Modeling Tools

IBM has pioneered the first electromagnetic modeling tools in the early 1970's and since it has built up an extensive suite of extremely powerful and accurate solvers. These tools can model the largest problem sizes in the industry, have been verified for accuracy with thousands of practical cases, and are continually evolving to encompass new techniques. They are all part of a user-friendly graphical framework and operate in both time and frequency-domain. The two major algorithms emplyed are Method-of-Moments, MOM, and Partial-Element-Circuit, PEEC.

MOM

These tools are full-wave, 3D, frequency-domain field solvers for calculating radiation, current distribution, and input impedance. They can handle up to 200K current elements today to represent extremely complex package and interconnect structures which is about 20x the capability of typical vendor supplied tools. They can calculate time waveforms for linear networks using FFT, solve eigenvalue problems to determine the frequency-domain characteristics of periodic 3D structures for periodic configurations such as mesh planes, and a special feature is provided for extracting the per-unit-length transmission-line parameters. A typical structure is shown.

The extracted package or interconnect parameters are used in circuit simulators, such as AS/X or PowerSpice, that have superior transmission-line solving algorithms that can handle many coupled lines with frequency-dependent losses very efficiently. This feature is much superior to the general SPICE capability used by most of the Signal Integrity engineers in the industry.

PEEC

Quasi-static inductance L and capacitance C extractors can handle extremely large problem sizes and have been used throughout IBM since 1970 to model most of the IBM products.

Time-domain, full-wave partial-element equivalent circuit (PEEC) solver, including novel circuit simulator is being developed. It combines linear circuit elements and electromagnetic structures in a single analysis. In the future it will handle nonlinear elements. It is well suited for calculating waveforms on planes, chips, and packages.

Characterization

We build special test vehicles for all the packaging technologies in IBM that are being used or planned. These test sites capture the relevant aspects of actual product configurations and processing effects with the minimum area, number of layers, or complexity. Time-domain, high-speed measurements are used to extract material characteristics, such as dielectric loss, resistivity, dielectric constant. Time-domain measurements are made to assess signal integrity performance in actual structure with relevant parasitics and excitations. Special time-domain technique allows extraction of broadband transmission-line matrix elements for evaluation of maximum bandwidth of interconnects. We use the fastest sampling oscilloscope available in the world that has a 70-GHz bandwidth built by Hypres that has a 5-ps source risetime.

Due to the excellent measurement set-ups and techniques used and the accurate modeling and simulation tools we develop, agreement between measurement and simulation is always excellent.

DRAM Development

We lead, as vice-chair, in the JEDEC Future Task Group the effort to define the attributes of next generation, double data rate SDRAM, SDRAM-DDR-II memory. IBM leads the packaging activity in which we contribute with design, modeling, and simulation.

Power and Cooling