Interconnect Via Structure With Dielectric Spacer Alignment
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Solution Overview
Problem
In advanced semiconductor technology, misalignments between metal lines and vias in interconnect structures become more critical as feature sizes shrink, leading to issues like shorts and reliability problems due to the limitations of current lithography processes and materials used in dual damascene processes.
Innovation Solution
The implementation of a dielectric spacer layer formed using atomic layer deposition between the vias and conductive elements, which helps in reducing misalignment and enhancing device reliability by limiting electron migration and time-dependent dielectric breakdown, and the use of nitrogen-free anti-reflection layers to prevent photoresist poisoning during lithographic processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes are shrunk to advance semiconductor technology, then device integration and performance are improved, but misalignment between metal lines and vias becomes more critical leading to shorts and reliability problems
Solution Approach 1:
A dielectric spacer layer is introduced as an intermediary component between the metal line and the via structure. This spacer layer, formed by atomic layer deposition (ALD), provides physical separation and alignment reference, enabling precise positioning of the via relative to the metal line without direct contact. The spacer acts as a mediator that resolves the alignment conflict between shrinking feature sizes and maintaining manufacturing precision.
Solution Approach 2:
The dielectric spacer layer is formed in advance before the via etching and filling processes. By establishing the spacer layer first, the via opening position is pre-determined and protected from misalignment during subsequent processing steps. This preliminary action ensures that even as feature sizes shrink, the via maintains correct alignment with the metal line throughout manufacturing.
2Ease of manufacture
If dual damascene processes are used to form interconnect structures, then manufacturing capability is maintained, but misalignment and reliability issues arise due to process limitations
Solution Approach 1:
The dielectric spacer layer serves as a mediator between the first and second dielectric layers in the dual damascene process. It provides a stable reference structure that prevents misalignment between the via opening and the underlying metal line, thereby improving reliability while maintaining the manufacturing capability of the dual damascene process.
Solution Approach 2:
The patent replaces reliance on purely mechanical/lithographic alignment with a chemically-formed dielectric spacer structure. The atomic layer deposition process creates a conformal spacer that physically defines the via position, substituting the need for perfect lithographic alignment with a more reliable spacer-based positioning mechanism.
3Device complexity
If conventional lithographic processes are used, then manufacturing simplicity is maintained, but photoresist poisoning occurs leading to inaccurate pattern replication
Solution Approach 1:
Nitrogen is extracted or removed from the anti-reflection coating composition to prevent photoresist poisoning. The nitrogen-free anti-reflection coating maintains its light-absorbing function while eliminating the harmful nitrogen component that causes pattern replication errors, thereby preserving manufacturing simplicity while improving precision.
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 dielectric spacer layer improves the alignment and reliability of interconnect structures by reducing electron migration and stress migration, while the nitrogen-free anti-reflection layer ensures accurate pattern replication, addressing the misalignment and reliability issues in advanced semiconductor technology.
Implementation Method 1
limiting electron migration and time-dependent dielectric breakdown
Implementation Method 2
formed using atomic layer deposition
Implementation Method 3
nitrogen-free anti-reflection layers to prevent photoresist poisoning during lithographic processes
Data Source
AI summary
A method includes providing a semiconductor structure including a dielectric layer having an opening exposing a top surface of a metal layer. A bottom via is selectively deposited in the opening and over the metal layer. A barrier layer is deposited over the bottom via and in contact with the dielectric layer at a sidewall of the opening. A top via is formed in the opening, in contact with the barrier layer, and over the bottom via. The top via is separated from the dielectric layer by the barrier layer.