Effects of Platinum Silicide Formation on Si1-yCy Epitaxial Layers and Thermal Stability

• Main Authors: Yi-Ping Lin, 林依頻
• Other Authors: Sheng-Wei Lee
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/01152029825856939751

碩士 === 國立中央大學 === 材料科學與工程研究所 === 99 === Strain　engineering　is　commonly　used　for　improving　the　performance　of　metal-oxide-semiconductor　(MOS)　devices.　For　example,　n-channel　MOS　(NMOS)　devices　with　silicon-carbon　　(Si1-yCy)　grown　in　the　source　and　drain　(S/D)　regions　as　uniaxial　compressive　stressors　for　the　channel　can　achieve　significant　drive　current　improvements.　However,　successfully　integrating　Si1-yCy　epilayers　into　a　standard　device　process　flow　requires　reliable　metal-silicide　contacts　in　the　Si1-yCy　S/D　regions.　Pt　silicide　formed　on　p-type　silicon　has　a　low　Schottky　barrier　height,　which　useful　as　Schottky　transistors.　However,　Pt　silicide　has　poor　thermal　stability.　In　this　study,　the　reaction　between　Pt　and　Si1-yCy　epilayers　with　an　interfacial　oxide　layer　was　investigated.　Pt　silicide　has　inevitable　oxide　layer,　which　as　a　diffusion　barrier　layer.　During　the　silicidation,　Pt　atoms　diffused　to　react　with　Si　through　the　oxide　pinholes.　C　atoms　play　a　critical　role　in　Pt　silicide　microstructure　and　reaction.　The　presence　of　C　atoms　retards　the　growth　kinetics　of　PtSi　and　significantly　enhances　the　thermal　stability　of　PtSi　thin　films.　In　addition,　C　atoms　suppressed　PtSi　agglomeration　and　widened　the　process　window　of　low-resistivity　PtSi　silicides.　On　the　other　hand,　the　thermal　stability　of　Pt　silicides　in　the　Pt/Si1-yCy　samples　was　found　to　be　significantly　improved,　even　after　long-time　annealing　at　800　℃.　 In　recently　years,　channel　strain　has　been　becoming　a　promise　technique.　Strain　distribution　with　different　depth　of　annealed　Si1-yCy　epilayers　using　lattice　strain　analysis　were　investigated　in　this　study.　At　the　initial　stage　of　annealing,　the　strain　of　Si1-yCy　epilayers　increased.　The　Cs　increased　0.001　in　the　Si1-y2Cy2　epilayers　sample　annealed　at　800　℃.　Lattice　strain　analysis　was　performed　using　high-resolution　transmission　electron　microscopy　(HRTEM)　and　diffractograms　obtained　by　fast　Fourier　transform　of　HRTEM　images.　The　magnitude　of　compressive　strain　was　larger　towards　Si1-y2Cy2　epilayers　sample　surface.　It　speculates　that　C　atoms　at　interstitial　sites　were　incorporated　into　substitutional　sites　after　annealing,　resulting　in　Cs　and　strain　increment.　In　addition,　no　strain　relief　by　the　introduction　of　misfit　dislocations　was　detectible　in　the　Si1-y2Cy2　epilayers　sample　after　annealing　900℃,　possibility　due　to　the　formation　of　carbon-containing　interstitial　complexes.