Application of Diazonaphthoquinone / Novolak Photosensitive Material for Photography Image Formation

摘要

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 Ag_4~+ 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.