Aryal Arjun, Stricklin Isaac, Behzadirad Mahmoud, Branch Darren W, Siddiqui Aleem, Busani Tito
Center for High Technology Materials (CHTM), University of New Mexico, MSC01 04-2710, 1313 Godard St. SE, Albuquerque, NM 87106-4343, USA.
Electrical and Computer Engineering (ECE), University of New Mexico, MSC01 11001, Albuquerque, NM 87131-0001, USA.
Nanomaterials (Basel). 2022 Aug 18;12(16):2836. doi: 10.3390/nano12162836.
The exceptional material properties of Lithium Niobate (LiNbO) make it an excellent material platform for a wide range of RF, MEMS, phononic and photonic applications; however, nano-micro scale device concepts require high fidelity processing of LN films. Here, we reported a highly optimized processing methodology that achieves a deep etch with nearly vertical and smooth sidewalls. We demonstrated that Ti/Al/Cr stack works perfectly as a hard mask material during long plasma dry etching, where periodically pausing the etching and chemical cleaning between cycles were leveraged to avoid thermal effects and byproduct redeposition. To improve mask quality on X- and Y-cut substrates, a H-plasma treatment was implemented to relieve surface tension by modifying the top surface atoms. Structures with etch depths as deep as 3.4 µm were obtained in our process across a range of crystallographic orientations with a smooth sidewall and perfect verticality on several crystallographic facets.
铌酸锂（LiNbO）卓越的材料特性使其成为广泛应用于射频、微机电系统、声子和光子领域的理想材料平台；然而，纳米-微米尺度的器件概念需要对铌酸锂薄膜进行高保真加工。在此，我们报道了一种高度优化的加工方法，该方法能够实现具有近乎垂直且光滑侧壁的深蚀刻。我们证明，在长时间的等离子体干法蚀刻过程中，Ti/Al/Cr堆叠作为硬掩膜材料效果极佳，通过在蚀刻周期之间定期暂停蚀刻和进行化学清洗，可避免热效应和副产物再沉积。为了提高X切和Y切衬底上的掩膜质量，实施了氢等离子体处理，通过改变表面原子来缓解表面张力。在我们的工艺中，跨越一系列晶体取向获得了蚀刻深度达3.4 µm的结构，其具有光滑的侧壁以及在多个晶面上的完美垂直度。
