JP3307924B2 - Heat treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a heat treatment apparatus, and more particularly, to a heat treatment apparatus for heat treating an object to be processed at a high temperature.

[0002]

[Background Art]

2. Description of the Related Art Conventionally, a heat treatment apparatus has been employed in a CVD apparatus of various thin film forming apparatuses in a semiconductor wafer manufacturing process, an epitaxial growth apparatus, an oxide film forming apparatus, or a thermal diffusion apparatus of a doping apparatus.

A general diffusion type heat treatment apparatus used for various kinds of heat treatment of a semiconductor wafer of this kind includes a process tube for forming a furnace chamber in which a plurality of semiconductor wafers to be processed are arranged;
A heating resistor is provided on the outer periphery of the process tube, and a heat insulating material is provided to surround the heating resistor.

In this case, a spiral heater made of FeCrAl or the like is used as a heating resistor, so that the furnace chamber can be heated to a high temperature of, for example, about 1200 ° C.

[0005] In addition, ceramic fibers or the like are used as the heat insulating material, and the amount of heat taken as radiant heat and conductive heat is reduced so that heating can be performed efficiently.

[0006]

[Problems to be solved by the invention]

In the above-mentioned conventional general diffusion type heat treatment apparatus, a heater made of FeCrAl is used as a heating resistor of the heating apparatus, and since the allowable current density of the heater is not so high, the temperature rise / fall rate in the furnace chamber is reduced. For example, only about 10 ° C. can be obtained in one minute, so that there is a problem that high-speed temperature raising / lowering processing cannot be performed and the processing speed is slow.

On the other hand, there is also known a lamp heating type heat treatment apparatus which raises and lowers the temperature by 500 to 1000 ° C. in 10 seconds, for example, but in this case, the in-plane temperature difference of the semiconductor wafer is large. In addition, there has been a problem that the in-plane temperature difference of the semiconductor wafer becomes, for example, about 40 ° C., and crystal defects such as slips occur in the semiconductor wafer.

[0008] Furthermore, the heating resistor heated to a high temperature has a large thermal deformation, and when the heating resistor and the heat insulating material come into contact with each other, the heating resistor and the heat insulating material react with each other, causing a problem that the heating resistor is disconnected. .

Therefore, the present invention provides a heat treatment apparatus that enables high-speed temperature rise / fall processing in a furnace chamber, can increase the processing speed of an object to be processed, and does not disconnect the heating resistor due to a thermal reaction. That is the challenge.

[0010]

[Means for Solving the Problems]

The present invention has been made to solve the above problems,
As a means for solving the problem, the heat treatment apparatus of the present invention includes a process tube forming a furnace chamber in which a plurality of workpieces are arranged, a heating resistor arranged on an outer peripheral side of the process tube, and surrounding the heating resistor. A heat insulating material, wherein the heat generating resistor is formed of molybdenum disilicide, and is attached to the heat insulating material without being in contact with the heat insulating material. The surface is formed of a material inert to silicon dioxide.

In the heat treatment apparatus having the above configuration, the heat generating resistor made of molybdenum disilicide has an allowable surface load density of 1200 ° C.
In large as about 20W / cm ^2. For this reason, the furnace chamber is heated at 50 to 100 ° C. per minute after the power is turned on.

Therefore, the temperature inside the furnace chamber can be raised and lowered at a high rate without causing slips or crystal defects.

Further, when the heating resistor made of molybdenum disilicide is heated, silicon dioxide is deposited on the surface, and forms a surface protection film of the heating resistor.

When the silicon dioxide reacts with a heat insulating material surrounding the heat generating resistor, the surface protective film is eroded, causing the heat generating resistor made of molybdenum disilicide to be disconnected. Is formed of a material that is inactive with respect to the above, so that the heating resistor does not break.

In addition, since the surface of the heat insulating material is formed of a material inert to silicon dioxide, the heat insulating material can be formed more easily and reliably than when a separate member is attached to the surface.

Further, since the heat generating resistor is attached to the heat insulating material in a state of not contacting the heat insulating material, it is possible to more reliably prevent the heat generating resistor that has become hot from reacting upon contact with the heat insulating material and breaking. can do.

In this case, the heat insulating material has a substantially cylindrical shape, and the heating resistor has a substantially cylindrical shape, and is disposed substantially concentrically on the inner peripheral side of the heat insulating material, and the heat insulating material forms The inner diameter of the cylindrical shape can be larger than the outer diameter of the cylindrical shape formed by the heating resistor.

With such a configuration, the heat generating resistor does not contact the heat insulating material because the inner diameter of the cylindrical shape formed by the heat insulating material is larger than the outer diameter of the cylindrical shape formed by the generating resistor.
The heat-generating resistor which has been heated to high temperature contacts and reacts with the heat insulating material, and does not break.

In the present invention, the heat insulating material may have a substantially vertical inner surface, and the heat generating resistor may be attached to the inner surface of the heat insulating material so as to be stretchable.

With this configuration, since the heat generating resistor is attached to the heat insulating material so as to be able to expand and contract on the substantially vertical inner surface, a change in the vertical length due to thermal expansion and contraction of the heat generating resistor can be prevented. It can be tolerated, and stress is not generated due to thermal expansion or contraction, and disconnection does not occur.

In the present invention, the heating resistor is formed in a meandering string shape, and can be suspended at a bent portion.

With such a configuration, since the meandering string-shaped heating resistor is hung at the bent portion and attached to the heat insulating material, the heating resistor can expand and contract, and therefore, the thermal expansion of the heating resistor In addition, a change in length in the vertical direction due to contraction can be tolerated, and there is no possibility that stress is generated due to thermal expansion or contraction and disconnection or the like occurs.

In the present invention, the heating resistor is attached to the heat insulating material by staples, and the staples are formed at least on a surface of a material inert to silicon dioxide, or And the same material.

With this configuration, since at least the surface of the staple for attaching the heating resistor to the heat insulating material is formed of a material inert to silicon dioxide, the heating resistor made of silicon dioxide and the staple are formed. Does not react and the surface protection film of the heating resistor is not eroded, so that the possibility of disconnection of the heating resistor can be reduced.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 to FIG. 5 are diagrams showing an embodiment of the present invention.

This embodiment shows a vertical heat treatment apparatus used for manufacturing a semiconductor wafer.

In this heat treatment apparatus, a process tube 10 made of quartz is vertically supported on a base plate 12 made of, for example, stainless steel.
A furnace chamber 14 is formed inside the furnace. Also,
The process tube 10 is housed in a casing 32.

A boat 20 mounted on a heat retaining tube 18 can be inserted into and removed from a furnace chamber 14 formed by the process tube 10. The wafers 22 are horizontally arranged and supported at equal intervals, and a gas is supplied from a processing gas supply source (not shown) so that a vapor phase growth process can be performed on the semiconductor wafer 22. In addition, heat insulation tube 18
Is mounted on a flange cap 24. The flange cap 24 is attached to an elevator arm (not shown) and moves up and down to move the heat retaining cylinder 18 and the boat 20 up and down.
Can be sealed.

A heating resistor 30 is provided on the outer periphery of the process tube 10, and a heating resistor 30 is provided outside the heating resistor 30.
A heat insulating material 34 that supports and surrounds 30 is provided.

The heating resistor 30 divides the inside of the furnace chamber 14 into, for example, three zones, that is, a top, a center, and a bottom, and heats the top, center, and bottom of the furnace chamber 14 under suitable temperature conditions. It employs a three-zone system constituted by the respective heating resistors 30a, 30b, 30c. The zone division is not limited to three zones, but may be determined as needed, such as five zones. Further, the heat insulating material 34 is also constituted by heat insulating members 34a, 34b and 34c on the top side, the center side and the bottom side corresponding to the three zones of the top, center and bottom.

Further, these heat insulating members 34a, 34b, 34c are cylindrical, and are formed by combining two semi-cylindrical members. , 30
b and 30c are also designed to combine two semi-cylindrical members.

The heating resistors 30a, 30b, 30c are made of molybdenum disilicide (M
oSi ₂ ). Specifically, a heater mainly composed of molybdenum disilicide (MoSi ₂ ) (a Kanthal super heating element manufactured by Kanthal) can be employed. The heating resistors 30a, 30b and 30c made of molybdenum disilicide have a very small resistance at room temperature, and have a large resistance at high temperatures. Molybdenum disilicide is a commonly used FeCr
The maximum surface load of the Al heating element is 2 W / cm ^{2 at} 1200 ° C.
On the other hand, the heating value is 10 times as large as 20 W / cm ² , a strong power increase is obtained, and the temperature rise of the conventionally used FeCrAl heating element is 10 ° C./min, The temperature rise can be made rapid at 100 ° C / min.

The heating resistors 30a, 30b, and 30c are the same as those shown in FIGS.
As shown in the figure, one wire rod is bent in a U-shape at the upper and lower portions to form a vertically continuous Myanda shape.

Then, as shown in FIGS. 3 to 5, the heating resistors 30a, 30b, 30c formed in the shape of a mound are attached to and held by the staples 36 on the inner surfaces of the heat insulating members 34a, 34b, 34c. It is made to let. The staple 36 is attached to the top of each bent portion above the heating resistors 30a, 30b, and 30c to suspend and support the heating resistors 30a, 30b, and 30c, as well as the heating resistors 30a, 30b, and 30c. In the lower part, the position is fixed by supporting the linear part avoiding each bent part, and by keeping the lower ends of the heating resistors 30a, 30b, 30c in an open state in this way, the heating resistor 30a, 3
A change in length in the vertical direction due to thermal expansion and contraction of 0b and 30c is allowed.

Further, the heating resistors 30 a, 30 b, and 30 c form a surface protection film of the heating resistor 30 on which silicon dioxide (SiO ₂ ) is deposited when heated, and the heating resistor 30 is exposed to the air. It reacts with the oxygen inside and oxidizes to prevent disconnection. At least the surface of the staple 36 that is in direct contact with the heating resistors 30a, 30b, 30c is formed of a material that is inert to the silicon dioxide even at a high temperature of, for example, 1200 ° C., and the deposited silicon dioxide is eroded. Heating resistor
30 does not break at the contact portion of the staple 30. Examples of materials inert to silicon dioxide include iron Fe, copper Cu, and nickel Ni. The entire staple 36 may be formed of a material inert to silicon dioxide or the same material as the heating resistors 30a, 30b, 30c.

As shown in FIG. 5, the heating resistors 30 a, 30 b, and 30 c have bent portions at their respective ends alternately longer and shorter at an adjacent boundary portion. The parts are alternately arranged in a meshing state. Therefore, the heating resistors 30a, 30b, and 30c are arranged without gaps at the adjacent boundaries, so that uniform heating can be performed at the boundaries between the top, center, and bottom zones. A plurality of heating resistors may be combined vertically in each of the top, center, and bottom zones. In this case, the zones may be alternately combined in each adjacent portion as described above. The inside can be maintained at a uniform temperature. Further, the combination state is not limited to the above example, and various combinations that can maintain a uniform temperature are possible.

In the heat insulating material 34, the heat insulating members 34a, 34b and 34c are formed of ceramic fibers. As shown in FIG. 2, these heat insulating members 34a, 34b, 34c
b, so as not to corrode react with 30c, the radius r ₁ is the heat generating resistor 30a, 30b, is set larger than the radius r ₂ of 30c,
The heating resistors 30a, 30b, and 30c are not in contact with each other.

The surface 38 of the heat insulating members 34a, 34b, 34c is formed of a material inert to silicon dioxide, so that the heat generating resistors 30a, 30b, 30c are deformed and heat-insulated even when heated. Even if the heating resistors 30a, 30c contact the members 34a, 34b, 34c,
The silicon dioxide film formed on the surfaces of b and 30c is not corroded and disconnected. As the material inert to silicon dioxide, for example, iron F
e, copper Cu, nickel Ni and the like. The surface 38 made of silicon dioxide and an inert material may be formed by coating or lamination, and various means can be adopted.

As described above, the heat insulating members 34 a, 34 b, 34 c and the heating resistor 3
0a, 30b, 30c, in addition to the non-contact structure, heat insulating members 34a, 34c
By forming the surface 38 of b and 34c with silicon dioxide and an inert material, erosion of the silicon dioxide film formed on the surface of the heating resistor 30 is prevented.

In this embodiment, as described above, the heating resistors 30 a, 30 b, and 30 c of the heating device 28 are made of molybdenum disilicide, so that the temperature can be raised and lowered at a high speed. Speed can be improved.

By forming the surface of the staple 36 for fixing the heating resistors 30a, 30b, and 30c with silicon dioxide and an inert material, the silicon dioxide film formed on the surface of the heating resistor 30 Erosion can be prevented.

Further, the heat insulating members 34 a, 34 b, 34 c and the heating resistor 30 a,
In addition to the non-contact structure with 30b and 30c, even if the heating resistor 30 is deformed due to heat generation and comes into contact with the heat insulating member 30, the heat insulating member 34
By forming the surface 38 of a, 34b, 34c with an inert material with silicon dioxide, the heat insulating members 34a, 34b, 34c react with the silicon dioxide deposited on the surface of the heating resistors 30a, 30b, 30c. It is possible to prevent erosion and disconnection of the heating resistor.

In the above embodiment, the vertical type heat treatment apparatus has been described. However, the present invention is not limited to this and can be applied to a horizontal type heat treatment apparatus. In this case, it is preferable to use each heating resistor that is folded back in a horizontal shape. When fixing this heating resistor to a heat insulating member, both ends of the heating resistor are not fixed and an intermediate portion is provided. It is good to fix a straight line part, and to be able to expand and contract in the left-right direction.

As described above, in the heat treatment apparatus of the present invention, since the heating resistor of the heating device is formed of molybdenum disilicide, this heating resistor has a maximum surface load of a normal heating element. The furnace chamber is heated up ten times, and is rapidly heated after the power is turned on. Accordingly, there is an effect that the temperature in the furnace chamber can be raised and lowered at high speed, and the processing speed of the semiconductor wafer can be improved.

In addition, since the surface of the heat insulating material provided to surround the heating resistor is formed of a material inert to silicon dioxide, the heating resistor is heated and deformed. Even if it comes into contact with the material, this silicon dioxide does not react with the heat insulating material, so that the silicon dioxide film formed on the surface of the heating resistor can be prevented from being eroded, and the disconnection of the heating resistor can be prevented. There is an effect that it can be prevented.

Further, since the surface of the heat insulating material is formed of a material inert to silicon dioxide, the heat insulating material can be formed more easily and reliably than when a separate member is attached to the surface.

Further, since the heat generating resistor is attached to the heat insulating material without being in contact with the heat insulating material, it is possible to more reliably prevent the heat generating resistor that has become hot from reacting upon contact with the heat insulating material and disconnection. can do.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a vertical heat treatment apparatus according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a heat generating resistor and a heat insulating material part of FIG.

FIG. 3 is a partial perspective view of the heat generating resistor and the heat insulating material shown in FIGS. 1 and 2;

FIG. 4 is an enlarged sectional view of a heating resistor and a heat insulating material.

FIG. 5 is a front view showing an arrangement state of a heating resistor.

[Explanation of symbols]

 10 Process tube 14 Furnace chamber 22 Semiconductor wafer 28 Heating device 30a, 30b, 30c Heating resistor 34 Heat insulating material 34a, 34b, 34c Heat insulating member 36 Staple 38 ... the surface of the heat insulating member

Continuation of the front page (51) Int.Cl. ⁷ identification code FI H05B 3/14 H05B 3/14 D 3/66 3/66 (58) Field surveyed (Int.Cl. ⁷ , DB name) F27D 11/02 F27B 17/00 H01L 21/205 H01L 21/31 H05B 3/14 H05B 3/66 H01L 21/324

Claims (5)

(57) [Claims] 1. A process tube forming a furnace chamber in which a plurality of workpieces are arranged, a heating resistor arranged on an outer peripheral side of the process tube, and a heat insulating material provided to surround the heating resistor. Wherein the heat generating resistor is formed of molybdenum disilicide,
The heat treatment apparatus, wherein the heat insulation material is attached to the heat insulation material without being in contact with the heat insulation material, and the heat insulation material has a surface formed of a material inert to silicon dioxide. 2. The heat-insulating material has a substantially cylindrical shape, the heat-generating resistor has a substantially cylindrical shape, and is disposed substantially concentrically on the inner peripheral side of the heat-insulating material, and the heat-insulating material forms a cylindrical shape. The heat treatment apparatus according to claim 1, wherein an inner diameter of the shape is larger than an outer diameter of a cylindrical shape formed by the heating resistor. 3. The heat insulating material has a substantially vertical inner surface, and the heat generating resistor is attached to the inner surface of the heat insulating material so as to be extendable and contractible. 3. The heat treatment apparatus according to 2. 4. The heating resistor according to claim 1, wherein the heating resistor is formed in a meandering string shape, is suspended at a bent portion, and is attached to a heat insulating material. The heat treatment apparatus according to any one of the above. 5. The heating resistor is attached to the heat insulating material by staples, wherein the staples are formed at least on a surface of a material inert to silicon dioxide, or are the same as the heating resistor. The heat treatment apparatus according to any one of claims 1 to 4, wherein the heat treatment apparatus is formed of a material.