Patent ID: 8491962

Claim:
A method of forming, a low-k layer on a substrate, comprising: (a) mixing tetraalkoxysilane, ethanol, tetraalkylammonium hydroxide and water in a molar ratio between 1:4:0.3:8 and 1:10:0.4:16 to form a first mixture; (b) heating the first mixture for a period of less than about 36 hours to form a second mixture containing a plurality of non-crystalline silicon-containing particles, wherein each of the non-crystalline silicon-containing particles has a particle size of smaller than about 10 nm; (c) adding a surfactant to the second mixture to form a colloid solution, wherein the surfactant has a concentration of about 1-20% by weight of the colloid solution; (d) coating the substrate with the colloid solution and thereby forming a colloid layer thereon; and (e) calcining the colloid layer at a temperature of about 400-600° C. in the presence of air to transforming the colloid layer into the low-k layer, wherein the low-k layer has a dielectric constant of less than 2.