The Laser-induced Liquid Corrosion Of Key Technologies

Compared with the conventional chemical etching, laser assisted wet chemical etching can eliminate the effect of crystal orientation efficiently and fabricate more diversified etched pattern; compared with the laser assisted gas chemical etching, the required condition for laser wet etching can be realized more easily and the operation can be simplified; compared with the ion etching,it has advantages of no ion damage to substrate, avoiding over-etching and cost-effective. For mentioned reasons above, considerable interests have been focused on laser induced wet etching. Because the etched pattern will be effected by many factors, many technical difficulties such as getting the ideal etched pattern and monitoring the etching process have not been solved yet.The purpose of this thesis is to develop the laser assisted wet chemical etching on the GaAs substrate. The main contents and contributions include:1) laser-assisted wet mask-etching method and poles-etching method have been proposed laser-assisted wet mask-etching method is that the area which need not etched is covered by mask film, and the uncovered area is processed by laser induced wet etching. Poles-etching method is that the etching current caused by the external voltage is used to promote the intermediate ion product break away from the surface of substrate and keep the etching rate stable. Theoretical analysis and experimental results show that the mentioned methods above can simplify the process condition, improve the etched effect, shorten the etching time and obtain more even etched surface.2) laser-assisted wet sequencially-selective-etching method has been developed This method can be applied when the corrosion solution is mixed solvent. For example, when the GaAs substrate is etched by H2SO4-H2O2, H2O2 is adopted to oxidate the substrate first, then the substrate was etched by means of laser wet etching in H2SO4 solvent. Theoretical analysis and experimental results show that compared with the mixed-solvent-etching, more smooth etched surface can be obtained by this method; and because the substrate is preprocessed, time of laser induced wet-chemical etching...