Doped Semiconductor Films via Preferential Etching
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Solution Overview
Problem
Existing techniques for forming highly doped semiconductor regions, such as ion implantation and diffusion doping, often result in undesirable dopant distributions and strain loss due to Gaussian dopant distribution and destruction of crystal structure, limiting the abruptness of junctions and increasing short channel effects.
Innovation Solution
A method involving cyclical deposition and etch (CDE) processes to form semiconductor films with high dopant concentrations, where the semiconductor material is preferentially etched to increase the dopant concentration without adding additional dopants, allowing for well-defined junctions and strain enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion implantation is used to form highly doped semiconductor regions, then dopant can be introduced into the semiconductor, but the crystal structure is destroyed and Gaussian distribution with large straggle limits junction abruptness
Solution Approach 1:
The patent changes the fundamental parameter of dopant introduction from post-deposition implantation to in-situ incorporation during epitaxial growth. This allows dopants to be integrated into the crystal lattice during formation, achieving high concentrations (exceeding 2.5×10^21/cm³) without Gaussian distribution or crystal damage, thus maintaining sharp junction profiles.
Solution Approach 2:
The dopant is incorporated into the semiconductor material during the epitaxial growth process itself, before subsequent processing steps. This preliminary incorporation ensures dopants are positioned precisely where needed in the crystal structure, avoiding later diffusion and straggle effects that degrade junction abruptness.
2Reliability
If high temperature dopant activation is used to activate dopants in doped semiconductor material, then dopants are activated, but dopant distribution becomes less defined and strain is lost
Solution Approach 1:
The patent changes the activation mechanism from thermal activation at high temperatures to in-situ incorporation during low-temperature epitaxial growth. Dopants are activated during the growth process itself at temperatures below 800°C, maintaining sharp junction definitions and preserving strain in the semiconductor structure.
3Quantity of substance
If dopant concentration is increased by adding more dopant, then higher dopant concentration is achieved, but dopant distribution control becomes more difficult and junction abruptness is compromised
Solution Approach 1:
The patent changes from post-growth dopant addition to in-situ dopant incorporation during epitaxial growth. This allows precise control of dopant concentration (exceeding 2.5×10^21/cm³) by controlling growth conditions, maintaining sharp junction profiles even at very high dopant concentrations.
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 achievement of high dopant concentrations exceeding 2.5×10^21/cm^3, providing sharper junctions and minimizing dopant diffusion, thus improving transistor performance by maintaining junction depth profile and abruptness.
Implementation Method 1
preferentially etching a portion of the first semiconductor material relative to the dopant
Implementation Method 2
in situ doping of semiconductor material involves incorporation of desired dopants during deposition
Data Source
AI summary
A method of forming a semiconductor material incorporating an electrical dopant is disclosed. In one aspect, a method of incorporating dopant in a semiconductor film comprises forming a first semiconductor material incorporating the dopant at a first dopant concentration and preferentially etching a portion of the first semiconductor material, wherein etching leaves a first etched semiconductor material incorporating the dopant at a second dopant concentration higher than the first dopant concentration.