石英晶片镀膜频率监控技术研究

Film Thickness Monitoring with Quartz Wafer

石英晶片镀膜是石英晶体谐振器生产中的重要工序之一,通过控制镀膜厚度使石英晶片谐振频率达到目标值。传统的镀膜采用时间控制方法,膜层厚度取决于镀源材料蒸发速率和镀膜时间,用该方法石英晶片谐振频率的控制精度较低。为提高石英晶片的镀膜精度,提出了基于晶体微量天平原理的晶片镀膜过程频率监控方案。重点探讨了镀膜过程中石英晶片和标晶谐振频率变化与镀膜厚度之间的关系,并通过实验给出石英晶片和标晶表面膜层沉积质量的比率关系,设计了监控晶片谐振频率的振荡器电路。实验证明,将研究的石英晶片镀膜监控技术应用于生产实际,可以显著提高镀膜后的石英晶片谐振频率的控制精度,具有较高的实际应用价值。

A novel technique was developed to control the thickness of the films grown on quartz wafer, with high accuracy, by measuring the frequency of the quartz oscilator. Discussions focus on operation principle of the quartz microbalance, design of the oscillator circuits and the relationship between the variations in the intrinsic frequency of the quartz oscillator and the film thickness. Morcover, the dependence of the film thickness on the variations in the frequency of the film covered quartz oscillator was experimentally calibrated. The advantages of the newly-developed technique over the conventional ones were discussed. Experimental results show that high accuracy of the oscillation frequency can be wellcontrolled and so was the film thickness.