Heating device and heating method

Abstract

To improve the in-plane uniformity of a heat process in which a substrate is heated to dry a coating film formed on the substrate.SOLUTION: A heating device for heating a substrate includes a heating plate on which the substrate is placed for heating the placed substrate, a gas inlet portion for making a gas flow into a space above the heating plate, and an exhaust portion for exhausting the gas from the space. The gas inlet portion and the exhaust portion are provided so as to sandwich the substrate placed on the heating plate and oppose each other in plan view. A gas supply portion is further included for supplying the gas toward the exhaust portion side of the space in the direction toward the gas inlet portion side.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a heating device and a heating method. [Background technology]

[0002] Patent Document 1 discloses a heating unit having a hot plate on which a substrate is placed and which heat-treats the substrate. This heating unit includes a processing vessel equipped with a hot plate, and the processing vessel is equipped with an exhaust device for evacuating the processing vessel. An exhaust port connected to the exhaust device is formed near the rear side of the hot plate, and an outlet port connected to a gas supply source is formed near the front side of the hot plate. A top plate is disposed above the hot plate. In this heating unit, a purge gas is supplied through the outlet port, and the purge gas is sucked through the exhaust port to form a gas flow, which is rectified by the top plate. This rectified gas flow prevents particles from adhering to the substrate during heat treatment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-45190 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure improves the in-plane uniformity of a heat treatment that heats a substrate and dries a coating film formed on the substrate. [Means for solving the problem]

[0005] One aspect of the present disclosure is a heating device for heat-treating a substrate, comprising: a hot plate on which a substrate is placed and which heats the placed substrate; a gas inlet section which introduces gas into a space above the hot plate; and an exhaust section which exhausts gas from the space, wherein the gas inlet section and the exhaust section are arranged opposite each other in a plan view, sandwiching the substrate placed on the hot plate; and the heating device further comprises a gas supply section which supplies gas to the exhaust section side of the space in a direction toward the gas inlet section side. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to improve the in-plane uniformity of a heat treatment in which a substrate is heated and a coating film formed on the substrate is dried. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing an outline of the configuration of a heating device according to a first embodiment. [Figure 2] 1 is a longitudinal sectional view showing an outline of the configuration of a heating device according to a first embodiment. [Figure 3] FIG. 3 is a partially enlarged view of FIG. 2. [Figure 4] FIG. 4 is a diagram for explaining the effect of the heat treatment according to the first embodiment. [Figure 5] Another example of the heating process of the wafer W by the heating apparatus according to the first embodiment will be described. [Figure 6] Another example of the heating process of the wafer W by the heating apparatus according to the first embodiment will be described. [Figure 7] FIG. 10 is a cross-sectional view showing the outline of the configuration of a heating device according to a second embodiment. [Figure 8] FIG. 10 is a diagram for explaining the effect of the heat treatment according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] 2. Description of the Related Art In a manufacturing process for semiconductor devices and the like, a coating film such as a resist film is formed on a substrate such as a semiconductor wafer (hereinafter referred to as a "wafer"). When a coating film is formed on a substrate, the substrate is subjected to a heat treatment in order to adjust the degree of dryness of the coating film. This heat treatment is usually performed using a heating device having a hot plate on which the substrate is placed and which heats the substrate.

[0009] The interior of a heating device is evacuated for purposes such as recovering the solvent vaporized from the coating film due to heating. One method of evacuating a heating device involves providing a gas outlet above the peripheral edge of the hot plate and an exhaust port above the center of the hot plate, creating an airflow from the peripheral edge to the center of the hot plate. Another method involves providing an exhaust port on the rear side of the hot plate and a gas outlet on the front side of the hot plate, creating a unidirectional airflow from the front to the rear. While the results vary depending on the type of film, the latter method can dry the coating film more uniformly across the substrate than the former method. However, the latter method may result in insufficient drying of the coating film downstream of the unidirectional flow, such as when the coating film is thick. Another method to address the insufficient drying downstream of the unidirectional flow is to extend the heating time of the substrate. However, with this method, the solidification of the coating film progresses in a portion different from the portion downstream of the unidirectional flow, and when subsequent development or the like is performed, the coating film may unintentionally remain, i.e., residue may be generated.

[0010] Therefore, the technology according to the present disclosure improves the in-plane uniformity of the heat treatment that heats the substrate and dries the coating film formed on the substrate.

[0011] Hereinafter, a heating device and a heating method according to the present embodiment will be described with reference to the drawings. In this specification, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0012] (First embodiment) <Heating device> 1 and 2 are a cross-sectional view and a longitudinal-sectional view, respectively, showing the outline of the configuration of a heating device according to a first embodiment, and FIG.

[0013] 1 and 2, the heating apparatus 1 has a housing 10 whose interior can be sealed. The housing 10 has, for example, a rectangular parallelepiped shape, and an upper region 12 and a lower region 13 are separated by a partition wall 11. A loading / unloading opening 10a for a wafer W as a substrate is formed in one side wall of the housing 10 on the upper region 12 side, and an opening / closing shutter 10b is provided for the loading / unloading opening 10a.

[0014] The housing 10 has a temperature control area 14, which cools and controls the temperature of the wafer W, on the loading / unloading port 10a side, i.e., the front side (negative side in the Y direction in the figure), and a heating area 15, which heats the wafer W, on the rear side (positive side in the Y direction in the figure), and the temperature control area 14 and the heating area 15 are separated by a partition wall 16. The partition wall 16 has an opening 16a through which a cooling plate 20 (described later) on which the wafer W is placed passes. The length (width) of the opening 16a in the longitudinal direction (X direction in the figure) is at least greater than the diameter of the wafer W. A shutter 16b is provided for adjusting the opening degree of the opening 16a. In this embodiment, the opening 16a functions as a gas inlet that allows gas to flow into a space above a heating plate 30 (described later).

[0015] A cooling plate 20 for placing a wafer W thereon and for cooling and regulating the temperature of the placed wafer W is provided in the temperature control region 14, and a heating plate 30 for placing a wafer W thereon and for heating the placed wafer W is provided in the heating region 15. The cooling plate 20, the heating plate 30, and the opening 16a are arranged side by side, for example, along the Y direction in FIGS.

[0016] The hot plate 30 has a thick, generally disk-like shape. The hot plate 30 has a horizontal upper surface, and the upper surface is provided with a suction port (not shown) for sucking the wafer W, for example, so that the wafer W can be sucked and held on the hot plate 30 by suction from the suction port. The hot plate 30 is also provided so that the horizontal upper surface is exposed to the upper region 12.

[0017] 2, a heating mechanism 31 is provided inside the hot plate 30 to heat the hot plate 30. For example, a resistance heater or the like is used as the heating mechanism 31, and the control unit 100 (described later) controls the amount of power supplied to the heating mechanism 31, thereby controlling the hot plate 30 to a predetermined set temperature.

[0018] The hot plate 30 has a plurality of through holes 32 formed therein that penetrate the plate in the vertical direction. The through holes 32 are provided with lift pins 33. The lift pins 33 are configured to be movable up and down by a lift drive mechanism 34 having a drive source such as a motor. The lift pins 33 pass through the through holes 32 and protrude from the upper surface of the hot plate 30, and can be raised and lowered while supporting the wafer W. The lift pins 33 and the lift drive mechanism 34 form a lift mechanism that raises and lowers the substrate.

[0019] The hot plate 30 is supported in the housing 10 by a support member (not shown) via a support ring 35 that is annular in plan view and supports the outer periphery of the hot plate 30 .

[0020] As shown in Fig. 1, the cooling plate 20 is provided in the upper region 12 and has a substantially rectangular flat plate shape, with the end surface facing the hot plate 30 curved in an arc. Two notches 21 are formed in the cooling plate 20 along the Y direction, which prevent the cooling plate 20 from interfering with the lifting pins 33 and the lifting pins 22 (Fig. 2) provided below the cooling plate 20. The lifting pins 22 are configured to be able to move up and down by a lifting drive mechanism 23 having a drive source such as a motor. The cooling plate 20 also has a built-in temperature adjustment member (not shown), such as a Peltier element.

[0021] As shown in Fig. 2, the cooling plate 20 is supported by a support arm 24. A drive unit 25 having a motor or the like is attached to the support arm 24. The drive unit 25 is attached to a rail 26 extending in the Y direction in the lower region 13. The rail 26 extends from below the cooling plate 20 to near the bottom of the opening 16a. The drive unit 25 allows the cooling plate 20 to move along the rail 26 to above the hot plate 30. In order to avoid interference with the support arm 24, the partition wall 11 is provided with a slit 11a that extends along the movement direction of the cooling plate 20 (the Y direction in the figure) and through which the support arm 24 is inserted.

[0022] A top plate 40 is provided in the heating region 15 in the upper region 12. The top plate 40 is provided above the hot plate 30 so as to face the hot plate 30. A heating mechanism (not shown), such as a resistance heater, is provided on the top plate 40. The top plate 40 is controlled by the heating mechanism to a temperature higher than room temperature and lower than that of the hot plate 30 under the control of the control unit 100, which will be described later. At least a portion of the bottom surface of the top plate 40 that overlaps with the wafer W on the hot plate 30 in a plan view is flat and free of depressions.

[0023] Furthermore, the heating region 15 in the upper region 12 is provided with an exhaust port 50 as an exhaust section. The exhaust port 50 is for exhausting the space S above the hot plate 30, and is connected to, for example, one end of an exhaust duct 51, the other end of which is connected to an exhaust device 53 such as an exhaust pump via an exhaust pipe 52.

[0024] In addition, the exhaust port 50 is provided opposite the opening 16a in a plan view, sandwiching the wafer W placed on the hot plate 30. In other words, the opening 16a is provided on the front side of the hot plate 30 (negative side in the Y direction in the figure), while the exhaust port 50 is provided on the rear side of the hot plate 30 (positive side in the Y direction in the figure). When exhaust is performed through the exhaust port 50, as shown by the white arrow in Figure 3, the atmosphere in the temperature control region 14 is taken into the heating region 15 through the opening 16a, and an airflow (unidirectional flow) is formed between the hot plate 30 and the top plate 40 along the wafer W on the hot plate 30 toward the exhaust port 50.

[0025] 1, the exhaust port 50 has a width in a direction (X direction in the figure) perpendicular to the airflow direction from the opening 16a toward the exhaust port 50 in a plan view (Y direction in the figure). Specifically, a plurality of exhaust ports 50 are provided at equal intervals along the perpendicular direction. The width of the formation area of ​​the exhaust port 50 in the perpendicular direction is approximately the same as the diameter of the wafer W.

[0026] 2, the exhaust port 50 is located above the hot plate 30 (specifically, above the wafer W on the hot plate 30), and is located on the top plate 40 side, not the hot plate 30 side. If the film formed on the wafer W to be heated generates sublimates when heated, the sublimates tend to adhere to the top plate 40 because the top plate 40 is at a lower temperature than the hot plate 30. However, by providing the exhaust port 50 on the top plate 40 side as described above, it is possible to further prevent the sublimates from adhering to the top plate 40.

[0027] Furthermore, a gas supply pipe 60 serving as a gas supply unit is provided in the heating region 15 in the upper region 12. The gas supply pipe 60 is for supplying a purge gas (e.g., compressed air or an inert gas such as nitrogen gas) to the space S above the hot plate 30, and is connected to a purge gas supply source 62 via a pipe 61, for example.

[0028] 3, the gas supply pipe 60 is provided on the rear side of the hot plate 30 (positive side in the Y direction in the figure), similar to the exhaust port 50. As shown by the gray arrow in Fig. 3, the gas supply pipe 60 supplies purge gas in a direction toward the opening 16a (negative direction in the Y direction in the figure) to the exhaust port 50 side of the space S above the hot plate 30, which is downstream in the airflow direction (Y direction in the figure) from the opening 16a toward the exhaust port 50. Specifically, the supply destination of the purge gas from the gas supply pipe 60 is the exhaust port 50 side of the space S above the wafer W on the hot plate 30.

[0029] More specifically, the gas supply pipe 60 supplies the purge gas in a direction toward the opening 16a and obliquely upward to the exhaust port 50 side of the space S. The "obliquely upward direction" means a direction in which the discharge axis of the discharge port 63 of the gas supply pipe 60 does not strike the coating film on the wafer W placed on the hot plate 30, and does not strike the hot plate 30 or the wafer W. The gas supply pipe 60 is located below the exhaust port 50 .

[0030] 1, the purge gas discharge port 63 of the gas supply pipe 60 has a width in a direction (X direction in the figure) perpendicular to the airflow direction from the opening 16a toward the exhaust port 50 (Y direction in the figure) in a plan view. Specifically, the discharge port 63 is formed within a range of the width of the wafer W in a direction perpendicular to the airflow direction in a plan view. More specifically, a plurality of discharge ports 63 are provided at equal intervals along the perpendicular direction, and the width of the region in which the plurality of discharge ports 63 are formed in the perpendicular direction is approximately the same as the diameter of the wafer W.

[0031] The heating device 1 described above is provided with a control unit 100 as shown in FIGS. 1 and 2. The control unit 100 is a computer equipped with a processor such as a CPU, a memory, and the like, and has a program storage unit (not shown). The program storage unit stores a program that controls the operation of the drive systems of the above-mentioned components and controls the heating process described below. The program may be recorded on a non-transitory computer-readable storage medium M and installed from the storage medium M into the control unit 100. The storage medium M may be either temporary or non-transitory. Part or all of the program may be realized by dedicated hardware (circuit board).

[0032] <Heat treatment example 1> Next, an example of a heating process of a wafer W by the heating apparatus 1 will be described. The following process is performed under the control of the control unit 100. It is also assumed that a thick film of a negative resist liquid coating is formed on the wafer W to be heated. In this specification, the term "thick film" refers to a film having a thickness of 5000 nm or more and 20000 nm or less.

[0033] First, the loading / unloading port 10a is opened by the opening / closing shutter 10b, and the wafer W held by a wafer transfer device (not shown) outside the heating device 1 is loaded into the temperature adjustment region 14 in the upper region 12 through the loading / unloading port 10a. Then, the lifting pins 22 are raised, and the wafer W is transferred to the lifting pins 22.

[0034] Next, the wafer transfer device (not shown) is removed from the temperature control area 14, the lift pins 22 are lowered, and the wafer W is transferred to the cooling plate 20. Also, the opening / closing shutter 10b closes the loading / unloading port 10a.

[0035] Next, the cooling plate 20 on which the wafer W is placed is moved above the heating plate 30 through the opening 16a. The heating plate 30 has been heated to a predetermined temperature in advance. The predetermined temperature is, for example, lower than the boiling point of the solvent of the resist solution that constitutes the coating film on the wafer W. More specifically, when the solvent is N-methylpyrrolidone (boiling point 204°C), the predetermined temperature is 100°C to 120°C.

[0036] Thereafter, the lift pins 33 are raised to the transfer position, the wafer W is transferred onto the lift pins 33, and then the cooling plate 20 is retracted from above the heating plate 30.

[0037] Next, the opening 16a is opened to a predetermined degree by the shutter 16b, and exhaust of the space S above the heat plate 30 via the exhaust port 50 begins. Furthermore, supply of purge gas from the gas supply pipe 60 begins.

[0038] Thereafter, the lifting pins 33 are lowered, the wafer W is placed on the heating plate 30, and heating of the wafer W is initiated. While the wafer W is being heated by the heating plate 30, exhaustion through the exhaust port 50 continues, an airflow continues to be formed from the opening 16a toward the exhaust port 50, and the supply of purge gas from the gas supply pipe 60 continues, so that the purge gas continues to be supplied to the exhaust port 50 side of the space S above the heating plate 30 in a direction toward the opening 16a (the negative Y direction in FIG. 3 ).

[0039] If an airflow is formed from the opening 16a toward the exhaust port 50 while the wafer W is being heated by the hot plate 30, the solvent vaporized from the coating film on the heated wafer W flows along the airflow from the point of vaporization. As a result, the concentration of vaporized solvent is higher in the downstream portion of the wafer W in the airflow direction (the positive side of the Y direction in FIG. 3, etc.) than in other portions. This tendency is particularly pronounced when the coating film is thick, since the amount of vaporized solvent is large. Furthermore, in the portion with a high concentration of vaporized solvent, the solvent is less likely to evaporate from the coating film. Therefore, it is thought that the coating film may not be sufficiently dried in the downstream portion of the airflow direction on the wafer W.

[0040] In contrast, in this heating process, as described above, the purge gas from the gas supply pipe 60 is supplied in a direction toward the opening 16a toward the exhaust port 50 side of the space S above the hot plate 30, which is downstream of the airflow direction (Y direction in FIG. 3, etc.). Therefore, it is possible to prevent the vaporized solvent from becoming high on the exhaust port 50 side of the space S above the hot plate 30, which is downstream of the airflow direction (Y direction in FIG. 3, etc.). Therefore, it is possible to make the degree of drying of the coating film on the wafer W uniform.

[0041] While the wafer W is being heated by the hot plate 30, the flow rate of the purge gas supplied from the gas supply pipe 60 is a flow rate that satisfies the following condition: That is, the flow rate is such that the flow rate of the purge gas supplied from the gas supply pipe 60 is slower than the airflow from the opening 16 a formed by exhaust through the exhaust port 50 toward the exhaust port 50. In other words, the flow rate is such that a unidirectional flow from the opening 16 a formed by exhaust through the exhaust port 50 toward the exhaust port 50 is maintained. By setting the flow rate at such a level, it is possible to prevent the vaporized solvent from leaking outside the housing 10 without being able to be exhausted.

[0042] After a predetermined time has elapsed since the start of heating the wafer W by the hot plate 30, when heating of the wafer W, i.e., drying of the coating film on the wafer W, is completed, the lift pins 33 are raised to the transfer position, whereby the wafer W is supported by the lift pins 33 and separated from the hot plate 30, thereby completing heating of the wafer W by the hot plate 30. In addition, exhaust through the exhaust port 50 and supply of purge gas from the gas supply pipe 60 are stopped.

[0043] Next, opening 16a is opened by shutter 16b, and cooling plate 20 is inserted between heating plate 30 and wafer W supported by lifting pins 33. Next, lifting pins 33 are lowered, and wafer W is transferred to cooling plate 20. Subsequently, cooling plate 20 on which wafer W is placed is moved to temperature adjustment region 14. Then, wafer W is cooled by cooling plate 20 for a predetermined time, and its temperature is adjusted.

[0044] Thereafter, the lift pins 22 are raised, whereby the wafer W is supported by the lift pins 22 and separated from the cooling plate 20. Next, the loading / unloading opening 10a is opened by the opening / closing shutter 10b, and a wafer transfer device (not shown) is inserted through the loading / unloading opening 10a between the cooling plate 20 and the wafer W supported by the lift pins 22. Next, the lift pins 22 are lowered, and the wafer W is supported by the wafer transfer device. Then, the wafer W is carried out by the wafer transfer device, and the heating process of the wafer W by the heating device 1 is completed. Note that the wafer W that has been heated by the heating device 1 is then subjected to, for example, an exposure process and a development process to form a pattern, and then is heated at a temperature higher than the boiling point of the solvent in the coating film.

[0045] <Major Effects of This Embodiment> As described above, in this embodiment, the heating apparatus 1 includes the gas supply pipe 60, and purge gas is supplied toward the exhaust port 50 of the space S above the hot plate 30, downstream of the airflow formed by the opening 16a and the exhaust port 50, in a direction toward the opening 16a. This supply of purge gas prevents the concentration of vaporized solvent from increasing on the exhaust side of the space S above the hot plate 30, which corresponds to the downstream side. Therefore, the solvent evaporates from the coating film on the wafer W on the downstream side of the wafer W, just like in other areas, ensuring uniform drying of the coating film on the wafer W across the wafer. Furthermore, this embodiment eliminates the need for measures such as extending the heating time of the entire coating film on the wafer W to accommodate areas of the coating film on the wafer W where drying is slow. This prevents residue from remaining on the wafer W, which would occur if such measures were taken.

[0046] Furthermore, in this embodiment, the gas supply pipe 60 supplies the purge gas obliquely upward toward the exhaust port 50 side of the space S. Therefore, the purge gas does not directly hit the coating film on the wafer W placed on the heating plate 30, and therefore deformation of the coating film due to the purge gas can be prevented.

[0047] Furthermore, in this embodiment, the discharge port 63 is formed within the width of the wafer W in a direction perpendicular to the airflow direction in a plan view. If the width of the discharge port 63 is narrow, the area in which the vaporized solvent is dispersed by the purge gas from the discharge port 63 may be limited on the exhaust port 50 side of the space S above the hot plate 30, i.e., above the wafer W. Such a limited area may result in poor uniformity of the heat treatment results, such as film quality and film thickness. In contrast, in this embodiment, the discharge port 63 is formed within the width of the wafer W as described above. Therefore, the purge gas from the discharge port 63 disperses the vaporized solvent over almost the entire area above the hot plate 30, i.e., on the exhaust port 50 side of the space S above the wafer W. Therefore, this embodiment can prevent the purge gas from the discharge port 63 from deteriorating the uniformity of the heat treatment results, such as film quality and film thickness. In other words, this embodiment efficiently disperses the vaporized solvent across the width of the wafer W while minimizing the effect of the purge gas from the discharge port 63 on the airflow from the opening 16a toward the exhaust port 50.

[0048] 4 shows the in-plane distribution of the resist film on the wafer W after the actual heat treatment. This figure shows the in-plane distribution in the case where purge gas was supplied to the exhaust port 50 side of the space S above the heating plate 30 (Case 1) as in the heat treatment described above, and in the case where purge gas was not supplied (Case 2). The processing conditions are the same for Case 1 and Case 2, except for whether or not purge gas was supplied.

[0049] As shown in the figure, in case 2 where no purge gas is supplied as in this embodiment, a thin film thickness portion was present on the exhaust port 50 side (region R2 in the figure), which is downstream in the direction of the airflow formed by the opening 16a and the exhaust port 50. On the other hand, in case 1 in which purge gas was supplied as in this embodiment, the area with thin film thickness was reduced compared to case 2 on the exhaust port 50 side (region R1 in the figure), which is downstream in the direction of the airflow formed by opening 16a and exhaust port 50. These results show that during heating processing, supplying purge gas to the exhaust port 50 side of the space S above the heating plate 30 can reduce film thickness differences, i.e., improve the in-plane uniformity of the heating processing on the wafer W.

[0050] <Heat treatment example 2> Next, a description will be given of another example of the heating process of the wafer W by the heating apparatus 1. Note that the description of the same parts as in the above-described example 1 will be omitted.

[0051] In this example, the wafer W is also moved by the cooling plate 20 to above the heating plate 30 through the opening 16a. Thereafter, the lift pins 33 are raised to the transfer position, the wafer W is transferred onto the lift pins 33, and then the cooling plate 20 is retracted from above the heating plate 30.

[0052] Next, the opening 16a is opened to a predetermined degree by the shutter 16b, and exhaust of the space S above the heat plate 30 via the exhaust port 50 begins. Furthermore, supply of purge gas from the gas supply pipe 60 begins.

[0053] 5, the wafer W is moved to an intermediate position P2, which is a position different from the transfer position P1 (specifically, a lower position) and where the distance from the top plate 40 to the wafer W is a predetermined distance, and is kept in that state (first state) for a predetermined time (e.g., 30 to 300 seconds), during which the wafer W is heated by the heat from the heating plate 30, thereby drying the coating film on the wafer W. The predetermined distance, i.e., the intermediate position P2, is determined in advance depending on the type of material of the coating film on the wafer W, and the predetermined time is determined in advance depending on the type of material and thickness of the coating film on the wafer W, and these pieces of information are stored in advance in a storage unit (not shown).

[0054] The intermediate position P2 on the wafer W, i.e., the position of the wafer W in the first state, is farther from the hot plate 30 than the position of the wafer W in the second state described below. For example, when the distance from the top plate 40 to the hot plate 30 is 30 mm, the intermediate position P2 is a position where the distance from the backside of the wafer W to the hot plate 30 is 2 to 20 mm. The intermediate position P2 may be a position where the distance from the top plate 40 to the front surface, i.e., the top surface, of the wafer W is shorter than the distance from the top surface of the hot plate 30 to the bottom surface of the wafer W. Furthermore, the intermediate position P2 may be a position where the discharge axis AX of the discharge port 63 of the gas supply pipe 60 intersects with the backside of the wafer W to avoid local adverse effects on the coating film caused by the gas discharged from the gas supply pipe 60. Examples of local adverse effects on the coating film caused by the gas include deformation due to the force of the discharged gas and worsening film thickness unevenness due to contact with a space with an extremely low concentration of volatile solvent.

[0055] Next, the lifting pins 33 are lowered to create a state (second state) in which the gap between the top plate 40 and the wafer W is larger than in the first state described above, specifically, the wafer W is placed on the heating plate 30. In this state, the wafer W is heated to a predetermined processing temperature, and the drying of the thick coating film on the wafer W is further promoted.

[0056] In the process performed before heating in this second state, i.e., the first state described above, if the distance between the top plate 40 and the wafer W is smaller than in the second state, the pressure loss in the space between the top plate 40 and the wafer W is greater. Furthermore, in this case, the distance from the surface of the hot plate 30 to the underside of the wafer W is greater in the first state than in the second state, meaning that the pressure loss in the space between the hot plate 30 and the wafer W is also smaller. Therefore, the strength of the airflow above and along the surface of the wafer W can be changed between the first and second states without changing the amount of exhaust through the exhaust port 50. Specifically, in the heating process in the first state, the airflow along the wafer surface is relatively weaker than in the heating process in the second state, and the coating film on the wafer W is dried.

[0057] The heating process in the first state is carried out until the fluidity of the coating film is reduced to such an extent that it is not affected by the relatively strong air current that flows along the surface of the wafer W when heated in the second state, after which the lifting pins 33 are lowered and the wafer W transitions to the second state as described above. Also, in the step of heating in the first state, the intermediate position P2 is set to a position where the distance from the top plate 40 to the surface, i.e., the upper surface, of the wafer W is shorter than the distance from the surface of the hot plate 30 to the underside of the wafer W. This setting significantly weakens the airflow along the surface of the wafer W in the step of heating in the first state due to the relative relationship of the pressure losses in the two spaces on the underside and the upper side of the wafer W, and can be used, for example, when it is necessary to significantly improve the film thickness unevenness described later.

[0058] During the drying of the coating film in the first state and the drying of the coating film in the second state, exhaust through the exhaust port 50 continues, an airflow continues to be formed from the opening 16a toward the exhaust port 50, and the supply of purge gas from the gas supply pipe 60 continues.

[0059] After a predetermined time has elapsed since the start of heating the wafer W in the second state and the coating film on the wafer W has completely dried, the wafer W is moved to the temperature adjustment region 14 and then cooled and temperature-adjusted by the cooling plate 20 for a predetermined time, as in the above-described Example 1. Then, the wafer W is carried out by the wafer transfer device, and the heating process of the wafer W by the heating device 1 is completed.

[0060] In this example, during drying of the coating film in the second state where the solvent is largely evaporated, an airflow is formed from the opening 16a toward the exhaust port 50. During the drying, purge gas is supplied from the gas supply pipe 60 toward the opening 16a toward the exhaust port 50 side of the space S above the hot plate 30, which is downstream of the airflow direction. Therefore, in this example, during the drying, the concentration of evaporated solvent can be prevented from increasing on the exhaust port 50 side of the space S above the hot plate 30, which is downstream of the airflow direction (Y direction in FIG. 3, etc.).

[0061] Furthermore, in the case of the heat treatment example 1 described above, the inventors' extensive investigations revealed that, depending on the type of coating film material, unevenness in film thickness parallel to the airflow direction toward the exhaust port 50 may occur, i.e., thin or thick portions of the film thickness may occur parallel to the airflow direction. In contrast, in the heat treatment of this example, in the initial stage when the fluidity of the coating film is high, the drying of the coating film is promoted with a weak airflow flowing along the surface of the wafer W. After the coating film has hardened to a degree that is not affected by the airflow, the airflow is strengthened to remove the vaporized solvent and further harden the coating film. Therefore, according to this example, it is possible to suppress unevenness in film thickness parallel to the airflow direction toward the exhaust port 50.

[0062] Another possible method for weakening the airflow flowing along the surface of the wafer W is to reduce the amount of exhaust from the space S. However, this method carries the risk of vaporized solvent from the coating film leaking out of the space S, i.e., out of the heating apparatus 1. In contrast, in this example, the airflow flowing along the surface of the wafer W is weakened without reducing the amount of exhaust from the space S. Therefore, this example can suppress the occurrence of film thickness unevenness parallel to the direction of the airflow toward the exhaust port 50 while suppressing the risk of vaporized solvent leaking out.

[0063] Another possible method for weakening the airflow flowing along the surface of the wafer W is to reduce the flow rate of the gas introduced into the space S. However, this method may not be able to properly remove the vaporized solvent from the coating film from above the wafer W, which may reduce the drying rate of the coating film and worsen throughput. In contrast, in this example, the airflow flowing along the surface of the wafer W is weakened without reducing the flow rate of the gas introduced into the space S. Therefore, this example can suppress the occurrence of film thickness unevenness parallel to the direction of the airflow toward the exhaust port 50 while suppressing a decrease in the drying rate of the coating film.

[0064] <Heat treatment example 2> Next, a description will be given of another example of the heating process of the wafer W by the heating apparatus 1. Note that the description of the same parts as in the above-mentioned examples 1 and 2 will be omitted.

[0065] In this example, the wafer W is also moved by the cooling plate 20 to above the heating plate 30 through the opening 16a. Thereafter, the lift pins 33 are raised to the transfer position, the wafer W is transferred onto the lift pins 33, and then the cooling plate 20 is retracted from above the heating plate 30.

[0066] Next, the opening 16a is opened to a predetermined degree by the shutter 16b, and exhaust of the space S above the heat plate 30 via the exhaust port 50 begins. Furthermore, supply of purge gas from the gas supply pipe 60 begins.

[0067] Thereafter, as shown in FIG. 6, the wafer W is moved to a heating position P3, which is a position different from the transfer position P1 (specifically, a lower position) and where the distance from the heating plate 30 to the wafer W is closer than the first state, i.e., the intermediate position P2 shown by the dotted line, and in this state, the wafer W is heated by the heat from the heating plate 30, and the temperature of the wafer W is set to a temperature close to the target temperature when heated in the first state.

[0068] Thereafter, as in the above-described Example 2, the coating film on the wafer W is dried in the first state, and then the drying is carried out in the second state.

[0069] During the heating of the wafer W at the temperature rising position P3, the drying of the coating film in the first state, and the drying of the coating film in the second state, exhaustion through the exhaust port 50 continues, an airflow continues to be formed from the opening 16a toward the exhaust port 50, and the supply of purge gas from the gas supply pipe 60 continues.

[0070] When the drying of the coating film on the wafer W in the second state is completed, the wafer W is moved to the temperature adjustment region 14, and then cooled and temperature-adjusted for a predetermined time by the cooling plate 20, as in the above-described Examples 1 and 2. Then, the wafer W is carried out by the wafer transfer device, and the heating process of the wafer W by the heating device 1 is completed.

[0071] According to this example, it is possible to reduce the time required for the wafer W to reach the target temperature when heated in the first state.

[0072] (Second embodiment) <Heating device> FIG. 7 is a cross-sectional view showing the outline of the configuration of a heating device according to the second embodiment. A heating device 1a in FIG. 7 has gas supply pipes 110 and 111 as separate gas supply units in addition to the configuration of the heating device 1 shown in FIG. 1 and the like.

[0073] The gas supply pipes 110 and 111, like the gas supply pipe 60, are provided in the heating region 15 in the upper region 12. Similarly to the gas supply pipe 60, the gas supply pipes 110 and 111 are used to supply purge gas (e.g., compressed air or an inert gas such as nitrogen gas) to the space S (see FIG. 2) above the heating plate 30, and are connected to purge gas supply sources 114 and 115 via pipes 112 and 113, for example.

[0074] However, unlike the gas supply pipe 60, the gas supply pipes 110 and 111 are provided on the sides of the wafer W placed on the heating plate 30, in a direction (X direction in the figure) perpendicular to the airflow direction from the opening 16a toward the exhaust port 50 in a plan view. Also, as shown by the gray arrows in Figure 7, the gas supply pipes 110 and 111 supply purge gas to the space S (see Figure 2) above the heating plate 30 in the perpendicular direction (X direction in the figure).

[0075] Specifically, the gas supply pipe 110 is provided on one side (positive side in the X direction in the figure) of the wafer W placed on the hot plate 30 in the perpendicular direction, and supplies the purge gas to the space S above the hot plate 30 toward the other side (negative side in the X direction in the figure) of the direction perpendicular to the upper air. The gas supply pipe 111 is provided on the other side (negative side in the X direction in the figure) of the wafer W placed on the hot plate 30 in the perpendicular direction, and supplies the purge gas to the space S above the hot plate 30 toward one side (positive side in the X direction in the figure) of the direction perpendicular to the upper air.

[0076] The purge gas outlets 116, 117 of the gas supply pipes 110, 111 have a width in the airflow direction (Y direction in the figure) from the opening 16a toward the exhaust port 50. Specifically, a plurality of the outlets 116, 117 are provided at equal intervals along the airflow direction. The width of the formation area of ​​the outlets 116, 117 in the airflow direction is approximately the same as the diameter of the wafer W.

[0077] The provision of the gas supply pipes 110, 111 has the following effect. That is, if the gas supply pipes 110, 110 are not provided and purge gas is not supplied in the perpendicular direction from the side of the wafer W in the perpendicular direction, portions with locally thin film thickness may occur at both ends in the perpendicular direction (left-right direction in the figure) at the peripheral edge of the wafer W, as shown by the dotted lines on the left side of Figure 8. In other words, portions with locally insufficient drying may occur at the ends in the perpendicular direction (left-right direction in the figure).

[0078] The reason for this is thought to be as follows: That is, depending on conditions such as the flow rate of the purge gas from the gas supply pipe 60 and the balance between this flow rate and the exhaust flow rate, the flow rate of the airflow from the opening 16a toward the exhaust port 50 decreases above both ends of the wafer W in the perpendicular direction because the side walls of the housing 10 are close, and the solvent evaporated from the coating film on the wafer W placed on the hot plate 30 tends to stagnate. As a result, it is thought that the coating film on the wafer W may not be sufficiently dried at both ends of the wafer W in the perpendicular direction.

[0079] In contrast, in this embodiment, purge gas is additionally supplied to the space S above the heating plate 30 in a direction perpendicular to the upper air direction from gas supply pipes 110, 111 provided on the sides of the wafer W placed on the heating plate 30 in the perpendicular direction. This prevents vaporized solvent from accumulating above both ends of the wafer W on the heating plate 30 in the perpendicular direction. Therefore, as shown by the dotted lines on the right side of FIG. 8, it is possible to prevent localized thin film thicknesses from occurring at both ends of the peripheral edge of the wafer W in the perpendicular direction (the left-right direction in the figure). In other words, the drying degree of the coating film on the wafer W can be made more uniform.

[0080] The evaluation results shown in FIG. 8 are a simple evaluation of supplying purge gas in the perpendicular direction, and there is room for optimization of the conditions during the heat treatment with regard to the overall in-plane uniformity of the film thickness, including the central part of the wafer W.

[0081] The flow rate of the purge gas supplied from the plurality of outlets 116 and 117 can be adjusted within the allowable range for the in-plane uniformity of the film thickness after the heat treatment. The flow rates of the purge gas supplied from the multiple outlets 116 may be equal to or different from each other among the outlets 116. For example, the flow rate of the purge gas from each outlet 116 may be determined according to the distance to the hot plate 30, and the flow rate from the outlet closest to the hot plate 30, i.e., the outlet 116 corresponding to the part of the hot plate 30 closest to the side wall of the housing 10, may be set to be the largest. This allows the drying degree of the coating film on the wafer W to be more uniform. In this case, for example, an adjustment valve for adjusting the flow rate is provided for each outlet 116. The flow rate of the purge gas from outlet 117 is, for example, similar to the flow rate of the purge gas from the opposing outlet 116, but may be different.

[0082] Like the gas supply pipe 60, the gas supply pipes 110 and 111 are located below the exhaust port 50. The gas supply pipes 110 and 111 supply purge gas obliquely upward into the space S above the heating plate 30. This prevents the purge gas from the gas supply pipes 110 and 111 from directly hitting the coating film on the wafer W placed on the heating plate 30, thereby preventing the coating film from being deformed by the purge gas from the gas supply pipes 110 and 111.

[0083] (Variation) In the above examples, the coating film is formed from a negative resist liquid, but it may be formed from a positive resist liquid. Also, the coating film may be formed from a coating liquid other than a resist liquid.

[0084] In the above example, the gas inlet portion that allows gas to flow into the space S above the hot plate 30 is the opening 16a, but the gas inlet portion may also be configured as a gas outlet portion that discharges gas.

[0085] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0086] It should be noted that the configurations described above can be implemented and used in combination with each other in ways other than those specified in the appended claims. [Explanation of symbols]

[0087] 1 Heating device 1a Heating device 16a aperture 30 hot plate 50 exhaust port 60 Gas supply pipe S space W wafer

Claims

1. A heating apparatus for heat-treating a substrate, a hot plate on which a substrate is placed and which heats the placed substrate; a gas inlet portion for inflowing gas into a space above the hot plate; an exhaust section that exhausts air from the space, the gas inlet section and the exhaust section are provided to face each other across the substrate placed on the hot plate in a plan view, The heating device further includes a gas supply unit that supplies gas to the exhaust unit side of the space in a direction toward the gas inlet unit side.

2. The heating device according to claim 1 , wherein the gas supply unit supplies the gas in an obliquely upward direction.

3. The heating device according to claim 2 , wherein the gas supply unit supplies the gas from below the exhaust unit.

4. The heating device according to claim 1 , wherein the gas supply section has an outlet formed within a range of the width of the substrate in a direction perpendicular to the direction of airflow from the gas inlet section toward the exhaust section in a plan view.

5. 5. The heating device according to claim 1, wherein the flow rate of the gas supplied from the gas supply section is lower than the flow rate of the gas flowing from the gas inlet section toward the exhaust section.

6. The heating device according to any one of claims 1 to 4, further comprises another gas supplying part, which supplies gas from the side of the substrate placed on the hot plate to the space in the direction perpendicular to the airflow direction from the gas inlet part to the exhaust part in plan view.

7. a top plate facing the hot plate across the space; a lifting mechanism for lifting and lowering the substrate; a control unit, The heating device according to any one of claims 1 to 4, wherein the control unit maintains the substrate at a predetermined distance from the top plate in a first state to proceed with drying of the coating film on the substrate, and then heats the substrate to a predetermined processing temperature in a second state in which the distance between the top plate and the substrate is greater than in the first state to further proceed with drying of the coating film.

8. 8. The heating device according to claim 7, wherein the substrate is farther from the hot plate in the first state than in the second state.

9. The heating device according to claim 7 , wherein in the first state, a gas ejection axis of the gas supply unit intersects with the rear surface of the substrate.

10. A heating method for heat-treating a substrate using a heating device, comprising: The heating device is a hot plate on which a substrate is placed and which heats the placed substrate; a gas inlet portion for inflowing gas into a space above the hot plate; an exhaust section that exhausts air from the space, the gas inlet section and the exhaust section are provided to face each other across the substrate placed on the hot plate in a plan view, A heating method comprising the step of supplying gas from a gas supply section to an exhaust section side of the space in a direction toward the gas inlet section side.

11. The heating method according to claim 10 , wherein the gas supplying step supplies the gas from the gas supply unit in an obliquely upward direction.

12. The heating method according to claim 11 , wherein the step of supplying the gas comprises supplying the gas from the gas supply unit located below the exhaust unit.

13. 11. The heating method according to claim 10, wherein the gas supplying step supplies the gas from an outlet of the gas supply unit having a width in a direction perpendicular to an airflow direction from the gas inlet unit toward the exhaust unit in a plan view.

14. 14. The heating method according to claim 10, wherein in the step of supplying the gas, a flow rate of the gas supplied from the gas supply unit is lower than a flow rate of the gas flowing from the gas inlet unit to the exhaust unit.

15. The heating method according to any one of claims 10 to 13, wherein the step of supplying gas comprises the step of supplying gas from another gas supply part that is located at the side of the substrate that is placed on the hot plate to the space in the direction perpendicular to the airflow direction from the gas inlet part to the exhaust part in plan view.

16. The heating device further includes a top plate facing the hot plate across the space, (A) heating the substrate to a predetermined treatment temperature that is the highest temperature during the heat treatment period to proceed with drying of the coating film on the substrate; (B) adjusting the gap between the top plate and the substrate to make the airflow along the substrate surface weaker than in (A); (C) before the step (A), heating the substrate in a state where the airflow is weak to promote drying of the coating film on the substrate. The heating method according to any one of claims 10 to 13, further comprising:

17. 17. The heating method according to claim 16, wherein the substrate is further away from the hot plate when the airflow is weak than when the substrate is heated in the step (A).

18. The heating method according to claim 16 , wherein when the airflow is weak, the discharge axis of the gas supply unit intersects with the rear surface of the substrate.

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