Although sulfate free cleaning has reduced number of residual ions on mask surface drastically, the lifetime of
photomask has improved marginally. New haze generation mechanism in sulfate free cleaning has been studied and
evaluated based on surface properties of photomask thin film materials. It was found that haze generation is co-related
with substrate surface properties as well as ionic re-combination under ArF illumination. Based on the haze generation
study, the surface modification treatment has been studied and investigated in the view of surface energy. The surface
modification treatment increases storage lifetime as well as cumulative haze threshold energy in wafer shops.
As the industry approaches to 45nm and below lithography, resolution and pattern collapse of SRAF (Sub Resolution
Assistant Feature) on photoresist is becoming critical issues on photomask industry. The collapse of photoresist pattern
has been become a serious problem in manufacturing of fine patterns in wafer and mask industries. The presumed causes
of the resist pattern collapse are capillary forces acting on the patterns and adhesion property of the patterns. The use of
thinner resist thickness has been known as one of the most effective method among reported literatures. However,
etching resistance of present resist is still bad. Therefore it is difficult to reduce the photoresist thickness, though the
pattern size is very small.
In this paper, the available limits of resist thickness for FEP171 were calculated for several kinds of common absorber
layers as considering current dry etch capability. We focused on pattern design and collapse window for SRAF. FEP171
resist performance especially for resolution and collapse window were evaluated for both 2000Å and 3000Å thickness
with line, space, and length focused on sub 100nm features. Radial position effect and drying conditions were studied
A lot of research has been carried on sulfate free cleaning process to minimize haze generating residual ions on mask
surface. However sulfate free cleaned mask has been suffered from short life time of haze generation than we expected,
because pellicle outgassing combines with ammonium residuals and formed haze near pellicle frame area and decrease
yield. Therefore physical and PKL developed chemical surface modification treatment was studied and evaluated in term
of near pellicle haze threshold energy, surface energy of mask substrate components (Qz/MoSi/Cr), AFM and AES depth
profile. Dehydration bake treatment (physical surface modification treatment) and PKL developed chemical treatment
increased near pellicle haze threshold energy by 2.5 and 4 times, respectively. Surface modification treatments didn't
show negative effect on phase angle and transmittance losses of ArF EAPSM mask. The effect of illumination sources on
surface modification treatment was also studied.
ArF exposure tool have been implementing as a main work force of lithography. And haze generation by high actinic
wavelength energy is big issue to be resolved. Many studies have been reported to remove or minimized ion residual on
photomask surface and PKL developed haze free process. Even though the surface of photomask is free from ions
generating haze defect by haze free process, but the ions from environment like pellicle and packing box make worsen to
keep cleanness of photomask. The evaluation of environment effect like outgas from pellicle and packing box have been
reported, but it was hard to know pure environmental effect because the surface of photomask was not enough clean to
Several pellicles and boxes with different material from supplies were tested in terms of outgas, contamination of ion and
threshold energy generating haze. Some material of packing box and pellicle showed very sensitive to keep haze free
For high quality products in the semiconductor and photomask industries, exposure wavelength has been shortening
from i-line to ArF to embody the high resolution as critical dimension (CD) shrinkage and the specifications have been
restricted. However, a new defect issue called haze has appeared that is shortening the wavelength. This defect is caused
by the photoreaction of chemical residues exposed to SO42-, NH4+ and other chemicals. Accordingly, in this paper we
investigated the generation of haze in thin film materials.
For fabrication of various thin films, the materials which were metal, compound material without nitrogen, and
compound material with nitrogen, were deposited on a quartz substrate using sputtering. Then, we chemically treated the
thin film materials using various conditions including sulfuric peroxide mixture (SPM) and standard cleaning (SC-1).
First, the concentration of ions on the thin film materials was measured using ion chromatography (IC) analysis. Second,
haze defects were inspected after exposure in order to evaluate the difference in haze generation on the thin film
materials. Also, we investigated the numbers and shape of the occurrences of haze.