Raman spectroscopic characterization of KrF-laser-irradiated silicon

Abstract

High-fluence KrF-laser-irradiated silicon wafers exhibit a wealth of surface structures, which are different depending on the medium present above the surface during treatment with ultraviolet light. A special surface feature, appearing after treatment under water and in air, is analyzed with a Raman microprobe spectrometer. It is found to consist of leaflike formed silicon structures located above but still attached to the treated surface. During Raman scattering measurements the temperature of these morphological peculiarity rises considerably even at low cw probe laser powers because of geometrically limited thermal conductivity. It is shown that the temperatures, which were derived from the Stokes-to-anti-Stokes scattering intensity ratio are more reliable than those extracted from line shifts since the stress developing inside the Raman laser-heated leaflike microstructures is not known. A Raman microprobe scan of a damage spot, generated by UV treatment under water, reveals in the most cases an enhanced Raman intensity (factor of 10) in comparison with untreated areas. This enhancement is even larger at surface spots of smaller ( < 1 pm) sizes and is attributed to the held enhancement of the incident and scattered radiation field caused by geometrical resonances.

Adjustable Fragmentation in Laser Desorption/Ionization from Laser-Induced Silicon Microcolumn Arrays

“…Another important factor is the near-field effect in the vicinity of the microcolumns. 49 The silicon microcolumns act like antennas and locally enhance the radiation field of the laser, thus reducing the fluence threshold.…”