Epitaxy Selectivity via Ion Implantation
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Solution Overview
Problem
Current techniques for forming strained semiconductor structures, such as those using epi silicon germanium (SiGe), face challenges in maintaining selectivity between the spacer and substrate, which can adversely impact the SiGe growth rate and process efficiency.
Innovation Solution
A method involving the implantation of Ge, C, P, or B atoms in a material layer over a semiconductor substrate, followed by forming recesses and depositing semiconductor material through an epitaxy process, which improves selectivity and eliminates the need for etchant gases, thereby enhancing SiGe growth and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etchant gas is used with the epi process to maintain selectivity between the spacer and the substrate, then selectivity is improved, but the SiGe growth rate is adversely impacted
Solution Approach 1:
The patent applies preliminary action by implanting atoms (such as Ge, C, P, F, or B) into the spacer material layer before the epitaxial growth process. This pre-treatment modifies the spacer's properties to achieve the desired selectivity during epi growth without requiring etchant gases, thereby resolving the contradiction between maintaining selectivity and preserving SiGe growth rate.
2Manufacturing precision
If etchant gases are used to maintain selectivity, then selectivity between spacer and substrate is improved, but process complexity and harmful factors increase
Solution Approach 1:
The patent extracts and eliminates the need for etchant gases from the process by using atom implantation to achieve selectivity. This removes the harmful factor of etchant gases while maintaining the critical selectivity between spacer and substrate during the epitaxial growth of SiGe.
3Manufacturing precision
If atom implantation is performed in the material layer, then selectivity is improved and etchant gases are eliminated, but process steps are added
Solution Approach 1:
The patent changes the physical-chemical parameters of the spacer material layer through atom implantation, modifying its composition or structure to achieve the desired selectivity. This parameter change approach replaces the need for complex etchant gas processes with a more controlled and precise implantation technique.
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 increases throughput and expands the process window by maintaining SiGe selectivity to the silicon nitride, preventing SiGe deposition on implanted regions and ensuring a constrained facet profile, thus improving carrier mobility and device performance without the use of etchant gases.
Implementation Method 1
implanting one of Ge, C, P, F, and B in the material layer
Implementation Method 2
depositing a semiconductor material in the recesses by an expitaxy process
Data Source
AI summary
The present disclosure provides a method of fabricating a semiconductor device that includes providing a semiconductor substrate, forming a gate structure over the substrate, forming a material layer over the substrate and the gate structure, implanting Ge, C, P, F, or B in the material layer, removing portions of the material layer overlying the substrate at either side of the gate structure, forming recesses in the substrate at either side of the gate structure, and depositing a semiconductor material in the recesses by an expitaxy process.