Single-Chamber HCl Etch and Low-Temp Epitaxy for Raised Source-Drain
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Solution Overview
Problem
Existing semiconductor fabrication processes for raised source-drain structures face challenges in achieving a clean interface surface while minimizing dopant diffusion, requiring a trade-off between interface quality and thermal budget.
Innovation Solution
A process that uses a single process chamber for both etching and epitaxial growth, employing a controlled atmosphere and hydrochloric acid etching at a temperature below 800°C to remove damaged surface layers, followed by cyclical epitaxial growth without breaking the vacuum, to form raised source-drain structures with minimal dopant diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high temperature pre-bake process (at or exceeding 800°C) is performed to prepare the interface surface for epitaxial growth, then the interface quality is improved, but significant dopant diffusion occurs
Solution Approach 1:
The patent changes the temperature parameter from high (800°C or above) to low (below 800°C) while maintaining the beneficial effect of interface preparation through a different mechanism - using in-situ etching to remove damaged surface layers rather than relying on thermal diffusion. This parameter change resolves the contradiction by achieving interface quality improvement without the harmful dopant diffusion associated with high temperatures.
Solution Approach 2:
The patent extracts the high temperature step from the process sequence entirely. Instead of performing a high temperature pre-bake to prepare the interface, the damaged surface layers are removed through in-situ etching at lower temperatures, and the interface is prepared through controlled atmosphere conditions during the epitaxial growth process itself, eliminating the need for high thermal budget processing.
2Manufacturing precision
If multiple process chambers are used for etching and epitaxial growth, then the interface surface quality can be improved through separate optimization, but the process complexity and thermal budget increase
Solution Approach 1:
The patent merges the etching and epitaxial growth processes into a single process chamber, allowing both operations to be performed in-situ without breaking vacuum. This consolidation achieves interface surface quality improvement while reducing process complexity by eliminating the need for multiple chamber transitions and separate process optimizations.
Solution Approach 2:
The single process chamber is designed to perform multiple functions - both etching and epitaxial growth - within the same controlled atmosphere. This multi-functional approach allows the chamber to provide both the damaged layer removal and the interface preparation functions that would otherwise require separate specialized chambers, reducing overall system complexity.
3Manufacturing precision
If multiple process chambers are used with vacuum breaks between steps, then each process can be independently optimized, but the overall processing time increases
Solution Approach 1:
The patent maintains continuous vacuum conditions throughout the entire process sequence, allowing etching and epitaxial growth to proceed without interruption or vacuum breaks. This continuous action eliminates the time losses associated with chamber evacuation and repressurization cycles, while still achieving precise process control through in-situ monitoring and control of the controlled atmosphere conditions.
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 results in a seamless interface with reduced dopant diffusion and improved transistor performance, characterized by lower leakage and resistance, and better electrostatics, without the need for a high thermal budget pre-bake.
Implementation Method 1
performing an etch with hydrochloric acid to remove the damaged surface layers
Implementation Method 2
drawing substantially a vacuum within the process chamber
Implementation Method 3
performing an in-situ epitaxial growth to grow, from the exposed interface surface, a raised source-drain structure
Data Source
AI summary
A raised source-drain structure is formed using a process wherein a semiconductor structure is received in a process chamber that is adapted to support both an etching process and an epitaxial growth process. This semiconductor structure includes a source region and a drain region, wherein the source and drain regions each include a damaged surface layer. The process chamber is controlled to set a desired atmosphere and set a desired temperature. At the desired atmosphere and temperature, the etching process of process chamber is used to remove the damaged surface layers from the source and drain regions and expose an interface surface. Without releasing the desired atmosphere and while maintaining the desired temperature, the epitaxial growth process of the process chamber is used to grow, from the exposed interface surface, a raised region above each of the source and drain regions.