Performance Of High-speed Circuits Research Articles

Flip chip interconnection with anisotropic conductive adhesives for RF and high-frequency applications

Anisotropic conductive adhesives (ACAs) are as promising interconnect materials for flip chip assembly in low cost, high-density, high-speed interconnection packages. We evaluated and compared several flip chip interconnects that use ACAs at the radio frequency (RF) and high-frequency range. The performance of high-speed circuits is limited by the package interconnect discontinuity which is due to large inductance and resistance in the high-frequency range. This discontinuity is determined by the interconnection geometry and materials used. For bumps on the integrated circuit (IC), we used Au studs, Au electroplated and electroless Ni/Au bumps, for the interconnection adhesives, we used two kinds of anisotropic conductive film (ACF) with a different dielectric constant. To evaluate the high frequency model parameters, which we based on an ACF flip chip model and network analysis, we took the high-frequency measurements of test flip chip vehicles that used different bonding materials. Furthermore, to demonstrate real applications for an ACF interconnection at the RF and high-frequency range, we applied ACF flip chip technologies to assemble a passive device that uses an RF integrated passive device. We also applied these technologies to an active device that uses a highly integrated monolithic microwave (IC) device on an RF module. Moreover, we compared the high-frequency characteristics of these devices with those of flip chip assemblies fabricated with conventional methods such as solder ball interconnection.

A CMOS-Compatible Rapid Vapor-Phase Doping Process for CMOS Scaling

An advanced CMOS process, which used rapid vapor-phase doping (RVD) for pMOSFETs and solid-phase diffusion (SPD) for nMOSFETs, has been developed. Using the RVD technique, a 40-nm-deep p-type extension with a sheet resistance as low as 400 /spl Omega//sq has been realized. These RVD and SPD devices demonstrate excellent short-channel characteristics down to 0.1 /spl mu/m channel length and 40% higher drain current, compared with conventional devices with ion implanted source/drain (S/D) extensions, and high-speed circuit performance. We investigate the effect of the S/D extension structure on the device performance and find that a gate extension overlap of 25 nm enables excellent dc and high-speed circuit performance in 0.1-/spl mu/m devices.

Full-wave equivalent circuit model for 2D conductor

A full-wave equivalent circuit model for any arbitrary 2D conductor has been developed. The SPICE-compatible full-wave circuit model could be easily integrated into any circuit-based simulator to study the influence of any conductor on high-speed circuit performance.

GaInP/GaAs HBT's for high-speed integrated circuit applications

GaInP/GaAs HBTs (heterojunction bipolar transistors) have been fabricated to investigate their noise behavior and high-speed circuit performance. The HBT epitaxial structure was grown by MOCVD (metal-organic chemical vapor deposition) with carbon p-type dopant and silicon n-type dopant. The measured 1/f noise is significantly lower than that of the AlGaAs/GaAs HBTs and comparable with that of silicon bipolar transistors. More significantly the noise 'bump' (Lorentzian components) in the intermediate frequency range (10-100 kHz) was not observed. The RF performance of gain blocks and frequency dividers (divide by 4) were measured and found to be comparable with that of the baseline AlGaAs/GaAs HBTs. The V/sub cc/ offset voltage was measured to be less than 140 mV for small size HBTs and 70 mV for large transistors with emitter dimensions of 70 mu m*70 mu m.

Fully self-aligned AlGaAs/GaAs heterojunction bipolar transistors for high-speed integrated-circuits application

Structure optimization, uniformity consideration, and high-speed circuit performance for an AlGaAs/GaAs heterojunction bipolar transistor (HBT) are described. The HBT is fabricated in a fully self-alignment manner using only a single photoresist mask for achieving submicrometer-dimension devices, and, thus reducing parasitic elements. The fabricated HBT's exhibit excellent threshold voltage deviation sigma V/sub BE/=2 mV on a 2-in wafer, a CML gate propagation delay time tau /sub pd/=9.5 ps, and a toggle frequency f/sub tog/=13.3 GHz for a CML divide-by-two frequency divider. >

Gallium arsenide depletion MESFET digital integrated circuits

For many years the GaAs MESFET has provided enhanced performance in a wide range of u. h. f. and microwave systems. GaAs digital i.c.s., also using depletion MESFET technology, are now available in research laboratories of many systems companies and commercially. The basic gate delay of 50 ps provides s.s.i. and m.s.i. functions to exploit the high-speed communications capabilities of optical fibre systems, operating at up to 4 Gbit/s.The main features of the fabrication technology are given for comparison with modern silicon fabrication techniques. Process monitoring for control and device characterization are particularly important to achieve good yield and reproducibility and to minimize the spreads in parameters used for circuit design. High-speed circuit performance depends critically on design and layout and requires careful simulation, including the effects of parasitics and the package. The use of well-characterized ‘function cells’ is advocated to reduce the overall design effort and to improve performance predictability.