Directed Self-Assembly of Block Copolymers for Sub-22 nm Via Uniformity
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Solution Overview
Problem
Conventional optical lithography struggles to achieve uniformity and precision in forming vias with critical dimensions below 22 nm, leading to significant variations and limitations in semiconductor device manufacturing.
Innovation Solution
The use of directed self-assembly of block copolymers on substrates with pre-defined openings, where the block copolymers phase-separate into self-assembled domains, which are then selectively removed to form holes with reduced critical dimension variations, enabling the creation of more uniform vias that can be transferred into the underlying substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical lithography is used to form vias with critical dimensions below 22 nm, then the manufacturing process can be maintained with existing tools, but the critical dimension uniformity deteriorates significantly
Solution Approach 1:
The block copolymer system performs self-assembly to automatically form uniform micellar structures within the openings. The amphiphilic blocks spontaneously organize into core-shell micelles with uniform dimensions, eliminating the need for external intervention to achieve critical dimension uniformity. This self-service mechanism directly addresses the lithography resolution limit by allowing the material itself to define the precise via dimensions.
Solution Approach 2:
The invention changes the physical and chemical parameters of the system by introducing block copolymers with specific block ratios and molecular weights. By adjusting these parameters, the micelle size and distribution can be controlled to achieve the desired critical dimension uniformity. The phase separation behavior and self-assembly characteristics are tuned through parameter optimization to resolve the contradiction between existing tool capabilities and the need for higher precision.
2Productivity
If the size of initial openings is reduced to achieve tighter pitch vias, then the via density increases, but the variation in critical dimensions increases
Solution Approach 1:
The block copolymer micelles serve as self-defined templates that automatically establish uniform via dimensions regardless of the initial opening size variations. The self-assembly process inherently corrects for opening size variations by forming micelles with consistent core dimensions, thereby maintaining critical dimension uniformity while enabling tighter pitch and higher via density.
Solution Approach 2:
The invention applies local quality control by allowing the block copolymer to form micelles with specific local structures within each opening. The core-shell morphology provides localized order and uniformity within each via location, ensuring that each via achieves the target critical dimension independently of variations in the initial opening pattern.
3Manufacturing precision
If block copolymers are used to form self-assembled domains, then the critical dimension uniformity improves, but the process complexity increases
Solution Approach 1:
The block copolymer system performs self-assembly to automatically form uniform micellar structures within the openings. The amphiphilic blocks spontaneously organize into core-shell micelles with uniform dimensions, eliminating the need for external intervention to achieve critical dimension uniformity. This self-service mechanism directly addresses the lithography resolution limit by allowing the material itself to define the precise via dimensions.
Solution Approach 2:
The invention changes the physical and chemical parameters of the system by introducing block copolymers with specific block ratios and molecular weights. By adjusting these parameters, the micelle size and distribution can be controlled to achieve the desired critical dimension uniformity. The phase separation behavior and self-assembly characteristics are tuned through parameter optimization to resolve the contradiction between existing tool capabilities and the need for higher 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
This method significantly reduces the percentage variation in the critical dimensions of the formed holes compared to the initial openings, allowing for the production of vias with improved uniformity and reduced process variability, even at tight pitches, thereby extending the resolution limits of current lithography techniques.
Implementation Method 1
Under the right conditions, the blocks of such copolymers phase separate into microdomains (also known as 'microphase-separated domains' or 'domains') to reduce the total free energy, and in the process, nanoscale features of dissimilar chemical composition are formed.
Implementation Method 2
the blocks of such copolymers phase separate into microdomains to reduce the total free energy
Data Source
AI summary
Methods involving the self-assembly of block copolymers are described herein, in which by beginning with openings (in one or more substrates) that have a targeted CD (critical dimension), holes are formed, in either regular arrays or arbitrary arrangements. Significantly, the percentage variation in the average diameter of the formed holes is less than the percentage variation of the average diameter of the initial openings. The formed holes (or vias) can be transferred into the underlying substrate(s), and these holes may then be backfilled with material, such as a metallic conductor. Preferred aspects of the invention enable the creation of vias with tighter pitch and better CD uniformity, even at sub-22 nm technology nodes.