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Method for a heatsink/heat spreader integrated device for measuring die temperature gradient

IP.com Disclosure Number: IPCOM000008469D
Publication Date: 2002-Jun-17
Document File: 3 page(s) / 37K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a heat sink/heat spreader integrated device for measuring die temperature gradient. Benefits include improved quality.

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Method for a heatsink/heat spreader integrated device for measuring die temperature gradient

Disclosed is a method for a heat sink/heat spreader integrated device for measuring die temperature gradient. Benefits include improved quality.

Background

              Measuring temperature gradient across the die while a microprocessor is running an application is difficult but extremely important for quality, reliability, and design purposes. For example, transistors at the hot spot of the die have a higher probability of failure than those at a cooler spot, resulting in a differential in probability of failure. Integrating this location-specific failure probability gives a more realistic prediction of device life than assuming equivalent temperature across the entire die. In addition, it is valuable for designers to know this information so that the reliability margins may be appropriately built-in by designing location-specific fixes.

              Conventionally, the temperature gradient across the die can be estimated either by a device circuit simulation or by a direct in-place measurement with the Infrared Emission Scan (IREM) method. Simulations ultimately require experimental validation. The IREM method is typically very difficult to perform. A packaged microprocessor must be re-packaged by removing the integrated heat spreader and thinning the silicon substrate to about 100 microns. A diamond window is installed in the package, through which IR emissions are collected during application. The process is expensive and time consuming. It typically takes several hours to do a single sample measurement.

              An alternative method is to fabricate an array of thermal diodes on the die. This approach is expensive and difficult to implement due to more-complex fabrication of the diodes. This solution also takes precious silicon surface area. However, the multiple thermal diode method may be used to calibrate the device of the disclosed method.

Description

              Disclosed is a method to design and manufacture a microprocessor heat spreader or heatsink with an integrated device for measuring the temperature gradient across the die. A circuit of single-layer metal loops can be deposited on a piece of sapphire or glass. The metal loops are deposited such that they circle around the die’s hot spot. This piece is attached to the integrated heatsink with the loop resistors terminals bonded to a connector. Measuring the resistance change of all the loops in place during an application determines the temperature gradient across the die.

The key elements include:

·        The loop metal resistors are used as thermal sensors because resistance changes with temperature.

·        The design of the loops enables easy measurement of the temperature gradient across the die relative to the hot spot.

·        The device is integrated in the heat spreader so that an in-place measurement can be easily done.

·        The device can be manufactured easily by a single layer metal deposition.

·        The attachment of the sapphire device to t...