A novel laser trimming technique for microelectronics

A novel laser trimming technique, fully compatible with conventional CMOS processes, is described for analogue and mixed microelectronics applications, In this method, a laser beam is used to create a resistive device by melting a silicon area, thereby forming an electrical link between two adjacent p-n junction diodes. These laser diffusible resistances can be made in less than a second with an automated system, and their values can be in the range 100 Omega to a few megaohms, with an accuracy of 50 ppm, by using an iterative process. In addition. these resistances can also be made to possess a TCR (temperature coefficient of resistance) close to 0. We present the method used to create these resistances, the main device characterization and some insight on process modeling. (C) 2002 Elsevier Science B.V. All rights reserved.