Self-Aligned Interconnect Via Structure for Leakage Reduction
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Solution Overview
Problem
Existing interconnect structures in integrated circuits suffer from misalignment issues between contact vias and metal lines, leading to increased leakage and resistivity, particularly in advanced IC generations with smaller geometries.
Innovation Solution
A method involving a layer stack with a first metal layer, conductive etch stop layer, and second metal layer, using reactive ion etching to form self-aligned conductive line features and contact vias with perpendicular sidewalls, ensuring precise alignment and reducing leakage by eliminating 'tiger teeth' formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional interconnect structures are used with metal lines and contact vias, then the basic interconnection function is achieved, but misalignment between contact vias and metal lines occurs leading to increased leakage and resistivity
Solution Approach 1:
The patent applies preliminary action by forming a mandrel structure before the contact via formation that defines the precise location where the via will be etched. This mandrel is positioned in advance to ensure the via will be self-aligned with the metal line, preventing misalignment issues that cause leakage and resistivity problems in conventional structures.
Solution Approach 2:
The patent introduces a mandrel structure as an intermediary element that mediates between the metal line and the contact via. This mandrel serves as a template or guide that ensures precise alignment during the via formation process, eliminating the direct alignment problem between via and metal line that plagues conventional interconnect structures.
2Productivity
If geometry size is decreased to increase functional density, then production efficiency increases and costs are lowered, but misalignment issues between contact vias and metal lines become more severe
Solution Approach 1:
By forming the mandrel structure in advance at the precise location where the contact via needs to be formed, the patent ensures that even as geometry sizes decrease and functional density increases, the alignment between via and metal line is maintained through this pre-positioned template structure.
Solution Approach 2:
The mandrel structure serves as a self-aligning feature where the via is etched to conform to the mandrel's position and shape. This self-service mechanism automatically ensures alignment without requiring additional alignment steps or processes, which is critical when scaling to smaller geometries where traditional alignment methods become insufficient.
3Ease of manufacture
If contact vias are formed without self-alignment features, then the fabrication process is simpler, but leakage and resistivity increase due to misalignment
Solution Approach 1:
The mandrel structure acts as an intermediary that simplifies the fabrication process while simultaneously ensuring proper alignment. Rather than requiring complex multi-step alignment procedures, the mandrel provides a single reference feature that guides via formation, making the process easier while preventing leakage and resistivity issues.
Solution Approach 2:
The patent replaces complex mechanical alignment systems with a simpler chemical/physical approach where the via is formed to conform to the mandrel structure. This substitution eliminates the need for precise mechanical positioning and alignment steps, simplifying fabrication while ensuring reliable alignment through the mandrel's presence.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves reduced leakage and higher pattern density by ensuring self-alignment of contact vias with metal lines, improving device performance and suitability for fabricating small conductive features.
Implementation Method 1
using reactive ion etching to form self-aligned conductive line features and contact vias with perpendicular sidewalls
Data Source
AI summary
Interconnect structures and methods of forming the same are provided. An interconnect structure according to the present disclosure includes a conductive line feature over a substrate, a conductive etch stop layer over the conductive line feature, a contact via over the conductive etch stop layer, and a barrier layer disposed along a sidewall of the conductive line feature, a sidewall of the conductive etch stop layer, and a sidewall of the contact via.