Rumiko Horiguchi

Polysiloxanes with a Phenol Moiety for Bilayer Photoresist Applications

Novel Polysiloxanes with a phenol pendant group were synthesized and applied to bilayer photoresists for g-line and deep-UV (248 nm) lithography. These polymers had adequate aqueous-base solubility and oxygen-RIE resistance to serve as the base resin component for top imaging resists in bilayer resist systems. One of these polysiloxanes was synthesized from chlorodiethoxyphenylsilane and m-trimethylsiloxychlobenzene. Others were synthesized from dichlorophenylsilane and phenol and phenols with a double bond moiety (eugenol, isoeugenol and m-isopropenylphenol). These polysiloxanes had from 9.8 wt.% to 13.1 wt.X Si content and displayed an oxygen-RIE resistance 10 times greater than novolak resin. The m.p. values for these polymers ranged from 30°C to 90°C. The UV transmittance value (at 248 nm, 1 micron thickness) were from 7 % to 76 X. Resists were prepared from these polysiloxanes and sensitizers. In g-line lithography, the sensitizer was naphthoquinonediazide. In deep-UV (248 nm) lithography, the sensitizer was selected from naphtoquinonediazide, diazide and diazo compounds. 0.5 micron line and space patterns were obtained, when the resist was exposed using a g-line stepper, and using a tetramethylammonium hydroxide solution (ca. 1.3 %). 0.4 micron line and space patterns were resolved, when the resist was exposed using a KrF excimer laser stepper, and developed using the same solution. The top layer pattern could be transferred to the bottom layer (hard baked positive resist OFPR-5000) using oxygen-RIE. The etching rate for the silicon containing resist was 35 nm/min, while that for OFPR-5000 was 555 nm/min. These polysiloxanes make it possible to obtain the fine pattern resolution required in VLSI processing.

Diazo‐β‐diketone Photoactive Compounds for KrF Excimer Laser Resists

The properties of excimer laser resists containing diazocompounds, such as R−COCN 2 CO−R, R−COCN 2 COO−R, and R−COCN 2 CONH−R, were examined. The resists consisting of the diazocompounds and polyvinylphenol were all the negative type. Ph−COCN 2 CO−Ph was the most adequate for the KrF excimer laser resist photoactive compound. Diazodiketone was decomposed by irradiation, and formed ester with phenol. Heat distortion temperature was about 140°C, which was enough to fabricate the resist patterns by reactive ion etching. The reactive ion etching durability was 1.9 times as high as that of the conventional resists. Line space patterns of 0.3 μm were fabricated by a three-layer resist process