The Evolution of Photolithography Technology, Process Standards, and Future Outlook

Photolithography has been one of the key enabling technologies for the development of integrated circuit industry. It has utilized the massive parallelism in projection replication of mask patterns. For the state of the art 193 nm immersion lithography, a full exposure field of 26 mm by 33 mm containing 4.2 × 10 ¹¹ pixels (each pixel occupies 45 nm × 45 nm area) can be scan-exposed in less than 0.2 second. For 1/3NA Soft X-Ray (SXR), 2.6 × 10 ¹² pixels (each pixel occupies 18 nm × 18 nm area) can be printed in one scan. Since the first invention of integrated circuits in 1958, the development of semiconductor industry has been through 62 years. In this long period, numerous novel technologies have been invented and fuel the advancement of the integrated circuit and device technology. In this paper, we will provide a summary of all key technologies in the field of photolithography and the process standards that the industry has developed and maintained. Also, we will provide an outlook of the photolithography technology in the future.