Self-Aligned Via Spacer Structure for Tight-Pitch Short Prevention
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Solution Overview
Problem
In semiconductor device fabrication, the formation of vias at small pitches leads to misalignment issues, which can result in electrical shorts and decreased efficiency due to the overlay and critical dimension tolerance between lines and vias, necessitating the use of self-aligned features and processes.
Innovation Solution
A method involving the etching of a via opening to remove lower level dielectric blocking material and depositing a spacer material in the via opening and self-aligned via cavity, followed by etching the spacer material to form a spacer region that prevents electrical connections between conductive lines, thereby correcting misalignment and ensuring insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vias are formed at small pitches, then device speed and efficiency increase, but misalignment issues cause electrical shorts and decreased reliability
Solution Approach 1:
The patent applies preliminary action by forming a spacer material around the via opening before completing the via formation process. This spacer acts as a protective structure that prevents misalignment-induced shorts, allowing small-pitch vias to be formed reliably. The spacer is deposited conformally on the etched dielectric surface and then planarized, creating a self-aligned structure that compensates for potential alignment errors in subsequent processing steps.
2Manufacturing precision
If overlay and critical dimension tolerance between line and via is reduced, then manufacturing precision improves, but process complexity increases due to additional self-aligned features
Solution Approach 1:
The patent employs self-service by creating a self-aligned via structure where the spacer material automatically positions itself around the via opening through conformal deposition. This self-aligned approach eliminates the need for separate alignment steps and reduces dependency on overlay precision between lithography steps. The spacer forms naturally on the etched dielectric surface, providing automatic compensation for alignment variations without requiring complex additional processing.
3Device complexity
If a single hard mask is used for patterning, then device complexity and process steps are reduced, but manufacturing precision may be compromised at tight pitches
Solution Approach 1:
The patent introduces an intermediary structure - the spacer material - that mediates between the single hard mask patterning and the final via structure. The spacer acts as a self-aligned mask that defines the via position and dimensions without requiring additional lithography steps. This intermediary structure enables tight-pitch via formation with a single hard mask while maintaining manufacturing precision, as the spacer's position is determined by the conformal deposition process rather than by additional alignment-critical lithography steps.
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
This approach enables the formation of semiconductor structures with improved insulation and reduced risk of electrical shorts, allowing for efficient patterning and metallization at tight pitches with a single hard mask, enhancing the overall speed and efficiency of semiconductor devices.
Implementation Method 1
etching a via opening in an upper level dielectric, etching in the via opening to remove lower level dielectric blocking material
Implementation Method 2
depositing a spacer material in the via opening, the self-aligned via cavity, and the spacer region
Data Source
AI summary
Embodiments disclosed herein describe semiconductor devices that include semiconductor structures and methods of forming the semiconductor structures. The semiconductor structures may include an upper conductive line, a first lower conductive line laterally insulated by a first lower dielectric region and a second lower dielectric region. The semiconductor structure also includes a lower level via region above the first lower conductive line. The lower level via region includes a dielectric blocking material and a spacer material.