Scanning Probe Microscopy Technique for Carrier Concentration Measurement in Silicon
|關鍵字:||掃描探針顯微術;載子濃度;表面電位;表面濃度;Scanning probe microscopy;carrier concentration;surface potential;surface concentration|
|摘要:||掃描探針顯微術是近年來發展迅速的一種表面分析技術，具有非破壞性、二維量測、高空間解析度等諸多優點。KFM (Kelvin Probe Force Microscopy)是其中一種，能夠量測試片表面電位。藉由量測矽半導體的表面電位，KFM可望應用於載子濃度的二維量測。
Scanning probe microscopy (SPM) is one of the surface analysis techniques which are developed rapidly in recent years. It has advantages of non-destructive, 2-D measurement, and high spatial resolution. Kelvin probe force microscopy (KFM) is one application of the SPM technique. The KFM measures surface potential of sample. By means of measuring the surface potential of silicon semiconductor, KFM is capable of 2-D measurement of carrier distribution. Before the measurement of surface potential, the feedback control circuit was modified to improve the signal response. Then, this thesis studied sample preparation method. It was observed that the oxidized or HF-dipped sample surface was covered by Si-O or Si-F, respectively, and resulted in degraded contrast of surface potential image. These bonds were removed effectively and image contrasts were promoted after the samples were ultrasonic oscillated in acetone, dipped in HF, and rinsed by D.I. water. After the surface potential differences were measured by KFM, several methods including spreading resistance profiling (SRP) method, capacitance-voltage (C-V) method, and secondary ion mass spectroscopy (SIMS) were employed to determine the surface carrier/dopant concentration in order to setup the correlation between surface potential difference and surface carrier/dopant concentration. This thesis also beforehand studied on the preparation of cross-sectional sample. Although the results are not perfect, it is looked forward that KFM can be applied on 2-D carrier profiling of nano-devices.
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