Experimental investigation of temperature dependent RF performances of RF-CMOS devices

Abstract

AbstiactThis paper presents the d e g m b o n of fT and f-in CMOS devices at elevated temperame. Since MOS transistors in RF applications are usually in d o n region and f7 of CMOS devices is proportional to g , a simple empirical model for temperature dependence of g, at any measurement bias has been suggested by considering the temperature dependence of a canier mobility and a saturation velocity simultaneously. From the empirical temperature behavior of g , we can predict the enhanced RF performances of CMOS at low temperatllre. in d o n region, the temperature dependence offT and f , should be characterized by the combination of the temperahlre dependence of pef and v , , . In this work, the temperature dependence of& and f , in CMOS devices have been measured. Since& and f , are proportional to g, the degradation of& and f , can be explained by a simple empirical model for tempemtm behavior of g, which was taken into considemtion of both canier mobility and d o n velocity degadahon. II . Device Fabrication and Measurement I . Introduction With the scaling towards an extreme sub-micrometer regime, a cut-off tkquency UT) of CMOS as high as 150 GHz and Si MMIC have been reported to replace GaAs MMIC in RF h n t e n d IC's[ 1-31. Generally, high channel tempeiature has well known detrimental effects on the performances of MOS devices such as threshold voltage shift, transconductance d e w o n , and distortion of the Dc I-V charactenstl cs. To explain the transconductance degradabon with the increase of temperature, there have been extensive studies on the temperature dependence of effective canier mobility ( p ) and saturation velocity (v, ), separately [4,5]. When the MOS transistor is operated in the saturation region, the channel region can be divided into two regions such as a strong inversion region and a velocity saturation region. Therefore, the tempemture dependent g behaviors in the saturation region should be described by the temperature dependence of p and v,, simultaneously. Particularly, since MOS transistors in RF applications are usually biased . . eff eliThe CMOS transistors used in this work were &-hid using a 0.8 wn twin-well CMOS process on the p Si with resistivity of 2000 Q an. The gate oxide thickness is 175A, and a TiSi silicide process was used to reduce the sowcedrain parasitic resistance. The gate pattern for RF chamcterization is multi-finger type with common sourcebulk configclration. All the test devices used in this work have 10 fingers with L4.8 rn and unit finger width Wu=lO lla Small signal scattering ( S ) m e t e r s have been measured using on-wafer RF probes of Cascade Microtech and a HP 8510C network analyzer at temperature ranging h m 300 to 473K.On-wafer dummy structures were employed to deembed pad parasites. Measured S parameters were converted into admittance (Y) parameters, and the inbinsic device characteristics were calculated in the Y domain by using a deembedded technology.The cut-off hquency V;) and maximum h u e n c y (&A have been determined as the frequency whe...

Temperature Dependence of High Frequency Noise Behaviors for RF MOSFETs

“…(5) (6) Equation ( 6) directly captures the positive temperature coefficient observed for . On the other hand, as temperature increases, the channel mobility would decline [2], causing to decrease with increasing temperature as shown in Table I. This explains the positive temperature coefficient for (4).…”

“…Besides, it is well known that both the small-signal circuit parameters and noise sources play important roles in RF noise modeling. The temperature dependence of small-signal performance has been widely discussed [2], [3], but that of RF noise sources was deficient. Therefore, for the purpose of temperature modeling and understanding the underlying physics, the temperature dependence of noise sources demands investigation.…”

Investigation of Temperature-Dependent High-Frequency Noise Characteristics for Deep-Submicrometer Bulk and SOI MOSFETs

“…It is also well known that both smallsignal circuit parameters and noise sources play important roles in the high-frequency noise modeling. There have been many studies on the high-frequency noise characterization and modeling for bulk and silicon-on-insulator (SOI) MOSFETs [1]- [9], and the temperature dependence of their small-signal performances has been also widely discussed [10]- [12]. In particular, Pascht et al have conducted the temperature noise modeling for MOSFETs using the small-signal equivalent cir-cuit with channel noise source [2].…”