Thermal stability of a porous low-k film is a critical issue for application consideration in the back-end-of-line. In this study, thermal stability of the porous silicate has been investigated by changing the thermal processing temperatures. Experimental results have shown that the dielectric constant of the porous silicate still remains below 2.0 after thermal processing at 500 degreesC for I h. A series of material analysis techniques and electrical characteristics have been used to verify the physical and chemical characteristics of the porous silicate film.