JP3911518B2 - Susceptor for vapor phase growth apparatus and vapor phase growth method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an improvement of a susceptor used in a single-wafer type vapor phase growth apparatus. The peripheral end portion of a counterbore portion formed as a recess in the susceptor is formed as an inclined surface, and this portion is in contact with the outer peripheral portion of the back surface of a wafer. The present invention relates to a susceptor for a vapor phase growth apparatus and a vapor phase growth method that can prevent slippage of a wafer on the susceptor and that can reduce slip and contamination because there is no abnormal protrusion on the susceptor surface.
[0002]
[Prior art]
In order to grow an epitaxial film on a semiconductor wafer, vapor phase growth apparatuses having various structures are generally used depending on the heating method and the difference in the shape of the susceptor. Conventionally, vertical vapor phase growth apparatuses that heat a susceptor on a circular flat plate from the lower side and barrel type vapor phase growth apparatuses that heat a barrel-shaped susceptor with a side lamp are frequently used due to productivity problems. I came.
[0003]
However, at present, the quality required for epitaxial films is becoming stricter year by year, and there is a tendency that conventional vertical type or barrel type vapor phase growth apparatuses cannot be used. Recently, single wafer type vapor phase growth apparatuses have been attracting attention. Yes.
In general, as shown in FIG. 2, a horizontal single wafer type vapor phase growth apparatus includes a quartz passage-shaped chamber 1 and a semiconductor wafer 3 on a disk-shaped susceptor 2 in which SiC is coated on a graphite base material. And heated by lamps 4 arranged on both front and back surfaces of the susceptor 2 to introduce various source gases into the chamber 1 from the nozzle portion 5 at the left end in the figure.
[0004]
In a vapor phase growth apparatus that performs epitaxial growth using this disk-shaped susceptor, the problem is that when a wafer is transferred onto the susceptor, a Bernoulli chuck is used to drop the wafer onto the susceptor from a height of about 10 mm. Therefore, the gas between the wafer and the susceptor does not escape quickly, the wafer slides on the susceptor, and one end of the wafer comes into contact with the counterbore side wall of the susceptor.
[0005]
When epitaxial growth is performed on a semiconductor wafer, it is necessary to make the temperature distribution of the semiconductor wafer uniform during the process in order to suppress the occurrence of slip defects. However, as described above, if the wafer slides on the susceptor and epitaxial growth is performed while the wafer is in contact with the side wall of the susceptor, the temperature distribution in the wafer surface greatly changes at the contact portion, which causes the occurrence of slipping. Yield decreases.
Further, when the wafer is in contact with the susceptor, the temperature distribution is not uniform on the wafer even during epitaxial growth, so that the specific resistance distribution of the epitaxial film is deteriorated and the uniformity of the film is deteriorated.
[0006]
[Problems to be solved by the invention]
Therefore, conventionally, in order to prevent the wafer from slipping on the surface of the susceptor, as shown in FIG. 3A, the so-called counterbore portion 2a, which is a shallow recess for placing the wafer of the susceptor 2, is a mesh called knurling. There are carved shallow narrow grooves. Therefore, as shown in FIG. 3B, a large number of convex portions are formed on the susceptor surface, that is, when the surface of the mounting surface is enlarged, it has a continuous shape such as the apex of the quadrangular pyramid. These convex portions are in contact with the back surface of the wafer.
[0007]
Although the shape of the convex portion shown in FIG. 3B is shown as a flat surface here, abnormal protrusions called bumps are likely to occur at the tip of the convex portion due to processing problems. It may be a cause of generation or a scratch during wafer transfer. If the convex portion on the surface of the susceptor is missing in the opposite direction to the bump, the portion becomes a pinhole and causes contamination or the like on the wafer.
Conventionally, the knurled shape of the counterbore portion has been changed in order to solve the problem of the slip defect caused by the slippage of the wafer, but this cannot prevent the abnormal protrusion on the susceptor.
[0008]
The present invention relates to a susceptor for a horizontal type single-wafer vapor phase growth apparatus configured so that the wafer does not slip when the wafer is transferred, and an abnormal protrusion due to a conventional knurl is not generated on the susceptor surface. And to provide a vapor phase growth method .
[0009]
[Means for Solving the Problems]
The inventor conducted various investigations on the shape of the counterbore part for the purpose of a susceptor for vapor phase growth in which the wafer is not slipped during wafer transfer without performing knurling on the counterbore part of the susceptor. The peripheral edge part of the counterbore part formed as a concave part is formed as an inclined surface, and this part is configured to contact and support the outer peripheral part of the back surface of the wafer, so that the wafer can be prevented from slipping on the susceptor, and the susceptor surface is abnormal. Since there is no protrusion or the like, the inventors have found that slip and contamination associated with vapor phase growth can be reduced, and the present invention has been completed.
[0010]
That is, the susceptor for the vapor phase growth apparatus of the present invention is a susceptor used for a single wafer type vapor phase growth apparatus in which heating means are provided on both front and back sides of the susceptor.
On the susceptor upper surface, a counterbore portion formed as a recess for placing a wafer is formed,
The counterbore part has a bottom surface that is a flat surface parallel to the mounted wafer, and a peripheral end portion that is an inclined surface of an inverted cone that rises at an angle θ from the bottom surface around the bottom surface. ,
The peripheral edge portion contacts the back outer peripheral side of the wafer placed on the inclined surface to contact and support the wafer, and the wafer surface height is the same as or higher than the susceptor upper surface. Shape and
When the wafer is contact-supported at the peripheral edge portion, it is not in contact with the counterbore portion other than the outer periphery of the back surface of the wafer,
The distance between the bottom surface and the wafer is set to 1 to 10 mm, the peripheral edge inclination angle θ is set to 10 to 80 degrees, and the wafer surface is set to be 0 to 0.5 mm higher than the susceptor top surface. Solved the problem.
This invention relates to a susceptor used in a single-wafer type vapor phase growth apparatus in which heating means are provided on both front and back sides of a susceptor, and the shape of the peripheral end portion of a counterbore portion formed as a recess for mounting a wafer is angled. A susceptor for a vapor phase growth apparatus, characterized in that the inclined surface rises at θ, the wafer is in contact with and supported by the inclined surface, and only the outer periphery of the back surface of the wafer is in contact with the counterbore part. Furthermore, the present invention is a single-wafer vapor phase growth method in which heating means are provided on both the front and back sides of the susceptor, and the peripheral end shape of the counterbore portion formed by the concave portion for placing the wafer is raised at an angle θ. Vapor phase growth can be performed using a susceptor having a configuration in which the wafer is in contact with and supported by this inclined surface, and does not contact the counterbore except for the outer periphery of the back surface of the wafer.
Moreover, the vapor phase growth method of the present invention can perform vapor phase growth using the above susceptor.
[0011]
Further, according to the present invention, in the susceptor having the above-described configuration, the bottom surface of the counterbore part formed as a recess for mounting the wafer is a flat surface parallel to the wafer, and the shape of the peripheral end part of the counterbore part is defined as an angle θ. The susceptor for vapor phase growth equipment, which is supported by the inclined surface and is not in contact with the counterbore part other than the outer periphery of the backside of the wafer, or the wafer placed on the counterbore part is contact the end of the counterbore portion on the side, the wafer surface height susceptor upper surface of the same or susceptor upper surface higher vapor phase growth apparatus for susceptor proposes together.
[0012]
[Action]
FIG. 1 shows a susceptor 10 according to the present invention. The counterbore part 11 is merely a concave part. Conventionally, as shown in FIG. 3B, when the surface of the counterbore part 2a is enlarged, the shape of the square pyramid is sharpened. On the other hand, the peripheral edge 12 of the counterbore part 11 is cut not diagonally but obliquely as a flat surface without the knurling of the counterbore part 11, and an inclined surface rising from the center side of the counterbore part (angle θ) ).
The wafer 3 comes into contact with the peripheral end portion 12 of the oblique counterbore portion 11 at the outer periphery or side surface of the back surface of the wafer, and the back surface of the wafer 3 does not contact the counterbore portion 11 except for the outer periphery.
[0013]
Therefore, the slip of the wafer 3 when the wafer 3 is transferred onto the susceptor 10 is eliminated, and the occurrence of slip failure due to the slip can be reduced. Further, since the wafer slip is eliminated, the wafer can be transferred to the same position on the susceptor 10 every time. When vapor phase growth is performed using the susceptor 10, the quality uniformity (reproducibility) of the obtained epitaxial film is obtained. Improved. Furthermore, since the knurling process is not performed on the surface of the susceptor, there are no abnormal protrusions or omissions on the surface, and the occurrence of slip defects, scratches, contamination, etc. due to these can be reduced.
[0014]
Further, since the susceptor for vapor phase growth according to the present invention does not perform knurling, the processing cost is lower than that of the conventional susceptor, and warpage during SiC coating can be prevented.
In addition, since it is easy to process, it becomes possible to produce a susceptor using a material that could not be used in the past (for example, SiC) as a base material. A long susceptor can be made.
[0015]
In the present invention, during the inclination angle of the peripheral end portion 12 is 10 to 80 degrees of the counterbore portion 11 shown in FIG. 1B, interval of the wafer 3 and the counterbore portion bottom surface 1 to 10 mm, the surface of the semiconductor wafer 3 is the It is desirable to appropriately select the shape and the like according to the size of the wafer 3 to be used, the heating conditions, and the like so that the height is equal to or higher than the uppermost surface of the susceptor 10.
Further, in the present invention, the counterbore portion of the susceptor other shape of the peripheral end portion 12 of the illustrated countersunk portion 11 is outer peripheral shape similar to the shape of the required cross-section of the inverted cone, or principal cross section at the opposite polygonal cone It can be made similar to the outer peripheral shape in FIG.
[0016]
【Example】
Example 1
Using the single wafer type vapor phase growth apparatus shown in FIG. 2, a conveyance test was performed using 100 wafers without increasing the furnace temperature, using a P-type (100) Si semiconductor wafer having a diameter of 150 mm. It was evaluated by observing how many of the wafers slip during transportation.
In the susceptor for vapor phase growth according to the present invention, the angle of inclination of the peripheral edge of the counterbore part is 30 degrees, the distance between the wafer and the bottom face of the counterbore part is 2 mm, and the surface of the semiconductor wafer is 0.5 mm higher than the uppermost surface of the susceptor. The dimension shape of each part was determined so that it might become.
For comparison, an evaluation was also conducted using a conventional susceptor with knurling as shown in FIG.
[0017]
As shown in FIG. 4 in which the horizontal axis represents the susceptor conditions and the vertical axis represents the percentage of occurrence of slip, about 85% of the wafers had slip in the past. It became 0%, and the improvement with respect to the sliding at the time of wafer conveyance was confirmed.
[0018]
Example 2
Using the susceptor for vapor phase growth according to the present invention, a reaction temperature using SiHCl ₃ as a Si source by using a single-wafer type vapor phase growth apparatus shown in FIG. An epitaxial film having a thickness of about 10 μm was grown at 1150 ° C.
For comparison, using the same single wafer type vapor phase growth apparatus to prepare a hundred epitaxial growth wafer in a conventional susceptor over the slip is confirmed in the transport test.
[0019]
A total of 200 epitaxially grown wafers were examined for occurrence of slip defects. FIG. 5 shows the total length of slip defects per wafer in the susceptor according to the present invention, and FIG. 6 shows the total length of slip defects in the conventional susceptor.
From these results, it can be seen that the conventional susceptor has a slip defect length of a maximum of 200 mm, but the susceptor of the present invention is reduced to a maximum of 40 mm.
[0020]
Further, with respect to these 200 epitaxially grown wafers, 9 specific resistances on the wafer were measured, variation was obtained from the maximum value and the minimum value, and the reproducibility of the specific resistance in the continuous reaction was evaluated.
FIG. 7 shows the measurement result of the specific resistance with the susceptor according to the present invention, and FIG. 8 shows the measurement result with the conventional susceptor in which sliding occurred during the wafer transfer.
As a result, while the variation in specific resistance has been ± 3.7 to 4.9% in the past, in the susceptor of the present invention, the variation has been improved to ± 3.1 to 3.9%. I understand.
[0021]
【The invention's effect】
As is apparent from the embodiments, the susceptor according to the present invention has no slippage when the wafer is transferred to the susceptor as compared with the conventional susceptor, and as a result, it is possible to reduce the occurrence of slip defects and no wafer slippage. Therefore, it is possible to improve variation in specific resistance of an epitaxially grown wafer obtained by performing vapor phase growth using the susceptor of the present invention .
Also, the counterbore portion in the conventional susceptor over to have subjected to Loretto working poor yield of the susceptor fabricated, its is correspondingly cost was high, since there is no knurling in susceptor of the present invention, machining is easy machining Cost can be reduced.
[0022]
Since the surface of the susceptor according to the present invention is flat, defects such as abnormal protrusions and surface defects hardly occur, and the back surface of the wafer does not come into contact with the susceptor surface except the outer periphery. Does not transfer to the wafer or cause scratches on the backside of the wafer.
Furthermore, since processing in comparison with the conventional susceptor over it is easy, such as high purity SiC, conventionally, a material that could not be used for knurling is complicated, used as the base material of the susceptor over can, effect can be expected to improve the quality of the extension and the epitaxial film of the life of the susceptor over.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an embodiment of a susceptor according to the present invention, in which A is a top explanatory diagram and B is a longitudinal explanatory diagram.
FIG. 2 is an explanatory view showing a configuration of a horizontal single wafer type vapor phase growth apparatus.
FIG. 3 is an explanatory view showing a configuration of a conventional susceptor, in which A is an upper surface explanatory view and B is a longitudinal explanatory view.
FIG. 4 is a graph comparing slip occurrence rates.
FIG. 5 is a graph showing the occurrence of slip when the susceptor of the present invention is used.
FIG. 6 is a graph showing the occurrence of slip when a conventional susceptor is used.
FIG. 7 is a graph showing the in-plane distribution of specific resistance of an epitaxially grown wafer when the susceptor of the present invention is used.
FIG. 8 is a graph showing the in-plane distribution of resistivity of an epitaxially grown wafer when a conventional susceptor is used.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Chamber 2, 10 Susceptor 2a, 11 Counterbore part 3 Semiconductor substrate 4 Lamp 5 Nozzle part 12 Circumferential edge part

Claims (2)

In a susceptor used for a single wafer type vapor phase growth apparatus provided with heating means on both front and back sides of the susceptor,
On the susceptor upper surface, a counterbore portion formed as a recess for placing a wafer is formed,
The counterbore part has a bottom surface that is a flat surface parallel to the mounted wafer, and a peripheral end portion that is an inclined surface of an inverted cone that rises at an angle θ from the bottom surface around the bottom surface. ,
The peripheral edge portion contacts the back outer peripheral side of the wafer placed on the inclined surface to contact and support the wafer, and the wafer surface height is the same as or higher than the susceptor upper surface. Shape and
When the wafer is contact-supported at the peripheral edge portion, it is not in contact with the counterbore portion other than the outer periphery of the back surface of the wafer ,
The distance between the bottom surface and the wafer is set to 1 to 10 mm, the peripheral edge inclination angle θ is set to 10 to 80 degrees, and the wafer surface is set to be 0 to 0.5 mm higher than the susceptor top surface. A susceptor for a vapor phase growth apparatus. Vapor deposition method and performing a vapor phase growth using a susceptor according to claim 1, wherein.

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