Drying and gas or vapor contact with solids – Material treated by electromagnetic energy
Reexamination Certificate
2000-05-26
2002-09-10
Doerrler, William C. (Department: 3744)
Drying and gas or vapor contact with solids
Material treated by electromagnetic energy
C034S467000, C034S472000, C034S229000, C034S219000, C034S220000, C034S448000, C118S715000, C118S724000, C118S725000
Reexamination Certificate
active
06446355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to removing liquid from disks, and more particularly to apparatus and methods for drying a disk that has been wet in a liquid bath, after which the disk and the bath are separated at a controlled rate to form a thin layer of liquid on the disk as the disk is positioned in a gas-filled volume, wherein the volume is defined by a hot chamber that continuously transfers thermal energy to the disk in the volume, and wherein hot gas directed into the volume and across the disk and out of the volume continuously transfers thermal energy to the disk, so that the thermal energy transferred to the disk in the volume evaporates the thin layer from the disk without decreasing the rate of separation of the disk and the bath below a maximum rate of such separation at which a meniscus will form between the bath and the surface of the disk during such separation.
2. Description of the Related Art
In the manufacture of semiconductor devices, process chambers are interfaced to permit transfer of wafers between the interfaced chambers. Such wafer transfer is via transport modules that move the wafers, for example, through slots or ports that are provided in the adjacent walls of the interfaced chambers. For example, transport modules are generally used in conjunction with a variety of wafer processing modules, which may include semiconductor etching systems, material deposition systems, flat panel display etching systems, and wafer cleaning systems. Due to growing demands for cleanliness and high processing precision, there has been a greater need to reduce the amount of human interaction during, between, and after such processing steps. This need has been partially met with the implementation of vacuum transport modules which operate as an intermediate wafer handling apparatus (typically maintained at a reduced pressure, e.g., vacuum conditions). By way of example, a vacuum transport module may be physically located between one or more clean room storage facilities where wafers are stored, and multiple wafer processing modules where the wafers are actually processed, e.g., etched or have deposition performed thereon, or cleaned. In this manner, when a wafer is required for processing, a robot arm located within the transport module may be employed to retrieve a selected wafer from storage and place it into one of the multiple processing modules.
Despite use of such intermediate wafer handling apparatus, it is still necessary to clean and dry the wafers at the completion of such processing. As an example, after the wafers have been cleaned, the wafers may have a non-uniform coating of liquid. A wafer with such non-uniform coating of liquid, or with one or more drops of liquid thereon, or with any liquid thereon in any physical form, may be said to be “wet”. In contrast, a wafer having a uniform coating of liquid may be said to be “uniformly wet”.
In the past, items other than wafers have been processed. Items such as annular-shaped disks of many various sizes have been used for manufacturing data storage devices, for example. Such disks have also been subjected to a drying operation. After cleaning and while wet, such disks have been placed in a tank containing a bath of hot liquid. In one type of drying operation, the hot liquid has been drained from the tank at a rate such that a thin layer of liquid, rather than one or more drops of liquid, forms on that portion of such disk that is out of the draining liquid. The thin layer has been preferred over one or more drops because a drop of liquid has a high volume, e.g., from about 0.001 ml. to about 0.020 ml. In comparison to the drop, a thin layer of liquid on a substrate such as a 95 mm diameter disk, may only have a volume of at the maximum diameter of the disk of about 0.0007 ml, for example. Evaporation of a drop generally results in the concentration of small particles at the last small point on the disk at which the drop exists. Such concentration may result in defects in a data storage device made from the disk.
To remove the thin layer from such disk, reliance has been placed on the thermal energy stored in such disk to provide the thermal energy necessary to evaporate the thin layer. However, it appears that using only such stored thermal energy, the thin layer may evaporate from the disk at a rate less than the maximum rate of separation of the liquid bath and the disk at which a meniscus will form between the liquid bath and the surface of the disk during such separation. Thus, the rate at which the liquid is drained from the tank has to be decreased to match the rate of evaporation. Alternatively, the disk would have to be retained in the tank after the draining has been completed. Each of such decreased rate of draining and such retaining increases the time required to dry the disk, which increases the cost of fabricating devices based on the disk.
In view of the forgoing, what is needed is apparatus and methods of efficiently drying disks. Such efficient drying should allow the disks and the liquid to be separated at a rate no less than the maximum rate of separation of the liquid and the disk at which a meniscus will form between the liquid bath and the surface of the disk. Also, the efficient drying should rapidly remove from the disk a thin layer of liquid that forms on the disk as the disk and the bath are separated, wherein “rapidly” means such removal occurs before the disk and the bath have been completely separated e.g., separated by about 0.004 inches.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills these needs by providing apparatus and methods of efficiently removing fluid from disks. The efficient removing is attained by providing apparatus and methods for drying a disk that has been uniformly wet in a fluid bath, in which the disk and the bath are separated at a controlled rate to form a thin layer of fluid on the disk as the disk is positioned in a gas-filled volume. In addition to such separation, the efficient removing is attained by defining the gas-filled volume by use of a hot chamber that continuously transfers thermal energy to the disk in the volume. Further, hot gas directed into the volume and across the disk and out of the volume continuously transfers thermal energy to the disk. The directing of the gas out of the volume is independent of the separation of the bath and the disk. The thermal energy transferred to the disk in the volume evaporates the thin layer from the disk without decreasing the rate of separation of the disk and the bath below the maximum rate of such separation at which a meniscus will form between the bath and the surface of the disk during such separation. In addition to such separation and directing of the hot gas across the disk and out of the volume, the relative humidity in the volume is kept low to inhibit recondensation of the fluid on the disks, for example.
Such efficient removal enables the disk throughput of such apparatus and method to be limited only by the type of disk that is being dried, and the type of fluid used to wet the disk. For example, the characteristics of particular types of disks and fluid dictate the maximum rate of such separation of the disk and the bath at which a meniscus will form between the bath and the surface of the disk during such separation and the disk will be uniformly wet.
In one embodiment of the present invention a disk drying system may include a bath enclosure configured to hold a fluid so that the fluid defines a top fluid surface. A temperature and humidity-controlled chamber may also be defined above the fluid surface. The chamber has a first opening at a first side proximate to the fluid surface and a second opening at a second side that is opposite to the first side.
In another embodiment of the present invention the disks to be dried have opposite sides, and apparatus for drying the disks may include a bath containing hot liquid, wherein the liquid defines an upper surface. Also provided is an enclosure having an inle
Borkowski Jonathan
Jones Oliver David
McMahon Kenneth C.
Mehmandoust Yassin
Olivas James M.
Lam Research Corporation
Martine & Penilla LLP
Shulman Mark S
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