Contact Window Structure Using Spacer-Guided Etching
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Solution Overview
Problem
The formation of high-aspect-ratio contact window structures in semiconductor devices often results in issues such as incomplete exposure of the target metal layer, over-etching, or breakdown due to the challenges in the etching process, particularly with high aspect ratio through holes.
Innovation Solution
A method involving the formation of an etching spacer on the target layer, followed by a dielectric layer covering the substrate, where the dielectric layer is etched to form an etching hole exposing the spacer's top surface, and the spacer is removed to create an etching channel, which supports the formation of a contact window structure with reduced depth and prevents over-etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a through hole with high aspect ratio is etched in the dielectric layer, then the contact window structure can be formed, but the target metal layer may not be exposed or may be over-etched and broken down
Solution Approach 1:
The etching process is segmented into two distinct stages: first forming an etching hole through the dielectric layer to expose the etching spacer, then removing the etching spacer to form the final contact window. This segmentation allows control over the etching depth and prevents over-etching of the target metal layer.
Solution Approach 2:
An etching spacer is formed on the target metal layer before etching the dielectric layer. This preliminary action creates a protective barrier that prevents direct contact between the etching process and the target metal layer, thereby preventing over-etching and breakdown while still allowing the contact window to be formed.
2Manufacturing precision
If the through hole dimension at the top is increased to ensure target metal layer exposure, then the target metal layer can be exposed, but the target metal layer may be over-etched or broken down
Solution Approach 1:
The etching spacer serves as an intermediary layer between the etching hole and the target metal layer. It allows the etching hole to have a larger top dimension for proper alignment and exposure while protecting the target metal layer from direct etching damage, thus preventing over-etching and breakdown.
3Area of stationary object
If the aspect ratio of the through hole is increased to reduce contact area, then the contact window structure can be formed, but the etching difficulty increases
Solution Approach 1:
The contact window formation is segmented into forming an etching hole first, then removing the etching spacer. This allows the etching hole to be optimized for etchability rather than minimizing contact area, reducing etching difficulty while the final contact area is controlled by the etching spacer dimensions.
Data Source
AI summary
A contact window structure and a method for forming the contact window structure are provided. The method includes: an etching spacer is formed on a surface of a target layer, and a dielectric layer covering a substrate, the target layer and the etching spacer is formed; the dielectric layer is etched to form an etching hole in the dielectric layer, a bottom of the etching hole exposing a top surface of the etching spacer; and the etching spacer is removed along the etching hole to form an etching channel communicating with the etching hole, the etching channel exposing a portion of the surface of the target layer and constituting a contact window structure with the etching hole.