Narrow gap filling in 25 nm shallow trench isolation using highly porous organosilica

• Mesoporous organosilica was synthesized in the trenches of patterned silicon wafers.
• Low dielectric constant of organosilica was obtained by dual surfactants.
• Defect-free organosilica was originated from vaporized precursors.
• Crosslinking agent provided relatively high mechanical properties to organosilica.

Highly porous organosilica (POS) in shallow, 25-nm-wide trenches of a patterned wafer was synthesized by vapor-phase synthesis using dual surfactant solution and vaporized precursors. Cetyltrimethylammonium bromide and nonionic triblock copolymers were employed as a structure-directing agent in the surfactant solution. Two precursors including tetraethyl orthosilicate (TEOS) with bis(trimethoxysilyl)ethane (BTSE) were diffused and hydrolyzed at the surfactant solution. The vaporized precursors were continuously supplied during condensation of organosilica by a nonvolatile catalyst. This process provides the minimized shrinkage compared with conventional sol–gel reaction during condensation reaction. The mechanical properties of the organosilica were improved by crosslinking of TEOS and BTSE. Synthesized POS had a pore size of 4.67 nm, a Young's modulus of 5.20 GPa and a dielectric constant of 1.65.