Negative Tone Lift Off Resist Processing
S3 Photoresist tools are capable of providing a fully automated series of processes which enable negative resist operations to function properly
Operational control is critical here as a lift off resist requires the precise control of process conditions. As with all lift off technology, it is necessary to provide a means whereby the polymer film that acts as the mask for the metal deposition “overhangs” the resist trench. In this way during lift off processing, the solvent can attack the polymer and thereby allow the metal film atop the polymer/resist to “Lift Off” leaving the deposited metal in the trench. The degree of “undercut” is determined by the precise control of post expose bake (PEB) conditions as well as exposure energy. Further, uniformity of the undercut is a function of develop uniformity in a puddle type develop process.
To effectively control the entire process therefore, it is important to have excellent film thickness uniformity, coupled with precise and repeatable control of hot plate baking conditions and uniform develop.
For more information on negative lift off resist processing using S-Cubed Photoresist processing tools,