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 Ω 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.