MASK-FREE PROCESS OF LASER-INDUCED FORMATION OF PERIODIC RELIEF WITH PHASE SHIFTS π ON SURFACE OF SEMICONDUCTOR MATERIALS Russian patent published in 2002 - IPC

FIELD: laser technology. SUBSTANCE: mask-free process of laser- induced formation of periodic relief on surface of semiconductor materials can find use in production of single-frequency semiconductor laser with distributed feedback. Surface of semiconductor material in contact with chemical etching agent is illuminated by two coherent laser beams creating interference picture with period d₁. Then it is illuminated by two coherent laser beams forming interference picture with period d₂ not equal to d₁. Illumination of surface of semiconductor material is carried out in the form of multiple train of cycles which number either exceeds or equals ten. Each cycle includes illumination of surface of semiconductor material first by two coherent laser beams creating interference picture with period d₁ and then by two coherent laser beams forming interference picture with period d₂ not equal to d₁. Illumination time in each cycle by pair of beams is chosen on condition that amplitude of relief in the course of this time increases by not more than 0.5 nm. EFFECT: high precision of process. 2 dwg