Multilayer Epitaxy With Feedback Temperature Uniformity
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Solution Overview
Problem
Conventional methods for selectively depositing highly strained and/or highly doped semiconductor materials on substrates are complex due to interactions among process parameters, making it challenging to achieve uniform deposition across the entire substrate surface while preventing deposition on non-crystalline surfaces.
Innovation Solution
A multiphase deposition process with precise temperature control using a feedback system, employing multiple pyrometers to monitor temperature uniformity and throttle heating, allows for the selective epitaxial deposition of multilayer structures with uniform boron concentration and strain levels, favoring crystalline surfaces over non-crystalline ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If selective deposition processes are used to deposit highly strained and/or highly doped materials, then material properties are improved, but process complexity increases enormously
Solution Approach 1:
The deposition process is divided into multiple sequential phases (first deposition phase, second deposition phase, third deposition phase), each depositing a specific layer (first SiGe:B layer, second SiGe:B layer, Si:B layer) with controlled properties. This segmentation allows complex multilayer structures to be formed through simpler, more controllable individual deposition steps rather than attempting to deposit all layers simultaneously.
Solution Approach 2:
The process employs systematic changes in deposition parameters across different phases, including temperature control (heating substrate to deposition temperature), pressure variations, and gas flow rate adjustments. These parameter changes enable precise control over material properties such as strain levels and dopant concentrations while maintaining process manageability.
2Manufacturing precision
If uniform selective deposition is maintained across the entire substrate surface, then deposition uniformity is improved, but process control complexity increases
Solution Approach 1:
The process implements a feedback control system using pyrometers to monitor substrate temperature during deposition. The pyrometers provide real-time temperature measurements, and the controller adjusts heating power based on these measurements to maintain uniform temperature across the substrate surface. This feedback mechanism ensures uniform deposition conditions without requiring overly complex manual control.
Solution Approach 2:
The process aims to create equipotential conditions across the substrate surface by maintaining uniform temperature distribution during deposition. By controlling the substrate temperature to be substantially uniform across the entire surface, the process ensures consistent deposition conditions for all areas of the substrate, achieving uniform material properties without requiring different parameters for different regions.
3Reliability
If highly doped source and drain regions are used, then contact resistance is reduced, but device performance uniformity becomes more challenging to maintain
Solution Approach 1:
The multilayer structure incorporates regions with different dopant concentrations and material compositions tailored to specific locations and functions. The source and drain regions have high dopant concentrations to reduce contact resistance, while other regions maintain different properties for their specific functions. This local optimization of material properties achieves both low contact resistance and uniform device performance across different device regions.
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 method achieves highly uniform and strained multilayer structures with low boron concentration non-uniformity, suitable for semiconductor transistor devices, ensuring optimal performance and uniformity across the substrate.
Implementation Method 1
a first pyrometer and a second pyrometer, the first pyrometer and the second pyrometer being supported above the upper heater element array and being optically coupled to the substrate surface
Implementation Method 2
heating the substrate to a deposition temperature employing at least an upper heater element array supported above the upper wall of the chamber body
Implementation Method 3
epitaxially depositing a first SiGe:B layer over the substrate during a first deposition phase, epitaxially depositing a fully strained second SiGe:B layer directly over the first SiGe:B layer
Data Source
AI summary
Methods for forming multilayer 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 deposition phase of multiphase deposition process. Semiconductor device structures including multilayer structures are also disclosed.