Polarization Interferometry for One-Shot Semiconductor Overlay Measurement
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Solution Overview
Problem
The miniaturization of semiconductor structures has led to decreased overlay margins, necessitating improved methods for in-cell and key overlay measurements that can reduce the size of the measurement spot and perform overlay measurements quickly with fewer shots, while obtaining measurements for all angles with one shot.
Innovation Solution
A semiconductor measurement device that utilizes a polarization unit to separate a laser beam into multiple beams with different polarization information, a beam splitter to direct these beams onto a semiconductor substrate, and a multiplex self-interference generation unit to generate and detect a multiplex self-interference image, allowing extraction of off-diagonal components of the Mueller matrix for precise overlay analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional overlay measurement methods are used, then measurement completeness is improved, but measurement time and number of shots increase
Solution Approach 1:
The patent combines multiple polarization states (s-polarized and p-polarized beams) into a single measurement shot by using a polarization beam splitter to create multiplex self-interference patterns. This merging allows all necessary polarization information to be captured simultaneously in one shot rather than requiring separate measurements for each polarization state, thereby reducing measurement time while maintaining complete overlay measurement capability.
Solution Approach 2:
The patent employs periodic modulation of the polarization state through a polarization modulator to encode different polarization information into a single interferogram. By periodically varying the polarization angle and capturing the resulting multiplex self-interference patterns, the system can extract complete overlay measurement data from one shot without requiring multiple sequential measurements.
2Manufacturing precision
If spot size is reduced for miniaturized structures, then measurement relevance is improved, but signal intensity decreases
Solution Approach 1:
The patent creates virtual copies of the incident beam through self-interference by generating both s-polarized and p-polarized beams from a single incident beam using a polarization beam splitter. These copied beams interfere with each other to produce multiplex self-interference patterns that contain enhanced signal information, allowing sufficient signal intensity to be obtained even when measuring miniaturized structures with reduced spot sizes.
Solution Approach 2:
The patent combines multiple polarization components (s-polarized and p-polarized beams) into a composite measurement signal through multiplex self-interference. This composite approach allows the system to maintain strong signal intensity by utilizing the combined information from multiple polarization states, enabling reliable measurements on miniaturized structures where signal strength would otherwise be insufficient.
3Measurement precision
If multiple shots are used for comprehensive measurement, then measurement completeness is improved, but productivity decreases
Solution Approach 1:
The patent merges multiple measurement functions into a single shot by simultaneously generating and detecting multiplex self-interference patterns from s-polarized and p-polarized beams. This consolidation allows complete overlay measurement data to be obtained in one shot rather than requiring multiple sequential shots, thereby significantly improving measurement throughput and productivity while maintaining comprehensive measurement capability.
Solution Approach 2:
The patent creates a universal measurement system that can extract multiple types of overlay information (including both diagonal and off-diagonal Mueller matrix components) from a single multiplex self-interference measurement. This multi-functional approach allows the system to perform comprehensive overlay measurements with one shot, eliminating the need for multiple specialized measurements and thereby maximizing productivity.
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
Enables reliable and efficient overlay measurements by reducing the number of shots required and providing comprehensive angle coverage with one shot, enhancing the accuracy and speed of semiconductor inspection processes.
Implementation Method 1
a polarization unit arranged on a path of the laser beam generated from the light source and configured to separate the laser beam into a first beam and a second beam
Implementation Method 2
a multiplex self-interference generation unit configured to separate a beam reflected from the top surface of the semiconductor substrate into a third beam and a fourth beam and to cause multiplex self-interference of the third beam and the fourth beam
Data Source
AI summary
A semiconductor measurement device includes a light source configured to generate a laser beam, a polarization unit arranged on a path of the laser beam generated from the light source, and configured to separate the laser beam into a first beam and a second beam, a beam splitter configured to make the first beam and the second beam, having been separated by the polarization unit, incident on a top surface of a semiconductor substrate, a multiplex self-interference generation unit configured to separate a beam reflected from the top surface of the semiconductor substrate into a third beam and a fourth beam and to cause multiplex self-interference of the third beam and the fourth beam, and a detection unit configured to detect a multiplex self-interference image generated from the third beam and the fourth beam, wherein the polarization unit may include a polarization unit delayer.