by Dale Robinette, Peregrine Semiconductor Inc. San Diego, CA
Commercial and military satellites require cost-effective ICs that meet stringent high-reliability standards. In addition, they need to provide distinct advantages that allow designers to advance satellite technology in order to meet changing needs, especially in terms of cost (weight, power), reliability (number of transmission lines, radiation tolerance, redundancy) and performance (including the ability to enhance opportunities for flexible payload designs using phased-array antennas or a switch matrix). Silicon on sapphire (SOS) is inherently a great match for these business and technical constraints, and is currently available in high-volume, high-yield commercial production.
A form of SOS technology that uses ultra-thin films, UltraCMOS™ technology is an extension of RF complementary metal-oxide-semiconductor (CMOS) technology that enables the manufacture of high-performance RF devices. Particularly important for satellites, this technology has low gate capacitance and fully depleted devices, which enables high speeds at low power. These devices also greatly improve linearity as compared to typical silicon on insulator (SOI) and GaAs technologies, and they offer 2 kV typical Human Body Model (HBM) electrostatic discharge (ESD) protection. Presently in high-volume production for commercial applications, UltraCMOS technology meets high-reliability and environmental requirements for operating in space and yields tend to be comparable to other CMOS processes.
Process Advantages for Satellites
Figure 1 Bulk Si process devices (top) have higher parasitics because of the thick layer of Si while UltraCMOS process devices utilize a thin 1000 Å Si layer.
CMOS technology’s advantages of low power and ease of integration are well known.1 UltraCMOS technology is a CMOS technology where a 50 to 100 nm silicon film is formed directly on a sapphire substrate. When properly processed, this provides for fully depleted devices with little or no body charge under the gate (see Figure 1). As compared to traditional CMOS processing, UltraCMOS offers the advantage of faster devices with reduced power loss, excellent linearity, high isolation and no kink effect. For satellite applications, this proves to be particularly valuable in the avoidance of single-event effects.
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