A comparison of the E-beam and UV-sensitivities and relative O₂- plasma stabilities of organosilicon polymers.Part II. Lithographic characteristics of polysilphenylene siloxanes and some organic polymers with pendant silyl groups

Abstract

A study of the UV- and E-beam sensitivities of exactly alternating silphenylene-siloxane copolymers and organic polymers with pendant silyl groups will be presented. These polymers can be used as imageable barrier layers for pattern transfer for fine line lithography using O2 -plasmas. These copolymers exhibit a remarkable thermal stability for linear polymers. TGA data shows that in nitrogen, the onset of degradation starts at 400 - 450°C and for the vinylmethyl containing copolymers, the weight remaining after 700°C is 75%, making these materials potentially useful as imageable dielectrics. These polymers can be sensitized to the deep UV using free radical initiators such as 2,2-Dimethoxy-2-phenyl acetophenone (Irgacure 651). the sensitivity of lb at 2537Å is 20 mJ/cm2. with a contrast (γ) of 1.0. High resolution patterns have been demonstrated on the PE 500 exposure system. E-beam sensitivities of at 20 kV were between 2 and 5 uc/cm2 (50% thickness remaining). A study of the sensitivities of organic polymers with pendant silyl groups showed that poly(trimethylsily)propyne films when irradiated at 2537Å form positive tone images after development, possibly due to the chain scission mechanism, with the formation of 1,3,5-tris(trimethylsilyl)-2,4,6-trimethylbenzene, although the sensitivity is low. The etch rates of both types of polymers in an 02 plasma at 10 mtorr and 0,15 watts/C.M2 was low due to the high silicon content (about 35-100Å/min). © 1987.