The latest progress of soft X-ray interference lithography at Shanghai Light Source. (2020)
2. Research Background
Soft X-ray interference lithography (XIL) technology is a new type of advanced micro- and nano-processing technology that uses the interference fringes of two or more coherent soft X-ray beams to expose photoresists, and can carry out dozens or even dozens of nanometer cycles. nanostructure processing. Compared with other methods such as lithography, XIL technology has the advantages of high resolution, no proximity effect, no pollution, and high output. It can more reliably obtain large-area, high-quality sub-50nm high-density periodic nanostructures. The soft X-ray interference lithography line station of Shanghai Light Source was opened to users in 2013. The construction of this line station aims to take advantage of the advantages of low emissivity, high brightness and high coherence of soft X-rays to establish a high-efficiency, low-cost, high-precision nano-processing technology platform at Shanghai Light Source. Internationally, the XIL-II line station of the Swiss light source and the BL-9 line station of the New SUBARU light source in Japan have carried out a lot of related research work based on this technology.
Researcher Wu Yanqing gave a detailed introduction to the recent work done by Shanghai Light Source's XIL line station on the development of this technology.
3. Latest progress
The soft X-ray interference lithography line station of Shanghai Light Source has established a set of accurate vibration evaluation system based on laser interferometer. The quantitative evaluation of the vibration of the exposure system provides guidance for the subsequent vibration reduction methods, and finally the vibration of the exposure system of the experimental station is controlled below the RMS value of 2.5 nm, laying a good hardware foundation for the interference exposure experiment. On this basis, the line station has developed experimental methods such as high-order diffraction interference lithography, large-area stitching depth exposure, and parallel direct writing Taibao lithography. The exposure resolution, exposure depth, and exposure area of the line station have been improved, and the exposure of complex periodic graphics has also been realized.
The high-order diffraction interference lithography method is an exposure method using second-order and above-order diffracted beams for interference lithography, which can realize the reduction of the exposure pattern period by 1/4 of the original mask lithography period. As shown in Figure 1. The current pattern half period (HP) is about 25nm. This technique has been used for EUV photoresist inspection.
The EUV Parallel Direct-Writing Taibao Lithography Method
describes a parallel direct-write lithography method based on a nano-displacement platform to achieve the exposure of strict periodic patterns of complex cells. As shown in Figure 3. This technology can be used for metasurface research and application.
Interesting use of X-Ray lithography techniques.
