Two-dimensional profiling of dopants in semiconductor devices using preferential etching/TEM method

摘要

We present a sample preparation technique for using transmission elecron microscopy (TEM) to profile the dopant in a specified doped region of a very large scale integrated (VLSI) devies. This technique is based on preferential etching of thedoped region in silicon. Becuase the rate at which silicon is etched depends on the dopant concentration, the dopant distribution can be iinferred by observing he thickness fringe. Using two-beam approximation and information on the dependence of the etching rate on the conentration, we calculated the intensity of the transmitted electron beam and found that the results agreed well with the obsered fringes. In addition, by using a focused ion beam (FIB), we could also observe the dopant distribution in a specified source region of a VLSI device.