Directed Self-Assembly Neutral Layer for Block Copolymer Defect Control
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Solution Overview
Problem
In semiconductor manufacturing, existing graphoepitaxy directed self-assembly (DSA) methods face challenges in controlling the self-assembly patterns of block copolymers due to issues with sidewall and bottom surface preferences, which can lead to limited use in semiconductor device manufacturing, particularly with the presence of resist residues and plasma etching damage.
Innovation Solution
The method involves forming oxide spacers and neutral polymeric layers within semiconductor cavities, followed by selective etching and solvent rinsing to create a controlled environment for block copolymer self-assembly, ensuring the desired lamellar patterns of PMMA and PS are achieved without defects, by making sidewalls and bottoms neutral or preferential to specific polymer species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing graphoepitaxy directed self-assembly methods are used to control block copolymer self-assembly, then pattern formation is achieved, but sidewall and bottom surface preferences cause defects and limited reliability in semiconductor device manufacturing
Solution Approach 1:
The patent introduces an intermediary neutral layer between the cavity surfaces and the block copolymer. This neutral layer mediates the interaction by preventing direct preferential adsorption of polymer species to the sidewalls and bottom, thereby eliminating the harmful surface preferences that cause defects in self-assembly patterns.
Solution Approach 2:
The patent employs a sacrificial oxide spacer that is temporarily formed to define the cavity structure, then selectively removed to expose the neutral layer. This disposable oxide spacer enables precise control of the neutral layer positioning without requiring permanent structural components.
2Manufacturing precision
If oxide spacers are formed along sidewalls to define cavities, then cavity structure is established, but oxide spacers must be removed to expose neutral layer, adding process complexity
Solution Approach 1:
The oxide spacer is formed in advance as a preliminary structure to define the cavity geometry and position the neutral layer. This preliminary action enables precise cavity definition before the actual self-assembly process, with the spacer serving its purpose and then being removed.
Solution Approach 2:
The patent segments the structure formation into distinct functional layers: the oxide spacer for structural definition, the neutral layer for surface preference control, and the block copolymer for pattern formation. This segmentation allows each component to be optimized and processed independently.
3Reliability
If neutral layer is formed along sidewalls and bottom, then surface preferences are controlled, but selective removal of sacrificial material requires precise etching control
Solution Approach 1:
The patent applies local quality by making different regions of the cavity have different surface properties through the neutral layer. The neutral layer is selectively positioned along sidewalls and bottom surfaces with specific thicknesses, creating locally optimized conditions for controlling block copolymer self-assembly in different 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 allows for precise control over block copolymer self-assembly patterns, reducing defects and improving the orientation of PMMA and PS columns, enhancing the efficiency and reliability of semiconductor manufacturing processes.
Implementation Method 1
depositing a neutral polymeric material within a cavity in a semiconductor material
Implementation Method 2
removing the oxide spacers to expose the first and second sidewalls and a portion of the bottom of the cavity adjacent the first and second sidewalls
Implementation Method 3
Graphoepitaxy directed self-assembly (DSA) employs a topographical guiding pattern to direct the self-assembly of block copolymers (BCPs)
Data Source
AI summary
The disclosure provides methods for directed self-assembly (DSA) of a block co-polymer (BCP). In one embodiment, a method includes: forming an oxide spacer along each of a first sidewall and a second sidewall of a cavity in a semiconductor substrate; forming a neutral layer between the oxide spacers and along a bottom of the cavity; and removing the oxide spacers to expose the first and second sidewalls and a portion of the bottom of the cavity adjacent the first and second sidewalls.