Si/SiGe Superlattice XRF Control for Strain-Stable Epitaxy
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the need for precise control and monitoring of layer thickness and composition in superlattice structures, particularly in 3D DRAM devices, to prevent strain relaxation and defect formation in SiGe layers during epitaxial deposition.
Innovation Solution
Implementing an X-ray fluorescence (XRF) measurement system to monitor and control the thickness and composition of Si/SiGe layers in-situ during epitaxial deposition, using an X-ray source and detector to adjust deposition parameters based on real-time measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional post-deposition measurement methods are used, then manufacturing simplicity is maintained, but manufacturing precision and measurement accuracy deteriorate due to inability to monitor in-situ
Solution Approach 1:
The patent combines the epitaxial deposition process with in-situ XRF measurement capabilities by integrating the X-ray source and detector directly into the deposition chamber. This merging allows simultaneous or sequential deposition and measurement without removing the substrate, achieving high measurement precision while avoiding the complexity of separate measurement equipment and processes.
Solution Approach 2:
The patent introduces an X-ray fluorescence measurement system as an intermediary between the deposition process and final quality assessment. This intermediary enables real-time monitoring of layer thickness and composition during deposition, providing continuous feedback without disrupting the primary deposition workflow.
2Manufacturing precision
If in-situ XRF measurement is implemented, then manufacturing precision is improved through real-time monitoring, but productivity deteriorates due to additional process steps
Solution Approach 1:
The patent implements continuous in-situ monitoring during the epitaxial deposition process, allowing real-time measurement of layer thickness and composition without interrupting the deposition workflow. The XRF measurements are performed sequentially during deposition pauses or in real-time, maintaining continuous useful action while achieving high manufacturing precision.
Solution Approach 2:
The patent establishes a feedback loop where XRF measurement data is used to adjust deposition parameters in real-time. This feedback mechanism enables precise control of layer thickness and composition by dynamically modifying deposition conditions based on actual measurements, improving manufacturing precision without requiring multiple trial runs.
3Measurement precision
If real-time XRF measurements are performed during deposition, then measurement accuracy is improved, but device complexity increases due to integration requirements
Solution Approach 1:
The patent merges the XRF measurement system with the epitaxial deposition chamber by positioning the X-ray source and detector within the chamber environment. This integration allows in-situ measurements without requiring separate measurement equipment or additional processing steps, achieving high measurement precision while managing device complexity through unified system design.
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
Ensures accurate layer-to-layer and within-wafer uniformity, preventing defects and enhancing device performance by maintaining strain and improving electron mobility in 3D DRAM devices.
Implementation Method 1
performing an X-ray fluorescence measurement process by exposing the one or more layers to an X-ray fluorescence process. The X-ray fluorescence process determines a thickness of at least one of the one or more layers
Data Source
AI summary
Methods and systems for epitaxial deposition using X-ray fluorescence (XRF) measurements and process control techniques are provided. The method involves performing an epitaxial deposition process to deposit alternating layers of silicon (Si) and silicon germanium (SiGe) on a substrate. XRF measurements determine the thickness and composition of these layers, allowing for precise control over layer thickness and composition. The process helps maintain the targeted strain and prevents defects, improving device performance. The XRF measurements can be performed in-situ or in a transfer chamber, enabling real-time adjustments to the deposition parameters. The method is applicable to various semiconductor devices, including 3D DRAM and gate-all-around (GAA) transistor devices.