Logic

Channel backscattering coefficients in the k/sub B/T layer (near the source) of 1.65-nm-thick gate oxide, 68-nm gate length bulk n-channel MOSFETs are systematically separated into two distinct components: the quasithermal-equilibrium mean-free-path for backscattering and the width of the k/sub B/T layer. Evidence to confirm the validity of the separation procedure is further produced: 1) the near-source channel conduction-band profile; 2) the existing value of k/sub B/T layer width from the sophisticated device simulation; and 3) an analytic temperature-dependent drain current model for the channel backscattering coefficients. The findings are also consistent with each other and therefore corroborate channel backscattering as the origin of the coefficients. Other interpretations and clarifications are determined with respect to the very recently released Monte Carlo particle simulation. Consequently, it can be reasonably claimed that the separated components, as well as their dependencies on temperature and bias, are adequate while being used to describe the operation of the devices undertaken within the framework of the channel backscattering theory.

The influence of preamorphization and solid-phase epitaxial regrowth on indium doping profile was discussed. Premorphised silicon significantly reduces channeling during indium ion implantation, producing a much more abrupt doping profile. It is suggested that during recrystallization by thermal annealing, indium segregates in front of the moving amorphous/crystalline interface, creating a clearly visible peak in the doping profile. It was also suggested that the indium segregation phenomenon get enhanced at lower temperatures.

We report solutions to the formidable challenges posed by integrating a HfSiON dielectric with a poly-Si gate for low-power device technology. A 1.5 nm EOT HfSiON is demonstrated with mobility comparable to SiO/sub 2/ and 3 orders of magnitude leakage reduction. A novel boron delta-doped strained-SiGe channel points a way out of the high threshold voltage problem associated with Fermi-pinning at the high-k/poly-Si interface and ameliorates short-channel effects in PMOS devices. In addition, a 20% hole mobility enhancement and 15% I/sub on/-I/sub off/ characteristics improvement are achieved owing to the compressive SiGe channel. NMOS PBTI lifetime of 35 years, and PMOS NBTI and NMOS hot carrier lifetimes of more than 1000 years are demonstrated at 1.2 V.

A highly manufacturable SOI technology with strained silicon and FinFET-like devices is demonstrated for sub-65 nm device scaling. This technology, named FIP-SOI (FinFET/FD/PD-SOI), achieves (1) performance gain of 10-35% for N-MOS using strained silicon compared with non-strained SOI, (2) bulk-to-SOI design portability without additional structures such as the body-contacted transistor scheme, and (3) superior scalability by the incorporation of FinFET-like devices. All feature size scaling (gate length, channel width, and SOI body thickness) will further enhance channel strain in the FIP-SOI. Scaling-strengthened strain is demonstrated for the first time.

Impact of shallow trench isolation (STI) induced mechanical stress on MOSFET drive current is investigated by means of a full-matrix active area layout experiment in advanced CMOS process technology. It turns out remarkably that transistor drive current density per unit width is not independent of the active area size, particularly along the direction of the channel current flow. Opposite sensitivities are observed between n- and p-MOSFETs with respect to lateral active area size. The role of gate placement inside the active area is also addressed. A statistical analysis scheme to find principal components is carried out as well.

This paper discusses an integrated modeling approach for diffusion profiles in advanced CMOS technologies. First, for USJ (Ultra-Shallow Junction) arsenic modeling, in addition to a fully-coupled model with implant damage, amorphous layer formation which depends on the Frenkel pair concentration and evolution of (311) defects and dislocation loops based on EOR (End of Range) defects are also used. Secondly, in order to improve polysilicon activation, a hybrid (arsenic + phosphorus) Source/Drain is used for NMOS. We also address the calibration of the hybrid Source/Drain for with various anneal temperatures. It is shown that modeling of the hybrid Source/Drain profile can be achieved by optimization of the dopant's Fermi level dependent diffusivity and the initial value of the point defect concentration in the equilibrium state. Finally, uphill diffusion at low anneal temperature is observed for BF2 USJ and is enhanced with Ge pre-implants. It is caused by a steep interstitial gradient created by preamorphisation and EOR damage, ultra-shallow boron profile, and boron long-hop diffusion. A BIC (Boron-Interstitial Cluster) model is employed to model boron diffusion after a spike RTA at both extension and S/D regions.

Intensive experiment on highly scaled MOSFETs with mask gate lengths down to 90 nm shows significant sensitivities (up to 10%) of drive current per unit width to the shrinking of active area size down to 0.6 /spl mu/m as well as to the gate placement distance from STI (shallow trench isolation) edge. This suggests the impact of STI induced mechanical stress along the direction of the channel current flow. Even n-and p-channel FETs are observed to behave in opposite trends with respect to the lateral active area size. Mechanical stress simulation of underlying entire front-end process line is conducted also intensively. Systematic analysis turns out strikingly that the experimental drive current sensitivity tracks well the compressive-type strain along the channel, leading to a correlation established between the two. This work promises exploration of mechanical stress issues in future nanoscale devices and circuits.

This paper demonstrates a new compact and scaleable model of mechanical stress effects on MOS electrical performance, induced by shallow trench isolation (STI). This model has included the influence of STI stress not only on the mobility and saturation velocity, but also on the threshold voltage and other important second-order effects. Thus it could simulate the layout dependence of MOS performance with good accuracy and efficiency. We have verified this model with various device dimensions and layout styles of our advanced MOS technologies. And it shows the importance of this new model for circuit design in advanced CMOS generations.

Current foundry technology menus are so rich that they are sufficient to provide single chip solutions to a wide variety of desktop, portable and communication systems. At 130-nm and 90-nm generations, many of the device characteristics are no longer a straightforward extension of past generations. Special attention should be made for mixed-signal chip design. A judicious choice of devices and careful trade-off between version options should be made to maximize the benefit from the latest foundry offerings.