Laser processing chamber with cassette cell

Details Laser processing chamber with cassette cell Laser processing chamber with cassette cell

1998-04-28

2000-09-26

Bueker, Richard

Adhesive bonding and miscellaneous chemical manufacture

Differential fluid etching apparatus

With microwave gas energizing means

134 13, 438795, 21912186, C23F 102

Patent

active

061238031

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to U.V. laser surface treatment methods, particularly to the removal of foreign materials from substrate surfaces. More particularly, the invention relates to a process chamber for the aforesaid purposes, which provides effective dry laser stripping and cleaning.


BACKGROUND OF THE INVENTION

In the manufacturing of various products it is necessary to apply a layer of protective material on a surface, which must be removed after a specified manufacturing step has been concluded. An example of such process is the so-called "masking", where a pattern is created on a surface using a layer of protective material illuminated through a mask, and the surface is then treated with a developer which removes material from the unmasked portions of the surface, therefore leaving a predetermined pattern. The surface is then treated by ion implantation or by etching agents, which introduce the implanted species into the unmasked portions of the surface, or removes material from unmasked portions. Once these processes are completed, the role of the protecting mask ends and it must be removed. The process is conventional and well known in the art, and is described, e.g., in U.S. Pat. No. 5,114,834.
Two main photoresist stripping methods exist in the modern VLSI/ULSI (Very/Ultra Large Scale Integration) circuits industry: U.V./O.sub.3 -based stripping.
Both methods are problematic and far from being complete, especially when taking into consideration the future miniaturization in the VLSI/ULSI industry. The current technology is capable of dealing with devices having feature sizes of about 0.5 .mu.m, but before the end of the century the expectation is that the workable size of the devices is expected to be reduced to 0.25 .mu.m. The expected size changes require considerable changes in the manufacturing technology, particularly in the stripping stage. The prior art photoresist stripping techniques described above will be unsuitable for future devices, as explained hereinafter.
Utilizing only the wet stripping method is not a perfect solution, as it cannot completely strip photoresist after tough processes that change the chemical and physical properties of the photoresist in a way that it makes its removal very difficult. Such processes include, e.g.,. High Dose Implantation (HDI), reactive Ion Etching (RIE), deep U.V. curing and high temperatures post-bake. After HDI or RIE the side walls of the implanted patterns or of the etched walls are the most difficult to remove.
In addition, the wet method has some other problems: the strength of stripping solution changes with time, the accumulated contamination in solution can be a source of particles which adversely affect the performance of the wafer, the corrosive and toxic content of stripping chemicals imposes high handling and disposal costs, and liquid phase surface tension and mass transport tend to make photoresist removal uneven and difficult.
The dry method also suffers from some major drawbacks, especially from metallic and particulate contamination, damage due to plasma: charges, currents, electric fields and plasma-induced U.V. radiation, as well as temperature-induced damage, and, especially, incomplete removal. During various fabrication stages, as discussed above, the photoresist suffers from chemical and physical changes which harden it, and this makes the stripping processes of the prior art extremely difficult to carry out. Usually a plurality of sequential steps, involving wet and dry processes are needed to remove completely the photoresist.
The art has addressed this problem in many ways, and commercial photoresist dry removal apparatus is available, which uses different technologies. For instance, UV ashers are sold, e.g. by Hitachi, Japan (UA-3150A), dry chemical ashers are also available, e.g., by Fusion Semiconductor Systems, U.S.A., which utilize nitrous oxide and ozone to remove the photoresist by chemical ashing, microwave plasma ashing is also effected, e.g., as in the UNA-200 Asher (ULVAC Japa

REFERENCES:
patent: 4752668 (1988-06-01), Rosenfield et al.
patent: 5024968 (1991-06-01), Engelsberg
patent: 5099557 (1992-03-01), Engelsberg
patent: 5114834 (1992-05-01), Nachshon

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