在氟化銨中以光電化學法蝕刻n-Si(100)單晶表面製作微米溝槽

Preparation of Macro Trenches on Si(100) by Photoelectrochemical Etching in Ammonium Fluoride Solution

本研究以光電化學法在在n-型（100）矽單晶上，採用不具毒性的氟化銨蝕刻液，蝕刻出微米級溝槽結構。陽極極化法及定電位蝕刻可以用來探討氟化銨溶液中，外加電壓與試片圖案間距對蝕刻速率及蝕刻形貌的影響。研究結果顯示：在預蝕刻圖形間距為110μm，若改變蝕刻電位由0.1 V增加到0.8 V，則蝕刻所得之結構其孔壁厚度由32μm增加至90μm。在外加電位為0.8 V時，若改變預蝕刻圖形間距在60 ~ 170μm範圍，則間距60、80及110μm試片可以製作出孔壁筆直之溝槽結構，但間距140及170μm試片，蝕刻孔洞發生擴孔，此現象之差異可由電場與空間電荷區分佈之差異來解釋。

Fabrication of macro-trenches on n-type silicon in the ammonium fluoride solution by photo-electrochemical etching has been investigated in this work. Effect of applied voltage and the pitch of pores were discussed in ammonium fluoride solution by dc-potentiodynamic polarization and potentiostatic etching. For the pattern with a pitch of 110 μm, the wall width of the etching structures increases from 32 μm to 90 μm when the etching voltage increases from 0.1 V to 0.8 V. For the etching conducted at 0.8 V, we obtained trenches in vertical walls as the pattern with a pitch less than 110 μm (e.g., 60, 80 and 110 μm) but in curved walls for the pattern with a pitch higher than 110 μm (e.g., 140 and 170 μm). This difference in trench morphology is delineated by different distribution for the strength of electric field and the space charge regions.