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Resist Hardening by E-Beam Irradiation

IP.com Disclosure Number: IPCOM000100080D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Related People

Lin, BJ: AUTHOR [+3]

Abstract

Disclosed is a photoresist hardening technique using a flood electron (E)-beam source to irradiate a developed resist pattern so that it can tolerate 200oC temperature processes, e.g., ion implantation, RIE, metal deposition, etc.

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Resist Hardening by E-Beam Irradiation

       Disclosed is a photoresist hardening technique using a
flood electron (E)-beam source to irradiate a developed resist
pattern so that it can tolerate 200oC temperature processes, e.g.,
ion implantation, RIE, metal deposition, etc.

      E-beam resist hardening is based on the ability of high energy
electrons to penetrate photoresists and to induce cross-linking.  At
25 keV, the electrons can penetrate a photoresist as thick as 10 mm.
For a typical 2 mm thick resist pattern, an energy of 10 keV  is
sufficient to harden the entire film.  In an experiment carried out
on SEM, it was observed that, after the E-beam exposure, both the
linewidth and profile of the developed resist pattern remained
unchanged up to a temperature of 250oC.  The minimum dose for
hardening is found to be   10-3C/cm2 for 10 keV electrons and   5 X
10-3C/cm2 for 25 keV electrons.  The difference is believed to be due
to the deeper penetration of 25 keV electrons into the substrate
rather than being absorbed in the resist film.  No pre-bake or
two-step post bake is needed in E-beam hardening.

      The penetration power of electron beams offers a unique
advantage in resist hardening.  In deep UV hardening, for example,
only the top 0.2 mm of the resist film becomes cross-linked because
of the severe optical absorption of photoresist at wavelengths below
300 nm.  As a result, the unhardened resist interior can still flow
at 160oC - 20...