A singly charged hydrocarbon ion CHx+ (x=0,1,2,3,4) was extracted from an electron bombardment type ion source using methane as the reagent gas and irradiated onto the Si(100) surface at glancing angle. Scattered ion spectrometry using an electrostatic energy analyzer revealed that H+, H-2(+), and H-3(+) ions were clearly formed at the scattering angle of 15degrees, associated with dissociative collisions of hydrocarbon ion species of incidence energy of 1000 eV. The formation of H-3(+) was tentatively interpreted as resulting from combination of excited atomic hydrogen produced by dissociative collisions of CH4+ ions with Si(100) surface. (C) 2004 American Institute of Physics.