Development of a basic silicon carbide TTL IC technology

Jeong Youb Lee, Purdue University

Abstract

Silicon carbide (SiC), as a wide bandgap semiconductor, offers the advantage to overcome the physical limitations of silicon. Due to its superior physical properties, SiC is an attractive material, especially for high temperature electronics applications. An ideal device for these applications is the bipolar junction transistor (BJT). In order to exploit the full temperature capabilities of SiC, an exploratory development effort to investigate monolithic bipolar integrated circuits (ICs) is performed for operation in the temperature range from room temperature to above 300 degree C. With proper optimization, discrete devices and integrated circuits in SiC should be able to operate reliably in the same high temperature technology. In this dissertation, a bipolar logic IC technology using transistor-transistor logic (TTL) is developed in 4H-SiC for the first time. This demonstrates feasibility of the circuit designs and fabrication processes, and produces basic circuits. This basic fabrication technology will support any bipolar IC family, including, for example, emitter-coupled logic (ECL) or linear integrated circuits. The voltage transfer characteristics of the fabricated SiC TTL gates are investigated, and each gate operates with good noise margins. For the inverter with a fan-out of 10, the high noise margin is 1.5 Volt and the low noise margin is 3.9 Volt. The transient responses for the SiC TTL gates are also characterized, and show proper operation for each gate. Finally, the SiC TTL circuits are characterized over a wide temperature range and show excellent logic functional operation from room temperature to above 300 degree C. This verifies that SiC bipolar integrated circuits are promising candidates for high temperature applications.

Degree

Ph.D.

Advisors

Cooper, Purdue University.

Subject Area

Electrical engineering

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