Fabrication Of Gratings Based On The Nanoimprint Lithography

Gratings with micrometer or nanometer size are widely used in the field of displacement measurement, optical coupling and spatial modulation. Gratings are vital micro optical elements when we talk about most advanced optical research focus, such as micro optics, nano photonics and surface plasmon optics. At present, the micro-nano machining technology has replaced the traditional mechanical method, becoming the main means of fabricating gratings. However, the existing micro-nano method used to fabricate grating is faced with the problem of high cost, low production efficiency, and complex equipment. The nanoimprint lithography is expected to solve these problems. In this thesis I conducted in-depth study on how to use nanoimprint lithography in grating fabrication field. I analyzed the key problems that hindered the application of nanoimprint technique for fabrication of grating. I found out that the imprint template was too expensive and the related technology was not mature. Around these problems, this thesis studied the two below aspects: the preparation of the imprint template and the process of imprint lithography.In this thesis, anisotropic wet etching process of silicon was proposed for the fabrication of imprint template. With this method, the V-profile template, Pyramid structure template and 2D square-array template were prepared successfully. The V-profile template contained micro pitch of 2 μm, and the blazed angle was 54.7. The 2D square array template can reach the same level with the template fabricated by the electron beam writing technology. This method was low-cost, simply-operated, and suitable for mass production. So it was of high value. In addition, in this thesis, I worked on the replication techniques of imprint template. I established a system using the micro-electroforming technology to replicate existing imprint template. In the process, I come up with a way to avoid damage to the template, by applying graphic carrier. In this thesis, a variety of nickel templates were made with a high accuracy of replication.In this thesis, the process of the imprint lithography was well studied in detail. For the fabrication of 2D grating and the blazed grating, the corresponding schemes of imprint process were designed. And the difficult technical problems were solved. In the end, the 2D grating and the blazed grating were fabricated by nanoimprint technology on the quartz glass substrates, and the reasonable technological parameters were obtained.This thesis summarized the whole process of using nanoimprint technology to produce gratings, from the template making process to implement the complete application. The way described in this thesis demonstrated the advantages of low cost, high production efficiency without the need for expensive equipment investment. So it was of high practical value.