大氣電漿技術沉積二氧化矽薄膜之機械性質探討

Abstract

本文係利用噴射式大氣電漿鍍膜技術，電漿氣體為氮氣並在電源以功率500 W、頻率20 kHz及室溫和一大氣壓力下產生電漿源。使用有機矽源的六甲基二矽氮烷(Hexamethyldisazane，HMDSN)當作沉積二氧化矽薄膜的前驅物。改變不同的前驅物流量、處理時間及基板溫度等實驗因子，經由奈米壓痕儀量測楊氏模數，來了解機械性質的變化。同時使用霍氏轉換紅外光譜儀(FTIR)、原子力顯微鏡(AFM)及掃描型電子顯微鏡(SEM)來分析影響機械性質改變的因素。 經大氣電漿所沉積的二氧化矽薄膜其機械性質改變會受到表面孔洞情形變化的影響。其楊氏模數的結果會隨著基板溫度增加而增加，但是會隨著前驅物流量及處理時間增加而減少。實驗中也發現在室溫下沉積的二氧化矽薄膜再經過退火處理會使得薄膜更加緻密，其楊氏模數也會隨之提升。在退火溫度為 800 ℃及退火時間為5小時，其楊氏模數相較於未經退火的40.2 GPa提升至54.7 GPa且最大平均深度(Rvm)改善約12 %左右。

Atmospheric pressure plasma jet (APPJ) chemical vapor deposition (CVD) technique is utilized in this paper. The jet operates by feeding nitrogen gas between two electrodes that driven by a 20 kHz frequency and 500 W power source at atmospheric pressure and near room temperature. The organic silicon source Hexamethyldisazane (HMDSN) was utilized as the precursor of silica films. With distinct experiment factors, such as the flow rate of precursor, deposition time and substrate temperature, we measure the mechanical properties via nano-indentation system. Moreover, the variation of the mechanical properties analyzed by Fourier-transform infrared spectrometer (FTIR), atomic force microscope (AFM) and scanning electron microscopy (SEM) were obtained that correlated with surface porosity. The results presented that the Young’s modulus of silica films deposited by APPJ CVD increased with increases in the substrate temperature, however, decreased with increases in the active precursor concentration and deposition time. When the films were deposited near room temperature after annealing in air, these films exhibited denser structure and higher Young’s modulus. Comparing non-annealing with annealing at 800 ℃ in 5 hours, the Young’s modulus increased from 40.2 GPa to 54.7 GPa and average maximum depth (Rvm) modified more about 12 %.