Laser scan sequencing and direction with respect to gas flow

A laser processing system for processing a workpiece having a major surface and one or more features formed on the major surface, wherein the major surface has a surface area, and wherein the laser processing system provides a processing field having a processing field orientation with a first processing field axis and a second processing field axis that is orthogonal to the first processing field axis, comprising:

• a processing station having a processing station orientation with a first processing station axis and a second processing station axis that is orthogonal to the first processing station axis;
• a chuck adapted for placing the workpiece in the processing station at which the workpiece is positionable so that at least one of the features is oriented with respect to the processing station orientation or the processing field orientation;
• a laser adapted for generating a laser beam;
• a beam positioning system including one or more stages for supporting the chuck or the workpiece, the beam positioning system also including a fast-positioner having a scan field that is smaller than the workpiece, wherein the laser processing field is within the scan field such that the laser processing field is smaller than or equal in area to the scan field, wherein the beam positioning system is adapted for positioning the processing field in multiple neighboring locations over the workpiece, and wherein the beam positioning system is adapted for scanning the laser beam along a laser beam processing axis to impinge the workpiece;
• a gas flow assembly that includes a gas input flow device adapted for establishing a gas input flow having a positive gas input velocity in a gas input direction across at least the processing field located over a portion of the major surface of the workpiece, wherein the gas flow assembly also includes a gas outtake port adapted for establishing a gas outtake flow in a gas outtake direction across at least the processing field located over the portion of the major surface of the workpiece, wherein the gas input flow and the gas outtake flow are adapted to establish a predominant gas flow direction across at least the processing field located over the portion of the major surface of the workpiece, and wherein the gas input flow and the gas outtake flow are adapted to cooperate to provide cumulative gas flow characteristics across at least the processing field located over the portion of the major surface of the workpiece;
• and
• a controller adapted to control, within the processing field and while maintaining the gas input flow and the gas outtake flow, scanning the laser beam in a first laser scan direction of relative movement of a laser beam processing axis of the laser beam with respect to the workpiece, such that the first laser scan direction is obliquely oriented opposite to the predominant gas flow direction and such that the laser beam impinges the workpiece along the first laser scan direction affecting the material along the first laser scan direction, wherein the controller is also adapted to control, within the processing field and while maintaining the gas input flow and the gas outtake flow, scanning the same laser beam or a different laser beam in a second laser scan direction of relative movement of a respective laser beam processing axis with respect to the workpiece, such that the second laser scan direction is obliquely oriented opposite to the predominant gas flow direction and such that the laser beam impinges the workpiece along the second laser scan direction affecting the material along the second laser scan direction, and wherein the second laser scan direction is transverse to the first laser scan direction.

A method for enhancing an edge characteristic of a laser-induced material effect resulting from transverse laser scans across a workpiece, comprising:

• relatively orienting a laser processing field and the workpiece at a processing station of a laser processing system;
• establishing, from a gas supply, a gas input flow in a gas input direction across at least a portion of a major surface of the workpiece, wherein gas in the gas input flow has a positive gas input velocity in the gas input direction;
• establishing, from a vacuum source, a gas outtake flow in a gas outtake direction across at least the portion of the major surface of the workpiece, wherein the gas input flow and the gas outtake flow establish a predominant gas flow direction across at least the portion of the major surface of the workpiece, and wherein the gas input flow and the gas outtake flow cooperate to provide a cumulative gas flow having a gas flow velocity across at least the portion of the workpiece;
• while maintaining the gas input flow and the gas outtake flow, scanning a laser beam in a first laser scan direction of relative movement of a laser beam processing axis of the laser beam with respect to the workpiece, wherein the laser beam impinges the workpiece along the first laser scan direction affecting the material along the first laser scan direction and creating one or more localized adverse gas characteristics that could interfere with the capability of the laser beam to impinge the workpiece accurately with respect to a directed position of the laser beam processing axis along the first laser scan direction and could cause fluctuation of the edge characteristic of the laser-induced material effect, wherein the first laser scan direction is transverse to the predominant gas flow direction, wherein the first laser scan direction includes a first laser scan direction component that is parallel with and opposite to the predominant gas flow direction, and wherein the first laser scan direction with respect to the predominant gas flow direction inhibits the one or more localized adverse gas characteristics;
• and
• while maintaining the gas input flow and the gas outtake flow, scanning the same laser beam or a different laser beam in a second laser scan direction of relative movement of a respective laser beam processing axis with respect to the workpiece, wherein the laser beam impinges the workpiece along the second laser scan direction affecting the material along the second laser scan direction and creating one or more localized adverse gas characteristics that could interfere with the capability of the laser beam to impinge the workpiece accurately with respect to a directed position of the laser beam processing axis along the second laser scan direction and could cause fluctuation of the edge characteristic of the laser-induced material effect, wherein the second laser scan direction is transverse to the first laser scan direction, wherein the second laser scan direction is transverse to the predominant gas flow direction, wherein the second laser scan direction includes a second laser scan direction component that is parallel with and opposite to the predominant gas flow direction, and wherein the second laser scan direction with respect to the predominant gas flow direction inhibits the one or more localized adverse gas characteristics.