Defocusing detection based on asymmetric placement of dual-quadrant detector

In the field of laser photolithography, automatic focusing is a key technology. The focusing degree of the writing light on the sample surface determines the quality of photolithography. In addition to the mask manufacturing in semiconductor industry, autofocus is also widely used in optical imaging and optical information reading. With the increasing demand of semiconductor market, it is necessary to reduce the cost of autofocus as much as possible on the premise of ensuring the accuracy. Dual-quadrant detector(DQD) is a kind of detector combining two photodetectors, in which the common edge of two photodetectors is usually a straight line. In this work, a defocusing detection method using a dual-quadrant detector is proposed, the expression of focusing error signal(FES) is defined. The relationship between defocus amount and FES is analyzed and simulated, accordingly. A focusing error detection system is established to demonstrate the theoretical analysis. The tracking range is up to 20μm, and the tracking accuracy is approximately 50. The theoretical and experimental results indicate that the defocusing detection method with a dual-quadrant detector takes into account the tracking range and tracking accuracy, and has good results. This technology is expected to be used in maskless laser direct writing lithography and optical imaging.

[1]  M. Wegener,et al.  Direct laser writing of three-dimensional photonic-crystal templates for telecommunications , 2004, Nature materials.

[2]  Yiqun Wu,et al.  High-speed maskless nanolithography with visible light based on photothermal localization , 2017, Scientific Reports.

[3]  Xianfan Xu,et al.  16 nm-resolution lithography using ultra-small-gap bowtie apertures , 2017, Nanotechnology.

[4]  A. Lasagni,et al.  Fabrication of multi-scale periodic surface structures on Ti-6Al-4V by direct laser writing and direct laser interference patterning for modified wettability applications , 2017 .

[5]  Fabrication of multi-wavelength visible and infrared filter for solar atmosphere tomographic imaging , 2017 .

[6]  Hyug-Gyo Rhee,et al.  300 mm reference wafer fabrication by using direct laser lithography. , 2008, The Review of scientific instruments.

[7]  M. Roeffaers,et al.  Direct Laser Writing of δ- to α-Phase Transformation in Formamidinium Lead Iodide , 2017, ACS nano.

[8]  Chien-Hung Liu,et al.  Application of the astigmatic method to the thickness measurement of glass substrates. , 2008, Applied optics.

[9]  Hyug-Gyo Rhee,et al.  Performance evaluation of laser lithographic machine for computer-generated hologram , 2011 .

[10]  A. Besancon-Voda,et al.  Modelling the focus error characteristic of a DVD player , 2002, Proceedings of the International Conference on Control Applications.

[11]  Design of a Dual-Wavelength Optical Head for Submicron-Scale and Nano-Scale Lithography , 2011, IEEE Transactions on Magnetics.

[12]  Jingsong Wei,et al.  Chalcogenide phase-change thin films used as grayscale photolithography materials. , 2014, Optics express.

[13]  A G Verhoglyad,et al.  Polar coordinate laser pattern generator for fabrication of diffractive optical elements with arbitrary structure. , 1999, Applied optics.

[14]  Yunwoo Lee,et al.  Realization and performance evaluation of high speed autofocusing for direct laser lithography. , 2009, The Review of scientific instruments.

[15]  N. Luo,et al.  Fabrication of a curved microlens array using double gray-scale digital maskless lithography , 2017 .

[16]  A. G. Poleshchuk,et al.  Methods of improving the accuracy of operation of an autofocus in a circular laser writing system , 2010 .

[17]  Z. Ku,et al.  Nanostructures and Functional Materials Fabricated by Interferometric Lithography , 2011, Advanced materials.

[18]  M Mansuripur,et al.  Analysis of astigmatic focusing and push-pull tracking error signals in magnetooptical disk systems. , 1987, Applied optics.

[19]  Jingsong Wei,et al.  Fabrication of micro/nano multifunctional patterns on optical glass through chalcogenide heat-mode resist AgInSbTe , 2021 .

[20]  A. Barzic,et al.  Fabrication of nanochannels on polyimide films using dynamic plowing lithography , 2017 .

[21]  Jingsong Wei,et al.  Laser‐Assisted Thermal Exposure Lithography: Arbitrary Feature Sizes , 2021, Advanced Engineering Materials.

[22]  Jingsong Wei,et al.  High-speed laser writing of arbitrary patterns in polar coordinate system. , 2016, The Review of scientific instruments.

[23]  Jitendra K. Behera,et al.  Nanostructure patterning of C-Sb2Te3 by maskless thermal lithography using femtosecond laser pulses , 2020 .