界面活性劑添加於氫氟酸緩衝溶液在蝕刻和清洗上的效應

Abstract

氫氟酸緩衝溶液在半導體製程是很好的蝕刻氧化層的溶 液，但其潤 濕性並不好，尤其在小尺寸更為不理想，無 法有效的蝕刻與清潔。 本文主要是探討我們在氫氟酸緩 衝溶液中加入微量的介面活性劑在 蝕刻與清潔的效應。 因為潤濕性可藉由降低表面張力而得到改善，故我們添 加介面活性 劑到氫氟酸緩衝溶液，其可降低表面張力 （<25 dyne / cm2）， 使其潤濕性更好。而添加介面活性 劑的氫氟酸緩衝溶液並不會改變原 溶液的蝕刻速度與 蝕刻外形，試片在經過有添加介面活性劑的氫 氟酸緩衝 溶液處理後，其表面氟元素鍵結的量明顯降低，讓表面 恐水性更完全，恐水性的表面可抑制自然氧化層的沈積 與金屬的污 染，而讓表面的粗糙度降低，粗糙度的增加 與表面的污染亦會影響 電性的特性如QBD和C-V，添加 介面活性劑的氫氟酸緩衝溶液確實 可讓處理過後的表 面更平整且有良好的電性特性。 BHF is a well-known, Excellent wet-etching regent for silicon dioxides. It cannot perform complete cleaning and etching, however,due to its poor wettability on the wafer surface. In this work, we stigate the effect of surfactants additives in BHF on etching and cleaning process of ULSI. The wettability can be improved by the reduction of surfacetension with the addition of surfactants in BHF. Addition of binarysurfactant can reduce surface tension lower than 25 dyne/cm2. The addition of surfactant does not change neither etching rate nor etchingprofiles. The wafer is treated by surfactant BHF is effective reducedthe fluorine coverage that passivated to reoxidation and hydrophobicsurface performs fully. The hydrophobic surface are well to besusceptible to natice oxide form,particle deposition and metallic contamination. Therefore, it can effective reduce the roughness.Thereduction of native oxide growth can decrease the contact resistance.An increase of surface micro-roughness has been confirmed toseverely degrade the electrical performance such as charge tobreakdown Qbd and C- V characteristics. The addition of surfactantsin BHF can smooth the surface and exhibit a excellent behavior in Qbd and C-V characteristics.