本研究以電感耦合式高密度電漿蝕刻機台來研究蝕刻HfAlO(1:1)、矽晶圓蝕刻特性,實驗操作參數為固定氣體比例BCl3/Ar(40/2 sccm),改變電漿源功率、偏壓功率、腔體壓力和蝕刻時間,研究這些參數對蝕刻率、選擇比的影響,及其蝕刻機制探討。 綜合所有的實驗參數結果,發現最佳製程操作點落在ICP power 500 W、Pressure 10 mTorr、Bias power 10~15 W之間 ,若要進行過蝕刻製程,則需降低Bias power至10 W以下,而HfAlO(1:1) / Si蝕刻選擇比可達10以上。 從XPS分析得知,蝕刻過後HfAlO(1:1)試片表面有B與O的鍵結;而Si試片表面有B與Si的鍵結。由於B加速O的移除導致HfAlO (1:1)蝕刻速率上升;B與Si產生鍵結有鈍化的效果,導致蝕刻速率下降,於是HfAlO (1:1)/Si蝕刻選擇比,比在Cl2電漿中提升很多。
The etching properties of HfAlO and silicon wafer with pattern were investigated using inductively coupled high density plasma etcher. The effects of the experimental parameters, including ICP power, bias power, pressure and etch time, on the etch rate and selectivity were studied. The gas species and ratio were fixed at BCl3/Ar and 40/2 sccm. In order to study the etch mechanism and surface roughness, we observed the etched sample by electron spectroscopy for chemical analysis (XPS) and atomic force microscopy (AFM). It was found that the best operation setpoint was at icp power 500 W, pressure 10 mTorr, bias power 10 W~15 W. The over etch process must be operrated under the bias power 10 W. Surface roughness was increased with etch rate increased. From XPS analysis, we oberseved that the B-O bonds on etched HfAlO suface and B-Si bonds on etched Si surface. Because the reducing chemistry of boron removes oxygen to increase HfAlO etch rate, and passivation chemistry of boron bonds silicon to decrease Si etch rate. The resulting selectivity of HfAlO/Si was improved to above 10 in BCl3 plasma, much higher than in Cl2 plasma.