JP4665935B2 - Manufacturing method of semiconductor wafer - Google Patents

Description

The present invention relates to a method of manufacturing a semi-conductor wafer.

Conventionally, a silicon single crystal substrate (hereinafter sometimes abbreviated as a semiconductor substrate or a substrate) supported by a susceptor is heated to a growth temperature by a heating device, and a source gas is formed on a main surface of the substrate by a gas supply device. A method of manufacturing a semiconductor wafer by vapor-depositing a thin film on the main surface of the substrate is known.

  The vapor phase growth apparatus used in such a manufacturing method includes a substrate having a main surface side and a main back surface side, such as a so-called single wafer type vapor phase growth apparatus or a barrel type (cylinder type) vapor phase growth apparatus. Such as a type that performs vapor phase growth while heating from both (hereinafter referred to as type 1) (heating from the main back side is performed through a susceptor), a so-called pancake type vapor phase growth apparatus, and the like, There is a type in which vapor phase growth is performed while heating the substrate only from the main back surface side through a susceptor (hereinafter referred to as type 2).

  Among these, in the case of type 2, as shown in FIG. 6, a heating device (for example, a high frequency induction heating coil) 102 is disposed below the susceptor 101 that supports the substrate W, and the susceptor 101 is moved by the heating device 102. The substrate W is heated from the main back surface side. For this reason, during vapor phase growth, the lower portion of the substrate W is thermally expanded more than the upper portion, so that the substrate W warps so as to protrude downward toward the center as shown in FIG. Therefore, in order to make the susceptor 101 fit suitably to the substrate W even in the state of warping in this way and to make the amount of heat conduction from the susceptor 101 to the substrate W uniform in the plane, as shown in FIG. The counterbore 103 of 101 is recessed in the concave curved surface shape which becomes large as it goes to a center from a peripheral part.

On the other hand, in the case of Type 1, for example, as shown in FIG. 5, heating devices 112 (for example, halogen lamps) are arranged on both the main surface side and the main back surface side with respect to the susceptor 111. Is heated from both the main surface side and the main back side. For this reason, since the substrate W hardly generates heat distribution in the front and back directions, the substrate W is maintained almost flat even during vapor phase growth.
Therefore, the counterbore 113 of the susceptor 111 in the case of type 1 is formed in a plane as shown in FIG. 5 (see, for example, Patent Document 1).
JP 2003-1442412 A

  However, in the case of the above type 1, the main back surface of the substrate W is in contact with the bottom surface of the counterbore 113, which is a flat surface, so that a contact mark with the bottom surface of the counterbore 113 is formed on the main back surface. May affect the appearance. This becomes a problem particularly when the main back surface of the substrate W is also subjected to mirror polishing (when a double-sided mirror substrate is used).

The present invention has been made to solve the above-described problems. When the semiconductor substrate is heated from both the main surface side and the main back side to perform vapor phase growth, the main substrate is used. and to provide a method of manufacturing a semi-conductor wafer capable prevented that the contact mark is formed on the back surface.

In order to solve the above problems, a method for manufacturing a semiconductor wafer of the present invention includes:
In a semiconductor wafer manufacturing method of manufacturing a semiconductor wafer by vapor-phase growth of a silicon single crystal thin film on a main surface of a silicon single crystal substrate having a diameter of 300 mm and having both surfaces subjected to mirror polishing,
As a susceptor for supporting the silicon single crystal substrate during vapor phase growth performed by heating the silicon single crystal substrate from both the main surface side and the main back surface side,
Having a counterbore for positioning the silicon single crystal substrate with respect to the susceptor,
The bottom face of the counterbore is gradually recessed from the peripheral edge toward the center, thereby being recessed from the bent shape of the silicon single crystal substrate during the heating,
The susceptor in which the bottom surface is recessed so that the maximum distance between the bottom surface and the silicon single crystal substrate is 0.35 mm or more and less than 0.45 mm when the silicon single crystal substrate is supported without heating.
And using
The counterbore has a two-stage structure having an outer peripheral side portion that supports the silicon single crystal substrate and an inner peripheral side portion that is formed inside the outer peripheral side portion so as to be recessed from the outer peripheral side portion. Use
The silicon single crystal substrate is supported by said susceptor, with heating from both the main back side over a main surface side and the susceptor, vapor phase growth of a silicon single crystal thin film on the main surface of the silicon single crystal substrate It is characterized by letting .

According to the method for manufacturing a semiconductor wafer of the present invention, the bottom face of the counterbore is recessed from the bent shape of the substrate at the time of heating in vapor phase growth, so that the substrate is separated from the main surface side and the main back surface side. When performing vapor phase growth by heating from both sides, even if the substrate is slightly bent in the direction in which the central part approaches the counterbore due to heating, the main back surface and the counterbore bottom surface of the substrate are brought into a non-contact state. Can be maintained. Therefore, a semiconductor wafer is obtained by vapor-phase-growing a thin film on the main surface of the substrate while preferably preventing contact traces with the counterbore bottom surface from being formed on the main back surface of the substrate whose both surfaces are mirror-polished. Can be manufactured .
However, if the distance between the counterbore and the substrate is too large, a large amount of hydrogen used for vapor phase growth enters the gap, and as a result, the main back surface of the substrate is etched by the hydrogen, and the main back surface Small scratches formed on the surface may become noticeable. Therefore, it is not necessary that the recess of the counterbore is large (the counterbore is simply deep).
For such circumstances, if the susceptor is gradually recessed toward the center from the peripheral edge, or a susceptor having an inclined surface portion, the peripheral edge while preventing contact with the substrate. The distance between the substrate and the spot facing can be reduced. Therefore, as a result of suppressing the penetration of hydrogen into the gap, the etching of the main back surface of the substrate due to the hydrogen can also be suppressed. Therefore, even if a slight scratch is formed on the main back surface, this scratch becomes conspicuous. Can be prevented.

In particular, in a two-stage counterbore, the maximum distance between the bottom surface of the inner peripheral portion and the silicon single crystal substrate is 0.35 mm or more and 0.45 mm in a state where the silicon single crystal substrate is supported without heating. When the bottom surface of the inner peripheral side portion is recessed so as to be less, the distance between the substrate and the counterbore can be reduced over the entire surface. Therefore, it is possible to further suppress the entry of hydrogen into the interval. Therefore, it is possible to more suitably prevent the minute scratches formed on the main back surface of the substrate from becoming conspicuous.

By the way, the susceptor is configured, for example, by coating SiC (silicon carbide) on the surface of a main body portion made of graphite. And when coating SiC with a main-body part, a main-body part is heated to high temperature. The main body is greatly warped by this heating, but since it is difficult to predict the amount of warping, it is extremely difficult to control the amount of warping by the amount of heating. Of course, the amount of warping is larger as the main body is larger in size, so that there is a problem that it is difficult to form a flatter as the susceptor has a larger diameter.
For such a situation, according to the susceptor used in the present invention , the bottom face of the counterbore (at least a part thereof) may be formed in a state of being recessed in a curved shape that is further away from the substrate toward the center from the peripheral edge. The susceptor can be manufactured more easily than the case where the counterbore needs to be formed flat. For example, a susceptor having a relatively large size such as a susceptor supporting a semiconductor wafer having a diameter of 300 mm can be preferably manufactured. Is possible.

In addition, the susceptor used in the present invention is formed in a disk shape having a curved overall posture so that the back surface of the main surface supporting the silicon single crystal substrate is recessed toward the center of the back surface. In this case, the present invention can also be applied to a case where the main surface supporting the silicon single crystal substrate is formed in a disk shape having an overall posture that warps so as to protrude.
In this case, since the susceptor may be formed in a warped overall posture, that is, it is not necessary to form the whole posture in a flat plate shape. Manufacturing becomes easy, and even a susceptor having a relatively large size, such as a susceptor that supports a semiconductor wafer having a diameter of 300 mm, can be preferably manufactured.

Further, according to the semiconductor wafer manufacturing method of the present invention, a thin film is vapor-phase grown on the main surface of the substrate whose both surfaces are mirror-polished without forming contact marks on the main back surface of the substrate. Can be manufactured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
First, the configuration of the susceptor will be described.
The susceptor 1 of the present embodiment shown in FIG. 1 supports the substrate W during vapor phase growth performed by heating the substrate W from both the main surface side and the main back surface side.
The susceptor 1 is schematically configured in a flat disk shape, for example.
The susceptor 1 has a counterbore 2 on the upper surface for positioning the substrate W with respect to the susceptor 1 while the substrate W is supported. This counterbore 2 is a circular recess in plan view with an inner diameter set slightly larger than the diameter of the substrate W.
However, the counterbore 2 of the susceptor 1 of the present embodiment is formed in an annular outer peripheral side portion 21 that supports the substrate W, and in a state of being recessed from the outer peripheral side portion 21 inside the outer peripheral side portion 21. A two-stage configuration having a circular inner peripheral side portion 22 in plan view is formed.
Among these, the outer peripheral side portion 21 is formed in a flat surface, for example, so that the peripheral edge portion or the chamfered portion of the substrate W can be suitably supported.
On the other hand, the bottom surface 22a of the inner peripheral side portion 22 is recessed in a concave curved shape so as to gradually become deeper from the peripheral edge toward the center, for example.
However, the concave shape of the bottom surface 22a of the inner peripheral side portion 22 is set deeper than the bent shape of the substrate W at the time of heating in vapor phase growth. That is, the bottom surface of the spot facing 2 is recessed from the bent shape of the substrate W during the heating in the vapor phase growth.
The maximum distance D between the bottom surface 22a of the inner peripheral side portion 22 of the counterbore 2 and the main back surface of the substrate W in a state where the substrate W is supported by the susceptor 1 without being heated is 0.35 mm or more and less than 0.45 mm. For example, it is set to 0.4 mm or less.
Such a susceptor 1 is configured, for example, by coating SiC (silicon carbide) on the surface of a main body portion made of graphite.

Next, the configuration of the semiconductor wafer manufacturing apparatus will be described.
As shown in FIG. 2, a semiconductor wafer manufacturing apparatus 10 is an apparatus for vapor-phase growth of a thin film (for example, a silicon single crystal thin film) on a main surface of a substrate W (for example, a silicon single crystal substrate), and a reaction vessel 11, the susceptor 1 disposed in the reaction vessel 11, a driving device (not shown) for rotating the susceptor 1 during vapor phase growth, and the reaction vessel 11 disposed above and below the susceptor 1. A heating apparatus 13 (for example, a halogen lamp) for heating is generally provided.
Gas (gas phase growth gas containing source gas and carrier gas) is introduced into the reaction vessel 11 along the arrow A direction, and exhausted along the arrow B direction from the reaction vessel 11. It has become.

Next, a method for manufacturing a semiconductor wafer will be described.
First, the susceptor 1 that supports the substrate W is placed in the reaction vessel 11, and while rotating the susceptor 1, the substrate W in the reaction vessel 11 is heated by the heating device 13 and gas is introduced into the reaction vessel 11. Thus, the gas can be supplied onto the main surface of the substrate W, and a thin film can be vapor-phase grown on the main surface of the substrate W to manufacture a semiconductor wafer.
The substrate W during the vapor phase growth is heated from both the main surface side of the substrate W and the main back surface side of the substrate W through the susceptor 1.
Further, as the substrate W, for example, a substrate whose both surfaces are mirror-polished (a substrate of a double-sided mirror) is used.

By the way, during vapor phase growth, the substrate W may be slightly bent in the direction in which the central portion approaches the bottom surface 22a of the inner peripheral side portion 22 of the spot facing 2 due to heating.
On the other hand, in the susceptor 1 of this embodiment, the bottom surface (the counterbore bottom surface) 22a of the inner peripheral side portion 22 of the counterbore 2 is recessed from the bent shape of the substrate W during the vapor phase growth heating. Therefore, even if the substrate W is bent by the heating as described above, the main back surface of the substrate W can be prevented from coming into contact with the bottom surface 22a. Therefore, it is possible to suitably prevent the contact trace with the spot facing 2 from being formed on the main back surface of the substrate W.
Moreover, since the bottom surface 22a of the inner peripheral side portion 22 of the spot facing 2 is gradually depressed toward the center from the peripheral edge portion, the distance between the substrate W and the bottom surface 22a at the peripheral edge portion is made narrower than the central portion. Can do. Therefore, it is possible to suppress the penetration of hydrogen (used as a carrier gas) into the gap while maintaining the non-contact state between the bottom surface 22a and the substrate W. As a result, the etching of the main back surface of the substrate W due to the hydrogen can also be suppressed, so that even if a slight scratch is formed on the main back surface, the scratch can be prevented from becoming noticeable.
Therefore, even when a semiconductor wafer is manufactured using the substrate W of the double-sided mirror, it is possible to prevent the contact trace with the bottom surface 22a from being formed on the main back surface of the substrate W.
It should be noted that minute scratches formed on the main back surface of the substrate W are considered to be polishing scratches formed in the polishing process, and are conspicuous by hydrogen etching.

Next, a preferred example of this embodiment will be described.
<Example>
The inventor can support a substrate having a diameter of 300 mm, and the maximum distance between the main back surface of the substrate W and the bottom surface 22a of the inner peripheral side portion 22 of the counterbore 2 in a state where the substrate W is supported without heating is 0.4 mm. The susceptor 1 of the present embodiment configured to be as follows and the susceptor 1 configured to have a maximum distance of 0.35 mm were prepared.
Then, using each of these susceptors 1, a silicon single crystal thin film as a thin film is vapor-phase grown at 1130 ° C. in a hydrogen atmosphere on the main surface of a silicon single crystal substrate as a substrate W of a double-sided mirror, and a semiconductor wafer As a silicon epitaxial wafer.
When the main back surface of the manufactured silicon epitaxial wafer was visually inspected, no noticeable scratches were found both when the susceptor 1 having the maximum distance of 0.4 mm was used and when the susceptor 1 having the same 0.35 mm was used. It was.

<Comparative example>
In addition, as a comparative example, the inventor has the same susceptor as in the above example except that the maximum distance is 0.45 mm, and the same as in the above example except that the maximum distance is 0.7 mm. Each susceptor was prepared, and using these susceptors, a semiconductor wafer (that is, a silicon epitaxial wafer) was manufactured under the same conditions as in the above-described example.
When the main back surface of the manufactured silicon epitaxial wafer was visually inspected, a noticeable scratch was found when the susceptor having the maximum distance of 0.45 mm was used. Further, when a susceptor having the maximum distance of 0.7 mm was used, more conspicuous scratches were found.

As is clear from the examination of such an example and a comparative example, the susceptor 1 of the present embodiment is such that the main back surface of the substrate W and the inner peripheral side portion of the counterbore 2 in a state where the substrate W is supported without being heated. If the maximum distance between the bottom surface 22a and the bottom surface 22a is 0.4 mm or less, hydrogen can be prevented from entering the space between the bottom surface 22a and the substrate W, and etching of the main back surface of the substrate due to the hydrogen can also be suppressed. .
Therefore, even if a minute flaw is originally formed on the main back surface of the substrate W, it can be prevented that the flaw becomes noticeable after the production of the semiconductor wafer.

According to the embodiment as described above, since the bottom surface 22a of the spot facing 2 is recessed from the bending shape of the substrate W during the vapor phase growth heating, the central portion of the substrate W is heated. Even if it slightly bends in the direction approaching the counterbore 2, the main back surface of the substrate W and the bottom surface 22a of the counterbore 2 can be maintained in a non-contact state. Therefore, it is possible to suitably prevent contact marks from being formed on the main back surface of the substrate W.
In addition, since the bottom surface 22a of the spot facing 2 is gradually depressed toward the center from the peripheral edge, the distance between the substrate W and the counterbore 2 at the peripheral edge can be reduced. Therefore, as a result of suppressing the penetration of hydrogen into the gap, the etching of the main back surface of the substrate due to the hydrogen can also be suppressed. Therefore, even if a slight scratch is formed on the main back surface, this scratch becomes conspicuous. Can be prevented.
In particular, the maximum distance D between the bottom surface 22a of the inner peripheral portion 22 and the substrate W is 0.35 mm or more and less than 0.45 mm, for example, 0.4 mm or less when the substrate W is supported without being heated. In addition, since the bottom surface 22a is recessed, the entry of hydrogen into the gap between the substrate W and the counterbore 2 can be reliably suppressed.

In the first embodiment, the example has been described in which the bottom surface 22a of the spot facing 2 is gradually recessed into a concave curved surface (recessed into a dome shape) from the peripheral edge toward the center. The present invention is not limited to this, and the bottom surface of the counterbore 2 may be in any other shape as long as the bottom surface of the counterbore 2 is recessed from the bent shape of the substrate W during the vapor phase growth heating. Since the back surface and the bottom surface 22a of the spot facing 2 can be maintained in a non-contact state, contact traces can be prevented from being formed on the main back surface of the substrate W.
Specifically, for example, the bottom surface of the spot facing may be recessed in an inverted conical shape (however, the height is extremely smaller than the top surface).
Alternatively, the bottom face of the counterbore may be recessed in an inverted truncated cone shape. That is, a part of the bottom face of the counterbore is an inclined surface-like part gradually recessed toward the center from the peripheral part (for example, corresponding to a side peripheral surface in the inverted frustoconical depression). The portion closer to the center than the inclined surface portion (e.g., corresponding to the flat surface portion of the inverted truncated cone-shaped recess) is deeper than the deepest portion of the inclined surface portion (when the recess is an inverted truncated cone shape) And a depth equal to the deepest portion of the inclined surface portion.
Further, for example, in the case of the counterbore of the two-stage configuration as described above, if the bottom surface 22a of the counterbore 2 is recessed from the bent shape of the substrate W during the vapor phase growth heating, the bottom surface 22a May be formed in a plane. However, in this case, since the distance between the bottom surface 22a and the substrate W at the peripheral edge is increased, the substrate W is easily etched, and the bottom surface 22a is flat. Therefore, when the susceptor is large, the susceptor is manufactured. hard.
Further, for example, in the case of a counterbore having a two-stage structure as described above, the bottom surface 22a of the counterbore 2 may be raised. However, in this case as well, the gap between the bottom surface 22a and the substrate W at the peripheral portion becomes large, so that the substrate W is easily etched, and the temperature at the peripheral portion of the substrate is lower than that at the central portion, so that slip is likely to occur. Become.

[Second Embodiment]
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In the susceptor 30 of the second embodiment shown in FIG. 3, as can be seen from the comparison with the imaginary line L drawn in a straight line, the back surface 32 is the center of the back surface 32 with respect to the main surface 31 that supports the substrate W. It is formed in a board shape that forms an overall posture that warps in such a manner that it is depressed as the portion is formed.
A counterbore 2 similar to that in the first embodiment is formed on the main surface 31 of the susceptor 30.
According to the second embodiment, the susceptor 30 may be formed in a warped overall posture. That is, it is not necessary to form the entire posture to be flat. Therefore, the susceptor 30 can be manufactured more easily than the case where it is necessary to form it in a flat plate shape. For example, even a susceptor having a relatively large size such as a susceptor that supports a semiconductor wafer having a diameter of 300 mm can be preferably manufactured. Is possible.

  In each of the above-described embodiments, the example in which the counterbore 2 has a two-stage configuration has been described. However, the present invention is not limited thereto, and for example, the counterbore 2 has one stage as in the susceptor 40 illustrated in FIG. Also good. In the case of the example shown in FIG. 4, the counterbore 2 supports the substrate W with its bottom surface 2 a in a circular line contact state with the substrate W.

It is typical front sectional drawing which shows the susceptor of 1st Embodiment. It is typical front sectional drawing which shows the manufacturing apparatus of a semiconductor wafer. It is a typical front sectional view showing a susceptor of a 2nd embodiment. It is a typical front view which shows the example in which the spot face is one step. It is typical front sectional drawing which shows the conventional vapor phase growth apparatus (type 1). It is typical front sectional drawing which shows the conventional vapor phase growth apparatus (type 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Susceptor 2 Counterbore 21 Outer peripheral part 22 Inner peripheral part 22a Bottom surface of inner peripheral part (bottom face of counterbore)
30 Susceptor 40 Susceptor W Semiconductor substrate D Maximum distance

Claims (1)

In a semiconductor wafer manufacturing method of manufacturing a semiconductor wafer by vapor-phase growth of a silicon single crystal thin film on a main surface of a silicon single crystal substrate having a diameter of 300 mm and having both surfaces subjected to mirror polishing,
As a susceptor for supporting the silicon single crystal substrate during vapor phase growth performed by heating the silicon single crystal substrate from both the main surface side and the main back surface side,
Having a counterbore for positioning the silicon single crystal substrate with respect to the susceptor,
The bottom face of the counterbore is gradually recessed from the peripheral edge toward the center, thereby being recessed from the bent shape of the silicon single crystal substrate during the heating,
The susceptor in which the bottom surface is recessed so that the maximum distance between the bottom surface and the silicon single crystal substrate is 0.35 mm or more and less than 0.45 mm when the silicon single crystal substrate is supported without heating.
And using
The counterbore has a two-stage structure having an outer peripheral side portion that supports the silicon single crystal substrate and an inner peripheral side portion that is formed inside the outer peripheral side portion so as to be recessed from the outer peripheral side portion. Use
The silicon single crystal substrate is supported by said susceptor, with heating from both the main back side over a main surface side and the susceptor, vapor phase growth of a silicon single crystal thin film on the main surface of the silicon single crystal substrate A method for producing a semiconductor wafer, comprising:

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