Abstract:
In a resist processing apparatus, a thermocouple wafer substrate is set to stand by in the predetermined position in advance. When the measurement of the temperature of a substrate in a thermal processing unit is necessary, the thermocouple wafer is carried into the thermal processing unit. After the thermocouple wafer carried in the thermal processing unit is heat-treated, the temperature of the heat-treated thermocouple wafer sensed by a heat sensor is measured. Thus, the temperature of the heat-treated substrate can be measured with accuracy, with the smallest influence available on a loss of time in operation of the apparatus, and without any human error.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a resist processing apparatus for coating a substrate with a resist, sending the substrate to an aligner and developing the substrate received from the aligner, and a measuring method therein. 
     In a photo-resist process of semiconductor device fabrication, a resist solution is coated on a surface of a substrate such as a semiconductor wafer, which is called a wafer hereinafter, to form a resist film. After the predetermined pattern is exposed on the resist film, the substrate is supplied with a developing solution and developed. A resist processing apparatus and an aligner have been used so far in a series of the above processes. 
     The resist processing apparatus is provided with processing units which individually perform a series of processes necessary for coating and developing, that is, an adhesion unit, a coating unit, a thermal processing unit, a developing unit and the like. An adhesion unit performs adhesion treatment to improve resist fixing. A coating unit coats a substrate with resist solution. A thermal processing unit heats a substrate coated with resist solution to cure a resist film. Another thermal processing unit heats an exposed substrate at the predetermined temperature. A developing unit develops an exposed substrate. A carrier unit is used for carrying a wafer between each processing unit or carrying a wafer into and out from each processing unit, a carrier unit, for example, being able to move while holding a wafer. 
     Temperature control in the above thermal processing unit is very important. Poor temperature control causes poor film thickness and poor developing of resist. Therefore, not the temperature in a thermal processing unit, but the real temperature of a wafer in a thermal processing unit may be measured using, for example, a wafer in which a thermocouple is buried. 
     More concretely, when measurement is necessary, the real operation of the resist processing unit is suspended and a cover of the thermal processing unit is opened. After the thermocouple wafer is placed in a position in which wafers are heat-treated in the thermal processing unit, the thermocouple wafer is heat-treated in an ordinary heat treatment. In a temperature measuring apparatus, the temperature is measured through the thermocouple buried in the thermocouple wafer and a measured result is processed. That is, the thermocouple wafer is not measured in the thermal processing unit. This is because a plurality of cables coupled between the thermocouple wafer and the temperature measuring apparatus interfere with normal shutting of the cover in the thermal processing unit. Additionally, a setting error cannot be prevented because the thermocouple wafer is manually placed in the thermal processing unit. 
     A series of the above processes is, however, performed manually so that it is difficult to exactly measure the temperature of a heat-treated wafer. 
     Moreover, the manual measurement described above requires suspension of the real operation for a considerable time, which results in a loss in apparatus operation time. 
     There is another disadvantage that the above measurement may lead to some human error. For example, a thermocouple wafer may be dropped from tweezers and be broken. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is provided in view of the aforesaid disadvantages. 
     An object of the present invention is to provide a resist processing apparatus which can accurately measure the temperature of a heat-treated substrate and a measuring method therein. 
     Another object of the present invention is to provide a resist processing apparatus which can measure the temperature of a heat-treated substrate with the smallest possible loss of apparatus operation time and a measuring method therein. 
     Still another object of the present invention is to provide a resist processing apparatus which can measure the temperature of a heat-treated substrate without any human error and a measuring method therein. 
     To attain the above-described objects, a resist processing apparatus in the first aspect of the present invention coats a substrate with a resist, sends the substrate to an aligner and develops the substrate received from the aligner. The resist processing apparatus is provided with a thermal processing unit for heat-treating the substrate received at least from the aligner, a carrier mechanism for carrying the substrate at least between the aligner and the thermal processing unit, a buffer unit where a heat-sensing substrate provided with a heat sensor stands by, and a measuring means disposed in the thermal processing unit for measuring the temperature of the heat-sensing substrate sensed by the heat sensor, the heat-sensing substrate being heat-treated in the thermal processing unit after being carried from the buffer unit to the thermal processing unit by the carrier mechanism. 
     A resist processing apparatus in the second aspect of the present invention coats a substrate with a resist, sends the substrate to an aligner and develops the substrate received from the aligner. The resist processing apparatus is provided with a thermal processing unit for heat-treating the substrate, a buffer unit where a heat-sensing substrate provided with a heat sensor and a storage element for storing a result sensed by the heat sensor stands by, and a reading means for reading the sensed result stored in the storage element of the heat-sensing substrate heat-treated in the thermal processing unit. 
     A resist processing apparatus in the third aspect of the present invention coats a substrate with a resist, sends the substrate to an aligner and develops the substrate received from the aligner. The resist processing apparatus is provided with a thermal processing unit for heat-treating the substrate, a buffer unit where a heat-sensing substrate provided with a heat sensor and a transmitter for transmitting by radio a result sensed by the heat sensor stands by, and a receiving means for receiving the sensed result transmitted from the transmitter of the heat-sensing substrate heat-treated in the thermal processing unit. 
     A measuring method in the fourth aspect of the present invention is a measuring method with the following steps in an apparatus for coating a substrate with a resist, sending the substrate to an aligner and developing the substrate received from the aligner. A heat-sensing substrate provided with a heat sensor needs to be set to stand by in advance. The heat-sensing substrate is carried in a thermal processing unit, which heat-treats a substrate received from the aligner, in the predetermined timing. The carried heat-sensing substrate is heat-treated in the thermal processing unit. In addition, the temperature of the heat-treated heat-sensing substrate sensed by a heat sensor is measured. 
     A measuring method in the fifth aspect of the present invention is a measuring method with the following steps in an apparatus for coating a substrate with a resist, sending the substrate to an aligner and developing the substrate received from the aligner. A heat-sensing substrate provided with a heat sensor and a storage element for storing a result sensed by the heat sensor needs to be set to stand by in advance. The heat-sensing substrate is carried in a thermal processing unit, which heat-treats a substrate received form the aligner, in the predetermined timing. The carried heat-sensing substrate is heat-treated in the thermal processing unit. In addition, the sensed result stored in the storage element of the heat-treated heat-sensing substrate is read. 
     A measuring method in the sixth aspect of the present invention is a measuring method with the following steps in an apparatus for coating a substrate with a resist, sending the substrate to an aligner and developing the substrate received from the aligner. A heat-sensing substrate provided with a heat sensor and a transmitter for transmitting by radio a result sensed by the heat sensor needs to be set to stand by in advance. The heat-sensing substrate is carried in a thermal processing unit, which heat-treats a substrate received from the aligner, in the predetermined timing. The carried heat-sensing substrate is heat-treated in the thermal processing unit. In addition, the sensed result transmitted from the transmitter of the heat-treated heat-sensing substrate is received. 
     In the present invention, a heat-sensing substrate is set to stand by in advance. When the measurement of the temperature of a substrate in a thermal processing unit is required, the heat-sensing substrate is carried in the thermal processing unit. After the heat-sensing substrate is heat-treated in the thermal processing unit, the temperature of the heat-treated heat-sensing substrate sensed by a heat sensor is measured. Thus, the temperature of the heat-treated substrate can be measured with accuracy, with the smallest loss of apparatus operation time, and without any human error. 
     The above-described objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. 
     FIG. 1 is a plan view of a resist processing apparatus according to an embodiment of the present invention; 
     FIG. 2 is a front view of the resist processing apparatus shown in FIG. 1; 
     FIG. 3 is a rear view of the resist processing apparatus shown in FIG. 1; 
     FIG. 4 is a front view of a thermocouple wafer according to an embodiment of the present invention; 
     FIG. 5 is a plan view of the thermocouple wafer shown in FIG. 4; 
     FIG. 6 is a front view of a chilling hot plate according to an embodiment of the present invention; 
     FIG. 7 is a fragmentary enlarged view of the chilling hot plate shown in FIG. 6; 
     FIG. 8 is a fragmentary enlarged view of the chilling hot plate shown in FIG. 6; 
     FIG. 9 is a front view of a thermocouple wafer according to another embodiment; 
     FIG. 10 is a block diagram showing a temperature data processing system when using the thermocouple wafer shown in FIG. 9; 
     FIG. 11 is a front view of a thermocouple wafer according to still another embodiment; 
     FIG. 12 is a block diagram showing a temperature data processing system when using the thermocouple wafer shown in FIG. 11; and 
     FIG. 13 is a plan view showing another embodiment of a resist processing apparatus to which the present invention is applicable. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain terminology will be used in the following description for convenience of reference only and will not be limiting. The words “up”, “down”, “right” and “left” will designate directions in the drawings to which reference is made. The words “in” and “out” will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. Such terminology will include derivatives and words of similar import. 
     As shown in FIGS. 1 to  3 , a resist processing apparatus  1  is provided with a cassette station  10 , a process station  11  and an interface unit  12 , all of which are integrally connected. In the cassette station  10 , more than one wafer W, for example, twenty-five wafers per cassette C are carried into the resist processing unit  1  from the outside and carried out from the resist processing unit  1  to the outside. The wafer W is carried into and out from the cassette C. In the process station  11 , various kinds of processing units are multi-tiered in a predetermined position. Each processing unit applies a predetermined treatment to wafers W one by one in the process of coating and developing. In the interface unit  12 , the wafer W is sent to and received from an aligner  13  which is disposed adjacent to the resist processing apparatus  1 . 
     In the cassette station  10 , as shown in FIG. 1, more than one, for example, four cassettes C are disposed respectively with a way in/out for each wafer W opening to the side of the process station  11  in a line in an X-direction (vertical direction in FIG. 1) in the position of each positioning projection  20   a  on a cassette stand  20  where cassettes are placed. A wafer carrier  21 , which can move in the direction of disposition of cassettes C (X-direction) and in a direction of disposition of wafers W contained in the cassette C (Z-direction; vertical direction), is movable along a carrier path  21   a  to be able to selectively access each cassette C. 
     The wafer carrier  21  is rotatable in a θ-direction and can access an alignment unit (ALIM) and an extension unit (EXT) which belong to a multi-tiered units of a third processing unit group G 3  in the side of the process station  11  as described hereinafter. 
     In the process station  11 , as shown in FIG. 1, a carrier unit  22  with a vertical carrier system is placed in a center portion. Around the carrier unit  22 , one set or more than one set of various kinds of processing units are multi-tiered so as to compose processing unit groups. In the resist processing apparatus  1 , five processing unit groups G 1 , G 2 , G 3 , G 4  and G 5  can be disposed. A first and a second processing unit group, G 1  and G 2 , can be disposed in the front side of a system, the third processing unit group G 3  can be disposed adjacent to the cassette station  10 , a fourth processing unit group G 4  can be disposed adjacent to the interface unit  12 , and a fifth processing unit group G 5  shown in a broken line can be disposed in the back side. The carrier unit  22  which is rotatable in a θ-direction and movable in a Z-direction can carry the wafer W into and out from each processing unit. 
     In the first processing unit group G 1 , as shown in FIG. 2, two spinner-type processing units in which a wafer W is mounted on a spin chuck in a cup CP in order to perform the predetermined processing, for example, a resist solution coating unit (COT) and developing unit (DEV) are dual stacked in that order from the bottom. In the second processing unit group G 2  just like the first processing unit group G 1 , two spinner-type processing units, for example, a resist solution coating unit (COT) and developing unit (DEV) are dual stacked in that order from the bottom. 
     As shown in FIG. 2, in the upper portion of the resist processing unit  1 , a high efficiency filter  23  such as a ULPA filter is disposed in each of the above-described three zones, that is, the cassette station  10 , the process station  11 , and the interface unit  12 . Particles and organic components of air supplied from above the high efficiency filter  23  are collected and removed. Therefore, through the high efficiency filter  23 , pure air flowing downward is supplied to the cassette stand  20 , the carrier path  21   a  of the wafer carrier  21 , the first and the second processing unit groups G 1  and G 2  described above, and the third to the fifth processing unit groups G 3 , G 4  and G 5  and the interface unit  12  which are described below in the direction of a solid line arrow or a dotted line arrow. 
     In the third processing unit group G 3 , as shown in FIG. 3, oven-type processing units in which the wafer W is mounted on a stand (not shown) in order to perform the predetermined processing, for example, a cooling unit (COL) for cooling processing, an adhesion unit (AD) for adhesion processing to improve fixing of the resist, an alignment unit (ALIM) for positioning, an extension unit (EXT), a prebaking unit (PREBAKE) for heat processing before coating, and a postbaking unit (POBAKE) are, for instance, eight-tiered in that order from the bottom. 
     Similarly, in the fourth processing unit group G 4 , as shown in FIG. 3, oven-type processing units in which the wafer W is mounted on a stand (not shown) in order to perform the predetermined processing, for example, a cooling unit (COL) for cooling processing, an extension &amp; cooling unit (EXTCOL) serving both as extension unit and cooling unit, an adhesion unit (AD), a prebaking unit (PREBAKE), and a postbaking unit (POBAKE) are, for instance, eight-tiered in that order from the bottom. 
     As described above, the cooling unit (COL) and the extension &amp; cooling unit (EXCOL), both requiring a low processing temperature, are disposed below, and the prebaking unit (PREBAKE), the postbaking unit (POBAKE) and the adhesion unit (AD), all three requiring a high processing temperature, are disposed above, thereby reducing thermal mutual interference between units. 
     As shown in FIG. 1, the interface unit  12  has the same dimension in the direction of depth (X-direction) as the process station  11 , but a dimension in the direction of width smaller than the process station  11 . As shown in FIGS. 1 and 2, a transportable pickup cassette CR and a fixed buffer cassette BR are dual tiered in the front side of the interface unit  12 , and a peripheral exposing unit  24  is disposed in the back side thereof. In the transportable pickup cassette CR and the fixed buffer cassette BR, at least one thermocouple wafer DW, described hereinafter, is set to stand by in advance. 
     In the center portion of the interface unit  12 , a wafer carrier  25  is disposed. The wafer carrier  25  moves in an X-direction and in a Z-direction (vertical direction) so as to be able to access both cassettes CR and BR, and the peripheral exposing unit  24 . The wafer carrier  25  is also rotatable in a θ-direction to be able to access the extension unit (EXT) which belongs to the fourth processing unit group G 4  in the side of the process station  11 , and moreover a wafer delivery stand (not shown) in the side of the adjacent aligner  13 . 
     As shown in FIGS. 4 and 5, in the thermocouple wafer DW, a thermocouple  32  serving as a heat sensor is buried in a body  31  which is basically a identical member to the wafer W. On a surface of the body  31 , a terminal  33  is disposed. A pin for measurement described hereinafter touches the terminal  33  and a result sensed by the thermocouple  32  is outputted to the outside through the pin for measurement. The thermocouple  32  and the terminal  33  are electrically connected by wiring  34 . Temperature distribution can be known by burying more than one thermocouple  32  in the body  31 . 
     As shown in FIG. 6, as the postbaking unit (POBAKE) in the third processing unit group G 3  and the fourth processing unit group G 4 , a chilling hot plate  41  is used for more accurate temperature control. 
     In the chilling hot plate  41 , a thermal processing unit  43  and a cooling unit  44  are disposed adjacently on a base  42 . 
     In the thermal processing unit  43 , a supporting pin  45  which supports the wafer W is disposed so as to be able to both protrude from and sink into a surface of a hot plate  46 . The supporting pin  45  moves vertically by means of a drive unit  47 . When the wafer W is received from the carrier unit  22  and the like, the supporting pin  45  comes out from the surface of the hot plate  46  by the operation of the drive unit  47 . When the wafer W is heat-treated, the supporting pin  45  sinks into the hot plate  46  as shown in FIG.  6 . Moreover, a cover  48  is disposed to cover the upper portion of the wafer W. The cover  48  can be moved vertically by a drive unit (not shown). When the wafer W is sent to and received from the thermal processing unit  43 , the cover  48  is opened. When the wafer W is heat-treated, the cover  48  is shut to form a processing space between the hot plate  46  and the cover  48  as shown in FIG.  6 . On the top of the cover  48 , an exhaust vent  49  is provided. Inside the cover  48 , a pin for measurement  50  is disposed so as to touch the terminal  33  of the thermocouple wafer DW when the cover  48  is shut. 
     When the cover  48  is shut, a point of the pin for measurement  50  does not touch a surface of the ordinary wafer W as shown in FIG. 7, but touches the terminal  33  of the thermocouple wafer DW as shown in FIG. 8 because the terminal  33  protrudes from the surface. From such a structure as the above, it is possible to take data from the thermocouple wafer DW without any special operation or control. 
     As shown in FIG. 6, the pin for measurement  50  is connected to a process unit  51  composed of a personal computer, for example, which processes data inputted through the pin  50 . The process unit  51  sends the thermocouple wafer DW from a standby position into the thermal processing unit  43  at the predetermined timing, measures the temperature, and displays a result on a display unit  52  composed of a liquid crystal panel, for example. 
     The above-described predetermined timing required for measuring the temperature using the thermocouple wafer DW is 
     1) when maintenance is performed, 
     2) a unit of each lot of the wafer W, 
     3) when malfunction of the wafer is detected, and the like. 
     The malfunction of the wafer means poor exposure, poor film thickness of the resist, or the like. 
     As shown in FIG. 6, the cooling unit  44  in the chilling hot plate  41 , a chill arm  53  is formed to be accessible into the thermal processing unit  43  by the operation of a drive unit  54 . 
     In the chilling hot plate  43  structured as described above, the wafer W received from the carrier unit  22  on the left side in FIG. 6 is heat-treated in the thermal processing unit  43  and then sent to the cooling unit  44  to be cooled, and subsequently the cooled wafer W is transferred to the carrier unit  22  through the thermal processing unit  43 . 
     In the resist processing apparatus with the above-described structure, the temperature measurement by the thermocouple wafer DW is performed in the following way. 
     When the temperature measurement is necessary, under the control of the process unit  51 , the thermo-couple wafer DW, which stands by in the buffer cassette BR in the interface unit  12 , for example, is carried into the postbaking unit (POBAKE) composed of the chilling hot plate  41  through the wafer carrier  25 , the extension unit (EXT) and the carrier unit  22  in that order. The above course is the same as the course of the exposed ordinary wafer W. In other words, a buffer unit for the thermocouple wafer DW is disposed in a temperature atmosphere on a carrier path between the aligner  13  and the postbaking unit (POBAKE) so that the thermocouple wafer DW can follow the same course as the ordinary wafer W and be carried into the postbaking unit (POBAKE). As a result, the thermocouple wafer DW has the same heat history as the ordinary wafer W. 
     After the thermocouple wafer DW is carried into the chilling hot plate  41 , the cover  48  is shut. At that moment, the pin for measurement  50  disposed inside the cover  48  touches the terminal  33  of the thermocouple wafer DW. 
     Subsequently the thermocouple wafer DW is heated under the same heating conditions as the ordinary wafer W in the chilling hot plate  41 . A result sensed by the thermocouple  32  of the thermocouple wafer DW is inputted to the process unit  51  through the terminal  33  and the pin for measurement  50 . A measured data processed by the process unit  51  is displayed in the display unit  52 . 
     As described above, the thermocouple wafer DW has the same heat history as the ordinary wafer W. Thus the measured result of the thermocouple wafer DW is considered to be the same as that of the ordinary wafer W. In other words, the temperature of the wafer W heat-treated according to the present invention is accurately detected. And the obtained result is utilized for the temperature control during thermal processing, thereby reducing occurrence of poor exposure of a wafer, poor film thickness of a resist and the like. 
     Next, another embodiment of the present invention is described. 
     In the embodiment, as shown in FIG. 9, a thermo-couple  91  is buried in the thermocouple wafer DW and a storage element  92  to store a result sensed by the thermocouple  91  is also provided in the thermocouple wafer DW. When the thermocouple wafer DW is made of the same silicon as a wafer W, the storage element  92  can be formed using the dummy substrate as a raw material of the thermocouple wafer DW, and a separately formed storage element  92  can be also buried in the thermocouple wafer DW. The data stored in the storage element  92  is outputted to the outside by a terminal  93 . 
     On the other hand, for example, in either of the third or the fourth processing unit groups G 3  or G 4  close to the thermal processing unit, a reading unit is disposed. The reading unit is provided with a pin for measurement  1001  which touches the terminal  93  to input data, a process unit  1002  composed of a personal computer, for example, which processes the data inputted through the pin  1001 , and a display unit  1003  composed of a liquid crystal panel, for example, which displays the result. 
     Next, still another embodiment of the present invention is described. 
     In the embodiment, as shown in FIG. 11, a thermo-couple  1101  is buried in the thermocouple wafer DW and a transmitter  1102  which transmits by radio a result sensed by the thermocouple  1101  is also buried in the thermocouple wafer DW. The transmitter  1102  preferably uses infrared rays as radio, whereby a circuit is composed of heat-resistant parts. 
     On the other hand, for example, in either of the third or the fourth processing unit groups G 3  or G 4  close to the thermal processing unit, a receiving and data processing unit is disposed. As shown in FIG. 12, the receiving and data processing unit is provided with a receiving unit  1201  consisting of light receiving elements in case of infrared rays, for example, which receives a signal from the transmitter  1102 , a process unit  1202  consisting of a personal computer, for example, which processes the data inputted through the receiving unit  1201 , and a display unit  1203  consisting of a liquid crystal panel, for example, which displays the result. 
     In the above embodiments, the process station  11  has the carrier unit  22  with a vertical carrier system. However, as shown in FIG. 13, the present invention is applicable to a resist processing apparatus provided with a process station  11 ′ in which a carrier unit  22 ′ is movable in a Y-direction and process units  1302  such as a coating unit and a developing unit are disposed on both sides of a moving path  1301  of the carrier unit  22 ′. 
     In the above embodiments, examples of using a wafer W as a substrate are described, but the present invention is not limited to the above-described embodiments. The present invention is also applicable to an embodiment in which an LCD substrate is used. 
     In the above embodiments, examples of using a chilling hot plate as a thermal processing unit are described, but the present invention is not limited to the above-described embodiments. The present invention is also applicable to an embodiment in which an LHP (Low Hot Plate) or an HHP (High Hot Plate) is used. 
     The above-described embodiments have the intention of clarifying technical meaning of the present invention. Therefore, the present invention is not intended to be limited to the above concrete embodiments or to be interpreted in a narrow sense, and various changes may be made therein without departing from the spirit of the present invention and within the meaning of the claims.