JPS63137416A - Vacuum heat insulating furnace - Google Patents

Abstract

PURPOSE:To shorten the decreasing time of temperature and to prevent the yield of contaminated material from a heat insulating material, by providing a tightly closed vacuum container at the outside of a reacting tube, forming a vacuum chamber between the tube and the container, and providing a heater in the vacuum chamber. CONSTITUTION:A tightly closed vacuum container 2 is provided at the outside of a reacting tube 1. A vacuum chamber 6 is formed at a gap between the reacting tube 1 and the container 2. The vacuum chamber 6 is evacuated to a vacuum state through an exhaust pipe 12. Heat insulating effect is secured with the vacuum chamber 6. Since a heat insulating material is not used at all, the heat capacity of a furnace can be made small, and the decreasing characteristic of temperature can be made excellent. A heater 5 is provided in the vacuum chamber 6. When the temperature of the furnace is decreased, nitrogen is introduced through a leaking pipe 7, and the heater 5 is directly cooled with air. Therefore the temperature decreasing characteristic becomes excellent. Since the heat insulating material is not used, a semiconductor substrate is not contaminated with contaminant yielded from the heat insulating material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvement of a heating furnace in semiconductor manufacturing equipment.

[Prior Art] Heating furnaces are widely used in fields such as chemical vapor deposition, oxidation, and impurity diffusion in the semiconductor manufacturing process, but the general characteristics required for such heating furnaces are thermal efficiency. Good heat retention, low power consumption, low energy consumption, rapid temperature rise and fall characteristics of the heating furnace, high temperature resistance, uniform temperature distribution within the heating furnace, and contamination from the heating furnace itself. Examples include prevention of heat generation, insulation to the outside of the heating furnace, and ease of handling. Conventionally, in heating furnaces used in semiconductor manufacturing equipment, a heating element is fixedly supported by a metal inner tube with an insulator, and a heat insulating material is placed between the outer tube and the heating element to maintain the temperature inside the furnace. Firebrick and asbestos are used as insulation materials. Particularly when refractory bricks are used as the heat insulating material, there are disadvantages in that the heat capacity of the entire heating furnace increases, it takes a long time to raise and lower the temperature of the heating furnace, and the electric power required for heating increases.

In addition, as the use of ultra-large scale integrated circuits (VLSI) continues to increase in recent years, measures to prevent contamination of semiconductors have become a problem, but contaminants generated from the heating furnace itself, especially the heat insulating material within it, can pass through the reaction tube and contaminate the semiconductor substrate. Asbestos, etc. used as a heat insulating material accumulates around semiconductor devices, especially around the openings of reaction tubes where wafers enter and exit, causing contamination.

- By not using a heat insulating material, contaminants from conventional heat insulating materials are no longer generated and contaminate the semiconductor substrate.

[Means for Solving the Problems] In order to achieve the above object, the heating furnace according to the present invention includes a reaction tube equipped with a reaction gas supply port and a discharge port, and a vacuum-sealed container disposed outside the reaction tube. A heating furnace is constructed by forming a vacuum chamber between the heating elements and providing a heating element within the vacuum chamber. In the heating furnace according to the present invention, a vacuum chamber is provided without using the heat insulating material used in the past, and the vacuum insulation is utilized, which eliminates the problem of contaminants being generated from the heat insulating material itself. A clean heating furnace can be constructed.

In addition, regarding temperature rise and fall times, since there is no insulation material, the heat capacity of the entire heating furnace is small, and the temperature rise and fall characteristics are excellent. In addition, especially when the temperature falls, nitrogen gas is introduced into the vacuum chamber and the heating element can be directly forced air cooled. The temperature drop characteristics become even better.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example in which a vertical cross-sectional view of the vacuum insulation furnace according to the present invention is applied to a vertical furnace. In the same figure, 1 is a reaction tube having a reaction gas inlet 17 and an outlet 18, and 2 is a vacuum sealed container disposed outside the reaction tube 1. The reaction tube 1 and the vacuum sealed container 2 are
The gap constitutes a vacuum chamber 6. This vacuum chamber 6 is an exhaust pipe 1
A vacuum evacuation device (not shown) performs evacuation through the chamber 2, and the vacuum chamber 6 ensures a heat insulating effect. Therefore, unlike conventional heating furnaces, no heat insulating material is used, so the heat capacity of the heating furnace can be reduced, and the temperature rise and fall characteristics are improved. A heating element 5 is provided in a vacuum chamber 6 together with a cylinder 4 that supports the heating element 5. When the temperature of the heating furnace is lowered, the leak valve 19 is opened, nitrogen is introduced from the leak pipe 7, and the heating element is directly air cooled, so that the temperature lowering characteristics are also improved. 3
is a water-cooled pipe that cools the heating furnace. Furthermore, since no heat insulating material is used as in the conventional method, the problem of contamination of the semiconductor substrate by contaminants generated from the heat insulating material is also eliminated.

In FIG. 1, a semiconductor substrate 9 is held in a boat 8, and this is placed on a boat support stand lO, and the boat 8 is rotated by a drive source 16 via a support shaft 11 to uniformly process the semiconductor substrate 9 in the boat 8. It is intended to provide The reaction tube 1 and the vacuum sealed container 2 are kept vacuum airtight by an O-ring OR.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an outline of an embodiment of a semiconductor manufacturing apparatus using a vacuum adiabatic heating furnace according to the present invention. i ------1 reaction tube 11---
- Support shaft 2 - - Vacuum sealed container 12 -
-1 Vacuum exhaust pipe 3--- Cooling pipe
13---Base plate 4-111 Heater support member
14-----1 Vacuum seal flange 5----
Heater 15-1 Cooling water passage 6-
-Vacuum chamber 16---Drive source 7---
- Leak pipe 17-- Reactive gas introduction hole 8--Boat 18=-Exhaust hole 9--Semiconductor substrate 19--Leak valve lθ-- Boat support 1 Engraving of drawing No. 1 Patent Office Director Kunio Ogawa 1. Indication of the case 3, Relationship with the case of the person making the amendment Patent question address Postal code 214 6-20-3-5 Nagao, Tama-ku, Kawasaki City, Kanagawa Prefecture Drawings to be amended 6, Contents of the amendment as per attached sheet

Claims (1)

[Scope of Claims] 1) A reaction tube equipped with a gas supply port and a gas discharge port, and a vacuum sealed container having a diameter larger than the reaction tube and closed at one end are disposed outside the reaction tube, A vacuum adiabatic heating furnace characterized in that a heater is provided between the reaction tube and the vacuum sealed container to provide a heat insulation effect by a vacuum section between the reaction tube and the vacuum sealed container. 2) The vacuum adiabatic heating furnace according to claim 1, wherein nitrogen gas or air is introduced into the vacuum section during cooling of the heating furnace to improve the cooling effect. 3) The vacuum adiabatic heating furnace according to claim 1, wherein the heater is attached to a heater support member having good thermal conductivity to improve thermal uniformity within the heating furnace.