Substrate drying device and substrate drying method

Abstract

[Problem] To provide a substrate drying device in which variation in temperature between a plurality of substrates is small and drying on surfaces of the substrates proceeds uniformly. [Solution] A substrate drying device (10) comprises: a treatment tank (20) for storing a treatment liquid (R); a first substrate holding mechanism (30) which is provided within the treatment tank, capable of holding a plurality of substrates (W) aligned such that substrate faces are parallel to each other, and capable of moving up and down in the treatment tank; a drying space (40) formed above the treatment tank; a second substrate holding mechanism (50) which is provided within the drying space, capable of holding the plurality of substrates, and capable of moving up and down in the drying space; and a heating mechanism (60) which is provided within the drying space and equipped with a plurality of rod-like heating members (61) that are aligned so as to be capable of being positioned in the gaps between the plurality of substrates held by the second substrate holding mechanism.

Description

Substrate drying apparatus and substrate drying method

[0001] The present invention relates to an apparatus and method for removing semiconductor wafer substrates, flat panel display (FPD) substrates, etc. from a processing solution and drying them after cleaning.

[0002] In the manufacture of semiconductor devices, FPDs, and other devices, many processes are performed to form circuits and patterns on substrate surfaces. Before and after each process, cleaning with various chemicals, cleaning with pure water, and drying are performed. One drying method is known to involve a substrate drying device, in which a substrate is immersed in heated pure water for cleaning, and then slowly removed from the water to dry it. The water on the substrate surface that is removed by gravity flows down and evaporates. If the substrate surface does not dry uniformly during this process, watermarks (drying marks) can occur, causing various defects in subsequent processes.

[0003] Patent Document 1 describes a substrate processing apparatus that includes an inner tank filled with a cleaning solution, a chamber connected to the top of the inner tank and having a space for containing a substrate, through which a drying gas circulates, and a heat source made of an optically transparent material and disposed outside the chamber, which radiates infrared rays, and that quickly dries a substrate that has been lifted from the inner tank into the chamber.

[0004] Patent Document 2 describes a substrate drying apparatus that dries a substrate as it is lifted out of a processing liquid, the apparatus comprising: a processing tank that stores the processing liquid; a substrate holding mechanism that holds the substrate; a lifting mechanism that raises and lowers the substrate holding mechanism between the inside of the processing liquid and a drying space formed above the processing liquid; and a blower mechanism that blows hot air that is hotter than the processing liquid from an outlet toward the drying space. The patent document also describes that the hot air increases the temperature of the upper portion of the meniscus along the surface of the substrate lifted into the drying space, reducing surface tension, generating convection along the meniscus surface from the substrate side toward the processing tank, thereby suppressing adhesion of moisture to the substrate; and that this promotes evaporation of moisture attached to the substrate even for thin substrates with little heat storage capacity, thereby enabling the substrate to be dried quickly.

[0005] Patent No. 6458123 JP 2021-145043 A

[0006] However, the apparatus described in Patent Document 1 has the problem of low energy efficiency because the entire atmosphere in the chamber is heated by the heat source. Also, the difference in the amount of infrared light irradiated on each substrate results in large temperature variations among multiple substrates, which causes the drying progress to vary uniformly among the substrates, making it necessary to match the lifting speed to the substrate that dries the slowest.

[0007] In the device described in Patent Document 2, warm air is blown diagonally downward into the drying space, which disturbs the surface of the processing liquid, causing variations in the height of the meniscus formed on the substrate surface, resulting in uneven drying of the substrate surface, and there is a concern that watermarks may become more likely to occur.

[0008] The present invention has been made in consideration of the above, and aims to provide a substrate drying apparatus and a substrate drying method in which temperature variation among multiple substrates is small and drying progresses uniformly on the surface of each substrate.

[0009] The substrate drying apparatus of the present invention comprises a processing tank for storing a processing liquid, a first substrate holding mechanism that is provided within the processing tank and is capable of holding a plurality of substrates aligned with their substrate surfaces parallel to one another and that can be raised and lowered within the processing tank, a drying space formed above the processing tank, a second substrate holding mechanism that is provided in the drying space and is capable of holding the plurality of substrates and is capable of being raised and lowered within the drying space, and a heating mechanism that is provided in the drying space and has a plurality of heating members aligned so that they can be positioned in each gap between the plurality of substrates held by the second substrate holding mechanism.

[0010] In the substrate drying apparatus, the second substrate holding mechanism and the heating mechanism are preferably linked and capable of moving up and down within the drying space. More preferably, the second substrate holding mechanism and the heating mechanism are fixedly connected to each other. This simplifies the configuration of the apparatus.

[0011] In any of the above substrate drying apparatuses, the heating member is preferably a heater, more preferably a rod-shaped heater, or preferably a heating pipe through which a heated fluid flows.

[0012] In any of the above substrate drying apparatuses, the processing liquid is preferably pure water.

[0013] The substrate drying method of the present invention includes the steps of holding a plurality of substrates aligned with their substrate surfaces parallel to one another with a first substrate holding mechanism, immersing the substrates in a processing liquid, and then raising the first substrate holding mechanism within the processing liquid to insert each of the plurality of substrates into each gap between a plurality of parallel-aligned rod-shaped heating members provided in a heating mechanism provided in a drying space formed above the processing liquid; holding the plurality of substrates with a second substrate holding mechanism provided in the drying space; and raising the second substrate holding mechanism and the heating mechanism within the drying space.

[0014] According to the substrate drying apparatus or method of the present invention, a heating element is inserted into each gap between multiple substrates aligned parallel to each other, heating the substrates on both sides of the heating element from close range, thereby minimizing temperature variations between the substrates. Furthermore, since only the area necessary for drying is heated, energy efficiency is high. Furthermore, since heating is performed by radiation from the rod-shaped heating element, the processing liquid surface is not disturbed, meniscus height variations are suppressed, and drying can proceed uniformly on the surface of each substrate.

[0015] Fig. 3 is a diagram showing the configuration of a substrate drying apparatus of an embodiment, and is a cross-sectional view taken along the line FF in Fig. 2. Fig. 4 is a diagram showing the configuration of a substrate drying apparatus of an embodiment, and is a cross-sectional view taken along the line SS in Fig. 1. A to D: diagrams for explaining a substrate drying method of an embodiment. Diagrams for explaining heating of a wafer by a heating member.

[0016] An embodiment of the substrate drying apparatus and method of the present invention will be described using the drying of semiconductor wafers after cleaning as an example.

[0017] 1 and 2, the substrate drying apparatus 10 of this embodiment is an apparatus that immerses a plurality of wafers W aligned with their substrate surfaces parallel to one another in a processing liquid R and then dries the wafers while lifting them out of the processing liquid.

[0018] The substrate drying apparatus 10 has a processing tank 20 for storing processing liquid R, a support 30 for holding a wafer W in the processing tank, a drying space 40 formed above the processing tank, a chuck 50 for holding the wafer in the drying space, and a heater unit 60 for heating the wafer in the drying space.

[0019] In this embodiment, a case where a semiconductor wafer is cleaned and dried will be described, but the type of substrate is not limited to this, and it may be a substrate for an FPD, for which watermarks are also a problem.

[0020] The processing tank 20 comprises a main tank 21 and an auxiliary tank 22 that surrounds the upper end of the main tank. The main tank 21 has a roughly rectangular parallelepiped shape. The main tank 21 stores processing liquid R, and wafers W are immersed in the processing liquid stored in the main tank for cleaning. The auxiliary tank 22 receives the processing liquid that overflows from the main tank 21 and discharges it from the bottom.

[0021] The type of processing liquid R is not particularly limited. The substrate drying apparatus 10 can be used for drying after cleaning with various processing liquids. Generally, after cleaning with various processing liquids, cleaning with pure water is performed to remove the processing liquid. With the substrate drying apparatus 10 of this embodiment, even after cleaning using only pure water without using an organic solvent, heating the wafer generates convection on the meniscus surface from the wafer side toward the processing bath, as described below, and the wafer surface can be dried uniformly from top to bottom. For this reason, the substrate drying apparatus 10 is particularly suitable for drying after cleaning with pure water.

[0022] A support 30 is provided within the main tank 21 of the processing tank 20. The support 30 supports and holds a plurality of aligned wafers W from below. The plurality of wafers are aligned upright at a fixed interval, with the surfaces of adjacent wafers facing each other and parallel to each other. The interval between the wafers is, for example, 5 to 20 mm.

[0023] The pedestal 30 includes, for example, three cylindrical support members 31. The three support members 31 are arranged parallel to one another with the longitudinal direction perpendicular to the wafer surface. The three support members 31 are provided with circumferential V-grooves at the same positions in the longitudinal direction to match the spacing between the wafers. This allows the peripheral edge of each wafer to fit into the grooves provided in the three support members, stabilizing the wafers in an upright position. The pedestal 30 can be made of quartz glass or a heat-resistant and chemical-resistant polymer material such as polyether ether ketone. Note that the structure of the pedestal is not limited to this, and any structure can be used as long as it can hold aligned wafers in an upright position.

[0024] The receiving stand 30 can be raised and lowered within the main tank 21 of the processing tank 20 by an elevation mechanism 32. When the processing liquid R is stored in the main tank 21, the receiving stand 30 rises and falls within the processing liquid and does not rise above the surface of the processing liquid, in order not to disturb the surface of the processing liquid.

[0025] A drying space 40 is formed above the processing bath 20. The drying space 40 is formed to have a size capable of accommodating the wafer W pulled up from the processing liquid R.

[0026] A chuck 50 is provided in the drying space 40. The chuck 50 holds a plurality of aligned wafers W. The chuck 50 is disposed directly above the pedestal 30 so that the wafers can be transferred between the chuck 50 and the pedestal 30.

[0027] The chuck 50 includes, for example, four cylindrical support members 51. Each of the four support members 51 has a circumferential V-groove at the same longitudinal position to match the spacing between the wafers. The four support members 51 are arranged two on each side of the wafer (left and right in FIG. 1 ), with the longitudinal direction perpendicular to the wafer surface. Each pair of support members 51 on the same side of the wafer is supported at both ends by a pair of arms 52. The arms 52 are connected to an arm opening / closing mechanism 53 at their base ends, with the base ends facing up. The arm opening / closing mechanism 53 rotates the arms around their base ends, slightly opening and closing the arms on both sides of the wafer, allowing the support members 51 to clamp and hold the peripheral edge of the wafer or release the wafer. The chuck 50 can be made of quartz glass or a heat-resistant polymer material such as polyether ether ketone. The chuck structure is not limited to this; any structure capable of holding aligned wafers in an upright position and transferring them to and from the pedestal 30 may be used.

[0028] The chuck 50, including the support member 51, the arm 52, and the arm opening / closing mechanism 53, is supported in a suspended state by a chuck hanging member 54. The chuck 50, together with the chuck hanging member 54, can be raised and lowered within the drying space 40 by a lifting mechanism (not shown). The speed at which the wafer W is lifted from the processing bath 20 is 0.5 to 4 mm / sec, and at that time, the chuck 50 is raised and lowered only within the drying space 40 and does not come into contact with the surface of the processing liquid. This is to avoid disturbing the surface of the processing liquid.

[0029] A heater unit 60 is provided within the drying space 40. The heater unit 60 heats the wafer. The heater unit 60 includes multiple rod-shaped heaters 61 aligned at the same intervals as the wafers, with the longitudinal direction parallel to the horizontal direction of the wafer surface. The heater 61 has a heating element inside a tube and heats the surrounding area by radiation.

[0030] Both ends of each heater 61 are connected to and supported by heater terminal boxes 62, which are disposed on both sides of the wafer and extend in a direction perpendicular to the wafer surface. The heater terminal boxes 62 are connected to and supported by the arm opening / closing mechanism 53 of the chuck 50 via piping 63. The heaters 61 are supplied with power through electric wires disposed within the piping 63.

[0031] By aligning the heaters 61 parallel to the wafer surface and at the same intervals as the wafers, the heaters can be inserted into the gaps between the aligned wafers. This allows the heaters to heat the wafers W on both sides from a short distance, resulting in efficient heating. This also eliminates the need to set the heater temperature too high, and abrupt temperature fluctuations can be avoided when controlling the heater on and off. Since the temperature of the processing liquid is 20 to 80°C, the heater temperature is set 20 to 120°C higher than the temperature of the processing liquid. In addition, the distance between the heater surface and the wafer is preferably 0.5 to 4.0 mm, and particularly preferably 0.5 to 3.5 mm, in consideration of temperature transfer and device stability. The same applies to the heating tubes described below.

[0032] Furthermore, by increasing the number of heaters 61 by one more than the number of wafers W, it becomes possible to sandwich the wafers at both ends of the wafer row between two heaters, and all wafers can be heated under approximately the same conditions.

[0033] Heater 61 is preferably an infrared heater. By using an infrared heater, the time required for the heater to heat up can be shortened and the temperature inside substrate drying apparatus 10 is not excessively increased. The heater diameter is preferably 2 to 8 mm, and more preferably 3 to 7 mm.

[0034] In this embodiment, the heater unit 60 and the chuck 50 are linked, and they move up and down in unison. The heater unit and the chuck do not necessarily need to move up and down in unison; they may move up, down, and down independently. However, allowing the heater unit and the chuck to move up and down independently would complicate the overall structure of the substrate drying apparatus 10 to prevent interference between their respective support mechanisms and lifting mechanisms. Therefore, the heater unit and the chuck are preferably linked and move up and down in unison, and more preferably are linked. Since disturbing the processing liquid surface is undesirable, it is preferable that the heater unit does not touch the processing liquid surface, just as it is preferable that the chuck does not touch the processing liquid surface. If the heater unit moves up and down in unison with the chuck, it would be difficult to position the heater unit near the processing liquid surface, i.e., near the bottom edge of the wafer. However, when the heater heats the wafer surface, the heat is transferred from top to bottom of the wafer toward the meniscus, ultimately heating the meniscus.

[0035] Alternatively, instead of the heater unit 60, a heating tube unit including heating tubes as heating members may be used as a mechanism for heating the wafer W. The heating tube unit includes multiple rod-shaped heating tubes aligned at the same intervals as the wafers, with the longitudinal direction parallel to the horizontal direction of the wafer surface. The heating tubes are heated by the flow of a heated fluid through the tubes, and the exterior of the tubes is heated by radiation from the surface of the heating tubes. Liquids such as hot water or gases such as air or nitrogen can be suitably used as the fluid. While a heater requires output control, such as on / off control, when heating tubes are used, the temperature of the tubes rises to the temperature of the fluid flowing through the tubes and stabilizes, eliminating the need for on / off control and resulting in a more stable wafer temperature. When heating tubes are used, a mechanism for introducing and discharging the fluid is provided instead of a power supply mechanism.

[0036] Next, the substrate drying method of this embodiment will be described. The reference numerals of the various components are the same as those in FIGS.

[0037] First, with the main tank 21 of the processing tank 20 filled with the processing liquid R, the aligned wafers W are placed and held on the pedestal 30, and the entire wafers are immersed in the processing liquid R for cleaning. After the cleaning is completed, the pedestal 30 holding the wafers W begins to rise. At this time, the arms 52 of the chuck 50 are opened, the chuck is lowered to its lowest position within the drying space 40, and power is started to be applied to the heater 61 (FIG. 3A).

[0038] As the pedestal 30 rises, the wafer moves from its upper end above the surface of the processing fluid until the top of the wafer enters the gap of the heater 61 (FIG. 3B).

[0039] The pedestal 30 is further raised to its upper limit position, and the arms 52 of the chuck 50 are closed to hold the wafer (FIG. 3C).

[0040] The chuck 50 is raised. At this time, the heater unit 60 connected to the chuck 50 also rises in conjunction with the chuck. The wafer W held by the chuck is released from the pedestal 30 and rises, until the entire wafer is above the surface of the processing liquid and enters the drying space 40. When the drying of the wafer is complete, the heater 61 is turned off (FIG. 3D).

[0041] When a wafer W is rising and partially immersed in the processing liquid ( FIGS. 3B and 3C ), a meniscus of processing liquid forms between adjacent wafers. Referring to FIG. 4 , the processing liquid R (arrow D) pulled up by the wafer W is removed from the wafer surface by gravity flowing downward and evaporating. Because the wafer is heated by the heater 61, heat is transferred from top to bottom across the wafer toward the meniscus M (arrow H). The upper portion of the meniscus experiences a rise in temperature and a decrease in surface tension due to heat transferred from the top of the wafer and, to some extent, heat radiated from the heater. This generates a convection current C on the meniscus surface from the wafer toward the processing bath, allowing the processing liquid to smoothly flow downward. Furthermore, because heat is constantly transferred from top to bottom within the wafer, evaporation is accelerated toward the upper portion of the meniscus. This allows the wafer surface to dry uniformly from top to bottom, reducing the likelihood of watermarks.

[0042] Furthermore, in this embodiment, the wafer W is heated by radiation from the heater 61, so the surface of the processing liquid R is not disturbed and the height of the meniscus formed does not vary.

[0043] The inventors conducted an experiment to confirm the effectiveness of the substrate drying method of this embodiment. Multiple silicon wafers, each 0.8 mm thick and 300 mm in diameter, were aligned at approximately equal intervals and immersed in hot water at 20 to 80°C, then removed from the water. A heater unit and chuck were connected, and a 6 mm diameter near-infrared halogen heater (maximum output 1 kW) was set to a heater tube surface temperature of 150°C and placed in the gaps between the wafers being removed to heat both the front and back surfaces of the wafers. As a result, the wafers were dried smoothly from top to bottom, and the meniscus shape remained stable even during wafer drying.

[0044] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the technical concept thereof.

[0045] REFERENCE SIGNS LIST 10 Substrate drying apparatus 20 Processing tank 21 Main tank 22 Auxiliary tank 30 Receiving table (first substrate holding mechanism) 31 Support member 32 Lifting mechanism 40 Drying space 50 Chuck (second substrate holding mechanism) 51 Support member 52 Arm 53 Arm opening / closing mechanism 54 Chuck hanging member 60 Heater unit (heating mechanism) 61 Heater (heating member) 62 Heater terminal box 63 Piping C Convection of processing liquid on meniscus surface D Flow of processing liquid pulled up by wafer H Heat flow within wafer M Meniscus R Processing liquid W Semiconductor wafer (substrate)

Claims

1. A substrate drying apparatus comprising: a processing tank for storing a processing liquid; a first substrate holding mechanism provided within the processing tank, capable of holding a plurality of substrates aligned with their substrate surfaces parallel to one another and capable of rising and falling within the processing tank; a drying space formed above the processing tank; a second substrate holding mechanism provided in the drying space, capable of holding the plurality of substrates and capable of rising and falling within the drying space; and a heating mechanism provided in the drying space and having a plurality of heating members aligned so as to be positionable in each gap between the plurality of substrates held by the second substrate holding mechanism.

2. The substrate drying apparatus according to claim 1, wherein the second substrate holding mechanism and the heating mechanism are capable of moving up and down within the drying space in cooperation with each other.

3. The substrate drying apparatus according to claim 1, wherein the heating member is a rod-shaped heater.

4. The substrate drying apparatus according to claim 1, wherein the heating member is a heating pipe through which a heated fluid flows.

5. The substrate drying apparatus according to claim 1, wherein the processing liquid is pure water.

6. A method for drying substrates, comprising the steps of: holding a plurality of substrates aligned with their substrate surfaces parallel with a first substrate holding mechanism; immersing the substrates in a processing liquid; raising the first substrate holding mechanism within the processing liquid and inserting each of the plurality of substrates into each gap between a plurality of rod-shaped heating members aligned in parallel provided in a heating mechanism provided in a drying space formed above the processing liquid; holding the plurality of substrates with a second substrate holding mechanism provided in the drying space; and raising the second substrate holding mechanism and the heating mechanism within the drying space.

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