低溫製程與雷射退火處理IZO透明導電薄膜光電與微觀特性研究

Studies of Electrical, Optical Properties and Microstructures of Indium Zinc Oxide Thin Films and Its Laser Annealing Process

吳姿穎(Tzu-Ying Wu)

指導教授 ： 邱傳聖

共同指導教授 ： 潘漢昌(Han-Chang Pan)

元智大學/工程學院/機械工程學系/碩士(2007年)

摘要

本研究討論在薄膜厚度、鍍膜氧分壓與基板溫度條件下以射頻磁控濺鍍方式成長IZO氧化物透明導電薄膜其光學、電性與微觀結構等特性變化，進一步再以低溫雷射退火處理，了解雷射退火製程參數對IZO薄膜其光電性質之影響。實驗結果顯示，隨著薄膜厚度增加將提升IZO薄膜結晶性並使得薄膜電阻率降低，而薄膜的表面粗糙度Rms約為0.4 nm。在改變鍍膜氧分壓條件中，純氬氣條件成長下，IZO薄膜載子濃度為1.4×10-20 cm-3，當氧分壓增加為3%，載子濃度減少為3.3×1016 cm-3。在SEM微觀分析中，隨著氧分壓提高，薄膜表面粗糙度增加，且產生一些微細顆粒。在改變基板溫度時，薄膜光學吸收限往短波長區移動，IZO薄膜電阻率在室溫條件至300℃區間，隨著溫度增加呈現降低趨勢，基板溫度高於400℃時，在SIMS觀察中發現薄膜表面銦原子含量降低，使IZO薄膜偏離化學劑量比，造成薄膜電阻率增加。在SEM微觀分析中，IZO薄膜晶粒尺寸隨著提高基板溫度而增加。TEM微觀影像觀察中顯示IZO薄膜在室溫鍍膜呈現奈米尺寸結晶，基板溫度增高為500℃時，IZO膜層頂端與底端呈現不同的結晶結構。在雷射退火實驗中發現，基板溫度為100℃與300雷射脈衝(shots)，雷射能量為80 mJ/cm2時可得到最佳電阻率為8.2×10-4 Ω-cm，且此時薄膜表面平均粗糙度約為Rms = 0.5 nm。

關鍵字

透明導電薄膜 ； 銦鋅氧化物 ； 雷射退火

並列摘要

Relationship among the optical, electrical properties and microstructures of transparent indium zinc oxide (IZO) films on the glass using rf. sputtering technique with a varying thickness, oxygen pressure and substrate temperature were discussed. A Nd-YAG laser was used to anneal IZO films deposited at room temperature. The experimental results showed the crystallinity of IZO films increases with increasing film thickness, as resulted in a decreasing of electrical resistivity. The surface roughness of IZO films is about of 0.3~0.4 nm regardless the film thickness. The highest electrical resistivity of 17.8 Ω-cm and lowest carrier concentration of 3.3×1016 /cm3, were obtained for the IZO films when the pressure of oxygen increases to 3%. The SEM micrographs exhibited the surface roughness of IZO film increases as the increasing of oxygen pressure. Optical absorption limit of thin films shift to the shorter wavelengths with increasing substrate temperature. The electrical resistivity of IZO films decrease with increasing substrate temperature under temperature of 300℃. The electrical resistivity of IZO films increase with decreasing Indium content of film surface when the substrate temperature higher then 400℃. The SEM micrographs exhibited the grain size increases as function of the substrate temperature. Cross-sectional TEM images implies that IZO films deposited at 500℃exhibited the upper layer of IZO films crystallized and films at the bottom layer remained amorphous. The properties of IZO films were investigated after laser annealing process. As a result of laser irradiation at 80 mJ/cm2 for 300 shots, the lowest electrical resistivity of IZO films is 8.2×10-4 Ω-cm, while the surface roughness is about 0.5 nm with the substrate temperature of 100℃.

並列關鍵字

TCO ； IZO ； laser annealing

參考文獻

[ ] T. Minami, T. Miyata and T. Yamamoto, “Work function of transparent conducting multicomponent oxide thin films prepared by magnetron sputtering, ” Surface and Coatings Technology, 108 (1998) 583.

[ ] A.S. Ryzhikov, R.B. Vasiliev, M.N. Rumyantseva, L.I. Ryabova, G.A. Dosovitsky, A.M. Gilmutdunov, V.F. Kozlovsky and A.M. Gaskov, “Microstructure and electrophysical properties of SnO2, ZnO and In2O3 nanocrystalline films prepared by reactive magnetron, ” Materials Science and Engineering, B96 (2002) 268.

[ ] T. Minami, “Transparent conducting oxide semiconductors for transparent electrodes, ” Semiconductor Science And Technology, 20 (2005) S35.

[ ] H. Nanto, T. Morita, H. Habara, K. Kondo, Y. Douguchi and T. Minami, “Doping effect of SnO2 on gas sensing characteristics of sputtered ZnO thin film chemical sensor, ” Sensors and Actuators B, 35 (1996) 384.

[ ] T. Minami, “New N-type transparent conducting oxides, ” Mirsbulletin, August 2000.