Electrical fuse circuit for security applications

Abstract

A fuse circuit is disclosed, which comprises at least one electrical fuse element having a resistance that changes after being stressed in an electromigration mode, a switching device serially coupled with the electrical fuse element in a predetermined path between a fuse programming power supply (VDDQ) and a low voltage power supply (GND) for selectively allowing a programming current passing through the electrical fuse element during a programming operation, and at least one peripheral circuit coupled to the VDDQ, wherein the peripheral circuit is active and draws current from the VDDQ during a fuse programming operation.

Description

Electrical fuse circuits for safety applications technical field The present invention relates to an electrical fuse circuit design, and more particularly to designing a tamper-resistant electrical fuse circuit for security applications. Background technique An e-fuse is known as a logical non-volatile memory for permanently retaining information such as "chip-ID" and the like. A typical example is a laser fuse, where laser energy is used to volatilize metal or polysilicon chains to program the fuse, and a latch is used to sense the resulting resistance change. However, since the pitch of the laser fuse device cannot be reduced below the wavelength of the laser beam (typically 1.06 μm), the laser fuse is not suitable for deep sub-micron technology. To overcome the pitch limitations of laser fuses, an electrical fuse, usually made of silicided polysilicon, is used for programming. When programming an e-fuse, a high current density is applied to the e-fuse link for a spec...

AI Technical Summary

Problems solved by technology

Second, when the PMOS transistor 113 is turned on and a relatively small VDDQ voltage such as 300mV is applied, the e-fuse element 122 will not be stressed enough to cause its resistance to rise

For this reason, the known e-fuse circuit 100 cannot be used in any safety application

Third, it is known that the sensing block 120 is not sensitive enough at low voltages to resolve small resistance changes caused by electromigration in the e-fuse element 122

As noted above, it would be desirable to have an electrically programmable e-fuse circuit in which data stored therein cannot be optically detected or electrically read out by unauthorized means

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