Self-Crosslinkable Polymer Gap-Fill for High Aspect Ratio Trenches
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Solution Overview
Problem
Conventional shallow trench isolation methods struggle to fill high aspect ratio gaps in semiconductor devices effectively, leading to voids and poor electrical isolation due to current leakage between adjacent devices as they approach sub-20 nanometer geometries.
Innovation Solution
A gap-fill method using a self-crosslinkable polymer composition comprising a polymerized backbone with crosslinkable groups, which self-crosslinks upon heating without the need for additional catalysts, minimizing void formation and defects by controlling molecular weight and polydispersity index, and including solvents and optional additives for improved filling of narrow gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional STI approach is used to fill trenches, then the process is simple and well-established, but high aspect ratio gaps cannot be filled effectively leading to voids and poor electrical isolation
Solution Approach 1:
The patent changes the physical and chemical parameters of the gap-fill material by using a polymer composition with controlled molecular weight (1,000-100,000 g/mol) and polydispersity index (1.05-2.0), along with specific solvents and crosslinking agents. These parameter changes enable the material to flow into high aspect ratio gaps and then solidify through crosslinking, achieving complete filling without voids while maintaining a manageable process
Solution Approach 2:
The patent employs a composite gap-fill composition consisting of polymer (e.g., polycycloolefin, polyethylene), solvent (e.g., toluene, xylene), and crosslinking agent (e.g., peroxide). This composite material combines the flow properties of the polymer-solvent mixture with the structural integrity provided by crosslinking, enabling effective filling of high aspect ratio gaps that conventional single-material approaches cannot achieve
2Productivity
If devices are packed with smaller spacing to increase integration density, then more devices can be fabricated on a substrate, but current leakage between adjacent transistors increases
Solution Approach 1:
The patent uses a consumable polymer-based gap-fill composition that is applied as a liquid or paste, flows into the trenches, and then transforms into a permanent dielectric barrier. The temporary liquid state enables infiltration into narrow gaps, while the final crosslinked solid state provides lasting electrical isolation, effectively resolving the current leakage issue enabled by high integration density
Solution Approach 2:
The gap-fill composition undergoes phase transition from liquid (during application and filling) to solid (through crosslinking and curing). This phase change allows the material to easily penetrate high aspect ratio gaps in liquid form and then lock in place as a solid dielectric barrier, ensuring complete filling and effective electrical isolation between closely spaced devices
3Reliability
If high aspect ratio trenches are filled with conventional dielectric material, then the isolation structure is formed, but voids are created leading to poor electrical isolation
Solution Approach 1:
The patent optimizes the molecular weight (1,000-100,000 g/mol) and polydispersity index (1.05-2.0) of the polymer to achieve the right balance between flowability and structural integrity. The controlled parameters allow the material to uniformly fill high aspect ratio gaps without void formation, ensuring both complete penetration and even distribution throughout the trench structure
Solution Approach 2:
The gap-fill composition is designed to self-crosslink through the use of peroxide crosslinking agents that activate upon contact with moisture or heat. This self-crosslinking mechanism eliminates the need for complex external curing processes and ensures uniform solidification throughout the filled gaps, preventing void formation and achieving consistent electrical isolation
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
The method effectively fills high aspect ratio gaps, reducing voids and current leakage, thereby enhancing electrical isolation and device performance by ensuring complete filling and uniform crosslinking of the polymer within the semiconductor substrate.
Implementation Method 1
heating the gap-fill composition at a temperature to cause the polymer to self-crosslink
Data Source
AI summary
Provided are gap-fill methods. The methods comprise: (a) providing a semiconductor substrate having a relief image on a surface of the substrate, the relief image comprising a plurality of gaps to be filled; (b) applying a gap-fill composition over the relief image, wherein the gap-fill composition comprises a self-crosslinkable polymer and a solvent, wherein the self-crosslinkable polymer comprises a first unit comprising a polymerized backbone and a crosslinkable group pendant to the backbone; and (c) heating the gap-fill composition at a temperature to cause the polymer to self-crosslink. The methods find particular applicability in the manufacture of semiconductor devices for the filling of high aspect ratio gaps.