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A Negative Bias, Positive Tone T-Boc Resist Process for Sub-0.5mm Lithography With P.E. 500 UV-2 Exposures

IP.com Disclosure Number: IPCOM000120166D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 54K

Publishing Venue

IBM

Related People

Collini, GJ: AUTHOR [+2]

Abstract

A novel resist (modification of t-Boc) having a negative print bias in positive mode, is described in this article. The disclosed resist process permits the generation of sub-micron features with existing photolithographic tooling and allows for a reduction of large image masks.

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This is the abbreviated version, containing approximately 65% of the total text.

A Negative Bias, Positive Tone T-Boc Resist Process for Sub-0.5mm
Lithography With P.E. 500 UV-2 Exposures

      A novel resist (modification of t-Boc) having a negative print
bias in positive mode, is described in this article. The disclosed
resist process permits the generation of sub-micron features with
existing photolithographic tooling and allows for a reduction of
large image masks.

      Applications of existing optical lithographic tooling can be
extended by utilizing certain chemical processes to generate
sub-micron images, i.e., patterns, with savings in optical hardware
expense.  Basically, the t-Boc resist is composed of a t-Boc polymer,
a sensitizer salt, and a casting solvent.  The polymer decomposes
thermally (T > 140oC) to para-hydroxy styrene polymer plus carbon
dioxide (C02) and isoprene gases.  The decomposition temperature is
lowered to   70-130oC in the presence of catalytic amounts of acid
formed when the salt is exposed to D.U.V. light.

      Imaged t-Boc resist can be developed by either dissolving the
unexposed and unconverted t-Boc in anisole (negative tone) or by
dissolving away the exposed and converted pHost in isopropyl alcohol
(positive tone).

      By way of example,
   a)  The resist is coated, spun dry, and soft baked at 97oC for one
minute.
   b)  3%wt/wt pHost in isopropyl alcohol is applied and spun at 5K
rpm followed by a bake at 130oC for 5 minutes.
   c)  The image is exposed to P.E. 500 UV-2 at 25 mJ...