應用於類中醫脈診之電容式壓力感測器的微結構探討

Investigation of the Micro Structure on a Capacitive Pressure Sensor Applied on the Mimicked Diagnosis by Feeling the Pulse in Chinese Medicine by CMOS-MEMS Process

10.29688/MHJ.201002.0001

蔡健忠(Chien-Chung Tsai)；張簡嘉靖(Chia-Ching Chang Chien)；陳紀佑(Chi-Yu Chen)；馮龍田(Jung-Tien Feng)；詹欣儒(Hsin-Ju Jan)

脈診 ； 中醫 ； CMOS-MEMS ； 感測器 ； 壓力 ； Diagnosis by feeling the pulse ； Chinese Medicine ； CMOS-MEMS ； Sensor ； Pressure

明新學報

36卷1期（2010 / 02 / 01）

1 - 16

繁體中文

本微元件之設計依照國家晶片系統設計中心(National Chip Implementation Center, CIC)之製程規範作為設計之準則，並採用台積電TSMC 0.35μm 2P4M CMOS-MEMS共用製程製造用於類中醫脈診之電容式壓力感測元件。電容式壓力感測器利用脈搏跳動所產生微小的脈衝壓力，改變感測器平行板間之距離，使其電容產生變化。本設計主要為改變金屬薄膜的形狀，期望能在大範圍的感測面積下，使電容式壓力感測元件有較線性的電容響應。本元件是利用共用製程中Metal 4與Metal 2做為感測元件之上下平行板並由固定臂支撐固定，Metal 3為犧牲層並作為平行板位移時的空腔層。本文針對不同金屬薄膜形狀與固定臂長度進行模擬分析，提出兩種平行板形狀設計，分別是拼圖型與方塊型，依其在鋁之降伏應力、拉伸極限應力限制條件下分析其應力變化及最佳固定臂結構，並由元件表面之最大位移量、上平行板表面彎曲度與電容響應之曲線分析最佳的薄膜形狀。最後，應用於中醫脈診之電容式壓力感測器，受壓薄膜之形狀可採用拼圖型，其具有20μm×20μm的固定臂結構，最佳面積為7600μm^2，元件性能在操作電壓5V時，可耐脈衝壓10~60mmHg，電容響應度0.15~0.66dB，呈線性輸出，預計將可應用在體外式的微型脈搏感測器，達到用來判斷人體健康狀況之目的。

The sensing micro structure on a capacitive pressure sensor, applied on the mimicked diagnosis by feeling the pulse in Chinese medicine, fabricated by CMOS-MEMS process is investigated in this paper. Intensity and frequency of the pulse are main factors when a doctor diagnoses the condition of a patient in Chinese medicine. According to the concepts of the maximum sensing area and the successfully releasing guideline of post process, 87.2μm × 87.2μm sensing area is adopted. The effects of jigsaw and square types of the sensing micro structure and the length of the fixed arm on the maximum displacements, the variation of deformation of top plate of the capacitor and the capacitive response varied with operation pulse pressure are examined. The device is fabricated by Taiwan Semiconductor Manufacture Cooperation, TSMC 0.35μm 2P4M mixed signal model, based upon CMOS-MEMS process and its simulated mechanical and electrical performance analysis will be shown in the paper. The thickness of Metal 3 layer is 0.64μm adopted as the cavity of the capacity and will be sacrificed during the releasing process. The reasonable operation pulse pressure will be limited by the yield point and the ultimate tensile stress of the material of metal in the process. The results demonstrate a jigsaw type for the sensing micro structure with 20μm×20μm fixed arm is the optimum design for the device. The area is 7600μm^2. The range of pulse pressure is from 10 to 60 mmHg and the response of capacitance is from 0.15 to 0.66dB, and with the wider region of linearity for a jigsaw type device. It is convenient to integrate the circuit on a chip and applied on the micro sensing of the pulse for the main goal of diagnosing the human health condition in time.

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