Raman microprobe: a diagnostic tool for processed silicon. Analysis of microindented silicon

Abstract

Laser-assisted processes are currently used in silicon technology. The response of the material to the laser beam depends strongly on its own physical properties and on the laser power density. The use of a microRaman system, allows the structural characteristics of the material to be analysed by varying the excitation laser power density on the sample over a large power range with a submicrometre lateral resolution. Results are reported on microindented crystalline silicon, showing that changes in the physical properties of the material, introducing grain boundaries, dislocations and cracking, result in a strong modification of the Raman spectrum. These spectral changes are enhanced for increasing laser power densities. Several mechanisms are pointed out as possible sources of the observed spectral modifications. These results show that Raman microprobe is a very promising technique for the diagnosis of technologically processed semiconductors and devices.