Heat treatment method, program, and heat treatment apparatus

Abstract

This invention provides a technique for accelerating the change in solubility in a developer solution when an exposed resist is formed on the surface of a substrate, the solubility of the exposed or unexposed areas of the resist changing when heated in response to water. [Solution] The system includes a stage 23 on which an exposed resist film formed on the surface of the substrate W, on which the solubility of the exposed or unexposed areas in the developer solution changes when heated in reaction with water, is placed and heated; a lifting mechanism 27 that moves the substrate W up and down relatively between a first position on the stage 23 and a second position away from the stage; and a gas supply unit 3 that supplies a first gas with a higher humidity than the atmosphere in which the stage 23 is provided to the substrate W, which is located at the second position before it moves to the first position.

Description

Technical Field

[0001] The present disclosure relates to a heat treatment apparatus and a heat treatment method.

Background Art

[0002] In the photolithography process in the semiconductor device manufacturing process, for example, a resist is applied onto a semiconductor wafer (hereinafter referred to as "wafer") to form a resist film. Next, an exposure process for exposing a predetermined circuit pattern is performed on the wafer on which the resist film is formed. Further, by heat-treating the wafer on which the exposed resist is formed, a chemical reaction in the exposed portion or the unexposed portion of the resist film proceeds, and the resist film is dissolved or insolubilized in the developer. Thereafter, by supplying the developer to the heat-treated wafer W, the soluble portion of the resist film is removed, and a predetermined resist pattern is formed on the wafer.

[0003] In recent years, there has been a demand for further high integration of semiconductor devices. Therefore, miniaturization of the resist pattern has been required, and an exposure process using EUV (Extreme Ultraviolet) has been proposed. In the exposure process using EUV, it is required that the resist film has high sensitivity to exposure, and for example, a metal-containing resist as described in Patent Document 1 is used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique capable of promoting a change in solubility when heat-treating a substrate having a developed resist formed on its surface, the solubility of which in a developer changes in an exposed portion or an unexposed portion by reacting with water and being heated. [Means for solving the problem]

[0006] The heat treatment apparatus of the present disclosure includes a stage on which an exposed resist film, on which a substrate has been formed with an exposed resist film on its surface, has its solubility in the exposed or unexposed areas of the film changed by heating in reaction with water, is placed and heated, A lifting mechanism that moves the substrate up and down relative to a first position on the stage and a second position away from the stage, A gas supply unit supplies a first gas with a higher humidity than the atmosphere in which the stage is provided to the substrate located at the second position before it moves to the first position, It is equipped. [Effects of the Invention]

[0007] According to this disclosure, when heat-treating a substrate on which an exposed resist has been formed on its surface, the solubility of the exposed or unexposed areas in the developer solution changes when heated in reaction with water, it is possible to accelerate the change in solubility. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional side view of a heat treatment apparatus according to the first embodiment. [Figure 2] This is a diagram showing the operation of the heat treatment apparatus. [Figure 3] This is a diagram showing the operation of the heat treatment apparatus. [Figure 4] This is a diagram showing the operation of the heat treatment apparatus. [Figure 5] This is a longitudinal cross-sectional side view of a processing chamber provided in a heat treatment apparatus according to the second embodiment. [Figure 6] This is an operation diagram showing the operation of the heat treatment apparatus according to the second embodiment. [Figure 7] This is an operation diagram showing the operation of the heat treatment apparatus according to the second embodiment. [Figure 8] This is an operation diagram showing the operation of the heat treatment apparatus according to the second embodiment. [Figure 9] This is a plan view of the lower side of the gas supply unit according to the third embodiment. [Figure 10] This is a longitudinal cross-sectional side view of a processing chamber provided in a heat treatment apparatus according to the third embodiment. [Figure 11] This is an explanatory diagram showing an example of gas supply in the third embodiment. [Figure 12] This is a longitudinal cross-sectional side view showing another example of a heat treatment apparatus according to the third embodiment. [Figure 13] This is a diagram illustrating the operation of another example of the heat treatment apparatus. [Figure 14] This is a diagram illustrating the operation of another example of the heat treatment apparatus. [Figure 15] This is a longitudinal cross-sectional view showing a coating and developing apparatus. [Figure 16] This is a plan view showing the coating and developing apparatus. [Figure 17] This graph shows the results of the example. [Modes for carrying out the invention]

[0009] [First Embodiment] The heat treatment apparatus 1 described herein will now be explained. This heat treatment apparatus 1 is a device for heating a wafer W on which a resist film has been formed, and the resist film has been exposed along a circuit pattern, for example by EUV. Therefore, the heat treatment apparatus 1 is a device for performing so-called post-exposure baking (PEB). The resist constituting this resist film contains, for example, a metal, and an example of such a metal is tin. To further explain the resist, when irradiated with radiation such as EUV, ligands are detached from the metal, and in that state, the resist reacts with water to introduce hydroxyl groups. When subsequently heated, dehydration condensation occurs between these hydroxyl groups, and as a result, it becomes insoluble in the developer solution.

[0010] The heat treatment apparatus 1 performs the above-described introduction of hydroxyl groups (hydrophilic treatment) and dehydration condensation. Therefore, as a result of the treatment by the heat treatment apparatus 1, the exposed regions of the resist film become insoluble in the developer, and the unexposed regions are dissolved and removed by the developer, forming a pattern on the resist film. The configuration of the heat treatment apparatus 1 will be described while referring to the longitudinal sectional view of FIG. 1. The heat treatment apparatus 1 includes a housing 10, and a transfer port 10A for the wafer W is provided on the side wall of the housing 10. Further, the heat treatment apparatus 1 is provided in an air atmosphere, and both the inside and outside of the housing 10 are in the air atmosphere. A chamber (treatment chamber) 20 for heat-treating the wafer W is provided on the back side when viewed from the side where the transfer port 10A opens inside the housing 10. The treatment chamber 20 includes a lid portion 21 that constitutes the ceiling portion, and a lower side portion 22 that is located below the lid portion 21 and includes a bottom portion. The lid portion 21 that constitutes the upper side portion of the treatment chamber 20 is connected to a chamber lifting mechanism 28 via a support portion 29. Then, by the lifting mechanism 28, when the lid portion 21 is lifted with respect to the lower side portion 22, the treatment chamber 20 is separated and opened, and when the lid portion 21 is lowered, the treatment chamber 20 is closed.

[0011] A stage 23 is provided inside the lower side portion 22. Note that reference numeral 25 in FIG. 1 is a holding member for holding the stage 23. A heater 24 is embedded in the stage 23, and is configured to heat the wafer W placed on the stage 23, for example, at 50°C to 210°C. Three through holes 23a penetrating the stage 23 in the thickness direction are provided in the circumferential direction on the stage 23. Lifting pins 26 perpendicular to each through hole 23a are inserted therethrough. Each lifting pin 26 is connected to a lifting mechanism 27 installed at the bottom of the lower side portion 22. Further, each lifting pin 26 moves up and down by the lifting mechanism 27, and the tip of the lifting pin 26 protrudes and retracts on the surface of the stage 23. The wafer W moves up and down between a first position where it is placed on the stage 23 and a second position away from the stage 23 by the lifting pins 26 that protrude and retract on the surface of the stage 23.

[0012] By the way, regarding the resist film formed on the wafer W, if the above-mentioned hydrophilic treatment is insufficient, dehydration condensation may not proceed sufficiently. Therefore, there is a risk that the line width (width of the convex portion) of the resist pattern formed after the development process becomes thinner than the desired width. Thus, the heat treatment apparatus 1 according to the present disclosure includes a gas supply unit 3 that supplies moist air containing moisture to the wafer W to surely hydrophilize the resist film and promote dehydration condensation.

[0013] The gas supply unit 3 includes a shower head 30 provided inside the lid portion 21 and having an opposing surface that opposes the wafer W placed on the stage 23. The inside of the shower head 30 forms a diffusion space for diffusing gas. Further, on the lower surface (opposing surface facing the wafer W) of the shower head 30, gas discharge holes 31 for supplying gas toward the wafer W are formed dispersed over the entire surface.

[0014] One end of a gas supply pipe 32 is connected to the upper surface of the shower head 30 so as to communicate with the diffusion space. At the other end of the gas supply pipe 32, a gas supply source 33 for supplying a first gas having a higher humidity than the atmosphere in which the stage 23 is provided is provided via a valve V32. The first gas is, for example, moist air with a humidity of 68%. Note that the humidity used in this specification indicates relative humidity. Also, the atmosphere in which the stage 23 is provided refers to the atmosphere above the stage 23 when the first gas is not supplied from the gas supply unit 3 toward the wafer W. Therefore, the first gas, which is the above-mentioned moist air, is a gas for increasing the humidity of the atmosphere above the stage 23.

[0015] As the gas supply source 33, for example, a module capable of supplying air with a desired humidity by adjusting the moisture content of the air can be used. For example, the gas supply source 33 can be configured to include a bubbler, a first line that supplies the water vapor generated by the bubbler to the downstream side, and a second line that supplies air at an arbitrary flow rate to the water vapor flowing through the first line for mixing. By adjusting the air flow rate in the second line, air with the desired humidity can be supplied to the shower head 30. However, the configuration is not limited to this, and the gas supply source 33 can be configured in any way.

[0016] A central exhaust port 34 for exhausting the atmosphere inside the processing chamber 20 is located in the center of the lower surface of the shower head 30. A central exhaust pipe 341, which is provided to pass through the shower head 30, is connected to the central exhaust port 34. Furthermore, the shower head 30 is positioned with a gap between its side surface and the inner surface of the lid portion 21, and this gap constitutes an outer peripheral exhaust port 35 for exhausting air from the outer periphery of the wafer W. The outer peripheral exhaust port 35 is in communication with an outer peripheral exhaust pipe 351. The central exhaust pipe 341 and the outer peripheral exhaust pipe 351 are connected to the exhaust equipment in the factory and are configured to exhaust the atmosphere inside the processing chamber 20. V341 and V351 provided on the central exhaust pipe 341 and the outer peripheral exhaust pipe 351 are valves for opening and closing the central exhaust pipe 341 and the outer peripheral exhaust pipe 351, respectively.

[0017] A transport mechanism 11 is provided on the front side (transport opening 10A side) of the housing 10. The transport mechanism 11 includes a support plate 12, which is a horizontal, roughly circular support part, and a wafer W is placed on the surface of the support plate 12. The support plate 12 has a temperature control mechanism (not shown) embedded in it, which controls the temperature of the wafer W placed on the support plate 12 so that it is uniform across the surface. This support plate 12 moves along a guide rail 15 provided on the bottom surface of the housing 10, extending from the transport opening 10A side to the rear side, by a moving mechanism 14 connected via a support member 13. As a result, the support plate 12 can move between the area above the stage 23 and the area outside the processing chamber 20 (the position shown in Figure 1) which is laterally separated from the stage 23.

[0018] When the transport mechanism 11 is located in the outer region, the external transport mechanism of the heat treatment apparatus 1 holding the wafer W enters the housing 10 through the transport opening 10A. Furthermore, the external transport mechanism moves up and down from above the support plate 12, thereby transferring the wafer W between the external transport mechanism of the heat treatment apparatus 1 and the transport mechanism 11 inside the housing 10. The support plate 12 has a slit (not shown) extending from one end on the processing chamber 20 side to the other end. This slit allows the lifting pin 26, which protrudes from the stage 23 when the support plate 12 is positioned on the stage 23, to protrude onto the support plate 12 through this slit. The lifting and lowering of the lifting pin 26 and the movement of the transport mechanism 11 work together to transfer the wafer W between the stage 23 and the support plate 12.

[0019] The heat treatment apparatus 1 includes a control unit 100, which is, for example, a computer. The control unit 100 is configured to output control signals to the chamber's lifting mechanism 28, lifting mechanism 27, valves V32, V341, V351, and moving mechanism 14. The control unit 100 stores a program in which instructions (a group of steps) are set up to execute the sequence of operations of the heat treatment apparatus 1, as shown later, including the transfer of wafers W, the raising and lowering of the lifting pins 26 and the lid 21, and the supply of gas. This program is stored on a storage medium such as a compact disk, hard disk, MO (magneto-optical disk), DVD, or memory card and installed in the control unit 100.

[0020] The operation of the heat treatment apparatus 1 according to this disclosure will now be explained. The heat treatment apparatus 1 is in standby mode with the stage 23 heated to 50°C to 210°C by, for example, a heater 24, and the processing chamber 20 open with exhaust gases being released from the exhaust ports 34 and 35. The support plate 12 is also in standby mode at the position for receiving the wafer W (indicated by the solid line in Figure 1). First, an external transport mechanism (not shown) holding the exposed wafer W is brought into the heat treatment apparatus 1 and moved from above to below the support plate 12 to place the wafer W on the support plate 12.

[0021] Next, the support plate 12 is moved directly above the stage 23. Furthermore, the wafer W supported by the support plate 12 is pushed up by the lifting pins 26 and supported at a second position on the stage 23, and the support plate 12 retracts to the outer region. Subsequently, as shown in Figure 2, the first gas is supplied to the wafer W, and exhaust is performed, for example, from the outer peripheral exhaust port 35 among the exhaust ports. At this time, the lid 21 remains raised, and the processing chamber 20 is open. Moisture is supplied to the wafer W by exposure to the first gas, which is humid air, and the resist film is hydrophilized.

[0022] Next, as shown in Figure 3, while the first gas supply and exhaust from the outer peripheral exhaust port 35 are still being performed, the lifting pin 26 descends and the wafer W moves to the placement position (first position) on the stage 23. For example, the lid 21 is lowered in parallel with the descent of the lifting pin 26 to close the processing chamber 20. In this way, the wafer W is placed on the stage 23 and heated to the same temperature as the stage 23, undergoing heat treatment. As the temperature of the wafer W rises, the dehydration condensation of hydroxyl groups described above occurs, and the insolubilization of the exposed areas in the resist film in the developer proceeds.

[0023] Once the heat treatment of the wafer W is complete, as shown in Figure 4, the supply of the first gas is stopped, and exhaust from the outer peripheral exhaust port 35 is stopped, and the system is switched to exhaust from the central exhaust port 34. Subsequently, the lid 21 is raised to open the processing chamber 20, and the lifting pin 26 is raised to lift the wafer W from the stage 23. Then, the transport mechanism 11 and the lifting pin 26 work together to transfer the wafer W to the transport mechanism 11. The wafer W is then transferred to an external transport device, removed from the heat treatment apparatus 1, and subjected to developing.

[0024] According to the heat treatment apparatus 1, air with a higher humidity than the atmosphere on the stage 23 (first gas) is supplied to the wafer W for heat treatment. As a result, during heat treatment, hydroxyl groups are sufficiently introduced in the exposed areas of the resist film, and the insolubilization of these exposed areas proceeds rapidly during the heat treatment. In other words, the sensitivity of the exposed areas to the reaction due to heating is increased. Because the insolubilization of the exposed areas is promoted in this way, it is suppressed that this insolubilization is insufficient during the development process, and that the width of the protrusions of the resist pattern becomes smaller than the set value.

[0025] Incidentally, after the wafer W is placed on stage 23 and heated, it is conceivable that the adhesion of water contained in the first gas to the resist film will decrease due to the heat of the wafer W. However, with the heat treatment apparatus 1, the first gas is supplied even before the wafer is placed on stage 23, so heating is performed with the hydroxyl groups introduced as described above reliably. Therefore, the rapid insolubilization of the exposed area described above can be performed with high reliability. Furthermore, since the position where the first gas is supplied is above stage 23, the wafer W can be quickly placed on stage 23 and heat treatment performed after the hydroxyl groups have been introduced.

[0026] Therefore, drying occurs on the surface of the wafer W due to the influence of the airflow in the region where the wafer W moves from the first gas supply until it is placed on the stage 23. This suppresses variations in the amount of moisture penetration into the resist on the surface of the wafer W until it is placed on the stage 23. In other words, since variations in the state of hydroxyl group introduction on the surface of the wafer W are suppressed, variations in the line width of the pattern on the surface of the wafer W after development can be suppressed.

[0027] Furthermore, by supplying the first gas with the wafer W in the second position, a higher humidity first gas can be supplied to the wafer W in a state closer to the showerhead 30 compared to when the wafer W is placed on the stage 23. In other words, because the space between the surface of the wafer W and the first gas supply unit is narrower than when the wafer W is heat-treated, airflow is less likely to occur on the wafer W, allowing moisture to penetrate more uniformly across the wafer W surface. Also, when supplying the first gas with the wafer W in the second position, the wafer W has not yet been heat-treated, so there is less sublimation generated due to the heat treatment of the wafer W. For this reason, the exhaust from the processing chamber 20 may be made weaker or turned off compared to when the wafer W is heat-treated (when the wafer W is placed on the stage 23), thereby adjusting the airflow around the wafer W to prevent leakage of sublimation while avoiding unnecessarily increasing the airflow on the wafer W.

[0028] In order to miniaturize the resist pattern, an exposure apparatus that irradiates with EUV from the light source, as in this embodiment, is sometimes used. However, exposure apparatuses that utilize EUV have a relatively low light output from the light source. Therefore, the resist is required to have a relatively low dose of solubility, that is, to be highly sensitive. As described above, the metal-containing resist used in this embodiment reacts with high sensitivity to moisture due to the desorption of the ligand. As described above, this technology utilizes this property of the resist to change the solubility of the resist film in the developer. Therefore, with this technology, a pattern can be reliably formed on the resist film even when using an exposure apparatus with low output, such as EUV. Furthermore, with the heat treatment apparatus 1, the supply of the first gas continues even after the wafer W is placed on the stage 23. Therefore, by more reliably introducing hydroxyl groups into the resist film and promoting the insolubilization reaction of the exposed areas in the film, a pattern with the desired line width can be obtained.

[0029] Furthermore, the wafer W processed by the heat treatment apparatus 1 according to this disclosure is not limited to resists containing metal, but can be any resist whose solubility in the exposed or unexposed areas in the developer changes when heated in reaction with water. Therefore, for example, a resist may be used in which the unexposed areas become solubilized or insoluble by the reaction, or in which the exposed areas become solubilized by the reaction. Even when such resists are used, this technology can reliably change the solubility of the resist in the exposed or unexposed areas. Note that a resist containing metal means that the metal is included as the main component, not as an impurity.

[0030] Furthermore, it is preferable that the humidity of the first gas is higher than 60%. As shown in the embodiments described later, by increasing the humidity to above 60%, the reaction rate can be greatly improved, and a significant effect can be obtained. Incidentally, although the humidity of the gas is sometimes described, the gas whose humidity is described is not limited to air. Therefore, the first gas may be a gas other than air. In the embodiments described later, the treatment may be performed using a gas with high humidity and a gas with low humidity, respectively, but these gases are also gases with high humidity and gases with low humidity as measured by a hygrometer, and these gases are not limited to air.

[0031] Alternatively, the flow rate of the first gas supplied to the wafer W may be reduced when the processing chamber 20 is open, and increased when the processing chamber 20 is closed. For example, in the heat treatment apparatus 1 shown in Figure 1, a flow rate adjustment unit is provided in the gas supply pipe 32, and the flow rate of the gas discharged from the shower head 30 is adjusted. Then, as shown in Figure 2, when the processing chamber 20 is opened and the wafer W is positioned at the second position on the stage 23 and the first gas is supplied, the flow rate of the first gas is set to the first flow rate. Furthermore, as shown in Figure 3, after the wafer W is placed on the stage 23 and the lid 21 is lowered to close the processing chamber 20, the flow rate of the first gas is set to a second flow rate, which is greater than the first flow rate.

[0032] When the processing chamber 20 is open, the amount of first gas flowing out of the processing chamber 20 can be suppressed by reducing the flow rate of the first gas supplied to the wafer W. This suppresses condensation caused by a high-humidity atmosphere outside the processing chamber 20. After closing the processing chamber 20, the flow rate of the first gas can be increased to supply a sufficient amount of first gas to the wafer W, thereby sufficiently hydrophilizing the resist film. The timing for lowering the lid 21 of the processing chamber 20 may be simultaneous with the lowering of the lifting pin 26, or it may be delayed. Furthermore, the exhaust port of the processing chamber 20 is not limited to being provided to exhaust from both the center of the wafer W and the outer circumference of the wafer W, but may be provided to exhaust from only one of them.

[0033] [Second Embodiment] Next, a heat treatment apparatus 1A according to the second embodiment will be described. In the drawings of this heat treatment apparatus 1A and the heat treatment apparatuses 1B and 1C described later, parts with the same configuration as the heat treatment apparatus 1 of the first embodiment are omitted, and only the processing chamber 20 is shown. As shown in Figure 5, the heat treatment apparatus 1A has a gas supply pipe 300, one end of which is connected to the diffusion space of the shower head 30, and the other end is branched into two. A first gas supply source 301 that supplies the first gas is installed at one end of the other end of the gas supply pipe 300, and a second gas supply source 302 that supplies the second gas, which has a lower humidity than the first gas, is installed at the other end. The first gas is, for example, air with a humidity of 68%, and the second gas is, for example, air with a humidity of 20%.

[0034] Reference numeral 303, provided in the gas supply pipe 300, is a three-way valve for switching the gas supplied to the shower head 30 between a first gas and a second gas. Alternatively, instead of the three-way valve 303, a mixing box may be provided to supply the first gas and the second gas by changing the mixing ratio of high-humidity gas and low-humidity gas.

[0035] First, the wafer W, which has been brought into the heat treatment apparatus 1A, is supplied with the first gas at a second position, as shown in Figure 6, before being placed on the stage 23. Then, as shown in Figure 7, with the first gas still supplied, the wafer W is placed on the stage 23 (moved to the first position) to start the heat treatment, and the processing chamber 20 is closed. After the heat treatment has been performed on the wafer W, the gas supplied to the wafer W is switched to the second gas (Figure 8).

[0036] While the reaction rate can be increased by performing heat treatment while supplying a high-humidity gas, supplying excessive moisture to the wafer W during heat treatment may worsen the roughness of the resist film surface and the in-plane uniformity of the resist pattern line width. Therefore, by lowering the humidity of the supplied gas in accordance with the progress of the reaction in the resist film during heat treatment of the wafer W, and adjusting the amount of moisture supplied to the wafer W, it is possible to suppress the deterioration of the roughness of the resist film surface and the deterioration of the in-plane uniformity of the resist pattern line width.

[0037] Furthermore, when heat-treating the wafer W, it is difficult to make the moisture content uniform across the surface of the wafer W, and when heating while supplying high-humidity humid air to the wafer W, differences in moisture content are likely to occur across the surface of the wafer W. For this reason, as shown in Figure 5, after supplying the first gas to the wafer W in the second position before placing it on the stage 23, the gas supplied to the wafer W may be switched to the second gas before placing the wafer W on the stage 23. Then, the wafer W with the second gas supplied may be placed on the stage 23, and heat treatment may be performed on the wafer W while supplying the second gas, as shown in Figure 8. Furthermore, the second gas, which has lower humidity than the first gas, may be an inert gas such as nitrogen (N2) gas. Also, from the viewpoint of sufficiently changing the humidity of the gas supplied to the wafer W, it is preferable that the humidity difference between the first gas and the second gas be, for example, 20% or more.

[0038] [Third Embodiment] Furthermore, the humidity of the gas supplied to the wafer W may be adjusted within the plane of the wafer W. Figure 9 is a bottom plan view of an example of a shower head 30 provided in such a heat treatment apparatus 1B. For example, when viewed from below, the shower head 30 is provided with a central gas supply area 300A and five gas supply areas 300B to 300E, which are formed by dividing the area surrounding the central area in the circumferential direction into four parts, and gas discharge holes 31 are formed in each gas supply area 300A to 300E. Furthermore, as shown in Figure 10, the inside of the shower head 30 is configured into five sections 301A to 301E corresponding to each area, and gas supply sources 33A to 33E are connected to each section 301A to 301E via gas supply pipes 32A to 32E. Note that in Figure 10, for convenience, the five sections 301A to 301E are shown arranged horizontally.

[0039] For example, when supplying the first gas to a wafer W that is being heat-treated after being placed on stage 23 (moved to the first position) as shown in Figure 3, the humidity of the first gas supplied from each region 300A to 300E is adjusted, as shown in Figure 11, so that the humidity decreases in the order of gas supply regions 300B, 300D, 300A, 300C, and 300E. By adjusting the humidity of the humid air supplied within the plane of the wafer W in this way, the amount of moisture supplied to the resist film can be adjusted within the plane of the wafer W. By adjusting the moisture supplied to the wafer W within the plane, the reaction rate of the resist can be adjusted within the plane of the wafer W. Note that when heat treatment is performed while supplying the first gas to a wafer W located in the second position before being placed on stage 23, the humidity of the first gas supplied to the wafer W can also be adjusted within the plane of the wafer W.

[0040] Furthermore, suppose that when a resist pattern is formed on the wafer W by performing the processing as described in the first embodiment, the line width of the resist pattern tends to be narrower at the periphery of the wafer W compared to the center. To cancel this tendency, in addition to supplying the first gas to the entire surface of the wafer W, the first gas may also be supplied toward the periphery of the wafer W. Figure 11 shows a processing chamber 20 provided in such a heat treatment apparatus 1C. Similar to the heat treatment apparatus 1 shown in Figure 1, this processing chamber 20 is equipped with a shower head 30A (hereinafter referred to as the "opposing gas supply unit") that supplies the first gas from an opposing part facing the wafer W placed on the stage 23. Furthermore, the heat treatment apparatus 1C is equipped with an outer periphery gas supply unit 30B that supplies the first gas from the outer periphery of the wafer W toward the center of the wafer W.

[0041] The outer periphery gas supply section 30B is configured, for example, as an annular pipe 310 with a rectangular cross-section, and is provided along the inner surface of the lower end of the lid 21. Multiple gas discharge holes 311 are formed along the circumferential direction of the wafer W on the inner wall of the pipe 310 for supplying a first gas from the outer periphery of the wafer W placed on the stage 23 when the lid 21 is lowered to seal the processing chamber 20. One end of a gas supply pipe 312 is connected to the pipe 310, and the other end of the gas supply pipe 312 is connected to a gas supply pipe 32 that supplies gas to the opposing gas supply section 30A, so that the first gas is supplied from the gas supply source 33. V312 in Figure 12 is a valve.

[0042] This heat treatment apparatus 1C, for example, supplies a first gas from the opposing gas supply unit 30A to the wafer W in a second position before it is placed on the stage 23, similar to Figure 2. Then, as shown in Figure 13, with the gas discharged from the opposing gas supply unit 30A, the wafer W is lowered and placed on the stage 23, and the lid 21 is lowered to close the processing chamber 20. This allows the wafer W to be heat-treated while the first gas is supplied to its entire surface. Then, as shown in Figure 14, with the wafer W placed on the stage 23, the supply of the first gas from the opposing gas supply unit 30A is stopped, and the first gas is supplied from the outer peripheral gas supply unit 30B. The process shown in Figure 13 and the process shown in Figure 14 are repeated multiple times. This allows the supply amount of the first gas in the outer peripheral region of wafer W to be greater than the supply amount of the first gas in the central region of wafer W. Consequently, the moisture content in the outer peripheral region of wafer W increases, and the reaction rate can be increased. This suppresses the reduction in the line width of the resist pattern on the outer peripheral side of wafer W.

[0043] Next, a coating and developing apparatus equipped with the heat treatment apparatuses 1, 1A to 1C described above will be explained. Figures 15 and 16 are schematic longitudinal cross-sectional side views and plan views, respectively, of the coating and developing apparatus. This coating and developing apparatus is composed of a carrier block D1, a processing block D2, and an interface block D3 connected in a straight line in order. On the interface block D3, an exposure apparatus D4 is connected to the opposite side from the connection direction of the processing block D2. The carrier block D1 has the role of loading and unloading carrier C into and out of the coating and developing apparatus, and is equipped with a mounting table 91 for carrier C, an opening / closing part 92 that moves up and down to open and close the lid of carrier C, and a transfer mechanism 93 for transporting wafer W from carrier C via the opening / closing part 92.

[0044] Processing block D2 is composed of unit blocks E1 to E6 stacked in order from bottom to top. Unit blocks E1 to E3 are equipped with a resist coating device as a liquid processing device 8, which applies resist and forms a resist film on the wafer W. Unit blocks E4 to E6 have a configuration that is substantially the same as unit blocks E1 to E3, but instead of a resist coating device, they are equipped with a developing device that supplies developing solution to the wafer and performs developing. Figure 16 shows unit block E5.

[0045] Unit block E5 is provided with a transport mechanism F5 that moves along a linear transport path from the carrier block D1 side to the interface block D3. Viewed from the carrier block D1 side, developing devices, which are liquid processing devices 8, are arranged in a row on the right side of the transport path. Also viewed from the carrier block D1 side, the heat processing devices 1 according to this disclosure are arranged in a row on the left side of the transport path. On the carrier block B1 side of the transport path, a shelf unit U7 is provided, which is composed of multiple modules stacked on top of each other. The transfer of wafers W between the transport arm 103 and the transport mechanism A5 is performed via the transfer module of the shelf unit U7 and the transport arm 104.

[0046] As shown in Figure 15, a filter 101 is provided on the ceiling of the transport path. Air from the cleanroom where the coating and developing equipment is located is taken in by an FFU (Fun Filter Unit) (not shown) and supplied to the filter 101, and then supplied downward from the filter 101. This supplied air is exhausted at the lid 21 of the processing chamber 20 of the heat treatment apparatus 1, flows into the housing 10 of the heat treatment apparatus 1, and is supplied onto the stage 23. In other words, this air forms the atmosphere around the stage 23. Therefore, the first gas supplied to the wafer W by the heat treatment apparatus 1 is a gas with a higher humidity than the air supplied via the filter 101.

[0047] The tower T1 shown in Figure 1 is located on the carrier block D1 side and extends vertically across each unit block E1 to E6. Transfer modules TRS are provided at each height of the unit blocks E1 to E6. A transfer arm 95 that can be raised and lowered is also provided on the carrier block D1 side for transferring wafers W to the tower T1. In Figure 15, the transport mechanisms 11 for each unit block E1 to E6 are shown as F1 to F6.

[0048] Interface block D3 includes towers T2, T3, and T4 that extend vertically across unit blocks E1 to E6. Wafers W are transferred between towers T2 and T3 by a vertically movable interface arm 96, and between towers T2 and T4 by a vertically movable interface arm 97. An interface arm 98 is also provided for transferring wafers W between tower T2 and the exposure apparatus D4. Modules such as transfer modules TRS are stacked on top of each other in tower T2. Modules are also provided in towers T3 and T4, but their description is omitted here.

[0049] In this coating and developing apparatus, the wafer W transported by carrier C is transported to unit blocks E1 to E3, where it undergoes resist film formation and heat treatment in sequence as described above. The wafer W is then transported to exposure apparatus D4 via transfer modules TRS at each height of unit blocks E1 to E3 in tower T2 of interface block D3, where it undergoes exposure treatment. After exposure, the wafer W is transported to transfer modules TRS at each height of unit blocks E4 to E6 in tower T2. Subsequently, the wafer W is transported to heat treatment apparatus 1 in unit blocks E4 to E6 for the heat treatment described above, then transported to developing apparatus, where it undergoes development treatment in sequence to form a resist pattern, and then returned to carrier C.

[0050] As discussed above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The embodiments described above may be omitted, substituted, modified, and combined in various ways without departing from the scope and spirit of the appended claims.

[0051] [Examples] To verify the effectiveness of the heat treatment apparatus according to this disclosure, Examples 1, 2, and 3 were created by using the heat treatment apparatus 1 shown in the first embodiment and setting the humidity of the first gas to 20%, 50%, and 68%, respectively, and processing the wafer W in the same manner as shown in the first embodiment. Each example was repeated three times, and the line width of the resist pattern was measured.

[0052] Figure 17 shows these results, with the black dots in the figure indicating the measured line widths of the resist patterns measured in Examples 1-3. The diamond shapes in each example represent the average diamond, the horizontal line in the center represents the average value for Examples 1-3, and the dots above and below the diamond represent the upper and lower limits of the two-sided 95% confidence interval for each example. Lines drawn above and below the average value for Examples 1-3 in the average diamond indicate overlap marks. Furthermore, the bars extending above and below the average value are the average error bars, and the dashed lines represent the standard deviation lines. Shown on the right side of the graph are comparison circles for Student's t-test (significance difference 0.05) for each combination.

[0053] According to these results, there was no significant difference in the line width of the resist pattern between Example 1 and Example 2. On the other hand, in Example 3, the line width was significantly thicker compared to Examples 1 and 2, and there was a difference of about 0.4 nm in line width between Examples 1 and 2 and Example 3. As mentioned above, the line width of the resist pattern becomes thicker as the reaction rate increases, so it can be said that the reaction rate can be greatly improved and the line width can be increased by setting the humidity of the first gas to more than 60%. [Explanation of symbols]

[0054] 1 Heat treatment apparatus 3. Gas Supply Department 23 stages 27 Lifting mechanism W wafer

Claims

[Claim 1] A stage on which an exposed resist film, on which the solubility of the exposed or unexposed areas in the developer solution changes when heated in reaction with water, is placed and heated, A lifting mechanism that moves the substrate up and down relative to a first position on the stage and a second position away from the stage, A gas supply unit supplies a first gas with a higher humidity than the atmosphere in which the stage is provided to the substrate located at the second position before it moves to the first position, A heat treatment apparatus equipped with [specific features / equipment].

Images