Contact Plug Structure for High-Aspect-Ratio Hole Alignment
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to increased aspect ratios of contact holes, resulting in mis-alignment and incomplete opening of contact holes during the etching process, which deteriorates the electrical characteristics of semiconductor devices.
Innovation Solution
A semiconductor device is fabricated with a pad formed at the bottom of the contact hole, a plug liner conformally covering the sidewall of the contact hole, and a contact plug formed over the pad inside the contact hole, enhancing the electrical characteristics and fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of contact plugs is reduced to achieve miniaturization, then the degree of integration is improved, but the aspect ratio of contact holes increases causing mis-alignment and incomplete opening
Solution Approach 1:
A pad structure is formed at the bottom of the contact hole before the contact plug is deposited. This preliminary structure provides a foundation that ensures complete opening and proper alignment of the contact hole, preventing defects that would otherwise occur with high aspect ratios.
Solution Approach 2:
A liner structure is formed on the sidewall of the contact hole as an intermediary element between the pad and the contact plug. This liner acts as a mediator that maintains structural integrity during the high-aspect-ratio etching process and ensures precise alignment.
2Productivity
If the aspect ratio of contact holes is increased due to miniaturization, then the integration density is improved, but mis-alignment and incomplete opening occur during etching
Solution Approach 1:
The pad is formed at the bottom of the contact hole before etching, establishing a reference point that guides the etching process and ensures complete opening even at high aspect ratios.
Solution Approach 2:
The liner on the sidewall serves as an intermediary structure that maintains alignment during etching by providing structural support and defining the contact hole boundaries throughout the high-aspect-ratio formation process.
3Length of moving object
If conventional contact plug fabrication is used with high aspect ratios, then miniaturization is achieved, but electrical characteristics deteriorate due to defects
Solution Approach 1:
The pad structure is formed in advance at the bottom of the contact hole, ensuring proper electrical contact and preventing defects that would compromise electrical characteristics.
Solution Approach 2:
The liner structure acts as an intermediary that ensures structural integrity and proper electrical connection between the pad and contact plug, maintaining reliable electrical characteristics despite high aspect ratios.
Data Source
AI summary
A semiconductor device including: a semiconductor substrate including an active region; a plurality of conductive structures formed over the semiconductor substrate; an isolation layer filling a space between the conductive structures and having an opening that exposes the active region between the conductive structures; a pad formed in a bottom portion of the opening and in contact with the active region; a plug liner formed conformally over a sidewall of the opening and exposing the pad; and a contact plug formed over the pad inside the opening.