AVS 49th International Symposium
    Plasma Science Friday Sessions
       Session PS-FrM

Paper PS-FrM2
Measurements of Desorbed Products and Etching Yield by CFx+(x=1,2,3) Ion Irradiation

Friday, November 8, 2002, 8:40 am, Room C-103

Session: Plasma Surface Interactions II
Presenter: K. Karahashi, Association of Super-Advanced Electronics Technologies (ASET), Japan
Authors: K. Karahashi, Association of Super-Advanced Electronics Technologies (ASET), Japan
K. Ishikawa, Association of Super-Advanced Electronics Technologies (ASET), Japan
H. Tuboi, Association of Super-Advanced Electronics Technologies (ASET), Japan
K. Yanai, Association of Super-Advanced Electronics Technologies (ASET), Japan
K. Kurihara, Association of Super-Advanced Electronics Technologies (ASET), Japan
M. Nakamura, Association of Super-Advanced Electronics Technologies (ASET), Japan
Correspondent: Click to Email
Fluorocarbon plasma has been widely used to etch silicon dioxide in the fabrication of semiconductor devices. For further development of integrated semiconductor devices, more precise control of the etching process is required. Thus, we have developed a mass-analyzed ion beam apparatus; Energy controlled single species ions are irradiated to SiO2 surface under ultra-high vacuum condition, and we can study the roles of individual fluorocarbon ion irradiation without gas phase reactions or neutral radicals irradiation. In the present work, we have investigated desorption products and etching yields for silicon or silicon dioxide by CFx+ (x = 1-3) ion bombardments. Desorbed products could detected with a quadrupole mass spectrometer by pulse ion beam method, and estimate the kinetic energy of desorbed products from the time delay of waveform from incident ion pulse. In SiO2 etching by CFx+ ion irradiation, the major desorbed product, which contains silicon, was SiF2. The kinetic energy of SiF2 was less than 0.1 eV. Therefore, products were different from physical sputtering particles such Si and SiF as desorbed from silicon surfaces by CFx+ (x = 1-3) ion bombardments. Etching yields for SiO2 were measured as a function of incident ion energy. The etching yield by F+ ion was smaller than that of Ar+ ion. The effect of chemical reaction of F+ ion did not clearly appeared. Etching yields of CFx+ (x = 1-3) increased with increasing the ion energy and with increasing number of fluorine atom in the ions. Above 1000 eV, etching yields is gradually saturated. Below 500 eV, etching yields abruptly dropped with decreasing ion energy, and fluorocarbon films grew on surfaces. These results suggest that the etching reaction is affected by chemical reactivity of the incident ions, and that the etching reactions are controlled by the incident ion energy and species. This work was supported by NEDO.