Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2026
標題: 偏壓控制熱燈絲化學氣相沉積法在高速鋼上成長鑽石薄膜之研究
作者: 林長毅
關鍵字: 偏壓控制熱燈絲
高速鋼
出版社: 機械工程研究所
摘要: 本研究除了建立一套偏壓控制熱燈絲化學氣相沉積系統外,另以 矽晶片為基材,擇要對製程參數做一探討;並以工業界常用之五種硬 質膜做為介層,評估在高速網上沉積鑽石薄膜的可行性;最後針對偏 壓效應及應力現象做較深入之探討。 熱燈絲在HFCVD系統中位居最關鍵之地位,由碳化處理時電阻的變 化情形,及處理後之燈絲狀況顯示:鉭絲較鎢絲更適宜做為熱燈絲的 材料。高溫電阻率之獲得,亦可供設計大面積沉積系統之參考。 各項製程參數中,提高燈絲溫度可有效促進鑽石薄膜的品質,基 材溫度則以750℃為宜,太高會使晶形劣化,太低則不利於鑽石的成 長。外加偏壓均導致鑽石品質下降,正偏壓效應由熱電子主導,轟擊 基材會促進孕核,但激發滯留區內的反應物種,則使正離子遭到排斥, 而產生球狀組織;負偏壓則受正離子與游離電子影響,高偏壓值時, 微晶結構開始生成。 五種硬質膜介層中,氮化鉻與CVD鑽石之附著性最佳,唯鑽石薄 膜之內應力甚大,此現象可藉由降低沉積時之基材溫度獲得改善;經 由拉曼分析之特性波峰的偏移程度可計算出應力值。而鑽石薄膜係生 成於非晶質碳之上,兩者間附著性甚佳。就高速網而言,以氮化鉻為 介層時,可成功地沉積鑽石薄膜且不會剝落,至於是否可實際應用於 工具上,則尚待後續之努力。
Bias-controlled hot filament chemical vapor deposition (HFCVD) system has been set up for the synthesis of diamond films. Silicon wafer was chosen as substrate to study the processing parameters of the system. Five commercial hard films was chosen as buffer layers to evaluate the feasibility of depositing diamond films on high speed steels. Hot filament plays a vital role in HFCVD system. Variations in electrical resistivity and los of mechanical integrity due to the carburization process during depositions are main concerns for choosing the candidate filament materials. In this study, the Ta wires turn out to be more stable and durable than W wires in supporting the HFCVD process. The high temperature reistivity data of Ta and W were measured and calculated to complement the design specification of a production HFCVD system for diamond film synthesis in the furture. Among various deposition parameters, the substrste temperature showed significant effects on the film quality. An optimum substrate temperature based on thermalcouple measurements was identified as 750℃. Lower temperatures bring down both deposition kinetics and film quality. On the other hand, poor crystallinity and morphology start to develop at higher substrate temperatures. Substrate biasing affects the electron distributinand plasma behavior. Excessive electron bombardment on substrates was induced by the forward biasing and resulted in improvement in nucleation density. However, at large forward biasing potential, degradation of film quality occurred due to the local shift of methyl/hydrogen ratio as a result of additional excitation of reactive species within the boundary layer. For reverse biasing, microcrystalline structure tends to develop at higher biasing current. Chromium nitride of 4 um showed the most promising result in improving the film adhesion between the diamond film and high speed steel substrates. In addition, a non-crystalline glassy carbon film, which may contribute to the improved film adhesion was found between the diamond film and the CrN buffer layer. There existed significant intrinsic stress within the diamond films grown on CrN. The internal stress based on the calculation from the Raman peak shift is about 1.2*1011 dyn/cm2. Preliminary results showed a promising potential for depositing high purity diamond films on the CrN-coated high speed steels.
URI: http://hdl.handle.net/11455/2026
Appears in Collections:機械工程學系所

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