Processes in semiconductor materials after laser cutting

Abstract

The results of laser - semiconductor interaction are presented. The characteristic zones are investigated after laser affects the semiconductor substrates by method of electro-physical (dynamic and static) performances of diagnostic structures. It has been found that: 1. Near of area of interaction of a laser radiation with a material of the target, the hot electrons generated by laser radiation, causes changes of properties of a material. It causes increase of reverse currents of the diodes. The magnification of reverse currents of the diode is observed which depends on supply voltage and distances between laser cut and diode. The distance between edge of the diode and edge of the laser cut with which begins increase of reverse currents of the diodes in Si: for supply voltage was 8,2 V - 5 micrometers , 20 V - 26 micrometers ; in HgCdTe: for working voltage (0,1 V) the distance was 18 micrometers . 2. The laser radiation causes temporary increase of reverse currents of the diodes on distances from 2 micrometers and more (measurement of a reverse currents of the diodes on distances 36 and 78 micrometers have shown reduction of a reverse currents, in time about 400 minutes). 3. Our experimental data allow us to develop criteria of definition of parameters of laser radiation for laser cutting of semiconductor materials on distances in some microns from elements of the integrated circuits. The basic criteria of a choice of laser radiation: 1. Repetition frequency of laser pulses; 2. Volume of destruction of a material for one pulse. The laser source for these experiments was an UV laser at 0,34 micrometers wavelength with 7 ns pulses, laser fluency was more than 1,1 J/cm 2 that corresponding to minimum energy density required to forming pits. The diagnostic structures included p-n junctions (Si, HgCdTe) or source of MOSFETs (Si). Our experimental data showing that the powerful high- speed laser tools for cutting of materials are of limited usefulness for semiconductor materials.