Semiconductor Overlay Mark Alignment Using Photoluminescent Layers
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Solution Overview
Problem
The semiconductor industry faces challenges in accurately measuring overlay errors in photoresist patterns and underlying patterns due to asymmetric shapes of measurement structures, making precise alignment detection difficult.
Innovation Solution
A method involving the formation of a semiconductor structure that includes a photoluminescent layer on an overlay mark, an intermediate layer over the photoluminescent layer and substrate, and a patterned mask layer for detecting alignment using optical signals and electrical signals processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional measurement structures are used for overlay error detection, then the manufacturing process is simpler, but the measurement precision deteriorates due to asymmetric shapes making accurate alignment detection difficult
Solution Approach 1:
The patent creates optical copies of overlay marks at different elevations by forming photoluminescent layers on first and second patterns at different heights. The alignment detection system captures optical images of these photoluminescent layers, effectively creating virtual copies that can be analyzed for overlay errors without requiring direct physical access to both patterns simultaneously. This resolves the measurement precision issue by enabling accurate comparison of asymmetric shapes through their optical representations.
Solution Approach 2:
The patent introduces photoluminescent layers as intermediary elements between the physical patterns and the detection system. These layers convert the physical positions of patterns at different elevations into optical signals that can be captured and analyzed. The intermediary photoluminescent layers enable precise measurement of overlay errors by translating three-dimensional positional information into two-dimensional optical images that can be processed by alignment detection equipment.
2Measurement precision
If overlay marks are placed at different elevations to improve measurement capability, then the measurement precision improves, but the device complexity increases due to multiple layers and materials required
Solution Approach 1:
The patent utilizes the vertical dimension by forming photoluminescent layers at different elevations (first elevation and second elevation) to encode overlay information. This dimensional approach allows the system to measure overlay errors between patterns that are vertically separated, effectively using the third dimension (height) to resolve the measurement challenge while maintaining a relatively simple planar structure when viewed from above.
Solution Approach 2:
The patent employs composite material structures including photoluminescent materials deposited on different patterns at different elevations. These composite structures combine multiple materials (substrate, pattern materials, photoluminescent coatings) to create a multi-functional overlay mark system that provides both structural support and optical detection capabilities, resolving the precision-complexity contradiction through material integration.
3Manufacturing precision
If photoluminescent layers are formed on patterns at different elevations, then the alignment detection accuracy improves, but the manufacturing complexity increases due to additional deposition and patterning steps
Solution Approach 1:
The patent performs preliminary actions by forming the first photoluminescent layer on the first pattern at a first elevation before forming the second pattern and second photoluminescent layer. This sequential approach allows each photoluminescent layer to be independently optimized and deposited under controlled conditions, improving alignment detection accuracy while managing manufacturing complexity through staged fabrication rather than simultaneous complex processing.
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
This approach enables precise detection of alignment between overlay marks at different elevations, improving the accuracy of overlay error measurement and reducing the complexity of alignment processes in semiconductor manufacturing.
Implementation Method 1
forming a photoluminescent layer on the first pattern
Implementation Method 2
an optical device, configured to emit a radiation to excite a photoluminescent material
Implementation Method 3
an optical filter, configured to receive and filter a radiation emitted from the photoluminescent material
Implementation Method 4
an optical detector, configured to convert an optical signal filtered by the optical filter to an electrical signal
Data Source
AI summary
The present disclosure provides a semiconductor structure and a system for manufacturing the semiconductor structure. The system includes a fabrication equipment, configured to perform operations to form a layer on a wafer; an exposure equipment, configured to perform patterning operations to form a pattern of the layer; and an alignment equipment, configured to detect an alignment of two overlay marks at different elevations on the wafer. The alignment equipment includes a stage, configured to support the wafer; an optical device, configured to emit a radiation to excite a photoluminescent material of one of the two overlay marks; an optical filter, configured to receive and filter a radiation emitted from the photoluminescent material; and an optical detector, configured to convert an optical signal filtered by the optical filter to an electrical signal.