Ion Implantation for CMP Dishing and Erosion Control
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes in integrated circuit manufacturing face issues such as localized dishing, microloading, erosion, and non-uniformity, leading to reliability differences and yield loss across dies due to variations in metal thickness and grain size, which affect the polish rate and material removal.
Innovation Solution
Ion implantation is used to amorphize metal surfaces, reducing grain size dependency and improving hardness, thereby enhancing the uniformity and efficiency of the CMP process by using plasma doping systems or beamline ion implanters to implant species into workpieces before or during the CMP step, controlling the depth and energy of implantation to minimize dishing and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If CMP process is used for material removal and planarization, then surface flatness is improved, but localized dishing and non-uniformity occur
Solution Approach 1:
Ion implantation is performed before the CMP process to modify the metal surface properties in advance. The implantation creates a modified surface layer with altered mechanical and chemical properties that resist excessive material removal during subsequent CMP, preventing dishing while maintaining planarization effectiveness
Solution Approach 2:
The ion implantation process changes the physical and chemical parameters of the metal surface by introducing implanted species that modify surface hardness, grain structure, and reactivity. These parameter changes make the surface more resistant to non-uniform polishing, thereby improving manufacturing precision while maintaining surface flatness
2Shape
If CMP process is used to remove material, then planarization is achieved, but dishing and erosion occur leading to yield loss
Solution Approach 1:
Ion implantation is applied as a preliminary treatment before CMP to protect the metal surface from excessive material removal and erosion. The implanted species create a hardened surface layer that maintains structural integrity during polishing, preventing dishing and erosion that would otherwise lead to yield loss and reliability issues
Solution Approach 2:
The ion implantation process creates a cushioning effect by forming a modified surface layer that absorbs and distributes the mechanical and chemical stresses during CMP. This beforehand cushioning prevents localized erosion and dishing, protecting the metal lines from damage that would reduce yield and reliability
3Manufacturing precision
If ion implantation is used to amorphize metal surface, then grain size dependency is reduced and hardness is improved, but process complexity increases
Solution Approach 1:
The ion implantation process replaces mechanical surface treatment methods with a physics-based approach using ion beams or plasma. This substitution achieves surface modification and amorphization through controlled ion bombardment and diffusion, providing more uniform results with less mechanical complexity compared to traditional mechanical polishing or surface treatment methods
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
Ion implantation improves CMP process results by reducing dishing, erosion, and microloading effects, leading to more uniform metal line resistance and reduced yield loss, while also enhancing metal surface adhesion and passivation layer integration.
Implementation Method 1
Ion implantation is used to amorphize metal surfaces, reducing grain size dependency and improving hardness
Implementation Method 2
At least a portion of the metal is amorphized by implanting a species into the metal
Data Source
AI summary
Embodiments of this method improve the results of a chemical mechanical polishing (CMP) process. A surface is implanted with a species, such as, for example, Si, Ge, As, B, P, H, He, Ne, Ar, Kr, Xe, and C. The implant of this species will at least affect dishing, erosion, and polishing rates of the CMP process. The species may be selected in one embodiment to either accelerate or decelerate the CMP process. The dose of the species may be varied over the surface in one particular embodiment.