UV Cure for High Aspect Ratio Trench Gapfill
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Solution Overview
Problem
The semiconductor industry faces challenges in depositing films in high aspect ratio trenches without forming seams or voids, which can lead to defects in FinFET devices during the fabrication of semiconductor devices.
Innovation Solution
A cyclic deposition-etching process followed by an ultraviolet (UV) cure process is used to fill high aspect ratio trenches with a dummy gate layer, breaking Si—H bonds and reconstructing Si—Si bonds to densify the film and reduce or eliminate seams and voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a film is deposited in high aspect ratio trenches using conventional deposition methods, then the trenches can be filled, but seams or voids form in the film leading to defects
Solution Approach 1:
The patent applies periodic cyclic deposition-etching actions to fill high aspect ratio trenches. Multiple deposition cycles are performed with etching steps in between, allowing the film to be deposited layer by layer while removing defective portions. This periodic process enables progressive densification of the film without forming continuous seams or voids, resolving the contradiction between filling the trench and maintaining film quality.
Solution Approach 2:
The patent changes processing parameters by introducing UV curing treatment after deposition cycles. The UV light exposure modifies the chemical state of the deposited film, breaking Si-H bonds and promoting Si-Si bond formation. This parameter change (adding photonic energy treatment) transforms the film structure in situ, densifying it and eliminating voids without requiring higher deposition temperatures or pressures that would exacerbate the trench filling problem.
2Ease of manufacture
If conventional deposition methods are used to fill high aspect ratio trenches, then the process is simple, but defects occur in the film
Solution Approach 1:
The patent introduces UV light as an intermediary treatment between deposition steps. This intermediary photonic treatment mediates the transformation of the deposited film from a porous, defective state to a dense, reliable state. The UV curing step acts as a bridge that connects the simple deposition process with the desired high-quality film outcome, adding minimal complexity while dramatically improving reliability by eliminating defects.
3Quantity of substance
If the trench aspect ratio is high, then device density increases, but film deposition becomes difficult without forming voids
Solution Approach 1:
The patent segments the continuous deposition process into discrete cyclic steps of deposition and etching. By dividing the filling process into manageable segments, each deposition cycle deposits a controlled amount of material that can be subsequently refined by etching and UV treatment. This segmentation allows precise control over film uniformity even in high aspect ratio trenches, enabling device density improvement without sacrificing film quality.
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 method effectively fills high aspect ratio trenches with a dense film, reducing the risk of defects in replacement gate structures and improving the yield of semiconductor devices.
Implementation Method 1
exposing the conformal film to ultraviolet light to break Si—H bonds and reconstruct Si—Si bonds
Implementation Method 2
an ultraviolet (UV) cure process is used to fill high aspect ratio trenches with a dummy gate layer
Data Source
AI summary
Embodiments disclosed herein relate generally to forming a gate layer in high aspect ratio trenches using a cyclic deposition-etch process. In an embodiment, a method for semiconductor processing is provided. The method includes performing a first deposition process to form a conformal film over a bottom surface and along sidewall surfaces of a feature on a substrate. The method includes performing an etch process to remove a portion of the conformal film. The method includes repeating the first deposition process and the etch process to fill the feature with the conformal film. The method includes exposing the conformal film to ultraviolet light.