Modulation of electron energy distribution function in radiofrequency SiH/sub 4/, SiH/sub 4/ - H/sub 2/ bulk plasmas

Journal Article · Thu Dec 01 04:00:00 EST 1988 · Plasma Chem. Plasma Process.; (United States)

DOI:https://doi.org/10.1007/BF01016057· OSTI ID:6419578

Capitelli, M; Gorse, C; Winkler, R; Wilhelm, J

Electron energy distribution functions (EDF) in SiH/sub 4/, SiH/sub 4/-H/sub 2/ radiofrequency discharges have been calculated by solving the time-dependent Boltzmann equation in the presence of a sinusoidal field. Particular emphasis is given to the modulation of EDF as a function of the applied frequency (..pi.. x 10/sup 6/ less than or equal to omega/p/sub 0/ less than or equal to ..pi.. x 10/sup 8/ sec/sup -1/ torr/sup -1/) and of gas composition. The results show that at omega/p/sub 0/ = ..pi.. x 10/sup 6/ sec/sup -1/ torr/sup -1/ EDF follows in a quasistationary mode the variation of the field with the exception of a small range of electric field near to the zero crossing. Still, at the higher considered frequency (omega/p/sub 0/ = ..pi.. x 10/sup 8/ sec/sup -1/ torr/sup -1/), they observe some modulation of EDF. The necessity of using a time-dependent approach is tested by comparing the present results with the corresponding ones obtained by using the effective field approximation (i.e., the approximation which solves instead of the time-dependent Boltzmann equation the corresponding stationary one at the effective values E = E/sub 0/ ..sqrt..2 of the rf field). The two sets of results can differ by orders of magnitude in the tail of EDF, the differences decreasing with increasing molar fraction of H/sub 2/ and increasing field frequency. The role of excited states (second-kind collisions) is studied by inserting in the Boltzmann equation given concentrations of vibrational and electronic states. The results show that second-kind collisions strongly affect EDF especially in pure silane. Finally a satisfactory agreement has been found between theoretical and experimental results concerning the modulation of electrons of given energy in pure silane discharges.

• Research Organization: Centro di Studio per la Chimica, Bari (Italy)
• OSTI ID: 6419578
• Journal Information: Plasma Chem. Plasma Process.; (United States), Journal Name: Plasma Chem. Plasma Process.; (United States) Vol. 8:4; ISSN PCPPD
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
BOLTZMANN EQUATION
COLLISION INTEGRALS
COLLISIONS
DIFFERENTIAL EQUATIONS
DISTRIBUTION FUNCTIONS
ELASTIC SCATTERING
ELECTRIC DISCHARGES
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LEVELS
ENERGY SPECTRA
ENERGY-LEVEL DENSITY
ENERGY-LEVEL TRANSITIONS
EQUATIONS
ETCHING
EXCITATION
EXCITED STATES
FERMIONS
FREQUENCY MODULATION
FUNCTIONS
HIGH-FREQUENCY DISCHARGES
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
INTEGRALS
IONIZATION
LEPTONS
MODULATION
MOLECULE COLLISIONS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PARTIAL DIFFERENTIAL EQUATIONS
PLASMA SIMULATION
SCATTERING
SILANES
SILICON COMPOUNDS
SIMULATION
SPECTRA
SURFACE FINISHING