Radiation-Induced Modifications of Allylamino-Substituted Polyphosphazenes
Efforts to synthesize allylamino-substituted polyphosphazenes and characterize their sensitivity to radiation and determine the value of using such polymers as new and better resist materials for microlithographic applications continues. An initial attempt to synthesize an amino-substituted polyphosphazene specifically tailored toward providing better resist properties was unsuccessful in that the polymer was quite radiation insensitive. The elastomeric models of an earlier study led us to the realization that the addition of aIlylic substituents might enhance the radiation sensitivity of such polymers significantly. Also, these amino-substituted polyphosphazenes were found to exhibit the glassy, thermal, and film forming properties required for conventional resists. Other potentially favorable resist characteristics of these polyphosphazenes includes relatively high RIE and high temperature resistance and good adhesion to SiO2 substrates. This work indicates our progress involving the use of these polymer systems including results for G(X) values. (a measure of the efficiency of crosslinking) and grafting attempts to induce complete solubility changes. Silicon wafers coated with thin films of the allylamino-substituted polyphosphazenes were patterned with E-beam lithographic techniques and illustrated excellent sensitivity (<6 μC/cm2) and resolution (to 0.1 μm).
