Identification of Si and SiH in catalytic chemical vapor deposition of SiH4 by laser induced fluorescence spectroscopy

Radical species produced in catalytic chemical vapor deposition (CVD), ofte n called hot-wire CVD, processes were identified by using a laser induced f luorescence technique. Ground state Si atoms could be detected at low press ures where collisional processes in the gas phase could be ignored. The ele ctronic temperature of Si atoms just after the formation on the catalyzer ( tungsten) surfaces was 1320 +/- 490 K, when the catalyzer temperature was 2 300 K. By the addition of 0.5 Pa of Ar, the electronic temperature was lowe red down to 450 +/- 30 K. The absolute density of Si atoms was 3 +/- 1x10(9 ) cm(-3) at 10 cm below the catalyzer when the flow rate and the pressure o f SiH4 were 0.5 sccm and 4 mPa, respectively. This density is just 0.3% of that of the parent SiH4 molecules. However, since the decay rate of Si atom s is fast, it can be concluded that atomic silicon is one of the major prod ucts on the heated catalyzer surfaces. SiH radicals could also be detected, but the production rate of this species is two orders of magnitude less th an that of Si atoms. It was also discovered that volatile SiH4 molecules ar e produced by the atomic hydrogen attack on the amorphous silicon deposited on the chamber walls. (C) 2000 American Institute of Physics. [S0021-8979( 00)06721-9].