JP2018120978A - Thermal treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal treatment device arranged so as to be able to prevent the decrease in thermal conductivity even if a sheet-like body to be placed on a thermal treatment plate has a larger thickness.SOLUTION: A thermal treatment device has a support sheet 20 of carbon placed on a top face of a hot plate 10 with a built-in heater 11, and performs a thermal treatment on a substrate W supported on the support sheet 20. The carbon has high rigidity, and the support sheet 20 is relatively thick. Therefore, the support sheet 20 can be prevented from floating from the hot plate 10. In addition, the carbon has a remarkably high thermal conductivity of 1000 W/(mK) or more and as such, the decrease in thermal conductivity can be prevented even if the support sheet 20 placed on the hot plate 10 is replaced with one having a larger thickness. Consequently, even after the start of a thermal treatment with the substrate W supported on the support sheet 20, the uniformity of an in-plane temperature distribution of the substrate W can be restored in a short time. Therefore, the device is capable of performing a thermal treatment on the substrate W while maintaining good in-plane temperature distribution uniformity.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat treatment apparatus for performing heat treatment on a thin precision electronic substrate (hereinafter simply referred to as “substrate”) such as a semiconductor wafer or a glass substrate for a liquid crystal display device.

  As is well known, products such as semiconductors and liquid crystal displays are manufactured by performing a series of processes such as cleaning, resist coating, exposure, development, etching, interlayer insulation film formation, heat treatment, and dicing on the substrate. Has been. Of these various processes, the heat treatment is typically performed by a heat treatment apparatus that places and heats a substrate on a flat plate-like hot plate that is controlled to a predetermined temperature.

  In the heat treatment apparatus, the in-plane temperature distribution uniformity of the substrate during the heat treatment is strongly required. In particular, in post-exposure baking (PEB) in the photolithography process, the in-plane temperature distribution of the substrate being processed directly affects the line width dimension and line width uniformity of the pattern. Uniformity is strictly demanded.

  In Patent Document 1, in order to improve the uniformity of in-plane temperature distribution during heat treatment, a sheet-like body of resin (for example, polyimide (PI)) is placed on a hot plate, and the substrate is formed by the sheet-like body. A technique for supporting the above is disclosed. A plurality of convex portions are formed on the sheet-like body disclosed in Patent Document 1, and the substrate is contacted and supported by the upper ends of the convex portions. By supporting the substrate with such a plurality of convex portions, it is possible to increase the planar accuracy of the substrate being processed and to prevent the lower surface of the substrate from being scratched.

JP 2007-258441 A

  The thickness of the sheet-like body disclosed in Patent Document 1, that is, the length from the upper end of the convex portion to the lower surface of the sheet-like body is 125 μm, which is very thin. When the substrate is brought into contact with and supported by such an extremely thin sheet-like material, if a sticky film or the like is formed on the back surface of the substrate, the sheet-like material sticks to the back surface of the substrate and floats from the hot plate. Sometimes.

  Therefore, if the thickness of the sheet-like body is increased to about 1 mm, the above-described lifting can be prevented. However, when the thickness of the sheet-like body is increased, the thermal conductivity from the hot plate to the substrate is lowered, and as a result, there is a problem that the in-plane temperature distribution uniformity of the substrate is also impaired.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat treatment apparatus capable of preventing a decrease in thermal conductivity even if the sheet-like body placed on the heat treatment plate is thickened. To do.

  In order to solve the above-mentioned problems, a first aspect of the present invention provides a heat treatment apparatus for performing heat treatment on a substrate, a heat treatment plate having a flat upper surface, and a sheet-like shape that is placed on the upper surface of the heat treatment plate and supports the substrate. And the sheet-like body has a thermal conductivity of 1000 W / (m · K) or more.

  According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the sheet-like body is formed of carbon.

  According to a third aspect of the present invention, in the heat treatment apparatus according to the second aspect of the present invention, a fluororesin coating film is provided on the surface of the sheet-like body.

  According to a fourth aspect of the present invention, in the heat treatment apparatus according to any one of the first to third aspects of the present invention, a convex portion is provided on the upper surface of the sheet-like body.

  According to a fifth aspect of the present invention, in the heat treatment apparatus according to any one of the first to third aspects, the upper surface of the sheet-like body is a flat surface.

  According to a sixth aspect of the present invention, in the heat treatment apparatus according to any one of the first to third aspects, a groove is provided on the upper surface of the sheet-like body.

  According to the inventions of claims 1 to 6, since the thermal conductivity of the sheet-like body placed on the upper surface of the heat treatment plate and supporting the substrate is 1000 W / (m · K) or more, the sheet-like body is Even if the thickness is increased, a decrease in thermal conductivity can be prevented.

  In particular, according to the invention of claim 3, since the fluororesin coating film is provided on the surface of the sheet-like body, it is possible to prevent the carbon and the substrate from coming into direct contact and contaminating the substrate.

It is a figure which shows schematic structure of the heat processing apparatus which concerns on this invention. It is an external appearance perspective view of a support sheet. It is the longitudinal cross-sectional view which expanded a part of support sheet. It is a figure which shows the change of the range of the board | substrate heat-processed by the heat processing apparatus. It is an external appearance perspective view which shows the other example of a support sheet. It is an external appearance perspective view which shows the other example of a support sheet.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 performs a heat treatment on the circular substrate W. In FIG. 1 and the subsequent drawings, the size and number of each part are exaggerated or simplified as necessary for easy understanding.

  The heat treatment apparatus 1 includes a hot plate 10 and a support sheet 20 as main components. Further, the heat treatment apparatus 1 includes a suction mechanism 50 and a control unit 60.

  The hot plate 10 is a circular flat plate formed of a metal material having high thermal conductivity (for example, aluminum (Al), copper (Cu), etc.). The upper surface of the hot plate 10 is a flat surface. The diameter of the upper surface of the circular hot plate 10 is larger than the diameter of the substrate W. The substrate W to be processed in the heat treatment apparatus 1 is a silicon disk-shaped semiconductor wafer, and the size thereof is not particularly limited, but is, for example, φ300 mm or φ450 mm. Depending on the size of the substrate W to be processed, the diameter of the hot plate 10 is set to an appropriate size larger than the diameter of the substrate W.

  A heater 11 as a heating source is built in the hot plate 10. The heater 11 is a planar heater that generates heat when energized, such as a mica heater. Typically, the heater 11 is divided into a plurality of zones. For example, a disk-shaped central heater is provided at the center of the hot plate 10, an annular intermediate heater is provided around it, and an annular region around the intermediate heater is divided into four equal parts in the circumferential direction. Four peripheral heaters are provided.

  A support sheet 20 is placed on the flat upper surface of the hot plate 10. FIG. 2 is an external perspective view of the support sheet 20. FIG. 3 is an enlarged longitudinal sectional view of a part of the support sheet 20. The support sheet 20 is a circular sheet-like body having substantially the same diameter as the hot plate 10. The support sheet 20 is placed on the upper surface of the hot plate 10 without being fixed.

  A plurality of convex portions 21 and seal portions 22 are formed on the upper surface of the circular support sheet 20. The plurality of convex portions 21 are regularly arranged on the upper surface of the support sheet 20. The number of the convex portions 21 to be installed is not particularly limited, and can be an appropriate number. Each convex portion 21 has a truncated cone shape whose diameter is slightly thicker from the upper end to the lower end.

  By forming the plurality of convex portions 21, irregularities are formed on the upper surface of the support sheet 20. The height h of the convex portion 21 (the length from the upper end to the lower end of the convex portion 21, in other words, the depth of the concave portion) is, for example, 65 μm. The plurality of protrusions 21 are processed with high accuracy so that the heights h of the plurality of protrusions 21 are uniform. Moreover, the thickness d of the support sheet 20 prescribed | regulated by the length from the upper end of the convex part 21 to the lower surface of the support sheet 20 is 700 micrometers, for example, and is the conventional sheet-like body as disclosed by patent document 1 It is significantly thicker than the thickness (125 μm). The substrate W is abutted and supported by the upper ends of the plurality of convex portions 21. In addition, the lower surface of the support sheet 20 is a flat surface.

  The seal portion 22 has an annular shape, is formed along the peripheral edge portion of the circular support sheet 20, and surrounds the plurality of convex portions 21. The inner diameter of the annular seal portion 22 is smaller than the diameter of the substrate W, and the outer diameter of the seal portion 22 is larger than the diameter of the substrate W. The height of the seal portion 22 is the same as the height of the convex portion 21. A closed space is formed between the upper surface of the support sheet 20 and the lower surface of the substrate W when the peripheral edge of the lower surface of the substrate W supported by the support sheet 20 contacts the seal portion 22. The seal part 22 closes the side of the closed space.

  The support sheet 20 including the plurality of convex portions 21 and the seal portion 22 is made of carbon. The thermal conductivity of carbon is extremely high although it depends on the crystal structure, and is at least 1000 W / (m · K) or more. That is, carbon has a significantly higher thermal conductivity than aluminum (236 W / (m · K)) and copper (398 W / (m · K)), which are said to have good thermal conductivity. In addition, the thermal conductivity of the polyimide used for the conventional sheet-like body is less than 1 W / (m · K).

  The manufacturing method of the support sheet 20 is not particularly limited. For example, the support sheet 20 may be manufactured by sintering carbon powder, or a convex portion 21 and a seal portion 22 which are separately processed are attached to a circular flat plate carbon. Alternatively, the support sheet 20 including the convex portion 21 and the seal portion 22 may be manufactured by grinding from plate-like carbon.

  As shown in FIG. 3, a fluororesin coating film 23 is formed on the upper surface of the support sheet 20 including the convex portions 21 and the seal portions 22. The coating film 23 is provided to prevent the carbon and silicon substrate W from coming into direct contact and contaminating the substrate W.

  Returning to FIG. 1, the heat treatment apparatus 1 is provided with a suction mechanism 50. The suction mechanism 50 includes a suction pipe 51, a valve 52, and a vacuum suction source 53. The suction pipe 51 has a distal end connected to a space formed between the upper surface of the support sheet 20 and the lower surface of the substrate W, and a proximal end connected to the vacuum suction source 53. A valve 52 is provided in the course of the suction pipe 51. As the vacuum suction source 53, for example, a vacuum pump can be used. When the valve 52 is opened while the vacuum suction source 53 is operated while the substrate W is supported by the support sheet 20, a closed space formed between the upper surface of the support sheet 20 and the lower surface of the substrate W is sucked. The substrate W can be adsorbed and supported on the support sheet 20.

  The control unit 60 controls the output of the heater 11 provided on the hot plate 10 and controls the operation of the suction mechanism 50. The configuration of the control unit 60 as hardware is the same as that of a general computer. That is, the control unit 60 includes a CPU that is a circuit that performs various arithmetic processes, a ROM that is a read-only memory that stores basic programs, a RAM that is a readable and writable memory that stores various information, control software, data, and the like. It has a magnetic disk to store. The output of the heater 11 is controlled by the CPU of the control unit 60 executing a predetermined processing program. The controller 60 is also connected to a temperature sensor (not shown) provided on the hot plate 10 and feedback-controls the output of the heater 11 based on the temperature measurement result of the temperature sensor.

  In addition to the above configuration, the heat treatment apparatus 1 includes, for example, lift pins that can be lifted and lowered when the substrate W is transferred to the hot plate 10, a cover that covers the upper portion of the hot plate 10 during the heat treatment of the substrate W, and the like. Provided (both not shown).

  Next, the heat treatment operation of the substrate W in the heat treatment apparatus 1 having the above configuration will be described. Prior to the heat treatment of the substrate W to be processed, the hot plate 10 is heated to a preset temperature (eg, 110 ° C.) by the heater 11 under the control of the control unit 60. A support sheet 20 is placed on the upper surface of the heated hot plate 10.

  The substrate W to be processed is placed and supported on the upper surface of the support sheet 20. The substrate W is abutted and supported by the plurality of convex portions 21 of the support sheet 20. That is, the upper ends of the plurality of convex portions 21 are in contact with the lower surface of the substrate W to support the substrate W. Since the height h of the plurality of convex portions 21 is uniform, the substrate W is supported by the support sheet 20 in a flat posture. When higher planar accuracy of the substrate W is required, the suction mechanism 50 sucks the closed space formed between the upper surface of the support sheet 20 and the lower surface of the substrate W, so that the substrate W is placed on the support sheet 20. It may be supported by adsorption.

  When the substrate W is supported by the support sheet 20, the heat of the hot plate 10 whose temperature has been raised is conducted to the substrate W through the support sheet 20, and the substrate W is heated. Since the thermal conductivity of the carbon support sheet 20 is as high as 1000 W / (m · K) or more, the thermal conductivity from the hot plate 10 to the substrate W through the support sheet 20 is good.

  Ideally, the heating of the substrate W is started immediately after the substrate W is placed on the support sheet 20 and the temperature is uniformly increased over the entire surface of the substrate W. Variation occurs. The difference between the highest temperature and the lowest temperature in the surface of the substrate W at the same time is called a “range”. For example, if the maximum temperature in the plane of the substrate W at a certain time is 68.5 ° C. and the minimum temperature is 66.4 ° C., the range is 2.1 ° C. The smaller the range, the smaller the difference between the highest temperature and the lowest temperature in the surface of the substrate W, and the uniform temperature distribution in the surface. If the heat treatment temperature of the substrate W is 110 ° C., it can be said that the in-plane temperature distribution uniformity is good if the range is 0.1 ° C. or less.

  FIG. 4 is a diagram showing a change in the range of the substrate W to be heat-treated by the heat treatment apparatus 1. At time t1, the substrate W is placed on the support sheet 20, and heating of the substrate W is started. The substrate W is heated and heated by heat conduction from the hot plate 10 to the substrate W via the carbon support sheet 20. In the temperature rising process immediately after the substrate W is supported by the support sheet 20, the range is inevitably increased. Then, the range reaches the maximum value at time t2. That is, the variation in the in-plane temperature distribution of the substrate W becomes the largest at time t2.

  After the range reaches the maximum value at time t2, the range value starts to decrease. At time t3, the range decreases to 0.1 ° C. or less, and the in-plane temperature distribution uniformity of the substrate W is restored. That is, the uniformity of the in-plane temperature distribution of the substrate W is recovered after the time (t3-t1) after the substrate W is placed on the support sheet 20.

  Here, a dotted line in FIG. 4 shows that a conventional polyimide sheet is placed on a hot plate instead of the carbon support sheet 20, and the substrate W is supported by the polyimide sheet. This is a change in the range when the heat treatment is performed. Even when a conventional polyimide sheet is used, the range becomes large immediately after the start of heating the substrate W, and then starts decreasing after reaching the maximum value. However, as shown in FIG. 4, when the conventional polyimide sheet-like body is used, the inclination in which the range decreases is more gradual than when the carbon support sheet 20 is used, and the range is 0.1 ° C. or less. Is time t4 after time t3. That is, the in-plane temperature distribution uniformity of the substrate W is restored after the time (t4-t1) after the substrate W is placed on the polyimide sheet. As apparent from FIG. 4, (t3-t1) is shorter than (t4-t1), and the in-plane temperature of the substrate W is shorter in a shorter time than the conventional polyimide sheet-like body by using the carbon support sheet 20. Distribution uniformity can be restored. According to the investigation by the inventors of the present invention, when the thickness of the polyimide sheet is made as thick as the support sheet 20 of the present embodiment, the range is not reduced to 0.1 ° C. or lower in the first place, It has been found that the in-plane temperature distribution uniformity of W does not recover.

  In this way, by performing the heat treatment by supporting the substrate W on the carbon support sheet 20 having a thermal conductivity of 1000 W / (m · K) or more, the in-plane temperature distribution uniformity of the substrate W after the heating is started. It will recover in a short time. And the heat processing of the board | substrate W will be performed, maintaining favorable in-plane temperature distribution uniformity.

  In particular, when the heat treatment by the heat treatment apparatus 1 is a post-exposure bake treatment (PEB), if it takes a long time to recover the in-plane temperature distribution uniformity of the substrate W after the heat treatment is started, the heating is started. The variation in the in-plane temperature distribution immediately after remains as a thermal history, and the line width dimension and line width uniformity of the pattern tend to be non-uniform. Even in the post-exposure baking, if the in-plane temperature distribution uniformity of the substrate W after the start of heating can be recovered in a short time by supporting the substrate W on the carbon support sheet 20 and performing the heat treatment, The uniformity of heat history can also be improved, and the line width dimension and line width uniformity of the pattern can be made uniform.

  After the heat treatment of the substrate W for a predetermined time is completed, the substrate W is unloaded from the hot plate 10. In the case where the substrate W is sucked and supported on the support sheet 20 by the suction mechanism 50, after the closed space formed between the upper surface of the support sheet 20 and the lower surface of the substrate W is restored and the suction is released. The substrate W is unloaded.

  In the present embodiment, a carbon support sheet 20 having a thermal conductivity of 1000 W / (m · K) or more is placed on the upper surface of the hot plate 10, and the substrate W is supported on the support sheet 20 and heat treatment is performed. ing. The carbon constituting the support sheet 20 has higher rigidity than the resin material, and the thickness d of the support sheet 20 is relatively thick as 700 μm. For this reason, the carbon support sheet 20 is not easily deformed, and the support sheet 20 sticks to the back surface of the substrate W even when an adhesive film or the like is formed on the back surface of the substrate W. The floating from the plate 10 can be prevented.

  In addition, the thermal conductivity of the carbon support sheet 20 is as extremely high as 1000 W / (m · K) or more, and even if the support sheet 20 placed on the hot plate 10 is thickened, it is possible to prevent a decrease in thermal conductivity. The thermal conductivity from the hot plate 10 to the substrate W through the support sheet 20 is very good. As a result, the in-plane temperature distribution uniformity of the substrate W after supporting the substrate W on the support sheet 20 and starting the heat treatment is recovered in a short time, while maintaining good in-plane temperature distribution uniformity. Then, the heat treatment of the substrate W can be performed.

  While the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention. For example, in the above embodiment, the support sheet 20 is formed of carbon, but is not limited to this, and is formed of another material having a thermal conductivity of 1000 W / (m · K) or more. May be.

  Moreover, in the said embodiment, although the some convex part 21 was formed on the upper surface of the support sheet 20, the shape of a support sheet may be another form as shown below. 5 and 6 are external perspective views showing other examples of the support sheet. The upper surface of the support sheet 120 shown in FIG. 5 is a flat surface. If the upper surface of the support sheet 120 is a flat surface, the adhesion between the supported substrate W and the support sheet 120 is improved, and the thermal conductivity from the hot plate 10 to the substrate W through the support sheet 120 is further improved. It will be a thing. However, since it is very difficult to process the upper surface of the support sheet 120 to be a completely flat surface, the planar accuracy of the substrate W supported by the support sheet 120 may be lower than that in the above embodiment.

  On the other hand, a plurality of grooves 221 are formed on the upper surface of the support sheet 220 shown in FIG. The number of grooves 221 and the manner of engraving are not particularly limited, but in the example of FIG. 6, three grooves 221 along the radial direction of the circular support sheet 220 are provided at intervals of 60 °. Yes.

  Both the support sheet 120 shown in FIG. 5 and the support sheet 220 shown in FIG. 6 are made of carbon as in the above embodiment. Further, the lower surfaces of the support sheet 120 and the support sheet 220 are flat surfaces, and the thickness is about 700 μm. By forming the support sheet 120 and the support sheet 220 with carbon having a thermal conductivity of 1000 W / (m · K) or more, the thermal conductivity is maintained even when the support sheets 120 and 220 placed on the hot plate 10 are thickened. Can be prevented, and the thermal conductivity from the hot plate 10 to the substrate W through the support sheets 120 and 220 can be improved. As a result, as in the above embodiment, the in-plane temperature distribution uniformity of the substrate W after the substrate W is supported on the support sheets 120 and 220 and the heat treatment is started is recovered in a short time. The substrate W can be heat-treated while maintaining the internal temperature distribution uniformity.

  In the above embodiment, the fluororesin coating film 23 is formed on the upper surface of the support sheet 20. However, the coating film 23 is not essential, and there is a problem even if the carbon and the substrate W are in direct contact. If not, the coating film 23 may not be formed.

  The heat treatment apparatus 1 is not limited to the one that heat-treats the substrate W, but a carbon support sheet 20 is placed on a cool plate, and the substrate W after heating is supported on the support sheet 20 to perform a cooling process. It may be a thing. In other words, the heat treatment apparatus 1 only needs to perform heat treatment on the substrate W.

  Furthermore, the substrate W to be processed by the heat treatment apparatus 1 is not limited to a semiconductor wafer, and may be a glass substrate or a solar cell substrate used for a flat panel display such as a liquid crystal display device.

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 10 Hot plate 11 Heater 20,120,220 Support sheet 21 Convex part 22 Seal part 23 Coating film 50 Suction mechanism 60 Control part 221 Groove W Substrate

Claims (6)

A heat treatment apparatus for performing heat treatment on a substrate,
A heat treatment plate having a flat upper surface;
A sheet-like body placed on the upper surface of the heat treatment plate to support the substrate;
With
The heat conductivity of the said sheet-like body is 1000 W / (m * K) or more, The heat processing apparatus characterized by the above-mentioned. The heat treatment apparatus according to claim 1, wherein
The heat treatment apparatus, wherein the sheet-like body is made of carbon. The heat treatment apparatus according to claim 2,
A heat treatment apparatus, wherein a coating film of a fluororesin is provided on a surface of the sheet-like body. In the heat processing apparatus in any one of Claims 1-3,
A heat treatment apparatus, wherein a convex portion is provided on an upper surface of the sheet-like body. In the heat processing apparatus in any one of Claims 1-3,
A heat treatment apparatus, wherein an upper surface of the sheet-like body is a flat surface. In the heat processing apparatus in any one of Claims 1-3,
A heat treatment apparatus, wherein a groove is provided on an upper surface of the sheet-like body.

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