JPH08264461A - Apparatus for vapor deposition - Google Patents

Abstract

PURPOSE: To eliminate variations of film quality characteristics between semiconductor wafers based on the different cross sections of reaction gas flow passages around a reactor by correcting displacement of the center of a susceptor on the basis of a distance between the center of the top part of the reactor and a central axis of the reactor. CONSTITUTION: Picture image pick-up means 71 is fixed outside the top of a reactor 1 to take the top part 21 of a susceptor 2, in the field of view and picture image processing means 72 receives an output of the picture image pick-up means 71, calculates a distance between the center of the cap-shaped top part 21 and a central axis of the reactor 1 and outputs the result as a display or a signal to the outside. In the calculation, sections in parallel to X and Y axes are evaluated from an image of the cap-shaped top part 21, and a point where longest sections intersect is taken as the center of the cap-shaped top part 21 to evaluate displacement of the reactor 1 from the central axis. A position displacement of the susceptor 2 is detected by the picture image pick-up means 71 and the picture image processing means 72, and on the basis of the position displacement, the position displacement of the susceptor 2 is eliminated with the aid of push type position displacement correction means 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vapor phase growth apparatus. In particular, it relates to an improvement that enables the center of the susceptor to coincide with the central axis of the reactor in a barrel type vapor phase growth apparatus.

[0002]

2. Description of the Related Art F used for satellite broadcasting and mobile phones
Epitaxial wafers used as materials for ET and HEMT are
A semiconductor wafer is supported on a susceptor in a reactor of a vapor phase growth apparatus, and arsine (AsH ₃ ) and trimethylgallium (TMG) are placed in the reactor while the susceptor is heated to a high temperature.
a), a raw material gas such as trimethylaluminum (TMAl) is caused to flow together with a carrier gas made of hydrogen to epitaxially grow a semiconductor layer on a semiconductor wafer.

FIG. 6 is a side sectional view of a conventional vapor phase growth apparatus.
In FIG. 4, reference numeral 1 denotes a reactor, which is provided with a gas supply port 11 and a vacuum suction port 13 in the upper part of the bell-shaped reactor 1, and a gas exhaust port 12 in the lower part. A susceptor 2 is composed of a cap-shaped top portion 21, a polygonal pyramid body portion 22 formed of carbon, and a support shaft 23. Three
Is a chamber, which is provided below the reactor 1 and is provided with a gate valve 31 at a position in contact with the reactor 1.
A chamber window 32 is provided on the body. Reference numeral 4 denotes a rotary shaft, which is rotatably supported on the bottom of the chamber 3 and is vertically movable, and is driven by a driving unit such as an electric motor (not shown). 41 is a fastening part, and after inserting the lower end of the support shaft 23 into the cylindrical recess provided in the upper end of the rotating shaft 4,
It is screwed on. Reference numeral 5 is a heating means such as a high-frequency coil wound around the outside of the body of the reactor 1, and 6 is a workpiece such as a semiconductor wafer attached to the polygonal pyramid body 22 of the susceptor 2.

When a high-frequency current is applied to the high-frequency coil 5, the carbon of the polygonal pyramid body 22 is induction-heated to heat the semiconductor wafer 6 mounted on the polygonal pyramid body 22. A reaction gas composed of a mixed gas of a raw material gas and a carrier gas is supplied from the gas supply port 11 into the reactor 1,
It flows along the surface of the semiconductor wafer 6, passes through the upper passage of the current plate 42, and is discharged through the gas exhaust port 12. Then, during this time, the reaction gas is thermally decomposed to form an epitaxial semiconductor layer on the heated semiconductor wafer 6.

When the epitaxial semiconductor layer is completed, the rotating shaft 4 is pulled down, and when the susceptor 2 is lowered into the chamber 3, the gate valve 31 is driven leftward to shut off the reactor 1 from the chamber 3. To do. Then, after the inside of the chamber 3 is set to the atmospheric pressure, the chamber window 31 is opened and the epitaxial semiconductor wafer is taken out. next,
After mounting a new semiconductor wafer on the polygonal pyramid body 22,
The chamber 3 is evacuated, the gate valve 31 is driven to the right to open to the position shown in the figure, and the rotary shaft 4 is driven upward to raise it to the position shown in the figure.

The characteristics required for the epitaxial semiconductor wafer manufactured in this manner include purity and uniform film quality characteristics. Regarding the purity, the level has risen considerably due to improvements in the characteristics of piping materials, the performance of equipment used, and the purification of raw materials. Regarding the uniform film quality characteristics, the in-plane uniformity of the semiconductor wafer is greatly improved by rotating the semiconductor wafer itself.

[0007]

However, regarding the uniform film quality characteristics between a plurality of semiconductor wafers simultaneously manufactured by using the vapor phase growth apparatus, the temperature difference between the semiconductor wafers during film formation and the semiconductor Variations occur due to the difference in the flow of the reaction gas between the wafers. The temperature difference between the semiconductor wafers is caused by the increase in the rotation speed of the rotating shaft 4 and the susceptor 2
By equalizing the carbon resistance of the polygonal pyramid body 22 of
It is possible to reduce the temperature difference. Further, it is possible to reduce the temperature difference not by induction heating but by heating with a heater using a plurality of zone heaters.
However, the difference in reaction gas flow between semiconductor wafers has not been improved so far. The rotating shaft 4 is made of metal, but the maximum around the susceptor 1 is about 800.
Quartz glass is used for the support shaft 23 because of the high temperature of ° C. Therefore, in the fastening portion 41, the fastening is loosened due to the difference in thermal expansion at high temperature, and the susceptor 1 is tilted. As a result, although the rotating shaft 4 is accurately aligned with the central axis of the reactor 1, the gap between the reactor 1 and the susceptor 2, which is the flow path of the reaction gas, is not uniform around the periphery, and in a narrow place. The flow velocity of the reaction gas becomes fast, and the flow velocity of the reaction gas becomes slow in a wide place. The difference in the flow of the reaction gas impairs the uniformity of the film quality characteristics between the semiconductor wafers.

An object of the present invention is to solve this problem, and the gap between the reactor 1 and the susceptor 2 can be made uniform over the periphery thereof, and the flow path of the reaction gas around the reactor 1 can be made. An object of the present invention is to provide a vapor phase growth apparatus that does not cause variations in film quality characteristics between semiconductor wafers due to differences in cross-sectional area.

[0009]

The above object can be achieved by any of the following means.

The first means is installed in the reactor (1), is driven to rotate about the central axis of the reactor (1), heats the polygonal pyramidal susceptor (2), and the susceptor (2) is heated. In a vapor deposition apparatus for forming a film on a wafer attached to a wafer, an image pickup means (71) is installed outside the top of the reactor (1) and monitors the top (21) of the susceptor (2). An image processing means (7) for receiving the output of the image capturing means (71) and calculating the distance between the center of the top portion (21) and the central axis of the reactor (1).
2) and a vapor phase growth apparatus having a pressing type positional deviation correcting means (8) for correcting positional deviation of the center of the susceptor (2) based on the distance signal calculated by the image processing means (72). Is.

The second means is installed in the reactor (1), is driven to rotate about the central axis of the reactor (1), heats the polygonal pyramidal susceptor (2), and the susceptor (2) is heated. In a vapor phase growth apparatus for forming a film on a wafer attached to a wafer, the wafer is installed at a plurality of locations on an outer periphery of an upper side surface of the reactor (1), and a laser beam is applied to a top portion (21) of the susceptor (2). A plurality of displacement detection means (75) for detecting reflected light and measuring the distance to the top, and outputs of the plurality of displacement detection means (75),
Rotational position calculation means (76) for calculating the distance between the center of the top portion (21) and the central axis of the reactor (1),
This is a vapor phase growth apparatus having a pressing type positional deviation correcting means (8) for correcting the positional deviation of the center of the susceptor (2) based on the distance signal calculated by the rotational position calculating means (76).

Then, the top portion (21) calculated by the image processing means (72) or the rotational position calculation means (76).
A control device is provided for making the distance between the center of the reactor and the central axis of the reactor (1) to 0 by negative feedback control, and the output of this control device provides the pressing-type positional deviation correcting means (8).
Is convenient because it is automatically centered.

[0013]

The first means of the vapor phase growth apparatus according to the present invention has the image pickup means 71 and the image processing means 72,
The image of the top portion 21 of the susceptor 2 captured by the image capturing means 71 is image-processed by the image processing means 72 to obtain the distance between the center of the top portion and the central axis of the reactor 1. In the second means, a plurality of The displacement position detecting means 75 and the rotational position calculating means 76 are provided. Based on the distances detected by the respective displacement detecting means 75 to the top portion 21, the rotational position calculating means 76 determines the center of the top portion 21 and the axial center of the reactor 1. Is calculating the distance to. Both the first means and the second means are the image processing means 72 or the rotational position calculating means 7.
It has a pressing type position shift correcting means 8 which corrects the position shift of the center of the susceptor 2 based on the distance signal calculated by 6. Therefore, even if the fastening portion 41 is loosened and the susceptor 2 is eccentric to the central axis of the reactor 1 or swings, the deviation of the susceptor 1 from the central axis of the reactor 1 is detected. It is possible to correct the movement of the susceptor 1 by the pressing-type positional deviation correcting means 8 so that the distance between the center of the top 21 and the central axis of the reactor 1 can be made zero.

It should be noted that any of the means uses an optical method and is installed outside the reactor 1 so that it does not impede the flow of the reaction gas and is installed above the reactor 1. Even if the reaction gas adheres to the inner wall of the reactor 1, the adhering portion is formed of carbon and is the lower portion of the reactor 1 corresponding to the polygonal pyramid body 22 having a high temperature. Distance measurement is not impeded.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The vapor phase growth apparatus according to the two embodiments of the present invention will be described in more detail below with reference to the drawings.

First Embodiment (corresponding to claim 1) See FIG. 1. FIG. 1 is a side sectional view of a vapor phase growth apparatus according to the first embodiment of the present invention. The following description will be given with an emphasis on the points different from the conventional example. In FIG. 1, 1 is a reactor whose main part is made of a transparent material such as quartz glass in this example, and a gas supply port 11 is provided at a position avoiding the top of the reactor 1. Reference numeral 71 denotes an image pickup means fixed to the outside of the top of the reactor 1, and at least the top 21 of the susceptor 2 (in this example, a hat-shaped top) is housed in the visual field. 72
Is an image processing means, which receives the output of the image capturing means 71, calculates the distance between the center of the hat-shaped top portion 21 and the central axis of the reactor 1, and outputs the result as a display or a signal to the outside. The calculation method is X from the image of the hat-shaped top 21.
A method of obtaining a chord parallel to the axis and the Y-axis, using the point where the longest chord intersects as the center of the hat-shaped top 21, and determining the deviation from the central axis of the reactor 1, mark at the center of the apex of the hat-shaped top 21. Is added and the deviation from the center axis of the reactor 1 is detected, or the center of gravity of the image of the cap-shaped top 21 is obtained by image analysis, and the center of gravity is used as the center of the center of the reactor 1. There are various methods such as a method for obtaining the deviation, and any method may be used.

The center of the hat-shaped top portion 21 is used to find the center of the susceptor 2. However, since the hat-shaped top portion 21 is farthest from the fastening portion 41, the detection sensitivity of the positional deviation is increased, and the susceptor 1 is detected. The positioning accuracy of can be improved.

Reference numeral 8 is a pressing type positional deviation correcting means, which is a heat resistant bearing 81 made of ceramic or the like having an inner ring fitted to the upper end of the quartz support shaft 23 of the susceptor 2, and a reactor corresponding to the heat resistant bearing 81. It is composed of a plurality of centering mechanisms 82 attached to the body portion 1 so that the angles formed by adjacent ones are 180 ° or less. The outer ring of the heat resistant bearing 81 is tapered. That is,
The lower end circle is larger than the upper end circle of the outer ring.

FIG. 2 is a side sectional view of the centering mechanism 82. Centering mechanism 8
2 is a fixed flange 82a fixed to the reactor 1,
A seal flange 82b, a metal bellows 82c having one end connected to a fixed flange 82a and the other end connected to a seal flange 82b, and a centering rod 82d having a handle penetrating the fixed flange 82a and the seal flange 82b.
And the contactor 82 fixed to the tip of the centering rod 82d.
e and. The material of the contact 82e that comes into contact with the outer ring of the heat-resistant bearing 81 may be metal, but heat-resistant resin such as polyimide is preferable. The fixing flange 82a and the centering rod 82d are threaded, and
When 2d is rotated, the centering rod 82d can be moved in and out in the radial direction of the reactor 1. A portion where the centering rod 82d penetrates the seal flange 82b is sealed by a magnetic seal or an O-ring seal. The fixed flange 82a is provided with a ventilation port 82f that connects the interior of the reactor 1 to the interior of the metal bellows 82c, so that the centering rod 82d can be smoothly rotated.

Referring again to FIG. 1, the fastening portion 41 has a plurality of spring-loaded push screws in which a spiral spring and a steel ball are loaded in a cylindrical recess provided at the tip of the screw in the circumferential direction of the fastening portion 41. It is used to press and support the lower end of the support shaft 23. Therefore, the fastening portion 41 becomes hot,
Even if the backlash due to the difference in thermal expansion becomes large, it is pressed and supported by the spring to prevent the inclination of the susceptor 2 to some extent.

In the vapor phase growth apparatus according to this embodiment, the image pickup means 71 and the image processing means 72 detect the positional deviation of the susceptor 2, and the pressing type positional deviation correcting means 8 detects the positional deviation based on the positional deviation. The position shift of 2 is eliminated. Further, once positioned, a new semiconductor wafer is mounted by the fastening portion 41 using a push screw with a spring and the heat-resistant bearing 81 of the tapered outer ring, and when the susceptor 2 is raised into the reactor 1, the heat-resistant The flexible bearing 81 and the centering mechanism 82 can be smoothly positioned at the correct position without colliding with each other.

See FIG. 3. FIG. 3 compares variations in film quality characteristics between semiconductor wafers manufactured by using the vapor phase growth apparatus according to the first embodiment of the present invention and the conventional vapor phase growth apparatus. The horizontal axis represents the number of times of epitaxial growth and the vertical axis represents the variation. In FIG. 3, the circle marks show the case of this embodiment, and the triangle marks show the case of the conventional example. From FIG. 3, the variation between semiconductor wafers when epitaxial growth is performed using the vapor phase growth apparatus according to the first embodiment of the present invention,
It is clearly seen that the improvement is remarkably improved as compared with the case where the epitaxial growth is performed by using the vapor phase growth apparatus according to the conventional technique.

Second Embodiment (corresponding to claim 2) See FIG. 4. FIG. 4 is a side sectional view of a vapor phase growth apparatus according to a second embodiment of the present invention. Hereinafter, differences from the first embodiment will be mainly described. In FIG. 4, reference numeral 75 denotes a laser light type displacement detecting means. A plurality of displacement detecting means 75 are provided on the outer periphery of the upper side surface of the reactor 1 so that each of the plurality of displacement detecting means 75 emits a narrowed laser light toward the hat-shaped top portion 21. It is installed in the place. Then, each displacement detection means 75 receives the reflected light of the bright spot of the hat-shaped top portion 21 generated by the laser light emitted by itself at a position slightly apart from the position where the laser light is emitted, and the emitted light and the reflected light are received. The angle of the top of the hat-shaped top 2
Distances up to 1 can be measured. Reference numeral 76 denotes a rotational position calculation means, which receives a signal corresponding to the distance from each of the plurality of displacement detection means 75 to the hat-shaped top portion 21 and calculates the distance between the center of the hat-shaped top portion 21 and the central axis of the reactor 1. , The calculation result can be displayed or output.

The pressing type positional deviation correcting means 8 in the vapor phase growth apparatus according to the second embodiment has an angle of 180 degrees between adjacent ones in the body of the reactor 1 corresponding to the upper end of the quartz support shaft 23 of the susceptor 2. It is a centering mechanism 83 with a plurality of rollers attached so as to be below.

Referring to FIG. 5, in the centering mechanism 83 with rollers, in the centering mechanism 82 of the first embodiment, instead of the contact 82e fixed to the tip of the centering rod 82d, a contact portion 83b having a roller 83a. There is. Therefore, the roller 83a moves integrally with the centering rod 82d toward the center of the reactor 1, but is held rotatably with respect to the contact portion 83b. Since the rod 83c extending from the contact portion 83b penetrates the through hole 83d provided in the fixed flange 82a, the contact portion 83b does not rotate with respect to the fixed flange 82a even when the centering rod 82d is rotated. Instead, the roller shaft is always kept in the vertical direction and moved in the front-back direction toward the center of the reactor 1. When the centering mechanism with a roller 83 is used for centering, the support shaft 23 rotates and the roller 83a of the contact portion 83b rotates, so that the rotating susceptor 2 can be held smoothly.

The variation between semiconductor wafers when a semiconductor layer is epitaxially grown using the vapor phase growth apparatus according to the second embodiment is the same as when the vapor phase growth apparatus according to the first embodiment is used. , Which was sufficiently lower than the conventional value.

The first and second embodiments are modified to combine the image pickup means 71, the image processing means 72 and the centering mechanism with roller 83, or the displacement detecting means 75 and the rotational position calculating means. 76 and heat resistant bearing 81
Needless to say, a combination of the centering mechanism 82 and the centering mechanism 82 may be used.

Further, a control device is installed in each of the above-described first and second embodiments, and the cap-like top portion 21 is provided.
It is also possible to negatively feed back the distance between the center of the reactor and the central axis of the reactor 1 so as to automatically control and drive the pressing-type positional deviation correcting means 8 (claims 3 and 4). The control device is
It is composed of a negative feedback amplifier and a rotary drive mechanism driven by the output of the negative feedback amplifier. Therefore, the image processing means 7
2 or output the output signal from the rotational position calculation means 76 and feed it back negatively to the negative feedback amplifier, and rotate the centering rod 82d of the pressing type position deviation correcting means 8 by the rotation drive mechanism.
Centering is done automatically.

[0029]

As described above, in the vapor phase growth apparatus according to the present invention, the optical method is used by the image pickup means and the image processing means, or by the displacement detecting means and the rotational position calculating means. Then, the susceptor is monitored from the outer upper part of the reactor, preferably the transparent reactor, and how the center of the susceptor deviates from the central axis of the reactor is calculated. Then, the pressure type displacement correction means of the susceptor is used to perform centering so that the displacement becomes zero, whereby the flow velocity distribution of the reaction gas flowing through the reactor can be made uniform. Therefore, it is possible to reduce variations in film quality characteristics between semiconductor wafers manufactured by using the vapor phase growth apparatus according to the present invention, and it is possible to manufacture a high-quality epitaxial semiconductor wafer.

[Brief description of drawings]

FIG. 1 is a side sectional view of a vapor phase growth apparatus according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of the centering mechanism of the vapor phase growth apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram showing variations in film quality characteristics between semiconductor wafers manufactured using the vapor phase growth apparatus according to the first embodiment of the present invention.

FIG. 4 is a side sectional view of a vapor phase growth apparatus according to a second embodiment of the present invention.

FIG. 5 is a side sectional view of a centering mechanism with rollers of a vapor phase growth apparatus according to a second embodiment of the present invention.

FIG. 6 is a side sectional view of a conventional vapor phase growth apparatus.

[Explanation of symbols]

 1 Reactor 11 Gas Supply Port 12 Gas Exhaust Port 13 Vacuum Outlet 2 Susceptor 21 Hat Top 22 Polygonal Pyramidal Body 23 Support Shaft 3 Chamber 31 Gate Valve 32 Chamber Window 4 Rotation Shaft 41 Fastening Section 42 Rectifier 5 High Frequency Coil 6 Workpiece such as semiconductor wafer 71 Image capturing means 72 Image processing means 75 Displacement detecting means 76 Rotation position calculating means 8 Pressing type position shift correcting means 81 Thermal bearing 82 Centering mechanism main body 82a Fixed flange 82b Seal flange 82c Bellows 82d Core Outlet rod 82e Contactor 82f Vent hole 83 Centering mechanism main body with roller 83a Roller 83b Contact portion 83c Rod 83d extending from the contact portion 83b Through hole

Claims (4)

[Claims] 1. A reactor (1) is installed in the reactor (1), is driven to rotate about a central axis of the reactor (1), heats a polygonal pyramidal susceptor (2), and is attached to the susceptor (2). In a vapor phase growth apparatus for forming a film on a wafer, an image pickup means (7) installed outside the top of the reactor (1) and monitoring the top (21) of the susceptor (2).
1) and the output of the image pickup means (71),
Image processing means (72) for calculating the distance between the center of 1) and the central axis of the reactor (1), and the center of the susceptor (2) based on the distance signal calculated by the image processing means (72). And a pressure-type positional deviation correcting means (8) for correcting the positional deviation of the vapor phase growth apparatus. 2. The reactor (1) is installed in the reactor (1), is driven to rotate about the central axis of the reactor (1), heats a polygonal pyramidal susceptor (2), and is attached to the susceptor (2). In a vapor phase growth apparatus for forming a film on a wafer, the apparatus is installed at a plurality of locations on an outer periphery of an upper side surface of the reactor (1), irradiates laser light onto a top portion (21) of the susceptor (2), and detects reflected light. A plurality of displacement detecting means (75) for measuring the distance to the top, and the outputs of the plurality of displacement detecting means (75),
A rotational position calculation means (76) for calculating a distance between the center of the top portion (21) and the central axis of the reactor (1), and the susceptor based on the distance signal calculated by the rotational position calculation means (76). A vapor phase growth apparatus comprising: a press type positional deviation correcting means (8) for correcting the central positional deviation of (2). 3. A control device for reducing the distance between the center of the top part (21) and the central axis of the reactor (1) calculated by the image processing means (72) to zero by negative feedback control. 2. The vapor phase growth apparatus according to claim 1, wherein the pressing-type positional deviation correcting means (8) is driven by the output of the above. 4. A control device for reducing the distance between the center of the apex (21) and the central axis of the reactor (1) calculated by the rotational position calculating means (76) to zero by negative feedback control. The vapor phase growth apparatus according to claim 2, wherein the pressing type positional deviation correcting means (8) is driven by the output of the apparatus.