Xingbo Liang

Oxygen precipitation in 1020 cm−3 germanium-doped Czochralski silicon

We have investigated the effects of germanium (Ge)-doping at the level of 1020 cm−3 on oxygen precipitation (OP) behaviors in Czochralski (CZ) silicon subjected to different low-high two-step anneals without or with prior high temperature rapid thermal processing (RTP). It is found that Ge-doping remarkably suppresses OP in CZ silicon without prior RTP. However, Ge-doping significantly enhances OP in CZ silicon with prior RTP. The suppressed OP in the case of the absence of prior RTP is primarily due to the fact that the 1020 cm−3 Ge-doping introduces compressive strain into silicon crystal lattice, which increases the critical size of oxygen precipitate nuclei for a given nucleation temperature. Moreover, it is revealed that the 1020 cm−3 Ge-doping facilitates the formation of vacancy-oxygen (V-O) complexes and may introduce Ge-V-O complexes in CZ silicon during high temperature RTP. More vacancy-related complexes in CZ silicon not only reduce the critical size of oxygen precipitate nuclei but also provi...

Enhanced red electroluminescence from a polycrystalline diamond film/Si heterojunction structure

Strongly enhanced red electroluminescence (EL) was realized at room temperature (RT) from a polycrystalline diamond film (PDF)∕n−-Si heterojunction fabricated by direct chemical vapor deposition of PDF on silicon substrate. The red EL peaks featuring fairly narrow linewidth (∼12nm) were obtained when the device was under sufficient reverse bias with the positive voltage applied on the silicon substrate. Cathodoluminescence spectra measured from 77K to RT suggested that the enhanced red EL peaks originated from the neutral vacancy induced intrinsic defects of the PDF rather than the Si-related centers. The carrier transport mechanism of the PDF∕n−-Si heterojunction was elucidated based on the proposed energy band diagram of the PDF∕n−-Si heterojunction.

Comparison on mechanical properties of heavily phosphorus- and arsenic-doped Czochralski silicon wafers

Heavily phosphorus (P)- and arsenic (As)-doped Czochralski silicon (CZ-Si) wafers generally act as the substrates for the epitaxial silicon wafers used to fabricate power and communication devices. The mechanical properties of such two kinds of n-type heavily doped CZ silicon wafers are vital to ensure the quality of epitaxial silicon wafers and the manufacturing yields of devices. In this work, the mechanical properties including the hardness, Young’s modulus, indentation fracture toughness and the resistance to dislocation motion have been comparatively investigated for heavily P- and As-doped CZ-Si wafers. It is found that heavily P-doped CZ-Si possesses somewhat higher hardness, lower Young’s modulus, larger indentation fracture toughness and stronger resistance to dislocation motion than heavily As-doped CZ-Si. The mechanisms underlying this finding have been tentatively elucidated by considering the differences in the doping effects of P and As in silicon.Heavily phosphorus (P)- and arsenic (As)-doped Czochralski silicon (CZ-Si) wafers generally act as the substrates for the epitaxial silicon wafers used to fabricate power and communication devices. The mechanical properties of such two kinds of n-type heavily doped CZ silicon wafers are vital to ensure the quality of epitaxial silicon wafers and the manufacturing yields of devices. In this work, the mechanical properties including the hardness, Young’s modulus, indentation fracture toughness and the resistance to dislocation motion have been comparatively investigated for heavily P- and As-doped CZ-Si wafers. It is found that heavily P-doped CZ-Si possesses somewhat higher hardness, lower Young’s modulus, larger indentation fracture toughness and stronger resistance to dislocation motion than heavily As-doped CZ-Si. The mechanisms underlying this finding have been tentatively elucidated by considering the differences in the doping effects of P and As in silicon.

On the mechanism of carrier scattering at oxide precipitates in Czochralski silicon

Oxygen precipitation (OP) in Czochralski (CZ) silicon has been extensively and intensively studied in the past decades due to its significance for improving manufacturing yield of integrated circuits. Nevertheless, how OP affects the carrier transportation in CZ silicon has hardly been addressed. Here, we report that the carrier mobility is decreased to a certain extent while the carrier concentration is nearly unchanged due to significant OP in CZ silicon. Interestingly, such a decrease in mobility can be offset by copper (Cu) decoration of oxygen precipitates via Cu drive-in anneal at appropriate temperatures. It is clarified that the charges associated with the oxygen precipitate/silicon interface states exert additional scattering effect on the carrier transportation, leading to the decrease of carrier mobility as mentioned above. We believe that the present work gains an insight into OP in CZ silicon from the electrical point of view.