Semiconductor Contact Plug and Line Leakage Prevention
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Solution Overview
Problem
As semiconductor devices become more integrated, the overlay margin between metal lines and contact plugs decreases, leading to misalignment and increased likelihood of leakage current and unwanted capacitance between adjacent conductive layers.
Innovation Solution
The semiconductor device design includes a first interlayer insulating layer, an etch stop layer, contact holes with contact plugs having a top surface lower than the etch stop layer, and line trenches where lines are formed to couple with the contact plugs, ensuring a critical distance to prevent leakage current and reducing capacitance by forming air gaps between lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cell area is decreased to increase degree of integration, then productivity is improved, but overlay margin between metal line and contact plug becomes smaller leading to misalignment and leakage current
Solution Approach 1:
The patent introduces a vertical height dimension by forming the contact plug top surface lower than the first interlayer insulating layer top surface. This dimensional change creates additional spacing in the vertical direction, preventing leakage current while maintaining horizontal integration density.
Solution Approach 2:
The patent introduces a second interlayer insulating layer as an intermediary substance between the contact plug and the metal line. This intermediate layer provides electrical isolation and prevents direct contact that would cause leakage current, while still allowing the metal line to be formed at the required position.
2Area of stationary object
If distance between contact plug and metal line is decreased due to misalignment, then area is reduced, but leakage current occurs between adjacent conductive layers
Solution Approach 1:
The patent compensates for horizontal distance reduction by creating vertical separation. The contact plug top surface is positioned lower than the first interlayer insulating layer, and the metal line is formed on top of it, creating a vertical stack that prevents lateral leakage while allowing compact horizontal spacing.
Solution Approach 2:
The second interlayer insulating layer serves as a mediator that fills the space between the contact plug and metal line. This intermediate material provides electrical isolation, preventing leakage current even when the horizontal distance between contact plug and metal line is minimized due to overlay misalignment.
3Area of stationary object
If distance between adjacent metal lines is decreased, then area is reduced, but unwanted capacitance between metal lines increases
Solution Approach 1:
The patent applies different dielectric properties to different regions. The second interlayer insulating layer is positioned specifically between adjacent metal lines to provide electrical isolation and reduce capacitance, while allowing the metal lines to be closely spaced for high density. This local modification of dielectric quality reduces capacitance without sacrificing overall integration density.
Data Source
AI summary
A semiconductor device and methods directed toward preventing a leakage current between a contact plug and a line adjacent to the contact plug, and minimizing capacitance between adjacent lines.