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Thermal Overstress Fuse

IP.com Disclosure Number: IPCOM000008158D
Publication Date: 2002-May-22
Document File: 3 page(s) / 72K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is an approach that uses a circuit to detect when a thermal diode on a microprocessor reaches a set maximum temperature and blows a low-voltage fuse. Benefits include, by reading the fuses and knowing the maximum temperature during testing or stressing, being able to optimize stress/test temperatures to minimize occurrences of thermal runaway.

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Thermal Overstress Fuse

Disclosed is an approach that uses a circuit to detect when a thermal diode on a microprocessor reaches a set maximum temperature and blows a low-voltage fuse. Benefits include, by reading the fuses and knowing the maximum temperature during testing or stressing, being able to optimize stress/test temperatures to minimize occurrences of thermal runaway.

Background

One of the most difficult aspects of microprocessor failure analysis is determining if a failure is due to over-stressing or an inherent design/manufacturing flaw. This analysis is further complicated by shrinking feature size and an increased transistor count.

Currently, there is no way to permanently record the microprocessor temperature on the device itself. In some cases temperature during stress testing can be recorded externally using a thermal diode, but this method is not always possible or practical. As a result, failure analysis engineers must determine the maximum temperature experienced by an integrated circuit device by examining the extent of damage; for customer returns there is no way to record this information.

General Description

The disclosed approach enables a fuse to be blown when a specified maximum temperature has been reached on a die, allowing failure analysis to determine if a part has been thermally overstressed. The disclosed approach includes monitoring the thermal diode, and triggering the fuse (which may, for example, be similar to the fuses disclosed in one or more of U.S. Patents 5,731,733 and 5,959,455) to blow when a specified pre-set temperature is reached (see Figure 1). This temperature is set during design, but could also be changed to another temperature via a Test Access Port (TAP). Using t...