Aug 28 2007
Physical limitations of existing photolithography technology has led to the introduction of novel lithographic technologies during the last two decades. Experts agree that by the end of the current decade, imaging requirements for sub-50 nm node and beyond, will require the introduction of new lithographic technologies to support challenging technological needs, production throughput, and cost effectiveness.
New analysis from Frost & Sullivan, Global Advances in Semiconductor Micro-lithography Technologies, discusses the trends and adoption factors influencing the development of microlithography in the field of microelectronics and other sectors. For many decades now, optical lithography has remained an industrial workhorse due in large part to the many enhancement techniques that have prolonged its lifetime, despite repeated forecasts predicting its end. Nevertheless, challenges such as rising mask set costs and the resolution limit drive the search for next generation lithography (NGL).
"Until now, existing optical lithography lacked a clear successor capable of providing cost effectiveness and technological manufacturing capability at finer geometries," says Frost & Sullivan Industry Analyst Dr. Jayson Koh.
Despite substantial technical progress, several challenges still require attention to ensure the successful adoption of new lithography tools and equipment to enable high-volume production for advanced integrated circuit (IC) manufacturing processes.
The unavailability of affordable lithography processes beyond sub-50 nm, hinders the transition to next-generation technology nodes. Costs of mask sets continue to rise exponentially. For instance, a mask set costs approximately $800,000 at 90 nm and $1.2 million at 65 nm. Following this trend, a 45 nm mask set will likely cost more than $2 million.
In addition, existing immersion optical techniques represent over one third of the chip manufacturing costs and this number continues to increase with each process technology generation. These factors have led to the support of maskless lithography such as electron-beam.
"Maskless technology provides a viable solution to fulfill the needs for higher resolution while lowering mask cost," says Dr. Koh. "However, maskless lithography suffers from low throughput and as such, it is currently targeting only low volume production, which requires approximately 20 wafers per hour."
The evaluation of strengths associated with any next generation lithography technology is largely determined by the cost of development and tools as well as its physical limits. Cost is the main reason behind the reluctance in adopting extreme ultraviolet wavelength optical lithography.
Future advanced lithographic tools, especially for extreme ultraviolet lithography, will likely total over $20 million. As a result, these next generation technologies rely heavily on worldwide collaborations for the development of new lithographic tools and materials.
In order to convince companies to adopt NGL for high-volume manufacturing, NGL manufacturers must quickly develop prototype tools and demonstrate their capabilities beyond existing photolithography technology.
These technologies must also provide technological scalability and extensions to improve the production tool throughput and lower the cost of ownership. In addition, the introduction of NGL processes also entails increased investments in R&D for exposure tools as well as equipment, resist materials, masks, and metrology advancements.