TEM-based phase retrieval of p-n junction wafers using the transport of intensity equation

Two cross-sectional specimens of pattered silicon wafers implanted with either arsenic or phosphor are investigated in the transmission electron microscope ( TEM). Phase retrieval using the transport of intensity equation ( TIE) is suggested as a means for nano-scale sensing of dopants in such p- n junction wafers. Improvements in TIE phase retrieval are proposed and implemented using a through-focus series of large numbers of images. Polynomial fitting to robustly estimate the required intensity defocus-derivative is shown to enhance data quality, resulting in phase maps that portray detail over a broad range of spatial-frequencies in a realistic manner.