Overlay Mark Structure Using Fluorescence for Precise Lithography Alignment
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Solution Overview
Problem
The challenge in semiconductor manufacturing is accurately measuring overlay errors in photoresist patterns and underlying patterns due to unclear optical images between current and pre-layers in lithography operations.
Innovation Solution
Incorporating a light-emitting feature that emits fluorescence with a specific wavelength and overlay mark structures with varying transmittances to enhance contrast in optical images, allowing for precise measurement of overlay errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional lithography measurement methods are used, then the measurement process is simple, but the overlay error measurement precision deteriorates due to unclear optical images between current and pre-layers
Solution Approach 1:
The patent applies color changes by introducing a light-emitting feature that emits fluorescence with a specific wavelength. The overlay mark structure includes regions with different transmittances to this fluorescence, creating distinct brightness differences (color changes) between the current layer and pre-layer in the optical image. This enables clear differentiation and precise measurement of overlay errors between layers.
Solution Approach 2:
The patent introduces an intermediary light-emitting feature and overlay mark structure between the current layer and pre-layer. This intermediary structure emits fluorescence that passes through the overlay mark regions with different transmittances, creating a visible contrast in the optical image that facilitates accurate overlay error measurement without directly modifying the device layers themselves.
2Measurement precision
If a light-emitting feature with fluorescence is introduced, then the contrast between current and pre-layers is improved, but the device structure complexity increases
Solution Approach 1:
The overlay mark structure serves multiple functions: it acts as an alignment reference for lithography, a fluorescence filter with varying transmittances, and a measurement target for overlay error detection. By integrating these functions into a single structure, the patent achieves improved optical contrast without proportionally increasing overall device complexity.
Solution Approach 2:
The patent applies local quality by creating regions within the overlay mark structure that have different transmittance properties to the fluorescence wavelength. Specifically, the structure includes regions with first transmittance and regions with second transmittance, allowing localized differentiation between current and pre-layers while maintaining a relatively simple overall structure.
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 improves the accuracy of overlay error calculation by enhancing the contrast between current and pre-layers in optical images, enabling more precise alignment of semiconductor device layers.
Implementation Method 1
The first light-emitting feature includes metal ions utilized to emit a fluorescence with a first wavelength
Implementation Method 2
The overlay mark structure is configured to absorb and/or reflect a fluorescence emitted from the first light-emitting feature
Implementation Method 3
The overlay mark structure is configured to absorb and/or reflect a fluorescence emitted from the first light-emitting feature
Data Source
AI summary
A semiconductor device structure with overlay marks is provided. The semiconductor device structure includes a substrate, a first light-emitting feature, a first pattern and a second pattern. The first light-emitting feature is disposed on the substrate. The first pattern is disposed on the first light-emitting feature. The second pattern is disposed on the first pattern. The first light-emitting feature is configured to emit a light of a first wavelength. The first pattern has a first transmittance to the light of the first wavelength. The second pattern has a second transmittance to the light of the first wavelength. The first transmittance is different from the second transmittance.