- 學位論文
利用電漿放射光譜診斷MPJCVD系統成長奈米晶鑽石膜及其光電導特性研究
A Study of Growing Nanocrystalline Diamond Films by In-situ Plasma Diagnosis of Chemical Species on MPJCVD System and Photoconductivity of As-grown Films
摘要
在CVD法成長奈米晶鑽石(NCD)膜製程中，電漿通常主導整個反應機制。因此電漿物種(CH、H2、Hα、C2與Hβ等)對於NCD膜成長過程中扮演極重要的角色。由於NCD膜材料特性(電性、物性及表面特性)是由材料鍵結所決定的，而材料鍵結之組成又與電漿內部物種及其濃度有直接的關係。因此利用電漿放射光譜儀(OES)診斷鑽石膜成長中電漿物種的組成情況，即可同時瞭解製程參數、電漿物種及薄膜結構與特性三者間的關係，對製程穩定性有相當大的幫助。 本研究中，完成設計組裝MPJCVD系統，並藉由田口法實驗設計探討CH4+H2電漿製程參數對合成NCD膜特性影響。並利用NCD晶種法處理獲得高成核密度(4.4 x 1010 cm-2)、成長速率(2.4 μm/hr)及均勻性(Rms=27.06 nm)的NCD膜。另外藉由電漿診斷技術監測電漿物種及性質，以及NCD膜特性分析結果，可清楚定義CH4+H2電漿、高Ar/CH4+H2濃度電漿、摻氮及摻硼的放射光譜，並發現摻氮及摻硼將有效提升NCD膜導電性，分別為6.70 x 10-4及2.30 x 10-3 Ω-cm。 在NCD膜紫外光感測器的光電導特性中，發現將Au/NCD膜交指型電極圖案結構，以450℃退火處理可獲得線性的I-V曲線，形成良好的歐姆接觸。並從暗與光電流的光電導實驗結果，可得平均電流增益為G=33.4，以及有效的光電時間響應(2.1 s)，證實已達到紫外光感測器的應用標準，且具有偵測紫外光光源強度之能力。 總結來說，本論文對於電漿在NCD膜製程上所扮演的角色加以深入的探討，利用電漿放射光譜診斷技術釐清電漿製程中的關鍵機制，以確定完整電漿合成NCD膜的成長模式，並完成NCD膜應用於紫外光感測器的可行性分析，希望可提供給相關研究和實驗製程上的參考。
並列摘要
Plasma usually dominates the whole reaction mechanism in growing nanocrystalline diamond (NCD) films during the CVD process. Therefore plasma species, such as CH, H2, Hα, C2, and Hβ, play extremely important roles in the process of NCD films growth. The properties of NCD films, such as electrical, physical, and surface characterization, depend strongly on the bonding of the film’s materials, while types of atomic bonds relate to plasma species and their concentrations. Therefore by diagnosing composition of plasma species in growing NCD films with in-situ plasma optical emission system (OES), the relationship between process parameters, plasma species, and film structure and properties can be understood simultaneously. This will be of great help to the stability of manufacturing process. This study accomplished the design and assembly of MPJCVD system, and employed Taguchi Method DOE to analyze the effect of process parameters in CH4 + H2 plasma on the properties of synthesized NCD films. NCD seeding nucleation can be used to obtain uniform and smooth (Rms = 27.06 nm) NCD films with high nucleation density of 4.4 x 1010 cm-2 and growth rate of 2.4 μm/hr. Next, plasma diagnosis technology is utilized to identify plasma species. Through combining the results of the analysis of NCD films characterization can be clearly defined the optical emission spectra and growth environments of CH4+H2 plasma, high Ar/CH4+H2 plasma, nitrogen-doped NCD films, and boron-doped NCD films. It is also discovered that the dopant of nitrogen and boron can effectively promote the conductivity of NCD films to 6.70 x 10-4 and 2.30 x 10-3 Ω-cm respectively. From the photoconductivity of NCD film UV-detector, it is discovered that excellent ohmic contact can be achieved by conducting 450℃ annealing treatment for Au/NCD films IDF electrode structure. And from the photoconductivity experiment of dark current and photo current can be calculated the mean current gain of G=33.4 and effective temporal response (2.1 s). It is thus proved that NCD films has reached the standard for application in ultraviolet detector and possesses the capability of detecting the intensity of ultraviolet source. In summary, this thesis makes an in-depth exploration of plasma’s role in the NCD films process. Plasma diagnosis technology is used to clarify the key mechanism and conception for plasma process and determine the pattern of thinking for the complete plasma synthesis of NCD films. Also the feasibility of NCD film’s application in ultraviolet detector is carried out in the hope that it provides reference for relevant research and experiment process.