Self-Aligned Sub-Lithographic Patterning via Block Copolymer Assembly
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Solution Overview
Problem
Current lithographic tools cannot resolve contact openings below 100 nm in diameter, limiting device density in CMOS technology, and self-assembling block copolymers lack precise alignment for CMOS device applications.
Innovation Solution
Combining conventional lithography with self-assembling block copolymers to form self-aligned sub-lithographic features by creating a lithographically patterned mask layer, applying a block copolymer that separates into ordered nano-scale units, and selectively removing components to achieve precise placement of sub-lithographic structural units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography is used to form contact openings, then the contact opening diameter can be resolved down to 100 nm, but device density is limited due to the minimum feature size constraint
Solution Approach 1:
The patent divides the contact opening formation process into two stages: first forming a lithographic pattern (100 nm), then using block copolymer self-assembly to further subdivide each lithographic feature into multiple smaller contact openings (e.g., 4 contacts per via). This segmentation enables sub-lithographic feature sizes while maintaining alignment through the hierarchical structure.
Solution Approach 2:
The patent implements a nested structure where block copolymer-derived contact patterns are nested within lithographically-defined via openings. The self-assembled block copolymer structures (second level) are contained within the larger lithographic features (first level), creating a multi-scale hierarchical pattern that achieves sub-lithographic resolution while preserving alignment.
2Manufacturing precision
If self-assembling block copolymers are used to form nano-scale patterns, then sub-lithographic dimensions (10-40 nm) can be achieved, but precise alignment and registration for CMOS devices is lost
Solution Approach 1:
The patent applies preliminary lithographic patterning to define via openings and alignment markers before introducing the block copolymer. This pre-established lithographic framework serves as a reference structure that guides the subsequent self-assembly process, ensuring that the self-assembled contact patterns are precisely positioned relative to underlying CMOS device features.
Solution Approach 2:
The patent uses the lithographically patterned mask layer as an intermediary structure that mediates between the lithographic tool and the block copolymer self-assembly process. The mask layer with its defined via openings acts as a template that constrains and guides the block copolymer self-assembly, transferring alignment information from the lithographic scale to the nanoscale contact pattern.
3Ease of manufacture
If large ordered arrays of repeating structural units are formed by self-assembly, then material self-organization is achieved, but individual structural unit placement cannot be controlled for metal line and via formation
Solution Approach 1:
The patent applies local quality by creating different functional zones within the lithographic pattern: some regions contain alignment markers for registration, while other regions contain the via openings that template the contact formation. The block copolymer self-assembles differently in these zones, with alignment markers providing positional information and via openings defining contact locations, thereby achieving both self-organization and precise placement control.
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 sub-lithographic contact openings with precise alignment, increasing device density beyond conventional lithographic limitations, suitable for CMOS technology.
Implementation Method 1
certain materials are capable of spontaneous organization of materials into ordered patterns without the need for human interference, which is typically referred to as the self-assembly of materials
Implementation Method 2
Each self-assembling block copolymer system typically contains two or more different polymeric block components that are immiscible with one another. Under suitable conditions, the two or more immiscible polymeric block components separate into two or more different phases on a nanometer scale and thereby form ordered patterns of isolated nano-sized structural units
Implementation Method 3
annealing the block copolymer layer to form a single unit polymer block of a diameter w inside each of the mask openings
Data Source
AI summary
A method for conducting sub-lithography feature patterning of a device structure is provided. First, a lithographically patterned mask layer that contains one or more mask openings of a diameter d is formed by lithography and etching over an upper surface of the device structure. Next, a layer of a self-assembling block copolymer is applied over the lithographically patterned mask layer and then annealed to form a single unit polymer block of a diameter w inside each of the mask openings, provided that w<d. Each single unit polymer block of the present invention is embedded in a polymeric matrix and can be selectively removed against the polymeric matrix to form a single opening of the diameter w in the polymeric matrix inside each of the mask openings. Sub-lithography feature patterning can then be conducted in the device structure using the single openings of diameter w.