JP2651601B2 - heating furnace - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a heating furnace, and particularly to a heating furnace suitable for use in heat diffusion such as thermal diffusion applied to semiconductor wafers or CVD. .

(Prior Art) In a semiconductor device manufacturing process, a heating furnace is used for heat treatment such as thermal diffusion or CVD.

In a heating furnace used for such a heat treatment, a temperature change in the furnace is apt to occur during loading and unloading of semiconductor wafers. Therefore, a large number of semiconductor wafers are arranged on a wafer boat, and the semiconductor wafers are placed together with the wafer boat. For example, many semiconductor wafers are configured to be inserted into a furnace tube heated to about several hundreds to several hundreds degrees to simultaneously heat-treat a large number of semiconductor wafers. By such an operation, the influence of the above-mentioned change in the furnace temperature on each semiconductor wafer is minimized, and the throughput of the heat treatment applied to the semiconductor wafer is improved.

Such a heating furnace is required to have uniform temperature in the furnace tube. For this reason, in a conventional heating furnace, a soaking tube is arranged around a furnace tube made of quartz or the like, a heater for heating is arranged around the furnace tube, and a porous heat insulating material or the like is provided so as to cover around the heater. Many have a heat insulating material layer.

That is, the conventional heating furnace covers the periphery of the heater with a heat insulating material having a low thermal conductivity, thereby reducing and uniformizing the heat release to the outside, and trying to secure the uniformity of the temperature distribution in the furnace tube. Things.

However, for example, in order to perform uniform heat treatment on a semiconductor wafer, uniformity of temperature within about ± 0.5 ° C. is required throughout the furnace. However, in the conventional heating furnace, it was not possible to set the furnace temperature with such high uniformity.

Further, in the conventional heating furnace, since the heater is installed in the atmosphere, there is a problem that heat loss due to convection is extremely large and energy efficiency is extremely low. Further, due to the heat loss due to the convection, the temperature distribution in the furnace tends to be non-uniform, and the total length of the furnace body is about twice as long as the required soaking length, resulting in an increase in the size of the apparatus.

(Problems to be Solved by the Invention) As described above, in the conventional heating furnace, the temperature inside the furnace cannot be maintained at a high uniformity, and the uniform heating length is shorter than the entire length of the furnace body. There was a problem that the whole was enlarged. Furthermore, there is a problem that energy efficiency is very low due to insufficient heat insulating effect. For this reason,
Further, development of a heating furnace having excellent soaking properties has been desired.

The present invention has been made to address such problems of the prior art, and sufficiently suppresses heat loss during heating.
An object of the present invention is to provide a heating furnace capable of heating the inside of the furnace efficiently and uniformly.

[Structure of the Invention] (Means for Solving the Problems) That is, according to the invention of claim 1, a heater disposed around a substantially cylindrical furnace tube and a substantially cylindrical heat insulating member disposed outside the heater are provided. In the heating furnace provided with a material layer, the heat insulating material layer is configured to be divided into a plurality of layers, and one or more reflecting material layers made of a heat reflecting material are provided between the plurality of heat insulating material layers. It is characterized by that.

The invention according to claim 2 is a heating furnace comprising a heater arranged around a substantially cylindrical core tube and a substantially cylindrical heat insulating material layer arranged outside the heater. The layer is configured to be divided into a plurality of layers, and between the plurality of heat insulating material layers, one or more reflecting material layers made of a heat reflecting material are provided, and the heat insulating material layer, the reflecting material layer, It is characterized in that the heater is arranged in a vacuum.

(Operation) The heat generated by the heater is not released only by heat conduction, but is also released to the outside by radiation from the surface of the heat insulating material. In general, such heat radiation due to radiation is particularly large in a heat insulating material having many voids and low thermal conductivity. This is apparent from the graphs showing the relationship between the thermal conductivity and the bulk density of the heat insulating material layer shown in FIGS. 5 and 6, for example. Note that the heat insulating material layers in these graphs are formed of ceramic fibers. From these graphs, it can also be seen that the higher the heating temperature, the greater the heat radiation effect by radiation in the heat insulating material layer. Also,
For example, a heat reflecting material such as an aluminum thin film has a high thermal conductivity and emits much heat due to heat conduction, but emits very little heat due to radiation.

Therefore, in the heating furnace of the present invention, for example, a heat-reflecting material layer provided with a heat-reflecting material is provided on the surface or intermediate portion of the heat-insulating material layer disposed outside the heater, and the heat-insulating material layer suppresses heat release due to heat conduction. In addition, the reflective material layer suppresses heat emission due to radiation. As a result, the amount of heat radiation can be reduced, the temperature in the furnace tube can be made uniform, the power consumption of the heater can be extremely reduced, and the object can be efficiently heat-treated.

Further, by disposing the heater in a vacuum, heat loss due to convection of the heater itself is almost eliminated, power consumption of the heater is extremely reduced, and the temperature in the furnace tube can be efficiently made uniform. As described above, even when the heater is placed in a vacuum, the radiation efficiency is increased and the heating efficiency is further improved by providing the reflection material layer made of the heat reflection material outside the heater.

(Example) Hereinafter, an example of a heating furnace of the present invention will be described with reference to the drawings.

For example, a furnace tube 1 made of quartz or the like has an outer diameter of 250 to 350 mm,
It is formed in a cylindrical shape with a length of about 1500 to 2000 mm. This furnace tube 1 is arranged in a soaking tube 2. A heating heater 3 having a heater wire formed in a coil shape is disposed outside the heat equalizing tube 2. Further outside the heater 3, a heat insulating material layer 4 made of a porous heat insulating material or the like is disposed so as to cover the periphery thereof. Ceramic fibers or the like are used as the heat insulating material.

The heat insulating material layer 4 has a plurality of layers, for example, a three-layer structure, between the innermost heat insulating material layer 4a and the intermediate heat insulating material layer 4b, and between the intermediate heat insulating material layer 4b and the outermost heat insulating material layer 4b. Reflecting material layers 5a and 5b made of a heat reflecting material such as an aluminum thin film having a thickness of, for example, about several tens to several hundreds of microns are arranged between the heat insulating material layers 4c. When the temperature is higher than 1000 ° C., it is preferable to omit the inner reflective material layer 5a or to form the inner reflective material layer 5a with a heat reflective material having excellent heat resistance such as platinum.
The reflecting material layers 5a and 5b may be formed in the heat insulating material layer 4 in the entire area along the longitudinal direction, or may be selectively provided in a predetermined area. A heater case 6 is arranged outside the heat insulating material layer 4.

The heating heater 3 is connected to a control device (not shown), and is a three-zone control in which the temperature is independently controlled for each of three divided regions in the longitudinal direction of the furnace tube 1.

Further, the heater 3 may have a configuration in which the number of turns of the heater wire is made dense at the center portion of the center zone of the above-mentioned three divided areas and sparse at both end portions of the center zone. This further lengthens the soaking zone.

In the heating furnace of this embodiment having the above-described structure, the inside of the furnace tube 1 is first heated by the heater 3 to, for example, about several hundreds to several hundreds degrees. Then, for example, a wafer boat 7 made of quartz or the like
A large number of semiconductor wafers 8 are arranged on the upper surface thereof such that their main surfaces face each other, and the semiconductor wafers 8 are arranged together with the wafer boat 7 in the furnace tube 1 from one end opening of the furnace tube 1 by soft landing or the like. , For example, thermal diffusion or CVD
And the like.

At this time, heat generated by heating the heater 3 is transmitted to the semiconductor wafer 8 through the heat equalizing tube 2. During the heat treatment of the semiconductor wafer 8, part of the heat in the heat equalizing tube 2 tends to flow out through the heat equalizing tube 2 and the heat insulating material layer 4 to the outside. However, the release of heat to the outside due to heat conduction is suppressed by the heat insulating material layers 4a to 4c. In addition, these heat insulating material layers 4a
Part of the heat passing through the heat insulating layers 4a to 4c is reflected in the direction of the furnace tube 1 by the reflecting material layers 5a and 5b disposed between the heat insulating layers 4a to 4c, and the heat generated by the radiation between the heat insulating layers 4a to 4c. Release is also suppressed.

Therefore, the amount of heat released outward can be significantly reduced as compared with the conventional heating furnace, that is, most of the heat generated by heating the heater 3 is reduced to the furnace tube 1.
Can be supplied inside. Thereby, the inside of the furnace tube 1 can be efficiently and uniformly heated with low power consumption, and a uniform heat treatment can be performed on the semiconductor wafer 8.

In the above embodiment, the reflector layers 5a and 5b are formed of an aluminum thin film. However, the present invention is not limited to such an embodiment, and may be formed of an aluminum foil or the like. Can also be used.

In addition, it goes without saying that the arrangement position, the number, and the like of the reflective material layers may be set as desired.

Next, a heating furnace according to another embodiment of the present invention will be described.

As shown in FIG. 3, the furnace tube 11 is made of quartz or the like as in the above-described embodiment, and has an outer diameter of 250 to 350 mm and a length of 1500 to 2000.
It is formed in a cylindrical shape of about mm. In this core tube 11,
A flange 11a for connecting to the furnace body is provided. The outer periphery of the furnace main body side is constituted by a cylindrical chamber-shaped vacuum chamber 12 formed of quartz or the like, and a flange 12a is provided on the open port side of the vacuum chamber 12. The core tube 11 is inserted into the vacuum chamber 12 and
The inside of the vacuum chamber 12 is fixed so as to be airtight by 11a and 12a. That is, the periphery of the furnace tube 11 is airtightly covered with the vacuum chamber 12 except for the insertion port side of the workpiece.

In the vacuum chamber 12, a heating heater 13 in which a heater wire made of tantalum, molybdenum, or the like is formed in a coil shape is disposed so as to be located outside the inserted core tube 11. Further outside the heater 13, similarly to the above-described embodiment, to cover the periphery thereof, the thickness is interposed between heat insulating layers 14a, 14b, and 14c made of a porous heat insulating material or the like, for example, Reflection material layers 15a and 15b made of a heat reflection material such as an aluminum thin film of about several tens to several hundreds of microns are arranged.

Similar reflector layers 15a and 15b are also provided on the bottom side and the inlet side of the furnace tube 11, that is, a vacuum chamber.
The inner wall of 12 is covered by the reflector layers 15a and 15b.

The vacuum chamber 12 is provided on its side with an electricity introduction port 16 and an exhaust port 17 for supplying electric power to the heater 13. The inside of the vacuum chamber 18 formed by the vacuum chamber 12 and the outer wall surface of the furnace tube 11 is set to a predetermined pressure, for example, several hundred Torr to about ^{10 −10} Torr by an exhaust mechanism (not shown) connected to the exhaust port 17. And maintained at this set pressure during the heat treatment.

The heat reflecting material for forming the reflecting material layers 15a and 15b is not limited to aluminum and platinum, but may be molybdenum, tantalum, stainless steel, or the like, since it is used in a vacuum and has a slow deterioration rate due to oxidation. Is also possible. However, when using a material having a low reflectance, it is preferable to use a mirror-finished surface.

Also in the heating furnace of this embodiment having the above-described configuration, a large number of semiconductor wafers are arranged in the furnace tube 11 and heat treatment such as thermal diffusion and CVD is performed in the same manner as in the above-described embodiment.

At this time, part of the heat generated by the heating of the heater 13 directly radiates and heats the inside of the core tube 11. The remaining heat radiated to the outer peripheral side is reflected toward the furnace tube 11 by the reflector layers 15a and 15b, and heats the inside of the furnace tube 11 by radiation. Since the heater 13 exists in the vacuum chamber 18 at a predetermined pressure, there is almost no heat loss due to convection of the heater 13 itself,
The furnace tube 11 can be efficiently heated.

Further, the core tube 11 itself is also inserted into the vacuum chamber 12, and since the outer periphery is vacuum insulated except for the insertion port side of the object, heat loss due to convection is extremely small. Can be uniformly heated. Therefore, the soaking zone can be set to be about 1.5 times longer than that of the conventional heating furnace, so that the furnace itself can be reduced in size and the power consumption can be significantly reduced.

FIG. 4 is a modified example of the above-described embodiment, and has a double tube structure having an insertion portion 21a of the furnace tube 11 so that the vacuum chamber 18 itself is formed by the vacuum chamber 21 forming the furnace body. Have been.

Further, in the vacuum chamber 21, the heater 13 and the reflective material layers 15a and 15b are provided, as in the above-described embodiment, to constitute a heating furnace.

Also in the heating furnace configured as described above, it is possible to prevent the heat loss due to the convection of the heater 13 by the vacuum chamber 18 in the vacuum chamber 21 and the heat loss due to the convection of the furnace core tube 11 as in the above-described embodiment. Similar effects can be obtained.

In addition, as in this embodiment, when the core tube 11 is arranged in the insertion portion 21a of the concave portion of the vacuum chamber 21, the vacuum chamber 2
If there is a gap between the core tube 11 and the furnace tube 11, the heat transfer efficiency is reduced. Therefore, it is preferable to interpose a heat-resistant filler having a high thermal conductivity in this gap.

In the above-described embodiment, the core tube itself is also vacuum-insulated by the vacuum chamber. However, by arranging only the heater in a vacuum, the heat generated from the heater can be efficiently transmitted to the core tube. And the thermal efficiency of the heating furnace can be improved.

[Effects of the Invention] As described above, according to the heating furnace of the present invention, it is possible to efficiently transmit the heat generated from the heater to the furnace tube, thereby improving the soaking characteristics and covering the semiconductor wafer or the like. It is possible to uniformly heat-treat the processed material. Further, since the soaking length can be set long, the furnace can be downsized and the power consumption can be greatly reduced, so that an economic heating furnace can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a heating furnace according to one embodiment of the present invention.
FIG. 3 is an enlarged longitudinal sectional view showing a main part of the heating furnace shown in FIG. 1, FIG. 3 is a longitudinal sectional view showing a heating furnace according to another embodiment of the present invention, and FIG. FIGS. 5 and 6 are longitudinal sectional views showing a modification of the heating furnace, and are characteristic diagrams showing the relationship between the thermal conductivity and the bulk density of the heat insulating material layer. 1, 11 ... core tube, 2 ... heat equalizing tube, 3, 13 ... heater,
4a to 4c, 14a to 14c ... heat insulation material layers, 5a, 5b, 15a, 15b ...
Reflective material layer, 6 heater case, 7 wafer port,
8 ... Semiconductor wafer, 12, 21 ... Vacuum chamber, 17 ...
Exhaust port, 18 Vacuum chamber.

Continuation of the front page (72) Inventor Teruo Iwata 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Inside Tokyo Electron Limited (56) References Japanese Utility Model Sho 49-131307 (JP, U) Japanese Utility Model Sho 58- 47013 (JP, U)

Claims (2)

(57) [Claims] 1. A heating furnace comprising: a heater disposed around a substantially cylindrical furnace tube; and a substantially cylindrical heat insulating material layer disposed outside the heater, wherein the heat insulating material layer comprises a plurality of heat insulating layers. A heating furnace, wherein the heating furnace is divided into layers and one or more reflecting material layers made of a heat reflecting material are provided between the plurality of heat insulating material layers. 2. A heating furnace comprising: a heater disposed around a substantially cylindrical furnace core tube; and a substantially cylindrical heat insulating material layer disposed outside the heater. The heat insulating material layer, the reflecting material layer, and the heater are provided with one or more reflecting material layers made of a heat reflecting material between the plurality of heat insulating material layers. A heating furnace, which is disposed inside.