Imec has demonstrated a breakthrough in the optimization of EUV lithography. By injecting oxygen during the post-exposure bake of metal oxide resists (MORs), a photospeed increase of up to twenty percent is achieved, reducing processing costs.
Findings from imec indicate that controlling the gas composition, and especially the oxygen level, during critical steps in the EUV lithography process has a significant impact on the performance of metal oxide resists. These resists are crucial for the production of chips with extremely small structures.
The research was presented at an international conference and is relevant for manufacturers striving for higher wafer throughput and lower costs. Imec’s focus is on improving the efficiency of lithography processes for advanced semiconductors.
Metal oxide resists in EUV lithography
In recent years, metal oxide resists have emerged as a major alternative to chemically amplified resists. They offer advantages such as better resolution and reduced line-edge roughness. This makes them suitable for applications where extremely small and precise structures are required, especially when using High NA EUV lithography.
Improved pattern transfer and the ability to work with thin resist films make MORs highly promising for the future of chip production. Their performance is now being further optimized through controlled oxygen injection during the post-exposure bake process.
Results with the BEFORCE instrument
Imec developed the BEFORCE instrument to study the influence of the ambient environment on MOR resists. Using this device, it was determined that an oxygen concentration of fifty percent during the post-exposure bake results in up to twenty percent faster photospeed compared to the standard twenty-one percent.
This approach lowers the required EUV dose and increases the throughput of the EUV scanner. Manufacturers can now apply these insights to adapt their equipment for more stable and efficient production processes.
Future research
For optimal results, further research is needed into the chemical mechanism underlying the improved performance. Imec is working on experiments where chemical changes during the baking process are analyzed in real-time, including through infrared spectrometry.
The BEFORCE tool is being expanded with new measurement capabilities and can test both MOR and CAR resists. Imec partners will have access to this technology for their own resist evaluation.