapor growth gas discharged from the reaction chamber passes through the bellows pipe. When passing, the vapor phase growth gas hardly contacts the inner peripheral surface of the bellows pipe, but contacts the inner peripheral surface of the sleeve, and a reaction product is generated in the form of a film. As a result, even if the bellows pipe is deformed (stretched) due to apparatus vibration or the like, the sleeve that is a rigid body does not deform, so the amount of particles generated due to peeling of the reaction product in the region of the bellows pipe is Reduced compared to the conventional case. Thereby, the amount (intrusion) of particles introduced into the reaction chamber from the gas exhaust pipe is reduced as compared with the conventional apparatus, and the amount of particles adhering to the semiconductor wafer can be reduced.

As the semiconductor wafer, for example, a single crystal silicon wafer, a polycrystalline silicon wafer, or the like can be employed.
As the shape of the susceptor, for example, a quadrangular frustum, a pentagonal frustum, a hexagonal frustum, or the like can be employed. Counterbore for housing the semiconductor wafer is formed on each side surface of the susceptor.
As the barrel type reaction chamber, for example, a pelja made of quartz can be adopted.
The vapor phase growth gas is, for example, a mixed gas of a carrier gas such as hydrogen gas and a reaction gas for growing an epitaxial film (vapor phase growth film) such as silicon. As the reaction gas, for example, when the epitaxial film is silicon, SiH ₄ gas, SiH ₂ Cl ₂ gas, SiCl ₄ gas, SiHCl ₃ gas, or the like can be employed. Further, a predetermined dopant gas (PH ₃ gas, B ₂ H ₆ gas, etc.) may be mixed in the vapor phase growth gas.

Each of the upstream piping section and the downstream piping section can be divided into a plurality of partial piping sections (upstream partial piping and downstream partial piping). In that case, you may arrange | position this bellows piping between each partial piping part.
For example, a connection between flanges can be adopted as a connection (communication) form between the upstream pipe portion and the bellows pipe and a connection form between the bellows pipe and the downstream pipe.
Each pipe including the bellows pipe is preferably made of stainless steel having excellent rigidity and acid resistance, and the bellows pipe is thin so that it can be moved flexibly.

As the material of the sleeve, for example, stainless steel, inconel, hastelloy, or the like can be used.
The outer diameter of the sleeve is preferably smaller than the inner diameter when the bellows pipe is most shortened. Further, the length of the sleeve is preferably the same as or slightly longer than the length of the bellows pipe in the communication state between the upstream pipe section and the downstream pipe section, for example. This further reduces the flow rate of the vapor phase growth gas that goes from the opening (exhaust port) on the downstream side of the sleeve to the inner peripheral surface of the bellows pipe, and reduces the amount of reaction product adhering to the inner peripheral surface of the bellows pipe. This is because it can.

  In the present invention, it is desirable that the entire inner peripheral surface of the sleeve is flush with the inner peripheral surface of the upstream pipe portion. The term “same state” as used herein refers to a state in which the inner diameter of the sleeve is the same as the inner diameter of the upstream piping section (at least the inner diameter of the opening on the bellows piping side of the upstream piping section) over the entire length of the sleeve and there is no step. means. Thereby, the reaction product can be generated with a uniform thickness over the entire inner peripheral surface of the sleeve. As a result, it is possible to reduce the amount of reaction product particles that peel from the inner peripheral surface of the sleeve, for example, compared to the case where the diameter-expanded portion is provided on the upstream pipe portion side of the sleeve.

  Further, it is desirable that the smoothness of the inner peripheral surface of the sleeve is high. This is because if there is a protrusion or the like on the inner peripheral surface of the sleeve, the amount of reaction product generated at the protrusion increases, and the amount of reaction product particles at that portion increases accordingly. It is. In the case of a metal sleeve, it is preferable that the sleeve is manufactured by various seamless methods, such as manufacturing a sleeve by machining the cylindrical body in a semi-grid manner so that no protrusion is formed on the inner peripheral surface. Of course, it may be manufactured by a method in which a protruding portion is generated on the inner peripheral surface, such as a forging method, an electric sewing method, or an arc welding method.

Next, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 10 denotes a barrel type vapor phase growth apparatus according to Embodiment 1 of the present invention. A barrel type vapor phase growth apparatus 10 includes a reaction chamber 12 of a bell jar 11 for vapor phase growth of a silicon epitaxial film on the surface of a silicon wafer (semiconductor wafer) W, and a susceptor 13 that is disposed in the reaction chamber 12 and holds the silicon wafer W. A gas introduction pipe 14 provided at the upper end of the bell jar 11 for introducing a vapor growth gas into the reaction chamber 12, a number of halogen lamps 15 provided around the bell jar 11 for heating the reaction chamber 12, and a bell jar 11 and a gas exhaust pipe 16 for exhausting the vapor phase growth gas in the reaction chamber 12.

The bell jar 11 is a cylinder made of quartz and having a cylindrical body whose lower end is gradually tapered, and an opening at the upper end is closed by a lid 17.
The gas introduction pipe 14 is formed in a part of the outer peripheral portion of the lid body 17 and is attached to a gas introduction port 17 a that communicates the inner peripheral surface and the outer peripheral surface of the lower portion of the lid body 17.
In addition, a large number of the halogen lamps 15 are disposed on the entire outer periphery of the body of the bell jar 11.
The susceptor 13 is suspended in the internal space of the reaction chamber 12 so as to be rotatable about the rotation shaft 18.
The susceptor 13 is a hexagonal frustum-shaped cylindrical body, and counterbore 19 is formed on each of the six peripheral side surfaces in two upper and lower stages (total of 12 locations). Each counterbore 19 is a shallow shallow circular portion when viewed from the front where the silicon wafer W is placed.
The gas exhaust pipe 16 has an upstream piping portion 20 communicated with an exhaust port at a lower end portion of the bell jar 11 through a flange 20a, a downstream opening portion communicated with an intake portion of the vacuum generator, and a midway portion. The downstream side piping part 21 with which a water-cooled exhaust line, a heat exchanger, etc. were connected, the bellows pipe 22 which flexibly connects these upper and downstream side pipe parts 20 and 21, and the inside of the bellows pipe 22 are accommodated. And a sleeve 23 (FIGS. 2 and 4).

The bellows pipe 22 is a stretchable tube made of stainless steel, and has flanges 22a at openings at both ends thereof. Therefore, the upper and downstream pipe portions 20 and 21 and the bellows pipe 22 are connected to each other through the flanges.
The sleeve 23 is manufactured by machining a cylindrical body made of stainless steel (FIGS. 1 and 2), and the outer diameter of the sleeve 23 is shorter than the inner diameter of the bellows pipe 22 in a normal use state ( 2 and 4). In addition, an enlarged diameter portion 23 a having a stepped diameter is integrally formed of the same material as that of the sleeve 23 in the opening on the upstream side of the sleeve 23. The thickness of the enlarged diameter portion 23 a is the same as the thickness of the normal portion of the sleeve 23.

Corresponding to the enlarged diameter portion 23a, the enlarged diameter portion 23a is connected to the inner peripheral portion of the downstream flange 20a of the upstream pipe portion 20 and the inner peripheral portion of the upstream flange 22a of the bellows piping 22. By working and storing, a pair of annular grooves 20b and 22b are formed so that the inner peripheral surface of the upstream pipe portion 20 and the inner peripheral surface of the enlarged diameter portion 23a are flush with each other.
On the outer peripheral surface of the enlarged diameter portion 23a, a short-width flange 26 having a projecting width shorter than those of the flanges 20a and 22a is integrally formed of the same material as the sleeve 23. An annular seal groove 26 a for hooking the O-ring 25 is provided on the outer peripheral surface of the short-width flange 26. The thickness (diameter) of the O-ring 25 is longer (larger) than the thickness of the short-width flange 26 in order to seal the gap between the flanges 20a and 22a. Although not shown, the upstream pipe portion 20 and the bellows pipe 22 are firmly connected with a clamping force of a predetermined shape with an O-ring 25 interposed between the flanges 20a and 22a.

  On the inner peripheral surface of the upstream opening of the sleeve 23, there is a stepped portion a due to the formation of the enlarged diameter portion 23a. For this reason, a part of the vapor phase growth gas that has passed through the upstream pipe portion 20 collides with the stepped portion a, and the amount of reaction product generated in this portion is likely to increase as compared with a normal portion. Therefore, in order to solve this problem, an annular partial stepped portion 26b having the same height as the enlarged diameter portion 23a is integrally formed with the same material as the sleeve 23 only at the base portion of the downstream side surface of the short width flange 26. You may comprise so that the annular groove 22b of the flange 22a of the upstream of the bellows piping 22 may be engage | inserted in the part 26b (FIG. 3). As a result, the inner peripheral surface of the upstream pipe section 20 and the entire inner peripheral surface of the sleeve 23 are flush with each other, and a reaction product is generated with a uniform thickness over the entire inner peripheral surface of the sleeve 23. can do. As a result, it is possible to reduce the amount of particles of the reaction product that peels from the inner peripheral surface of the sleeve 23 as compared with the case where the enlarged diameter portion 23a is provided.

Next, an epitaxial silicon wafer manufacturing method using the barrel type vapor phase growth apparatus 10 according to the first embodiment of the present invention will be described with reference to FIGS.
First, the lid 17 is removed, and a total of 12 silicon wafers W are stood and stored in the counterbore 19 of the susceptor 13 from the opening on the upper side of the bell jar 11 so that the surface of each wafer faces outward. Next, the upper opening of the bell jar 11 is sealed with the lid 17, and the reaction chamber 12 is brought into a reduced pressure state of 80 Torr with a vacuum generator. In this state, air is replaced with nitrogen gas in the reaction chamber 12, and then hydrogen gas is introduced to replace nitrogen gas.

Next, each halogen lamp 15 is energized, the silicon wafer W is heated to 1080 ° C., and the susceptor 13 is rotated in a predetermined direction around the rotation shaft 18 at a predetermined speed, and then the reaction chamber 12 is connected to the reaction chamber 12. Is supplied with trichlorosilane (reactive gas), and a silicon epitaxial film having a thickness of 2 to 10 μm is vapor-phase grown on the surface of the silicon wafer W.
Thereafter, the unreacted vapor phase growth gas flows from the lower opening of the bell jar 11 into the upstream piping unit 20 and sequentially passes through the sleeve 23 and the downstream piping unit 21 housed in the bellows piping 22, Eventually, harmful substances in the gas are removed and the atmosphere is released.

By the way, during the vapor phase growth, in the gas exhaust pipe 16, trichlorosilane comes into contact with the inner peripheral surface, and a silicon reaction product is generated over the entire length of the gas exhaust pipe 16. In particular, in the region of the bellows pipe 22, since the sleeve 23 covers substantially the entire inner peripheral surface of the bellows pipe 22 from the inside of the pipe, a reaction product is generated in the form of a film on the inner peripheral surface of the sleeve 23.
At this time, in Example 1, since the vapor phase growth is performed in a reduced pressure state of 80 Torr, the pressure in the furnace easily fluctuates, and the bellows pipe 22 of the gas exhaust pipe 16 is flexibly deformed (expanded) in accordance with the fluctuation. (FIG. 5).

  However, the sleeve 23 in which the reaction product is generated on the inner peripheral surface is a rigid body made of stainless steel whose outer diameter is smaller than the inner diameter of the bellows pipe 22 as described above, and is formed in the opening on the downstream side of the upstream pipe section 20. Cantilevered. Therefore, even if the bellows pipe 22 is deformed, the reaction product on the inner peripheral surface of the sleeve 23 hardly peels off. As a result, the amount of particles generated due to peeling of the reaction product in the region of the bellows pipe 22 is reduced as compared with the conventional case. Therefore, the amount of particles introduced from the gas exhaust pipe 16 into the reaction chamber 12 (reverse flow rate) is reduced as compared with the conventional apparatus. As a result, the particle counter counts on the wafer surface counted during particle inspection after vapor phase growth. The number of particles can be reduced.

  In the present invention, because the sleeve having a small outer diameter due to the inner diameter of the bellows pipe is inserted into the bellows pipe in a cantilever state in which one end is fixed only to the upstream pipe part, even if the bellows pipe is deformed, The amount of particles peeled off from the bellows pipe is reduced, and the amount of particles adhering to the semiconductor wafer can be reduced.

10 barrel type vapor phase growth equipment,
12 reaction chamber,
13 Susceptor,
16 gas exhaust pipe,
20 Upstream piping section,
21 Downstream piping section,
22 bellows piping,
23 sleeve,
W Semiconductor wafer.

Claims (2)

A barrel type reaction chamber containing a semiconductor wafer susceptor;
A barrel type gas exhaust having a gas exhaust pipe for discharging the vapor phase growth gas supplied to the reaction chamber and having an upstream pipe section, a downstream pipe section, and a bellows pipe for flexibly communicating them. In the phase growth device,
A sleeve having an outer diameter smaller than the inner diameter of the bellows pipe is inserted into the bellows pipe in a cantilever state in which only the upstream opening of the sleeve is fixed to the downstream opening of the upstream pipe. Barrel type vapor phase growth equipment.   The barrel type vapor phase growth apparatus according to claim 1, wherein the entire inner peripheral surface of the sleeve is flush with the inner peripheral surface of the upstream pipe portion.

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