An In-Line Method for Extracting and Mapping CD-Loss and Side-Wall Angle in DRIE

Addressing the problem that the non-ideal effect in deep reactive ion etching (DRIE) process leads to the cross-section dimension deviation of structure, this paper proposes an precise in-line method for extracting cross-section dimensions of high-aspect-ratio movable microbeams fabricated by DRIE. By mathematically fitting the responses of test structure under loading into mechanical model, we extracted CD-loss and side-wall angle (SWA), with theoretical precision not less than 0.03 μm and 0.15° (1σ interval), respectively. The method was applied to two bulk silicon fabrication MEMS production lines, successfully acquiring full-wafer mappings (FWM) of cross-section dimensions under four different etch widths, demonstrating its capability to monitor process quality in mass production.