TECHNICAL POINT OF CONTACT (TPOC)
Dmitry Ruzmetov
Nicholas Jankowski
Tony Ivanov
PROJECTED CMMC LEVEL REQUIREMENT
Level 2 (Self)
TECHNOLOGY AREAS
None
MODERNIZATION PRIORITIES
Microelectronics
|
Quantum Science
KEYWORDS
Diamond Transistors, Charge Trapping, Current Collapse, Semiconductor Metrology, Ultra-Wide Bandgap (UWBG), RF Power Electronics, Defect Dynamics, Surface-Channel Devices, Hydrogen-terminated Diamond.
OBJECTIVE
Develop an innovative, non-destructive diamond semiconductor defect metrology technique and laboratory-scale apparatus to identify, quantify, determine location in the device, and energetically characterize charge traps that cause current collapse in surface-channel diamond transistors.
DESCRIPTION
Hydrogen-terminated (surface-channel) diamond transistors hold great promise for next-generation, high-frequency, high-power RF electronics and advanced communications due to diamond's high breakdown field and superior thermal conductivity. However, wide-scale operational deployment is constrained by "current collapse" and "knee walkout" - phenomena where transient charges trapped at defect sites in the semiconductor prevent the transistor from operating at its full, high-frequency RF power. Commercial device-characterization tools, built primarily for silicon or traditional compound semiconductor materials, lack the specialized physics and sensitivity required to isolate and characterize traps in ultra-wide bandgap (UWBG) diamond devices. These performance-limiting charge traps can reside in multiple distinct, critical locations within the device stack, including the gate dielectric, the dielectric-to-diamond interface, the diamond epitaxial layer, the epitaxial-to-substrate interface, and the diamond bulk substrate. Understanding and mitigating these mechanisms requires a specialized metrology capability. This topic seeks the development of a comprehensive measurement system and associated methodology capable of extracting trap density, energy levels, physical location (specifically identifying the layers or interfaces where the traps reside), and time constants characterizing these defects so that design teams can efficiently work to address them.
Standard capacitance-voltage (CV) or simple transient electrical analyses do not provide sufficient physical insight into trap dynamics. Specifically, a successful technique and system must be capable of resolving multiple trap populations and correlating these distinct signatures with observed current collapse behavior in diamond. Because hydrogen-terminated diamond relies on unique surface-channel p-type conduction, validation of these new techniques can not necessary rely on prior validation from conventional n-type semiconductor materials (e.g., GaN, Ga2O3, AlN), as the fundamentally different physical mechanisms and device architectures may not be acceptable surrogates for the diamond device behavior.
To meet operational requirements, all primary experimental validations and core metrology capability demonstrations under this effort must be performed specifically on Government-provided hydrogen-terminated diamond material and RF transistor devices. The Government will provide these verified working devices and/or test articles as Government Furnished Property (GFP) during the execution phase to anchor the research. The public literature contains examples of hydrogen-terminated diamond RF transistors that exhibit comparable baseline characteristics [1, 2]. While the GFP will vary in specific design, architecture, and properties from the literature, they can provide a baseline for concept development. It is expected that preliminary or intermediate metrology demonstrations on other wide or ultra-wide bandgap semiconductor devices may be used for initial development, the main and final capability demonstrations must be validated directly on the specific diamond device architectures provided. This effort will address a critical metrology gap, establishing a validated metrology standard that accelerates the development of high-reliability diamond RF electronics.
PHASE I
Conduct a 6-month study to establish the scientific and technical feasibility of the proposed defect metrology technique. The performer shall describe the measurement process, provide sound scientific arguments justifying the approach's ability to meet the project objectives of trap identification and measurement, and describe the hardware equipment requirement needed to perform the measurement. Expected means to demonstrate feasibility include preliminary experimental demonstrations, a review of relevant existing techniques used on other types of semiconductors, and supporting modeling or simulations.
In alignment with the overall topic objective, while initial benchtop calibration may utilize other wide bandgap materials, the core Phase I feasibility demonstration must be applied specifically to hydrogen-terminated diamond architectures. To facilitate this early validation, the Government will provide representative diamond test structures as Government Furnished Property (GFP).
Phase I Deliverables:
i. A comprehensive feasibility study report detailing the proposed metrology process, scientific justification, and measurement equipment used for the approach.
ii. Initial feasibility data (derived from preliminary experimental demonstrations, literature review of relevant semiconductor techniques, or modeling) supporting the viability of the technique for surface-channel p-type architectures.
iii. A detailed Phase II transition plan outlining the schedule, testing procedures, and integration strategy for validating the prototype instrument on the provided diamond devices.
PHASE II
Develop, construct, and validate a fully functional prototype, laboratory-scale, trap metrology instrument based on the Phase I design. The performer is expected to demonstrate the system's ability to successfully isolate and distinguish between different trap locations (e.g., gate-dielectric interface vs. bulk epitaxial layer) and correlate these signatures with measured RF current collapse on hydrogen-terminated diamond transistors, which will continue to be provided as GFP by the Government. The performer is expected to continue refining the technique developed in Phase 1 incorporating those refinements into the prototype.
The principal milestone of the Phase II effort is the validation of the developed hardware and measurement methodology at the performer's facility. For this effort, "validation" is explicitly defined as the successful identification, characterization, and physical location attribution of the specific charge traps responsible for current collapse and similar detrimental effects in the provided diamond transistors. Following this successful demonstration, the complete, operational prototype measurement system, including all associated hardware, specialized instrumentation, and software, will be provided as a deliverable to the Government.
Phase II Deliverables:
i. Prototype System Validation & Hardware Transfer: Successful demonstration of the developed technique and hardware's ability to identify, locate, and quantitatively characterize (specifically provide numerical values for trap density, energy levels, time constants, etc.) the specific traps responsible for current collapse and other detrimental effects in the GFP diamond devices, as well as delivery of the fully operational prototype defect metrology test instrumentation to the Government.
ii. Documentation & Training: A comprehensive Standard Operating Procedure (SOP) manual containing step-by-step measurement instructions tailored specifically to the provided diamond RF devices, accompanied by hands-on training for Government personnel.
iii. Final Report: A technical report detailing the identified trap signatures on the GFP devices, the methodology used to correlate these measurements to observed RF performance loss, detailed procedures by which the prototype tool can be used to reproduce the validation results on GFP devices, details of any identified limitations of the technique or system related to the desired function, including any identified material or processing mitigation options related to those limitations.
PHASE III DUAL USE APPLICATIONS
Military Application: The delivered measurement technique will be used to analyze, optimize, and validate the reliability of high-power diamond transistors. US Army DEVCOM is presently developing diamond transistor devices for the next generation of advanced military sensing, high-frequency communications, and broad-spectrum electromagnetic platforms. Successful outcomes of this research and development program will result in laboratory techniques and supporting equipment necessary to continue development of this technology. It is expected that the technology will become a standard metrology technique within DEVCOM electronic device laboratories and among the Defense Industrial Base partners with semiconductor foundries presently being engaged in this development.
Commercial Application: The performing small business can commercialize the diagnostic system design, measurement software, and procedural methodology to support the emerging domestic commercial diamond semiconductor industry. This highly specialized metrology capability will be valuable to domestic and allied commercial foundries manufacturing advanced diamond electronics to improve device reliability and manufacturing yield for commercial 5G/6G telecommunications, commercial satellite communications (SatCom), commercial radar systems, and high-frequency communication systems requiring advanced thermal management. Because this metrology system is designed to evaluate high-power, semiconductor technologies, some of which fall under ITAR or CCL export-controls, all commercialization, licensing, and replication services will need to comply with U.S. export control laws (ITAR/EAR). While this may limit certain commercial markets, it also has the potential to establish higher exclusivity within controlled markets.
REFERENCES
C. Yu, C. Zhou, J. Guo, Z. He, M. Ma, H. Yu, X. Song, A. Bu, and Z. Feng, "Hydrogen-terminated diamond MOSFETs on (0 0 1) single crystal diamond with state of the art high RF power density," Functional Diamond, vol. 2, no. 1, pp. 64-70, 2022.
X. Yu, W. Hu, J. Zhou, et al., "1.26 W/mm Output Power Density at 10 GHz for Si3N4 Passivated H-Terminated Diamond MOSFETs," IEEE Transactions on Electron Devices, vol. 68, no. 10, pp. 5068-5072, Oct. 2021.
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