The effect of Methanol/Ethanol added-HF/NH4F solution
| Autor: | Yi-Chi Chou, 周裕齊 |
|---|---|
| Rok vydání: | 2006 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 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 . |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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