Semiconductor Overlay Measurement Using Transmission-Weighted Pattern Matching
Solution Overview
Problem
Existing methods for semiconductor pattern overlay measurement fail to accurately account for the transmission of lower layers through upper layers, leading to reduced pattern matching success rates and overlay measurement precision in multi-layered structures.
Innovation Solution
A semiconductor observation system that adaptively adjusts the consideration range for pattern matching based on the degree of transmission between layers, using a processor to analyze image data and apply weighted pattern matching techniques to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If area division or mask processing is applied to remove upper layer information during pattern matching, then pattern matching accuracy for the lower layer is improved, but essential lower layer information that transmits through the upper layer is erased, reducing pattern matching success rate
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different regions in the image. Instead of uniformly removing upper layer information across the entire image, the method selectively processes only the overlapping regions where upper and lower layers intersect. This allows preservation of lower layer information in non-overlapping areas while still improving pattern matching accuracy in overlapping regions through targeted mask processing.
Solution Approach 2:
The patent employs dynamics by adaptively adjusting the mask processing parameters based on the specific characteristics of each overlapping region. The consideration range and mask application are dynamically determined based on local luminance information and pattern characteristics, rather than using fixed global parameters. This dynamic approach ensures optimal balance between removing upper layer interference and preserving lower layer information in different regions.
2Illumination intensity
If high-energy electron beams are used to reveal lower layer patterns through upper layers, then lower layer visibility is improved, but upper layers still obscure lower layers in overlapping portions, reducing measurement precision
Solution Approach 1:
The patent applies segmentation by dividing the image processing into distinct regions: overlapping regions and non-overlapping regions. For overlapping regions, the method segments out the upper layer pattern information through mask processing to isolate the lower layer pattern. This segmentation allows precise measurement of lower layer patterns even when upper layers are present, overcoming the limitation of high-energy electron beam imaging.
3Device complexity
If pattern matching is performed on overlapping regions without considering layer transmission, then processing simplicity is maintained, but matching failures increase due to upper layer interference
Solution Approach 1:
The patent applies preliminary action by performing area division and determining consideration ranges before executing pattern matching. The method pre-identifies overlapping regions and prepares appropriate mask patterns based on luminance information and design data. This preliminary preparation ensures that when pattern matching is performed, the upper layer interference has already been accounted for, significantly improving matching success rate without adding substantial complexity to the overall process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the success rate of pattern matching and overlay measurement in complex multi-layer structures by dynamically adjusting the pattern matching process based on the transmission characteristics of each layer.
Implementation Method 1
The SEM outputs a captured image (hereinafter, referred to as an image to be measured) by detecting reflected electrons and the like obtained when an electron beam is irradiated onto a semiconductor sample.
Data Source
AI summary
An image of a sample captured by a microscope includes a first layer template image and a second layer template image indicating pattern shapes of a first layer and a second layer. Pattern matching of the second layer is performed based on the second layer template image to acquire a second position deviation amount related to the second layer and an area recognized as the second layer. Pattern matching processing of the first layer is performed based on a first layer consideration range, the first layer template image, and the image to acquire a first position deviation amount related to the first layer and an area recognized as the first layer on the image to be measured. An overlay is measured based on the second position deviation amount and the first position deviation amount.