Comparative study of phosphosilicate glass on (100) silicon by furnace and rapid isothermal annealing

Abstract

Annealing experiments were carried out on phosphosilicate glass (PSG) films deposited on (100) silicon substrates by using a low-pressure chemical vapor deposition technique. Rapid isothermal processing and conventional furnace heating were used to study the electrical, structural, and mechanical characteristics of these films and the results of the two processes compared. A refractive index of 1.457 was obtained in the rapid isothermal annealing cycle of 800 °C/15S, but was 1.419 for the furnace annealing cycle (i.e., 800 °C/65S). Spreading resistance analysis has shown that the junction depth remains unchanged for an 800 °C/15S rapid isothermal annealing cycle. Stress measurements show that rapid isothermal annealing leads to less strain compared to furnance annealing. The x-ray photoelectron spectroscopy analysis shows that as compared to furnance annealing, rapid isothermal annealing provides a chemically homogenous interface. High-frequency capacitance voltage (C-V) measurements show that furnance-annealed samples are leaky and a higher concentration of oxygen-related defects are present in the PSG/Si interface. On the other hand, because of a relatively clean interface, a well behaved C-V characteristic is observed in the rapid isothermal annealed samples. In summary, as compared to furnace annealing, rapid isothermal annealing resulted in superior structural, mechanical, and electrical properties of PSG films on Si substrates. A plausible explanation of such behavior may be attributed to the difference in the radiation spectra of the two sources of energy.