A Universal BCD-on-SOI Based High Temperature Short Circuit Protection for SiC Power Switches

Abstract

In recent years, the rapid increase in the market for hybrid electric vehicles has generated great demand for low-cost, high-volume, high-temperature power converters that can work in harsh environment (temperature ≥ 150°C) conditions. Most of the commercially available power semiconductor devices and associated control electronics are rated for maximum of 85°C ambient temperature. Under this circumstance, wide bandgap (WBG) semiconductors have become a better alternative due to their ability to operate at much higher temperatures (≥500°C) than conventional bulk silicon based devices. As with any other power devices, SiC switches also require fault detection and protection mechanisms for their reliable application to real systems. One severe fault situation is the short circuit at the load end, which can cause very high surge currents that flow through the power switches. Quick detection and removal of the short circuit fault current by external circuitry is required to protect the power switch as well as the power converter module. This work presents a high-temperature (≥200°C), high-voltage short circuit protection (SCP) for SiC power devices. The circuit is designed using a resistor sensing method to provide protections for both “normally ON” and “normally OFF” SiC FET switches. A rail-to-rail input comparator is employed to ensure that the circuit operates under different power supply levels. The prototype circuit is implemented using a 0.8-micron, 2-poly, and 3-metal BCD-on-SOI process. The die size for the protection circuit is 0.52 mm2 (845 μm × 612 μm). The circuit has been successfully tested up to 200°C ambient temperature under power supplies ranging from 10 V to 30 V without any heat sink or cooling mechanism.

Fabrication of silicon-on-diamond substrate with an ultrathin SiO2 bonding layer

“…On the other hand, in a DC-DC converter, a MOSFET on a silicon-on-insulator (SOI) substrate is used as a highfrequency switching device owing to its small parasitic capacitance, small leakage current, and immunity to temperature-induced latch-up. [5][6][7][8][9][10][11][12][13][14][15][16] However, the SOI MOSFET has a heat dissipation issue because it has a low-thermalconductivity SiO 2 layer used as a buried layer. 12,[17][18][19][20][21][22] This layer affects the increase in the operating temperature of SOI devices.…”

Impact of the silicon on diamond structure for high temperature switching applications

“…[1][2][3][4][5][6][7][8][9] Silicon-on-insulator (SOI) technology is attractive for these applications because of lower leakage currents as well as high reliability (immunity of temperature induced latch up). [10][11][12][13][14][15] Thin-film approaches are promising because it showed quite lower leakage current. 16) When the SOI power MOSFETs operate at high temperature, on-resistance and leakage current increase because of selfheating effect due to poor thermal conductivity of SiO 2 .…”

Device characteristics of the thin-film silicon-on-insulator power MOSFETs at high temperatures

“…11) Thin-film approaches are promising because they provide a low leakage current. As a result, SOI circuits can operate at temperatures above 573 K, while bulk devices are usually limited to 423 K. [12][13][14][15][16][17][18][19][20][21] Power ICs based on SOI technology, which can operate up to 573 K, were reported. 22) A thin-film SOI power MOSFET, which can operate at 573 K, and its related characteristics at fixed device structural parameters were also reported.…”