The Physics of EUV Photoresist and How It Drives Strategies for Improvement

EUV lithography requires high performance resists. The mechanism of light absorbance and acid generation is very different in EUV resists than in previous generations of chemically amplified resists. Resist absorbance must be driven up instead of down, which will require that new elements be incorporated into the resist. Some hafnium-containing resists have shown promise while maintaining a satisfactory etch resistance. These capabilities need to be built upon, and other metals need to be tested. The physics of EUV light and the small feature sizes involved also mean that the industry will be challenged to overcome noisiness, rather than grayness. This will require better understanding of LWR) and likely post-processing treatment of resists to improve the LWR and process windows.