September 19, 2011 — Applied Materials (Nasdaq:AMAT) unveiled its Centura Tetra EUV advanced reticle etch system at the SPIE BACUS conference (Monterey, CA). The system addresses changing requirements from transmission photomasks used in optical lithography to reflection photomasks needed for extreme ultraviolet lithography (EUVL).
The much shorter EUV wavelength would be absorbed in a transmission photomask. The EUV light source wavelength is approximately 15x shorter than that of deep ultraviolet lithography. The figure shows a comparison between a conventional photomask and an EUV photomask.
|Figure. Photomask sees paradigm change with EUVL. Short EUV wavelength would be absorbed in a transmission mask. SOURCE: Applied Materials.|
Applied Materials’ new etch system addresses: 1) being able to handle tantalum (Ta) materials used in EUV masks, 2) using optical emission spectroscopy to determine when to stop the etch process, and 3) minimizing damage to the ruthenium (Ru) surface, which is the stopping layer underneath the absorber.
According to Amitabh Sabharwal, GM, mask etch products, at Applied Materials, end users are experimenting with Ta-based materials and the complex structure required for an EUV mask. Listen to Sabharwal’s interview below. The Bragg mirror alone has 40 alternating layers of molybdenum (Mo) and silicon (Si). When using Ta-based materials,