Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Reexamination Certificate
2000-04-19
2001-01-09
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
C134S133000, C134S135000, C134S902000
Reexamination Certificate
active
06171403
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cleaning and drying apparatus for cleaning a wafer to be processed, such as a semiconductor wafer or a glass substrate for LCDs, by immersing the same in a cleaning liquid, and drying the same after cleaning, a wafer processing system, and a wafer processing method.
2. Description of the Related Art
Generally, in a semiconductor device fabricating process to be carried out by a semiconductor device fabricating system, a generally known cleaning method cleans a wafer to be processed (hereinafter referred to simply as “wafer”), such as a semiconductor wafer or a glass substrate for LCDs, by sequentially immersing the wafer in a liquid chemical, a rinsing liquid (cleaning liquid) and such contained in processing tanks. A cleaning system for carrying out such a cleaning method is provided with a drying apparatus which brings a drying gas containing a vapor of a volatile organic solvent, such as isopropyl alcohol, into contact with the surface of the cleaning liquid in order that moisture is removed from the wafer and the wafer is dried by the Marangoni effect. (Refer to JP-A No. 8-148458.)
A conventional cleaning and drying apparatus of this kind includes a cleaning tank storing a cleaning liquid, such as a liquid chemical or a rinsing liquid, having an upper opening covered with a hood (lid). Usually, the lid is made of a strong material, such as polypropylene or a stainless steel, to seal the cleaning tank during a drying process. In this cleaning and drying apparatus, a carrying arm carries a wafer through the open opening into the cleaning tank, transfers the wafer to a wafer supporting means which moves in a transfer unit, and moves out of the cleaning tank. Then, the opening is closed with the lid, the wafer is cleaned in the cleaning tank, and then the wafer is taken out of the cleaning tank for drying.
However, since the wafer is carried into the cleaning tank from above the transfer unit disposed in an upper portion of the cleaning tank, and the wafer is taken out from the cleaning tank after cleaning when cleaning the wafer by this conventional cleaning and drying apparatus, the carrying arm has a great vertical length (height) and the cleaning and drying apparatus is large. Particularly, there is the trend of change from using 8 in. diameter wafers to using 12 in. diameter wafers for the fabrication of semiconductor devices owing to the progressive miniaturization of semiconductor devices, the advancement of IC complexity to large-scale integration and the progress of mass production in recent years. The use of 12 in. diameter wafers entails the further enlargement of cleaning and drying apparatus and resultant reduction of throughput.
Since the lid and the cleaning tank are made of polypropylene or a stainless steel, particles are liable to be produced, metallic impurities are precipitated or eluted from the lid and the cleaning tank due to aged deterioration. The metallic impurities adhere to wafers to reduce the yield.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing problems and it is therefore an object of the present invention to provide a cleaning and drying apparatus of a small construction capable of carrying out a cleaning process and a drying process and of operating at an improved throughput, a wafer processing system and a wafer processing method.
With the foregoing object in view, a cleaning and drying apparatus according to a first aspect of the present invention comprises a cleaning tank containing a cleaning liquid for cleaning wafers, a drying unit disposed above the cleaning tank and having a drying chamber, and a wafer holding means for holding wafers and moving wafers into the cleaning tank and the drying chamber. The drying unit having the drying chamber, has a fixed base connected to the cleaning tank so as to surround an opening formed in the cleaning tank, and a liftable top cover placed on the fixed base in close contact with the fixed base.
Although the top cover may be of an optional shape provided that the top cover can be vertically moved relative to the fixed base surrounding the opening of the cleaning tank, it is preferable to interpose a sealing member between the fixed base and the top cover and to provide the opening of the cleaning tank with a shutter for isolating a cleaning chamber defined by the cleaning tank, and the drying chamber from each other. Preferably, the top cover is a member made of quartz and having a cross section of a shape resembling the inverted letter U. It is preferable that the top cover is a member made of quartz and having a cross section of a shape resembling the inverted letter U, and both the fixed base and the cleaning tank are made of quartz.
Heating elements can be disposed outside the top cover if the top cover is made of quartz. It is preferable to disposed reflecting plates behind the heating elements if the heating elements are disposed outside the top cover. The heating elements may be, for example, heating lamps or rubber heaters.
Preferably, a drying gas is supplied into the drying chamber by a drying gas supply unit. Preferably, the drying gas supply unit is disposed on the fixed base and, more preferably, the drying gas supply unit is designed so as to supply a drying gas upward from a position on one side of the drying chamber. Preferably, the fixed base of the drying unit is provided with a drying gas discharge unit.
The drying gas may be an inert gas, an organic solvent gas or a mixed gas of an inert gas and an organic solvent gas.
A wafer processing system according to the present invention comprises a cleaning tank containing a cleaning liquid for cleaning wafers, a drying unit having a fixed base connected to the cleaning tank so as to surround an opening formed in the cleaning tank, and a top cover placed on the fixed base in close contact with the fixed base with a sealing member interposed therebetween, and defining a drying chamber, and a wafer holding means for holding wafers and moving wafers into the cleaning tank and the drying chamber, a first lifting means for vertically moving the top cover, and a second lifting means for vertically moving the wafer holding means. The first and the second lifting means are ball screw mechanisms sharing common guide rails.
It is preferable to extend a rod connected to the wafer holding means through a through hole formed in the top cover and to connect the same to the second lifting means, and to seal a gap between the top cover and the rod by a sealing structure having the shape of an airtight, flexible, annular tube, and filled with a gas.
Preferably, the first lifting means is provided with a stopper for limiting the upward movement of the wafer holding means relative to the top cover.
Furthermore, the wafer holding means comprises a pair of lower support members for supporting a plurality of wafers in a vertical position at suitable intervals, and a pair of upper support members disposed beside a region above the lower support members, each of the lower support members has a rigid core and a support block of a synthetic resin resistant to different kinds of cleaning liquids, each of the lower support members is provided with grooves of a substantially V-shaped cross section for receiving wafers therein, and each of the upper support members is provided with grooves of a substantially Y-shaped cross section for preventing the wafers from tilting.
According to the present invention, the drying chamber is defined by the fixed base fixed to the cleaning tank so as to surround the opening of the cleaning tank, and the top cover closely connected to the fixed base, and the top cover can be vertically moved to provide a space through which wafers are carried into the cleaning tank by lifting the top cover. Therefore, wafers can be transferred from a wafer carrying means which moves laterally into the space to the wafer holding means, and from the latter to the former. Accordingly, the cleaning and drying apparatus can be fo
Kamikawa Yuji
Kuroda Osamu
Nomura Tsuyoshi
Soejima Kenji
Coe Philip R.
Smith , Gambrell & Russell, LLP
Tokyo Electron Limited
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