Advances in CPL, Collimated Plasma Source & Full Field Exposure for Sub-100nm Lithography
Brent Boerger, Scott
Mcleod, Richard Forber, I.C.E. Turcu, Cel
Key words: Collimated Laser Plasma Lithography (CPL), Collimated Laser Plasma Source(CPS), Chemically Amplified Resist (CAR), X-Ray, E-Beam, DUV.
In the world of micro- Lithography, several options exist for obtaining features below the 100nm level. Options include a variety of methods which range from additional process steps in etch, multilayer resist systems, or expensive throughput limited direct write E-beam systems. Each comes with a handful of trade offs in uniformity, repeatability and cost. Collimated (LASER) Plasma Lithography (CPL), on the other hand offers a full field exposure with minimal process intervention to obtain resolution below the 100nm barrier. CPL, uses a membrane 1x proximity mask and a collimated light source with energy peaking at 11 A°. By using a mask, an entire 22mm x 22mm field (30mm x 30mm with the next generation) can be exposed at once regardless of chip density, removing any throughput concerns as well as placement, stitching and typical E-beam machine flaw defects. Collimation, provides a predictable flux of energy to ensure minimal global divergence and energy level variation. Energy at 11 A°, allows for a high level of uniformity and penetration within the resist, without introducing resolution compromising scattering or standing wave effects.
This Paper will demonstrate the capabilities of CPL as well as the advantages over traditional lithography in obtaining features below 100nm. We will also depict process techniques which take full advantage of improvements in CAR, and experiments which suggest reduction possibilities through variables in mask fabrication.