Heating device and heating method

Abstract

This improves the in-plane uniformity of the heat treatment process, which involves heating a substrate and drying the coating film formed on the substrate. [Solution] A heating device for heat-treating a substrate, comprising: a heating plate on which the substrate is placed and which heats the placed substrate; a gas inlet for introducing a first gas into a space above the heating plate; and an exhaust outlet for exhausting gas from the space, wherein the gas inlet and the exhaust outlet are arranged to face each other in a plan view, sandwiching the substrate placed on the heating plate, and further comprising a gas supply outlet for supplying a second gas from the side of the substrate placed on the heating plate into the space in a direction perpendicular to the airflow direction from the gas inlet to the exhaust outlet in a plan view.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a heating unit having a hot plate on which a substrate is placed and for heat-treating the substrate. This heating unit includes a processing container provided with a hot plate, and the processing container is provided with an exhaust device for exhausting the inside of the processing container. An exhaust port connected to the exhaust device is formed near the back side of the hot plate, and a discharge 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, purge gas is supplied from the discharge port, this purge gas is sucked at the exhaust port to form a gas flow, and this gas flow is rectified by the top plate, and particles are prevented from adhering to the substrate being heat-treated by this rectified gas flow.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology according to the present disclosure improves the in-plane uniformity of a heat treatment for heating a substrate and drying a coating film formed on the substrate.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a heating apparatus for heat-treating a substrate, comprising: a heating plate on which a substrate is placed and which heats the placed substrate; a gas inlet for introducing a first gas into a space above the heating plate; and an exhaust outlet for exhausting gas from the space, wherein the gas inlet and the exhaust outlet are arranged to face each other in a plan view, sandwiching the substrate placed on the heating plate, and further comprising a gas supply outlet for supplying a second gas from the side of the substrate placed on the heating plate into the space in a direction perpendicular to the airflow direction from the gas inlet to the exhaust outlet in a plan view. [Effects of the Invention]

[0006] According to this 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 drawing]

[0007] [Figure 1] This is a cross-sectional view showing a schematic configuration of the heating device according to the first embodiment. [Figure 2] This is a longitudinal cross-sectional view showing a schematic configuration of the heating device according to the first embodiment. [Figure 3] This is a magnified view of a portion of Figure 2. [Figure 4] This is a diagram illustrating the effect of the heat treatment according to the first embodiment. [Figure 5] Another example of the heating treatment of a wafer W using the heating device according to the first embodiment will be described. [Figure 6] Another example of the heating treatment of a wafer W using the heating device according to the first embodiment will be described. [Figure 7] This is a cross-sectional view showing a schematic configuration of the heating device according to the second embodiment. [Figure 8] This figure illustrates the effect of the heat treatment according to the second embodiment. [Modes for carrying out the invention]

[0008] In the manufacturing process of semiconductor devices, a coating film such as a resist film is formed on a substrate such as a semiconductor wafer (hereinafter referred to as "wafer"). When a coating film is formed on a substrate, the substrate is subjected to a heat treatment to adjust the degree of drying of the coating film. This heat treatment is usually performed using a heating device that has a heating plate on which the substrate is placed and which heats the substrate.

[0009] In heating devices, the interior is evacuated for purposes such as recovering the solvent vaporized from the coated film due to heating. One exhaust method in heating devices is to provide a gas outlet above the periphery of the heating plate and an exhaust port above the center of the heating plate, creating an airflow that flows from the periphery to the center of the heating plate for exhaust. Another exhaust method is to provide an exhaust port on the back side of the heating plate and a gas outlet on the front side, creating a unidirectional airflow from the front to the back for exhaust. Although the results vary depending on the type of film, the latter method can dry the coated film more uniformly across the substrate surface compared to the former method. However, with the latter method, the drying of the coated film may be insufficient in the downstream portion of the substrate from the unidirectional flow. For example, this may occur when the coated film is thick. One way to resolve the insufficient drying in the downstream portion of the unidirectional flow is to increase the heating time of the substrate. However, with this method, the coating film solidifies in a part different from the downstream part of the unidirectional flow described above, and when development or other processes are performed afterward, the coating film may unintentionally remain, that is, residue may be generated.

[0010] Therefore, the technology disclosed herein improves the in-plane uniformity of a heat treatment in which a substrate is heated and a coating film formed on the substrate is dried.

[0011] The heating device and heating method according to this embodiment will be described below with reference to the drawings. In this specification, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations will be omitted.

[0012] (First Embodiment) <Heating device> Figures 1 and 2 are a schematic cross-sectional view and a longitudinal cross-sectional view showing the configuration of the heating device according to the first embodiment, respectively. Figure 3 is a partially enlarged view of Figure 2.

[0013] As shown in Figures 1 and 2, the heating device 1 has a housing 10 that can be sealed inside. 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. An inlet / outlet 10a for loading wafers W as substrates is formed on one side wall of the housing 10 on the upper region 12 side, and an opening / closing shutter 10b is provided for this inlet / outlet 10a.

[0014] Furthermore, the housing 10 has a temperature control region 14 for cooling and temperature-regulating the wafer W on the loading / unloading port 10a side, i.e., the front side (negative Y direction in the figure), and a heating region 15 for heating the wafer W on the back side (positive Y direction in the figure), and these temperature control region 14 and heating region 15 are separated by a partition wall 16. The partition wall 16 has an opening 16a through which the cooling plate 20 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 degree of opening of the opening 16a. In this embodiment, the opening 16a functions as a gas inlet for introducing gas into the space above the heating plate 30, which will be described later.

[0015] Within the temperature control region 14, a cooling plate 20 is provided on which the wafer W is placed and which cools and controls the temperature of the placed wafer W. Within the heating region 15, a heating plate 30 is provided on which the wafer W is placed and which heats the placed wafer W. The cooling plate 20, the heating plate 30, and the aforementioned opening 16a are arranged side by side along the Y direction in Figures 1 and 2, for example.

[0016] The hot plate 30 has a thick substantially disk shape. The hot plate 30 has a horizontal upper surface, and on this upper surface, there is provided a suction port (not shown) for sucking, for example, the wafer W. By suction from this suction port, the wafer W can be adsorbed and held on the hot plate 30. Further, the hot plate 30 is provided such that the above horizontal upper surface is exposed in the upper region 12.

[0017] Inside the hot plate 30, as shown in FIG. 2, a heating mechanism 31 for heating the hot plate 30 is provided. As the heating mechanism 31, for example, a resistance heating heater or the like is used, and by controlling the amount of power supplied to the heating mechanism 31 by a control unit 100 described later, the hot plate 30 can be controlled to a predetermined set temperature.

[0018] A plurality of through holes 32 penetrating in the vertical direction are formed in the hot plate 30. Lift pins 33 are provided in the through holes 32. The lift pins 33 are configured to be able to move up and down by a lift drive mechanism 34 having a drive source such as a motor. The lift pins 33 pass through the inside of the through holes 32 and project from the upper surface of the hot plate 30, and can move up and down while supporting the wafer W. The lift pins 33 and the lift drive mechanism 34 constitute a lift mechanism for lifting and lowering the substrate.

[0019] 2]The hot plate 30 is supported within the housing 10 by a support member (not shown) via an annular support ring 35 in a plan view that supports the outer peripheral portion of the hot plate 30.

[0020] The cooling plate 20 is provided in the upper region, as shown in FIG. 1, has a substantially square flat plate shape, and the end face on the hot plate 30 side is curved in an arc shape. Two cutouts 21 along the Y direction are formed in the cooling plate 20, and the cooling plate 20 can be prevented from interfering with the lift pins 33 and the lift pins 22 in FIG. 2 provided below the cooling plate 20. The lift pins 22 are configured to be able to move up and down by a lift drive mechanism 23 having a drive source such as a motor. Further, the cooling plate 20 incorporates a temperature adjustment member (not shown) such as a Peltier element.

[0021] As shown in Figure 2, the cooling plate 20 is supported by a support arm 24. A drive unit 25, which includes a motor, is attached to the support arm 24. The drive unit 25 is attached to a rail 26 that extends 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 heating plate 30. To avoid interference with the support arm 24, the partition wall 11 is provided with a slit 11a that extends along the direction of movement of the cooling plate 20 (Y direction in the figure) and through which the support arm 24 is inserted.

[0022] Furthermore, a top plate 40 is provided in the heating region 15 of the upper region 12. The top plate 40 is provided above the heating plate 30 and opposite to the heating plate 30. The top plate 40 is equipped with a heating mechanism (not shown), such as a resistance heating heater. The top plate 40 is controlled by the heating mechanism to a temperature higher than room temperature but lower than that of the heating plate 30, under the control of the control unit 100 described later. In addition, at least the portion of the underside of the top plate 40 that overlaps with the wafer W on the heating plate 30 in a plan view is a flat surface without any indentations or other defects.

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

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

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

[0026] Furthermore, as shown in Figure 2, the exhaust port 50 is located above the heating plate 30 (specifically, above the wafer W on the heating plate 30), and is provided on the top plate 40 side, not the heating plate 30 side. If the film formed on the wafer W to be heated generates sublimation material upon heating, the top plate 40 is at a lower temperature than the heating plate 30, so the sublimation material tends to adhere to the top plate 40. However, by providing the exhaust port 50 on the top plate 40 side as described above, the adhesion of sublimation material to the top plate 40 can be further suppressed.

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

[0028] Furthermore, the gas supply pipe 60, like the exhaust port 50, is located behind the hot plate 30 (positive Y direction in the figure). As shown by the gray arrow in Figure 3, the gas supply pipe 60 supplies purge gas in the direction toward the opening 16a (negative 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 toward the exhaust port 50 (Y direction in the figure) from the opening 16a. Specifically, the destination of the purge gas supplied by 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 purge gas to the exhaust port 50 side of the space S in a direction toward the opening 16a side and diagonally upward. "Diagonally upward" means that the discharge axis of the discharge port 63 of the gas supply pipe 60 does not come into contact with the coated film on the wafer W placed on the hot plate 30, nor does it come into contact with the hot plate 30 or the wafer W. Furthermore, the gas supply pipe 60 is located below the exhaust port 50.

[0030] Furthermore, the purge gas outlet 63 of the gas supply pipe 60 has a width in the direction perpendicular to the airflow direction (Y direction in the figure) and the direction perpendicular to the plan view (X direction in the figure), as shown in Figure 1, for example. Specifically, the outlet 63 is formed within the width range of the wafer W in the direction perpendicular to the airflow direction in the plan view. More specifically, multiple outlets 63 are provided at equal intervals along the perpendicular direction, and the width in the perpendicular direction of the region where multiple outlets 63 are formed is approximately the same as the diameter of the wafer W.

[0031] As shown in Figures 1 and 2, the heating device 1 is equipped with a control unit 100. The control unit 100 is a computer equipped with, for example, a processor such as a CPU and memory, and has a program storage unit (not shown). The program storage unit stores a program that controls the operation of the drive systems of each of the above-mentioned parts and controls the heating process described later. The above program may have been recorded on a non-temporary storage medium M that is readable by the computer and installed from the storage medium M to the control unit 100. The storage medium M may be temporary or non-temporary. Part or all of the program may be implemented on dedicated hardware (circuit board).

[0032] <Example of heat treatment 1> Next, an example of heating a wafer W using the heating device 1 will be described. The following process is performed under the control of the control unit 100. It is assumed that a thick film of negative-type resist solution is formed on the wafer W to be heated. In this specification, "thick film" refers to a film with 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 transport device (not shown) outside the heating device 1, is loaded into the temperature control area 14 in the upper area 12 through the loading / unloading port 10a. Subsequently, the lifting / lowering pin 22 is raised, and the wafer W is handed over to the lifting / lowering pin 22.

[0034] Next, the wafer transfer device (not shown) is withdrawn from the temperature control area 14, the lifting pin 22 is lowered, and the wafer W is transferred to the cooling plate 20. 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 preheated to a predetermined temperature. The predetermined temperature is, for example, below the boiling point of the solvent in the resist solution that constitutes the coating film on the wafer W. More specifically, for example, if the solvent is N-methylpyrrolidone (boiling point 204°C), the predetermined temperature is 100°C to 120°C.

[0036] Subsequently, the lifting pin 33 is raised to the transfer position, the wafer W is transferred to the lifting pin 33, and then the cooling plate 20 retracts from above the heating plate 30.

[0037] Next, the shutter 16b opens the opening 16a to a predetermined degree, exhaust of the space S above the hot plate 30 via the exhaust port 50 is started, and furthermore, the supply of purge gas from the gas supply pipe 60 is started.

[0038] Subsequently, the lifting pin 33 is lowered, the wafer W is placed on the heating plate 30, and heating of the wafer W begins. While the wafer W is being heated by the heating plate 30, exhaust is continued through the exhaust port 50, and an airflow is continuously formed from the opening 16a toward the exhaust port 50. At the same time, the supply of purge gas from the gas supply pipe 60 continues, and purge gas is continuously supplied to the space S above the heating plate 30 toward the exhaust port 50 in the direction toward the opening 16a (negative Y direction in Figure 3).

[0039] While the wafer W is being heated by the hot plate 30, if an airflow is formed from the opening 16a toward the exhaust port 50, the solvent vaporized from the coated film on the heated wafer W will flow along the airflow from the point of vaporization. Therefore, the concentration of vaporized solvent becomes higher in the downstream side of the airflow direction on the wafer W (the positive Y-direction side in Figure 3, etc.) compared to other parts. This tendency is particularly pronounced when the coated film is thick, as the amount of vaporized solvent is large. Furthermore, in areas with a high concentration of vaporized solvent, it becomes more difficult for the solvent to vaporize from the coated film. Therefore, it is thought that the drying of the coated film may be insufficient in the downstream side of the airflow direction on the wafer W.

[0040] In contrast, in this heat treatment, as described above, the purge gas from the gas supply pipe 60 is supplied toward the opening 16a side toward the exhaust port 50 side of the space S above the hot plate 30, which is downstream in the airflow direction (Y direction as shown in Figure 3). Therefore, it is possible to suppress the increase in vaporized solvent on the exhaust port 50 side of the space S above the hot plate 30, which is downstream in the airflow direction (Y direction as shown in Figure 3). Consequently, the degree of drying of the coated film on the wafer W can be made 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 such that it satisfies the following conditions: the flow velocity of the purge gas supplied from the gas supply pipe 60 is lower than the airflow from the opening 16a formed by exhaust through the exhaust port 50 toward the exhaust port 50. In other words, it is a flow rate that maintains a unidirectional flow from the opening 16a formed by exhaust through the exhaust port 50 toward the exhaust port 50. By setting the flow rate in this manner, it is possible to suppress the leakage of vaporized solvent outside the housing 10 without being able to exhaust it.

[0042] After a predetermined time has elapsed since the heating of the wafer W by the heating plate 30 began, and the heating of the wafer W, i.e., the drying of the coating film on the wafer W, is complete, the lifting pins 33 are raised to the transfer position, thereby supporting the wafer W by the lifting pins 33 and separating it from the heating plate 30, and the heating of the wafer W by the heating plate 30 ends. At the same time, exhaust through the exhaust port 50 and the supply of purge gas from the gas supply pipe 60 are stopped.

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

[0044] Subsequently, the lifting pins 22 are raised, thereby supporting the wafer W by the lifting pins 22 and separating it from the cooling plate 20. Next, the loading / unloading port 10a is opened by the opening / closing shutter 10b, and a wafer transport device (not shown) is inserted through the loading / unloading port 10a between the cooling plate 20 and the wafer W supported by the lifting pins 22. Then, the lifting pins 22 are lowered, and the wafer W is supported by the wafer transport device. Finally, the wafer W is unloaded by the wafer transport device, and the heating treatment of the wafer W by the heating device 1 is completed. The wafer W that has been heated by the heating device 1 is then subjected to, for example, exposure and development treatments to form a pattern, and then heated at a temperature higher than the boiling point of the solvent of the coating film.

[0045] <Main effects of this embodiment> As described above, in this embodiment, the heating device 1 is equipped with a gas supply pipe 60 and supplies purge gas in the direction toward the opening 16a to the exhaust port 50 side of the space S above the hot plate 30, which is downstream in the direction of the airflow formed by the opening 16a and the exhaust port 50. By supplying this purge gas, it is possible to suppress the concentration of vaporized solvent from becoming high on the exhaust side of the space S above the hot plate 30, which is downstream. Therefore, even on the downstream side of the wafer W, the solvent vaporizes from the coating film on the wafer W, just like in other parts, so the degree of drying of the coating film on the wafer W can be made uniform across the wafer surface. Furthermore, according to this embodiment, since the degree of drying of the coating film on the wafer W can be made uniform, measures such as extending the heating time of the entire coating film on the wafer W for parts of the coating film on the wafer W that dry slowly are unnecessary. Therefore, it is possible to suppress the residue remaining on the wafer W, which would occur if such measures were taken.

[0046] Furthermore, in this embodiment, the gas supply pipe 60 supplies purge gas diagonally upward towards the exhaust port 50 side of the space S. Therefore, since the purge gas does not directly come into contact with the coating film on the wafer W placed on the hot plate 30, 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 range 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 on the exhaust port 50 side of the space S above the hot plate 30, i.e., above the wafer W, may be limited. Such limitation can lead to a deterioration in the uniformity of the heat treatment results, such as film quality and film thickness. In contrast, in this embodiment, since the discharge port 63 is formed within the width range of the wafer W as described above, the vaporized solvent is dispersed by the purge gas from the discharge port 63 over almost the entire area on the exhaust port 50 side of the space S above the hot plate 30, i.e., above the wafer W. Therefore, according to this embodiment, it is possible to suppress the deterioration of the uniformity of the heat treatment results, such as film quality and film thickness, due to the purge gas from the discharge port 63. In other words, according to this embodiment, the vaporized solvent can be dispersed efficiently in the width direction of the wafer W while suppressing the influence of the purge gas from the discharge port 63 on the airflow from the opening 16a to the exhaust port 50.

[0048] Figure 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 hot plate 30 (Case 1) and in the case where no purge gas was supplied (Case 2), as in the heat treatment described above. The treatment conditions are the same for Case 1 and Case 2, except for the presence or absence of purge gas supply.

[0049] As shown in the figure, in case 2, where no purge gas is supplied as in this embodiment, a thin film 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, where purge gas was supplied as in this embodiment, the area with a thinner 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 the opening 16a and the exhaust port 50. These results show that by supplying purge gas to the exhaust port 50 side of the space S above the hot plate 30 during the heat treatment, the film thickness difference can be reduced, meaning that the in-plane uniformity of the heat treatment on the wafer W can be improved.

[0050] <Example of heat treatment 2> Next, another example of the heating treatment of wafer W using heating device 1 will be described. Note that the same parts as in Example 1 described above will be omitted from the explanation.

[0051] In this example as well, the wafer W is moved above the hot plate 30 through the opening 16a by the cooling plate 20. Subsequently, the lifting pin 33 is raised to the transfer position, the wafer W is transferred to the lifting pin 33, and then the cooling plate 20 retracts from above the heating plate 30.

[0052] Next, the shutter 16b opens the opening 16a to a predetermined degree, exhaust of the space S above the hot plate 30 via the exhaust port 50 is started, and furthermore, the supply of purge gas from the gas supply pipe 60 is started.

[0053] Subsequently, as shown in Figure 5, the wafer W is moved to an intermediate position P2, which is a different position from the transfer position P1 (specifically, a lower position), and the distance from the top plate 40 to the wafer W is a predetermined distance. It is held in this state (first state) for a predetermined time (for example, 30 seconds to 300 seconds), and heated by the heat from the heating plate 30, which promotes the drying of the coating film on the wafer W. The predetermined distance, i.e., the intermediate position P2, is predetermined according to the type of material of the coating film on the wafer W, and the predetermined time is predetermined according to the type of material and film thickness of the coating film on the wafer W. This information is 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 a position further from the heating plate 30 than the position of the wafer W in the second state described later. The intermediate position P2 is, for example, the position where the distance from the back surface of the wafer W to the heating plate 30 is 2 to 20 mm when the distance from the top plate 40 to the heating plate 30 is 30 mm. The intermediate position P2 may also be a position where the distance from the top plate 40 to the surface (i.e., top surface) of the wafer W is smaller than the distance from the surface of the heating 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 back surface of the wafer W in order to avoid local adverse effects on the coating film by the gas discharged from the gas supply pipe 60. Local adverse effects on the coating film by the gas include, for example, deformation due to the force of the discharged gas and deterioration of film thickness unevenness due to contact with a space with an extremely low concentration of volatile solvent.

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

[0056] In the first state described above, which is the state in the process performed before heating in the second state, 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 large. Also, in this case, the distance from the surface of the heating plate 30 to the bottom surface of the wafer W is larger in the first state than in the second state, meaning that the pressure loss in the space between the heating plate 30 and the wafer W is also smaller. Therefore, even without changing the exhaust volume through the exhaust port 50, the strength of the airflow above the wafer W along its surface can be changed between the first state and the second state. Specifically, in the heating process in the first state, the drying of the coating film on the wafer W proceeds with a relatively weaker airflow along the wafer surface compared to the heating process in the second state.

[0057] The heating process in the first state is carried out until the fluidity of the coated film decreases to the extent that it is not affected by the relatively strong airflow that flows along the surface of the wafer W during heating in the second state. After that, the lifting pin 33 is lowered, and the process transitions to the second state as described above. Furthermore, as previously mentioned, in the heating process 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 top surface, of the wafer W is smaller than the distance from the surface of the heating plate 30 to the bottom surface of the wafer W. This setting can be used, for example, when it is necessary to significantly improve the film thickness unevenness described later, because the airflow along the surface of the wafer W in the heating process in the first state is significantly weakened due to the relative relationship of the pressure loss in the two spaces on the bottom and top sides of the wafer W.

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

[0059] After a predetermined time has elapsed since the heating of the wafer W in the second state began and the drying of the coating film on the wafer W is complete, the wafer W is moved to the temperature control region 14, and then cooled on the cooling plate 20 for a predetermined time to control its temperature, similar to Example 1 described above. Then, the wafer W is unloaded by the wafer transport device, and the heating process of the wafer W by the heating device 1 is completed.

[0060] In this example, during the drying of the coated film in the second state where solvent vaporization is high, an airflow is formed from the opening 16a toward the exhaust port 50. During this drying, purge gas from the gas supply pipe 60 is supplied toward the opening 16a toward the exhaust port 50 side of the space S above the hot plate 30, which is downstream in the direction of the airflow. Therefore, in this example as well, during the drying, it is possible to suppress the increase in the vaporized solvent concentration on the exhaust port 50 side of the space S above the hot plate 30, which is downstream in the direction of the airflow (the Y direction in Figure 3, etc.).

[0061] Furthermore, in the case of the aforementioned example 1 of the heat treatment, the inventors have conducted thorough investigations and found that, depending on the type of coating material, uneven film thickness can occur parallel to the direction of airflow toward the exhaust port 50; that is, areas with thin or thick film thickness may occur parallel to the direction of airflow. 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 advanced with a weak airflow flowing along the surface of the wafer W. After the coating film has hardened to the extent that it is not affected by the airflow, the hardening of the coating film is further advanced by increasing the airflow to a strong state while removing the vaporized solvent. Therefore, according to this example, it is possible to suppress the occurrence of uneven film thickness parallel to the direction of airflow toward the exhaust port 50.

[0062] Another method to weaken the airflow along the surface of the wafer W is to reduce the exhaust volume from the space S. However, with this method, there is a risk that the vaporized solvent from the coated film may leak out of space S, i.e., outside the heating device 1. In contrast, in this example, the airflow along the surface of the wafer W is weakened without reducing the exhaust volume from space S. Therefore, according to this example, it is possible to suppress the risk of vaporized solvent leaking to the outside while suppressing the occurrence of film thickness unevenness parallel to the airflow direction toward the exhaust port 50.

[0063] Another method to weaken the airflow along the surface of the wafer W is to reduce the flow rate of gas taken into the space S. However, with this method, it may not be possible to properly remove the vaporized solvent from the coated film from above the wafer W, which could reduce the drying speed of the coated film and worsen the throughput. In contrast, in this example, the airflow along the surface of the wafer W is weakened without reducing the flow rate of gas taken into the space S. Therefore, according to this example, it is possible to suppress the reduction in the drying speed of the coated film while suppressing the occurrence of uneven film thickness parallel to the airflow direction toward the exhaust port 50.

[0064] <Example of heat treatment 2> Next, we will describe another example of the heating treatment of wafer W using heating device 1. Note that we will omit explanations of parts that are the same as those described in Examples 1 and 2 above.

[0065] In this example as well, the wafer W is moved above the hot plate 30 through the opening 16a by the cooling plate 20. Subsequently, the lifting pin 33 is raised to the transfer position, the wafer W is transferred to the lifting pin 33, and then the cooling plate 20 retracts from above the heating plate 30.

[0066] Next, the shutter 16b opens the opening 16a to a predetermined degree, exhaust of the space S above the hot plate 30 via the exhaust port 50 is started, and furthermore, the supply of purge gas from the gas supply pipe 60 is started.

[0067] Subsequently, as shown in Figure 6, the wafer W is moved to a heating position P3 that is 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 described above, i.e., the intermediate position P2 shown by the dashed line. In this state, the wafer W is heated by the heat from the heating plate 30, and the temperature of the wafer W is brought to a temperature close to the target temperature during heating in the first state.

[0068] Subsequently, similar to Example 2 described above, the coating film on the wafer W is dried in the first state, and then the same drying is performed in the second state.

[0069] During the heating of the wafer W at the heating position P3, the drying of the coating film in the first state, and the drying of the coating film in the second state, exhaust is continued through the exhaust port 50, an airflow from the opening 16a toward the exhaust port 50 is continuously formed, and the supply of purge gas from the gas supply pipe 60 is also continued.

[0070] Once the drying of the coating film on the wafer W in the second state is complete, the wafer W is moved to the temperature control area 14, and then cooled on the cooling plate 20 for a predetermined time to control its temperature, similar to the examples 1 and 2 described above. The wafer W is then removed by the wafer transport device, and the heating treatment of the wafer W by the heating device 1 is completed.

[0071] In this example, the time it takes for the wafer W to reach the target temperature during heating in the first state can be shortened.

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

[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. Also, like the gas supply pipe 60, the gas supply pipes 110 and 111 are for supplying purge gas (for example, an inert gas such as compressed air or nitrogen gas) to the space S above the hot plate 30 (see Figure 2), and are connected to the purge gas supply sources 114 and 115 via pipes 112 and 113, for example.

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

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

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

[0077] By providing gas supply pipes 110 and 111, the following effects are obtained. That is, if gas supply pipes 110 and 111 are not provided and purge gas is not supplied from the side of the wafer W in the direction of the orthogonal direction, locally thin film thickness areas may occur at both ends of the peripheral edge of the wafer W in the direction of the orthogonal direction (left and right direction in the figure), as shown by the dotted line on the left side of Figure 8. In other words, locally insufficient drying may occur at the ends in the direction of the orthogonal direction (left and right direction in the figure).

[0078] The following reasons are considered to be the cause. Specifically, depending on conditions such as the flow rate of the purge gas from the gas supply pipe 60 and the balance between that flow rate and the exhaust flow rate, the airflow velocity from the opening 16a towards the exhaust port 50 decreases above both ends of the wafer W in the above-mentioned orthogonal direction because the side walls of the housing 10 are close, and the solvent vaporized from the coating film on the wafer W placed on the hot plate 30 tends to accumulate relatively easily. As a result, it is thought that insufficient drying of the coating film on the wafer W may occur at both ends of the wafer W in the above-mentioned orthogonal direction.

[0079] In contrast, in this embodiment, purge gas is supplied to the space S above the hot plate 30 from gas supply pipes 110 and 111 located on the sides of the wafer W placed on the hot plate 30 in the direction perpendicular to the above direction, in the direction perpendicular to the above direction. Therefore, it is possible to suppress the accumulation of vaporized solvent above both ends of the wafer W on the hot plate 30 in the direction perpendicular to the above direction. Consequently, as shown by the dotted line on the right side of Figure 8, it is possible to suppress the occurrence of localized thin film thickness areas at both ends of the peripheral edge of the wafer W in the direction perpendicular to the above direction (left and right direction in the figure). In other words, the degree of drying of the coating film on the wafer W can be made more uniform.

[0080] The evaluation results shown in Figure 8 represent a simplified assessment of supplying purge gas in the orthogonal directions mentioned above. There is still room for optimization of the heat treatment conditions regarding 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 multiple outlets 116 and 117 can be adjusted within the allowable range of in-plane uniformity of the film thickness after heat treatment. The flow rates of the purge gas supplied from the multiple discharge ports 116 may be equal or different among the discharge ports 116. For example, the flow rate of the purge gas from each discharge port 116 may be determined according to the distance to the hot plate 30, and the flow rate from the discharge port closest to the hot plate 30, that is, the flow rate from the discharge port 116 corresponding to the part of the hot plate 30 closest to the side wall of the housing 10, may be the largest. This makes it possible to make the degree of drying of the coating film on the wafer W even more uniform. In this case, for example, a control valve for adjusting the flow rate is provided at each discharge port 116. The flow rate of the purge gas from the discharge port 117 is, for example, the same as the flow rate of the purge gas from the opposing discharge port 116, but may be different.

[0082] Furthermore, gas supply pipes 110 and 111 are located below the exhaust port 50, similar to gas supply pipe 60. In addition, gas supply pipes 110 and 111 supply purge gas to the space S above the hot plate 30 in an upward direction at an angle. As a result, the purge gas from gas supply pipes 110 and 111 does not directly come into contact with the coating film on the wafer W placed on the hot plate 30, thus preventing deformation of the coating film due to the purge gas from gas supply pipes 110 and 111.

[0083] (modified version) In the above examples, the coating film was formed from a negative-type resist solution, but it may also be formed from a positive-type resist solution. Furthermore, the coating film may be formed from a coating solution other than a resist solution.

[0084] Furthermore, in the above example, the gas inlet that allows gas to flow into the space S above the heating plate 30 was an opening 16a, but the gas inlet may also be composed of a gas outlet that discharges gas.

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

[0086] Furthermore, the configurations described above may be implemented and used in combination with each other, in addition to the examples specified in the attached claims. [Explanation of Symbols]

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

Claims

1. A heating device for heat-treating a substrate, A heating plate on which a substrate is placed and which heats the substrate on which the substrate is placed, A gas inlet for introducing a first gas into the space above the heating plate, It comprises an exhaust section that exhausts air from the aforementioned space, The gas inlet and exhaust portions are arranged so as to face each other in a plan view, with the substrate placed on the heating plate in between. A heating device further comprising a gas supply unit that supplies a second gas into the space from the side of a substrate placed on the heating plate, in a direction perpendicular in a plan view to the airflow direction from the gas inlet to the exhaust unit.

2. The heating device according to claim 1, wherein the gas supply unit is provided at one position and the other position in a direction perpendicular to the substrate placed on the heating plate.

3. The gas supply unit has a plurality of discharge ports provided along the airflow direction from the gas inlet to the exhaust unit, The heating device according to claim 1 or 2, wherein the flow rate of the second gas discharged from each of the plurality of discharge ports differs according to the distance from the discharge port to the heating plate.

4. The heating device according to claim 3, wherein, among the plurality of discharge ports, the flow rate of the second gas from the discharge port closest to the heating plate is greater than the flow rate of the second gas from the other discharge ports.

5. A top plate facing the heating plate across the aforementioned space, A lifting mechanism for raising and lowering the circuit board, It further comprises a control unit and, The heating apparatus according to claim 1 or 2, wherein the control unit controls the substrate to maintain a first state in which the substrate is separated from the top plate by a predetermined distance, thereby promoting the 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, thereby further promoting the drying of the coating film.

6. The heating apparatus according to claim 5, wherein in the first state, the substrate is further away from the heating plate than in the second state.

7. A heating method for heating a substrate using a heating device, The heating device is A heating plate on which a substrate is placed and which heats the substrate on which the substrate is placed, A gas inlet for introducing a first gas into the space above the heating plate, It comprises an exhaust section that exhausts air from the aforementioned space, The gas inlet and exhaust portions are arranged so as to face each other in a plan view, with the substrate placed on the heating plate in between. A heating method comprising the step of supplying a second gas from the side of a substrate placed on a heating plate into the space, in a direction perpendicular to the airflow direction from the gas inlet to the exhaust, in a plan view, by a gas supply unit.

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