Semiconductor Alignment Mark Formation via Block Copolymer Segmentation
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Solution Overview
Problem
Conventional methods for forming alignment marks using directed self-assembly of block copolymers often result in unexpected minute structures, which can compromise overlay accuracy between layers in semiconductor devices, as these marks can be difficult to detect due to self-assembly effects.
Innovation Solution
A method involving the formation of an intermediate layer on a substrate, followed by exposing an image of a first mark to create a second mark with recessed portions, and applying a polymer layer containing block copolymers, allowing for selective removal and self-assembly in specific areas to form precise alignment marks alongside circuit patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If directed self-assembly of block copolymer is used to form circuit patterns, then circuit pattern resolution beyond lithography limits is achieved, but unexpected minute structures are formed in alignment marks making them difficult to detect
Solution Approach 1:
The substrate surface is divided into distinct functional zones: a mark formation area where alignment marks are created using conventional lithography without block copolymer application, and a circuit pattern formation area where block copolymer self-assembly is applied. This spatial segmentation prevents the block copolymer from interfering with alignment mark formation while still enabling super-resolution circuit patterning in other regions.
Solution Approach 2:
Different surface treatments and material properties are applied to different regions of the substrate. The mark formation area receives a conventional photoresist coating and standard lithography processing, while the circuit pattern area receives the block copolymer layer for self-assembly. This local differentiation ensures that alignment marks maintain their detectability while circuit patterns achieve enhanced resolution.
2Productivity
If block copolymer self-assembly is applied across the entire substrate, then circuit patterns are formed, but alignment marks lose their expected structure and become undetectable
Solution Approach 1:
The substrate is segmented into a mark formation area and a circuit pattern formation area. The block copolymer is applied only to the circuit pattern formation area, excluding the mark formation area. This ensures that alignment marks are formed with conventional methods maintaining their detectability and reliability, while circuit patterns benefit from block copolymer self-assembly for enhanced productivity.
Solution Approach 2:
A mask layer or masking strategy is used as an intermediary to prevent block copolymer deposition or self-assembly in the mark formation area. This intermediary protects the alignment mark regions from the block copolymer process while allowing the rest of the substrate to undergo self-assembly, thus maintaining both overlay accuracy and production capability.
3Loss of time
If alignment marks are formed using conventional methods in the presence of block copolymer, then marks are formed quickly, but unexpected minute structures are created that compromise mark quality
Solution Approach 1:
The substrate is divided into a mark formation area where conventional lithography is used and a circuit pattern area where block copolymer self-assembly is applied. By spatially separating these processes, alignment marks are formed quickly using conventional methods without the presence of block copolymer, ensuring high mark quality while still benefiting from rapid processing.
Solution Approach 2:
The mark formation area is prepared in advance by applying a conventional photoresist layer before the block copolymer is applied to the circuit pattern area. This preliminary preparation ensures that alignment marks are formed using optimized conventional processes, maintaining their quality while the block copolymer process proceeds separately in other regions.
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 precise alignment marks that can be detected with high accuracy, ensuring improved overlay precision between layers in semiconductor devices, even when forming circuit patterns beyond the resolution limit of conventional lithography.
Implementation Method 1
the directed self-assembly (directed self-organization) of a block copolymer between patterns formed by using the lithography step so as to generate a minute structure of nano-scale
Implementation Method 2
forming, on a processing target layer of a substrate, an intermediate layer to which a polymer layer containing a block copolymer is adherable
Data Source
AI summary
A mark forming method includes: a step of forming, on a device layer of a wafer, an intermediate layer to which a polymer layer containing a block copolymer is adherable, the device layer including a shot area and a scribe line area; a step of removing a portion, of the intermediate layer, formed in the scribe line area; a step of exposing an image of a mark on the scribe line area and forming, based on the image of the mark, a mark including recessed portion; and a step of applying the polymer layer containing the block copolymer on the device layer of the wafer. When a circuit pattern is formed by using the self-assembly of the block copolymer, it is possible to form the mark simultaneously with the formation of the circuit pattern.