Helium Implantation for Damage-Free Dopant Diffusion
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Solution Overview
Problem
Conventional doping methods for semiconductor devices, such as ion implantation, cause residual damage and are limited by thermal budget considerations, making it difficult to achieve effective dopant incorporation and activation in small-scale devices.
Innovation Solution
A method involving helium implantation at elevated temperatures (above 300°C) followed by deposition of a thin dopant layer and high-temperature annealing, which promotes dopant diffusion and activation without introducing residual defects, using a system with integrated chambers for helium implantation, dopant deposition, and annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion implantation is used for doping, then dopant can be incorporated into the substrate, but residual damage is caused to the substrate structure
Solution Approach 1:
The patent extracts the harmful ion implantation step and replaces it with a different mechanism. Instead of using ion implantation to introduce dopants, the invention uses thermal diffusion from a deposited dopant layer, thereby achieving dopant incorporation without the residual damage caused by ion bombardment
Solution Approach 2:
The patent replaces the mechanical ion implantation process with a thermal diffusion process. Instead of mechanically forcing ions into the substrate, the invention uses thermal energy to drive dopant atoms from the deposited layer into the substrate, eliminating the mechanical damage associated with ion implantation
2Object-affected harmful factors
If thermally-driven outdiffusion from a deposited layer is used, then dopant can be incorporated without damage, but the amount of dopant incorporated and activation is limited by thermal budget considerations
Solution Approach 1:
The patent changes the thermal parameters by implementing a rapid thermal annealing process with very high temperatures (900-1100°C) for extremely short durations (0.1-10 seconds). This allows sufficient dopant incorporation and activation without excessive thermal budget that would cause diffusion beyond the desired region
Solution Approach 2:
The patent uses a periodic rapid thermal annealing process where the substrate is quickly heated to high temperature for a brief period and then rapidly cooled. This periodic heating and cooling enables controlled dopant diffusion with precise spatial and temporal limits, overcoming the limitations of conventional thermal budget constraints
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 enhances dopant diffusion and activation, achieving higher dopant concentrations and lower sheet resistance, while avoiding residual damage and defects, thus improving the scalability and performance of semiconductor devices.
Implementation Method 1
implanting a dose of a helium species into the substrate through a surface of the substrate at an implant temperature of 300° C. or greater
Implementation Method 2
annealing the substrate at an anneal temperature, the anneal temperature being greater than the implant temperature
Implementation Method 3
annealing the substrate at an anneal temperature greater than 600° C.
Data Source
AI summary
A method of doping a substrate. The method may include implanting a dose of a helium species into the substrate through a surface of the substrate at an implant temperature of 300° C. or greater. The method may further include depositing a doping layer containing a dopant on the surface of the substrate, and annealing the substrate at an anneal temperature, the anneal temperature being greater than the implant temperature.