添加甲醇/乙醇於氫氟酸/氟化銨溶液對其製作p-型(100)矽微米孔洞之影響

The effect of Methanol/Ethanol added-HF/NH4F solution

周裕齊(Yi-Chi Chou)

指導教授 ： 林景崎

國立中央大學/工學院/機械工程學系/碩士(2006年)

摘要

本研究以電化學方法在p-型（100）矽單晶上，蝕刻出微米級巨孔陣列結構。研究方式利用陽極極化法及定電位蝕刻，在氫氟酸及氟化銨溶液中，分別就不同添加劑改變溶液潤濕性、蝕刻時間、試片圖案孔洞尺寸，不同pH值等參數，探討其對蝕刻之影響。
研究結果顯示，p-型（100）矽單晶，隨著2M氫氟酸中添加乙醇之溶液中，其潤濕係數從0.15、0.42，0.59增加到0.82時，對p-Si(100)的蝕刻8小時，其孔洞寬度維持在7.8μm，但蝕孔深度由14.6μm增加到34.3μm，即蝕刻速率由1.825μm/h增加到4.29μm/h。若在2M氟化銨溶液中潤濕係數由0.15增加到0.60時，對p-Si(100)蝕刻8小時，其深度由9.2μm增加到21.6μm(蝕刻速率由1.15μm/h增加至2.7μm/h)。進一步延長氫氟酸溶液蝕刻時間至64小時可以有效增加蝕刻的深度至120μm。
預蝕刻時若圖案孔徑（L）從4、6、8到12μm進行蝕刻，不管是在氫氟酸或是氟化銨溶液中，都會有擴孔的現象，但是蝕刻孔洞的壁厚（P－L）均趨於定值，理論上與兩倍空間電荷層（2W）厚度相當近似。
使用潤濕係數 0.82之氫氟酸溶液，控制其蝕刻電流與蝕刻時間可以分別在P4試片和P12試片上得到深215μm、421μm的微米巨孔陣列。

關鍵字

潤濕係數 ； 氫氟酸 ； 氟化銨 ； 電化學蝕刻 ； p-型Si(100)單晶

並列摘要

Formation of macro-pore arrays on p-type silicon in fluoride-containing solution by electrochemical etching has been investigated in this work. Effect of wetting coefficient, etching time, Size of the pre-etched holes and pH value are discussed in fluoride-containing solution by dc-potentiodynamic polarization and potentiostatic etching.
The depth of etching pores on p-type(100) silicon increases from 14.6μm to 34.3μm(etching rate from 1.825μm/h to 4.29μm/h) with increasing the wetting coefficient from 0.15 to 0.82 in 2M HF solutions containing various concentration of methanol and ethanol for 8h. The width of etching pores keeps at constant(roughly at 7.8μm). The depth of etching pores increase from 9.2μm to 21.6μm with increasing the wetting coefficient from 0.15 to 0.59 in 2M NH4F solutions containing various concentration of methanol and ethanol for 8h. The total etching depth increases to 120μm with increasing the etching time up to 64h in hydrofluoric acid solution.
Regardless the etching extended in 2M ammonium fluoride or 2M hydrofluoric acid, the opening of the etched pore expanded a little for the patterns with increasing the pre-etched pit from P4, P6, P8 to P12. The wall width for all the etching structures keeps at constant that is theoretically determined at the twice of the SCR region.
Galvanostatic etching of p-Si(100) with pattern P4 for 32h in 2MHF containing 8MEtOH results in macro-pore arrays at a depth of 215μm depths. Galvanostatic etching with pattern P12 in 2MHF containing 8MEtOH for 16h leads to macro-pore arrays at a depth of 421μm .

並列關鍵字

p-type(100) silicon ； electrochemical etching ； Ammonium fluoride ； Hydrofluoric Acid ； Wetting coefficient

參考文獻

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