Ultimate vertical gate-all-around metal–oxide–semiconductor field-effect transistor and its three-dimensional integrated circuits

According to the International Roadmap for Devices and Systems, gate-all-around (GAA) metal–oxide–semiconductor field-effect transistors (MOSFETs) will become the main devices in integrated circuits over the next few decades. However, both vertical and lateral GAA-MOSFETs currently face two issues: large variance in sub-10-nm devices and challenges in integration. In particular, vertical GAA-MOSFETs have an asymmetric source/drain structure that is different from that of all other MOSFETs, resulting in unfavorable electrical characteristics. The traditional fabrication process of GAA-MOSFETs is likely the main cause of the above problems, preventing the application of traditional GAA-MOSFETs in integrated circuits. In this work, a novel method is proposed to fabricate the ultimate vertical GAA (UVGAA) MOSFET that may exhibit a symmetric source/drain structure, significantly reduced variance, high yield, high integration, high performance (high speed and low energy consumption), and low cost. Furthermore, a new architecture consisting of a three-dimensional (3D) integrated circuit based on the proposed UVGAA-MOSFETs where memory cells and/or logic devices are stacked in the vertical direction is developed. This work paves the way for next-generation integrated circuits with a new 3D architecture.