噴射式大氣電漿系統之設計架設與多次沉積氧化鋅鎵薄膜性質之量測與模擬

Development of NTU APPJ System, Measurement and Simulation of the Properties of Ga-doped ZnO films Prepared by Multiple Depositions

陳于壹(Yu-Yi Chen)

指導教授 ： 莊嘉揚

國立臺灣大學/工學院/機械工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602432

摘要

本研究使用直流脈衝電源產生之噴射式大氣電漿(Atmospheric Pressure Plasma Jet, APPJ)鍍製GZO薄膜，優點是免去高昂的真空腔體費用，且能夠透過小面積漸進式的掃描將薄膜鍍製在大面積基板上。目前許多研究指出將不同薄膜材料層層堆疊之多層膜沉積法(multi-layer deposition)，能夠有效製造出高光電性質之薄膜，但礙於需更換製程材料，提高了時間及製造成本。過去我們團隊使用工研院之APPJ系統進行了一系列之機台最佳化參數研究，在本研究也使用過去研究所得之最佳參數進行前人未使用過之多次沉積法(multiple deposition)研究，此方法將使用同一材料GZO，在固定總沉積時間的條件下(deposition time)調整掃描速率與次數進行多次沉積，優點是免更換材料且製程時間短。在經性質分析與量測後，發現在光電性質上多次沉積之薄膜確實有所改善，而此方法可應用至在製程中涉及軌跡之沉積法，如:噴霧熱解法。
同時我們利用有限元素法模擬四點探針量測各層電阻率不同之多層膜，解讀每層電阻率與四點探針量測值之關係，並發現多層薄膜在廣範圍之電阻率且總厚度低於0.5倍之探針距離時，皆可被視為等效並聯電阻電路。因此在多層導電膜量測中，可在每層沉積完畢後，藉此並聯模型量測並計算，最後推得每層之電阻率。本研究中也將使用有限元素軟體模擬四點探針，改變探針之間距與排列組態，探討以四點探針量測導電薄膜厚度的可能。
本研究包含了NTU APPJ之架設與部件設計組裝，我們改善了原工研院在設計上的些許缺失，如:外罩氣流、移動平台和電漿噴嘴外加組件。並進行小面積玻璃試片製程參數基準線之校正，藉著控制主氣流量、電壓值與工作週期，來得到一最佳光電性質之組合。且我們透過膜厚量測、霍爾量測、X光繞射儀和穿透度量測，針對改變主氣流量之樣品進行分析，探討造成片電阻值變化甚巨之原因。再來便是以此參數在大面積玻璃上進行鍍膜，我們得到平均片電阻值62.8 Ω/□，可見光平均穿透度87%以上，且片電阻值均勻度為14%之GZO薄膜。

關鍵字

多層薄膜 ； 有限元素法 ； 噴射式大氣電漿 ； GZO ； 四點探針

並列摘要

One of the advantages of the Atmospheric Pressure Plasma Jet, APPJ equipped with DC pulsed power source, is free of the vacuum chamber and is used to deposit Ga-doped ZnO(GZO)thin films in open air. By depositing small area thin films step by step, we can have a large area thin films. Recent research shows that the multi-layer deposition method, which stack materials with different characteristics together, can achieve better electrical and optical properties. However, the multilayer deposition often requires using different material as the buffer layer, which may increase the process time, tool complexity and materials cost. Here we studied the feasibility of enhancing the film properties and deposition rate by multiple depositions using only GZO, and adjusting the scanning speed and times. We find that both the deposition rate and the films properties are significantly improved. The method can be applied to other methods that involve scanning trajectory, such as spray pyrolysis.
In this thesis, we conduct three-dimensional finite element simulations on conductive multilayer films to study the relationship between the reading of the four-point probe and the conductivity of the individual layers. We find that a multilayer film may be modeled as a simple equivalent circuit with multiple resistances connected in parallel for a wide range of resistivity and thickness ratios as long as its total thickness is smaller than approximately half of the probe spacing. As a result we may determine the resistivity of each layer sequentially by applying the four-point probe, with the original correction factor π/ln(2), after deposition of each layer. Also, we use FEM and simulate the four-point probe by changing the probe spacing and configuration to discuss the possibility of measuring films thickness by four-point probe.
The thesis discusses the assembling and design of NTU APPJ. We improve some defects of ITRI APPJ such as, exhaust system, moving stage and jet additional prats. We established a fabrication baseline using small area substrates, which will be used as a basis for further optimization of the parameters. By controlling the main gas, voltage and duty cycle, it comes out the best films properties. Also, we measured the thickness, Hall measurement, XRD and transmittance to find out the reasons of the low sheet resistance of samples in low main gas flow rate. At last, we conduct the large area deposition with the baseline parameters, and obtain an average sheet resistance of 62.8 Ω/□, average transmittance in visible region over 87%, and the uniformity 14%, for GZO thin films.

並列關鍵字

multilayer thin films ； finite element method ； APPJ ； GZO ； four-point probe

參考文獻

[13] 林心恬, “國立臺灣大學工學院機械工程學研究所 碩士論文 大氣電漿沉積大面積氧化鋅薄膜與材料性質分布 Material Properties Uniformity of Large Area Ga-doped ZnO Thin Films Deposited by Atmospheric Pressure Plasma Jet 林心恬 Hsin-Tien Lin Advisor ： Kuo-Long Pan , Ph . D . 、 Jia-Yang Juang , Ph . D . January ,” 2015.

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