SiGe/Si Stacked Structures With Sharp Interface Layer Control
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Solution Overview
Problem
The formation of semiconductor stacked structures with alternating SiGe and Si layers faces challenges due to surface passivation issues and inadequate temperature control during deposition, leading to undesirable interface layers with excessive thickness and composition variations.
Innovation Solution
A method involving feedback-controlled temperature regulation across the substrate surface during sequential deposition, using independent optical temperature measurements to throttle heating and maintain a consistent temperature profile, along with the introduction of transition gases to passivate the surface and prevent germanium segregation, resulting in sharp and abrupt interface layers with reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface passivation is not correctly performed prior to Si layer deposition, then germanium segregation occurs at the SiGe/Si interface, but implementing proper passivation with transition gas introduction adds process complexity and time
Solution Approach 1:
The patent applies preliminary action by introducing a transition gas (such as HCl or silane) before depositing the Si layer to pre-passivate the SiGe surface. This preliminary chemical treatment prevents germanium segregation during subsequent Si deposition, ensuring a sharp interface without requiring complex in-situ passivation layers. The transition gas treatment is performed as a preparatory step that eliminates the need for additional passivation process steps.
Solution Approach 2:
The patent uses an intermediary substance (transition gas) that mediates between the SiGe layer and the Si layer deposition. The transition gas (HCl, silane, or other precursor gases) temporarily modifies the SiGe surface chemistry to prevent Ge segregation, acting as a chemical intermediary that facilitates the formation of a sharp interface without requiring direct contact between SiGe and Si during the critical interface formation stage.
2Manufacturing precision
If temperature gradients are not controlled during deposition, then layer composition and thickness uniformity deteriorate, but implementing feedback control with multiple pyrometers increases device complexity
Solution Approach 1:
The patent applies local quality by using multiple pyrometers positioned at different locations on the substrate surface to measure temperature independently at each zone. The control system then adjusts heating elements locally to maintain uniform temperature across different regions of the substrate, ensuring consistent deposition conditions and uniform layer properties throughout the entire substrate area.
Solution Approach 2:
The patent implements feedback control by continuously monitoring substrate temperature with pyrometers and using the measured temperature data to dynamically adjust the power supplied to heating elements. The control system compares actual temperature readings with target temperature values and modifies heating in real-time to maintain precise temperature control, ensuring uniform layer deposition across the substrate surface.
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 enables the formation of high-quality semiconductor stacked structures with interface layers thinner than 10 Angstroms, improving the precision and uniformity of layer transitions and composition, suitable for advanced three-dimensional device fabrication.
Implementation Method 1
acquiring at least two independent sets of optical temperature measurements from at least two separate areas on the upper surface of the substrate
Implementation Method 2
heating the substrate to a deposition temperature employing an upper heater element array supported above the upper wall of the chamber body
Implementation Method 3
introducing a transition gas into the chamber body to passivate an exposed surface of the first layer
Implementation Method 4
introducing a first precursor gas into the chamber body to epitaxially deposit a first layer comprising silicon and germanium on the substrate
Data Source
AI summary
Methods for forming semiconductor stacked structures are disclosed. The methods may include, seating a substrate within a chamber body, and regulating a temperature profile across an upper surface of the substrate during each individual step of a sequential deposition process. Semiconductor stacked structures including two or more bilayers of SiGe/Si with intervening interface layers are also disclosed.