In this work, we develop anneal-free hafnium zirconium oxide (HZO)-based ferroelectric field-effect transistor (FeFET) with low thermal budget (≤350 °C) suitable for monolithic 3-dimensional (M3D) integration technology. Integrating with room temperature oxide semiconductor, the demonstrated FeFET is fully back-end-of-line (BEOL)-compatible, featuring Ion/off of >105, memory window (MW) of 0.7 V, and good retention performance of 1×104 s. Such excellent electrical characteristics are achieved by HZO surface energy engineering for the ferroelectric orthorhombic phase formation. Furthermore, FeFET exists 32 controllable states with the linearity (α) of 0.31 and -5.03 in potentiation (Pot) and depression (Dep).

Researcher/Author: Tsai Shih-Hao, Chen Chun-Kuei,  Wang Xinghua, Chand Umesh, Hooda Sonu, Zamburg Evgeny, Aaron Thean Voon-Yew 

2022 International Symposium on VLSI Technology, Systems and Applications (VLSI-TSA)

The recent legalization of cannabidiol (CBD) to treat neurological conditions such as epilepsy has sparked rising interest across global pharmaceuticals and synthetic biology industries to engineer microbes for sustainable synthetic production of medicinal CBD. Since the process involves screening large amounts of samples, the main challenge is often associated with the conventional screening platform that is time consuming, and laborious with high operating costs. Here, a portable, high-throughput Aptamer-based BioSenSing System (ABS3) is introduced for label-free, low-cost, fully automated, and highly accurate CBD concentrations’ classification in a complex biological environment. The ABS3 comprises an array of interdigitated microelectrode sensors, each functionalized with different engineered aptamers. To further empower the functionality of the ABS3, unique electrochemical features from each sensor are synergized using physics-guided multidimensional analysis. The capabilities of this ABS3 are demonstrated by achieving excellent CBD concentrations’ classification with a high prediction accuracy of 99.98% and a fast testing time of 22 µs per testing sample using the optimized random forest (RF) model. It is foreseen that this approach will be the key to the realistic transformation from fundamental research to system miniaturization for diagnostics of disease biomarkers and drug development in the field of chemical/bioanalytics.

Researcher/Author: Stephanie Hui Kit Yap, Jieming Pan, Dao Viet Linh, Xiangyu Zhang, Xinghua Wang, Wei Zhe Teo, Evgeny Zamburg, Chen-Khong Tham, Wen Shan Yew, Chueh Loo Poh, Aaron Voon-Yew Thean

Small 2022, 18, 22, 2107659.

A ferroelectric field-effect transistor (FeFET), capable of logic and memory functionalities in a single device, is a promising three-terminal memtransistor that enables high-performance in-memory computing for non Von Neumann architectures. Among all HfO2-based ferroelectric materials, HfZrO2 (HZO) has attracted the most attention due to the low process temperature of ≤500 °C; however, it has relatively weak polarization. Many prior works claimed that the way to improve HZO-based FeFET characteristics is to enhance HZO ferroelectric properties, while they did not account for the fundamental compromise on dielectric breakdown strength (BDS), transistor ON/OFF current (ION/IOFF) ratio, and memory window (MW) due to the enhanced polarization. In this work, we propose an approach for controlling the ferroelectric orthorhombic phase (O phase) and the corresponding polarization in optimal value by engineering both the surface morphology and stress of HZO layer by a thermal expansion mismatch with a TiN/W stacked capping layer, to improve the BDS, ION/IOFF ratio, and MW. Through electrode surface optimization and stress memorization we achieved an 18% HZO ferroelectricity increase with a high BDS value of ≥4.8 MV/cm. Our optimized FeFET shows good electrical characteristics and supports operation in an identical pulse programming (IPP) mode, showing good potentiation and depression nonlinearity (−0.84 and −2.04) with an asymmetry factor of 1.2. A simulation based on the proposed FeFET array demonstrates the high potential of application in an artificial neural network (ANN).

Researcher/Author: Shih-Hao Tsai, Zihang Fang, Xinghua Wang, Umesh Chand, Chun-Kuei Chen,Sonu Hooda, Maheswari Sivan, Jieming Pan, Evgeny Zamburg, Aaron Voon-Yew Thean

ACS Appl. Electron. Mater. 2022, 4, 4, 1642–1650.

In this paper, we present a unique hybrid integration platform for wafer scale passive assembly of electronics and photonics devices using a CMOS based Optical Interposer. Our optical interposer enables seamless communications between electronics and photonics chips that are assembled on it using visually assisted passive flip chip bonding techniques. This unique integration platform is the first such platform in the industry adapted to directly modulated lasers and enables the world’s smallest single chip Transmit/Receive Optical engine for 100G-400G optical engines.

Researcher/Author: Suresh Venkatesan, James Lee, Simon Chun Kiat Goh, Brian Pile, Daniel Meerovich, Jinyu Mo, Yang Jing, Lucas Soldano, Baochang Xu, Yu Zhang, Aaron Voon Yew Thean, Yeow Kheng Lim

2022 IEEE Symposium on VLSI Technology and Circuits (VLSI Technology and Circuits)