Polymerizable SAMs for Area-Selective ALD Masking
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Solution Overview
Problem
Current self-assembled monolayers (SAMs) used in area-selective atomic layer deposition (AS-ALD) lack sufficient area selectivity, leading to unwanted deposition in masked regions and potential defects during semiconductor device fabrication, especially when dealing with high aspect ratio features and small critical dimensions.
Innovation Solution
The use of polymerizable self-assembled monolayers with specific compounds that form a crosslinked layer on the substrate surface, resistant to ALD precursor deposition, allowing for selective patterning and extended ALD cycle duration without unwanted deposition in masked areas, achieved through exposure to radiation for polymerization and subsequent selective removal of non-exposed SAM regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional self-assembled monolayers are used to block ALD deposition, then area selectivity is provided, but unwanted deposition occurs in masked regions after a limited number of ALD cycles
Solution Approach 1:
The patent changes the chemical and physical parameters of the SAM by incorporating polymerizable functional groups (such as vinyl, epoxide, or isocyanate groups) into the monolayer structure. After formation, the SAM is exposed to radiation or chemical agents that induce polymerization, transforming the monolayer from a simple adsorbed layer into a crosslinked polymeric network. This parameter change dramatically increases the SAM's resistance to ALD precursor deposition, allowing it to maintain area selectivity through hundreds or thousands of ALD cycles without unwanted deposition in masked regions.
2Reliability
If SAM thickness is increased to improve blocking capability, then area selectivity improves, but critical dimension control and pattern precision deteriorate
Solution Approach 1:
The patent transforms the physical state and density of the SAM through polymerization. The crosslinked polymeric network creates a denser, more uniform blocking layer with consistent thickness at the molecular level. This parameter change provides superior blocking capability compared to thicker conventional SAMs, while maintaining precise critical dimensions because the polymerization occurs in-situ within the self-assembled monolayer structure, preserving the original pattern fidelity and surface morphology.
3Manufacturing precision
If multiple ALD cycles are performed to achieve desired film thickness, then coating quality improves, but unwanted deposition in masked regions increases
Solution Approach 1:
The patent creates a composite structure by integrating polymerizable functional groups into the SAM architecture. The resulting material combines the self-assembly and selective adsorption properties of conventional SAMs with the enhanced barrier properties of crosslinked polymers. This composite material provides exceptional resistance to ALD precursor penetration, enabling hundreds or thousands of deposition cycles to be performed on unmasked regions without any unwanted deposition occurring in masked regions, thereby maintaining coating quality while eliminating harmful side effects.
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 enhances the number of ALD cycles before unwanted deposition occurs in masked regions, minimizing defects and enabling the creation of patterns with smaller critical dimensions and improved uniformity, thus improving the precision and reliability of semiconductor fabrication.
Implementation Method 1
H′ is a head group comprising a functional group capable of binding to said portion of the surface by electrostatic interactions and/or a covalent bond
Implementation Method 2
H′ is a head group comprising a functional group capable of binding to said portion of the surface by electrostatic interactions and/or a covalent bond
Implementation Method 3
exposing the SAM to a radiation, thereby forming a polymerized SAM
Data Source
AI summary
Self-assembled monolayers (SAMs) were selectively prepared on portions of a substrate surface utilizing compounds comprising a hydrogen-bonding group and polymerizable diacetylene group. The SAMs were photopolymerized using ultraviolet light. The pre-polymerized and polymerized SAMs were more effective barriers against metal deposition in an atomic layer deposition process compared to similar compounds lacking these functional groups.