Patent Publication Number: US-11024521-B2

Title: Heat treatment method for managing dummy wafer

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a heat treatment method which manages dummy wafers. 
     Description of the Background Art 
     In the process of manufacturing a semiconductor device, attention has been given to flash lamp annealing (FLA) which heats a semiconductor wafer in an extremely short time. The flash lamp annealing is a heat treatment technique in which xenon flash lamps (the term “flash lamp” as used hereinafter refers to a “xenon flash lamp”) are used to irradiate a surface of a semiconductor wafer with a flash of light, thereby raising the temperature of only the surface of the semiconductor wafer in an extremely short time (several milliseconds or less). 
     The xenon flash lamps have a spectral distribution of radiation ranging from ultraviolet to near-infrared regions. The wavelength of light emitted from the xenon flash lamps is shorter than that of light emitted from conventional halogen lamps, and approximately coincides with a fundamental absorption band of a silicon semiconductor wafer. Thus, when a semiconductor wafer is irradiated with a flash of light emitted from the xenon flash lamps, the temperature of the semiconductor wafer can be raised rapidly, with only a small amount of light transmitted through the semiconductor wafer. Also, it has turned out that flash irradiation, that is, the irradiation of a semiconductor wafer with a flash of light in an extremely short time of several milliseconds or less allows a selective temperature rise only near the surface of the semiconductor wafer. 
     Such flash lamp annealing is used for processes that require heating in an extremely short time, e.g. typically for the activation of impurities implanted in a semiconductor wafer. The irradiation of a surface of a semiconductor wafer implanted with impurities by an ion implantation process with a flash of light emitted from flash lamps allows the temperature rise in the surface of the semiconductor wafer to an activation temperature only for an extremely short time, thereby achieving only the activation of the impurities without deep diffusion of the impurities. 
     Typically, not only heat treatment but also processing or treatment of semiconductor wafers is performed lot by lot (a group of semiconductor wafers subjected to the same processing or treatment under the same conditions). In a single-wafer type substrate processing apparatus, semiconductor wafers in a lot are processed sequentially in succession. In a flash lamp annealer, semiconductor wafers in a lot are also transported one by one into a chamber and heat-treated sequentially. 
     Unfortunately, the temperature of in-chamber structures (structures in a chamber including a susceptor for holding a semiconductor wafer and the like changes in some cases in the course of the sequential processing or treatment of semiconductor wafers in a lot. Such a phenomenon occurs when new treatment starts in a flash lamp annealer which has been in a nonoperational condition for some time or when treatment conditions including a treatment temperature of semiconductor wafers and the like are changed. Changes in temperature of the in-chamber structures including the susceptor and the like in the course of the treatment of semiconductor wafers in a lot give rise to a problem that there arises a difference in temperature history during the treatment between initial semiconductor wafers and latter semiconductor wafers in the lot. 
     To solve such a problem, it has been common practice that dummy wafers not to be treated are transported into the chamber and supported by the susceptor prior to the start of the treatment of a lot, and flash heating treatment is performed on the dummy wafers under the same conditions as the lot to be treated, whereby the temperature of the in-chamber structures including the susceptor and the like is increased in advance (dummy running). U.S. Patent Application Publication No. 2017/0125312 discloses that flash heating processing is performed on about 10 dummy wafers, so that the temperature of the in-chamber structures including the susceptor and the like reaches a stable temperature during the processing. 
     The dummy wafers not to be treated are used in the dummy running performed a plurality of times, and are repeatedly subjected to the heating treatment. As a result, deterioration of the dummy wafers proceeds to accordingly make cracking and warpage prone to occur in the dummy wafers. The occurrence of cracking and warpage in the dummy wafers during the dummy running causes contamination in the chamber and transport trouble. It is hence necessary to accurately grasp the deterioration condition of the dummy wafers and to thereby replace a dummy wafer suffering advanced deterioration in an appropriately timed manner. In conventional techniques, however, the deterioration condition has not sufficiently been grasped because an operator views or writes on paper the treatment history of the dummy wafers to manage the treatment history. This has resulted in a problem that heating treatment is accidentally performed on a dummy wafer suffering excessively advanced deterioration. 
     SUMMARY 
     The present invention is intended for a method of managing a dummy wafer for a heat treatment process. 
     According to one aspect of the present invention, the method comprises the steps of: (a) calculating a wear-and-tear value by adding up values obtained by multiplying the temperature of a dummy wafer measured when the dummy wafer is heated by irradiation with light from a continuous lighting lamp by a heating time period; and (b) issuing an alarm when the wear-and-tear value is not less than a predetermined threshold value. 
     According to another aspect of the present invention, the method comprises the steps of: (a) calculating a wear-and-tear value by adding up the amounts of electric power inputted to a continuous lighting lamp which are measured when a dummy wafer is heated by irradiation with light from the continuous lighting lamp; and (b) issuing an alarm when the wear-and-tear value is not less than a predetermined threshold value. 
     According to another aspect of the present invention, the method comprises the steps of: (a) calculating a wear-and-tear value by adding up discharge voltages of a flash lamp measured when a dummy wafer is heated by irradiation with a flash of light from the flash lamp; and (b) issuing an alarm when the wear-and-tear value is not less than a predetermined threshold value. 
     According to another aspect of the present invention, the method comprises the steps of: (a) calculating a wear-and-tear value by adding up values obtained by multiplying the front surface temperature of a dummy wafer measured when the dummy wafer is heated by irradiation with a flash of light from a flash lamp by an irradiation time period; and (b) issuing an alarm when the wear-and-tear value is not less than a predetermined threshold value. 
     According to another aspect of the present invention, the method comprises the steps of: (a) calculating a first wear-and-tear value, a second wear-and-tear value, a third wear-and-tear value, and a fourth wear-and-tear value, the first wear-and-tear value being calculated by adding up values obtained by multiplying the temperature of a dummy wafer measured when the dummy wafer is heated by irradiation with light from a continuous lighting lamp by a heating time period, the second wear-and-tear value being calculated by adding up the amounts of electric power inputted to the continuous lighting lamp which are measured when the dummy wafer is heated by irradiation with light from the continuous lighting lamp, the third wear-and-tear value being calculated by adding up discharge voltages of a flash lamp measured when the dummy wafer is heated by irradiation with a flash of light from the flash lamp, the fourth wear-and-tear value being calculated by adding up values obtained by multiplying the front surface temperature of the dummy wafer measured when the dummy wafer is heated by irradiation with a flash of light from the flash lamp by an irradiation time period; and (b) issuing an alarm when at least one of the first, second, third, and fourth wear-and-tear values is not less than a predetermined threshold value. 
     The method is capable of appropriately managing the deterioration of dummy wafers to reliably grasp a dummy wafer suffering advanced deterioration. 
     It is therefore an object of the present invention to reliably grasp a dummy wafer suffering advanced deterioration. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a heat treatment apparatus according to the present invention; 
         FIG. 2  is a front view of the heat treatment apparatus of  FIG. 1 ; 
         FIG. 3  is a longitudinal sectional view showing a configuration of a heat treatment part; 
         FIG. 4  is a perspective view showing the entire external appearance of a holder; 
         FIG. 5  is a plan view of a susceptor; 
         FIG. 6  is a sectional view of the susceptor; 
         FIG. 7  is a plan view of a transfer mechanism; 
         FIG. 8  is a side view of the transfer mechanism; 
         FIG. 9  is a plan view showing an arrangement of halogen lamps; 
         FIG. 10  is a block diagram showing a configuration of a controller; 
         FIG. 11  is a flow diagram showing a procedure for management of a dummy wafer according to a first preferred embodiment of the present invention; and 
         FIG. 12  is a graph showing changes in temperature of the dummy wafer during preheating using the halogen lamps. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments according to the present invention will now be described in detail with reference to the drawings. 
     First Preferred Embodiment 
     First, a heat treatment apparatus according to the present invention will be described.  FIG. 1  is a plan view of a heat treatment apparatus  100  according to the present invention, and  FIG. 2  is a front view of the heat treatment apparatus  100 . The heat treatment apparatus  100  is a flash lamp annealer for irradiating a disk-shaped semiconductor wafer W serving as a substrate with flashes of light to heat the semiconductor wafer W. The size of the semiconductor wafer W to be treated is not particularly limited. For example, the semiconductor wafer W to be treated has a diameter of 300 mm and 450 mm. The semiconductor wafer W prior to the transport into the heat treat me apparatus  100  is implanted with impurities. The heat treatment apparatus  100  performs heating treatment on the semiconductor wafer W to thereby activate the impurities implanted in the semiconductor wafer W. It should be noted that the dimensions of components and the number of components are shown in exaggeration or in simplified form, as appropriate, in  FIG. 1  and the subsequent figures for the sake of easier understanding. An XYZ rectangular coordinate system in which an XY plane is defined as a horizontal plane and a Z axis is defined to extend in a vertical direction is additionally shown in  FIGS. 1 to 3  for purposes of clarifying the directional relationship therebetween. 
     As shown in  FIGS. 1 and 2 , the heat treatment apparatus  100  includes: an indexer part  101  for transporting untreated semiconductor wafers W from the outside into the heat treatment apparatus  100  and for transporting treated semiconductor wafers W to the outside of the heat treatment apparatus  100 ; an alignment part  230  for positioning an untreated semiconductor wafer W; two cooling parts  130  and  140  for cooling semiconductor wafers W subjected to the heating treatment; a heat treatment part  160  for performing flash heating treatment on a semiconductor wafer W; and a transport robot  150  for transferring a semiconductor wafer W to and from the cooling parts  130  and  140  and the heat treatment part  160 . The heat treatment apparatus  100  further includes a controller  3  for controlling operating mechanisms provided in the aforementioned processing parts and the transport robot  150  to cause the flash heating treatment of the semiconductor wafer W to proceed. 
     The indexer part  101  includes: a load port  110  for placing thereon a plurality of (in this preferred embodiment, two) carriers (or cassettes) C arranged in juxtaposition; and a transfer robot  120  for taking an untreated semiconductor wafer W out of each of the carriers C and for storing a treated semiconductor wafer W into each of the carriers C. An unmanned transport vehicle (an AGV (automatic guided vehicle) or an OHT (overhead hoist transfer)) or the like transports a carrier C with untreated semiconductor wafers W stored therein to place the carrier C on the load port  110 , and carries a carrier C with treated semiconductor wafers W stored therein away from the load port  110 . 
     In the load port  110 , the carriers C are movable upwardly and downwardly as indicated by an arrow CU in  FIG. 2  so that the transfer robot  120  is able to load any semiconductor wafer W into each carrier C and unload any semiconductor wafer W from each carrier C. The carriers C may be of the following types: an SMIF (standard mechanical interface) pod and an OC (open cassette) which exposes stored semiconductor wafer W to the outside atmosphere, in addition to a FOUP (front opening unified pod) which stores semiconductor wafer Win an enclosed or sealed space. 
     The transfer robot  120  is slidable as indicated by an arrow  120 S in  FIG. 1 , pivotable as indicated by an arrow  120 R in  FIG. 1 , and movable upwardly and downwardly. Thus, the transfer robot  120  loads and unloads semiconductor wafers W into and from the two carriers C, and transfers semiconductor wafers W to and from the alignment part  230  and the two cooling parts  130  and  140 . The operation of the transfer robot  120  loading and unloading the semiconductor wafers W into and from the carriers C is achieved by the sliding movement of a hand  121  of the transfer robot  120  and the upward and downward movement of the carriers C. The transfer of the semiconductor wafers W between the transfer robot  120  and the alignment part  230  or between the transfer robot  120  and the cooling parts  130  and  140  is achieved by the sliding movement of the hand  121  and the upward and downward movement of the transfer robot  120 . 
     The alignment part  230  is provided on and connected to one side of the indexer part  101  in adjacent relation thereto along the Y axis. The alignment part  230  is a processing part for rotating a semiconductor wafer W in a horizontal plane to an orientation appropriate for flash heating. The alignment part  230  includes an alignment chamber  231  which is a housing made of an aluminum alloy, a mechanism provided in the alignment chamber  231  and for supporting and rotating a semiconductor wafer W in a horizontal attitude, a mechanism provided in the alignment chamber  231  and for optically detecting a notch, an orientation flat, and the like formed in a peripheral portion of a semiconductor wafer W, and the like. 
     The transfer robot  120  transfers a semiconductor wafer W to and from the alignment part  230 . The semiconductor wafer W with the center thereof in a predetermined position is transferred from the transfer robot  120  to the alignment chamber  231 . The alignment part  230  rotates the semiconductor wafer W received from the indexer part  101  about a vertical axis passing through the central portion of the semiconductor wafer W to optically detect a notch and the like, thereby adjusting the orientation of the semiconductor wafer W. The semiconductor wafer W subjected to the orientation adjustment is taken out of the alignment chamber  231  by the transfer robot  120 . 
     A transport chamber  170  for housing the transport robot  150  therein is provided as space for transport of the semiconductor wafer W by means of the transport robot  150 . A treatment chamber  6  in the heat treatment part  160 , a first cool chamber  131  in the cooling part  130 , and a second cool chamber  141  in the cooling part  140  are connected in. communication with three sides of the transport chamber  170 . 
     The heat treatment part  160  which is a principal part of the heat treatment apparatus  100  is a substrate processing part for irradiating a preheated semiconductor wafer W with flashes of light from xenon flash lamps FL to perform flash heating treatment on the semiconductor wafer W. The configuration of the heat treatment part  160  will be described later in detail. 
     The two cooling parts  130  and  140  are substantially similar in configuration each other. The cooling parts  130  and  140  include respective metal cooling plates and respective quartz plates (both not shown) placed on the upper surfaces of the cooling plates in the first and second cool chambers  131  and  141  which are housings made of art aluminum alloy. Each of the cooling plates is temperature-controlled at ordinary temperatures (approximately 23° C.) by a Peltier element or by circulation of constant-temperature water. The semiconductor wafer W subjected to the flash heating treatment in the heat treatment part  160  is transported into the first cool chamber  131  or the second cool chamber  141 , and is then placed and cooled on a corresponding one of the quartz plates. 
     The first cool chamber  131  and the second cool chamber  141  provided between the indexer part  101  and the transport chamber  170  are connected to both the indexer part  101  and the transport chamber  170 . Each of the first cool chamber  131  and the second cool chamber  141  has two openings for transporting the semiconductor wafer W thereinto and therefrom. One of the two openings of the first cool chamber  131  which is connected to the indexer part  101  is openable and closable by a gate valve  181 . The other opening of the first cool chamber  131  which is connected to the transport chamber  170  is openable and closable by a gate valve  183 . In other words, the first cool chamber  131  and the indexer part  101  are connected to each other through the gate valve  181 , and the first cool chamber  131  and the transport chamber  170  are connected to each other through the gate valve  183 . 
     The gate valve  181  is opened when the semiconductor wafer W is transferred between the indexer part  101  and the first cool chamber  131 . The gate valve  183  is opened when the semiconductor wafer W is transferred between the first cool chamber  131  and the transport chamber  170 . When the gate valve  181  and the gate valve  183  are closed, the interior of the first cool chamber  131  is an enclosed space. 
     One of the two openings of the second cool chamber  141  which is connected to the indexer part  101  is openable and closable by a gate valve  182 . The other opening of the second cool chamber  141  which is connected to the transport chamber  170  is openable and closable by a gate valve  184 . In other words, the second cool chamber  141  and the indexer part  101  are connected to each other through the gate valve  182 , and the second cool chamber  141  and the transport chamber  170  are connected to each other through the gate valve  184 . 
     The gate valve  182  is opened when the semiconductor wafer W is transferred between the indexer part  101  and the second cool chamber  141 . The gate valve  184  is opened when the semiconductor wafer W is transferred between the second cool chamber  141  and the transport chamber  170 . When the gate valve  182  and the gate valve  184  are closed, the interior of the second cool chamber  141  is an enclosed space. 
     The cooling parts  130  and  140  further include respective gas supply mechanisms for supplying clean nitrogen gas to the first and second cool chambers  131  and  141  and respective exhaust mechanisms for exhausting atmospheres from the first and second cool chambers  131  and  141 . The gas supply mechanisms and the exhaust mechanisms may be capable of changing the flow rates thereof in two levels. 
     The transport robot  150  provided in the transport chamber  170  is pivotable about a vertical axis as indicated by an arrow  150 R. The transport robot  150  includes two linkage mechanisms comprised of a plurality of arm segments. Transport hands  151   a  and  151   b  each for holding a semiconductor wafer W are provided at respective distal ends of the two linkage mechanisms. These transport hands  151   a  and  151   b  are vertically spaced a predetermined distance apart from each other, and are independently linearly slidable in the same horizontal direction by the respective linkage mechanisms. The transport robot  150  moves a base provided with the two linkage mechanisms upwardly and downwardly to thereby move the two transport hands  151   a  and  151   b  spaced the predetermined distance apart from each other upwardly and downwardly. 
     When the transport robot  150  transfers (loads and unloads) a semiconductor wafer W to and from the first cool chamber  131 , the second cool chamber  141 , or the treatment chamber  6  in the heat treatment part  160  as a transfer target, both of the transport hands  151   a  and  151   b  pivot into opposed relation to the transfer target, and move upwardly or downwardly after (or during) the pivotal movement, so that one of the transport hands  151   a  and  151   b  reaches a vertical position at which the semiconductor wafer W is to be transferred to and from the transfer target. Then, the transport robot  150  causes the transport hand  151   a  (or  151   b ) to linearly slide in a horizontal direction, thereby transferring the semiconductor wafer W to and from the transfer target. 
     The transfer of a semiconductor wafer W between the transport robot  150  and the transfer robot  120  is performed through the cooling parts  130  and  140 . That is, the first cool chamber  131  in the cooling part  130  and the second cool chamber  141  in the cooling part  140  function also as paths for transferring a semiconductor wafer W between the transport robot  150  and the transfer robot  120 . Specifically, one of the transport robot  150  and the transfer robot  120  transfers a semiconductor wafer W to the first cool chamber  131  or the second cool chamber  141 , and the other of the transport robot  150  and the transfer robot  120  receives the semiconductor wafer W, whereby the transfer of the semiconductor wafer W is performed. The transport robot  150  and the transfer robot  120  constitute a transport mechanism for transporting a semiconductor wafer W from the carriers C to the heat treatment part  160 . 
     As mentioned above, the gate valves  181  and  182  are provided between the indexer part  101  and the first and second cool chambers  131  and  141 , respectively. The gate valves  183  and  184  are provided between the transport chamber  170  and the first and second cool chambers  131  and  141 , respectively. A gate valve  185  is further provided between the transport chamber  170  and the treatment chamber  6  of the heat treatment part  160 . These gate valves  181  to  185  are opened and closed, as appropriate, when the semiconductor wafer W is transported in the heat treatment apparatus  100 . Nitrogen gas is supplied from a gas supply part to the transport chamber  170  and the alignment chamber  231 , and an exhaust part exhausts atmospheres from the transport chamber  170  and the alignment chamber  231  (both not shown). 
     Next, the configuration of the heat treatment part  160  will be described.  FIG. 3  is a longitudinal sectional view showing the configuration of the heat treatment part  160 . The heat treatment part  160  includes the treatment chamber  6  for receiving a semiconductor wafer W therein to perform heating treatment on the semiconductor wafer W, a flash lamp house  5  including the plurality of built-in flash lamps FL, and a halogen lamp house  4  including a plurality of built-in halogen lamps HL. The flash lamp house  5  is provided over the treatment chamber  6 , and the halogen lamp house  4  is provided under the treatment chamber  6 . The heat treatment part  160  further includes a holder  7  provided inside the treatment chamber  6  and for holding a semiconductor wafer W in a horizontal attitude, and a transfer mechanism  10  provided inside the treatment chamber  6  and for transferring a semiconductor wafer W between the holder  7  and the transport robot  150 . 
     The treatment chamber  6  is configured such that upper and lower chamber windows  63  and  64  made of quartz are mounted to the top and bottom, respectively, of a tubular chamber side portion  61 . The chamber side portion  61  has a generally tubular shape having an open top and an open bottom. The upper chamber window  63  is mounted to block the top opening of the chamber side portion  61 , and the lower chamber window  64  is mounted to block the bottom opening thereof. The upper chamber window  63  forming the ceiling of the treatment chamber  6  is a disk-shaped member made of quartz, and serves as a quartz window that transmits flashes of light emitted from the flash lamps FL therethrough into the treatment chamber  6 . The lower chamber window  64  forming the floor of the treatment chamber  6  is also a disk-shaped member made of quartz, and serves as a quartz window that transmits light emitted from the halogen lamps HL therethrough into the treatment chamber  6 . 
     An upper reflective ring  68  is mounted to an upper portion of the inner wall surface of the chamber side portion  61 , and a lower reflective ring  69  is mounted to a lower portion thereof. Both of the upper and lower reflective rings  68  and  69  are in the form of an annular ring. The upper reflective ring  68  is mounted by being inserted downwardly from the top of the chamber side portion  61 . The lower reflective ring  69 , on the other hand, is mounted by being inserted upwardly from the bottom of the chamber side portion  61  and fastened with screws not shown. In other words, the upper and lower reflective rings  68  and  69  are removably mounted to the chamber side portion  61 . An interior space of the treatment chamber  6 , i.e. a space surrounded by the upper chamber window  63 , the lower chamber window  64 , the chamber side portion  61 , and the upper and lower reflective rings  68  and  69 , is defined as a heat treatment space  65 . 
     A recessed portion  62  is defined in the inner wall surface of the treatment chamber  6  by mounting the upper and lower reflective rings  68  and  69  to the chamber side portion  61 . Specifically, the recessed portion  62  is defined which is surrounded by a middle portion of the inner wall surface of the chamber side portion  61  where the reflective rings  68  and  69  are not mounted, a lower end surface of the upper reflective ring  68 , and an upper end surface of the lower reflective ring  69 . The recessed portion  62  is provided in the form of a horizontal annular ring in the inner wall surface of the treatment chamber  6 , and surrounds the holder  7  which holds a semiconductor wafer W. The chamber side portion  61  and the upper and lower reflective rings  68  and  69  are made of a metal material (e.g., stainless steel) with high strength and high heat resistance. 
     The chamber side portion  61  is provided with a transport opening (throat)  66  for the transport of a semiconductor wafer W therethrough into and out of the treatment chamber  6 . The transport opening  66  is openable and closable by the gate valve  185 . The transport opening  66  is connected in communication with an cuter peripheral surface of the recessed portion  62 . Thus, when the transport opening  66  is opened by the gate valve  185 , a semiconductor wafer W is allowed to be transported through the transport opening  66  and the recessed portion  62  into and out of the heat treatment space  65 . When the transport opening  66  is closed by the gate valve  185 , the heat treatment space  65  in the treatment chamber  6  is an enclosed space. 
     At least one gas supply opening  81  for supplying a treatment gas therethrough into the heat treatment space  65  is provided in an upper portion of the inner wall of the treatment chamber  6 . The gas supply opening  81  is provided above the recessed portion  62 , and may be provided in the upper reflective ring  68 . The gas supply opening  81  is connected in communication with a gas supply pipe  83  through a buffer space  82  provided in the form of an annular ring inside the side wall of the treatment chamber  6 . The gas supply pipe  83  is connected to a treatment gas supply source  85 . A valve  84  is inserted at some midpoint in the gas supply pipe  83 . When the valve  84  is opened, the treatment gas is fed from the treatment gas supply source  85  to the buffer space  82 . The treatment gas flowing in the buffer space  82  flows in a spreading manner within the buffer space  82  which is lower in fluid resistance than the gas supply opening  81 , and is supplied through the gas supply opening  81  into the heat treatment space  65 . Examples of the treatment gas usable herein include inert gases such as nitrogen gas (N 2 ), and reactive gases such as hydrogen (H 2 ) and ammonia (NH 3 ) (although nitrogen is used in the present preferred embodiment). 
     At least one gas exhaust opening  86  for exhausting a gas from the heat treatment space  65  is provided in a lower portion of the inner wall of the treatment chamber  6 . The gas exhaust opening  86  is provided below the recessed portion  62 , and may be provided in the lower reflective ring  69 . The gas exhaust opening  86  is connected in communication with a gas exhaust pipe  88  through a buffer space  87  provided in the form of an annular ring inside the side wall of the treatment chamber  6 . The gas exhaust pipe  88  is connected to an exhaust mechanism  190 . A valve  89  is inserted at some midpoint in the gas exhaust pipe  88 . When the valve  89  is opened, the gas in the heat treatment space  65  is exhausted through the gas exhaust opening  86  and the buffer space  87  to the gas exhaust pipe  88 . The at least one gas supply opening  81  and the at least one gas exhaust opening  86  may include a plurality of gas supply openings  81  and a plurality of gas exhaust openings  86 , respectively, arranged in a circumferential direction of the treatment chamber  6 , and may be in the form of slits. The treatment gas supply source  85  and the exhaust mechanism  190  may be mechanisms provided in the heat treatment apparatus  100  or be utility systems in a factory in which the heat treatment apparatus  100  is installed. 
     A gas exhaust pipe  191  for exhausting the gas from the heat treatment space  65  is also connected to a distal end of the transport opening  66 . The gas exhaust pipe  191  is connected through a valve  192  to the exhaust mechanism  190 . By opening the valve  192 , the gas in the treatment chamber  6  is exhausted through the transport opening  66 . 
       FIG. 4  is a perspective view showing the entire external appearance of the holder  7 . The holder  7  includes a base ring  71 , coupling portions  72 , and a susceptor  74 . The base ring  71 , the coupling portions  72 , and the susceptor  74  are all made of quartz. In other words, the whole of the holder  7  is made of quartz. 
     The base ring  71  is a quartz member having an arcuate shape obtained by removing a portion from an annular shape. This removed portion is provided to prevent interference between transfer arms  11  of the transfer mechanism  10  to be described later and the base ring  71 . The base ring  71  is supported by the wall surface of the treatment chamber  6  by being placed on the bottom surface of the recessed portion  62  (with reference to  FIG. 3 ). The multiple coupling portions  72  (in the present preferred embodiment, four coupling portions  72 ) are mounted upright on the upper surface of the base ring  71  and arranged in a circumferential direction of the annular shape thereof. The coupling portions  72  are quartz members, and are rigidly secured to the base ring  71  by welding. 
     The susceptor  74  is supported by the four coupling portions  72  provided on the base ring  71 .  FIG. 5  is a plan view of the susceptor  74 .  FIG. 6  is a sectional view of the susceptor  74 . The susceptor  74  includes a holding plate  75 , a guide ring  76 , and a plurality of substrate support pins  77 . The holding plate  75  is a generally circular planar member made of quartz. The diameter of the holding plate  75  is greater than that of a semiconductor wafer W. In other words, the holding plate  75  has a size, as seen in plan view, greater than that of the semiconductor wafer W. 
     The guide ring  76  is provided on a peripheral portion of the upper surface of the holding plate  75 . The guide ring  76  is an annular member having an inner diameter greater than the diameter of the semiconductor wafer W. For example, when the diameter of the semiconductor wafer W is 300 mm, the inner diameter of the guide ring  76  is 320 mm. The inner periphery of the guide ring  76  is in the form of a tapered surface which becomes wider in an upward direction from the holding plate  75 . The guide ring  76  is made of quartz similar to that of the holding plate  75 . The guide ring  76  may be welded to the upper surface of the holding plate  75  or fixed to the holding plate  75  with separately machined pins and the like. Alternatively, the holding plate  75  and the guide ring  76  may be machined as an integral member. 
     A region of the upper surface of the holding plate  75  which is inside the guide ring  76  serves as a planar holding surface  75   a  for holding the semiconductor wafer W. The substrate support pins  77  are provided upright on the holding surface  75   a  of the holding plate  75 . In the present preferred embodiment, a total of 12 substrate support pins  77  are spaced at intervals of 30 degrees along the circumference of a circle concentric with the outer circumference of the holding surface  75   a  (the inner circumference of the guide ring  76 ). The diameter of the circle on which the 12 substrate support pins  77  are disposed (the distance between opposed ones of the substrate support pins  77 ) is smaller than the diameter of the semiconductor wafer W, and is 270 to 280 mm (in the present preferred embodiment, 270 mm) when the diameter of the semiconductor wafer W is 300 mm. Each of the substrate support pins  77  is made of quartz. The substrate support pins  77  may be provided by welding on the upper surface of the holding plate  75  or machined integrally with the holding plate  75 . 
     Referring again to  FIG. 4 , the four coupling portions  72  provided upright on the base ring  71  and the peripheral portion of the holding plate  75  of the susceptor  74  are rigidly secured to each other by welding. In other words, the susceptor  74  and the base ring  71  are fixedly coupled to each other with the coupling portions  72 . The base ring  71  of such a holder  7  is supported by the wall surface of the treatment chamber  6 , whereby the holder  7  is mounted to the treatment chamber  6 . With the holder  7  mounted to the treatment chamber  6 , the holding plate  75  of the susceptor  74  assumes a horizontal attitude (an attitude such that the normal to the holding plate  75  coincides with a vertical direction). In other words, the holding surface  75   a  of the holding plate  75  becomes a horizontal surface. 
     A semiconductor wafer W transported into the treatment chamber  6  is placed and held in a horizontal attitude on the susceptor  74  of the holder  7  mounted to the treatment chamber  6 . At this time, the semiconductor wafer W is supported by the 12 substrate support pins  77  provided upright on the holding plate  75 , and is held by the susceptor  74 . More strictly speaking, the 12 substrate support pins  77  have respective upper end portions coming in contact with the lower surface of the semiconductor wafer W to support the semiconductor wafer W. The semiconductor wafer W is supported in a horizontal attitude by the 12 substrate support pins  77  because the 12 substrate support pins  77  have a uniform height (distance from the upper ends of the substrate support pins  77  to the holding surface  75   a  of the holding plate  75 ). 
     The semiconductor wafer W supported by the substrate support pins  77  is spaced a predetermined distance apart from the holding surface  75   a  of the holding plate  75 . The thickness of the guide ring  76  is greater than the height of the substrate support pins  77 . Thus, the guide ring  76  prevents the horizontal misregistration of the semiconductor wafer W supported by the substrate support pins  77 . 
     As shown in  FIGS. 4 and 5 , an opening  78  is provided in the holding plate  75  of the susceptor  74  so as to extend vertically through the holding plate  75  of the susceptor  74 . The opening  78  is provided for a radiation thermometer  20  (with reference to  FIG. 3 ) to receive radiation (infrared radiation) emitted from the lower surface of the semiconductor wafer W held by the susceptor  74 . Specifically, the radiation thermometer  20  receives the radiation emitted from the lower surface of the semiconductor wafer W held by the susceptor  74  through the opening  78  to measure the temperature of the semiconductor wafer W. Further, the holding plate  75  of the susceptor  74  further includes four through holes  79  bored therein and designed so that lift pins  12  of the transfer mechanism  10  to be described later pass through the through holes  79 , respectively, to transfer a semiconductor wafer W. 
       FIG. 7  is a plan view of the transfer mechanism  10 .  FIG. 8  is a side view of the transfer mechanism  10 . The transfer mechanism  10  includes the two transfer arms  11 . The transfer arms  11  are of an arcuate configuration extending substantially along the annular recessed portion  62 . Each of the transfer arms  11  includes the two lift pins  12  mounted upright thereon. The transfer arms  11  are pivotable by a horizontal movement mechanism  13 . The horizontal movement mechanism  13  moves the pair of transfer arms  11  horizontally between a transfer operation position (a position indicated by solid lines in  FIG. 7 ) in which a semiconductor wafer W is transferred to and from the holder  7  and a retracted position (a position indicated by dash-double-dot lines in  FIG. 7 ) in which the transfer arms  11  do not overlap the semiconductor wafer W held by the holder  7  as seen in plan view. The transfer operation position is under the susceptor  74 , and the retracted position is outside the susceptor  74 . The horizontal movement mechanism  13  may be of the type which causes individual motors to pivot the transfer arms  11  respectively or of the type which uses a linkage mechanism to cause a single motor to pivot the pair of transfer arms  11  in cooperative relation. 
     The transfer arms  11  are moved upwardly and downwardly together with the horizontal movement mechanism  13  by an elevating mechanism  14 . As the elevating mechanism  14  moves up the pair of transfer arms  11  in their transfer operation position, the four lift pins  12  in total pass through the respective four through holes  79  (with reference to  FIGS. 4 and 5 ) bored in the susceptor  74 , so that the upper ends of the lift pins  12  protrude from the upper surface of the susceptor  74 . On the other hand, as the elevating mechanism  14  moves down the pair of transfer arms  11  in their transfer operation position to take the lift pins  12  out of the respective through holes  79  and the horizontal movement mechanism  13  moves the pair of transfer arms  11  so as to open the transfer arms  11 , the transfer arms  11  move to their retracted position. The retracted position of the pair of transfer arms  11  is immediately over the base ring  71  of the holder  7 . The retracted position of the transfer arms  11  is inside the recessed portion  62  because the base ring  71  is placed on the bottom surface of the recessed portion  62 . An exhaust mechanism not shown is also provided near the location where the drivers (the horizontal movement mechanism  13  and the elevating mechanism  14 ) of the transfer mechanism  10  are provided, and is configured to exhaust an atmosphere around the drivers of the transfer mechanism  10  to the outside of the treatment chamber  6 . 
     Referring again to  FIG. 3 , the flash lamp house  5  provided over the treatment chamber  6  includes an enclosure  51 , a light source provided inside the enclosure  51  and including the multiple (in the present preferred embodiment, 30) xenon flash lamps FL, and a reflector  52  provided inside the enclosure  51  so as to cover the light source from above. The flash lamp house  5  further includes a lamp light radiation window  53  mounted to the bottom of the enclosure  51 . The lamp light radiation window  53  forming the floor of the flash lamp house  5  is a plate-like quartz window made of quartz. The flash lamp house  5  is provided over the treatment chamber  6 , whereby the lamp light radiation window  53  is opposed to the upper chamber window  63 . The flash lamps FL direct flashes of light from over the treatment chamber  6  through the lamp light radiation window  53  and the upper chamber window  63  toward the heat treatment space  65 . 
     The flash lamps FL, each of which is a rod-shaped lamp having an elongated cylindrical shape, are arranged in a plane so that the longitudinal directions of the respective flash lamps FL are in parallel with each other along a main surface of a semiconductor wafer W held by the holder  7  (that is, in a horizontal direction). Thus, a plane defined by the arrangement of the flash lamps FL is also a horizontal plane. 
     Each of the xenon flash lamps FL includes a rod-shaped glass tube (discharge tube) containing xenon gas sealed therein and having positive and negative electrodes provided on opposite ends thereof and connected to a capacitor, and a trigger electrode attached to the outer peripheral surface of the glass tube. Because the xenon gas is electrically insulative, no current flows in the glass tube in a normal state even if electrical charge is stored in the capacitor. However, if a high voltage is applied to the trigger electrode to produce an electrical breakdown, electricity stored in the capacitor flows momentarily in the glass tube, and xenon atoms or molecules are excited at this time to cause light emission. Such a xenon flash lamp FL has the property of being capable of emitting extremely intense light as compared with a light source that stays lit continuously such as a halogen lamp HL because the electrostatic energy previously stored in the capacitor is converted into an ultrashort light pulse ranging from 0.1 to 100 milliseconds. Thus, the flash lamps FL are pulsed light emitting lamps which emit light instantaneously for an extremely short time period of less than one second. The light emission time period of the flash lamps FL is adjustable by the oil constant of a lamp light source which supplies power to the flash lamps FL. 
     The reflector  52  is provided over the plurality of flash lamps FL so as to cover all of the flash lamps FL. A fundamental function of the reflector  52  is to reflect flashes of light emitted from the plurality of flash lamps FL toward the heat treatment space  65 . The reflector  52  is a plate made of an aluminum alloy. A surface of the reflector  52  (a surface which faces the flash lamps FL) is roughened by abrasive blasting. 
     The halogen lamp house  4  provided under the treatment chamber  6  includes an enclosure  41  incorporating the multiple (in the present preferred embodiment, 40) halogen lamps HL. The halogen lamps HL direct light from under the treatment chamber  6  through the lower chamber window  64  toward the heat treatment space  65 . 
       FIG. 9  is a plan view showing an arrangement of the multiple halogen lamps HL. In the present preferred embodiment, 20 halogen lamps HL are arranged in each of two tiers, i.e. upper and lower tiers. Each of the halogen lamps HL is a rod-shaped lamp having an elongated cylindrical shape. The 20 halogen lamps HL in each of the upper and lower tiers are arranged so that the longitudinal directions thereof are in parallel with each other along a main surface of a semiconductor wafer W held by the holder  7  (that is, in a horizontal direction). Thus, a plane defined by the arrangement of the halogen lamps HL in each of the upper and lower tiers is also a horizontal plane. 
     As shown in  FIG. 9 , the halogen lamps HL in each of the upper and lower tiers are disposed at a higher density in a region opposed to the peripheral portion of the semiconductor wafer W held by the holder  7  than in a region opposed to the central portion thereof. In other words, the halogen lamps HL in each of the upper and lower tiers are arranged at shorter intervals in the peripheral portion of the lamp arrangement than in the central portion thereof. This allows a greater amount of light to impinge upon the peripheral portion of the semiconductor wafer W where a temperature decrease is prone to occur when the semiconductor wafer W is heated by the irradiation thereof with light from the halogen lamps HL. 
     The group of halogen lamps HL in the upper tier and the group of halogen lamps HL in the lower tier are arranged to intersect each other in a lattice pattern. In other words, the 40 halogen lamps HL in total are disposed so that the longitudinal direction of each of the halogen lamps HL arranged in the upper tier and the longitudinal direction of each of the halogen lamps HL arranged in the lower tier are orthogonal to each other. 
     Each of the halogen lamps HL is a filament-type light source which passes current through a filament disposed in a glass tube to make the filament incandescent, thereby emitting light. A gas prepared by introducing a halogen element (iodine, bromine and the like) in trace amounts into an inert gas such as nitrogen, argon and the like is sealed in the glass tube. The introduction of the halogen element allows the temperature of the filament to be set at a high temperature while suppressing a break in the filament. Thus, the halogen lamps HL have the properties of having a longer life than typical incandescent lamps and being capable of continuously emitting intense light. That is, the halogen lamps HL are continuous lighting lamps that emit light continuously for not less than one second. In addition, the halogen lamps HL, which are rod-shaped lamps, have a long life. The arrangement of the halogen lamps HL in a horizontal direction provides good efficiency of radiation toward the semiconductor wafer W provided over the halogen lamps HL. 
     A reflector  43  is provided also inside the enclosure  41  of the halogen lamp house  4  under halogen lamps HL arranged in two tiers ( FIG. 3 ). The reflector  43  reflects the light emitted from the halogen lamps HL toward the heat treatment space  65 . 
     The controller  3  controls the aforementioned various operating mechanisms provided in the heat treatment apparatus  100 .  FIG. 10  is a block diagram showing a configuration of the controller  3 . The controller  3  is similar in hardware configuration to a typical computer. Specifically, the controller  3  includes a CPU that is a circuit for performing various computation processes, a ROM or read-only memory for storing a basic program therein, a RAM or readable/writable memory for storing various pieces of information therein, and a magnetic disk  35  for storing control software, data and the like thereon. The CPU in the controller  3  executes a predetermined processing program, whereby the processes in the heat treatment apparatus  100  proceed. For example, the controller  3  controls a transport mechanism  38  including the transport robot  150  and the transfer robot  120  to cause the transport mechanism  38  to transport the semiconductor wafer W along an established transport path. The controller  3  is shown in the indexer part  101  in  FIG. 1 . The present invention, however, is not limited to this. The controller  3  may he disposed in any position in the heat treatment apparatus  100 . 
     As shown in  FIG. 10 , the controller  3  includes a calculation part  31  and an alarm issuing part  32 . The calculation part  31  and the alarm issuing part  32  are functional processing parts implemented by the CPU of the controller  3  executing a predetermined processing program. The details of the processing in the calculation part  31  and the alarm issuing, part  32  will be further described later. 
     The controller  3  is connected to a display part  34  and an input part  33 . The controller  3  causes a variety of pieces of information to appear on the display part  34 . An operator of the heat treatment apparatus  100  may input various commands and parameters from the input part  33  while viewing the information appearing on the display part  34 . A keyboard and a mouse, for example, may be used as the input part  33 . A liquid crystal display, for example, may be used as the display part  34 . In the present preferred embodiment, a liquid crystal touch panel provided on an outer wall of the heat treatment apparatus  100  is used to function as both the display part  34  and the input part  33 . 
     The heat treatment part  160  further includes, in addition to the aforementioned components, various cooling structures to prevent an excessive temperature rise in the halogen lamp house  4 , the flash lamp house  5 , and the treatment chamber  6  because of the heat energy generated from the halogen lamps HL and the flash lamps FL during the heat treatment of a semiconductor wafer W. As an example, a water cooling tube (not shown) is provided in the walls of the treatment chamber  6 . Also, the halogen lamp house  4  and the flash lamp house  5  have an air cooling structure for forming a gas flow therein to exhaust heat. Air is supplied to a gap between the upper chamber window  63  and the lamp light radiation window  53  to cool down the flash lamp house  5  and the upper chamber window  63 . 
     Next, a treatment operation in the heat treatment apparatus  100  according to the present invention will be described. The treatment operation for an ordinary semiconductor wafer W will be described first, and the management of a dummy wafer will be thereafter described. A semiconductor wafer W to be treated herein is a semiconductor substrate doped with impurities (ions) by an ion implantation process. The impurities are activated by the heat treatment apparatus  100  performing the process of heating (annealing) the semiconductor wafer W by means of flash irradiation. 
     First, while being stored in a carrier C, untreated semiconductor wafers W implanted with impurities are placed on the load port  110  of the indexer part  101 . The transfer robot  120  takes the untreated semiconductor wafers W one by one out of the carrier C to transport each of the untreated semiconductor wafers W into the alignment chamber  231  of the alignment part  230 . In the alignment chamber  231 , a semiconductor wafer W is rotated in a horizontal plane about a vertical axis passing through the central portion of the semiconductor wafer W, and a notch or the like is optically detected, whereby the orientation of the semiconductor wafer W is adjusted. 
     Next, the transfer robot  120  of the indexer part  101  takes the orientation-adjusted semiconductor wafer W out of the alignment chamber  231  to transport the semiconductor wafer W into the first cool chamber  131  of the cooling part  130  or the second cool chamber  141  of the cooling part  140 . The untreated semiconductor wafer W transported into the first cool chamber  131  or the second cool chamber  141  is transported to the transport chamber  170  by the transport robot  150 . The first cool chamber  131  and the second cool chamber  141  function as the paths for transferring the semiconductor wafer W when the untreated semiconductor wafer W is transferred from the indexer part  101  via the first cool chamber  131  or the second cool chamber  141  to the transport chamber  170 . 
     After taking out the semiconductor wafer W, the transport robot  150  pivots so as to face toward the heat treatment part  160 . Subsequently, the gate valve  185  opens the space between the treatment chamber  6  and the transport chamber  170 , and the transport robot  150  transports the untreated semiconductor wafer W into the treatment chamber  6 . At this time, if a preceding semiconductor wafer W subjected to the heating treatment is present in the treatment chamber  6 , the untreated semiconductor wafer W is transported into the treatment chamber  6  after one of the transport hands  151   a  and  151   b  takes out the semiconductor wafer W subjected to the heating treatment. In this manner, the semiconductor wafers W are interchanged. Thereafter, the gate valve  185  closes the space between the treatment chamber  6  and the transport chamber  170 . 
     The semiconductor wafer W transported into the treatment chamber  6  is preheated by the halogen lamps HL, and is thereafter subjected to the flash heating treatment by flash irradiation from the flash lamps FL. This flash heating treatment activates the impurities implanted in the semiconductor wafer W. 
     After the completion of the flash heating treatment, the gate valve  185  opens the space between the treatment chamber  6  and the transport chamber  170  again, and the transport robot  150  transports the semiconductor wafer W subjected to the flash heating treatment from the treatment chamber  6  to the transport chamber  170 . After taking out the semiconductor wafer W, the transport robot  150  pivots from the treatment chamber  6  so as to face toward the first cool chamber  3  or the second cool chamber  141 . The gate valve  185  closes the space between the treatment chamber  6  and the transport chamber  170 . 
     Thereafter, the transport robot  150  transports the semiconductor wafer W subjected to the heating treatment into the first cool chamber  131  of the cooling part  130  or the second cool chamber  141  of the cooling part  140 . At this time, the semiconductor wafer W that has passed through the first cool chamber  131  before the heating treatment is also transported into the first cool chamber  131  after the heating treatment, and the semiconductor wafer W that has passed through the second cool chamber  141  before the heating treatment is also transported into the second cool chamber  141  after the heating treatment. In the first cool chamber  131  or the second cool chamber  141 , the semiconductor wafer W subjected to the flash heating treatment is cooled. The semiconductor wafer W is cooled to near ordinary temperatures in the first cool chamber  131  or the second cool chamber  141  because the temperature of the entire semiconductor wafer W is relatively high when the semiconductor wafer W is transported out of the treatment chamber  6  of the heat treatment part  160 . 
     After a lapse of a predetermined cooling time period, the transfer robot  120  transports the cooled semiconductor wafer W out of the first cool chamber  131  or the second cool chamber  141 , and returns the cooled semiconductor wafer W back to the carrier C. After a predetermined number of treated semiconductor wafers W are stored in the carrier C, the carrier C is transported from the load port  110  of the indexer part  101  to the outside. 
     The description on the heating treatment in the heat treatment part  160  will be continued. Prior to the transport of the semiconductor wafer W into the treatment chamber  6 , the valve  84  is opened for supply of gas, and the valves  89  and  192  for exhaust of gas are opened, so that the supply and exhaust of gas into and out of the treatment chamber  6  start. When the valve  84  is opened, nitrogen gas is supplied through the gas supply opening  81  into the heat treatment space  65 . When the valve  89  is opened, the gas within the treatment chamber  6  is exhausted through the gas exhaust opening  86 . This causes the nitrogen gas supplied from an upper portion of the heat treatment space  65  in the treatment chamber  6  to flow downwardly and then to be exhausted from a lower portion of the heat treatment space  65 . 
     The gas within the treatment chamber  6  is exhausted also through the transport opening  66  by opening the valve  192 . Further, the exhaust mechanism not shown exhausts an atmosphere near the drivers of the transfer mechanism  10 . It should be noted that the nitrogen gas is continuously supplied into the heat treatment space  65  during the heat treatment of a semiconductor wafer W in the heat treatment part  160 . The amount of nitrogen gas supplied into the heat treatment space  65  is changed as appropriate in accordance with process steps. 
     Subsequently, the gate valve  185  is opened to open the transport opening  66 . The transport robot  150  transports a semiconductor wafer W to be treated through the transport opening  66  into the heat treatment space  65  of the treatment chamber  6 . The transport robot  150  moves the transport hand  151   a  (or the transport hand  151   b ) holding the untreated semiconductor wafer W forward to a position lying immediately over the holder  7 , and stops the transport hand  151   a  (or the transport hand  151   b ) thereat. Then, the pair of transfer arms  11  of the transfer mechanism  10  is moved horizontally from the retracted position to the transfer operation position and is then moved upwardly, whereby the lift pins  12  pass through the through holes  79  and protrude from the upper surface of the holding plate  75  of the susceptor  74  to receive the semiconductor wafer W. At this time, the lift pins  12  move upwardly to above the upper ends of the substrate support pins  77 . 
     After the untreated semiconductor wafer W is placed on the lift pins  12 , the transport robot  150  causes the transport hand  151   a  to move out of the heat treatment space  65 , and the gate valve  185  closes the transport opening  66 . Then, the pair of transfer arms  11  moves downwardly to transfer the semiconductor wafer W from the transfer mechanism  10  to the susceptor  74  of the holder  7 , so that the semiconductor wafer W is held in a horizontal attitude from below. The semiconductor wafer W is supported by the substrate support pins  77  provided upright on the holding plate  75 , and is held by the susceptor  74 . The semiconductor wafer W is held by the holder  7  in such an attitude that the front surface thereof patterned and implanted with impurities is the upper surface. A predetermined distance is defined between the hack surface (a main surface opposite from the front surface) of the semiconductor wafer W supported by the substrate support pins  77  and the holding surface  75   a  of the holding plate  75 . The pair of transfer arms  11  moved downwardly below the susceptor  74  is moved back to the retracted position, i.e. to the inside of the recessed portion  62 , by the horizontal movement mechanism  13 . 
     After the semiconductor wafer W is held from below in a horizontal attitude by the susceptor  74  of the holder  7 , the 40 halogen lamps HL turn on simultaneously to start preheating (or assist-heating). Halogen light emitted from the halogen lamps HL is transmitted through the lower chamber window  64  and the susceptor  74  both made of quartz, and impinges upon the lower surface of the semiconductor wafer W. By receiving light irradiation from the halogen lamps HL, the semiconductor wafer W is preheated, so that the temperature of the semiconductor wafer W increases. It should be noted that the transfer arms  11  of the transfer mechanism  10 , which are retracted to the inside of the recessed portion  62 , do not become an obstacle to the heating using the halogen lamps HL. 
     The temperature of the semiconductor wafer W is measured with the radiation thermometer  20  when the halogen lamps HL perform the preheating. Specifically, the radiation thermometer  20  receives infrared radiation emitted from the lower surface of the semiconductor wafer W held by the susceptor  74  through the opening  78  to measure the temperature of the semiconductor wafer W which is on the increase. The measured temperature of the semiconductor wafer W is transmitted to the controller  3 . The controller  3  controls the output from the halogen lamps HL while monitoring whether the temperature of the semiconductor wafer W which is on the increase by the irradiation with light from the halogen lamps HL reaches a predetermined preheating temperature T 1  or not. In other words, the controller  3  effects feedback control of the output from the halogen lamps HL so that the temperature of the semiconductor wafer W is equal to the preheating temperature T 1 , based on the value measured with the radiation thermometer  20 . The preheating temperature T 1  shall be on the order of 600° to 800° C. (in the present preferred embodiment, 700° C.) at which there is no apprehension that the impurities implanted in the semiconductor wafer W are diffused by heat. 
     After the temperature of the semiconductor wafer W reaches the preheating temperature T 1 , the controller  3  maintains the temperature of the semiconductor wafer W at the preheating temperature T 1  for a short time. Specifically, at the point in time when the temperature of the semiconductor wafer W measured with the radiation thermometer  20  reaches the preheating temperature T 1 , the controller  3  adjusts the output from the halogen lamps HL to maintain the temperature of the semiconductor wafer W at approximately the preheating temperature T 1 . 
     By performing such preheating using the halogen lamps HL, the temperature of the entire semiconductor wafer W is uniformly increased to the preheating temperature T 1 . In the stage of preheating using the halogen lamps HL, the semiconductor wafer W shows a tendency to be lower in temperature in a peripheral portion thereof where heat dissipation is liable to occur than in a central portion thereof. However, the halogen lamps HL in the halogen lamp house  4  are disposed at a higher density in the region opposed to the peripheral portion of the semiconductor wafer W than in the region opposed to the central portion thereof. This causes a greater amount of light to impinge upon the peripheral portion of the semiconductor wafer W where heat dissipation is liable to occur, thereby providing a uniform in-plane temperature distribution of the semiconductor wafer W in the stage of preheating. 
     The flash lamps FL irradiate the front surface of the semiconductor wafer W with a flash of light at the point in time when a predetermined time period has elapsed since the temperature of the semiconductor wafer W reached the preheating temperature T 1 . At this time, part of the flash of light emitted from the flash lamps FL travels directly toward the interior of the treatment chamber  6 . The remainder of the flash of light is reflected once from the reflector  52 , and then travels toward the interior of the treatment chamber  6 . The irradiation of the semiconductor wafer W with such flashes of light achieves the flash heating of the semiconductor wafer W. 
     The flash heating, which is achieved by the emission of a flash of light from the flash lamps FL, is capable of increasing the front surface temperature of the conductor wafer W in a short time. Specifically, the flash of light emitted from the flash lamps FL is an intense flash of light emitted for an extremely short period of time ranging from about 0.1 to about 100 milliseconds as a result of the conversion of the electrostatic energy previously stored. In the capacitor into such an ultrashort light pulse. The front surface temperature of the semiconductor wafer W subjected to the flash heating by the flash irradiation from the flash lamps FL momentarily increases to a treatment temperature T 2  of 1000° C. or higher. After the impurities implanted in the semiconductor wafer W are activated, the front surface temperature of the semiconductor wafer W decreases rapidly. Because of the capability of increasing and decreasing the front surface temperature of the semiconductor wafer W in an extremely short time, the flash heating achieves the activation of the impurities implanted in the semiconductor wafer W while suppressing the diffusion of the impurities due to heat. It should be noted that the time required for the activation of the impurities is extremely short as compared with the time required for the thermal diffusion of the impurities. Thus, the activation is completed in a short time ranging from about 0.1 to about 100 milliseconds during which no diffusion occurs. 
     After a predetermined time period has elapsed since the completion of the flash heating treatment, the halogen lamps HL turn off. This causes the temperature of the semiconductor wafer W to decrease rapidly from the preheating temperature T 1 . The radiation thermometer  20  measures the temperature of the semiconductor wafer W which is on the decrease. The result of measurement is transmitted to the controller  3 . The controller  3  monitors whether the temperature of the semiconductor wafer W is decreased to a predetermined temperature or not, based on the result of measurement with the radiation thermometer  20 . After the temperature of the semiconductor wafer W is decreased to the predetermined temperature or below, the pair of transfer arms  11  of the transfer mechanism  10  is moved horizontally again from the retracted position to the transfer operation position and is then moved upwardly, so that the lift pins  12  protrude from the upper surface of the susceptor  74  to receive the heat-treated semiconductor wafer W from the susceptor  74 . Subsequently, the transport opening  66  which has been closed is opened by the gate valve  185 , and the transport hand  151   b  (or the transport hand  151   a ) of the transport robot  150  transports the treated semiconductor wafer W placed on the lift pins  12  to the outside. The transport robot  150  moves the transport hand  151   b  forward to a position lying immediately under the semiconductor wafer W thrust upwardly by the lift pins  12 , and stops the transport hand  151   b  thereat. Then, the pair of transfer arms  11  of the transfer mechanism  10  moves downwardly, whereby the semiconductor wafer W subjected to the flash heating is transferred to and placed on the transport hand  151   b . Thereafter, the transport robot  150  causes the transport hand  151   b  to move out of the treatment chamber  6 , thereby transporting the treated semiconductor wafer W to the outside. 
     Typically, the treatment of semiconductor wafers W is performed on a lot-by-lot basis. The term “lot” refers to a group of semiconductor wafers W subjected to the same treatment under the same conditions. In the heat treatment apparatus  100  according to the present preferred embodiment, multiple (e.g., 25) semiconductor wafers W in a lot are placed on the load port  110  of the indexer part  101  while being stored in one carrier C, and are sequentially transported one by one into the treatment chamber  6  and subjected to the heating treatment. 
     For the start of the treatment of a lot in the heat treatment apparatus  100  that has not performed the treatment for some period of time, the first semiconductor wafer W in the lot is transported into the treatment chamber  6  that is at approximately room temperature and is then subjected to the preheating and the flash heating treatment. Examples of this case are such that the heat treatment apparatus  100  starts up after maintenance and then treats the first lot and such that a long time period has elapsed since the treatment of the preceding lot. During the heating treatment, heat transfer occurs from the semiconductor wafer W increased in temperature to in-chamber structures (structures in the chamber) including the susceptor  74  and the like. For this reason, the temperature of the susceptor  74  that is initially at room temperature increases gradually due to heat storage as the number of treated semiconductor wafers W increases. Also, part of infrared radiation emitted from the halogen lamps HL is absorbed by the lower chamber window  64 . For this reason, the temperature of the lower chamber window  64  increases gradually as the number of treated semiconductor wafers W increases. 
     When the heating treatment is performed on approximately ten semiconductor wafers W, the temperature of the susceptor  74  and the lower chamber window  64  reaches a constant stabilized temperature. In the susceptor  74  the temperature of which reaches the stabilized temperature, the amount of heat transferred from the semiconductor wafer W to the susceptor  74  and the amount of heat dissipated from the susceptor  74  are balanced with each other. Before the temperature of the susceptor  74  reaches the stabilized temperature, the amount of heat transferred from the semiconductor wafer W to the susceptor  74  is greater than the amount of heat dissipated from the susceptor  74 , so that the temperature of the susceptor  74  increases gradually due to heat storage as the number of treated semiconductor wafers W increases. On the other hand, after the temperature of the susceptor  74  reaches the stabilized temperature, the amount of heat transferred from the semiconductor wafer W to the susceptor  74  and the amount of heat dissipated from the susceptor  74  are balanced with each other, so that the temperature of the susceptor  74  is maintained at the constant stabilized temperature. After the temperature of the lower chamber window  64  reaches the stabilized temperature, the amount of heat that the lower chamber window  64  absorbs from the light emitted from the halogen lamps HL and the amount of heat released from the lower chamber window  64  are balanced with each other, so that the temperature of the lower chamber window  64  is also maintained at the constant stabilized temperature. 
     If the treatment is started in the treatment chamber  6  that is at room temperature in this manner, there has been a problem that a non-uniform temperature history results from a difference in temperature of the structures in the treatment chamber  6  between initial semiconductor wafers W in the lot and intermediate semiconductor wafers W in the lot. Also, there have been cases in which wafer warpage occurs in the initial semiconductor wafers W because the flash heating treatment is performed on the initial semiconductor wafers W supported by the susceptor  74  that is at a low temperature. To solve these problems, dummy running has been performed prior to the start of the treatment of a lot. The dummy running is a technique in which dummy wafers not to be treated are transported into the treatment chamber  6  and are subjected to the preheating and the flash heating treatment similar to those for the semiconductor wafers W to be treated, whereby the temperature of the in-chamber structures including the susceptor  74  and the like is increased to the stabilized temperature. The temperature of the in-chamber structures including the susceptor  74  and the like is increased to the stabilized temperature by performing the preheating and the flash heating treatment on approximately ten dummy wafers. Such dummy running is performed not only in the case of starting the treatment in the treatment chamber  6  that is at room temperature but also in the case of changing the preheating temperature T 1  and the treatment temperature T 2 . As mentioned above, the preheating and the flash heating treatment are performed repeatedly on the dummy wafers. As a result, deterioration of the dummy wafers proceeds to accordingly make cracking and warpage prone to occur in the dummy wafers. It is hence necessary to appropriately manage the deterioration condition of the dummy wafers. The management of the dummy wafers in the heat treatment apparatus  100  will be described below. 
       FIG. 11  is a flow diagram showing a procedure for management of a dummy wafer according to a first preferred embodiment of the present invention. The dummy wafers are disk-shaped silicon wafers similar to the semiconductor wafers W to be treated, and are similar in size and shape to the semiconductor wafers W. The dummy wafers, however, are neither patterned nor implanted with ions. That is, the dummy wafers are what is called bare wafers. 
     For the dummy running, whether a wafer to be started for transport is a dummy wafer or not is initially checked (Step S 11 ). The dummy wafers are stored in a carrier C (dummy carrier) exclusive to the dummy wafers and different from the carriers C for storing the ordinary semiconductor wafers W therein when in use. When the carrier C exclusive to the dummy wafers is placed on the load port  110  of the indexer part  101 , a tag attached to the carrier C is read, so that the controller  3  recognizes that the carrier C is the dummy carrier. If the wafer to be started for transport is a wafer stored in the dummy carrier, the controller  3  judges that the wafer is the dummy wafer. If the wafer to be started for transport is not the dummy wafer, the dummy running is not started. The type itself of the carrier C exclusive to the dummy wafers is the same as that of the carriers C for storing the ordinary semiconductor wafers W therein, and is a FOUP in the present preferred embodiment. 
     If the wafer to be started for transport is the dummy wafer, the procedure proceeds from Step S 11  to Step S 12  in which the dummy wafer is transported by the transport mechanism  38  (the transfer robot  120  and the transport robot  150 ) from the indexer part  101  to the heat treatment part  160 . The procedure for the transport of the dummy wafer is substantially similar to the aforementioned procedure for the transport of the semiconductor wafer W to be treated. 
     Next, the heating treatment is performed on the dummy wafer in the treatment chamber  6  of the heat treatment part  160  (Step S 13 ). Specifically, the dummy wafer is preheated by irradiation with light from the halogen lamps HL, and the front surface of the dummy wafer is thereafter flash heated by irradiation with a flash of light from the flash lamps FL. The details of the preheating and the flash heating are the same as those of the aforementioned heating treatment of the ordinary semiconductor wafer W. 
     Subsequently, the calculation part  31  of the controller  3  calculates a wear-and-tear value of the dummy wafer by summation in accordance with the details of the heating treatment performed on the dummy wafer (Step S 14 ). In the first preferred embodiment, the calculation part  31  calculates a preheating counter as the wear-and-tear value. The preheating counter is calculated by adding up the values obtained by multiplying the temperature of the dummy wafer measured when the dummy wafer is preheated by irradiation with light from the halogen lamps HL by a heating time period. 
       FIG. 12  is a graph showing changes in temperature of the dummy wafer during the preheating using the halogen lamps HL. The temperature of the dummy wafer is maintained at the preheating temperature T 1  from time t 1  to time t 2  by the irradiation with light from the halogen lamps HL The preheating counter is calculated by adding up the values obtained by multiplying the preheating temperature T 1  by a heating time period (t 2 −t 1 ). For example, it is assumed that the preheating counter of a dummy wafer prior to the treatment has a value of 20000. Then, in the case where the dummy wafer is heated at a preheating temperature of 700° C. for four seconds, 700×4=2800 is added to the preheating counter value of 20000 obtained prior to the treatment, so that the preheating counter has a new calculated value of 22800. In the case where the dummy wafer is further heated at a preheating temperature of 700° C. for four seconds, a new increment of 2800 is added to the preheating counter value of 22800 obtained prior to the treatment, so that the preheating counter has a new calculated value of 25600. The preheating counter value of the dummy wafer obtained prior to the treatment is registered in a dummy database  39  (with reference to  FIG. 10 ). The new value of the preheating counter calculated by the calculation part  31  is overwritten into the dummy database  39 . The dummy carrier and the wear-and-tear value of each of the dummy wafers stored in the dummy carrier are registered in association with each other in the dummy database  39 . 
     Next, the controller  3  judges whether the wear-and-tear value (the preheating counter the first preferred embodiment) calculated by the calculation part  31  is less than a predetermined threshold value or not (Step S 15 ). If the preheating counter is not less than the threshold value, the procedure proceeds from. Step S 15  to Step S 17  in which the alarm issuing part  32  of the controller  3  issues an alarm. For example, the alarm issuing part  32  displays on the display part  34  a warning that damage to the dummy wafer due to the preheating reaches a usage limit. 
     On the other hand, if the preheating counter is less than the threshold value, no alarm is issued. In this case, the dummy wafer subjected to the heating treatment is returned by the transport mechanism  38  from the heat treatment part  160  to the original carrier C in the indexer part  101 . In the present preferred embodiment, even if the alarm is issued in Step S 17 , the transport of the dummy wafer is not stopped but the dummy wafer is returned by the transport mechanism  38  to the original carrier C in the indexer part  101 . 
     In the first preferred embodiment, the alarm is issued if the preheating counter calculated by adding up the values obtained by multiplying the temperature of the dummy wafer measured when the dummy wafer is preheated by irradiation with light from the halogen lamps HL by the heating time period is not less than the threshold value. As the temperature of the dummy wafer during the preheating increases or as the heating time period increases, the damage to the dummy wafer increases and the preheating counter value accordingly greatly increases. In other words, the preheating counter is an indicator grasped as the wear-and-tear value indicating the degree of deterioration of the dummy wafer. The method as mentioned in the first preferred embodiment allows an operator of the heat treatment apparatus  100  to recognize that the deterioration of the dummy wafer reaches a set limit value and to reliably grasp the dummy wafer suffering advanced deterioration. Then, the operator replaces the dummy wafer suffering advanced deterioration with a new dummy wafer, for example, to prevent the erroneous treatment of the dummy wafer suffering advanced deterioration. 
     Second Preferred Embodiment 
     Next, a second preferred embodiment according to the present invention will be described. The second preferred embodiment is similar in configuration of the heat treatment apparatus  100  and in procedure for treatment of the semiconductor wafer W to the first preferred embodiment. The second preferred embodiment is substantially similar in details of the management of the dummy wafer ( FIG. 11 ) to the first preferred embodiment. The second preferred embodiment is different from the first preferred embodiment in details of the wear-and-tear value indicating the degree of deterioration of the dummy wafer. 
     In the second preferred embodiment, the calculation part  31  calculates an input electric power counter as the wear-and-tear value. The input electric power counter is calculated by adding up the amounts of electric power inputted to the halogen lamps HL which are measured when the dummy wafer is preheated by irradiation with light from the halogen lamps HL. Specifically, the input electric power counter is calculated by adding up the amounts of electric power inputted to the halogen lamps HL during a time interval between the time t 1  and the time t 2  where the temperature of the dummy wafer is maintained at the preheating temperature T 1  with reference to  FIG. 12 . For example, it is assumed that the input electric power counter of a dummy wafer prior to the treatment has a value of 32000. Then, in the case where the amount of electric power inputted to the halogen lamps HL which is measured when the dummy wafer is preheated is 16000, a new increment of 16000 is added to the input electric power counter value of 32000 obtained prior to the treatment, so that the input electric power counter has a new calculated value of 48000. In the case where the dummy wafer is further preheated with the amount of electric power of 16000 inputted to the halogen lamps HL, a new increment of 16000 is added to the input electric power counter value of 48000 obtained prior to the treatment, so that the input electric power counter has a new calculated value of 64000. The input electric power counter value of the dummy wafer obtained prior to the treatment is registered in the dummy database  39 . The new value of the input electric power counter calculated by the calculation part  31  is overwritten into the dummy database  39 . 
     The controller  3  judges whether the wear-and-tear value (the input electric power counter in the second preferred embodiment) calculated by the calculation part  31  is less than a predetermined threshold value or not, as in the first preferred embodiment. If the input electric power counter is not less than the threshold value, the alarm issuing part  32  issues an alarm. On the other hand, if the input electric power counter is less than the threshold value, no alarm is issued. In this case, the dummy wafer subjected to the heating treatment is returned by the transport mechanism  38  to the original carrier C. 
     In the second preferred embodiment, the alarm is issued if the input electric power counter calculated by adding up the amounts of electric power inputted to the halogen lamps HL which are measured when the dummy wafer is preheated by irradiation with light from the halogen lamps HL is not less than the threshold value. As the amount of electric power inputted to the halogen lamps HL during the preheating increases, the damage to the dummy wafer due to the preheating increases and the input electric power counter value accordingly greatly increases. In other words, the input electric power counter is an indicator grasped as the wear-and-tear value indicating the degree of deterioration of the dummy wafer. The method as mentioned in the second preferred embodiment allows an operator of the heat treatment apparatus  100  to recognize that the deterioration of the dummy wafer reaches a set limit value and to reliably grasp the dummy wafer suffering advanced deterioration. 
     Third Preferred Embodiment 
     Next, a third preferred embodiment according to the present invention will be described. The third preferred embodiment is similar in configuration of the heat treatment apparatus  100  and in procedure for treatment of the semiconductor wafer W to the first preferred embodiment. The third preferred embodiment is substantially similar in details of the management of the dummy wafer ( FIG. 11 ) to the first preferred embodiment. The third preferred embodiment is different from the first preferred embodiment in details of the wear-and-tear value indicating the degree of deterioration of the dummy wafer. 
     In the third preferred embodiment, the calculation part  31  calculates a discharge voltage counter as the wear-and-tear value. The discharge voltage counter is calculated by adding up the discharge voltages of the flash lamps FL measured when the dummy wafer is flash heated by irradiation with flashes of light from the flash lamps FL. Electric power is supplied from high-capacitance capacitors to the respective flash lamps FL. A value obtained by subtracting a residual voltage remaining in the capacitors after the flash irradiation from a charging voltage stored in the capacitors before the flash irradiation is the discharge voltage of the flash lamps FL. For example, it is assumed that the discharge voltage counter of a dummy wafer prior to the treatment has a value of 8000. In the case where the residual voltage of the capacitors is 3000 V after the flash lamps FL emit flashes of light for 1.4 milliseconds with the capacitors having a charging voltage of 4000 V prior to the flash irradiation, the discharge voltage of the flash lamps FL is 4000−3000=1000 V. In this case, an increment of 1000 is added to the discharge voltage counter value of 8000 obtained prior to the treatment, so that the discharge voltage counter has a new calculated value of 9000. In the case where the dummy wafer is further flash heated while the discharge voltage of the flash lamps FL is 2400, a new increment of 2400 is added to the discharge voltage counter value of 9000 obtained prior to the treatment, so that the discharge voltage counter has a new calculated value of 11400. The discharge voltage counter value of the dummy wafer obtained prior to the treatment is registered in the dummy database  39 . The new value of the discharge voltage counter calculated by the calculation part  31  is overwritten into the dummy database  39 . 
     The controller  3  judges whether the wear-and-tear value (the discharge voltage counter in the third preferred embodiment) calculated by the calculation part  31  is less than a predetermined threshold value or not, as in the first preferred embodiment. If the discharge voltage counter is not less than the threshold value, the alarm issuing part  32  issues an alarm. On the other hand, if the discharge voltage counter is less than the threshold value, no alarm is issued. In this case, the dummy wafer subjected to the heating treatment is returned by the transport mechanism  38  to the original carrier C. 
     In the third preferred embodiment, the alarm is issued if the discharge voltage counter calculated by adding up the discharge voltages of the flash lamps FL measured when the dummy wafer is flash heated by irradiation with flashes of light from the flash lamps FL is not less than the threshold value. As the discharge voltage of the flash lamps FL during the flash heating increases, the damage to the dummy wafer due to the flash heating increases and the discharge voltage counter value accordingly greatly increases. In other words, the discharge voltage counter is an indicator grasped as the wear-and-tear value indicating the degree of deterioration of the dummy wafer. The method as mentioned in the third preferred embodiment allows an operator of the heat treatment apparatus  100  to recognize that the deterioration of the dummy wafer reaches a set limit value and to reliably grasp the dummy wafer suffering advanced deterioration. 
     Fourth Preferred Embodiment 
     Next, a fourth preferred embodiment according to the present invention will be described. The fourth preferred embodiment is similar in configuration of the heat treatment apparatus  100  and in procedure for treatment of the semiconductor wafer W to the first preferred embodiment. The fourth preferred embodiment is substantially similar in details of the management of the dummy wafer ( FIG. 11 ) to the first preferred embodiment. The fourth preferred embodiment is different from the first preferred embodiment in details of the wear-and-tear value indicating the degree of deterioration of the dummy wafer. 
     In the fourth preferred embodiment, the calculation part  31  calculates a flash heating counter as the wear-and-tear value. The flash heating counter is calculated by adding up the values obtained by multiplying the front surface temperature of the dummy wafer measured when the dummy wafer is flash heated by irradiation with flashes of light from the flash lamps FL by the irradiation time period of the flashes of light. The irradiation time period of the flashes of light is the light emission time period of the flash lamps FL, and is adjustable, for example, by the coil constant of the lamp light source which supplies electric power to the flash lamps FL. Alternatively, the light emission time period of the flash lamps FL may be adjusted by connecting an IGBT (insulated-gate bipolar transistor) to a circuit which connects each of the flash lamps FL and a corresponding one of the capacitors and by controlling a time period for which electric charge is supplied by the IGBT from the corresponding capacitor to each flash lamp FL. For example, it is assumed that the flash heating counter of a dummy wafer prior to the treatment has a value of 30000. Then, in the case where the dummy wafer is flash heated to a front surface peak temperature of 1200° C. by flash irradiation for an irradiation time period of 1.4 milliseconds, 1200×1.4=1680 is added to the flash heating counter value of 30000 obtained prior to the treatment, so that the flash heating counter has a new calculated value of 31680. In the case where the dummy wafer is further flash heated to a front surface peak temperature of 1000° C. by flash irradiation for an irradiation time period of 10 milliseconds, a new increment of 1000×10=10000 is added to the flash heating counter value of 31680 obtained prior to the treatment, so that the flash heating counter has a new calculated value of 41680. The flash heating counter value of the dummy wafer obtained prior to the treatment is registered in the dummy database  39 . The new value of the flash heating counter calculated by the calculation part  31  is overwritten into the dummy database  39 . 
     The controller  3  judges whether the wear-and-tear value (the flash heating counter in the fourth preferred embodiment) calculated by the calculation part  31  is less than a predetermined threshold value or not, as in the first preferred embodiment. If the flash heating counter is not less than the threshold value, the alarm issuing part  32  issues an alarm. On the other hand, if the flash heating counter is less than the threshold value, no alarm is issued. In this case, the dummy wafer subjected to the heating treatment is returned by the transport mechanism  38  to the original carrier C. 
     In the fourth preferred embodiment, the alarm is issued if the flash heating counter calculated by adding up the values obtained by multiplying the front surface temperature of the dummy wafer measured when the dummy wafer is flash heated by irradiation with flashes of light from the flash lamps FL by the irradiation time period of the flashes of light is not less than the threshold value. As the front surface temperature of the dummy wafer during the flash heating increases or as the irradiation time period of the flashes of light increases, the damage to the dummy wafer increases and the flash heating counter value accordingly greatly increases. In other words, the flash heating counter is an indicator grasped as the wear-and-tear value indicating the degree of deterioration of the dummy wafer. The method as mentioned in the fourth preferred embodiment allows an operator of the heat treatment apparatus  100  to recognize that the deterioration of the dummy wafer reaches a set limit value and to reliably grasp the dummy wafer suffering advanced deterioration. 
     Modifications 
     While the preferred embodiments according to the present invention have been described hereinabove, various modifications of the present invention in addition to those described above may be made without departing from the scope and spirit of the invention. For example, the alarm may be issued by ORing the wear-and-tear values described in the first to fourth preferred embodiments. Specifically, the preheating counter calculated by adding up the values obtained by multiplying the temperature of the dummy wafer measured when the dummy wafer is preheated by irradiation with light from the halogen lamps HL by the heating time period is defined as a first wear-and-tear value. The input electric power counter calculated by adding up the amounts of electric power inputted to the halogen lamps HL which are measured when the dummy wafer is preheated by irradiation with light from the halogen lamps HL is defined as a second wear-and-tear value. The discharge voltage counter calculated by adding up the discharge voltages of the flash lamps FL measured when the dummy wafer is flash heated by irradiation with flashes of light from the flash lamps FL is defined as a third wear-and-tear value. The flash heating counter calculated by adding up the values obtained by multiplying the front surface temperature of the dummy wafer measured when the dummy wafer is flash heated by irradiation with flashes of light from the flash lamps FL by the irradiation time period of the flashes of light is defined as a fourth wear-and-tear value. Then, the alarm issuing part  32  may issue the alarm if at least one of the first, second, third, and fourth wear-and-tear values is not less than a threshold value. Such an increase in the number of wear-and-tear values allows the operator to reliably grasp the dummy wafer suffering advanced deterioration with higher accuracy. 
     If the wear-and-tear value is not less than the threshold value, the transport of the dummy wafer may be stopped in addition to the issue of the alarm. The dummy wafer is deformed in some cases if the wear-and-tear value is not less than the threshold value. In these cases, there is apprehension that the deformation of the dummy wafer causes transport trouble. Stopping the transport of the dummy wafer if the wear-and-tear value is not less than the threshold value prevents such transport trouble. 
     In the first preferred embodiment, the preheating counter may be calculated by adding up the values obtained by integrating the temperature of the dummy wafer measured during a time interval between the transport of the dummy wafer into the treatment chamber  6  and the transport of the dummy wafer out of the treatment chamber  6  (i.e., the values obtained by integrating the wafer temperature of  FIG. 12  with respect to time). Similarly, in the second preferred embodiment, the input electric power counter may be calculated by adding up the values obtained by integrating the amount of electric power inputted to the halogen lamps HL during the time interval between the transport of the dummy wafer into the treatment chamber  6  and the transport of the dummy wafer out of the treatment chamber  6 . 
     Although the 30 flash lamps FL are provided in the flash lamp house  5  according to the aforementioned preferred embodiments, the present invention is not limited to this. Any number of flash lamps FL may be provided. The flash lamps FL are not limited to the xenon flash lamps, but may be krypton flash lamps. Also, the number of halogen lamps HL provided in the halogen lamp house  4  is not limited to 40. Any number of halogen lamps HL may be provided. 
     In the aforementioned preferred embodiments, the filament-type halogen lamps HL are used as continuous lighting lamps that emit light continuously for not less than one second to preheat the semiconductor wafer W. The present invention, however, is not limited to this. In place of the halogen lamps HL, discharge type arc lamps (e.g., xenon arc lamps) may be used as the continuous lighting lamps to perform the preheating, In this case, the preheating of the dummy wafers is also performed by light irradiation from the arc lamps. 
     Moreover, a substrate to be treated by the heat treatment apparatus  100  is not limited to a semiconductor wafer, but may be a glass substrate for use in a flat panel display for a liquid crystal display apparatus and the like, and a substrate for a solar cell. 
     While the invention has been described in detail, the foregoing description is in all aspects illustrative and not restrictive, it is understood that numerous other modifications and variations can be devised without departing from the scope of the invention.