Off-axis illumination structure for improving photolithographic resolution and photolithographic system

Abstract

The invention discloses an off-axis illumination structure for improving photolithographic resolution and a photolithographic system. The off-axis illumination structure for improving photolithographic resolution orderly comprises a reflector, a condensing lens, a mask plate and a projection lens and also comprises a phase graph sheet between the reflector and the mask plate. The phase graph sheet comprises a pole edge sector having the equal adjacent included angles and central angles in the same circle. The pole edge sector is divided into multiple curved-side illumination pole blocks having spaces in arithmetic progression through the multiple concentric circles. An incident beam is reflected to the phase graph sheet through the reflector and then deviates from a principal optic axis so that a dip angle is produced. The zero-level and first-level diffraction light penetrating the graph of the mask plate passes through the projection lens and forms interference patterns on a photoresist of a wafer. The pole edge sector of the phase graph sheet is divided into the multiple curved-side illumination pole blocks so that the number of the illumination poles is increased, circular and pole edge illumination double characteristics are obtained, the resolution of the lithography is improved and the depth of focus is increased.

Description

technical field [0001] The invention relates to the technical field of lithography design, in particular to an off-axis illumination structure and a lithography system for enhancing lithography resolution. Background technique [0002] The basic principle of photolithography is: use the photoresist (or called photoresist) to have the characteristics of corrosion resistance due to photochemical reaction after being exposed to light, and engrave the pattern on the mask onto the processed surface. With the continuous development and progress of microelectronics technology, the requirements for photolithography systems are also getting higher and higher. Therefore, the lithography system is the mainstay of the sustainable development of the high-tech industry, and can ultimately affect the success or failure of the commercial competition of electronic products. [0003] With the reduction of lithographic feature size and the increasingly complex and diversified lithographic pat...

AI Technical Summary

Problems solved by technology

Common off-axis lighting methods include ring lighting, dipole lighting, quadrupole lighting, etc. The characterization parameters include lighting coherence factor, opening angle of lighting poles, number and shape of lighting poles, improvement of resolution by different off-axis lighting methods, Depth of focus and contrast are improved to different degrees, but commonly used off-axis lighting methods are only suitable for graphics with fixed pitch and regular lines

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