The arsenic concentration (CAs) in polycrystalline silicon (poly-Si) deposited under various deposition conditions in the deposition temperature range 670°-760°C using SiH4-H2-AsH3 gas system has been determined by neutron activation analysis. From the experimental results, it was found that CAS increases with decreasing deposition temperature and with increasing partial pressure of AsH3 in the gas introduced into the reactor (PAsH3(i)), and that for lower PASH3(I) region, CAS decreases with decreasing gas velocity and with increasing deposition rate, and for higher PAsH3(i) region, CAs is independent of gas velocity and deposition rate. Prom the analyses of the experimental data, it was suggested that (i) for lower PAsH3(i) region, CAs is limited by the diffusion of As-containing species, such as As molecule, Asa molecule, and As4 molecule, in the stagnant layer formed by gas stream, and for higher PASH3″(I) region, CAS is controlled by the surface reaction; (ii) monatomic As existing at wafer surface is incorporated in poly-Si in accordance with Henry's law; (iii) the transfer coefficient of As atoms in gas phase increases slightly with increasing deposition temperature and gas velocity; (iv) the segregation coefficient of monatomic As between gas phase and poly-Si (m) is approximated by m = 1.5 X 10* exp (-71.5 kcal/mole/RT); (u) the energy of As-Si bond is 44.5 kcal/mole.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry