JP2012186355A - Vapor growth device with lifting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor growth device equipped with a stop mechanism which prevents heavy goods, i.e. a gas outflow part, from falling while maintaining the surface height of the gas outflow part accurately when the gas outflow part is lifted.SOLUTION: In the vapor growth device equipped with the fall mechanism of a gas outflow part 105 that stops rotation of a ball screw 22 lifting the gas outflow part 105, a plurality of ball screws 22 are connected with the gas outflow part 105 via a shaft 21, and a plurality of belt fracture detection sensors 28, 29, 30, 31 are installed on all timing belts 27 connecting respective ball screws 22 and a motor 26.

Description

  The present invention relates to a vapor phase growth apparatus having an elevating mechanism for forming a thin film on a substrate to be processed.

  Conventionally, in the manufacture of light-emitting diodes, semiconductor lasers, space solar power devices, and high-speed devices using compound semiconductor materials, organometallic gases such as trimethylgallium (TMG) or trimethylaluminum (TMA), ammonia (NH3), A MOCVD method is used in which a compound semiconductor crystal is grown by introducing a hydrogen compound gas such as phosphine (PH3) or arsine (AsH3) into a growth chamber as a reaction gas contributing to film formation.

  The MOCVD method is a method in which a compound semiconductor crystal is grown on a substrate by introducing the above-mentioned reaction gas together with a carrier gas into a growth chamber and heating it to cause a gas phase reaction on a predetermined substrate. In the production of compound semiconductor crystals using MOCVD, there is always a high demand for how to secure the maximum yield and production capacity while reducing costs while improving the quality of growing compound semiconductor crystals. Has been.

  FIG. 10 shows a schematic configuration of an example of a conventional gas outflow portion type vapor phase growth apparatus used in the MOCVD method. In this vapor phase growth apparatus, a gas pipe 104 for introducing a reaction gas and a carrier gas from a gas supply source 101 to a growth chamber 103 inside the reaction furnace 102 is connected, and the internal growth chamber in the reaction furnace 102 is connected. A gas outflow portion 105 provided with a plurality of gas discharge holes for introducing a reaction gas and a carrier gas into the growth chamber 103 is provided as a gas introduction portion above the 103.

  In addition, a susceptor 107 for placing the substrate 106 is installed below the growth chamber 103 so as to face the gas outflow portion 105. The susceptor 107 includes a heater 108 for heating the substrate 106, and is rotatable about a rotation shaft 109 by an actuator (not shown).

  Further, a gas exhaust unit 110 for exhausting the gas in the growth chamber 103 to the outside is installed at the lower part of the reaction furnace 102. The gas exhaust unit 110 is connected via a purge line 111 to an exhaust gas treatment device 112 for rendering the exhausted gas harmless.

  When a compound semiconductor crystal is grown in the gas outflow portion type vapor phase growth apparatus having the above configuration, first, the substrate 106 is set on the susceptor 107, the susceptor 107 is rotated, and the substrate 106 is brought to a predetermined temperature by the heater 108. Heat. Thereafter, a reaction gas and a carrier gas (inert gas) are introduced into the growth chamber 103 from a plurality of gas discharge holes arranged in the gas outflow portion 105 and held for a certain period of time, whereby a compound semiconductor is formed on the substrate 106. Crystal growth is performed. Then, after raising the gas outflow part 105 at the upper part of the reaction furnace 102 to replace the grown substrate and removing the reaction decomposition products, the gas outflow part 105 at the upper part of the reaction furnace 102 is lowered again to grow the growth chamber 103. Repeat the same process with airtightness.

On the other hand, the gas outflow part 105 at the top of the reaction furnace 102 is held by a lifting mechanism (not shown). As the diameter of the substrate 106 is increased, the gas outflow portion 105 has a weight of nearly 1 ton, and in recent years, the weight applied to the lifting mechanism that holds the gas outflow portion 105 has increased considerably. For this reason, it is necessary to take sufficient measures to prevent the gas outflow portion 105 from dropping when the gas outflow portion 105 is moved up and down every time the crystal is grown. Patent Documents 1 and 2 propose methods for dealing with the safety of such a lifting mechanism.
In Patent Document 1, although it is not a vapor phase growth apparatus, when the power transmission mechanism from the motor for moving the X-ray tube, the top plate, the imaging apparatus, etc. to the up and down movement to the ball screw is broken, the apparatus or the like is not dropped. The structure of an X-ray diagnostic apparatus with a safe mechanism is described. As shown in FIG. 11, a belt breakage detection sensor 114 is provided as an abnormality detection means for detecting an abnormality when the belt 113 is broken. For example, the belt breakage detection sensor 114 serving as the abnormality detection means is provided with a transmission type optical sensor including a light emitting unit and a light receiving unit at a position where the belt 113 travels, and detects an abnormality of the power transmission mechanism unit based on the output. . On the other hand, the ball screw portion has a ball screw mechanism in which the screw rod 115 is fixed to the apparatus and the nut 116 rotates.
In Patent Document 2, as shown in FIG. 13, a structure of a handrail belt driving device for a passenger conveyor is described in which a driving belt that drives a handrail belt is circulated and moved in synchronization with a footboard. Further, as shown in FIG. 14, a biasing mechanism 119 that biases the idler 117 in a direction in which the deflection of the drive chain 118 is eliminated, a shaft body 120 that rotatably supports the idler 117, and the shaft body 120 are indicated by arrows. A housing 121 configured to be supported so as to be movable in the Z direction, and interposed between the housing 121 and the idler 117 so that the idler 117 can be urged so as to always press the drive chain 118. The coil spring 122 is made up of. In a state where the length of the drive chain 118 is increased to such an extent that the safety of the passenger is jeopardized due to wear or the like, the limit switch 123 is activated, and the operation signal is supplied to the control panel to turn off the motor immediately. In addition, the movement of the footboard and the handrail belt can be stopped.

JP 2002-11003 A JP 2007-191284 A

As a problem of the vapor phase growth apparatus, it has been necessary to implement a countermeasure in terms of safety so that the gas outflow portion 105 does not fall when the gas outflow portion 105 is moved up and down every time crystal growth is performed.
Furthermore, the gas outflow portion 105 itself has a weight of nearly 1 ton and is a heavy object, and it is not possible to hold the supporting ball screw with one, and it is necessary to support with two or more ball screws. was there.
In addition, two or more ball screws always have a constant gas outflow portion because the gas pipe 104 for introducing the reaction gas and the carrier gas into the internal growth chamber 103 is connected to the gas outflow portion 105. If the elevating mechanism is not operated while maintaining the surface height of 105, there is a possibility that the gas flow rate and flow velocity will be adversely affected, and that film formation may be non-uniform during crystal growth.

  In the case of Patent Document 1, a transmission type optical sensor including a light emitting unit and a light receiving unit is provided at a position where the belt 113 travels, and an abnormality of the power transmission mechanism unit is detected based on the output. The ball screw portion is a ball screw mechanism in which the screw rod 115 is fixed to the apparatus and the nut 116 rotates. The mechanism has a single screw rod 115, and a heavy structure cannot be connected to a work to be lifted (an X-ray tube, an imaging device, a top plate, etc. are attached). In addition, as shown in FIG. 12, the transmissive optical sensor 114 does not sense that the belt is broken and the light shielding part is not completely removed from the front of the sensor, and there is a time delay until the sensor reacts. appear. In particular, even when only one of the two belts between the transmission type optical sensors is disconnected, it is difficult to detect the disconnection of the belt if the remaining one is shielded from light. Therefore, it is not possible to sufficiently secure the fall prevention in a short time until the fall required by a large apparatus such as a vapor phase growth apparatus.

  In the case of Patent Document 2, a position detector 124 that can detect the position of the idler 117 that is moved by being urged by the urging mechanism 119 is provided. Compared with Patent Document 1, prevention of disconnection can be confirmed in a shorter time. . In addition, the limit switch 123 operates in a state where the length of the drive chain 118 is increased to such an extent that the safety of passengers is jeopardized due to wear or the like, and the operation signal is supplied to the control panel to turn off the motor. Immediately, the movement of the tread plate and the handrail belt can be stopped, and the drive chain 118 is stopped before the entire length becomes longer due to wear and the operation is disturbed. It is possible to prevent the customer from becoming in a dangerous state due to the loss of synchronization.

However, the drive chain 118 has only one electric motor and drive wheel, and it is difficult to secure a heavy object such as a gas outflow portion while maintaining a certain lifting accuracy. Further, the position detector 124 is biased to one location, and when the position detector 124 malfunctions due to some influence, sufficient safety cannot be ensured. Therefore, it is difficult to perform management with a heavy weight in the gas outflow part such as a vapor phase growth apparatus being raised and lowered with high accuracy and sufficiently ensuring safety when the drive chain is bent or disconnected.
The present invention has been made in view of the above-described conventional problems, and the object thereof is to maintain a high surface height of the gas outflow portion with high accuracy when the gas outflow portion is moved up and down, and which is a heavy gas outflow portion. It is to provide a vapor phase growth apparatus provided with a stop mechanism for preventing the falling of the material.

A vapor phase growth apparatus according to the present invention is a vapor phase growth apparatus that forcibly stops rotation of a ball screw that moves up and down a gas outflow portion and includes a dropping mechanism for the gas outflow portion. A plurality of ball screws are connected to each other, and a plurality of belt breakage detection sensors are installed on all timing belts connecting the respective ball screws and the motor.

  Alternatively, in the vapor phase growth apparatus of the present invention, a plurality of ball screws are connected to each other through a shaft to a gas outflow portion, and a belt breakage detection sensor is provided at a part of a timing belt that connects each ball screw and a motor. It is characterized by having installed.

By connecting a plurality of shafts to the gas outflow part of the vapor phase growth apparatus and installing a plurality of belt breakage detection sensors on the timing belt connecting each shaft, ball screw, and motor, the gas outflow part is moved up and down. Sometimes, it is possible to prevent the gas outflow portion, which is a heavy object, from falling while maintaining the surface height of the gas outflow portion with high accuracy.

It is the schematic which shows the whole structure of the vapor phase growth apparatus which concerns on this invention. It is sectional drawing which shows the growth chamber structure of a vapor phase growth apparatus. It is a perspective view of the gas outflow part and raising / lowering mechanism of a vapor phase growth apparatus. It is a perspective view of the raising / lowering mechanism of the gas outflow part upper part of a vapor phase growth apparatus. FIG. 4 is an arrangement top view of the timing belt and the belt breakage detection sensor according to the first embodiment. FIG. 3 is a perspective view of the timing belt and the belt breakage detection sensor according to Embodiment 1 before disconnection. FIG. 3 is a perspective view of the timing belt and the belt breakage detection sensor according to Embodiment 1 before disconnection. FIG. 6 is an arrangement perspective view of a belt breakage detection sensor of Example 2. 3 is a structural diagram of a belt breakage detection sensor according to Embodiment 1 and Embodiment 2. FIG. It is explanatory drawing of the vapor phase growth apparatus of a prior art example. It is explanatory drawing of the patent document 1 of a prior art example. It is explanatory drawing of the patent document 1 of a prior art example. It is explanatory drawing of the patent document 2 of a prior art example. It is explanatory drawing of the patent document 2 of a prior art example.

  An embodiment of the present invention will be described with reference to FIG. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

FIG. 1 shows an example of a schematic configuration of an entire MOCVD apparatus 1 as a vapor phase growth apparatus of the present invention. As shown in FIG. 1, the entire MOCVD apparatus 1 mainly includes a growth chamber 2 for growing a compound semiconductor crystal, a substrate heating mechanism 3 for heating a substrate in the growth chamber, a lifting mechanism 4 for raising and lowering a gas outflow portion, and a gas (not shown). It consists of a cooling pipe system that cools the periphery of the outflow part, a high vacuum exhaust system that exhausts the growth chamber, and a process gas exhaust system.
The present invention relates to an elevating mechanism for elevating and lowering a gas outflow portion among these main components.

  Moreover, FIG. 2 is sectional drawing which shows a long chamber structure. The growth chamber is provided with a reaction furnace 5 that isolates the interior from the atmosphere side. Inside the reaction furnace 5, a reaction external space 7 and a reaction chamber 8 separated by a reaction chamber partition wall 6 are provided. A purge gas supply pipe 9 is connected to the reaction external space 7, and purge gas (N2 gas, H2 gas) is introduced. The reaction chamber 8 is provided with a substrate holder 11 (susceptor) on which the substrate 10 to be processed is placed. The substrate holding unit 11 is provided at one end of the rotation transmitting unit 12 and can be rotated by a rotation mechanism (not shown). A substrate heater 13 for heating the substrate to be processed 10 is provided below the substrate holding unit 11.

  A gas outflow portion 14 is detachably disposed at the upper portion of the reaction furnace 5. The reaction furnace 5 and the gas outflow portion 14 are sealed by an O-ring 14a, and the inside of the reaction furnace 5 can be exhausted from the gas discharge port and maintained in an airtight state.

  When a compound semiconductor crystal is formed on the substrate 10 to be processed, for example, a first gas containing a group III element is introduced into the first gas distribution space 15 from the first gas introduction port 16a. After being cooled through the plurality of first gas supply pipes 17b penetrating, the reaction gas is introduced into the reaction chamber 8 through the plate holes 18a of the central plate 18 communicating with the gas discharge holes H1 of the first gas supply pipe 17b.

  Further, for example, a second gas containing a group V element is introduced into the second gas distribution space 19 from the second gas introduction port 19 a and passes through the plurality of second gas supply pipes 20 b penetrating the refrigerant space 17. After being cooled, the gas is introduced into the reaction chamber 8 from the central plate 18 communicating with the gas discharge hole H2 of the second gas supply pipe 20b.

As described above, the gas outflow portion 14 has a large number of first gas supply pipes and second gas supply pipes, and has a large area with an increase in the diameter of the substrate to be processed. It has become. After film formation, the gas outflow portion 14 is opened from the reaction furnace 5 by an O-ring 14a connected to an elevating mechanism (not shown), and the replacement and maintenance of the crystal substrate are performed. Although the gas outflow part 14 of a present Example was demonstrated in the Example called a shower head, it is not limited to this structure,
It includes those that have a gas outflow part called the center radiation type and line radiation type.
Next, an embodiment of the lifting mechanism which is a characteristic of the present invention will be described in detail with reference to FIGS. 3 to 4, and a belt breakage detection sensor and another embodiment will be described in detail with reference to FIGS.
FIG. 3 is a perspective view of the gas outflow portion and the lifting mechanism of the vapor phase growth apparatus. The gas outflow part 14 is connected by four shafts 21 penetrating the glove box. The four shafts 21 are connected to one ball screw 22 by two each. The connected ball screw 22 raises or lowers the connected shaft 21 while rotating at a constant speed. As a result, the gas outflow portion 14 connected to the shaft 21 moves up or down at a constant speed. The heavy gas outflow portion 14 is configured by four shafts 21 and two ball screws 22, so that the height variation is suppressed with high accuracy and the diameter of the gas outflow portion 14 is increased. The brake unit 23 is configured and can be forcibly stopped when the limit of the rise of the ball screw 22 is exceeded. Further, the two ball screws 22 are connected to each other via a bridging portion 24 at the upper portion, and have an effect of uniformly distributing the load applied to the ball screw by the gas outflow portion. In FIG. 3, the connection part 25 of the ball screw 22 and the four shafts 21 is located in the lower part, and represents the state where the gas outflow part 14 descend | falls.
FIG. 4 is a perspective view of the lifting mechanism at the upper part of the gas outflow part of the vapor phase growth apparatus. In FIG. 4, the connecting portion 25 is located at the upper part as compared with FIG. 3, and the four shafts 21 are raised by the rotation of the ball screw 22 in the direction of the arrow shown in the figure, and the gas outflow portion 14 is raised Represents. The two ball screws 22 are connected to each other via a bridge portion 24 at the upper portion, and rise while dispersing the load on the ball screw 22 by the gas outflow portion 14 uniformly, and are forcibly stopped at the upper limit. It is in a state. With these structures, the safety against dropping of the four shafts 21 is improved as compared with the case where they are not connected.

  FIG. 5 is a top view showing the drive structure of the shaft 21, the ball screw 22, and the motor 26 by the timing belt 27 and the arrangement of the belt breakage detection sensors 28, 29, 30, and 31. The two ball screws 22 in FIG. 5 are rotationally driven by a timing belt 27 wound around the ball screw 22 and connected to the same one motor 26 via a relay shaft 32. That is, the driving from the motor 26 is transmitted by the timing belt 27 and converted into rotational driving of the two ball screws 22. At this time, it is assumed that the timing belt 27 is disconnected under the influence of overloading any one of the ball screws 22 or damage to the timing belt 27. Therefore, two belt breakage detection sensors 28 and 31 are arranged on two timing belts 27 connecting the motor 26 and the relay shaft 32, respectively, and two timing belts 27 connecting the relay shaft 32 and the ball screw 22 are arranged at two locations. The belt breakage detection sensors 29 and 30 are arranged, and the belt breakage detection sensors 28, 29, 30, and 31 are arranged at positions opposite to the left and right ball screws 22 around the motor 26 as shown in FIG. With this configuration, when the timing belt 27 is disconnected due to overloading of any one of the ball screws 22 or damage to the timing belt 27, any one of the belt breakage detection sensors 28, 29, 30 and 31 can detect the situation and prevent the gas outflow portion 14 from dropping due to disconnection. Further, by arranging the belt breakage detection sensors 28, 29, 30, and 31 at any of the plurality of belt positions, any of them has an effect of preventing the fall in a short time even when the timing belt 27 is broken.

FIG. 6 shows a structural diagram of the belt breakage detection sensor 28 as an example. The belt breakage detection sensor 28 is mainly composed of a photo sensor including a light emitting unit 33 and a light receiving unit 34 and a flag plate 35. Furthermore, in FIG. 7, the behavior when the belt breakage detection sensor is disconnected will be described. When these belt breakage detection sensors are used and the timing belt 27 is not disconnected as shown in FIG. 7, the flag plate 35 is pushed by the tension of the timing belt 27, so that the gap between the light emitting unit 33 and the light receiving unit 34 is In the state where the flag plate 35 is inserted, the light receiving portion 34 is not incident and the brake is always energized. Next, as shown in FIG. 8, in the situation where the timing belt 27 is disconnected, the tension due to the timing belt 27 is instantaneously lost, and the light shielding between the light emitting portion 33 and the light receiving portion 34 of the flag plate 35 in the photosensor is eliminated. Then, the light enters the light receiving unit 34. In this state, the brake is interrupted, and a stop mechanism for preventing the gas outflow portion 14 from falling is activated instantly.
[Embodiment 2]
Another embodiment will be described with reference to FIG. FIG. 9 is different from FIG. 5 only in the arrangement configuration of the belt breakage detection sensors 28, 29, 30, and 31, and therefore only different portions will be described.
9, the arrangement | positioning state of the belt breakage detection sensors 30 and 31 is shown. In this embodiment, a belt breakage detection sensor 31 is arranged at one of two timing belts 27 that connect the motor 26 and the relay shaft 32, and among the two timing belts 27 that connect the relay shaft 32 and the ball screw 22. The belt breakage detection sensor 30 is arranged at one place.
With this configuration, the number of belt breakage detection sensors can be reduced, and when the timing belt 27 is broken, the detection time is delayed compared to the first embodiment, but it is possible to detect the fall prevention of the gas outflow portion 14 due to disconnection at a lower cost. . The belt breakage detection sensors 30 and 31 are fixed on the glow box so that the flag plate 35 operates in a direction perpendicular to the length direction of the timing belt 27.
As shown in FIG. 9, when the direction positions of the belts 27a and 27b of the timing belt 27 are different, the arrangement positions of the belt breakage detection sensors 30 and 31 are set so that the flag plate 35 operates in a direction perpendicular to the respective direction positions. It has changed.
Further, as an example of numerical values of the load and the deflection on these belts, 36.5N and a deflection of about 8.4 mm are set for the belt 27a, and 35.2N and a deflection of about 3.3mm are set for the belt 27b under optimum conditions. Yes.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be used in a vapor phase growth apparatus having a lifting mechanism.

DESCRIPTION OF SYMBOLS 1 MOCVD apparatus 2 Growth chamber 3 Substrate heating mechanism 4 Elevating mechanism 5 Reaction furnace 6 Reaction chamber partition 7 Reaction external space 8 Reaction chamber 9 Purge gas supply pipe 10 Substrate 11 Substrate holding part 12 Rotation transmission part 13 Substrate heater 14 Gas Outflow portion 14a O-ring 15 First gas distribution space 16 First gas introduction port 17 Refrigerant space 17b First gas supply pipe 18 Central plate 18a Plate hole 19 Second gas distribution space 19a Second gas introduction port 20b Second gas supply pipe 21 shaft 22 ball screw 23 brake portion 24 bridging portion 25 connecting portion 26 motor 27 timing belt 27a belt 27b belt 28 belt breakage detection sensor 29 belt breakage detection sensor 30 belt breakage detection sensor 31 belt breakage detection sensor 32 relay shaft 33 light emitting portion 34 Light receiver 35 Flag plate 101 Gas supply source 10 Reaction furnace 103 Growth chamber 104 Gas piping 105 Gas outflow portion 106 Substrate 107 Susceptor 108 Heater 109 Rotating shaft 110 Gas exhaust portion 111 Purge line 112 Exhaust gas treatment device 113 Belt 114 Transmission type optical sensor 115 Screw rod 116 Nut 117 Idler 118 Drive chain 119 Energizing mechanism 120 Shaft body 121 Housing 122 Coil spring 123 Limit switch 124 Position detector

Claims (6)

A gas outflow portion, a plurality of ball screw portions, a shaft portion that moves up and down the gas outflow portion connected to the ball screw portion, a holding mechanism using a timing belt between the ball screw portion and the motor portion, A vapor phase growth apparatus provided with a sensor unit in the vicinity.
The relay shaft is provided between the ball screw portion and the motor portion, and sensor portions are provided in the vicinity of all timing belts between the ball screw portion, the relay shaft, and the relay shaft and the motor portion. Vapor growth equipment.
2. A relay shaft is provided between the ball screw portion and the motor portion, and a sensor portion is provided in the vicinity of any one of the timing belt between the ball screw portion and the relay shaft and between the relay shaft and the motor portion. The vapor phase growth apparatus described.
2. The gas outflow part constitutes a shower head part composed of a plurality of gas pipes.
4. The vapor phase growth apparatus according to 3.
5. The vapor phase growth apparatus according to any one of claims 1 to 4, wherein the ball screw portion includes a brake portion that stops the gas outflow portion from rising.
6. The vapor phase growth apparatus according to claim 1, wherein the ball screw portions are connected to each other via a bridging portion.