Heat treatment apparatus

A heating means is disclosed which comprises a reflector plate composed of an opaque quartz and a quartz tube welded to the surface of the reflector plate. A carbon wire which generates heat when a current is applied is inserted in the quartz tube.

FIELD OF THE INVENTION

The present invention relates to a heat treatment apparatus for the heat treatment of a semiconductor wafer or the like; and a heating unit and a mounting table for use therein.

BACKGROUND OF THE INVENTION

In general, in a manufacturing process of semiconductor integrated circuits, various single-substrate processes, such as a film forming process, an etching process, a heat treatment process, a quality modification process, a crystallization process, are repeated on a target object such as a semiconductor wafer to build up the desired integrated circuits. In the various processes described above, required gases corresponding to specific processes, e.g., a film forming gas for the film forming process, an ozone gas or the like for the quality modification process, and an O2gas or an inactive gas such as N2for the crystallization process, are introduced into processing chambers.

For example, in case of a single-wafer heat treatment apparatus which performs heat treatment on semiconductor wafers on a single wafer basis, a mounting table which includes, e.g., a built-in resistance heater or the like is installed in a vacuum-evacuable processing chamber and a semiconductor wafer is mounted on the top surface of the mounting table. Under these circumstances, a processing gas is introduced into the processing chamber, and heat treatment is variously performed on the semiconductor wafer under a process condition (see, for example, Japanese Patent Laid-open Application No. 2002-256440).

In a heat treatment apparatus of a different type, an inner processing chamber made of, e.g., quartz glass is provided in a vacuum-evacuable processing chamber made of, e.g., aluminum, and a substrate supporting table which includes a built-in resistance heater is prepared in the inner processing chamber. The inner processing chamber is supplied with a plurality of processing gases of different species flowing alternately in an intermittent manner. Hence, thin films each being about one molecular layer in thickness can be repeatedly laminated on the surface of the semiconductor wafer supported on the substrate supporting table (see, for example, Japanese Patent Laid-open Application No. 2002-151489).

However, it is required to make each layer thinner as well as to make the line width narrower in accordance with the high integration and the high miniaturization of the semiconductor integrated circuits. Under the circumstances, stricter standards for contamination, such as organic contamination and metal contamination, are also required. Therefore, structures in the processing chamber are made of purer materials which do not contain metal species serving as a source of contamination. The structures in the processing chamber include, e.g., a heater for heating a semiconductor wafer or the like, and a mounting table which supports a wafer. A mounting table was also proposed, wherein a heater is completely covered with high purity quartz plates and/or quartz cases thermally bonded as a single unit (see Japanese Patent Laid-open Application No. S63-278322, Japanese Patent Laid-open Application No. H07-078766, Japanese Patent Laid-open Application No. H03-220718, or Japanese Patent Laid-open Application No. H06-260430).

To encapsulate the whole heater inside the quartz plates and/or the quartz cases, planar quartz surfaces are required to be thermally bonded together. Therefore, quartz needs to be machined with good flatness. That is, surface processing of quartz is needed with high accuracy. Such a process, however, is very difficult, and the apparatus itself becomes costly.

Further, in case of using transparent quartz material, thermal efficiency becomes poor since heat rays from the heater buried inside the quartz radiate in all directions.

Moreover, if the heater material contains metal atoms of, e.g., heavy metals, a semiconductor wafer can be contaminated by such metal atoms even when the heater is completely encapsulated with quartz. That is because such metal atoms can move across the quartz by so-called thermal diffusion.

SUMMARY OF THE INVENTION

The present invention has been contrived on the basis of the aforementioned problems to solve them effectively. It is, therefore, an object of the present invention to provide a heating unit, a mounting table, and a heat treatment apparatus which can suppress such contaminations as organic contamination and metal contamination, and can be manufactured relatively easily and inexpensively.

The present invention provides a heating unit including: a reflector plate made of an opaque quartz; and a quartz tube welded to a surface of the reflector plate, wherein a carbon wire which generates heat when a current is applied thereto is inserted in the quartz tube.

In accordance with the present invention, a target object can be heated while barely suffering from organic contamination and/or metal contamination. Further, the heating unit of the present invention can be manufactured relatively easily and inexpensively.

Preferably, the quartz tube is bent.

Further, on the surface of the reflector plate, the quartz tube is preferably divided and welded to a plurality of zones.

The heating unit can be placed in a mounting table. That is, the present invention provides a mounting table includes: the heating unit having the above-described features; and a mounting table cover member installed to cover the whole quartz tube of the heating unit, a target object being mounted thereon, wherein the mounting table cover member is made of a light absorbing material.

In this case, the mounting table cover member is made of, e.g., SiC.

Further, the mounting table is employed in a heat treatment apparatus. That is, the present invention provides a heat treatment apparatus including: the mounting table having the above-described features; a processing chamber accommodating therein the mounting table; a gas supply unit for supplying a predetermined gas in the processing chamber; a vacuum pumping system for evacuating the inside of the processing chamber to vacuum.

Further, another embodiment of the present invention provides a heat treatment apparatus including: a mounting table on which a target object is mounted; a processing chamber accommodating therein the mounting table; a gas supply unit for supplying a predetermined gas in the processing chamber; a vacuum pumping system for evacuating the inside of the processing chamber to vacuum; and the heating unit, having the above-described features, prepared in the processing chamber so as to face the mounting table.

In this case, for example, an additional inner vessel can be installed to cover an upper side of the mounting table.

Still further, the present invention provides a heat treatment apparatus including: a mounting table on which a target object is mounted; a processing chamber accommodating therein the mounting table; a gas supply unit for supplying a predetermined gas in the processing chamber; a vacuum pumping system for evacuating the inside of the processing chamber to vacuum; a target object heating unit for heating the target object; an inner vessel installed in the processing chamber; the heating unit having the above-described features and installed between the inner vessel and an inner wall of the processing chamber to apply heat to the inner vessel.

In this case, the inner vessel is made of, e.g., sic.

Further, in this case, the target object heating unit is preferably built in the mounting table integrally.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a heating unit, a mounting table and a heat treatment apparatus in accordance with preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

A First Preferred Embodiment

FIG. 1provides a cross sectional configuration view of a heat treatment apparatus in accordance with the first preferred embodiment of the present invention;FIG. 2shows a cross sectional view of an arrangement of quartz tubes provided in the mounting table;FIG. 3presents a cross sectional view of the mounting table; andFIG. 4sets forth an exploded view of the mounting table.

As shown, a heat treatment apparatus2has a processing chamber4whose inside is roughly cylindrical in shape and which is made of aluminum. Provided at the ceiling portion of the processing chamber4is a shower head unit6which is a gas supply means used to introduce necessary processing gases, for example, film forming gas. A gas injection surface8which is a bottom surface of the shower head unit6has a plurality of gas injection openings10A and10B. And, the processing gases are injected from the plurality of gas injection openings10A and10B to a processing space S.

Formed in this shower head unit6are two partitioned hollow gas diffusion areas12A and12B. The processing gases are diffused in the horizontal direction in the gas diffusion areas12A and12B, and then injected from the gas injection openings10A and10B connected to the gas diffusion areas12A and12B, respectively. That is, the gas injection openings10A and10B are arranged in a matrix shape.

The whole shower head unit6is made of, for example, nickel, nickel alloy such as Hastelloy (trademark) or the like, aluminum, or aluminum alloy. The shower head unit6may have only one gas diffusion area. And, at a joint portion between the shower head unit6and a top opening portion of the processing chamber4, a sealing member which is composed of, e.g., an O-ring or the like is placed. Accordingly, airtightness is maintained in the processing chamber4.

On a sidewall of the processing chamber4, a loading/unloading port16is installed to load and unload a semiconductor wafer W as a target object. At the loading/unloading port16, a gate valve18capable of airtightly opening and closing the loading/unloading port16is installed.

And, an exhaust space22is formed at a bottom portion20of the processing chamber4. Specifically, a large opening24is formed at the center of the bottom portion20of the processing chamber4, and a cylindrical partition wall26of a cylindrical body which has a bottom portion is extended downward from the opening24, and the inside of the cylindrical partition wall26serves as the exhaust space22. At the bottom portion28of the cylindrical partition wall26which partitions off the exhaust space22, there is provided an upright cylindrical support column30made of, e.g., quartz glass. A mounting table32is fixed by welding onto an upper portion of the cylindrical support column30. Further, the cylindrical support column30can be made of ceramic such as AlN.

The diameter of the opening24on the entrance side of the exhaust space22is set to be less than that of the mounting table32. Accordingly, a processing gas which flows downward through the outside of the peripheral portion of mounting table32, flows around to the bottom portion of the mounting table32, and then flows into the opening24. On a lower sidewall of the cylindrical partition wall26, there is formed a gas exhaust port34connected to the exhaust space22. A vacuum pumping system38is connected to the gas exhaust port34. Specifically, the vacuum pumping system38is formed of a gas exhaust line36equipped with a vacuum pump (not shown). Accordingly, the atmosphere inside the processing chamber4and the exhaust space22can be pumped to be evacuated to vacuum.

A pressure control valve (not shown) capable of controlling the opening ratio is installed in the middle of the gas exhaust line36. The internal pressure of the processing chamber4can be maintained at a constant level by controlling the opening ratio of the pressure control valve automatically, or a pressure value can be adjusted quickly to a desired level.

Further, the mounting table32is provided with a heating unit40which is a feature of the present invention. A mounting table cover member42is installed to cover the heating unit40. At the top surface of the mounting table cover member42, a semiconductor wafer W can be mounted as a target object. The configurations of the mounting table32and the heating unit40will be described in detail hereinafter.

The heating unit40is connected to feeder lines44disposed in the support column30. Accordingly, while being controlled, electric powers are supplied to the heating unit40. These feeder lines44are inserted in quartz tubes (not shown) in the drawings, and are connected to the power cables under the support column30. Further, as will be described later, the heating unit40is divided into, for example, an inner zone and an outer zone which encloses the exterior of the inner zone in a concentric circular shape to control an electric power of each zone separately. For that purpose, four feeder lines44(seeFIG. 3) are prepared in an example shown in the drawing.

A plurality of, for example, three pin insertion through holes46is provided through the mounting table32in vertical direction (FIG. 1illustrates only two pin insertion through holes). A vertically movable upthrust pin48is inserted loosely through each pin insertion through hole46. Under the upthrust pins48, a circular ring-shaped upthrust ring50made of ceramic such as alumina is arranged. That is, the bottom of each vertically movable upthrust pin48is not fixedly supported by upthrust ring50. An arm unit52extended from the upthrust ring50is connected to up/down rod54which passes through a bottom portion20, and the up/down rod54is driven vertically by an actuator56. Accordingly, the upthrust pins48move up or down from the upper end of pin insertion through holes46when replacing the wafer W. Further, between the actuator56and a through portion, at the bottom portion20of the processing chamber4, through which the up/down rod54of the actuator56passes, an expansible bellows58is interposed. Accordingly, the up/down rod54can be vertically movable while maintaining the airtightness of the processing chamber4.

The mounting table32and the heating unit40will now be described in detail with reference toFIGS. 2 to 4. The upthrust pins48and the pin insertion through holes46(seeFIG. 1) are omitted inFIGS. 2 to 4.

As shown inFIGS. 3 and 4, the mounting table32is primarily composed of the heating unit40and the mounting table cover member42prepared to cover the whole top surface of the heating unit40. Here, the heating unit40functions as a target object heating unit which applies heat to the wafer W.

Specifically, the heating unit40has a circular plate-shaped reflector plate60which has a greater diameter than that of the wafer W. The whole reflector plate60is made of strongly heat-resistant opaque quartz which is white turbid since it is intermixed with fine bubbles. In this case, the surface of the reflector plate60is non-transparent to externally incident heat rays, and reflects the heat rays with high reflectivity. The opaque quartz forming the reflector plate60can be intermixed with any materials other than bubbles and the surface thereof may be mirror finished as long as it is non-transparent to heat rays.

Moreover, an upright positioning projection61is prepared in the upper direction at the peripheral region of the reflector plate60. The positioning projection61performs the positioning of the mounting table cover member42which is inserted by the positioning projection61. The positioning projection61can be made into a ring-shape by using the same material as that of the reflector plate60. It can be installed integrally with the reflector plate60or separately from the reflector plate60. In addition to performing the positioning of the mounting table cover member42as described above, the positioning projection61contacts with the mounting table cover member42, and also functions to transfer heat efficiently from the reflector plate60to the mounting table cover member42(wafer W side). Accordingly, the falling of the temperature at the peripheral region of a wafer can be prevented and thus the temperature difference between the central portion and the peripheral portion of the wafer decreases.

And, the top end of the support column30made of quartz is welded around the center portion of the bottom surface of the reflector plate60. Further, strongly heat-resistant and transparent quartz tubes62which are formed to be bent in a predetermined shape are welded to the top surface of the reflector plate60. Carbon wires64which generate Joule heat when a current is applied thereto are inserted in these quartz tubes62. A heater of this kind formed by inserting the carbon wire64in the quartz tube62is described in, e.g., Japanese Patent Laid-open Application No. 2001-208478 describes. When jointing the quartz tubes62to the surface of the reflector plate60, joint pins66, also made of quartz, are used. Specifically, these joint pins66are disposed at proper places between the quartz tubes62and the reflector plate60, and by melting them, the quartz tubes62and the reflector plate60are welded together.

Herein, as shown inFIG. 2, the quartz tubes62are formed to be bent so that they include a quartz tube portion62A in an inner zone and a quartz tube portion62B in an outer zone which encompasses the exterior of the quartz tube portion62A. Each of the quartz tube portions62A and62B has two concentric circular portions and two end portions which are concentered at the central portion of the reflector plate60for supplying electric power. The both end portions pass through the reflector plate60downward. And, as described above, the carbon wire64in each of the quartz tube portions62A and62B is connected to the feeder lines44. Accordingly, application of electric power can be controlled separately in each zone. Further, the number of zones is not limited to 2. It may be 3 or more.

Each of the quartz tube portions62A and62B can be easily bent in a desired shape by heat process. Further, the quartz tube portions62A and62B are easily jointed to the surface of the reflector plate60by using the joint pins66. Heat rays from the carbon wires64in the quartz tube portions62A and62B are reflected at the surface of the reflector plate60which has high heat-resistance, and directed upward in the example shown in the drawing.

Further, the mounting table cover member42is installed to cover the whole top surface of the heating unit40fabricated as described above. As a result, the whole mounting table32is constructed. Specifically, the mounting table cover member42is formed to have a circular lid shape and made of light absorbing material, e.g., SiC, which has a good thermal conductivity but with negligible metal impurities. An inner surface of a sidewall42A of the lid-shaped mounting table cover member42is set to have a slightly greater diameter than that of the reflector plate60, and it is in close contact with a side surface of the reflector plate60to be generally circumscribed thereto. Thus, when being attached to the reflector plate60from above, the mounting table cover member42is combined with the reflector plate60while being positioned at a specific place by the positioning projection61. And, the wafer W is mounted on the top surface of the mounting table cover member42. Further, the inner space of the mounting table cover member42may be sealed completely by airtightly thermal-bonding the peripheral regions of the mounting table cover member42and the reflector plate60together, and further, by thermal-bonding quartz pipes at portions of the pin insertion through holes46(seeFIG. 1).

Hereinafter, the operation of the heat treatment apparatus with the above configuration will now be described.

First of all, a semiconductor wafer W not processed is held by a transfer arm (not shown) and loaded into the processing chamber4through the open gate valve18and the loading/unloading port16. This wafer W is loaded on the upthrust pins48which are in their elevated position. And then, the upthrust pins48move down, and the wafer W is mounted and supported on the top surface of the mounting table32, specifically on the top surface of the mounting table cover member42.

And then, flow-controlled processing gases, e.g., film forming gases such as TiCl4, H2, NH3, WF6, SiH4, H2, PET, and O2, are supplied into the shower head unit6. These gases are emitted (injected) through the gas injection holes10A and10B into the processing space S. And, by driving continuously the vacuum pump (not shown) connected to the vacuum gas exhaust line36, the atmosphere in the processing chamber4and the exhaust space22is exhausted to vacuum; and further, the opening ratio of the pressure control valve is controlled automatically, and thus the atmosphere in the processing space S is maintained at a predetermined process pressure level. At this time, the wafer W is heated by the heating unit40provided in the mounting table32and thus the temperature of the wafer is maintained at a predetermined process temperature level. Accordingly, thin films such as Ti, TiN, W, WSi, Ta2O5are formed on the surface of the semiconductor wafer W. Further, when using TMA (Tri-Methyl Aluminum) and ozone as film forming gases, an alumina (Al2O3) film can be formed.

In the above process, heat rays from the carbon wires64inserted in quartz tubes62(62A and62B) of the heating unit40radiate in all directions. Heat rays emitted downward, however, are reflected upward at the surface of the reflector plate60supporting and fixing quartz tubes62and made of opaque quartz, and thus apply heat to the mounting table cover member42, and further, the wafer W mounted on the top surface thereof.

The reflector plate60which constitutes the heating unit40is made of high-purity opaque quartz which contains hardly any impurities. The quartz tubes62and the carbon wires64also contain hardly any impurities and thus have high purity. Accordingly, contamination such as organic contamination and/or metal contamination can be substantially suppressed. Moreover, the relatively easy fabrication processes for the reflector plate60and the quartz tubes62substantially reduce the manufacturing cost. Further, thermal energy can be used effectively and efficiently by using the reflector plate60.

The mounting table cover member42, which is a part constituting the mounting table32, is made of a light absorbing material, e.g., SiC, having a good thermal conductivity and a high purity. Therefore, the mounting table cover member42can be heated while maintaining the in-surface temperature uniformity of the wafer W at a high level. The mounting table cover member42can be made of arbitrary light absorbing material, e.g., opaque quartz intermixed with carbon.

Furthermore, a large amount of electric power can be supplied since the main components of the heating unit40are made of quartz, strongly resistant to thermal shocks. Accordingly, a high temperature rising rate, for example, about 1000° C./5 minutes can be obtained.

A Second Preferred Embodiment

Hereinafter, the second preferred embodiment of the present invention will be described.

FIG. 5depicts a cross sectional configuration view of a heat treatment apparatus in accordance with the second preferred embodiment of the present invention;FIG. 6is a perspective view of a heating unit for use in the second preferred embodiment; andFIG. 7provides a partially enlarged cross sectional view of the heating unit shown inFIG. 6.

The heat treatment apparatus70of the second preferred embodiment has a cylindrical processing chamber4′ made of, for example, aluminum. In the processing chamber4′, a rectangular-shaped space is provided, for example. At the ceiling of the processing chamber4′, a ceiling portion74made of, for example, aluminum or the like is attached via a sealing member72which is formed of, e.g., O-ring or the like.

And, at the central portion of the bottom portion20′ of the processing chamber4′, a cylindrical mounting table receiving vessel76of a relatively large-diameter, is formed in a downward protruding shape. In the mounting table receiving vessel76, a mounting table78made of ceramic, e.g., SiC or the like, is installed for mounting thereon a semiconductor wafer W as a target object. Inside the mounting table78, e.g., a resistance heater80which is a target object heating unit to apply heat to the wafer W is encapsulated. At a central portion of the bottom surface of the mounting table78, a rotation axis83extended downward is fixedly attached. The rotation axis83passes through a bottom plate82of the mounting table receiving vessel76via, e.g., a rotatable magnetic fluid sealing84. Accordingly, the rotation axis83is supported rotatably and airtightly. Further, the bottom plate82is airtightly jointed to the lower end of the mounting table receiving vessel76by an expansible and contractible bellows86. Accordingly, the bottom plate82and the mounting table78can be vertically movable as a unit by an actuator (not shown). Further, lifter pins (not shown) are provided on the bottom plate82for lifting the wafer W. Further, on a lower sidewall of the mounting table receiving vessel76, a gate valve88opened and closed when the wafer W is loaded and unloaded is installed. As the mounting table78is placed at a lowered position, the loading and the transport of the wafer W are performed via the gate valve88between the inside and the outside.

Further, in the processing chamber4′, two, i.e., a first and a second, gas supply units90and92are installed on two opposite sides with the mounting table78being at the center therebetween. From the first and the second gas supply units90and92, flow-controlled processing gases, e.g., film forming gases, are supplied when necessary. The first and the second gas supply units90and92are formed of, e.g., heat-resistant quartz pipes and have nozzles90A and92A. The respective nozzles90A and92A can be arranged on two opposite sides in the processing chamber4′ in such a manner that a plurality of nozzles is arranged in parallel on each side. In this case, the processing gases can be supplied in a planar shape.

On two sides of the bottom portion of the processing chamber4′, two, i.e., a first and a second, vacuum pumping systems94and96are installed in a manner of corresponding to the first and the second gas supply units90and92. The atmosphere in the processing chamber4′ can be pumped to be evacuated to vacuum by vacuum pumps (not shown) of the vacuum pumping systems94and96when necessary. In this case, the first and the second vacuum pumping systems94and96are respectively connected to the gas exhaust ports94A and96A fronting the processing space.

Inside the processing chamber4′, a lid-shaped inner vessel98is installed in such a manner of covering processing space S on the mounting table78. The inner vessel98has a good heat resistance, and further, it is made of a high-purity light absorbing material, e.g., SiC, which contains hardly any impurities of metal atoms or the like. The inner vessel98has the functions to be heated and thus accelerate the process reactions, and to align the gas flow of the processing gases. And, a heating unit100which is the feature of the present invention is installed between the inner vessel98and a wall surface of the ceiling plate74of the processing chamber4′. The basic configuration of the heating unit100is substantially the same as that of the heating unit40described in conjunction withFIGS. 2 to 4.

That is, as shown inFIGS. 6 and 7, the heating unit100has a substantially rectangular-shaped reflector plate102which is greater than a diameter of the wafer W. The whole reflector plate102is made of strongly heat-resistant opaque quartz which is white turbid since it is intermixed with fine bubbles. In this case, the surface of the reflector plate102is non-transparent to externally incident heat rays, and reflects such heat rays with high reflectivity. And, the top surface of the reflector plate102is attached on the bottom surface of the ceiling plate74. Further, a strongly heat-resistant and transparent quartz tube104, formed to be bent in a predetermined shape, is jointed by welding to the bottom surface of the reflector plate102. A carbon wire106which generates Joule heat when a current is applied thereto is inserted in the quartz tube104. Connecting terminals110at two ends of carbon wire106upwardly pass through the reflector plate102, and also pass through the ceiling plate74airtightly to be extended to the outside. When jointing the quartz tube104to the surface of the reflector plate102, joint pins108(seeFIGS. 6 and 7), also made of quartz, are used. Specifically, these joint pins108are disposed at proper places between the quartz tube104and the reflector plate102, and by melting them, the quartz tube104and the reflector plate102are welded together.

Accordingly, heat rays from the carbon wire106inside the quartz tube104are reflected at the surface of the reflector plate102having high heat-resistance, and directed altogether downward inFIG. 5. Accordingly, the inner vessel98made of a light absorbing material can be heated to a predetermined temperature level. Further, a cooling jacket112is installed in the ceiling plate74to cool the ceiling plate74. By flowing a coolant such as cooling water or the like in the cooling jacket112, the ceiling plate74can be cooled.

The operation of the heat treatment apparatus having the above configuration will now be described. Herein, as an example of a heat treatment, the case of laminating extremely thin alumina films, each being one to several molecules in thickness, on a layer-by-layer basis, will be described.

The wafer W mounted on the mounting table78is heated and maintained at a predetermined temperature level, primarily by the resistance heater80embedded in the mounting table78.

Further, the inner vessel98prepared in the processing chamber4′ is heated uniformly by the heating unit100prepared on an upper side of the inner vessel98. That is, the heat rays from the carbon wire106inserted in the quartz tube104of the heating unit100are absorbed in the inner vessel98made of a light absorbing material, directly, or indirectly by being reflected by the reflector plate102supporting quartz tube104, and thus heat the inner vessel98to a predetermined temperature level.

Meanwhile, the inner processing chamber98is supplied with film forming gases, as processing gases, in an intermittent manner, so that thin films are laminated into a multilayer stack. For example, a flow-controlled TMA (Tri-Methyl Aluminum) gas is supplied intermittently from the first gas supply unit90, and a flow-controlled ozone gas is supplied intermittently from the second gas supply unit92, flowing alternately with the supply of TMA gas. Accordingly, thin alumina films are laminated into a multilayer stack on the surface of the wafer W.

Specifically, when the TMA gas is supplied from the first gas supply unit90, the second vacuum pumping system96on the opposite side of the nozzle90A is driven, hence a gas flow in the direction of the arrow A1is formed in the processing space S. On the contrary, when the ozone gas is supplied from the second gas supply unit92, the first vacuum pumping system94on the opposite side of the nozzle92A is driven, so that a gas flow in the direction of the arrow A2, opposite from A1, is formed in the processing space S. By repeating these manipulations, the film forming process is performed.

The reflector plate102which constitutes the heating unit100is made of high-purity opaque quartz which contains hardly any impurities. The quartz tube104and the carbon wire106also have a high purity containing hardly any impurities. Thus, contamination such as organic contamination and/or metal contamination can be substantially suppressed. Moreover, the relatively easy fabrication processes for the reflector plate102and the quartz tube104substantially reduce the manufacturing cost. Further, thermal energy can be used effectively and efficiently by using the reflector plate102.

Moreover, a large amount of electric power can be supplied since the main components of the heating unit100are made of quartz which is strongly resistant to thermal shocks. Accordingly, a high temperature rising rate, for example, about 1000° C./5 minutes can be obtained.

Further, instead of the mounting table78of the second preferred embodiment, the mounting table32described with reference toFIGS. 1 to 4, that is, the mounting table which includes the integrally built-in heating unit can be used. In this case, contamination to the wafer W can be suppressed still further.

Furthermore, heating lamps can be used instead of the resistance heater80as a target object heating unit.

Still further, the inner vessel98may be made of transparent or opaque quartz. Further, a target object can be heated directly without installing the inner vessel98.

Though the second preferred embodiment has described the case of forming alumina film, the present invention is not limited thereto. The present invention can be applied to any film forming processes.

Furthermore, though the heating unit40(100) is formed by inserting the carbon wire64(106) in the transparent quartz tube62(104) in the above-described preferred embodiments, the present invention is not limited thereto. For example, as shown inFIG. 8, the lower half portion (upper half portion) of the quartz tube62(104) may be made of opaque quartz for reflection, and the upper half portion (lower half portion) may be made of transparent quartz to raise the thermal efficiency. In this case, a wafer has to be positioned on the side of transparent quartz.

Moreover, though the above preferred embodiments have described the cases of performing the film forming process as the heat treatment process, the present invention is not limited thereto. The present invention can be applied to different heat treatment processes such as oxidation/diffusion process, annealing process, and quality modification process.

Further, though the above preferred embodiments have described the film forming apparatuses by thermal CVD, the present invention is not limited thereto. The present invention can be applied to such apparatus as plasma CVD processing apparatus, etching processing apparatus, oxidation/diffusion processing apparatus, and sputter processing apparatus.

Still further, though the above preferred embodiments have described the cases of using a semiconductor wafer as a target object as an example, the present invention is not limited thereto. The present invention can be applied to LCD substrate, glass substrate and the like.