Structured Anti-Reflective Coating for Deep Dopant Activation
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Solution Overview
Problem
Conventional laser thermal annealing techniques are limited in activating dopant atoms implanted deeper than 400 nm within semiconductor substrates, resulting in incomplete activation and increased costs for forming doped regions beyond this depth.
Innovation Solution
The use of a structured anti-reflective coating region aligned with deep doped regions in semiconductor bodies, allowing for laser thermal annealing to activate dopant atoms at greater depths with high efficiency and minimal damage, achieved by reflecting less radiation and directing more energy into the semiconductor body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional laser thermal annealing is used to activate dopant atoms, then activation efficiency is high for shallow depths, but activation is incomplete for depths beyond 400 nm
Solution Approach 1:
The patent introduces an anti-reflective coating layer as an intermediary between the laser beam and the semiconductor substrate. This coating layer mediates the interaction by reducing laser reflection and enhancing energy coupling into the substrate, enabling effective thermal annealing of deeply implanted dopant atoms that would otherwise remain inactive
Solution Approach 2:
The patent changes the optical parameters of the semiconductor surface by applying an anti-reflective coating with specific refractive index properties. This parameter change modifies the laser energy absorption characteristics, allowing deeper penetration and more uniform thermal distribution for activating dopants at depths beyond 400 nm
2Length of stationary object
If laser energy is increased to activate deeper dopant atoms, then activation depth improves, but crystalline lattice damage increases
Solution Approach 1:
The anti-reflective coating acts as a protective intermediary that enables efficient energy transfer at lower laser intensities. By reducing reflection losses, the coating allows sufficient thermal energy to reach deep dopant atoms without requiring high laser power that would cause lattice damage
Solution Approach 2:
The patent employs pulsed laser annealing with optimized pulse duration and frequency. This periodic action delivers thermal energy in controlled bursts that accumulate sufficient heat for dopant activation while allowing thermal diffusion to prevent excessive localized temperatures that would damage the crystalline lattice
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 method enables near-perfect activation of dopant atoms (90-99%) at depths beyond 400 nm without increasing laser energy or damaging the crystalline lattice, enhancing the formation of robust semiconductor devices.
Implementation Method 1
A structured anti-reflective coating region is formed on a surface of the semiconductor body. A laser thermal anneal of the deep doped region of the semiconductor body is performed through the anti-reflective coating region thereby activating the implanted dopant atoms in the deep doped region
Implementation Method 2
Laser thermal annealing (LTA) has developed as a promising technique for dopant activation. Generally speaking, laser thermal annealing refers to a technique whereby radiation from a beam of a laser source is directed into a selected portion of a semiconductor body
Implementation Method 3
This is done by annealing the substrate (e.g., at temperatures of 700° C. or higher) to cause the implanted dopant atoms to move into substitutional lattice sites within the semiconductor body
Data Source
AI summary
A semiconductor body having a first surface is provided. A deep doped region of the semiconductor body is formed using masked ion implantation to implant dopant atoms into a discrete region within the semiconductor body. A structured anti-reflective coating region is formed on a portion of the first surface that is aligned with the deep doped region in a lateral direction of the semiconductor body, the lateral direction being parallel to the first surface. A laser thermal anneal of the deep doped region of the semiconductor body is performed through the anti-reflective coating region thereby activating the implanted dopant atoms in the deep doped region.