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Historically diazoquinone/novolak- the two-component photosensitive material (photoresist) was efficiently used in
various industries. In the semiconductor industry it is used for the high contrast, high resolution binary image
formation for the integrated circuitry. Comparing with the silver halide photosensitive system which has Ag4
+ cluster or
T-grain sensitizing center that generates detailed gray scale (photographic density) black & white images, the
diazoquinone / novolak resist for the gray scale image formation has not been investigated thoroughly in the past.
Diazoquinone/novolak could be used in the photography field as one of the non-silver photosensitive materials and this
passive photosensitive material also has its broad exposure-energy response towards the image formation. Here in this
paper we provide this silver-halide supplement material to transfer our semiconductor photolithography binary process
experience of that resist to its photography application.
We also reported the TEM figures and the measurement data of the resist particle diameter after the photolithography
development process. The thick photoresist was coated on the aluminum substrate. Using critical dimension, CD =
2μm photomask to process several lots of wafers, the resist particles were collected and the particle size and its
distribution after the development process was obtained. Their size distribution mainly has dual separate distribution
peaks: 85% of particles have the diameter distributed around 23±3 nm and the rest 15% of bigger particles around
220±50 nm. Here in the experiment we use the standard-equivalent projection reticle to substitute the standard contact
mask to obtain 2μm CD latent images thereafter the corresponding particles throughout several lots. Because of the
unique role of DNQ, which is both the photo-sensitizer and the development inhibitor before its exposure, the correlation
of the resist particle size with respect to the developer concentration, the size of the radius of gyration, the
"photosensitizing center" and the "development center" is speculated. Generally the particle size distribution is mainly
correlated to the developer concentration, possibly also to the polymer resin molecular weight and the polymer / PAC
ratio etc.
We added our study of its photochemistry property (here specifically the UV-vis absorbance or optical density), provided
its spectroscopic response figures with respect to the sequentially increased exposure of the resist on quartz (250 - 550
nm and 300 - 450 nm). The relationship of the photographic contrast and its photochemistry property of the resist was
briefed.
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