JP2010074037A - Susceptor, and apparatus and method for manufacturing semiconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a susceptor and an apparatus and method for manufacturing semiconductor, capable of inhibiting metal contamination during a film formation process, uniformly forming a film on a wafer, preventing deterioration in yield and improving reliability of a semiconductor device. <P>SOLUTION: This susceptor includes: a first annular susceptor part 21 for placing a wafer w; a first concave portion 22a for holding the wafer w; a second annular concave portion 22b formed in the first concave portion 22a and for housing the first susceptor part 21 without allowing the susceptor part 21 to protrude or be retracted; and a second susceptor part 22 having a plurality of opening portions 22c formed in the second concave portion 22b and shielded by the first susceptor part 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a susceptor for holding a semiconductor wafer, a semiconductor manufacturing apparatus, and a semiconductor manufacturing method, for example, used for film formation by supplying a reaction gas to the surface while heating from the back surface of a semiconductor wafer.

  In recent years, along with demands for lowering the cost and higher performance of semiconductor devices, there has been a demand for higher quality such as improvement in film thickness uniformity as well as high productivity in the wafer film forming process.

  In order to satisfy such requirements, a backside heating method is used in which a single-wafer type epitaxial film forming apparatus is used, for example, a process gas is supplied while being rotated at a high speed of 900 rpm or more and heated from the backside using a heater. .

  In recent years, with the miniaturization and high functionality of semiconductor devices, a high level of metal contamination is required in the film forming process. In the above-described backside heating method, the wafer has a heat source and a rotation mechanism below the wafer, and is not completely separated from the heat source and the rotation mechanism, so that the wafer contamination occurs due to diffusion and movement of metal atoms. There's a problem.

  Usually, a wafer is held by a susceptor in a film forming apparatus (reaction furnace), and is moved up by a push-up pin penetrating a pin hole provided in the susceptor during transport. Therefore, there is a problem that it is particularly difficult to block wafer contamination from the pin holes.

  On the other hand, for example, Patent Document 1 proposes a susceptor structure in which pin holes are not provided in order to achieve uniform wafer temperature distribution. However, if the susceptor structure does not actually have pin holes, a gas layer is formed at the bottom of the wafer when the wafer is placed, and the wafer rises, making it difficult to hold it stably. . Furthermore, when forming a film by heating and rotating the wafer and supplying a process gas, uniform film formation is difficult in such an unstable state.

In order to perform uniform film formation, it is necessary to rotate the wafer at a high speed. In such an unstable state, the wafer may move out of the susceptor mounting position during the high-speed rotation. There is a problem that uniform film formation becomes difficult.
JP 2002-43302 A ([0019] to [0022], [0036], FIG. 1 and the like)

  As described above, in order to block contamination from the pin holes provided in the susceptor, a susceptor structure in which no pin holes are provided makes it difficult to stably hold the wafer and form a film uniformly. Therefore, it is conceivable to provide a plurality of protrusions on the susceptor and place the wafer thereon, but the uniformity of the temperature distribution of the wafer cannot be obtained, and it is difficult to form a uniform film. Problems arise.

  The present invention suppresses metal contamination in a film forming process, can form a film uniformly on a wafer, suppresses a decrease in yield, and improves the reliability of a semiconductor device, and semiconductor manufacturing An object is to provide an apparatus and a semiconductor manufacturing method.

  The susceptor of the present invention is formed in an annular first susceptor part for mounting a wafer, a circular first recess for holding the wafer, and the first recess. An annular second concave portion that is housed without being protruded or depressed, and a second susceptor part that is formed in the second concave portion and has a plurality of openings that are shielded by the first susceptor part. Features.

  In the susceptor of the present invention, the wall surfaces of the first susceptor part and the second recess preferably have a taper.

  Furthermore, the susceptor of the present invention preferably includes a third susceptor part that holds the second susceptor part on its outer periphery.

  The semiconductor manufacturing apparatus of the present invention includes a reaction furnace into which a wafer is introduced, a gas supply mechanism for supplying process gas to the reaction furnace, a gas discharge mechanism for discharging gas from the reaction furnace, and a wafer. An annular first susceptor part to be placed, a circular first recess for holding a wafer, and a first susceptor part that is formed in the first recess without being protruded or depressed. An annular second recess, a susceptor having a second susceptor part formed in the second recess and having a plurality of openings shielded by the first susceptor part, and heating the wafer from the lower part of the susceptor A heating mechanism, a rotating mechanism for rotating the wafer, and a vertical drive mechanism for raising and lowering the first susceptor part.

  In addition, the semiconductor manufacturing method of the present invention carries a wafer into a reaction furnace, and is installed in the reaction furnace, and a second annular susceptor part for holding the wafer is used for holding the wafer. The susceptor part is lifted by a push-up pin penetrating an opening formed in the annular second recess provided in the circular first recess formed on the first susceptor part, and the wafer is placed on the first susceptor part The first susceptor part is lowered, and the first susceptor part is housed in the second recess without protruding or sinking, and the opening formed in the second recess is shielded. Holding the wafer in the first recess, heating the wafer through the first susceptor part and the second susceptor part, rotating the wafer, and supplying a process gas onto the wafer. .

  According to the present invention, it is possible to suppress metal contamination in the film formation process of a semiconductor device, to form a film uniformly on a wafer, to suppress a decrease in yield, and to improve the reliability of the semiconductor device. It becomes.

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

  FIG. 1 shows a cross-sectional view of an epitaxial growth apparatus which is a semiconductor manufacturing apparatus of this embodiment. As shown in the figure, for example, in a reaction chamber 11 in which a wafer w having a diameter of 200 mm is formed, a process gas including a source gas such as TCS and dichlorosilane is supplied onto the wafer w from above the reaction chamber 11. A gas supply port 12 connected to a gas supply mechanism (not shown) is installed. A gas discharge port connected to a gas discharge mechanism (not shown) for discharging gas to, for example, two places below the reaction chamber 11 and controlling the pressure in the reaction chamber 11 to be constant (normal pressure). 13 is installed.

  A rectifying plate 14 for supplying the process gas supplied from the gas supply port 12 to the wafer w in a rectified state is installed in the upper part of the reaction chamber 11.

  Below the reaction chamber 11, a rotation drive mechanism 15 for rotating a wafer w composed of a motor (not shown), a rotation shaft (not shown), a ring 15 a and the like is connected to the rotation drive mechanism 15. A susceptor 16 for holding the wafer w is installed.

  Below the susceptor 16, an in-heater 17a for heating a wafer w made of, for example, SiC is installed. Furthermore, between the susceptor 17 and the in-heater 17a, an out-heater 17b for heating the peripheral portion of the wafer w made of, for example, SiC is installed. A disc-shaped reflector 18 for efficiently heating the wafer w is installed below the in-heater 17a. A push-up pin 19 is provided so as to penetrate the in-heater 17a and the reflector 18 and move the wafer w up and down.

  FIG. 2 shows an enlarged view of the susceptor 16. As shown in the figure, the susceptor 16 made of SiC or the like includes an inner susceptor 21 that is a first susceptor part, a mid susceptor 22 that is a second susceptor part, and an outer susceptor 23 that is a third susceptor part. Yes.

  The inner susceptor 21 has, for example, an annular shape with an inner diameter of 150 to 170 mm and an outer diameter of 190 mm, and can be moved up and down by the push-up pins 19 from below with or without the wafer w mounted thereon. And the side surface is provided with a taper of 15 °, for example.

  The mid susceptor 22 has a disc shape and is formed in a circular recess 22a for holding the wafer w and in the recess 22a. The mid susceptor 22 has, for example, a 15 ° taper on the side surface, and does not protrude or sink the inner susceptor. An annular recess 22b to be housed and a plurality of openings 22c formed in the second recess and penetrating the push-up pin 19 are formed. The opening 22c can be shielded by the inner susceptor 21. Then, a step portion 22d whose upper side protrudes is formed on the outer peripheral portion.

  The outer susceptor 23 is formed with a step portion 23a whose lower side protrudes on the inner periphery, and holds the mid susceptor 22 by arranging the step portion 22b on the step portion 23a. And it is connected with the rotation drive mechanism 15 in the outer periphery.

  For example, a Si epitaxial film is formed on the wafer w using such a semiconductor manufacturing apparatus. First, for example, a φ200 mm wafer w is introduced into the reaction chamber 11 and placed on the inner susceptor 21 raised by the push-up pins 19 as shown in FIG. Then, the inner susceptor 21 is housed in the recess 22 b of the mid susceptor 22 by lowering the push-up pin 19.

  At this time, the upper surface of the inner susceptor 21 is accommodated without protruding or sinking from the bottom surface of the recess 22a of the mid susceptor. That is, the upper surface of the inner susceptor 21 and the bottom surface of the recess 22a of the mid susceptor constitute the same plane, and the back surface of the wafer w is in uniform contact with the upper surface of the inner susceptor 21 and the bottom surface of the recess 22a of the mid susceptor. is doing.

  Next, the temperature of the in-heater 17a is controlled to about 1400 ° C., and the temperature of the out-heater 17b is controlled to about 1500 ° C. so that the temperature of the wafer w becomes 1100 ° C. Then, the wafer w is rotated at, for example, 900 rpm by the rotation driving mechanism 15 and the process gas is supplied from the gas supply port 12 through the rectifying plate 14 in a rectified state onto the wafer w. The process gas is prepared to have a TCS concentration of 2.5%, for example, and supplied at, for example, 50 SLM.

  On the other hand, gas such as excess TCS-containing process gas, dilution gas, and reaction by-product HCl is discharged from the gas discharge port 13, and the pressure in the reaction chamber 11 is controlled to be constant (for example, normal pressure). Then, an Si epitaxial film is grown on the wafer w.

  Thus, by dividing the susceptor and making the inner susceptor 21 into an annular shape, the wafer w can be placed on the inner susceptor 21 with a relatively small contact area with respect to the area of the wafer w. Therefore, since the influence of the gas layer formed in the lower part of the wafer can be suppressed, the floating of the wafer w can be suppressed, and the variation in the temperature distribution of the wafer w can be suppressed.

  FIG. 4 shows the position dependency of the wafer w temperature during the formation of the epitaxial film. As a comparative example, FIG. 5 shows the position dependency of the wafer w temperature when a wafer is placed on a plurality of protrusions formed on a circular inner susceptor and an epitaxial film is similarly formed. As shown in these drawings, according to the present embodiment, it is possible to suppress the temperature rise particularly at the peripheral portion of the wafer to about 62 to 75% of the conventional case. For example, the in-plane film thickness variation is 0.5%. The following uniform epitaxial film can be formed.

  Further, the slip stress defined by the shear stress in the crystal direction caused by the variation in temperature distribution can be suppressed to about 58 to 94% of the conventional value, and the occurrence of slip on the wafer w can be suppressed. .

  Further, in the epitaxial film formed in this way, the diffusion length of Fe by the SPV (Surface Photovoltage) method becomes, for example, 400 μm, and metal contamination can be sufficiently suppressed.

  In the present embodiment, the susceptor is divided into three parts of the inner susceptor 21, the mid susceptor 22, and the outer susceptor 23. However, the mid susceptor and the outer susceptor may be integrated. However, the thermal stress can be further suppressed by dividing into three as in this embodiment. Therefore, it is possible to suppress a decrease in productivity by suppressing breakage due to thermal stress and reducing the maintenance frequency.

  Further, the side surface of the inner susceptor 21 and the side surface of the recess 22b of the mid susceptor 22 are each provided with a 15 ° taper. However, by providing the taper, the inner susceptor 21 can be easily housed in the recess 22b. Even if the inner susceptor 21 is lowered (or raised) by the push-up pin 19, even if a slight displacement occurs, it can be stored in the recess 22b. At this time, the taper angle is preferably 10 to 30 °. If it is less than 10 °, the margin of misalignment when the inner susceptor 21 is housed in the recess 22b is reduced. On the other hand, if the angle exceeds 30 °, the contact area between the wafer w and the inner susceptor 21 becomes large, and it is influenced by the gas layer formed below the wafer. More preferably, it is 15 ± 2 °.

  Furthermore, as shown in the partial enlarged view of the contact portion between the inner susceptor 21 ′ and the mid susceptor 22 ′ in FIG. 6, a step portion may be provided on the side surface of the inner susceptor 21 ′ and the side surface of the recess 22b ′ of the mid susceptor 22 ′. Good. By providing the stepped portion, metal contamination from the back surface can be further suppressed.

  Moreover, although SiC was used as the susceptor material, it is preferable from the viewpoint of workability and high temperature stability. For SiC, a sintered body can be used, and high purity SiC may be coated. Also, carbon coated with high purity SiC can be used.

  According to these embodiments, a film such as an epitaxial film can be stably formed on the semiconductor wafer w with high productivity. As well as improving the yield of the wafer, it is possible to improve the yield of the semiconductor device formed through the element formation process and the element isolation process and to stabilize the element characteristics. In particular, an excellent element can be obtained by being applied to an epitaxial formation process of a power semiconductor device such as a power MOSFET or IGBT that requires a thick film growth of 100 μm or more in an N-type base region, a P-type base region, an insulating isolation region, or the like. It becomes possible to obtain characteristics.

In the present embodiment, the case of forming a Si single crystal layer (epitaxial film) has been described. However, the present embodiment can also be applied when forming a poly-Si layer. Further, the present invention can be applied to film formation other than Si film such as SiO ₂ film and Si ₃ N ₄ film, and compound semiconductor such as GaAs layer, GaAlAs and InGaAs. Various other modifications can be made without departing from the scope of the invention.

FIG. 6 is a cross-sectional view of a semiconductor manufacturing apparatus of one embodiment of the present invention. The figure which shows the susceptor in 1 aspect of this invention. 4A and 4B illustrate a manufacturing process of a semiconductor device according to one embodiment of the present invention. The figure which shows the position dependence of the wafer w temperature at the time of epitaxial film formation in 1 aspect of this invention. The figure which shows the position dependence of the wafer w temperature at the time of epitaxial film formation in a comparative example. The elements on larger scale of the susceptor in 1 aspect of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Reaction chamber 12 ... Gas supply port 13 ... Gas discharge port 14 ... Current plate 15 ... Rotation drive mechanism 16 ... Susceptor 17a ... Inheater 17b ... Outheater 18 ... Reflector 19 ... Push-up pin 21 ... Inner susceptor 22 ... Mid susceptor 23 ... Outer susceptor

Claims (5)

An annular first susceptor part on which a wafer is placed;
A circular first recess for holding the wafer, an annular second recess formed in the first recess and accommodating the first susceptor part without protruding or sinking, and A susceptor comprising a second susceptor part formed in a second recess and having a plurality of openings shielded by the first susceptor part.   2. The susceptor according to claim 1, wherein the wall surfaces of the first susceptor part and the second recess have a taper.   The susceptor according to claim 1, further comprising a third susceptor part that holds the second susceptor part on an outer periphery thereof. A reactor into which the wafer is introduced;
A gas supply mechanism for supplying process gas to the reactor;
A gas discharge mechanism for discharging gas from the reactor;
An annular first susceptor part on which the wafer is placed, a circular first concave part for holding the wafer, and a first susceptor part that protrudes from the first concave part. An annular second recess for storing without being depressed, and a susceptor having a second susceptor part formed in the second recess and having a plurality of openings shielded by the first susceptor part;
A heater for heating the wafer from a lower part of the susceptor;
A rotation mechanism for rotating the wafer;
A semiconductor manufacturing apparatus comprising a vertical drive mechanism for raising and lowering the first susceptor part. Bring wafers into the reactor,
An annular first susceptor part, which is installed in the reaction furnace and is used for mounting the wafer, is placed in a circular first recess formed in the second susceptor part for holding the wafer. The wafer is placed on the first susceptor part by being raised by a push-up pin that penetrates an opening formed in the provided annular second recess,
Lowering the first susceptor part, storing the first susceptor part in the second recess without protruding or sinking, and shielding the opening formed in the second recess, Holding the wafer in the first recess;
Heating the wafer through the first susceptor part and the second susceptor part;
Rotate the wafer,
A semiconductor manufacturing method, wherein a process gas is supplied onto the wafer.

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