High Temperature CMOS Circuits on Silicon Carbide

Abstract

This paper presents the characteristics and performance of a range of Silicon Carbide (SiC) CMOS integrated circuits fabricated using a process designed to operate at temperatures of 300°C and above. The properties of Silicon carbide enable both n-channel and p-channel MOSFETS to operate at temperatures above 400°C [1] and we are developing a CMOS process to exploit this capability [4]. The operation of these transistors and other integrated circuit elements such as resistors and contacts is presented across a temperature range of room temperature to +400°C. We have designed and fabricated a wide range of test and demonstrator circuits. A set of six simple logic parts, such as a quad NAND and NOR gates, have been stressed at 300°C for extended times and performance results such as propagation delay drive levels, threshold levels and current consumption versus stress time are presented. Other circuit implementations, with increased logic complexity, such as a pulse width modulator, a configurable timer and others have also been designed, fabricated and tested. The low leakage characteristics of SiC has allowed the implementation of a very low leakage analogue multiplexer showing less than 0.5uA channel leakage at 400°C. Another circuit implemented in SiC CMOS demonstrates the ability to drive SiC power switching devices. The ability of CMOS to provide an active pull up and active pull down current can provide the charging and discharging current required to drive a power MOSFET switch in less than 100ns. Being implemented in CMOS, the gate drive buffer benefits from having no direct current path from the power rails, except during switching events. This lowers the driver power dissipation. By including multiple current paths through independently switched transistors, the gate drive buffer circuit can provide a high switching current and then a lower sustaining current as required to minimize power dissipation when driving a bipolar switch.

Integrated Digital and Analog Circuit Blocks in a Scalable Silicon Carbide CMOS Technology

“…A decade ago, Raytheon Systems Limited developed a proprietary 1.2 μm SiC CMOS technology, called high temperature silicon carbide (HiTSiC), and demonstrated integrated circuits [14], [15]. The group of Mantooth at the University of Arkansas demonstrated a comparator [16], 8-bit digitalto-analog converter (DAC) [17], voltage and current references [18], gate driver [19], complex digital circuits [20], protection circuits in voltage regulators and switch-mode converters [21], digitally controlled pulsewidth modulation (PWM) generator [22], and data converters [23].…”

Visible Blind Quadrant Sun Position Sensor in a Silicon Carbide Technology

“…This opens the door to inherently visible blind sun position sensor devices by implementation in wide bandgap materials. For on-chip readout electronics, SiC is at present considered the most mature technology and best known are the CMOS HiTSiC [5][6] and BJT HOTSiC [7][8] technologies, developed by Raytheon Systems Limited and the KTH university respectively. Unfortunately, the HiTSiC technology was discontinued in 2018, which left the need for a new and open SiC CMOS technology.…”

Resistive and CTAT Temperature Sensors in a Silicon Carbide CMOS Technology

“…Over the last twenty years, different technologies for integrated circuit design in SiC were reported, all of which focused on the high temperature application of such circuits. These technologies include CMOS [10][11][12][13], BJT [14,15], JFET [16,17] and MESFET [18,19], but access to these mostly proprietary technologies is limited. Fortunately, the SiC CMOS technology developed by Fraunhofer IISB is addressing this need.…”