低溫大面積直接沉積複晶矽薄膜之技術開發Technology; Development of the Direct Fabrication of Large-area Polycrystalline Silicon Thin Films at Low Temperature

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6602

Title:	低溫大面積直接沉積複晶矽薄膜之技術開發Technology;Development of the Direct Fabrication of Large-area Polycrystalline Silicon Thin Films at Low Temperature
Authors:	古建德;Jian-De Gu
Contributors:	光電科學研究所
Keywords:	大面積微波電漿源;電漿輔助化學氣相沉積法;射頻偏壓;低溫製作;複晶矽薄膜;Large-area Microwave Plasma Source;Polycrystalline Silicon Thin Film;RF-bias;Low-temperature Fabrication;Plasma-enhanced Chemical Vapor Deposition
Date:	2005-07-02
Issue Date:	2009-09-22 10:23:43 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究分兩階段進行，第一階段應用偏壓輔助射頻電感耦合式電漿輔助化學氣相沉積系統（RF-biased RF inductively-coupled PECVD），以矽烷（SiH4）、氫氣（H2）、氬氣（Ar）等混合氣體為原料，成功地在玻璃基板及單晶矽基板上直接成長大晶粒複晶矽薄膜。第二階段則應用可調式陣列天線微波電漿輔助化學氣相沉積系統（Adjustable Array Antenna Microwave PECVD, Triple-A M-PECVD）進行矽薄膜之大面積低溫沉積，目標是在34 cm ´ 45 cm的基板面積上成長出複晶矽薄膜。在第一階段的實驗中，利用偏壓效應可成功地在82 °C以下成長出晶粒尺寸約為0.15 ~ 0.3 μm的複晶矽薄膜。經XRD繞射分析得知矽薄膜具有(111)-Si的優選方向，經FTIR檢測後發現薄膜均含氫。研究中發現，在適當的電容耦合能量範圍內，此RF能量可視為基板負偏壓效應。隨偏壓能量增加，對晶粒尺寸、薄膜結晶性、沉積速率等特性有改善效果。另一方面，在較大的電容耦合能量下，電容耦合與電感耦合所形成的電漿區有疊加效應，適合複晶矽薄膜沉積的範圍可由單一位置再擴大至約10 cm徑向的範圍內。在第二階段的實驗中，利用天線陣列可將微波範圍放大，形成一個大面積化的微波電漿源。在使用與第一階段相同的氣體原料下，藉由改變微波功率、射頻功率、反應氣體流量、鍍膜時間等參數，來研究其對矽薄膜品質的影響。本實驗中H2/SiH4之最佳氣體流量比例為25，在此比例下矽薄膜之晶粒尺寸可藉由增加微波功率、延長鍍膜時間等實驗參數來改善，最大尺寸可達100 nm。薄膜沉積之面積可達基板面積的70 % 以上，且表面粗糙度變化在5 % 以內，沉積溫度依然低於82 °C，然而厚度均勻性及薄膜結晶性依然有待改進。 Large-area polycrystalline silicon (poly-Si) thin films are fabricated by employing both the RF-biased RF inductively-coupled PECVD and the Adjustable Array Antenna (Triple-A) microwave PECVD system at temperature lower than 82 °C. High purity (99.99 %) SiH4, H2, and Ar are introduced as reaction gases, and ultrasonically cleaned glasses and p-type (100) silicon wafers are used as substrates. In the RF-biased RF inductively-coupled PECVD system, poly-Si thin films with grain size about 0.15 ~ 0.3 μm are successfully fabricated by applying another capacitively-coupled RF power on substrates. All crystalline silicon films exhibit (111)-Si preferred orientation. Under proper deposition conditions, the capacitively-coupled RF power can be taken as bias. The deposition rate, grain size, and crystallinity of poly-Si thin films are improved as the RF bias power increased to 5 watts. However, under higher RF bias power, the superposition of the plasma regions generated by the RF main power and the RF bias power are observed; thus results in a proper plasma environment with 10 cm wide in axial direction for poly-Si thin films deposition. In the triple-A microwave PECVD system, three sets of array antenna composed by many copper rods with adjustable length are employed to couple the large-area microwave power into the deposition chamber. Silicon films with grain sizes about 80 ~ 100 nm and surface roughness uniformity within 5 % are successfully deposited over 70 % of the 34 cm ´ 45 cm substrate holder. Further studies will focus on the modification of the system design so as to reach the goal to deposit silicon films with improved crystallinity, larger grain sizes, and more uniformity over the large area.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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