This page gives a brief introduction of my technical
work at (CADIFT). @ University of Toronto.

I work with a patent pending infrared imaging system which we call the ' PCR system' .
The acronym PCR stands for 'photoconductive radiometry'. The basic idea is given by
the figure below. 

A Silicon (semiconductor or relevant) sample is placed on the stage where it is moved
in a 2D area for scanning. The sample is illuminated by a modulated infrared laser that
heats the sample at the same frequency as of the modulation frequency. The heating of
the sample causes it to emit infrared radiation in the near infrared (NIR) range. This
infrared radiation is focused onto a InGaAs detector at room temperature. The output
is then sent to a pre-amplifier and then to a lockin amplifier which uses the reference
frequency as the same as modulation frequency of the laser. For data acquisition
MatLab software is used.

The images below give how the PCR system was used to make an image of a defect
on the backside of the Silicon wafer. An advantage of this technique is that it uses a
non-intrusive probing of the material to make an image of the defect.

Figure (1a & 1b) -  10 mm X 10 mm

Figures 1 & 2 consists of an area of 10 mm X 10 mm. The two hollow shapes show
the defect made on the Silicon wafer. The small square on the surface of the image
1a and 1b is resolved upto 100 micron X 100 micron in figures 3 and 4. In all images
a, is the amplitude and b, is the phase of the signal from the detector output. 

Figure (2a & 2b) ; A lateral view of the defect
10 mm X 10 mm

Figure (3a & 3b) -  100 microns X  100 microns
The small square on 1a & 1b  resolved  (100 X)

Figure (4a & 4b) - 100 microns X  100 microns