Silylated poly(4-hydroxystyrene)s and radical polymerized 4-tert-butyldimethylsilyloxystyrene (TBDMSOSt) were examined as electron beam resists. Commercial poly(4-hydroxystyrene) (PHS) with M-w = 1.69 x 10(4) and M-w/M-n = 5.41 was silylated with 1-(trimethylsilyl)imidazole and tert-butylchlorodimethylsilane. Both silylation reactions proceeded quantitatively to afford trimethylsilylated PHS with M-w = 3.93 x 10(4) and M-w/M-n = 4.91, and tert-butyldimethylsilylated PHS with M-w = 4.08 x 10(4) and M-w/M-n = 3.81. These 2 silyl ether polymers acted as a negative working resist to electron beam (EB) exposure. Sensitivity and contrast of tert-butyldimethylsilylated PHS were not affected by prebake temperature around its T-g of 97 degrees C, while those of PHS were dependent on prebake temperature around its T-g of 160 degrees C. At a prebake temperature of 125 degrees C, the sensitivity parameter D-g(0.5) and the contrast gamma value were obtained as follows : 3.93 x 10(-4) C cm(-2) and 0.91 for PHS; 1.49 x 10(-4) C cm(-2) and 1.06 for trimethylsilylated PHS; 1.84 x 10(-4) C cm(-2) and 1.44 for tert-butyldimethylsilylated PHS. The silylation procedures obviously improved the sensitivity of PHS. TBDMSOSt was polymerized in bulk at 60 degrees C with 2,2＇-azobisisobutyronitrile (AIBN) as an initiator. The resultant poly(TBDMSOSt) possessed M-w = 3.01 x 10(5) and M-w/M-n = 1.92 and exhibited a sensitivity D-g(0.5) of 1.60 x 10(-5) C cm(-2) and a gamma value of 1.47. More than 10 times enhancement of sensitivity was observed compared with tert-butyldimethylsilylated PHS. Such a high sensitivity is probably due to the high molecular weight of the bulk polymerized material. Poly(TBDMSOSt) resolved an isolated line of 0.20 mu m width and 0.5 mu m line and space patterns.