Semiconductor Source/Drain Junction Extension via In-Situ Doping
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Solution Overview
Problem
As semiconductor technology scales down, particularly at 22 nm or beyond, the challenge is to achieve a source/drain junction extension with high doping concentration and low junction depth to mitigate the short-channel effect and reduce series resistance, which existing methods like ultra-low-energy implantation and high-energy transient laser annealing struggle to address effectively.
Innovation Solution
The method involves forming a trench on both sides of a gate stack and using epitaxial growth with in-situ doping to create a source/drain junction extension, allowing for precise control of junction depth and doping concentration, thereby improving semiconductor structure performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the junction depth of the source/drain junction extension is decreased to curb the short-channel effect, then the short-channel effect is suppressed, but the series resistance increases
Solution Approach 1:
The patent applies local quality by creating a source/drain junction extension with non-uniform doping concentration distribution. The doping concentration is highest at the interface with the channel and decreases towards the drain, forming a graded structure. This local variation in doping concentration allows the junction to simultaneously achieve low series resistance at the channel interface and adequate junction depth control, resolving the contradiction between suppressing short-channel effects and maintaining low resistance.
Solution Approach 2:
The patent employs parameter changes by utilizing in-situ doping during selective epitaxial growth to achieve precise control over doping concentration and junction depth. By adjusting doping parameters during the epitaxial process, the method creates a graded doping profile that optimizes both the electrical characteristics (low resistance) and the structural characteristics (junction depth) of the source/drain extension, thereby resolving the technical contradiction.
2Length of stationary object
If ultra-low-energy implantation is used to reduce junction depth, then the junction depth is reduced, but the doping concentration activation becomes difficult
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical epitaxial growth process for doping. Instead of physically implanting ions into the semiconductor lattice, the method uses in-situ doping during selective epitaxial growth, where dopants are incorporated chemically during the crystal growth process. This substitution enables precise control of both junction depth and doping concentration activation, overcoming the limitations of ultra-low-energy implantation.
Solution Approach 2:
The patent changes the fundamental parameter of the doping process by transitioning from post-growth implantation to in-situ doping during epitaxial growth. This parameter change allows simultaneous control of doping concentration and junction depth through process conditions such as temperature, pressure, and dopant flow rate, effectively resolving the contradiction between achieving low junction depth and maintaining high doping concentration activation.
3Quantity of substance
If high-energy transient laser annealing is applied to enhance activation concentration, then the activation concentration is enhanced, but the process complexity and difficulty increase
Solution Approach 1:
The patent extracts and eliminates the complex laser annealing step from the manufacturing process. By using in-situ doping during selective epitaxial growth, the method achieves high doping concentration activation directly during the growth process itself, without requiring subsequent high-energy laser annealing treatments. This extraction of the laser annealing step significantly reduces process complexity while maintaining effective doping activation.
Solution Approach 2:
The patent implements self-service by enabling the doping and activation process to occur simultaneously during the epitaxial growth itself. The in-situ doping mechanism allows dopants to be incorporated and activated in a single integrated process step, eliminating the need for separate annealing operations. This self-service approach reduces process complexity and improves manufacturing efficiency while achieving the desired activation concentration.
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 a semiconductor structure with high doping concentration and low junction depth, effectively enhancing device performance by reducing parasitic resistance and improving mobility.
Implementation Method 1
forming a source/drain junction extension in the trench by epitaxial growth and in-situ doping
Implementation Method 2
forming a source/drain junction extension in the trench by epitaxial growth and in-situ doping
Data Source
AI summary
The present invention provides a semiconductor structure comprising a substrate; a gate stack on the substrate; a spacer on the sidewalls of the gate stack; a source/drain junction extension formed in the substrate on both sides of the gate stack by epitaxial growth; and a source/drain region in the substrate on both sides of the source/drain junction extension. Accordingly, the present invention also provides methods for manufacturing the semiconductor structure. The present invention can provide a source/drain junction extension with a high doping concentration and a low junction depth, thereby effectively improving the performance of the semiconductor structure.