Photolithography, also known as optical lithography or UV lithography, is essential in microfabrication for aligning wafers through opaque layers. The process utilizes alignment mark regions that are transparent, allowing optical techniques such as lasers to align the wafer accurately. A hard mask is employed, but it must contain clear areas for effective alignment. In modern CMOS fabrication, a wafer may undergo the photolithographic cycle up to 50 times to achieve precise patterns.
PREREQUISITESThis discussion is beneficial for microfabrication engineers, photolithography specialists, and anyone involved in semiconductor manufacturing processes.
Edge5 said:In a lithography process I have a hard mask which is opaque. I have to make a wafer alignment, however I use optical techniques to align my wafer (lasers etc.) . How can I align my wafer through an opaque layer?
https://en.wikipedia.org/wiki/Photolithography said:Photolithography, also termed optical lithography or UV lithography, is a process used in microfabrication to pattern parts of a thin film or the bulk of a substrate. It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical "photoresist", or simply "resist," on the substrate. A series of chemical treatments then either engraves the exposure pattern into the material or enables deposition of a new material in the desired pattern upon the material underneath the photo resist. For example, in complex integrated circuits, a modern CMOS wafer will go through the photolithographic cycle up to 50 times.