Substrate processing method, substrate processing apparatus and computer storage medium

Abstract

To obtain an excellent pattern of metal-containing resist.SOLUTION: There is provided a substrate processing method that includes a process of developing a substrate which has a coating of metal-containing resist formed and is subjected to exposure processing and heating processing after the exposure processing, and the developing process includes a process of exposing the substrate being heated to an acid atmosphere containing at least one of a weak acid gas and a mist.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a substrate processing method, a substrate processing apparatus, and a computer storage medium. [Background technology]

[0002] Patent Document 1 discloses a developing method for developing a substrate, which includes a step of supplying a developer containing an organic solvent to the substrate on which a metal-containing coating film has been exposed to a predetermined pattern. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-96081 Summary of the Invention [Problem to be solved by the invention]

[0004] The techniques of the present disclosure provide good patterns of metal-containing resists. [Means for solving the problem]

[0005] One aspect of the present disclosure is a substrate processing method including a step of developing a substrate on which a metal-containing resist film has been formed and which has been subjected to an exposure process and a heat treatment after the exposure process, wherein the developing step includes a step of exposing the substrate to an acid atmosphere, which is an atmosphere containing at least one of a weak acid gas and a weak acid mist, while heating the substrate. [Effects of the Invention]

[0006] According to the present disclosure, good patterns of metal-containing resists can be obtained. [Brief explanation of the drawings]

[0007] [Figure 1]1 is a plan view schematically showing an outline of the configuration of a wafer processing system as a substrate processing apparatus according to an embodiment of the present invention. [Figure 2] 1 is a front view schematically showing an outline of the configuration of a wafer processing system as a substrate processing apparatus according to an embodiment of the present invention. [Figure 3] FIG. 2 is a vertical cross-sectional view schematically illustrating the configuration of a development unit. [Figure 4] FIG. 2 is a bottom view schematically illustrating the configuration of the upper chamber. [Figure 5] 10 is a flowchart showing main steps of a first example of a processing sequence. [Figure 6] 4 is an explanatory diagram showing the operation of the development unit of FIG. 3. [Figure 7] FIG. 10 shows the results of developing a metal-containing resist to form a pillar pattern. [Figure 8] FIG. 10 shows the results of developing a metal-containing resist to form a pillar pattern. [Figure 9] FIG. 10 shows the results of developing a metal-containing resist to form a pillar pattern. [Figure 10] FIG. 10 shows the results of development to form a line and space pattern of a metal-containing resist. [Figure 11] FIG. 10 shows the results of development to form a line and space pattern of a metal-containing resist. [Figure 12] FIG. 10 shows the results of development to form a line and space pattern of a metal-containing resist. [Figure 13] FIG. 10 shows the results of etching using a line and space pattern of a metal-containing resist as a mask. DETAILED DESCRIPTION OF THE INVENTION

[0008] In photolithography, a manufacturing process for semiconductor devices, etc., a series of processes is performed to form a desired resist pattern on a substrate such as a semiconductor wafer (hereinafter referred to as a "wafer"). The series of processes includes, for example, a resist coating process in which a resist solution is supplied onto the substrate to form a resist coating (hereinafter referred to as a "resist film"), an exposure process in which the resist film is exposed to light in a predetermined pattern, a PEB (Post Exposure Bake) process in which the substrate is heated after exposure in order to promote chemical reactions within the exposed resist film, and a development process in which the substrate after the exposure process is developed to form a resist pattern.

[0009] In the above-mentioned development process, for example, a developer is supplied onto the substrate, a liquid film of the developer is formed on the surface of the substrate, and the substrate is developed. In this case, a cleaning liquid such as pure water may then be supplied onto the substrate, and the substrate may be rotated at high speed to be cleaned.

[0010] Recently, advances in exposure technology and the like have led to further advances in miniaturization of semiconductor devices, i.e., miniaturization of resist patterns. With fine resist patterns, problems can arise if the developer or cleaning solution remains on the substrate during the above-mentioned development process. For example, when the developer or cleaning solution remains between patterns, the surface tension of the remaining developer or cleaning solution can cause so-called pattern collapse.

[0011] Furthermore, while chemically amplified resists have been widely used as resists in the past, non-chemically amplified metal-containing resists have recently been used. These metal-containing resists are expected to be more suitable for forming fine patterns. However, even when using a metal-containing resist, when a substrate is developed using a processing solution such as a developer to form a fine resist pattern, the pattern may collapse, i.e., pattern collapse, which is a type of defect, may occur.

[0012] Therefore, the technology according to the present disclosure suppresses the occurrence of defects such as pattern collapse and obtains a good pattern of metal-containing resist.

[0013] Hereinafter, a substrate processing method and a substrate processing apparatus according to the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0014] <Wafer processing system> First, the configuration of a wafer processing system as a substrate processing apparatus according to this embodiment will be described. Figures 1 and 2 are a plan view and a front view, respectively, that schematically show the outline of the configuration of wafer processing system 1. In this embodiment, the wafer processing system 1 will be described as an example of a photolithography processing system that performs a resist film forming process and a development process on wafers W.

[0015] 1, the wafer processing system 1 includes a cassette station 2 into which a cassette C containing a plurality of wafers W is loaded and unloaded, and a processing station 3 equipped with a plurality of various processing devices that perform predetermined processing on the wafers W. The wafer processing system 1 has a configuration in which the cassette station 2 and an interface station 4 that transfers the wafers W between the processing station 3 and an exposure device (not shown) adjacent to the opposite side of the processing station 3 are integrally connected. Note that, although two processing stations 3 are installed between the cassette station 2 and the interface station 4 as shown in FIG. 1, one processing station 3 or three or more processing stations may be installed.

[0016] The cassette station 2 is provided with a cassette mounting table 21, a wafer transfer device 22, and a wafer transfer device 23. The cassette mounting table 21 has a plurality of cassette mounting plates 24 arranged in the X direction. The cassette station 2 uses the wafer transfer device 22 or the wafer transfer device 23 to transfer wafers between the cassette C mounted on the cassette mounting table 21 and the processing station 3. To this end, the wafer transfer device 22 and the wafer transfer device 23 are each provided with a drive mechanism for movement in each direction, such as the horizontal direction (X direction and Y direction), the vertical direction (Z direction), and around the vertical axis (θ direction), as needed, and may also be provided with a drive mechanism for movement in all directions. At least one of wafer transfer device 22 and wafer transfer device 23 is capable of transferring wafers W between cassettes C and processing station 3. The transfer of wafers W to and from processing station 3 refers to, for example, transferring wafers between processing station 3 and third block G3, which includes a transfer device accessible by wafer transfer device 33 in processing station 3 (described later). Third block G3 may include multiple transfer devices (not shown) arranged vertically.

[0017] An inspection device (not shown) for inspecting the wafer W may be provided at a position accessible to either the wafer transfer device 22 or the wafer transfer device .

[0018] The processing station 3 is provided with multiple blocks, for example, three blocks G1, G2, and G4 (first, second, and fourth blocks). As shown in FIG. 2, multiple layers 31 each including the first and second blocks G1 and G2 are stacked vertically. For example, the first block G1 is provided on the front side of the processing station 3 (the negative X-direction side in FIG. 1), and the second block G2 is provided on the rear side of the processing station 3 (the positive X-direction side in FIG. 1). The fourth block G4 is provided on the interface station 4 side of the processing station 3 (the positive Y-direction side in FIG. 1) or at a connection point with another adjacent processing station 3. The fourth block G4 may include multiple transfer devices arranged vertically. The aforementioned third block G3 may also be provided within the processing station 3.

[0019] The first block G1 includes a plurality of processing devices, such as a patterning film forming device and a development processing device (both not shown). The patterning film forming device may include, for example, a resist film forming device and an anti-reflection film forming device.

[0020] For example, the plurality of processing devices are arranged in a horizontal line in the first block G1. Note that the number, arrangement, and types of these processing devices in the first block G1 can be selected arbitrarily.

[0021] In these patterning film forming apparatuses and developing treatment apparatuses, predetermined processes are performed, for example, by supplying a predetermined processing liquid or a predetermined gas onto the wafer W. In this manner, the patterning film forming apparatus forms a resist film that is used as a mask when forming a pattern on an underlying film, and an anti-reflection film for efficiently performing a light irradiation process, such as an exposure process. Meanwhile, in the developing treatment apparatus, a portion of the exposed resist film is removed to form the uneven shape that serves as the mask.

[0022] For example, in the second block G2, heat treatment devices (not shown) that perform heat treatment such as heating and cooling of the wafer W are arranged in a vertical and horizontal direction. Also, in the second block G2, although neither is shown, a hydrophobization treatment device that performs a hydrophobization treatment to improve the adhesion of the resist liquid to the wafer W, and a peripheral exposure device that exposes the peripheral portion of the wafer W are arranged in a vertical and horizontal direction (Z direction). The number and arrangement of these heat treatment devices, hydrophobization treatment devices, and peripheral exposure devices can also be selected as desired.

[0023] 1, a wafer transfer area 32 is formed in an area sandwiched between a first block G1 and a second block G2 in a plan view. In the wafer transfer area 32, for example, a wafer transfer device 33 is disposed.

[0024] The wafer transfer device 33 has a transfer arm that is movable in, for example, the Y direction, the front-rear direction, the θ direction, and the Z direction. The wafer transfer device 33 moves within the wafer transfer area 32 and can transfer the wafer W to predetermined devices in the surrounding first block G1, second block G2, third block G3, and fourth block G4. When there are multiple processing stations 3 as shown in FIG. 1, the wafer transfer device 33 provided in the processing station 3 located on the interface station 4 side can transfer the wafer W to predetermined devices in the first, second, and fourth blocks G1, G2, and G4, as well as the fifth block G5 described below.

[0025] A plurality of wafer transfer devices 33 are arranged, for example, one above the other. One wafer transfer device 33 can transfer wafers W to a predetermined device located at the height of the upper layers 31 among the multiple layers 31 stacked vertically. Another wafer transfer device 33 can transfer wafers W to a predetermined device located at the height of multiple layers 31 located below the layers 31. A plurality of wafer transfer areas 32 are provided to enable such transfer of wafers W. Note that the number of wafer transfer devices 33 and the number of layers 31 corresponding to one wafer transfer device 33 can be selected arbitrarily, such as by providing a wafer transfer device 33 for each layer 31.

[0026] The wafer transfer area 32, the first block G1, or the second block G2 may also include a shuttle transfer device (not shown). The shuttle transfer device linearly transfers the wafer W between a space adjacent to one side of the processing station 3 and another space adjacent to the opposite side.

[0027] The interface station 4 is provided with a fifth block G5 equipped with a plurality of transfer devices, and a wafer transfer device 41 and a wafer transfer device 42. The interface station 4 uses the wafer transfer device 41 or the wafer transfer device 42 to transfer the wafer W between the fifth block G5, where the wafer W is transferred by the wafer transfer device 33, and the exposure device. To this end, the wafer transfer device 41 and the wafer transfer device 42 are each provided with a drive mechanism for movement in each direction, such as the X direction, the Y direction, the Z direction, and around the vertical axis (the θ direction), as needed, and may also be provided with a drive mechanism for movement in all directions. At least one of the wafer transfer device 41 and the wafer transfer device 42 can support the wafer W and transfer the wafer W between the transfer device in the fifth block G5 and the exposure device.

[0028] A cleaning device for cleaning the surface of the wafer W and the aforementioned peripheral exposure device may be provided in the interface station 4 at a position accessible to either the wafer transfer device 41 or the wafer transfer device 42.

[0029] The inspection device may be provided in the cassette station 2 as described above, but it may also be provided in the processing station 3 and the interface station 4 at a position accessible to any of the wafer transport devices 33, 41, and 42 provided inside each station.

[0030] The wafer processing system 1 described above includes at least one controller 100, as shown in FIG. 1 . The controller 100 processes computer-executable instructions that cause the wafer processing system 1 to perform the various processes described herein. The controller 100 may be configured to control each element of the wafer processing system 1 to perform the various processes described herein. In one embodiment, part or all of the controller 100 may be included in the wafer processing system 1. The controller 100 may include a processor, a memory, and a communication interface. The controller 100 may be implemented, for example, by a computer. The processor may be configured to read from the memory a program that provides logic or routines that enable the various control operations to be performed, and to execute the read program to perform the various control operations. This program may be stored in the memory in advance or may be acquired via a medium when needed. The acquired program is stored in the memory and read from the memory by the processor for execution. The medium may be a variety of computer-readable storage media or a communication line connected to the communication interface. The storage medium may be temporary or non-temporary. The processing unit may be a CPU (Central Processing Unit) or one or more circuits. The storage unit may include a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface may communicate with the wafer processing system 1 via a communication line such as a LAN (Local Area Network).

[0031] It should be noted that the wafer processing system in the present disclosure is not limited to the configuration described above. For example, in the embodiment described above, the wafer processing system is directly connected to the exposure apparatus, and the wafer W is transferred between the interface station 4 and the exposure apparatus. However, the wafer processing system does not have to be directly connected to the exposure apparatus. In that case, for example, the wafer W is transferred from the cassette station 2 to the processing station 3, where it is subjected to the necessary processing, and then transferred back to the cassette station 2 to be removed from the system. Furthermore, among the processing devices listed above, devices that are not required may not be provided in the wafer processing system, or processing may not be performed in those devices.

[0032] <Type of resist> In the wafer processing system 1 of the present disclosure, the resist coating, ie, the resist film, formed on the wafer W by the resist film forming device is a metal-containing resist coating, ie, a metal-containing resist film. The metal contained in the metal-containing resist may be any metal, for example, tin. The metal-containing resist used in the wafer processing system 1 is a negative type.

[0033] <Developing unit 200> Next, a description will be given of the developing unit 200. Fig. 3 is a vertical cross-sectional view that schematically shows the outline of the configuration of the developing unit 200. Fig. 4 is a bottom view that schematically shows the outline of the configuration of an upper chamber 301, which will be described later.

[0034] 3 is provided with a chamber 300 that covers a processing space K on a heating plate 350 (described later) and accommodates a wafer W during heat treatment. The chamber 300 has an upper chamber 301 located on the upper side and a lower chamber 302 located on the lower side that is integrated with the upper chamber 301 and can seal the interior.

[0035] The upper chamber 301 is configured to be able to move up and down freely by an elevation mechanism (not shown). The elevation mechanism has a drive source (not shown) such as a motor that generates a driving force for raising and lowering the upper chamber 301. This elevation mechanism is controlled by the control unit 100.

[0036] The upper chamber 301 is formed, for example, in a substantially cylindrical shape with an open bottom. The upper chamber 301 has a ceiling 310. The ceiling 310 forms a processing space K below and is disposed so as to face a wafer W on a heating plate 350 (described later). The ceiling 310 is also provided with a shower head 311 as a gas discharge unit.

[0037] The showerhead 311 discharges a process gas containing a weak acid gas into the chamber 300. Specifically, the process gas containing a weak acid gas is discharged from the ceiling 310 toward the hot plate 350. The weak acid gas is, for example, a weak carboxylic acid gas. The weak carboxylic acid gas may also be, for example, acetic acid vapor. In this disclosure, the term "weak acid" refers to an acid having an acid strength that does not allow development of a metal-containing resist at room temperature (20°C to 30°C), specifically, an acid with an acid dissociation constant (pka) value of 4 or more (e.g., approximately 5). The process gas containing a weak acid gas may also contain an organic solvent gas. The process gas containing a weak acid gas may, for example, contain a vaporized product of a mixed solution of a weak carboxylic acid and an organic solvent, i.e., vapor, and a carrier gas. The process gas containing a weak acid gas may also contain a vaporized product of a weak carboxylic acid alone and a carrier gas. A specific example of a weak carboxylic acid is acetic acid. The organic solvent is, for example, propylene glycol monomethyl ether acetate (PGMEA), and the carrier gas is, for example, an inert gas such as nitrogen gas or argon (Ar) gas.

[0038] In this embodiment, the shower head 311 also discharges an inert gas such as nitrogen gas or Ar gas into the chamber 300. That is, the shower head 311 also functions as another gas discharge unit that discharges an inert gas into the chamber 300.

[0039] The shower head 311 also has a plurality of outlet holes 312 and a gas distribution space 313 . The outlet holes 312 are formed in the lower surface of the shower head 311. The outlet holes 312 are arranged approximately uniformly in the center of the lower surface of the shower head 311, for example, as shown in FIG. The gas distribution space 313 distributes the gas introduced into the shower head 311 and supplies it to each outlet hole 312. As shown in FIG.

[0040] The supply mechanism 330 supplies a process gas containing a weak acid gas to the showerhead 311 (specifically, the gas distribution space 313). The supply mechanism 330 also includes, for example, a tank 331 that stores a mixed solution of a weak acid carboxylic acid and an organic solvent as a raw material for the weak acid gas, and a supply pipe 332 that supplies a carrier gas to the tank 331. The tank 331 may be provided with a heater (not shown) that heats the mixed solution to promote vaporization of the mixed solution. The mixed solution may also be vaporized by using a carrier gas for bubbling in the tank 331. The supply pipe 332 is provided with a supply device group 333 that includes an on-off valve, a flow rate control valve, and the like that control the flow of the carrier gas.

[0041] The supply mechanism 330 also has an inlet pipe 334 that introduces the treatment gas containing weak acid gas from the tank 331 into the supply pipe 314. The inlet pipe 334 is provided with a group of supply devices 335 including an on-off valve, a flow rate control valve, etc. that control the flow of the treatment gas containing weak acid gas. The supply devices 333 and 335 are controlled by the control unit 100 .

[0042] The supply mechanism 340 has an introduction pipe 341 that introduces the inert gas stored in a storage source (not shown) into the supply pipe 314. The introduction pipe 341 is provided with a supply device group 342 including an on-off valve, a flow rate control valve, etc. that control the flow of the inert gas. The supply equipment group 342 is controlled by the control unit 100 .

[0043] Furthermore, a peripheral exhaust unit 320 is provided on the ceiling unit 310 of the upper chamber 301. The peripheral exhaust unit 320 exhausts air from the ceiling unit 310 above the peripheral portion of the wafer W on the hot plate 350, inside the processing space K. The peripheral exhaust unit 320 has an exhaust port 321. As shown in FIG. 4 , the exhaust port 321 opens downward from the underside of the ceiling unit 310 so as to surround the outer periphery of the shower head 311. The exhaust port 321 may be a plurality of exhaust holes arranged along the outer periphery of the shower head 311. The peripheral exhaust unit 320 exhausts air from the processing space K through the exhaust port 321. The peripheral exhaust unit 320 constitutes an exhaust unit that exhausts air from the chamber 300, i.e., the processing space K.

[0044] The exhaust port 321 is provided, for example, between a position where the peripheral edge of the exhaust port 321 overlaps with the peripheral edge of the wafer W on the heating plate 350 and a position 10 mm inside from that position when viewed from above.

[0045] 3 has a peripheral exhaust path extending from an exhaust port 321. An exhaust device 323 such as a vacuum pump is connected to the peripheral exhaust path via an exhaust pipe 322. An exhaust device group 324 having a valve for adjusting the amount of exhaust is provided in the exhaust pipe 322. The exhaust device 323 and the exhaust device group 324 are controlled by the control unit 100.

[0046] Furthermore, a central exhaust unit may be provided above the center of the wafer W on the heating plate 350 to exhaust the processing space K. In this case, exhaust may be performed from the central exhaust unit at a predetermined timing during the heat treatment process. The exhaust path of the central exhaust unit may be provided, for example, from the upper surface of the ceiling unit 310 to the lower surface of the shower head 311 so as to penetrate the central region of the shower head 311. One or more exhaust ports of the central exhaust unit may be provided on the lower surface of the shower head 311.

[0047] The lower chamber 302 is provided, for example, to surround the periphery of the hot plate 350 (specifically, the sides and below the hot plate 350).

[0048] The hot plate 350 heats the wafer W. The hot plate 350 is configured to be able to support the wafer W. The hot plate 350 has a thick disk shape. The hot plate 350 has a built-in heater 351, for example. The heater 351 is, for example, a resistance heater. The temperature of the hot plate 350 is adjusted by, for example, controlling the heater 351 by the control unit 100, and thereby, for example, the wafer W placed on the hot plate 350 is heated to a predetermined temperature. Furthermore, the heating plate 350 is provided with, for example, a plurality of suction holes (not shown) for suctioning the wafer W onto the heating plate 350.

[0049] The heating plate 350 may be configured to be able to heat the wafer W so that the temperature of the wafer W varies in the radial direction of the wafer W.

[0050] Furthermore, within the lower chamber 302, for example, three lift pins 360 are provided below the heat plate 350 to support and lift the wafer W from below. The lift pins 360 are raised and lowered by a lift mechanism 361. The lift mechanism 361 has a drive source (not shown), such as a motor, that generates a driving force for raising and lowering the lift pins 360. The lift mechanism 361 is controlled by the control unit 100. A through hole 352 through which the lift pins 360 pass is formed in the center of the heat plate 350. The lift pins 360 can pass through the through hole 352 and protrude from the upper surface of the heat plate 350.

[0051] The hot plate 350 is supported, for example, on the bottom wall of the lower chamber 302. Specifically, the hot plate 350 is supported, for example, on the bottom wall of the lower chamber 302 via a support portion 370.

[0052] 1 and 2, the developing treatment device is provided in the first block G1 in the wafer processing system 1. In contrast, the developing unit 200 is provided in the second block G2, for example, in which a heat treatment device having a heating plate or the like similar to the developing unit 200 is located.

[0053] <Processing sequence example 1> Next, a description will be given of an example of a processing sequence executed by the wafer processing system 1. Fig. 5 is a flowchart showing main steps of processing sequence example 1. Fig. 6 is an explanatory diagram showing the operation of the developing unit 200.

[0054] (Step S1) First, the wafer W is loaded into the wafer processing system 1. Specifically, a cassette C containing a plurality of wafers W is carried into cassette station 2 of wafer processing system 1 and placed on cassette mounting plate 24. Next, wafer transfer device 22 or 23 sequentially removes each wafer W from cassette C and transfers them to a transfer device in third block G3.

[0055] (Step S2) Next, the wafer W is subjected to an anti-reflection film forming process, and an anti-reflection film is formed on the wafer W. Specifically, the wafer W transferred to the transfer device in the third block G3 is supported by the wafer transfer device 33 and transferred to the anti-reflection film forming device provided in the first block G1, where an anti-reflection film is formed as an undercoat film for the metal-containing resist so as to cover the surface of the wafer W. This step S2 may be omitted.

[0056] (Step S3) Next, the wafer W is subjected to a resist coating process, and a metal-containing resist film is formed on the wafer W. Specifically, the wafer W is supported by the wafer transport device 33 and transported to a resist film forming device installed in the first block G1, and a negative metal-containing resist film is formed so as to cover the anti-reflective film serving as an undercoat film on the wafer W.

[0057] (Step S4) Subsequently, the wafer W is subjected to a PAB process. Specifically, the wafer W is supported by the wafer transfer device 33 and transferred to a heat treatment device for PAB treatment in the second block G2, where it is subjected to PAB treatment. Thereafter, the wafer W is transferred to the transfer device in the fifth block G5. Note that, when there are multiple processing stations 3 as shown in FIGS. 1 and 2, the wafer W is temporarily placed in the transfer device in the fourth block G4 before being transferred to the transfer device in the fifth block G5, and then transferred between the multiple wafer transfer devices 33.

[0058] (Step S5) Next, the wafer W is subjected to an exposure process. Specifically, the wafer W transferred to the transfer device in the fifth block G5 is transferred to the exposure device by the wafer transfer device 41 and the wafer transfer device 42, and is exposed to a predetermined pattern. The exposed wafer W is then transferred to the transfer device in the fifth block G5 by the wafer transfer device 41 and the wafer transfer device 42.

[0059] (Step S6) Next, the wafer W is subjected to a PEB process. Specifically, the wafer W transferred to the delivery device in the fifth block G5 after the exposure process is transferred by the wafer transfer device 33 to the heat treatment device for the PEB process, where the PEB process is performed.

[0060] (Step S7) Subsequently, the wafer W is developed (step S7). Specifically, the following steps S7a to S7d are performed.

[0061] (Step S7a) First, the wafer W is loaded into the chamber 300 . Specifically, first, the wafer W is moved into the developing unit 200 by the wafer transfer device 33, and then the lift pins 360 are raised and the transfer arm of the wafer transfer device 33 is withdrawn, and the wafer W is supported by the lift pins 360. Thereafter, the upper chamber 301 is lowered, and the processing space K is defined by the upper chamber 301 and the lower chamber 302. At this time, for example, the wafer W continues to be supported by the lift pins 360 and is spaced from the heating plate 350, as shown in FIG. 6(A). Thereafter, the lift pins 360 supporting the wafer W are lowered, and the wafer W is transferred to and placed on the heating plate 350. The wafer W is then adsorbed to the heating plate 350 via suction holes (not shown).

[0062] (Step S7b) Next, the wafer W is exposed to an acid atmosphere containing gases of a weak acid and an organic solvent while being heated. Specifically, as shown in FIG. 6(B), a process gas containing a weak acid and an organic solvent gas is discharged toward the wafer W from the shower head 311, and the peripheral exhaust unit 320 exhausts the gas. As a result, the wafer W is heated and exposed to an acid atmosphere containing a weak acid gas in the process space K. Specifically, the wafer W is heated and exposed to an acid atmosphere containing a weak acid gas under a predetermined pressure equal to or higher than atmospheric pressure. When the negative metal-containing resist film on the wafer W is exposed to the acid atmosphere, the unexposed portions react with the weak acid gas and become low-molecular-weight compounds. Furthermore, by heating the wafer W, the unexposed portions of the negative metal-containing resist film on the wafer W that have been low-molecular-weight compounds due to the reaction with the weak acid gas sublimate, forming a metal-containing resist pattern. For example, if the weak acid gas is acetic acid gas and the metal-containing resist film contains tin as the metal, tin acetate sublimes. The "atmospheric pressure" is, for example, 670 Torr to 760 Torr. The temperature of the wafer W in step S7b is, for example, the same as that during the PEB process, specifically, 100° C. to 200° C. This step S7b is completed, for example, when a predetermined time has elapsed since the supply of the processing gas started.

[0063] (Step S7c) On the other hand, in this step, the atmosphere around the wafer W is replaced from an acid atmosphere to an inert gas atmosphere. 6(C), for example, without the wafer W being carried out of the chamber 300, the inert gas is supplied from the shower head 311 while the peripheral exhaust unit 320 continues to exhaust the gas. This changes the atmosphere inside the chamber 300 from an acid atmosphere to an inert gas atmosphere. This step S7c is completed, for example, when the supply of the inert gas is stopped after a predetermined time has elapsed since the start of the supply of the inert gas.

[0064] (Step S7d) Thereafter, the wafer W is unloaded from the chamber 300. Specifically, for example, the wafer W is discharged from the chamber 300 and carried out to the outside of the developing unit 200 in the reverse order of step S7a.

[0065] The development conditions can be adjusted depending on the dimensions of the pattern.

[0066] (Step S8) After development, the wafer W is subjected to POST processing. Specifically, the wafer W is transferred by the wafer transfer device 33 to the heat treatment unit 40 for the POST treatment, and the POST treatment is performed. This step S8 may be omitted.

[0067] (Step S9) Then, the wafer W is unloaded from the wafer processing system 1. Specifically, the wafer W is transferred by the wafer transfer device 33 to the transfer device in the third block G3, and then transferred by the wafer transfer device 22 or 23 in the cassette station 2 to the cassette C on the predetermined cassette mounting plate 24. In this way, a series of photolithography steps is completed.

[0068] <Main effects of processing sequence example 1> As described above, in this example, the process of developing the wafer W on which the metal-containing resist film is formed includes a process of exposing the PEB-treated wafer W to an acid atmosphere containing a weak acid gas (specifically, a weak acid and an organic solvent gas) while heating. That is, in this example, the portions of the metal-containing resist film to be removed by development are removed using acetic acid gas and heat without using a developer, cleaning solution, or other treatment, to form a metal-containing resist pattern. Therefore, pattern collapse due to the surface tension of the treatment liquid does not occur. Therefore, according to this example, it is possible to suppress collapse of the metal-containing resist pattern, and therefore it is possible to obtain a good metal-containing resist pattern. Furthermore, in this example, a processing gas containing a weakly acidic gas is used, which can prevent damage to components of the developing unit 200, such as the inner wall of the chamber 300, caused by the processing gas, compared to when a processing gas containing a strongly acidic gas is used.

[0069] Furthermore, in this example, the weak acid in the acid atmosphere has an acid strength that prevents development of the metal-containing resist at room temperature. Therefore, after the development process in step S7 in Example 1 of the above-described processing sequence, when the temperature of the wafer W is at room temperature, development does not proceed, and metal-containing components (e.g., tin acetate, etc.) that are reaction products during development are unlikely to be generated. Therefore, after the development process in step S7 in Example 1 of the above-described processing sequence, contamination of the surroundings of the developed wafer W (e.g., other wafers W located above it in the wafer processing system 1 or cassette C, etc.) with the metal-containing components can be prevented. One possible reason why a weak acid may have such acid strength that development of a metal-containing resist does not proceed at room temperature is that the development involves an acid-base reaction in which the acid breaks bonds. Because a weak acid involves an acid-base reaction, development is weak and it is thought that development does not proceed easily unless heat is applied.

[0070] Furthermore, after the above-described processing sequence, the wafer W is etched using the metal-containing resist pattern as a mask, but before this etching, the periphery of the developed wafer W can be prevented from being contaminated by the above-described metal-containing components.

[0071] <Requirements when the developing gas contains acetic acid and organic solvent vapor (gas)> (1. Spontaneous ignition temperature requirements) For safety reasons, development using a mixed gas of acetic acid and an organic solvent cannot be performed under conditions where the temperature of the processing space K, i.e., the processing temperature, exceeds the spontaneous ignition temperature of the acetic acid or the organic solvent. Furthermore, the spontaneous ignition temperature of organic solvents is generally lower than that of acetic acid (485°C). For example, the spontaneous ignition temperature of PGMEA is 272°C. Therefore, the processing temperature during development using a mixed gas of acetic acid and an organic solvent is limited to the spontaneous ignition temperature of the organic solvent. Therefore, when the processing temperature during development using a mixed gas of acetic acid and an organic solvent is preferable in terms of development performance, an organic solvent with a high spontaneous ignition temperature close to that of acetic acid is preferred.

[0072] (2. Ease of Vaporization Requirements) When a mixed gas of acetic acid and an organic solvent is generated as a developing gas by vaporizing a mixed solution of acetic acid and an organic solvent in a vaporizer, if the vaporizability of the acetic acid and the organic solvent differs, the concentration of the mixed solution in the vaporizer will change, and as a result, the concentration of acetic acid gas in the generated developing gas will also change. This makes it difficult to maintain a constant concentration of acetic acid gas in the developing gas supplied to the processing space K. Therefore, it is preferable that the vaporizability of the acetic acid and the organic solvent be similar. Parameters related to the vaporizability of a liquid include boiling point and vapor pressure. The higher the boiling point of a liquid, the more difficult it is to vaporize, and the lower the boiling point, the more easily it is vaporized. Furthermore, the higher the vapor pressure of a liquid, the more easily it is vaporized, and the lower the vapor pressure, the more difficult it is to vaporize. Furthermore, in the case of a mixed fluid, the vaporizability is proportional to the molar fraction, which is determined by the molecular weight. In other words, molecular weight is also a parameter related to the vaporizability.

[0073] In view of the above two requirements, when producing from a mixed solution of acetic acid and an organic solvent, it is preferable to use an organic solvent that satisfies at least one of the following (A) and (B): (A) The spontaneous ignition temperature is equivalent to that of PGMEA, which is commonly used for substrate processing, or closer to that of acetic acid than PGMEA. (B) It is preferable to use a compound whose boiling point at the same processing pressure, vapor pressure at the same processing temperature, and / or molecular weight is equal to or closer to that of PGMEA than that of acetic acid.

[0074] There are many such organic solvents, some of which include PGMEA, propylene glycol monomethyl ether (PGME), methyl isobutyl carbinol (MIBC), methyl isobutyl ketone (MIBK), butyl acetate (nBA), and γ-butyrolactone. In addition, sulfoxides, sulfones, lactams, polyhydric alcohols, dialkyl glycol ethers, alkylene glycol monoalkyl ethers, and the like can be used. Organic solvents that meet the above requirements may be used, such as alkyl ethers, alkylene glycol esters, alkylene glycol monoalkyl ether acetates, ketones, alkyl lactate esters, other ethers and esters, aliphatic hydrocarbons, aromatic hydrocarbons, and terpenes.

[0075] <Development results> 7 to 9 each show the results of development to form a pillar pattern of metal-containing resist. FIG. 7 shows the relationship between CD (Critical Dimension), i.e., pillar diameter, and defect occurrence rate. FIG. 8 shows the relationship between exposure dose and CD, i.e., exposure sensitivity. FIG. 9 shows the relationship between CD and LCDU (Local CD Uniformity). Note that the defects shown in FIG. 7 are due to pattern collapse. LCDU in FIG. 9 is the variation (2σ) in pillar diameter. 7 to 9 show the results of wet development, dry development, and development according to Example 1 of the above processing sequence (hereinafter referred to as weak acid development), respectively. For wet development, a general developer was used and the development time was 27 seconds. For dry development, hydrogen bromide was used under a reduced pressure atmosphere (approximately 500 mTorr) and the development time was 40 seconds. For weak acid development, the development time (specifically, the time during which weak acid gas was supplied) was 120 seconds. For dry development, an additional PEB treatment was performed after the PEB treatment and before development, whereas for wet development and weak acid development, no additional PEB treatment was performed.

[0076] As shown in FIG. 7, the rate of defect occurrence in weak acid development was lower than that in wet development and was equivalent to that in dry development. Furthermore, as shown in FIG. 8, the exposure sensitivity in weak acid development was equivalent to that in dry development. Furthermore, as shown in FIG. 9, the LCDU, which is an index of surface roughness, was lower with weak acid development than with wet development and dry development.

[0077] 10 to 12 show the results of developing to form a line-and-space pattern of metal-containing resist, with Fig. 10 showing the relationship between CD (i.e., line width) and the defect occurrence rate, Fig. 11 showing the relationship between exposure dose and CD (i.e., exposure sensitivity), and Fig. 12 showing the relationship between CD and uLWR (unbiased line edge roughness). Note that the defects shown in Fig. 10 are caused by pattern collapse and chipping of the upper part of the pattern. 10 to 12 show the results of wet development, dry development, and development according to Example 1 of the above-mentioned processing sequence (hereinafter referred to as weak acid development), respectively. The wet development and dry development here are the same as those for the hole pattern. Unlike the hole pattern, the weak acid development here had a development time (specifically, the time for supplying weak acid gas) of 120 seconds.

[0078] As shown in FIGS. 10 to 12, the development results for forming the line and space pattern were similar to those for forming the pillar pattern.

[0079] These results demonstrate that weak acid development makes it possible to form metal-containing resist hole patterns and line and space patterns with small surface roughness and few defects at an appropriate exposure sensitivity.

[0080] One possible reason why weak acid development takes longer for hole patterns than for line-and-space patterns is the following. Specifically, when the metal-containing resist in the unexposed areas is decomposed into smaller molecules by reaction with the weak acid gas (specifically, acid-base), by-products (gases) are generated. These by-products react with the weak acid gas and inhibit the reaction between the metal-containing resist in the unexposed areas and the weak acid gas, i.e., development. Hole patterns have more unexposed areas than line-and-space patterns, and therefore generate a larger amount of the above-mentioned by-products. Therefore, the reaction between the metal-containing resist in the unexposed areas and the weak acid gas, i.e., development, is significantly inhibited by the by-products. This is one possible reason why weak acid development takes longer for hole patterns.

[0081] The present inventors have also confirmed that weak acid development can produce a rectangular pattern in cross section when no additional PEB treatment is performed.

[0082] <Etching using a metal-containing resist pattern as a mask> Fig. 13 shows the results of etching using a line-and-space pattern of metal-containing resist as a mask, and shows the occurrence rate of defects (specifically, bridge defects) when wet development, dry development, and weak acid development were performed. The processing conditions for wet development, dry development, and weak acid development were the same as those when the results of Figs. 10 to 12 were obtained. As shown in FIG. 13, with weak acid development, the rate of defects occurring in etching after development was lower than with wet development and was equivalent to that with dry development.

[0083] <Processing sequence example 2> This example differs from Processing Sequence Example 1 in the development step of step S7. In Processing Sequence Example 1, the step of exposing to an acid atmosphere while heating in step S7b and the step of replacing the atmosphere with an inert gas in step S7c were each performed once. On the other hand, in this example, in the development step, the step of exposing to an acid atmosphere while heating in step S7b is performed multiple times, with the step of replacing the atmosphere with an inert gas in step S7c sandwiched between them. According to this, the replacement step of step S7c removes the by-products located above and near the unexposed area in the immediately preceding step S7b, thereby preventing the by-products from interfering with development in the immediately following step S7b and allowing development to proceed appropriately. Therefore, development can proceed sufficiently in a relatively short development time. This example is particularly preferable when developing to form a hole pattern.

[0084] <Processing sequence example 3> In this example, the developing step in step S7 is different from process sequence example 1. In this example, in the developing step, before steps S7a to S7d, wet development, i.e., development with a developer, is performed by developing unit 200 so that a part of the portion of the metal-containing resist film to be removed by development remains.

[0085] When a developer is used, development proceeds faster than when a weak acid gas is used, so according to this example, the time required for development can be shortened.

[0086] <Modification> Components of the wafer processing system 1 may be omitted as appropriate depending on the processing sequence performed by the wafer processing system 1. In other words, when the wafer processing system 1 performs only a part of the example processing sequences described above, components of the wafer processing system 1 that are not used in the processing sequence may be omitted.

[0087] In the above examples, the acid atmosphere contains both a weak acid component (specifically, a weak acid gas) and an organic solvent component (specifically, an organic solvent gas), but as long as it contains a weak acid component, it does not have to contain an organic solvent component.

[0088] In the above examples, the acid atmosphere contains a weak acid gas as the weak acid component, but it may contain a weak acid mist instead of the weak acid gas. The acid atmosphere may contain both a weak acid gas and a weak acid mist as the weak acid component. However, it is preferable that the acid atmosphere contains a weak acid gas as the weak acid component, rather than a weak acid mist, because this results in a more uniform development result within the surface of the wafer W.

[0089] The acid atmosphere may contain an organic solvent mist as the organic solvent component instead of an organic solvent gas. The acid atmosphere may contain both an organic solvent gas and an organic solvent mist as the organic solvent component. However, it is preferable that the acid atmosphere contains an organic solvent gas as the organic solvent component, rather than an organic solvent mist, because this results in a more uniform development result within the surface of the wafer W.

[0090] In order to prevent weak acid gases and the like from reaching the back surface of the wafer W, the developing unit 200 may be provided with a structure that forms a flow of inert gas along the back surface of the wafer W toward the peripheral edge.

[0091] After the weak acid development and before etching using the pattern obtained by the weak acid development as a mask, plasma treatment may be performed on the wafer W. This plasma treatment is performed, for example, in an etching apparatus that performs the above-mentioned etching.

[0092] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. For example, the components of the above-described embodiments may be arbitrarily combined. Such an arbitrary combination naturally provides the functions and effects of each of the components involved in the combination, and also provides other functions and effects that are apparent to those skilled in the art from the description of this specification.

[0093] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0094] Note that the following configuration examples also fall within the technical scope of the present disclosure. (1) a step of developing a substrate on which a metal-containing resist film has been formed and which has been subjected to an exposure treatment and a post-exposure heat treatment, A substrate processing method, wherein the developing step includes a step of exposing the substrate to an acid atmosphere, which is an atmosphere containing at least one of a weak acid gas and a weak acid mist, while heating the substrate. (2) The substrate processing method according to (1), wherein the weak acid has an acidity such that development of the metal-containing resist does not proceed at room temperature. (3) The substrate processing method according to (1) or (2), wherein the developing step is a step of replacing the atmosphere around the substrate from the acid atmosphere with an inert gas atmosphere, and the step of exposing while heating is repeated multiple times. (4) A substrate processing apparatus for processing a substrate, a developing unit for developing the substrate; a control unit, The developing unit comprises: a chamber for housing a substrate; a hot plate for heating the substrate within the chamber; a gas discharge unit that discharges at least one of weak acid gas and mist into the chamber, the control unit controls the substrate processing apparatus to execute a process of developing the substrate on which a metal-containing resist film has been formed and which has been subjected to an exposure process and a heat treatment after the exposure process; The developing step includes a step of exposing, while heating, the substrate that has been subjected to the heat treatment after the exposure treatment to an acid atmosphere that contains at least one of a gas and a mist of the weak acid. (5) The substrate processing apparatus according to (4), wherein the weak acid has an acidity such that development of the metal-containing resist does not proceed at room temperature. (6) The developing unit further includes another gas discharge unit that discharges an inert gas into the chamber, The substrate processing apparatus according to (14) or (5), wherein the developing step is performed by repeating the heating and exposing step multiple times, with an intervening step of replacing the atmosphere around the substrate from the acid atmosphere with an inert gas atmosphere. (7) A readable computer storage medium storing a program that runs on a computer of a control unit that controls a substrate processing apparatus so as to cause the substrate processing apparatus to execute a substrate processing method, The substrate processing method includes a step of developing a substrate on which a metal-containing resist film has been formed and which has been subjected to an exposure process and a heat treatment after the exposure process, A computer storage medium, wherein the developing step includes exposing the substrate to an acid atmosphere, the acid atmosphere containing at least one of a gas and a mist of a weak acid, while heating the substrate. [Explanation of symbols]

[0095] 1. Wafer Processing System 100 control section 200 Development Unit 311 shower head 350 Hot plate H storage medium W wafer

Claims

1. a step of developing a substrate on which a metal-containing resist film has been formed and which has been subjected to an exposure treatment and a post-exposure heat treatment, A substrate processing method, wherein the developing step includes a step of exposing the substrate to an acid atmosphere, which is an atmosphere containing at least one of a weak acid gas and a weak acid mist, while heating the substrate.

2. 2. The substrate processing method according to claim 1, wherein the weak acid has an acid strength such that development of the metal-containing resist does not proceed at room temperature.

3. 3. The substrate processing method according to claim 1, wherein the developing step includes a step of replacing the acid atmosphere around the substrate with an inert gas atmosphere, and the step of exposing the substrate while heating is performed multiple times with the step of replacing the acid atmosphere around the substrate with an inert gas atmosphere in between.

4. A substrate processing apparatus for processing a substrate, a developing unit for developing the substrate; a control unit, The developing unit comprises: a chamber for housing a substrate; a hot plate for heating the substrate within the chamber; a gas discharge unit that discharges at least one of weak acid gas and mist into the chamber, the control unit controls the substrate processing apparatus to execute a process of developing the substrate on which a metal-containing resist film has been formed and which has been subjected to an exposure process and a heat treatment after the exposure process; The developing step includes a step of exposing, while heating, the substrate that has been subjected to the heat treatment after the exposure treatment to an acid atmosphere that contains at least one of a gas and a mist of the weak acid.

5. The substrate processing apparatus according to claim 4 , wherein the weak acid has an acidity that does not allow development of the metal-containing resist to proceed at room temperature.

6. the developing unit further includes another gas discharge unit that discharges an inert gas into the chamber; 6. The substrate processing apparatus according to claim 4, wherein the developing step comprises repeating the step of exposing while heating a plurality of times with an intervening step of replacing the acid atmosphere around the substrate with an inert gas atmosphere.

7. A readable computer storage medium storing a program that runs on a computer of a control unit that controls a substrate processing apparatus so as to cause the substrate processing apparatus to execute a substrate processing method, The substrate processing method includes a step of developing a substrate on which a metal-containing resist film has been formed and which has been subjected to an exposure process and a heat treatment after the exposure process, A computer storage medium, wherein the developing step includes exposing the substrate to an acid atmosphere, the acid atmosphere containing at least one of a weak acid gas and a weak acid mist, while heating the substrate.

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