A compact, efficient electrical dual-circuit topology for the representation of transient thermal coupling is presented. Based on controlled sources, the method allows an arbitrary level of complexity to be used for each self and coupled response. Two possible variations on the circuit form, and the resulting requirements for model extraction, are developed. The method is applied to the modeling of transient thermal self-heating and coupling data for a pair of thermal sources representative of integrated device structures in semi-infinite homogeneous as well as trench-isolated substrates.

The prediction of a simple lumped representation of heat sharing through emitter interconnect in high-power multiemitter bipolar devices is compared to numerical thermal simulation and found to exhibit nonphysical results. Using numerical simulation, interfinger metal heat flow is characterized qualitatively in three dimensions and the requirements for a more accurate model are determined. A new modeling approach based on these insights, using segmented emitters and a coarse representation of the metal structure, yields results within 2% of those obtained from numerical thermal simulation for a wide variety of device geometries and substrate materials, with a simulation time reduction of more than an order of magnitude. Using the new model, an extensive series of simulations is performed for devices fabricated in Si, GaAs, and InP substrates using Al and Au for metallization. Reduction in maximum temperature due to the presence of emitter interconnect in these structures is found to be in the range of 5%-15%.

This paper presents a novel three-dimensional (3D) thermal simulation tool for semiconductor integrated devices. The simulator is used to automatically generate an accurate 3D physical model of the device to be simulated from layout information. The simulator produces an appropriate mesh of the device based on a rectangular block structure. The mesh is automatically created such that a fine mesh is produced around heat generation regions, but a moderate number of blocks are used for the entire device. This paper first confirms that the simulator produces an accurate solution to the nonlinear differential equation describing the heat flow. Then model generation from three example technologies (silicon trench, GaAs mesa structures, silicon on insulator) is presented. The potential of the simulator to quickly and easily explore the effect of layout and process variations is illustrated, with the simulation of a two-transistor GaAs power cell as a large example. The program incorporates a transient solver based on a transmission line matrix (TLM) implementation using a physical extraction of a resistance and capacitance network. The formulation allows for temperature dependent material parameters and a nonuniform time stepping. An example of a full transient solution of heat flow in a realistic Si trench device is presented.