Platinum assisted chemical etching of single- and poly-crystalline silicon with applications to templated nanomaterials

When emerging nanofabrication techniques are explored for improved performance in semiconductor device fabrication, they need to substantially improve in their performance and/or cost relative to incumbent process technologies. These incumbent technologies align themselves to the CMOS (Complimentary Metal Oxide Semiconductor) semiconductor roadmap, which continuously strives towards reduced feature size, increased aspect ratio, and increased fabrication throughput for complex 3D architectures. Metal Assisted Chemical Etching (MacEtch) is an emerging wet etch technique with potential to outperform reactive ion etch (RIE) methods. At nanometer scale patterns, RIE methods have limitations in the quality of high aspect ratio nanoscale structures due to potential for tapered profiles and high side wall roughness. MacEtch is capable of producing anisotropic, high aspect ratio features with atomically smooth, vertical sidewalls in silicon materials with high throughput capability. MacEtch requires a catalyst that enables a reaction just underneath it, which leads to silicon being etched beneath the catalyst. The catalyst that is predominantly reported in the literature is gold (Au). However, Au is an undesirable material choice for CMOS fabrication as it leads to deep level defects in silicon. In the MacEtch research literature non-Au catalysts such as Ruthenium (Ru) and Platinum (Pt) have been recently reported. But these non-Au results could require process steps that are not CMOS friendly (e.g., requiring high temperature annealing) and do not have tunable process quality (non-porous, atomically precise high aspect ratio silicon nanostructures) equivalent to Au-based MacEtch methods. This dissertation demonstrates a MacEtch process that utilizes a Pt catalyst with process steps that do not conflict with CMOS process flows. This process is also capable of wafer-scale process quality that is comparable to Au-based MacEtch. In addition to overcoming catalyst limitations, this work demonstrates MacEtch in both liquid and gas phases with anneal-free Pt catalyst. The gas phase etching has demonstrated the ability to produce >100:1 aspect ratio in silicon. In addition to semiconductor fabrication where silicon etching is valuable, there are a number of applications in areas including medicine, optics, and energy storage that require high-quality nanofabrication methods for non-silicon materials. This work has developed a demonstrated an approach for extending nanoscale precision, high-aspect ratio, and nano-dimensional capability of MacEtch to non-silicon materials by the use of a novel approach enabled by fabrication of silicon templates.