膜厚與中間層對射頻電漿輔助化學氣相沈積類鑽碳膜之影響

The Effects of Film Thickness and Intermediate layer on the DLC Films Synthesized by RF Plasma Enhanced Chemical Vapor Deposition

郭志民(Chih-Ming Kuo)

指導教授 ： 曾信雄

大同大學/工程學院/材料工程學系所/碩士(2006年)

摘要

本實驗以射頻電漿輔助化學氣相沈積法沈積類鑽碳膜，藉由改變反應氣體、氣體流量、電漿功率、工作壓力與沈積時間等製程條件，利用拉曼測量碳膜的微結構，邁克森干涉儀與奈米壓痕量測碳膜的機械性質，更進一步在相同基板上沈積不同厚度的非晶質矽中間層與在不同基板上沈積相同厚度的非晶質矽中間層，研究中間層與基材對類鑽碳膜結構與性質之影響。
由實驗結果顯示，利用射頻甲烷與乙炔電漿在工作壓力0.3 torr、功率60 W條件下，碳膜的sp3鍵結含量、硬度與楊氏模數皆隨著氣體流量的增加而下降。以乙炔為反應氣體所沈積碳膜的硬度與楊氏模數均大於以甲烷為反應氣體所沈積的碳膜。殘留應力則隨著乙炔流量的增加而下降，但隨著甲烷流量的改變並沒有明顯的變化。碳膜中sp3鍵結含量隨著工作壓力的增加，鍍膜離子能量下降而下降，導致碳膜的硬度、楊氏模數與殘留應力下降。在乙炔工作壓力0.3 torr、氣體流量10 sccm條件下，功率20 W(-270 V)的離子能量不足，碳膜為微晶石墨結構，硬度、楊氏模數與殘留應力低。隨著功率增加，碳膜內sp2鍵結含量下降，在功率60 W(-780 V)有最大硬度、楊氏模數與殘留應力。至功率80 W(-950 V)時，過高的離子能量使得碳膜產生熱震(thermal spike)之現象，導致sp2鍵結含量增加，硬度楊氏模數與殘留應力下降的趨勢。碳膜中sp3鍵結含量、硬度、楊氏模數隨著膜厚的增加而增加，但其殘留應力卻隨著沈積時間增加導致極板溫度上升而下降。另一方面，非晶質矽中間層可有效善類鑽碳膜於SK6工具鋼以及氧化鋁剛玉(Al2O3 sapphire)上之附著狀況。對於矽基材而言，沈積在中間層上的類鑽碳膜，其sp2鍵結含量相對於無中間層之類鑽碳膜高，硬度與楊氏模數也有些微下降的趨勢；而中間層膜厚在20 nm到100 nm之間的變化，對類鑽碳膜的結構與性質影響小。

關鍵字

膜厚 ； 射頻電漿輔助化學氣相沈積 ； 類鑽碳膜 ； 非晶質矽中間層

並列摘要

Diamond-like carbon (DLC) films were deposited by RF plasma enhanced chemical vapor deposition. The influence of deposition parameters, i.e. reactive gas, gas flow rate, working pressure, r.f. power, deposition time and amorphous silicon intermediate layer on microstructure as well as the mechanical properties were addressed. The microstructure and mechanical properties of the DLC film were successively measured by Raman spectroscopy, nanoindentation and phase-shifting Michelson interferometer. Further, the DLC films deposited on four different substrates (silicon wafer, glass, SK6 tool steel, Al2O3 sapphire) and amorphous silicon intermediate layer were investigated.
The results showed that all of the film sp3 content, hardness and Young’s modulus decrease with increasing gas flow rate while the supplied power and working pressure are fixed. On the other hand, the hardness and modulus of DLC films deposited by acetylene plasma are greater than those deposited by methane plasma. The residual stress decreases with increasing acetylene flow rate but no obvious changes were found with increasing methane flow rate. The sp3 content, hardness, Young’s modulus and residual stress decrease with increasing working pressure. The results of Raman spectrum indicate that carbon films deposited under 20 W have a microcrystalline graphite-like structure. The film sp3 content increases with increasing power under fixed flow rate and working pressure. The maximum values of hardness, modulus and residual stress of carbon films occur when the supplied is set to be 60 W. The higher ion energy under 80 W causes the thermal spike effect, which lead to the drop of sp3 content, hardness, modulus and residual stress. In addition, the adherence of DLC films on SK6 tool steel and Al2O3 sapphire was improved by amorphous silicon intermediate layer. For the Si substrate, we observed that the sp3 content, hardness and Young’s modulus of DLC films deposited with amorphous silicon intermediate layer are less than those of DLC films deposited without intermediate layer. However, the changes of intermediate layer thickness from 20 nm to 100 nm have no significant effect on microstructure and mechanical properties of DLC films.

並列關鍵字

film thickness ； RF plasma enhanced chemical vapor deposition ； diamond-like carbon ； amorphous silicon intermediate layer

參考文獻

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