Logic

Advanced beyond-silicon electronic technology requires both channel materials and also ultralow-resistance contacts to be discovered. Atomically thin two-dimensional semiconductors have great potential for realizing high-performance electronic devices. However, owing to metal-induced gap states (MIGS), energy barriers at the metal–semiconductor interface—which fundamentally lead to high contact resistance and poor current-delivery capability—have constrained the improvement of two-dimensional semiconductor transistors so far. Here we report ohmic contact between semimetallic bismuth and semiconducting monolayer transition metal dichalcogenides (TMDs) where the MIGS are sufficiently suppressed and degenerate states in the TMD are spontaneously formed in contact with bismuth. Through this approach, we achieve zero Schottky barrier height, a contact resistance of 123 ohm micrometres and an on-state current density of 1,135 microamps per micrometre on monolayer MoS2; these two values are, to the best of our knowledge, the lowest and highest yet recorded, respectively. We also demonstrate that excellent ohmic contacts can be formed on various monolayer semiconductors, including MoS2, WS2 and WSe2. Our reported contact resistances are a substantial improvement for two-dimensional semiconductors, and approach the quantum limit. This technology unveils the potential of high-performance monolayer transistors that are on par with state-of-the-art three-dimensional semiconductors, enabling further device downscaling and extending Moore’s law.

Ultrathin two-dimensional (2D) semiconducting layered materials offer great potential for extending Moore’s law of the number of transistors in an integrated circuit1. One key challenge with 2D semiconductors is to avoid the formation of charge scattering and trap sites from adjacent dielectrics. An insulating van der Waals layer of hexagonal boron nitride (hBN) provides an excellent interface dielectric, efficiently reducing charge scattering2,3. Recent studies have shown the growth of single-crystal hBN films on molten gold surfaces4 or bulk copper foils5. However, the use of molten gold is not favoured by industry, owing to its high cost, cross-contamination and potential issues of process control and scalability. Copper foils might be suitable for roll-to-roll processes, but are unlikely to be compatible with advanced microelectronic fabrication on wafers. Thus, a reliable way of growing single-crystal hBN films directly on wafers would contribute to the broad adoption of 2D layered materials in industry. Previous attempts to grow hBN monolayers on Cu (111) metals have failed to achieve mono-orientation, resulting in unwanted grain boundaries when the layers merge into films6,7. Growing single-crystal hBN on such high-symmetry surface planes as Cu (111)5,8 is widely believed to be impossible, even in theory. Nonetheless, here we report the successful epitaxial growth of single-crystal hBN monolayers on a Cu (111) thin film across a two-inch c-plane sapphire wafer. This surprising result is corroborated by our first-principles calculations, suggesting that the epitaxial growth is enhanced by lateral docking of hBN to Cu (111) steps, ensuring the mono-orientation of hBN monolayers. The obtained single-crystal hBN, incorporated as an interface layer between molybdenum disulfide and hafnium dioxide in a bottom-gate configuration, enhanced the electrical performance of transistors. This reliable approach to producing wafer-scale single-crystal hBN paves the way to future 2D electronics.

We demonstrated that FinFET CMOS logic technologies are capable of ~50% speed increase at constant operating power when operating at 77K, or 0.27× power reduction at constant speed. The benefits arise primarily from steeper SS, carrier transport enhancement, and lower interconnect resistances. Better reliability enables additional speed gain for single-thread computing to ~70%. To extract this benefit, gate work function engineering at the transistor level is necessary. And design technology co-optimization at system level can further bring additional benefits.

For the first time, multiple-Vt (multi-Vt) device options with Vt range> 250 mV are achieved in standard cells at dimensions beyond 7nm technology node. To overcome the common scaling challenges of potential device options such as FinFET and gate all-around (GAA) nanosheet transistor - gate length and cell height scaling, key enablers are identified, including novel, thin, and conformal work function metal (WFM) with enhanced patterning efficiency, high-k (HK) engineering, and precise WFM patterning boundary control. This work enables design flexibility for advanced CMOS technology beyond 7nm node with critical differentiators.

We report on Qualcomm® Snapdragon™ SDM855 mobile SoC and world's first commercial 5G platform using industry-leading 7nm FINFET technologies. SDM855 exhibits CPU performance gain over the previous generation thanks to a new design architecture enabled by dual poly pitch process integration. Low voltage operation and tight spread in power consumption has been achieved through process and design co-development, delivering a high performance and low power solution for both mobile and AI applications. Extending the 7nm technology with 2 nd -year process enhancement demonstrates up to 50mV CPU Vmin reduction without any change to design rules, which paves the road for an integrated 5G mobile platform with connectivity.

Growth of ultrathin semiconducting nanowires (NWs) and incorporation of dopants suitable for future CMOS scaling targets (diameter <20 nm) is a challenge. Limits on dopant incorporation in thin NWs have led to concerns about the suitability of these structures. In this work, the atomic structure of the thinnest InAs NWs ever reported, down to 7 nm diameter, is characterized using transmission electron microscopy (TEM) and atom probe tomography (APT). It is demonstrated that there is no fundamental limit of Sn incorporation into ultrathin InAs NWs. Additionally, the Sn distribution of the Au catalyst particle controlling the growth is characterized.

High performance carbon nanotube (CNT) network transistors with on-resistance (R on ) of <; 250 Ω are successfully integrated as back-end-of-the-line (BEOL) power gating devices onto Si CMOS wafers manufactured using 28-nm process technology. When the power supply is connected through the BEOL CNT network header array, the front-end-of-the-line (FEOL) Si ring oscillators (ROs) achieve a similar quiescent current (I DDQ ) and have the comparable active power (P ACTIVE ) consumption under the same operation frequency as compared to the operation without the power gating CNT transistors. The fabrication of CNT devices in the BEOL is verified to cause no performance degradation in the underlying FEOL Si CMOS devices. This study has successfully demonstrated heterogeneous integration of advanced Si logic circuits with low-cost and high-mobility CNT transistors in the BEOL fabricated at low, BEOL-compatible temperatures (250 °C).

The proliferation of AI and the deployment of 5G networks accelerate the transformation of our society into a highly connected world. Semiconductors are the indispensable elements in realizing all the product innovations. The progress and challenges of the state of art CMOS technology and advanced packaging, considered as critical pillars to continue the improvement of system functions, will be reviewed.

A leading edge 5nm CMOS platform technology has been defined and optimized for mobile and HPC applications. This industry-leading 5nm technology features, for the first time, full-fledged EUV, and high mobility channel (HMC) finFETs with densest 0.021μm 2 HD SRAM. This true 5nm CMOS platform technology is a full node scaling from our successful 7nm node [4] in offering ~1.84x logic density, 15% speed gain or 30% power reduction. The 5nm platform technology successfully passed qualification [3] with consistently high yielding 256Mb HD/HC SRAM, and large logic test chip consisting of CPU/GPU/SoC blocks. Currently in risk production, this true 5nm platform technology is on schedule for high volume production in 1H 2020.