Barrier Layer Thickness Control in Trenches via Neutral Beam Oxidation
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Solution Overview
Problem
As semiconductor and electronic structures shrink in size, it becomes increasingly difficult to form uniform barrier layers in trenches and vias, particularly below 3 nanometers, which is essential for effective interconnects, as existing methods like PVD and ALD result in non-uniform thickness and poor step coverage.
Innovation Solution
A technique involving neutral beam oxidation and modified etch-K chemistries is used to form and selectively thin barrier layers in trenches, achieving uniform thickness by forming an oxidized layer and removing it through an etching process, maintaining the modified trench profile while ensuring scalability and minimizing non-Cu material resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PVD or ALD methods are used to form barrier layers, then the process is simple or conformal coverage is achieved, but the barrier layer thickness becomes non-uniform and step coverage is poor
Solution Approach 1:
The barrier layer formation is divided into multiple deposition cycles with alternating oxidation and etching steps. Each cycle deposits a portion of the barrier layer, oxidizes it selectively at the bottom, and removes the oxidized portion. This segmented approach achieves uniform thickness control that would be impossible in a single continuous deposition step.
Solution Approach 2:
The process employs periodic alternating actions of deposition, oxidation, and etching. The neutral beam oxidation is applied periodically to specific regions (bottom of trenches) while the etching process periodically removes oxidized material. This periodic action pattern enables precise thickness control at different locations within the trench structure.
2Area of moving object
If the barrier layer thickness is reduced below 3 nanometers, then the interconnect area is enhanced, but the formation becomes increasingly difficult and non-uniform
Solution Approach 1:
The neutral beam oxidation process applies different treatment to different locations within the trench structure. The bottom regions receive oxidation while sidewalls and top regions do not. This local quality differentiation enables selective thinning of the barrier layer at the bottom to achieve uniform thickness across the entire trench, allowing overall thickness reduction below 3nm while maintaining control.
Solution Approach 2:
The process changes physical and chemical parameters of the barrier layer material through oxidation. By converting portions of the barrier layer to an oxidized state and then selectively removing it, the effective thickness is reduced and uniformized. This parameter change approach enables precise thickness control at sub-3nm scales.
3Manufacturing precision
If cyclic oxidation and etching processes are used, then uniform barrier layer thickness is achieved, but the process complexity increases
Solution Approach 1:
The oxidation process serves as an intermediary step between deposition and etching. Rather than directly etching the barrier layer, the process first oxidizes it in situ, creating a distinct intermediate layer that is then selectively removed. This intermediary oxidation step enables selective thinning and uniform thickness control that would be difficult to achieve with direct etching alone.
Solution Approach 2:
The process replaces traditional mechanical or chemical deposition methods with neutral beam oxidation for selective material modification. The neutral beam provides a non-contact, highly selective oxidation mechanism that substitutes for conventional thermal or chemical oxidation methods, enabling precise spatial control of the oxidation reaction.
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 allows for precise control of barrier layer thickness, achieving uniformity comparable to ALD with the fill advantages of PVD, enhancing interconnect area and resistance targets, particularly for Cu interconnects.
Implementation Method 1
forming an oxidized layer using a neutral beam oxidation
Implementation Method 2
removing the oxidized layer using an etching process
Data Source
AI summary
A semiconductor structure includes a dielectric layer having a trench formed therein and a barrier layer formed on a bottom and sidewalls of the trench, and on a top surface of the dielectric layer. The trench comprises a flared top gap opening and additional area at the bottom such that the top and bottom of the trench are wider than sidewalls of the trench. A thickness of the barrier layer on the bottom of the trench and on the top surface of the dielectric layer is controlled using one or more cycles comprising forming an oxidized layer using a neutral beam oxidation and removing the oxidized layer using an etching process, such that the thickness of the barrier layer on the bottom of the trench and on the top surface of the dielectric layer is substantially the same as the thickness of the barrier layer on sidewalls of the trench.