US3819067A

US3819067A - Heat treating apparatus

Info

Publication number: US3819067A
Application number: US00284648A
Authority: US
Inventors: I Hammond
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-08-29
Filing date: 1972-08-29
Publication date: 1974-06-25
Anticipated expiration: 1991-06-25

Abstract

An apparatus is provided for heat treating semi-conductor elements in a diffusion furnace in which an interface is formed between the apparatus and the interior heat treating chamber of the furnace.

Description

United States Patent [191 Hammond June 25, 1974 [54] HEAT TREATING APPARATUS 3,563,434 2/1971 Shriver 214/23 [76] Inventor: a K. H n e 3,669,431 6/1972 Lenss et a] 432/239 X Kinnelon, NJ. 07405 22 Filed: A 29 1972 Primary Examiner-Robert G. Sheridan Attorney, Agent, or Firm-Marvin A. Naigur [21] App]. No.: 284,648

[52] U.S. Cl 214/26, 432/253, 432/258 7 ABSTRACT [51] Int. Cl. F27b 9/00 of Search R, 23, An apparatus is provided for heat treating emi. 432/258, 239, conductor elements in a diffusion furnace in which an interface is formed between the apparatus and the in- [56] References C'ted terior heat treating chamber of the furnace.

UNITED STATES PATENTS 12/1966 Cloutier 214/18 R 9 Claims, 5 Drawing Figures HEAT TREATING APPARATUS BACKGROUND OF THE INVENTION In the heat treatment of semi-conductor materials, there is usually provided a furnace that is traversed by a movable fixture of quartz or glass on which, the semiconductor elements are positioned. The usual type of glass or quartz fixture has a tendency to stick to the interior surface of the furnace, thereby making it impossible to move the fixture in the furnace. In this connection, it should be noted that heat treating furnaces are usually provided with mechanical devices which are capable of extending and retracting the fixture at a relatively slow rate such that a uniform heat treating procedure can be applied to the semi-conductor elements. Since the mechanical actuating device is automatically operated by an electric motor, the fixture has a tendency to stick to the surface and then become dislodged by the actuator device which often results in the semi-conductor elements being damaged by vibration or actually broken through being dislodged from the fixture. It has been found that the adherence of the fixture to the internal surface of the furnace results from the furnace being operated at a temperature which is very close to the fusion temperature of the quartz material from which the fixture is formed. Also, during some heat treating operations, there is a formation of a thin film of tacky substance formed along the internal surface of the furnace, thereby further causing the fixture to stick to the furnace walls. The adherence of the fixture to the furnace is prevented in accordance with the invention by providing an interface between the fixture and the furnace wall. This interface essentially provides point contact between the fixture and the furnace wall, thereby reducing the area, subject to the fusion or stick- SUMMARY OF THE INVENTION In accordance with an illustrative embodiment demonstrating features and advantages of the present invention, there is provided apparatus for heat treating semi-conductor elements in a diffusion furnace having an internal heat treating chamber. The apparatus comprises an elongated carrier formed with means for positioning the semi-conductor elements. Means are provided on the fixture for forming an interface between the fixture and the heat treating chamber.

BRIEF DESCRIPTION OF THE DRAWINGS The above brief description, as well as further objects, features, and advantages of the present invention will be more fully appreciated by reference to the following detailed description of presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in connection with the accompanying drawings wherein:

FIG. 1 is an elevational view of a heat treating furnace and linear actuator mechanism, with portions of the heat treating furnace being broken away to better illustrate the present invention;

FIG. 2 is an elevational view of an embodiment of the carrier in accordance with the present invention which is shown removed from the heat treating furnace;

FIG. 3 is a cross-sectional view of the carrier shown in FIG. 2, positioned in the heat treating furnace tube;

FIG. 4 is a sectional view similar to FIG. 3, but showing a sectional view of a carrier in accordance with a further embodiment of the present invention; and

FIG. 5 is a plan view of the carrier shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, there is shown a heat treating apparatus generally designated by the reference numeral 10 which comprises a furnace 12 upon which there is mounted a linear actuator mechanism 14. The linear actuator mechanism I4 includes a series of arms 16 which can be telescopically extended and retracted into a housing 18 in which there is mounted a gear driven motor. A more detailed description of the linear actuator can be obtained from applicants U.S. Pat. No. 3,592,070 which has been granted on July 13, I971. The furnace 12 comprises a housing 20, in which there is mounted a heat treating cylindrical tube 22 which is usually fabricated from quartz or glass material.

Movably mounted in the tube 22 is a carrier fixture 24 which is formed with a series of slots 26 for positioning semi-conductor wafers 28. The carrier fixture 24 is formed from a pair of outer beam members 30, the front portions of which converge at a tab section 32 which is formed with a circular opening 34. The rear portion of the beam members are joined by an end beam 36, and a series of brace beams 38 are joined between the outer beam sections 30 for providing greater structural stability to the carrier fixture 24. The carrier fixture 24 is slideably connected to the linear actuator mechanism 14 by means of a pull rod 40, one end of which is provided with a hook 42 for mounting in the opening 34, and the other end of which is connected to a tie rod 44. The outermost arm 16 of the linear actuator 14 is secured to tie rod 44 by means of a clamp 46 and the pull rod 40 is secured to tie rod 44 by means of a wing nut clamp 48.

As best shown in FIG. 2, the outer beams 30 of carrier fixture. 24 are provided with slots 49 which are formed to receive wedge elements 50. In order to secure the wedge elements 50 to the carrier fixture 24, wedge elements 50 are positioned in the slots 49 and a pair of rods 52 are fused to the beam members 30 on either end of slot 49. Since the wedge elements 50 are formed with a configuration generally conforming to the frustum' of a triangle, the base of the wedge elements 52 are fixed in position within the slots 49 by means of the rods 52. The rods 52 are fused to the carrier fixture 24 by applying heat to a pair of relatively straight quartz stock material such that the rods 52 are bent over and brought into contact with the opposite ends of the wedge unit 50 fused to ends of slot 49. Depending on the specific application, it is also possible to secure the wedge elements 50 without the use of any of the rods 52. This is accomplished by applying heat around the edges of slots 49, such that the wedge elements 50 are surrounded by a perimeter of fused quartz. The wedge elements 50 are preferably fabricated from silicone carbide material which is compatible with diffusion processes, such that contamination will not be produced in the furnace 22 which would result in the semi-conductor wafers 28 being spoiled.

Turning to FIG. 4, there is illustrated a further embodiment of the invention in which corresponding parts have been designated by the same reference numerals as part of a 100" series. In this form of the invention, there is shown a carrier fixture 124 formed with semispherical indentations 148 which are provided for positioning spherical elements 150. Each of the spherical elements 150 are positioned in the openings 148 by means of a pair of rods 152 in a manner similar to the mounting of the wedge elements 50 by means of the rods 52. It is also possible to secure the spherical elements 150 by applying heat around the edges of apertures 148, thereby eliminating the use of the rods 152. As in the case of the wedge elements 50, it is preferable to fabricate the spherical elements 150 from a material which is compatible with the diffusion processes such that contamination will not occur in cylindrical tube 22.

It should be understood that the wedge elements 50 and spherical elements 150 have been designed to provide minimal contact between the elements (50, 150) and the inner surface of cylindrical tube 22, such that point contact is essentially achieved. Thus, the elements (50, 150) could take a variety of equivalent shapes to obtain point contact. For example, the elevational viewin FIG. 2 of the wedge elements 50 could be changed to a triangular shape or a semi-circular shape, and for the sake of simplicity these various shapes have not been shown in the drawings.

From the foregoing, it can be appreciated that in accordance with the present invention, there is provided carrier fixtures (24, 124) for heat treating semiconductor elements 28 in the heat treating tube 22 of 30 diffusion furnace 20. The carrier fixtures (24, 124) are formed with slots (26, 126) for positioning the semiconductor elements 28. The wedge elements 50 and spherical elements 150 are respectively mounted on the carrier fixtures (24, 124) for forming an interface between carrier fixtures (24, 124) and the internal surface of heat treating tube 22. Thus, by utilizing the wedge units 50 or the spherical units 150, it is possible to essentially obtain point contact between the carrier fixtures (24, 124) and the internal surface of the furnace tube 22.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in some instances some features of the invention will be employed withou a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

1. Apparatus for heat treating semi-conductor elements in a diffusion furnace having an internal heat treating cylindrical chamber comprising an elongated carrier fixture formed with means for positioning said semi-conductor elements, a plurality of point contact support members mounted on said fixture, and each of said support members making point contact with the internal surface of said cylindrical chamber whereby an interface between said fixture and said heat treating chamber is established.

2. Apparatus for heat treating semi-conductor elements in a diffusion furnace according to claim 1 in which said means on said fixture comprise a plurality of wedge sections secured to the bottom of said fixture.

3. Apparatus for heat treating semi-conductor elements in a diffusion furnace according to claim 2 in which said wedge sections are fabricated from a material which is compatible with the operation within said diffusion furnace such that contamination will not occur within said diffusion furnace to adversely affect said semi-conductor elements.

4. Apparatus for heat treating semi-conductor elements in a diffusion furnace according to claim 2 in which said carrier fixture is fabricated from quartz material formed with a plurality of slot openings sized to receive said wedge sections.

5. Apparatus for heat treating semi-conductor elements in a diffusion furnace according to claim 2 in which said wedge sections are fabricated from silicone carbide material formed with a generally triangular shaped outer configuration.

6. Apparatus for heat treating semi-conductor elements in a diffusion furnace according to claim 1 in which said means on said fixture comprise a plurality of spherically shaped sections secured to the bottom of said fixture.

7. Apparatus for treating semi-conductor elements in a diffusion furnace having an internal heat treating chamber and a linear actuator capable of being extended and retracted within said chamber, comprising an elongated carrier fixture formed with means for positioning said semi-conductor elements, said carrier fixture mounted on said actuator for moving said fixture in said chamber, and a plurality of point contact support means on said fixture, and each of said support means making a point contact with the internal surface of said chamber, whereby an interface is established between said support means and said heat treating chamber, such that said support means are prevented from adhering to the surface of said heat treating chamher.

8. Apparatus for heat treating semi-conductor elements in a diffusion furnace according to claim 7 in which said means on said fixture comprise a plurality of wedge sections secured to the bottom of said fixture.

said slot openings.

Claims

7. Apparatus for treating semi-conductor elements in a diffusion furnace having an internal heat treating chamber and a linear actuator capable of being extended and retracted within said chamber, comprising an elongated carrier fixture formed with means for positioning said semi-conductor elements, said carrier fixture mounted on said actuator for moving said fixture in said chamber, and a plurality of point contact support means on said fixture, and each of said support means making a point contact with tHe internal surface of said chamber, whereby an interface is established between said support means and said heat treating chamber, such that said support means are prevented from adhering to the surface of said heat treating chamber.

9. Apparatus for heat treating semi-conductor elements in a diffusion furnace according to claim 7 in which said carrier fixture is fabricated from quartz material formed with a plurality of slot openings sized to receive said wedge sections, such that said wedge sections can be secured to said fixture by applying heat to said slot openings.