Langmuir-Type Mechanism for In-Situ Doping in CVD Si and Si1-xGex Epitaxial Growth

In-situ doping process of B and P in CVD Si and Si1-xGex (100) epitaxial growth is investigated using SiH4-GeH4-dopant gas (B2H6 or PH3)-H-2 gas mixture. For lower dopant gas partial pressure, the in situ doping is explained quantitatively by the Langmuir-type adsorption and reaction at Si-Si, Si-Ge or Ge-Ge pair sites on the (100) surface. For higher B2H6 gas partial pressure (P-B2H6), it is proposed that SiH4, GeH4 and B2H6 molecules are adsorbed and react partially at the B-occupied sites where B2H6 molecules have been adsorbed on the (100) surface. For higher PH3 gas partial pressure (P-PH3), it is proposed that the in situ doping and Ge incorporation are enhanced by the self-limited adsorption of PH3 molecules and the decomposition of GeH4 at the P-occupied sites where PH3 molecules have been adsorbed on the (100) surface, respectively, and that the decrease of P concentration with increasing P-PH3 in high P-PH3 region is caused by lower segregation coefficients of P at Si-Ge and Ge-Ge pair sites than that at Si-Si pair sites according to the Henry's law. Fairly good agreement is obtained between all the experimental data and the modified Langmuir-type mechanism for in situ doping.

Automated summary

The in-situ doping process of B and P in CVD Si and Si1-xGex (100) epitaxial growth was investigated using SiH4-GeH4-dopant gas (B2H6 or PH3)-H2 gas mixture. The study proposed mechanisms for in situ doping at different dopant gas partial pressures and showed good agreement with experimental data.