Alignment simulation
US6988060B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 1, 2000 |
| Grant date | Jan 17, 2006 |
| Priority date | — |
| Expiry date | Feb 22, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7076
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An alignment simulation method simulates the signal waveform for an alignment mark using various alignment methods as well as the signal strength for an alignment mark, which is useful in optimizing the thickness of one or more layers as well as the geometry of the mark. The simulation of signal strength is also useful in optimizing the thickness of a layer for artifact wafers. The alignment simulation method includes accurately modeling the alignment mark, including one or more layers of various thicknesses and materials. The accurate modeling of the alignment mark includes such things as smoothing regions of the alignment mark and generating lateral shifts of the layers. The model of the alignment mark is a series of small pixels, each including the thickness of the layers and the layers indices of refraction. Using scalar diffraction, a complex reflectivity is generated for each pixel and a fast fourier transform is performed on the series of pixels. The results of the fast fourier transform are used to simulate the diffraction intensities for the alignment mark alignment systems, such as LIA or LSA as well as the signal waveforms. The LSA signal waveform, however, requires addi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.