使用三步化學蝕刻製成紋理微結構基板之光學及結構性質

Abstract

與乾式蝕刻相比，濕式蝕刻製程普遍用於製作出大面積的紋理結構基板，由於此製程相對簡單、同時成本也低，因此可以達成大量製造的目的。加上因為金字塔不同多平面，使得光線可在結構之間產生多次的反射，而增加光的收割性質。在本次實驗中，使用了在 (100)方向的P型矽基板，使用三步化學蝕刻去形成一種混合性結構，包含金字塔、蝕刻洞、樹枝狀結構跟奈米尺寸的倒置金字塔洞。為了達到這種混合性結構，使用非等向性濕式蝕刻作為第一步蝕刻去成長出多種不同尺寸的金字塔，隨後，在矽基板上蒸鍍一層銀薄膜去生長出團聚的銀顆粒，使用金屬化學輔助蝕刻去形成垂直排列的蝕刻洞在原先的金字塔結構上，金屬輔助蝕刻則為第二步蝕刻。最後，再一次使用非等向性濕式蝕刻當作第三步蝕刻，通過蝕刻液穿透先前的蝕刻洞(第二步蝕刻)去成長出隨機的倒置金字塔結構和樹枝狀結構。經過最佳參數的三步蝕刻處理的矽基板，可得到大尺寸、低反射率的紋理結構。

Compared to dry etching, wet etching is commonly used in the fabrication of large-area textured silicon substrates because it is an inexpensive and uncomplicated method. The pyramidal structure can increase light collection because it has different neighbor facets, which can generate multiple reflections. In this thesis, we implemented the fabrication of mixed structures, including pyramids, etching holes and inverted pyramidal cavities on (100) p-type silicon substrates, using three-step chemical etching. To achieve this, we utilized the anisotropic wet etching as the first-step etching to form pyramids of various sizes. Subsequently, a thin Ag film was deposited on a p-type (100) silicon substrate to form agglomerated Ag particles, and metal-assisted chemical etching (MacEtch) was performed to develop aligned etching holes on pyramids structure. Ultimately, we again used the anisotropic wet etching as the third-step etching for the etchant to penetrate holes to form randomly inverted pyramidal cavities and dendrite-like structures. Optimizing the three-step etching treatments, large-scaled textured structures with low reflectance could be obtained.