Self-Aligned Metal Lines via Block Copolymer Etch Trim
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Solution Overview
Problem
Current methods for forming metal lines and vias in VLSI/ULSI circuits face challenges in aligning sub-40 nm pitch wiring due to limitations in metal wiring alignment with respect to underlying via patterns, hindering continued wire pitch scaling.
Innovation Solution
The use of self-assembling di-block copolymers, which are deposited on a patterned surface and selectively aligned with metal features, allowing for the formation of self-aligned metal lines and vias through directed self-assembly and subsequent conversion into metal using sequential infiltration synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metal wiring alignment methods are used, then existing fabrication processes can be maintained, but alignment precision deteriorates at sub-40 nm pitch
Solution Approach 1:
The block copolymer system performs self-alignment through spontaneous phase separation and self-assembly into ordered domains that automatically register with the underlying via pattern, eliminating the need for complex external alignment tools and processes while achieving sub-40 nm precision
Solution Approach 2:
The fabrication process is divided into distinct functional layers: the block copolymer forms self-assembled domains that serve as alignment templates, while the metal wiring is deposited separately and aligned to these templates, decoupling the alignment function from the metal deposition process itself
2Quantity of substance
If wire pitch is decreased to increase density, then wiring density improves, but alignment precision deteriorates
Solution Approach 1:
The block copolymer's self-assembled domain size is controlled by changing parameters such as polymer composition, molecular weight, and processing conditions, allowing the alignment template pitch to be scaled down to sub-40 nm while maintaining precise self-alignment capability
Solution Approach 2:
The block copolymer system inherently provides alignment functionality through its self-organizing behavior, where the micelle or lamellar structures spontaneously form with dimensions and orientations that directly define the metal wiring pattern, eliminating alignment errors that typically accompany pitch reduction
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
Enables the formation of dense, self-aligned metal lines down to 15 nm pitch aligned with underlying vias, overcoming alignment limitations and enhancing wiring density in VLSI/ULSI circuits.
Implementation Method 1
A self-assembled di-block copolymer material is deposited on a patterned surface of the neutral layer and the metal features. The self-assembled di-block copolymer material includes a first block composition with a first affinity for alignment to the metal features.
Implementation Method 2
The first block composition of the self-assembled di-block copolymer is converted to a metal that is self-aligned to the metal features.
Data Source
AI summary
A method of forming metal lines that are aligned to underlying metal features that includes forming a neutral layer atop a hardmask layer that is overlying a dielectric layer. The neutral layer is composed of a neutral charged di-block polymer. Patterning the neutral layer, the hardmask layer and the dielectric layer to provide openings that are filled with a metal material to provide metal features. A self-assembled di-block copolymer material is deposited on a patterned surface of the neutral layer and the metal features. The self-assembled di-block copolymer material includes a first block composition with a first affinity for alignment to the metal features. The first block composition of the self-assembled di-block copolymer is converted to a metal that is self-aligned to the metal features.