Photoinduced fabrication of amorphous SiO2 (a-SiO2) film is examined w
ith tetramethoxysilane (TMOS) at room temperature. The photoinduced re
actions consist of two steps: photoexcitation of silicon substrate and
photoinduced synthesis of a-SiO2. The surface of the irradiated silic
on with the Xe-2 excimer lamp peaking at 7.2 eV is covered with silano
l groups. Although the TMOS is difficult to coat on a silicon substrat
e because of its high volatility, the TMOS can be coated on the irradi
ated silicon wafer. The increase of the cohesive power is thought to o
riginate from silanol groups on silicon generated with irradiation. In
frared absorption related to the methyl group in TMOS disappeared with
illumination in the second step. The line shape of IR absorption turn
s to be similar to that of thermal SiO2 on silicon. The dependence of
photon energy for illumination is also examined. The refractive index
of SiO2 synthesized from TMOS is 1.453 at 633 nm, which is almost the
same as the refractive index of thermal SiO2. Finally, a model of phot
ochemical reaction is proposed. (C) 1996 American Institute of Physics
.