利用螺旋式電極的常壓射頻電漿束鍍製氧化矽薄膜之研究

Abstract

本文係探討以同軸式耦合射頻常壓電漿系統進行鍍製氧化矽(SiOx)薄膜技術之研究。利用同軸式耦合射頻電漿，放電氣體為混合的氬氣與氧氣，電源頻率為13.56 MHz，在一大氣壓條件下產生電漿源。在使用石英管包覆內層螺旋式電極下，氬氣可以混合高比例的氧氣(10%) 並產生穩定且無電弧的電漿。利用本系統進行鍍製氧化矽薄膜，使用六甲基二矽氧烷 (Hexamethyldisiloxane, HMDSO) 做為沈積薄膜之前驅物，並利用氬氣做為前驅物的載體，將前驅物導入後放電區域沈積氧化矽薄膜於矽基材上。改變不同實驗參數來探討薄膜特性，包括處理次數、處理距離(3-7.5 mm)、輸入功率(35-50W)、氧氣濃度(0-10 %)及基板溫度(25-300 oC)。由實驗結果得知，鍍膜沈積速率會隨著處理次數、輸入功率及氧氣濃度增加而增加; 隨著處理距離、基板溫度增加而減少。並進一步去探討在不同的氧氣濃度及基板溫度下進行鍍膜，薄膜特性的變化。 在輸入功率為50 W、基板溫度為300 oC、處理距離為5 mm的實驗參數下進行鍍膜，氬氣電漿在無氧氣添加下，鍍膜速率為37.5 nm/min，若氧氣濃度增加至0.8%，鍍膜速率會明顯上升至275 nm/min 但是在氧氣濃度增加至2 %以上，發現會有高孔性的結構產生。由FTIR及XPS量測結果發現，薄膜中碳的成份會隨著基板溫度增加而減少。在較高的基板溫度下進行鍍膜可以降低鍍膜速率，並減少薄膜孔性程度，且提高薄膜硬度。 總結來說，在氬氧電漿混合適當比例的氧氣下，我們可成功於後放電區沈積氧化矽薄膜，並且在不同實驗參數下討論薄膜的特性。同時在論文的最終節列出建議未來應進行的研究。

Thin film deposition of silicon oxide (SiOx) using a radio-frequency (13.56 MHz) coaxial argon atmospheric-pressure plasma jet (RF-APPJ) has been investigated experimentally in this thesis. A stable, arc-free swirling APPJ was produced with a spiral powered electrode covered by a quartz tube, which makes the addition of oxygen (up to 10%) possible without extinguishing the discharge. This APPJ was employed to deposit silicon oxide thin films using a precursor, hexamethyldisiloxane (HMDSO), diluted in an argon carrier gas, into the post-discharge region. Test conditions included variations of treatment passes, input power (35-50 W), treatment distances (3-7.5 mm), oxygen additions (0-10%), and substrate temperatures (25-300 oC). Results show that deposition rate increased with increasing treatment passes, input power, oxygen addition and decreased with increasing substrate temperatures and treatment distances. The variation of oxygen addition and substrate temperature greatly affected the properties of silicon oxide thin films. The deposition rate of the silicon oxide thin film was 37.5 nm/min using pure argon plasma with 50 W RF power, 300 oC substrate temperature and 5 mm treatment distance. When oxygen addition increases to 0.8%, the deposition rate increases to 275 nm/min. However, oxygen addition is more than 2%, highly porous, particle-like structure was formed. FTIR and XPS measurements show that quantity of carbon atoms, the degree of porosity and deposition rate in the film decrease with increasing substrate temperature. However, the hardness of the film surface increases with increasing substrate temperature. In summary, we have successfully deposited and characterized the silicon oxide films formed in the post-discharge region of a RF-APPJ using argon mixed with oxygen. Recommendations for the future study are also outlined at the end of the thesis.