微機電技術與壓電塊材在感測器的

應用研究

Study on the Application of Sensors with MEM Technology and Bulk PZT

 

摘要

本研究以鋯鈦酸鉛(PZT)優越的壓電性質,並使用塊材的形式,以其穩定的特性,配合微機電的技術,來作為壓力感測器(pressure sensor)與超音波感測器(ultrasonic sensor)的主體。

在絕緣層方面,是利用射頻磁控濺鍍法(RF sputtering),製備大面積、且平坦的絕緣層,並在絕緣層與上電極間,加入以濺鍍方式製成的鋁,來改善原來塊材上電極的粗糙度,使得絕緣層得以成功的絕緣。再利用微影、蝕刻的精密尺寸,做出連接電極與晶片座(plug)中導線的接觸窗(contact),使得元件作用時,得以順利的將電荷引出。此壓力感測器工作環境,乃應用在射出成形的模具內,感測出模具內部即時的壓力值。由於模具內部為高壓、高溫環境,且有腐蝕感測器的考量;同時,感測器的擺入,絕不可破壞射出成品的品質;所以,體積小、耐高溫、高壓、且抗腐蝕的特殊型壓力感測器是必要的。

實驗結果顯示,本壓力感測器在定性的測試上,不論是零輸入、變化輸入和穩態輸入,本系統的輸出上呈現強烈的對比,並未有不合理的狀況產生。定量方面,在靈敏度上,本次所發展的感測器與市售產品比較,在0.5 SEC內極為相似﹔在線性誤差上為20%,需再進一步的改善感測器本體的結構。在超音波感測器方面,則進行了初步的研究與設計。

 

 

 

Abstract

To promote the quality of the molding injection products, the process of injection would be monitored by measuring the instant pressure variation in the mold cavity with a small-size and erosion-resistant pressure sensor. In this study, bulk lead-zirconate-titanate (PZT) with reliable piezoelectric properties were used in sensors as pressure and ultrasonics sensing elements. By tacking advantage of micro-electrical-mechanical (MEM) technology , the sensing element can be fabricated with low cost and high performance.  

The formation of the isolation layer is to use RF-magnetron sputtering method. Since the surface roughness of electrode of the bulk PZT is too large to sputter a isolation layer of SiO2 directly, a layer of aluminum is plated by DC sputtering method in advance. The results show the surface roughness of the electrode has been improved up to an acceptable range. After this, a series of process, such as, SiO2 sputtering, lithography, etching and packaging are followed to complete the pressure sensing element and the pressure sensor.

Some experiments are implemented to evaluate the performance of the package sensor. The results show that the static and dynamic response is close to the similar products in the market.