Seamless Trench Fill via Oxidation-Etching Cycle
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Solution Overview
Problem
Conventional methods, such as plasma-enhanced chemical vapor deposition (PECVD), fail to fill narrow trenches with high aspect ratios without voiding, resulting in 'mushroom shape' films and pinching-off, which leads to seams and composition variations within the trench.
Innovation Solution
A method involving conformal nitride film deposition followed by oxidation and etching using atomic layer deposition (ALD) and pseudo atomic layer etch techniques, with repeated cycles to achieve a v-shaped nitride film, ensuring seamless filling of high aspect ratio trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional PECVD is used to deposit dielectric films, then deposition can be performed, but the film forms a mushroom shape on top of narrow trenches due to plasma inability to penetrate deep trenches, resulting in pinching-off and void formation at the bottom
Solution Approach 1:
The deposition process is segmented into multiple sequential steps: initial conformal deposition, oxidation to form asymmetric oxide, selective etching of the oxide, and repetition of the cycle. This segmentation allows progressive filling of the trench while maintaining uniformity and avoiding mushroom-shaped defects.
Solution Approach 2:
An asymmetric oxide layer is formed preliminarily on the deposited film before etching. This preliminary oxidation creates a sacrificial layer that guides the subsequent etching process to achieve the desired V-shape profile and prevent void formation.
2Length of moving object
If aspect ratios increase in narrow trenches, then device dimensions decrease, but post-curing of as-deposited flowable films becomes difficult, resulting in films with varying composition throughout the filled trench
Solution Approach 1:
The deposition-oxidation-etching sequence is performed periodically in multiple cycles. Each cycle deposits a thin conformal layer, oxidizes it to form an asymmetric oxide, and etches the oxide selectively. This periodic repetition ensures uniform composition throughout the trench by maintaining consistent processing conditions in each cycle.
3Manufacturing precision
If bottom up gap fill is performed, then gap filling can be achieved, but seams are left in the filled structure and annealing to remove seams requires temperatures higher than the thermal budget
Solution Approach 1:
An asymmetric oxide layer serves as an intermediary sacrificial material during the filling process. The oxide is deposited conformally, then selectively etched to create the desired profile. This intermediary layer enables seamless filling because it can be removed completely without leaving seams, and its removal occurs at lower temperatures than traditional annealing processes.
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 approach allows for seamless, high-quality filling of narrow trenches with minimal seam formation, maintaining uniform composition and preventing voids, even in structures with high aspect ratios.
Implementation Method 1
depositing a conformal titanium nitride film on the substrate surface and the at least one feature by sequentially exposing the substrate surface to a titanium precursor comprising one or more of tetrakis(dimethylamino) titanium or titanium chloride and a reactant comprising an ammonia plasma
Implementation Method 2
oxidizing a portion of the titanium nitride film by exposing the titanium nitride film to an oxidizing agent comprising one or more of ozone, hydrazine or oxygen plasma to form an asymmetric titanium oxide film on top of the titanium nitride film
Implementation Method 3
etching the titanium oxide film from the titanium nitride film by exposing the titanium oxide film to a metal halide comprising one or more of niobium chloride, niobium fluoride, tungsten fluoride or tungsten chloride to leave a v-shaped titanium nitride film in the at least one feature
Data Source
AI summary
Methods for filing a feature on a substrate surface comprising depositing a conformal nitride film on the substrate surface and at least one feature on the surface, oxidizing a portion of the nitride film to form an asymmetric oxide film on top of the nitride film and etching the oxide film from the nitride film to leave a v-shaped nitride film in the at least one feature.