SOFT-X-RAY PHOTOCHEMISTRY OF CHEMISORBED SELF-ASSEMBLED MONOLAYERS

The first results of the effect of monochromatic soft x-ray exposure o f self-assembled monolayers (SAMs) of iodomethylphenylsilyl groups che misorbed on the native oxide surface of a Si substrate are presented. The SAMs, combined with a subsequent selective metallization process, have already been shown to be an effective resist system for projectio n x-ray lithography and show great promise as an e-beam resist. The fi rst conclusive evidence is presented for the loss of iodine from the S AM during soft x-ray exposure. The loss of iodine in the exposed areas allows the selective deposition of an etch resistant metal in the une xposed areas. The SAMs also provide a model system for the study of re sists at the molecular level, and the role of photogenerated electrons in determining sensitivity and resolution. The concentration of iodin e left on the surface during monochromatic exposure was monitored usin g photoemission. The loss of iodine with exposure was then fit with a double exponential. The photon energy dependence of the decay rates ar e measured and presented for photon energies 75-108 eV. The SAM sensit ivity is shown to correlate with photoelectrons generated from the Si native oxide surface.