Spectroscopic investigations of borosilicate glass and its application as a dopant source for shallow junctions

Borosilicate glass was investigated as a dopant source for proximity rapid thermal diffusion. A borosilicate gel was spun onto a silicon wafer and the layer was rapid thermally processed to convert it to a borosilicate glass. Fourier transform infrared spectroscopy, spectroscopic ellipsometry, and sheet resistance measurements were used to understand and subsequently optimise the conversion of the gel to a borosilicate glass. The optimum conversion step, which avoided any boron loss from the borosilicate glass layer, was a curing step of 900 degrees C for 45 s. Secondary ion mass spectrometry was used to measure the boron dopant profile of a silicon wafer that was doped with the borosilicate glass layer. The wafer had a surface dopant concentration of 4.7 X 10(19) cm(-3) and a junction depth of 65.5 nm. Junction diodes, which were fabricated using the glass layer as a dopant source, displayed excellent characteristics, with very low leakage currents and a near ideal forward slope. (C) 2000 The Electrochemical Society. S0013-3651(99)12-095-0. All rights reserved.