Dielectric Mirror for Laser Annealing in MOS Devices
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Solution Overview
Problem
The manufacturing of large-scale integration MOS devices faces challenges in achieving ultra-shallow junctions and efficient dopant activation due to high thermal budgets and the risk of deformation from high-energy laser irradiation, which affects the electrical performance and structural integrity of the devices.
Innovation Solution
A dielectric mirror, such as a Bragg reflector, is used to reflect laser radiation during the annealing process, preventing damage to the MOS device structure while allowing for high-energy irradiation to achieve complete defect removal, and also serves as an electrical insulation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-energy laser irradiation is used to achieve complete defect removal and shallow junctions, then manufacturing precision and dopant activation are improved, but structural deformation and device damage occur
Solution Approach 1:
A dielectric mirror layer is introduced as an intermediary component between the laser source and the MOS device structure. This mirror reflects the laser beam to selectively anneal source/drain regions while protecting other sensitive structures from direct laser exposure, thereby preventing structural deformation while achieving complete defect removal in the target areas
Solution Approach 2:
The patent applies selective annealing to different regions of the MOS device with different laser energies. The dielectric mirror enables local high-energy irradiation on source/drain regions for complete defect removal, while other regions receive reduced or no laser exposure, maintaining their structural integrity and avoiding unnecessary deformation
2Reliability
If conventional thermal annealing is used to activate dopants, then device structure stability is maintained, but manufacturing precision and dopant activation efficiency are insufficient
Solution Approach 1:
The patent transitions from conventional thermal annealing parameters (high temperature, long duration) to laser annealing parameters (high energy density, short duration). The dielectric mirror enables precise control of laser energy delivery, achieving complete dopant activation and defect removal in ultra-shallow junctions while maintaining overall device structure stability through selective and localized heating
3Manufacturing precision
If high-energy laser irradiation is applied to source/drain regions, then complete annealing of implantation defects is achieved, but gate structures and other sensitive areas suffer damage
Solution Approach 1:
The dielectric mirror serves as a protective intermediary that redirects laser energy away from sensitive gate structures. By positioning the mirror to reflect the laser beam, the patent enables complete defect annealing in source/drain regions while the gate structures are shielded from direct high-energy irradiation, preventing damage and maintaining device functionality
Solution Approach 2:
The patent segments the laser irradiation process into distinct zones: source/drain regions receive high-energy laser exposure for complete defect removal, while gate structures and channel regions are excluded from direct laser exposure through the dielectric mirror's reflective geometry, achieving selective annealing without cross-contamination or damage
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 production of MOS devices with complete annealing of implantation defects, preventing structural deformation and ensuring precise control over dopant diffusion, thereby improving the electrical characteristics and repeatability of the manufacturing process.
Implementation Method 1
A dielectric mirror, such as a Bragg reflector, is used to reflect laser radiation during the annealing process
Implementation Method 2
excimer-laser irradiation techniques for local heating and possibly melting of silicon regions to enable rapid diffusion and activation of dopant atoms
Implementation Method 3
During melting, the crystallographic defects due to ion implantation are completely eliminated, and dopants diffuse rapidly within the molten region
Data Source
AI summary
A process for manufacturing a MOS device and the MOS device manufactured thereby are disclosed. The process includes in a semiconductor layer forming a gate structure above the semiconductor layer; forming a first doped region within a first surface portion of the semiconductor layer; and irradiating the first doped region with electromagnetic radiation, to carry out annealing thereof. Prior to the irradiating step, a dielectric mirror is formed above a second surface portion of the semiconductor layer. The dielectric mirror, which may be of the Bragg-reflector type, reflects at least in part the electromagnetic radiation, and protects underlying regions from the electromagnetic radiation.