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In this paper, for the first time we demonstrate that horizontally stacked gate-all-around (GAA) Nanosheet structure is a good candidate for the replacement of FinFET at the 5nm technology node and beyond. It offers increased W eff per active footprint and better performance compared to FinFET, and with a less complex patterning strategy, leveraging EUV lithography. Good electrostatics are reported at L g =12nm and aggressive 44/48nm CPP (Contacted Poly Pitch) ground rules. We demonstrate work function metal (WFM) replacement and multiple threshold voltages, compatible with aggressive sheet to sheet spacing for wide stacked sheets. Stiction of sheets in long-channel devices is eliminated. Dielectric isolation is shown on standard bulk substrate for sub-sheet leakage control. Wrap-around contact (WAC) is evaluated for extrinsic resistance reduction.

We fabricated firstly body-tied triple-gate NMOSFETs that have fin top width of 30 nm, fin bottom width of 61 nm, fin height of 99 nm, and gate length of 116 nm. Fabrication process steps of the devices are compatible with that of conventional bulk planar channel MOSFET technology and explained in detail in this paper. This MOSFET shows excellent transistor characteristics, such as very low subthreshold swing, Drain Induced Barrier Lowering (DIBL) of 24 mV/V, almost no body bias effect, and orders of magnitude lower I SUB / I D than planar channel DRAM cell transistors. By optimizing process further, it is expected that cost effective body-tied triple-gate MOSFETs can be applied to real Integrated Circuits (ICs).

This paper describes thermal desorption silicon etching (TDSE)/channel-epi transistor, which has improved the profile and the electrical characteristics of channel-epi transistor. Thermal desorption silicon etching (TDSE) process is introduced before Si channel-epi growth using ultrahigh vacuum system to improve transistor performance at dynamic random access memory (DRAM) device. TDSE process for etching active silicon was carried out using Cl2 gas at 700°C in UHV chamber. Following the TDSE process, in-situ Si channel-epi was grown at the same chamber. We evaluated the electrical characteristics of TDSE/channel-epi transistor, and also measured the reliability of gate oxide. Compared with the conventional channel-epi which shows the degradation of transistor characteristics due to the raised active profile, TDSE process with channel-epi presents superior transistor performance in terms of transistor hump characteristics and inverse narrow width effect (INWE). TDSE induced interface and junction leakages, however, are observed. To solve these problems, H2 added TDSE process or H2 anneal process after TDSE has been developed.

FinFET, the milestone for sub-50 nm DRAM cell transistor has been successfully demonstrated by a unique fabricating method with novel concept. We obtained a core solution of front-end-of-line process and structure, focusing on short channel behavior, off-state leakage, and saturation current. We have developed the scheme that is able to suppress off-state leakage current below 1 fA/cell with p+ poly-Si gate. We have also examined mobility and parasitic engineering techniques to maximize the cell performance (DeltaIon > 48 %). In conclusion, we propose the effective guideline for highly manufacturable FinFET for DRAM application at the sub-50 nm node.

Nano scale body-tied FinFETs have been firstly fabricated. They have fin top width of 30 nm, fin bottom width of 61 nm, fin height of 99 nm, and gate length of 60 nm. This Omega MOSFET shows excellent transistor characteristics, such as very low subthreshold swing, Drain Induced Barrier Lowering (DIBL) of 24 mV/V, almost no body bias effect, and orders of magnitude lower I/sub SUB//I/sub D/ than planar type DRAM cell transistors.

A 90 nm generation logic technology with Cu/low-k interconnects is reported. 50 nm transistors are employed using gate oxide 1.3 nm in thickness and operating at 1.0 V. High speed transistors have drive currents of 870 /spl mu/A/pm and 360 /spl mu/A//spl mu/m for NMOS and PMOS respectively, while generic transistors have currents of 640 /spl mu/A//spl mu/m and 260 /spl mu/A//spl mu/m respectively. Low power process using high-k gate dielectrics and SOI process are also provided in this technology. The low-k SiOC material with 2.9 in the k value is used for 9 layers of dual damascene Cu/low-k interconnects. The effective k (k/sub eff/) value of interconnect is about 3.6. Fully working 6-T SRAM cell with an area of 1.1 /spl mu/m/sup 2/ and SNM value of 330 mV is obtained. For MIM capacitor, voltage coefficient of capacitance is less than 20 ppm/V.