AVS 46th International Symposium
    Electronic Materials and Processing Division Tuesday Sessions
       Session EM-TuM

Invited Paper EM-TuM2
Infrared Spectroscopy as a Probe of Semiconductor/Dielectric Interfaces: Growth and Structure of SiO@sub 2@ on Si

Tuesday, October 26, 1999, 8:40 am, Room 608

Session: Si Surface Chemistry and Etching, Passivation, and Oxidation
Presenter: K.T. Queeney, Bell Laboratories, Lucent Technologies
Authors: K.T. Queeney, Bell Laboratories, Lucent Technologies
M.K. Weldon, Bell Laboratories, Lucent Technologies
Y.J. Chabal, Bell Laboratories, Lucent Technologies
K. Raghavachari, Bell Laboratories, Lucent Technologies
Correspondent: Click to Email
The structure and quality of the Si/SiO@sub 2@ interface are crucial to the performance of transistors with gate oxide thicknesses < 20 Å. We have exploited the intrinsic sensitivity of infrared absorption spectroscopy to microscopic chemical environment in order to elucidate structural details of this interface between crystalline Si and amorphous SiO@sub 2@. Infrared spectra of thermally grown SiO@sub 2@ are acquired as a function of film thickness by etchback of device-quality films. Modeling the mechanical and optical properties of these films reveals that substoichiometry at the Si/SiO@sub 2@ interface dominates the spectra of ultrathin (< 10 Å) SiO@sub 2@; different thermal histories are shown to affect the quality of this "transition region." To understand the microscopic structure of this interfacial substoichiometry, we have grown and characterized a model Si/SiO@sub x@ interface via controlled H@sub 2@O reaction of Si(100)-(2x1) in ultrahigh vacuum. Coalescence of dimer-based silicon epoxide species (capped by triangular Si-O-Si linkages) into an extended silicon-oxygen network results in the birth of SiO@sub x@ phonon modes (975 and 1130 cm@super -1@) whose microscopic structural origins are for the first time well understood. This epoxided interface is trnasformed at room temperature into high-quality SiO@sub 2@, and the mechanism for room-temperature H@sub 2@O-induced oxidation is compared to that observed for technologically relevant surface terminations.