AVS 62nd International Symposium & Exhibition
    Electronic Materials and Processing Wednesday Sessions
       Session EM+AS+MS+SS-WeA

Paper EM+AS+MS+SS-WeA3
Hydrogen Desorption from 6H-SiC (0001) Surfaces

Wednesday, October 21, 2015, 3:00 pm, Room 211C

Session: Surface and Interface Challenges in Wide Bandgap Materials
Presenter: Sean King, Intel Corporation
Authors: S.W. King, Intel Corporation
R. Nemanich, North Carolina State University
R. Davis, North Carolina State University
Correspondent: Click to Email
Due to the extreme chemical inertness of silicon carbide (SiC), in-situ thermal desorption is commonly utilized as a means to remove surface contamination prior to initiating critical semiconductor processing steps such as epitaxy, gate dielectric formation, and contact metallization. In-situ thermal desorption and silicon sublimation has also recently become a popular method for epitaxial growth of mono and few layer graphene. Accordingly, numerous thermal desorption experiments of various processed silicon carbide surfaces have been performed, but have ignored the presence of hydrogen which is ubiquitous throughout semiconductor processing. In this regard, we have performed a combined temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS) investigation of the desorption of molecular hydrogen (H2) and various other oxygen, carbon, and fluorine related species from ex-situ aqueous hydrogen fluoride (HF) and in-situ thermal and remote hydrogen plasma cleaned 6H-SiC (0001) surfaces. Using XPS, we observed that temperatures on the order of 700 - 1000°C are needed to fully desorb C-H, C-O and Si-O species from these surfaces. However, using TPD, we observed H2 desorption at both lower temperatures (200 – 550°C) as well as higher temperatures (> 700°C). The low temperature H2 desorption was deconvoluted into multiple desorption states that, based on similarities to H2 desorption from Si (111), were attributed to silicon mono, di, and trihydride surface species as well as hydrogen trapped by sub-surface defects, steps or dopants. The higher temperature H2 desorption was similarly attributed to H2 evolved from surface O-H groups at ~ 750°C as well as the liberation of H2 during Si-O desorption at temperatures > 800°C. These results indicate that while ex-situ aqueous HF processed 6H-SiC (0001) surfaces annealed at < 700°C remain terminated by some surface C-O and Si-O bonding, they may still exhibit significant chemical reactivity due to the creation of surface dangling bonds resulting from H2 desorption due from previously undetected silicon hydride and surface hydroxide species.