內藏式模具溫度與壓力感測器研製

指導教授 : 黃榮堂    研究生 : 游展彬  機電整合研究所 87年


摘要

本研究以鋯鈦酸鉛(PZT)薄膜優越的壓電性質,作為壓力感測器(pressure sensor)感測主體。利用射頻磁控濺鍍法(RF sputtering),製備大面積、低損傷、高壓電係數的壓電薄膜,應用其基本的壓電特性,而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。本壓力感測器所採用的結構為Al/PZT/Pt/Ti/SiO2/Si,其中採用Pt為高溫金屬電極,但Pt與Si高溫易形成矽化物,所以,通常在Si和Pt間成長SiO2作為阻絕層;又Pt與SiO2附著性不佳,中間層Ti或Ta的置入以增加附著性;Al則作為上電極之用。

實驗結果顯示,鋯鈦酸鉛薄膜以基板溫度300℃以上,操作壓力0.05 torr,射頻輸入功率100 W,工作間距5 cm,氧氣100 SCCM成長,再以650℃以上的一般爐管退火,3℃/min. 溫升速度,650℃定溫2hr. , 如此可得高結晶方向的鈣鈦礦壓電薄膜,其殘餘極化量Pr=3.438 m C/cm2,矯頑電場Ec=100 KV/cm2,壓電常數d33=191 pC/N。

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, lead-zirconate-titanate (PZT) thin films with excellent piezoelectric properties were deposited on a silicon-based wafer as pressure sensing elements. The thin films were fabricated by means of RF-magnetron sputtering using a composite target. The complete sensing elements were constructed with a multi-layered structure of Al/PZT/Pt/Ti/SiO2/Si, where silicon oxide as a barrier between Si and Pt, Pt as a lower electrode, Ti as an adhesive between Pt and SiO2, and Al as upper electrode.

The high oriental and crystal thin films with peroveskite structure could be obtained in our experiments. The conditions are following as: substrate temperature over 300℃, separation between target and substrate 5 cm, pressure 0.05 torr, RF power 100 W, pure oxygen 100 SCCM, and furnace annealing with 650℃, 2 hours, 3℃/min. Remnant polarization, coercive field, and piezoelectric constant of the PZT films are Pr=3.438 m C/cm2, Ec=100 KV/cm2 and d33=191 pC/N, respectively.