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Solvent Lift-Off Procedure For PSTTF Negative Resists

IP.com Disclosure Number: IPCOM000048693D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kaufman, FB: AUTHOR [+2]

Abstract

Negative resists which typically operate by radiation-induced cross linking can usually only be removed by a plasma ashing procedure. This is due to the fact that the crosslinked polymer matrix does not dissolve, but only swells in a solvent. However, the novel class of polystyrene tetrathiafulvalene (PSTTF)(*) negative resists owes its radiation induced differential solubility to the production of dimer physical crosslinks. The PSTTF negative resist can be readily removed after patterning using a simple solvent wash procedure.

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Solvent Lift-Off Procedure For PSTTF Negative Resists

Negative resists which typically operate by radiation-induced cross linking can usually only be removed by a plasma ashing procedure. This is due to the fact that the crosslinked polymer matrix does not dissolve, but only swells in a solvent. However, the novel class of polystyrene tetrathiafulvalene (PSTTF)(*) negative resists owes its radiation induced differential solubility to the production of dimer physical crosslinks. The PSTTF negative resist can be readily removed after patterning using a simple solvent wash procedure.

The solvent lift-off procedure on irradiated PSTTF occurs as follows:
1. Irradiation followed by solvent development to get

an imaged pattern.
2. Acetonitrile solvent wash of resist pattern to

remove unreacted acceptor. The polymer film is no

longer photoactive.
3. After selected processing steps (see below), PSTTF

film can be removed by washing with a

DMF-hydrazine solution. In an additional

embodiment, a gaseous reducing agent, obviating

the requirement for a specific solvent for

for the hydrazine, can be used.

If the irradiation step involves UV or visible photons, undercut profiles are obtainable through a choice of the selected wavelength. In addition, after actual patterning (step 1), blanket irradiation of the remaining pattern can be used to control the morphology of the resulting polymer film by introducing a specified number of additional dimer crosslinks. Finally, it is under...