Atsushi Kominato

The ultimate chrome absorber in photomask making

193nm-immersion lithography is the most promising technology for 32nm-node device fabrication. A new Cr absorber (TFC) for 193-nm attenuated phase-shift blanks was developed to meet the photomask requirements without any additional process step, such as hardmask etching. TFC was introduced with a design concept of the vertical profile for shorter etching time, the over etching time reduction. As a result, the dry-etching time was dramatically improved by more than 20% shorter than the conventional Cr absorber (TF11) without any process changes. We confirmed that 150nm-resist thickness was possible by TFC. The 32nm technology-node requirement is fully supported by TFC with thinner CAR, such as resolution and CD performance.

Development and Characterization of a New Low Stress Molybdenum Silicide Film for 45 nm Attenuated Phase Shift Mask Manufacturing

As optical lithography is extended for use in manufacturing 45 nm devices, it becomes increasingly important to maximize the lithography process window and enable the largest depth of focus possible at the wafer stepper. Consequently it is very important that the reticles used in the wafer stepper be as flat as possible. The ITRS roadmap requirement for mask flatness for 45 nm node is 250 nm. To achieve this very tight reticle flatness requirement, the stress of each film present on the mask substrate must be minimized. Another key reticle specification influenced by film stress on the mask blank is image placement. In this paper, we will describe the development and detailed characterization of a new low stress Molybdenum Silicide (MoSi) film for use in manufacturing 45 nm node critical level attenuated phase shift masks to be used in 193 nm immersion lithography. Data assessing and comparing the cleaning durability, mask flatness, image placement, Critical Dimension (CD) performance, dry etch properties, phase performance, and defect performance of the new low stress MoSi film versus the previous industry standard A61A higher stress MoSi attenuator film will be described. The results of our studies indicate that the new low stress MoSi film is suitable for 45 nm mask manufacturing and can be introduced with minimal changes to the mask manufacturing process.