Papers by Keyword: CF₄

Abstract: We investigated impacts of the Ar and CF₄plasma during reactive ion etching (RIE) on defect formation in the Ge substrates using the deep-level-transient-spectroscopy (DLTS) technique. It was found that the Ar plasma causes the roughening of the Ge surface. Moreover, the Ar plasma induces a defect with an energy level of 0.31 eV from the conduction band minimum in the Ge substrate, confirming by DLTS spectra. On the other hand, the CF₄ plasma hardly induces the surface roughness of Ge. However, the CF₄ plasma induces many kinds of electron and hole traps. It should be noted that the defects associated with Sb and interstitials are widely distributed to around 3-µm.

Abstract: To study the influence of twice-deposited mask layers on the verticality of side wall and the aspect ratios of silicon-based nanostructures, the performance of focused ion beam (FIB) and CF₄-based inductive coupled plasma reactive ion etching (ICP-RIE) processes was realized. The first etching mask of chromium (Cr) was deposited by radiofrequency (RF) magnetron sputtering as the conductive and etching barrier layers. Next, the Cr layer was directly patterned by a dual-beam FIB system to form nanograting patterns. Thereafter, a secondary mask layer of oxide (SiO₂) with a thickness of 50 nm was deposited by sputtering. In order to study the influence of various deep etching parameters on verticality and aspect ratios, we examined argon flow rates, coil powers, platen powers, and chamber pressures. The SiO₂ barrier layer on the side wall could be retained to maintain a high verticality contour and reduce the line-width shrinking ratio to surmount over etching during the use of fluorine-based gas. The residual Cr and SiO₂ layers were dissolved and removed using a wet etching process consisting of a Cr-etching solution (CR-7). Measurements show that the verticality and aspect ratios of the grating nanostructures were 92.1° and 5.63, respectively.