# Device to Circuit Co‐Design Utilizing High‐Performance PEALD Indium‐Gallium‐Zinc Oxide Thin‐Film Transistor Enabling Technology Node Scaling in Monolithic 3D Systems

## TL;DR

This paper explores the use of high-performance IGZO thin-film transistors for monolithic 3D systems, showing promising device and circuit-level performance for future technology scaling.

## Contribution

The study introduces a holistic co-design approach for M3D systems using PEALD IGZO TFTs, including device characterization and circuit-level projections.

## Key findings

- IGZO TFTs achieved a field-effect mobility of up to 116.35 cm² V⁻¹·s⁻¹.
- Projected 22 nm node scaling enables 240 MHz ring oscillators and 0.78 ns SRAM switching times.
- Robust reliability and low variation were demonstrated (△VTH < 0.15 V, △µFE < 2%).

## Abstract

The development of oxide semiconductor devices for monolithic 3D (M3D) integration has largely remained at the device level, limiting progress toward large‐scale applications. To advance this technology, evaluation from device to circuit level—akin to CMOS—is essential. This work presents a comprehensive study of M3D‐compatible technology using indium‐gallium‐zinc oxide (IGZO) thin‐film transistors (TFTs) fabricated via plasma‐enhanced atomic layer deposition (PEALD). The investigation spans material characterization, device performance, technology computer‐aided design (TCAD) Modeling, circuit design, and scaling projections. At device level, comprehensive material and electrical characterizations elucidate intrinsic property interdependencies in IGZO TFTs, which exhibit a field‐effect mobility (µFE
) up to 116.35 cm2 V−1·s−1, high reliability (△VTH
< 0.15 V), and low variation (△µFE
< 2%). These results enable accurate TCAD models for system‐level co‐design of unipolar TFT circuits, including pseudo‐CMOS inverters, 5‐stage ring oscillators (ROs), and static random‐access memory (SRAM) cells, all exhibiting robust functionality. For future technology scaling, projections to the 22 nm node show RO frequencies up to 240 MHz and SRAM switching times as low as 0.78 ns, with strong dynamic and noise characteristics. This work offers critical insight into circuit‐level performance of PEALD IGZO TFTs and provides valuable guidance for the implementation of oxide semiconductor‐based M3D systems.

This article presents a holistic investigation of M3D‐compatible oxide semiconductor technology using PEALD‐fabricated IGZO TFTs, spanning device‐level characterization, TCAD Modeling, circuit design, and scaled‐node projections. It demonstrates high field‐effect mobility (up to 116.35 cm2 V−1·s−1), robust reliability (△VTH
< 0.15 V), low variation (△µFE
< 2%), and forecasts 240 MHz ring oscillators and 0.78 ns SRAM at 22 nm.