Introduction

Method for manufacturing an electronic device comprising wide bandgap semiconductor, dopant species implanted in selected regions, and annealing of the implanted region. This annealing is carried out by laser radiation exposure of a coating of absorbing material deposited on implanted regions which, during the exposure time, is subjected to erosion to allow at least part of the laser radiation to reach the surface of the underlying implanted regions.

Technical features

The initial thickness of the heat-absorbing layer is selected based on the energy density of the laser radiation, such that it is sufficient to prevent the laser radiation from reaching the semiconductor surface. During the first step of the laser heat treatment process, a gradual recovery of the optical and thermodynamic parameters of the implanted semiconductor region is achieved by diffusion of heat from the heat-absorbing coating layer which is gradually eroded by exposure to the laser radiation, until the optical contact with laser radiation is tolerated by the implanted semiconductor zones and the heat treatment can be carried out to the deeper implanted regions. The thermoabsorbent material is any material with melting temperature higher than the melting temperature of the semiconductor, optical extinction coefficient k equal to or greater than 0.2 and reflectance lower than 5%, selected among amorphous carbon, graphite, TaC, HfC, ZrC, HfC , TaB₂, ZrB₂, or HfB₂. The actual TRL is 3-4.

Possible Applications

• Thermal treatment of source and body implants for power MOSFETs;
• Silicide formation;
• Edge junction termination heat treatment;
• Thermal treatment of selectively implanted wide bandgap semiconductor regions.

Advantages

• Full activation of the implanted dopant;
• Protection against surface degradation during laser annealing treatment;
• Selective annealing of the implanted regions;
• Reduced resistance of drift regions in power MOSFETs;
• Improved on-state resistance in power devices;
• Speed up of the post-implantation thermal annealing process.