Development of an Optical Alignment System for Nanoimprint Lithography
Date Issued
2006
Date
2006
Author(s)
Ding, LiAn
DOI
zh-TW
Abstract
The main subject of this thesis is to design an optical system applied to the alignment of nano-imprint lithography. Under the premise of all optical elements being well-aligned, the alignment between the mold plane and the wafer plane only involves 2-D plane and rotation of z axis. There are two emphases on the thesis. The first is the alignment procedure of the entire optical elements, including zero-degree incidence, focus control and the horizontal adjustment of grating planes.
The second emphasis is two-axis alignment setup between the mold and the wafer. A scanner-like, dual-stage control method is used . In the first stage we use the underneath position stage along with traditional alignment marks and white light microscopy to achieve micron-level coarse alignment.
In the second stage, we adopt the near-field measurement along with piezo-electric actuator in the alignment system to achieve nano-range positioning. The near-field measurement is based on grating-coupled principle, using the curve of first-order light intensity variation as the alignment reference.
We compare the results with G-solver simulation and found out that the error sources are primarily from vibration of the position stages and defects of the grating structure. From the experiment results, the clear signal variation within a grating pitch movement can be obtained while both factors are under control. The signal can then used for second stage fine alignment, and break the limitation of convertional optical
Subjects
奈米壓印
對位技術
位移平台
近場量測
nano-imprint lithography
overlap control
precision alignment
near-field measurement
Type
thesis