Patent ID: 6534743
Filing Date: 2003-03-18
Classification: B23K,H01C

Abstract:
A method of laser trimming a film resistor to change from an initial value to a nominal value a parameter of the resistor that includes a film resistor material supported on a substrate, the film resistor material contributing to a determination of the initial value of the parameter, the method comprising:producing a Gaussian beam of at least one laser pulse of UV radiation having an energy density spatial profile of generally Gaussian shape; propagating the Gaussian beam along an optical path through a beam shaping element to convert the Gaussian beam into a transformed beam having a more substantially uniform energy density spatial profile; propagating a major portion of the transformed beam through an aperture to convert it into a target beam that forms a target spot with a substantially uniform energy density spatial profile; directing the target beam onto a target area of the film resistor material to ablate the film resistor material within the target area of the resistor to change its initial value to the nominal value and penetrating the substrate to form a kerf through the film resistor material and uniformly expose a major portion of the substrate within the target area, the substantially uniform energy density spatial profile of the target spot having an effective energy density value that minimizes formations of microcracks in the substrate.