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LASER PROGRAMMED SUBSTRATE ANTI-FUSE ELEMENT AND METHOD OF OPERATION

IP.com Disclosure Number: IPCOM000007636D
Original Publication Date: 2002-Apr-10
Included in the Prior Art Database: 2002-Apr-10
Document File: 2 page(s) / 22K

Publishing Venue

Motorola

Related People

Douglas M. Reber: AUTHOR

Abstract

This report describes a new substrate anti-fuse element and method of its operation for semiconductor circuit redundancy or one-time programming applications. This element functions as an electrical diode until it is programmed by laser irradiation; thereafter, it functions as an irreversible electrical short (see Figure 1). To form the diode, a shallow metallurgical junction is formed in a semiconductor substrate by means of ion-implantation or diffusion of the opposite dopant type than the substrate or well that confines the anti-fuse.

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LASER PROGRAMMED SUBSTRATE ANTI-FUSE ELEMENT AND METHOD OF OPERATION

by Douglas M. Reber

This report describes a new substrate anti-fuse element and method of its operation for semiconductor circuit redundancy or one-time programming applications.  This element functions as an electrical diode until it is programmed by laser irradiation; thereafter, it functions as an irreversible electrical short (see Figure 1).  To form the diode, a shallow metallurgical junction is formed in a semiconductor substrate by means of ion-implantation or diffusion of the opposite dopant type than the substrate or well that confines the anti-fuse. 

Subsequent to shallow junction formation, a metal is reacted with the silicon surface to create a salicide that acts as one electrode with the well or substrate acting as the other (Fig 1a).  The circuit fabrication is completed in a similar fashion as is typical of a circuit not containing such an anti-fuse.  To program the active anti-fuse element, a laser pulse train is irradiated on the surface of the salicide.  The laser pulse train is optimized so as to ensure the pulse energy advances the salicide depth to the extent where it shorts the metallurgical junction that previously acted as a diode (Figs. 1b & 1c).


                            (a)                                                       (b)                                          (c)

Figure 1.  Schematic cross-section of the laser programmed substrate anti-fuse element; (a) an electrical diode is formed between a shallow junction and the substrate or a well, (b) a laser pulse train is irradiated on the surface of t...