JP2015177024A - Heat treatment method of substrate, heat treatment apparatus and computer readable recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the temperature of a wafer more precisely.SOLUTION: A heat treatment method of a wafer W includes (A) a step of measuring the clearance between a heat plate 113 for giving heat to the wafer W, and the wafer W arranged above the heat plate 113 by means of distance sensors 118a, 118b, 118d, (B) a step of measuring the temperature of the heat plate 113 by means of temperature sensors 117a, 117b, 117d, (C) a step of calculating the estimation temperature of the wafer W arranged above the heat plate 113, on the basis of the clearance measured in step A and the temperature of the heat plate 113 measured in step B, and (D) a step of adjusting the temperature of the heat plate 113 on the basis of the difference between the estimation temperature calculated in step C, and the target temperature of the wafer W.

Description

  The present disclosure relates to a method for heat treating a substrate, a heat treatment apparatus, and a computer-readable recording medium.

  Patent document 1 is disclosing the heat processing apparatus provided with the hot platen which heats the board | substrate arrange | positioned upwards. For example, when the substrate is finely processed using a photolithography technique, the heat treatment apparatus performs heat treatment (pre-baking) for evaporating the solvent of the resist solution applied to the surface of the substrate or exposure processing, A heat treatment (post-exposure baking) for promoting the chemical reaction of the coating film and a heat treatment (post-baking) after the development treatment are performed.

JP 2002-353111 A

  Currently, a microfabrication process for forming a concavo-convex pattern (for example, a resist pattern) on the surface of a substrate (for example, a semiconductor wafer, a glass wafer, or other various wafers) using a photolithography technique is widely performed. In the above heat treatment apparatus, it is difficult to directly attach the temperature sensor to the substrate to be processed due to its configuration. Therefore, by measuring the temperature of the hot plate with the temperature sensor and adjusting the temperature of the hot plate, indirectly The temperature of the board is managed.

  In recent years, with further miniaturization of the uneven pattern, there has been an increasing demand for uniformly heat-treating various materials arranged on the substrate surface within the substrate surface. Therefore, it is important to control the temperature of the substrate with higher accuracy.

  Thus, the present disclosure describes a method, a heat treatment apparatus, and a computer-readable recording medium for heat-treating a substrate that can control the temperature of the substrate with higher accuracy.

  A method of heat-treating a substrate according to one aspect of the present disclosure includes: (A) measuring a separation distance between a hot plate that applies heat to the substrate and a substrate disposed above the hot plate by a distance sensor; , (B) measuring the temperature of the hot plate with a temperature sensor, and (C) based on the separation distance measured in the above A term and the temperature of the hot plate measured in the above B term. Calculating the estimated temperature of the substrate disposed above; and (D) adjusting the temperature of the hot plate based on the difference between the estimated temperature calculated in the above-mentioned item C and the target temperature of the substrate. Including.

  In the method of heat-treating a substrate according to one aspect of the present disclosure, the distance between the hot plate and the substrate is measured by a distance sensor. Therefore, the temperature generated in the substrate by the heat from the hot plate can be estimated more accurately by calculation. Therefore, the temperature of the substrate can be controlled with higher accuracy by adjusting the temperature of the hot plate so that the estimated temperature of the substrate approaches the target temperature.

  The above items A to D may be repeated until a predetermined period elapses. In this case, for example, the temperature of the substrate can be controlled so that the temperature of the substrate changes along the target temperature from the start to the end of the heat treatment of the substrate. In addition, since the separation distance between the hot plate and the substrate is repeatedly measured, even if the substrate is deformed by heat from the hot plate, the separation distance between the hot plate and the substrate that has changed with the deformation is immediately estimated by the substrate. Reflected in temperature. Therefore, the temperature of the substrate can be controlled with higher accuracy.

  The above items B to D may be repeated until a predetermined period elapses. In this case, for example, the temperature of the substrate can be controlled so that the temperature of the substrate changes along the target temperature from the start to the end of the heat treatment of the substrate.

  The hot plate has a plurality of regions where the temperature can be adjusted independently, and a distance sensor and a temperature sensor are arranged for each of the plurality of regions, and the above items A to D are performed for each of the plurality of regions. Also good. In this case, since the distance sensors are present at a plurality of locations on the hot plate, the board is warped, for example, the board rides on a foreign object existing on the hot plate, and the board is disposed inclined with respect to the hot plate. Even if it is a case, the temperature of a hot plate is adjusted for every area | region of a hot plate according to the state of such a board | substrate. Therefore, the temperature of the substrate can be controlled with higher accuracy.

  The plurality of regions may be arranged in the circumferential direction. In this case, a plurality of linear distances between the hot plate and the substrate are acquired in the circumferential direction. Therefore, the inclination as the whole substrate can be grasped. Therefore, for example, when the substrate rides on a foreign object existing on the hot plate and the substrate is disposed to be inclined with respect to the hot plate, the temperature of the substrate can be controlled particularly accurately.

  The estimated temperature may be calculated using a temperature change amount of the substrate obtained by dividing a heat transfer amount per predetermined time out of heat transferred from the hot plate to the substrate via air.

  A heat treatment apparatus according to another aspect of the present disclosure includes a hot plate that applies heat to the substrate, a support member that supports the substrate above the hot plate, and a distance sensor that measures a separation distance between the hot plate and the substrate. And a temperature sensor that measures the temperature of the hot plate and a control unit, the control unit (A) control that causes the distance sensor to measure the distance, and (B) control that causes the temperature sensor to measure the temperature of the hot plate. And (C) control for calculating an estimated temperature of the substrate disposed above the hot plate based on the separation distance measured by the control A and the temperature of the hot plate measured by the control B; D) Control for adjusting the temperature of the hot plate based on the difference between the estimated temperature calculated in the control C and the target temperature of the substrate is executed.

  In the heat treatment apparatus according to another aspect of the present disclosure, the control unit causes the distance sensor to measure the separation distance between the hot plate and the substrate. Therefore, the temperature generated in the substrate by the heat from the hot plate can be estimated more accurately by calculation. Therefore, the temperature of the substrate can be controlled with higher accuracy by adjusting the temperature of the hot plate so that the estimated temperature of the substrate approaches the target temperature.

  The control unit may repeatedly execute the controls A to D until a predetermined period elapses. In this case, for example, the temperature of the substrate can be controlled so that the temperature of the substrate changes along the target temperature from the start to the end of the heat treatment of the substrate. In addition, since the separation distance between the hot plate and the substrate is repeatedly measured, even if the substrate is deformed by heat from the hot plate, the separation distance between the hot plate and the substrate that has changed with the deformation is immediately estimated by the substrate. Reflected in temperature. Therefore, the temperature of the substrate can be controlled with higher accuracy.

  The control unit may repeatedly execute the controls B to D until a predetermined period elapses. In this case, for example, the temperature of the substrate can be controlled so that the temperature of the substrate changes along the target temperature from the start to the end of the heat treatment of the substrate.

  The hot plate has a plurality of regions that can be adjusted in temperature independently, and a distance sensor and a temperature sensor are arranged for each of the plurality of regions, and the control unit executes the control A to D for each of the plurality of regions. May be. In this case, since the distance sensors are present at a plurality of locations on the hot plate, even if the board is warped or the board is inclined with respect to the hot plate, such a board is used. The temperature of the hot plate is adjusted for each region of the hot plate according to the state. Therefore, the temperature of the substrate can be controlled with higher accuracy.

  The plurality of regions may be arranged in the circumferential direction. In this case, a plurality of linear distances between the hot plate and the substrate are acquired in the circumferential direction. Therefore, the inclination as the whole substrate can be grasped. Therefore, for example, when the substrate rides on a foreign object existing on the hot plate and the substrate is disposed to be inclined with respect to the hot plate, the temperature of the substrate can be controlled particularly accurately.

  A computer-readable recording medium according to another aspect of the present disclosure records a program for causing a heat treatment apparatus to execute the above method. The computer-readable recording medium according to another aspect of the present disclosure can control the temperature of the substrate with higher accuracy as in the above method. In this specification, a computer-readable recording medium includes a non-transitory tangible medium (non-transitory computer recording medium) (for example, various main storage devices or auxiliary storage devices) and a propagation signal (transitory computer recording medium). (E.g., a data signal that can be provided over a network).

  According to the method, the heat treatment apparatus, and the computer-readable recording medium for heat treating a substrate according to the present disclosure, the temperature of the substrate can be controlled with higher accuracy.

FIG. 1 is a perspective view showing a coating / developing system. 2 is a cross-sectional view taken along line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view of the heating / cooling unit as viewed from the side. FIG. 5 is a sectional view of the heating / cooling unit as seen from above. FIG. 6 is a cross-sectional view of the hot plate viewed from the side. FIG. 7 is a view of the hot plate seen from above. FIG. 8 is a flowchart for explaining the wafer temperature adjustment procedure. FIG. 9 is a diagram showing how the wafer temperature changes with respect to the processing time. FIG. 10 is a flowchart for explaining the wafer temperature adjustment procedure.

  Embodiments of the present invention will be described with reference to the drawings. However, the following embodiments are exemplifications for explaining the present invention and are not intended to limit the present invention to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

[Configuration of coating and developing equipment]
First, an outline of the configuration of the coating / developing apparatus 1 shown in FIGS. 1 to 3 will be described. The coating / developing apparatus 1 performs a process of coating a resist material on the surface of the wafer W to form a resist film before the exposure process by the exposure apparatus E1. The coating / developing apparatus 1 performs a development process on the resist film formed on the surface of the wafer W after the exposure process by the exposure apparatus E1. In the present embodiment, the wafer W has a disk shape, but a wafer having a part of a circle cut out or a shape other than a circle such as a polygon may be used. The wafer W may be, for example, a semiconductor substrate, a glass substrate, a mask substrate, an FPD (Flat Panel Display) substrate, or other various substrates.

  As shown in FIGS. 1 and 2, the coating / developing apparatus 1 includes a carrier block BK1, a processing block BK2, an interface block BK3, and a control unit CU that functions as a control unit of the coating / developing apparatus 1. . In the present embodiment, the carrier block BK1, the processing block BK2, the interface block BK3, and the exposure apparatus E1 are arranged in series in this order.

  As shown in FIG. 1 and FIG. 3, the carrier block BK1 includes a carrier station 12 and a carry-in / carry-out unit 13. The carrier station 12 supports a plurality of carriers 11. The carrier 11 accommodates a plurality of wafers W in a sealed state. The carrier 11 has an open / close door (not shown) for taking in and out the wafer W on the side surface 11a side. The carrier 11 is detachably installed on the carrier station 12 so that the side surface 11a faces the loading / unloading unit 13 side.

  As shown in FIGS. 1 to 3, the carry-in / carry-out unit 13 includes open / close doors 13 a corresponding to the plurality of carriers 11 on the carrier station 12. When the open / close door of the side surface 11a and the open / close door 13a of the carry-in / carry-out unit 13 are opened simultaneously, the inside of the carrier 11 and the carry-in / carry-out unit 13 communicate with each other. As shown in FIGS. 2 and 3, the carry-in / carry-out unit 13 incorporates a delivery arm A <b> 1. The delivery arm A1 takes out the wafer W from the carrier 11 and delivers it to the processing block BK2. The delivery arm A1 receives the wafer W from the processing block BK2 and returns it to the carrier 11.

  The processing block BK2 is adjacent to the carrier block BK1 and connected to the carrier block BK1, as shown in FIGS. As shown in FIGS. 1 and 2, the processing block BK2 includes a lower antireflection film formation (BCT) block 14, a resist film formation (COT) block 15, an upper antireflection film formation (TCT) block 16, and A development processing (DEV) block 17. The DEV block 17, the BCT block 14, the COT block 15, and the TCT block 16 are arranged in this order from the bottom side.

  As shown in FIG. 2, the BCT block 14 includes a coating unit (not shown), a heating / cooling unit (not shown), and a transfer arm A2 for transferring the wafer W to these units. Yes. The coating unit applies a chemical solution for forming an antireflection film to the surface of the wafer W. The heating / cooling unit heats the wafer W using, for example, a hot plate, and then cools the wafer W using, for example, a cooling plate. Thus, a lower antireflection film is formed on the surface of the wafer W.

  As shown in FIG. 2, the COT block 15 includes a coating unit (not shown), a heating / cooling unit (not shown), and a transfer arm A3 for transferring the wafer W to these units. Yes. The coating unit applies a chemical solution (resist material) for forming a resist film on the lower antireflection film. The heating / cooling unit heats the wafer W using, for example, a hot plate, and then cools the wafer W using, for example, a cooling plate. Thus, a resist film is formed on the lower antireflection film of the wafer W. The resist material may be a positive type or a negative type.

  As shown in FIG. 2, the TCT block 16 includes a coating unit (not shown), a heating / cooling unit (not shown), and a transfer arm A4 for transferring the wafer W to these units. Yes. The coating unit applies a chemical solution for forming an antireflection film on the resist film. The heating / cooling unit heats the wafer W using, for example, a hot plate, and then cools the wafer W using, for example, a cooling plate. Thus, an upper antireflection film is formed on the resist film of the wafer W.

  As shown in FIGS. 2 and 3, the DEV block 17 includes a plurality of development processing units U1, a plurality of heating / cooling units (heat treatment units) U2, and a transfer arm A5 that transfers the wafer W to these units. A transfer arm A6 that transfers the wafer W between before and after the processing block BK2 without including these units is incorporated.

  The development processing unit U1 performs development processing on the exposed resist film, as will be described later. The heating / cooling unit U2 heats the resist film on the wafer W, for example, by heating the wafer W with a hot plate. The heating / cooling unit U2 cools the heated wafer W by, for example, a cooling plate. The heating / cooling unit U2 performs heat treatment such as post-exposure baking (PEB) and post-baking (PB). PEB is a process for heating the resist film before the development process. PB is a process of heating the resist film after the development process.

  As shown in FIGS. 1 to 3, a shelf unit U10 is provided on the carrier block BK1 side of the processing block BK2. The shelf unit U10 includes a plurality of cells C30 to C38. The cells C30 to C38 are arranged in the vertical direction between the DEV block 17 and the TCT block 16. A lifting arm A7 is provided in the vicinity of the shelf unit U10. The lift arm A7 transports the wafer W between the cells C30 to C38.

  A shelf unit U11 is provided on the interface block BK3 side in the processing block BK2. The shelf unit U11 has a plurality of cells C40 to C42. The cells C40 to C42 are arranged adjacent to the DEV block 17 in the vertical direction.

  As shown in FIGS. 1 to 3, the interface block BK3 is located between the processing block BK2 and the exposure apparatus E1, and is connected to each of the processing block BK2 and the exposure apparatus E1. As shown in FIGS. 2 and 3, the interface block BK3 includes a delivery arm A8. The transfer arm A8 transfers the wafer W from the shelf unit U11 of the processing block BK2 to the exposure apparatus E1. The transfer arm A8 receives the wafer W from the exposure apparatus E1, and returns the wafer W to the shelf unit U11.

  The control device CU is a computer for control and includes a storage unit CU1 and a control unit CU2 as shown in FIG. The storage unit CU1 stores a program for operating each part of the coating / developing apparatus 1 and each part of the exposure apparatus E1. The storage unit CU1 is, for example, a semiconductor memory, an optical recording disk, a magnetic recording disk, or a magneto-optical recording disk. The program may be included in an external storage device separate from the storage unit CU1 or an intangible medium such as a propagation signal. The program may be installed in the storage unit CU1 from these other media, and the program may be stored in the storage unit CU1. The control unit CU2 controls the operation of each unit of the coating / developing apparatus 1 and each unit of the exposure apparatus E1 based on the program read from the storage unit CU1.

  Next, an outline of the operation of the coating / developing apparatus 1 will be described. First, the carrier 11 is installed in the carrier station 12. At this time, one side surface 11 a of the carrier 11 is directed to the open / close door 13 a of the carry-in / carry-out unit 13. Subsequently, the opening / closing door of the carrier 11 and the opening / closing door 13a of the loading / unloading section 13 are both opened, and the wafer W in the carrier 11 is taken out by the transfer arm A1, and any of the shelf units U10 of the processing block BK2 is selected. It is sequentially transported to that cell.

  After the wafer W is transferred to any cell of the shelf unit U10 by the transfer arm A1, the wafer W is sequentially transferred to the cell C33 corresponding to the BCT block 14 by the lifting arm A7. The wafer W transferred to the cell C33 is transferred to each unit in the BCT block 14 by the transfer arm A2. In the process in which the wafer W is transferred through the BCT block 14 by the transfer arm A2, a lower antireflection film is formed on the surface of the wafer W.

  The wafer W on which the lower antireflection film is formed is transferred to the cell C34 above the cell C33 by the transfer arm A2. The wafer W transferred to the cell C34 is transferred to the cell C35 corresponding to the COT block 15 by the lifting arm A7. The wafer W transferred to the cell C35 is transferred to each unit in the COT block 15 by the transfer arm A3. In the process in which the wafer W is transferred through the COT block 15 by the transfer arm A3, a resist film is formed on the lower antireflection film.

  The wafer W on which the resist film is formed is transferred to the cell C36 above the cell C35 by the transfer arm A3. The wafer W transferred to the cell C36 is transferred to the cell C37 corresponding to the TCT block 16 by the lifting arm A7. The wafer W transferred to the cell C37 is transferred to each unit in the TCT block 16 by the transfer arm A4. In the process in which the wafer W is transported through the TCT block 16 by the transport arm A4, an upper antireflection film is formed on the resist film.

  The wafer W on which the upper antireflection film is formed is transferred to the cell C38 above the cell C37 by the transfer arm A4. The wafer W transferred to the cell C38 is transferred to the cell C32 by the lift arm A7 and then transferred to the cell C42 of the shelf unit U11 by the transfer arm A6. The wafer W transferred to the cell C42 is transferred to the exposure apparatus E1 by the transfer arm A8 of the interface block BK3, and the exposure process of the resist film is performed in the exposure apparatus E1. The wafer W subjected to the exposure processing is transferred to the cells C40 and C41 below the cell C42 by the transfer arm A8.

  The wafer W transferred to the cells C40 and C41 is transferred to each unit in the DEV block 17 by the transfer arm A5, and development processing is performed. As a result, a resist pattern (uneven pattern) is formed on the surface of the wafer W. The wafer W on which the resist pattern is formed is transferred by the transfer arm A5 to cells C30 and C31 corresponding to the DEV block 17 in the shelf unit U10. The wafer W transferred to the cells C30 and C31 is transferred to a cell accessible by the transfer arm A1 by the lift arm A7, and returned to the carrier 11 by the transfer arm A1.

  The configuration and operation of the coating / developing apparatus 1 described above are merely examples. The coating / developing apparatus 1 may include a liquid processing unit such as a coating unit or a development processing unit, a pre-processing / post-processing unit such as a heating / cooling unit, and a transport device. That is, the number, type, layout, etc. of each unit can be changed as appropriate.

[Configuration of heating / cooling unit]
Next, the configuration of the heating / cooling unit (heat treatment apparatus) U2 will be described in more detail with reference to FIGS. As illustrated in FIGS. 4 and 5, the heating / cooling unit U <b> 2 includes a heating unit 110 that heats the wafer W and a cooling unit 120 that cools the wafer W in the housing 100. A loading / unloading port 101 for carrying the wafer W into the housing 100 and carrying the wafer W out of the housing 100 is formed on both side walls of the portion corresponding to the cooling unit 120 in the housing 100. Yes.

  The heating unit 110 includes a lid portion 111 and a hot plate housing portion 112. The lid portion 111 is located above the hot plate housing portion 112 and can be moved up and down between an upper position separated from the hot plate housing portion 112 and a lower position placed on the hot plate housing portion 112. It is. The lid portion 111 constitutes the processing chamber R together with the hot plate accommodating portion 112 when in the lower position. An exhaust part 111 a is provided at the center of the lid part 111. The exhaust part 111 a is used for exhausting gas from the processing chamber R.

  The hot plate accommodating portion 112 has a cylindrical shape, and accommodates the hot plate 113 therein. The outer peripheral portion of the hot plate 113 is supported by a support member 114. The outer periphery of the support member 114 is supported by a cylindrical support ring 115. A gas supply port 115 a that opens upward is formed on the upper surface of the support ring 115. The gas supply port 115a ejects an inert gas into the processing chamber R.

  As shown in FIGS. 4 to 7, the hot plate 113 is a flat plate having a circular shape. The outer shape of the hot plate 113 is larger than the outer shape of the wafer W. The heat plate 113 is formed with three through holes HL extending in the thickness direction (see FIGS. 5 and 7). On the upper surface of the hot plate 113, six support pins PN that support the wafer W are erected (see FIGS. 4, 6, and 7). The height of the support pin PN may be about 100 μm, for example.

  In the present embodiment, the heat plate 113 has five regions 113a to 113e (see FIG. 7). One region 113 a has a circular shape when viewed from above, and constitutes the center of the hot plate 113. The four regions 113b to 113e have an arc shape and are arranged so as to surround the region 113a. More specifically, the region 113b is adjacent to the regions 113c and 113e and faces the region 113d with the region 113a interposed therebetween.

  Heaters 116a to 116e are respectively disposed on the lower surfaces of the regions 113a to 113e (see FIGS. 5 and 7). Each of the heaters 116a to 116e is connected to the control unit CU2 (see FIGS. 4 and 6). Based on the instruction signal from the control unit CU2, the heaters 116a to 116e are independently controlled. Therefore, the regions 113a to 113e can be independently adjusted to different temperatures.

  Temperature sensors 117a to 117e are embedded in the regions 113a to 113e, respectively (see FIGS. 6 and 7). The temperature sensors 117a to 117e measure the temperatures of the corresponding regions 113a to 113e, and transmit the measurement signals to the control unit CU2 (see FIG. 6).

  Distance sensors 118a to 118e are provided in the regions 113a to 113e, respectively (see FIGS. 6 and 7). Each of the distance sensors 118 a to 118 e is attached in an installation hole provided in the hot plate 113. In the example shown in FIGS. 6 and 7, the upper ends of the distance sensors 118 a to 118 e are exposed from the surface of the hot plate 113. The distance sensors 118a to 118e measure the linear distance in the vertical direction between the wafer W located above and the hot plate 113 (regions 113a to 113e), and transmit the measurement signal to the control unit CU2 (FIG. 6). reference). Examples of the distance sensors 118a to 118e include laser displacement meters and LED photoelectric sensors. When the LED photoelectric sensor is used, the distance is calculated based on the intensity of reflected light from the wafer W or the like.

  As shown in FIGS. 4 and 5, an elevating mechanism 119 is disposed below the hot plate 113. The elevating mechanism 119 includes a motor 119a disposed outside the housing 100, and three elevating pins 119b that move up and down by the motor 119a. The elevating pins 119b are configured to be able to pass through the corresponding through holes HL. When the control unit CU2 transmits an ascending signal or a descending signal to the motor 119a, the elevating pins 119b move up and down while moving in the corresponding through holes HL. When the tip of the lift pins 119b protrudes above the hot plate 113, the wafer W can be placed on the tip of the lift pins 119b. The wafer W placed on the tip of the lift pins 119b moves up and down as the lift pins 119b move up and down.

  As shown in FIG. 4, the cooling unit 120 is located adjacent to the heating unit 110. The cooling unit 120 includes a cooling plate 121 that cools the mounted wafer W. The cooling plate 121 is a flat plate having a rectangular shape as shown in FIG. An end of the cooling plate 121 on the heating unit 110 side has an arc shape protruding toward the heating unit 110. The cooling plate 121 incorporates a cooling member 121a such as a Peltier element. The cooling member 121a can adjust the cooling plate 121 to a predetermined set temperature.

  The cooling plate 121 is attached to a rail 122 extending toward the heating unit 110 side. The cooling plate 121 is driven by the driving unit 123 and can move horizontally on the rail 122. The cooling plate 121 that has moved to the heating unit 110 side is located above the heating plate 113.

  As shown in FIG. 5, the cooling plate 121 is formed with two slits 124 extending along the extending direction of the rail 122. The slit 124 is formed to extend from the end of the cooling plate 121 on the heating unit 110 side to the vicinity of the center of the cooling plate 121. The slit 124 prevents interference between the cooling plate 121 moved to the heating unit 110 side and the elevating pins 119b protruding on the heating plate 113.

  As shown in FIG. 4, an elevating mechanism 125 is disposed below the cooling plate 121. The elevating mechanism 125 includes a motor 125a disposed outside the housing 100 and three elevating pins 125b that move up and down by the motor 125a. The elevating pins 125b are configured to be able to pass through the slits 124, respectively. When the control unit CU2 transmits an ascending signal or a descending signal to the motor 125a, the elevating pin 125b moves up and down while moving in the slit 124. When the tips of the lift pins 125b protrude above the cooling plate 121, the wafer W can be placed on the tips of the lift pins 125b. The wafer W placed on the tip of the lift pins 125b moves up and down as the lift pins 125b move up and down.

[Wafer heat treatment method]
Next, a method for heat-treating the wafer W using the heating / cooling unit U2 will be described mainly with reference to FIG. First, after the resist film is formed on the surface of the wafer W, immediately before the wafer W is transferred to the heating unit 110, the temperature of the wafer W is measured (step S11). For example, a radiation thermometer can be used for the temperature measurement of the wafer W at this time.

  Subsequently, the wafer W is transferred into the heating unit 110 (inside the processing chamber R) (step S12). Specifically, when the transfer arm A5 places the wafer W on the tip of the elevating pin 125b of the cooling unit 120, the elevating pin 125b is lowered and transferred onto the cooling plate 121. When the cooling plate 121 moves along the rail 122 toward the heating unit 110, the elevating pins 119 b rise and lift the wafer W from the cooling plate 121. When the cooling plate 121 is retracted from the heating unit 110, the elevating pins 119b are lowered to place the wafer W on the support pins PN. Thus, the wafer W is supported by the support pins PN above the hot plate 113. As a result, heat from the hot plate 113 moves to the wafer W, and the wafer W is heated.

  Subsequently, the heating process of the wafer W by the hot plate 113 is started, and it is determined whether or not a predetermined processing time has elapsed (that is, whether or not a predetermined time has elapsed from the start of the processing) (step S13). . If the processing time has elapsed, the heating process of the wafer W by the hot plate 113 is completed. On the other hand, if the processing time has not elapsed, the heating process of the wafer W by the hot plate 113 is continued. The processing time may be set to about 60 seconds, for example.

  If it is determined in step S13 that the processing time has not elapsed, the temperature of the hot plate 113 is measured by the temperature sensors 117a to 117e (step S14). Specifically, the temperature sensors 117a to 117e measure the temperatures of the corresponding regions 113a to 113e, respectively, and transmit measurement signals of the measured temperatures to the control unit CU2.

  Subsequently, a linear distance in the vertical direction between the hot plate 113 and the wafer W is measured by the distance sensors 118a to 118e (step S15). Specifically, the distance sensors 118a to 118e respectively measure the linear distances in the vertical direction between the corresponding regions 113a to 113e and the wafer W (that is, the portion of the wafer W that is directly above itself). The measurement signal of the measured distance is transmitted to the control unit CU2.

Subsequently, the amount of heat transferred from the hot plate 113 to the wafer W is calculated by the control unit CU2 (step S16). Specifically, when the control unit CU2 receives measurement signals from the temperature sensors 117a to 117e and the distance sensors 118a to 118e, respectively, the heat transfer amount ΔQ from the hot plate 113 to the wafer W for each of the regions 113a to 113e according to Equation 1. Calculate In the heat transfer from the hot plate 113 to the wafer W, the heat transfer due to convection or heat radiation is sufficiently smaller than the heat conduction. Therefore, in Equation 1, heat transfer due to convection and heat radiation is not considered.
ΔQ = S × λ × (Tp−Tw) × Δt / H (1)

Here, in Equation 1, the parameters S, λ, Tp, Tw, Δt, and H are defined as follows.
S: Area of calculation target regions 113a to 113e λ: Thermal conductivity of air Tp: Temperature of hot plate 113 measured in step S14 Tw: Temperature of wafer W measured in step S11 at the time of the first calculation, At the time of the second and subsequent calculations, the temperature of the wafer W calculated in step S17 to be described later Δt: time per loop in which steps S14 to S19 are executed H: measured in step S15 in the calculation target regions 113a to 113e Linear distance between the heated plate 113 and the wafer W in the vertical direction

Subsequently, the control unit CU2 calculates output values for the heaters 116a to 116e (step S18). Specifically, the control unit CU2 first calculates the temperature change amount ΔTw of the wafer W for each of the regions 113a to 113e according to Equation 2.
ΔTw = ΔQ / C (2)
Here, in Expression 2, the parameter C is defined as follows.
C: Heat capacity in a portion of the wafer W corresponding to each of the regions 113a to 113e (in this embodiment, a portion of the wafer W overlapping with each of the regions 113a to 113e when viewed from above)

Next, based on the temperature change amount ΔTw obtained by Expression 2, the control unit CU2 calculates the estimated temperature Twe of the wafer W for each of the regions 113a to 113e according to Expression 3.
Twe = Tw + ΔTw (3)

  Next, based on the difference (Twe−Twt) between the estimated temperature Twe obtained by Expression 3 and the target temperature Twt of the wafer W, the control unit CU2 calculates an output value for each of the heaters 116a to 116e according to Expression 4. . That is, if the difference (Twe−Twt) is positive, the wafer W may be heated too much, so the control unit CU2 sets the output values of the corresponding heaters 116a to 116 smaller than the current value. If the difference (Twe−Twt) is negative, there is a possibility that the wafer W will not be sufficiently heated. Therefore, the control unit CU2 sets the output values of the corresponding heaters 116a to 116e larger than the current value. If the difference (Twe−Twt) is 0, the heating amount of the wafer W is appropriate, and the control unit CU2 sets the output values of the corresponding heaters 116a to 116e to the current values.

  The target temperature Twt means an ideal temperature at which the resist film on the wafer W is appropriately processed in a certain processing time. The target temperature Twt usually increases while drawing a predetermined curve as the processing time elapses (see FIG. 9). The target temperature Twt may be obtained in advance by experiments or the like.

  Then, each heater 116a-116e is controlled by control part CU2 (step S19). Specifically, the control unit CU2 controls the outputs of the heaters 116a to 116e so that the output value set in step S18 is obtained. Thereafter, returning to step S13, if the processing time has elapsed, the heating process of the wafer W by the hot plate 113 is completed. On the other hand, if it is before progress of processing time, the process of step S14-S19 will be repeated. That is, feedback control is performed on the temperature of the wafer W by repeating steps S14 to S19. The time (Δt) per loop in which steps S14 to S19 are executed may be set to about 0.1 seconds, for example.

[Action]
In the present embodiment as described above, the distance between the hot plate 113 and the wafer W (the linear distance in the vertical direction) is measured by the distance sensors 118a to 118e. Therefore, the temperature generated in the wafer W due to the heat from the hot plate 113 is estimated more accurately by calculation. Therefore, by adjusting the temperature of the hot plate 113 so that the estimated temperature Twe of the wafer W approaches the target temperature Twt, the temperature of the wafer W can be controlled with higher accuracy.

  In the present embodiment, the processes of steps S14 to S19 are repeated. Therefore, for example, the temperature of the wafer W can be controlled so that the temperature of the wafer W changes along the target temperature Twt from the start to the end of the heat treatment of the wafer W. Further, since the distance between the hot plate 113 and the wafer W is repeatedly measured in each loop, even when the wafer W is deformed by the heat from the hot plate 113, the hot plate 113 and the wafer W that have changed along with the deformation are changed. Is immediately reflected in the estimated temperature Twe of the wafer W. Therefore, the temperature of the wafer W can be controlled with higher accuracy.

  In the present embodiment, the regions 113a to 113e have heaters 116a to 116e, temperature sensors 117a to 117e, and distance sensors 118a to 118e, respectively. In the present embodiment, the processes in steps S14 to S19 are repeated for each of the regions 113a to 113e, and the temperatures of the regions 113a to 113e are independently adjusted. For this reason, even when the wafer W is warped (see FIG. 6) or the wafer W is inclined with respect to the hot plate 113, the hot plate according to the state of the wafer W is used. The temperature of the hot plate 113 is adjusted for each region 113. For this reason, both the temperature at the center of the wafer W and the temperature at the outer periphery change along the target temperature (see FIG. 9A), so that the temperature of the wafer W can be controlled with higher accuracy. On the other hand, in the conventional method in which the temperature of the hot plate itself is adjusted, if the wafer is warped or the wafer is disposed to be inclined with respect to the hot plate, as shown in FIG. In addition, the temperature at the center or outer periphery of the wafer may deviate significantly from the target temperature. The case where the wafer W is disposed to be inclined with respect to the hot plate 113 can be exemplified by, for example, a case where a foreign object larger than the support pin PN exists on the hot plate 113 and the substrate has been placed on the foreign object. .

  In the present embodiment, the regions 113 a to 113 e are arranged in the circumferential direction of the hot plate 113. Therefore, a plurality of linear distances between the hot plate 113 and the wafer W are acquired in the circumferential direction. Therefore, the inclination of the entire wafer W can be grasped. As a result, when the wafer W is disposed to be inclined with respect to the hot plate 113, the temperature of the wafer W can be controlled particularly accurately.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to above-described embodiment. For example, as shown in FIG. 10, step S15 may be performed before step S13, not between step S14 and step S16. For example, as shown in FIG. 10, step S15 may be performed between step S11 and step S12. In this case, before the wafer W is heat-treated, the distance between the wafer W and the hot plate 113 is measured. Therefore, even when the wafer W is warped before the heat treatment, the temperature of the wafer W can be accurately controlled.

  The heat plate 113 may not have a plurality of regions, and may have two or more regions. Also in this case, a heater, a temperature sensor, and a distance sensor are respectively arranged in the plurality of regions, and the temperature of each region is adjusted independently. The number of regions arranged in the circumferential direction of the hot plate 113 may be two, or may be three or more. When the number of regions arranged in the circumferential direction of the hot plate 113 is two, there may be at least one region at the center of the hot plate 113. As described above, when the hot plate 113 has at least three regions and the distance sensors arranged in each region are not arranged on one straight line, the posture of the wafer W can be grasped. .

  One or more temperature sensors may be arranged in each region of the hot plate 113. The distance sensor disposed in each region of the hot plate 113 may be one by one or plural.

  The present invention may be applied not only to the heating / cooling unit U2 of the DEV block 17 but also to various heat treatment apparatuses for heat treating the wafer.

  The upper ends of the distance sensors 118a to 118e exposed from the surface of the hot plate 113 may be covered with a transparent plate, for example. In this case, the opening formed in the hot plate 113 to accommodate the distance sensors 118a to 118e is covered with a transparent plate. Therefore, the transparent plate and the hot plate 113 are thermally connected, and the wafer W can be heated also in the opening portion. Accordingly, the temperature measurement function by the distance sensors 118a to 118e is not hindered, and the temperature in the surface of the hot plate 113 can be made uniform.

  DESCRIPTION OF SYMBOLS 1 ... Coating / development apparatus, 110 ... Heating part, 113 ... Hot plate, 113a-113e ... Area, 117a-117e ... Temperature sensor, 118a-118e ... Distance sensor, CU2 ... Control part, PN ... Supporting pin, U2 ... Heating -Cooling unit, W ... wafer.

Claims (12)

(A) measuring a separation distance between a heat plate for applying heat to the substrate and the substrate disposed above the heat plate by a distance sensor;
(B) measuring the temperature of the hot plate with a temperature sensor;
(C) calculating an estimated temperature of the substrate disposed above the hot plate based on the separation distance measured in the A term and the temperature of the hot plate measured in the B term. When,
(D) A method of heat-treating a substrate including adjusting the temperature of the hot plate based on a difference between the estimated temperature calculated in the item C and a target temperature of the substrate.   The method according to claim 1, wherein the items A to D are repeatedly performed until a predetermined period elapses.   The method according to claim 1, wherein the items B to D are repeatedly performed until a predetermined period elapses. The hot plate has a plurality of regions that can be temperature-controlled independently,
The distance sensor and the temperature sensor are arranged for each of the plurality of regions,
The method according to claim 1, wherein the items A to D are performed for each of the plurality of regions.   The method according to claim 4, wherein the plurality of regions are arranged in a circumferential direction.   The estimated temperature is calculated using a temperature change amount of the substrate obtained by dividing a heat transfer amount per predetermined time out of heat transferred from the hot plate to the substrate via air. 6. The method according to any one of claims 1 to 5, wherein: A heat plate for applying heat to the substrate;
A support member for supporting the substrate above the hot plate;
A distance sensor for measuring a separation distance between the hot plate and the substrate;
A temperature sensor for measuring the temperature of the hot plate;
A control unit,
The controller is
(A) Control for measuring the separation distance by the distance sensor;
(B) control for measuring the temperature of the hot plate by the temperature sensor;
(C) Based on the separation distance measured in the control A and the temperature of the hot plate measured in the control B, an estimated temperature of the substrate disposed above the hot plate is calculated. Control,
(D) A heat treatment apparatus that executes control for adjusting the temperature of the hot plate based on a difference between the estimated temperature calculated in the control C and a target temperature of the substrate.   The heat treatment apparatus according to claim 7, wherein the control unit repeatedly executes the controls A to D until a predetermined period elapses.   The heat treatment apparatus according to claim 7, wherein the control unit repeatedly executes the controls B to D until a predetermined period elapses. The hot plate has a plurality of regions that can be temperature-controlled independently,
The distance sensor and the temperature sensor are arranged for each of the plurality of regions,
The said control part is a heat processing apparatus as described in any one of Claims 7-9 which performs said control AD for every said some area | region.   The heat treatment apparatus according to claim 10, wherein the plurality of regions are arranged in a circumferential direction.   The computer-readable recording medium which recorded the program for making a heat processing apparatus perform the method as described in any one of Claims 1-6.

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