晶圓穿孔陣列之光輔助電化學蝕刻特性研究

Abstract

本研究自行開發低光源成本之光輔助電化學蝕刻(photo-assisted electrochemical etching, PAECE)設備，藉由改變光照強度及界面活性劑等實驗條件，並改善電化學蝕刻穿孔製程，得到較高之蝕刻速率與低孔壁粗糙度的穿洞陣列。未來可應用於積體化微探針陣列之製作，或利用晶圓內垂直導體之晶圓內連線而實現晶圓級堆疊封裝之目的。此技術開發有設備與製程成本低、可批次生產、良率高，且與半導體製程相容性高等特點。 由實驗結果已驗證，在利用光輔助電化學蝕刻技術製作高深寬比微穿孔陣列方面，可得到500 um的孔洞深度、穿孔時間最快約為16.7 hr的微穿孔陣列，且孔壁形貌有極佳之表面粗糙度。電化學蝕刻之孔徑最小約為21 um，蝕刻孔洞之深寬比最大約為17.7。相關之實驗條件如下：光源照度為32000 lux至18000 lux，選用陽離子型界面活性劑1 wt.% DC-1、陰離子型界面活性劑1 wt.% MA、強氧化劑2.5 wt.% H2O2及有機界面活性劑1 wt.% Alcohol。經此技術蝕刻而得之黑色微孔洞陣列，在僅添加陰離子型界面活性劑1 wt.% MA且蝕刻2 hr後，其反射率最低可降至約0.43%，而使用界面活性劑蝕刻穿孔之結構亦能有約0.4-0.5%之反射率。 本研究證明了利用此技術已能局部取代乾式蝕刻之應用領域，並對於積體化微探針陣列之製作，或晶圓內連線之晶圓級堆疊封裝有極大的助益。且經此技術所製成之黑色微孔洞陣列結構，將有機會應用於太陽能電池之抗反射層，大幅提升太陽能電池之轉換效率。

This research developed photo-assisted electrochemical etching (PAECE) system with low-cost light source for fabricating high-density silicon wafer through-holes array. This process is described as followed: high-density through-holes array in silicon is etched by photo-assisted electrochemical etching under various parameters, such as illumination, surfactants, and concentrations, then to improve the through-hole etching fabrication to obtain through-holes array with high etching rate and smooth etching sidewall. The developed technology will be promising for applications of integrated probe array and wafer-level package in the further. Its advantages are described as followed: low-cost system and fabrication, manufacture, high yield, and suitable for semiconductor process. Using PAECE technology to fabricate wafer through-holes array, we can get the structures with high etching rate and smooth etching sidewall through silicon substrate with thickness of 500 um when the etching time reached 16.7 hours. The smallest width of through-hole by PAECE is 21 um, and the highest aspect ratio is 17.7. The related experimental parameters are described as followed: illumination is 18000-32000 lux, chose surfactants are 1 wt.% DC-1, 1 wt.% MA, 2.5 wt.% H2O2 and 1 wt.% Alcohol. The black micro holes array fabricated by PAECE 2 hr with 1 wt.% MA has ultra-low reflectivity 0.43%, and reflectivity of through-holes array also has equal values about 0.4-05%. Results of this research proved that PAECE technology had been able to partially replace the dry etching technology. It has advantages for applications of integrated probe array and interconnection of wafer-level package. After PAECE fabrication, the black micro holes array will be applied to antireflective structure of solar cell to improve the efficiency obviously.