JP2011146542A - Heat treatment apparatus, heat treatment method and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment apparatus capable of continuously monitoring an exhaust air flow rate. <P>SOLUTION: An exhaust pipe 54 which is connected to a container for heating and treating a coating film formed on a wafer and has a flow rate adjusting portion, for example, a fan interposed is provided with a heater 71 which heats a gas up to a sublimation temperature of a sublimate from the coating film or higher, and first temperature sensors 72 and second temperature sensors 73 disposed upstream and downstream from the heater 71. Here, the temperature sensors 72 and 73 are provided peripherally at opposite positions, exhaust air flow rate measured values obtained from temperature detection values of sets of the respective first temperature sensors 72 and the second temperature sensors 73 are averaged, and the average value is used as an exhaust air flow rate measured value for flow rate control, for example, for the fan. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat treatment apparatus and a heat treatment method for placing a substrate on a hot plate in a container and heat-treating a coating film formed on the substrate.

  In the photoresist process, which is one of the semiconductor manufacturing processes, a resist is applied to the surface of a substrate, for example, a semiconductor wafer (hereinafter simply referred to as “wafer”), the resist is exposed in a predetermined pattern, and then developed. A resist pattern is formed. Such processing is generally performed using a resist pattern forming system in which an exposure apparatus is connected to a resist coating and developing apparatus. The coating and developing apparatus includes a heat treatment apparatus for heating the wafer. It has been incorporated. In this heat treatment apparatus, after a wafer having a resist film (coating film) formed on the surface thereof is accommodated in the container, the wafer is placed on a heating plate provided in the container and heat treatment is performed. At this time, for example, nitrogen gas is supplied to the inside of the container, and the gas inside the container is discharged through the exhaust path.

In such a heat treatment apparatus, it is important to monitor the exhaust gas flow rate. For example, when connecting an exhaust passage to an exhaust duct in a factory, it is necessary to determine whether or not the exhaust air is exhausted at the designed exhaust flow rate, and whether or not the exhaust passage is clogged. It also becomes. Further, when adjusting the exhaust flow rate by providing a flow rate adjusting unit in the exhaust path, a detected value of the exhaust flow rate is required. Therefore, conventionally, a throttle is provided in the middle of the exhaust passage, and the amount of gas discharged from the container is detected by the difference between the pressure upstream of the throttle and the pressure at the portion where the throttle is provided. However, if the sublimate from the coating film adheres to the area where the diaphragm is provided, there is a risk of clogging the exhaust passage, which tends to increase the frequency of maintenance. In particular, since the temperature of the gas decreases with increasing distance from the heat treatment apparatus, such a concern is great when the heat treatment apparatus and the diaphragm are separated.
In paragraph 0034 of Patent Document 1, in order to prevent the sublimate from the coating film from adhering to the exhaust passage, the length of the air passage on the downstream side of the heat treatment apparatus is set to a short length of about 20 mm. Is described. Further, paragraph 0008 of Patent Document 1 also describes that when the sublimate from the coating film adheres to the exhaust passage, the exhaust passage is clogged and the exhaust flow rate is reduced. However, Patent Document 1 does not specifically describe the measurement of the exhaust gas flow rate.
Further, paragraph 0003 of Patent Document 2 describes providing a mass flow controller in the supply system, but does not describe measuring the exhaust flow rate.

JP 2008-166604 A JP 2003-303023 A

The present invention has been made under such a background, and its purpose is as follows.
An object of the present invention is to provide a technique capable of stably monitoring an exhaust flow rate in a heat treatment apparatus that heat-treats a coating film formed on a substrate with a hot plate in a container.

The heat treatment apparatus of the present invention is a heat treatment apparatus in which a substrate is placed on a hot plate in a container and a coating film formed on the substrate is heat-treated.
An exhaust path for exhausting the atmosphere in the container;
A heating unit that is provided in the exhaust passage and heats the gas passing through the exhaust passage to a temperature higher than the sublimation temperature of the sublimate from the coating film;
A first temperature detection unit for detecting a temperature upstream of the heating unit in the exhaust path;
A second temperature detection unit for detecting a temperature downstream of the heating unit in the exhaust path;
A flow rate measuring unit configured to measure an exhaust flow rate of the exhaust path based on detection results of the first temperature detecting unit and the second temperature detecting unit.

Specific examples of the present invention include the following configurations.
(1) A plurality of the first temperature detection unit and the second temperature detection unit are provided in the circumferential direction of the exhaust passage.
(2) The plurality of second temperature detectors are provided at positions corresponding to the first temperature detectors.
(3) The flow rate measuring unit calculates a value obtained by averaging the exhaust flow rates detected by the pairs of the first temperature detection unit and the second temperature detection unit corresponding to each other as the exhaust flow rate of the exhaust passage. The detection value.
(4) The flow rate measurement unit measures an exhaust flow rate based on an average value of temperatures detected by the plurality of first temperature detection units and an average value of temperatures detected by the plurality of second temperature detection units. To do.
(5) An exhaust flow rate adjusting unit for adjusting the exhaust flow rate from the container, and a control signal for controlling the exhaust flow rate adjusting unit based on the exhaust flow rate set in advance and the exhaust flow rate measured by the flow rate measuring unit are output. And a means comprising:

The heat treatment method of the present invention includes a step of bringing the substrate into a container;
Placing the substrate on the hot plate in the container and heating;
Exhausting the atmosphere in the container through an exhaust path;
A step of heating the gas passing through the exhaust passage to a temperature equal to or higher than a sublimation temperature of the sublimate from the coating film by a heating unit;
Detecting the upstream and downstream temperatures of the heating unit in the exhaust passage by the first temperature detection unit and the second detection unit, respectively,
And a step of measuring an exhaust flow rate of the exhaust passage based on a detection result of the first temperature detection unit and a detection result of the second temperature detection unit.

  According to the present invention, since the exhaust flow rate is measured based on the detection results of the first temperature detection unit and the second temperature detection unit, it is not necessary to restrict the middle of the exhaust path, and the exhaust path is clogged. The risk of doing so can be reduced. Moreover, since the gas passing through the exhaust passage is heated to a temperature higher than the sublimation temperature of the coating film, it is possible to reliably prevent clogging in the exhaust passage. Therefore, the exhaust flow rate can be monitored stably.

It is a vertical side view which shows embodiment of the heat processing apparatus of this invention. It is a cross-sectional top view of the said heat processing apparatus. It is a perspective view which shows the part attached to the exhaust pipe in the exhaust flow measurement part used for the said heat processing apparatus. FIG. 4 is a cross-sectional view showing an exhaust pipe and a heater shown in FIG. FIG. 4 is a cross-sectional view showing an exhaust pipe and a temperature sensor shown in FIG. It is a block diagram which shows an exhaust flow measurement part.

  As an example of an embodiment of a heat treatment apparatus according to the present invention, for example, a heat treatment apparatus for heat-treating a semiconductor wafer (hereinafter abbreviated as a wafer) which is a substrate on which a resist film as a coating film is formed is shown in FIG. This will be described with reference to FIG. First, the main body portion 2 of the heat treatment apparatus will be briefly described. The main body portion 2 includes a flat rectangular housing 20, and a wafer transfer port 21 that is opened and closed by a shutter 21 a is formed on the side wall of the housing 20.

  A base 22 is provided in the lower part of the housing 20, and when the side toward the transport port 21 is the front side, a front side position (position of FIG. 1) is guided by a guide mechanism (not shown) along the base 22. A cooling plate 25 is provided that is movable between the rear side and an upper position of a later-described hot plate 41. The cooling plate 25 transfers the wafer to / from an external transfer arm carried in via the transfer port 21 through the lifting / lowering operation of the three lifting / lowering pins 23a and 3 to / from the heat plate 41. The wafer is transferred through the lifting / lowering operation of the lifting pins 24a. In the figure, W is a wafer, and 23 and 24 are elevating mechanisms. A gas discharge unit 31 is provided on the back side in the housing 20. As shown in FIG. 2, the gas discharge section 31 is configured by arranging discharge ports 33 formed of a large number of small holes facing upward on the back side so as to cover the diameter of the wafer. The gas discharge unit 31 is supplied with an inert gas such as a purge gas such as nitrogen gas via a gas supply pipe 34, and has the same temperature as the wafer heating temperature (wafer surface temperature during heating) in the gas discharge unit 31. The temperature is adjusted to be discharged from the discharge port 33.

The hot plate 41 has a heater (not shown) inside, and is configured in a circular shape, for example. An exhaust part 51 is provided so as to face the gas discharge part 31 with the hot plate 41 interposed therebetween. As shown in FIG. 3, the exhaust portion 51 is configured by arranging exhaust ports 53 formed of a large number of small holes facing upward on the front side so as to cover the diameter of the wafer. The exhaust unit 51 is connected to, for example, a factory exhaust path via an exhaust pipe 54 that constitutes the exhaust path 66 and has, for example, a perfect cross section. The exhaust pipe 54 is provided with a fan 55 as an exhaust flow rate adjusting unit, and the exhaust flow rate is controlled by controlling the rotation speed of the fan 55. In FIG. 1, V1 and V2 are valves.
A top plate 62 is provided in the housing 20 so as to face the hot plate 41, and the inert gas discharged from the gas discharge unit 31 on the front side is separated from the top plate 62 and the hot plate 41. Flows toward the discharge unit 51 on the back side, and thus a one-way flow is formed.

  On the downstream side of the fan 55 in the exhaust pipe 54, a heater 71 as a heating unit is provided as shown in FIGS. The heater 71 is made of, for example, a rubber heater, and is wound around the outer periphery of the exhaust pipe 54 so that the inner surface of the exhaust pipe 54 is heated to a temperature at which the sublimate from the coating film on the wafer surface does not adhere, that is, the sublimation temperature or higher. The heat generation is controlled by a device controller described later.

  A first temperature sensor 72 serving as a first temperature detection unit and a second temperature sensor 73 serving as a second temperature detection unit are provided on the upstream side and the downstream side of the heater 71 in the exhaust pipe 54, respectively. These temperature sensors 72 and 73 are for detecting the temperature of the exhaust flow flowing in the exhaust pipe 54. In this example, the temperature of the exhaust flow is detected via the tube wall of the exhaust pipe 54. These temperature sensors 72 and 73 are, for example, thermocouples, but may be thermistors or the like. A plurality of, for example, four first temperature sensors 72 are arranged at equal intervals along the circumferential direction of the exhaust pipe 54. FIG. 4 is a cross-sectional view of the exhaust pipe 54 at a portion where the first temperature sensor 72 is disposed. As shown in FIG. 4, each of the first temperature sensors 72 is disposed on the outer peripheral surface of the exhaust pipe 54. It fits in the formed recessed part 70, and is further fixed with the adhesive agent 70a.

  The second temperature sensor 73 is provided symmetrically with the first temperature sensor 72 with respect to the heater 71. That is, four second temperature sensors 73 are also arranged at equal intervals along the circumferential direction of the exhaust pipe 54, and the positions of each temperature sensor 73 are extended from the exhaust pipe 54 as viewed from each of the first temperature sensors 72. It is located in the direction of going, that is, in the direction of the axis of the exhaust pipe 54. In other words, it can be said that each of the second temperature sensors 73 is provided at a position corresponding to each of the first temperature sensors 72. The installation structure of the second temperature sensor 73 is the same as that of the first temperature sensor 72, and the distance from the heater 71 is also the same as that of the first temperature sensor 72.

  The heat treatment apparatus includes an apparatus controller 8 as shown in FIG. The device controller 8 includes a storage unit 81, an exhaust flow rate control unit 82, and a power control unit 83. The storage unit 81 stores a processing recipe for heat processing performed in the apparatus main body 2. In this processing recipe, the values of process parameters such as the operation of each operation part and the temperature of the hot plate 41 are described in time series according to the type of wafer (type of coating film). A flow rate setting value is input to the exhaust flow rate control unit 82. This setting value is uniformly determined regardless of the type of coating film when it is written in the processing recipe as a value corresponding to the type of coating film. May have been. A measured value of the exhaust flow rate is input to the exhaust flow rate control unit 82, and a control signal for the fan 55 is output by, for example, PID calculation based on a deviation from the flow rate set value. This measured value will be described later.

  The power control unit 83 controls the temperature of the heater 71 via the power supply unit 75 for controlling the power of the heater 71 based on the temperature detection value and the temperature setting value of the temperature sensor 74 that detects the temperature of the heater 71. It is for control. The temperature sensor 74 is composed of a thermocouple, for example, and is attached to the outer peripheral surface of the exhaust pipe 54 in the region where the heater 71 is disposed. The temperature of the exhaust pipe 54 corresponding to the temperature set value is a temperature at which the sublimate from the coating film on the wafer does not adhere to the inner wall of the exhaust pipe 54 and is a temperature equal to or higher than the sublimation temperature. Therefore, this temperature set value is written in the processing recipe, and a value corresponding to the type of coating film being processed is read from the processing recipe and input to the power control unit 83.

  Further, the temperature detection values of the first temperature sensor 72 and the second temperature sensor 73 are input to the flow rate measuring unit 84 as shown in FIG. The function of the flow rate measuring unit 84 will be described below. The first temperature sensor 72 and the second temperature sensor 73 are provided at equal distances on the upstream side and the downstream side across the heating area of the heater 71 in the exhaust pipe 54. If no gas is flowing, there is no temperature difference between the temperature detection value of the first temperature sensor 72 and the temperature detection value of the second temperature sensor 73. On the other hand, if the gas flows through the exhaust pipe 54, the second temperature sensor 73 receives more heat from the heater 71 than the first temperature sensor 72. It can be seen that there is a temperature difference between the temperature detection value and the temperature detection value of the second temperature sensor 73, and gas flows through the exhaust pipe 54 from this temperature difference.

Since the temperature difference detected by these temperature sensors 72 and 73 and the exhaust flow rate of the gas flowing through the exhaust pipe 54 have a certain relationship, this relationship is written in the program as an algorithm, and the temperature Based on the difference and the algorithm, the exhaust flow rate of the gas flowing through the exhaust pipe 54 can be detected. Instead of using an algorithm, the correspondence between the temperature difference and the exhaust flow rate may be described in a table, and the exhaust flow rate corresponding to the temperature difference may be read from this table. Here, four temperature sensors 72 and 73 are used, and the number of both sets is four. Therefore, a value obtained by averaging the temperature difference of each set is used as the temperature difference used for measuring the exhaust flow rate. Yes.
The flow rate measuring unit 84 includes a CPU and a memory, and software including the above programs and tables is loaded into the memory from a storage medium such as a compact disk or a memory card.

  Next, the operation of the above embodiment will be described. Returning to FIG. 1, for example, when a wafer on which a resist film as a coating film is formed is carried into the housing 20 via the transfer port 21 by the transfer mechanism outside the main body portion 2, via the support pins 23 a. Then, the wafer is transferred to the cooling plate 25. The surface of the hot plate 41 is uniformly heated to, for example, 130 ° C. by the heater 42 until the cooling plate 25 moves onto the hot plate 41. The support pins 24 a are raised by the elevating mechanism 24, and the back surface of the wafer transferred onto the hot plate 41 is supported by the cooling plate 25. When the cooling plate 25 is retracted, the support pins 24 a are lowered by the elevating mechanism 24, and the wafer is transferred onto the hot plate 41.

  The wafer is heated on the hot plate 41 at a set temperature of about 100 degrees, for example. At this time, the valve V <b> 1 is opened, and the purge gas is supplied from the gas supply source 36 to the gas supply pipe 34. The purge gas is heated to the set temperature of the heat treatment by the discharge unit 31 and discharged from the discharge port 33 toward the top plate 62 and flows between the top plate 62 and the heat plate 41 from the near side to the back side. . The purge gas that has passed around the wafer flows into the exhaust pipe 54 and is removed to the outside of the housing 20. At this time, the fan 55 is driven, and exhaust is performed from the exhaust pipe 51 at a predetermined flow rate, in this example, a slightly higher flow rate than the purge gas supply flow rate.

  When the wafer is heated, the sublimate from the coating film on the wafer is exhausted through the exhaust pipe 54 together with the purge gas. Further, the heater 71 is controlled by the power control unit 83 so that the temperature of the heating region of the exhaust pipe 54 becomes a temperature corresponding to the processing recipe, that is, the temperature of the sublimated material from the resist film is higher than the sublimation temperature. As a result, the sublimated material from the coating film passes through the exhaust pipe 54 without adhering to the inner wall. As described above, when the exhaust flow rate is large, the temperature of the gas on the downstream side of the heater 71 becomes high. Therefore, the temperature difference between the temperature sensors 72 and 73 becomes large, and the flow rate measurement value in the flow rate measurement unit 84 becomes large. Thus, the rotational speed of the fan (exhaust flow rate adjusting unit) 55 is lowered by the control operation of the exhaust flow rate control unit 82. On the other hand, when the exhaust flow rate is small, the temperature difference between the temperature sensors 72 and 73 becomes small, the flow rate measurement value in the flow rate measurement unit 84 becomes large, and the rotational speed of the fan 55 is increased.

  Here, in the flow rate measurement unit 76, as described above, the temperature is set for each set of the first temperature sensor 72 and the second temperature sensor 73 (the set of temperature sensors 72 and 73 arranged in the axial direction of the exhaust pipe 54). The difference is obtained, the temperature differences of the four sets obtained are averaged, and the exhaust gas flow rate is calculated by applying the average temperature difference to the algorithm. In this calculation method, an exhaust flow rate may be obtained for each set of temperature differences, and the exhaust flow rates may be averaged.

According to the heat treatment apparatus 7 of the present embodiment, since the exhaust flow rate is output based on the detection results of the first temperature sensor 72 and the second temperature sensor 73, it is not necessary to place a throttle in the middle of the exhaust pipe 54. The possibility of clogging in the exhaust pipe 54 can be reduced. Moreover, since the gas passing through the exhaust pipe 54 is heated to a temperature higher than the sublimation temperature from the resist, it is possible to reliably prevent the exhaust pipe 54 from being clogged. Therefore, the exhaust flow rate can be continuously monitored.
In addition, a plurality of temperature sensors 72 and 73 are provided in the circumferential direction of the exhaust pipe 54, and the flow rate is determined using the temperature difference obtained by the pair of temperature sensors 72 and 73 corresponding to each other. Even when the gas passing through the gas does not form a laminar flow, since the value obtained by averaging the flow rates at a plurality of locations in the circumferential direction is obtained, the exhaust flow rate can be measured with high accuracy.

  In the above-described embodiment, the exhaust fan 55 that is a flow rate adjusting unit is provided on the upstream side of the heater 71, but may be provided on the downstream side. Further, the present invention is not limited to using the value of the exhaust flow rate (estimated exhaust flow rate) obtained by the flow rate measurement unit as a feedback signal in the flow rate adjustment unit. For example, in a device in which the flow rate set value by the fan 55 is constant or a device in which a damper is provided without using the fan 55 and the exhaust flow rate is constant, the measured exhaust flow rate is used as a guide for clogging of the exhaust passage. There may be. The number of temperature sensors 72 and 73 arranged in the circumferential direction of the exhaust pipe 54 is not limited to four, but may be two or three, may be five or more, or one. There may be.

  The heat treatment apparatus according to the present invention is not limited to an apparatus that performs heat treatment on a wafer on which a resist film is formed, and can also be applied to a heat treatment apparatus that performs heat treatment on a wafer after development or exposure. Furthermore, the coating film formed on a substrate such as a wafer may be an insulating film such as a silicon oxide film.

2 Main body portion 20 Housing 41 Heat plate 54 Exhaust pipe 55 Fan (exhaust flow rate adjusting unit)
71 Heater 72 1st temperature sensor (1st temperature detection part)
73 2nd temperature sensor (2nd temperature detection part)
8 Device controller 84 Flow rate measurement unit

Claims (14)

In a heat treatment apparatus for placing a substrate on a hot plate in a container and heat-treating a coating film formed on the substrate,
An exhaust path for exhausting the atmosphere in the container;
A heating unit that is provided in the exhaust passage and heats the gas passing through the exhaust passage to a temperature higher than the sublimation temperature of the sublimate from the coating film;
A first temperature detection unit for detecting a temperature upstream of the heating unit in the exhaust path;
A second temperature detection unit for detecting a temperature downstream of the heating unit in the exhaust path;
A heat treatment apparatus comprising: a flow rate measurement unit that measures an exhaust flow rate of the exhaust passage based on detection results of the first temperature detection unit and the second temperature detection unit.   2. The heat treatment apparatus according to claim 1, wherein a plurality of the first temperature detection unit and the second temperature detection unit are provided in the circumferential direction of the exhaust passage.   The heat treatment apparatus according to claim 2, wherein the plurality of second temperature detection units are provided at positions corresponding to the first temperature detection units, respectively.   The flow rate measurement unit measures the exhaust flow rate of the exhaust passage by averaging the exhaust flow rate measured based on the first temperature detection unit and the second temperature detection unit corresponding to each other. 4. The heat treatment apparatus according to claim 3, wherein the heat treatment apparatus is a value.   The flow rate measuring unit measures an exhaust flow rate based on an average value of temperatures detected by the plurality of first temperature detection units and an average value of temperatures detected by the plurality of second temperature detection units. The heat treatment apparatus according to claim 2 or 3, characterized in that   A storage unit that stores data in which the type of the coating film is associated with the heating temperature of the heating unit, and a unit that reads the heating temperature according to the type of the coating film from the storage unit and controls the heating unit. The heat treatment apparatus according to claim 1, further comprising a heat treatment apparatus. An exhaust flow rate adjusting unit for adjusting the exhaust flow rate from the container;
7. A means for outputting a control signal for controlling the exhaust flow rate adjusting unit based on an exhaust flow rate set in advance and an exhaust flow rate measured by the flow rate measuring unit. The heat processing apparatus as described in any one of these. The heat treatment method of the present invention is a heat treatment method for heat-treating a coating film formed on a substrate.
Carrying the substrate into a container;
Placing the substrate on the hot plate in the container and heating;
Exhausting the atmosphere in the container through an exhaust path;
A step of heating the gas passing through the exhaust passage to a temperature equal to or higher than a sublimation temperature of the sublimate from the coating film by a heating unit;
Detecting the upstream and downstream temperatures of the heating unit in the exhaust passage by the first temperature detection unit and the second detection unit, respectively,
And a step of measuring an exhaust flow rate of the exhaust passage based on a detection result of the first temperature detection unit and a detection result of the second temperature detection unit.   The heat treatment method according to claim 8, wherein a plurality of the first temperature detection unit and the second temperature detection unit are provided in the circumferential direction of the exhaust passage.   The heat treatment method according to claim 9, wherein the plurality of second temperature detection units are provided at positions corresponding to the first temperature detection units, respectively.   The step of detecting the exhaust gas flow rate is obtained by averaging a value obtained by averaging the exhaust gas flow rate measured based on a pair of the first temperature detection unit and the second temperature detection unit corresponding to each other on the exhaust path. The heat treatment method according to claim 10, wherein the heat treatment method is a step of obtaining a flow rate measurement value.   The step of detecting the exhaust flow rate includes measuring an exhaust flow rate based on an average value of temperatures detected by the plurality of first temperature detection units and an average value of temperatures detected by the plurality of second temperature detection units. The heat treatment method according to claim 9, wherein the heat treatment method is a step of setting a value. Adjusting the exhaust flow rate from the container in the exhaust flow rate adjustment unit;
13. The heat treatment method according to claim 8, further comprising: controlling the exhaust flow rate adjusting unit based on a preset exhaust flow rate and a measured exhaust flow rate. A storage medium for storing a computer program used in a heat treatment apparatus that places a substrate on a hot plate in a container and heat-treats a coating film formed on the substrate,
14. A storage medium characterized in that the computer program includes a group of steps so as to perform the heat treatment method according to any one of claims 8 to 13.

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