Replacement Channel Dopant Gradient for Semiconductor Speed
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Solution Overview
Problem
Existing semiconductor fabrication methods face challenges in achieving high dopant concentration levels in replacement channel materials formed using epitaxial deposition, leading to increased defect density and reduced device speed.
Innovation Solution
A method involving the formation of a channel region, removal of original channel material, and subsequent epitaxial deposition of a dopant-enhanced channel material with a dopant impurity boost, followed by optional annealing, to create a defect-free replacement channel with a gradient of dopant concentration, enhancing transistor speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If epitaxial deposition is used to form replacement channel material with high dopant concentration, then device speed is improved, but defect density increases
Solution Approach 1:
The patent applies preliminary action by first forming the replacement channel material with a lower dopant concentration through epitaxial deposition to ensure low defect density, then subsequently increasing the dopant concentration through a second doping step. This two-stage approach allows the channel to be formed in a defect-free state before the dopant concentration is boosted to the desired level, thereby resolving the contradiction between achieving high device speed (requiring high dopant concentration) and maintaining low defect density.
2Speed
If dopant concentration is increased to provide faster channel speeds, then transistor performance is improved, but material stability deteriorates
Solution Approach 1:
The patent forms the replacement channel material with initial dopant concentration during epitaxial deposition, ensuring stable and defect-free material formation. After the material is stable and defect-free, a subsequent doping step increases the dopant concentration to achieve faster channel speeds. This sequential approach ensures material stability is established before attempting to boost performance through higher dopant concentrations.
Solution Approach 2:
The patent changes the dopant concentration parameter in two distinct stages: first at a lower level during epitaxial deposition to ensure material stability, then at a higher level through a subsequent doping step to achieve faster channel speeds. This parameter change strategy allows the system to benefit from both material stability and high performance.
3Speed
If epitaxial deposition produces high dopant concentration, then device performance is enhanced, but manufacturing precision deteriorates
Solution Approach 1:
The patent segments the dopant concentration formation process into two distinct stages: (1) initial dopant incorporation during epitaxial deposition at a controlled lower concentration, and (2) subsequent dopant concentration enhancement through a separate doping step. This segmentation allows each stage to be optimized independently, with the first stage focusing on precise material formation and the second stage focusing on achieving the target dopant concentration for high-speed operation.
Solution Approach 2:
The patent performs the epitaxial deposition with initial dopant incorporation as a preliminary action before the final dopant concentration enhancement. This preliminary formation step establishes the channel structure with controlled and precise dopant distribution, which is then refined in the subsequent doping step to achieve the final high-performance characteristics.
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 stable, defect-free replacement channel with increased dopant concentration, improving transistor speed and reliability by forming a dopant gradient within the channel material.
Implementation Method 1
Epitaxial deposition methods are favored for producing replacement channels
Implementation Method 2
further doping the replacement channel material with the dopant thereby increasing the average dopant concentration
Implementation Method 3
followed by optional annealing, to create a defect-free replacement channel
Data Source
AI summary
A replacement channel and a method for forming the same in a semiconductor device are provided. A channel area is defined in a substrate which is a surface of a semiconductor wafer or a structure such as a fin formed over the wafer. Portions of the channel region are removed and are replaced with a replacement channel material formed by an epitaxial growth/deposition process to include a first dopant concentration level less than a first dopant concentration level. A subsequent doping operation or operations is then used to boost the average dopant concentration to a level greater than the first dopant concentration level. The replacement channel material is formed to include a gradient in which the upper portion of the replacement channel material has a greater dopant concentration than the lower portion of replacement channel material.