Flowable Silicon Oxide Gap Fill via Precursor Ratio Control
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Solution Overview
Problem
Current deposition processes face challenges in reliably filling small, high aspect ratio trenches and gaps in semiconductor processing due to pinching off and the formation of voids and seams, especially with conformal deposition techniques.
Innovation Solution
A method involving the reaction of cyclic and aliphatic organic siloxane precursors with atomic oxygen to form a flowable silicon oxide layer, which is initially conformal and then cured to fill gaps without voids, using a ratio of cyclic to aliphatic precursor flow rates of at least 2:1, and maintaining the substrate at temperatures between 0°C and 200°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conformal deposition techniques are used to fill trenches, then the deposition is uniform and conformal, but the gaps pinch off at their necks and voids form
Solution Approach 1:
Instead of using conformal deposition from the top down which causes pinching off, the patent uses non-conformal deposition that preferentially fills the narrow neck regions first, then progresses upward. This inverted approach prevents pinching off by ensuring the narrowest parts are filled before the wider openings seal shut.
Solution Approach 2:
The patent changes deposition parameters including using lower substrate temperatures (room temperature to 200°C), adjusting precursor flow rates (cyclic to aliphatic ratio of at least 2:1), and controlling pressure conditions to achieve non-conformal deposition that favors neck region filling over conformal coverage.
2Productivity
If PVD or PECVD processes are used for gap filling, then deposition can be achieved, but voids and seams form in the fill material
Solution Approach 1:
The patent uses a composite precursor system combining cyclic organic siloxane (e.g., OMCTS) and aliphatic organic siloxane (e.g., TMOS) in specific ratios. This composite approach creates a flowable dielectric material with optimized properties that fills gaps completely without voids or seams, then cures to form a reliable solid structure.
Solution Approach 2:
The deposited silicon oxide layer maintains a flowable state during deposition, allowing it to dynamically adapt and fill the gap features completely. After deposition, the material is cured to transition from flowable to solid, ensuring void-free filling while maintaining reliability.
3Productivity
If the substrate temperature is increased to improve deposition rate, then productivity increases, but the flowability of the deposited layer is reduced
Solution Approach 1:
The patent optimizes substrate temperature to a specific range (room temperature to 200°C) that balances deposition rate with flowability. This temperature parameter change ensures the deposited silicon oxide remains flowable enough to fill gaps completely while still achieving practical deposition rates, then allows curing to lock in the filled structure.
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 consistent, void-free gap filling with a high-quality silicon oxide layer that is uniform and resistant to seams, even in features with high aspect ratios, and can be further improved through annealing to enhance its dielectric properties.
Implementation Method 1
reacting the cyclic organic siloxane precursor and the aliphatic organic siloxane precursor with atomic oxygen to form the silicon oxide layer on a substrate positioned in the deposition chamber
Implementation Method 2
curing the deposited silicon oxide layer
Implementation Method 3
generating atomic oxygen outside a deposition chamber and introducing the atomic oxygen into the deposition chamber
Data Source
AI summary
Implementations described herein generally relate to methods for dielectric gap-fill. In one implementation, a method of depositing a silicon oxide layer on a substrate is provided. The method comprises introducing a cyclic organic siloxane precursor and an aliphatic organic siloxane precursor into a deposition chamber, reacting the cyclic organic siloxane precursor and the aliphatic organic siloxane precursor with atomic oxygen to form the silicon oxide layer on a substrate positioned in the deposition chamber, wherein the substrate is maintained at a temperature between about 0° C. and about 200° C. as the silicon oxide layer is formed, wherein the silicon oxide layer is initially flowable following deposition, and wherein a ratio of a flow rate of the cyclic organic siloxane precursor to a flow rate of the aliphatic organic siloxane precursor is at least 2:1 and curing the deposited silicon oxide layer.