JP2012151247A - Substrate heating apparatus, substrate heating method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect whether a micro object of 1 mm or smaller, for example, adhering to the surface of a hot plate has ridden on a substrate or not when the substrate is placed on the hot plate and heated.SOLUTION: With regard to a hot plate 11 for mounting a wafer W, a plurality of heaters 12 are provided so as to be spaced apart from each other in the horizontal direction, and temperature sensors 13 are arranged to correspond with these heaters 12. The wafer W is then mounted on the hot plate 11 set to a set temperature, and the standard deviation is calculated for the temperatures measured by the temperature sensors 13 after the temperature of the hot plate 11 begins to lower due to heat absorption by the wafer W before returning to the set temperature. The standard deviation is compared with a preset threshold.

Description

  The present invention relates to a substrate heating apparatus that heats a substrate, a substrate heating method, and a storage medium that stores the method.

  2. Description of the Related Art A coating / developing apparatus that performs a resist film coating process or a resist film developing process on a substrate such as a semiconductor wafer (hereinafter referred to as a “wafer”) includes a heating device for performing a heating process on the wafer. Is provided. In this heating apparatus, for example, after applying a resist solution to a wafer (pre-baking), or after performing exposure processing with an exposure apparatus connected to the coating / developing apparatus (post-exposure baking), further developing processing is performed. After (post-baking), the wafer is heated. This heating device corresponds to a heating plate on which a wafer is placed, heaters provided at a plurality of locations inside the heating plate in order to uniformly heat the wafer over the surface, and the position of each heater. And temperature sensors provided at a plurality of locations. On the upper surface of the heating plate, a guide pin having a substantially cylindrical shape with a length dimension of about 3 mm, for example, for regulating the position of the wafer along the outer peripheral surface of the wafer placed on the heating plate. Are provided at a plurality of locations.

  When performing heat treatment on the wafer, the peripheral portion of the wafer is guided by a cooperative action of a transfer arm outside the heating device and an elevating pin provided on the lower side of the heating plate. Is placed on a heating plate adjusted to a certain set temperature, for example, 80 ° C. At this time, when a wafer at room temperature, for example, is placed on the heating plate, the heat of the heating plate is taken away by the wafer (transferred), and the temperature of the heating plate decreases by, for example, about 5 ° C. The heater output is greatly adjusted to compensate. Therefore, the temperature of the heating plate lowered by the wafer placement is then raised and returned to the original set temperature as shown in FIG.

  Here, in the heating device, when the wafer is placed on the heating plate, the peripheral portion of the wafer may erroneously ride on the above-described guide pins. If the wafer rides on the guide pins, that is, if the wafer is tilted with respect to the heating plate, uniform heat treatment will not be performed in the plane. Therefore, when the wafer is heated by the heating device, it is detected whether or not the wafer is riding on the guide pins.

  Specifically, when the wafer is placed on the heating plate as described above, the temperature of the heating plate falls from the set temperature (undershoots), and then rises and returns to the original set temperature. When the end of the plate is riding on the guide pin, the surface of the heating plate is separated from the back surface of the wafer by the height of the guide pin at the end, so that the heat of the heating plate is difficult to transfer to the wafer (decrease). Difficult). Therefore, as in Patent Document 1, for example, an integrated value for a detection value detected by each temperature sensor is calculated, and the integrated value or threshold value when the integrated value is normal (when not on the guide pin) is calculated. Whether it is smaller than the value is calculated.

On the other hand, on the surface of the heating plate, for example, a minute object of 1 mm or less such as a wafer fragment or particle generated when the wafer collides with the guide pin may adhere. Even when a wafer is placed on such a minute object, there is a possibility that the heat treatment of the wafer may vary in the plane, and it is desired to detect whether or not the wafer has been placed on the minute object. However, it is extremely difficult to detect such a minute object with the detection method described above. In other words, the difference between the integral values described above is slight when the wafer is placed on the minute object compared to the normal state. Therefore, even when the wafer is placed on the minute object, the temperature of the hot plate is the set temperature. After returning to the above, when the temperature becomes higher than the set temperature due to overshoot, for example, the difference between the integral values may be offset. Therefore, the temperature change of the hot plate after mounting the wafer during normal operation (when a minute object is not attached on the heating plate) and when abnormal (when a minute object is attached on the heating plate). Even if there is a difference in the curve indicating the above (the detected value), there is a case where it is not possible to detect whether or not the wafer has been placed on the minute object without causing a difference in the integrated value. On the other hand, if the threshold value for determining that the wafer has run on the minute object is set to the normal side rather than the abnormal side, that is, if the margin for determining that the wafer is normal is set to be small, the wafer is normally placed on the heating plate. Even in such a case, there is a possibility that an abnormality is detected due to erroneous detection.
Although Patent Documents 1 to 4 describe an apparatus for heating a wafer, such a problem is not described.

JP2009-123816A JP 2010-109350 A JP2002-50557 JP 2008-258289 A

  The present invention has been made under such circumstances. The purpose of the present invention is to place a substrate on a heating plate and heat it, and a small minute object such as 1 mm or less is attached to the surface of the heating plate. Even in such a case, it is an object to provide a substrate heating apparatus, a substrate heating method, and a storage medium in which this method is stored, which can detect whether or not the substrate is placed on the minute object.

The substrate heating apparatus of the present invention is
In the substrate heating apparatus that heats the substrate placed on the heating plate to the set temperature by the heating unit,
A plurality of temperature measuring units that are provided apart from each other in the direction of the plate surface of the heating plate and measure the temperature of at least one of the heating plate and the substrate;
A temperature variation calculation unit that calculates a value of variation between the temperature measurement values of the plurality of temperature measurement units after placing the substrate on the heating plate;
In order to determine whether or not the substrate is on a foreign object on the heating plate, a comparison unit that compares the value of variation of the temperature measurement value with a preset threshold value is provided. And

The substrate heating device may be configured as follows.
The said heating part is the structure provided in multiple places so as to correspond to the arrangement position of the said temperature measurement part. The variation value calculated by the temperature variation calculation unit is a standard deviation of the measured temperature. The threshold value is a value set in advance based on a variation value calculated by the temperature variation calculation unit when the substrate is horizontally placed on the heating plate. A configuration comprising an alarm reporting unit that is triggered when the comparison unit detects that the variation value is greater than the threshold value.

The substrate heating method of the present invention comprises:
In the substrate heating method of heating the substrate placed on the heating plate to the set temperature by the heating unit,
Placing the substrate on the heating plate;
Next, a step of measuring the temperature of at least one of the heating plate and the substrate after placing the substrate on the heating plate by a plurality of temperature measurement units provided apart from each other in the direction of the plate surface of the heating plate; ,
Subsequently, a step of calculating a variation value between the temperature measurement values of the plurality of temperature measurement units,
Thereafter, the temperature variation value calculated in the calculating step is compared with a preset threshold value, and based on the comparison result, it is determined whether or not the substrate is on a foreign object on the heating plate. And a step of performing.

  The substrate heating method may be configured as follows. In the heating plate, the substrate is heated by the heating units provided at a plurality of locations so as to correspond to the arrangement positions of the temperature measurement units. The variation value calculated in the calculating step is a standard deviation of the measured temperature. After the step of comparing, a step of issuing an alarm when the value of variation is larger than the threshold value in the step of comparing. Before the step of placing the substrate on the heating plate, the step of horizontally placing the substrate on the heating plate and calculating a variation value for each temperature measurement value of the plurality of temperature measurement units; and And a step of setting the threshold value based on the value of variation calculated in the above.

The storage medium of the present invention is
A storage medium storing a program used in a substrate heating device for heating a substrate placed on a heating plate,
The program is characterized in that a group of steps is assembled so as to implement any one of the above substrate heating methods.

  In the present invention, when a substrate placed on a heating plate is heated to a set temperature by a heating unit, after the substrate is placed on the heating plate, a plurality of them are provided apart from each other in the direction of the plate surface of the heating plate. The temperature measurement unit measures the temperature of at least one of the heating plate and the substrate, and calculates the value of variation between these temperature measurement values. Since this calculated value is compared with a preset threshold value, it is possible to detect whether or not the substrate is on a minute object (foreign matter) on the heating plate.

It is a longitudinal cross-sectional view which shows an example of the substrate heating apparatus of this invention. It is a cross-sectional top view which shows the said substrate heating apparatus. It is a schematic diagram which shows the control part of the said substrate heating apparatus. It is a schematic diagram which shows the temperature change of the said heating plate when a wafer is mounted in the heating plate of the said substrate heating apparatus. It is a flowchart which shows the substrate heating method of this invention. It is a longitudinal cross-sectional view of the heating plate which shows the effect | action in the said substrate heating method. It is a longitudinal cross-sectional view of the heating plate which shows the effect | action in the said substrate heating method. It is a longitudinal cross-sectional view of the heating plate which shows the effect | action in the said substrate heating method. It is a top view which shows the other example of the said heating plate. It is a top view which shows the other example of the said heating plate. It is a characteristic view which showed the characteristic obtained in the Example of this invention. It is a characteristic view which showed the characteristic obtained in the Example of this invention. It is a characteristic view which showed the characteristic obtained in the Example of this invention. It is a characteristic view which showed the characteristic obtained in the Example of this invention. It is a characteristic view which showed the characteristic obtained in the Example of this invention.

  An example of an embodiment of the substrate heating apparatus of the present invention will be described with reference to FIGS. The substrate heating apparatus includes a heating plate 11 for placing a wafer W, and a heater that is a heating unit embedded in the heating plate 11 at a plurality of locations in order to heat the wafer W via the heating plate 11. 12 and a temperature sensor 13 which is a temperature measurement unit provided corresponding to the arrangement position of the heater 12 in order to measure the temperature of the heating plate 11 (wafer W). Then, as will be described later, the substrate heating apparatus detects whether or not the wafer W is on a foreign matter (a minute object) such as a particle on the heating plate 11 using the temperature detection values of the temperature sensors 13. is doing. In FIG. 1, reference numerals 21 and 22 denote a processing container and a transfer port, respectively, which form a casing.

  An upper side of the heating plate 11 is provided so as to face the heating plate 11 and to be lifted and lowered by a lifting mechanism (not shown) so as to cover the atmosphere in which the heat treatment is performed on the wafer W from the upper side in the circumferential direction. A lid 23 is provided. In FIG. 1, reference numeral 24 denotes a support table that supports the heating plate 11 from the side in the circumferential direction, and reference numeral 25 denotes gas discharge holes formed in the upper surface of the support table 24 in the circumferential direction. The gas discharged from the gas discharge hole 25, for example, nitrogen (N 2) gas is configured to be exhausted from an exhaust port 26 provided on the upper surface of the lid body 23. In FIG. 2, the description of the heater 12 and the temperature sensor 13 is omitted.

  As shown in FIG. 3, the heaters 12 are provided at a plurality of, for example, five locations so as to be separated from each other in the horizontal direction (the thickness direction of the heating plate 11). That is, in this example, the heating plate 11 is partitioned into a circular inner region 11a and a ring-shaped outer region 11b outside the inner region 11a, and the outer region 11b is provided at four locations at equal intervals in the circumferential direction. It is partitioned into partitioned areas 11c. The heater 12 is disposed in each of the inner region 11a and the four partitioned regions 11c. Further, as shown in FIGS. 1 and 3, temperature sensors 13 are arranged below the heating plate 11 so as to correspond to the arrangement positions of the heaters 12, and the temperature detection values of the temperature sensors 13 are displayed. The amount of electric power supplied to each heater 12 is adjusted by a temperature controller 31 that forms a temperature adjustment unit so that the set temperature is, for example, 80 ° C.

  On the heating plate 11, in order to regulate (guide) the position of the wafer W, guide pins 14 having a height dimension of about 3 mm, for example, are arranged at a plurality of places, for example, six places at equal intervals along the circumferential direction of the wafer W. Is provided. Further, on the heating plate 11, in order to support the back surface of the wafer W with a distance of, for example, about 0.1 mm from the surface of the heating plate 11, a projecting shape having a height dimension of, for example, about 0.1 mm. The proximity pins 15 are provided at a plurality of locations. Below the heating plate 11, lift pins 27 are provided for transferring the wafer W to and from a transfer arm (not shown). The lift pins 27 are mounted on the heating plate 11. In the heating plate 11, through holes 16 are formed at a plurality of places, for example, three places. In FIG. 1, reference numeral 28 denotes a lifting mechanism. FIG. 2 is a simplified drawing of the substrate heating apparatus.

  As shown in FIG. 3, the substrate heating apparatus is provided with a control unit 32 including a computer for controlling the operation of the entire apparatus. The control unit 32 includes a CPU 33, a program 34, and a memory 35. I have. The program 34 includes a wafer heating program 34a for performing a heat treatment by placing the wafer W on the heating plate 11, and a standard forming a temperature variation calculation unit for calculating a standard deviation of the temperature detection values of the temperature sensors 13. A deviation calculation program 34b and a difference calculation program 34c forming a comparison unit for comparing the standard deviation calculated by the standard deviation calculation program 34b with a preset threshold value are provided.

  The wafer heating program 34a is used to maintain the heating plate 11 at a set temperature, for example, 80 ° C. over the surface via the temperature controller 31 described above, and to transfer the wafer W between the heating plate 11 and the like. It is a program.

  The standard deviation calculation program 34b determines whether or not the wafer W is inclined with respect to the heating plate 11 on the heating plate 11, that is, whether or not the wafer W is riding on a minute object such as a particle on the heating plate 11. This is a program for obtaining a standard deviation, which is a variation value of a temperature detection value of each temperature sensor 13, which is an index for evaluation. Specifically, for example, when a normal temperature wafer W is placed on a heating plate 11 maintained at a set temperature, for example, 80 ° C., the heating plate 11 is placed on the wafer W as schematically shown in FIG. The heat is absorbed and the temperature drops. At this time, for example, if the end portion of the wafer W rides on a minute object such as a particle on the heating plate 11, the end portion is further away from the heating plate 11 than other portions of the wafer W. For this reason, the heating plate 11 (the heating plate 11 at the site where the minute object is attached) facing this end portion is less likely to absorb heat by the wafer W, and therefore the temperature change (temperature decrease rate) is smaller than at other sites. . Further, when the end portion of the wafer W rides on a minute object, the wafer W on the proximity pin 15 is inclined, so that the portion facing the end portion in the diameter direction of the wafer W is more than the other portion. In some cases, the temperature is close to the heating plate 11, and therefore the temperature of the heating plate 11 is quickly absorbed (the temperature decreasing rate of the heating plate 11 is increased). Therefore, it is possible to determine whether or not the wafer W is riding on the minute object by utilizing the difference in temperature change of the heating plate 11 based on such an edge of the wafer W riding on the minute object.

  Here, when an attempt is made to evaluate the temperature change with an absolute value, specifically, for example, the temperature of the heating plate 11 at a portion where the end of the wafer W rides on the minute object and the end of the wafer W become the minute object. If it is attempted to compare the temperature of the heating plate 11 at a portion that is not on the board, it may not be possible to determine whether or not the wafer W is on a minute object because the temperature difference is small. However, in the present invention, when the wafer W rides on the minute object, each temperature detection value in each temperature sensor 13 varies in the plane as shown in the embodiments described later. As described above, the standard deviation obtained by quantifying the variation is used as an index for determining whether or not the vehicle has taken over.

  Then, a standard deviation when the wafer W is not on the minute object (when the wafer W is horizontally placed on the heating plate 11) is calculated in advance, and this standard deviation or this standard deviation is arbitrarily set. A value obtained by adding the margin α is used as a threshold value. That is, when the heat treatment is performed on each wafer W, the standard deviation of each temperature detection value is calculated, and if this standard deviation is larger than the threshold value, the wafer W is riding on a minute object. The alarm 36 is issued as a result of the determination, and when the standard deviation is equal to or smaller than the threshold value, it is determined that the wafer W is normally placed and the subsequent processing is continued. Such a comparison between the standard deviation and the threshold value is performed by the above-described difference calculation program 34c. This threshold value is acquired in advance as described above and stored in the memory 35. The programs 34a to 34c are installed in the control unit 32 from a storage medium 40 such as a hard disk, a compact disk, a magneto-optical disk, a memory card, or a flexible disk.

  Next, the substrate heating method of the present invention, which is an operation using the substrate heating apparatus described above, will be described with reference to FIGS. First, the standard deviation (threshold value) described above is calculated for the case where the wafer W is normally (horizontally) placed on the heating plate 11. That is, for example, by performing maintenance or the like, deposits such as particles on the heating plate 11 are removed in advance. And the heating plate 11 is set to set temperature, for example, 80 degreeC via each heater 12 (step S1). Next, as shown in FIG. 6, the wafer W is placed on the heating plate 11 while the peripheral portion of the wafer W at room temperature is guided by the guide pins 14 by the cooperative action of the transfer arm (not shown) and the lift pins 27. Place horizontally. Then, the lid body 23 is lowered and gas is discharged from the gas discharge holes 25. When the wafer W is placed on the heating plate 11, the temperature of the heating plate 11 is absorbed by the wafer W and lowered as shown in FIG. 4, while the temperature of the wafer W is raised by the heat of the heating plate 11. (Step S2).

（σ：標準偏差、ｎ：温度センサ１３の個数、ｘ_ｉ：各々の温度センサ１３の温度検出値、ｘバー：各温度検出値の平均値） At this time, as shown in FIG. 7, since the wafer W is horizontally placed on the heating plate 11, the distance between the wafer W and the heating plate 11 is aligned in the plane. Therefore, the temperature-decreasing curve indicating the temperature change of the heating plate 11 is in a uniform state (small variation) in each temperature sensor 13 as shown in FIG. Then, from the time when the wafer W is placed on the heating plate 11, 0.8 to 1.5 seconds in this example, the temperature detection value of each temperature sensor 13 after 1 second is obtained, and based on the following formula (1) The standard deviation of these temperature detection values is calculated.
(Formula 1)

(Σ: standard deviation, n: number of temperature sensors 13, x _i : temperature detection value of each temperature sensor 13, x bar: average value of each temperature detection value)

  Further, the above-mentioned margin α is added to this standard deviation and stored in the memory 35 as a threshold value (reference) (step S3). Since the output value of the heater 12 is adjusted so that the heating plate 11 becomes the set temperature as described above, the temperature of the heating plate 11 is then returned to the set temperature, and the wafer W is also set to the set temperature. Will rise.

  Subsequently, after unloading the above-described wafer W from the heating plate 11, for example, continuous processing for a plurality of wafers W is started. Specifically, as in the example described above, the wafer W is placed on the heating plate 11 set to the set temperature (step S4), and the wafer W is placed on the heating plate 11 from the time when the wafer W is placed. The temperature detection value of each temperature sensor 13 after 2 seconds is acquired, and the standard deviation is calculated (step S5). Then, this standard deviation is compared with the above-described threshold value (step S6). At this time, when the wafer W is placed horizontally on the heating plate 11 as in the case of FIG. 7 described above, that is, when the wafer W is not on a minute object such as a particle, the standard deviation is reduced. It becomes below the threshold value, and it is determined that the wafer W is normally (horizontally) placed on the heating plate 11. In this case, the heat of the heating plate 11 that is subsequently reduced by the heat absorption of the wafer W is transferred to the heating plate 11 by the heater 12, and the heating plate 11 and the wafer W are set to the set temperature as described above. The heat treatment is performed over the time. Thereafter, the wafer W is unloaded from the processing container 21 by the lifting pins 27 and a transfer arm (not shown) (step S7).

  On the other hand, while the heat treatment is continuously performed on the plurality of wafers W, for example, particles adhere to an external transfer arm (not shown) or the wafer W and are brought into the processing container 21, or the guide pins 14 attach the wafers. When the W collides and the edge of the wafer W is slightly chipped, for example, a small minute object of about 1 mm or less may adhere to the heating plate 11. As shown in FIG. 8, when the wafer W is placed on the heating plate 11 having such a minute object attached to the surface (step S <b> 4), the wafer W is inclined with respect to the heating plate 11. To do. As described above, the heat transfer to the wafer W is slower in the portion where the minute object is attached as shown by the arrow in FIG. 8 than in other portions where the minute object is not attached. 11 temperature change (temperature decrease rate) becomes gradual. Further, at the part facing the minute object in the diameter direction of the wafer W, the wafer W and the heating plate 11 are closer to each other than the other part, so that the temperature change of the heating plate 11 becomes quicker. Therefore, the temperature detection value varies in each temperature sensor 13. Therefore, the temperature detection value of each temperature sensor 13 after 1 second from the time when the wafer W is placed on the heating plate 11 is acquired, the standard deviation is calculated (step S5), and compared with the threshold value (step S5). S6), the standard deviation is larger than the threshold value. In this case, the alarm 36 is issued (step S8), and for example, the subsequent processing is stopped. For example, by performing maintenance, the heating plate 11 is cleaned by an operator, for example, and the minute object is removed. In FIG. 8, a minute object is schematically drawn large.

According to the above-described embodiment, when the wafer W is placed on the heating plate 11 set to the set temperature and the heat treatment is performed, after the wafer W is placed on the heating plate 11, A standard deviation between each temperature measurement value of the temperature sensor 13 measured from the time when the temperature is absorbed by the wafer W to start dropping and returning to the set temperature is calculated, and this standard deviation and a preset threshold value are calculated. And comparing. Therefore, it is possible to easily detect whether or not the wafer W is on the minute object on the heating plate 11. Therefore, even if the wafer W rides on the guide pin 14 having a height of 3 mm as described above, it can be detected whether or not the wafer W rides on the guide pin 14.
Further, since the threshold value is set in advance based on the standard deviation measured with the wafer W placed horizontally on the heating plate 11, that is, the surface shape of the heating plate 11 and each temperature sensor 13 have. Since the influence of environmental errors (background) such as characteristic variations is reduced, it is possible to detect with high accuracy whether or not the wafer W is on a minute object.

  In the example described above, five heaters 12 and five temperature sensors 13 are arranged, but the number of these heaters 12 and temperature sensors 13 may be at least two. FIG. 9 shows an example in which 13 heaters 12 and 13 temperature sensors 13 are arranged. Specifically, a region on the outer peripheral side of the inner region 11a of the heating plate 11 is partitioned into three ring-shaped regions 11d from the inner peripheral side toward the outer peripheral side, and these regions 11d are divided into four partitions in the circumferential direction. The area 11c is partitioned at equal intervals. And the heater 12 is arrange | positioned to these inner area | region 11a and 12 division area | regions 11c, respectively. A temperature sensor 13 is provided below the heating plate 11 so as to correspond to each heater 12. As described above, by increasing the number of the temperature sensors 13 as compared with the example of FIG. 1 described above, it is highly accurate whether or not the standard deviation when the wafer W rides on the minute object is larger than the threshold value. Can be detected. In FIG. 9, the temperature sensor 13 is not shown.

Further, as a temperature detection value of the temperature sensor 13 used for setting the standard deviation and the threshold value, the wafer W is placed on the heating plate 11 and the heating plate 11 is mounted as shown in an example described later. The temperature detection value in the range from 0.8 to 1.5 seconds after the wafer W is placed on the heating plate 11 may be used during the period from when the temperature starts to fall to the set temperature. In addition, an integrated value of the temperature detection value within the range may be used. The range may vary depending on the thickness dimension of the wafer W, the output value of the heater 12, the number and dimensions of the proximity pins 15, and so on, and is set individually according to the apparatus and recipe.
In the above-described example, the temperature detection value of each temperature sensor 13 at a certain time point (for example, after 1 second) ranging from 0.8 to 1.5 seconds after the wafer W is placed on the heating plate 11. Although the standard deviation was calculated based on the above, the present invention is not limited to this example. Specifically, a temperature detection value is obtained every 0.1 seconds, for example, after 1.5 seconds elapse after the wafer W is placed on the heating plate 11, for example, and this temperature. Based on the detected value, the standard deviation at each time point is calculated, and when each standard deviation is compared with the threshold value at each time point, if any standard deviation is larger than the corresponding threshold value, the alarm 36 is generated. You may let me know. That is, it may be detected whether or not the wafer W has landed on the minute object during a certain period, for example, from when the temperature of the heating plate 11 starts to decrease due to the placement of the wafer W until the temperature returns to the set temperature.

In the above-described example, the standard deviation (σ) of the temperature detection value in each temperature sensor 13 is used to detect whether or not the wafer W is on the minute object. (Σ ² ) may be used. Further, as is apparent from FIGS. 11 and 12 in the embodiments described later, when the wafer W is on a minute object, the difference between the maximum value and the minimum value of the temperature detection value of each temperature sensor 13. (Opening of the temperature detection value) becomes larger than when the wafer W is normally (horizontally) placed on the heating plate 11. That is, when the end portion of the wafer W is on the minute object, the temperature of the heating plate 11 facing the end portion is higher than that of other portions. The value increases. Further, since the wafer W is inclined when the end portion of the wafer W rides on the minute object, the portion facing the end portion in the diameter direction of the wafer W is closer to the heating plate 11 than the other portions. Since the heat of the heating plate 11 is absorbed quickly, the minimum value of each temperature detection value is smaller than in the normal state. Therefore, if the end of the wafer W is on the minute object, the difference described above becomes larger than that in the normal state. For this reason, as a variation value used for detecting whether or not the wafer W is on the minute object, a difference between the maximum value and the minimum value of the temperature detection value may be used instead of the standard deviation.

  Further, although the temperature of the heating plate 11 is used as the temperature detection value for calculating the standard deviation, the temperature of the wafer W may be used instead of the temperature of the heating plate 11. That is, if the wafer W is normally (horizontally) placed on the heating plate 11 without climbing on the minute object, the wafer W is heated uniformly over the surface. On the other hand, for example, when the end portion of the wafer W rides on a minute object, the temperature rise rate is slower at the end portion because it is farther from the heating plate 11 than at other portions, so that it is more in-plane than normal. In this case, the temperature distribution varies. In this case, the temperature sensor 13 may be provided as a radiation thermometer or the like at a position separated from the upper surface side of the heating plate 11 or the upper side with respect to the heating plate 11.

  Further, all the temperature detection values of the temperature sensor 13 are used in calculating the standard deviation and the threshold value, but at least two of the temperature detection values of the temperature sensor 13 may be used. Further, although the temperature sensor 13 is arranged corresponding to the arrangement position of the heater 12, a dedicated temperature for calculating the standard deviation and the threshold is provided separately from the temperature sensor 13 for adjusting the output value of the heater 12. A sensor may be provided separately.

  Further, although the plurality of heaters 12 are arranged on the heating plate 11, one heater 12 may be arranged and the temperature sensors 13 may be provided at a plurality of locations as described above. In this case, as shown in FIG. 10, for example, a circular surface heater corresponding to the wafer W placed on the heating plate 11 is used as the heater 12. In addition, FIG. 10 shows an example in which the temperature sensor 13 is disposed at the central portion of the wafer W on the back surface side of the heating plate 11 and is provided at eight locations so as to be separated from each other in the circumferential direction of the wafer W at the outer peripheral portion. ing. In this case, as the temperature sensor 13 for adjusting the output value of the heater 12, for example, the temperature sensor 13 at the center of these temperature sensors 13 is used.

  Further, in the above-described example, the case where the end of the wafer W climbs on the minute object and is tilted is detected. However, for example, minute objects of the same size are arranged on the heating plate 11 in the circumferential direction. When the wafer W is attached to a plurality of locations, the wafer W may be substantially parallel to the heating plate 11 when the wafer W rides on these minute objects. However, even in such a case, when transferring heat from the heating plate 11 to the wafer W via the minute object, it is considered that the amount of heat transfer varies for each minute object, and thus the wafer W rides on the minute object. It is determined whether or not.

  The substrate heating apparatus described above is a coating / developing apparatus that performs a resist film coating process or a resist film developing process on the wafer W, for example, after applying a resist solution to the wafer (pre-baking) or the coating process.・ After exposure processing (post-exposure baking) with an exposure device connected to the development device, and further after development processing (post-baking), it is applied as a heating device to heat the wafer W Is done.

  Then, the result confirmed by actually experimenting about the method of this invention is demonstrated. First, as the substrate heating apparatus, as shown in FIG. 9 described above, the heating plate 11 provided with 13 channels (13 pieces) each of the heater 12 and the temperature sensor 13 was used. Then, a minute object having a dimension of 500 μm was left on the heating plate 11 and the heating plate 11 was set to 80 ° C. Next, the wafer W was placed on the heating plate 11 and the temperature detection value of each temperature sensor 13 was read. The thin lines in FIG. 11 indicate the temperature detection values of these temperature sensors 13. Moreover, the standard deviation of these temperature detection values was calculated and shown by a thick line in FIG. In FIG. 11, the “wafer heating time” on the horizontal axis indicates the elapsed time from the time when the wafer W is placed on the heating plate 11.

  On the other hand, the temperature detection value and the standard deviation of each temperature sensor 13 were similarly obtained when a minute object was not placed on the heating plate 11, that is, when the wafer W was placed horizontally on the heating plate 11. . In FIG. 12, which shows the result in this case, the temperature detection values of the respective temperature sensors 13 are more uniform than in the example of FIG. 11, and the standard deviation is lower (the variation is smaller) than in the example of FIG.

  Accordingly, the standard deviations of FIGS. 11 and 12 are collectively shown in one graph, and when the difference between these standard deviations is taken, a clear difference is confirmed between the standard deviations as shown in FIG. It was. That is, the standard deviation at the normal time (FIG. 12) is smaller than the standard deviation at the time of climbing the minute object (FIG. 11), and is particularly different between the elapsed times of 0.8 to 1.5 seconds. Was getting bigger. Therefore, it can be seen that by using the standard deviation between 0.8 and 1.5 seconds as described above, it can be easily detected with high accuracy whether or not the wafer W has landed on the minute object.

  Here, when the edge of the wafer W is on the minute object (FIG. 11), the maximum value and the minimum value when viewed at a certain time (wafer heating time) as compared with the normal time (FIG. 12). It can be seen that the difference from the value is large. That is, when the end portion of the wafer W is on the minute object, the temperature of the heating plate 11 facing the end portion is higher than that of other portions. The value increases. Further, when the end of the wafer W is placed on the minute object, the wafer W is inclined as described above. Therefore, in the portion facing the end in the diameter direction of the wafer W, the heating plate is more than normal. 11, the temperature of the heating plate 11 is quickly absorbed by the wafer W, and the temperature may be lower than other portions. In this case, the minimum value of each temperature detection value is smaller than that in the normal state. For this reason, it is considered that the difference between the maximum value and the minimum value of the temperature detection value is different between the abnormal time and the normal time.

  Subsequently, for the cases where the set temperature was 80 ° C. and 160 ° C., the difference in standard deviation corresponding to FIG. 13 described above was obtained. As a result, as shown in FIG. 14 and FIG. 15, it was found that the higher the set temperature, the greater the difference in standard deviation between when normal and when climbing a minute object.

W Wafer 11 Heating plate 12 Heater 13 Temperature sensor 31 Temperature controller 34a, 34b, 34c Program 35 Memory 36 Alarm

Claims (11)

In the substrate heating apparatus that heats the substrate placed on the heating plate to the set temperature by the heating unit,
A plurality of temperature measuring units that are provided apart from each other in the direction of the plate surface of the heating plate and measure the temperature of at least one of the heating plate and the substrate;
A temperature variation calculation unit that calculates a value of variation between the temperature measurement values of the plurality of temperature measurement units after placing the substrate on the heating plate;
In order to determine whether or not the substrate is on a foreign object on the heating plate, a comparison unit that compares the value of variation of the temperature measurement value with a preset threshold value is provided. A substrate heating apparatus.   The substrate heating apparatus according to claim 1, wherein the heating unit is provided at a plurality of locations so as to correspond to the arrangement position of the temperature measurement unit.   The substrate heating apparatus according to claim 1, wherein the variation value calculated by the temperature variation calculation unit is a standard deviation of the measured temperature.   The threshold value is a value set in advance based on a variation value calculated by the temperature variation calculation unit when a substrate is horizontally placed on the heating plate. The substrate heating apparatus according to any one of 1 to 3.   5. An alarm issuing unit that is issued when the comparison unit detects that the variation value is larger than the threshold value. The substrate heating apparatus as described. In the substrate heating method of heating the substrate placed on the heating plate to the set temperature by the heating unit,
Placing the substrate on the heating plate;
Next, a step of measuring the temperature of at least one of the heating plate and the substrate after placing the substrate on the heating plate by a plurality of temperature measurement units provided apart from each other in the direction of the plate surface of the heating plate; ,
Subsequently, a step of calculating a variation value between each temperature measurement value of the plurality of temperature measurement units,
Thereafter, the temperature variation value calculated in the calculating step is compared with a preset threshold value, and based on the comparison result, it is determined whether or not the substrate is on a foreign object on the heating plate. And a step of heating the substrate.   The said heating plate WHEREIN: A board | substrate is heated by the said heating part provided in multiple places so as to correspond to the arrangement position of the said temperature measurement part, The board | substrate heating method of Claim 6 characterized by the above-mentioned.   The substrate heating method according to claim 6, wherein the variation value calculated in the calculating step is a standard deviation of the measured temperature.   9. The step of issuing an alarm when the value of variation is larger than the threshold value in the step of comparing after the step of comparing. The substrate heating method as described in one. Before the step of placing the substrate on the heating plate,
Placing the substrate horizontally on the heating plate, and calculating a variation value for each temperature measurement value of the plurality of temperature measurement units;
The substrate heating method according to claim 6, wherein the threshold value is set based on a variation value calculated in the step. A storage medium storing a program used in a substrate heating device for heating a substrate placed on a heating plate,
11. A storage medium characterized in that the program includes a group of steps so as to implement the substrate heating method according to claim 6.

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