JP2007281408A - Vapor phase growth device and vapor phase growth method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor phase growth device capable of preventing malfunction of an encoder that monitors rotational speed of a rotor unit and to provide its method. <P>SOLUTION: The vapor phase growth device comprises a process furnace 102, a gas introducing opening 104 which is formed in the process furnace 102 for guiding a film forming gas into the process furnace 102, a gas exhausting opening 106 which is formed in the process furnace 102 for exhausting the film forming gas, a holder 110 in which a wafer is placed and is positioned in the process furnace 102, a rotor unit 112 where the holder 110 is arranged on its upper surface, a rotational mechanism part 120 positioned under the process furnace 102 to rotate the rotor unit 112, an encoder 126 positioned in the rotational mechanism part 120 to monitor the rotational speed of the rotor unit 112, a purge gas introducing pipe 132 for purging the inside of the encoder 126, and a purge gas exhausting pipe 134 which exhausts the gas introduced by the purge gas introducing pipe 132. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vapor phase growth apparatus and a vapor phase growth method, and more particularly, to a vapor phase growth apparatus and a vapor phase growth method that can prevent malfunction of an encoder that monitors the rotation speed of a rotating body unit.

In the manufacture of semiconductor devices such as ultra-high-speed bipolar and ultra-high-speed CMOS, vapor phase growth technology of single crystal layer and polycrystalline layer with controlled impurity concentration and film thickness is indispensable for improving device performance. It has become.
For example, in epitaxial growth in which a single crystal thin film is vapor-grown on a semiconductor substrate such as a silicon wafer, low pressure CVD (Chemical
Vapor Deposition) is often used, and an epitaxial growth apparatus called VPE (including Vapor phase epitaxial growth) is used therein. Among these, an epitaxial growth apparatus using a low pressure CVD method will be described with reference to FIG.

  An epitaxial growth apparatus 300, which is an example of a conventional vapor phase growth apparatus, includes a processing furnace 102, a gas inlet 104 for introducing a reaction gas (film forming gas) into the processing furnace 102, and a gas for discharging the film forming gas. An exhaust port 106, a first vacuum pump 108 connected to the gas exhaust port 106, and a holder 110 that is disposed inside the processing furnace 102 and that holds and holds a semiconductor wafer 116 (hereinafter also simply referred to as a wafer) The rotating mechanism unit 120 includes a rotating body unit 112 that is arranged on the upper surface and rotates, a heater 118 that heats the semiconductor wafer 116 placed on the holder 110, and a rotating device 114 that rotates the rotating body unit 112.

  In addition, an encoder 126 that monitors the number of rotations of the rotating body unit 112 is provided in the rotating mechanism unit 120. By monitoring the rotational speed with the encoder 126, the rotating body unit 112 is controlled to maintain a predetermined rotational speed. Here, the encoder 126 includes an encoder head 128 that detects rotation and an encoder pickup 130 that includes a circuit board that processes the detected signal.

In the conventional epitaxial growth apparatus 300 configured as described above, the circuit board of the encoder 126 is corroded by being exposed to the corrosive reaction gas (film forming gas) used in the processing furnace 102. Therefore, there is a problem that the malfunction of the encoder 126 occurs.
Here, examples of the corrosive reaction gas include SiH ₂ Cl ₂ and SiHCl ₃ used as a source gas, HCl used as an etching gas, and the like.

  In order to solve this problem, in the conventional epitaxial growth apparatus 300, the rotation mechanism section purge gas introduction pipe 202 and the rotation mechanism section purge gas discharge pipe 204 are provided in the rotation mechanism section 120. A purge gas for purging the inside of the rotating mechanism section 120 is introduced from the rotating mechanism section purge gas introduction pipe 202, purges the inside of the rotating mechanism section, and is then discharged from the rotating mechanism section purge gas discharge pipe 204. ing. In this way, by purging the entire rotating mechanism 120 where the encoder 126 is installed with the purge gas, the circuit board of the encoder pickup 130 is suppressed from being exposed to corrosive gas, and malfunction due to corrosion of the encoder 126 is prevented. Was.

  However, in the epitaxial growth apparatus 300, the pressure in the rotation mechanism 120 is not controlled. In addition, a high sealing performance is provided between the processing furnace 102 and the rotation mechanism unit 120 due to the structure of the apparatus in which a rotation shaft 122 that rotates the rotating body unit 112 extends from the rotation mechanism unit 120 to the inside of the processing furnace 102. It cannot be secured. Therefore, when the internal pressure (p1) of the processing furnace 102 is higher than the internal pressure (p2) of the rotating mechanism 120 (p1> p2), the film forming gas (reactive gas) used in the processing furnace 102 is the rotating mechanism. The encoder entered the part 120 and was corroding the encoder. On the other hand, when the internal pressure (p1) of the processing furnace 102 is lower than the internal pressure (p2) of the rotating mechanism 120 (p1 <p2), purge gas contaminated with metal or the like enters the processing furnace 102 from the rotating mechanism 120. There has been a problem that the downflow airflow in the original processing furnace 102 is disturbed and the semiconductor wafer 116 is contaminated.

  In order to solve the above problems, a pressure gauge is provided in the processing furnace 102 and the rotation mechanism 120 to monitor the pressure, and the measurement result is processed and fed back to the pressure regulating valve provided in the purge gas discharge pipe. And the technique of controlling and maintaining the internal pressure of the rotation mechanism part 120 in a specific range is disclosed (for example, patent document 1).

JP 2002-8981 A

  Certainly, as in the technique of the above-mentioned Patent Document 1, a pressure gauge is provided in the processing furnace and the rotation mechanism unit to monitor the pressure, and the measurement result is processed and processed into a pressure adjusting valve provided in the purge gas discharge pipe. By feeding back and maintaining the internal pressure inside the rotation mechanism within a specific range, problems such as turbulence in the downflow airflow in the processing furnace and contamination of the semiconductor wafer are suppressed to some extent. However, it is difficult to completely control the processing furnace internal pressure and the rotation mechanism section internal pressure, and it is difficult to completely avoid problems such as turbulence in downflow airflow and wafer contamination. Further, the above-described technique has a problem that the apparatus becomes complicated by adding a new configuration such as a pressure gauge, a pressure control circuit, a pressure control valve, and the like.

  The present invention has been made in consideration of the above circumstances, and the object of the present invention is to prevent malfunctions by preventing corrosion of the circuit board of the encoder that monitors the rotational speed of the rotating body unit. An object of the present invention is to provide a vapor phase growth apparatus and a vapor phase growth method.

The vapor phase growth apparatus of one embodiment of the present invention includes:
A processing furnace, a gas inlet formed in the processing furnace for introducing a film forming gas into the processing furnace, a gas exhaust port formed in the processing furnace for discharging the film forming gas, and the processing A holder for placing a wafer in the furnace, a rotating unit that places the holder on the upper surface, a rotating mechanism that rotates the rotating unit at the bottom of the processing furnace, and in the rotating mechanism. An encoder for monitoring the number of revolutions of the rotating body unit, a purge gas introduction pipe for purging the inside of the encoder, and a purge gas discharge pipe for discharging the gas introduced by the purge gas introduction pipe are provided.

The vapor growth method of one embodiment of the present invention includes:
A vapor deposition method for forming a film on a wafer,
A purge gas is introduced only into an encoder in a rotating mechanism provided at the lower part of the processing furnace, and the purge gas is discharged outside the rotating mechanism.

  According to the present invention, it is possible to provide a vapor phase growth apparatus and a vapor phase growth method capable of preventing malfunction by preventing corrosion of a circuit board of an encoder that monitors the number of rotations of a rotating body unit. It becomes.

[Embodiment 1]
The epitaxial growth apparatus and epitaxial growth method according to the first embodiment of the present invention have a structure in which an encoder for monitoring the number of rotations of a rotary unit of an epitaxial growth apparatus is directly purged with a purge gas, and a wafer is formed using the epitaxial apparatus. It is characterized by film formation. Hereinafter, the present embodiment will be described with reference to FIG.
Although an epitaxial growth apparatus is described here, the present invention is not necessarily limited to the epitaxial growth apparatus, and can be applied to any vapor phase growth apparatus having a rotation mechanism.

FIG. 1 is a schematic diagram schematically showing an epitaxial growth apparatus according to the present embodiment.
As shown in FIG. 1, an epitaxial growth apparatus 100 according to the present embodiment includes a processing furnace 102 and a gas inlet 104 for introducing a film forming gas (reactive gas or the like) into the processing furnace as in the conventional epitaxial growth apparatus. A gas exhaust port 106 for discharging the film forming gas, a first vacuum pump 108 connected to the film forming gas exhaust port 106 to control the internal pressure inside the processing furnace, and disposed inside the processing furnace, A holder 110 for placing a semiconductor wafer, a rotating body unit 112 arranged on the upper surface thereof for rotation, and a rotating device 114 for rotating the rotating body unit are provided. In addition, the rotary unit 112 disposed inside the processing furnace is provided with a heater 118 that indirectly heats the semiconductor wafer 116 placed on the holder from below the semiconductor wafer by radiant heat.

  In addition, the rotation mechanism unit 120 installed at the lower part of the furnace body of the processing furnace 102 is provided with an encoder 126 that monitors the number of rotations of the rotating body unit 112 using a rotating plate 124 attached to the rotating shaft 122. Yes. The encoder 126 includes an encoder head 128 that detects the rotation of the rotating plate 124 attached to the rotating shaft 122, and an encoder pickup 130 that includes a detected signal processing circuit board. The encoder 126 is a space closed with respect to the rotation mechanism unit 120. A purge gas introduction pipe 132 and a purge gas discharge pipe 134 are connected to the encoder 126 to directly purge the encoder 126. A second vacuum pump 136 is connected to the purge gas discharge pipe 134.

Note that the type of the encoder 126 that monitors the rotational speed used here is not particularly limited, and may be, for example, a magnetic encoder or an optical encoder. However, on the principle of monitoring magnetism, it is preferable to use a magnetic encoder that is less affected by oil, dust and the like and has excellent environmental resistance compared to the optical type.
Here, the magnetic encoder is a device that monitors the change in the magnetic field accompanying the rotation of the magnetized rotating plate with a magnetic sensor such as a magnetoresistive element arranged in the encoder head 128 unit, and measures the rotation speed.

Next, an epitaxial growth method using the epitaxial growth apparatus 100 configured as described above will be described. In addition, operations and effects of the epitaxial growth apparatus 100 and the epitaxial method of the present embodiment will be described.
In the processing furnace 102, the semiconductor wafer 116 to be processed is placed on the holder 110. The rotating body unit 112 having the holder 110 on the upper surface rotates at a predetermined rotation speed by driving the rotating shaft 122 by the rotating device 114 of the rotating mechanism unit 120. At this time, a deposition gas such as a source gas, a dopant gas, and a carrier gas is supplied from the gas inlet 104 toward the upper surface of the semiconductor wafer 116 from above the processing furnace 102. The film forming gas contains a corrosive gas such as HCl. The semiconductor wafer 116 is heated by the heater 118 from the back side of the semiconductor wafer 116. Further, the deposition gas reacts on the heated semiconductor wafer 116 and flows down to the bottom of the processing furnace 102 while growing an epitaxial single crystal film on the surface of the semiconductor wafer 116, and the deposition gas discharge port 106. To the first vacuum pump 108 and discharged. Here, the pressure in the processing furnace 102 is controlled by the vacuum pump 108 so as to be maintained at an optimum condition for epitaxial growth.

Further, the rotation mechanism unit 120 provided at the lower part of the processing furnace 102 is kept in a vacuum by the third vacuum pump 206 so that metal contamination generated in the rotation mechanism unit 120 does not flow into the processing furnace 102. The rotation number of the rotating body unit 112 is monitored by the encoder 126, and the monitoring result is fed back to the rotating device 114, whereby the rotation speed of the rotating body unit 112 can be held at a predetermined value.
Then, in order to protect the circuit board and the like in the encoder pickup 130 from corrosion, the purge gas is directly introduced into the encoder 126 from the purge gas introduction pipe 132 and is drawn from the purge gas discharge pipe 134 by being drawn by the second vacuum pump 136. The
In this way, the internal pressure (p1) of the processing furnace 102 during the epitaxial growth is kept higher (p1> p2) than the internal pressure (p2) of the rotation mechanism 120. Further, the internal pressure (p3) of the encoder 126 is also kept higher (p3> p2) than the internal pressure (p2) of the rotation mechanism 120.

Here, the purge gas used is not particularly limited as long as it is a gas that does not corrode the circuit board or the like in the encoder pickup 130.
In the case of the conventional epitaxial growth apparatus shown in FIG. 3, it is preferable to use H ₂ gas. This is because, since the carrier gas and the gas type are the same in the processing furnace 102, even if it flows into the processing furnace 102 via the rotating mechanism 120, the influence on the film growth is limited. .
However, H ₂ gas was not preferable from the viewpoint of safety and ease of handling.
In the case of the present embodiment, the purge gas flows only in the closed encoder 126 and the circuit mechanism unit 120 is evacuated, so even if a leak occurs from the encoder 126, the processing furnace It is difficult for the gas to flow into 102. Therefore, it is possible to use an inert gas such as N ₂ or Ar that is highly safe and easy to handle as the purge gas, and it is preferable to use the inert gas as the purge gas.

  As described above, in the conventional technique, the purge gas is caused to flow through the entire rotating mechanism unit 120 provided at the lower portion of the processing furnace 102, and therefore the internal pressure (p1) of the processing furnace 102 is higher than the internal pressure (p2) of the rotating mechanism unit 120. At (p1> p2), the film forming gas (reactive gas) used in the processing furnace 102 entered the rotating mechanism 120 and corroded the encoder. On the contrary, when the internal pressure (p1) of the processing furnace 102 is lower than the internal pressure (p2) of the rotating mechanism 120 (p1 <p2), purge gas contaminated with metal or the like flows from the rotating mechanism 120 into the processing furnace 102. There has been a problem that the downflow airflow in the original processing furnace 102 is disturbed or the semiconductor wafer 116 is contaminated.

  However, according to the present embodiment, not only the entire rotation mechanism unit 120 but also only the inside of the encoder 126 closed with respect to the rotation mechanism unit is directly purged. 120 (p1> p2) can always be kept higher than the 120 internal pressure (p2), and the internal pressure (p3) of the encoder 126 can also be kept always higher (p3> p2) than the internal pressure (p2) of the rotating mechanism 120.

  Therefore, the internal pressure (p1) of the processing furnace 102 becomes lower than the internal pressure (p2) of the rotating mechanism 120 (p1 <p2), and the purge gas contaminated with metal flows from the rotating mechanism 120 into the processing furnace 102, and the original processing The problem of disturbing the downflow airflow in the furnace 102 or contaminating the semiconductor wafer 116 cannot occur.

  Certainly, since the internal pressure (p1) of the processing furnace 102 is always higher (p1> p2) than the internal pressure (p2) of the rotation mechanism 120, the film forming gas (reaction gas) enters the rotation mechanism 120. However, since the internal pressure (p3) of the encoder 126 is always kept higher (p3> p2) than the internal pressure (p2) of the rotation mechanism unit 120, the film forming gas (reaction gas) enters the encoder 126 from the rotation mechanism unit 120. Intrusion is prevented. In particular, conventionally, there is a restriction on the upper limit of the internal pressure (p2) of the rotation mechanism 120 in order to avoid the purge gas from flowing into the processing furnace 102 from the rotation mechanism 120. That is, in order to increase the purge effect, it has been impossible to increase the internal pressure (p2) of the rotating mechanism 120 significantly higher than the internal pressure (p1) of the processing furnace 102 (p2 >> p1). According to the present embodiment, since the internal pressure (p3) of the encoder 126 can be set independently of the internal pressure (p1) of the processing furnace 102, the internal pressure (p3) of the encoder 126 is set to the internal pressure (p1) of the processing furnace 102 or the rotation mechanism. The internal pressure (p2) can be significantly increased (p3 >> p1, p3 >> p2). Therefore, the circuit board in the encoder pickup 130 is not corroded by the reaction gas (film forming gas) that has entered the rotating mechanism 120 from the processing furnace 102.

As described above, according to the present embodiment, the malfunction of the encoder due to the corrosion of the circuit board does not occur, stable rotation of the rotating body unit can be maintained, and high-quality epitaxial growth can be realized.
Furthermore, according to the present embodiment, there is no need to provide a mechanism such as a pressure gauge, a control circuit, or a pressure regulating valve, which is required for the prior art of Patent Document 1. Therefore, since the apparatus is not complicated, the problem of an increase in manufacturing cost of the manufacturing apparatus can be avoided.
Further, the present embodiment can be realized only by connecting a purge pipe to a conventional encoder. Therefore, it is possible to contribute to the suppression of the manufacturing cost increase of the manufacturing apparatus from the viewpoint that the conventional apparatus configuration can be used as it is.

[Embodiment 2]
Next, as a second embodiment, an epitaxial growth apparatus provided with a rotating device that can rotate the rotating body unit at a rotational speed of 100 min ⁻¹ or more (100 rpm) to which the present invention is applied, and an epitaxial growth using the same The method will be described with reference to FIG.
When the high-speed rotation CVD method is used to rotate the rotating body unit at a high speed of 100 min ⁻¹ or more (100 rpm), the rotation of the rotating shaft 122 extending from the rotating body unit 112 to the rotating device 114 becomes faster. It is more difficult to ensure a high sealing performance than when the rotational speed is low. Therefore, when there is a difference between the internal pressure (p1) of the processing furnace 102 and the internal pressure (p2) of the rotating mechanism 120, there is a problem that the leakage of the reaction gas or the purge gas is further increased and the corrosion of the encoder becomes more remarkable. It was.

  The basic configuration of the processing furnace 102, gas introduction port 104, gas exhaust port 106, vacuum pump 108, holder 110, rotating body unit 112, and the like is the same as that of the first embodiment shown in FIG.

However, the epitaxial growth apparatus of this embodiment, a rotator unit 112, while the rotation speed of the conventional epitaxial growth apparatus is less than 100 min ^-1, rotation that enables to rotate at 100 min ^-1 or more rpm It differs from the above-mentioned embodiment by the point provided with the apparatus 114. FIG.

The film formation conditions in the present embodiment are not particularly limited as in the first embodiment, and the same film formation conditions as in the prior art can be taken.
However, for example, when forming P-type silicon on an 8-inch diameter silicon wafer using SiH ₄ (silane) as a silicon source gas, it is preferable to form the film in the following condition range.
Set temperature: 920-1020 ° C
Processing furnace pressure: 2 to 6.667 KPa (15 to 50 torr)
Silicon source gas: SiH ₄ (silane)
Silicon source gas flow rate: 0.4-0.8 slm
Dopant gas: B ₂ H ₆
Carrier gas / flow rate: H ₂ · 40-50 slm
Purge gas: H ₂
Semiconductor wafer rotation speed: 1300-1500 min ⁻¹ (1300-1500 rpm)
However, sccm and slm are units of gas flow rate, and 1 sccm indicates that a gas having a weight occupying a volume of 1 cc (1 cm ³ ) in a standard state flows per minute. Further, slm indicates that the weight of the gas occupying the volume per minute 1L (1 dm ³⁾ is flowing, 1 slm is equivalent to 1000 sccm.

For example, when forming P-type silicon on an 8-inch diameter silicon wafer using SiH ₂ Cl ₂ (dichlorosilane: DCS) as a silicon source gas, it is preferable to form the film in the following condition range.
Set temperature: 980-1100 ° C
Processing furnace internal pressure: 10.67 to 53.33 KPa (80 to 400 torr)
Silicon source gas: SiH ₂ Cl ₂ (dichlorosilane: DCS)
Silicon source gas flow rate: 0.5-1.5 slm
Dopant gas: B ₂ H ₆
Dopant gas flow rate: 150 to 300 sccm
Carrier gas / flow rate: H ₂ · 40-50 slm
Purge gas: H ₂
Semiconductor wafer rotation speed: 1300-1500 min ⁻¹ (1300-1500 rpm)

For example, when N-type silicon is formed on an 8-inch diameter silicon wafer using SiHCl ₃ (trichlorosilane: TCS) as a silicon source gas, it is preferable to form the film in the following condition range.
Set temperature: 1100-1150 ° C
Processing furnace pressure: 80 to 101.3 kPa (600 to 760 torr)
Silicon source gas: SiHCl ₃ (trichlorosilane: TCS)
Silicon source gas flow rate: 20-35 slm
First layer dopant gas: PH ₃
Dopant gas flow rate: 200 to 250 sccm
Second layer dopant gas: PH ₃
Dopant gas flow rate: 40-60 sccm
Carrier gas / flow rate: H ₂ · 100 to 120 slm
Purge gas: H ₂
Semiconductor wafer rotation speed: 800 to 1000 min ⁻¹ (800 to 1000 rpm)

Although the purge gas is H ₂ here, it is more preferable to use an inert gas such as N ₂ or Ar that is highly safe and easy to handle as in the first embodiment. .

  As described above, in the high-speed rotation CVD method in which the epitaxial growth is performed by rotating the semiconductor wafer 116 at a high rotational speed, an extremely thin concentration boundary layer (boundary layer) is provided immediately above the semiconductor wafer 116, thereby achieving a high film formation rate and Epitaxial single crystal film growth with high in-plane film thickness uniformity is possible.

  However, when the high-speed rotation CVD method is used, as described above, there is a problem that the leakage of the reaction gas or the purge gas is further increased and the corrosion of the encoder becomes more remarkable as compared with the case of the conventional low-speed rotation. It was.

  However, in the present embodiment, as in the first embodiment, not only the entire rotation mechanism unit 120 but also the inside of the encoder 126 that is closed with respect to the rotation mechanism unit 120 is directly purged, thereby increasing gas leakage. Even so, the internal pressure (p3) of the encoder 126 can be set with a high degree of freedom so that the circuit board in the encoder pickup 130 does not corrode. Therefore, even in a high-speed rotation CVD apparatus that may increase the leakage at the rotating shaft 122, this embodiment can effectively prevent malfunction of the epitaxial growth apparatus due to encoder corrosion. Become.

[Embodiment 3]
The epitaxial apparatus and the epitaxial growth method according to the third embodiment of the present invention have a structure in which an encoder for monitoring the number of rotations of a rotating body unit of the epitaxial apparatus is directly purged with a purge gas, and the rotation mechanism is also purge gas independent of the encoder. And purging the film on the wafer using the epitaxial apparatus. Hereinafter, the present embodiment will be described with reference to FIG.

FIG. 2 is a schematic diagram schematically showing an epitaxial growth apparatus 200 according to the present embodiment.
A third vacuum pump 206 connected to the rotation mechanism section purge gas introduction pipe 202, the rotation mechanism section purge gas discharge pipe 204, and the rotation mechanism section purge gas discharge pipe 204 for purging the rotation mechanism section 120 independently of the encoder 126 is provided. Since it is the same as that of Embodiment 1 or Embodiment 2 except having it, description is abbreviate | omitted.

In the present embodiment, a purge gas for purging the rotation mechanism 120 independently of the encoder 126 is introduced into the rotation mechanism 120 from the rotation mechanism purge gas introduction pipe 202. The purge gas is drawn from the rotation mechanism portion purge gas discharge pipe 204 by being drawn by the third vacuum pump 206.
At this time, regarding the internal pressure (p1) of the processing furnace 102, the internal pressure (p2) of the rotation mechanism 120, and the internal pressure (p3) of the encoder 126, the internal pressure (p2) of the rotation mechanism 120 is always lower than the internal pressure (p1) of the processing furnace 102 (p1> p2) and the flow rate of the purge gas for purging the rotation mechanism 120 and the encoder 126 is set so that the internal pressure (p3) of the encoder 126 is always higher than the internal pressure (p2) of the rotation mechanism 120 (p2 <p3).

As described in the first embodiment, by directly purging the encoder 126, it is possible to take measures against malfunction caused by corrosion of the encoder 126, which has been a problem in the past. However, if inflow of the reaction gas into the rotation mechanism unit 120 continues, mechanical parts such as bearings constituting the rotation mechanism unit 120 are contaminated, and thus the rotation mechanism unit 120 needs to be cleaned (maintenance). Therefore, it is not preferable.
According to the present embodiment, unlike Embodiment 1 and Embodiment 2 in which the purge mechanism 120 is kept in a vacuum without flowing the purge gas, the purge gas can also flow through the rotation mechanism 120. Therefore, it is possible to alleviate contamination of the machine parts constituting the rotation mechanism unit 120.
Further, since the purge gas flow rate is set so that the internal pressure (p2) of the rotating mechanism 120 is always lower than the internal pressure (p1) of the processing furnace 102 (p1> p2), the reverse flow of the purge gas from the rotating mechanism 120 into the processing furnace 102 also occurs. Does not occur.
Further, since the purge gas flow rate is set so that the internal pressure (p3) of the encoder 126 is always higher than the internal pressure (p2) of the rotation mechanism 120 (p2 <p3), the reaction gas flowing into the rotation mechanism 120 enters the encoder 126. There is nothing.

  Therefore, according to the present embodiment, it is possible to obtain an effect of reducing the cleaning (maintenance) frequency of the rotating mechanism unit 120 while preventing malfunction due to corrosion of the encoder 126.

  Since the operations and effects other than those described above are the same as those in the first embodiment or the second embodiment, description thereof will be omitted.

  The vapor phase epitaxial growth using the epitaxial growth apparatuses according to the first, second, and third embodiments described above is particularly different from the growth method using the conventional apparatus except that the above apparatus configuration is adopted. However, almost the same conditions may be adopted. The semiconductor substrate used for film formation is typically a silicon wafer, but a semiconductor substrate other than silicon, such as a silicon carbide substrate, can also be used. The thin film formed on the semiconductor substrate is most commonly a silicon film or a single crystal silicon film containing boron, phosphorus, arsenic or the like as an impurity, but a polysilicon film or other thin film such as a GaAs film. And compound semiconductors such as GaAlAs films can be applied without any problem. Further, the film forming gas used for the vapor phase growth is not particularly limited, and a film forming gas used for film formation by a normal epitaxial growth method can be used.

  The embodiments of the present invention have been described above with reference to specific examples. In the embodiment, the description of the portions of the vapor phase growth apparatus and the vapor phase growth method that are not directly required for the description of the present invention is omitted. However, the vapor phase growth apparatus and the vapor phase growth method that are required are omitted. It is possible to appropriately select and use elements related to the above.

  In addition, all vapor phase growth apparatuses and vapor phase growth methods that include elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

Examples and comparative examples will be described below with reference to FIGS.
(Example)
FIG. 1 shows an epitaxial growth apparatus to which the present invention is applied. Using this apparatus, a silicon film containing boron as an impurity was epitaxially grown on the surface of a semiconductor wafer. At this time, the relationship between the flow rate of the purge gas and the internal pressure of the rotating mechanism was measured.
The conditions for forming the epitaxial growth film were as follows.
Semiconductor wafer to be processed: 8-inch diameter silicon wafer Setting temperature: 1000 ° C
Processing furnace pressure: 2000 Pa (15 torr)
Silicon source gas: SiH ₄ (silane)
Silicon source gas flow rate: 0.56 slm
Dopant gas: B ₂ H ₆ (diborane)
Carrier gas / flow rate: H ₂ · 50 slm
Purge gas: H ₂
Semiconductor wafer rotation speed: 1500 min ⁻¹ (1500 rpm)

(Comparative example)
FIG. 3 shows an epitaxial growth apparatus to which the conventional technique is applied as described above. For comparison with the example, a silicon film containing boron as an impurity was epitaxially grown on the surface of the semiconductor wafer using this apparatus. Conditions other than the apparatus were the same as those in the example. At this time, the relationship between the flow rate of the purge gas and the internal pressure of the circuit mechanism was measured as in the example.

(Experimental result)
In the case of the comparative example, when H2 as the purge gas exceeds 500 sccm, the internal pressure of the rotating mechanism reaches 1933 Pa (14.5 torr), approaches the processing furnace internal pressure of 2000 Pa (15 torr), and the reverse flow of the purge gas to the processing furnace Because of fear, film formation had to be stopped.
On the other hand, in the case of Example, even if it exceeded 1000 sccm, the change did not arise in the initially set rotation mechanism part internal pressure.

  From the above, it has been found that in the examples, there is no fear of backflow of the purge gas from the inside of the rotating mechanism to the processing furnace even if a purge gas having a flow rate more than twice that of the comparative example is flowed. Therefore, the effectiveness of purging the encoder of the present invention was confirmed by the examples.

Schematic of epitaxial growth apparatus according to Embodiment 1 Schematic of epitaxial growth apparatus according to Embodiment 3 Schematic diagram of an epitaxial growth apparatus according to the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Epitaxial growth apparatus 102 Processing furnace 104 Gas inlet 106 Gas outlet 108 First vacuum pump 112 Rotor unit 114 Rotator 116 Semiconductor wafer 120 Rotating mechanism part 122 Rotating shaft 124 Rotating plate 126 Encoder 132 Purge gas inlet 134 Purge gas outlet 136 Second vacuum pump 200 Epitaxial growth apparatus 202 Rotating mechanism part purge gas inlet 204 Rotating mechanism part purge gas outlet 206 Third vacuum pump 300 Epitaxial growth apparatus

Claims (6)

  A processing furnace; a gas inlet formed in the processing furnace for introducing a film forming gas into the processing furnace; a gas exhaust port formed in the processing furnace for discharging the film forming gas; and the processing A holder in the furnace for mounting the wafer; a rotating unit that places the holder on the upper surface; a rotating mechanism that is provided in the lower portion of the processing furnace and rotates the rotating unit; and the rotating mechanism. A gas phase comprising an encoder for monitoring the number of revolutions of the rotating body unit, a purge gas introduction pipe for purging the inside of the encoder, and a purge gas discharge pipe for discharging the gas introduced by the purge gas introduction pipe. Growth equipment.   The vapor phase growth apparatus according to claim 1, wherein the encoder is a magnetic encoder. 3. The vapor phase growth apparatus according to claim 1, further comprising a rotating device that enables the rotating body unit to rotate at a rotation speed of 100 min ⁻¹ or more.   A purge gas introduction pipe for purging the inside of the rotation mechanism section independently from the inside of the encoder, and a purge gas discharge pipe for discharging the gas introduced by the purge gas introduction pipe for purging the inside of the rotation mechanism section independently of the inside of the encoder. The vapor phase growth apparatus according to any one of claims 1 to 3, further comprising a vapor phase growth apparatus. A vapor deposition method for forming a film on a wafer,
A vapor phase growth method comprising the steps of introducing a purge gas only into an encoder in a rotating mechanism provided at a lower portion of the processing furnace, and discharging the purge gas to the outside of the rotating mechanism. 6. The vapor phase growth method according to claim 5, wherein an internal pressure of the processing furnace and an internal pressure of the encoder are maintained higher than an internal pressure of the rotating mechanism unit.

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