JPH0758037A - Heat treatment apparatus for semiconductor wafer - Google Patents

Abstract

PURPOSE:To prevent metal impurity from entering a heat treatment chamber, and hereby improve the yield of semiconductor wafer products as well as the quality of the products by covering an external circumference of the heat treatment chamber with a grannular or powdered polysilicon material that has a property of adsorbing metallic matter. CONSTITUTION:A hollow portion formed between inner and outer tubes 10a and 10b of a furnace tube 10 is filled with a grannular polysilicon material 30. The polysilicon material 30 has a property of adsorbing metallic matter such as Fe, Cr, Ni, and Cu. Accordingly, any metal impurity entering a heat treatment chamber 11 from the outside of the furnace tube 10 is absorbed by the surface of the polysilicon material 30 with which the hollow portion is filled, and is therefore prevented from entering the heat treatment chamber 11. The thickness of the hollow portion is arbitrary, but provided it is too thick, it is deteriorated in its thermal conduction, while provided it is too thin, it is deteriorated in the ability of absorbing metal impurity, so that proper thickness is set taking the thermal conductor and the adsorption performance into consideration. The individual grannular polysilicon material 30 is reduced in its diameter to the utmost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical heat treatment furnace used for manufacturing or processing semiconductor wafers, CVD.
The present invention relates to a semiconductor wafer heat treatment apparatus such as a furnace and an epitaxial growth furnace.

[0002]

2. Description of the Related Art In the process of manufacturing or processing semiconductor wafers, heat treatment work is performed to impart various properties to the semiconductor wafers. In the heat treatment apparatus used for such heat treatment work, a heat treatment chamber is formed inside a furnace core tube or bell jar made of a quartz material. The semiconductor wafer is arranged in the heat treatment chamber, a predetermined processing gas is supplied into the heat treatment chamber, and the semiconductor wafer in the heat treatment chamber is heated by a heater arranged on the outer periphery of the furnace core tube or bell jar. .

[0003]

When metal impurities are mixed in the heat treatment chamber, the semiconductor wafer arranged therein is contaminated with metal components, which accelerates the generation of crystal defects and lowers the product yield. It is known to cause quality deterioration. However, a furnace core tube and a bell jar made of a quartz material have a property of allowing metal impurities such as Cu and Fe existing outside to permeate through the furnace core tube and bell jar even at a high temperature, for example, at a high temperature of 1100 ° C. In particular,
When a reducing or inert atmosphere was formed in the heat treatment chamber, the permeation of metal impurities was remarkable. The present invention has been made in view of such circumstances, and provides a semiconductor wafer heat treatment apparatus capable of eliminating the mixing of metal impurities into the heat treatment chamber, increasing the product yield of semiconductor wafers, and improving the quality. With the goal.

[0004]

To achieve the above object, the present invention provides a heat treatment apparatus for performing a predetermined heat treatment on a semiconductor wafer placed in a heat treatment chamber, wherein the outer periphery of the heat treatment chamber is covered with a polysilicon material. Configured.

[0005]

The polysilicon material covering the outer periphery of the heat treatment chamber has a property of adsorbing a metal substance. Therefore, metal impurities that try to enter from the outside are adsorbed by the polysilicon material and do not reach the heat treatment chamber. Here, if the outer periphery of the heat treatment chamber is covered with a granular or powdery polysilicon material, the surface area for adsorbing metal impurities increases, so that the metal impurities can be more effectively prevented from entering the heat treatment chamber. You can

[0006]

EXAMPLES A heat treatment apparatus for a semiconductor wafer according to the present invention will be specifically described below with reference to its preferred examples. FIG. 1 is a front sectional view showing an embodiment of a semiconductor wafer heat treatment apparatus according to the present invention, and particularly shows a vertical heat treatment furnace used in a semiconductor manufacturing process. First,
A schematic configuration of the vertical heat treatment furnace shown in the figure will be described. The vertical heat treatment furnace includes a furnace core tube 10 having a generally cylindrical shape. The furnace core tube 10 is opened downward, and a semiconductor wafer is taken in and out through the opening. A heat treatment chamber 11 is formed inside the furnace core tube 10. The semiconductor wafer W is placed in the heat treatment chamber 11 by the wafer holding member 12.

A processing gas introducing pipe 13 is provided in the heat treatment chamber 11 so that a predetermined processing gas can be introduced. Similarly, in the heat treatment chamber 11, the processing gas discharge pipe 14
Is provided to discharge the processing gas. The wafer holding member 12 has a plurality of heat shield plates 12a and is configured to rotate the held semiconductor wafer W about a vertical axis. The wafer holding member 12 is
It is installed on the furnace lid 15, and the furnace lid 15 is fixed to the base 16. The base 16 is driven by a vertical drive mechanism (not shown), and the wafer holding member 12 is inserted into and removed from the furnace core tube 10.

A soaking tube 17 is provided outside the furnace core tube 10. The soaking tube 17 has a cylindrical shape as a whole and opens downward. The soaking tube is made of SiC or SiC impregnated with Si. Exhaust pipe 1 is placed above the soaking pipe 17.
8 is provided. On the other hand, a stainless steel mount 19 is provided on the outer periphery of the lower end of the soaking tube 17. A soaking tube support member 20 is screwed under the frame 19. A soaking tube 17 is installed on the soaking tube support member 20. A gas introducing pipe 21 is installed in the soaking tube supporting member 20 so that the gas is introduced into the space formed between the furnace core tube 10 and the soaking tube 17. The gas introduced by the gas introduction pipe 21, for example, nitrogen gas containing hydrochloric acid gas is discharged from the exhaust pipe 22 provided on the upper part of the soaking pipe.

Between the soaking tube support member 20 and the furnace lid 15,
The furnace core tube support member 23 is arranged, and the soaking tube support member 2
It is screwed to 0. The furnace core tube 10 is installed on the furnace core tube supporting member 23, and the furnace core tube 10 and the furnace core tube supporting member 2 are provided.
Although not shown, a Teflon-made O-ring is provided at the contact portion 3 to improve the airtightness in the furnace. A heater 24 is arranged outside the soaking tube 17, and the heater 24
A heat insulating body 25 made of, for example, a heat insulating fiber is provided on the outer side of the.

In the semiconductor wafer heat treatment apparatus having the above-described structure, the furnace core tube 10 has a double tube structure of an inner tube 10a and an outer tube 10b made of quartz glass. Then, in the hollow portion formed between the inner pipe 10a and the outer pipe 10b,
It is filled with a granular polysilicon material 30. The polysilicon material 30 has a property of adsorbing a metal substance such as Fe, Cr, Ni and Cu. Therefore, the furnace core tube 10
The metal impurities that try to enter the heat treatment chamber 11 from the outside are adsorbed on the surface of the polysilicon material 30 filled in the hollow portion and are prevented from entering the heat treatment chamber 11.
The thickness of the hollow part (that is, the polysilicon material layer) may be arbitrary, but if it is too thick, the thermal conductivity deteriorates, and if it is too thin, the adsorption performance of metal impurities deteriorates. Set an appropriate thickness considering each of the adsorption performance. The diameter of each granular polysilicon material 30 is
It is preferable to make it as small as possible because the surface area increases and the hollow portion is densely packed. Further, a powdery polysilicon material may be filled in the hollow portion.

FIG. 2 is a front sectional view showing another embodiment of the present invention. That is, a quartz tube 41 having a hollow inside is installed between a furnace core tube 40 and a soaking tube 17 made of one piece of quartz glass, and a hollow portion of the quartz tube 41 is filled with a granular polysilicon material 42. You can also do it. Even with such a configuration, since the polysilicon material in the quartz tube 41 adsorbs the metal impurities, the metal impurities can be prevented from entering the heat treatment chamber 11. This quartz tube 41
Are installed on the soaking tube support member 20. The gas introduction pipe 21 is open both outside and inside the quartz pipe 41. A discharge port 42 for discharging the gas introduced from the gas introduction pipe 21 is provided at the center of the upper wall of the quartz pipe 41.
Is formed.

Example and Comparative Example A heat treatment apparatus (Example) having the configuration shown in FIG. 1 and a conventional furnace in which a furnace core tube was made of one piece of quartz glass and a polysilicon material was not arranged outside the furnace core tube Using a heat treatment apparatus (comparative example), heat treatment was performed on the silicon wafer at 1100 ° C. for 5 hours in an oxidizing atmosphere. The surface of the silicon wafer that had been subjected to the heat treatment by the apparatus of this example and the apparatus of the comparative example having the above structures was measured by atomic absorption spectrometry, and the amount of heavy metal impurities adsorbed on the surface was detected. The results are shown in Table 1. In Table 1, “<1” indicates that the value was below the detection limit. As is clear from Table 1, the heat treatment apparatus of this example significantly reduced the amount of metal contamination of the wafer to be processed, as compared with the comparative example having no metal portion coating layer.

[0013]

[Table 1] (× 10 ¹⁰ atms / cm ² )

[0014]

As described above, according to the semiconductor wafer heat treatment apparatus of the present invention, since the outer periphery of the heat treatment chamber is covered with the polysilicon material, the polysilicon material adsorbs metal impurities generated outside, Intrusion into the heat treatment chamber can be prevented. As a result, it is possible to suppress the generation of crystal defects in the semiconductor wafer placed in the heat treatment chamber, improve the product yield, and improve the quality.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a semiconductor wafer heat treatment apparatus according to the present invention.

FIG. 2 is a front sectional view showing another embodiment of the semiconductor wafer heat treatment apparatus according to the present invention.

[Explanation of symbols]

 10, 40 Furnace core pipe 10a Inner pipe 10b Outer pipe 11 Heat treatment chamber 13 Process gas introduction pipe 14 Process gas discharge pipe 15 Furnace lid 16 Base 17 Soaking pipe 19 Frame 20 Soaking pipe support member 21 Gas introduction pipe 22 Exhaust pipe 23 Furnace core Tube support member 24 Heater 30,42 Polysilicon material 41 Quartz tube

Claims (2)

[Claims] 1. A heat treatment apparatus for performing a predetermined heat treatment on a semiconductor wafer placed in a heat treatment chamber, wherein the outer periphery of the heat treatment chamber is covered with a polysilicon material. 2. The heat treatment apparatus for a semiconductor wafer according to claim 1, wherein an outer periphery of the heat treatment chamber is coated with a granular or powdery polysilicon material.