Strain mapping of semiconductor specimens with nm-scale resolution in a transmission electron microscope

The international technology roadmap of semiconductors (ITRS) is approaching the historical end point and we observe that the semiconductor industry is driving complementary metal oxide semiconductor (CMOS) further towards unknown zones. Today's transistors with 3D structure and integrated advanced strain engineering differ radically from the original planar 2D ones due to the scaling down of the gate and source/drain regions according to Moore's law. This article presents a review of new architectures, simulation methods, and process technology for nano-scale transistors on the approach to the end of ITRS technology. The discussions cover innovative methods, challenges and difficulties in device processing, as well as new metrology techniques that may appear in the near future.

State of the Art and Future Perspectives in Advanced CMOS Technology.

When the international technology roadmap of semiconductors (ITRS) started almost five decades ago, the metal oxide effect transistor (MOSFET) as units in integrated circuits (IC) continuously miniaturized. The transistor structure has radically changed from its original planar 2D architecture to today’s 3D Fin field-effect transistors (FinFETs) along with new designs for gate and source/drain regions and applying strain engineering. This article presents how the MOSFET structure and process have been changed (or modified) to follow the More Moore strategy. A focus has been on methodologies, challenges, and difficulties when ITRS approaches the end. The discussions extend to new channel materials beyond the Moore era.

Miniaturization of CMOS.

With technology node scaling down to 5 nm, the narrow device geometry confines the material thermal conductivity and further aggravates the self-heating effect in gate-all-around (GAA) transistors. In this paper, we investigate the self-heating of horizontally stacked three-layer GAA nanosheet transistors by 3-D finite-element modeling (FEM) simulation. The anisotropic thermal conductivity of nanosheets with the dependence of silicon thickness and temperature is implemented in the FEM simulator to evaluate thermal behavior accurately. The impact of layout design on thermal properties is investigated comprehensively from single device to device arrays with implication on electrical performance. The results indicate that the width of nanosheet is the key parameter to make the tradeoffs between self-heating and electrical characteristic. Meanwhile, the optimizations of layout design are given to suppress the thermal effects, including self-heating, nonuniformity of temperature, and thermal crosstalk at device level. This paper will provide guidelines for layout design, thermal management, device performance, and thermal-aware reliability prediction in the GAA-stacked structure.

Layout Design Correlated With Self-Heating Effect in Stacked Nanosheet Transistors

The architecture, size and density of metal oxide field effect transistors (MOSFETs) as unit bricks in integrated circuits (ICs) have constantly changed during the past five decades. The driving force for such scientific and technological development is to reduce the production price, power consumption and faster carrier transport in the transistor channel. Therefore, many challenges and difficulties have been merged in the processing of transistors which have to be dealed and solved. This article highlights the transition from 2D planar MOSFETs to 3D fin field effective transistors (FinFETs) and then presents how the process flow faces different technological challenges. The discussions contain nano-scaled patterning and process issues related to gate and (source/drain) S/D formation as well as integration of III-V materials for high carrier mobility in channel for future FinFETs.

The Challenges of Advanced CMOS Process from 2D to 3D

We report on vertically stacked horizontal Si NanoWires (NW) /»-MOSFETs fabricated with a replacement metal gate (RMG) process. For the first time, stacked-NWs transistors are integrated with inner spacers and SiGe source-drain (S/D) stressors. Recessed and epitaxially re-grown SiGe(B) S/D junctions are shown to be efficient to inject strain into Si/-channels. The Precession Electron Diffraction (PED) technique, with a nm-scale precision, is used to quantify the deformation and provide useful information about strain fields at different stages of the fabrication process. Finally, a significant compressive strain and excellent short-channel characteristics are demonstrated in stacked-NWs /-FETs.

https://hal-cea.archives-ouvertes.fr/cea-01973383/document

Vertically stacked-NanoWires MOSFETs in a replacement metal gate process with inner spacer and SiGe source/drain

We have fabricated hybrid channel Ω-gate CMOS nanowires (NWs) with strained SiGe-channel (cSiGe) p-FETs and Si-channel n-FETs. An optimized process flow based on the Ge enrichment technique results in a +135% hole mobility enhancement at long gate lengths compared to Si. Effectiveness of cSiGe channel is also evidenced for ultra-scaled p-FET NWs (gate length L G =15 nm) with +90% I ON current improvement.

Dual-channel CMOS co-integration with Si NFET and strained-SiGe PFET in nanowire device architecture featuring sub-15nm gate length

The Nano Wire (NW) CMOS technology is widely considered as a promising evolutionary solution of current FinFET technology. The main advantage of the nanowire transistors for ultimate CMOS scaling is their optimal electrostatic confinement. In this paper, the major assets of NW field-effect-transistors in leading-edge technology nodes are explained in details. For this purpose, electron (hole) transport properties of Si (SiGe) NWs and the critical contribution of strain are discussed. A particular attention is given to the key technological integration challenges to be addressed, with emphasis on the practical implementation of 3D high-density stacked-NWs architectures.

L. Gaben

Papers

Vertically stacked-NanoWires MOSFETs in a replacement metal gate process with inner spacer and SiGe source/drain

Dual-channel CMOS co-integration with Si NFET and strained-SiGe PFET in nanowire device architecture featuring sub-15nm gate length

Opportunities and challenges of nanowire-based CMOS technologies