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Focused Ultrasound for Microscopic Patterning of Polymers

IP.com Disclosure Number: IPCOM000120195D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Braren, B: AUTHOR [+3]

Abstract

We have found a new method for patterning polymers with micron sized features using ultrasound rather than conventional patterning that uses photoresist or laser ablation. At present our feature size is in the 100 micron range but we fully expect that 1-10 microns can be achieved by going to higher acoustic frequencies than we have so far used. With a 10 MHz soundwave in water, localized swelling or the formation of ridges and/or holes results when the ultrasound is focused onto polyimide (Kapton). The smallest feature size at 10 MHz is between 50-100 microns, close to the diffraction limited spot size of the acoustic beam.

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Focused Ultrasound for Microscopic Patterning of Polymers

      We have found a new method for patterning polymers with micron
sized features using ultrasound rather than conventional patterning
that uses photoresist or laser ablation.  At present our feature size
is in the 100 micron range but we fully expect that 1-10 microns can
be achieved by going to higher acoustic frequencies than we have so
far used.  With a 10 MHz soundwave in water, localized swelling or
the formation of ridges and/or holes results when the ultrasound is
focused onto polyimide (Kapton).  The smallest feature size at 10 MHz
is between 50-100 microns, close to the diffraction limited spot size
of the acoustic beam. Patterning is achieved by submerging the
spherically shaped front surface focusing transducer (Precision
Acoustic Devices, Fremont, CA) in water and directing the focused
beam at the polymer, also submerged in water. Experimentally, for a
50-micron-thick sheet of Kapton (Dupont Reg. TM) we have observed
patterns in the form of raised ridges,   20-30 microns high, 100
microns wide for an effective incident acoustic power level of only
1000 W/cm2 with the substrate scanned at 250 microns/s.  Similar
patterns have been fabricated on polymethylmethacrylate (PMMA).  With
an acoustic microscope in the gigahertz range, the pattern will be
smaller in proportion to the reduced wavelength, i.e., on the order
of 1 micron.  This type of patterning in Kapton and other polymers is
ideally s...