Surface Roughness Modification of Free Standing Single Crystal Silicon Microstructures Using KrF Excimer Laser Treatment for Mechanical Performance Improvement

• 作者: Mohamed Elwi Mitwally Osamu Tabata Sherif Sedky Toshiyuki Tsuchiya
• 来源期刊: 表面工程材料与先进技术期刊(英文)
• 学科: 医学
• 关键词: FREESTANDING Mechanical Test Structures Harsh Laser TREATMENT Surface ROUGHNESS IMPROVEMENT
• 年，卷（期）: bmgcclyxjjsqkyw_2015,（1）
• 页码范围: 28-41
• 页数: 14页
• 分类号: R73

摘要

Single crystal silicon freestanding structures for tensile and fatigue testing were treated with KrF excimer laser to improve surface roughness and accordingly mechanical performance. Sample thickness was 5 μm. Localized laser treatment was successful in eliminating the scallops developed during Bosch process and in reducing surface roughness. Harsh irradiation at laser energies up to 4 J/cm2 was only possible due to localized treatment without significant vibrations occurring on the freestanding samples that led to fracture in preliminary experiments at energies as low as 0.16 J/cm2. Finite element analysis was used to investigate the temperature distribution on the irradiated structures. Atomic force microscopy (AFM) and Raman spectroscopy were also used to assess surface roughness, crystallinity changes and surface stresses developing on surfaces subjected to perpendicular laser irradiation. At a high energy (3.2 J/cm2) the top surface showed a decrease of roughness compared to fabricated samples. Raman spectroscopy showed the dominance of crystalline silicon after laser irradiation. The effects of laser energy, number of pulses