Wei Liu

As semiconductor devices approach the sub-10 nm technology node, the self-heating effect (SHE) induced by confined geometries (e.g., FinFETs and nanosheet FETs) has emerged as a critical bottleneck affecting both performance and reliability. This challenge has prompted extensive research efforts to develop advanced characterization methodologies to investigate this effect and its corresponding influence on the device’s reliability issues. In this paper, we propose reflection-based ultra-fast measurement techniques for the continuous monitoring of the self-heating effect in advanced MOSFETs. With this approach, the self-heating effect-induced degradation of transistor drain current and the real-time temperature change can be continuously captured using a digital phosphor oscilloscope on a nanosecond scale. The thermal time constant of 17 ns and the thermal resistance of 34,000 K/W have been extracted for the short channel transistors used in this study with the help of this new characterization method. This reflection-based method is useful for the fast extraction of the thermal time constant and thermal resistance and for the continuous monitoring of current degradation as well as the real-time temperature. Therefore, this new characterization method is beneficial for the evaluation of the self-heating effect in advanced ultra-scaled MOSFETs.

In this letter, the real-time polarization switching process in HfZrO ₄ ferroelectric film is investigated at high speed (100 MHz, highest up-to-date) by using the ultrafast measurements system. Based on the measurements over a wide range of speed from ms to ns, clear and detailed time-dependent behaviors of the polarization switch of HfZrO ₄ are captured. HfZrO ₄ film with 10 nm in thickness still exhibits ferroelectric characteristics measured with a voltage sweep period from 4 ms to 20 ns and a voltage amplitude of 4 V. The phenomenon of polarization switching diminishes distinctively with the increase of measurement speed. When the measurement speed reaches as fast as 10 ns, the polarization process could not be clearly observed. Therefore, high-speed application of negative capacitance field-effect transistor should be optimized to prevent potential problems caused by the insufficient polarization.

In this work, we developed an asymmetric Ge-based RRAM using fully CMOS compatible process. Due to the adoption of a thin AlOx/GeOx interfacial layer, the TiN/HfOx/AlOx/GeOx/Ge structured RRAM shows both excellent switching behavior and diode-like rectifying characteristics. Based on the asymmetric RRAM device, a high density nonvolatile content addressable memory (CAM) was proposed and demonstrated, and its function was verified by experimental measurements. This novel two asymmetric RRAM based TCAM cell with only 8F2 size is very promising for future energy and area efficient IoT and internet applications.

In this letter, a novel fast threshold voltage (Vth) measurement (FVM) technique is proposed and demonstrated which could perform I-V characterization of MOSFETs within 1 ns. With the advanced FVM technique, down to 1 ns negative biased temperature instability (NBTI) characterization was successfully carried out for Si pFinFETs at 14 nm technology node. It is experimentally confirmed that the nano-second-level fast recoverable traps, which are generated during NBTI stress, could lead to the underestimation of Vth degradation under micro-second-level measurement speed. Furthermore, it is found that even when the Vth measurement is performed within 1 ns after the stress removal, it is still not fast enough to be the real recovery-free measurement. Yet, with the proposed FVM technique, NBTI characteristics could be characterized more accurately and closer to its intrinsic behaviors.