SEM Image Enhancement for High-Throughput IC Inspection
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Solution Overview
Problem
Scanning electron microscopy (SEM) image enhancement techniques for high-throughput inspection of integrated circuit components face challenges in maintaining image quality due to reduced resolution and increased beam current or multiple beams, leading to distorted or lost small-scale features.
Innovation Solution
The method involves acquiring a first SEM image at a high resolution and a second SEM image at a lower resolution, using features extracted from the high-resolution image to enhance the low-resolution image, either by pattern matching or numerical compensation, thereby improving image quality without compromising throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple beams are used to increase inspection throughput, then productivity is improved, but image quality deteriorates due to resolution losses from off-axis beam aberrations
Solution Approach 1:
The patent creates a digital copy (point spread function) of the beam's effect on the sample and applies it computationally to correct the low-resolution image, avoiding the need for physical high-resolution imaging while maintaining image quality
Solution Approach 2:
The patent introduces a computational intermediary (deconvolution algorithm using point spread function) that mediates between the low-resolution physical measurement and the desired high-resolution image, separating the measurement process from the resolution requirement
2Productivity
If beam current is increased to improve throughput, then productivity is improved, but image quality deteriorates due to increased spot size
Solution Approach 1:
The patent creates a computational model (point spread function) that copies the beam's spatial distribution effects and applies it to correct the image, allowing high current usage without the corresponding loss of resolution
Solution Approach 2:
The patent replaces the mechanical/optical constraint (spot size limitation from high beam current) with a computational solution (deconvolution algorithm), substituting physical imaging limitations with digital signal processing
3Productivity
If inspection pixel sizes are increased to improve throughput, then productivity is improved, but image quality deteriorates due to reduced sampling
Solution Approach 1:
The patent creates a computational representation of the sampling process (point spread function) and uses it to reconstruct fine details that were not captured in the original low-resolution image
Solution Approach 2:
The patent transforms the problem from the spatial domain (pixel resolution) to the frequency domain (point spread function in Fourier space), allowing recovery of high-frequency information through computational methods rather than increased spatial sampling
Data Source
AI summary
Systems and methods for image enhancement are disclosed. A method for enhancing an image may include acquiring a first scanning electron microscopy (SEM) image at a first resolution. The method may also include acquiring a second SEM image at a second resolution. The method may further include providing an enhanced image by using the first SEM image as a reference to enhance the second SEM image. The enhanced image may be provided by using one or more features extracted from the first image to enhance the second SEM image, or using the first SEM image as a reference to numerically enhance the second SEM image.