Method of pattern formation utilizing radiation-sensitive resin composition containing monooxymonocarboxylic acid ester solvent

#1. Field of the Invention

#This invention relates to a radiation-sensitive resin composition comprising a solution of an alkali-soluble resin and a radiation-sensitive compound dissolved in a solvent, which composition is sensitive to radiations such as ultraviolet rays, far-ultraviolet rays, X-rays, electron beams, molecular beams, gamma-rays, synchrotron radiations, proton beams and the like.

#2. Description of the Invention

#Under shading the light, in a 2-liter separable flask equipped with a stirrer were placed 244 g of a novolak obtained by addition condensation of a cresol mixture (m-cresol/p-cresol=6/4 by weight) and formaldehyde, 56 g of ethylene glycol di(3,4,5-trihydroxybenzoate)-1,2-naphthoquinonediazide-5-sulfonic acid pentaester and 900 g of ethyl 2-oxypropionate. The resulting mixture was stirred to form a solution. The solution was then filtered through a membrane filter having a pore diameter of 0.2 .mu.m, and the filtrate was filled in two 500-ml glass bottles, whereby a positive type radiation-sensitive resin composition was prepared. Immediately after the preparation, the composition was subjected to measurement of the number of fine particles contained therein, using an automatic fine-particles measurement tester manufactured by HIAC/ROYCO. The number of fine particles having particle diameters of at least 0.5 .mu.m was 15 per ml of the composition.

#The positive type radiation-sensitive resin composition prepared above was coated on a silicon wafer having a silicon oxide film using a spinner. The resulting coated wafer was subjected to prebaking for 25 minutes at 90.degree. C. in an oven to form a resist layer of 12 .mu.m in thickness. Then, a test pattern mask (a product of TOPPAN PRINTING CO., LTD.) was attached to the resist layer. Using an ultrahigh pressure mercury lamp as a light source, ultraviolet rays were applied to the resist layer through a test pattern mask, and the coated wafer was subjected to development for 60 seconds using an aqueous solution containing 2.4% by weight of tetramethylammonium hydroxide, whereby a pattern having a line width of 1.0 .mu.m could be resolved. The yield of residual film thickness at the unexposed portion was 95%.

#In the same manner as above, a resist pattern was formed on a silicon wafer having a silicon oxide film. The resist pattern was subjected to post-baking for 30 minutes at 130.degree. C. and then to etching for 10 minutes at 25.degree. C. using an etchant which was a 1:6 (by volume) mixture of 49% HF and 40% NH.sub.4 F. The resist was stripped off and the pin hole density on the wafer was measured. The pin hole density was 0.1 flaw/cm.sup.2. The pin hole density was determined by measuring the density of the flaws caused on the substrate by the pin holes of the resist.