Yihwan Kim

35% drive current improvement from recessed-SiGe drain extensions on 37 nm gate length PMOS

Results from the best reported PMOS transistor at a 37 nm gate length (Lg) built on a process with a recessed SiGe epitaxial layer are discussed. The process details include successful integration of SiGe at the drain extension (DE) location. A highly compressive SiGe layer, in close proximity to the channel, results in large hole mobility improvements. HRTEM based lattice parameter extractions confirm the compressive strain in the channel. In situ doped B in SiGe can be activated to a higher degree than implanted B in bulk Si resulting in further improvements from the lower DE resistance. Both changes combine to give an unprecedented 35% PMOS performance improvement. Process and device simulations that predict the observed parametric behavior quantitatively isolate the improvements to be /spl sim/ 28% from stress and 7% from DE resistance improvement.

Layout impact on the performance of a locally strained PMOSFET

We present a study on the layout dependence of a SiGe S/D PMOSFET technology. While 65% increase in drive current is obtained for 45nm gate length transistors with large active areas, measurements and simulations show that this improvement may be seriously degraded when transistor dimensions, such as the source-drain length (L/sub s/d/) and the device width are further scaled. TDDB and NBTI measurements show that the oxide reliability is not degraded for this technology.

Demonstration of a Ge/GeSn/Ge Quantum-Well Microdisk Resonator on Silicon: Enabling High-Quality Ge(Sn) Materials for Micro- and Nanophotonics

We theoretically study and experimentally demonstrate a pseudomorphic Ge/Ge0.92Sn0.08/Ge quantum-well microdisk resonator on Ge/Si (001) as a route toward a compact GeSn-based laser on silicon. The structure theoretically exhibits many electronic and optical advantages in laser design, and microdisk resonators using these structures can be precisely fabricated away from highly defective regions in the Ge buffer using a novel etch-stop process. Photoluminescence measurements on 2.7 μm diameter microdisks reveal sharp whispering-gallery-mode resonances (Q > 340) with strong luminescence.

A systematic study of trade-offs in engineering a locally strained pMOSFET

We present the results of a study on the impact of process parameters on the performance of strain enhanced pMOSFETs with recessed SiGe S/D. Recess depth, channel length, layout sensitivity, and their subsequent impact on strain and hole mobility are explored. Micro-Raman spectroscopy (/spl mu/RS), process simulations, device simulations, and electrical results are presented. A 30% improvement in drive current is demonstrated.

Hole Mobility Enhancement in Compressively Strained

Germanium tin (GeSn) pMOSFETs with channel Sn composition of 7% are fabricated using a low thermal budget process. GeSn pMOSFETs show enhancement in hole mobility over control Ge devices by 85% in high inversion charge density regime. Hole mobility improvement observed in GeSn channel pMOSFETs compared with Ge control is due to the biaxial compressive strain in GeSn resulting from epitaxial growth of GeSn thin films on relaxed Ge buffer layers.

{\rm Ge}_{0.93}{\rm Sn}_{0.07}

We present a new etch chemistry that enables highly selective dry etching of germanium over its alloy with tin (Ge(1-x)Sn(x)). We address the challenges in synthesis of high-quality, defect-free Ge(1-x)Sn(x) thin films by using Ge virtual substrates as a template for Ge(1-x)Sn(x) epitaxy. The etch process is applied to selectively remove the stress-inducing Ge virtual substrate and achieve strain-free, direct band gap Ge0.92Sn0.08. The semiconductor processing technology presented in this work provides a robust method for fabrication of innovative Ge(1-x)Sn(x) nanostructures whose realization can prove to be challenging, if not impossible, otherwise.

pMOSFETs

Highly activated n-type dopant is essential for n+/p germanium diodes which will be in use for source/drain regions in Ge n-MOSFET as the geometry scaling proceeds. This letter has investigated a combination of ion implantation of Sb in Ge and subsequent laser annealing, which resulted in highly activated Sb beyond 1020 cm-3. Well-behaved Sb-doped nv/p Ge diode I-V characteristics have been demonstrated combined with TEM, SIMS, and spreading resistance profiling characterization.

Highly Selective Dry Etching of Germanium over Germanium–Tin (Ge1–xSnx): A Novel Route for Ge1–xSnx Nanostructure Fabrication

For the first time, high performance Ge nMOSFET is fabricated using laser annealing of ion-implanted antimony (Sb) dopants which provides donor activation beyond 1×10²⁰cm⁻³ in germanium. Record I<inf>on</inf>/I<inf>off</inf> > 10⁵ is demonstrated for n⁺/p junctions combined with significant reduction of contact resistance to 7×10⁻⁷ Ω-cm². Performance projections for ITRS HP 22nm technology node are also discussed.

High n-Type Antimony Dopant Activation in Germanium Using Laser Annealing for

S/D epitaxy remains an effective source of strain engineering for both aggressively and conservatively scaled FinFETs. Not merging the S/D epitaxy between adjacent fins and recess etch into the fin before S/D epitaxy is recommended for maximizing the gain. With high active P concentration Si:C becomes an effective stressor for NMOS. Contact and gate metal fills provide new knobs for engineering strain in FinFET devices for the 22nm node and remain effective with conservative scaling of contact / gate CD only.

\hbox{n}^{+}/\hbox{p}

The effect of phosphorus implantation and thermal annealing on properties of Si:C epitaxial films was investigated. High resolution x-ray diffraction analysis and secondary ion mass spectroscopy indicated that spike annealing only causes slight loss of substitutional carbon. Phosphorus implantation, even with low energy, could cause surface damages and loss of substitutional carbon. Although spike annealing effectively activates implanted phosphorus, it also results in significant substitutional carbon loss (from 1.2% to less than 0.5%) within the phosphorus diffused layer. The interaction of carbon and phosphorus resulted in a junction profile as abrupt as with 3 nm/decade.