Achieving an aspect ratio of 52
Deep reactive ion etching (DRIE) with an aspect ratio of 52, featuring smooth sidewalls and a scallop size of less than 100 nm. The achievable etching depth is primarily limited by the mask thickness—the thicker the mask, the higher the aspect ratio that can be processed. For a 300 nm pattern with sufficient mask thickness, an aspect ratio of up to 100 is possible. Additionally, narrower trenches offer a distinct advantage in achieving higher aspect ratios.