Alta^® 4700DP Mask Writer

As ICAPS applications grow, chipmakers need an increasing volume of photomasks for IC production at mature logic nodes. The Applied Alta^® 4700DP is a high-productivity laser mask writer. Laser writers offer lower cost of ownership and greater ease of operation compared to electron beam writers. Besides ICAPS applications, Alta also supports mask-writing for leading-edge chips. Since masks are not tied to a specific wafer size, they can be used for lithography on 200 and 300mm wafers, as well as smaller sizes including 150 and 100mm.

Key Features & Benefits

• 32 finely focused laser beams 

• Stable layer-to-layer overlay 

• Multi-pass writing for enhances lithography quality 

• Integrated software for feature size optimization

• High yield

• Automation with SECS/GEM* for enhanced system productivity

The Alta patterns photomasks with 32 finely focused laser beams that convert chip drawings into physical patterns on a six-inch square mask made of ultra-high-quality quartz. Each mask is a stencil that is used to print thousands or sometimes millions of individual chips using optical lithography systems. A large set of masks is needed to make each single device design. Alta is somewhat unique in the breath of the science and technology it includes: short wavelength lasers, complex optics, high-precision positioning systems, controlled exposure of the photoresist chemistry, accurate robotic material handlers, high-bandwidth data processing, and a vision system for alignment. 

The second-level alignment system provides the tight overlay needed to produce advanced phase shifting masks (PSM), which are used in greater numbers as optical wafer lithography is pushed to its limits. The non-exposing alignment light ensures accurate and stable layer-to-layer overlay. The alignment system can also be used on masks for leading edge EUV lithography, to write the “black border” around the critical chip area of the mask.

The Alta 4700DP uses multi-pass writing to enhance lithography quality. Integrated software can be used to optimize the control of feature sizes on the mask by compensating for errors due to the mask process.

Alta’s reliable printing engine combined with a minimal-contact mask-handling system results in very high yield. Also standard is SECS/GEM, allowing communications between the writer and the fab host, and enabling automation of the mask production process.