Nur'aini Anafi, Oh Ilwhan
Departments of Applied Chemistry, Chemical Engineering, and Department of Energy Convergence Engineering, Kumoh National Institute of Technology, Gumi, Gyeongbuk 39177, South Korea.
ACS Omega. 2022 May 2;7(19):16665-16669. doi: 10.1021/acsomega.2c01113. eCollection 2022 May 17.
A deep etching method for silicon "micro"structures was successfully developed. This wet etching process is based on metal-assisted chemical etching (MACE), which was previously mainly utilized to etch the features that have lateral dimensions of "nanometers." In this novel MACE, the critical improvement was to promote the "out-of-plane" mass transfer at the metal/Si interface with an ultrathin metal film. This enabled us to etch micrometer-wide holes, which was previously challenging due to the mass transport limitation. In addition, it was found that when ethanol was used as a solvent instead of water, the formation of porous defects was suppressed. Under the optimized etch conditions, deep (>200 μm) and vertical (>88°) holes could be carved out at a fast etch rate (>0.4 μm/min). This novel deep MACE will find utility in applications such as microelectromechanical systems (MEMS) devices or biosensors.
一种用于硅“微”结构的深蚀刻方法被成功开发出来。这种湿法蚀刻工艺基于金属辅助化学蚀刻（MACE），该方法此前主要用于蚀刻横向尺寸为“纳米”级别的特征。在这种新型MACE中，关键的改进在于利用超薄金属膜促进金属/硅界面处的“面外”传质。这使我们能够蚀刻出微米级宽的孔，而此前由于传质限制，这一直具有挑战性。此外，还发现当使用乙醇作为溶剂而非水时，多孔缺陷的形成受到抑制。在优化的蚀刻条件下，可以以较快的蚀刻速率（>0.4μm/分钟）蚀刻出深度大于200μm且垂直度大于88°的孔。这种新型的深MACE将在微机电系统（MEMS）器件或生物传感器等应用中发挥作用。
