Hot-Carrier Detrapping in Post-Stress Behavior of MOS Devices

Abstract

s-D-4 99.41tm. The oxide thickness is 15nm and the gate electrode material is doped polysilicon. All transistors used are conventional single-drain devices. Constant-current stress (Fowler-Nordheim injection) at fixed temperature is used to ensurc that generated traps and trapped charges are uniformly distributed across the oxide cross-section, assuming edge effects can be neglected. In order to provide sufficient electrons for injection from p-type subsffate, the sample is continuously illuminated throughout current stressing. Voltage versus time measurements are performed on capacitors with a current density of 5x10-5 Ncmz until a voltage shift of about 200 mV is obtained. C-V measurements are taken prior to stress and at time intervals subsequent to stressing. C-V curves are analyzed to obtain the D11 versus energy plot.t6l For quasi-static measurements, ramp rates of 50 mV/s and 10mV/s are used. Transistors are stressed for 1000 seconds with a current density of 6x10-5 Ncmz. Poststress electrical characteristics are then monitored for up to lOa seconds. Vtrr is determined at IprlpA. Maximum 8m is calculated in the linear region with Vur 0.lV. The temperature dependence of the post-stress behavior is studied with threshold voltage and transconductance measurements between 81K and 373K.

A cross section of VLSI reliability-hot carriers, dielectrics and metallization

“…In the AC case, not only electron trapping but also electron detrapping occurs, which correlates with lowering of the electron trap level due to compressive mechanical stress. Under compressive mechanical stress, fieldassisted detrapping [31] is accelerated, which results in a reduction of threshold voltage shift. A reduction of interface states probably contributes to the effective decrease of injected hot holes which recombine with detrapped electrons.…”

Modelling of Hot-Electron Energy in Short-Channel MOSFETs by Electrical Method

“…[1,2] Hot carriers are known as one of the major factors in device reliability degradation. [3] However, HE enhances the operating speeds of shortchannel MOSFETs by ballistic transport induced velocity overshoot, [4] and recently, HE injection is widely implemented in the operation of flash memories. [5] HE energy 𝜑 𝑒 is an important parameter in modelling of the device reliability of short-channel MOSFETs and the controllability of multi-level cell flash memories.…”

A simple approach to study time evolution of trapped electrons in metal-oxide-semiconductor devices

“…The recovery, how-, can be accelemted applying proper gate bias. [6][7][8] Against a good number of experimental reports [6][7][8][9][10] on charge trapping and subsequent relaxation phenomena in MOS devices, very few reports [ll-13] Now, let us consider the case when an external voltage is applied to the gate of the MOS device. The conduction band profile of the MOS structure unda oxide electric field due to the applied voltage iS shown in Fig.…”

“…All these features are consistent w i t h physical concepts and experimental results of relaxation phenomm of trapped chatges in MOS devi~es. [6][7][8][9][10], [18][19] -t#lsec. …”