Influence of thermal budget on phosphosilicate glass prepared by high-density plasma chemical-vapor deposition

Abstract

High-density plasma chemical-vapor deposition phosphosilicate glass (PSG) films were evaluated for the application of premetal dielectric materials. The PSG films were deposited using phosphorous-related precursors reacted with silane and oxygen at a temperature ⩽550°C. The as-deposited films were subsequently furnace annealed at 400 °C for 10 to 30 min to simulate the effect of thermal budget on premetal dielectric layers in the current integrated circuit scheme. In addition, the PSG films were also annealed by rapid thermal processing at 925 °C for 10 to 30 s, to examine film stability near the glass transformation temperature. Fourier transform infrared spectroscopy (FTIR), stress measurement, x-ray fluorescence analysis, and x-ray photoelectron spectroscopy (XPS) were used to characterize the PSG films. Film stress measurement was used to examine the stress hysteresis of the PSG films in the thermal-budget process. The results show that residual inactive phosphorous and compounds with PO bonds are present in the as-deposited PSG films. Some residual phosphorous became active after the thermal annealing. The FTIR results that show an increase in the PO group upon numerous annealing treatments is in agreement with the XPS analysis.