Outdiffusion of impurity atoms from silicon crystals and its dependence upon the annealing atmosphere

Abstract

The outdiffusion of boron, antimony, and phosphorus from the bare silicon wafer at 1200 °C, especially its dependence upon the annealing atmosphere, has been studied with spreading resistance and secondary ion mass spectroscopy (SIMS). It is found that the boron outdiffusion proceeds when the crystal is annealed in hydrogen, but is completely suppressed in argon even if the doping concentration is as high as 3×1018 cm−3 and the annealing time is as long as 2 h. The dramatic dependence upon the atmosphere has not been observed for the other impurities and is temporarily related with the desorption process of boron atoms from the surface.

Deep level studies in high‐temperature annealed silicon wafers for layer transfer in thin‐film solar cells

“…From the C – V plots and the free carrier density profiles reported here, one can conclude that high‐temperature annealing of Si wafers under H 2 atmosphere may change the dopant profile. In the case of p‐type material, B can outdiffuse 8, 9. On the contrary, in n‐type material a pile up at the interface may occur, if an SiO 2 layer is present 10, 11.…”

B profile alteration by annealing in reactive ambients

“…Alternatively a BF 2 implant ͑2.2 keV, 1 ϫ 10 15 atoms/ cm 2 ͒ was used, which leads to a F profile overlapping with the B profile. Pieces of wafers were annealed in a Heatpulse lamp oven at 950°C for 30 s, with ramp-up rate around 100°C / s and ramp-down rate around 70°C / s. Three different gas ambients during anneal were used, i.e., N 2 100%, H 2 10% +N 2 90% ͑stimulating the B desorption process͒, 15 and O 2 10% +N 2 90% ͑stimulating I injection͒. 15,16 After processing, B depth profiles were determined using secondary ion mass spectroscopy ͑SIMS͒ using an Atomika 4500 instrument, and the electrical activation was extracted from the sheet resistance measurements based on standard mobility data.…”

“…Pieces of wafers were annealed in a Heatpulse lamp oven at 950°C for 30 s, with ramp-up rate around 100°C / s and ramp-down rate around 70°C / s. Three different gas ambients during anneal were used, i.e., N 2 100%, H 2 10% +N 2 90% ͑stimulating the B desorption process͒, 15 and O 2 10% +N 2 90% ͑stimulating I injection͒. 15,16 After processing, B depth profiles were determined using secondary ion mass spectroscopy ͑SIMS͒ using an Atomika 4500 instrument, and the electrical activation was extracted from the sheet resistance measurements based on standard mobility data. 17 In order to prevent any substrate contribution due to probe penetration, the sheet resistance was extracted from variable probe spacing measurements using spreading resistance probes with less than 5 nm penetration.…”

Effect of the Flash Annealing on the Impurity Distribution and the Electronic Structure in the Inversion Layer

“…Because the reduction of dopant concentration leads to increase of the width of inversion layer, dopant concentration is crucial to the subband energy levels confined in IL. Dopant diffusion in Si subsurface region has been studied in detail for several decades especially in terms of the process of MOSFET fabrication [7][8][9]. However, the effect of flash annealing in UHV on the dopant concentration has been still under discussions [10,11].…”