• Acta Photonica Sinica
  • Vol. 52, Issue 6, 0631001 (2023)
Xiuhua FU1、2, Junqi LIU1、*, Zhuolin LI3, Haicheng LIU1, Haifeng REN4, Yibo WANG1, and Kexu HAN1
Author Affiliations
  • 1College of Optoelectronic Engineering, Changchun University of Science and Technology, Changchun 130022, China
  • 2Zhongshan Research Institute, Changchun University of Science and Technology, Zhongshan 528436, China
  • 3Moral Education and Comprehensive Teaching and Research Training Department, Jilin Provincial Institute of Education, Changchun 130022, China
  • 4Guang Chi Technology (Shanghai) Co., Ltd., Shanghai 200444, China
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    DOI: 10.3788/gzxb20235206.0631001 Cite this Article
    Xiuhua FU, Junqi LIU, Zhuolin LI, Haicheng LIU, Haifeng REN, Yibo WANG, Kexu HAN. Study on Thickness Uniformity of Double-sided Sputtering Film on Large-diameter Ultra-thin Substrates[J]. Acta Photonica Sinica, 2023, 52(6): 0631001 Copy Citation Text show less

    Abstract

    As an important part of the original fingerprint identification under the optical screen, the infrared cut-off filter needs to be plated on a large-diameter and ultra-thin substrate in order to connect the subsequent processing process and facilitate mass production. The substrate surface type has very high requirements. In recent years, many scholars have done a lot of experimental research on the issues related to the uniformity of sputtering coating film thickness, but there are few references on the related research on the uniformity control of ultra-thin and large-area substrates. In the traditional method of coating double-sided film layers, in the process of using ultra-thin and large-diameter substrates, only one side can be plated first, and then the substrate can be taken out and turned over to coat the other side. This operation is inefficient and the risk of substrate chipping is high and the film uniformity is poor, which will cause uneven stress distribution in the film layer, resulting in the bending of the substrate, which can not meet the actual use requirements. In this paper, two materials, SiO2 and Nb2O5, are used as the research objects, and the influence on the film thickness uniformity is analyzed from three aspects: the distribution of the magnetic field intensity of the target material, the public-rotation system, and the shielding angle of the substrate fixture. According to the experimental results, the relative strength of the target magnetic field has a certain relationship with the uniform distribution of the relative thickness of the film, and the relative thickness of the film will also increase when the relative strength of the magnetic field is larger. The revolution system can greatly improve the film thickness uniformity. In this paper, the film thickness uniformity under three rotational speed ratios of 1∶2, 2∶1, and 5∶4 is studied. When the rotational speed ratio is 5∶4, the film thickness is uniform,and the uniformity is the best. The film uniformity of SiO2 increases from 17.31% when only rotating to 3.86%, and the film uniformity of Nb2O5 increases from 15.99% when only rotating to 3.41%. After calculation, the coating efficiency and target utilization rate increase by 12.3% and 17.6% respectively. Since the equipment has a public rotation system, the edge of the substrate fixture will block the effective coating area. In this paper, five blocking angles of 0°, 20°, 35°, 55°, and 70° are studied. Among them, SiO2 single-layer film is thin at a 20° blocking angle, and has the best thickness uniformity, which is 0.62%. The uniformity of 0°, 35°, 55°, and 70° is 1.42%, 5.43%, 7.52%, and 8.58%, respectively. The thickness of Nb2O5 single-layer film is uniform at 20° blocking angle, and the best performance is 0.71%. The uniformity of 0°, 35°, 55°, and 70° is 1.55%, 3.64%, 7.56%, and 10.81%, respectively. Considering factors such as substrate loading and uniformity, a 20° blocking angle is selected for the preparation of the infrared cut-off filter. The filter is made of D263T substrate with a diameter of 20.32 cm and a thickness of 0.07 mm. In order to balance the influence of the film stress on the upper and lower surfaces on the surface shape of the substrate as much as possible, the Essential Meclord software is used to adopt the design of a symmetrical film system. The physical thicknesses of the upper and lower surfaces are 3 944.27 nm and 4 366.19 nm, respectively. After measurement of the prepared samples, the wavelengths at the transmittance of 50% are 572.6 nm and 572.5 nm, the transmittance at the 450~550 nm band are 97.59%, 98.14%, and the transmittance at the 590~1 100 nm band is 0.042%, 0.048%, which all meet the design and practical application requirements. The sample uniformity can reach 0.13% and 0.142%, and the warpage degree of the substrate is 0.085 mm, which meets the requirements. How to obtain a film with a larger effective coating area and better film thickness uniformity on the magnetron sputtering equipment is the key research direction for the next step.
    Xiuhua FU, Junqi LIU, Zhuolin LI, Haicheng LIU, Haifeng REN, Yibo WANG, Kexu HAN. Study on Thickness Uniformity of Double-sided Sputtering Film on Large-diameter Ultra-thin Substrates[J]. Acta Photonica Sinica, 2023, 52(6): 0631001
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