JP3070158B2 - Susceptor rotation support structure for thin film vapor phase growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a susceptor support rotating structure used in a thin film vapor phase growth apparatus such as an MOCVD apparatus. In particular, the present invention relates to an improvement in which a susceptor on which a wafer is mounted can be automatically attached and detached, and the susceptor can be revolved and rotated during growth.

[0002]

2. Description of the Related Art In the MOCVD method, an organic metal gas or a hydride gas is introduced into a vacuum chamber, and a thin film of a reaction product is grown on a heated substrate. Gas flows from top to bottom. The substrate is placed on the susceptor, and there are many types of susceptors. There is also a barrel type in which a plurality of substrates are mounted on a vertical inclined surface.
There is also a type in which one substrate is placed on a horizontal plane (branch type). Further, there is a type in which a plurality of substrates (wafers) are placed on a horizontal surface. The present invention is concerned with such improvements. In this case, the susceptor can revolve. If the gas flow and the temperature are different in the circumferential direction, the conditions for forming the thin film are different, so that the film thickness and the film quality are not constant. Thus, the susceptor is rotated about a central axis to increase circumferential uniformity.

Another important point in the MOCVD method is that the substrate can be automatically transferred. The vacuum chamber must not be opened and exposed to the atmosphere to mount the substrate on the susceptor. Productivity may be reduced and impurities may be adsorbed on the chamber walls. In addition, toxic components may be scattered outside. In many cases, the wafer tray is transported by a fork which can move in the horizontal direction and has a forked end. Now, although the susceptor is capable of mounting a plurality of substrates, it is not possible to secure radial uniformity simply by rotating the susceptor around the central axis. Therefore, there has been an increasing demand to rotate the plurality of substrates themselves around the central axis of the substrates. However, since it is inside the chamber in a vacuum at a high temperature, it is not possible to provide many mechanical parts and driving sources.

Japanese Patent Application Laid-Open No. 27226/1984 describes a vapor phase growth apparatus having a rotating substrate as shown in FIGS. FIG. 4 shows a horizontal disk susceptor 41 in which a plurality of stop holes 42 are drilled, bearings 43 are provided around the holes, and a sun gear 44 is installed at the center of the susceptor 41. A plurality of wafer receiving gears 45 are placed on the susceptor. These are geared on the periphery and have a projection 46 in the lower center. Since the projection 46 enters the stop hole 42, the wafer receiving gear 45 can rotate. Since the external teeth of the wafer receiving gear 45 mesh with the sun gear 44, the revolving motor 47
When the sun gear 44 is rotated by the rotation motor 48, the susceptor 41 revolves around its central axis.

Although this apparatus can certainly rotate the wafer 49, it cannot automatically transfer the wafer in a vacuum. This is because the wafer receiving gear cannot be lifted from the side by forks, and it is also difficult to lift only the wafer. The one shown in FIG. 5 supports a plurality of wafers 51 obliquely upward. The engagement between the bevel gears 52 and 53 is used. At the inner end of each susceptor 54 is a bevel gear 52, which meshes with a horizontally fixed bevel gear 53. When the conical susceptor support cone 5 revolves, the wafer 5
1 revolves around the orbit. However, this apparatus cannot transfer a wafer automatically in a vacuum. In order to replace the wafer, the vacuum chamber must be opened and the operator must replace the wafer by hand.

Since the susceptor supporting the wafer is provided with gears and the wafer is rotated by meshing with the fixed gear, the wafer is rotated using the driving force for revolving, so that a new drive mechanism is required. There is an advantage that there is no need to provide. However, gears must be meshed, and the gears cannot be attached or detached due to poor operability such as a fork. Therefore, such a device cannot perform automatic conveyance at all. The present invention solves such a problem, and provides a susceptor support rotating structure that can automatically transfer a wafer (substrate) in a vacuum and that enables the wafer to revolve and revolve.

[0007]

According to the present invention, there is provided a susceptor rotating support structure for a thin film vapor phase growth apparatus, in which a source gas is introduced into a vacuum chamber and a reaction is generated on a substrate placed on a heated susceptor. A susceptor rotation support structure for a thin film vapor phase growth apparatus that grows a thin film of an object, a revolving axis that can rotate around a vertical axis provided in a cylindrical, vertical direction, and an upper end of the revolving axis The support cylinder, which is a cylindrical body having a larger diameter than the cylindrical body, is fixed and supported, and a plurality of disc-shaped insertion holes having a stepped portion into which the susceptor enters from above are cut out and attached to and detached from the upper end of the support cylinder. A tray that can be mounted as possible, a fixed shaft that is provided vertically in the revolving shaft and that does not rotate, a central shaft that is provided directly or indirectly at the upper end of the fixed shaft, and a tray that is almost at the upper end of the central shaft. With sun gear fixed at the same height A plurality of carrier having inclined holes to the distal end is fixed toward the center at the upper end of the support tube,
It is circular, has a concave portion on the upper surface, has a downward projection at the center of the lower surface, has a planetary gear carved around it, is loosely fitted in the insertion hole of the tray, the downward projection is inserted into the inclined hole of the carrier, and the planetary gear is the sun. A plurality of susceptor receiving gears meshed with the gears; and a circular susceptor receiving gear that has a diameter larger than the step portion of the tray insertion hole, supports the substrate on the upper surface, and is placed in the concave portion of the susceptor receiving gear. The susceptor comprises a plurality of susceptors, and the susceptor revolves around its axis when the orbital shaft rotates.

[0008]

The center axis of the susceptor receiving gear is inserted into the inclined hole of the carrier and the carrier rotates together with the revolving shaft, so that the susceptor receiving gear revolves. The susceptor receiving gear has a planetary gear on the side circumference and meshes with a stationary sun gear, so that the susceptor receiving gear rotates around its central axis. Such points are the same as those described above.
However, in the present invention, the tray can be lifted, and when the tray is lifted, the susceptor is lifted by the step portion, so that the automatic transfer of the wafer (substrate) is possible. The susceptor receiving gear does not lift, only the susceptor lifts away from it with the tray. For this reason, the meshing portion between the gears does not come off or mesh with each other. Further, since the gears do not come off, there is no need to reinsert the gears with the center axis aligned.

If the tray is lifted by a forked transporting device such as a fork, only the tray, the susceptor and the substrate are separated from other components. Of course, when the tray is placed on the rotary support structure, the phase of the tray must match the phase of the rotating part of the support mechanism. Techniques for stopping the rotating shaft at a fixed position have already been used. This is done, for example, by fixing a ring provided with several cuts around the rotation axis and providing a stop member which moves forward and backward with respect to the cut. The rotation axis is stopped at a rough stop position by controlling the rotation angle of the motor. In this state, when the stop member is advanced and pushed into the cut, the rotary shaft slightly moves and stops at a certain position.

[0010]

FIG. 1 is a longitudinal sectional view of a susceptor rotation support structure according to an embodiment of the present invention. FIG. 2 is a slightly reduced plan view. The mechanism for susceptor rotation support has a disc-shaped tray 1 at the uppermost position. The tray 1 is detachably provided at the upper end of a support cylinder 2 which is a wide cylindrical member. The support cylinder 2 is fixed to the upper flange 4 of the revolving shaft 3 at its lower end.

The revolving shaft 3 is also a cylindrical body, which is rotatably supported below by a suitable bearing and is rotatable by a driving mechanism (not shown). The revolving shaft 3, the upper flange portion 4, the support cylinder 2, and the tray 1 rotate around the central axis as a unit. A fixed shaft 5 is provided inside the revolution shaft 3. A fixed disk 6 is fixed to the upper end of the fixed shaft 5. A plurality of fixed support bars 7 are provided upright on the fixed disk 6 in the vertical direction. A disk-shaped receiving plate 8 is provided at the upper end of the fixed support bar 7.
Has been fixed. A plurality of annular reflectors 9 are stacked on the receiving plate 8. This is a thin plate of a heat-resistant metal such as Mo or Ta. The center axis 10 is fixed upward at the center of the receiving plate 8. This can also be made of a high melting point metal such as Mo. Sun gear 11 on center axis 10
Is fixed. The sun gear 11 does not rotate because the lower cylindrical portion 12 is fixed to the central shaft 10.

The tray 1 has an outer edge 13 which is flat disk-shaped but has a shape hanging downward on the outside. The outer edge 13 surrounds the periphery of the upper end of the support cylinder 2. Tray 1
Is not fixed to the support cylinder 2 and is detachable. Since the outer edge 13 fits into the support cylinder 2, the tray 1 does not move left and right in the state of being worn. The center 14 of the tray 1 is thin because a recess 15 for receiving the sun gear 11 is formed therein. The back surface of the tray 1 is supported on the upper end 16 of the support tube 2, and a ring-shaped step 17 protruding inward is formed on the inner peripheral surface near the tray 1.

A carrier ring 19 having a plurality of carriers 18 extending inward is fixed to the step 17. The carrier ring can be made, for example, of Mo.
It has carriers 18 equal to the number of wafers. In order to show this part in detail, the plan view of FIG. 2 also shows a state where a part of the tray is cut out and the susceptor is removed. A circular insertion hole 20 is formed in the tray 1 equal to the number of wafers to be processed. It has a step 21 at an intermediate height.
The susceptor 22 and the susceptor receiving gear 23 are fitted into the insertion hole 20 of the tray 1 from above.

The susceptor receiving gear 23 has on its upper surface a recess 24 into which the susceptor 22 fits exactly. A planetary gear 25 is engraved on the side circumference, and this is the sun gear 11 at the center.
Are engaged. At the center of the lower surface of the susceptor receiving gear 23, a downwardly tapered projection 26 is formed. The projection 26 is inserted through a slide cylinder 27 into an inclined hole 28 formed at the tip of the carrier 18. That is, the susceptor receiving gear 23 can rotate around the central axis of the inclined hole 28. Planetary gear 25 on the side circumference of susceptor receiving gear 23
Does not contact the inner surface of the insertion hole 20 of the tray 1. This is because the outer diameter is smaller than the inner diameter of the step portion 21. The carrier ring 19 can be made of Mo.

The susceptor 22 is a circular thin container. On the upper surface there is a shallow recess 30 in which the wafer 29 is to be placed. The lower surface is supported by the recess 24 of the susceptor receiving gear 23. The peripheral flange portion 31 is wider than the susceptor receiving gear 23, and the step portion 21 is located in the middle of the insertion hole 20 of the tray 1.
Has a wider diameter. Therefore, when the tray 1 is lifted, the susceptor 22 is lifted by being caught on the step portion 21. The above is the mechanism for supporting the rotation of the susceptor. In this embodiment, since the susceptor is heated by resistance, a carbon heater is built in the support cylinder 2. Of course, the present invention is not limited to the resistance heating method, but can be applied to an induction heating method in which the susceptor is heated by an external induction coil. In this case, no heater exists in the support cylinder.

Two electrode rods 32 are provided vertically inside the fixed shaft 5. These are the horizontal parts 3 that extend radially at the top
3. It is deformed into a vertical rising portion 34. This is also made of, for example, a Mo bar. A spiral carbon resistor 36 is attached to the vertical rising portion 34 via an electrode portion 35. The carbon resistor 36 is formed integrally with the electrode section 35. The shape and distribution of the spiral resistor 36 are appropriately determined so that the temperature distribution in the plane of the wafer becomes uniform. The current flows from one electrode rod 32 to one electrode rod 35
Through the carbon resistor to the electrode part 35 and the electrode rod 32 on the opposite side.

Joule heat is generated from the carbon resistor and is radiated to heat the susceptor 22. The reflector 9 reflects the radiation directed downward and returns the radiation toward the susceptor 22. The operation of the above configuration will be described. The revolving shaft 3 is rotated by the force of a motor (not shown) provided below. The angular velocity of this revolution and Ω _1. The support cylinder 2 and the tray 1 rotate at the same angular velocity. Tray 1
When the carrier rotates, the carrier 18 also rotates at the same speed. Therefore, the susceptor 22 and the susceptor receiving gear 23 also rotate at the same angular velocity.

However, since the planetary gear 25 on the side circumference of the susceptor receiving gear 23 meshes with the stationary sun gear 11, the susceptor receiving gear 23 also rotates in the same direction as the revolving direction. The angular velocity Ω ₂ of the rotation is Ω ₂ = (S + P) Ω ₁ / P (1) Here, S is the number of teeth of the sun gear, and P is the number of teeth of the planetary gear. Ω ₂ is the rotational angular velocity for the laboratory system.
Relative angular speed Ω _{3 of} susceptor receiving gear relative to tray
Is obtained, this results in Ω ₃ = Ω ₂ −Ω ₁ = SΩ ₁ / P (2) Although the relative rotation angular velocity is smaller than the revolution angular velocity Ω ₁ (if S / P <1), it still rotates. Since the wafer is rotated to make the temperature distribution and the gas flow distribution the same, it is not necessary to rotate too fast.

The most important point in the present invention is that the wafer can be automatically transferred. Outer edge 13 of tray 1
Is inserted around the support cylinder 2 and the whole of the support cylinder 2, the fixed shaft 5, the revolving shaft 3 and the like are lowered. Then tray 1 rides on the fork,
Separated from other parts. The susceptor 22 and the wafer 29 are left on the tray 1 by the step 21 of the tray 1. The susceptor receiving gear 23 descends. FIG. 3 is a sectional view showing only the raised tray portion. Only such tray 1, susceptor 22, and wafer 29 are taken up. It is conveyed by a fork in this state. The opposite is true when installing a tray, but you must position it. That is, when the revolving shaft 3 is stopped, it always stops at the same phase. This has already been mentioned. Rough positioning is performed by appropriately defining the number of rotations of the motor when stopped, and strict positioning is performed by mechanical means.

[0021]

According to the present invention, the wafers can be rotated and revolved in the thin film vapor phase growth apparatus, so that the temperature distribution and the gas flow distribution are uniform between the wafers and within the plane of one wafer. Therefore, a thin film having a constant thickness and quality can be grown. Further, a tray on which wafers are placed can be automatically attached and detached, so that automatic transfer can be performed. Since the wafer can be replaced without breaking the vacuum, the productivity is improved and the quality is constant.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a susceptor rotation support structure of a thin film vapor phase growth apparatus according to an embodiment of the present invention.

FIG. 2 is a partially cutaway plan view of the same.

FIG. 3 is a vertical sectional view of a tray component when only the tray is lifted.

FIG. 4 is a schematic sectional view of a vapor phase growth apparatus according to a conventional example.

FIG. 5 is a schematic sectional view of a vapor phase growth apparatus according to another conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tray 2 support cylinder 3 revolving shaft 4 upper flange 5 fixed shaft 6 fixed disk 7 fixed support rod 8 receiving plate 9 reflector 10 central axis 11 sun gear 13 outer edge of tray 18 carrier 19 carrier ring 20 insertion hole 21 step 22 Susceptor 23 Susceptor receiving gear 25 Planetary gear 26 Projection 28 Inclined hole 29 Wafer 32 Electrode rod 35 Electrode part 36 Resistance acceleration heater

Claims (2)

(57) [Claims] 1. A susceptor rotating support structure of a thin film vapor phase growth apparatus wherein a source gas is introduced into a vacuum chamber and a thin film of a reaction product is grown on a substrate placed on a heated susceptor. A revolving shaft capable of rotating around a vertical axis provided in a cylindrical shape in a vertical direction, a support cylinder being a cylindrical body having a larger diameter fixedly supported by an upper end of the revolving shaft, and a circle. A plate-shaped tray with a plurality of notched insertion holes with steps to allow the susceptor to enter from above, and a tray that can be detachably mounted on the upper end of the support cylinder, and provided vertically through the inside of the revolving shaft A fixed shaft that does not rotate, a central shaft provided directly or indirectly at the upper end of the fixed shaft, a sun gear fixed at substantially the same height as the tray at the upper end of the central shaft, and a center at the upper end of the support cylinder. It is fixed to the direction and has an inclined hole at the tip A plurality of carriers, circular, having a concave portion on the upper surface, having a downward projection at the center of the lower surface, having a planetary gear carved around the periphery, being loosely fitted into the insertion hole of the tray, and having the downward projection inserted into the inclined hole of the carrier. A plurality of susceptor receiving gears in which the planetary gear meshes with the sun gear, and are circular and have a diameter larger than the step portion of the tray insertion hole, support the substrate on the upper surface, and have a concave portion of the susceptor receiving gear. A susceptor rotation support structure for a thin film vapor phase growth apparatus, comprising a plurality of susceptors to be mounted, wherein the susceptor revolves around its axis of rotation when the orbital axis rotates. 2. A susceptor rotating support structure of a thin film vapor phase growth apparatus for introducing a raw material gas into a vacuum chamber and growing a thin film of a reaction product on a substrate placed on a heated susceptor. A revolving shaft capable of rotating around a vertical axis provided in a cylindrical shape in a vertical direction, a support cylinder being a cylindrical body having a larger diameter fixedly supported by an upper end of the revolving shaft, and a circle. A plate-shaped tray with a plurality of notched insertion holes with steps to allow the susceptor to enter from above, and a tray that can be detachably mounted on the upper end of the support cylinder, and provided vertically through the inside of the revolving shaft Fixed shaft that does not rotate, a horizontal receiving plate provided at the upper end of the fixed shaft, a plurality of disk-shaped reflectors placed on the peripheral edge of the upper surface of the receiving plate, and a reflector and a susceptor inside the support cylinder. A resistance heating heater provided between An electrode rod provided inside the revolving shaft for supporting the anti-heating heater and supplying current thereto, a center shaft fixed upward in the center of the receiving plate, and a tray at an upper end of the center shaft. A sun gear fixed at the same height,
A plurality of carriers that are fixed toward the center at the upper end of the support cylinder and have inclined holes at the tip, and a planetary gear that is circular, has a concave portion on the upper surface, has a downward projection on the lower surface, and has a downward protruding portion. A plurality of susceptor receiving gears, which are loosely fitted into the insertion holes of the tray and into which the downward projections are inserted into the inclined holes of the carrier so that the planetary gears mesh with the sun gears; The susceptor comprises a plurality of susceptors having a diameter larger than that supporting the substrate on the upper surface and to be placed in the concave portion of the susceptor receiving gear, wherein the susceptor revolves around itself by rotation of the revolving shaft. Susceptor rotation support structure of a thin film vapor phase growth apparatus.