Precise fabrication of large-area microstructures by digital oblique scanning lithography strategy and stage self-calibration technique

Abstract

We proposed an efficient and low-cost method for precise fabrication of large-area microstructures. A programmable digital lithography system based on digital micromirror device (DMD) oblique scanning strategy was developed, which can effectively reduce pixel quantization errors and complete a sub-pixel exposure accuracy. To further reduce the cost and enhance the flexibility of the fabrication system, a two-dimensional (2D) stage self-calibration technique is studied, which can replace the laser interferometer measurement (LIM) system and ensure the calibration accuracy well. The presented method is promising for developing large-area microstructure applications such as flat panel display (FPD), organic light-emitting diodes (OLED).

An efficient and low-cost compensation method for exposure uniformity based on digital oblique scanning lithography

“…On the other hand, the influence of scanning stitching error and illumination nonuniformity is effectively reduced. In addition, in our previous study, 18) DMD-based oblique scanning lithography method and stage self-calibration technology were combined, which can effectively improve the lithography resolution and overlay accuracy of the lithography system.…”

“…The specific working principle of the DMD oblique scanning lithography system has been introduced in detail in our previous research. 18) Here, a UV-LED is used as the exposure light source. UV-LED exposure light source has the following advantages: (1) Large power can meet the requirements of the photolithography process on the light energy density; (2) It is similar to a point light source due to its small shape and size, which is conducive to the uniform light design of the optical system;…”

Stitching error compensation for large-area microstructures based on digital oblique scanning exposure mode

“…[14][15][16][17] At present, DMD-based digital lithography mainly includes the dynamic projection lithography method [18][19][20][21][22] and dynamic scanning lithography method. [23][24][25][26] In the former case, due to the limited size of DMD surface size, the processing of large-area high-resolution microstructures cannot be realized by a single projection. The latter dynamic scanning lithography can realize the high-efficiency processing of large-area microstructures by combining the dynamic updating of DMD pixels with the control of the motion stage.…”

“…However, due to the dynamic modulation characteristics of the DMD itself, the problem of discrepancy between the designed digital mask and the actual machining size will occur when dealing with non-integer pixels, the socalled DMD pixel quantization error. 27) In view of this, some relevant scholars put forward a kind of DMD-based oblique scanning exposure mode to achieve sub-pixel accuracy, 2,8,23) which can better meet the requirements of the lithography resolution and lithography efficiency. In this method, DMD is rotated to form a certain angle with the scanning direction, and then a smaller size pixel is formed by using the exposure position and the amount of spot integral energy.…”

“…where θ is the tilting angle and N is the tilting factor. According to previous studies, 23,28) we have built a DMDbased oblique scanning exposure system and successfully applied it to the high-resolution fabrication of large-area grating. In this study, N = 8 was still taken as the experimental parameter, and then the tilting angle θ can be calculated as 7.125°.…”