光助电化学刻蚀法制作大面积高深宽比硅深槽

Photoelectrochemical Etching of Large-Area High-Aspect-Ratio Silicon Deep Trenches

为解决用光助电化学刻蚀法制作大面积高深宽比硅深槽过程中出现均匀性差的问题,在分析了传统光助电化学刻蚀装置中存在的不足的基础上,设计并制作了一套新型大面积光助电化学刻蚀装置.该装置通过特殊设计的花洒式溶液循环机构和水冷隔热系统,解决了大面积硅片在长时间深刻蚀过程中出现的溶液升温和气泡堆积的问题.借助这套装置能够实现127 mm(5 inch)及以上大面积硅片的均匀深刻蚀.同时,通过采用以0.01 A/min的速率逐步增加刻蚀电流的方法,来补偿侧向腐蚀对槽底电流密度的影响,保证了整个刻蚀过程中硅深槽形貌的一致性.最终在整个127 mm硅片上制作出了各处均匀一致的硅深槽,深度达60μm、深宽比在20以上.

To deal with the problem of non-uniformity in photoelectrochemical etching of large-area high-aspect-ratio silicon deep trenches,a novel large-area photoelectrochemical etching setup was designed and manufactured,based on analysis of the defaults in traditional photoelectrochemical etching setups.With the specially designed shower-like solution circulation module and water cooling system,the problems of solution＇s temperature rising and gathering of hydrogen bubbles in long-time photoelectrochemical etching process of large-area silicon wafers were solved.Uniform deep etching can be performed on large-area silicon wafers of 127 mm（5 inch） or more,with this novel large-area photoelectrochemical etching setup.Meanwhile,morphology consistency of silicon deep trenches was well kept in the whole etching process by increasing the etching current at the speed of 0.01 A/min to compensate the influences of lateral etching on the current density on bottom of the trenches.Uniform silicon deep trenches with good morphology consistency were eventually fabricated on full 127 mm silicon wafers,whose depth was up to 60 μm and aspect-ratio was larger than 20.