一、引言随着MOS大规模集成电路和CCD器件的迅速发展,对器件表面质量要求越来越高。为监控工艺流程,提高器件质量,必须采用能较精确的测量界面态密度的方法。目前,国内外测量界面态密度主要采用如下几种方法,其中应用较广的为准静态法:(1)由Berglund所建立的低频C-V法。其测量频率小于100Hz。这种方法所能探测到的禁带区域较宽。但正如下面将要指出的,由于反型层的响应时间为1s量级,因此5Hz的测量频率仍然不够低,在测量时少子仍跟不上外加信号的变化。应用锁定技术,Ber- I. INTRODUCTION With the rapid development of MOS large scale integrated circuits and CCD devices, the surface quality requirements of the devices are getting higher and higher. To monitor the process and improve the quality of the device, we must adopt a method that can measure the interface state density more accurately. At present, the methods of measuring the density of states at home and abroad mainly adopt the following methods, of which the quasi-static method is widely used: (1) The low-frequency C-V method established by Berglund. The measurement frequency is less than 100Hz. This method can detect a wide band gap. However, as will be pointed out below, since the response time of the inversion layer is on the order of 1 s, the measurement frequency at 5 Hz is still not sufficiently low, and the young child can not keep up with the change of the applied signal during the measurement. Application lock technology, Ber-