JP4736269B2 - Cylinder type vapor phase growth equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylinder-type vapor phase growth apparatus for forming a silicon epitaxial layer on a silicon single crystal wafer.
[0002]
[Prior art]
As shown in FIG. 3, the cylinder-type vapor phase growth apparatus is provided with a polygonal frustum-shaped susceptor rotatably provided inside a quartz bell jar (reactor) 120, and a heating lamp outside the bell jar 120. Is provided with a plurality of lamp modules (heating lamp modules) 130. Then, the silicon single crystal wafer is placed on a circular counterbore 110a formed on the side wall surface of the susceptor 110, and the silicon single crystal wafer is heated by a heating lamp arranged in the lamp module 130 while rotating the susceptor 110. Then, a silicon source gas is circulated in the bell jar 120 to form a silicon epitaxial layer on the main surface of the silicon single crystal wafer (Japanese Patent Laid-Open No. 2-241029).
[0003]
[Problems to be solved by the invention]
In this cylinder type vapor phase growth apparatus, while performing vapor phase growth on a silicon single crystal wafer, in order to prevent silicon from adhering to the inner wall surface of the bell jar 120, for example, as shown in FIG. The bell jar 120 is cooled by circulating air through the lamp module cover 140 or the like. However, even if such cooling is performed, it is difficult to completely prevent silicon from adhering to the inner wall surface of the bell jar 120. Moreover, once silicon adheres to the inner wall surface of the bell jar 120, polysilicon is rapidly deposited around the silicon. Start to deposit.
In the bell jar 120 on which polysilicon is deposited, a part of the inner wall surface of the bell jar 120 is covered with polysilicon, so that the light from the heating lamp is blocked and the silicon single crystal wafer heated in the susceptor 120 is uniformly heated. I can't do that. As a result, there may be problems such as the in-batch resistivity distribution of the silicon epitaxial wafer subjected to vapor phase growth becoming large or the growth rate of the silicon epitaxial layer rapidly decreasing.
On the other hand, on the inner wall surface of the bell jar 120, the portion where the polysilicon is deposited becomes devitrified after the acid cleaning. Even if polysilicon is dropped by performing acid cleaning, not only radiation heating by a heating lamp is not performed well in a devitrified portion, but silicon deposition tends to occur again on the devitrified quartz surface. Accordingly, the bell jar 120 with deposited polysilicon must be repaired.
[0004]
An object of the present invention is to provide a cylinder type vapor phase growth apparatus capable of reducing the deposition of polysilicon on the inner wall surface of a bell jar (reactor).
[0005]
[Means for Solving the Problems]
As a result of studies on the cylinder type vapor phase growth apparatus, the present inventors have found that the bell jar has a position where polysilicon is relatively easily deposited on the inner wall surface. This position was the lower part of the bell jar opposite to the position of the cold air inlet formed in the lamp module cover and closest to the susceptor.
Accordingly, the position where the polysilicon is easily deposited is predicted to be able to reduce the deposition of polysilicon if the cooling is insufficient and the position can be cooled more efficiently, and the present invention has been achieved.
[0006]
That is, the means according to the present invention for solving the problem includes, for example, as shown in FIGS. 1 and 2, a cylindrical reactor (bell jar 20) having a susceptor (10) for holding a silicon single crystal wafer, and the reaction described above. A gas supply part (for example, a gas supply pipe 15) for supplying a reaction gas to the inside of the furnace, a plurality of heating lamp modules (30) provided around the reaction furnace, and surrounding the outside of the plurality of heating lamp modules The lamp module cover (40) provided with a cold air inlet (41) for taking in cooling air, and the cold air provided outside the lamp module cover so as to communicate with the cold air inlet A cylinder comprising an introduction pipe (45) and a blower (50) connected to the cold air introduction pipe and supplying cooling air to the cold air introduction pipe In the type vapor phase growth apparatus (100), the lamp module cover (40) is provided with a side cold air vent (43 ), And an end (61) of a side pipe (60) branched from the cold air introduction pipe is connected to the side cold air inlet.
[0007]
In addition, inside the lamp module cover, the cooling air flows from the cold air inlet or the side cold air outlet and is exhausted from the exhaust port provided at the lower part of the lamp module cover. It circulates downward from. Therefore, the cold air inlet is formed in the upper part of the lamp module cover, the side cold air inlet to which the end of the side tube is connected is below the cold air inlet, and polysilicon is deposited. More preferably, it is formed above the position.
Polysilicon is likely to be deposited at two locations on the inner wall surface opposite to the direction of the cold air inlet from the center of the reactor. Therefore, it is more preferable that the side cold air ports are formed at two positions slightly above the positions of the lamp module cover corresponding to these positions.
[0008]
According to the present invention, the lamp module cover is formed with a side cold air inlet at a location substantially corresponding to the circumferential direction with respect to the position where polysilicon is deposited on the inner wall surface of the reactor, The end of the side pipe branched from the cold air introduction pipe is connected.
Therefore, the reaction furnace can be efficiently cooled by guiding the cooling air supplied from the blower to the vicinity of the position where polysilicon in the reaction furnace is deposited. As a result, the deposition of polysilicon on the inner wall surface of the reactor can be reduced. Accordingly, the lamp heating from the outside of the reactor is not hindered by the polysilicon, and the temperature distribution of the susceptor is improved, so that a silicon epitaxial layer is suitably formed on the silicon single crystal wafer placed on the susceptor. Can do.
Further, since the reaction furnace can be prevented from devitrifying due to the deposition of polysilicon, the replacement period of the reaction furnace is extended, and the productivity is improved. In addition, costs can be reduced because the need to repair the reactor is reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of a cylinder type vapor phase growth apparatus 100 of the present invention. 2A is a plan sectional view showing the main configuration of the vapor phase growth apparatus 100, and FIG. 2B is a side view.
The vapor phase growth apparatus 100 includes a susceptor 10, a bell jar (reactor) 20, a lamp module (heating lamp module) 30, a lamp module cover 40 that covers the outer periphery of the lamp module 30, and the lamp module cover 40. And a blower 50 for supplying cooling air.
[0010]
The bell jar 20 is formed in a cylindrical shape by transparent quartz, and a lower end portion thereof is fitted to form a neck 21. On the upper side of the bell jar 20, a gas supply port 22 for taking in a reaction gas in the vapor phase growth reaction is provided, and an exhaust pipe (not shown) is connected to a lower end portion of the lower neck 21. In the bell jar 20, the reaction gas flows from the upper side to the lower side.
[0011]
The susceptor 10 is made of carbon and has a polygonal frustum shape (indicated by a hexagonal frustum shape in the drawing), and a circular counterbore 10a for holding a silicon single crystal wafer is provided on the peripheral surface thereof. Yes. The susceptor 10 is hung in the bell jar 20 with a hanger 11 provided at the upper end. Further, the hanger 11 is connected to a rotation drive device (not shown), and the susceptor 10 is rotated in the circumferential direction according to the operation of the rotation drive device. Further, a temperature sensor (not shown) is provided in the susceptor 10 so that the temperature on the back side of the susceptor 10 can be monitored.
In FIG. 2, the susceptor 10 has a hexagonal cross section, but the shape of the susceptor 10 is pentagonal depending on the size of the counterbore formed according to the diameter of the silicon single crystal wafer to be subjected to vapor phase growth. Or a heptagon may be sufficient and can be changed suitably.
[0012]
The gas supply pipe (gas supply unit) 15 supplies a gas necessary for vapor phase growth, such as silicon source gas such as monosilane, dichlorosilane, and trichlorosilane, and dopant gas, into the bell jar 20 together with a carrier gas such as hydrogen. . These source gases and the like are supplied into the bell jar 20 through a gas supply port 22 provided on the upper side of the bell jar 20.
The source gas and the like supplied into the bell jar 20 flow downward along the main surface of the silicon single crystal wafer placed on the susceptor 10 and the counterbore 10a of the susceptor 10, and are provided below the bell jar 20. It is discharged from an exhaust pipe (not shown). With these gases, a silicon epitaxial layer is formed on the main surface of the silicon single crystal wafer heated on the susceptor 10.
[0013]
The lamp module 30 is configured by arranging a large number of heating lamps such as halogen lamps provided with reflecting plates in a lamp frame. As shown in FIGS. 1 and 2A, five heating lamp modules 30 are provided so as to surround the bell jar 20 coaxially. In the heating lamp module 30, a slit is formed between adjacent halogen lamps so that air can flow. A gap is also provided between two adjacent lamp modules 30. With these slits and gaps, the air easily flows through the front side and the back side of the heating lamp module 30 (the bell jar 20 side and the lamp module cover 40 side). The cooling air for cooling the vapor phase growth apparatus 100 is supplied from the outside of the lamp module 30 and mainly flows downwardly between the lamp module 30 and the reaction furnace 20 through the upper side of the lamp module 30. The reaction furnace 20 is cooled.
[0014]
The lamp module cover 40 is formed in a cylindrical shape and covers the outside of the five heating lamp modules 30, and a cold air inlet 41 for introducing cooling air is formed in the upper part of the lamp module cover 40. Further, an exhaust duct 42 for discharging air is formed at the lower part of the lamp module cover 40. Further, side cold air ports 43 and 43 are formed at two locations below the cold air inlet 41 of the lamp module cover 40. Inside the lamp module cover 40, air flowing in from the cold air introduction pipe 41 and the side cold air ports 43, 43 flows downward and is discharged from the exhaust duct 42.
[0015]
The positions in the circumferential direction for forming the side cold air vents 43, 43 are formed at locations substantially corresponding to positions where polysilicon is likely to be deposited on the inner wall surface of the bell jar 20. Experience has shown that the positions where polysilicon is likely to deposit are two positions (positions indicated by A in FIG. 2) near about 120 degrees with respect to the direction of the cold air inlet 41 from the center of the bell jar 20. Therefore, it is desirable to form the side cold air vents 43, 43 of the lamp module cover 40 at locations corresponding to the two locations in the circumferential direction.
In addition, as described above, the vertical positions of the side cold air ports 43 and 43 are positions where the cooling air flows from the upper side to the lower side, and the polysilicon of the bell jar 20 is easily deposited efficiently. 2 (b), it is preferable that it is below the cold air inlet 41 and above the position A where the polysilicon of the bell jar 20 is easy to deposit.
[0016]
A cold air introduction tube 45 is provided outside the cold air introduction port 41 of the lamp module cover 40 so as to communicate with the cold air introduction port 41. Two side pipes 60, 60 are provided on the side surface of the cold air introduction pipe 45 so that the inside communicates. Moreover, the end parts 61 and 61 of these side pipes 60 and 60 are connected to the side cold air vents 43 and 43 formed in the lamp module cover 40, as shown to Fig.2 (a) and (b). .
It should be noted that an adjustment valve or the like may be provided in the cold air introduction tube 45 to adjust the direction of the cooling air that flows into the lamp module cover 40.
[0017]
The heat exchanger 55 is a device that cools air by flowing cooling water therein and exchanging heat with warm air. The air discharged from the exhaust duct 42 of the lamp module cover 40 flows into the heat exchanger 55 and is cooled.
[0018]
The blower 50 is a device that includes a motor 51 and a fan 52 and blows cooling air taken from the heat exchanger 55. The air outlet 51 of the blower 50 is connected to the cold air introduction pipe 45, and the cooling air blown from the blower 50 is supplied to the inside of the lamp module cover 40 through the cold air introduction pipe 45 and the two side pipes 60 and 60. It has come to be.
[0019]
The flow of cooling air in the vapor phase growth apparatus 100 will be described.
The cooling air is supplied from the blower 50 and flows into the cold air introduction pipe 45. A part of the cooling air flows into the inside of the lamp module cover 40 from the cold air inlet 41 and a part of the cooling air passes from the side cold air outlet 43 via the side pipe 60 branched from the cold air inlet pipe 45. It flows into the lamp module cover 40.
[0020]
A part of the cooling air flowing in from the cold air inlet 41 flows above the lamp module 30 and flows downward between the lamp module 30 and the bell jar 20, and a part of the cooling air flows between the lamp module 30 and the lamp module cover 40. Between the lamp module 30 and the bell jar 20 through the slits formed between the halogen lamps in the lamp module 30 and flows downward.
[0021]
On the other hand, the cooling air flowing in from the side cold air ports 43, 43 flows downward between the lamp module 30 and the lamp module cover 40, and a part of the slits formed between the halogen lamps in the lamp module 30. It flows between the lamp module 30 and the bell jar 20 through and flows downward.
[0022]
Such a flow of cooling air cools the lamp module 30 and the periphery of the bell jar 20, and in particular, on the inner wall surface of the bell jar 20, above the position where polysilicon is likely to deposit and the position corresponding to the circumferential direction. The cooling air from the side cold air vents 43, 43 formed in the air flows through the slit of the lamp module 30 to a position where the polysilicon of the bell jar 20 is easily deposited. Therefore, the position where the polysilicon on the inner wall surface of the bell jar 20 easily deposits is efficiently cooled, and the deposition of polysilicon is suppressed.
[0023]
According to the vapor phase growth apparatus 100 of the present invention, the side cold air vents 43 are formed on the inner wall surface of the bell jar 20 at the location of the lamp module cover 40 that substantially corresponds to the circumferential direction with respect to the position where polysilicon is easily deposited. is doing. Since the end 61 of the side pipe 60 branched from the cold air introduction pipe 45 is connected to the side cold air port 43, the polysilicon of the bell jar 20 is likely to deposit the cooling air supplied from the blower 50. It can be guided near the position, and cooling can be performed efficiently.
Accordingly, it is possible to suppress the deposition of polysilicon on the inner wall surface of the bell jar 20, and as a result, the temperature of the susceptor 10 is prevented without being disturbed by the polysilicon from heating from the halogen lamp located outside the bell jar 20 during vapor phase growth. Since the distribution is improved, the silicon epitaxial layer can be suitably formed on the silicon single crystal wafer.
Further, since the bell jar 20 can be prevented from devitrifying due to the deposition of polysilicon, the replacement period of the bell jar 20 is extended and the productivity is improved. Furthermore, the need to repair the bell jar 20 is reduced, and the cost can be reduced.
[0024]
The present invention is not limited to the above embodiment. For example, you may make it cool, for example by attaching a water cooling apparatus etc. to the lamp module 30 grade | etc.,. Further, the cooling air may be appropriately taken from outside the apparatus in addition to the air circulating in the vapor phase growth apparatus.
In addition, in the present invention, the side cold air outlet 43 is positioned so as to cool the bell jar 20 portion at a position of about 120 degrees with respect to the cold air inlet 41 direction from the center of the bell jar 20 as a position where polysilicon is easily deposited. However, the design of the side cold air outlet 43 can be changed as appropriate in view of the position where polysilicon is easily deposited. Even in that case, the vertical position of the side cold air inlet 43 is preferably lower than the cold air inlet 41 and higher than the position where polysilicon is easily deposited.
[0025]
【Example】
Using the cylinder type vapor phase growth apparatus 100 of the present invention, vapor phase growth is performed on a silicon single crystal wafer. A silicon single crystal wafer is manufactured from a silicon single crystal ingot manufactured by the FZ method or the CZ method through a chamfering process, a slicing process, a lapping process, an etching process, a CVD oxide film growing process, and a mirror polishing process. A silicon single crystal wafer for vapor phase growth with a diameter of 125 mm (hereinafter referred to as a wafer) having a CVD oxide film formed on the back surface is used.
In the vapor phase growth, first, a wafer is set on the susceptor 10, and the wafer is heated to about 1110 ° C. to 1190 ° C. by a halogen lamp arranged in the lamp module 30. Then, by supplying a silicon source gas or the like from the gas supply pipe 15, a silicon epitaxial layer is formed on the wafer surface.
Vapor phase growth is performed at heating temperatures of (1) 1110 ° C., (2) 1160 ° C., and (3) 1190 ° C. The processing time and the like are appropriately set to conditions for forming the silicon epitaxial layer to a desired thickness. In this example, the silicon epitaxial layer was formed on the average of about 150 μm per day by the vapor phase growth apparatus 100.
[0026]
In the present embodiment, the thickness of the silicon epitaxial layer (hereinafter referred to as the film thickness) formed on the wafer by a single vapor phase growth process is measured, and polysilicon is deposited on the inner wall surface of the bell jar 20 to form the bell jar 20. The total film thickness formed on the wafer before the replacement is recorded.
In the vapor phase growth under each temperature condition, the total film thickness formed on the wafer before the bell jar replacement was (1) 165 μm, (2) 592 μm, and (3) 958 μm, respectively.
[0027]
<Comparative example>
In this comparative example, vapor deposition is performed on a wafer using a conventional cylinder type vapor phase growth apparatus 101. The wafer used, the reaction time, etc. are the same as in the previous examples, and growth temperatures are (1) 1110 ° C., (2) 1160 ° C., (3) 1190 ° C., and the silicon epitaxial layer averages about 150 μm per day. Formed.
[0028]
Under each temperature condition, the total film thickness formed on the wafer before the replacement of the bell jar 120 was (1) 56 μm, (2) 331 μm, and (3) 277 μm.
[0029]
In comparison with the example and the comparative example, in this example, the thickness of the silicon epitaxial layer that can be formed before the polysilicon is deposited on the inner wall surface of the bell jar is greatly increased as compared with the comparative example.
Therefore, in the vapor phase growth apparatus 100 of the present invention, it can be seen that the cumulative film thickness of the silicon epitaxial layer that can be formed before the bell jar replacement is larger than that of the conventional one, and therefore the replacement period of the bell jar becomes longer.
[0030]
【The invention's effect】
According to the present invention, the lamp module cover is formed with the side cold air port at a location substantially corresponding to the circumferential direction with respect to the position where polysilicon is deposited on the inner wall surface of the reactor, Since the end of the side pipe branched from the introduction pipe is connected so as to communicate, the cooling air supplied from the blower can be guided to the vicinity of the position where polysilicon is deposited in the reactor through the side pipe. Can be efficiently cooled.
Therefore, since it is possible to reduce the deposition of polysilicon on the inner wall surface of the reactor, the lamp heating from the outside of the reactor is not hindered by the polysilicon in the vapor phase growth, and the temperature distribution in the susceptor is improved. A silicon epitaxial layer can be suitably formed on a silicon single crystal wafer.
Further, devitrification of the reaction furnace due to the deposition of polysilicon can be prevented, so that the replacement period of the reaction furnace is extended and productivity is improved. In addition, the cost can be reduced because the need to repair the reactor is reduced.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing an example of a cylinder type vapor phase growth apparatus to which the present invention is applied.
2 shows the vapor phase growth apparatus of FIG. 1, in which FIG.
FIG. 3 is a schematic longitudinal sectional view showing a conventional cylinder type vapor phase growth apparatus.
[Explanation of symbols]
10 Susceptor 15 Gas supply pipe (gas supply part)
20 bell jar (reactor)
30 Lamp module (heating lamp module)
40 Lamp module cover 41 Cold air inlet 42 Exhaust duct 43 Side cold air inlet 45 Cold air inlet pipe 50 Blower 51 Air outlet 60 Side pipe 61 Ends 100, 101 Vapor phase growth apparatus

Claims (1)

A cylindrical reactor equipped with a susceptor holding a silicon single crystal wafer;
A gas supply unit for supplying a reaction gas into the reaction furnace;
A plurality of heating lamp modules provided around the reactor;
A lamp module cover provided so as to surround the outside of the plurality of heating lamp modules and formed with a cold air inlet for taking in cooling air;
A cold air introduction tube provided outside the lamp module cover so as to communicate with the cold air inlet;
A cylinder type vapor phase growth apparatus comprising: a blower connected to the cold air introduction pipe and supplying cooling air to the cold air introduction pipe;
In the lamp module cover, a side cold air port is formed at a position substantially corresponding to the circumferential direction with respect to the position where polysilicon is deposited on the inner wall surface of the reactor.
The side cold air inlet is connected to an end of a side pipe branched from the cold air introduction pipe ,
The cold air inlet is formed at the top of the lamp module cover,
The cylinder type vapor phase growth apparatus , wherein the side cold air port is formed below the cold air inlet and above a position where the polysilicon is deposited .

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