A statistical method to optimize the chemical etching process of Zinc Oxide thin films

<p>Zinc Oxide (ZnO) is an attractive material for micro and nanoscale devices. Its desirable semiconductor, piezoelectric, and optical properties <span>make</span> it useful in applications ranging from microphones to missile warning systems to biometric sensors. This work introduces a demonstration of blending statistics and chemical etching of thin films to identify the dominant factors, and interaction between factors, and <span>develop</span> statistically enhanced models on etch rate and selectivity of ZnO thin films. Over other mineral acids, ammonium chloride (NH₄Cl) solutions <span>have</span> commonly been used to <span>wet</span> etch microscale ZnO devices because of their controllable etch rate and near-linear behavior. <span>Etchant</span> concentration and temperature were found to <span>have</span> a significant effect on etch rate. Moreover, this is the first demonstration that has identified multifactor interactions between temperature and concentration and between temperature and agitation. A linear model <span>was</span> developed relating etch rate and its variance against these significant factors and multifactor interactions. An average selectivity of 73:1 <span>was </span>measured with none of the experimental factors having a significant effect on the <span>selectivity. </span>This statistical study captures the significant variance observed <span>by</span> other researchers. <span>Furthermore,</span> it enables statistically enhanced microfabrication processes for other materials.</p>