JPS581992Y2 - Heater holding device for heat reflection type diffusion furnace - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a diffusion furnace used in the manufacturing process of semiconductor devices and the like.

A resistance heating horizontal tube furnace is generally used as the diffusion furnace.

FIGS. 1 and 2 are a longitudinal sectional view and a transverse sectional view of one example.

In the figure, 1 is an annular resistance heating wire (hereinafter referred to as a heater).

), 2 is a heater terminal wire, and 3 is a separator for maintaining the spacing between the heater windings, which is inserted at various places in the heater winding.

(In Fig. 1, only one of them is shown - 4, which is a molded heat insulating material whose main purpose is to hold the heater.

5 is a felt-like heat insulating material, 6 is a furnace case, and 1 is a heater support material, which prevents the heater and the molded heat insulating material from bending in a heated state.

However, conventional furnaces with this type of structure have a large heat capacity,
Rapid heating and cooling are not possible, and this has drawbacks such as high power consumption.

On the other hand, recent semiconductors are becoming larger in size to improve production efficiency and for applications such as ultra-LSIs.

As wafers become larger, the inside of the electric furnace core tube is initially kept at about 700°C to prevent wafer warping during heat treatment, and the wafers are heated to a temperature of 1000 to 110°C, which is the post-processing temperature.
There is a step of raising the temperature to 0°C, performing a diffusion process with a predetermined gas, then lowering the temperature to about 700°C again, and then taking out the sea urchins.

For this reason, it is necessary to repeatedly raise and lower the temperature in a range of about 300 to 400°C each time.

Shortening the temperature rise and temperature fall times is an absolutely necessary condition for improving the operating rate.

As rapid heating and rapid cooling furnaces for this purpose, the present applicant has proposed a "heat reflection type diffusion furnace" and a "heat reflection type electric furnace" in Utility Application No. 52-155341 and Utility Application No. 53-64148. , the present invention further relates to these improvements.

Figures 3 and 4 show a longitudinal section and a cross section of one embodiment of the above proposal, in which 1 is a heater, 8 is a heater holding tube made of quartz, etc., and 9 is a furnace case with an inner surface. 10 is a heat conduction blocking space, and in the above-mentioned Utility Model Application No. 53-64148, this part is further vacuumed to prevent heat transfer by convection.

11 is alumina fiber, and the heater is connected to the heater holding tube 8.
It is to be fixed at

With this structure, of the heat loss from the heater, the one due to conduction only passes through the end plate 9-1 of the furnace case and the heater terminal wire 2, which is extremely small, and the heat loss due to convection is reduced compared to the actual heat loss described above. In Application No. 53-64148, the heat conduction cut-off space is made a vacuum to prevent heat loss, and in both of the above proposals, the radiated infrared rays are reflected by applying a gold coating to the inner surface of the furnace case. It is then returned to the heater part.

However, although such a structure can minimize heat loss, it is not preferable to suppress the bending of the heater holding tube with a heater support material as in the conventional example in terms of heat loss.

Therefore, the present invention provides a heater support that minimizes heat loss.

Figure 5 shows an embodiment of the present invention, and is an exploded view of a tube furnace.
is a two-part case, and heater holding plates 13 are attached to the central part of the lower case 12-1 at multiple locations so that the degree of slack can be adjusted in the direction perpendicular to the furnace axis. Two heater holding rods 14 are attached to the heater holding plate parallel to the furnace axis and symmetrically with respect to the furnace axis so as to ride on the plate.

The heater holding plate is made of a metal plate with poor thermal conductivity and high tensile strength, such as stainless steel, and the heater holding rod is made of a heat-resistant insulating material such as alumina.

FIG. 6 shows a cross section of a tube furnace made up of these members.

In the figure, 1 is a heater, 8 is a heater holding tube, 10 is a heat conduction blocking space, 11 is an alumina fiber, 12-1 is a lower case, and 12-2 is an upper case, and the inner surfaces of these cases are all coated with gold. 13 is a heater holding plate, 14 is a heater holding rod, and 15 is a tightening bolt for the upper and lower cases.

With this structure, the heater holding tube is held at its center by the heater holding plate and heater holding rod outside both end plates of the case, making it possible to suppress the deflection of the heater holding tube due to heating. (Since it is supported through an alumina fiber, it is possible to correctly hold the heater holding tube by loosening the bolt 15 and adjusting the amount of tension on the heater holding plate.)

With this structure, the heat capacity is small, so it is not only effective for rapid heating and cooling, but also because the heater is held in the center, there is no bending of the heater holding tube.
Since its lifespan is dramatically extended, the economic effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional annular furnace. FIG. 2 is a cross-sectional view of a conventional ring furnace. Figure 3 is a vertical cross-sectional view of the newly proposed heat-reflecting ring furnace. Figure 4 is a cross-sectional view of the newly proposed heat-reflecting ring furnace. FIG. 5 is an exploded view of the heat-reflecting ring furnace of the present invention. FIG. 6 is a cross-sectional view of the heat-reflecting ring furnace of the present invention.

Claims (1)

[Scope of utility model registration request] In a heat reflection type diffusion furnace, a space is provided between the outer periphery of an annular heating element concentric with the furnace axis and an outer wall tube, and the inner surface of this outer wall tube is an infrared reflecting surface. 1. A heater holding device for a heat reflection type diffusion furnace, comprising a plurality of heater holding plates held between tubes and a heater holding rod fixed so as to straddle the heater holding plates.