光电工程  2020, Vol. 47 Issue (6): 190387      DOI: 10.12086/oee.2020.190387

DMD maskless lithography stitching error correction based on motion compensation
Jiang Xu, Yang Xu, Liu Hong, Hu Jun, Wang Yingzhi
Electronic Information Engineering, Changchun University of Science and Technology, Jilin, Changchun 130000, China
Abstract: For the digital micromirror device (DMD) lithography equipment, due to the exposed images joint errors which caused by mechanical loading errors, problems such as misalignment and overlap of the exposed images may arise. In order to eliminate the exposure error of DMD during large-area exposure, the error correction method was studied. Firstly, the exposure error was got by measuring the exposed substrate with a microscope. Then, an error model was established based on the known exposure error. Finally, an error correction based on motion compensation for DMD lithography system was proposed based on the error model. This method is different from the existing error correction method. The experimental results show that during the micron image exposure process, the exposure error is reduced by more than 80%, and the DMD exposure center offset distance is reduced from 175 μm to 21 μm. The stitching accuracy of the exposed image is improved effectively, which meets the requirements for high quality and high precision of large-area exposure images.
Keywords: DMD lithography    DMD large area exposure    motion compensation    inclination error

1 引言

2 数字光刻系统

 图 1 数字光刻系统示意图 Fig. 1 Schematic diagram of digital lithography system

 ${d^ * } = d/\left| \beta \right|,$ (1)

3 倾角误差校正方法 3.1 数学模型

 图 2 (a) 不平行性误差的示意图；(b)曝光过程中倾角误差的示意图 Fig. 2 (a) Schematic diagram of non-parallel error; (b) Schematic diagram of the inclination error during exposure

 $OC = 2 \times {d^ * }{\kern 1pt} {\rm{sin}}(\theta /2)。$ (2)

 $AB = {d^ * }{\kern 1pt} {\rm{cos}}\theta ,$ (3)
 $OB = {d^ * }{\kern 1pt} {\rm{sin}}\theta ,$ (4)

3.2 运动补偿的校正方法

 图 3 曝光实验步骤示意图 Fig. 3 Exposure experiment steps

 图 4 角度测量示意图 Fig. 4 Angle measurement diagram

 ${d^ * } = d/\left| \beta \right|。$ (5)

DMD的分辨率是1024×768，在得到误差夹角后可以利用倾角误差校正方法求出Δx和Δy的数值：

 ${\Delta x = 1024{d^*}{\rm{cos}}\theta , }$ (6)
 ${\Delta y = 768{d^*}{\rm{sin}}\theta }。$ (7)

4 实验结果

 图 5 曝光图案示意图 Fig. 5 Exposure pattern

 图 6 大面积曝光结果 Fig. 6 Large area exposure results

 图 7 误差测量结果 Fig. 7 Error measurement result

 ${{d^*} = d/|\beta | = 13.68 \div 2.2 = 6.218{\kern 1pt} {\kern 1pt} {\kern 1pt} {\rm{ \mathsf{ μ} m}}}。$ (8)

 ${\Delta x = 1024 \times {d^*}{\kern 1pt} {\rm{cos}}{\kern 1pt} 1.776 = 6.364{\kern 1pt} {\kern 1pt} {\kern 1pt} {\rm{mm, }}}$ (9)
 ${\Delta y = 768 \times {d^*}{\kern 1pt} {\rm{sin}}{\kern 1pt} 1.776 = 0.148{\kern 1pt} {\kern 1pt} {\kern 1pt} {\rm{mm, }}}$ (10)

 ${\Delta d = 1024 \times 2 \times {d^*}{\kern 1pt} {\rm{sin}}{\kern 1pt} 1.776/2 = 0.198{\kern 1pt} {\kern 1pt} {\kern 1pt} {\rm{mm}}, }$ (11)
 ${\Delta {d^\prime } = 1024 \times 2 \times {d^*}{\kern 1pt} {\rm{sin}}{\kern 1pt} 0.127/2 = 0.014{\kern 1pt} {\kern 1pt} {\kern 1pt} {\rm{mm}}}。$ (12)

 图 8 校正后曝光实验结果 Fig. 8 Corrected exposure experiment results

 图 9 校正后大面积曝光结果 Fig. 9 Corrected large area exposure results

 测量位置 首次曝光误差倾角/(°) 首次曝光中心偏移/mm 二次曝光误差倾角/(°) 二次曝光中心偏移/mm 倾角误差缩减率/% 1 1.776 0.198 0.127 0.014 92.9 2 1.523 0.169 0.083 0.009 94.6 3 1.983 0.165 0.248 0.021 95.9 4 2.254 0.188 0.376 0.032 83.4 5 1.657 0.138 0.143 0.012 91.4 6 1.857 0.155 0.237 0.020 87.3 7 1.675 0.140 0.179 0.015 89.4 8 1.897 0.158 0.275 0.023 85.6 9 1.938 0.215 0.303 0.034 84.4 10 2.035 0.226 0.289 0.032 85.8
5 结论

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