Backside Power Rail Substrate Etching with Ion-Implanted Recesses
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Solution Overview
Problem
As semiconductor devices continue to integrate more components into a given area with reduced feature sizes, challenges arise in efficiently removing substrates during etching processes, leading to etch rate variations and non-uniform oxide growth, which affect device performance and increase defects.
Innovation Solution
Performing an ion implantation on the substrate prior to etching to damage the crystal structure, enhancing the etch rate and selectivity, and subsequently growing an oxide in the resulting recess to improve uniformity and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used on substrates with reduced feature sizes, then substrate removal is attempted, but etch rate variations and non-uniform oxide growth occur leading to device defects
Solution Approach 1:
Ion implantation is performed on the substrate prior to etching to damage the crystal structure in advance. This preliminary action creates a more uniform etch response across the substrate surface, preventing etch rate variations and non-uniform oxide growth that would otherwise lead to device defects
Solution Approach 2:
The crystal structure of the substrate is modified through ion implantation, changing its physical and chemical parameters. This parameter change enhances etch selectivity and reduces facet effects, leading to more uniform etching and subsequent oxide growth
2Ease of manufacture
If substrate etching is performed without ion implantation, then the process is simpler, but etch rate variations occur due to facet effects reducing manufacturing precision
Solution Approach 1:
Ion implantation is applied as a preliminary step to damage the substrate crystal structure before etching. This pre-treatment reduces facet effects and promotes uniform etch rates across the substrate, significantly improving manufacturing precision without substantially complicating the overall process
Solution Approach 2:
By changing the crystal structure parameters through ion implantation, the substrate becomes more resistant to facet effects during etching. This parameter modification ensures more uniform etch rates while maintaining process feasibility
3Manufacturing precision
If ion implantation is performed to damage crystal structure, then etch selectivity is enhanced, but additional process steps are required increasing device complexity
Solution Approach 1:
Ion implantation is performed as a preliminary step to enhance etch selectivity. While this adds a process step, it enables subsequent complete substrate removal and uniform oxide growth, ultimately improving device performance and reducing defects that would require even more complex remediation
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
The method allows for complete substrate removal with reduced etch rate variations, improving oxide growth uniformity and device performance by addressing facet effects and enhancing etch selectivity.
Implementation Method 1
performing an ion implantation on the substrate prior to etching the substrate. The ion implantation may be used to damage the crystal structure of the substrate
Implementation Method 2
improves an etch selectivity of the substrate relative to surrounding materials
Implementation Method 3
reduces etch rate variations of the substrate based on facets in the substrate (facet effect)
Implementation Method 4
subsequently growing an oxide in the resulting recess to improve uniformity and reduce defects
Data Source
AI summary
A method of forming a semiconductor device including performing an ion implantation on a substrate and etching the substrate and semiconductor devices formed by the same are disclosed. In an embodiment, a method includes forming a transistor on a first side of a substrate; performing an ion implantation on a second side of the substrate opposite the first side; after performing the ion implantation, etching the substrate to remove the substrate and form a first recess; and forming a dielectric layer in the first recess.