Co-doped SiC Semiconductor Device Resistance Reduction

The patent combines p-type and n-type doping into a single co-doping process, introducing both Al and N impurities simultaneously during crystal growth. This merging of doping functions achieves resistance reduction through the synergistic effect of Al (providing holes) and N (forming shallow donor levels when paired with Al), while maintaining manufacturing simplicity by performing both doping operations in one integrated process step rather than separate sequential steps.

The patent creates a composite doped structure in SiC by introducing two different types of impurities (Al and N) that form specific pair structures (Al-N pairs) within the crystal lattice. This composite approach at the atomic level allows the material to exhibit enhanced electrical properties that neither impurity alone could achieve, specifically lowering resistance through the formation of shallow donor levels by N when paired with Al acceptors.

The patent merges p-type Al doping and n-type N doping into a co-doping scheme where both impurities are introduced together at concentrations that would individually exceed solubility limits. The Al and N atoms form stable pair structures (Al-N pairs) within the SiC lattice, allowing higher total impurity concentrations to be incorporated without creating excessive crystal defects, thereby achieving high carrier concentration while maintaining crystal stability.

The patent uses N impurity atoms as intermediaries that form pair structures with Al atoms. These Al-N pair structures act as mediators that stabilize the crystal lattice when high concentrations of impurities are present. The N atoms in these pairs create shallow donor levels that contribute to carrier concentration while the paired structure itself stabilizes the composition, preventing excessive crystal defects that would otherwise occur at such high doping levels.

The patent applies preliminary action by pre-establishing the co-doping mechanism and Al-N pair formation principles before actual device manufacturing. The solubility enhancement and resistance reduction effects are achieved through this pre-planned co-doping strategy, which simplifies the overall process compared to attempting to achieve the same results through multiple separate doping steps or post-growth treatments.

The patent merges the functions of increasing solubility and reducing resistance into a single co-doping operation. By introducing Al and N simultaneously during crystal growth, the process achieves both objectives together: the Al-N pair structures increase the effective solubility limit for impurity incorporation while the formation of shallow donor levels by N and hole contribution by Al work synergistically to reduce resistance, all within one integrated doping process step.