Cleaning and liquid contact with solids – Processes – Including application of electrical radiant or wave energy...
Reexamination Certificate
1999-09-22
2002-08-13
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Including application of electrical radiant or wave energy...
C134S006000, C134S032000, C134S033000, C134S034000, C134S902000, C015S077000, C015S088100, C015S102000
Reexamination Certificate
active
06431185
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an apparatus and method for cleaning a semiconductor substrate, and in particular to an apparatus and method for cleaning a semiconductor substrate of sheet form, which make it possible to fully remove even fine particles. Specifically, this invention relates to novel cleaning method consisting of a combination of the conventional contact cleaning (Pen) and non-contact cleaning (CJ) (Cavitation-jet composite pen cleaning method: hereinafter referred to as “Cavipen cleaning method”), which enables the flat portion and recessed portion of a cleaning material to be simultaneously cleaned.
As the working dimension in the manufacture of a semiconductor device becomes increasingly finer such as in the order of submicron, even a very fine particle may become a cause for the generation of a defective product, when the particle is allowed to adhere on the surface of a semiconductor substrate to be employed in the production of a semiconductor device. Therefore, it is now demanded to develop a construction schedule control which makes it possible to completely remove such a very fine particle. Further, when a metallic impurity is allowed to adhere onto the surface of a semiconductor substrate, it may become a cause for a failure of electric characteristics even such a metallic impurity is very little in quantity, so that it is also demanded to completely remove such a metallic impurity.
To meet such a demand, there has been recently developed a method for effectively removing particles adhered onto a surface of a substrate, wherein a high pressure pure water impressed with ultrasonic wave of Mega Hertz band is employed to clean the substrate to thereby obtain a very high clean surface of the substrate. An apparatus utilizing such a method is also being developed now.
For example, a sheet cleaning type apparatus utilizing the aforementioned method is known. However, there are a problem that a mist of steam is allowed to generate in the gas phase especially when (1) a high pressure water is jetted against the surface of a semiconductor substrate, or (2) a high-frequency wave (megasonics) is impressed at the occasion of cleaning the substrate by making use of a cleaning nozzle of various type (e.g. a water jet nozzle, a cavitation jet nozzle, megasonic device-attached water jet nozzle, etc.) which is designed to be mounted on the sheet cleaning type apparatus. This mist may be re-adsorbed in a subsequent drying step after the cleaning of a semiconductor substrate, thus rendering the mist to remain as a water mark on the surface of the substrate. Otherwise, this mist may adhere to the dust in the gas phase, thus rendering the mist to be re-adsorbed as a particle on the surface of the substrate. By the way, by the expression of a high pressure water, it means a water having a pressure in the order of several Kgf/cm
2
in the case of the megasonic device-attached water jet nozzle, and a pressure in the range of several tens Kgf/cm
2
to several hundreds Kgf/cm
2
in the case of the a water jet nozzle or a cavitation jet nozzle.
In view of preventing such a mist from being allowed to generate, there has been developed a semiconductor cleaning apparatus which is provided with exhaust ports to be disposed around a semiconductor substrate so as to forcibly discharge the mist.
In the followings, the general structure of the conventional semiconductor cleaning apparatus will be explained with reference to FIG.
34
.
FIG. 34
represents a schematic view of the main portion of the conventional sheet form semiconductor substrate cleaning apparatus wherein a semiconductor substrate is placed inside the cleaning apparatus. The reference number
1
denotes the chamber of a semiconductor substrate cleaning apparatus, which is cylindrical in configuration with the top and bottom surfaces thereof being closed. A rod-like substrate holder
2
is disposed inside the chamber
1
in such a manner that it passes through a central portion of the bottom of the chamber
1
while keeping an air-tightness between the bottom of the chamber
1
and the substrate holder
2
and at the same time, ensuring the rotatability of the substrate holder
2
in relative to the bottom of the chamber
1
. This substrate holder
2
is connected at one end thereof with a rotating mechanism (not shown) which is disposed outside the chamber
1
thereby enabling the substrate holder
2
to be revolved at a high speed. The other end of the substrate holder
2
which is disposed inside the chamber
1
is connected with a substrate-mounting jig
6
. Namely, it is designed such that a semiconductor substrate
20
can be horizontally mounted on the substrate-mounting jig
6
and revolved through the rotation of the substrate holder
2
. Further, a nozzle
4
for jetting a high pressure water jet is disposed inside the chamber
1
in such a manner that the tip end
4
A of the nozzle
4
is positioned over and slightly spaced away from the top surface of the semiconductor substrate
20
. The nozzle
4
is fixingly retained, through a portion near the tip end
4
A thereof, by a nozzle frame
5
.
On the other hand, a rod-like nozzle-supporting arm
3
is disposed inside the chamber
1
in such a manner that it passes through an upper peripheral surface portion of the chamber
1
while keeping an air-tightness between the upper peripheral surface portion of the chamber
1
and the nozzle-supporting arm
3
and at the same time, ensuring the rotatability of the nozzle-supporting arm
3
in relative to the upper peripheral surface portion of the chamber
1
. This nozzle-supporting arm
3
is connected at an upper end thereof with a rotating mechanism (not shown) which is disposed outside the chamber
1
thereby enabling the nozzle-supporting arm
3
to be revolved at a predetermined range of angle. Further, a lower portion of the nozzle-supporting arm
3
which is disposed inside the chamber
1
is L-shaped with the distal end thereof being directed toward the center of the chamber
1
and fixed to the nozzle frame
5
.
According to this cleaning apparatus, when the nozzle-supporting arm
3
is rotated to a predetermined angle, the nozzle frame
5
is enabled to scan an entire area along the diametral direction of the semiconductor substrate
20
, and when the substrate holder
2
is additionally rotated, the entire surface of the semiconductor substrate
20
can be allowed to come close to the tip end
4
A of the nozzle
4
.
The nozzle
4
is designed to function also as a feeding pipe for feeding water of high pressure and hence, formed of a flexible tube such as a fine stainless steel tube or a Teflon tube. Further, while ensuring air tightness in relative to the chamber
1
, the nozzle
4
is extended out of an upper portion of the chamber
1
, leaving a sufficient length thereof inside the chamber
1
so as enable it to follow the rotation of the nozzle-supporting arm
3
. One end portion of the chamber
1
is connected with a high pressure water feeding source (not shown) thereby making it possible to continuously feed a high pressure water.
A gas inlet port
10
is formed at a central portion of the upper surface of the chamber
1
thereby making it possible to feed an inert gas such as nitrogen gas into the chamber
1
. On the other hand, an exhaust port
11
connected with an outside exhauster (not shown) is formed at a lower portion of the chamber
1
which is lower than the mounting portion of the semiconductor substrate
20
, thereby allowing an inert gas fed through the gas inlet port
10
to be discharged from this exhaust port
11
. It is possible with this construction to pass an inert gas through the chamber
1
at the occasion of cleaning the surface of the semiconductor substrate
20
by making use of an ejection of a high pressure water, thereby effectively guide and move a mist that has been generated from the high pressure water toward the exhaust port
11
together with the introduced inert gas. At the same time, the high pressure water can be also effectively discharged
Nadahara Soichi
Sato Motoyuki
Tomita Hiroshi
Gulakowski Randy
Kabushiki Kaisha Toshiba
Winter Gentle E.
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