氢氟酸和PSG牺牲层腐蚀的TDC模型

对不同结构,即直沟道结构、冒泡结构和组合沟道结构的氢氟酸牺牲层腐蚀进行了研究.以往的牺牲层腐蚀模型和实验结果不能很好地吻合.以往的模型和实验结果的误差随着腐蚀时间的增加而增大.本文提出了一个修正模型,在修正模型中:HF的扩散系数是浓度和温度的函数;腐蚀速率常数是温度的函数;此外还考虑了腐蚀产物对腐蚀过程的影响.对于组合沟道结构,对腐蚀前端形状的描述采用了一个新的数学模型.实验结果和以往的模型以及修正模型进行了对比,结果表明修正模型能够和实验结果吻合得很好.

TDC Model for PSG Sacrificial Layer Etching with Hydrofluoric Acid

HF etching of sacrificial layers with different structures, namely channel, bubble, and joint-channel, is studied.The existing model cannot fit the experimental data well. The error of etching rate between the existing model and the ex-perimental data increases with etching time. A modified model considering the diffusion coefficient as a function of HF concentration and temperature is proposed. The etching rate coefficient as a function of temperature and the effect of re-action production are also considered in the modified model. For the joint-channel structure, a new mathematical model for the etching profile is also adopted. Experimental data obtained with channel, bubble, and joint-channel structures are com-pared with the modified modet and the previous model. The results show that the modified model matches the experiments well.