An introduction to heat transfer

Introduction to heat transfer

Light emitting diodes reliability review

The growing packing density and power consumption of very large scale integration (VLSI) circuits have made thermal effects one of the most important concerns of VLSI designers The increasing variability of key process parameters in nanometer CMOS technologies has resulted in larger impact of the substrate and metal line temperatures on the reliability and performance of the devices and interconnections Recent data shows that more than 50% of all integrated circuit failures are related to thermal issues This paper presents a brief discussion of key sources of power dissipation and their temperature relation in CMOS VLSI circuits, and techniques for full-chip temperature calculation with special attention to its implications on the design of high-performance, low-power VLSI circuits The paper is concluded with an overview of techniques to improve the full-chip thermal integrity by means of off-chip versus on-chip and static versus adaptive methods

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Thermal Modeling, Analysis, and Management in VLSI Circuits: Principles and Methods

A new evaluation method of thermal transient measurement results

A new method has been developed in order to identify the thermal environment of a semiconductor device chip. The identification algorithm operates on the thermal transient response of the device recorded during a one-shot pulse measurement. A deconvolution operation performed in the logarithmic time domain gives the “time-constant spectrum” of the chip-case-ambient thermal structure. A further transformation leads to the “structure-function” that is the cross-sectional area of the heat conducting materials vs thermal resistance (related to the heat source). The structure function has a good and quantitatively evaluable correspondence to the physical chip environment and heat conducting structure. Separating the different regions of the heat-flow path (corresponding to the chip, bond, header, case) as well as the detection of eventual heat-transport irregularities (mounting errors) is possible.

Fine structure of heat flow path in semiconductor devices: a measurement and identification method

This paper deals with the identification of RC networks from their time- or frequency-domain responses. A new method is presented based on a recent approach of the network description where all response functions are calculated by convolution integrals. The identification is carried out by deconvolution (NID method). This paper discusses the practical details of the method. Special attention is paid to the identification and modeling of distributed RC networks, like the problems of conductive heat-flow. A number of examples make it easy to understand the operation and the capabilities of the NID method. Comparative considerations are given concerning the accuracy and expenses of the NID and the popular AWE (momentum-matching) methods.

Identification of RC networks by deconvolution: chances and limits

Representations of infinite distributed RC one-ports are described. Two functions are introduced: the dipole intensity function (as the generalization of pole-zero pattern) and the time-constant density (as the generalization of the discrete time-constant set of a lumped network). Relations between these representations and the complex impedance are presented. These representations can be regarded as the generalization of the descriptions commonly used in the theory of lumped networks. The representations offer possibilities for the identification and for the synthesis of distributed RC networks. Although the representations were introduced for the case of RC networks, the results can also be applied directly for inductance-resistance networks. The use of the new representations is demonstrated by some examples. >

On the representation of infinite-length distributed RC one-ports

The paper presents appropriate sensors for the realization of the design principle of design for thermal testability (DfTT). After a short overview of the available CMOS temperature sensors, a new family of temperature sensors will be presented, developed by the authors especially for the purpose of thermal monitoring of VLSI chips. These sensors are characterized by the very low silicon area of about 0.003-0.02 mm/sup 2/ and the low power consumption (200 /spl mu/W). The accuracy is in the order of 1/spl deg/C. Using the frequency-output versions an easy interfacing of digital test circuitry is assured. They can be very easily incorporated into the usual test circuitry, via the boundary-scan architecture. The paper presents measured results obtained by the experimental circuits. The facilities provided by the sensor connected to the boundary-scan test circuitry are also demonstrated experimentally.

CMOS sensors for on-line thermal monitoring of VLSI circuits

The paper presents techniques of measuring partial steady state thermal resistance values in a heat flow path with the help of thermal transient measurements and the subsequent numerical evaluation The method is based on the further evaluation of the structure functions of the heat flow path After presenting the theoretical background of the evaluation two different practical examples are presented to demonstrate the use of the method The first example presents a series of experiments on how to use the method to detect die attach and/or soldering failures in packaged devices The second example demonstrates that the method can be applied to measure the very small R/sub th/ values of thin conducting layers Various practical solutions are discussed and demonstrated by simulations The chances and the limits of the methodology are discussed in detail in the conclusion section

Vladimir Szekely

Papers

Fine structure of heat flow path in semiconductor devices: a measurement and identification method

Identification of RC networks by deconvolution: chances and limits

On the representation of infinite-length distributed RC one-ports

CMOS sensors for on-line thermal monitoring of VLSI circuits

Measuring partial thermal resistances in a heat-flow path