This paper proposes a novel method based on the surface acoustic wave (SAW) sensor for monitoring in situ the thickness of a silicon membrane during batch chemical etching. Like pressure sensors and accelerometers, some micro-electro-mechanical systems (MEMS) devices require the thickness of silicon membranes to be known precisely. Precisely controlling the thickness of a silicon membrane during batch chemical etching is important, because it strongly influences postprocessing and device performance. In summary, the proposed method for measuring the thickness of a silicon membrane in real time from tenths of μm to 80 μm, is highly accurate, is. simple to implement and can be mass-produced. The principles of the method, detailed process flows, the setup for measuring thickness and simulation and experimental results are all discussed. The theoretical and measured values differ by an error of less than 3.00 μm, so the experimental and theoretical values correlate well with each other.
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