應用品質手法改善IGZO-TFT之介電層成膜及蝕刻製程參數

Apply quality control to improve IGZO-TFT filming and etching process parameters at the passivation layer

官秀華(Hsiu-Hua Kuan)

指導教授 ： 陳育欣

中原大學/電機資訊學院/工業與系統工程研究所/碩士(2016年)

https://doi.org/10.6840/cycu201600526

摘要

隨著面板趨勢走向對於LCD面板需求高解析度及低功率消耗，目前市場上消費者已不設限在追求高解析度，反而回歸到價格比較、3D支援、手機輕薄度、全視角、可撓曲及低功耗等；對於面板產業之未來願景，為如何提升產品效能將會是重要的課題。目前在面板業最常用之半導體材料有a-Si(非晶矽)、LTPS(低溫多晶矽)、IGZO等，其中IGZO此材料電子遷移率雖不及LTPS，但因人眼辨識解析度有限故此材料也已足以滿足消費者對於解析度之需求而製程成本低，使用光罩數也少且IGZO而製程溫度也不像LTPS所需求之溫度較高，故就以目前開發階段也有不少業界利用此材料來開發可撓性顯示器之液晶面板。
在IGZO-TFT製程中的瓶頸階段，則是在製作薄膜電晶體和對應之保護層部分，當IGZO的上、下保護層在成膜時，若是成膜SiOx的SiH4流量太高，容易會有氫 Doping在絕緣層內和IGZO半導體的連結而影響整體電性的問題，但SiOx於膜成時SiH4之流量調小時，即成膜速率會大幅下降。
以個案公司為例，運用品質手法QC-Story之核心PDCA做為實驗步驟之進行，因實驗週期較短所以選擇利用田口實驗設計方法之優勢在短時間內做出有效之製程參數分析，將影響成膜/蝕刻製程均一性之顯著因子，寫入一組參數優化膜厚之均一性進而提升電性良率。
分析實驗結果指出，在成膜製程運用低溫可改善成膜均一性由21%降至10%，而使用了低功率對成膜速率從2.71A/sec增加至6.63A/sec；而蝕刻製程在數據分析後可得出運用高功率和低O2流量成功將蝕刻速率11.54A/sec增加至18.28A/sec，低壓力也將蝕刻均一性由33%降至13%；利用上述品質手法之改善成功讓此技術良率提升且導入線上作業。

關鍵字

介電層,田口方法,TFT-LCD,

並列摘要

With the trend of developing higher resolution and lower power consumption of LCD panels, newer and better semiconductor materials are researched and used. For the future of the LCD panel industry, how to improve the product efficacy is an important issue. In the industry, a-Si, LTPS and IGZO are the most used semiconductor materials. The electron mobility of IGZO is not as good as LTPS; however, due to the limit of human vision, IGZO can generally satisfy consumers’ demands. Furthermore, the manufacturing costs, required temperature and photo masks of IGZO are less or lower than LTPS. In the developing stage, many industries utilize IGZO to develop the bendable LCD monitors.
In the manufacturing process of IGZO, producing the thin film transistor and the passivation layers are the difficult steps. When thin films are forming at the upper and lower passivation layers, if the flow of SiH4 is too fast, H doping form easily at the insulation layers, and connectivity is poor. On the other hand, if the flow of SiH4 is slow, the filming rate will decrease.
In this case study, we utilized the QC method-PDCA as the experimental procedure. We applied the Taguchi Method due to the shorter experimental cycle time. Two-stage Taguchi Method is utilized to investigate the final sign parameters. The first stage consists of finding the significant factors, which affect filming and etching uniformity through analyzing with L8(26), half-method and engineering experiment, the results showed the significant factors of filming uniformity were power, pressure, temperature; the significant factors of etching uniformity were O2, power, pressure. The second stage consists of determining parameter values of the filming and etching significant factors for improving uniformity and electrical yield.
The experimental results indicated that uniformity in the filming and etching process could improve from 21% to 10% and from 33% to 13% respectively by lowering temperature. The overall electrical yield increases from 67% to 87%. The previously mentioned QC methods improve the technology yield and set the stage for mass production.

並列關鍵字

Passivation, Taguchi Method, TFT-LCD

參考文獻

6. 王俊程. (2014). 利用田口方法提升伺服器測試之效率. 台北科技大學. Available from Airiti AiritiLibrary database. (2014年)

8. 吳振東. (2014). 田口方法應用於導光板黃化改善之研究. 中原大學. Available from Airiti AiritiLibrary database. (2014年)

12. 杜鳳棋. (2014). Improvement of In-car Air Quality Under Driving Conditions Based on Saving Energy. [在行車狀態下以節能方式改善車內的空氣品質]. 機械技師學刊, 7(4), 15-20. doi: 10.6208/jpme-2014-12-03

13. 林昇輝. (2006). 以不同方式成長氧化矽膜及其對氮化鎵發光二極體漏電流之影響研究. 中興大學. Available from Airiti AiritiLibrary database. (2006年)

14. 邱久容. (2009). 低電壓氧化物半導體a-IGZO與高分子介電層薄膜電晶體. 中興大學. Available from Airiti AiritiLibrary database. (2009年)