Backside Power Rail Substrate Etching with Ion Implantation
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Solution Overview
Problem
As the minimum feature sizes in semiconductor devices are reduced, challenges arise in achieving uniform etch rates and selectivity, particularly due to facet effects during backside etching processes.
Innovation Solution
Performing an ion implantation on the substrate prior to etching damages the crystal structure, enhancing the etch rate, reducing facet-related variations, and improving etch selectivity, allowing for complete removal of the substrate during a wet etch process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching is performed on the substrate, then the etching process can be completed, but non-uniform etch rates and facet effects occur reducing manufacturing precision
Solution Approach 1:
Ion implantation is performed on the substrate before the etching process to pre-damage the crystal structure. This preliminary action creates uniform etch susceptibility across the substrate surface, eliminating facet effects and ensuring uniform etch rates during subsequent wet etching, thereby resolving the contradiction between etch rate uniformity and etch selectivity
Solution Approach 2:
The crystal structure of the substrate is modified through ion implantation, changing its physical and chemical parameters. This parameter change increases the substrate's susceptibility to wet etching while maintaining selectivity, allowing uniform etch rates to be achieved without sacrificing etch selectivity, thus resolving the technical contradiction
2Manufacturing precision
If ion implantation is performed on the substrate prior to etching, then etch rate uniformity and selectivity are improved, but additional process steps are required increasing device complexity
Solution Approach 1:
The ion implantation process serves multiple functions: it pre-damages the crystal structure to enable uniform etching, enhances etch selectivity between substrate and surrounding materials, and prepares the substrate surface for complete removal. By combining these functions into a single preliminary step, the patent reduces overall process complexity while achieving superior etch uniformity
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 ion implantation method ensures uniform oxide growth, reduces device defects, and enhances performance by addressing facet effects and improving etch selectivity.
Implementation Method 1
performing an ion implantation on a substrate prior to etching the substrate. The ion implantation may be used to damage the crystal structure of the substrate, which increases an etch rate of the substrate, reduces etch rate variations of the substrate based on facets in the substrate
Implementation Method 2
improves an etch selectivity of the substrate relative to surrounding materials (e.g., a silicon germanium (SiGe) dummy fin extending through the substrate, a SiGe etch stop layer, and the like)
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.