CD-Dependent Silicon Gap Fill and Conformal Film Deposition
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Solution Overview
Problem
Current deposition methods for gap fill and conformal films in SiGe finFETs and gate all-around transistors face challenges with poor quality films at low deposition temperatures, including seams and voids at narrow trench dimensions and high wet etch rates at wide trench dimensions due to film stress and volumetric shrinkage.
Innovation Solution
A method involving the deposition of a flowable polysilazane material on a substrate using a silicon precursor and plasma-based reactants, followed by UV curing and annealing to form silicon-containing films that laterally fill features without seams or voids at narrow dimensions and conformally coat wider features, utilizing trisilylamine and reactive gases like ammonia or oxygen to control film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ALD is used for gap fill at low deposition temperatures, then SiGe out-diffusion is prevented, but films exhibit poor quality with seams or voids at narrow trench dimensions
Solution Approach 1:
The patent changes the deposition temperature parameter from low (preventing out-diffusion) to elevated (improving film quality), and combines it with in-situ nitrogen passivation to simultaneously achieve both goals: high-quality gap fill without seams or voids while preventing SiGe out-diffusion through the nitrogen-containing atmosphere
Solution Approach 2:
The patent introduces nitrogen as an intermediary substance that passivates SiGe interfaces during deposition, preventing out-diffusion while allowing elevated temperature deposition to proceed. The nitrogen acts as a protective mediator between the hot deposition environment and the SiGe substrate
2Reliability
If conventional flowable CVD is used at low anneal temperatures, then SiGe out-diffusion is minimized, but films exhibit high wet etch rate at wide trench dimensions due to film stress and volumetric shrinkage
Solution Approach 1:
The patent eliminates the need for high-temperature annealing by incorporating nitrogen passivation during deposition itself, allowing gap fill to be performed at elevated temperatures without subsequent annealing steps that would cause stress and shrinkage
Solution Approach 2:
The patent performs nitrogen passivation continuously during the deposition process itself, rather than as a separate pre- or post-treatment step, ensuring continuous protection of SiGe interfaces throughout the entire film formation process
3Manufacturing precision
If elevated deposition temperature is used, then film quality improves, but SiGe out-diffusion occurs
Solution Approach 1:
Nitrogen serves as an intermediary that enables elevated temperature deposition by passivating SiGe interfaces, allowing the beneficial thermal effects (improved film quality) to occur while the nitrogen barrier prevents the harmful effect (SiGe out-diffusion)
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 achieves high-quality gap fill without seams or voids at narrow dimensions and conformal coating at wider dimensions, reducing film stress and impurities, and enables better integration with subsequent ALD processes, resulting in superior film quality and reduced roughness.
Implementation Method 1
exposing a substrate surface with at least one feature formed therein to a silicon precursor and a plasma based reactant to deposit a flowable polysilazane material
Implementation Method 2
The flowable polysilazane material is exposed to UV radiation to cure the flowable polysilazane material and form a SiNH film
Implementation Method 3
The SiNH film is annealed in an anneal environment to form a silicon-containing material
Data Source
AI summary
A method of depositing a silicon-containing material is disclosed. Some embodiments of the disclosure provide films which fill narrow CD features without a seam or void. Some embodiments of the disclosure provide films which form conformally on features with wider CD. Embodiments of the disclosure also provide superior quality films with low roughness, low defects and advantageously low deposition rates.