Nuclear Microprobe Application in Semiconductor Process Developments

Scanning nuclear microprobes using Rutherford backscattering (RBS) with light ions have been applied to semiconductor process steps, in which minimum feature sizes of several microns down to submicron and multi-layered structures were used. Two or three dimensional RBS mapping of processed semiconductor layers such as multi-layered wiring, semiconductor-on-insulator (SOI), focused ion implanted layers, and laser processed layers, has clearly revealed process failures and inhomogeneity in buried layers without layer removal processes. Radiation damage due to the probe beams was found to be induced by high probe doses at and above 1017/cm2, in which the degradation of crystallinity by probe beams differs between Si and GaAs

Detection of nonmagnetic metal thin film using magnetic force microscopy

Magnetic force microscopy (MFM) allows detection of stray magnetic fields around magnetic materials and the two-dimensional visualization of these fields. This paper presents a theoretical analysis of the oscillations of an MFM tip above a thin film of nonmagnetic metal. The results show good agreement with experimental data obtained by varying the tip height. The phenomenon analyzed here can be applied as a "metal detector" at the nanometer scale and for contactless measurement of sheet resistivity. The detection sensitivity is obtained as a function of oscillation frequency, thus allowing determination of the best frequency for phase-shift measurement. The shift in resonance frequency due to the presence of a nonmagnetic metal is also discussed.Comment: 4 pages, 5 figure

Nuclear Microprobe for Integrated Circuit Process Inspection

A nuclear microprobe with a minimum beam-spot diameter of less than 100 nm, intended for application to IC (integrated circuit) process inspection, has been designed and installed at Osaka University. An ultra high-vacuum sample-chamber with a three-axis goniometer stage and a toroidal electrostatic analyzer for medium energy ion scattering (MEIS) was combined with a short acceleration column for a focused ion beam. A liquid metal ion source (LMIS) for light metal ions such as Li+ or Be+ was mounted on the short column. A minimum beam spot-size of about 80 nm with a current of 30 pA was obtained for 400 keV Be++ LMIS. An energy resolution of 4 x 10-3 (ΔE/E) for the toroidal analyzer gives rise to atomic resolution in RBS spectra for Si and GaAs. This system seems feasible for atomic-level in-depth analysis of localized surfaces and crystalline/disorder structures. The design concept and simulated focusing characteristics using beryllium and lithium liquid metal ion sources were compared with those of conventional microprobes. The feasibility of this microprobe to localized analysis of future IC process steps with a minimum feature size of less than a quarter micrometer was discussed

Excimer-laser removal of SiO2 patterns from GaAs substrates

Japanese Journal of Applied Physics, Part 2: Letters333 AL324-L327JAPL