JP3265498B2 - Vertical furnace for semiconductor wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer vertical furnace for embedding and diffusing impurities into a semiconductor wafer such as a silicon wafer or forming a CVD film by a chemical vapor deposition method under reduced pressure. About.

[0002]

2. Description of the Related Art Conventionally, as a vertical furnace for semiconductor wafers of this type, a furnace body having a vertical furnace core tube, a groove or the like which is inserted into the furnace core tube and horizontally supports the semiconductor wafer therein is provided. A quartz or silicon boat provided with the edges spaced at equal intervals in the vertical direction, and an arm for supporting the semiconductor wafer, rotatable about a vertical axis, vertically movable and horizontally movable, 2. Description of the Related Art There is known a device provided with a wafer transfer robot for transferring a semiconductor wafer between wafer cassettes.

[0003]

However, in a conventional vertical furnace for semiconductor wafers, film formation or diffusion is performed on both surfaces of the semiconductor wafer, so that the following inconvenience occurs in a subsequent process. (1) In forming the poly-Si film, a contact portion between the boat and the semiconductor wafer remains as a step. For this reason, when this surface is mirror-polished in a later step, there is a problem that a step portion remains as a pit-shaped projection. (2) In the impurity buried diffusion of the bipolar substrate, the impurities are also diffused on the back surface of the semiconductor wafer. However, when the epitaxial growth is performed in the next step (a single crystal silicon thin film is formed by vapor phase growth on the wafer surface after diffusion) During this process, the impurities that have been diffused on the back surface diffuse again into the gas phase, and then reach the wafer surface, whereupon the auto-doping phenomenon is remarkably diffused into the substrate, which adversely affects the wafer characteristics. In addition, various measures are taken in the epitaxial process to prevent the auto-doping, and there is a problem that productivity is reduced. In order to eliminate such inconvenience, that is, film formation or diffusion on both sides, it is conceivable to use a wafer charging method of mounting a semiconductor wafer on a flat plate and performing processing, but when using a conventional wafer transfer robot, , It was difficult to respond. Therefore, an object of the present invention is to provide a semiconductor wafer vertical furnace that can automatically transfer a semiconductor wafer and perform film formation, diffusion, and the like on only one side.

[0004]

In order to solve the above problems, a vertical furnace for a semiconductor wafer according to the present invention comprises: a furnace body having a vertical furnace core tube; a boat to be charged into the furnace core tube; A plate body which is horizontally mounted at equal intervals in the vertical direction inside the boat and has a cutout portion opened at the periphery, and is detachably mounted in the cutout portion from above so that the semiconductor is integrally formed with the plate body. It consists of a detachable part that can support wafers, a large number of wafer mounting plates on which semiconductor wafers are mounted, a robot body that can rotate about a vertical axis, can move up and down and move horizontally, a horizontal direction from the robot body Two thin arms that can move back and forth and can support a semiconductor wafer, and can be moved up and down to the robot body so as to be located between these two arms, and move horizontally from the robot body. Possible, the result of the detachable unit from the supportable rectangular frame shape arm, characterized in that it comprises a wafer transfer robot for transferring the semiconductor wafers between the boat and the wafer cassette. The width of the attaching / detaching portion of the wafer mounting plate, the interval between the two thin arms of the wafer transfer robot, and the width of the rectangular frame-shaped arm are as follows: the interval between the two thin arms> the width of the attaching / detaching portion> the width of the rectangular frame-shaped arm. It is preferable to satisfy a wide relationship. Further, it is preferable that the two thin arms and the rectangular frame-shaped arm of the wafer transfer robot have a vacuum chuck.

Here, the boat and the wafer mounting plate are desirably made of quartz, silicon or silicon carbide. The attachment of the wafer mounting plate to the boat is based on the attachment of the two or the detachable fitting or mounting of the wafer mounting plate on a groove or an edge provided in the boat.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1, 2 and 3 are a side view, an elevation view of a main part and an example of an embodiment of a boat with a wafer mounting plate constituting a part of a vertical furnace for semiconductor wafers according to the present invention. FIG. 3 is a sectional view taken along line III-III in FIG. In the drawing, reference numeral 1 denotes a boat made of quartz, silicon, silicon carbide, or the like, which is inserted into a vertical furnace core tube of a furnace body (not shown). It comprises three pillars 2 erected at intervals and a disk-shaped end plate 3 connecting the upper and lower ends of these pillars 2. A number of horizontal plate fitting grooves 4 are formed at equal intervals in the vertical direction inside each of the columns 2 of the boat 1, and these plate fitting grooves 4 are similar to those of the boat 1. A disk-shaped wafer mounting plate 5 made of quartz, silicon, or the like, on which a semiconductor wafer (not shown) is mounted, is attached by fitting the peripheral portions. The wafer mounting plate 5 enables processing on only one side of a semiconductor wafer to be mounted, and includes a disk-shaped plate body 7 having a rectangular notch 6 opened at a peripheral edge, and a notch 6. And a rectangular recessed portion 8 having a flange 8a which is detachably fitted from above and which is engaged with a step 6a at the upper peripheral edge of the notch 6, and which has a circular recess 9 on which a semiconductor wafer is placed. Are formed on the upper surface. Note that the present invention is not limited to the above structure, and as shown in FIG. 7 to be described later, the plate body 7 is horizontally integrated with each support 2 of the boat 1 at equal intervals in the vertical direction. It may be a structure that is joined together.

FIGS. 4, 5 and 6 are front views showing an example of an embodiment of a wafer transfer robot constituting a vertical furnace for semiconductor wafers in combination with the above-mentioned boat with a wafer mounting plate and the like. It is a side view and a plan view. The wafer transfer robot 10 transfers semiconductor wafers between the boat 1 and a wafer cassette (not shown). The wafer transfer robot 10 is rotatable about a vertical axis, and is provided so as to be able to move up and down and move horizontally. The robot body 11 and the front of the robot body above the robot body 11 (FIG. 5)
In the horizontal direction toward the left), two thin arms 12 supporting a semiconductor wafer, and being movable between the two arms 12 so as to be able to ascend and descend to the robot body 11 and to have the robot body A rectangular frame-like arm 13 is provided so as to be able to move forward and backward in the horizontal direction from 11 and supports the attaching / detaching portion 8 of the wafer mounting plate 5. The space between the two thin arms 12 of the wafer transfer robot 10 and the width of the rectangular frame-shaped arm 13 and the width of the attachment / detachment portion 8 of the wafer mounting plate 5 are attached and detached by the rectangular frame-shaped arm 13. Two thin arms 1 to prevent the lifting and lowering of the part 8
It is provided so as to satisfy the following relationship: interval of 2> width of detachable portion 8> width of rectangular frame-shaped arm 13. Further, the two thin arms 12 and the rectangular frame-shaped arm 13 of the wafer transfer robot 10 are provided with a vacuum chuck (not shown) for preventing the semiconductor wafer and the attaching / detaching portion 8 from falling.

In order to perform film formation and diffusion processing on a semiconductor wafer using the vertical furnace for a semiconductor wafer having the above structure, first,
As shown in FIG. 7A, the semiconductor body W is supported by two thin arms 12 after the robot main body 11 of the wafer transfer robot 10 is appropriately operated to face the wafer cassette. Next, as shown in FIG. 7B, the robot body 11 is appropriately operated to face the boat 1, and the two thin arms 12 are positioned above the required wafer mounting plate 5 of the boat 1. After that, both arms 1
The vacuum chuck 2 is turned off. At this time, the rectangular frame-shaped arm 13 is located below the attaching / detaching portion 8 of the wafer mounting plate 5. Next, as shown in FIG. 7 (c), the rectangular frame-shaped arm 13 of the wafer transfer robot 10 is raised to support the attaching / detaching portion 8, and then further raised, as shown in FIG. 7 (d). W stops the rectangular frame-shaped arm 13 at a position away from the two thin arms 12, and thereafter retreats the two thin arms 12 as shown in FIG. 7 (e). Next, FIG.
As shown in (f), when the rectangular frame-shaped arm 13 is lowered, the attaching / detaching portion 8 is fitted into the notch 6 of the plate body 7 and the semiconductor wafer W is placed on the wafer mounting plate 5.
Rectangular frame-shaped arm 1 which is placed in
3 returns to the original position. After the above operation is repeated and the transfer of the semiconductor wafer W from the wafer cassette to the boat 1 is completed, the boat 1 is loaded into the furnace core tube of the furnace body to form a film or diffuse the semiconductor wafer W. Thereafter, the boat 1 is taken out of the furnace core tube, and the semiconductor wafer W is transferred from the boat 1 to the wafer cassette by the wafer transfer robot 10 in a procedure reverse to the operation described above.

[0009]

As described above, according to the vertical furnace for semiconductor wafer of the present invention, the semiconductor wafer supported by the two thin arms of the wafer transfer robot is formed in a rectangular frame shape of the wafer transfer robot. As the arm is raised, the two thin arms are retracted, and the rectangular frame-shaped arm is lowered, the semiconductor wafer is mounted on the wafer mounting plate attached to the boat, so that the semiconductor wafer can be automatically transferred. In addition, film formation, diffusion, and the like can be performed only on one side thereof.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of an embodiment of a boat with a wafer mounting plate constituting a part of a vertical furnace for a semiconductor wafer according to the present invention.

FIG. 2 is a front view of a main part of the boat shown in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a front view showing an example of an embodiment of a wafer transfer robot constituting a part of a vertical furnace for a semiconductor wafer according to the present invention.

FIG. 5 is a side view of the wafer transfer robot of FIG.

FIG. 6 is a plan view of the wafer transfer robot of FIG. 4;

FIGS. 7 (a) to 7 (f) are explanatory views showing processing steps of a semiconductor wafer by a semiconductor wafer vertical furnace according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boat 5 Wafer mounting plate 6 Notch part 7 Plate body 8 Detachable part 10 Wafer transfer robot 11 Robot body 12 Thin arm 13 Rectangular frame arm W Semiconductor wafer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 H01L 21/22 511 H01L 21/31 H01L 21/68

Claims (3)

(57) [Claims] 1. A furnace body having a vertical furnace core tube, a boat to be loaded into the furnace core tube, and a notch which is horizontally mounted at equal intervals in the vertical direction inside the boat and has an opening at the periphery. A plate body having a portion, and a detachable portion which is detachably attached to a notch portion of the plate body from above so as to be able to support a semiconductor wafer integrally with the plate body, and a large number of wafer mounting portions for mounting the semiconductor wafer. A plate, a robot body rotatable about a vertical axis, and capable of moving up and down and moving horizontally, two thin arms capable of moving forward and backward from the robot body and supporting a semiconductor wafer, and between the two arms A rectangular frame-shaped arm that can move up and down on the robot body, move back and forth from the robot body in the horizontal direction, and support the detachable part. And a wafer transfer robot for transferring semiconductor wafers between wafer cassettes. 2. The width of the attachment / detachment portion of the wafer mounting plate, the interval between two thin arms of the wafer transfer robot, and the width of the rectangular frame-shaped arm, the interval between the two thin arms> the width of the attachment / detachment portion> The vertical furnace for a semiconductor wafer according to claim 1, wherein a relation of a width of the rectangular frame-shaped arm is satisfied. 3. The vertical furnace for semiconductor wafers according to claim 1, wherein the two thin arms and the rectangular frame-shaped arms of the wafer transfer robot have vacuum chucks.