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Infrared microscopy (Microscopy) is a method to look through a silicon wafer because silicon is transparent to infrared light.

Infrared microscopy
Technology Details
Other Names Microscopy,  %other names and abbreviations, separated by commas%
Technology Metrology
Equipment List of Microscopy equipment
Materials %Optional materials processed%



Olympus IR Microscope

Main article: Olympus IR Microscope

This microscope is set up with 5x, 10x, 20x and 50x objectives and has light sources from both the front and back. We have a holder for the bond aligner fixture to check bond alignment. It uses the same Steam software as the BX-51 microscope.

Method of operation

Using infrared (IR) light and an IR detector, it is possible to see through a silicon wafer to see if patterns line up on the front and back of a wafer, allows wafer bonds to be checked, and determine if alignment has shifted during the bond aligning process. While the silicon is transparent, oxide is more absorptive thereby appearing darker, and metal will block the IR. Different wavelengths allow greater depth of focus.


Here we describe what parameters are of importance in this technology (e.g. power, temperature...). May not be relevant to some technologies.


Main article: Magnification

Magnification is the ratio between the perceived size of the object and the actual size of the object. Often there are 2 magnifications that must be multiplied together to get the actual magnification: the objective lens magnification, and the eyepiece or camera magnification. i.e. If you have a 5x objective and a 10x eyepiece you get a 50x magnification. Because IR is not visible to the eye, an IR camera must be used and it may have its own lens.

Depth of focus

Depth of focus

The depth of focus depends on the lens and the wavelength of the light. Because the wavelength of the infrared light is longer, it is possible to get much higher depth of focus allowing the user to see both sides of the wafer on the lower magnifications.


For micro and nano fabrication, typically IR microscopy is used to see through a Si wafer. This is helpful when trying to inspect the alignment from the front to the back and when looking at bonding alignments both before bonding and after. With metal bonds you are able to generally see if the bonds are good or if they have "squished" out too much.


Optional description of materials that can be processed by technology. I think the best example of where this comes in handy would be with LPCVD describing the difference between HTO and LTO.

See also

Other related wiki pages


Further reading

  • Other stuff, e.g. technology workshop slides
  • External links (can be in another section below, if appropriate)