Abstract
High aspect ratio (AR) Silicon base structure plays an important role in semiconductor industry. Recent advances in small size and multifunctional chip has made the increased demands of fabrication of micro and nano scale high AR silicon structure. However, the commercial fabricating method, deep reactive ion etching (DRIE) suffers from high cost and complex processing due to the high maintenance fees and complicated set up. In contrast, we investigate the ability of promising novel chemical etching, metal assisted chemical etching (MACE) that can etch Silicon (Si) wafer in <100> direction near room temperature and thus benefits from it’s simple and cost effective reaction process. In order to fabricate high AR silicon micro holes structure, we have optimized our MACE recipe by employing statistical Taguchi L9 method and ANOVA analysis. Subsequently, the post-MACE formed Si wires have been removed by furnace oxidation followed by Hydrofluoric acid (HF) treatment. Therefore, high AR Si micro holes structure with smooth surface is obtained. Our results demonstrate that the AR value is up to 13 (for 4x4um square arrays in p-type (100) Si substrate), and the etching rate of optimal condition is about 3 µm/min. Moreover, an alternative method that possess larger throughput for fabricating high AR Si micro structure has been performed. Besides, it is believed that the AR value can be further improved by increasing the thickness of Si nitride layer (protection layer), using stronger protection layer instead, and exploring the method that can well-control the morphology of metal catalyst which strongly influence the post-etched structure.