Abstract:
An apparatus for fabricating a semiconductor device, whereby a semiconductor wafer is thermally treated with a wafer treatment device. The semiconductor wafer is delivered with a conveyer to the wafer treatment device. The temperature of the conveyer is controlled to have an optimum temperature by an arm heater and an arm cooler.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a divisional application of application Ser. No. 09/206,235, filed Dec. 7,1998, now U.S. Pat. No. 6,413,888, which is hereby incorporated by reference in its entirety for all purposes. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a method and an apparatus for fabricating a semiconductor device. More particularly, the present invention is directed to a method and an apparatus for fabricating a semiconductor device, in which a semiconductor wafer is delivered by a conveyer to a wafer treatment device and is thermally treated. 
     BACKGROUND OF THE INVENTION 
     In a process for fabricating a semiconductor device, a semiconductor wafer is thermally treated. For example, in diffusion process, an electrode formed on a compound semiconductor wafer is sintered. 
     A conventional sinter furnace includes a heating chamber, in which a semiconductor wafer is heated, and a cooling chamber, in which the semiconductor wafer is cooled down. In such a conventional sinter furnace, a semiconductor wafer is conveyed by a delivery arm, between a loader cassette and the heating chamber; between the heating chamber and the cooling chamber; and between the cooling chamber and an un-loader cassette. 
     Semiconductor wafers contained in the loader cassette are controlled in temperature at about 20° C. The heating chamber includes a hot plate controlled in temperature at 450° C. The cooling chamber includes a cooling plate controlled in temperature at 20° C. 
     According to the conventional apparatus, a semiconductor wafer of the room temperature is rapidly heated up when the wafer is put onto the heating plate in the heating chamber. The temperature of the semiconductor wafer changes too rapidly, and therefore, the semiconductor wafer may be broken by heat-shock phenomenon. In addition, a semiconductor wafer, which has been heated in the heating chamber, is rapidly cooled down when the wafer is taken out from the heating chamber. That is because the delivery arm is at the room temperature of about 20° C., which is 430° C. different from the semiconductor wafer, which has been already heated. As a result, the semiconductor wafer may be broken by cool-shock phenomenon. Once a semiconductor wafer is broken, semiconductor devices formed thereon can not be used anymore. The above-described problems are remarkable and more serious to compound type of semiconductor wafers, such as GaAs wafers, 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a method for fabricating a semiconductor device in which a semiconductor wafer is prevented from being broken, caused by rapid temperature variation. 
     Another object of the present invention is to provide an apparatus for fabricating a semiconductor device in which a semiconductor wafer is prevented from being broken, caused by rapid temperature variation. 
     Additional objects, advantages and novel features of the present invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     According to a first aspect of the present invention, a method for fabricating a semiconductor device includes the steps of: thermally treating a semiconductor wafer with a wafer treatment device; delivering the semiconductor wafer by a conveyer to the wafer treatment device; and controlling the temperature of the conveyer to have an optimum temperature. 
     According to a second aspect of the present invention, an apparatus for fabricating a semiconductor device, includes a wafer treatment device which applies a thermal treatment to a semiconductor wafer; a conveyer which delivers the semiconductor wafer to and from the wafer treatment device; and a controller which controls the temperature of the conveyer to have an optimum temperature. 
     As described above, according to the present invention, the conveyer is controlled in temperature, therefore, it can be avoided that the temperature of the semiconductor wafer is changed too rapidly. As a result, the semiconductor wafer is prevented from being broken due to heat-shock (rapid heating) or cool-shock (rapid cooling). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view illustrating a conventional sinter furnace. 
         FIG. 2  is a graph showing temperature variation of a semiconductor wafer that is processed in the conventional sinter furnace. 
         FIG. 3  is a plan view illustrating a sinter furnace according to a first preferred embodiment of the present invention. 
         FIG. 4  is a cross-sectional view taken on line A—A of FIG.  3 . 
         FIG. 5  is a cross-sectional view showing the inside of a delivery arm used in the sinter furnace of the first preferred embodiment. 
         FIG. 6  is an explanatory diagram showing the operation of an arm unit used in the sinter furnace of the first preferred embodiment. 
         FIG. 7  is a graph showing temperature variation of a semiconductor wafer that is processed in the sinter furnace of the first preferred embodiment. 
         FIG. 8  is a plan view illustrating a sinter furnace according to a second preferred embodiment of the present invention. 
         FIG. 9  is a cross-sectional view taken on line B—B in FIG.  8 . 
         FIG. 10  is a cross-sectional view taken on line C—C in FIG.  8 . 
         FIG. 11  is a cross-sectional view showing the inside of a delivery arm of a first arm unit used in the sinter furnace of the second preferred embodiment. 
         FIG. 12  is a cross-sectional view showing the inside of a delivery arm of a second arm unit used in the sinter furnace of the second preferred embodiment. 
         FIG. 13  is a graph showing temperature variation of a semiconductor wafer that is processed in the sinter furnace of the second preferred embodiment. 
         FIG. 14  is a plan view illustrating a sinter furnace according to a third preferred embodiment of the present invention. 
         FIG. 15  is a diagram showing the operation of an arm unit used in the sinter furnace of the third preferred embodiment. 
         FIG. 16  is a graph showing temperature variation of a semiconductor wafer that is processed in the sinter furnace of the third preferred embodiment. 
         FIG. 17  is a plan view illustrating a sinter furnace according to a fourth preferred embodiment of the present invention. 
         FIG. 18  is a cross-sectional view taken on line D—D in FIG.  17 . 
         FIG. 19  is a cross-sectional view showing the inside of a delivery arm of an arm unit used in the sinter furnace of the fourth preferred embodiment. 
         FIG. 20  is a graph showing the temperature variation of a semiconductor wafer, which is processed in the sinter furnace according to the fourth preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For better understanding of the present invention, a conventional technology is first described.  FIG. 1  depicts a conventional sinter furnace, which includes a heating chamber  1 , a cooling chamber  2 , a conveying arm  3 , a loader cassette  5  and an un-loader cassette  6 . In the heating chamber  1 , a GaAs semiconductor wafer  4  is heated on a hot plate, kept at 450° C., in a nitrogen gas atmosphere. In the cooling chamber  2 , the semiconductor wafer  4  is cooled by a cool plate, kept at 20° C., in a nitrogen gas atmosphere. The semiconductor wafer  4  is delivered by the conveying arm  3 , which is made of SUS. In the loader cassette  5  and the un-loader cassette  6 , semiconductor wafers have the room temperature of about 20° C. 
       FIG. 2  is a graph showing temperature variation of the semiconductor wafer  4 , which is processed by the conventional sinter furnace. When a semiconductor wafer  4  is conveyed by the conveying arm  3  from the loader cassette  5  to the heating chamber  1 , the semiconductor wafer  4  is heated in the heating chamber  1  for five minutes. The instant the semiconductor wafer  4  is put on the hot plate (not shown) in the heating chamber  1 , the semiconductor wafer is rapidly heated to 450° C., as shown in FIG.  2 . 
     After the heating treatment, the semiconductor wafer  4  is conveyed by the conveying arm  3  from the heating chamber  1  to the cooling chamber  2 . The instant the semiconductor wafer  4  is in touch with the conveying arm  3  of the room temperature, the semiconductor wafer  4  is rapidly cooled down, because the conveying arm  3  is more than 400° C. different in temperature from the semiconductor wafer  4 , which has been heated to 450° C. 
     According to the conventional apparatus, the semiconductor wafer  4  of the room temperature is rapidly heated up when the wafer is put onto the hot plate in the heating chamber  1 , and therefore, the semiconductor wafer  4  may be broken by heat-shock phenomenon. In addition, a wafer, which has been heated in the heating chamber  1 , is rapidly cooled down when the wafer is picked up with the conveying arm  3 . As a result, the wafer may be broken by cool-shock phenomenon. Once a semiconductor wafer is broken, semiconductor devices formed on the wafer can not be used anymore. 
       FIG. 3  depicts a sinter furnace according to a first preferred embodiment of the present invention.  FIG. 4  shows the cross-section taken on line A—A of FIG.  3 . The sinter furnace includes a heating chamber  10 , a cooling chamber  12 , a conveying arm unit  20 , a, loader cassette  16  and an un-loader cassette  18 . In the heating chamber  10 , a GaAs semiconductor wafer  14  is heated on a hot plate (not shown), which is kept at 450° C., in a nitrogen gas atmosphere. In the cooling chamber  12 , the semiconductor wafer  14  is cooled on a cool plate (not shown), which is kept at 20° C., in a nitrogen gas atmosphere. During sintering process, the semiconductor wafer  14  is delivered by the conveying arm unit  20 , which is made of SUS. In the loader cassette  16  and the un-loader cassette  18 , semiconductor wafers have the room temperature of about 20° C. 
     The arm unit  20  includes a base arm  22 , a delivery arm  24  and rotation motors  26  and  28 . The motor  26  is connected to one end of the base arm  22  and turns (swings or pivots) the base arm  22  on the axis thereof. The motor  28  is connected to the other end of the base arm  22  and to one end of the delivery arm  24  and turns (swings or pivots) the delivery arm  24  on the axis thereof. The semiconductor wafer  14  is placed on the other end of the delivery arm  24 . The delivery arm  24  is connected to a controller  34  via a flexible cable  36 . The base arm  22  and the delivery arm  24  are driven independently from each other, so that the semiconductor wafer  14  can be delivered only by the delivery arm  24 . 
     As shown in  FIG. 4 , the heating chamber  10  is provided with an elevation motor  30  and elevation pins  32 . The elevation pins  32  extend vertically through the heating chamber  10  to reach the bottom surface of the semiconductor wafer  14 . The elevation motor  30  drives the elevation pins  32  up and down so that the semiconductor wafer  14  is delivered between the delivery arm  24  and the hot plate (not shown) in the heating chamber  10 . In the same manner as the heating chamber  10 , the cooling chamber  12  is provided with an elevation motor (not shown) and elevation pins (not shown), as well. 
       FIG. 5  depicts the inside structure of the delivery arm  24  according to the first preferred embodiment of the present invention. The delivery arm  24  is provided therein with a heating coil  38  and a thermocouple  40 . The heating coil  38  is connected via a flexible wire  42  to the controller  34 , shown in FIG.  4 . The thermocouple  40  is connected via a flexible wire  44  to the controller  34 . The wires  42  and  44  are included in the flexible cable  36  so that the flexible wires  42  and  44  do not block the passage of the base arm  22  and the delivery arm  24 . 
     The heating coil  38  generates heat in response to electric current supplied from the controller  34  through the flexible wire  42 , so that the delivery arm  24  is heated to about 200° C. Basically, the delivery arm  24  is controlled in temperature at 200° C. throughout the sintering process. The thermocouple  40  detects the temperature of the delivery arm  24  and supplies the corresponding output signal to the controller  34  through the flexible wire  44 . In response to the output signal of the thermocouple  40 , the controller  34  controls the amount of current to be supplied through the flexible wire  42  to the heating coil  38 , so that the delivery arm  24  is controlled at an optimum temperature (200° C.). 
       FIG. 6  shows the route along which the semiconductor wafer  14  is delivered, according to the first preferred embodiment of the present invention.  FIG. 7  is a graph showing temperature variation of the semiconductor wafer  14 , which is processed in the sinter furnace of the first preferred embodiment of the present invention. When the semiconductor wafer  14  is picked up with the delivery arm  24  from the loader cassette  16 , the semiconductor wafer  14  is delivered toward the heating chamber  10 . During the delivery of the semiconductor wafer  14  between the loader cassette  16  and the heating chamber  10 , as indicated by a broken line of {circle around ( 1 )}, the semiconductor wafer  14  is pre-heated to 150-200° C. on the delivery arm  24 . The delivery arm  24  delivers the semiconductor wafer  14  relatively slowly so that the semiconductor wafer  14  is sufficiently pre-heated. 
     When the delivery arm  24  is positioned above the heating chamber  10 , the elevation motor  30  moves the elevation pins  32  up so as to reach the semiconductor wafer  14 , and the delivery arm  24  slides back so as not to block the passage of the semiconductor wafer  14 . When the delivery arm  24  is completely apart from the heating chamber  10 , the elevation motor  30  moves the elevation pins  32  down so that the semiconductor wafer  14  is set on the hot plate in the heating chamber  10 . The semiconductor wafer  14  is heated on the hot plate (not shown) of 450° C. in a nitrogen gas atmosphere for five minute. When the semiconductor wafer  14  is placed on the hot plate, the semiconductor wafer  14  has been already heated to 150-200° C. As a result, the semiconductor wafer  14  is not heated too rapidly to 450° C., as shown in FIG.  7 . Therefore, it is avoided that the semiconductor wafer  14  is broken due to heat-shock phenomenon. 
     After the heating treatment in the heating chamber  10 , the elevation motor  30  moves the elevation pins  32  up so that the elevation pins  32  lift the semiconductor wafer  14  apart from the heating chamber  10 . When the semiconductor wafer  14  is lifted up from the heating chamber  10 , the delivery arm  24  is slid under the semiconductor wafer  14 , then the elevation pins  32  go down so that the semiconductor wafer  14  is placed on the delivery arm  24 . When the semiconductor wafer  14  of 450° C. is in touch with the delivery arm  24  of 200° C., the semiconductor wafer  14  is cooled down to around 150 to 200° C. Because the temperature difference between the semiconductor wafer  14  and the delivery arm  24  is about 250° C., the semiconductor wafer  14  is not cooled down too rapidly. Therefore, it is avoided that the semiconductor wafer  14  is broken due to cool-shock phenomenon. 
     Next, the semiconductor wafer  14  is delivered by the delivery arm  24  from the heating chamber  10  to the cooling chamber  12 , as indicated by a broken line of {circle around ( 2 )}. In the cooling chamber  12 , the semiconductor wafer  14  is cooled down on the cool plate of 20° C. The cooling treatment is carried out for five minutes in a nitrogen gas atmosphere. After the cooling treatment, the delivery arm  24  picks up the semiconductor wafer  14  and delivers it to the un-loader cassette  18 , as indicated by a broken line of {circle around ( 3 )}. In the cooling chamber  12 , the semiconductor wafer  14  is conveyed between the delivery arm  24  and the cool plate in the same manner as the heating chamber  10 . 
     As described above, according to the first preferred embodiment of the present invention, the delivery arm  24  is controlled in temperature, therefore, it can be avoided that the temperature of the semiconductor wafer  14  is changed too rapidly. As a result, the semiconductor wafer  14  is prevented from being broken due to heat-shock (rapid heating) or cool-shock (rapid cooling). 
       FIG. 8  depicts a sinter furnace according to a second preferred embodiment of the present invention.  FIG. 9  is a cross-sectional view taken on line B—B in FIG.  8 .  FIG. 10  is a cross-sectional view taken on line C—C in FIG.  8 . The sinter furnace of the second preferred embodiment includes a heating chamber  110 , a cooling chamber  112 , a first conveying arm unit  120 , a second conveying arm unit  150 , a loader cassette  116  and an un-loader cassette  118 . In the heating chamber  110 , a GaAs semiconductor wafer  114  is heated on a hot plate (not shown), which is kept at 450° C., in a nitrogen gas atmosphere. In the cooling chamber  112 , the semiconductor wafer  114  is cooled on a cool plate (not shown), which is kept at 20° C., in a nitrogen gas atmosphere. During sintering process, the semiconductor wafer  114  is delivered by the first and second conveying arm units  120  and  150 , which are made of SUS. In the loader cassette  116  and the un-loader cassette  118 , semiconductor wafers have the room temperature of about 20° C. 
     The first arm unit  120  includes a base arm  122 , a delivery arm  124  and motors  126  and  128 . The motor  126  is connected to one end of the base arm  122  and turns (swings or pivots) the base arm  122  on the axis thereof. The motor  128  is connected to the other end of the base arm  122  and to one end of the delivery arm  124  and turns (swings or pivots) the delivery arm  124  on the axis thereof. The semiconductor wafer  114  is placed on the other end of the delivery arm  124 , The delivery arm  124  is connected to a controller  134  via a flexible cable  136 . The base arm  122  and the delivery arm  124  are driven independently from each other, so that the semiconductor wafer  114  can be delivered only by the delivery arm  124 . 
     The second arm unit  150  includes a base arm  152 , a delivery arm  154  and motors  156  and  158 . The motor  156  is connected to one end of the base arm  152  and turns (swings or pivots) the base arm  152  on the axis thereof. The motor  158  is connected to the other end of the base arm  152  and to one end of the delivery arm  154  and turns (swings or pivots) the delivery arm  154  on the axis thereof. The semiconductor wafer  114  is placed on the other end of the delivery arm  154 . The delivery arm  154  is connected to a controller  164  via a flexible pipe  168 . The base arm  152  and the delivery arm  154  are driven independently from each other, so that the semiconductor wafer  114  can be delivered only by the delivery arm  154 . 
     As shown in  FIG. 9 , the heating chamber  110  is provided with an elevation motor  130  and elevation pins  132 . The elevation pins  132  extend vertically through the heating chamber  110  to reach the bottom surface of the semiconductor wafer  114 . The elevation motor  130  drives the elevation pins  132  up and down so that the semiconductor wafer  114  is carried between the delivery arm  124  and the hot plate (not shown) in the heating chamber  110 . 
     As shown in  FIG. 10 , the cooling chamber  112  is provided with an elevation motor  160  and elevation pins  162 . The elevation pins  162  extend vertically through the cooling chamber  112  to reach the bottom surface of the semiconductor wafer  114 . The elevation motor  160  drives the elevation pins  162  up and down so that the semiconductor wafer  114  is carried between the delivery arm  124  and the cool plate (not shown) in the cooling chamber  112 , and between the delivery arm  154  and the cool plate. 
       FIG. 11  depicts the inside structure of the delivery arm  124  of the first conveying arm unit  120  according to the second preferred embodiment of the present invention. The delivery arm  124  is provided therein with a heating coil  138  and a thermocouple  140 . The heating coil  138  is connected via a flexible wire  142  to the controller  134 , shown in FIG.  9 . The thermocouple  140  is connected via a flexible wire  144  to the controller  134 . The flexible wires  142  and  144  are included in the flexible cable  136  so that the flexible wires  142  and  144  do not block the passage of the base arm  122  and the delivery arm  124 . 
     The heating coil  138  generates heat in response to electric current supplied from the controller  134  through the flexible wire  142 , so that the delivery arm  124  is heated to about 200°. The thermocouple  140  detects the temperature of the delivery arm  124  and supplies the corresponding output signal to the controller  134  through the flexible wire  144 . In response to the output signal of the thermocouple  140 , the controller  134  controls the amount of current to be supplied through the flexible wire  142  to the heating coil  138 , so that the delivery arm  124  is controlled at an optimum temperature. 
       FIG. 12  depicts the inside structure of the delivery arm  154  of the second conveying arm unit  150  according to the second preferred embodiment of the present invention. The delivery arm  154  is provided therein with a cooling pipe  170  and a thermocouple  172 . The cooling pipe  170  is connected via a flexible pipe  168  to the controller  164 , as shown in FIG.  10 . The thermocouple  172  is connected via a flexible wire  174  to the controller  164 . The ends of the cooling pipe  170  and the flexible wire  174  are contained in the flexible pipe  164  so that the cooling pipe  170  and the flexible wire  172  do not block the passage of the base arm  152  and the delivery arm  154 . 
     Cooling liquid, such as water, travels in the cooling pipe  170  so that the delivery arm  154  is controlled in temperature at about 20° C. The thermocouple  172  detects the temperature of the delivery arm  154  and supplies the corresponding output signal to the controller  164  through the flexible wire  174 . In response to the output signal of the thermocouple  172 , the controller  164  controls the temperature of the cooling liquid traveling in the cooling pipe  170 , so that the delivery arm  154  is controlled at an optimum temperature. 
       FIG. 13  is a graph showing temperature variation of the semiconductor wafer  114 , which is processed in the sinter furnace according to the second preferred embodiment of the present invention. In this embodiment, the first conveying arm unit  120  is used for conveying the semiconductor wafer  114  between the loader cassette  116  and the heating chamber  110 , and between the heating chamber  110  and the cooling chamber  112 . On the other hand, the second conveying arm unit  150  is used for conveying the semiconductor wafer  114  between the cooling chamber  112  and the un-loader cassette  118 . 
     In operation, the semiconductor wafer  114  is picked up with the delivery arm  124  of the first conveying arm unit  120  from the loader cassette  116 , and delivered toward the heating chamber  110 . During the delivery of the semiconductor wafer  114  between the loader cassette  116  and the heating chamber  110 , the semiconductor wafer  114  is pre-heated to 150-200° C. on the delivery arm  124 . The delivery arm  124  delivers the semiconductor wafer  114  relatively slowly so that the semiconductor wafer  114  is pre-heated enough. 
     When the delivery arm  124  is positioned just above the heating chamber  110 , the elevation motor  130  moves the elevation pins  132  up so as to reach the semiconductor wafer  114 , and the delivery arm  124  slides back so as not to block the passage of the semiconductor wafer  114 . When the delivery arm  124  is completely apart from the heating chamber  110 , the elevation motor  130  moves the elevation pins  132  down so that the semiconductor wafer  114  is arranged on the hot plate (not shown) in the heating chamber  110 . The semiconductor wafer  114  is heated on the hot plate (not shown) in a nitrogen gas atmosphere for five minutes. When the semiconductor wafer  114  is placed on the hot plate, the semiconductor wafer  114  has been already pre-heated to 150-200° C. As a result, the semiconductor wafer  114  is not heated too rapidly to 450° C., as shown in FIG.  13 . Therefore, the semiconductor wafer  114  is prevented from being broken due to heat-shock phenomenon. 
     After the heating treatment in the heating chamber  110 , the elevation motor  130  moves the elevation pins  132  up so that the elevation pins  132  lift up the semiconductor wafer  114  apart from the heating chamber  110 . When the semiconductor wafer  114  is lifted up from the heating chamber  110 , the delivery arm  124  is slid under the semiconductor wafer  114 , then the elevation pins  132  go down so that the semiconductor wafer  114  is placed on the delivery arm  124 . When the semiconductor wafer  114  of 450° C. is in touch with the delivery arm  124  of 200° C., the semiconductor wafer  114  is cooled down to around 150-200° C. Because the temperature difference between the semiconductor wafer  114  and the delivery arm  124  is about 250° C., the semiconductor wafer  114  is not cooled down too rapidly. Therefore, the semiconductor wafer  114  is prevented from being broken due to cool-shock phenomenon. 
     Next, the semiconductor wafer  114  is delivered by the delivery arm  124  from the heating chamber  110  to the cooling chamber  112 . 
     When the delivery arm  124  is positioned above the cooling chamber  112 , the elevation motor  160  moves the elevation pins  162  up so as to reach the semiconductor wafer  114 , and the delivery arm  124  slides back so as not to block the passage of the semiconductor wafer  114 . When the delivery arm  124  is completely apart from the cooling chamber  112 , the elevation motor  160  moves the elevation pins  162  down so that the semiconductor wafer  114  is arranged on the cool plate (not shown) in the cooling chamber  112 . The semiconductor wafer  114  is cooled on the cool plate (not shown) in a nitrogen gas atmosphere for five minutes. 
     After the cooling treatment, the elevation motor  160  moves the elevation pins  162  up so that the elevation pins  162  lift the semiconductor wafer  114  apart from the cooling chamber  112 . When the semiconductor wafer  114  is lifted up from the cooling chamber  112 , the delivery arm  154  of the second conveying arm unit  150  is slid under the semiconductor wafer  114 . Then, the elevation pins  162  go down so that the semiconductor wafer  114  is placed on the delivery arm  154 . In this case, the semiconductor wafer  114  of 20° C. is in touch with the delivery arm  154  of 20° C., so that there is no temperature difference between them. Therefore, the semiconductor wafer  114  is prevented from being broken due to cool-shock phenomenon. 
     Next, the semiconductor wafer  114  is delivered by the delivery arm  154  of the second conveying arm unit  150  to the un-loader cassette  118 . 
     As described above, according to the second preferred embodiment of the present invention, the delivery arm  124  of the first conveying arm unit  120  is controlled in temperature at 200° C. Therefore, the semiconductor wafer  114  is prevented from being broken due to heat-shock (rapid heating) or cool-shock (rapid cooling). 
     Further, according to the second preferred embodiment of the present invention, the delivery arm  154  of the second conveying arm unit  150  is controlled in temperature at 20° C. Therefore, it can be avoided that the temperature of the semiconductor wafer  114  is changed too rapidly, when the semiconductor wafer  114  is conveyed from the cooling chamber  112  to the un-loader cassette  118 . 
       FIG. 14  depicts a sinter furnace according to a third preferred embodiment of the present invention. The sinter furnace includes a heating chamber  110 , a cooling chamber  112 , a first conveying arm unit  120 , a second conveying arm unit  150 , an intermediate chamber  238 , a loader cassette  116  and an un-loader cassette  118 . In the heating chamber  110 , a GaAs semiconductor wafer  114  is heated on a hot plate (not shown), which is kept at 450° C., in a nitrogen gas atmosphere. In the cooling chamber  112 , the semiconductor wafer  114  is cooled on a cool plate (not shown), which is kept at 20° C., in a nitrogen gas atmosphere. During sintering process, the semiconductor wafer  114  is delivered by the first and second conveying arm units  120  and  150 , which are made of SUS. In the loader cassette  116  and the un-loader cassette  118 , semiconductor wafers have the room temperature of about 20° C. 
     The detailed structure of the first and second arm units  120  and  150 , the heating chamber  110 , the cooling chamber  112 , the loader cassette  116  and the un-loader cassette  118  correspond to those in the second preferred embodiment, shown in  FIGS. 8-12 . The same description for those elements are not repeated. 
     The intermediate chamber  238  includes a heat plate controlled in temperature at 150° C., so that the semiconductor wafer  114  placed therein is pre-heated before the heating treatment of the heating chamber  110  and pre-cooling before the cooling treatment of the cooing chamber  112 . 
       FIG. 15  shows the route along which the semiconductor wafer  114  is delivered in the sinter furnace according to the third preferred embodiment of the present invention.  FIG. 16  shows temperature variation of the semiconductor wafer  114 , which is processed in the sinter furnace according to the third preferred embodiment of the present invention. 
     In this embodiment, the first conveying arm unit  120 , provided with the heating mechanism, is used for conveying the semiconductor wafer  114  between the intermediate chamber  238  and the heating chamber  110 , as indicated by broken lines {circle around ( 2 )} and {circle around ( 3 )}. On the other hand, the second conveying arm unit  150 , provided with the cooling mechanism, is used for conveying the semiconductor wafer  114  from the loader cassette  116  to the intermediate chamber  238 , as indicated by a broken line {circle around ( 1 )}; from the intermediate chamber  238  to the cooling chamber  112 , as indicated by a broken line {circle around ( 4 )}; and from the cooling chamber  112  to the un-loader cassette  118 , as indicated by a broken line {circle around ( 5 )}. 
     In operation, first, the semiconductor wafer  114  is delivered by the delivery arm  154  of the second conveying arm unit  150  from the loader cassette  116  to the intermediate chamber  238 , as indicated by broken line {circle around ( 1 )}. When the semiconductor  114  is placed on the delivery arm  154 , the delivery arm  154  has been controlled at 20° C., which is corresponding to the current temperature of the semiconductor wafer  114 . In the intermediate chamber  238 , the semiconductor wafer  114  is gradually heated to 150° C. in a nitrogen gas atmosphere for five minutes. 
     Next, the first conveying arm unit  120  delivers the semiconductor wafer  114  from the intermediate chamber  238  to the heating chamber  110 , as indicated by broken line {circle around ( 2 )}. When the semiconductor wafer  114  is placed on the delivery arm  124 , the temperature difference between them is about 50° C. In the heating chamber  110 , the semiconductor wafer  114  is heated on the hot plate (not shown) in a nitrogen gas atmosphere for five minutes. When the semiconductor wafer  114  is placed on the hot plate of the heating chamber  110 , the semiconductor wafer  114  has been already heated to 150-200° C. by the delivery arm  124  of the first conveying arm unit  120 . As a result, the temperature difference between the semiconductor wafer  114  and the hot plate is 250-300° C. Therefore, the semiconductor wafer  114  is not heated too rapidly to 450° C., as shown in FIG.  16 . The semiconductor wafer  114  is prevented from being broken due to heat-shock phenomenon. 
     After the heating treatment in the heating chamber  110 , the first conveying arm unit  120  delivers the semiconductor wafer  114  to the intermediate chamber  238  again, as indicated by broken line {circle around ( 3 )}. When the semiconductor wafer  114  of 450° C. is in touch with the delivery arm  124  of 200° C., the semiconductor wafer  114  is cooled down to around 150-200° C. Because the temperature difference between the semiconductor wafer  114  and the delivery arm  124  is about 250° C., the semiconductor wafer  114  is not cooled down too rapidly. Therefore, the semiconductor wafer  114  is prevented from being broken due to cool-shock phenomenon. 
     In the intermediate chamber  238 , the semiconductor wafer  114  is controlled in temperature at 150° C. When the semiconductor wafer  114  is set in the intermediate chamber  238 , there is no temperature difference between them. After the intermediate treatment, the semiconductor wafer  114  is delivered by the second conveying arm unit  150  to the cooling chamber  112 , as indicated by a broken line {circle around ( 4 )}. In the cooling chamber  112 , the semiconductor wafer  114  is cooled on the cool plate (not shown) in a nitrogen gas atmosphere for five minutes. 
     After the cooling treatment, the second conveying arm unit  150  delivers the semiconductor wafer  114  to the un-loader cassette  118 , as indicated by broken line {circle around ( 5 )}. In this case, the semiconductor wafer  114  of 20° C. is in touch with the delivery arm  154  of 20° C., so that no temperature difference is made between them. Therefore, the semiconductor wafer  114  is prevented from being broken due to cool-shock phenomenon. 
     As described above, according to the third preferred embodiment of the present invention, the same advantages as the first and second preferred embodiments can be obtained. That is, it can be avoided that the temperature of the semiconductor wafer  114  is changed too rapidly. As a result, the semiconductor wafer  114  is prevented from being broken due to heat-shock (rapid heating) or cool-shock (rapid cooling). 
       FIG. 17  depicts a sinter furnace according to a fourth preferred embodiment of the present invention.  FIG. 18  shows a cross-section taken on line D—D in FIG.  17 . The sinter furnace according to the fourth preferred embodiment includes a heating chamber  310 , a cooling chamber  312 , a conveying arm unit  320 , an intermediate chamber  338 , a loader cassette  316  and an un-loader cassette  318 . In the heating chamber  310 , a GaAs semiconductor wafer  314  is heated on a hot plate (not shown), which is kept at 450° C., in a nitrogen gas atmosphere. In the cooling chamber  312 , the semiconductor wafer  314  is cooled on a cool plate (not shown), which is kept at 20° C., in a nitrogen gas atmosphere. During sintering process, the semiconductor wafer  314  is delivered by the conveying arm unit  320 , which is made of SUS. In the loader cassette,  316  and the un-loader cassette  318 , semiconductor wafers have the room temperature of about 20° C. 
     The conveying arm unit  320  includes a base arm  322 , a delivery arm  324  and motors  326  and  328 . The motor  326  is connected to one end of the base arm  322  and turns (swings or pivots) the base arm  322  on the axis thereof. The motor  328  is connected to the other end of the base arm  322  and to one end of the delivery arm  324  and turns (swings or pivots) the delivery arm  324  on the axis thereof. The semiconductor wafer  314  is placed on the other end of the delivery arm  324 . The delivery arm  324  is connected to a controller  334  via a flexible tube  336 . The base arm  322  and the delivery arm  324  are driven independently from each other, so that the semiconductor wafer  314  can be delivered only by the delivery arm  324 . 
     As shown in  FIG. 18 , the heating chamber  310  is provided with an elevation motor  330  and elevation pins  332 . The elevation pins  332  extend vertically through the heating chamber  310  to reach the bottom surface of the semiconductor wafer  314 . The elevation motor  330  drives the elevation pins  332  up and down so that the semiconductor wafer  314  is delivered between the delivery arm  324  and the hot plate (not shown) in the heating chamber  310 . In the same manner as the heating chamber  310 , the cooling chamber  312  is provided with an elevation motor (not shown) and elevation pins (not shown), as well. 
       FIG. 19  shows the inside structure of the delivery arm  324  of the conveying arm unit  320  according to the fourth preferred embodiment of the present invention. The delivery arm  324  is provided therein with a heating coil  388 , a cooling pipe  370  and a thermocouple  372 . The heating coil  388  is connected via a flexible wire  390  shown in  FIG. 19 , to the controller  334 . The ends of the cooling pipe  370  are connected via the flexible tube  336  shown in  FIG. 18 , to the controller  334 . The thermocouple  372  is connected via a flexible wire  374  shown in  FIG. 19 , to the controller  334 . The flexible wires  374  and  390 , and the cooling pipe  370  are included in the flexible tube  336  so that the flexible wires  374  and  390  and the cooling pipe  370  do not block the passage of the base arm  322  and the delivery arm  324 . 
     The heating coil  388  generates heat in response to electric current supplied from the controller  334  through the flexible wire  390 , so that the delivery arm  324  can be heated to 450° C. The thermocouple  372  detects the temperature of the delivery arm  324  and supplies the corresponding output signal to the controller  334  through the flexible wire  374 . In response to the output signal of the thermocouple  372 , the controller  334  controls the amount of current to be supplied through the flexible wire  390  to the heating coil  388 , so that the delivery arm  324  is controlled at an optimum temperature. 
     Cooling liquid, such as water travels in the cooling pipe  370  so that the delivery arm  324  can be controlled in temperature to about 20° C. In response to the output signal of the thermocouple  372 , the controller  334  controls the temperature of the cooling liquid traveling in the cooling pipe  370 , so that the delivery arm  324  is controlled at an optimum temperature. 
     The controller  334  selectively operates a current source (not shown), supplying electric current to the heating coil  388 , and a pump (not shown), supplying the cooling liquid to the cooling pipe  370 . In other words, the controller  334  controls the delivery arm  324  to have the optimum temperature all the time during delivery of the semiconductor wafer  314 . 
       FIG. 20  shows the temperature variation of the semiconductor wafer  314 , which is processed in the sinter furnace according to the fourth preferred embodiment of the present invention. 
     In operation, first, the delivery arm  324  of the conveying arm unit  320  delivers the semiconductor wafer  314  from the loader cassette  316  to the intermediate chamber  338 . When the semiconductor wafer  314  is put on the delivery arm  324 , the delivery arm  324  is controlled in temperature at 20° C., corresponding to the current temperature of the semiconductor wafer  314 . In other words, there is no temperature difference between the semiconductor wafer  314  and the delivery arm  324 . Once the semiconductor wafer  314  is set on the delivery arm  324 , the controller  334  starts operating the heating coil  388  to control the temperature of the delivery arm  324  until 150° C., which is corresponding to the temperature in the intermediate chamber  338 . In the intermediate chamber  338 , the semiconductor wafer  314  is controlled in temperature at 150° C. in a nitrogen gas atmosphere for five minutes. 
     Next, the delivery arm  324  delivers the semiconductor wafer  314  from the intermediate chamber  338  to the heating chamber  310 . When the semiconductor wafer  314  is put on the delivery am,  324 , the delivery arm  324  has been controlled in temperature at 150° C., which is corresponding to the current temperature of the semiconductor wafer  314 . During the delivery from the intermediate chamber  338  to the heating chamber  310 , the controller  334  operates the heating coil  338  to control the temperature of the delivery arm  324  unit 450° C., which is corresponding to the temperature in the heating chamber  310 . Thus, no temperature difference is made when the semiconductor wafer  314  is delivered in the heating chamber  310 . In the heating chamber  310 , the semiconductor wafer  314  is heated on the hot plate (not shown) in a nitrogen gas atmosphere for five minutes. 
     After the heating treatment, the delivery arm  324  delivers the semiconductor wafer  314  to the intermediate chamber  338 . When the semiconductor wafer  314  of 450° C. is put on the delivery arm  324 , the delivery arm  324  has been controlled at 450° C. During the delivery between the heating chamber  310  and the intermediate chamber  338 , the controller  334  operates the cooling system ( 370 ) to control the temperature of the delivery arm  324  until 150° C., which is corresponding to the temperature in the intermediate chamber  338 . In the intermediate chamber  338 , the semiconductor wafer  314  is controlled in temperature at 150° C. in a nitrogen gas atmosphere for five minutes. 
     After the intermediate treatment, the delivery arm  324  delivers the semiconductor wafer  314  to the cooling chamber  312 . When the semiconductor wafer  314  is placed on the delivery arm  324 , the delivery arm  324  has been controlled in temperature at 150° C., which is corresponding to the current temperature of the semiconductor wafer  314 . During the delivery between the intermediate chamber  338  and the cooling chamber  312 , the controller  334  controls the temperature of the delivery arm  324  until 20 C., which is corresponding to the temperature in the cooling chamber  312 . In the cooling chamber  312 , the semiconductor wafer  314  is cooled on the cool plate (not shown) at 20° C. in a nitrogen gas atmosphere for five minutes. 
     After the cooling treatment, the semiconductor wafer  314  is delivered to the un-loader cassette  318 . When the semiconductor wafer  314  is set on the delivery arm  324 , the delivery arm  324  has been controlled in temperature at 20° C., which is corresponding to the current temperature of the semiconductor wafer  314 . 
     As described above, according to the fourth preferred embodiment of the present invention, the delivery arm  324  is controlled to have the same temperature as the semiconductor wafer  314  every time when those are touch with each other. In other words, no temperature difference is made between the semiconductor wafer  314  and the delivery arm  324 . Therefore, it is prevented that the semiconductor wafer  314  is broken due to heat-shock (rapid heating) or cool-shock (rapid cooling). 
     It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended with the meaning and range of equivalents of the appended claims. 
     The present invention is applicable not only to a single wafer processing type, but also, to a batch processing type of sinter furnace. The present invention is applicable not only to a sinter furnace, but also, to a CVD apparatus, a dry-etching apparatus, and the like.