Semiconductor Device Epitaxial Dislocation Removal
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Solution Overview
Problem
Conventional semiconductor fabrication processes often result in the formation of dislocations during epitaxial growth, which negatively impact the optical and electrical performance of semiconductor materials.
Innovation Solution
A method involving multiple deposition and etching processes is employed to form epitaxial layers, where each deposition step is followed by an etching process to remove part of the epitaxial layer and embedded dislocations, specifically using silicon phosphide (SiP) and etching gases like hydrochloric acid (HCl) to minimize dislocation formation and ensure their removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If selective epitaxial growth technique is used to form SiGe epitaxial layer to produce compressive stress and increase carrier mobility, then carrier mobility is improved, but dislocations are easily formed during epitaxial growth
Solution Approach 1:
The patent applies segmentation by dividing the continuous epitaxial growth process into multiple discrete stages: initial growth stage, intermediate etching stage, and final growth stage. Each stage serves a specific purpose - the initial stage forms the base layer, the intermediate etching removes dislocations, and the final stage completes the epitaxial structure. This segmented approach allows the process to achieve both high carrier mobility through complete SiGe layer formation and low dislocation density through periodic removal of defective material.
Solution Approach 2:
The patent implements periodic action through alternating cycles of epitaxial growth and etching processes. The growth phase deposits SiGe material to build the epitaxial layer and induce compressive stress for enhanced carrier mobility, while the subsequent etching phase periodically removes accumulated dislocations. This periodic alternation between constructive (growth) and corrective (etching) actions enables the system to maintain high material quality throughout the formation process.
2Manufacturing precision
If multiple deposition and etching processes are performed to remove dislocations, then dislocation density is reduced, but fabrication process complexity increases
Solution Approach 1:
The patent applies merging by combining the deposition and etching operations into an integrated multi-stage process sequence. Rather than treating these as separate, independent processes, the methodology merges them into a coordinated workflow where each etching step is directly coupled with subsequent growth steps. This merging reduces process complexity by creating a systematic, repeatable pattern that can be automated and controlled through unified process parameters.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying growth conditions (temperature, pressure, gas flow rates, composition ratios) and etching conditions (etchant concentration, temperature, duration) across different stages of the process. These parameter adjustments optimize each stage's performance - for example, using different SiGe composition ratios in initial versus final growth stages, or varying etching durations to match accumulated dislocation levels - thereby achieving high dislocation removal efficiency without requiring excessive process steps.
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 effectively reduces dislocation density within the epitaxial layers, thereby enhancing the electrical and optical properties of semiconductor devices by ensuring complete removal of dislocations through repeated deposition and etching cycles.
Implementation Method 1
performing a first deposition process to form a first epitaxial layer
Implementation Method 2
using silicon phosphide (SiP) and etching gases like hydrochloric acid (HCl)
Implementation Method 3
performing a first etching process to remove part of the first epitaxial layer at the same time
Data Source
AI summary
A semiconductor device is disclosed. The semiconductor device includes: a substrate, a gate structure on the substrate, a spacer adjacent to the gate structure, an epitaxial layer in the substrate adjacent to two sides of the spacer, and a dislocation embedded within the epitaxial layer. Preferably, the top surface of the epitaxial layer is lower than the top surface of the substrate, and the top surface of the epitaxial layer has a V-shape.