MICROWAVE HEATING APPARATUS AND PROCESSING METHOD

A microwave heating apparatus includes a processing chamber for accommodating a target, a support device for supporting the target in the processing chamber and a microwave introducing device for generating microwaves to introduce them into the processing chamber. The processing chamber further includes a top wall having a plurality of microwave introduction ports to introduce the microwaves generated in the microwave introducing device into the processing chamber. Each of the microwave introduction ports has a rectangular shape having long sides and short sides parallel to inner wall surfaces of four sidewalls of the processing chamber, and the support device includes a support member to support the target and a rotating mechanism for rotating the supported target.

FIELD OF THE INVENTION

The present invention relates to a microwave heating apparatus for performing a process by introducing microwaves into a processing chamber and a processing method for heating a target object to be processed by using the microwave heating apparatus.

BACKGROUND OF THE INVENTION

Along with miniaturization of LSI devices or memory devices, the depth of a diffusion layer in a transistor manufacturing process becomes shallower. Conventionally, activation of the doping atoms implanted into a diffusion layer is performed by a high-speed heating process referred to as a rapid thermal annealing (RTA) using a lamp heater. However, in the RTA process, as the diffusion of the doping atoms proceeds, the depth of the diffusion layer exceeds an allowable range, which causes difficulty in achieving a miniaturized design. Incomplete control of the depth of the diffusion layer is a factor to deteriorate the electrical characteristics of devices such as generation of leakage current.

Recently, as an apparatus for performing heat treatment on a semiconductor wafer, an apparatus using microwaves has been proposed. When the activation of the doping atoms is performed by microwave heating, the microwaves directly act on the doping atoms. Thus, it is advantageous in that excessive heating does not occur, and expansion of the diffusion layer can be suppressed.

As a heating apparatus using microwaves, for example, a microwave heating apparatus for heating a target by introducing microwaves into a pyramid-shaped horn through a rectangular waveguide has been proposed in Patent Document 1 (Japanese Patent Application Publication No. S62-268086). In Patent Document 1, the rectangular waveguide is rotated and arranged by an angle of 45 degrees in its axial direction with respect to the pyramid-shaped horn, so that two orthogonally polarized microwaves in a TE10mode can be irradiated onto the target in the same phase.

Further, as a heating apparatus for bending a target object to be heated, a microwave heating apparatus including a heating chamber having a square cross section whose size is set to about λ/2 to λ of a free space wavelength of the introduced microwaves has been proposed in Patent Document 2 (Japanese Utility Model Application Publication No. H6-17190).

The microwave has a wavelength which is as long as several tens of millimeters, and has a feature of easily forming a standing wave in the processing chamber. Thus, for example, when a semiconductor wafer is heated by microwaves, the intensity of an electromagnetic field becomes non-uniform in the plane of the semiconductor wafer, and non-uniformity of the heating temperature is likely to occur. In order to promote uniform diffusion of the microwaves in the processing chamber, it is known that a microwave radiation space is provided with a stirrer for stirring the microwaves. However, a stirring effect of the stirrer is small and, in a semiconductor process, particles may be generated from a rotary drive unit of the stirrer.

SUMMARY OF THE INVENTION

The present invention provides a microwave heating apparatus and a processing method capable of performing uniform processing on a target object.

In accordance with an aspect of the present invention, there is provided a microwave heating apparatus including a processing chamber configured to accommodate a target object to be processed, the processing chamber including a microwave irradiation space, a support device configured to support the target object in the processing chamber, and a microwave introducing device configured to generate microwaves for heating the target object and introduce the microwaves into the processing chamber, wherein the processing chamber further includes a top wall, a bottom wall, and four sidewalls connected to each other, and wherein the top wall has a plurality of microwave introduction ports through which the microwaves generated in the microwave introducing device are introduced into the processing chamber. Each of the microwave introduction ports is formed in a rectangular shape having long sides and short sides in a plan view, and the long sides and the short sides are parallel to inner wall surfaces of the four sidewalls. Further, the support device includes a support member in contact with the target object to support the target object, and a rotating mechanism for rotating the target object supported by the support member.

In the microwave heating apparatus of the present invention, the support device may further include a vertical position adjusting mechanism for adjusting a vertical position of the target object supported by the support member.

In the microwave heating apparatus of the present invention, the microwave introduction ports may include a first to a fourth microwave introduction port. The first to the fourth microwave introduction port may be divided into two microwave introduction ports corresponding to an inner microwave radiation zone and two microwave introduction ports corresponding to an outer microwave radiation zone in an outward direction from a center of the top wall. In this case, the two microwave introduction ports corresponding to the inner microwave radiation zone may be arranged such that their centers are disposed on a circumference of an inner circle of two virtual concentric circles, and the two microwave introduction ports corresponding to the outer microwave radiation zone may be arranged such that their centers are disposed on a circumference of an outer circle of the two virtual concentric circles.

In the microwave heating apparatus of the present invention, the first to the fourth microwave introduction port may be arranged such that central axes parallel to the long sides of two microwave introduction ports which are adjacent to each other are perpendicular to each other, and the central axes of two microwave introduction ports which are not adjacent to each other do not overlap each other on a same straight line.

In the microwave heating apparatus of the present invention, the microwave introduction ports may be arranged such that distances from a center of the top wall are different from each other in the outward direction from a center of the top wall.

In the microwave heating apparatus of the present invention, a ratio L1/L2of a length L1of the long sides to a length L2of the short sides of each of the microwave introduction ports may be equal to or greater than 4.

In the microwave heating apparatus of the present invention, the microwave introducing device may include at least one waveguide for transmitting the microwaves toward the processing chamber, and an adapter member which is mounted on an outside of the top wall of the processing chamber and includes a plurality of metallic block bodies, and the adapter member further may include at least one waveguide path for transmitting microwaves therein, the waveguide path having a substantially S-shape. In this case, one end of the waveguide path may be connected to a corresponding waveguide and the other end of the waveguide path is connected to a corresponding microwave introduction port, and the waveguide may be connected to the corresponding microwave introduction port such that they do not overlap each other at least partially in a vertical direction.

In accordance with another aspect of the present invention, there is provided a processing method for heating a target object to be processed by using a microwave heating apparatus which includes a processing chamber configured to accommodate the target object, the processing chamber having a microwave irradiation space, a support device configured to support the target object in the processing chamber, and a microwave introducing device configured to generate microwaves for heating the target object and introduce the microwaves into the processing chamber.

In the processing method of the present invention, the processing chamber further has a top wall, a bottom wall, and four sidewalls connected to each other, the top wall has a plurality of microwave introduction ports through which the microwaves generated in the microwave introducing device are introduced into the processing chamber. Each of the microwave introduction ports is formed in a rectangular shape having long sides and short sides in a plan view, the long sides and the short sides being parallel to inner wall surfaces of the four sidewalls. Further, the support device has a support member in contact with the target object to support the target object, and a rotating mechanism for rotating the target object supported by the support member. Furthermore, the microwave introduction ports are divided into microwave introduction ports corresponding to an inner microwave radiation zone and microwave introduction ports corresponding to an outer microwave radiation zone in a direction outward from a center of the top wall. Then, the processing method of the present invention processes the target object by introducing microwaves from each of the microwave introduction ports while rotating the target object supported by the support member by the rotating mechanism.

In the processing method of the present invention, the support device may further have a vertical position adjusting mechanism to adjust a vertical position of the target object supported by the support member. Then, the processing method of the present invention may include a first step of setting the vertical position of the target object to a first vertical position by the vertical position adjusting mechanism and processing the target object, and a second step of setting the vertical position of the target object to a second vertical position different from the first vertical position by the vertical position adjusting mechanism and processing the target object.

In the microwave heating apparatus and the processing method of the present invention, it is possible to perform uniform heating processing on a target object.

DETAILED DESCRIPTION OF THE EMBODIMENTS

First Embodiment

First, a schematic configuration of a microwave heating apparatus according to a first embodiment of the present invention will be described with reference toFIG. 1.FIG. 1is a cross-sectional view showing a schematic configuration of a microwave heating apparatus according to the present embodiment. A microwave heating apparatus1according to the present embodiment is the apparatus which performs an annealing process on, e.g., a semiconductor wafer (hereinafter, simply referred to as “wafer”) W for manufacturing a semiconductor device by irradiating microwaves to the wafer W in accordance with multiple consecutive operations.

The microwave heating apparatus1includes a processing chamber2for accommodating the wafer W as a target object to be processed, a microwave introducing device3for introducing microwaves into the processing chamber2, a support device4for supporting the wafer W in the processing chamber2, a gas supply mechanism5for supplying a gas into the processing chamber2, an exhaust device6for vacuum-evacuating the processing chamber2, and a control unit8for controlling the respective components of the microwave heating apparatus1.

The processing chamber2is made of a metal material. As a material for forming the processing chamber2, for example, aluminum, aluminum alloy, stainless steel or the like may be used. The microwave introducing device3is provided at the top of the processing chamber2and functions as a microwave introducing unit for introducing electromagnetic waves (microwaves) into the processing chamber2. A configuration of the microwave introducing device3will be described in detail later.

The processing chamber2has a plate-shaped ceiling portion11serving as an upper wall, a bottom portion13serving as a bottom wall, and four sidewall portions12serving as sidewalls connecting the ceiling portion11and the bottom portion13. Further, the processing chamber2has microwave introduction ports10provided to vertically pass through the ceiling portion11, a loading and unloading port12aprovided in one of the sidewall portions12, and an exhaust port13aprovided in the bottom portion13. In this case, the four sidewall portions12are connected at a right angle to have a rectangular tube shape in a horizontal plan view. Thus, the processing chamber2forms a cube shape having a cavity therein. Further, the inner surface of each of the sidewall portions12is flattened, and functions as a reflecting surface for reflecting microwaves.

In the microwave heating apparatus1according to the present embodiment, all inner wall surfaces (i.e., the inner side of the ceiling portion11, the four sidewall portions12and the bottom portion13) of the processing chamber2are mirror-finished. By mirror-finishing the inner wall surfaces of the processing chamber2, it is possible to improve the reflection efficiency of radiant heat from the wafer W. Further, since it is possible to reduce the surface area of the inner wall surfaces of the processing chamber2by mirror finishing, it is possible to reduce the microwaves absorbed into the walls of the processing chamber2, thereby improving the reflection efficiency of the microwaves.

Therefore, it is possible to efficiently perform the annealing process on the wafer W, and to increase the attainment temperature of the wafer W as compared with a case where mirror finishing is not performed. Further, the processing chamber2may be manufactured by machining. In this case, since it is practically impossible to form corner portions such as a joint between the sidewall portions12and a joint between the bottom portion13and the sidewall portions12at a right angle, a rounding process may be performed on the corner portions. It can be seen from the results of a simulation that in the rounding process, a radius of curvature Rcis preferably in a range from 15 mm to 16 mm to suppress the reflection into the microwave introduction ports10(seeFIG. 18).

The loading and unloading port12ais used in loading and unloading the wafer W between the processing chamber2and a transfer chamber (not shown) adjacent to the processing chamber2. A gate valve GV is provided between the processing chamber2and the transfer chamber (not shown). The gate valve GV has a function of opening and closing the loading and unloading port12a,and allows the wafer W to be transferred between the transfer chamber (not shown) and the processing chamber2in an open state while air-tightly sealing the processing chamber2in a closed state.

FIG. 2is a cross-sectional view of main parts in the vicinity of the gate valve GV of the processing chamber2. The gate valve GV has a main body110, a plate-shaped block111inserted into a recess of the main body110, and a drive mechanism (not shown). The main body110and the block111constitute a valve body. The drive mechanism displaces the valve body vertically and horizontally. The main body110and the block111are formed of, e.g., metal such as aluminum or stainless steel. The block111is a replaceable consumable part because it is exposed to a space in the processing chamber2. A gap112is provided between the main body110and the block111to form a choke structure for preventing leakage of microwaves.

A frame113for contacting the gate valve GV is interposed between the gate valve GV and the sidewall portions12of the processing chamber2. The frame113is formed of, e.g., metal such as aluminum or stainless steel. The frame113is a replaceable consumable part because it is exposed to the space in the processing chamber2. The frame113is provided with an opening113ahaving a size corresponding approximately to the loading and unloading port12a.Between the frame113and the sidewall portions12of the processing chamber2, an electromagnetic shield member114and an O-ring115are disposed so as to surround the opening113a.As shown inFIG. 2, the electromagnetic shield member114is disposed inwardly, and the O-ring115is disposed outwardly.

The main body110and the block111serving as a valve body are provided to be displaceable in vertical and horizontal directions by a drive unit (not shown). Thus, opening and closing of the gate valve GV are performed. Further, for example, in the case of performing the opening and closing by displacing the valve body in an oblique direction, the inner surface of the block111which is exposed to the inside of the processing chamber2becomes an inclined surface, which may affect the reflection of microwaves. In this case, for example, a reflecting plate may be mounted on the inner wall surface of the block111to correct the inclined surface and to form a vertical surface.

The support device4has a hollow tubular shaft14extending to the outside of the processing chamber2through the approximate center of the bottom portion13of the processing chamber2, a plurality of (e.g., three) arm portions15provided in a substantially horizontal direction from the vicinity of the upper end of the shaft14, and a plurality of support pins16detachably mounted on the arm portions15, respectively. Further, the support device4has a rotation drive unit17for rotating the shaft14, an elevation drive unit18for vertically displacing the shaft14, and a movable coupling unit19for connecting the rotation drive unit17to the elevation drive unit18while supporting the shaft14. The rotation drive unit17, the elevation drive unit18and the movable coupling unit19are provided outside the processing chamber2. Further, in the case of setting the inside of the processing chamber2to a vacuum state, a sealing mechanism20such as a bellows may be provided around a portion where the shaft14passes through the bottom portion13.

In the support device4, the shaft14, the arm portions15, the rotation drive unit17and the movable coupling unit19constitute a rotating mechanism for rotating the wafer W held on the support pins16in the horizontal direction. Further, in the support device4, the shaft14, the arm portions15, the elevation drive unit18and the movable coupling unit19constitute a vertical position adjusting mechanism for adjusting the vertical position of the wafer W held on the support pins16. The support pins16support the wafer W in contact with a back surface of the wafer W in the processing chamber2.

The support pins16are disposed such that upper end portions thereof are arranged in the circumferential direction of the wafer W. By the rotation drive unit17, the arm portions15rotate around the shaft14to revolve the support pins16in the horizontal direction. Further, by the elevation drive unit18, the support pins16and the arm portions15are displaced up and down in the vertical direction with the shaft14. In order to keep the horizontal level of the wafer W to be supported by the arm portions15and the support pins16, the support device4has a mechanism (not shown) for adjusting the inclination of the shaft14.

Further, in order to prevent leakage of microwaves through the support device4, prevent abnormal discharge, and prevent generation of particles from moving parts, the following measures have been taken in the support device4. First, in order to prevent the leakage of microwaves through the support device4, in the tubular shaft14, a double choke structure is provided although not illustrated. Further, a ground terminal such as a shield finger (not shown) is attached to the shaft14and is maintained at a ground potential. Furthermore, since particles are likely to be generated from the moving parts in the hollow shaft14, there is provided an exhaust and purge mechanism (not shown) for evacuating or purging the inside of the hollow shaft14.

The support pins16and the arm portions15are made of a dielectric material. As a material forming the support pins16and the arm portions15, e.g., quartz or ceramic may be used.

FIGS. 3 and 4show an exemplary configuration of the support pins16mounted on the arm portions15. First,FIG. 3illustrates the state where two support pins16A and16B are mounted on one arm portion15. The support pin16A is in contact with the back surface in the vicinity of an outer peripheral portion of the wafer W to support the wafer W, and the support pin16B is in contact with the back surface of the wafer W at a position closer to the radial inner side of the wafer W than the support pin16A. The support pin16A is detachably mounted by being inserted into mounting holes15aprovided in the arm portion15. The support pin16B is detachably mounted by being inserted into mounting holes15bprovided in the arm portion15.

Thus, by providing two mounting holes15aand two mounting holes15b,the support pin16A and the support pin16B can be reliably fixed to the arm portion15. Therefore, it is possible to prevent the support pin16A and the support pin16B from falling off by, e.g., electrostatic adsorption to the wafer W. Further, since the support pin16A and the support pin16B are fixed by being inserted into the mounting holes15aand the mounting holes15b,it is possible to reduce the generation of particles as compared to a screwing method or the like.

FIG. 4shows the state in which the support pin16A is replaced with a support pin16C and the support pin16B is removed from the state ofFIG. 3. The support pin16C has an inclined surface16C1in contact with a bevel portion of the wafer W to support the wafer W.

As shown inFIGS. 3 and 4, in the microwave heating apparatus1of the present embodiment, by using the detachable support pins16, the contact state of the support pins16with the wafer W, and the mounting position, the shape, the number of the support pins16mounted on the arm portion15and the like may be selected appropriately.

The rotation drive unit17is not particularly limited as long as it can rotate the shaft14, and for example, may include a motor (not shown) or the like. The elevation drive unit18is not particularly limited as long as it can vertically displace the shaft14and the movable coupling unit19, and for example, may include a ball screw (not shown) or the like. The rotation drive unit17and the elevation drive unit18may be formed as a single mechanism, and may be configured without the movable coupling unit19. Further, the rotating mechanism for rotating the wafer W in the horizontal direction and the vertical position adjusting mechanism for adjusting the vertical position of the wafer W may have other configurations as long as they can achieve these purposes.

The exhaust device6has a vacuum pump such as a dry pump. The microwave heating apparatus1further includes an exhaust pipe21for connecting the exhaust port13ato the exhaust device6and a pressure regulating valve22provided in the exhaust pipe21. By operating the vacuum pump of the exhaust device6, an inner space of the processing chamber2is vacuum-evacuated. Further, the microwave heating apparatus1may also perform processing at an atmospheric pressure, in which case the vacuum pump is not required. Instead of using a vacuum pump such as a dry pump as the exhaust device6, exhaust equipment provided in facilities in which the microwave heating apparatus1is installed may be used.

The microwave heating apparatus1further includes the gas supply mechanism5for supplying a gas into the processing chamber2. The gas supply mechanism5includes a gas supply device5ahaving a gas supply source (not shown), and a plurality of pipes23connected to the gas supply device5ato introduce a processing gas into the processing chamber2. The plurality of pipes23are connected to the sidewall portions12of the processing chamber2.

The gas supply device5ais configured to supply a gas such as N2, Ar, He, Ne, O2and H2as a processing gas or a cooling gas into the processing chamber2through the pipes23in a side flow manner. The supply of gas into the processing chamber2may be carried out, for example, by a gas supply unit provided at a position (e.g., the ceiling portion11) opposite to the wafer W. Further, instead of the gas supply device5a,an external gas supply device which is not included in the configuration of the microwave heating apparatus1may be used. Although not shown, the microwave heating apparatus1further includes a mass flow controller and an opening and closing valve which are provided in the pipes23. The type of gas supplied into the processing chamber2, the flow rate of the gas and the like are controlled by the mass flow controller and the opening and closing valve.

The microwave heating apparatus1further includes a rectifying plate24having a frame shape around the support pins16in the processing chamber2between the sidewall portions12and the support pins16. The rectifying plate24has a plurality of rectifying holes24awhich are provided so as to vertically pass through the rectifying plate24. The rectifying plate24rectifies an atmosphere of a region in which the wafer W is to be disposed in the processing chamber2, and makes it flow toward the exhaust port13a.The rectifying plate24is formed of a metal material such as aluminum, aluminum alloy, or stainless steel. Further, the rectifying plate24is not an essential component in the microwave heating apparatus1, and may be omitted.

The microwave heating apparatus1further includes a plurality of radiation thermometers26for measuring a surface temperature of the wafer W, and a temperature measurement unit27connected to the radiation thermometers26. InFIG. 1, only the radiation thermometer26for measuring the temperature of the central portion of the back surface of the wafer W through the hollow shaft14is illustrated and the others are omitted.

In the microwave heating apparatus1of the present embodiment, in the processing chamber2, a space defined by the ceiling portion11, the four sidewall portions12and the rectifying plate24forms a microwave radiation space S. Microwaves are radiated into the microwave radiation space S from the microwave introduction ports10provided in the ceiling portion11. Since the ceiling portion11, the four sidewall portions12and the rectifying plate24of the processing chamber2are formed of a metal material, the microwaves are reflected and scattered into the microwave radiation space S.

Next, a configuration of the microwave introducing device3will be described with reference toFIGS. 1 and 5.FIG. 5is a diagram showing a schematic configuration of a high voltage power supply unit of the microwave introducing device3.

As described above, the microwave introducing device3is provided at the top of the processing chamber2, and functions as a microwave introducing unit for introducing electromagnetic waves (microwaves) to the processing chamber2. As shown inFIG. 1, the microwave introducing device3includes a plurality of microwave units30for introducing microwaves into the processing chamber2, and a high voltage power supply unit40connected to the microwave units30.

In this embodiment, the microwave units30have the same configuration. Each of the microwave units30has a magnetron31to generate microwaves for processing the wafer W, a waveguide32to transmit the microwaves generated in the magnetron31to the processing chamber2, and a transmission window33fixed to the ceiling portion11to cover the microwave introduction port10. The magnetron31corresponds to a microwave source in the present invention.

The magnetron31has an anode and a cathode (all not shown) to which a high voltage supplied by the high voltage power supply unit40is applied. Further, as the magnetron31, a component capable of oscillating microwaves of various frequencies may be used. The microwave generated by the magnetron31is selected to have an optimal frequency for each process of a target object. For example, for the annealing process, a microwave with a high frequency of 2.45 GHz, 5.8 GHz or the like is preferable, and a microwave of 5.8 GHz is particularly preferable.

The waveguide32has a square tubular shape having a rectangular cross section, and extends upward from the top surface of the ceiling portion11of the processing chamber2. The magnetron31is connected to the vicinity of the upper end of the waveguide32. The lower end of the waveguide32is in contact with the upper surface of the transmission window33. The microwave generated by the magnetron31is introduced into the processing chamber2through the waveguide32and the transmission window33.

The transmission window33is formed of a dielectric material. As the material of the transmission window33, for example, quartz, ceramics or the like may be used. The gap between the transmission window33and the ceiling portion11is air-tightly sealed by a sealing member (not shown). A distance (gap G) from the lower surface of the transmission window33to the front surface of the wafer W supported by the support pins16is preferably equal to or greater than, e.g., 25 mm, and is more preferably adjusted to vary within a range from 25 mm to 50 mm in terms of suppressing the microwaves from being radiated directly to the wafer W.

The microwave unit30further includes a circulator34, a detector35and a tuner36provided in the waveguide32, and a dummy load37connected to the circulator34. The circulator34, the detector35and the tuner36are arranged in this order from the upper end side of the waveguide32. The circulator34and the dummy load37constitute an isolator to separate reflected waves from the processing chamber2. That is, the circulator34guides the reflected waves from the processing chamber2to the dummy load37, and the dummy load37converts the reflected waves guided by the circulator34into heat.

In the present embodiment, for example, four microwave units30are provided. Although not shown, the magnetrons31of the four microwave units30are unevenly distributed above the ceiling portion11so as to be close to each other. As a result, the shapes of the waveguides32between the circulators34and the magnetrons31in the microwave units30are different from each other. Therefore, by arranging the magnetrons31to be concentrated in close proximity, it is possible to facilitate maintenance of the magnetrons31.

The detector35detects the reflected waves from the processing chamber2in the waveguide32. The detector35is configured as, e.g., an impedance monitor, in particular, a standing wave monitor for detecting an electric field of standing waves in the waveguide32. The standing wave monitor may include, e.g., three pins protruding into an inner space of the waveguide32. By detecting the location, phase and strength of the electric field of standing waves by the standing wave monitor, it is possible to detect the reflected waves from the processing chamber2. Also, the detector35may be configured as a directional coupler capable of detecting traveling waves and reflected waves.

The tuner36has a function of matching the impedance between the magnetron31and the processing chamber2. Impedance matching by the tuner36is performed based on the detection result of the reflected waves in the detector35. The tuner36may be configured as a conductive plate (not shown) capable of moving into and out of the inner space of the waveguide32. In this case, by controlling the protrusion amount of the conductive plate into the inner space of the waveguide32, it is possible to adjust the amount of power of the reflected waves, and to adjust the impedance between the magnetron31and the processing chamber2.

(High Voltage Power Supply Unit)

The high voltage power supply unit40supplies a high voltage to the magnetron31to generate the microwaves. As shown inFIG. 5, the high voltage power supply unit40includes an AC-DC conversion circuit41connected to a commercial power supply, a switching circuit42connected to the AC-DC conversion circuit41, a switching controller43for controlling operation of the switching circuit42, a step-up transformer44connected to the switching circuit42, and a rectifier circuit45connected to the step-up transformer44. The magnetron31is connected to the step-up transformer44via the rectifier circuit45.

The AC-DC conversion circuit41is a circuit for rectifying an alternating current (e.g., three-phase AC 200V) from the commercial power supply and converting the alternating current into a direct current of a predetermined waveform. The switching circuit42is a circuit for controlling on/off of the direct current converted by the AC-DC conversion circuit41. In the switching circuit42, phase shift type Pulse Width Modulation (PWM) control or Pulse Amplitude Modulation (PAM) control is conducted by the switching controller43, and a pulsed voltage waveform is generated. The step-up transformer44steps up the voltage waveform outputted from the switching circuit42to a predetermined magnitude. The rectifier circuit45is a circuit for rectifying the voltage stepped up by the step-up transformer44and supplying the voltage to the magnetron31.

<Arrangement of Microwave Introduction Ports>

Next, the arrangement of the microwave introduction ports10in the present embodiment will be described in detail with reference toFIGS. 1,6and7.FIG. 6shows a state of the lower surface of the ceiling portion11of the processing chamber2shown inFIG. 1, which is viewed from the inside of the processing chamber2. InFIG. 6, the position and size of the wafer W are shown by a dashed double-dotted line to overlap with the ceiling portion11. Reference symbol O represents the center of the wafer W, and in the present embodiment, also represents the center of the ceiling portion11. Two lines passing through reference symbol O represent center lines M connecting the midpoints of opposite sides in four sides serving as a boundary between the ceiling portion11and the sidewall portions12.

Further, the center of the wafer W and the center of the ceiling portion11may not overlap each other necessarily. InFIG. 6, for simplicity of description, joint portions between the inner wall surfaces of the four sidewall portions12of the processing chamber2and the ceiling portion11are denoted by reference numeral12A,12B,12C, and12D to distinguish the four sidewall portions12from each other and indicate their locations. Further, FIG. is an enlarged plan view showing one of the microwave introduction ports10.

As shown inFIG. 6, in this embodiment, as a plurality of microwave introduction ports, there are provided the four microwave introduction ports10arranged to form a substantially cross shape as a whole in the ceiling portion11. Hereinafter, when the four microwave introduction ports10are expressed to be distinguished from each other, they are denoted by reference numeral10A,10B,10C, and10D. Further, in the present embodiment, the microwave units30are connected to the microwave introduction ports10, respectively. That is, the number of the microwave units30is four. In this embodiment, a case where the four microwave introduction ports10A,10B,10C and10D are provided as a plurality of microwave introduction ports is described as an example, but the number of the microwave introduction ports10is arbitrary, and for example, may be in a range from2to8.

As shown inFIG. 7, each of the four microwave introduction ports10has a rectangular shape having long and short sides in its plan view. A ratio L1/L2of a length L1of the long sides to a length L2of the short sides of the microwave introduction port10is, for example, in a range from 2 to 100, preferably, equal to or greater than 4, and more preferably, in a range from 5 to 20. The ratio L1/L2is set to be 2 or more, preferably, 4 or more in order to strengthen the directivity of microwaves radiated into the processing chamber2from the microwave introduction port10in a direction perpendicular to the long side (direction parallel to the short side) of the microwave introduction port10.

If the ratio L1/L2is less than 2, the microwaves radiated into the processing chamber2from the microwave introduction port10are likely to be oriented in a direction parallel to the long side (direction perpendicular to the short side) of the microwave introduction port10. Further, if the ratio L1/L2is less than 2, the directivity of the microwaves becomes strong immediately below the microwave introduction port10. Thus, when the gap G is small, microwaves are irradiated directly to the wafer W, and local heating is likely to occur. On the other hand, if the ratio L1/L2exceeds 20, since the directivity of the microwaves becomes excessively weak in a direction parallel to the long side (direction perpendicular to the short side) of the microwave introduction port10or immediately below the microwave introduction port10, the heating efficiency of the wafer W may be reduced.

Further, the length L1of the long sides of the microwave introduction port10is preferable to meet L1=n×λg/2 (n is an integer) for, e.g., a guide wavelength Ag of the waveguide32, and n=2 is more preferable. The ratio L1/L2or the size of each of the microwave introduction ports10may be different, but from the viewpoint of improving the controllability while enhancing the uniformity of heating processing on the wafer W, it is preferable that all of the four microwave introduction ports10have the same size and shape.

Further, in the present embodiment, from the viewpoint of making uniform the electric field distribution on the wafer W, in the ceiling portion11, the four microwave introduction ports10are disposed at different positions in an outward direction from the center O of the ceiling portion11(wafer W) such that each of the centers Opoverlaps with one of two concentric circles. That is, the four microwave introduction ports10do not have the same position in the radial direction of the wafer W, and are disposed at different positions in the radial direction to form a plurality of radiation zones on the wafer W.

For example, as shown inFIG. 6, the four microwave introduction ports10include two sets disposed at different positions for forming an inner microwave radiation zone and an outer microwave radiation zone. Specifically, the microwave introduction ports10A and10C, which are not adjacent to each other in the circumferential direction of the wafer W, are disposed such that the centers Opthereof lie on a virtual circle having a radius RINwith respect to the center O of the wafer W, thereby forming the inner microwave radiation zone. Also, the microwave introduction ports10B and10D, which are not adjacent to each other in the circumferential direction of the wafer W, are disposed such that the centers Opthereof lie on a virtual circle having a radius ROUTwith respect to the center O of the wafer W, thereby forming the outer microwave radiation zone. In this case, the centers of two virtual concentric circles coincide with the center O (center of the wafer W) of the ceiling portion11, and the radius RINis smaller than the radius ROUT(RIN<ROUT).

In the example shown inFIG. 6, the microwave introduction ports10A and10C are disposed at a reference position of the microwave introduction ports10. When all of the four microwave introduction ports10are disposed at the reference position, all of the centers Opof the four microwave introduction ports10are located on the virtual circle having the radius RIN. In this case, in a plane parallel to the lower surface of the ceiling portion11, a direction perpendicular to the long side of each of the microwave introduction ports10is set as an X-axis, and a direction parallel to the long side of each of the microwave introduction ports10is set as a Y-axis. In the example shown inFIG. 6, each of the microwave introduction ports10B and10D is disposed to be translated by a distance ROUT-RINin the Y-axis direction from the reference position (shown by an imaginary line inFIG. 6).

In the example shown inFIG. 6, the microwave introduction ports10are arranged to radiate microwaves into two divided regions of the inner microwave radiation zone and the outer microwave radiation zone. In this case, when the radius of the wafer W is R, under the condition of RIN<ROUT, for example, the radius RINindicating the reference position is preferable to satisfy R/5≦RIN≦3R/5, and the radius ROUTis preferable to satisfy 2R/5≦ROUT≦5R/5. For example, in the case of the wafer W having a diameter of 300 mm, under the condition of RIN<ROUT, the radius RINis preferably set in a range from 30 mm to 90 mm, and the radius ROUTis preferably set in a range from 60 mm to 150 mm.

Thus, the microwave introduction ports10are arranged to radiate microwaves into two divided regions of the inner microwave radiation zone and the outer microwave radiation zone. With this configuration, in the present embodiment, when the wafer W on the support pins16is rotated horizontally by driving the rotation drive unit17, it is possible to enhance the heating uniformity in the radial direction of the wafer W in addition to the heating uniformity in the circumferential direction of the wafer W.

Further, in the present embodiment, the long sides and the short sides of each of the four microwave introduction ports10are provided to be parallel to the inner wall surfaces of the four sidewall portions12A,12B,12C and12D. For example, inFIG. 6, the long sides of the microwave introduction port10A are parallel to the sidewall portions12B and12D, and the short sides of the microwave introduction port10A are parallel to the sidewall portions12A and12C. Most of the microwaves radiated from the microwave introduction port10A travel and propagate in the X-axis direction perpendicular to the long side (direction parallel to the short side) thereof. Further, the microwaves radiated from the microwave introduction port10A are reflected by each of the two sidewall portions12B and12D.

Since the sidewall portions12B and12D are provided to be parallel to the long side of the microwave introduction port10A, the directivity (electromagnetic field vector) of reflected waves is opposite by 180 degrees to the directivity (electromagnetic field vector) of traveling waves, and scattering in the direction toward the other microwave introduction ports10B,10C and10D hardly occurs. Thus, by arranging the four microwave introduction ports10having the ratio L1/L2of, e.g., 2 or more such that the long sides and the short sides of each of the four microwave introduction ports10are parallel to the inner wall surfaces of the four sidewall portions12A,12B,12C and12D, it is possible to control the directions of the microwaves radiated from the microwave introduction ports10and the reflected waves thereof.

Further, in this embodiment, the four microwave introduction ports10having the ratio L1/L2of, e.g., 2 or more are arranged such that when each of the microwave introduction ports10is translated in the X-axis direction perpendicular to the long side thereof, it does not overlap the other microwave introduction ports10having a long side parallel thereto. For example, inFIG. 6, the microwave introduction ports10A˜10D are arranged to form a cross shape as a whole. That is, two microwave introduction ports10adjacent to each other are arranged to be shifted by 90 degrees such that central axes AC parallel to the long sides thereof are perpendicular to each other.

Further, even when the microwave introduction port10A is translated in the X-axis direction perpendicular to the long side thereof, it does not overlap the other microwave introduction port10C having a long side parallel to that of the microwave introduction port10A. In other words, within a range of the length of the long side of the microwave introduction port10A, between the two sidewall portions12B and12D parallel to the long side of the microwave introduction port10A, another microwave introduction port10(microwave introduction port10C) having a long side in the same direction as the long side of the microwave introduction port10A is not disposed.

With such an arrangement, it is possible to prevent, as much as possible, the microwaves radiated from the microwave introduction port10A with a strong directivity in the X-axis direction perpendicular to the long side thereof and the reflected waves thereof from entering another microwave introduction port10. If there is another microwave introduction port10having the long side of the same direction as the microwave introduction port10A within a range of the length of the long side of the microwave introduction port10A between the two sidewall portions12B and12D parallel to the microwave introduction port10A, excitation directions of microwaves are the same, and microwaves and reflected waves thereof are likely to enter the microwave introduction port10of the same direction, thereby increasing power loss.

On the other hand, if the another microwave introduction port10of the same direction as the microwave introduction port10A is not present between the two parallel sidewall portions12B and12D within the range of the length of the long side of the microwave introduction port10A, the microwaves radiated from the microwave introduction port10A and the reflected waves thereof are suppressed from entering the other microwave introduction port10. Therefore, it is possible to suppress the loss of power caused when the microwaves radiated from the microwave introduction port10A and the reflected waves thereof enter the another microwave introduction port10.

InFIG. 6, since the microwaves radiated from the microwave introduction port10A and the reflected waves thereof have an excitation direction different from that of the microwave introduction ports10B and10D arranged adjacent to the microwave introduction port10A to be shifted by 90 degrees, they hardly enter the microwave introduction ports10B and10D. Therefore, when the microwave introduction port10A is translated in the X-axis direction perpendicular to the long side thereof, the microwave introduction port10A may overlap the microwave introduction ports10B and10D having long sides in a direction different from the direction of the long side thereof.

Further, in this embodiment, among the four microwave introduction ports10disposed to form a cross shape as a whole, two microwave introduction ports10which are not adjacent to each other are arranged such that the central axes AC do not overlap each other on the same straight line. For example, inFIG. 6, the central axis AC of the microwave introduction port10A and the central axis AC of the microwave introduction port10C which is not adjacent to the microwave introduction port10A are disposed in the same direction without overlapping each other. Thus, by arranging two microwave introduction ports10which are not adjacent to each other among the four microwave introduction ports10such that the central axes AC thereof in the same direction do not overlap each other, it is possible to prevent the microwaves radiated in a direction perpendicular to the short side (Y-axis direction parallel to the long side) of one of two microwave introduction ports10having the central axes AC in the same direction, from entering the other, thereby suppressing the loss of power.

In such an arrangement, the central axis AC of each of the microwave introduction ports10may not overlap with the center line M. Therefore, each of the microwave introduction ports10may be disposed at a position far from the center line M, e.g., at a position at which the long side of each of the microwave introduction ports10is close to the sidewall portion12. From the viewpoint of uniformly introducing microwaves into the processing chamber2, it is preferable that each of the microwave introduction ports10is disposed to be close to the center line M, and it is more preferable that, as shown inFIG. 6, at least a part of each of the microwave introduction ports10is disposed so as to overlap the center line M. Further, among the four microwave introduction ports10disposed to form a cross shape as a whole, the two microwave introduction ports10which are not adjacent to each other may disposed such that the central axes AC overlap each other, and in this case, the central axes AC may coincide with the center line M.

The microwave introduction ports10A,10B,10C and10D are disposed to establish the above relationship between them and between each of the microwave introduction ports10and the sidewall portions12.

Modifications of the arrangement of the microwave introduction ports10will now be described with reference toFIGS. 8 to 10.FIG. 6shows an exemplary arrangement in which each of the microwave introduction ports10B and10D is translated in the Y-axis direction from the reference position. However, for example, as shown inFIG. 8, each of the microwave introduction ports10B and10D may be translated in the X-axis direction from the reference position (shown by a dashed double-dotted line inFIG. 8) such that the centers Op thereof overlap with a circumference of a virtual circle having a radius ROUT. Even in this case, similarly to the case ofFIG. 6, when the wafer W is rotated horizontally, it is possible to enhance the uniformity of heating in the radial direction of the wafer W in addition to the uniformity of heating in the circumferential direction of the wafer W. Further, although illustration is omitted, each of the microwave introduction ports10B and10D may be moved in both the X-axis and Y-axis directions from the reference position such that the centers Opthereof overlap with the circumference of the virtual circle having the radius ROUT.

Further,FIGS. 6 and 8illustrate an arrangement example in which each of the microwave introduction ports10B and10D which are not adjacent to each other in the circumferential direction of the wafer W is translated from the reference position. However, the two microwave introduction ports10which are adjacent to each other in the circumferential direction of the wafer W may be moved as a group. For example,FIG. 9is an example in which each of the microwave introduction ports10C and10D which are adjacent to each other in the circumferential direction of the wafer W is translated by a distance ROUT-RINin the Y-axis direction from the reference position (shown by a dashed double-dotted line inFIG. 9) such that the centers Opthereof overlap with the circumference of the virtual circle having the radius ROUT. In this case, similarly to the case ofFIG. 6, when the wafer W is rotated horizontally, it is possible to enhance the uniformity of heating in the radial direction of the wafer W in addition to the uniformity of heating in the circumferential direction of the wafer W. Further, also in the present modification, the moving direction of the microwave introduction ports10is not limited to the Y-axis direction, and may be the X-axis direction, or both the X-axis and Y-axis directions.

Further, inFIGS. 6 to 9, the four microwave introduction ports10are divided into two groups to radiate microwaves into two regions of the inner microwave radiation zone and the outer microwave radiation zone, but the microwave radiation zones are not limited to two inner and outer zones. For example, the four microwave introduction ports10may be disposed on four virtual concentric circles with different radii, respectively, such that four microwave radiation zones can be formed. Specifically, for example, as shown inFIG. 10, the four microwave introduction ports10A to10D may be arranged on concentric circles which are different in radial distance from the center O of the wafer W (center of the ceiling portion11).

In the modification shown inFIG. 10, the microwave introduction port10A is disposed such that the center Opthereof lies on a virtual circle having a radius R1. The microwave introduction port10B is disposed such that the center Opthereof lies on a virtual circle having a radius R2. The microwave introduction port10C is disposed such that the center Opthereof lies on a virtual circle having a radius R3. Further, the microwave introduction port10D is disposed such that the center Opthereof lies on a virtual circle having a radius R4. Also in this case, similarly to the case ofFIG. 6, when the wafer W is rotated horizontally, it is possible to enhance the uniformity of heating in the radial direction of the wafer W in addition to the uniformity of heating in the circumferential direction of the wafer W.

Further, also in the present modification, the moving directions of the microwave introduction ports10are not limited to the Y-axis direction, and may be the X-axis direction, or both the X-axis and the Y-axis direction. Furthermore, inFIG. 10, the four microwave introduction ports10are arranged such that the positions of the centers Opthereof becomes larger in a radially outward direction clockwise in the order of the microwave introduction ports10A,10B,10C and10D, but may be arranged randomly, not in this order.

Further, in the example ofFIGS. 6 to 10, all of the four microwave introduction ports10are disposed immediately above the wafer W to overlap the wafer W. However, as long as uniform heating in the plane of the wafer W is realized, the position of the wafer W and the position of the microwave introduction ports10may not necessarily overlap each other.

Next, a chamber opening and closing mechanism in the microwave heating apparatus1will be described with reference toFIGS. 11 to 13.FIGS. 11 to 13illustrate a procedure of opening and closing operations of the chamber opening and closing mechanism. Further, inFIGS. 11 to 13, a portion including the ceiling portion11of the processing chamber2and the microwave introducing device3of the microwave heating apparatus1is simplified and illustrated in a box shape as an upper unit101. The chamber opening and closing mechanism of the present embodiment opens the interior of the processing chamber2by sliding the upper unit101on a rail.

FIG. 11shows three microwave heating apparatuses1and a rail mechanism102for pulling out the upper unit101in each of the microwave heating apparatuses1. The rail mechanism102has a rail portion102ain a lattice shape. The rail portion102ais provided to be foldable such that it is upright when not used, and is developed into a horizontal position to be bridged to the microwave heating apparatus1when used.

From the state ofFIG. 11, the ceiling portion11, which forms a part of the upper unit101and functions as a lid, is pushed up by a lifting force of a lifting unit such as a spring (not shown), and the upper unit101is lifted up from the sidewall portions12of the processing chamber2.FIG. 12shows the state where one of the upper units101is pulled out by sliding the upper unit101on the rail portion102a.FIG. 13shows the state where a sliding direction of the upper unit101is changed at a right angle and the upper unit101is moved to the front side of the neighboring microwave heating apparatus1. By providing the rail mechanism102, it is possible to easily open the processing chamber2of the microwave heating apparatus1, thereby facilitating maintenance of the inside of the processing chamber2or the microwave introducing device3. Further, between a plurality of microwave heating apparatuses1sharing the rail mechanism102, the upper unit101can be easily exchanged through the rail mechanism102.

Each component of the microwave heating apparatus1is connected to the control unit8and controlled by the control unit8. The control unit8is typically a computer.FIG. 14is a diagram showing a configuration of the control unit8shown inFIG. 1. In the example ofFIG. 14, the control unit8includes a process controller81having a CPU, and a user interface82and a storage unit83connected to the process controller81.

The process controller81is a control means for overall control of respective components (e.g., the microwave introducing device3, the support device4, the gas supply device5a,the exhaust device6, the temperature measurement unit27and the like) involved in the processing conditions such as temperature, pressure, gas flow rate and microwave output in the microwave heating apparatus1.

The user interface82includes a keyboard or touch panel through which a process manager inputs a command to manage the microwave heating apparatus1, a display for visually displaying an operational status of the microwave heating apparatus1, and so forth.

The storage unit63stores therein, e.g., control programs (software) for implementing various processes in the microwave heating apparatus1under the control of the process controller81, and recipes including processing condition data and the like. In response to instructions from the user interface82or the like, if necessary, a control program or recipe is retrieved from the storage unit83and executed by the process controller81. Accordingly, a desired process is performed in the processing chamber2of the microwave heating apparatus1under the control of the process controller81.

The control programs and the recipes may be read out from a computer-readable storage medium (e.g., a CD-ROM, a hard disk, a flexible disk, a flash memory, a DVD, a Blu-ray Disc, etc.). Further, the recipes may be used online by transmission from another apparatus through, e.g., a dedicated line, whenever necessary.

Next, a processing procedure in the microwave heating apparatus1when an annealing process is performed on the wafer W will be described. First, a command is inputted to the process controller81from, e.g., the user interface82to perform an annealing process in the microwave heating apparatus1. Then, the process controller81reads the recipe stored in the storage unit83or computer-readable storage medium in response to this command. Then, a control signal is transmitted from the process controller81to each end device (e.g., the microwave introducing device3, the support device4, the gas supply device5a,the exhaust device6, and the like) of the microwave heating apparatus1such that the annealing process is performed under the conditions based on the recipe.

Subsequently, the gate valve G is opened, and the wafer W is loaded into the processing chamber2through the gate valve G and the loading and unloading port12aby a transfer device (not shown) and mounted on the support pins16. The support pins16are elevated in a vertical direction together with the shaft14and the arm portions15by driving the elevation drive unit18, and the wafer W is set at a predetermined vertical position (initial vertical position). At this vertical position, by driving the rotation drive unit17, the wafer W is rotated at a predetermined speed in the horizontal direction. Further, the rotation of the wafer W may not be continuous but be discontinuous. Then, the gate valve G is closed, and the processing chamber2is vacuum-evacuated by the exhaust device6if necessary. Then, the processing gas and the cooling gas are introduced at a predetermined flow rate by the gas supply device5a.The pressure of the inner space of the processing chamber2is adjusted to a predetermined pressure by adjusting the gas supply amount and the exhaust amount.

Then, a voltage is applied from the high voltage power supply unit40to each magnetron31to generate a microwave.

The microwave generated in the magnetron31is propagated through the waveguide32, and then transmitted through the transmission window33to be introduced into a space above the wafer W rotating in the processing chamber2. In this embodiment, microwaves are generated sequentially in the magnetrons31, and are alternately introduced into the processing chamber2from each of the microwave introduction ports10. Alternatively, microwaves may be generated simultaneously in the magnetrons31, and simultaneously introduced into the processing chamber2from the microwave introduction ports10.

The microwaves introduced into the processing chamber2are irradiated onto the surface of the rotating wafer W, and the wafer W is heated rapidly by electromagnetic wave heating such as Joule heating, magnetic heating and induction heating. As a result, the annealing process is performed on the wafer W. During the annealing process, the vertical position of the wafer W may be displaced in multiple stages.

For example, during a certain period of time from the start of the annealing process, the wafer W is set at the initial vertical position (first vertical position). Then, by driving the elevation drive unit18, the wafer W may be moved from the initial vertical position to and set at a second vertical position different from the initial vertical position and the remaining annealing may be carried out at the second vertical position.

Further, the vertical position may be set in three or more stages without being limited to two stages, and switching of the vertical position in two or more stages may be repeated. Thus, by processing the wafer W at the vertical position of two or more stages, it is possible to reduce the bias of the microwaves irradiated to the wafer W and to suppress the reflection of microwaves. As a result, it is possible to make uniform the heating temperature in the plane of the wafer W while improving the heating efficiency by increasing a maximum temperature and a rate of temperature rise.

When a control signal for terminating the annealing process is transmitted from the process controller81to each end device of the microwave heating apparatus1, the generation of the microwaves is stopped, the rotation of the wafer W is stopped, and the supply of the processing gas and the cooling gas is stopped to thereby terminate the annealing process on the wafer W. Then, the gate valve GV is opened, the vertical position of the wafer W on the support pins16is adjusted, and the wafer W is unloaded by the transfer device (not shown).

The microwave heating apparatus1may be preferably used for the purpose of annealing for activation of doping atoms implanted in a diffusion layer in, e.g., a manufacturing process of semiconductor devices.

Next, effects of the microwave heating apparatus1and a processing method of the wafer W using the microwave heating apparatus1according to the present embodiment will be described with reference toFIGS. 1,6and15to18. In the present embodiment, by driving the rotation drive unit17, annealing is performed on the wafer W held on the support pins16while rotating the wafer W at a predetermined speed in the horizontal direction. Thus, microwave radiation in the circumferential direction within the plane of the wafer W is uniform. Therefore, it is possible to realize uniform annealing in the circumferential direction within the plane of the wafer W by the rotation.

Further, in the present embodiment, in order to achieve uniform microwave irradiation in the radial direction within the plane of the wafer W, as shown inFIG. 6, the four microwave introduction ports10may be divided and arranged such that two or more microwave radiation zones can be formed. By this arrangement, in the case of performing annealing on the wafer W while horizontally rotating the wafer W, it is possible to enhance the heating uniformity in the radial direction of the wafer W in addition to the heating uniformity in the circumferential direction of the wafer W. Thus, by combining the rotation of the wafer W and the arrangement of the microwave introduction ports10, it is possible to realize uniform annealing in the plane of the wafer W.

Simulation results of the power absorption efficiency of the wafer W in the case where the arrangement of the microwave introduction ports10was changed in the X-axis or the Y-axis direction will now be described with reference toFIGS. 15 and 16. These simulations were carried out for the purpose of obtaining optimal arrangement in the case of forming the inner microwave radiation zone by the two microwave introduction ports10located at the reference position among the four microwave introduction ports10and forming the outer microwave radiation zone by translating the other two microwave introduction ports10in an outward direction.

FIG. 15andFIG. 16show maps of simulation results showing volume loss density distribution of microwave power within the plane of the wafer W, and wafer absorbed power Pw and scattering parameters obtained from the simulations. Further, in the frame of the upper left end ofFIGS. 15 and 16, the reference positions of the microwave introduction ports10simulated and the moving direction therefrom are shown by being projected on the wafer W. In this case, the reference positions of the microwave introduction ports10was set as an arrangement in which the center of each of the four microwave introduction ports10lies on the virtual circle having a radius of 55 mm from the center O of the wafer W.

FIG. 15shows the simulation results when the position of the center of each of the two microwave introduction ports10which are not adjacent to each other was shifted up to 120 mm by 10 mm increment outwardly in the X-axis direction from the reference position.FIG. 16shows the simulation results when the position of the center of each of the two microwave introduction ports10, which are not adjacent to each other, was shifted by 10 mm increment up to 100 mm outwardly in the Y-axis direction from the reference position.

Other conditions in these simulations are as follows. The processing chamber includes the sidewall portions12forming a square tubular shape. The long and the short sides of the four microwave introduction ports10are provided to be parallel to the inner wall surfaces of the four sidewall portions12. The ratio L1/L2of the length L1of the long sides to the length L2of the short sides of the respective microwave introduction port10is 4.

Further, the four microwave introduction ports10are arranged such that when one of the microwave introduction ports10is translated in the X-axis direction perpendicular to the long sides thereof, it does not overlap another microwave introduction port10having long sides parallel thereto. The wafer W was assumed to be a silicon wafer doped with impurities such as arsenic. The simulations were conducted under conditions that microwaves of power ranging from 500 W to 3000 W are introduced from one microwave introduction port represented in black in the frame of the upper left end ofFIGS. 15 and 16.

In this case, the absorption power of the wafer W can be calculated by using the scattering parameters (S parameters). When the input power is Pin and the total power absorbed by the wafer W is Pw, the total power Pw can be obtained by the following Eq. (1). Further, S11, S21, S31and S41are S parameters of the four microwave introduction ports10, and the microwave introduction port10in black corresponds to Port1.

Further, the distribution of power absorption within the plane of the wafer W was calculated by obtaining the electromagnetic waves volume loss density using a pointing vector in the plane of the wafer W. Further, the total power Pw absorbed by the wafer W can be obtained by the following Eq. (2). By calculating these values with an electromagnetic field simulator and plotting on the wafer W, maps shown inFIGS. 15 and 16were created. In these maps, although not expressed exactly due to black and white representation, the more light black (white) indicates substantially the larger electromagnetic waves volume loss density within the plane of the wafer W.

PW[W]=∫∫SWRe{right arrow over (S)}·{right arrow over (n)}dS=∫∫SW∫0δwRe[1/2({right arrow over (E)}·{right arrow over (J*)}−∇×{right arrow over (E)}·{right arrow over (H*)})]dSdz(2)

In the Eq. (2), {right arrow over (S)} is the pointing vector, {right arrow over (J)} is a current density, and {right arrow over (E)} and {right arrow over (H)} represent electric and magnetic field, respectively.

From the simulation results shown inFIG. 15, it is believed that when each of the two microwave introduction ports10which are not adjacent to each other is shifted in the X-axis direction from the reference position, the total power Pw absorbed by the wafer W is large at a position to which the corresponding microwave introduction port10has been moved by, e.g., 80 mm outwardly, and the power absorption distribution within the plane of the wafer W is also uniform. Thus, this is considered as optimal arrangement for forming the outer microwave radiation zone. Therefore, in the case of the above simulation conditions, it is preferable that each of the two microwave introduction ports10which are not adjacent to each other is shifted in the X-axis direction outwardly from the reference position by a distance in the range from 10 mm to 80 mm.

Moreover, from the simulation results shown inFIG. 16, it is thought when each of the two microwave introduction ports10which are not adjacent to each other is shifted in the Y-axis direction from the reference position, the total power Pw absorbed by the wafer W is large and the power absorption distribution within the plane of the wafer W is also uniform, at a position to which the corresponding microwave introduction port10has been moved by, e.g., 50 mm outwardly. Thus, this is considered as optimal arrangement for forming the outer microwave radiation zone. Therefore, in the case of the above simulation conditions, it is preferable that each of the two microwave introduction ports10which are not adjacent to each other is shifted in the Y-axis direction outwardly from the reference position by a distance in the range from 10 mm to 70 mm.

By these simulations, it is possible to determine the optimal positions of the microwave introduction ports10for various types of wafers W in the case of rotating the wafer W. Further, it was observed that it is possible to control the distribution of power absorption in the plane of the wafer W by dividing and arranging the four microwave introduction ports10to form a plurality of microwave radiation zones.

Next, the simulation results obtained by observing an effect of the rounding process of the corner portions as the connecting portions of the adjacent sidewall portions12of the processing chamber2on the reflection of microwaves will be described with reference toFIGS. 17 and 18.FIG. 17is an explanatory diagram schematically showing the configuration of the microwave heating apparatus which is assumed in the simulation.FIG. 17schematically shows a positional relationship of the wafer W and the shape of the sidewall portions12(only the positions of the inner wall surfaces are shown) in the case where the rounding process was performed on the corner portions of the connecting portions of the adjacent sidewall portions12.

Further, inFIG. 17, the positions of the four microwave introduction ports10A,10B,10C and10D provided in the ceiling portion11(not shown) are illustrated by being projected onto the wafer W. As shown inFIG. 17, all corner portions C between the sidewall portion12A and the sidewall portion12B, between the sidewall portion12B and the sidewall portion12C, between the sidewall portion12C and the sidewall portion12D, and between the sidewall portion12D and the sidewall portion12A are rounded with a radius of curvature Rc. Other configurations were the same as those of the microwave heating apparatus1.

In the simulation, scattering parameters S11and S31when the radius of curvature Rcof the rounding process of the corner portions C was changed from 0 mm (right angle) to 18 mm in 1 mm increments ware analyzed. In this case, the microwaves were introduced from the microwave introduction port10A. S11is the scattering parameter of the radiated microwaves and the reflected microwaves of the microwave introduction port10A, and S31is the scattering parameter of the radiated microwaves of the microwave inlet port10A and the reflected microwaves of the microwave introduction port10C.

The simulation results are shown inFIG. 18. It can be seen fromFIG. 18that when the radius of curvature Rcranges from 15 mm to 16 mm, the variation of S11and S31is small and each of S11and S31has a relatively low value. Therefore, it has been confirmed that, from the viewpoint of suppressing the reflected waves incident onto the microwave introduction ports10to increase the use efficiency of the microwave power, in the rounding process of the corner portions C of the connecting portions of the adjacent sidewall portions12of the processing chamber2, the radius of curvature Rcpreferably ranges from 15 mm to 16 mm. Further, in the simulation, the rounding process was carried out on the corner portions C that is the connecting portions between the adjacent sidewall portions12of the processing chamber2, but the rounding process using the same radius of curvature Rcmay be preferably applied to the corner portions that is connecting portions between each of the sidewall portions12and the bottom portion13.

From the above simulation results, it was also confirmed that uniform heating processing can be implemented on the wafer W by using the microwave heating apparatus1according to the present embodiment.

As described above, in this embodiment, the microwave introduction ports10are arranged to correspond to the inner microwave radiation zone and the outer microwave radiation zone in addition to the rotation of the wafer W, thereby improving the in-plane uniformity of the annealing process. However, the microwaves form standing waves, and in the case where the standing waves are generated in the processing chamber2, positions of nodes and antinodes of the standing waves are fixed. Since the electromagnetic field becomes strong locally at the positions of the nodes of the standing waves, and the electromagnetic field becomes weak locally at the positions of the antinodes of the standing waves, the annealing process may be non-uniform in the radial direction of the wafer W even when the two microwave radiation zones are formed.

Therefore, in the present embodiment, more preferably, it is configured to vary the vertical position of the wafer W by the elevation drive unit18. As shown inFIG. 1, varying the vertical position of the wafer W supported by the support pins16is the same as varying the distance (gap G) from the lower surface of the transmission window33of the microwave introduction port10to the top surface of the wafer W held on the support pins16. Even though standing waves are formed in the processing chamber2, a relative positional relationship between the wafer W and the standing waves can be changed by changing the gap G. As a result, it is possible to change the radiation distribution of microwaves in the radial direction of the wafer W.

Next, the experimental results in the case where an annealing process was performed while changing the vertical position of the wafer W in the microwave heating apparatus1will be described with reference toFIGS. 19 to 26.

EXPERIMENTAL EXAMPLE 1

FIG. 19is a graph showing the results of an experiment of measuring a temperature change in the plane of the wafer W when an annealing process was performed while changing the vertical position of the wafer W having a diameter of 300 mm, which is supported on the support pins16, by using the microwave heating apparatus1. In this experiment, three points of point1(0 mm in the radial direction from the center O of the wafer W), point2(75 mm in the radial direction from the center O of the wafer W), and point3(145 mm in the radial direction from the center O of the wafer W) were measured.

The annealing process was carried out for 5 minutes at a microwave frequency of 5.8 GHz, a microwave power of 2000 W, a pressure of 90 kPa, and a nitrogen gas flow rate of 10 slm (L/min). The horizontal axis ofFIG. 19shows the vertical position of the wafer W, which is a height (mm) from the upper surface of the rectifying plate24. Further, the height from the upper surface of the rectifying plate24to the lower surface of the transmission window33covering the microwave introduction port10is 67 mm. The vertical axis ofFIG. 19is an attainment temperature at each measuring point of the wafer W.

It can be found fromFIG. 19that a change in the heating temperature depending on the vertical position of the wafer W is largely different between the points1,2and3. For example, temperature differences between three measuring points in the plane of the wafer W range from 2° C. to 3° C. if the height from the upper surface of the rectifying plate24is about 20 mm, whereas they are increased to about 40° C. if the height from the upper surface of the rectifying plate24is about 30 mm. This indicates that the temperature distribution within the plane of the wafer W varies according to the vertical position of the wafer W, and the temperature distribution within the plane of the wafer W can be controlled by changing the vertical position of the wafer W.

EXPERIMENTAL EXAMPLE 2

FIG. 20is a graph showing measurement results of a sheet resistance value when a silicon wafer doped with arsenic as impurities was annealed and activated by performing an annealing process while changing the vertical position of the wafer in the microwave heating apparatus1. The annealing conditions were the same as those in Experiment 1.FIG. 20shows an average and a standard deviation of a sheet resistance (ρs) for the cases where the vertical position of the wafer W was set to 21.2 mm, 27.0 mm and 31.2 mm from the upper surface of the rectifying plate24, and for the case where processing for 3 minutes at the vertical position of 27.0 mm is combined with processing for 2 minutes at the vertical position of 31.2 mm.FIG. 20also shows a map indicating in-plane distribution of the wafer W of the sheet resistance at each vertical position. These maps are black-and-white displays and do not exactly represent the in-plane distribution of the sheet resistance, but they show that the distribution of the sheet resistance is smaller (uniformity is better) as shading of the color is less.

It can be confirmed fromFIG. 20that in the cases where the vertical position of the wafer W is 27.0 mm and 31.2 mm from the upper surface of the rectifying plate24, the standard deviations of the sheet resistance values are large and the map showing the in-plane distribution of the sheet resistance also has a large variation. On the other hand, it can be confirmed that in the case where the vertical position of the wafer W is 21.2 mm from the upper surface of the rectifying plate24, the standard deviation of the sheet resistance value is small, and the map showing the in-plane distribution of the sheet resistance has a substantially uniform state.

Referring to the results of Experiment 1 shown inFIG. 19, the temperature distribution within the plane of the wafer W is the smallest when the vertical position of the wafer W is about 20 mm from the upper surface of the rectifying plate24, which is consistent with that shown inFIG. 20, that is, the in-plane uniformity of the sheet resistance is high when the vertical position of the wafer W is 21.2 mm from the upper surface of the rectifying plate24. On the other hand, as shown inFIG. 19, the temperature differences in the plane of the wafer W are largest when the vertical position of the wafer W is about 30 mm from the upper surface of the rectifying plate24, which is consistent with that shown inFIG. 20, i.e., the variations of the sheet resistance values are high when the vertical position of the wafer W is 27.0 mm and 31.2 mm from the upper surface of the rectifying plate24.

Further, in the case of changing the vertical position of the wafer W from 27.0 mm (for 3 min) to 31.2 mm (for 2 min) during the annealing process, the uniformity of the sheet resistance within the plane of the wafer W is significantly improved as compared to the case where the vertical position is 27.0 mm or 31.2 mm. It is considered that this is because the non-uniformity of the annealing process at each vertical position is offset and the distribution of the sheet resistance within the plane of the wafer W is resolved as a result of combining two different vertical positions.

EXPERIMENTAL EXAMPLE 3

A microwave reflection amount and a temperature change in the plane of the wafer W when an annealing process was performed while changing the vertical position of the wafer W having a diameter of 300 mm, which is supported by the support pins16in the microwave heating apparatus1were measured. The microwave reflection amount was measured by the detector35(hereinafter, the same applies). In this experiment, the annealing process was carried out for 2 minutes at a microwave frequency of 5.8 GHz, microwave power of 3900 W, a pressure of 100 kPa, and a nitrogen gas flow rate of 5 slm (L/min).

The experiment was performed by changing a height (hereinafter, may be referred to as “wafer height”) Z to the back surface of the wafer W from the upper surface of the bottom portion13of the processing chamber2. The height Z was set to 34 mm under condition A, the height Z was set to 36 mm under condition B, and the height Z was changed from 34 mm to 36 mm during the annealing process under condition C. A timing of changing the wafer height Z under condition C was set to a time point when about 25 seconds have been elapsed from the start of the annealing process.

In the annealing process under condition A and condition B, a relationship between time and the temperature of the wafer W is shown inFIG. 21, and a relationship between time and the microwave reflection amount is shown inFIG. 22. Further, under condition C, a relationship between time and the temperature of the wafer W is shown inFIG. 23, and a relationship between time and the microwave reflection amount is shown inFIG. 24. Further, for reference,FIG. 23also shows the results of condition A and condition B together with the result of condition C.

It can be seen fromFIGS. 21 and 23that the temperature rise rate under condition A (Z=34 mm) is higher than that under condition B (Z=36 mm), and the maximum attainment temperature under condition B is higher than that under condition A. Further, the temperature rise rate under condition C (Z=34 mm36 mm) is the same as that under condition A, and the maximum temperature under condition C is the same as that under condition B. That is, by changing the wafer height Z from 34 mm to 36 mm during the annealing process, under condition C, both a large temperature rise rate equivalent to that under condition A and a high attainment temperature equivalent to that under condition B are obtained.

In addition, it can be seen fromFIG. 22that in the case of condition B (Z=36 mm), the microwave reflection amount is large until the processing time reaches about 30 seconds as compared to condition A (Z=34 mm). On the other hand, under condition A (Z=34 mm), the reflection amount is increased from when the processing time exceeds about 30 seconds. It is considered that this is because the matching in the processing chamber2was changed by the temperature rise of the wafer W. However, it can be seen fromFIG. 24that under condition C that the wafer height Z is changed during the annealing process, it is possible to reduce the microwave reflection amount.

EXPERIMENTAL EXAMPLE 4

FIG. 25is a graph showing the results of an experiment of measuring the maximum temperature of the wafer W when an annealing process was performed while changing the vertical position of the wafer W having a diameter of 300 mm, which is supported by the support pins16, by using the microwave heating apparatus1. The experiment was performed by changing the wafer height Z. The annealing process was carried out for 5 minutes at a microwave frequency of 5.8 GHz, a microwave power of 3900 W, a pressure of 100 kPa, and a nitrogen gas flow rate of 5 slm (L/min). It was confirmed fromFIG. 25that by changing the wafer height Z, the heating temperature (maximum temperature) of the wafer W is also changed and, thus, the wafer height Z affects the heating efficiency.

EXPERIMENTAL EXAMPLE 5

FIG. 26is a graph showing the results of an experiment of measuring the microwave reflection amount when an annealing process was performed while changing the vertical position of the wafer W having a diameter of 300 mm, which is supported by the support pins16, under the same conditions as Experiment 4 by using the microwave heating apparatus1. It was confirmed fromFIG. 26that by changing the wafer height Z, the microwave reflection amount is changed and, thus, the wafer height Z affects the absorption efficiency of microwaves.

From the above results, it became clear that the vertical position of the wafer W may significantly affect the microwave reflection amount in the annealing process, the temperature distribution in the plane of the wafer W, the distribution of the sheet resistance, the temperature rise rate and the maximum temperature. Further, it was confirmed that by changing the vertical position of the wafer W during the annealing process, it is possible to make uniform the sheet resistance or temperature distribution in the plane of the wafer W, and also improve the heating efficiency by suppressing the reflection of microwaves to increase the temperature rise rate and the maximum temperature.

As described above, in the microwave heating apparatus and the processing method according to the present embodiment, by performing the annealing process while rotating the wafer W at a predetermined speed in the horizontal direction, the radiation of microwaves in the circumferential direction of the wafer W is made uniform. Further, by arranging the four microwave introduction ports10such that the centers Opthereof lie on two virtual concentric circles and two microwave radiation zones are formed, when the annealing process is performed while horizontally rotating the wafer W, it is possible to enhance the heating uniformity in the radial direction of the wafer W in addition to the heating uniformity in the circumferential direction of the wafer W. Further, in the microwave heating apparatus and the processing method according to the present embodiment, by changing the vertical position of the wafer W during the annealing process, it is possible to further improve the in-plane uniformity of the annealing process on the wafer W. Thus, according to the microwave heating apparatus and the processing method of the present embodiment, it is possible to perform uniform heating processing on the wafer W.

Next, other effects of the microwave heating apparatus1according to the present embodiment will be described. In this embodiment, by combination of the characteristic arrangement and the characteristic shape of the microwave introduction ports10and the shape of the sidewall portions12of the processing chamber2, the microwaves radiated from one microwave introduction port10into the processing chamber2are prevented as much as possible from entering the other microwave introduction ports10.FIGS. 27 and 28schematically show the radiation directivity of the microwaves in the microwave introduction port10, a ratio L1/L2of the length L1of the long sides to the length L2of the short sides of which is at least 4.FIG. 27shows the microwave introduction port10viewed from below the ceiling portion11(not shown).FIG. 28shows the microwave introduction port10in a cross-section of the ceiling portion11in a direction of the short side thereof.

InFIGS. 27 and 28, arrows indicate electromagnetic field vectors100radiated from the microwave introduction port10, and the directivity of the microwaves is stronger as the arrow is longer. Further, inFIGS. 27 and 28, both the X axis and the Y axis are oriented in the direction parallel to the lower surface of the ceiling portion11. The X axis refers to a direction perpendicular to the long sides of the microwave introduction port10, and the Y axis refers to a direction parallel to the long sides of the microwave introduction port10. Further, the Z axis refers to a direction perpendicular to the lower surface of the ceiling portion11.

In this embodiment, as described above, the four microwave introduction ports10formed in a rectangular shape having long and short sides in a plan view are arranged in the ceiling portion11. The ratio L1/L2of the microwave introduction port10used in this embodiment is set to, e.g., 2 or more, preferably, 4 or more. Therefore, as shown inFIG. 27, the radiation directivity of the microwaves is strong and becomes dominant along the X axis (direction perpendicular to the long sides (direction parallel to the short sides)). Accordingly, the microwaves radiated from any one of the microwave introduction ports10mainly propagate along the ceiling portion11of the processing chamber2, and are reflected by the inner wall surfaces of the sidewall portions12serving as reflective surfaces, which are parallel to the long sides thereof.

In this embodiment, the inner wall surfaces of the four sidewall portions12of the processing chamber2are provided in a direction perpendicular to each other, and the long sides and the short sides of each of the four microwave introduction ports10are provided to be parallel to the inner wall surfaces of the four sidewall portions12A,12B,12C and12D. Therefore, the direction of the waves reflected by the four sidewall portions12A,12B,12C and12D is opposite by almost 180 degrees to the direction of traveling waves, and the reflected waves hardly travel toward the other microwave introduction ports10.

In the present embodiment, by setting the ratio L1/L2to 2 or more, preferably, 4 or more, as shown inFIG. 28, the directivity of the microwaves radiated from the microwave introduction ports10increases in the lateral direction (X-axis direction), and propagates mainly in the lateral direction along the lower surface of the ceiling portion11. Therefore, the amount of microwaves irradiated directly onto the wafer W located immediately below the microwave introduction ports10is small, and local heating does not easily occur even when the gap G is reduced by increasing the vertical position of the wafer W. As a result, it is possible to perform uniform processing on the wafer W in the microwave heating apparatus1according to the present embodiment.

On the other hand, if the ratio L1/L2is smaller than 2, although not shown, since the directivity of the microwaves becomes stronger along the Y axis, i.e., in the direction parallel to the long sides (direction perpendicular to the short sides) and the directivity in the X-axis direction perpendicular to the long sides (direction parallel to the short sides) is relatively weakened, a dominant direction in the radiation directivities of the microwaves disappears.

Thus, when the microwave introduction ports10having the ratio L1/L2smaller than 2 (e.g., long side:short side=1:1) are arranged as shown inFIG. 6, for example, the microwaves radiated from the microwave introduction port10A are likely to propagate also in the direction (Y-axis direction) parallel to the long sides of the microwave introduction port10A and enter the microwave introduction port10C. Further, in the microwave introduction port10having the ratio L1/L2less than 2, the directivity of the radiated microwaves becomes strong in a downward direction (i.e., direction toward the wafer W along the Z axis), and a percentage of the microwaves irradiated directly onto the wafer W immediately below the microwave introduction port10increases. Accordingly, local heating in the plane of the wafer W is likely to occur in the case of reducing the gap G by increasing the vertical position of the wafer W.

In the present embodiment, as shown inFIG. 6, the four microwave introduction ports10having the ratio L1/L2of 2 or more are arranged to be shifted by an angle of 90 degrees such that central axes AC parallel to the long sides of the two microwave introduction ports10adjacent to each other are perpendicular to each other. Further, each microwave introduction port10is disposed so as not to overlap the other microwave introduction port10having long sides parallel thereto when it is translated in the direction perpendicular to the long sides. Thus, it is possible to prevent the microwaves radiated from one of the microwave introduction ports10and the reflected waves thereof from entering the other microwave introduction port10having the same microwaves excitation direction as that of the one microwave introduction port10in the direction perpendicular to the long sides of the one microwave introduction port10.

Further, in this embodiment, the two microwave introduction ports10which are not adjacent to each other among the four microwave introduction ports10are arranged such that the central axes AC thereof do not overlap each other on the same straight line. With this arrangement, also in the direction perpendicular to the short sides of the microwave introduction ports10, the microwaves radiated from one of the microwave introduction ports10and the reflected waves thereof hardly enter the other microwave introduction port10having the same microwaves excitation direction as that of the one microwave introduction port10.

As the above, in the present embodiment, the microwave introduction ports10are arranged in consideration of the shape of the microwave introduction ports10, particularly, the ratio L1/L2, the radiation directivity of the microwaves which depends on the shape of the microwave introduction ports10, and the shape of the sidewall portions12of the processing chamber2. Therefore, in this embodiment, it is possible to prevent as much as possible the microwaves introduced from one of the microwave introduction ports10from entering the other microwave introduction ports10, thereby minimizing the loss of power.

In the microwave heating apparatus1of the present embodiment, as described above, the characteristic arrangement and the characteristic shape of the microwave introduction ports10and the shape of the sidewall portions12of the processing chamber2are combined with the rotation of the wafer W and the adjustment of the vertical position. By efficiently using the microwaves having the radiation directivity shown inFIGS. 27 and 28or the reflected waves traveling in the opposite direction thereto through this combination, it is possible to perform the annealing process with excellent uniformity in the radial direction as well as in the circumferential direction in the plane of the wafer W.

Second Embodiment

Next, a microwave heating apparatus according to a second embodiment of the present invention will be described with reference toFIGS. 29 to 31.FIG. 29is a cross-sectional view showing a schematic configuration of a microwave heating apparatus1A according to the present embodiment.FIG. 30is an explanatory diagram showing a state in which a microwave introducing adaptor50serving as an adaptor member having a waveguide path for transmitting microwaves therein is mounted on the ceiling portion11in the microwave heating apparatus1A.FIG. 31is an explanatory diagram showing a state of a groove formed in the microwave introducing adaptor50.

The microwave heating apparatus1A of the present embodiment performs an annealing process by irradiating microwaves to, e.g., a semiconductor wafer W for manufacturing semiconductor devices in accordance with a plurality of consecutive operations. In the following description, differences between the microwave heating apparatus1B of the present embodiment and the microwave heating apparatus1of the first embodiment will be mainly described. In the microwave heating apparatus1A shown inFIGS. 29 to 31, components having the same configuration as those in the microwave heating apparatus1of the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted.

The microwave heating apparatus1A includes a processing chamber2for accommodating a wafer W serving as a target object to be processed, a microwave introducing device3A for introducing microwaves into the processing chamber2, a support device4for supporting the wafer W in the processing chamber2, a gas supply mechanism5for supplying a gas into the processing chamber2, an exhaust device6for vacuum-evacuating the processing chamber2, and a control unit8for controlling the respective components of the microwave heating apparatus1A.

The microwave introducing device3A is provided at the top of the processing chamber2, and functions as a microwave introducing unit for introducing electromagnetic waves (microwaves) into the processing chamber2. As shown inFIG. 29, the microwave introducing unit3A includes a plurality of microwave units30for introducing the microwaves into the processing chamber2, a high voltage power supply unit40connected to the microwave units30, and the microwave introducing adaptor50connected between a waveguide32and microwave introduction ports10to transmit the microwaves therebetween.

In the present embodiment, the microwave units30have the same configuration. Each of the microwave units30includes a magnetron31to generate microwaves for processing the wafer W, the waveguide32to transmit the microwaves generated in the magnetron31to the processing chamber2, and a transmission window33fixed to the ceiling portion11to cover the microwave introduction port10. Each of the microwave units30further includes a circulator34, a detector35and a tuner36which are provided in the waveguide32, and a dummy load37connected to the circulator34.

As shown inFIG. 30, the microwave introducing adaptor50includes a plurality of metallic block bodies. That is, the microwave introducing adaptor50includes a single large central block51disposed at the center thereof, and four auxiliary blocks52A,52B,52C and52D disposed around the central block51. The block bodies are fixed to the ceiling portion11by a fixing unit such as a bolt.

As shown inFIG. 31, the central block51has a plurality of grooves51aformed on its side surfaces. At the corresponding side of the central block51, each of the grooves51ais formed to have a substantially S-shape extending from the upper surface to the lower surface of the central block51in a side view. The number of the grooves51acorresponds to the number of the microwave units30, and is four in this embodiment.

The auxiliary blocks52A to52D are combined with the central block51to form the microwave introducing adaptor50. The auxiliary blocks52A to52D are arranged respectively to correspond to the grooves51aof the central block51. That is, each of the auxiliary blocks52A to52D is fixed in close contact with the side surface on which each of the grooves51aof the central block51is formed. Further, a substantially S-shaped waveguide path53capable of transmitting microwaves therethrough is formed by closing an opening of the groove51aon the side surface of the central block51by each of the auxiliary blocks52A to52D. That is, the waveguide path53is formed by three walls in the groove51aand one wall of each of the auxiliary blocks52A to52D.

The waveguide path53is a through opening extending from the upper surface to the lower surface of the microwave introducing adaptor50. The upper end of the waveguide path53is fixed to the lower end of the waveguide32, and the lower end of the waveguide path53is connected to the transmitting window33for closing the microwave introduction port10. The waveguide32is position-aligned with the waveguide path53and fixed to the microwave introducing adaptor50by a fixing unit such as a bolt. The waveguide path53is formed in an S shape in order to shift the positions of the waveguide32and the microwave introduction port10in the horizontal direction while minimizing the transmission loss of the microwaves. Thus, by using the combination of a plurality of block bodies, it is possible to form the waveguide path53with little transmission loss by simple metal processing.

In the microwave heating apparatus1A of the present embodiment, by using the microwave introducing adaptor50, it is possible to significantly increase the flexibility of arrangement of the microwave units30and the microwave introduction ports10. In the microwave heating apparatus1A, it is necessary to provide the components of the four microwave units30except for the transmission windows33at the top of the processing chamber2. However, since there is a limit to an installation space above the processing chamber2, in the configuration in which the waveguides32are connected directly to the microwave introduction ports10, the arrangement of the microwave introduction ports10may be restricted by the interference between the adjacent microwave units30.

In the present embodiment, the relative position between the microwave introduction port10and the waveguide32may be flexibly adjusted by using microwave introducing adaptor50having the S-shaped waveguide path53. That is, it is possible to flexibly adjust from the fixed arrangement in which they overlap each other vertically to the arrangement in which they do not overlap each other vertically or they only partially overlap each other (i.e., to be shifted laterally). Thus, by using the microwave introducing adaptor50, the microwave introduction port10may be provided at any portion of the ceiling portion11without being restricted to the installation space of the microwave unit30. For example, in the case where the four microwave introduction ports10are arranged to be concentrated near the center of the ceiling portion11, it is possible to avoid the interference between the microwave units30by using the microwave introducing adaptor50.

In the microwave heating apparatus1A as described above, by using the microwave introducing adaptor50, the flexibility of arrangement of the microwave introduction ports10is significantly improved. Therefore, according to the microwave heating apparatus1A of the present embodiment, the uniformity of heating in the plane of the wafer W may be improved to perform uniform heating processing on the wafer W.

The other configurations and effects of the microwave heating apparatus1A of the present embodiment are the same as those of the microwave heating apparatus1of the first embodiment, and a description thereof will be omitted. Further, the block body used in the microwave introducing adaptor50may have various shapes and sizes according to the number and arrangement of the microwave introduction ports10. For example, the waveguide path may be formed by combining small block bodies such as the auxiliary blocks52A to52D without providing the central block51. Further, in this embodiment, the microwave introducing adaptor50is common to the microwave units30, but the microwave introducing adaptor50may be provided individually for each of the microwave units30. Further, the microwave introducing adaptor50may be included as a part of the configuration of the microwave unit30.

The present invention may be modified in various ways without being limited to the above embodiments. For example, the microwave heating apparatus of the present invention is not limited to the case of using a semiconductor wafer as a target object to be processed and may also be applied to a microwave heating apparatus which uses, as the target object, e.g., a substrate for a solar cell panel or a substrate for a flat panel display.

The number of the microwave units30(the magnetrons31) and the number of microwaves simultaneously introduced into the processing chamber2are not limited to those described in the above embodiments.

This international application claims priority to Japanese Patent Application No. 2012-40095 filed on Feb. 27, 2012, Japanese Patent Application No. 2012-179803 filed on Aug. 14, 2012, and Japanese Patent Application No. 2012-261338 filed on Nov. 29, 2012, the entire contents of which are incorporated herein by reference.