Thermally Decomposable Gap-Fill Polymer for Clean Air Gap Formation
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Solution Overview
Problem
Traditional gap-fill materials in photolithography processes for semiconductor devices are not easily adaptable to generate air gaps due to issues like byproduct generation, outgassing, and incomplete removal, especially with high-temperature processes, limiting their effectiveness in multilayer patterning and pattern transfer.
Innovation Solution
A thermally decomposable gap-fill composition comprising a polymer with a crosslinkable monomer and a second monomer, specifically glycidyl methacrylate and methyl methacrylate, which is crosslinked and then heated to its thermal decomposition temperature for removal, allowing for complete filling of gaps and formation of air gaps without voids or residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional sacrificial gap-fill materials are used, then gaps can be filled during lithography processes, but byproduct generation and outgassing occur during removal processes
Solution Approach 1:
The patent changes the chemical composition parameters of the gap-fill material by using a polymer with controlled molecular weight (2,000-10,000 g/mol) and specific functional groups that enable clean thermal decomposition. This parameter optimization allows the material to decompose completely at high temperatures without generating harmful byproducts or excessive outgassing, resolving the contradiction between effective gap-filling and clean removal.
Solution Approach 2:
The patent utilizes phase transition by heating the gap-fill material to its thermal decomposition temperature, causing it to transition from a solid polymer state to gaseous decomposition products that can be completely removed. This phase transition approach enables clean removal without the byproduct generation issues associated with traditional wet or plasma etch processes.
2Reliability
If high-temperature thermal decomposition is used to remove gap-fill materials, then complete removal can be achieved, but outgassing products collect in bake units or exhaust lines
Solution Approach 1:
The patent optimizes the polymer's molecular weight and chemical structure parameters to ensure complete decomposition at high temperatures without excessive outgassing. The controlled molecular weight (2,000-10,000 g/mol) and specific monomer composition enable the material to break down completely into volatile products that can be efficiently evacuated, achieving reliable complete removal without outgassing collection problems.
Solution Approach 2:
The patent employs a disposable gap-fill material designed for single-use thermal decomposition. The polymer is formulated to completely decompose at high temperatures, leaving no residue and generating minimal outgassing that can be easily evacuated. This approach treats the gap-fill material as a temporary, consumable component that is completely removed after serving its purpose, eliminating long-term contamination issues.
3Reliability
If thermal decomposition temperature is increased to improve removal completeness, then more complete removal is achieved, but limited hotplate ranges prevent full removal
Solution Approach 1:
The patent carefully selects and optimizes the polymer's glass transition temperature and decomposition temperature parameters to match available hotplate capabilities. By controlling the polymer's molecular weight and composition, the material decomposes completely at temperatures achievable with standard high-temperature hotplates (typically up to 400-450°C), eliminating the need for more complex high-temperature equipment while ensuring complete removal.
4Manufacturing precision
If uniform planarizing layer is deposited for accurate pattern transfer, then critical dimension control is improved, but high-aspect-ratio trenches and gaps create filling challenges
Solution Approach 1:
The patent uses a composite approach by combining the gap-fill polymer with specific functional groups and crosslinking agents that enable the material to conform to high-aspect-ratio structures while maintaining uniformity. The polymer's specific molecular weight and composition allow it to fill deep trenches and gaps uniformly, creating a planarizing layer that maintains both gap-filling effectiveness and pattern transfer accuracy.
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 solution enables complete filling of high-aspect-ratio gaps and efficient thermal decomposition, preventing pattern collapse and ensuring accurate pattern transfer with minimal residues, enhancing the multilayer photolithography process.
Implementation Method 1
The gap-fill composition comprises a polymer comprising a crosslinkable monomer and a second monomer different from the crosslinkable monomer. The gap-fill composition is crosslinked to form a crosslinked gap-fill layer.
Implementation Method 2
The crosslinked gap-fill layer is heated to its thermal decomposition temperature or higher, thereby removing at least some of the gap-fill layer.
Data Source
AI summary
Thermally decomposable gap-fill materials are disclosed that fill small features and are completely removed by a high-temperature bake after processing. These materials are self-crosslinkable polymers. Potential applications of these materials include use as sacrificial gap-fill materials for creating air gaps, as well as protection of high-aspect-ratio or other delicate microelectronic features during processing steps.