Seam-Free Gapfill in High Aspect Ratio Trenches
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Solution Overview
Problem
Current methods for filling narrow trenches with high aspect ratios in microelectronics device fabrication often result in seam formation and voiding due to inadequate film penetration and deposition rates, leading to poor film quality and structural failures.
Innovation Solution
A cyclic deposition-etch-treatment process is employed to form a conformal amorphous silicon film within high aspect ratio trenches, where each deposition step creates a seam that is progressively etched to remove, ultimately achieving a seam-free film fill without voids, using techniques like chemical vapor deposition and annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional PECVD or thermal CVD is used to fill high aspect ratio trenches, then deposition can be achieved, but seams and voids form due to inadequate plasma/precursor penetration into deep trenches
Solution Approach 1:
The deposition process is divided into multiple sequential steps: initial conformal deposition, seam formation, seam removal via etch, and repeat cycles. This segmentation allows the system to address the penetration problem by treating seam formation and removal as separate controllable steps rather than attempting perfect single-step deposition.
Solution Approach 2:
The process employs periodic cycles of deposition and etching. Each cycle deposits a thin conformal layer that forms a seam, then an etch step removes the seam. Repeating this periodic action progressively eliminates seams while building up the trench fill, solving the penetration issue through iterative refinement.
2Manufacturing precision
If flowable CVD is used to fill trenches, then conformal coverage can be achieved, but the as-deposited film has poor quality requiring additional processing steps
Solution Approach 1:
The method performs preliminary conformal deposition to ensure complete coverage of the trench walls and bottom before attempting to remove seams. This preliminary action establishes the foundation for quality film formation, allowing subsequent seam removal without compromising the conformal coverage already achieved.
Solution Approach 2:
The process changes deposition parameters to control seam formation depth and characteristics. By adjusting deposition thickness and etch selectivity parameters, the system optimizes the balance between achieving conformal coverage and enabling effective seam removal, improving overall film quality.
3Reliability
If furnace poly-silicon or amorphous silicon dummy gate is used in metal replacement gate processes, then good etch selectivity is achieved, but a seam forms in the middle of the dummy gate causing structure failure
Solution Approach 1:
The method extracts and removes the harmful seam element from the deposited film through selective etching. By identifying the seam as a distinct feature that can be selectively removed while preserving the surrounding film, the process eliminates the source of structure failure while maintaining the beneficial etch selectivity of the amorphous silicon material.
Solution Approach 2:
The process uses feedback from seam detection (via etch response or inspection) to control subsequent deposition and etching cycles. When seams are detected or anticipated, the process parameters are adjusted in real-time to prevent or remove them, ensuring seam-free dummy gate formation while preserving etch selectivity.
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 ensures high-quality, seam-free film deposition in high aspect ratio trenches, enhancing the reliability and performance of microelectronics devices by preventing seam formation and voiding, even at advanced wafer fabrication dimensions.
Implementation Method 1
The film deposition process comprises forming a conformal film on the at least one feature creating a seam within the width of the feature
Implementation Method 2
treatment (e.g., annealing) of the amorphous silicon film
Data Source
AI summary
Methods for seam-less gapfill comprising sequentially depositing a film with a seam, reducing the height of the film to remove the seam and repeating until a seam-less film is formed. Some embodiments include optional film doping and film treatment (e.g., ion implantation and annealing).