High aspect ratio etching by infrared laser induced micro bubbles

High aspect ratio etching of metals has been attained by the irradiation of infrared laser in an inert liquid with low vaporization energy and low ratio of coefficient of viscosity to specific gravity. In-situ cross sectional observation at the irradiation point appealed the mechanism of laser etching in a liquid in detail. The mechanism is the following: micro bubbles in the liquid are produced when the laser is irradiated, the bubbles generate a local upward stream in the liquid, the stream removes debris produced by the laser etching, therefore the etching is efficiently occurred by this mechanism and high aspect ratio etching is attained.