Don Disney

High Voltage Vertical GaN p-n Diodes With Avalanche Capability

In this paper, vertical p-n diodes fabricated on pseudobulk gallium nitride (GaN) substrates are discussed. The measured devices demonstrate breakdown voltages of 2600 V with a differential specific on-resistance of 2 mΩ cm2. This performance places these structures beyond the SiC theoretical limit on the power device figure of merit chart. Contrary to common belief, GaN devices do possess avalanche capability. The temperature coefficient of the breakdown voltage is positive, showing that the breakdown is indeed because of impact ionization and avalanche. This is an important property of the device for operation in inductive switching environments. Critical electric field and mobility parameters for epitaxial GaN layers grown on bulk GaN are extracted from electrical measurements. The reverse recovery time of the vertical GaN p-n diode is not discernible because it is limited by capacitance rather than minority carrier storage, and because of this its switching performance exceeds the highest speed silicon diode.

3.7 kV Vertical GaN PN Diodes

There is a great interest in wide band-gap semiconductor devices for power electronics application. In this letter, vertical GaN p-n diodes fabricated on bulk GaN substrates are discussed. The device layers are grown by MOCVD on low defect density (104 cm-2) bulk GaN substrates. The measured devices show breakdown voltages of 3.7 kV with an area differential specific on-resistance (Rsp) of 2.95 mΩ-cm2.

Vertical power diodes in bulk GaN

Vertical diodes with breakdown voltages up to 2.6kV have been fabricated on bulk GaN substrates. The measured figures-of-merit of these devices show performance near the theoretical limit of GaN. These vertical GaN diodes exhibit robust avalanche breakdown behavior with a positive temperature coefficient. System-level performance advantages have been demonstrated in power conversion applications. Statistical data have been collected from thousands of devices. Initial reliability tests have been completed.

JFET Depletion in SuperJunction Devices

SuperJunction theory predicts that specific on- resistance improves as the widths of the N- and P-type regions in the drift region are reduced. In this paper, it is shown that there is a practical limit to improving on-resistance by shrinking these widths, due to JFET depletion of the conducting regions. An analytic model is developed to calculate the optimum drift region width for super junction devices, and this model is verified by simulations. Specific examples of optimized drift region widths for superjunction devices with various levels of drift region charge and applied drain voltage are provided.

High-Voltage Integrated Circuits: History, State of the Art, and Future Prospects

High-voltage ICs (HVICs) are used in many applications, including ac/dc conversion, off-line LED lighting, and gate drivers for power modules. This paper describes the technologies most commonly used in commercial HVICs, including junction-isolation, thin silicon-on-insulator (SOI), and thick SOI approaches. Emerging technologies such as thin silicon membrane are also discussed.

60V Lateral Trench MOSFET in 0.35 μm Technology

A novel Lateral Trench MOSFET was fabricated in a 0.35 μm ModularBCDtrade technology. This device is compact, efficient, rugged, and offers hot-carrier lifetime that is far superior to equivalent LDMOS devices. Breakdown voltages up to 75 V were demonstrated.

High-voltage IC technologies for AC/DC power conversion

The market for AC/DC power converters is growing rapidly, driven largely by the proliferation of portable electronic devices and adoption of LED lighting. This paper provides an overview of one of the most common circuit topologies used for AC/DC conversion and describes the IC technology requirements for these systems. Key characteristics and trends in high-voltage (HV) and ultra-high voltage (UHV) technologies are discussed.

30V High-side N-channel Lateral Trench MOSFET

A High-side Lateral Trench MOSFET (LTDMOS) was fabricated in a 0.35µm ModularBCD™ technology. The drift region of this device completely surrounds and isolates the trench, body, and source regions from the substrate, allowing the entire LTDMOS to float to a high-voltage above the substrate. A complete 28V half-bridge level-shifter was demonstrated using integrated floating high-side drive circuitry along with low-side and high-side LTDMOS devices.

180nm HVIC technology for digital AC/DC power conversion

A new high-voltage integrated circuit (HVIC) technology has been developed and optimized for AC/DC power conversion applications that require increased digital content. This cost-effective process uses 3.3V CMOS and a 180nm backend process to provide about 10X greater digital circuit density compared to conventional 0.5um 5V CMOS solutions. Excellent analog circuit performance is maintained. For the first time, reliable 700V devices are demonstrated using shallow trench isolation (STI) oxide over a double-RESURF drift region.

Guest Editorial Special Issue on Power Semiconductor Devices and Smart Power IC Technologies

Power semiconductor devices have been a mainstay of electron device technology since the introduction of the thyristor in the late 1950s. In the last six decades, electron devices and VLSI technology have gone through unprecedented changes. The state-of-the-art performance has progressed closely according to the famous Moores Law, since it was introduced in 1965. The current techno-trend is the “More Than Moore” roadmap with emphasis on System in Package and 3-D integration. Over this period, we have witnessed device feature sizes shrinking from several microns in the 1970s to the 10-nm production-ready processes in 2017. At the same time, power semiconductor devices have also benefited significantly from these advancements.