Semiconductor Device Metal Bump Via Plug Alignment
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Solution Overview
Problem
In semiconductor devices, particularly three-dimensional memories, positioning plugs and interconnections is challenging, leading to shorts and aging deterioration due to the difficulty in accurately forming plugs on thin interconnections with narrow spacing.
Innovation Solution
The solution involves forming a metal bump protruded upward from a stopper insulator on a first interconnection, with a via plug positioned above the bump, allowing for longer contact distance and reduced risk of shorts, even with low lithography accuracy, and enabling further integration and reduced electrostatic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If interconnections are thinned to improve integration, then device integration is improved, but positioning accuracy of plugs and interconnections deteriorates leading to shorts
Solution Approach 1:
A metal bump is introduced as an intermediary structure between the via plug and the thin interconnection. The metal bump protrudes upward from the stopper insulator and provides a larger target area for via plug formation, making positioning easier even when interconnections are thin. This intermediary structure resolves the contradiction by enabling accurate plug positioning on thinned interconnections without requiring high lithography precision.
Solution Approach 2:
The invention transitions from a planar connection structure to a three-dimensional structure by forming a metal bump that protrudes upward from the stopper insulator. This vertical dimension provides additional space and a larger surface area for via plug formation, allowing plugs to be positioned accurately on thin interconnections even with low lithography accuracy, thus resolving the positioning difficulty caused by interconnection thinning.
2Length of moving object
If plugs are formed directly on thin interconnections, then interconnection length is reduced, but shorts between plug and other interconnections easily occur
Solution Approach 1:
The metal bump acts as a mediator between the via plug and the thin interconnection. By providing a protruding structure that extends upward from the stopper insulator, it creates a larger positioning target that is easier to align with, reducing the risk of misalignment and shorts while still maintaining the shortened interconnection length benefit.
Solution Approach 2:
The metal bump protruding structure serves as a cushioning measure beforehand, creating a safety margin for positioning errors. The larger vertical profile of the metal bump provides a buffer zone that compensates for potential lithography inaccuracies, preventing shorts before they can occur during the via plug formation process.
3Manufacturing precision
If lithography precision is increased to improve plug positioning, then positioning accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The metal bump intermediary structure enlarges the effective target area for via plug formation. This protruding structure provides a larger vertical profile that is easier to locate and align with using lower precision lithography processes, thereby achieving accurate plug positioning without requiring expensive high-precision lithography equipment or processes.
Data Source
AI summary
In one embodiment, a semiconductor device includes a first insulator, a plurality of interconnections provided in the first insulator. The device further includes a second insulator provided on the first insulator and the plurality of interconnections, and a conductor provided on a first interconnection among the plurality of interconnections and having a shape that is projected upwardly with respect to the first interconnection in the second insulator. The device further includes a plug provided on the first interconnection via the conductor. The device further includes a first pad provided above the plug and electrically connected to the plug, and a second pad provided on the first pad and electrically connected to the first pad.