Lead Inventor:
Kenneth Shepard, Ph.D.
Floating Body Effect Inhibits Partially-Depleted Silicon-on-Insulator Technology:
Over the years, Silicon-on-insulator (SOI) technology has matured into a key semiconductor manufacturing process used throughout the microelectronics industry. By offering lower parasitic capacitances than conventional silicon substrate-based devices, SOI has contributed to the continued scaling of modern microelectronics, thus enabling chips featuring higher performance and lower power consumption.
Partially-depleted silicon-on-insulator (PD-SOI) has emerged as the preferred SOI technology for digital applications due to its superior reduction of parasitics over fully-depleted devices. However, PD-SOI devices and circuits suffer from what is known as the floating body effect, which is manifested in the form of threshold voltage uncertainties and noise failures due to the parasitic bipolar effect. The design margining required to mitigate these undesirable effects significantly limits the overall performance of a given circuit.
Body Voltage Estimation Improves Partially-Depleted Silicon-on-Insulator Technology:
The following technology details a technique for accurately estimating the body voltage of PD-SOI field effect transistors (FETs), thus representing a method for increasing the performance potential of PD-SOI-based circuits. By leveraging the information on the switching activity behavior of a given circuit, this technique characterizes the critical physical parameters of a PD-SOI FET via a state-diagram abstraction. An accurate determination of the body voltage is derived via the resulting analytic model and further calibrated based on Monte Carlo methods.
Applications:
• The body-voltage estimation technique can be applied to transistor-level timing and extended to static noise analysis
• This technology can also be employed in circuit simulation software to reduce the simulation time spent determining steady-state body-voltage values
Advantages:
• Enables the accurate determination of important electrical characteristics in SOI circuits such as the estimation of the upper and lower bounds of the body voltage
• Accurate threshold voltage and temperature predictions will facilitate reduced design margining, leading to higher performance, lower cost PD-SOI-based circuit designs
Patent Status: Patent Issued (US 7,102,522) ~ see link below.
Licensing Status: Available for Licensing and Sponsored Research Support
Publications: Shepard, K. L. and Kim, D.
Body-voltage estimation in digital PD-SOI circuits and its application to static timing analysis. ICCAD 1999. pp. 531-538.
