JPH09115846A - Heat treatment system for semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a noxious gas generated in a process chamber from leaking through a gap at the outer circumferential part of an elevating/lowering rod to the outside of a system surely by employing a hydrostatic bearing for supporting the elevating/lowering rod and composing the sliding face therefor of quartz or silicon carbide. SOLUTION: Means for elevating/lowering a semiconductor wafer supported by a wafer support comprises an elevating/lowering rod 31 for bearing the wafer support, a hydrostatic bearing for supporting the rod 31 such that it can ascend/descend freely, and a driver for elevating/lowering the rod 31. A coating layer D of silicon carbide is formed on the inner circumferential surface of the sleeve 32b of hydrostatic bearing. The coating layer D is formed by chemical deposition with high density and the thickness thereof is set at 100-500μm. High density quartz may be substituted for silicon carbide in the formation of coating layer D on the sleeve 32b of hydrostatic bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer heat treatment apparatus used for forming an annealed oxide film, diffusing impurities, and forming a vapor deposition film in a semiconductor wafer manufacturing process. Regarding

[0002]

2. Description of the Related Art Conventionally, in the manufacturing process of semiconductor wafers, annealing, phosphorus,
A heat treatment apparatus having a rapid heating furnace is used for diffusion of impurities such as arsenic, formation of an oxide film, and chemical vapor deposition.
As one of the heat treatment apparatuses, there is provided one that heats semiconductor wafers one by one in a horizontally supported state (for example, see Japanese Patent Laid-Open No. 14514/1990).

In this type of heat treatment apparatus, a wafer support for horizontally supporting a semiconductor wafer supplied into a process chamber, and this wafer support via an elevating rod made of a quartz tube (quartz tube). The semiconductor wafer supported by the wafer support is transferred from the loading position to the heating chamber by performing the predetermined heat treatment by elevating the wafer support through the elevating rod. It can be performed. Further, when the heating process is completed, the elevating rod is lowered to return the semiconductor wafer to the loading position again so that the semiconductor wafer can be taken out from the process chamber.

In the above conventional heat treatment apparatus, the elevating rod is a slide bearing which also serves as a seal member.
It is supported so that it can be raised and lowered and rotated. This slide bearing is a hollow ring made of fluororesin, in which a ring-shaped coil spring for applying a tightening force is embedded, and the slide rod is slidably supported and the process is performed. The harmful gas generated in the chamber is prevented from leaking through the gap in the outer peripheral portion of the lifting rod. The plain bearing is water-cooled so as not to overheat.

However, in the above conventional heat treatment apparatus, since it is necessary to process the semiconductor wafer at a high temperature of about 1200 ° C., the above slide bearing is about 200 ° C. even though it is water-cooled. To be heated. Therefore, the abrasion resistance is deteriorated, and abrasion powder is generated by sliding contact with the elevating rod, and the abrasion powder enters the process chamber to contaminate the semiconductor wafer. Also, due to the wear of the plain bearing,
The sealing property is deteriorated, and the harmful gas generated in the process chamber may leak through the gap in the outer peripheral portion of the elevating rod.

Therefore, it has been attempted to support the lifting rod by a hydrostatic bearing so as to be lifted and lowered. However, even in this static pressure bearing, since sliding contact with the lifting rod is unavoidable, the sliding contact surface may be worn, and abrasion powder may enter the process chamber and contaminate the semiconductor wafer. . Particularly, the sliding contact surface of the hydrostatic bearing with respect to the lifting rod is SUS304, SUS3.
16, SUS316L, and other heat- and corrosion-resistant stainless steels, and the wear powder contains heavy metals such as Fe, Ni, and Cr, so that the semiconductor wafer is contaminated by these heavy metals. Therefore, there is a possibility of causing a serious defect that the lifetime of the semiconductor is shortened.

The present invention has been made in view of the above problems, and includes an elevating rod for supporting a wafer support,
An object of the present invention is to provide a semiconductor wafer heat treatment apparatus capable of preventing the semiconductor wafer from being contaminated by abrasion powder generated by sliding contact with a bearing supporting the lifting rod. Further, the present invention provides a semiconductor wafer heat treatment apparatus capable of reliably preventing harmful gas generated in the process chamber from leaking out of the apparatus through a gap in the outer peripheral portion of the elevating rod. To aim.

[0008]

To achieve the above object, a semiconductor wafer heat treatment apparatus according to the present invention comprises a wafer support for horizontally supporting a semiconductor wafer, and a lifting rod for supporting the wafer support. A semiconductor having a bearing for supporting the elevating rod so that the elevating rod can be moved up and down, and elevating means for elevating the wafer support through the elevating rod and transferring the semiconductor wafer supported by the wafer support to the heating chamber. In the wafer heat treatment apparatus, the bearing is composed of a hydrostatic bearing, and the sliding contact surface with respect to the elevating rod is composed of quartz or silicon carbide.

According to the semiconductor wafer heat treatment apparatus having the above-mentioned structure, since the bearing for supporting the lifting rod is composed of the static pressure bearing, wear due to sliding contact with the lifting rod is prevented.
It can be significantly reduced compared to the conventional plain bearing. Moreover, the sliding contact surface of the hydrostatic bearing with respect to the lifting rod is made of quartz or silicon carbide, and the amount of heavy metal contained in the abrasion powder generated by the sliding contact with the lifting rod is very small. Heavy metal contamination of the wafer can be effectively prevented. Also, the harmful gas leaked from the inside of the process chamber to the static pressure bearing side through the gap in the outer peripheral portion of the lifting rod is collected together with the purge gas which is discharged after being supplied to the static pressure bearing to support the small hole rod. You can

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 is a schematic sectional view showing one embodiment of the semiconductor wafer heat treatment apparatus of the present invention. This heat treatment apparatus includes a rapid heating furnace 1 for heating a semiconductor wafer W and a process chamber C.
A wafer support 2 for supporting a semiconductor wafer W inside the chamber, an elevating means 3 for elevating and lowering the semiconductor wafer W supported by the wafer support 2, and a wafer support 2
A handling part 4 for supplying the semiconductor wafer W to the wafer support or taking out the semiconductor wafer W from the wafer support 2 and a control part 5 for controlling the driving of the elevating part 3 and the handling part 4 and the like constitute a main part. There is.

In the rapid heating furnace 1, a heater 12 is arranged on the outer periphery of an upper portion of a tubular body 11 which constitutes a process chamber C, and an intermediate portion of the tubular body 11 is covered with a heat insulating material 13. . The cylindrical body 11 is made of quartz, SiC, or the like, and has an upper part closed and a lower part opened. The lower opening of the cylindrical body 11 communicates with a transfer chamber B in which the handling means 4 is configured, and the bottom of the transfer chamber B is a bottom plate B.
It is blocked by 1. The upper part of the process chamber C is configured as a heating chamber A.

As shown in detail in FIG. 4, the wafer support 2 is formed on a flat substrate 21 made of quartz, SiC, or the like.
A plurality of support pins 22 made of quartz are erected. The height of each support pin 22 is set uniformly so that the semiconductor wafer W can be supported horizontally. The lower end of the support pin 22 is fixed to the base 21.

The elevating means 3 is the wafer support 2
An elevating rod 31 for supporting the elevating rod 31, a static pressure bearing 32 for supporting the elevating rod 31 so as to be able to elevate and lower, and an elevating drive unit 33 for elevating the elevating rod 31. The elevating rod 31 is made of a quartz tube, and its upper end is connected to the bottom surface of the base 21 of the wafer support 2.

As shown in detail in FIG. 1, the hydrostatic bearing 32 is provided with a sleeve 32b slidably contacting the elevating rod 31 inside a casing 32a attached to the bottom plate B1. A gap S is formed between the rod 31 and the rod 31 for circulating the purge gas. The annular groove 3 is formed on the outer circumference of the sleeve 32b.
2c is formed, and on the peripheral surface of the annular groove 32c,
A plurality of small holes 32d that communicate the annular groove 32c and the gap S are formed. The small holes 32d are formed at equal intervals along the circumference of the upper and lower two rows (upper and lower eight positions in the illustrated example), and the upper small hole 32d and the lower small hole 32d.
And are formed in a state where their phases are shifted from each other (see FIGS. 6 and 7).

Further, the casing 32a is formed with a gas supply port 32e for supplying purge gas to the annular groove 32c of the sleeve 32b, and is supplied to a gap S between the elevating rod 31 and the sleeve 32b. A gas discharge port 32f for discharging the purged gas is formed. A water passage 32h for circulating cooling water is formed in the casing 32a. An O-ring 32g is interposed between the casing 32a of the hydrostatic bearing 32 and the bottom plate B1 to prevent the gas in the process chamber C and the purge gas from leaking out of the apparatus. Nitrogen gas is used as the purge gas.

A coating layer D made of silicon carbide is formed on the inner peripheral surface of the sleeve 32b of the hydrostatic bearing 32, that is, on the sliding contact surface X with the elevating rod 31 (see FIG. 3). The coating layer D has a high density formed by chemical vapor deposition and has a thickness of 100
It is set to ˜500 μm.

Referring to FIG. 2, an elevating / lowering drive unit 33 for vertically moving the elevating / lowering rod 31 includes a motor 33a and a spiral gear 3 rotationally driven by the motor 33a.
3b and the lower end of the elevating rod 31 are connected to each other, and the elevating member 33c is screwed to the spiral gear 33b.
And a guide rod 3 for guiding the raising and lowering of the raising and lowering member 32c.
3d, an encoder 33e for controlling the lifting stroke of the lifting rod 31, and the like. Further, the elevating means 3 also includes a rotation drive mechanism for rotating the elevating rod 31.

The handling means 4 forms a plurality of grooves 42 on the contact surface side of the tip of the robot arm 41 which can swivel in the horizontal direction with the back surface (lower surface) of the semiconductor wafer W, and further the grooves 42 are formed in the grooves 42. The semiconductor wafer W is vacuum-sucked by forming a small hole 43 penetrating the arm portion and communicating with the vacuum pump (see FIGS. 4 and 5). Two
Can be supplied onto the support pins 22 or the semiconductor wafer W which has been subjected to the heat treatment can be taken out from the support pins 22.

With the above construction, since the lifting rod 31 is supported by the hydrostatic bearing 32, the lifting rod 3
The wear of the sliding contact surface X of the hydrostatic bearing 32 due to the sliding contact with 1 can be significantly reduced as compared with the conventional sliding bearing. Moreover, since the sliding contact surface X of the hydrostatic bearing 32 is made of high-density silicon carbide (Fe0.04 ppm, Cr 0.01 ppm or less) containing very little heavy metal as an impurity, the lifting rod 31 The amount of heavy metal contained in the abrasion powder generated by sliding contact with is very small. Therefore, it is possible to effectively prevent the semiconductor wafer from being contaminated by the heavy metal and shortening the lifetime of the semiconductor.

Further, the sleeve 32b and the elevating rod 3
A part of the purge gas supplied between
Although it is discharged to the atmosphere through the gas, most of the gas is discharged through the gas discharge port 32f and collected.
The toxic gas leaked from the inside of the process chamber C to the static pressure bearing 32 side through the gap in the outer peripheral portion of the elevating rod 31 can also be discharged and collected through the gas discharge port 32f. Therefore, it is possible to reliably prevent the toxic gas from leaking to the outside of the device. Further, the gas pressure of the purge gas supplied between the sleeve 32b and the elevating rod 31 can prevent the poisonous gas in the process chamber C from leaking to the static pressure bearing 32 side. In addition,
The toxic gas discharged from the discharge port 32f together with the purge gas is collected in a state of being separated from the purge gas by a dedicated collecting device.

The coating layer D formed on the sleeve 32b of the hydrostatic bearing may be made of high-density quartz instead of silicon carbide, and in this case also, since heavy metals as impurities are small ( Fe0.05pp
m), it is possible to effectively prevent the semiconductor wafer W from being contaminated by heavy metal caused by sliding contact with the elevating rod 31. Further, instead of forming the coating layer D, the sleeve 32b may be entirely formed of quartz or silicon carbide.

[0022]

As described above, according to the semiconductor wafer heat treatment apparatus of the present invention, since the bearing for supporting the lifting rod is composed of the static pressure bearing, the wear caused by the sliding contact with the lifting rod is prevented. The sliding contact surface of the hydrostatic bearing with respect to the elevating rod is made of quartz or silicon carbide having an extremely low content of heavy metal. It is possible to prevent the semiconductor wafer from being contaminated with heavy metals due to the abrasion of the surface. Therefore, it is possible to effectively prevent the lifetime of the semiconductor from being shortened. The semiconductor wafer heat treatment apparatus of the present invention can also reliably prevent harmful gas generated in the process chamber from leaking out of the apparatus through the gap in the outer peripheral portion of the elevating rod.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydrostatic bearing equipped in a semiconductor wafer heat treatment apparatus of the present invention.

FIG. 2 is a schematic cross-sectional view showing the entire heat treatment apparatus.

FIG. 3 is a cross-sectional view showing details of a sliding contact surface of a hydrostatic bearing.

FIG. 4 is a cross-sectional view of a wafer support.

FIG. 5 is a perspective view of a main part of the handling device.

FIG. 6 is a sectional view taken along line VI-VI of FIG. 1;

FIG. 7 is a sectional view taken along line VII-VII of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rapid heating furnace 2 Wafer support 3 Elevating means 31 Elevating rod 32 Static pressure bearing W Semiconductor wafer A Heating chamber D Coating layer X Sliding contact surface

Claims (1)

[Claims] 1. A wafer supporting body for horizontally supporting a semiconductor wafer, an elevating rod for supporting the wafer supporting body, and a bearing for supporting the elevating rod so as to be movable up and down. In a heat treatment apparatus for a semiconductor wafer, which comprises an ascending / descending means for elevating the semiconductor wafer supported by the wafer support to a heating chamber, the bearing is constituted by a static pressure bearing, and the bearing is slid on the ascent / descent rod. A heat treatment apparatus for a semiconductor wafer, wherein the contact surface is made of quartz or silicon carbide.