Ridgetop Group’s Hot Carrier (HC) Prognostic Cell is a pad-limited CMOS hot carrier damage/failure detection cell. It is a part of the Sentinel Silicon™ library of prognostic (“canary”) cells.
The HCI prognostics cell’s unique and proprietary architecture behaves as an early-warning “sentinel” of an upcoming hot carrier damage fault condition in the host circuit. This degradation of MOS transistors is caused by the injection of high-energy electrons into the gate oxide. The damage is in the form of localized charge trapping, which causes a decrease in drain current ID and an increase in threshold voltage (VT). The amount of pre-warning is given in the form of percent of delta VT shift from 2 to 10%.
Promoting miniaturization without scaling the supply voltage implies increasing the electric field intensity of the internal elements of a device. This is especially true in the case of MOS FETs, where the electric field intensity near the drain area increases and a hot carrier degradation effect occurs.
Hot Carrier Block Diagram
Carriers (electrons) that flow into the high-electric-field area are accelerated by the strong field, and gain substantial energy. Some of the carriers become a hot carrier, which means they have enough energy to overcome the electric potential barrier existing between the Si substrate and gate oxide film. These degradations cause the deterioration of all semiconductor device characteristics and ultimately lead to failure.
The HC prognostic cell looks at two modes of degradation: Drain avalanche hot carrier (DAHC) injection and channel hot electron (CHE) injection.A block diagram of the Ridgetop Hot Carrier prognostic cell is shown in the figure below.
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Ridgetop is certified as category 1A under the Defense Microelectronics Activity (DMEA) as part of the Trusted Supplier Program. Ridgetop has history of designing analog and mixed signal ICs for demanding applications in space satellites that are subjected to extreme temperatures and radiation. Our designs have utilized bulk CMOS, CMOS-SOI, and SiGe at process geometries down to 28 nm channel lengths. Radiation hardness is also a concern, and Ridgetop has addressed those requirements as well. A recent Ridgetop design was delivered to ON Semiconductor for the U.S. Air Force STELLAR Star Tracker.
Under contract to NASA, Ridgetop designed an effective 3-axis wireless rotational sensor. The RotoSense™ sensor has been tested on fast-spinning pinion gears on helicopter gear boxes, and also rolling stock for railroad safety improvements.