Data preparation for digital scanner

Abstract

Nikon has been developing the Digital Scanner (DS), an optical maskless exposure tool with a DUV light source and a micromirror-type spatial light modulator (SLM). Rasterized digital data, essentially huge bitmap files, are used to drive the SLM. The DS enables new applications such as large area printing and chip customization because its digital pattern data are easily modified. Flexible and fast data preparation software was developed for the new applications. As a standard operation of DS data preparation software, a CAD file (GDS or OASIS) is converted into bitmap files. In addition, bitmap file generation by a scripting language is available without a CAD file. This is useful when the CAD file includes a lot of polygons in which each polygon is similar but not identical, resulting in a huge file. As an example of application, a metasurface consists of sub-wavelength periodic patterns with various shapes, which are arranged to achieve the desired optical effect. The shape of each pattern at a grid point can be determined by a computer program, i.e., a pattern generator script. On the other hand, data preparation time can be shortened for periodic pattern which is often seen in semiconductor circuits. We report those data preparation methods for the DS, which have been used for our recent exposure experiments.

Expected performance of digital scanner and the potential application for advanced semiconductor fabrication

“…The first method is to apply OPC to target pattern and then convert it to DS pixel mask. Any OPC tools can be used, while the conversion software from OPC mask to pixel mask was specifically developed for DS 6) . In this case, the pixel mask is iteratively adjusted such that the projected image of DS becomes equivalent with that of the polygon mask.…”

“…One alternative technology is maskless exposure, which has advantages over mask exposure tool. Recently, the Digital Scanner (DS), a DUV optical maskless exposure tool, is being developed [2][3][4][5][6] . DS uses a micromirror-type spatial light modulator (SLM) to create the "mask" pattern combined with a solid-state laser with wavelength of 193 or 248 nm.…”

“…The DS system is described in previous papers [2][3][4][5][6] . This paper describes key features and application areas of DS in section 2, target specification of the first product scanner, DS248, in section 3, and the exposure results of DS proof-of-concept tool (DS-POC), which has a similar imaging performance with DS248, in section 4.…”

Review of optical direct-write technology for semiconductor manufacturing

“…Recently, a technology called the digital scanner (DS) was introduced 15 – 18 Figure 2 shows schematic diagram of DS, which uses deep UV (DUV) solid-state laser of wavelength 248 or 193 nm as the light source, and a SLM whose parameters and operation are different from past SLMs. It has DUV lithography resolution <100 nm, the same resolution as that of conventional mask DUV scanners.…”

“…Various patterning demonstrations on 200- and 300-mm silicon wafers were done using a DS proof-of-concept (DS-POC) exposure system, whose numerical aperture (NA) is 0.675 and exposure wavelength is 193 nm. Exposed samples 15 – 18 include half-pitch 80-nm line and space pattern, 180-nm-logic integrated circuit patterns, chip-ID printing, subpixel pattern edge control, a mixture of different chips on a wafer, and large-size patterning including meta lens and silicon interposer for heterogeneous integration. Those are the realizations of the expected performance of the optical direct-write system designed for semiconductor manufacturing at DUV resolution.…”