Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/10264
標題: 加強型電容耦合式高密度電漿在液晶薄膜電晶體氮化矽蝕刻製程應用研究
Investigation of TFT-LCD SiNx Etching Using Enhanced Capacitive-Coupled High-Density Plasma
作者: 林子根
Lin, Tzu-Ken
關鍵字: Dry etch;乾蝕刻;SiNx;Experiment design;Hhigh density plasma;氮化矽;實驗設計;高密度電漿
出版社: 材料科學與工程學系所
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摘要: 
本研究以加強型電容耦合式高密度電漿蝕刻機台來研究蝕刻氮化矽(SiNx)結構,實驗操作參數為射頻電漿源功率、射頻偏壓源功率、SF6、O2、He氣體流量和腔體壓力。研究這些參數對蝕刻率與均勻性的影響與傾斜角的變化。利用田口法進行實驗設計,吾人獲得一組解,其腔體壓力:175 mTorr、射頻電漿源功率:9 kW、射頻偏壓源功率:0.5 W、SF6流量:1,500 sccm得到的蝕刻率7,321 Å/min與均勻性18.5 %,蝕刻率及均勻性雖符合所訂定之標準,但傾斜角有2階段傾斜角,容易造成氮化矽上方之氧化銦錫(ITO)覆蓋不佳,導致斷線,造成阻抗過高,進而影響液晶驅動。
經由實驗結果做分析表格,吾人可以有效的決定對蝕刻特性的重要因子。製程參數的腔力壓力變化對氮化矽蝕刻率的改變趨勢是相同的,腔體壓力由125 mTorr上升至175 mTorr,腔體內氣體粒子較多,產生離子化碰撞的機會較多,所以電漿密度上升,蝕刻率也跟著上升。射頻電漿源功率由5 kW提高到9 kW將有助腔體內氣體分子的解離,提高腔體內活性基的數目,增加化學反應,可得到較高的蝕刻速率。射頻偏壓源功率由1 kW提高到2 kW物理轟擊蝕刻較劇烈,使得能夠更有效的打斷Si-N鍵結增加蝕刻率。總氣體流量由5,250 sccm上升至7,000 sccm,可以被解離出來的自由基濃度也將會增加,蝕刻率明顯提高,均勻性也有下降的趨勢。由實驗結果分析得知若壓力愈低則2階段傾斜角會更加嚴重,因此將腔壓力提高到200 mTorr,其它參數與預測因子一致,並進行一週的製程穩定性監測,蝕刻率的變動範圍在7,790~8,032 Å/min,均勻性則在17.3~18.2 %之間,均符合規格且穩定性良好,傾斜角未見2階段傾斜角,為一最佳解。

This thesis described the etching characteristics of silicon nitride (SiNx) passivation films in the thin-film transistor structure using an enhanced capacitive-coupled high-density plasma etcher. The main parameters used in these experiments were RF source power, RF bias power, chamber pressure, SF6, O2 and He gas flow rates. The Taguchi Method was employed in terms of the etching rate, uniformity and taper angle. Typically we can obtain the etching rate of 7,300 Å/min with a uniformity of 18.5 % when the chamber pressure, RF source power, RF bias power and SF6 flow rate are 175 mTorr, 9 kW, 0.5 kW and 1,500 sccm, respectively. Although the etching rate and uniformity could achieve the target, the etched nitride film showed a two-step taper structure which would result in the poor step coverage of the following indium oxide tin (ITO) deposition and lead to high contact resistance.
In order to solve the above problem, a systematic experimental data analysis was performed to determine the characteristic factors more efficiently. It was found that the SiNx etching rate increased as the chamber pressure increased from 125 to 175 mTorr. This could be due to the more the gas molecules in the chamber, the more collision opportunity to be ionized. The increase of RF source power was expected to increase the gas dissolution rate, which would achieve the higher etching rate because of the more radicals in the chamber. Physics bombardment etching is also enhanced when the bias power increases from 1 to 2 kW, which enables the more effective etching rate. Moreover, higher total gas flow rates (SF6, O2, He) from 5,250 to 7,000 sccm were found to achieve better performance, i.e. the high etching rate and nice uniformity. the lower the pressure has the worse 2-step angle.
Based on these experimental results, the chamber pressure was confirmed to be the key factor in determining the formation of the two-step taper structure. The lower chamber pressure was used (e.g. 125 mTorr), the more evident two-step taper was observed. An optimum pressure of 200 mTorr is found while the other parameters can be kept the same. During a weekly monitoring system, the performance data was found to keep stable and within the specification where the etching rate changing level is about 7,790~8,032 Å/min, the uniformity 17.3~18.2%, the taper without two-step angle.
URI: http://hdl.handle.net/11455/10264
其他識別: U0005-2108200612275300
Appears in Collections:材料科學與工程學系

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