- #1
Edge5
- 22
- 0
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?
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.
Photolithography uses a process called "alignment marks" to align wafers through opaque layers. These marks are patterns etched onto the surface of the wafer, which are then used as reference points to align the wafer with the desired position.
The purpose of aligning wafers through opaque layers in photolithography is to ensure precise and accurate placement of the patterns onto the wafer. This is crucial for the success of the fabrication process, as any misalignment can result in defects and errors in the final product.
Photolithography achieves alignment through opaque layers by using a combination of alignment marks, specialized equipment such as alignment sensors and microscopes, and software algorithms to calculate the precise alignment of the wafer.
Some challenges in aligning wafers through opaque layers in photolithography include the complexity of the alignment process, the potential for human error, and the need for highly specialized and precise equipment. Additionally, the thickness and opacity of the layers can also affect the accuracy of the alignment.
Alignment is a critical step in the photolithography process as it directly affects the quality and accuracy of the final product. Any misalignment can result in defects and errors, which can be costly and time-consuming to fix. Therefore, precise alignment is essential for the success of the fabrication process.