Laurent Vancaillie

Influence of device engineering on the analog and RF performances of SOI MOSFETs

This work presents a systematic comparative study of the influence of various process options on the analog and RF properties of fully depleted (FD) silicon-on-insulator (SOI), partially depleted (PD) SOI, and bulk MOSFETs with gate lengths down to 0.08 /spl mu/m. We introduce the transconductance-over-drain current ratio and Early voltage as key figures of merits for the analog MOS performance and the gain and the transition and maximum frequencies for RF performances and link them to device engineering. Specifically, we investigate the effects of HALO implantation in FD, PD, and bulk devices, of film thickness in FD, of substrate doping in SOI, and of nonstandard channel engineering (i.e., asymmetric Graded-channel MOSFETs and gate-body contacted DTMOS).

Advantages of the graded-channel SOI FD MOSFET for application as a quasi-linear resistor

In this paper, we analyze the previously unexpected advantages of asymmetric channel engineering on the MOS resistance behavior in quasi-linear operation, such as used in integrated continuous-time tunable filters. The study of the two major figures of merit in such applications as on-resistance and nonlinear harmonic distortion, is supported by both measurements and simulations of conventional and graded-channel (GC) fully depleted silicon-on-insulator (SOI) MOSFETs. The quasi-linear current-voltage characteristics of GC transistors show a decrease of the on-resistance as the length of the low doped region in the channel is increased, as well as an improvement in the third-order harmonic distortion (HD3), when compared with conventional transistors. A method for full comparison between conventional and GC SOI MOSFETs is presented, considering HD3 evolution with on-resistance tuning under low voltage of operation. Results demonstrate the significant advantages provided by the asymmetrical long channel transistors.

Intelligent SOI CMOS integrated circuits and sensors for heterogeneous environments and applications

In this paper, we demonstrate how a simple fully-depleted SOI CMOS process can be adapted to provide a wide range of performance compatible with the realization of heterogeneous micropower, high-temperature or RF micro-systems which involve the integration of sensing, analog and digital components. High-temperature and low-voltage examples are discussed.

MOSFET mismatch in weak/moderate inversion: model needs and implications for analog design

Based on mismatch measurements performed on very different CMOS technologies and large operating temperature range, we propose to model more adequately the mismatch in weak and moderate inversion by adding a new term related to the mismatch of the body effect factor dependence on the gate voltage. The model is introduced in a top-down analog design methodology, applied to the current mirror case, revealing some nonobvious design rules as well as typical misconceptions.

Characterization and design methodology for low-distortion MOSFET-C analog structures in multithreshold deep-submicrometer SOI CMOS technologies

The harmonic distortion (HD) of MOSFETs operating in the triode regime is thoroughly investigated for the different device types of a multi-V/sub th/ deep-submicrometer 0.12-/spl mu/m silicon-on-insulator (SOI) CMOS process. The measurements performed in a wide temperature range (25/spl deg/C-220/spl deg/C) and on devices with different oxide thicknesses and channel dopings help to identify the relative impact of the different physical mechanisms at the origin of HD. A measurement-based and design-oriented methodology is finally developed to compare device types, biases and configurations responding to practical design targets.

MOSFETs scaling down: advantages and disadvantages for high temperature applications

With technology advances into deep submicron era, new physical phenomena appear and the relative importance of existing phenomena for high-temperature behaviour can change. This paper is focused on the influence of scaling down technology, particularly the decrease in gate oxide thickness and the increase in doping levels on the high-temperature characteristics of SOI and bulk MOSFETs. By examining different device properties, major evolutions in high-temperature behaviour with regards to previous device generations have been identified.