Application of ozonated DI water to scrubbers for resist...

Cleaning and liquid contact with solids – Processes – Including application of electrical radiant or wave energy...

Reexamination Certificate

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Details

C134S002000, C134S018000, C134S019000, C134S025400, C134S902000

Reexamination Certificate

active

06634368

ABSTRACT:

FIELD OF THE INVENTION
The invention is generally related to the field of resist patterning of semiconductor devices and more specifically to resist strip and resist residue removal processes.
BACKGROUND OF THE INVENTION
In the fabrication of semiconductor devices, photoresist patterns are routinely used for delineating certain areas of the semiconductor device, for example, for patterned etching and ion implantation. After the etch or implantation sequence, the resist pattern must be removed. This is referred to as a resist strip. Additionally, any resist residue must also be removed. Currently, an ozonated H
2
SO
4
operated at 130° C. or a combined solution of H
2
SO
4
and H
2
O
2
are widely used for resist strip. To reduce particles, the above resist strip process is followed by a SC
1
(H
2
O:NH
4
OH:H
2
O
2
) megasonic cleanup. Alternatively, a deionized water (DIW) scrub may be used for particle removal.
Unfortunately, the chemicals described above for resist strip are not environmentally safe and require special precautions for handling and disposal. Furthermore, sulfur compounds have been found to be left on wafer surfaces after the H
2
SO
4
cleanups, which may cause corrosions or work function shifts on devices. The SC
1
clean-up may result in NH
3
abatement. If the alternative DIW scrub is used, two process tools are required. Accordingly, a resist strip and particle removal process is desired that is environmentally safe and overcomes the above mentioned particle removal problems.
U.S. Pat. No. 5,464,480 describes a process for removing organic materials such as photoresist without the use of H
2
SO
4
and H
2
O
2
. Wafers are placed in a tank containing chilled deionized water. Ozone is diffused into the chilled deionized water to oxidize the organic material from the wafer surface. This process requires the addition of a chiller to current process equipment.
SUMMARY OF THE INVENTION
One aspect of the invention is a combined resist strip and particle removal process that uses ozonated deionized water at elevated temperatures in a scrubber. Both resist strip and particle removal are accomplished using a single scrubber step instead of two steps (a bench resist strip and a megasonic cleanup for particle removal).
Another aspect of the invention is a canister for use in forming the ozonated deionized water. The canister is filled with deionized water. The deionized water is circulated through the canister and ozone is added at a premixer stage. A dissolved ozone monitor may be used to monitor the ozone level and shut off the ozone when the ozone concentration reaches a set point.
An advantage of the invention is providing a single step resist strip and particle removal process that is environmentally safe.


REFERENCES:
patent: 5464480 (1995-11-01), Matthews
patent: 6273108 (2001-08-01), Bergman et al.
patent: 6345630 (2002-02-01), Fishkin et al.
patent: 0548 596 (1993-06-01), None

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