Si晶片激光标识码制作技术的研究

Study on laser mark technology for Si wafer

Si片标识码在工艺加工管理中起重要作用。传统手写方式存在字体不美观、划痕深及硅渣污染等缺点。鉴于此,采用波长1060 nm光纤激光器进行激光标识码制作。研究中分别改变激光平均输出功率、脉冲频率及扫描速度,借助目视、金相显微镜及动态三维光学轮廓仪来观察标识码清晰程度、污染程度及深浅程度的变化,了解它们与上述参数间相互对应关系。重点解决清晰度与打标深度之间的矛盾,从而得到清晰、清洁且深度满足后续半导体纳米级加工工艺要求的激光标码技术。研究表明:低脉冲频率(20 k Hz)下,随平均功率上升,标识码的清晰度逐渐增加,镜检结果显示硅渣的数量及其分布区域增大;高脉冲频率(90 k Hz)下,平均功率增加对标识码清晰度的影响不明显,镜检结果没有发现硅渣。扫描频率与清晰度及污染程度成正比关系。扫描速度与打标深度呈反比关系。采用40%平均功率,25 k Hz频率,1500 mm/s扫描速度及双线填充字体(True Type)的工艺条件,所得标识码在目视及镜检下清晰美观,无硅渣污染。轮廓仪测量结果显示字迹深度及边缘凸起均在200 nm以下。经批量产品验证,根据研究成果所开发的工艺技术稳定且对后续工艺无不良影响。目前已取代手写方式。

As the traditional handmade wafer mark way has the disadvantages that the typeface is not beautiful,the scratch is deep and Si pollutes,etc.,the 1060 nm fiber laser was used for laser mark. During the work,the effect of laser average power,pulse frequency and scan speed on mark definition,Si residue and mark depth were studied by the different measurement methods,such as eye inspection,metalloscope and 3D optical profiler. The results show that,when pulse frequency is at 20 k Hz,mark definition gradually increases with increase of average power,and the number and distribution area of Si residue increase; however,the effect of average power on mark definition is not obviously when pulse frequency is at 90 k Hz,and there is no Si residue. Pulse frequency is proportional to definition and degree of contamination,and the mark depth is inverse proportional to scan speed. Under the condition of 40 % average laser power,25 k Hz pulse frequency and 1500 mm / s scan speed,the mark is very clear and has no Si residue contamination,and its edge embossments are less than 200 nm. The overall results show that the developed technology is robust and it has replaced the handmade wafer mark.