Nitrogen Plasma Passivation for Bottom-Up Tungsten Gap Fill
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor device fabrication lies in achieving precise metal gap-fill with critical dimensions, as existing techniques often result in incomplete filling due to overhangs and seams, and are affected by impurities like fluorine, boron, and nitrogen, leading to increased resistance and fabrication costs.
Innovation Solution
A method involving nitrogen plasma treatment is used to passivate the tungsten nucleation layer, allowing for bottom-up growth of tungsten layers within semiconductor features, ensuring conformal treatment and reducing resistance penalties by delaying incubation/growth on sidewalls and top fields, thereby achieving nearly conformal metal gap-fill with reduced resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bottom-up growth methods are used to fill metal gaps, then the gap can be filled, but seams and incomplete filling occur due to overhangs on sidewalls
Solution Approach 1:
The patent applies preliminary nitrogen plasma treatment to passivate the tungsten nucleation layer on sidewalls before the metal gap-fill process. This preliminary action prevents premature tungsten nucleation on sidewall surfaces, ensuring that tungsten grows only from the bottom surface and eliminates seam formation, thereby resolving the contradiction between gap-fill completeness and uniformity
Solution Approach 2:
The patent introduces nitrogen plasma as an intermediary substance that temporarily modifies the surface chemistry of the tungsten nucleation layer. The nitrogen radicals adsorb onto the tungsten surface, creating a passivation layer that blocks unwanted nucleation sites on sidewalls while allowing controlled bottom-up growth, thus achieving uniform gap-fill without seams
2Manufacturing precision
If multiple incremental processes are used to control critical dimensions, then dimension control improves, but fabrication time and cost increase
Solution Approach 1:
The patent combines the nucleation layer preparation and metal gap-fill processes into a single integrated process sequence. By performing nitrogen plasma treatment immediately before tungsten deposition in the same chamber, the patent eliminates intermediate transfer steps and reduces the total number of process chambers required, thereby maintaining critical dimension control while improving fabrication throughput and reducing costs
Solution Approach 2:
The patent designs a multi-functional process chamber that can perform both plasma treatment and metal deposition functions. This universal chamber configuration allows the same equipment to execute multiple process steps that would traditionally require separate specialized chambers, reducing overall fabrication time and improving productivity while maintaining precision
3Reliability
If nitrogen plasma treatment is applied to passivate sidewall tungsten, then seam formation is prevented, but complete passivation may inhibit desired bottom-up growth
Solution Approach 1:
The patent applies nitrogen plasma treatment with locally optimized parameters to achieve selective passivation. By controlling plasma power, gas flow rates, and exposure time, the treatment selectively passivates tungsten nucleation sites on sidewalls while leaving the bottom surface sufficiently reactive to initiate bottom-up growth. This local quality control prevents seam formation while maintaining desired growth behavior
Solution Approach 2:
The patent optimizes plasma treatment parameters including nitrogen gas flow rate, plasma power, and treatment duration to achieve the desired balance between passivation and growth control. By carefully adjusting these parameters, the process achieves sufficient sidewall passivation to prevent seams while maintaining bottom surface reactivity for controlled bottom-up tungsten growth
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 enables improved metal gap-fill with reduced resistance and increased grain size, overcoming the limitations of conventional bottom-up growth methods, resulting in enhanced Rs/Rc performance and cost-effective fabrication.
Implementation Method 1
generating a plasma comprising nitrogen-containing radicals in a remote plasma source
Implementation Method 2
exposing an exposed portion of the tungsten nucleation layer along the sidewall surfaces of the tungsten nucleation layer to the nitrogen-containing radicals to passivate the exposed portion
Data Source
AI summary
A method of forming a semiconductor device structure includes forming a nucleation layer within at least one feature. The method includes exposing the nucleation layer to a nitrogen plasma treatment. The nitrogen plasma treatment preferentially treats the top field and sidewalls while leaving the bottom surface substantially untreated to encourage bottom up metal growth.