Device for drying a substrate and method for drying a substrate

Abstract

[Task] To provide a device for drying a substrate in which the temperature fluctuations between several substrates are small and the drying process proceeds uniformly on each substrate surface. [Means of Dissolving] Device (10) for drying a substrate, comprising: a processing container (20) which accumulates a processing fluid (R), a first substrate holding mechanism (30) which is provided in the processing container, which can hold several substrates (W) which are aligned with parallel substrate surfaces and can move up and down in the processing container, a drying chamber (40) which is formed above the processing container, a second substrate holding mechanism (50) which is provided in the drying chamber, which can hold several substrates and can move up and down in the drying chamber, and a heating mechanism (60) which is provided in the drying chamber and is equipped with several heating elements (61) which are aligned so that they can be positioned in each gap of the several substrates which are held by the second substrate holding mechanism.

Description

Technical field

[0001] The present invention relates to a device and a method for drying a semiconductor wafer substrate and a flat panel display (FPD) substrate, in which these are lifted out of the processing fluid after cleaning. Background technology

[0002] The fabrication of semiconductor devices and FPDs involves numerous steps to create circuits and patterns on the substrate surface. Before and after each step, cleaning with various chemicals, purified water cleaning, and drying are performed. One drying process involves substrate drying devices that dry cleaned substrates by immersing them in heated purified water and then slowly lifting them out. The water on the surface of the raised substrate is removed by gravity and evaporation. If the drying of the substrate surface is uneven during this step, resulting in water spots (drying spots), these can cause various defects in subsequent steps.

[0003] Patent document 1 describes a device for processing a substrate, comprising: an inner container section filled with a cleaning solution, a chamber section having a space connected to the upper part of the inner container section containing a substrate and in which a drying gas circulates, and a heat source section provided outside the chamber section, which consists of a translucent material and emits infrared rays, whereby the substrate lifted from the inner container section into the chamber section is rapidly dried.

[0004] Patent document 2 describes a device for drying a substrate by lifting the substrate from the processing fluid, comprising: a processing container in which the processing fluid is collected, a substrate holding mechanism that holds the substrate, a lifting mechanism for moving the substrate holding mechanism upwards and downwards between the interior of the processing fluid and a drying chamber formed above the processing fluid, and a blower mechanism that blows hot air, which is hotter than the processing fluid, from the outlet into the drying chamber.The warm air increases the temperature of the upper part of the meniscus along the surface of the substrate lifted into the drying chamber and lowers the surface tension, creating a convection current on the meniscus surface from the substrate side towards the processing container, which can suppress the adhesion of moisture to the substrate, and, even if the substrate is thin and has a low heat storage capacity, the evaporation of the moisture adhering to the substrate can be accelerated, so that the substrate can be dried quickly. Identified documents / patent documents Patent document 1: JP 6458123 B Patent Document 2: JP 2021-145043 A Brief description of the invention Problem to be solved by the invention

[0005] However, the device described in patent document 1 suffers from low energy efficiency, as the entire atmosphere in the chamber is heated by the heat source section. Furthermore, due to the varying amounts of infrared radiation emitted onto the individual substrates, temperature fluctuations between substrates increase, and the drying progress is not equalized between them. Therefore, it is necessary to adjust the lifting speed to the slowest drying substrate.

[0006] In the device described in patent document 2, hot air is blown obliquely downwards into the drying chamber, and it was feared that the surface of the processing fluid would be disturbed and the meniscus height produced on the substrate surface would fluctuate, leading to uneven drying progress on the substrate surface, which could easily result in water stains.

[0007] The present invention was made in view of the above circumstances and aims to provide a device for drying a substrate and a method for drying a substrate in which the temperature fluctuations between several substrates are small and the drying process proceeds uniformly on each substrate surface. Means of solving the task

[0008] The device for drying the substrate of the present invention comprises the following: a processing container which accumulates a processing liquid, a first substrate holding mechanism provided in the processing container which can hold several substrates aligned with parallel substrate surfaces and which can move up and down in the processing container, a drying chamber which is formed above the processing container, a second substrate holding mechanism which is provided in the drying chamber which can hold several substrates and which can move up and down in the drying chamber, and a heating mechanism which is provided in the drying chamber and is equipped with several heating elements which are aligned so that they can be positioned in each gap of the several substrates which are held by the second substrate holding mechanism.

[0009] In the above device for drying a substrate, the second substrate holding mechanism and the heating mechanism can preferably move upwards and downwards in a coupled manner within the drying chamber. More preferably, the second substrate holding mechanism and the heating mechanism are connected and fixed together. This simplifies the design of the device.

[0010] In each of the above-mentioned devices for drying a substrate, the heating element is preferably a heating element, particularly preferably a rod-shaped heating element. Alternatively, the heating element is preferably a heating tube in which a heated fluid circulates.

[0011] In each of the above-mentioned devices for drying a substrate, the processing fluid is preferably pure water.

[0012] The method for drying the substrate of the present invention comprises: a step for holding several substrates aligned with parallel substrate surfaces by a first substrate holding mechanism, immersion in a processing fluid and upward movement of the first substrate holding mechanism in the processing fluid to introduce each substrate of the several substrates into each gap of parallel aligned, several rod-shaped heating elements provided in a heating mechanism provided in a drying chamber formed above the processing fluid, a step for holding the several substrates by a second substrate holding mechanism provided in the drying chamber, and a step for upward movement of the second substrate holding mechanism and the heating mechanism in the drying chamber. Effects of the invention

[0013] According to the substrate drying device or substrate drying method of the present invention, the heating element enters each gap of the multiple substrates, which are aligned with the parallel substrate surfaces, and heats the substrates positioned on both sides of the heating element from a short distance, thus reducing temperature fluctuations between the respective substrates. Furthermore, only the area required for drying is heated, resulting in good energy efficiency. Heating is achieved by radiation from the rod-shaped heating element, so that the surface of the processing fluid is not disturbed, variations in meniscus height are suppressed, and drying can proceed uniformly on the surface of each substrate. Brief explanation of the drawings Fig. Figure 1 shows the design of a device for drying a substrate of one embodiment and is a FF sectional view of Fig. 2. Fig. Figure 2 shows the design of the device for drying the substrate in one embodiment and is a sectional view of Fig. 1. Fig. Figure 3 AD shows views to illustrate a method for drying a substrate of one embodiment. Fig. Figure 4 shows a view illustrating the heating of a wafer by a heating element. Embodiments of the invention

[0014] An embodiment of a device and a method for drying a substrate is explained using the example of drying semiconductor wafers after cleaning.

[0015] With reference to Fig. 1 and Fig. 2 The device 10 for drying the substrate of the present embodiment is a device for drying several wafers W which are aligned with the parallel substrate surfaces while they are lifted out of the processing fluid after they have been immersed in a processing fluid R.

[0016] The device 10 for drying the substrate comprises the following: a processing container 20 in which the processing liquid R is collected, a receiving table 30 for holding the wafer W in the processing container, a drying chamber 40 formed above the processing container, a chuck 50 for holding the wafer in the drying chamber, and a heating unit 60 for heating the wafer in the drying chamber.

[0017] The present embodiment describes a case in which semiconductor wafers are cleaned and dried, but the type of substrate is not limited to this and can also be a substrate for FPDs, etc., where water stains are also a problem.

[0018] The processing vessel 20 consists of a main vessel 21 and an auxiliary vessel 22, which surrounds the upper end of the main vessel. The main vessel 21 has a substantially cuboid shape. The main vessel 21 collects the processing fluid R, and the wafer W is immersed in the processing fluid collected in the main vessel for cleaning. The auxiliary vessel 22 receives the overflowing processing fluid from the main vessel 21 and drains it from the bottom.

[0019] The type of processing fluid R is not limited. The device 10 for drying the substrate can be used for drying after cleaning with various processing fluids. Generally, after cleaning with different processing fluids, rinsing with pure water is carried out to remove the processing fluids. In the device 10 for drying the substrate of the present embodiment, even after cleaning with pure water without organic solvents, a convection current is generated from the wafer side towards the processing vessel on the meniscus surface by the heating of the wafer as described below, and the wafer surface can be dried uniformly from top to bottom. This makes the device 10 for drying the substrate particularly suitable for drying after cleaning with pure water.

[0020] A receiving table 30 is provided in the main container 21 of the processing container 20. The receiving table 30 supports and holds several aligned wafers W from below. The wafers are aligned at regular intervals in an upright position, with the surfaces of adjacent wafers parallel and facing each other. The distance between the wafers is, for example, 5 to 20 mm.

[0021] The receiving table 30 is equipped with, for example, three cylindrical support elements 31. The three support elements 31 are arranged parallel to each other, with the longitudinal direction being perpendicular to the wafer surface. The three support elements 31 have V-shaped grooves that correspond to the distance between the wafers and are arranged circumferentially at the same positions in the longitudinal direction. This allows the circumference of each wafer to fit into the grooves of the three support elements, and the wafer can stabilize itself in a vertical position. The receiving table 30 can be made of quartz glass or a heat- and chemical-resistant polymer material such as polyetheretherketone. The structure of the receiving table is not limited to this, as long as it can hold the aligned wafers in an upright position.

[0022] The receiving table 30 can move up and down within the main container 21 of the processing container 20 by means of a lifting mechanism 32. When the processing fluid R has accumulated in the main container 21, the receiving table 30 moves up and down within the processing fluid and not above the surface of the processing fluid. This prevents the surface of the processing fluid from being disturbed.

[0023] Above the processing vessel 20, a drying chamber 40 is formed. The drying chamber 40 is large enough to accommodate wafers W that have been lifted out of the processing liquid R.

[0024] A feeder 50 is provided in the drying room 40. The feeder 50 holds several aligned wafers W. The feeder 50 is positioned directly above the receiving table 30, so that the wafers can be transferred between the feeder and the receiving table.

[0025] The tray 50 is provided, for example, with four cylindrical support elements 51. The four support elements 51 have V-shaped grooves that correspond to the distance between the wafers and are arranged circumferentially at the same positions in the longitudinal direction. Two of the four support elements 51 are located on each side of the wafer (left and right in the Fig. 1) arranged, the direction perpendicular to the wafer surface being the longitudinal direction. The two support elements 51 on the same side of the wafer are each supported at both ends by a pair of arms 52. The arms 52 are connected to an arm opening / closing mechanism 53 at the base end, with the base end facing upwards. The arm opening / closing mechanism 53 pivots the arms around the base end of the arms and slightly opens and closes the arms on both sides of the wafer, allowing the support elements 51 to either clamp around the perimeter of the wafer or release the wafer. The chuck 50 can be made of fused silica or a heat-resistant polymer material such as polyetheretherketone. The chuck structure is not limited as long as it can hold aligned wafers in an upright position and transfer them to the receiving table 30.

[0026] The chuck 50, including the support element 51, the arm 52, and the mechanism 53 for opening / closing the arm, is suspended and supported by a chuck suspension element 54. The chuck 50, together with the chuck suspension element 54, can move up and down in the drying chamber 40 by means of a lifting mechanism (not shown). The speed at which the wafer W is lifted from the processing container 20 is 0.5 to 4 mm / sec. During this movement, the chuck 50 only moves up and down in the drying chamber 40 and does not touch the surface of the processing fluid. This prevents any disturbance of the surface of the processing fluid.

[0027] A heating unit 60 is provided in the drying chamber 40. The heating unit 60 heats the wafer. The heating unit 60 is equipped with several rod-shaped heaters 61, which are arranged at equal intervals to the wafers, with the direction parallel and horizontal to the wafer surface being the longitudinal direction. The heater 61 has a heating element inside the tube and heats the surroundings by radiation.

[0028] Both ends of each heater 61 are connected to a heater connection box 62, which is located on both sides of the wafer and extends perpendicular to the wafer's surface. The heater connection box 62 is connected to and supported by pipes 63 by the mechanism 53 for opening / closing the arm of the feeder 50. The heater 61 is powered via power cables in the pipes 63.

[0029] By aligning the heaters 61 parallel to the wafer surface and at the same distance as the wafers, the heaters can be inserted into each gap of the aligned wafers. In this way, the heaters can efficiently heat the wafers W on both sides from a short distance. This also means that the heater temperature does not need to be very high, and rapid temperature fluctuations can be avoided, even when the heater is switched on and off. Since the temperature of the processing fluid is 20 to 80°C, the heater temperature should be set 20 to 120°C higher than the temperature of the processing fluid. The distance between the heating surface and the wafer is preferably 0.5 to 4.0 mm, and particularly preferably 0.5 to 3.5 mm, with regard to heat transfer and the stability of the device. The same applies to a heating tube as described below.

[0030] By increasing the number of heaters 61 by one more than the number of wafers W, it is possible to clamp the wafers at both ends of a wafer row with two heaters, and all wafers can be heated under essentially the same conditions.

[0031] The heater 61 is preferably an infrared heater. Using an infrared heater reduces the heating time and prevents excessive increases in the substrate drying device 10. The heater diameter is preferably 2 to 8 mm and particularly preferably 3 to 7 mm.

[0032] In the present embodiment, the heating unit 60 and the feed 50 are connected, and both move up and down together. The heating unit and the feed need not necessarily move up and down in a coupled manner, and they can also be designed to move up, stop, and move down independently. However, to allow the heating unit and the feed to move up and down independently, the overall structure of the substrate drying device 10 becomes more complex to prevent interference with the respective support and lifting mechanisms. Therefore, the heating unit and the feed can preferably move up and down in a coupled manner and are more preferably connected to each other.Since it is undesirable to disturb the surface of the processing fluid, the heating unit preferably does not touch the surface of the processing fluid, just as it is preferred that the feeder does not touch the surface of the processing fluid. If the heating unit moves upwards coupled with the feeder, it is difficult to position the heating unit near the surface of the processing fluid, i.e., near the bottom of the wafer. However, by heating the surface of the wafer and transferring the heat from top to bottom to the meniscus, the meniscus portion is heated.

[0033] As a mechanism for heating the wafer W, a heating tube unit with a heating tube as the heating element can be used instead of the heating unit 60. The heating tube unit is equipped with several rod-shaped heating tubes arranged at the same intervals as the wafer, with the direction parallel and horizontal to the wafer surface being the longitudinal direction. The heating tube is an element in which the tube is heated by the circulation of a heated fluid inside, and the outside of the tube is heated by radiation from the surface of the heating tube. Liquids such as hot water or gases such as air or nitrogen can be used as the fluid. When a heater is used, the power must be controlled by switching it on and off, etc., whereas when using the heating tube, the temperature of the tube rises to the temperature of the fluid circulating in the tube and stabilizes, so that control by switching it on and off, etc., is not necessary.This is not required and the wafer temperature is more stable. When the heating tube is used, a mechanism for introducing and draining the fluid is provided instead of a power supply mechanism.

[0034] Next, the process for drying a substrate will be explained. The reference symbols for the various parts are the same as in Fig. 1 and Fig. 2.

[0035] First, the aligned wafers W are placed on the receiving table 30 and held in place, while the main container 21 of the processing container 20 is filled with the processing fluid R, and the entire wafer is immersed in the processing fluid for cleaning. After cleaning is complete, the receiving table 30, on which the wafers W are held, begins to move upwards. During this movement, the arm 52 of the chuck 50 opens, the chuck is moved downwards to its lower end position in the drying chamber 40, and the heater 61 begins to energize ( Fig. 3A).

[0036] As the receiving table 30 moves upwards, the wafer moves from its top edge above the surface of the processing fluid, and finally the upper part of the wafer enters the gap between the heaters 61 ( Fig. 3B).

[0037] The receiving table 30 is moved further upwards into the upper limit position and the arm 52 of the feeder 50 is closed to hold the wafer ( Fig. 3C).

[0038] The feeder 50 is moved upwards. The heating unit 60, which is connected to the feeder 50, also moves upwards along with the feeder. The wafer W, held in the feeder, moves upwards away from the receiving table 30. The entire wafer rises above the surface of the processing fluid and enters the drying chamber 40. When the wafer drying is complete, the heating unit 61 stops the current flowing to it. Fig. 3D).

[0039] In the state where the wafer W moves upwards and is partially immersed in the processing fluid ( Fig. 3B, C), a meniscus of processing fluid forms between the adjacent wafers. Fig.4. The processing fluid R (arrow D), lifted from the wafer W, is removed from the wafer surface by gravity flow and evaporation. Since the wafer is heated by the heater 61, heat is transferred from top to bottom towards the meniscus M (arrow H). Due to the heat transferred from the upper part of the wafer and, to a certain extent, the heat radiated by the heater, the temperature at the top of the meniscus rises and the surface tension decreases. This creates a convection current C on the surface of the meniscus from the wafer side towards the processing vessel, allowing the processing fluid to flow smoothly down. Evaporation is also promoted in the upper part of the meniscus because heat is continuously transferred from top to bottom through the wafer. This ensures that the drying of the wafer surface proceeds uniformly from top to bottom and reduces the likelihood of water spots forming.

[0040] In the present embodiment, the wafer W is heated by the radiation of the heater 61, so that the surface of the processing fluid R is not disturbed and the height of the formed meniscus does not fluctuate.

[0041] The inventors confirmed the effectiveness of the substrate drying process through experiments. Several silicon wafers, 0.8 mm thick and 300 mm in diameter, were aligned at essentially equal intervals, immersed in water heated to between 20 and 80°C, and then lifted out of the hot water. The heating unit and the stave were connected, and a near-infrared halogen heater (maximum power 1 kW) with a diameter of 6 mm was positioned so that the surface temperature of the heating tube reached 150°C. It was placed in the gap between the lifted wafers to heat both the front and back surfaces. As a result, the wafer drying proceeded smoothly from top to bottom, and the meniscus shape remained stable throughout the drying process.

[0042] The present invention is not limited to the embodiments mentioned above and can be varied within the framework of the basic technical idea. Explanation of reference symbols 10 Device for drying a substrate 20 processing containers 21 main tanks 22 auxiliary containers 30 Pick-up table (first substrate holding mechanism) 31 Support element 32 Lifting mechanism 40 drying room 50 Feed (second substrate retention mechanism) 51 Support element 52 Arm 53 Mechanism for opening / closing an arm 54 Feed suspension element 60 Heating unit (heating mechanism) 61 Heating (heating element) 62 Heating connection box 63 Pipeline C Convection current of the processing fluid on the meniscus surface The flow of the processing fluid lifted from the wafer H Heat flow in wafer M Meniscus R Processing fluid W Semiconductor wafer (substrate) QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 6458123 B

[0004] JP 2021-145043 A

[0004]

Claims

Device for drying a substrate, comprising: a processing container which accumulates a processing fluid, a first substrate holding mechanism provided in the processing container which can hold several substrates aligned with parallel substrate surfaces and which can move up and down in the processing container, a drying chamber which is formed above the processing container, a second substrate holding mechanism which is provided in the drying chamber which can hold several substrates and which can move up and down in the drying chamber, and a heating mechanism which is provided in the drying chamber and is equipped with several heating elements which are aligned so that they can be positioned in each gap of the several substrates which are held by the second substrate holding mechanism. Device for drying a substrate according to claim 1, wherein the second substrate holding mechanism and the heating mechanism can move upwards and downwards in a coupled manner in the drying chamber. Device for drying a substrate according to claim 1, wherein the heating element is a rod-shaped heater. Device for drying a substrate according to claim 1, wherein the heating element is a heating tube in which a heated fluid circulates. Device for drying a substrate according to claim 1, wherein the processing liquid is pure water. A method for drying a substrate, comprising: a step for holding several substrates aligned with parallel substrate surfaces by a first substrate holding mechanism, immersion in a processing fluid and upward movement of the first substrate holding mechanism in the processing fluid to introduce each of the several substrates into each gap of parallel aligned, several rod-shaped heating elements provided in a heating mechanism provided in a drying chamber formed above the processing fluid, a step for holding the several substrates by a second substrate holding mechanism provided in the drying chamber, and a step for upward movement of the second substrate holding mechanism and the heating mechanism in the drying chamber.

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