模內溫度即時量測薄膜矽基熱電偶之研製

Fabrication of Thin-film Thermocouples on Silicon Wafers for Real-time Measurements of Temperature in Mold Cavity

指導教授 : 黃榮堂    研究生 : 羅國綸  機電整合研究所 88年


摘要

本研究是製作薄膜式溫度感測器,將傳統熱電偶應用現今半導體工業技術,利用射頻磁控濺鍍法(RF sputtering),沈積Chromel、Alumel與SiO2薄膜,並且配合微影蝕刻、封裝技術以作為感測元件的主體,由於此感測器主要應用於射出塑料溫度的量測,在設計的過程中提出兩種感測器製作流程,主要差異在是否作Si的背面蝕刻,以因應模具內體積小、高溫、高壓、腐蝕性的環境,達成尺寸微小化與快速響應的目標。本溫度感測器所採用的結構為Si/SiO2/ Chromel /SiO2/Alumel /SiO2,其中SiO2為保護層與絕緣層,Alumel與Chromel為主要感測金屬,而為了達到快速響應的目的,兩層金屬在測頭部分接觸面積應盡量微小。
實驗內容將討論濺鍍、微影蝕刻、封裝製程中,各種製程參數的選定以及對元件的影響,包含薄膜品質、附著性、響應速度、雜訊、穩定性等,並且比較兩種元件製作方法的優缺點,還有在封裝部分中絕緣陶瓷材料的選擇。選擇Chromel與Alumel金屬薄膜在300℃,Ar 100sccm,工作壓力0.05 torr,經回火熱處理後有較佳的結晶與附著性。封裝完成之後,暫態響應時間常數為0.2秒,且經由磨耗測試感測頭有自動更新(Self Renewing)現象。
本薄膜式溫度感測元件經過不斷的改進,在設計與製作上都經過詳細的評估與研究,各項製程已逐漸確定,並且也將兩種設計類型製作成品,經由初步測試驗證後,將實際裝置在模具中作射出塑料的溫度量測,以驗證是否符合規格要求。

ABSTRACT

This research is developed to manufacture thin-film thermocouple temperature sensors. The manufacturing process of sensors is resulted from the knowledge of semiconductor processes including RF sputtering, photolithography, etching and package technologies. The structure on silicon wafers consists of five layers SiO2/Chromel/SiO2/Alumel/SiO2. The thin-film thermocouple is used to measure temperature distributions between R.T. to 350℃ of polymer melts in the cavity of an injection mould. We proposed two manufacturing process of thin-file thermocouple temperature sensors in order to reach fast response and small size. Besides, the sensors is protected from high pressure and corrosion in the injection environment. In order to reach fast response, the contact area of two metal must be as small as possible.
The contents of experiments discussed parameters seletion of sputtering, photolithography, etching and package process. It is also analyzed membrane quality, adhesivity, noise and stability. We compared the adventages and disadvantages of two different manufacturing process.
The experiment results show at the experiment conditions of substrate temperature 300℃, R.F. sputtering, power 100W, 0.05 torr, Ar flow rate 100 sccm, we had good films quality. The time constant of the thermocouple response is 0.2 secs after package process. It is better than the response time(0.45 secs) of the NANMAC PENCIL ERODING PROBE THERMOCOUPLE E 12-3. .