Regarding onstate performance, 2d materials with moderate transport properties like mos2 become competitive at channel lengths around 5nm, due to the. There are physical limitations to the extent of scaling. In this work, fundamental design metrics of analog circuits using twodimensional transition metal dichalcogenide 2dtmd molybdenum disulfide mos 2 transistors are systematically investigated and compared with the stateoftheart silicon mosfets. Small geometry effects design of highdensity chips require a packing density as high as possible.
Sg 4layer fet had a smaller ionioff and a larger ssmin 105. In order to realize high performance mos2 mosfets, three major issues needs to be. The scaling of mosfets, moores law, and itrs chapter 2 8 2. Thapar university, patialasunday, march 12, 2017 9 fig. Channel length scaling of mos2 mosfets han liu, adam t. We compare the short channel behavior of sets of mosfets with various channel thickness, and reveal the superior immunity to short channel effects of mos2 transistors. Device scaling should be carried out with appropriate limits on dimensions for proper behavior 7. Mosfet channellength modulation technical articles. We observe no obvious short channel effects on the device with 100 nm channel length lch fabricated on a 5 nm thick mos2 2d crystal even when using 300 nm thick sio2 as gate dielectric, and has a current onoff ratio up to 109. Lead resistances, capacitances, and inductances clif fonstad, 31808 lecture 11 slide 1. Other hand with different gate voltage, drain current for smaller gate length more than other tows. Section iii describes research results related to this fundamental limit regime.
Mos2 fieldeffect transistor with sub10nm channel length. Pdf mos2 fieldeffect transistor with sub10nm channel length. Mosfets in ics scaling, leakage, and other topics chapter objectives how the mosfet gate length might continue to be reduced is the subject of this chapter. Immunity to contact scaling in mos2 transistors using in. Scaling length theory of doublegate interband tunnel. Highperformance silicon transistors can have gate lengths as short as 5 nm before sourcedrain tunneling and loss of electrostatic control lead to unacceptable leakage current when the device is off. Cmos technology scaling gate length has not scaled proportionately with device pitch 0. Classical discussions on short channel effects are mostly based on silicon mosfets. The current flows due to the flow of negatively charged electrons, also known as n channel mosfet. Channel length scaling of mos2 mosfets by han liu, adam.
A ushape mos 2 pmosfet with 10nm channel and polysi sourcedrain is demonstrated. Lecture 25 mosfet basics understanding with math reading. A comprehensive study on impact of channel stress on ultrathinbody fdsoi mosfets is presented. As the scaling of silicon mosfet approaches to its physical limit, research efforts have been made in exploring alternative devices. When v t drops too much, i off becomes too large and that channel length is not acceptable. Short channel monolayer mos2 fieldeffect transistors. If the mosfets channel length between source and drain becomes small enough for electrons to tunnel through the barrier without the gate bias, it can no longer be operated as a switch. The thermionic limit of ss due to boltzmann distribution of electrons in conduction band, which is around 60 mvdec at room temperature, prevents. Pdf mos2 fieldeffect transistor with sub10nm channel. In this article, we investigate electrical transport properties in ultrathin body utb mos2 twodimensional 2d crystals with channel lengths ranging from 2 mu m down to 50 nm.
Its found that straininduced mobility enhancement diminishes with silicon body thickness scaling below 5nm for electrons, but not for holes. Short channel effects in mosfet with junctions, part of the reduction of the threshold short channel effects is due to the presence of a spacecharge region where vth0 is the long channel threshold voltage. Channel length modulation occurs in all field effect transistors, not just mosfets. Therefore, making an enhancementmode mos2 mosfet is quite challenging. One of several short channel effects in mosfet scaling, channel length modulation clm is a shortening of the length of the inverted channel region with increase in drain bias for large drain biases. There is a 1nm sourcegate overlap in sentaurus and omen. In this article, we investigate electrical transport properties in ultrathin body utb mos2 twodimensional 2d crystals with channel lengths ranging from 2. Mos2 transistors associated with channel length scaling must also be investigated. Magnitude of internal electric fields is kept constant. T28 97848634850 2015 symposium on vlsi technology digest of technical papers 15nm channel length mos2 fets with single and doublegate structures a. Here, we show that clean edge contacts to 2d mos 2 can provide immunity to the contact scaling problem, with performance that is independent of contact length down to the 20 nm regime. We observe no obvious short channel effects on the device with 100 nm channel length lch fabricated on a 5 nm thick mos2 2d crystal even when using 300 nm thick sio2 as gate. Our study therefore suggests that germanane mosfets represent a viable option for. Figures 5cd summarizes the length dependence of devices performance.
In this article, we investigate electrical transport properties in ultrathin body utb mos2 twodimensional 2d crystals with channel lengths ranging from 2 \mum down to 50 nm. Design and analysis of mos2based mosfets for ultralow. A metal or polycrystalline gate covers the region between source and drain, but is separated from the. Short channel junctionless nanowire transistors free download 3. Ye school of electrical and computer engineering and birck nanotechnology center, purdue university 1205 west state street, west lafayette, in.
In these figures see that increscent of gate length increasing slope of iv carve and g m. Effectiveness of strain solutions for nextgeneration. Channel length scaling of mos2 transistors we fabricated sets of mos2 mosfets with various channel length. Thus, we can study the channel length scaling of monolayer mos 2 fets. Straininduced carrier transport enhancement is maintained with gate. An n channel mosfet has a gate width to length ratio of zl100, u n 200 cm2vsec, cox0. However, the power dissipation challenge for transistor scaling remains unchanged as siliconbased mosfets. The yield was greater than 50% in terms of effective gate control with lessthan10 v threshold voltage, even for mosfets having deepsubmicron gate length. One important topic is the offstate current or the leakage current of the mosfets. The systematic reduction in the dimensions of devices is referred to as mosfet scaling. Mos2, mosfet, short channel effects, contact resistance. On monolayer mos2 fieldeffect transistors at the scaling limit. Phaseengineered lowresistance contacts for ultrathin mos.
The transfer curves of five mos 2 fets with different channel length are shown in figure 5a for v sd 1 v. Ye school of electrical and computer engineering and birck nanotechnology center, purdue university, west lafayette, indiana 47906, united states in thepastdecade,asscalingofsiliconbased transistor has approached its physical limit, intensive e. Request pdf on monolayer mos2 fieldeffect transistors at the scaling limit the. Transistor performance has been boosted by other means. Scaling of the conventional mosfet devices chapter 4 87 4.
Based only on these fundamental limits, it may be possible to scale fets down to very small dimensions, e. Thus, channellength modulation means that the saturationregion drain current will increase slightly as the draintosource voltage increases. Contact length scaling remains an unresolved epidemic for transistor scaling, a. The activity of mos2 can now be enhanced by facilitating electron injection from the electrode to the catalyst. The resistance of the channel is proportional to its widthto length ratio. This topic complements the discourse on the onstate current conducted in the previous chapter. Mos2 transistors with 1nanometer gate lengths science. Gate length l g versus channel length l and experimental data versus. Each set was fabricated on the same rectangular mos2 flake, so the scaling effect can be directly observed and compared without needing to correct for geometry and thickness variations. However for the mos 2 transistors, the origins and behaviors of short channel effects. In this regime, conventional models for the scaling length 4 are not valid figs. Transistors fabricated should have sizes as small as possible. Phaseengineered lowresistance contacts for ultrathin mos 2 transistors.