US 7,741,131 B2Granted

Laser processing of light reflective multilayer target structure

AssigneeElectro Scientific Industries, Inc.

InventorsYunlong Sun, Steve Harris

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Abstract

A solution to an interference effect problem associated with laser processing of target structures entails adjusting laser pulse energy or other laser beam parameter, such as laser pulse temporal shape, based on light reflection information of the target structure and passivation layers stacked across a wafer surface or among multiple wafers in a group of wafers. Laser beam reflection measurements on a target link measurement structure and in a neighboring passivation layer area unoccupied by a link enable calculation of the laser pulse energy adjustment for a more consistent processing result without causing damage to the wafer. For thin film trimming on a wafer, similar reflection measurement information of the laser beam incident on the thin film structure and the passivation layer structure with no thin film present can also deliver the needed information for laser parameter selection to ensure better processing quality.

Claims21

Dependent claims

A method of laser processing a light reflective structure that has a major surface and includes a multilayer passivation structure and target material supported on a substrate, the light reflective structure characterized by a nonuniform distribution of passivation layer thickness across the major surface, comprising:

obtaining prior knowledge about the nonuniform distribution of the passivation layer thickness across the major surface;
performing a first light beam reflection measurement on a first region of the light reflective structure at a location where a portion of the target material is present, the measurement being performed at a first light beam wavelength while leaving operationally undamaged the first region and the substrate;
performing a second light beam reflection measurement on a second region of the light reflective structure in a vicinity of the first region and at a location where a portion of the multilayer passivation structure is present and where the target material is not present, the measurement being performed at a second light beam wavelength while leaving operationally undamaged the second region and the substrate and, the first and second light beam wavelengths being the same;
and
processing the first and second light beam reflection measurements to calculate absorption difference corresponding to the first and second light beam reflection measurements and the prior knowledge to determine a processing laser output parameter for laser processing a selected portion of target material in proximal location to the first and second regions.

2 more elements

A method of laser processing a light reflective structure that has a major surface and includes a multilayer passivation structure and electrically conductive link material supported on a substrate, the light reflective structure characterized by a nonuniform distribution of passivation layer thickness across the major surface, and the link material having a link width, comprising:

obtaining prior knowledge about the nonuniform distribution of the passivation layer thickness across the major surface;
providing a scanning light beam producing, when incident on the light reflective structure, a beam spot with a beam spot size that is larger than the link width;
positioning the scanning light beam at a first wavelength to perform a first light reflection measurement at a first location of the light reflective structure where the link material and multilayer passivation structure are present, the scanning light beam having a first beam spot with a beam spot size that covers a first region of the link material and a first region of the multilayer passivation structure outside of the first region of the link material;
positioning the scanning light beam at a second wavelength that is the same as the first wavelength to perform a second light reflection measurement at a second location of the light reflective structure in a vicinity of the first location and where at least one of the link material and multilayer passivation structure are present, the scanning light beam having a second beam spot with a beam spot size that covers at least one of a second region of the link material and a second region of the multilayer passivation structure outside of the link material;
and
processing the first and second beam reflection measurements to determine light reflection information relating to the link material and the multilayer passivation structure and, with the prior knowledge, to determine a processing laser output parameter for laser processing a selected portion of the electrically conductive link material in proximity to the first and second locations.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/754,214Filed 25 May 2007
Published: US 2008/0293166 A127 Nov 2008
Granted: 22 Jun 2010
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

H10P 34/42
With high-energy radiation: with electromagnetic radiation, e.g. laser annealing
H10P 74/203
Characterised by the properties tested or measured, e.g. structural or electrical properties: structural properties, e.g. testing or measuring…
H10P
Generic processes or apparatus for the manufacture or treatment of devices covered