Newly Developed Low-K and Low-Stress Fluorinated Silicon Oxide Utilizing Temperature-Difference Liquid-Phase Deposition Technology

ABSTRACTTo meet the requirements of low-K and low-stress intermetal dielectric (IMD) for future ULSI devices, a novel temperature-difference liquid-phase deposition (TD-LPD) method is proposed. The deposition solution of supersaturated silicic acid with high concentration of fluorine can be achieved by raising deposition temperature larger than 15 °C from dissolution temperature (0 °C). Because fluorine atoms can easily be incorporated with the technique, TDLPD fluorine-doped SiO2 (FSG) exhibits low-K (∼3.4) and low-stress (∼40MPa) property. In this paper, to study the interaction between TD-LPD FSG and moisture, the FSG is annealed and moisture stressed repeatedly as in a real process. Since K is sensitive to moisture absorption, and the stress is sensitive to the dehydration reaction between Si-OH's, the both are monitored as indices. A feasible mechanism is proposed to explain the variation in K/stress during annealing and boiling cycles.