We investigated the fabrication of diamond-like carbon (DLC) emitter patterns by
room-temperature curing nanoimprint lithography (RTC-NIL) with
polydimethylsiloxane (PDMS) molds using polysiloxane, as an application to the
emitter for the next generation flat panel display.
The DLC which has excellent properties similar to diamond properties was used as
a pattern material. A PDMS was used as a mold material and fabricated by the
following optimum conditions of the first curing time at RT for 36 h and the
second curing time at the temperature of 150 °C for 15 mins. The
polysiloxane is in the state of sticky liquid at RT and stable in air.
Therefore, the polysiloxane was used the electron beam (EB) resist and oxide
mask material in EB lithography, and also used as RT-imprint material.
First, we fabricated the PDMS mold with pit array. Each dot is 5
µm-diameter and 400 nm-depth. We carried out the RTC-NIL process with
PDMS molds using polysiloxane under the following optimum imprint conditions of
0.5 MPa-imprinting pressure, 1.5 min-the time between spin-coat and imprint, and
5 min-imprinting time. Next, the residual layer of imprinted polysiloxane
pattern was 450 nm and then was removed with electron cyclotron resonance (ECR)
trifluoromethane (CHF3) ion shower under the conditions of 300 eV-ion
energy and 3 min-etching time. Then, we processed the imprinted polysiloxane
patterns on the DLC film with an ECR oxygen (O2) ion shower under the
conditions of 400 eV-ion energy and 12 min-etching time. As a result, we
succeeded in fabricating convex DLC emitter patterns with high accuracy which
has 5 µm-diameter and 500 nm-height.