Photolithography
Photolithography process control is one of the most critical steps of the manufacturing process. Collimated light Exposure systems have unique imaging capabilities that allow precise feature replication over the entire exposure area with resulting high yield. Virtual elimination of light divergence and declination angle with collimated light produces uniform features, displacement or undercut. Separation of the undesirable infrared light energy from the usable UV energy allows the exposure process to occur with minimal thermal gradient at the exposure plane, eliminating the need for auxiliary cooling systems. Image transfer can be obtained by three different but related techniques as follows:
Image transfer is made by placing the mask directly on the photoresist surface, holding in contact by vacuum clamping and exposing with Collimated UV light. The contact aligner is a relatively low cost method of reproducing fine line features.
In projection printing, a lens is placed between the mask and the photoresit coated substrate to transfer the image. Collimated UV light passes through the mask and is imaged by the projection lens on the photoresist. Ideal for photolithographic steps down to 3 microns resolution.
Large area scanning for large area substrates. Provides excellent exposure uniformity over the entire exposure area.
Combines the high yield benefits of projection lithography with the ability to provide local alignment accuracy.
This process is similar to contact printing except the mask and the substrate are separated by a small variable distance. Collimated UV light passes through a mask which is imaged onto the substrate, producing a single sided exposure.
Excimer Laser ablation is a non-contact, non-thermal method for removing material using a mask. The result is effective, predictable material removal, with very little thermal loading of adjacent areas. Laser ablation systems will produce process geometries down to 1 micron.
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