Metal Nitride Gapfill for Seam-Free High-Aspect Trenches
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Solution Overview
Problem
The formation of seams and voids during the atomic layer deposition of titanium nitride and tungsten stacks in 3D structures like FinFETs and DRAM word lines leads to issues in downstream processes, necessitating methods to fill these structures without creating seams.
Innovation Solution
A deposition-treatment-etch-deposition scheme is employed, involving the formation of a first film, treatment with oxidizing plasma to form an oxidized film, etching the oxidized film, and depositing a second film to fill the feature without seams or voids, using a batch processing chamber for high aspect ratio trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If atomic layer deposition is used to fill high aspect ratio trenches, then the trenches can be filled, but seams and voids are formed in the deposited film
Solution Approach 1:
The deposition process is divided into multiple sequential deposition steps with intermediate plasma treatments. Instead of attempting to fill the high aspect ratio trench in a single continuous deposition, the film is built up in segments, allowing plasma to penetrate and treat intermediate layers, ensuring complete coverage and eliminating seams and voids that would form in a single-step deposition.
Solution Approach 2:
The process employs periodic alternation between deposition and plasma treatment cycles. After each deposition step, plasma is introduced to treat the film, creating a repeating pattern of deposit-plasma-deposit-plasma. This periodic action ensures that each layer is properly treated before the next is added, preventing defect accumulation and ensuring uniform film quality throughout the high aspect ratio structure.
2Productivity
If conventional deposition methods are used, then deposition speed is maintained, but seams and voids are created causing downstream process issues
Solution Approach 1:
The process maintains continuous film growth through optimized deposition parameters and timing. By carefully controlling deposition rates and plasma treatment durations, the process ensures that material is continuously added to build the film without interruption or defects. The plasma treatment steps are timed to occur during or between deposition cycles, ensuring continuous useful action without stopping the overall film formation process.
3Manufacturing precision
If plasma treatment is applied to form oxidized film, then film quality is improved, but additional process steps are required
Solution Approach 1:
The plasma treatment steps are merged with the deposition sequence rather than being separate post-processing operations. The plasma treatments are integrated into the deposition cycle itself, occurring between deposition steps or concurrently with deposition, thereby combining multiple functions into a unified process flow. This merging reduces overall process complexity compared to adding separate plasma treatment steps after complete deposition.
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 results in seam-free, high-quality film deposition that effectively fills high aspect ratio trenches, improving the integrity of structures like FinFETs and DRAM word lines by preventing void formation and delamination.
Implementation Method 1
treating the substrate surface with an oxidizing plasma to form an oxidized film
Implementation Method 2
treating the substrate surface with an oxidizing plasma to form an oxidized film
Implementation Method 3
A seam is often observed from an ALD or CVD deposited film
Implementation Method 4
A seam is often observed from an ALD or CVD deposited film
Implementation Method 5
etching the substrate surface to remove the oxidized film
Data Source
AI summary
Methods for filling a substrate feature with a seamless metal gate fill are described. Methods comprise sequentially depositing a film on a substrate surface having at least one feature thereon. The at least one feature extends a feature depth from the substrate surface to a bottom surface and has a width defined by a first sidewall and a second sidewall. The film is treated with an oxidizing plasma. Then the film is etched to remove the oxidized film. A second film is deposited to fill the feature, where the second film substantially free of seams and voids.