水熱法沉積PZT壓電薄膜應用於微致動器之開發

Deposited PZT film for microactuators using a hydrothermal method

林宏展(Hong-Zhan Lin)

指導教授 ： 楊啟榮

國立臺灣師範大學/科技學院/機電科技研究所/碩士(2006年)

摘要

傳統之陶瓷壓電材料鋯鈦酸鉛(PZT)薄膜，必須使用射頻磁控濺鍍法，或是以溶膠-凝膠法(sol-gel)旋塗後，再經由高溫燒結(650 ?C-700 ?C)而成，其生產之製程設備昂貴、薄膜結構製程複雜或經高溫燒結會使微元件受到破壞等缺點。因此，必須發展低溫製程之鋯鈦酸鉛薄膜沉積，以實現低成本微元件之開發。水熱合成法是將化學溶液放置在密閉容器中，加熱至120 ~ 200 ?C使容器內部達到飽和蒸汽壓力，藉著高溫高壓之環境析出所需之物質。由於水熱法擁有低製程溫度與製造成本，且容易製作厚膜，故本研究使用水熱法來沉積鋯鈦酸鉛薄膜，並且利用此薄膜沉積技術製作壓電式微致動器。
本研究在探討鈦金屬層對於水熱法沉積之特性，利用不同之鈦金屬層厚度觀察其沉積情形；再者，透過低溫之基板前熱處理方式，改善薄膜之附著性；最後嘗試著控制成核及晶體成長之沉積機制改善薄膜之密度。研究結果證實，鈦金屬層於水熱法中是當作沉積之起始層，且鈦金屬層會在開始沉積時提供反應所需之鈦離子，增加鈦金屬層厚度可以加快薄膜沉積速率。本研究成功在1 ?m之鈦金屬層輔助下，使鋯鈦酸鉛薄膜之沉積速度達到6.20 ?m / 24 hr，但是鈦金屬層超過1 ?m後，對於沉積速率並無太大的影響。本研究利用200 ?C持溫一小時之基板前熱處理條件下，有效的改善鋯鈦酸鉛薄膜之附著性。本研究以提高水熱溶液之反應物濃度，控制薄膜在成核機制下進行沉積之方式，製作出密度為 4.402 ? 103 kg / m3之薄膜。
本研究預期利用發展出之鋯鈦酸鉛薄膜沉積方式，製作懸臂樑壓電微致動器，但遇到矽基材表面之氮化矽覆蓋不緻密，導致矽基材受到KOH攻擊之問題，目前仍致力於保護矽基材之方式進行研究。

關鍵字

鋯鈦酸鉛薄膜 ； 水熱法 ； 壓電微致動器

並列摘要

Traditional deposition of ceramic piezoelectric lead zirconate titanate (PZT) thin film was used RF magnetron sputtering method, or sol-gel method spin-coating before sintered at high temperature (650 ?C ? 700 ?C), it has some shortcomings, those are: process equipment expensive, process complicated and damage structure by the high-temperature sintering process. Therefore, it is necessary to develop low-temperature process for PZT thin film deposition.
Hydrothermal method is to synthesize requirements substance during high temperature and high pressure environmental. The cost and temperature of the method is rather low. In this study, we deposit PZT thin films by hydrothermal method, and fabricate piezoelectric microactuator using this technology.
The purpose of this study was using different thickness of the titanium layer to investigate the characteristics of titanium layer for hydrothermal deposition. Furthermore, it is to improve the adhesion of PZT films by pre-heat treatment of substrate at low temperature. Finally try to control nucleation and crystal growth process of deposition to improve the density. We developed a high deposition rate which was 6.20 ?m / 24 hr on nickel substrate with Ti layer of 1 ?m. In this study, we improved the adhesion of PZT film by pre-heat treatment of 200 ?C temperature of one hour. We improved the density of the PZT film to 4.403 ? 103 kg / m3 by controling the concentration of hydrothermal solution.

參考文獻

2. R. G. Kepler and R. A. Anderson, "Ferroelectricity in polyvinylidene fluoride", Journal of applied physics, Vol. 49, No. 3, pp. 1232-1235 (1978).

4. Z. Ounaies, J. S. Harrison and R. J. Silcox, "Piezoelectric materials for sensor and actuator applications at NASA LaRC", Quarterly newsletter of the institute for computer applications in science and engineering, Vol. 8, No. 2, pp. 12-23 (1999).

7. B. Ploss, P. Lehmann, H. Schopf, T. Lessle, S. Bauer and U. Thiemann, "Integrated pyroelectric detector arrays with the sensor material PVDF", Ferroelectrics, Vol. 109, pp. 223-228 (1990).

9. D. Cathignol and A. Thomas, "PVDF hydrophone with liquid electrodes for shock wave measurements", IEEE ultrasonics symposium , Vol. 1, pp. 341-344 (1990).

10. G. W. Taylor, J. R. Burns, S. M. Kammann, W. B. Powers and T. R. Welsh, "The energy harvesting eel: a small subsurface ocean/river power generator", IEEE journal of oceanic engineering, Vol. 26, No. 4, pp. 539-547 (2001).