JP2009135258A - Suscepter support shaft, and epitaxial growth system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suscepter support shaft capable of reducing or preventing deformation even when used over a long time in a high-temperature environment. <P>SOLUTION: In this suscepter support shaft 30, three braces 32 are not only fixed and supported to a principal post 31 at a tip of the principal post 31 but also supported to one another by being connected to one another by reinforcing members 34. That is to say, each brace is supported at two parts such as the connection part to the principal post 31 and the connection part to the reinforcing members 34. Accordingly, strength against a mechanical load on the braces 32 is considerably improved, and deformation of the braces 32 can be prevented even when the suscepter support shaft is used over a long time for executing an epitaxial growth process to a large quantity of wafers W in a high-temperature environment for carrying out epitaxial growth. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a structure of a susceptor support shaft provided to support a susceptor on which a wafer is placed in a single wafer type epitaxial growth apparatus for growing an epitaxial film on the surface of a semiconductor wafer such as a silicon wafer, and in particular, a modification thereof. The present invention relates to a susceptor support shaft capable of reducing the above and an epitaxial growth apparatus capable of forming an epitaxial film having a stable quality by including the susceptor support shaft.

  In recent years, as a silicon wafer for MOS devices, a single crystal silicon thin film having a high resistivity in which a dopant having a lower concentration than that of the wafer is added to the surface of a low resistivity silicon wafer having a high concentration of dopant. An epitaxial wafer obtained by vapor-phase growth of an (epitaxial film) is used. This epitaxial wafer has excellent characteristics such as an improvement in the yield of the gate oxide film of the MOS device, a reduction in parasitic capacitance, prevention of soft errors, and an improvement in gettering ability.

  Conventionally, in the production of this epitaxial wafer, a batch processing type epitaxial growth apparatus that performs epitaxial growth simultaneously on a plurality of silicon wafers has been used. However, a batch processing type epitaxial growth apparatus is difficult to cope with an increase in the diameter of a silicon wafer. Therefore, in recent years, a single wafer type epitaxial growth apparatus is mainly used. Recently, a large-diameter single wafer epitaxial growth apparatus capable of performing epitaxial growth on a wafer having a diameter of 300 mm or more has been developed.

  This single wafer type epitaxial growth apparatus is roughly classified into two types according to the wafer transfer system between the transfer jig for transferring the wafer to the apparatus and the susceptor. One is a type in which the wafer is transferred by the Bernoulli method or the raising / lowering method of the conveying jig, and the other is a type in which the lower surface of the wafer is supported by pins and transferred by raising / lowering the pins.

A conventional general single wafer epitaxial growth apparatus of the latter type will be described with reference to FIG.
As shown in FIG. 5, in the epitaxial growth apparatus 80, an epitaxial film forming chamber 14 is formed surrounded by the upper dome 11, the lower dome 12, and the dome attachment body 13. For the epitaxial film forming chamber 14, a gas supply port 21 and a gas discharge port 22 for supplying and discharging a reactive gas are formed at positions facing the side surfaces.

A susceptor 15 on which the wafer W is placed is disposed in the epitaxial film forming chamber 14. The susceptor 15 is fitted and supported at the outer periphery of the lower surface thereof by a susceptor support shaft 90 connected to the susceptor rotating portion 23, and rotates with the susceptor support shaft 90. The susceptor 15 has a through hole through which a lift pin 19 for moving the wafer W up and down is passed. The lift pins 19 are supported by the wafer lift 20 and are lifted and lowered.
A plurality of heating lamps 18 are disposed above the upper dome 11 and below the lower dome 12, respectively, and thereby a susceptor 15 disposed in the epitaxial film forming chamber 14 and a wafer placed on the susceptor 15. W is heated.

  In such an epitaxial growth apparatus 80, a reactive gas is supplied from the gas supply port 21 into the epitaxial film forming chamber 14. An epitaxial film is grown on the surface of the wafer W when the supplied reaction gas passes through the surface of the wafer W placed on the susceptor 15 while the wafer W is heated to a predetermined temperature by the heating lamp 18. The The supplied reaction gas is discharged from the gas discharge port 22 to the outside of the epitaxial growth apparatus 80.

In this type of epitaxial growth apparatus, there is also disclosed an apparatus in which a plurality of gas supply ports and gas discharge ports are provided in an epitaxial film forming chamber so that gas passes through the front surface and the back surface of a wafer placed on a susceptor. For example, see Patent Document 1). In this epitaxial growth apparatus, a reactive gas is supplied to the front surface of the wafer and only a carrier gas is supplied to the back surface of the wafer to perform an epitaxial growth process. Thereby, an epitaxial film can be formed without forming a protective film on the back surface of the wafer, and the epitaxial wafer can be manufactured at low cost. In addition, the influence of autodoping from the back surface of the wafer can be eliminated, and the uniformity of the dopant concentration in the epitaxial film surface can be improved.
JP 2003-197532 A

In the conventional general epitaxial growth apparatus 80 illustrated with reference to FIG. 5, the susceptor 15 on which the wafer W is placed is supported by a susceptor support shaft 90 shown in FIG.
As shown in the figure, the susceptor support shaft 90 has a structure in which three pillars (arms) 92 are provided so as to extend radially in the horizontal direction from the tip of the main pillar 91 (end on the epitaxial film forming chamber 14 side). is there. Each support column 92 is provided so as to be inclined in the direction of the susceptor 15 (tilt upward), and a pin 93 is provided at the tip (the end opposite to the fixed portion with the main column 91). Is done. The pin 93 engages with a predetermined portion of the outer peripheral portion of the lower surface of the susceptor 15 to support the susceptor 15 so as to be movable up and down.
As shown in FIG. 5, the susceptor support shaft 90 supports the susceptor 15 with the support column 92 that is a rod-shaped member, as shown below the epitaxial film forming chamber 14 (below the lower dome 12). This is because it is necessary to heat the susceptor 15 by the heating lamp 18.

However, in the susceptor support shaft 90 having such a configuration, the support column 92 may be deformed with time.
Since epitaxial growth is normally performed in a high temperature atmosphere of 1000 ° C. or higher, the susceptor support shaft 90 is also disposed and used in such a high temperature environment in the epitaxial film forming chamber 14. In an actual epitaxial wafer production line, a large amount of wafers are sequentially processed by an epitaxial growth apparatus. On the other hand, in the epitaxial growth apparatus 80, as described above, in order to increase the heating efficiency from the heating lamp 18 disposed below the epitaxial film forming chamber 14, the support column 92 is formed of a thin rod-shaped member.

As a result, when the epitaxial growth apparatus 80 is continuously used and, for example, about tens of thousands of wafers are processed, the support column 92 may be deformed so as to be slightly lowered as shown by an arrow in FIG. is there.
If the support column 92 is deformed, the susceptor 15 is displaced, or the susceptor 15 is tilted and supported, which may reduce the quality of the formed epitaxial film. Further, when the deformation of the support column 92 is large, the susceptor support shaft 90 may interfere with surrounding constituent members.

The present invention has been made in view of such problems, and its object is to reduce or prevent deformation even when used for a long period of time in a high temperature environment, and to maintain the susceptor in a desired state for a longer period of time. It is an object of the present invention to provide a susceptor support shaft that can be stably supported by this, and can stably form a high-quality epitaxial film on a substrate placed on the susceptor.
Another object of the present invention is to reduce or prevent the susceptor support shaft from changing over time, and to stably support the susceptor in a desired state over a long period of time, whereby the susceptor support shaft is placed on the susceptor. Another object of the present invention is to provide an epitaxial growth apparatus that can stably form a high-quality epitaxial film on a substrate.

In order to solve the above problems, a susceptor support shaft according to the present invention is a main column and a plurality of columns supporting the susceptor, each of which is a plurality of columns connected to the main column at a predetermined location; Each of the plurality of support columns is connected to the support column at a location different from the connection location of the support column to the main column, and is connected to another member other than the support column at a location different from the connection location with the support column. And a reinforcing member.
A susceptor support shaft characterized by that.

  In such a susceptor support shaft, each support column is connected to the reinforcing member at a location different from the location connected to the main column. This reinforcing member is connected to another member at a location different from the connection location with the support column. As a result, each support column is connected to the other member via the reinforcement member at a location different from the connection location with the main column. It will be supported by the member. That is, each support column is supported at two locations: a connection location with the main pillar and a connection location with the reinforcing member. As a result, compared to a state where the main column is connected to the main column at one place, mechanical strength is increased, resistance to load is increased, and deformation can be prevented or greatly reduced.

Preferably, the reinforcing member has a plurality of members that connect the plurality of support columns to each other.
Preferably, the reinforcing member has a plurality of members that connect each of the plurality of support columns to the main column.

  The epitaxial growth apparatus according to the present invention is an epitaxial growth apparatus having a susceptor on which a substrate on which an epitaxial film is to be formed is placed, and a susceptor support shaft that supports the susceptor, wherein the susceptor support shaft includes: A plurality of struts for supporting the susceptor, each of the plurality of struts connected to the main pillar at a predetermined location, and for each of the plurality of struts, a place where the main pillar of the strut is connected Has a reinforcing member connected to the support column at a different location and connected to another member other than the support column at a location different from the connection location with the support column.

According to the present invention, deformation can be reduced or prevented even when used in a high temperature environment for a long period of time, and the susceptor can be stably supported in a desired state for a longer period of time, thereby being mounted on the susceptor. It is possible to provide a susceptor support shaft capable of stably forming a high-quality epitaxial film on a placed substrate.
In addition, the aging of the susceptor support shaft can be reduced or prevented, and the susceptor can be stably supported in a desired state over a long period of time, whereby a high-quality epitaxial layer can be formed on the substrate placed on the susceptor. An epitaxial growth apparatus that can stably form a film can be provided.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram schematically showing a configuration of an epitaxial growth apparatus according to an embodiment of the present invention.
An epitaxial growth apparatus 10 shown in FIG. 1 is a single wafer epitaxial growth apparatus of a type in which a wafer lower surface is supported by a pin and transferred.

The epitaxial growth apparatus 10 includes an upper dome 11, a lower dome 12, and a dome mounting body 13, and an epitaxial film forming chamber 14 is formed as a space surrounded by these. The upper dome 11 and the lower dome 12 are made of a transparent material such as quartz.
A susceptor 15 on which the wafer W is placed is disposed inside the epitaxial film forming chamber 14.
A plurality of heating lamps 18 (for example, halogen lamps) are disposed above and below the epitaxial film forming chamber 14, respectively.

The susceptor 15 is formed of, for example, a material in which a surface of a carbon base material is coated with a SiC film, and is configured to support the entire back surface of the wafer W. Specifically, for example, a disk-shaped susceptor 15a shown in FIG. 2A or a concave susceptor 15b formed with a countersink 16 into which a wafer W shown in FIG. 2B is inserted is used. Is done.
As shown in FIGS. 2 (A) and 2 (B), lift pins 19 for raising and lowering the wafer W are provided on the wafer W mounting surface of the susceptor 15 (including the susceptors 15a and 15b). Through holes 17a and 17b for passing therethrough are formed.
The lower portion of the lift pin 19 is supported by the lift of the wafer lift 20, and the lift pin 19 is lifted and lowered in accordance with the lift of the wafer lift 20 while being supported by the wafer lift 20.

The susceptor 15 rotates with the outer peripheral portion of the lower surface engaged and supported by the susceptor support shaft 30 according to the present invention.
The configuration of the susceptor support shaft 30 will be described with reference to FIG.
As shown in FIG. 3, the susceptor support shaft 30 includes a main column 31, three columns 32, three pins 33, and three reinforcing members 34.
The main column 31 is a cylindrical bar-like member that supports the susceptor support shaft 30 and the entire susceptor 15 mounted thereon.
As shown in FIG. 1, the main pillar 31 is disposed so that one end protrudes below the lower dome 12. The lower end of the main column 31 is connected to the susceptor rotating unit 23. Thereby, the main pillar 31 is rotated with the longitudinal direction as the rotation axis direction and the direction as indicated by the arrow in FIG. 3 as the rotation direction.

Three struts 32 are installed at the end (tip) of the main pillar 31 on the epitaxial film forming chamber 14 side. Each column 32 has one end fixed to the tip of the main column 31 and is installed so as to incline in the direction of the susceptor 15 and extend obliquely upward (see FIG. 1). A pin 33 is installed at the other end of each column 32, thereby supporting the susceptor 15.
Further, as shown in FIG. 3, the tip portions of the three support columns 32 are connected to each other by a reinforcing member 34. That is, the susceptor support shaft 30 has three reinforcing members 34 arranged in an equilateral triangle shape that connects the tips of the columns 32.

  Further, the epitaxial growth apparatus 10 is provided with a gas supply port 21 for supplying a reactive gas to the epitaxial film forming chamber 14 and a gas exhaust port 22 for discharging the reactive gas from the epitaxial film forming chamber 14. From the gas supply port 21, for example, a reaction gas obtained by diluting a Si source such as SiHCl 3 with hydrogen gas and mixing a trace amount of dopant thereto is supplied.

  In the epitaxial growth apparatus 10 having such a configuration, the wafer W for epitaxial growth is placed on the susceptor 15 and placed in the epitaxial film forming chamber 14. The susceptor 15 is supported by a susceptor support shaft 30 as shown in FIG. 3, and the susceptor support shaft 30 is rotated by a susceptor rotating portion 23. Thereby, the wafer W is rotated integrally with the susceptor 15 in a plane parallel to the growth surface of the epitaxial film.

In this state, the heating lamp 18 is operated to heat the susceptor 15 in the epitaxial film forming chamber 14 and the wafer W placed on the susceptor 15 through the upper dome 11 and the lower dome 12.
Then, a reactive gas is supplied from the gas supply port 21 into the epitaxial film forming chamber 14. The reaction gas supplied into the epitaxial film forming chamber 14 passes through the surface of the wafer W placed on the susceptor 15 and grows an epitaxial film on the surface of the wafer W, and then the outside of the epitaxial growth apparatus 10 through the gas discharge port 22. To be discharged.

  And in the susceptor support shaft 30 of such an epitaxial growth apparatus 10, as shown in FIG. 3, not only the support | pillar 32 is fixed to the main pillar 31 by the front-end | tip part of the main pillar 31, but is supported, The reinforcing members 34 are connected to each other and supported by each other. That is, the support column 32 is supported at two locations: a connection location with the main pillar 31 and a connection location with the reinforcing member 34. Accordingly, the strength of the support 32 against the mechanical load is considerably improved and strengthened, and the epitaxial growth process is performed on a large amount of wafers W over a long period of time even in a high temperature environment where epitaxial growth is performed. Even if it is used, the deformation of the column 32 can be prevented. Even if the support column 32 is deformed, it is possible to lengthen the period until the support 32 is deformed and increase the number of wafers on which epitaxial growth processing is performed up to that period. Further, the degree of deformation can be reduced.

  Further, by preventing or reducing the deformation of the susceptor support shaft 30, it is possible to prevent the susceptor 15 or the wafer W placed on the susceptor 15 from being inclined or displaced. As a result, the wafer W to be epitaxially grown can be stably supported in a desired state, and a high quality epitaxial film can be stably formed on the wafer W.

  In addition, this embodiment is described in order to make an understanding of this invention easy, and does not limit this invention at all. Each element disclosed in the present embodiment includes all design changes and equivalents belonging to the technical scope of the present invention, and various suitable modifications can be made.

For example, the configuration of the susceptor support shaft 30 is not limited to the configuration shown in FIG.
FIG. 4 shows another configuration example of the susceptor support shaft according to the present invention.
The basic configuration of the susceptor support shaft 30b shown in FIG. 4 is the same as that of the susceptor support shaft 30 described above with reference to FIG. That is, three support columns 32 are provided to be inclined in the direction of the susceptor 15 in a radial direction with respect to the main column 31b. Pins 33 are provided at the tip portions of these support columns 32. When the pins 33 engage with the susceptor 15, the susceptor 15 is supported so as to be rotatable and liftable.

However, the susceptor support shaft 30b shown in FIG. 4 is different from the susceptor support shaft 30 shown in FIG.
First, in the susceptor support shaft 30b, the main column 31b extends further in the direction of the susceptor 15 from the fixed portion of the support column 32. In other words, the support column 32 is fixed to an inner (lower) portion where the tip is left by a predetermined length, not the tip of the main column 31b. As a result, the main column 31b is configured to protrude from the fixed portion of the column 32 to the susceptor 15 side. In addition, the extended part of this support | pillar 32b is called the protrusion part 35. FIG.

In the susceptor support shaft 30b, the protruding portion 35 and a predetermined portion near the tip end portion (the end portion on which the pin 33 is provided) of each of the three columns 32 are connected by the reinforcing member 36.
As a result, each support column 32 is supported at two locations by the main column 31b and the reinforcing member 36, like the susceptor support shaft 30 illustrated in FIG. Therefore, also in the susceptor support shaft 30b, the mechanical strength of the support column 32 is increased, and resistance to load is improved and enhanced.
In addition, the protrusion part 35 of the main pillar 31b is formed in the length which the front-end | tip part does not contact the susceptor 15.
The configuration of the susceptor support shaft may be such a configuration, for example, or may be a configuration different from these.

In addition, the susceptor support shafts 30 and 30b illustrated in FIGS. 3 and 4 are each configured to have three support columns 32, but may be four or more.
Further, the configuration of the epitaxial growth apparatus is not limited to the configuration illustrated in FIG. 1, and may be an arbitrary configuration.

FIG. 1 is a diagram showing an epitaxial growth apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a susceptor of the epitaxial growth apparatus shown in FIG. FIG. 3 is a view showing an example of a susceptor support shaft of the epitaxial growth apparatus shown in FIG. FIG. 4 is a view showing another example of the susceptor support shaft of the epitaxial growth apparatus shown in FIG. FIG. 5 is a diagram showing a conventional epitaxial growth apparatus. 6 is a diagram showing an example of a susceptor support shaft of the epitaxial growth apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,80 ... Epitaxial growth apparatus 11 ... Upper dome 12 ... Lower dome 13 ... Dome attachment body 14 ... Epitaxial film formation chamber 15 ... Susceptor 16 ... Countersink part 17 ... Through-hole 18 ... Heating lamp 19 ... Lift pin 20 ... Wafer lift 21 ... Gas supply port 22 ... Gas discharge port 23 ... Susceptor rotation shaft 30, 90 ... Susceptor support shaft 31, 91 ... Main pillar 32, 92 ... Post 33, 93 ... Pin 34, 36 ... Reinforcement member 35 ... Main pillar protrusion

Claims (4)

The main pillar,
A plurality of supports supporting the susceptor, each of which is connected to the main pillar at a predetermined location;
Each of the plurality of support columns is connected to the support column at a location different from the connection location of the support column to the main column, and is connected to another member other than the support column at a location different from the connection location with the support column. A susceptor support shaft comprising: a reinforcing member.   The susceptor support shaft according to claim 1, wherein the reinforcing member includes a plurality of members that connect the plurality of support columns to each other.   2. The susceptor support shaft according to claim 1, wherein the reinforcing member includes a plurality of members that connect the plurality of support columns to the main column. 3. An epitaxial growth apparatus having a susceptor on which a substrate on which an epitaxial film is to be formed is placed, and a susceptor support shaft that supports the susceptor,
The susceptor support shaft is
The main pillar,
A plurality of supports supporting the susceptor, each of which is connected to the main pillar at a predetermined location;
Each of the plurality of support columns is connected to the support column at a location different from the connection location of the support column to the main column, and is connected to another member other than the support column at a location different from the connection location with the support column. An epitaxial growth apparatus comprising: a reinforcing member.

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