Conditions for laser-induced plasma to effectively remove nano-particles on silicon surfaces
Jinghua Han(韩敬华)1, Li Luo(罗莉)1,2, Yubo Zhang(张玉波)3, Ruifeng Hu(胡锐峰)1, Guoying Feng(冯国英)1
1. College of Electronics and Information Engineering, Sichuan University, Chengdu 610064, China; 2. College of Optoelectronic technology, Chengdu University of Information Technology, Chengdu 610225, China; 3. Sichuan Engineering Technical College, Deyang 618000, China
Abstract Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave. The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients, making the particles easier to be removed. Laser plasma can ionize and even vaporize particles more significantly than an incident laser and, therefore, it can remove the particles more efficiently. The laser plasma shock wave plays a dominant role in removing particles, which is attributed to its strong burst force. The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface. In order to obtain the working conditions for particle removal, the removal mechanism, as well as the temporal and spatial characteristics of velocity, propagation distance and pressure of shock wave have been researched. On the basis of our results, the conditions for nano-particle removal are achieved.
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