Heat treatment apparatus

Abstract

This invention provides a heat treatment apparatus that reduces defects caused by bubbles during film formation on a substrate. The heat treatment apparatus includes: a mounting section on which the substrate, before the film formed on it is cured, is placed; and a heating section that heats the substrate placed on the mounting section at a temperature lower than the boiling point of the solvent contained in the film.

Description

Technical Field

[0001] This disclosure relates to a heat treatment apparatus. Background Technology

[0002] In the manufacture of semiconductor devices, a film is formed by supplying liquid to a semiconductor wafer (hereinafter referred to as a wafer) serving as a substrate, and the wafer is subjected to a heat treatment to remove the solvent from the film. Patent Document 1 describes a heat treatment in which heating is performed in stages at different temperatures.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2000-91218 Utility Model Content

[0006] Problems to be solved by utility models

[0007] This disclosure reduces defects caused by bubbles during film formation on a substrate.

[0008] Solution for solving the problem

[0009] The heat treatment apparatus disclosed herein includes: a mounting section on which the substrate, before the film formed on the substrate is cured, is mounted; and a heating section that heats the substrate mounted on the mounting section at a temperature lower than the boiling point of the solvent contained in the film.

[0010] According to the heat treatment apparatus described above, it further comprises: a processing container forming a processing space in a manner surrounding the mounting portion, the processing container being closed during heating of the substrate by the heating portion, and the processing container having an exhaust port; and an exhaust portion venting the processing space from the exhaust port, such that the concentration of the solvent in the processing space at a second time point later than the first time point during the heating period is higher than the concentration of the solvent in the processing space at the first time point during the heating period.

[0011] According to the heat treatment apparatus described above, the film is formed by supplying a liquid containing an i-line exposure resist or polyimide with a viscosity of 50 cP to 10000 cP to the substrate before it is supplied to the substrate.

[0012] According to the heat treatment apparatus described above, the film is formed in such a way that it contacts a stepped pattern formed on the substrate.

[0013] According to the heat treatment apparatus described above, the membrane is a laminated membrane formed by overlapping multiple membranes of the same type.

[0014] According to the heat treatment apparatus described above, when the heating section is configured as a first heating section, the substrate is a substrate heated by a second heating section for removing the solvent at a transport destination from the mounting section, and the first heating section heats the substrate at a temperature lower than the heating temperature of the substrate by the second heating section.

[0015] According to the heat treatment apparatus described above, the processing container forms a processing space surrounding the mounting portion. During heating of the substrate by the heating portion, the processing container is closed, and the processing container includes an exhaust port and a gas supply port; an exhaust portion exhausts gas from the exhaust port into the processing space such that a first exhaust volume during a first period of more than half the length of the heating period is smaller than a second exhaust volume during a second period following the first period of the heating period; and a gas supply portion supplies gas to the processing space from the gas supply port during the second period to replace the atmosphere of the processing space from the atmosphere of the solvent to the atmosphere of the gas.

[0016] According to the heat treatment apparatus described above, the exhaust section exhausts air from the exhaust port during the period including the second period and the period before the substrate is moved into the processing container.

[0017] According to the heat treatment apparatus described above, the mounting section is a hot plate equipped with a heater serving as the heating section, the gas supply port opens to the outside of the hot plate when viewed from above, and the exhaust port is located at a position closer to the center of the hot plate than the gas supply port, and opens towards the periphery of the hot plate when viewed from above.

[0018] According to the heat treatment apparatus described above, the mounting section is a hot plate equipped with a heater that serves as the heating section, and a support ring is provided at a position facing the gas supply port, surrounding and connecting the hot plate.

[0019] Effects of the utility model

[0020] This disclosure reduces defects caused by bubbles during film formation on a substrate. Attached Figure Description

[0021] Figure 1 This is a top view of a wafer processing system including the heat treatment apparatus of this disclosure.

[0022] Figure 2 This is the front view of the wafer processing system.

[0023] Figure 3 This is a flowchart of the processing of the wafer processing system.

[0024] Figure 4 This is a longitudinal sectional side view of the heat treatment apparatus.

[0025] Figure 5 This is a partial cross-sectional top view of the processing vessel in the heat treatment apparatus.

[0026] Figure 6 This is a longitudinal sectional side view of the processing container.

[0027] Figure 7 This is a flowchart of the process performed by the heat treatment apparatus.

[0028] Figure 8 This is an explanatory diagram showing the operation of the heat treatment apparatus.

[0029] Figure 9 This is an explanatory diagram showing the operation of the heat treatment apparatus.

[0030] Figure 10 This is an explanatory diagram showing the operation of the heat treatment apparatus.

[0031] Figure 11 This is an explanatory diagram showing the operation of the heat treatment apparatus.

[0032] Figure 12 This is a schematic diagram showing the state of the wafer processed by the heat treatment apparatus.

[0033] Figure 13 This is a schematic diagram showing the state of the wafer processed by the heat treatment apparatus.

[0034] Figure 14 This is a schematic diagram showing the state of the wafer processed by the heat treatment apparatus.

[0035] Figure 15 This is a schematic diagram showing the state of the wafer.

[0036] Figure 16 This is a schematic diagram showing the state of the wafer.

[0037] Figure 17 This is a longitudinal sectional side view of a heat treatment apparatus showing a modified example. Detailed Implementation

[0038] The wafer processing system, which is a substrate processing apparatus according to this embodiment, will now be described with reference to the accompanying drawings. Furthermore, in this specification, elements having substantially the same functional structure are labeled with the same reference numerals, thereby omitting repeated descriptions.

[0039] <Wafer Processing System>

[0040] First, the structure of the wafer processing system involved in this embodiment will be explained. Figure 1 , Figure 2 These are a top view and a front view, respectively, schematically showing the outline of the structure of the wafer processing system 1. In this embodiment, the wafer processing system 11 is described as a photolithography system that performs resist film formation and development processes on the wafer W.

[0041] like Figure 1 As shown, the wafer processing system 1 includes: a cassette station 2 for loading and unloading cassettes C containing multiple wafers W; and a processing station 3 equipped with various processing devices for performing prescribed processing on the wafers W. Furthermore, the wafer processing system 1 has a structure that integrates the cassette station 2, the processing station 3, and the interface station 4, with the interface station 4 handling wafer W exchange with an exposure device (not shown) adjacent to the interface station 4 on the opposite side of the processing station 3. Additionally, as... Figure 1 As shown, two processing stations 3 are set between box station 2 and interface station 4. However, one processing station 3 or more processing stations 3 can be set.

[0042] The cassette station 2 is equipped with multiple cassette mounting plates 21 and wafer transfer mechanisms 22 and 23. The cassette station 2 transfers wafers W between the cassettes C, which are mounted on the cassette mounting plates 21, and the processing station 3 via the wafer transfer mechanisms 22 or 23. For this purpose, the wafer transfer mechanisms 22 and 23 may be equipped with drive mechanisms in the X direction, Y direction, vertical direction, and around the vertical axis (θ direction), or may be equipped with drive mechanisms in all directions, as needed.

[0043] At least one of the wafer transport mechanisms 22 and 23 can transfer wafer W to the housing C, and can also transfer wafer W to the processing station 3. Furthermore, the transfer of wafer W to the processing station 3 can be, for example, between a third block G3 that has a transfer device accessible by the wafer transport mechanism 33 within the processing station 3 (described later). The third block G3 may also have multiple transfer devices (not shown) arranged vertically.

[0044] In addition, an inspection device (not shown) for inspecting wafer W can be provided at a location accessible by either of the wafer transport mechanisms 22 and 23.

[0045] Processing station 3 has multiple blocks, for example, it has three blocks: G1 (first block), G2 (second block), and G4 (fourth block). Additionally, as... Figure 2 As shown, layer 31, which includes the first G1 and the second G2, has multiple layers stacked in the vertical direction. For example, on the front side of processing station 3 ( Figure 1 The first G1 is located on the negative X-direction side of the processing station 3. Figure 1A second G2 is installed on the positive X-direction side. On the side of processing station 3 near interface station 4 ( Figure 1 A fourth G4 is provided on the Y-direction positive side or at the connection point with other adjacent processing stations 3. The fourth G4 may also have multiple connecting devices arranged in the vertical direction. In addition, the aforementioned third G3 may also be provided within the processing station 3.

[0046] The first G1 is equipped with multiple processing devices, such as a patterning film forming device (not shown) and a developing device (not shown). The patterning film forming device may include, for example, an anti-reflective film forming device in addition to a resist forming device.

[0047] For example, multiple processing units can be arranged horizontally. Furthermore, the number, configuration, and type of these processing units can be arbitrarily selected.

[0048] In these patterning film forming apparatuses and developing apparatuses, processing is performed, for example, by supplying a predetermined processing solution or a predetermined gas to the wafer W. In this way, the patterning film forming apparatus forms a resist film used as a mask when forming a pattern on the underlying layer, and an anti-reflective film for efficiently performing light irradiation processing, such as exposure processing. On the other hand, the developing apparatus removes a portion of the exposed resist film to form the uneven shape of the aforementioned mask.

[0049] In, for example, the second G2, a heat treatment apparatus (not shown) for heating and cooling wafer W is arranged in both the vertical and horizontal directions. Additionally, in the second G2, a hydrophobic treatment apparatus for improving the adhesion of the resist to wafer W, and a peripheral exposure apparatus for exposing the outer periphery of wafer W are arranged in both the vertical and horizontal directions. Figure 2 The devices are arranged in the Z-direction and horizontal direction, but neither is shown in the diagram. The number and configuration of these heat treatment devices, hydrophobic treatment devices, and peripheral exposure devices can be arbitrarily selected.

[0050] like Figure 1 As shown, a wafer transport region 32 is formed in the area sandwiched between the first G1 and the second G2 when viewed from above. A wafer transport mechanism 33, for example, is disposed in the wafer transport region 32.

[0051] The wafer transport mechanism 33 has a transport arm 33a that can move freely in, for example, the Y direction, the front-back direction, the θ direction, and the vertical direction. The wafer transport mechanism 33 can move within the wafer transport area 32 to transport wafers W to designated devices within the surrounding first G1, second G2, third G3, and fourth G4. Figure 1In the case of multiple processing stations 3, the wafer transfer mechanism 33 of the processing station 3 located on the side of the interface station 4 can transfer wafers W to the specified devices in the first G1, the second G2 and the fourth G4, and also to the specified devices in the fifth G5 (described later).

[0052] For example, wafer transport mechanism 33 Figure 2 As shown, multiple wafer transfer mechanisms 33 are arranged in the vertical direction. One wafer transfer mechanism 33 can transfer a wafer W to a predetermined device located at the height position of the upper layer 31 among the multiple layers 31 stacked in the vertical direction. Other wafer transfer mechanisms 33 can transfer wafer W to predetermined devices located at the height position of the lower layer 31. Multiple wafer transfer areas 32 are provided in such a way that wafer W can be transferred. Furthermore, the number of wafer transfer mechanisms 33 and the number of layers 31 corresponding to one wafer transfer mechanism 33 can be arbitrarily selected, for example, a separate wafer transfer mechanism 33 can be provided for each layer 31.

[0053] Alternatively, a shuttle conveyor mechanism (not shown) may also exist in wafer transport area 32 or in the first G1 and the second G2. The shuttle conveyor mechanism linearly transports wafer W between the space adjacent to one side of the processing station 3 and other spaces adjacent to it on the opposite side.

[0054] Interface station 4 is equipped with wafer transport mechanisms 41 and 42 and a fifth block G5 having multiple transfer devices. Interface station 4 uses wafer transport mechanisms 41 or 42 to transport wafer W between the exposure machine and the fifth block G5, where wafer W is transferred by wafer transport mechanism 33. For this purpose, wafer transport mechanisms 41 and 42 may be equipped with drive mechanisms in the X direction, Y direction, vertical direction, and about the vertical axis (θ direction), or may be equipped with drive mechanisms in all directions as needed. At least one of wafer transport mechanisms 41 and 42 can support wafer W and transport wafer W between the transfer devices and the exposure machine within the fifth block G5.

[0055] The cleaning device for cleaning the surface of wafer W and the aforementioned peripheral exposure device can also be located within the interface station 4 in a position accessible to either of the wafer transport mechanisms 41 and 42.

[0056] As described above, the inspection device can be installed at the cassette station 2, but it can also be installed at the processing station 3 and the interface station 4 at any wafer transport mechanism located inside each processing station. Figure 1 or Figure 2 The locations that can be accessed are 33, 41, and 42 in the table.

[0057] A control unit 100 is provided for the wafer processing system 1 described above. The control unit 100 is, for example, a computer, and has a program storage unit (not shown). The program storage unit stores programs for controlling the processing of the wafer W in the wafer processing system 1. Additionally, the program storage unit also stores programs for controlling the operation of the drive systems of the various processing devices, transport mechanisms, etc., described above to implement wafer processing in the wafer processing system 1. Each program contains a set of steps, enabling the control of the operation of each part of the wafer processing system 1 to transport and process the wafer W. The control unit 100 includes one or more control circuits that send control signals to each part of the wafer processing system 1 to control the operation, so that the operations of each step set described above are executed. Furthermore, the above programs can also be recorded in a computer-readable storage medium H and installed from that storage medium H into the control unit 100.

[0058] <Operations of the Wafer Processing System>

[0059] The wafer processing system 1 is configured as described above. Next, an example of wafer processing performed using the wafer processing system 1 configured as described above will be described.

[0060] First, the cassette C containing multiple wafers W is moved into the cassette station 2 of the wafer processing system 1 and placed on the cassette mounting plate 21. Then, the wafers W in the cassette C are sequentially removed by the wafer transfer mechanism 22 or 23 and transferred to the transfer device of the third G3.

[0061] The wafer W, which is being transferred to the third G3 junction device, is supported by the wafer transport mechanism 33 and then transported to the hydrophobication treatment device located in the second G2 for hydrophobication treatment. Next, the wafer W is transported by the wafer transport mechanism 33 to the resist forming device to form a resist film on the wafer W. After that, the wafer W is transported to the heat treatment device for pre-baking treatment before being transferred to the fifth G5 junction device. Furthermore, in... Figure 1 , Figure 2 In the case of multiple processing stations 3, wafer W is temporarily placed in the fourth G4 transfer device before being transferred to the fifth G5 transfer device, and then transferred between multiple wafer transfer mechanisms 33. Alternatively, wafer W can be transferred to the peripheral exposure device via the wafer transfer mechanism 33 as needed to expose the periphery of wafer W.

[0062] The wafer W, which is to be transferred to the fifth G5 junction device via wafer transport mechanisms 41 and 42, is then transferred to the exposure device for exposure processing with a specified pattern. Furthermore, the wafer W can be cleaned by a cleaning device before exposure processing.

[0063] The exposed wafer W is transferred to the fifth G5 transfer device via wafer transfer mechanisms 41 and 42. Then, it is transferred to the heat treatment apparatus via wafer transfer mechanism 33 for post-exposure baking.

[0064] The wafer W, which has undergone exposure and baking, is transported to the developing apparatus via the wafer transport mechanism 33 for developing. After developing, the wafer W is transported to the heat treatment apparatus via the wafer transport mechanism 33 for post-baking.

[0065] Subsequently, wafer W is transferred to the handover device of the third G3 via wafer transfer mechanism 33, and then transferred to the designated cassette C on the cassette carrier 21 via wafer transfer mechanism 22 or 23 of cassette station 2. This completes a series of photolithography processes. Alternatively, unnecessary devices listed as processing devices may be omitted, or processing within those devices may be omitted.

[0066] <Explanation on the formation of the resist film and subsequent heating>

[0067] Reference Figure 3 The process of forming the resist film and subsequent heat treatment is illustrated using a flowchart. The resist film is formed by supplying a liquid resist (resist solution) from a nozzle to the center of the surface of the wafer W using a resist film forming apparatus. Specifically, the resist film is formed by spin coating, in which the resist is diffused to the periphery by rotating the mounting portion of the wafer W that holds it in place (step S1). The resist is, for example, an i-line resist containing a wavelength of 365 nm as the photosensitive wavelength. Furthermore, the viscosity of the resist before being supplied to the wafer W is, for example, 50 cP to 10000 cP.

[0068] After the resist film is formed, the wafer W is transported to a heat treatment apparatus for heating as described above. More specifically, the wafer W is first transported to the heat treatment apparatus 5. At this time, the solvent constituting the liquid resist remains in the resist film, and this solvent is not solidified. Furthermore, in the heat treatment apparatus 5, an atmosphere of solvent vapor released from the resist film (hereinafter referred to as a solvent atmosphere) is formed in the processing container 6 holding the wafer W, and the wafer W is heated at a temperature lower than the boiling point of the solvent (step S2). By heating the wafer W in this solvent atmosphere, as described in detail later, the bubbles (air bubbles) contained in the resist film are removed.

[0069] Next, the wafer W is transferred to a heat treatment apparatus 5A, which is different from the heat treatment apparatus 5. In this heat treatment apparatus 5A, the wafer W is heated at a temperature higher than the heating temperature of the wafer W in the heat treatment apparatus 5 to remove the solvent remaining in the resist film, thereby curing the resist film (step S3). Therefore, a so-called PAB (post-apply bake) is performed in the heat treatment apparatus 5A. Furthermore, the heating of the wafer W in the heat treatment apparatus 5 is performed before the resist film cures. The structure of the heat treatment apparatus 5A is, for example, the same as that of the heat treatment apparatus 5 described later.

[0070] Suppose that after the resist film is formed, it is not heated by the heat treatment apparatus 5, but instead heated at a relatively high temperature by the heat treatment apparatus 5A. In this case, the resist film solidifies while the bubbles remaining in it expand due to heat, becoming relatively large bubbles. This could potentially prevent the subsequent pattern formation by photolithography and etching of the wafer W from proceeding properly. The treatment performed by the heat treatment apparatus 5 can prevent such defects caused by the residue of bubbles.

[0071] Furthermore, when the viscosity of the resist forming the resist film is relatively high, as in the exemplified range, when the resist is supplied from the nozzle and diffused by spin coating, surrounding air enters the resist and forms bubbles. Subsequently, the resist, due to its low fluidity, is difficult to expel from the film. In other words, when a liquid with the viscosity in the aforementioned range is supplied and a film is formed by drying the liquid, bubbles are easily contained in the film. Therefore, treatment by the heat treatment apparatus 5 is particularly effective.

[0072] <Heat treatment apparatus for removing bubbles>

[0073] Below, referring to the longitudinal sectional side view... Figure 4 Let's describe the heat treatment apparatus 5. Figure 51 shows the housing, which is a rectangular parallelepiped shape extending in the front-to-back direction. Figure 52 shows the wafer W transfer port formed on the front wall of the housing 51. Figure 53 shows a partition plate located below the transfer port 52, dividing the housing 51 internally in the vertical direction.

[0074] A conveyor 55 and a processing container 6 are provided inside the housing 51. The processing container 6 stores and processes the wafer W. The processing container 6 is located on the rear side inside the housing 51 and has a lower structure 61 and a cover 81. The cover 81 is raised and lowered between a raised position and a lowered position by a lifting mechanism 82, thereby opening and closing the processing container 6.

[0075] The lower structure 61 includes a hot plate 62, on which the wafer W is heated by placing it. Figure 1 The wafer transport mechanism 33 described herein has a standby position located on the front side inside the housing 51.Figure 4 The wafer W is transferred to the conveyor 55 at the position shown. With the processing container 6 open, the conveyor 55 can move back and forth between the standby position and the transfer position above the hot plate 62, and the wafer W is transferred between the conveyor 55 and the hot plate 62 at the transfer position by means of the pin described later.

[0076] The conveyor body 55 is a horizontal plate-shaped structure disposed on the partition plate 53, and the wafer W is placed on the upper surface of the conveyor body 55. The conveyor body 55 has a fluid flow path (not shown), and the temperature of the wafer W is adjusted by heat exchange between the wafer W and the fluid. The temperature of the fluid is set to cool the wafer W placed on the conveyor body 55 after it has been heated by the hot plate 62. 56 in the figure is a conveying mechanism disposed below the partition plate 53, connected to the conveyor body 55 via a connecting part 57, which moves the conveyor body 55 back and forth as described above.

[0077] <Structure of the processing container>

[0078] Below, also refer to the top view as a cross section. Figure 5 As a partial longitudinal sectional side view Figure 6 Let's explain how to process container 6. Figure 5 This is a cross-sectional top view of the protrusion 91, described later, and also shows the hot plate 62 and other structures below it. For ease of observation, the lower structure 61, described later, is shaded, the O-ring 69 is marked with small dots, and the location of the gas supply port 87, described later, is indicated by a dashed line. Furthermore, in Figure 4 , Figure 6 The diagram shows the processing container 6 in two states: with the cover 81 in the raised position and the processing container 6 in the lowered position. The airtight space within the processing container 6 in the closed state is defined as the processing space 6A. As described above, a solvent atmosphere is formed in the processing space 6A. When a solvent atmosphere is formed in this way, the processing container 6 is configured so that solvent vapor does not leak to the outside and affect the processing of the wafer W performed around the heat treatment apparatus 5, but this will be described in detail later.

[0079] First, the lower structure 61 of the processing container 6 will be described. The lower structure 61 is composed of a hot plate 62, a support ring 60, and a support body 7. The hot plate 62, which forms the mounting portion of the wafer W, is composed of an upper plate 63 and a lower plate 64, and the hot plate 62 includes a heater 65 as a heating part (first heating part). The upper plate 63 and the lower plate 64 are, for example, horizontal circular plates made of metal, with the upper plate 63 stacked on top of the lower plate 64. When viewed from above, the upper plate 63 and the lower plate 64 are arranged concentrically, and the diameter of the lower plate 64 is longer than the diameter of the upper plate 63. Therefore, the lower plate 64 protrudes from the upper plate 63 over its entire circumference, and the protruding area of ​​the lower plate 64 protruding from the upper plate 63 is defined as a flange 66. Furthermore, in Figure 5 The center of the upper plate 63 and the lower plate 64 when viewed from above is denoted as P. The wafer W is horizontally mounted on the upper plate 63 with its center aligned with this center P.

[0080] Heater 65 is configured, for example, as a plate-shaped member having a conductive pattern as a heating element, sandwiched between upper plate 63 and lower plate 64, heating wafer W through upper plate 63. Multiple heaters 65 are provided, each formed as a ring centered on center P when viewed from above, and the diameter of the ring is different among the heaters 65. For convenience, the heater located at the center of hot plate 62 will sometimes be described as 65A, and the heater located at the periphery of hot plate 62 will be described as 65B. Furthermore, 67 in the figure is an O-ring, which is set in a groove formed on the lower surface of upper plate 63 and surrounds heaters 65A and 65B, sealing the gap between upper plate 63 and lower plate 64.

[0081] Heater 65B is configured with power density per unit surface area (W / cm²). 2 The power density is greater than that of heater 65A. As described later, the periphery of the hot plate 62 contacts the support ring 60, and heat is transferred from the periphery of the hot plate 62 to the support ring 60. In order to prevent the temperature of the periphery of the hot plate 62 from being lower than that of the center of the hot plate 62 due to such heat transfer, the power density is designed to be different between heater 65A and heater 65B as described above.

[0082] Next, the support ring 60 will be described. The support ring 60 is a circular member centered at center P when viewed from above. The support ring 60 surrounds the entire circumference of the upper plate 63, acting as a thermal barrier from the upper plate 63 towards the outside of the processing container 6. The support ring 60 is, for example, made of resin. A gap is formed between the support ring 60 and the upper plate 63 to prevent the upper plate 63 from contacting and interfering with the support ring 60 due to thermal expansion.

[0083] The lower surface of the support ring 60 on the central side is connected to the flange 66, and the hot plate 62 is supported by the support ring 60 through this connection. By connecting the support ring 60 and the hot plate 62 to each other in this way, the heat transfer from the hot plate 62 to the support ring 60 becomes greater. Therefore, it is possible to prevent solvent vapor in the processing space 6A from condensing at the surface of the support ring 60 and remaining when the processing container 6 is opened. In other words, it is possible to prevent the solvent remaining in this way from vaporizing and leaking to the outside of the processing container 6 after the processing container 6 is opened.

[0084] The upper surface of the support ring 60 is horizontal and, as described later, is positioned at the same height as the upper surface of the upper plate 63 in a manner that does not impede the flow of air formed within the processing container 6. A groove 68 is formed along the circumference of the support ring 60 near the periphery of its upper surface, and an O-ring 69 is disposed in the groove 68. This O-ring 69 serves as a sealing member to ensure an airtight processing space 6A by sealing it tightly against the lower surface of the cover 81 when the processing container 6 is closed.

[0085] As described above, heat from the hot plate 62 is transferred to the support ring 60, which is in contact with the hot plate 62. This heat is also transferred to the O-ring 69, which is in contact with the support ring 60. Therefore, the thermal expansion of the O-ring 69 is relatively large, resulting in a higher seal between the O-ring 69 and the cover 81. Consequently, the airtightness of the processing space 6A is further improved, thus more reliably preventing solvent leakage to the outside of the processing container 6.

[0086] The support body 7 is a component that supports the hot plate 62 and the support ring 60 on the bottom wall of the housing 51, and is composed of a support body 71 and a support column 72. The support body 71 forms the lower side of the side wall and the bottom wall in the processing container 6, and is arranged to be recessed into the opening formed in the partition plate 53, and is supported from below by the support column 72 provided on the bottom wall of the housing 51. The support body 71 is concave in longitudinal section, and the upper part of the concave part is an enlarged diameter portion. The support ring 60 is received in the enlarged diameter portion and is supported by the support body 71 by connecting with the inner circumferential surface of the support body 71. Furthermore, the hot plate 62 is separate from the support body 71.

[0087] In addition, three pins 73 extending vertically are provided, penetrating the hot plate 62 and the support body 71. Each pin 73 is connected to the lifting mechanism 74 below the support body 71, and can protrude from and retract into the hot plate 62, thereby enabling the transfer of the wafer W between the hot plate 62 and the conveyor 55. In the figure, 75 is a bellows used to ensure the airtightness of the processing container 6, surrounding the pins 73 and connecting the lifting mechanism 74 to the support body 71.

[0088] Next, the cover 81 will be described. The cover 81 is configured as a horizontal circular plate. When the cover 81 is closed, a circular recess 83 forming the processing space 6A is provided on the lower surface of the cover 81 facing the hot plate 62. When viewed from above, the center of the recess 83 is located at center P. By forming the recess 83 in this way, the cover 81 constitutes the upper side and upper wall of the sidewall of the processing container 6.

[0089] Furthermore, the lower part of the recess 83 widens towards the periphery of the cover 81, thereby forming a flat, annular recess. This shallow recess 83 forms a relatively small processing space 6A, to which air is supplied as described later. The outer periphery of this annular recess overlaps with the support ring 60 when viewed from above, and is located closer to the center P than the O-ring 69. The flow path formed by this recess on the support ring 60 in the lowered position (the processing container 6 is closed) is designated as a lateral flow path 84. The area on the lower surface of the cover 81 that is outer of the lateral flow path 84 is configured as a horizontal sealing surface 80, which faces the O-ring 69. In the lowered position, the sealing surface 80 is in close contact with the O-ring 69.

[0090] A circular gas diffusion space 85, as viewed from above, is formed inside the cover 81. Multiple gas flow paths 86, spaced apart from each other, extend downward from the periphery of the gas diffusion space 85. Furthermore, the lower end of each gas flow path 86 opens into a side flow path 84 as a gas supply port 87, and is located opposite the support ring 60. Therefore, the gas supply port 87 opens outward from the upper plate 63 when viewed from above.

[0091] Additionally, a gas supply unit 88 is connected to the cover 81. The gas supply unit 88 includes, for example, a gas supply source, a supply path connected to the gas supply source, and a valve provided in the supply path, and is capable of supplying, for example, air as a gas to the center of the diffusion space 85 and cutting off the supply. The air supplied from the gas supply unit 88 to the gas diffusion space 85 is supplied to the support ring 60 from the gas supply port 87.

[0092] Furthermore, the center of the recess 83 of the cover 81 is further recessed upwards, and the center of this recess protrudes downwards to form a circular protrusion 91 when viewed from above. Multiple exhaust ports 92 are horizontally provided on the sides of the protrusion 91, and the exhaust ports 92 are spaced apart along the circumference of the protrusion 91. Therefore, each exhaust port 92 is located closer to the center of the hot plate 62 than the gas supply port 87, and opens towards the periphery of the hot plate 62 when viewed from above.

[0093] Each vent 92 is connected to a flow path 93 that extends downward from the upper surface of the cover 81 at the center of the cover 81 and reaches the protrusion 91. An vent 94 is connected to the flow path 93 of the cover 81. For example, the vent 94 has an vent path connected to an vent source and a valve provided in the vent path, which can switch whether to vent through the vent 92 via the flow path 93.

[0094] In this example, the operation of the gas supply unit 88 and the exhaust unit 94 is controlled to supply air from the gas supply port 87 while simultaneously exhausting air from the exhaust port 92. As described in detail later, periods for gas supply and exhaust, and periods for not supplying and exhausting gas, are set both during the opening and closing of the processing container 6. Figure 6 The dashed arrows indicate the airflow in the state where the processing container 6 is closed, forming the processing space 6A. The gas supply and exhaust during the closure of the processing container 6 are to remove the solvent atmosphere in order to prevent solvent vapor from leaking out when the processing container 6 is opened.

[0095] Air ejected from the gas supply port 87, located outside the hot plate 62 when viewed from above, onto the support ring 60 flows through the lateral flow path 84 on the support ring 60 towards the center of the processing container 6 due to the exhaust from the exhaust port 92. Furthermore, this air flows from the periphery side of the wafer W placed on the hot plate 62 towards the center and into the exhaust port 92. Solvent vapors in the processing space 6A are removed by the airflow thus formed. As described above, the air flows from the periphery side to the center side of the processing container 6, thus more reliably preventing solvent vapors from leaking to the outside of the processing container 6.

[0096] Furthermore, the height of the gas flow path 86 is greater than the height of the gap formed by the sealing surface 80 of the cover 81 and the support ring 60 on the center side of the processing container 6, closer to the O-ring 69. Moreover, relative to the side flow path 84, a space with a greater height than the side flow path 84 is formed on the center side of the processing container 6 due to the recess 83. In other words, the air supplied from the gas supply port 87 to the side flow path 84 has a lower pressure loss in the flow path towards the center of the processing container 6 than in the flow path towards the outside of the processing container 6. Therefore, this air is less likely to flow towards the outside of the processing container 6, and thus, solvent vapor leakage to the outside of the processing container 6 can be more reliably prevented.

[0097] Furthermore, as described above, the exhaust port 92 opens to the side facing the periphery of the hot plate 62 when viewed from above. This exhaust port 92 could also be configured to open downwards, but in that case, air supplied from each gas supply port 87 would accumulate below the exhaust port 92, and this accumulated air would flow upwards. That is, the air would locally concentrate above the uncured resist film, potentially affecting the film thickness. In other words, as described above, by having the exhaust port 92 open towards the periphery of the hot plate 62, it is preferable to suppress the influence of air flow on the film thickness of the resist film.

[0098] Additionally, a heater 95 is provided inside the cover 81. Multiple heaters 95 are provided, similar to the heaters 65 provided on the hot plate 62, and are formed into a plate shape that appears as a ring centered on center P when viewed from above. The diameter of this ring is different among the heaters 95. The heaters 95 heat the cover 81 to, for example, the same temperature as the hot plate 62, thereby preventing solvent vapor from condensing on the cover 81. That is, it prevents the condensed solvent from vaporizing and leaking out of the processing container 6 when it is opened.

[0099] <Wafer processing performed by heat treatment apparatus 5>

[0100] Next, use Figure 7 Flowchart, Figure 8-11 An explanatory diagram showing the operation of the heat treatment apparatus 5, and Figure 12-14 The schematic diagram showing the state of the resist film R formed on wafer W illustrates the processing of wafer W performed by heat treatment apparatus 5. It is assumed that other wafers W were processed prior to this processing of wafer W.

[0101] First, in the heat treatment apparatus 5 before the wafer W is loaded, the hot plate 62 is preheated to a set temperature, which is fixed in this example, including standby time when no heat treatment is performed. As already described, the set temperature is a temperature below the boiling point of the solvent, for example, 50°C to 100°C, more specifically, for example, 75°C.

[0102] Then, the cover 81 is positioned above the standby position and set to a state where air is supplied from the gas supply port 87 via the gas supply unit 88 and exhaust is performed from the exhaust port 92 via the exhaust unit 94 (step S21). Figure 8 That is, the processing container 6 is in the open state. Air supplied from the gas supply port 87 flows along the lower surface of the cover 81, into the exhaust port 92, and towards the exhaust section 94, so as to dry the flow path from the exhaust port 92 to the exhaust section 94. This drying process will be described in detail later.

[0103] Subsequently, when the conveyor 55 supporting the wafer W moves above the hot plate 62, the pin 73 protrudes upwards from the hot plate 62, and the wafer W is supported by the pin 73. Meanwhile, the gas supply and exhaust operations performed by the gas supply section 88 and the exhaust section 94 are stopped (step S22). Next, as the conveyor 55 retracts from the hot plate 62 and the pin 73 descends to place the wafer W on the hot plate 62, the cover 81 moves to the lowered position to close the processing container 6, forming the processing space 6A (step S23). The moment when the wafer W is placed on the hot plate 62 is designated as time t1.

[0104] The solvent gradually evaporates from the resist film of the wafer W, which is heated by being placed on the hot plate 62. Over time, the solvent concentration in the processing space 6A increases, forming a solvent atmosphere in the processing space 6A. Figure 9 Then, in the relatively small processing space 6A, the solvent vapor rapidly reaches or nearly reaches saturation, and the wafer W continues to be heated while the solvent concentration remains roughly constant. In other words, a gas-liquid balance is established between the liquid solvent in the resist film and the solvent vapor in the processing space 6A, and the resist film maintains its fluidity through the liquid solvent.

[0105] like Figure 12 As shown, the resist film R contains bubbles B of varying sizes caused by air trapped within it during resist coating. As described above, by heating the wafer W to a temperature below the boiling point of the solvent, the solvent in the resist film R remains and flows within the wafer W without excessive evaporation. The bubbles B become more mobile due to heating, generating convection through the aforementioned solvent flow and diffusing within the film. Through this movement within the film, the bubbles B break into smaller bubbles, or the solvent dissolution within the film progresses, resulting in (…). Figure 13 ) is removed from the resist film R ( Figure 14 (Step S24).

[0106] At time t2, after a predetermined time has elapsed since time t1, air supply from gas supply port 87 and exhaust from exhaust port 92 are restarted to remove solvent vapor from processing space 6A and replace processing space 6A with atmospheric atmosphere (step S25). Figure 10 ).

[0107] When the processing space 6A is replaced with an atmospheric atmosphere, while gas supply and exhaust are still being carried out through the gas supply port 87 and the exhaust port 92, the wafer W is removed from the heat treatment apparatus 5 in the reverse process of the wafer W being loaded (step S26). Figure 11Let time t3 be the moment when the wafer W leaves the hot plate 62 by the rise of pin 73. After the wafer W is removed, the aforementioned air supply and venting continue, thus repeating step S21. Even if the solvent vapor drawn from the vent 92 in step S25 condenses on the wall of the flow path from the vent 92 to the vent section 94, continued air supply and venting will vaporize and flush away the solvent, removing it from the flow path and drying it. Therefore, solvent leakage to the surrounding area of ​​the device is more reliably prevented.

[0108] After dissolving bubble B and removing it from resist film R as described above, wafer W is as follows: Figure 3 As described above, the film is moved into the heat treatment apparatus 5A and placed on the hot plate 62. For example, it is placed on the hot plate 62 while the treatment container is being vented and purged to perform heat treatment, thereby removing the solvent remaining in the film. Since the bubbles have been removed, the defects caused by bubble expansion, as described above, can be prevented. Furthermore, the heater 65 provided on the hot plate 62 of the heat treatment apparatus 5A serves as a second heating section.

[0109] Furthermore, the period from time t1 to time t3 when wafer W is placed on hot plate 62 is the heating period of wafer W, which is, for example, 60 seconds to 600 seconds, and more specifically, for example, 300 seconds to 600 seconds. The period from the start of this heating period to the gas supply and exhaust of the processing space 6A (time t1 to time t2) is defined as the first period, and the subsequent period (time t2 to t3) is defined as the second period. As described above, the first period is the period during which the wafer W is heated in a solvent atmosphere to dissolve the bubbles. The first period is set relatively long to reliably remove the bubbles; specifically, it is set to a length greater than half the length of the heating period. Therefore, the second period is shorter than the first period, for example, 30 seconds.

[0110] In the above-described processing example, no venting is performed through the venting section 94 during the first period. However, as long as sufficient flowability for bubble removal can be ensured on the anti-etching film, a small amount of venting may be performed during the first period. Therefore, the venting volume during the first period is set to be smaller than the venting volume during the second period, but it is not limited to not performing venting during the first period (i.e., making the venting volume 0). Furthermore, whether venting is performed or not during the first period, a solvent atmosphere is formed in the processing space 6A by solvent vapor released from the wafer W to the processing space 6A. This means controlling the operation of the venting section 94 so that the solvent concentration in the processing space 6A at the second time point immediately following the formation of the first time point is higher than the solvent concentration in the processing space 6A at the first time point.

[0111] In this example, gas is supplied through the gas supply section 88 while venting is performed through the venting section 94, but gas supply may not be performed through the gas supply section 88. However, from the viewpoint of preventing the wafer W from moving due to gas flowing in from the surroundings when the processing container 6 is opened, or from the viewpoint of reliably removing solvent vapors in the processing container 6 by purging them, it is preferable to also perform this gas supply.

[0112] The heat treatment described above is for... Figure 15 , Figure 16 Wafers like the one shown are particularly useful. Figure 15 In this process, a resist film R is pre-formed on the surface layer Wa in a manner that brings it into contact with the steps obtained through patterning. That is, the resist film R is formed by laminating it onto the film forming the raised and recessed pattern. During the formation of this resist film R, air is sometimes entrained in the resist as it passes over the steps during spin coating, thus raising concerns about the presence of numerous bubbles in the resist film R. Therefore, it is effective to remove these bubbles by heating using the heat treatment apparatus 5.

[0113] Furthermore, while resist films have been cited as an example of coating films used for bubble removal, they are not limited to resist films. Figure 16 In the example shown, the polyimide film R1 is the coated film intended for bubble removal. Further details are provided below. Figure 16 The following example is shown: spin coating using a coating liquid including polyimide is repeated twice, thereby forming a polyimide film R1 as a coating film.

[0114] During spin coating, a pre-wetting process, known as pre-wetting, is sometimes performed to improve the wettability of the wafer W surface to the coating solution before supplying it with the coating solution for forming the coating film, and to improve its spreadability by reducing the viscosity of the coating solution. However, in the case of forming two polyimide films R1, if pre-wetting is performed when forming the upper polyimide film R1, the lower polyimide film R1 will melt, making pre-wetting impossible. Consequently, the coating solution for forming the polyimide film on the upper side will diffuse on the wafer W at a relatively high viscosity, making it difficult to remove the incorporated bubbles. Therefore, removing bubbles by heating with the heat treatment apparatus 5 is effective. Furthermore, the same principle applies when stacking three or more films of the same type; for the same reason, removing bubbles by heating with the heat treatment apparatus 5 is also effective.

[0115] In addition, using the above Figure 15 , Figure 16The wafer W shown was subjected to an experiment to investigate the bubble removal performance of the heat treatment apparatus 5. Specifically, the number of bubbles in the film before processing by the heat treatment apparatus 5 was compared with the number of bubbles in the film after processing by the heat treatment apparatus 5 for each wafer W. As a result, the number of bubbles after processing for each wafer W was less than 1 / 10 of the number of bubbles before processing. That is to say, this is a preferred result where more than 90% of the bubbles are removed.

[0116] <Variation Example>

[0117] The heat treatment for removing bubbles from the resist film as described above is not limited to the heat treatment apparatus 5 with the above-described structure. Figure 17 This is a partial longitudinal sectional side view showing another heat treatment apparatus 5m used for performing the heat treatment of this disclosure. In the heat treatment apparatus 5m, an exhaust port 96 connected to an exhaust mechanism 97 is provided outside the O-ring 69 that ensures the airtightness of the treatment container 6. The heat treatment apparatus 5m exhausts the atmosphere near the outside of the O-ring 69, thereby preventing diffusion to the outside even if solvent vapors are assumed to leak from the treatment container 6. A plurality of exhaust ports 96 open, for example, along the periphery of the described opening of the partition plate 53 where the lower structure 61 is arranged.

[0118] Furthermore, when the film obtained by the heat treatment disclosed herein is formed from i-line resist, polyimide, etc., a large amount of bubbles can be effectively removed. Therefore, this resist film and polyimide film are preferred, but it can also be applied to other resist films with fewer bubbles. In addition, this film is not limited to the case formed by spin coating, but can also be applied to the case formed using a slit-shaped nozzle without rotating the wafer W.

[0119] Furthermore, in the heat treatment of this disclosure, the wafer W is heated at a fixed set temperature below the boiling point of the solvent, but this is not limited to this; the set temperature can also be appropriately varied. Specifically, after temporarily heating the wafer W at a temperature above the boiling point of the solvent to evaporate the solvent and form a solvent atmosphere, the heating performed by the hot plate 62 can be weakened to a temperature below the boiling point, thereby removing bubbles without curing the resist film. Moreover, in the heat treatment of this disclosure, when the processing space 6A is replaced with an atmospheric atmosphere by supplying and exhausting air, heating is also performed at a fixed set temperature, but the heating performed by the heater 65 can also be weakened.

[0120] The hot plate is not limited to a heater 65 as a heating element; for example, it could be a structure with an internal flow path for the heated fluid to circulate. Alternatively, it could be a device structure that heats the wafer W by irradiating light from below the wafer W, which is mounted on a mounting portion that only supports the back side of the wafer W, using an LED as a heating element. Therefore, it is not limited to the case where the mounting portion of the wafer W is a hot plate. Furthermore, in the case of heating by an LED, the heating period of the wafer W coincides with the period during which light is irradiated onto the wafer W. Air is supplied to the gas supply unit 88, but for example, an inactive gas may also be supplied.

[0121] Furthermore, the wafer processing system in this disclosure is not limited to the structure and operation described above. The substrate processed by each wafer processing system is not limited to wafer W, but may also be an FPD (flat panel display) substrate or a mask substrate used to fabricate an exposure mask. Moreover, the embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, modified, and combined in various ways without departing from the appended claims and their spirit.

[0122] Explanation of reference numerals in the attached figures

[0123] R: resist film; W: wafer; 62: hot plate; 65: heater.

Claims

1. A heat treatment apparatus characterized by comprising: Possessing: a placement portion on which a substrate is placed before a film formed on the substrate is cured; and a heating portion that heats the substrate placed on the placement portion at a temperature lower than a boiling point of a solvent contained in the film.

2. The heat treatment apparatus according to claim 1, wherein Further possessing: a processing container that forms a processing space in a manner of surrounding the placement portion, is closed during heating of the substrate by the heating portion, and has an exhaust port; and an exhaust portion that exhausts the processing space from the exhaust port so that a concentration of the solvent in the processing space at a second time point later than a first time point during the heating is higher than a concentration of the solvent in the processing space at the first time point during the heating.

3. The heat processing apparatus according to claim 1 or 2, wherein the film is a film formed by supplying a liquid containing an i-line exposure resist or a polyimide to a substrate, the liquid having a viscosity of 50 cP to 10,000 cP before being supplied to the substrate.

4. The heat processing apparatus according to claim 3, wherein the film is formed in contact with a pattern having a step formed on the substrate.

5. The heat processing apparatus according to claim 3, wherein the film is a laminated film in which a plurality of films of the same kind are overlapped.

6. The heat processing apparatus according to claim 1 or 2, wherein when the heating portion is a first heating portion, the substrate is a substrate heated by a second heating portion for removing the solvent at a conveyance destination conveyed from the placement portion, the first heating portion heats the substrate at a temperature lower than a heating temperature of the substrate by the second heating portion.

7. The heat treatment apparatus according to claim 1 or 2, wherein Further possessing: a processing container that forms a processing space in a manner of surrounding the placement portion, is closed during heating of the substrate by the first heating portion, and has an exhaust port and a gas supply port; an exhaust portion that exhausts the processing space from the exhaust port so that a first exhaust amount exhausted from the exhaust port during a first period of a half or more of the heating period is smaller than a second exhaust amount exhausted from the exhaust port during a second period after the first period during the heating period; and a gas supply portion that supplies a gas to the processing space from the gas supply port during the second period to replace an atmosphere of the processing space from an atmosphere of the solvent to an atmosphere of the gas.

8. The heat processing apparatus according to claim 7, wherein the exhaust portion exhausts the processing space from the exhaust port during a period including the second period and a period before the substrate is conveyed into the processing container.

9. The heat processing apparatus according to claim 7, wherein the placement portion is a hot plate that has a heater as the heating portion, the gas supply port opens to an outside of the hot plate in plan view, the exhaust port is located at a position closer to a center portion of the hot plate than the gas supply port and opens toward a peripheral portion of the hot plate in plan view.

10. The heat processing apparatus according to claim 8, wherein The placement portion is a hot plate provided with a heater as the heating portion, The gas supply port opens to the outside of the hot plate when viewed from above, The exhaust port is located at a position closer to the center portion of the hot plate than the gas supply port and opens toward the peripheral portion of the hot plate when viewed from above.

11. The heat treatment apparatus according to claim 7, wherein The placement portion is a hot plate provided with a heater as the heating portion, A support ring that surrounds the hot plate and is connected to the hot plate is provided at a position facing the gas supply port.

12. The heat treatment apparatus according to claim 8, wherein The placement portion is a hot plate provided with a heater as the heating portion, A support ring that surrounds the hot plate and is connected to the hot plate is provided at a position facing the gas supply port.

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