Towards Silicon Carbide VLSI Circuits for Extreme Environment Applications

Abstract

A Process Design Kit (PDK) has been developed to realize complex integrated circuits in Silicon Carbide (SiC) bipolar low-power technology. The PDK development process included basic device modeling, and design of gate library and parameterized cells. A transistor–transistor logic (TTL)-based PDK gate library design will also be discussed with delay, power, noise margin, and fan-out as main design criterion to tolerate the threshold voltage shift, beta ( β ) and collector current ( I C ) variation of SiC devices as temperature increases. The PDK-based complex digital ICs design flow based on layout, physical verification, and in-house fabrication process will also be demonstrated. Both combinational and sequential circuits have been designed, such as a 720-device ALU and a 520-device 4 bit counter. All the integrated circuits and devices are fully characterized up to 500 °C. The inverter and a D-type flip-flop (DFF) are characterized as benchmark standard cells. The proposed work is a key step towards SiC-based very large-scale integrated (VLSI) circuits implementation for high-temperature applications.

A Silicon Carbide 256 Pixel UV Image Sensor Array Operating at 400 °C

“…Our preliminary works have shown the high temperature performance of discrete UV-only SiC photodetectors (up to 550 • C) [24], [25], [26] and BJT (up to 400 • C) as a switch controlling a photodiode [27]. We have also presented our work on a TTL process design kit (PDK) demonstrating the functionality of basic digital circuits up to 500 • C [28]. Here, our in-house processing flow for SiC bipolar technology has been optimized to achieve a higher yield in both device level and circuit level [29] so that an image sensor is demonstrated.…”

“…The image sensor has 1959 transistors in total and the whole layout has an area of 62.3 mm 2 . The circuits are built from standard discrete cells (inverter, buffer, AND, XOR and D flip-flop) selected from our TTL PDK [28]. The schematic diagrams of the digital circuits are shown in the Supplementary Material of this paper.…”

“…The characterization results of the basic gates, except for the tri-state buffer, used in the digital circuits have been reported in [28]. The measurement results of the tristate buffer and the simulation results of the decoder and counter are reported in the Supplementary Material of this paper.…”

SPICE Modeling and Circuit Demonstration of a SiC Power IC Technology

“…SiC ICs with junction field-effect transistors (JFETs) and bipolar junction transistors (BJTs) have also been investigated for extreme-temperature (>500°C) applications. Shakir et al demonstrated a SiC 555 timer and a SiC comparator that are operational under 500°C [14] with an in-house SiC bipolar junction transistor (BJT) process [15]. Hou et al reported a 16x16 SiC UV image sensor array operating at 400°C with the same BJT technology [16].…”

Radiation Hardness of 4H-SiC P-N Junction UV Photo-Detector

“…Recently, we have shown [ 18 ] that the defects introduced by He irradiation in a 4H-SiC based p-n junctions can be exploited to fabricate photon sources operating in the NIR and we also published a wide study on the electrical performance of ion irradiated 4H-SiC p-n junctions correlating their evolution with irradiation defects [ 19 ]. As it is well known, p-n junction is an essential element of more complicated devices such as MOSFET or avalanche photodiode, widely investigated in the literature for extreme environment UV monitoring applications [ 20 , 21 , 22 ]. In this field, electro-optical performance changes due to cosmic rays and, more generally, to particle irradiation need to be managed.…”