Method and system for diffusion and implantation in gallium nitride based devices

#Power electronics are widely used in a variety of applications. Power electronic devices are commonly used in circuits to modify the form of electrical energy, for example, from ac to dc, from one voltage level to another, or in some other way. Such devices can operate over a wide range of power levels, from milliwatts in mobile devices to hundreds of megawatts in a high voltage power transmission system. Despite the progress made in power electronics, there is a need in the art for improved electronics systems and methods of operating the same.

#The present invention relates generally to electronic devices. More specifically, the present invention relates to methods and systems for fabricating electronic devices using implantation and/or diffusion processes. Merely by way of example, the invention has been applied to GaN-based diodes and transistors with implanted and diffused p-n junctions. The methods and techniques can be applied to a variety of compound semiconductor systems including diodes and transistors.

#According to an embodiment of the present invention, a method of forming a doped region in a III-nitride substrate is provided. The method includes providing the III-nitride substrate. The III-nitride substrate is characterized by a first conductivity type. The method also includes forming a masking layer having a predetermined pattern and coupled to a portion of the III-nitride substrate. The predetermined pattern defines exposed regions of the III-nitride substrate. The method further includes heating the III-nitride substrate to a predetermined temperature and placing a dual-precursor gas adjacent the exposed regions of the III-nitride substrate. The dual-precursor gas includes a nitrogen source and a dopant source. Additionally, the method includes maintaining the predetermined temperature for a predetermined time period, forming p-type III-nitride regions adjacent the exposed regions of the III-nitride substrate, and removing the masking layer.

#FIG. 1 is a simplified schematic diagram illustrating a conventional Schottky barrier diode.

#FIG. 2 is a simplified schematic diagram illustrating a conventional p-n junction diode.

#FIGS. 3A-3C are simplified process flow diagrams illustrating a vapor-phase diffusion process according to an embodiment of the present invention;

#Embodiments of the present invention relate to electronic devices. More specifically, the present invention relates to methods and systems for fabricating electronic devices using implantation and/or diffusion processes. Merely by way of example, the invention has been applied to GaN-based diodes and transistors with implanted and diffused p-n junctions. The methods and techniques can be applied to a variety of compound semiconductor systems including diodes and transistors.

#Some III-nitride devices form p-n junctions during the epitaxial growth process as materials with differing conductivity types are epitaxially grown. This can be achieved by introducing a precursor of a p-type dopant species during growth of a layer immediately over the surface of an n-type layer, providing an interface/junction that is substantially planar. The performance and reliability of electronic and optoelectronic devices may be improved by the formation of lateral p-n junctions, however, the high temperatures utilized in some semiconductor doping processes, including diffusion or implantation, present difficult issues related to performing such semiconductor doping processes in III-nitride based materials including GaN. Thus, embodiments of the present invention provide diffusion and implantation doping processes that allow for the formation of lateral p-n junctions in III-nitride materials including GaN. Past attempts to diffuse and implant dopants into III-nitride materials have met with limited success because the high temperatures associated with diffusing and annealing implanted species have resulted in the decomposition of the III-nitride substrates, due, in part, to the high vapor pressure of the nitrogen components of the nitride materials.

#As described more fully throughout the present specification, a number of fundamental device structures benefit from the processes provided by embodiments of the present invention. Just by way of example, devices that can benefit from the processes described herein include Schottky barrier diodes and p-n junction diodes, which are basic elements in power electronics. Both Schottky barrier diodes and p-n junction diodes are two-terminal devices. Additionally, three-terminal devices, including FETs, can benefit from the processed described herein.