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Ultra-High Voltage Insulated Gate Bipolar Transistor on Silicon Carbide


OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Develop an ultra-high voltage (UHV) insulated gate bipolar transistor (IGBT) on silicon carbide (SiC) technology with high reliability and yield so that these devices may be produced in a high volume manufacturing setting. DESCRIPTION: Despite nearly three decades of research and development (R&D) efforts into SiC power devices, commercial SiC power transistors with voltage ratings greater than 1.7kV are not widely available. Despite significant R&D investments, a fully-qualified, commercially-available, greater than 6.5kV rated SiC power transistor has remained elusive [1-7]. On the other hand, there is an increased demand for UHV SiC power transistors, especially SiC IGBTs, for mission critical applications in both defense and commercial sectors. Other semiconductor materials (e.g., GaN) have been studied for their applicability in the UHV market, yet SiC has emerged as the material of choice for its UHV capabilities and enhanced thermal conductivity [2, 3, 5]. At present, there are very few manufacturing sources within the U.S. that can produce UHV SiC technologies [2, 5]. In addition, the manufacturing challenges associated with UHV SiC devices has hindered its adoption and advancement in the semiconductor industry. For example, in order to achieve ultra-high blocking voltages (e.g., >15kV), manufacturers must produce or procure SiC substrates with ultra-thick (>100um) SiC epilayers [3 – 7]. Ultra-thick SiC epilayers suffer from high basal plane defect (BPD) levels, especially if appropriately thick (>3um) buffer layers are not employed in the epi structure [5]. It is extremely important to tightly control the density of BPDs in the epilayers procured for device fabrication. It is imperative that an UHV SiC power transistor be developed to meet the UHV and switching speed requirements in mission critical systems. A SiC IGBT is an ideal candidate to meet this demand signal. The proposed SiC IGBT must be produced on 150mm SiC substrates to facilitate high volume manufacturing, demonstrate a blocking voltage greater than 20kV, possess a current rating of at least 15A, threshold voltage Vth ~3.0V, and <500ns switching times at 80% of rated breakdown voltage. Form factor, ideally, will be 49mm2. DIRECT TO PHASE II: DMEA will only accept Direct to Phase II proposals. PHASE I: Perform a feasibility study on the selected fabrication process to obtain the device characteristics outlined in the preceding section of this document. The end product of Phase I is a feasibility study report, which demonstrates the proposed techniques, manufacturing process steps, and justification for utilizing the proposed techniques. The report will explicitly address the following items: 1. The feasibility study shall describe the proposed technique for obtaining global and local epitaxial layer flatness. 2. The feasibility study shall describe the substrate back grinding process for ohmic contact formation. 3. The feasibility study shall describe the method for enhancing carrier lifetimes in the N-drift layer, which is necessary for achieving a low VCE-SAT [5]. 4. The feasibility study shall describe the utilization and role of modeling and simulation in the development of the proposed techniques. 5. The feasibility study shall describe all required fabrication tools utilized to implement the proposed techniques and describe each tools applicability to the manufacturing process. Respondents shall deliver a report that satisfies all of the requirements outlined in Phase I. If any of the above items cannot be fully addressed in the Phase I feasibility report, the report must include relevant research and justification for their inapplicability. PHASE II: Phase II will result in manufacturing, testing, and delivering a fully functional prototype of the SiC IGBT developed in Phase I. A thorough analysis of the devices’ physical and electrical characteristics must be demonstrated by way of simulation. In conjunction, verification of the simulation results must be demonstrated by direct measure of the prototype device. The simulated and measured data that prove prototype conformance shall constitute a deliverable item and must be integrated into a final report. The final report must also contain sufficient technical details on the manufacturing process, mitigated challenges, and reliability of the device. PHASE III DUAL USE APPLICATIONS: Phase III will conclude with the delivery of a fully developed and verified pre-production SiC IGBT capable of meeting all of the performance and process metrics described in the preceding sections of this document. During Phase III, offerors may refine the performance of the design or manufacturability of the component. A pre-production device with any and all refinements must be provided for evaluation. REFERENCES: 1. A. Q. Huang, "Power Semiconductor Devices for Smart Grid and Renewable Energy Systems," in Proceedings of the IEEE, vol. 105, no. 11, pp. 2019-2047, Nov. 2017, doi: 10.1109/JPROC.2017.2687701. 2. B. J. Baliga, "The future of power semiconductor device technology," in Proceedings of the IEEE, vol. 89, no. 6, pp. 822-832, June 2001, doi: 10.1109/5.931471. 3. C. E. Weitzel et al., "Silicon carbide high-power devices," in IEEE Transactions on Electron Devices, vol. 43, no. 10, pp. 1732-1741, Oct. 1996, doi: 10.1109/16.536819. 4. M. Alam, N. Opondo, D. T. Morisette and J. A. Cooper, "Demonstration of a 10-kV Class Waffle-Substrate n-Channel IGBT in 4H-SiC," in IEEE Transactions on Electron Devices, vol. 69, no. 10, pp. 5683-5688, Oct. 2022, doi: 10.1109/TED.2022.3200922. 5. Tsunenobu Kimoto; James A. Cooper, "Bipolar Power Switching Devices," in Fundamentals of Silicon Carbide Technology: Growth, Characterization, Devices and Applications, IEEE, 2014, pp.353-415, doi: 10.1002/9781118313534.ch9. 6. T. Tamaki, G. G. Walden, Y. Sui and J. A. Cooper, "Optimization of on-State and Switching Performances for 15–20-kV 4H-SiC IGBTs," in IEEE Transactions on Electron Devices, vol. 55, no. 8, pp. 1920-1927, Aug. 2008, doi: 10.1109/TED.2008.926965. 7. X. Wang and J. A. Cooper, "High-Voltage n-Channel IGBTs on Free-Standing 4H-SiC Epilayers," in IEEE Transactions on Electron Devices, vol. 57, no. 2, pp. 511-515, Feb. 2010, doi: 10.1109/TED.2009.2037379. KEYWORDS: Silicon Carbide, SiC, Insulated Gate Bipolar Transistor, IGBT, Ultra-High Voltage, UHV
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