JPH0783001B2 - Heat treatment furnace - Google Patents

Description

Description: (a) Field of Industrial Application The present invention relates to a heat treatment furnace having a heater for heating a furnace core tube and a mechanism for cooling the furnace core tube. The present invention relates to a heat treatment furnace used for heat treatment of a wafer for producing a semiconductor chip which is a main component.

The heat treatment of the wafer includes, for example, forming a thermal oxide film, forming a film by chemical vapor deposition (CVD), and diffusing impurities.

In any of these cases, a heat treatment furnace used for mass production is required to be able to uniformly process a large number of wafers, which are the objects to be processed, and therefore, a furnace for inserting wafers in the heat treatment furnace is required. The temperature in the center zone of the core tube is not only uniform in the heated state, but also uniform in the rise and fall of the temperature, and the rate of rise and fall can be controlled to a predetermined value. Is desired. Needless to say, this demand does not change even if the size of the wafer increases with the increase in the production amount.

(B) Conventional Technology FIG. 2 is a side sectional view schematically showing a typical configuration of a conventional heat treatment furnace. The heat treatment furnace shown in the drawing is a tubular furnace core made of, for example, quartz glass with one opening. Tube 1, cap 2 made of, for example, quartz glass for covering the opening of the furnace core tube 1, heaters 3a to 3 arranged around the furnace core tube 1 and heating the furnace core tube 1
c, a heat insulating layer 4 covering the outsides of the heater cores 1 and the heaters 3a to 3c, and a heat insulating layer 4 and a heater arranged outside the heat insulating layer 4.
It comprises a cooling mechanism 5 for cooling the furnace core tube 1 through 3a to 3c. Note that 1a and 1b are gas inlets and gas outlets, respectively, which are provided in the furnace core tube 1 and allow gas to pass through the furnace core tube 1.

The heater 3a is located in the center zone 1c region where the wafer A in the furnace core tube 1 is inserted and heat-treated, and heats the center zone 1c. The heaters 3b and 3c are end zones 1d before and after the center zone 1c, respectively. Located in the 1e region, the end zones 1d and 1e are heated so that the heat radiation at the end of the furnace core tube 1 is offset and the temperature of the center zone 1c becomes uniform.

The cooling mechanism 5 is, for example, one in which a metal tube is consistently wound over substantially the entire length of the furnace core tube 1 (end zone 1d + center zone 1c + end zone 1e), and cooling water is constantly supplied during operation of the heat treatment furnace. The cooling degree is controlled by adjusting the flow rate of the cooling water.

On the other hand, when the wafer A is heat-treated, the temperature of the center zone 1c may be set to the processing temperature before the wafer A is inserted or removed. However, after the wafer A is inserted at a predetermined temperature lower than the processing temperature, There is a case where the wafer A is taken out after the temperature is raised to the predetermined temperature and the temperature is lowered to the predetermined temperature.
When the size of the wafer A becomes large, the latter case becomes overwhelmingly large. In this latter case, if the temperature rises and falls slowly,
Proper treatment results may not be obtained by heat treatment with a short treatment time.

From this, in the heat treatment furnace configured as described above,
When performing the latter heat treatment, there are the following problems.

That is, the temperature rise is controlled by adjusting the power of the heater 3a while controlling the power of the heaters 3b and 3c so that the temperature of the center zone 1c becomes uniform, as shown in FIG. It is possible to have a desired rate such as ° C / min.

However, the temperature drop is as shown in FIG. 3 at positions a to c in the center zone 1c shown in FIG. 2 when all the heaters 3a to 3c are turned off.

That is, since the heat radiation on the end zone 1e side is smaller than the others, the temperature drop speed at the position c is slower than at the positions a and b.
This tendency becomes more remarkable as the wafer A becomes larger, that is, the diameter of the furnace core tube 1 becomes larger. For example, at a rate of about 5 ° C./min, which is much slower than the desired rate.

In the heat treatment of the wafer A, the temperature of the center zone 1c needs to be uniform even when the temperature drops, and this can be realized by adjusting the heaters 3a and 3b. The maximum descent speed is constrained by the speed at position c.

Therefore, under such circumstances, as mentioned above,
There is a case where proper heat treatment cannot be performed on the wafer A, and this influence is great especially when the wafer is large.

If the cooling capacity of the cooling mechanism 5 is increased, the problem of the temperature drop rate at the position c can be solved, but in such a case, a large amount of power is required for the heaters 3a and 3b, which is not practical as a heat treatment furnace.

The above description is for the case of the heat treatment furnace in which the furnace core tube 1 is arranged in the horizontal direction as shown in FIG. 2, but the above problem also occurs in the heat treatment furnace in which the furnace core tube is arranged in the vertical direction. Exists in.

(C) Problems to be Solved by the Invention A problem to be solved by the present invention is that it is difficult to perform proper heat treatment because the temperature drop rate at one end in the center zone is slow.

(D) Means for Solving Problems The above problems are caused by heating a furnace core tube having a gas inlet and a gas outlet, and heating the furnace core tube provided around the furnace core tube. A heat treatment furnace having a heater and a mechanism for further cooling the furnace core tube provided on the outer periphery thereof, for heat treating a wafer supported in the furnace core tube, the heater comprising: The furnace core tube is divided into a plurality of regions in the longitudinal direction of the furnace core tube so that the respective regions can be individually heated and controlled, and a mechanism for cooling the furnace core tube is provided. Is solved by the heat treatment furnace according to the present invention, which is divided into a plurality of regions so that it is possible to individually cool and control each of the plurality of regions divided in the longitudinal direction.

In the practice of the present invention, the region is composed of three regions of a center zone and both end zones in the furnace core tube, and the cooling capacity for each region of the mechanism for cooling the furnace core tube is The area of the core tube on the side where the temperature drop rate is slower is larger than the other areas.

(E) Action As described above, in the conventional heat treatment furnace shown in FIG. 2, the temperature lowering rate on the side of the furnace core tube in the center zone with less heat radiation is slower, and the speed lowers the temperature lowering rate of the center zone. You are constrained. Therefore, by increasing only the cooling capacity for the region on the side where the temperature drop rate is slower than before, it is practical as a heat treatment furnace, and it is possible to increase the temperature drop rate in the center zone.

Thus, it is necessary to insert the wafer into the furnace core tube at a predetermined temperature lower than the processing temperature, raise the temperature to the processing temperature, and lower the temperature to the predetermined temperature before taking out the wafer. Even for a short time heat treatment of a large wafer, it is possible to perform an appropriate treatment on the wafer.

In the practice of the present invention, setting the individually controllable regions for cooling to the three regions has the effect of facilitating heating and cooling control in each region, in line with the divided arrangement of the heaters. .

However, the present invention is not limited to the individually controllable regions for cooling being the above-mentioned three regions, and the individually controllable regions for heating and cooling do not always match.

Further, the above is not limited to the case of the heat treatment furnace in which the furnace core tubes are arranged in the horizontal direction as shown in FIG. 2, but also holds in the heat treatment furnace in which the furnace core tubes are arranged in the vertical direction.

(F) Example An example of a heat treatment furnace according to the present invention will be described below with reference to FIG. 1 (side sectional view) schematically showing. The same reference numerals denote the same objects throughout the drawings.

In FIG. 1, the cooling mechanisms 5a to 5c are replaced with the cooling mechanism 5 shown in FIG. 2, and the other parts are the same as those shown in FIG.

Each of the cooling mechanisms 5a and 5b is obtained by dividing the conventional cooling mechanism 5 in accordance with the center zone 1c and the end zone 1d regions of the furnace core tube 1, and the metal tube is placed on the heat insulating layer 4 as in the conventional case. It has been wrapped around. In addition, the cooling mechanism 5c
It corresponds to the end zone 1e region part of the conventional cooling mechanism 5, and in order to increase the cooling capacity for the end zone 1e region, a thick metal tube must be wound with a higher density than in the case of the cooling mechanisms 5a and 5b. ing.

Thus, the temperature drop rate at the position c in the center zone 1c becomes faster than before, and the temperature drop rate in the center zone 1c can be set to a desired speed, and the temperature rise and fall control for each zone 1c to 1e is controlled. Will be easier.

The inventor of the present application modified the heat treatment furnace shown in FIG. 2 in which the diameter of the furnace core tube 1 is about 20 cm according to the above configuration, and the temperature decrease rate of the center zone 1c was about 5 ° C./min. The heat treatment furnace could be used for heat treatment at the rate of about 15 ° C./min, and the temperature rise and fall could be easily controlled.

The contents of the modification are as follows.

The cooling mechanism 5 is installed in the end zone 1d, the center zone 1c,
The end zone 1e was divided into three parts in accordance with the respective regions, and the former two parts were respectively made into cooling mechanisms 5b and 5a so that cooling water could individually pass therethrough.

A portion of the cooling mechanism 5 which fits the end zone 1e region due to the division is removed, and a metal tube having a thickness of about 1.5 times that of the conventional one is arranged at a density of about 2.5 times that of the conventional cooling mechanism 5c.
The cooling water can be separately passed.

(G) Effects of the Invention As described above, by taking the measures according to the present invention, it is possible to perform appropriate heat treatment on the wafer even if the wafer becomes large.

[Brief description of drawings]

FIG. 1 is a side sectional view schematically showing an embodiment of a heat treatment furnace according to the present invention, FIG. 2 is a side sectional view schematically showing a typical constitution of a conventional heat treatment furnace, and FIG. It is the figure which showed the temperature rise and fall situation of the center zone. In the drawings, 1 is a furnace core tube, 1a is a gas inlet, 1b is a gas outlet, 1c is a center zone, 1d and 1e are end zones, 2 is a cap,
3a to 3c are heaters, 4 is a heat insulating layer, 5 and 5a to 5c are cooling devices,
a to c respectively indicate positions.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akinao Ogawa 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited (56) 10458 (JP, U)

Claims (3)

[Claims] 1. A furnace core tube having a gas inlet and a gas outlet, a heater for heating the furnace core tube provided around the furnace core tube, and a heater further provided on the outer periphery thereof. A heat treatment furnace having a mechanism for cooling the furnace core tube, for heat-treating a wafer supported in the furnace core tube, wherein a plurality of heaters are provided in a longitudinal direction of the furnace core tube. Each of the divided regions is divided into a plurality of parts so that heating control can be performed individually, and a mechanism for cooling the furnace core pipe is divided into a plurality of parts in the longitudinal direction of the furnace core pipe. A heat treatment furnace characterized by being divided into a plurality of parts so that each region can be individually controlled for cooling. 2. The individually heated or cooled regions,
Both are three regions of a center zone into which the wafer is inserted in the furnace core tube and both end zones located in front of and behind the center zone.
The heat treatment furnace according to the item. 3. The cooling capacity for the respective regions of the mechanism for cooling the furnace core tube is larger than that for the other areas with respect to the area on the side of the furnace core tube having the slower temperature drop rate. The heat treatment furnace according to claim (1) or (2).