lactate and carrying out the post baking at 100 u00b0 c for 50 sec and the development for 60 sec in an aqueous 2 38 wt tetramethylammonium hydroxide solution the pattern obtained was found to have a good cross section 0 35 u03bcm thick at an exposure energy of 10 mj cm 2 as observed with an electron microscope a similar procedure to that of example i was repeated except for preparing a resist solution by dissolution of 100 weight parts of resin xvi obtained in synthesis example xix and 3 5 weight parts of triphenylsulfonium triflate in 300 weight parts of ethyl lactate and carrying out the post baking at 100 u00b0 c for 50 sec and the development for 60 sec in an aqueous 2 38 wt tetramethylammonium hydroxide solution the pattern obtained was found to have a good cross section 0 35 u03bcm thick at an exposure energy of 15 mj cm 2 as observed with an electron microscope a similar procedure to that of example i was repeated except for using 2 0 weight parts of triphenylsulfonium hexafluoroantimonate instead of triphenylsulfonium triflate the pattern obtained was found to have a good cross section 0 40 u03bcm thick at an exposure energy of 20 mj cm 2 as observed with an electron microscope as described hereinbefore the present invention is a polymer which can be sensitive to uv light deep uv light excimer laser x ray and electron base on the positive chemical amplified photoresist composition based on the polymer which is superior in thermal resistance resolution and storage preservativity and can afford resist patterns of excellent profile irrespective of the substrates employed the present invention has been described in an illustrative manner and it is to be understood the terminology used is.