Organic Monolayers Covalently Bonded to Si as Ultra Thin Photoresist Films in Vacuum UV Lithography

Self-assembled monolayers (SAMs) covalently attached to Si(111) substrates through Si–C or Si–O–C chemical bonds have been synthesized using chemical reactions of 1-hexadecene or 1-hexadecanol with Si(111) substrates terminated with hydrogen and, applied as ultra thin resist films of about 2 nm thick in photolithography based on vacuum UV light at a wavelength of 172 nm. The SAMs were so uniform that the surface structure of the Si substrates consisting monoatomic steps and atomically flat terraces remained even after the SAM formation. Furthermore, the SAMs showed excellent chemical resistivities to HF and were successfully applied to masks for Si oxide etching.