Recessed Alignment Mark Structure for Precise Gate Pattern Overlay
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Solution Overview
Problem
Existing overlay inspection methods in semiconductor manufacturing rely on rectangular or square patterns for alignment marks, which are inefficient in ensuring precise alignment of mask patterns across multiple layers, leading to potential misalignment issues.
Innovation Solution
A semiconductor structure with alignment marks featuring gate patterns on recesses, where the top plane of the metal layer is lower than the recess top plane, and the gate patterns are formed using a unique photolithography process to ensure precise alignment and minimize residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rectangular or square patterns are used for alignment marks, then the structure is simple and easy to manufacture, but the alignment precision between mask patterns is insufficient
Solution Approach 1:
The alignment mark is divided into multiple segments including a recess structure and a gate pattern with metal layer. This segmentation allows the alignment mark to provide more precise alignment references while maintaining manufacturability through standardized process steps.
Solution Approach 2:
The alignment mark structure is extended from a simple two-dimensional rectangular pattern to a three-dimensional structure with a recess and a gate pattern featuring a metal layer. This dimensional enhancement provides additional alignment features that improve precision without significantly complicating the manufacturing process.
2Manufacturing precision
If multiple mask overlapping steps are performed, then complete semiconductor patterns can be formed, but cumulative misalignment errors increase
Solution Approach 1:
The enhanced alignment mark structure with gate patterns and metal layers provides more accurate feedback references for each mask overlapping step. This allows real-time verification and correction of alignment accuracy, preventing cumulative errors from propagating through multiple processing steps.
3Manufacturing precision
If photolithography materials are not completely removed from alignment marks, then manufacturing speed is maintained, but alignment accuracy deteriorates due to residue formation
Solution Approach 1:
The gate pattern with metal layer provides a distinct local quality difference on the alignment mark surface. This local differentiation ensures that photolithography materials can be selectively and completely removed from specific areas while maintaining the structural integrity and alignment functionality of the mark.
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
The solution enhances the precision of mask pattern alignment, reducing misalignment errors and improving the accuracy of semiconductor manufacturing by ensuring consistent and complete removal of photolithographic materials from alignment marks.
Implementation Method 1
performing a photolithography process to pattern the photolithographic material layer to form a photolithographic material pattern
Implementation Method 2
performing an etching process using the photolithographic material pattern as a mask to pattern the photolithographic material layer into gate patterns
Data Source
AI summary
A semiconductor structure is provided in the present invention, including a substrate, a recess in the substrate, an alignment mark in the recess, and a gate pattern on the alignment mark and including a metal layer, wherein a top plane of the metal layer is lower than a top plane of the recess.