Patent ID: 7667159

Claim:
A method for employing laser output to trim resistor material from a resistor to change an initial resistance value of the resistor to a nominal resistance value, wherein the resistor material has a surface area positioned between electrical contacts and is supported on a substrate, wherein laser output applied to the resistor material induces thermoelectric effects in the resistor that cause the resistor to exhibit an errant or transient resistance value that deviates from a true or steady state resistance value of the resistor that is measured during an absence of the laser output such that the applied laser output prevents an accurate measurement of the true or steady state resistance value immediately following the applied laser output, a method for reducing resistance value deviations caused by laser-induced thermoelectric effects, comprising: positioning probes of measurement equipment to be in communication with a single resistor or respective resistors from a set of resistors; setting an applied current value from the measurement equipment to a reference or zero value; directing respective sets of one or more evaluation pulses of laser output along respective simulation paths to apply heat to different respective locations on the surface areas of the single resistor or the respective resistors, the evaluation pulses causing insignificant change to the true or steady-state resistance value of the initial resistance value; measuring voltage values across the single resistor or the respective resistors after the respective sets of evaluation laser pulses to obtain voltage deviation information for each of the different respective locations; using the voltage deviation information to determine a preferred location on the respective surface areas of the respective resistors that exhibits minimal voltage deviation; and directing trimming pulses of laser output along a trim path at the preferred location on the surface area of the single resistor or the preferred locations on the surface area of some or all of the set of resistors to remove resistor material from them to change their initial resistance value to a nominal resistance value to reduce thermoelectric resistance deviations induced by the laser output.