Rotary tumble dryer with improved drying characteristics

Abstract

Embodiments of the present application relate to a spin-rinse-dryer having improved drying characteristics, having a rotatable support for supporting the substrate, a rotatable member within the housing above the rotatable support, the rotatable member having a continuous lower surface, and a drive for rotating the rotatable member. During cleaning of a wafer, liquid splashed from the wafer will hit the rotatable member rather than the upper walls of the housing, and droplets of liquid can form on the rotatable member. After flow of the cleaning liquid has stopped, the drive can rotate the rotatable member at high speed, which tends to fling the liquid droplets from the rotatable member by centrifugal force. Liquid then flows down the walls of the housing, away from the wafer, so that the chance of contamination of the cleaned wafer is greatly reduced. The rotatable member and the rotatable support can be integrally formed and rotate together. Alternatively, they can be separate components.

Description

Technical Field

[0001] The present invention relates to a rotary rinsing dryer, and more particularly to a rotary rinsing dryer having components for reducing the chance of unwanted contamination. Background Technology

[0002] Rotary rinse-dryer (SRD) is commonly used in the semiconductor industry and related industries to clean substrates. The SRD can be used as a standalone unit or integrated into a larger system that includes additional systems for performing other functions (e.g., wet etching systems, photoresist systems, or electrochemical deposition systems).

[0003] A common function of SRD (Search Engine Manufacturing) is to clean and dry (typically circular) workpieces or (especially in the semiconductor industry) wafer substrates. During the cleaning step, a cleaning fluid (typically an aqueous solution) is sprayed onto the wafer while it rotates in a horizontal plane at a relatively low speed (typically 50 rpm to 200 rpm). This typically occurs within a chamber or housing, which prevents liquid spray escape and ensures the wafer remains in a controlled environment. The process volume is usually purged from above the wafer with an inert gas (e.g., N2) to aid fluid flow within the chamber. Once the cleaning fluid has removed contaminants from the wafer, the fluid flow is stopped, and the wafer is rotated at a high speed (up to approximately 2000 rpm to 2500 rpm) to promote wafer drying before it comes to a standstill and is ready to be retrieved and moved forward to further process steps.

[0004] In some critical process steps, such as the final cleaning before returning to the cassette or front-open assembly cassette (FOUP), this "rinse and dry" process not only thoroughly cleans the wafer but also ensures it is completely dry when retrieved from the SRD chamber. Aqueous droplets present on the wafer surface can damage devices on the substrate; for example, if the layer being cleaned is a metal such as copper, aqueous droplets can cause corrosion or excessive oxidation of the substrate surface. This is undesirable because it can lead to a loss of yield.

[0005] Integrating several process steps into a single automated system offers several benefits, such as cost, productivity, and yield. In the case of an electrochemical deposition system, the process sequence may involve a pre-cleaning step, followed by several metal deposition steps, and several post-deposition wafer cleaning steps before returning to the wafer cassette or FOUP.

[0006] When bump metallization (for example) requires relatively thick (several micrometers) metal deposition steps, a relatively large number of modules (more than ten deposition stations) are needed to make the production system cost-effective. Minimizing footprint is important in the context of semiconductor capital equipment because cleanroom space is expensive and therefore tooling footprint is a key contributor to total tooling cost. This has led to methods of vertically “stacking” process modules to improve productivity while minimizing cleanroom footprint. For example, US 9421617 shows (in Figure 2 of the document) an arrangement where one SRD module is positioned above a second SRD module.

[0007] Figure 1a and 1b A schematic representation of a conventional bowl-shaped SRD similar in type to that shown in US 6497241 is presented. Figure 1a In this configuration, the top of chamber 1 is open, allowing the wafer 3 to be inserted into and removed from chamber 1 from above. Figure 1b In the middle, chamber 1 has a flat cover 7 to provide a housing. The wafer 3 can be inserted into and removed from chamber 1 via slits in the sidewalls; alternatively, the cover 7 can be removed, allowing it to be connected to... Figure 1a The arrangement shown in the image is similar to that used for inserting and removing chip 3.

[0008] Chamber 1 is typically made of polymer materials such as high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkylene (PFA), polyvinyl chloride (PVC), etc. The choice of material will depend largely on the properties of the cleaning fluid used to process the wafer. Some cleaning fluids are not compatible with conventional polymer materials, and if these fluids are used, then stainless steel or another metal can be used to make the chamber.

[0009] The chamber has a rotor assembly 2 that holds the wafer 3 and can be controlled to rotate at speeds up to approximately 3000 rpm. A jet nozzle or a series of jet nozzles 4a is located above the plane of the wafer 3 and points towards the front surface of the wafer. Similarly, a jet nozzle or a series of jet nozzles 4b is located below the plane of the wafer 3 and points towards the rear surface of the wafer.

[0010] Fluid from nozzles 4a and 4b impacts wafer 3, is flung away from wafer 3 as in a centrifuge to impact the sidewalls of chamber 1, and is removed from the discharge port (not shown) at the base of chamber 1. After the rinsing step, an inert purging gas (e.g., N2) can be directed to wafer 3 to aid in drying the wafer. However, after wafer 3 has been dried, some fluid may remain on the walls of chamber 1, and... Figure 1bIn this arrangement, droplets 6 may form on the lower surface of the chamber cover 7. These droplets may fall onto the wafer 3 during the removal of the wafer 3 from the chamber 1 and contaminate the wafer 3.

[0011] Obviously, this problem will not occur. Figure 1a In this arrangement, there is no cap on top where droplets can form. However, Figure 1a The layout is incompatible with low-profile SRD module designs; if stacked vertically as... Figure 1a The SRDs shown in the figure will require a large gap between the modules to prevent droplets from forming on the lower surface of the upper module.

[0012] Alternative methods have been proposed to address the problem of droplet formation on the lower surface of the cap. For example, US9421617 (mentioned above) shows that the cap 10 is formed in a conical shape (in... Figure 2a The arrangement (illustrated schematically) causes the droplets to tend to flow downwards and radially outwards, away from the wafer. This effect can be enhanced by making the lower surface of the cap hydrophobic. Figure 2b The illustration shows an arrangement in which the cover 12 is formed as a dome, which may again have a hydrophobic lower surface. Nozzles for the purge gas may be positioned at the top of the dome 12 to guide an inert purge gas (e.g., N2) along the inner surface of the dome 12 to push the droplets radially outward and away from the wafer.

[0013] However, these arrangements all require a considerable amount of vertical space above the wafer, and therefore are not well-suited for high-density vertical chamber stacking. Summary of the Invention

[0014] Therefore, the objective of this invention is to provide a low-profile rotary rinsing and drying machine capable of high-density vertical stacking of contaminated wafers after cleaning and drying, with reduced risk.

[0015] According to a first aspect of the invention, a rotary rinsing and drying machine for processing a substrate is provided, comprising: a housing; a rotatable support for supporting the substrate; a rotatable component located above the rotatable support within the housing, the rotatable component having a continuous lower surface; and a drive for rotating the rotatable component.

[0016] During wafer cleaning, any liquid splashed from the wafer will impact the lower surface of the rotatable component rather than the upper wall of the housing, and may form droplets on the rotatable component. After the flow of the cleaning liquid has stopped, the actuator can rotate the rotatable component at high speed, which tends to dislodge the liquid droplets from the lower surface of the rotatable component by centrifugal force. The liquid then flows down the wall of the housing, away from the wafer, thus greatly reducing the chance of contamination of the cleaned wafer.

[0017] An advantage of this invention is that the rotary rinsing dryer can be provided as a low-profile rotary rinsing dryer. The low-profile rotary rinsing dryer of this invention can have a vertical height of 300 mm or less. This is particularly suitable for applications where modules are vertically stacked.

[0018] When the substrate is supported by a rotatable support, the lower surface of the rotatable component can be arranged to be generally parallel to the upper surface of the substrate.

[0019] A rotatable support can be connected to a rotatable component, allowing the rotatable support to rotate together with the rotatable component. Several arms can extend downward from the rotatable component, and pointed teeth can extend radially inward from the lower end of each arm, the pointed teeth acting as rotatable supports. There can be three arms evenly distributed along the circumference.

[0020] The actuator may be located next to the housing and may be connected to the rotatable component and the rotatable support to drive the rotatable component and the rotatable support to rotate.

[0021] The rotatable support and the rotatable component may not be connected to each other and may rotate independently. The rotatable support and the rotatable component may be arranged to rotate about a common axis. A single actuator may be located next to the housing and connected to both the rotatable component and the rotatable support to drive their rotation. The actuator may be connected to the rotatable component and the rotatable support via a telescopic shaft. In another arrangement, two actuators may be located next to the housing; a first actuator may be connected to the rotatable component to drive its rotation, and a second actuator may be connected to the rotatable support to drive its rotation.

[0022] Both the housing and the rotatable component can be circular in plan view. The diameter of the rotatable component can be slightly smaller than the inner diameter of the housing. The diameter of the rotatable component can be larger than the diameter of the substrate to be processed.

[0023] The rotatable component may be formed of a hydrophobic material such as polycarbonate.

[0024] The rotatable component can be formed as a single part.

[0025] The rotatable component may be formed with reinforcing features such as ribs.

[0026] The rotary rinsing dryer may include nozzles located above and below the rotatable support for guiding liquid toward a substrate located on the rotatable support.

[0027] The rotary rinsing and drying machine can operate at pressures below atmospheric pressure.

[0028] The rotary rinsing and drying machine may have a vertical height of less than approximately 300 mm.

[0029] The invention also extends to an apparatus for processing a substrate, comprising a stack of substrate processing modules, wherein at least one of the modules is a rotary rinse dryer as described above.

[0030] According to another aspect of the present invention, a method for processing a substrate is provided, comprising: supporting the substrate on a rotatable support in a housing below a rotatable component; guiding liquid from nozzles above and below the rotatable support to the substrate to rinse the substrate; rotating the rotatable support to remove liquid from the substrate; rotating the rotatable component to remove liquid from the rotatable component; and removing the substrate from the housing.

[0031] The substrate may be a semiconductor substrate, such as a semiconductor wafer.

[0032] Although the invention has been described above, it is extended to any combination of features set forth in the foregoing or in the following description, drawings, or claims. For example, any feature disclosed with respect to one aspect of the invention may be combined with any feature disclosed with respect to any other aspect of the invention. Attached Figure Description

[0033] Preferred embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0034] Figure 1a and 1b This is a schematic diagram of an existing rotary rinsing and drying machine;

[0035] Figure 2a and 2b This is a schematic diagram of a prior art rotary rinsing dryer that includes components designed to reduce contamination of cleaned wafers;

[0036] Figure 3This is a schematic cross-sectional view of a first embodiment of the rotary rinsing and drying machine according to the present invention;

[0037] Figure 4 This is a side view of the rotary rinsing and drying machine according to the present invention; and

[0038] Figure 5a and 5b It is similar to Figure 3 A schematic cross-sectional view showing the alternative drive component. Detailed Implementation

[0039] Figure 3 The first embodiment of the present invention is shown. Figure 3 The rotary rinse-dryer comprises a housing formed by a body 21 and a cover 22, having a rotatable support 23 for a wafer 29. A rotatable component 27, located above the wafer 29 and below the cover 22 of the housing, is in the form of a disk with a continuous lower surface. Any liquid splashed from the wafer 29 during rinsing will impact the lower surface of the rotatable component 27, rather than the cover 22 of the housing, thus droplets will form on the rotatable component 27 rather than the cover 22. The rotatable component 27 can then be rotated to remove the droplets from the lower surface via centrifugal force.

[0040] exist Figure 3 In the specific version shown, the rotatable support 23 for the wafer 29 is integrally formed with the rotatable component 27. Three circumferentially distributed arms extend downward from the rotatable component 27, and the wafer 29 is supported on three pointed teeth extending radially inward from the lower ends of the arms. The rotatable component 27, and thus the arms and teeth, rotate via a central shaft 25, which extends vertically through the cover 22 of the housing. The central shaft 25 is powered to rotate by means of a motor 28 located on one side of the chamber, wherein the shaft of the motor 28 extends vertically and is connected to the central shaft 25 via a drive 26. A drive member is arranged next to the housing to reduce the overall height of the rotary rinsing dryer.

[0041] During wafer cleaning, as cleaning fluid is ejected from nozzles 24a and 24b, the rotatable component 27 and the rotatable support 23 for the wafer 29 rotate (typically at 50 rpm to 200 rpm). All internal surfaces of the chamber are wetted by the dispersed spray, resulting in the formation of suspended liquid droplets that can fall onto the wafer 29 (similar to...). Figure 1b The possibility of suspended liquid droplets shown in the image.

[0042] Once wafer 29 has been rinsed, the fluid supply is shut off and wafer 29 is dried by rotating at a high speed (typically 2000 rpm to 2500 rpm). An inert drying purge gas, such as nitrogen, may also be used. During this high-speed rotation, not only wafer 29 is dried (by centrifugal force that moves water radially away from wafer 29), but also the rotatable component 27 located directly above wafer 29 is dried. Droplets formed on the rotatable component 27 are thrown off by centrifugal force. When rotation ends, there should be no droplets above wafer 29, and therefore no risk of liquid dripping onto wafer 29. Furthermore, this is achieved in a low-profile package (i.e., with minimal vertical height).

[0043] Typically, the rotatable component 27 has a larger diameter than the wafer 29; for example, if the wafer 29 has a diameter of 300 mm, then the rotatable component 27 will have a diameter of 320 mm. Furthermore, the rotatable component 27 should extend as close as possible to the chamber wall, and preferably within a maximum of 10 mm of the chamber wall. This further reduces the risk of liquid dripping from the lower surface of the chamber cover 22 onto the wafer 29. Drainage channels for the fluid may be located near the chamber wall. Additionally, the top of the rotatable component 27 should be positioned close to the lower surface of the chamber cover 22 (to reduce the risk of spray from the nozzle impacting the lower surface of the chamber cover 22), and preferably within 3 mm of the lower surface of the chamber cover 22.

[0044] Figure 4 A low-profile rotary rinse dryer is shown, in which a chamber is opened to allow loading or unloading of wafers. In this configuration, the lower portion 31 of the chamber moves away from the fixed upper portion 32, but it is possible to keep the lower portion 31 of the chamber fixed and to move the upper portion 32 of the chamber. This opening and closing movement can be achieved using an electric motor or a pneumatic or hydraulic piston.

[0045] When the chamber is opened, the wafer 39 can be inserted into or removed from the rotatable support 33. The inner diameter between the retaining arms must be larger than the diameter of the wafer 39 to allow the wafer 39 to be placed into the chamber and onto the rotatable support 33. Furthermore, if notch alignment is required, the wafer 39 needs to be rotated and aligned in position within the rotatable support 33 before wafer loading or unloading can occur. This is achieved by a central lifting post 40, which lifts the wafer 39 from the rotatable support 33 and allows the notch or plane on the wafer 39 to be aligned with a defined orientation on the rotatable support before the unloading step.

[0046] Figure 4 A particular version of the room has a maximum height of approximately 215mm when opened; this allows the rooms to be stacked with a spacing of approximately 225mm, resulting in efficient use of space.

[0047] This invention is not limited to Figure 3 The specific drive arrangement shown in the document. Figure 5a The illustration shows a variation in which the rotatable support 53 and rotatable component 54 are separate entities arranged to rotate about a common axis. The rotatable support 53 supports the wafer from below, which simplifies the wafer loading and unloading process. The rotatable support 53 and rotatable component 54 are driven by a single motor 51 and connected to the single motor via a telescopic coupling 52 (the telescopic aspect is necessary to allow the upper and lower portions of the chamber to move away from each other to open the chamber). Figure 5b This section showcases alternative versions of separate motors 61 and 62 provided for the rotatable support 63 and rotatable component 64, which are rearranged to rotate around a common axis. Figure 3 As in the embodiment shown, one or more motors 61, 62 are arranged on the side of the chamber to keep the overall height as low as possible.

[0048] By forming the rotatable support and the rotatable component as two different entities, it is possible to reduce the overall size of the rotor assembly, which in turn can produce a chamber with a smaller diameter. Figure 5a and 5b The arrangement shown also allows for greater process flexibility in cleaning and drying wafers because it allows rotatable supports and rotatable components to rotate at different speeds. Furthermore, Figure 5b The arrangement shown allows the rotatable support and rotatable components to rotate independently of each other.

[0049] When operating with two drive assemblies, the rotatable component will typically have a maximum speed lower than the wafer's maximum speed (less than or equal to approximately 1000 rpm) because the rotatable component does not contain surface morphologies that need to be dried and only requires the removal of larger liquid droplets. If the process uses deionized water for cleaning, the rotatable component can be made of hydrophobic plastic materials such as polycarbonate, but the choice of material will of course depend on compatibility with the process chemistry.

[0050] Rotatable components are typically machined or molded into individual parts to ensure mechanical robustness. Furthermore, rotatable components may be formed with ribs or similar reinforcing features radiating outwards from the center to increase their rigidity.

[0051] Figure 3 , 5aFigure 5b only shows a linear number of wetting nozzles. In reality, a rotary rinse dryer will feature several wetting nozzles capable of reaching both the upper and lower surfaces (front and back) of the wafer. Depending on process requirements, different nozzle flow rates, drive pressures, and spray patterns can be used. Common spray pattern options are fan and solid cone. A typical nozzle flow rate is 1 liter / minute at 35 psi (approximately 240 kPa), and therefore a rotary rinse dryer using four fluid nozzles would operate at 4 liters / minute.

[0052] The chamber can be sealed during wafer delivery, which allows wafers to be processed at pressures below atmospheric pressure (typically 10 to 100 Torr (approximately 133 Pa to 1330 Pa)).

[0053] Although only specific embodiments of the invention have been described, those skilled in the art will understand that the invention is not limited to these embodiments and may be varied within the scope of the appended claims.

Claims

1. A rotary rinsing and drying machine for processing substrates, comprising: The shell, which is formed by a body and a cover; A rotatable support located within the housing, which supports the substrate; A rotatable component located within the housing, above the rotatable support, the rotatable component having a continuous lower surface and a top, wherein the top of the rotatable component is positioned within 3 mm of the lower surface of the cover, wherein both the housing and the rotatable component are circular in plan view, and wherein the circular edge of the rotatable component extends to a position 10 mm or closer to the main body; and A driver, which is used to rotate the rotatable component, The rotary rinsing dryer described therein can operate at pressures below atmospheric pressure.

2. The rotary rinsing and drying machine according to claim 1, wherein when the substrate is supported by the rotatable support, the lower surface of the rotatable member is arranged substantially parallel to the upper surface of the substrate.

3. The rotary rinsing and drying machine according to claim 1 or claim 2, wherein the rotatable support is connected to the rotatable component such that the rotatable support rotates together with the rotatable component.

4. The rotary rinsing and drying machine according to claim 3, wherein a plurality of arms extend downward from the rotatable component, and fangs extend radially inward from the lower end of each arm, the fangs serving as the rotatable support.

5. The rotary rinsing and drying machine according to claim 4, wherein there are three arms evenly distributed along the circumference.

6. The rotary rinsing and drying machine according to claim 3, wherein the drive is located next to the housing and connected to the rotatable component and the rotatable support to drive the rotatable component and the rotatable support to rotate.

7. The rotary rinsing and drying machine according to claim 1, wherein the rotatable support and the rotatable component are not connected to each other and rotate independently.

8. The rotary rinsing and drying machine according to claim 1, wherein the rotatable support and the rotatable components are arranged to rotate about a common axis.

9. The rotary rinsing and drying machine according to claim 8, wherein a single drive is located next to the housing and connected to both the rotatable component and the rotatable support to drive the rotatable component and the rotatable support to rotate.

10. The rotary rinsing and drying machine according to claim 9, wherein the drive is connected to the rotatable component and the rotatable support via a telescopic shaft.

11. The rotary rinsing and drying machine according to claim 7, wherein two drives are located beside the housing, a first drive of the drives is connected to the rotatable component to drive the rotatable component to rotate, and a second drive of the drives is connected to the rotatable support to drive the rotatable support to rotate.

12. The rotary rinsing and drying machine according to claim 1 or claim 2, wherein the diameter of the rotatable component is smaller than the inner diameter of the housing.

13. The rotary rinsing and drying machine according to claim 12, wherein the diameter of the rotatable component is larger than the diameter of the substrate to be processed.

14. The rotary rinsing and drying machine according to claim 1 or claim 2, wherein the rotatable component is formed of a hydrophobic material.

15. The rotary rinsing dryer according to claim 14, wherein the hydrophobic material is polycarbonate.

16. The rotary rinsing and drying machine according to claim 14, wherein: The rotatable component is formed as a single part; or The rotatable component has a reinforcing feature; or The rotary rinsing dryer includes nozzles located above and below the rotatable support for guiding liquid toward a substrate located on the rotatable support.

17. The rotary rinsing dryer according to claim 16, wherein the reinforcing feature is a rib.

18. The rotary rinsing dryer according to claim 1 or claim 2, wherein the vertical height of the rotary rinsing dryer is less than 300 mm.

19. An apparatus for processing a substrate, comprising a stack of substrate processing modules, wherein at least one of the modules is a rotary rinse dryer according to any of the preceding claims.

20. A method for processing a substrate, comprising: A substrate is supported on a rotatable support in a housing below the rotatable component. The housing is formed by a body and a cover. The rotatable component has a continuous lower surface and a top surface. The top surface of the rotatable component is located within 3 mm from the lower surface of the cover. The housing and the rotatable component are both circular in plan view. The circular edge of the rotatable component extends to a position 10 mm or closer to the body. Liquid is directed from nozzles above and below the rotatable support to the substrate to rinse the substrate; Rotate the rotatable support to remove liquid from the substrate; Rotate the rotatable component to remove liquid from the rotatable component; and Remove the substrate from the housing. The aforementioned process can be performed at pressures below atmospheric pressure.

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