Journal
JOURNAL OF MICROMECHANICS AND MICROENGINEERING
Volume 30, Issue 6, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/1361-6439/ab8909
Keywords
pressure sensor; barometer; scar-free; MIS process; single wafer; single-side; low-cost
Categories
Funding
- National Science Foundation of China [61674160, 61834007]
- Ministry of Science and Technology of China [2016YFA0200800]
- National Key Research and Development Program of China [2016YFA0200803]
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This paper presents a tiny 0.4 mm x 0.4 mm piezoresistive absolute pressure sensor chip with a fabrication cost as low as 0.01 US$/die. With the thin-?lm under bulk-silicon technique, a very thin but uniform poly-silicon pressure-sensing diaphragm is formed beneath a bulk-silicon beam-island structure to accommodate piezoresistors. The thin diaphragm exhibits a high sensitivity, and the beam-island-reinforced structure helps reduce deflection and improve linearity. The sensor is fabricated using a novel scar-free micro-hole inter-etch and sealing (MIS) process. In this newly developed process, seals are removed from the diaphragm area and placed on both the single-crystalline silicon island and single-crystalline silicon frame surrounding the poly-silicon diaphragm. Thus, the thin diaphragm is kept flat and smooth, thereby enhancing the sensing performance and fabrication yield. More importantly, the diaphragm-beam-island structure is small enough to fabricate sensor chips as small as 0.4 mm x 0.4 mm. With the high-yield process, a very low fabrication cost of 0.01 US$/die is realised owing to a high throughput of 90 000 die per 6 inch wafer. The ultra-small and low-cost pressure sensor exhibits sensitivity of 0.88 mV kPa(-1)/3.3 V, hysteresis of 0.15% full scale (FS), repeatability error of 0.04% FS, and non-linearity of +/-
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