(Invited) Advanced CMOS Device Technologies Discussed Also with Transition-Metal Di-Chalcogenide (TMDC) Channel

Abstract

Advanced CMOS device technology for a high-performance system-on-a-chip (SoC) LSI is firstly discussed by using benchmarking of published data [1-6], mainly-highlighted by a FinFET and beyond, as shown in Fig. 1. To enhance the performance of FinFET devices, a low-voltage operation less than 0.7 V with smaller variability of characteristics is highly required rather than an enlargement of channel width (W_eff / W_footprint). Here, W_eff and W_footprint mean effective and footprint channel widths. After that, higher-mobility channel devices are strongly needed with superimposed manner having an InGaAs high-electron mobility transistor (HEMT), InGaAs quantum well (QW), InAs QW, and InGaAs MISFET having an appropriate smaller bandgap. In this case, smooth thin-channel is promising to suppress the variability of characteristics. Therefore, an atomically-consistent semiconductor material such as a graphene and transition-metal di-chalcogenide (TMDC) are favorable candidates. Although the graphene has a zero band-gap, the TMDCs have superior properties such as an appropriate bandgap, for example, 1.2 eV in single-layer MoS₂ film. Furthermore, they also yield higher mobility, transparent and mechanical robustness.

In our experiments, a higher Hall mobility of electron with 28 cm²/Vs in 10-nm-thick MoS₂ film is achieved even by using a magnetron sputtering process with MoS₂ target for channel formation [7]. This might be caused by a suppression of carrier scattering due to contaminations such as alkali metals of sodium and potassium, impurities, crystal defects, and film roughness in the MoS₂ film.

In conclusion, the TMDC-channel MISFET could be suitable for high-performance SoC LSIs as not only advanced CMOS devices but also monolithic transistor to enhance the functionalities per chip area. Furthermore, it has a strong possibility achieving not only more-Moore and more-than-Moore but also more-comfort properties for high-performance human-interface (I/F) devices such as a transparent and flexible display.

Acknowledgements

This work was partially supported by JSPS Grant-in-Aid for Scientific Research on Innovative Areas: Grant Number 26105014, and the Center of Innovation Program from Japan Science and Technology Agency, JST.

References

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[2]     S. Natarajan, et al., in IEDM, 3.7, p. 71, 2014.

[3]     M. Radosavljevic, et al., in IEDM, p. 319, 2009.

[4]     Alireza Alian, et al., in IEDM, p. 437, 2013.

[5]     S.W. Chang, et al., in IEDM, 16.1, p. 417, 2013.

[6]     J. A. del Alamo, et al., in IEDM, p. 578, 2014.

[7]     Takumi Ohashi, Hitoshi Wakabayashi, et al. “Multi-layered MoS₂ film formed by high-temperature sputtering for enhancement-mode nMOSFETs,” in 2015 Jpn. J. Appl. Phys. 54 04DN08, doi:10.7567/JJAP.54.04DN08.