Symptom reliability: S‐parameters evaluation of power laterally diffused‐metal–oxide–semiconductor field‐effect transistor after pulsed‐RF life tests for a radar application

Abstract

This paper treats the s-parameter performance degradation by hot electron induced for N-MOSFET devices used in radar applications. This study is relevant for devices operating in the RF frequency regime. The power LD-MOSFET device (0.8 µm channel length, Gate oxide thickness 0.065 µm and 2.2 GHz) are designed and fabricated. Subsequently, life tests in pulsed RF cause, after ageing, the electrical behaviour and its relation with charge trapping at the interface are presented and discussed. Unlike all other current methods, a complete evaluation of S parameters is carried out to obtain key information concerning the defects location. The s-parameter performance degradation can be explained by the transconductance and the miller capacitance move, and by the leakage current augmentation IG, which is shown by hot-carrier event from the Si/SiO 2 interface state generation and/or in a build up of negative charge. Also, the degradation can be predicted by the experimental correlation of RF and dc performance shifts, favour by the measurement of dc performance or initial leakage current. The analysis accompanied proves that the s-parameters shift by hot electron induced and should be taken into consideration in the design. Through physical processes of ATLAS-SILVACO simulations these degradation phenomena are located and confirmed

Temperature impact on reliability of power RF devices under S-band pulsed-RF test

“…8) and a high electrons concentration at the SiO 2 /LDD interface ( Fig. 9) contributed to the appearance of hot carriers [5,19]. The simulation results tend to prove that for these tests conditions (polarization, temperature, etc.)…”

“…The reliability bench diagram has been implemented is shows in Fig. 1, which will achieve the objective, namely the estimation of the lifetime of the transistors under operational radar conditions [5]. It contains eight "branches" of tests.…”

“…Metal Oxide Field Effect Transistors (MOSFETs) are the smost used devices in higher power RF field [3]. They are distinguished many advantages relative to bipolar devices, such as in particular [4,5]; better linearity, with intermodulation products of smaller amplitude, and these are devices that are better from thermal runaway [1,6].…”

“…Recently, the characterization, optimization, and reliability of LDMOS devices have drawn much attention [2,4]. For this purpose, we designed and implemented an innovative reliability bench able to keep monitoring of RF powers, voltages and device basic temperatures where the values correspond to the constraint operating conditions [5,7,8]. The duty cycle and pulse length have steadily increased to improve radar performance, from the accession of solid-state power modules in radar system [5].…”

“…For this purpose, we designed and implemented an innovative reliability bench able to keep monitoring of RF powers, voltages and device basic temperatures where the values correspond to the constraint operating conditions [5,7,8]. The duty cycle and pulse length have steadily increased to improve radar performance, from the accession of solid-state power modules in radar system [5]. These important needs for operation have increased the amount of constraint applied to devices and have a direct impact on their lifetime.…”