JPH0426115A - Vertical heat processor - Google Patents

Abstract

PURPOSE:To prevent corrosion of a rotational drive bearing by providing an inert gas atmosphere at the metal part of the bearing for rotating a boat for containing an element to be treated, conveyed into a reaction vessel at least for a treating period. CONSTITUTION:Part of a reaction vessel 1 or a boat 9 for containing an element to be treated in contact with treating gas is formed of a material of nonmetal, a bearing 13 for rotatably driving the boat 9 for containing the element is formed of metal, inert gas such as N2, etc., is supplied from a supply passage 19 at least during a period for treating a semiconductor wafer 6, fed from an outlet hole 21 to an atmosphere space S to provide an inert gas atmosphere at the metal of the bearing 13 to cover the exposed surface with the inert gas to protect it. For this inert gas, gas of the same type as the carrier gas in the treating gas is used.

Description

[Detailed description of the invention]

"Purpose of invention"

[Industrial Application Field 1] The present invention relates to a vertical heat treatment apparatus. [Prior art and its problems] When semiconductor wafers are carried into a reaction vessel of a diffusion furnace and subjected to heat treatment, a processing boat loaded with a large number of wafers at predetermined intervals in the vertical direction is moved through a loading/unloading mechanism. The semiconductor wafers are transported into a reaction vessel, and while the processing boat is rotated, a processing gas is introduced into the vessel to heat each semiconductor wafer so that its cross section is uniformly heated. In this case, in order to introduce the processing gas into the container, the processing gas is introduced from above the container, or an injector is inserted into the container, and multiple jets are emitted at predetermined intervals of the wafer along the length of the injector. A method has been adopted in which a hole is formed and the processing gas is supplied through the ejection hole. Among these, phosphorus doping is sometimes performed by introducing a processing gas into the semiconductor wafer, but in this case, the inside of the reaction vessel is usually heated to about 900 to 1200°C, and 02, N2 Each semiconductor wafer is doped with phosphorus by introducing a processing gas containing phosphorus oxychloride (POCQ, ) into a carrier gas such as . Since this processing gas, POCQ, is a corrosive gas, the parts that come into contact with the processing gas introduced into the reaction vessel are
Must be made of corrosion-resistant material. Therefore, quartz glass is usually used as a non-metallic material for parts such as reaction vessels that come into contact with the processing gas. However, since the processing boat carried into the reaction vessel is rotated as described above, the bearing section that supports the processing boat is usually
Since it is formed of a metal material, there is a problem that this bearing part may be corroded by the processing gas. The present invention was developed in view of the above-mentioned circumstances, and is a vertical heat treatment apparatus for the purpose of preventing corrosion of the rotational drive bearing portion of the object storage boat carried into the reaction vessel. "Structure of the Invention" [Means for Solving the Problems 1] In order to achieve the above-mentioned object, the present invention provides a vertical heat treatment apparatus in which a portion in contact with a processing gas is constructed of a heat-resistant non-metallic reaction vessel. The metal part of the bearing part that rotates the object storage boat carried into the reaction vessel was set in an inert gas atmosphere at least during the processing period. Also,
It is preferable to use the same gas as the carrier gas contained in the processing gas as the above-mentioned inert gas. [Function 1] Therefore, according to the present invention, when the object storage board 1- loaded with a large number of objects to be processed is carried into the reaction container by the loading/unloading mechanism and the processing gas is supplied into the reaction container, the inside of the container is The object to be processed is heat treated to bring the cross section to a uniform temperature state, and the object to be processed is subjected to oxidation and diffusion treatment. In this case, the parts that come into contact with the processing gas, such as the reaction vessel and the boat for storing objects to be processed, are made of non-metallic materials, and the bearing parts for rotational drive of the boat for storing objects to be processed are made of metal. . Therefore, if an inert gas is supplied to this bearing part while the object to be processed is being processed, the atmosphere of the metal part of the bearing part can be made into an inert gas atmosphere, so that the metal part of the bearing part can be processed. In addition to preventing corrosion caused by corrosive gas in the gas, in particular, this inert gas is supplied to the bearing portion located below in the reaction vessel, the same type of gas as the carrier gas in the processing gas. This makes it possible to create an inert atmosphere, which not only does not affect the processing of objects to be processed within the reaction vessel. The processing object storage boat is rotationally driven via a metal bearing part. [Example] Hereinafter, an example in which the present invention is applied to a vertical heat treatment apparatus for oxidizing and diffusing semiconductor wafers will be specifically described with reference to the drawings. In FIG. 1, a reaction vessel 1- is formed of quartz glass into a cylindrical shape, and its axial direction is vertical, thereby forming a vertical heat treatment section. A container wall 2 is placed below the reaction container wall 2 of this reaction container 1.
A tubular injector 4 made of quartz glass and sealed at the tip is inserted through a protruding cylinder part 3 that is integrally formed and protrudes outward from the injector 4, and a large number of ejection holes 5 are formed in the injector 4. The processing gas supplied from this injector 4 into the reaction vessel 1 contains phosphorus oxychloride (POCQ, ).
□, N2 is introduced to dope the semiconductor wafer 6 with phosphorus, and the introduced POCQ 3 is a corrosive gas.Furthermore, a heater 7 is provided around the reaction vessel 1, and the reaction vessel 1 is inside, usually 900-1200℃
An exhaust pipe 8 is provided at the bottom of the reaction vessel 1, and the processing gas introduced into the reaction vessel 1 through the exhaust pipe 8 is disposed of. A to-be-processed object storage boat 9 is carried in or out of the reaction vessel 1 via a carry-in/out mechanism (not shown). A processing gas is introduced into the reaction vessel 1 in which the wafer 6 is loaded and subjected to heat treatment, so that the semiconductor wafer 6 is subjected to oxidation and diffusion treatment. In this case, in the object storage boat 7, a drive shaft 12 is rotatably provided on the drive motor 10 via a belt 11, a metal bearing 13 is provided on the upper part of the drive shaft 12, and the bearing 13 A processing object storage boat 7 is rotatably provided via a boat support section 14 made of quartz glass provided at the bottom. The material used for the bearing portion 13 is a load-bearing metal such as stainless steel. Further, an opening/closing lid member 17 made of quartz glass for covering the lower opening 16 of the reaction vessel 1 is attached to the drive shaft 12 via a bearing 15 so that it can be carried in and out together with the boat 7. This opening/closing lid member 17 is provided with a glue tab seal 18 for hermetically sealing the opening 16 of the reaction vessel 1, and is further provided with a supply path 19 provided in the opening/closing lid member 17 (the supply path 19 is made of quartz). rather than an inert gas such as N2 (provided on the stainless steel lid),
A non-anti-corrosive gas is supplied to the bearing part 13 such as 2, from a ring-shaped cavity 20 communicating with the supply path 19, and from a plurality of outflow holes 21 opened radially facing the bearing part 13. The inert gas is configured to flow out into the atmosphere space S on the misting surface of the bearing part 13. Next, the operation of the above embodiment will be explained. When the processing object storage boat 9 carrying a large number of semiconductor wafers 6 is carried into the reaction vessel 1 by the carrying-in/out mechanism, and POCΩ3 is supplied from the injector 4 inserted into the reaction vessel 1, the injector 4 inside the vessel 1 supplies POCΩ3. semiconductor wafer 6
Processing gas is supplied at predetermined intervals, and the wafer 6 is heat-treated to a cross-section uniform temperature state, and the wafer 6 is doped with phosphorus. In this case, the parts that come into contact with the processing gas, such as the reaction vessel 1 and the object storage boat 9, are made of non-metallic material, and the bearing part 13 for rotating the object storage boat 9 is made of metal. However, at least during the period when the semiconductor wafer 6 is being processed, an inert gas such as N2 is supplied to the supply path 19.
The metal of the bearing portion 13 is brought into an inert gas atmosphere by being supplied from the outlet hole 21 into the atmosphere space S. That is, the exposed surface is protected by covering it with an inert gas at least during the period when a gas containing a corrosive gas is introduced. Therefore, the exposed metal surface of the bearing part 13 can be protected from being corroded by the corrosive gas in the processing gas, and in particular, this inert gas can be transferred to the reaction vessel 10 using the same type of gas as the carrier gas in the processing gas. By supplying the atmosphere to the bearing part 13 located at the lower part of the reaction vessel 1, an inert atmosphere can be created, which not only does not affect the processing of the semiconductor wafers 6 in the reaction vessel 1, but also allows the storage of the objects to be processed. The boat 9 is rotationally driven via a metal bearing 13. It is not necessary to blow out a large amount of this inert gas, and it is sufficient to prevent the metal n exit surface from coming into contact with one reaction gas. Therefore, the timing of releasing the inert gas may be at the same time as or earlier than the introduction of the reaction gas, or even after the introduction of the reaction gas, as long as it is before the reaction gas reaches the metal n exit surface. Furthermore, it is desirable to finish the introduction of the inert gas after all the reaction gases have been exhausted. The gas supplied to the bearing portion 13 is not limited to an inert gas, but may be any gas that is non-corrosive to the metal bearing portion 13, and may be any gas contained in the processing gas for the object to be processed. However, 2, for example 02, is also fine. "Effects of the Invention" As is clear from the above, the present invention has the following excellent effects. This has effects such as being able to prevent corrosion of the rotational drive bearing portion of the processing object storage boat carried into the reaction vessel.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of a vertical heat treatment apparatus according to the present invention, and FIG. 2 is a partially enlarged cross-sectional view showing a bearing portion of the same boat. 1...Reaction container 6...To be processed 9...To be processed object storage boat 13...Bearing portion 17...Covering member 21...Outflow hole

Claims (2)

[Claims] (1) In a vertical heat treatment apparatus in which the part that comes into contact with the processing gas is constructed of a heat-resistant non-metallic reaction vessel, at least the metal part of the bearing that rotates the object storage boat carried into the reaction vessel is processed. A vertical heat treatment apparatus characterized by being set in an inert gas atmosphere for a period of time. (2) The vertical heat treatment apparatus according to claim 1, wherein the inert gas is the same as the carrier gas contained in the processing gas.