VHDL IMPLEMENTATION OF THE NOISE REDUCTION SYSTEM

Abstract

The spectroscopic photon emission microscope system (SPEMS) consists of a conventional emission microscope suitable for imaging in panchromatic mode and a retractable spectroscopic system of high spectral resolution having continuous wavelength analysis capability. It overcomes some deficiencies in a conventional photon emission microscope (PEM). SPEMS is a high sensitivity system with a continuous wavelength spectroscopic capability. It helps in failure analysis of the semiconductor devices using a non-destructive approach. However, the performance of SPEMS depends on the accuracy with which the defect spot in the device is detected.

The SPEMS uses a technique called defect finger printing, where the spectral characteristics obtained from an unknown failure is compared with a set of standard spectra from known mechanisms to ascertain the failure mechanism of the device under test.

This project aims to enhance the performance of SPEMS by increasing the clarity of the captured image and the quality of the emission spectra by suppressing the noise present in the system. The project uses a digital technique wherein samples are taken at regular intervals and converted to digital data with the help of an analog-to-digital converter. An averaging technique is used to reduce the noise present in the samples. The digital data output from the system designed in this project can be converted into analog signals and the spectral characteristics can be obtained. Since the noise is suppressed, the spectral characteristics obtained with the help of these signals are very much closer to the standard spectral characteristics. This will help to enhance the performance of the system considerably.

The digital averaging technique used in this project has proven to be an efficient technique to reduce the noise. This is achieved with a greater resolution and greater speed, thus reducing the time taken to get samples from each point pixel. The speed and accuracy of the system may be limited only by the cost and efficient programmable devices only.