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In UV imprint, positioning errors can occur between a mold and a wafer due to pressure when there is a contact with the UV resin. The moiré technique, which is produced by superimposition of two gratings, is a well-known and simple method for high-resolution position measurement. However, the authors believe that a direct observation of two separate gratings is more appropriate for higher positioning accuracy. Here they propose a new method for the position measurement, which obtains "electronic" moiré fringes by combining the images of two separate gratings from different areas of the mold and the wafer. The fundamental detection error was = 0.15 nm. The repeatabilities of the total system was = 0.68 nm in air and = 0.73 nm in resin. The linearity of the measurement value to control signal was R 2 = 0.97.

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As semiconductor device geometry shrinks down to the 100 nm order for the most critical layers, requirements for overlay accuracy have become increasingly strict in the semiconductor manufacturing process. One contribution to overlay error (particularly alignment error) originates from the process and tool interaction. Therefore, it is necessary to improve the alignment accuracy of both the process and the tool. Alignment errors can be separated into tool-induced shift (TIS), wafer-induced shift (WIS), and TIS-WIS interaction. In this study, optimization of the alignment mark will be proposed in order to reduce not only TIS, but also WIS for the XRA-1000, which is the volume production stepper of proximity X-ray lithography (PXL).

We propose a new inspection method of in-line focus and dose control at semiconductor volume production. We have been referred to this method as Focus & Dose Line Navigator (FDLN). Using FDLN, the deviations from the optimum focus and exposure dose can be obtained by measuring the topography of resist pattern on a process wafer that was made with single exposure condition. Generally speaking, FDLN belongs to the technology of solving the inverse problem as scatterometry. The FDLN sequence involves following two steps.Step 1: creating a focus exposure matrix (FEM) using test wafer for building the library as supervised data. The library means relational equation between the topography of resist patterns (critical dimension (CD), height, side wall angle) and FEM's exposure conditions.Step 2: measuring the topography of resist patterns on production wafers and feeding the topography data into the library to extrapolates focus and dose. To estimate the accuracy of FDLN, we had some experiment. We made a FEM with ArF lithography tool and measured the topography of the FEM with optical CD measurement tool. By using the topography data, we obtained following result as accuracy of FDLN. Focus: 27.0nm (5.2nm) and Dose: 1.8% (1.4nm). The numerical value in a parenthesis shows the value of estimated accuracy into change of CD value. We also show other experimental results and some simulation result in this paper.