Glen Spectra offers a new
generation, after-market i-line interference filter designed for
litho tools in the photolithography process, such as LSI and LCD
Steppers with high power Mercury Lamps. This high performance and
environmentally stable bandpass filter resolves monochromatic
wavelengths reaching the photomask substrate so that optimum
resolution is achievable. We have designed a filter that efficiently
transmits the five lines of the fine structure of the Mercury i-line
with bandwidth, centre wavelength, and filter construction designed
to allow maximum throughput and filter life. Significant improvements
have been engineered into this after-market filter. We offer custom
engineered filters as well as standard i-line filters.
Glen Spectra's new
generation i-line filters feature greatly improved i-line intensity
delivered to the resist, surpassing the standard OEM filters. We have
refined our coating designs and developed a consistently reliable
coating process, resulting in compressed delivery schedules. All
filters are thoroughly characterised photometrically. In addition,
all filters are qualified to the highest manufacturing standards and
are packaged in a nitrogen-purged ESD bag.
The filter is manufactured
using durable oxide films, which are deposited via electron beam with
ion-assist, to assure stability over time and varying environmental conditions.
Purified fused silica
substrates, rather than borosilicate, are used to assure the highest
optical quality and spectral stability.
Volatile epoxies, which
are the source of out-gassing and resulting degradation of intensity and/or
uniformity, have been eliminated in contrast with many OEM filters.
Omega's i-line filters are
thoroughly characterized photometrically. The bandpass transmission
is evaluated along 4 radii at ½ " intervals (125 &
165mm diameter product) using a research-grade spectrophotometer. A
filter with uniform bandpass characteristics across the entire
surface yields the greatest intensity delivered to the resist. Our
filters typically exceed intensity levels offered by OEM replacement
filters by 10-20%.
Omega Optical manufactures
i-line filters in series, dedicating evaporators solely to the
narrow-band coatings required for this product. This controls key
process parameters in real-time and identifies and eliminates
unexpected variables. The result is a product that is consistent on a
lot-to-lot basis, as well as across the surface of the individual
coated filter. This manufacturing strategy results in improved
deliveries and cost savings for customers due to higher coating yields.
photolithography brochure (pdf, 389k)
Omega Optical offers mask
aligner optical filters which provide improved exposures and sharper,
straighter feature walls of the SU-8 photoresist. This filter
provides a nominal cut-on wavelength of 360nm, blocking shorter
wavelengths and transmitting the longer wavelengths including the
useful 365, 405 & 436nm mercury lines. It is 90% transparent to
visible light (or provides 90% transmission), allowing for proper
visualization of mask alignment through the filter glass.
MicroChem Corp recommends
Omega Optical's PL-360LP optical filter for use with its SU-8 photoresist.
Mask Aligner Filters