Contact Plug Opening Structure for Accurate High-Aspect-Ratio Etching
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Solution Overview
Problem
The formation of high aspect ratio etching through holes in semiconductor manufacturing is challenged by issues such as through hole offset, poor contact, and over etching, which affect the exposure of target metal layers and lead to electrical leakage.
Innovation Solution
The method involves forming an annular gasket on a substrate with a central through hole, followed by a dielectric layer covering the substrate, where the dielectric layer is etched to form an etching hole communicating with the central through hole, guiding the etching hole to the correct position and preventing side etching and electrical leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high aspect ratio etching through hole is formed in the dielectric layer, then the contact plug structure can be formed to enable interconnection between metal layers, but through hole offset and poor contact occur
Solution Approach 1:
The patent divides the through hole formation into two separate stages: first forming a guide hole through the dielectric layer, then forming the final contact hole. This segmentation allows the guide hole to provide positioning accuracy while the second etching step creates the proper contact geometry, resolving the contradiction between positioning precision and contact quality.
Solution Approach 2:
The patent introduces a mandrel structure as an intermediary element during the etching process. The mandrel serves as a temporary guide that defines the through hole position and shape, enabling precise positioning while maintaining contact integrity. After etching, the mandrel is removed, leaving the properly formed contact hole.
2Length of moving object
If the etching depth is increased to expose the target metal layer, then the contact plug can be formed, but over etching occurs leading to electrical leakage
Solution Approach 1:
The patent performs preliminary actions by forming the guide hole and mandrel structure before the final etching step. The mandrel is positioned to extend slightly below the dielectric layer surface, providing a stop point that prevents over-etching. This preliminary structuring ensures the etching depth is controlled to expose the metal layer without causing electrical leakage.
3Length of stationary object
If the aspect ratio of the etching through hole is increased to reach deeper metal layers, then multi-layer interconnection is enabled, but through hole offset and poor contact occur
Solution Approach 1:
The patent segments the deep hole formation into a guide hole creation step followed by a controlled etching step. The guide hole provides a template for positioning, while the subsequent etching using the mandrel as a stopper achieves the required depth without losing positioning accuracy, even for high aspect ratio structures.
Solution Approach 2:
The mandrel structure acts as an intermediary that maintains positioning accuracy throughout the etching process. By providing a physical reference and stop point, the mandrel ensures that even as the hole depth increases to create high aspect ratio structures, the positioning accuracy is preserved and offset is prevented.
Data Source
AI summary
A forming method for an opening structure includes: a substrate is provided, where a target layer is formed in the substrate, and the substrate exposes a surface of the target layer; an annular gasket is formed on the surface of the target layer, where a central through hole exposing a part of the surface of the target layer is provided in a center of the annular gasket; a dielectric layer covering the substrate, the target layer and the annular gasket is formed; and the dielectric layer is etched to form an etching hole communicating with the central through hole in the dielectric layer, where the etching hole and the central through hole form an opening structure.