B and Ga Co-Doped Si1-xGex for p-Type Source/Drain Contacts

Abstract Contact resistivity reduction at the source/drain contacts is one of main requirements for fabrication future MOS devices. Current research focuses on methods to increase active doping concentration near contact region in silicon-germanium S/D epilayers. A possible approach consists adding co-dopants during epitaxy process. In case p-MOS, gallium can be used addition boron. this work, properties situ Ga and B co-doped Si 0.55 Ge 0.45 layers are discussed. The surface morphologies, layer compositions, structural electrical material described compared with those a B-doped reference layer. segregation occurring growth evidenced. Post-epi cleans required obtain correct profiles 1-x x from secondary ion mass spectrometry, otherwise altered by knock-on. crystalline quality, show progressive degradation increasing dose. Finally, specific titanium-Si :B(:Ga) values have been extracted using multi-ring circular transmission line method. lower samples, lowest value (< 3 10 -9 Ω.cm 2 ) being obtained sample grown Ga-precursor flow.