Dynamic Haze Mask System for Semiconductor Metrology
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Solution Overview
Problem
Current metrology tools in the semiconductor industry lack effective methods to suppress haze, which affects the signal-to-noise ratio and hinders the detection of embedded defects in semiconductor wafers, particularly in UV and dual-wavelength channels.
Innovation Solution
A dynamic and reconfigurable haze mask system comprising two independently movable masks, one along the tangential direction and the other along the radial direction, is used to minimize haze impact by determining optimal positions based on signal-to-noise ratio and haze values, utilizing a processor to control the masks' positions and shapes for improved sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UV channel is used for defect detection, then embedded defects can be detected, but haze cannot be suppressed effectively
Solution Approach 1:
The patent divides the single mask function into two separate masks: a transmissive mask for UV wavelengths and a reflective mask for visible wavelengths. This segmentation allows each mask to be optimized for its specific wavelength range, enabling effective haze suppression in the UV channel while maintaining defect detection capability
Solution Approach 2:
The patent changes the optical parameters of the masks by using different materials with specific transmission and reflection properties at different wavelengths. The transmissive mask is designed to transmit UV light while blocking haze, and the reflective mask reflects visible light to suppress haze, thereby optimizing haze suppression across different wavelength channels
2Measurement precision
If dual wavelength channel is used, then embedded defects detection is improved, but haze suppression remains ineffective
Solution Approach 1:
The patent segments the dual-wavelength detection system into two independent optical paths, each with its own optimized mask. The UV path uses a transmissive mask while the visible path uses a reflective mask, allowing each wavelength channel to suppress haze effectively while maintaining the ability to detect embedded defects
Solution Approach 2:
The patent introduces wavelength-selective optical elements as intermediaries between the light source and the wafer. These intermediaries (transmissive and reflective masks) are designed to selectively interact with different wavelength components, suppressing haze in each channel while preserving the dual-wavelength capability for embedded defect detection
Data Source
AI summary
This system and method minimize an effect of haze to signal-to-noise ratio and compensate for haze on the haze map. A first mask with a first aperture is disposed along the path of the light beam between a light source and a collector. A first actuator moves the first mask along a tangential direction. A second mask with a second aperture is disposed along the path of the light beam between the first mask and the collector. A second actuator moves the second mask along a radial direction perpendicular to the tangential direction. The first mask and the second mask are independently movable along the tangential direction and the radial direction using the first actuator and the second actuator.