Improvement of High Dynamic Range Capacitive Displacement Sensor by a Globalm Planarization

Abstract

This study presents an improvement of high dynamic range contact-type capacitive displacement sensor by applying planarization. The sensor is called the contact-type linear encoder-like capacitive displacement sensor (CLECDiS), is a nano-meter-resolution sensor with a wide dynamic range. However, height differences due to patterned electrodes may cause a variety of problems or performance degradation. In devices of two glass wafer surfaces with patterned structures assembled face-to-face and in sliding contact, the heights of the patterns crucially affect their performance and practicality, so it should be planarized for reducing the problem. A number of techniques for planarizing glass wafer surfaces with patterned chrome electrodes were evaluated and the following three were selected as adequate: lift-off, etch-back, and chemical mechanical polishing (CMP). The fabricated samples showed that CMP provided the best planarization. CMP was successfully employed to produce CLECDiS with improved signal reliability due to reduced collisions between electrodes

Micro-Machined Capacitive Linear Encoder with a Mechanical Guide

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