采用157 nm波长准分子激光,对LED-GaN半导体薄膜进行了刻蚀试验研究。探讨了GaN基半导体材料的基本刻蚀特性和刻蚀机理。结果表明,157 nm激光在能量密度高于2.5 J/cm2时,刻蚀速率可达50 nm/pulse以上。以低于16 Hz脉冲频率和高于0.25 mm/min的扫描速度进行激光直写刻蚀时,可以获得Ra30 nm以下的表面粗糙度。采用扫描刻蚀方法,可以加工出75°左右的刻蚀壁面。实验也证明157 nm激光在三维微结构加工方面具有较大的潜力。单光子吸收电离引起的光化学反应是157 nm激光刻蚀GaN基材料的主要机理。

Using excimer laser with 157 nm wavelength,experimental studies on micro-ablation of LED-GaN semiconductor films have been performed. The primary etching performance and mechanism of GaN-based semiconductor materials have been investigated and analyzed. The results show the etching rate above 50 nm/pulse can be achieved as the laser fluence is higher than 2.5 J/cm2. For 157 nm laser direct writing,the etched surface with roughness lower than 30 nm-Ra which can be obtained when the laser repetition rate is smaller than 16 Hz and the scanning velocity is higher than 0.25 mm/min. Using laser scanning approach for GaN film etching,a sidewall with about 75° sharpness can be fabricated. The potential of the 157 nm laser for micro-machining of three-dimensional (3D) micro-structures has been proven. Photo-chemical reaction induced by single photon absorption ionization plays a dominant role in GaN-based material etching with 157 nm laser.