Rama Divakaruni

Dual stress liner for high performance sub-45nm gate length SOI CMOS manufacturing

For the first time, tensile and compressively stressed nitride contact liners have been simultaneously incorporated into a high performance CMOS flow. This dual stress liner (DSL) approach results in NFET/PFET effective drive current enhancement of 15%/32% and saturated drive current enhancement of 11%/20%. Significant hole mobility enhancement of 60% is achieved without using SiGe. Inverter ring oscillator delay is reduced by 24% with DSL. Overall yield for the DSL process is comparable to that of a similar technology without DSL. Single and multi-core SOI microprocessors are being manufactured using the DSL process in multiple, high-volume fabrication facilities.

A manufacturable dual channel (Si and SiGe) high-k metal gate CMOS technology with multiple oxides for high performance and low power applications

Band-gap engineering using SiGe channels to reduce the threshold voltage (VTH) in p-channel MOSFETs has enabled a simplified gate-first high-к/metal gate (HKMG) CMOS integration flow. Integrating Silicon-Germanium channels (cSiGe) on silicon wafers for SOC applications has unique challenges like the oxidation rate differential with silicon, defectivity and interface state density in the unoptimized state, and concerns with Tinv scalability. In overcoming these challenges, we show that we can leverage the superior mobility, low threshold voltage and NBTI of cSiGe channels in high-performance (HP) and low power (LP) HKMG CMOS logic MOSFETs with multiple oxides utilizing dual channels for nFET and pFET.

A 7nm FinFET technology featuring EUV patterning and dual strained high mobility channels

We present a 7nm technology with the tightest contacted poly pitch (CPP) of 44/48nm and metallization pitch of 36nm ever reported in FinFET technology. To overcome optical lithography limits, Extreme Ultraviolet Lithography (EUV) has been introduced for multiple critical levels for the first time. Dual strained channels have been also implemented to enhance mobility for high performance applications.

A novel, low-cost deep trench decoupling capacitor for high-performance, low-power bulk CMOS applications

We present an overview and electrical results for a novel deep trench decoupling capacitor. The process of this decoupling capacitor borrows from the regular embedded DRAM trench process, but with significant process simplification for decoupling use which provide reduced cost and reduced process cycle time. This capacitor can provide significant chip-level area savings, using only 1/8 silicon real estate to fabricate the same capacitance as standard planar gate oxide capacitors. Additionally, the trench decap demonstrates a dramatic improvement in leakage compared to standard planar gate oxide capacitors - as much as 105 improvement in leakage can be realized using trench decaps instead of conventional planar decap designs.

New layout dependency in high-k/Metal Gate MOSFETs

We report a new N/PFET Gate Patterning Boundary Proximity layout dependent effect in high-k dielectric/Metal Gate (HK/MG) MOSFETs which causes anomalous threshold voltage (Vt) modulation for the first time. We investigated the mechanism by using special test structures and process optimizations to suppress this layout dependency. Finally, we achieved the best over all process optimization which makes it possible to suppress layout dependency without degrading FET performance/yield/reliability.

Air spacer for 10nm FinFET CMOS and beyond

For the first time, we report integration of air spacers with FinFET technology at 10nm node dimensions. The benefit of parasitic capacitance reduction by air spacers has been successfully demonstrated both at transistor level (15–25% reduction in overlap capacitance (COT)) and at ring oscillator level (10–15% reduction in effective capacitance (Cf)). Key process challenges and device implications of integrating air spacers in FinFET are identified. We propose a partial air spacer scheme, in which air spacers are formed only above fin top and sandwiched by two dielectric liners, as a viable option to adopt air spacers in FinFET technology with minimal risks to yield and reliability.

Effect of Germanium Preamorphization Implant on Performance and Gate-Induced Drain Leakage in SiGe Channel pFET

Silicon-germanium (SiGe) channel pMOSFET is considered as a replacement for silicon channel device for 32-nm node and beyond, because of its lower threshold voltage and higher channel mobility. Lower SiGe bandgap makes gate-induced drain leakage (GIDL) important for low leakage, high threshold voltage device designs. In this letter, the effect of prehalo/LDD Ge preamorphization implant (PAI) on GIDL and performance is investigated using experimental data and simulations. Results suggest that GIDL reduction of ~40% is achieved without Ge PAI and the total OFF-state leakage (IOFF) is reduced by ~50% with a slight reduction in drive current (ION) and similar short-channel effects as compared with the case with PAI for same process conditions, which is not reported yet. The reduction in GIDL, and hence the improvement in ION/IOFF ratio is because of elimination of end-of-range defects at the source/drain sidewall junction regions. It is also shown that a slight reduction in ION in the absence of Ge PAI is because of a small increase in the extrinsic series resistance.

Technology viable DC performance elements for Si/SiGe channel CMOS FinFTT

Low Ge content SiGe-based CMOS FinFET is one of the promising technologies [1-2] offering solutions for both high performance and low power applications. In this paper, we established a competitive SiGe-based CMOS FinFET baseline and examined various elements for high performance offering. The performance elements in gate stack, channel doping, contact resistance, and junction have been explored to provide a cumulative 20% / 25% (n/pFET) performance enhancement. These elements provide a viable path towards performance enhancement for future technology nodes.

A 45nm low power bulk technology featuring carbon co-implantation and laser anneal on 45°-rotated substrate

This paper presents a cost-effective low power 45 nm bulk technology platform, primarily designed to serve the wireless multimedia and consumer electronics need. This technology platform features carbon co-IIP in the nMOS halo, laser annealing scheme, stress liner on the 45°-rotated wafer (<100>) for process simplicity to achieve high device performance and low leakage together. Drive current as high as 650/320 uA/um at Ioff of 0.5 nA/um with Vdd=1.1V has been achieved for both NMOS and PMOS respectively. Ring oscillator speed (FO=1) has been boosted up by 30% with the device optimization. SRAM Vt mismatch is also improved by 10% with carbon co-IIP with good SRAM characteristics and low leakage current in 0.299 um2 cell.

An orthogonal 6F/sup 2/ trench-sidewall vertical device cell for 4 Gb/16 Gb DRAM

This paper describes a novel 6F/sup 2/ trench-capacitor DRAM with a trench-sidewall vertical-channel array transistor. The cell features a line/space pattern for the active area, single-sided buried-strap node contact, vertical transistor channel formed along the upper region of the trench capacitor, a device active area bounded by the isolation trench and capacitor collar, and a single bit contact per cell.