Laser scan sequencing and direction with respect to gas flow

Patent metadata

Field	Value
Publication number	US-2017057016-A1
Application number	US-201615233364-A
Country	US
Kind code	A1
Filing date	Aug 10, 2016
Priority date	Aug 26, 2015
Publication date	Mar 2, 2017
Grant date	—

Abstract

Employing laser scanning directions ( 20 ) that are oblique to and against a predominant gas flow direction ( 25 ) equalize the quality and waviness characteristics of orthogonal scribe lines ( 26 ) made by the laser scans. Positioning and sequence of multiple scan passes to form a feature wider than the width of a scribe line ( 26 ) can be controlled to enhance quality and waviness characteristics of the edges of the feature.

First claim

1 . 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 cumulative gas flow characteristics across at least the portion of the major surface 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 that is obliquely oriented opposite to the predominant gas flow direction; 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 that is obliquely oriented opposite to the predominant gas flow direction, wherein the second laser scan direction is transverse to the first laser scan direction.

2 . The method of claim 1 , wherein the second scan direction is orthogonal to the first scan direction.

3 . The method of claim 1 , wherein the first scan direction is at a 135°±5.125° angle with respect to the predominant gas flow direction.

4 . The method of claim 3 , wherein the second scan direction is at a 225°±5.125° angle with respect to the predominant gas flow direction.

5 . The method of claim 1 , wherein the predominant gas flow direction remains generally the same during scans along the first laser scan direction and the second laser scan direction.

6 . The method of claim 1 , wherein the laser-induced material effect forms elongated scan features along the first and second laser scan directions, wherein the elongated scan features exhibit a perpendicular width having a standard deviation of less than 0.5 microns.

7 . The method of claim 1 , wherein the laser-induced material effect forms a first scan feature along the first laser scan direction, wherein the first scan feature has opposing first primary and first secondary edges, wherein the laser-induced material effect forms a second scan feature along the second laser scan direction, wherein the second scan feature has opposing second primary and second secondary edges, wherein each of the edges can be expressed as a respective average straight fit line, wherein horizontal peaks and valleys of each edge can be expressed as absolute values with respect to the respective average straight fit line, wherein a standard deviation of the absolute values of each edge to its respective average straight fit line is less than 0.3 microns.

8 . The method of claim 1 , wherein scanning the laser beam in the first laser scan direction employs one or more of: a galvanometer-driven minor, a fast-steering minor, a rotating polygon scanner, and an acousto-optic device.

9 . The method of claim 1 , wherein the cumulative gas flow along the predominant gas flow direction is continuous during and between the step of scanning a laser beam in a first laser scan direction of relative movement and the step of scanning the same laser beam or a different laser beam in a second laser scan direction.

10 . The method of claim 1 , wherein the laser beam processing axis moves within a scan field, wherein the scan field includes a laser processing field that is smaller than or equal in area to the scan field, wherein the cumulative gas flow along the predominant gas flow direction is maximized with respect to flow dynamics encompassing the processing field, and wherein a velocity of scanning the laser beam in the first scan direction is maximized with respect to a parameter recipe that achieves desirable quality of the laser induced effect.

11 . The method of claim 1 , wherein the step of scanning the laser beam in the first laser scan direction of relative movement comprises scanning the laser beam along multiple parallel scan paths in the first laser scan direction before the step of scanning the same laser beam or a different laser beam in a second laser scan direction of relative movement.

12 . The method of claim 1 , wherein the laser beam processing axis moves within a scan field, wherein the scan field includes a laser processing field that is smaller than or equal in area to the scan field, wherein the processing field has a rectangular perimeter, and wherein the first scan direction is parallel to a diagonal axis of the processing field.

13 . The method of claim 1 , wherein the laser beam processing axis moves within a scan field, wherein the scan field includes a laser processing field that is smaller than or equal in area to the scan field, wherein the processing field has a major axis dimension of a major axis that bisects the processing field, wherein the gas input direction is generally perpendicular to the major axis of the processing field, wherein a gas flow volume traveling along the gas input direction has a flow width dimension that is perpendicular to the gas input direction, and wherein the flow width dimension is greater than the major axis dimension.

14 . The method of claim 1 , wherein the laser beam processing axis is provided with continuous motion during and between the step of scanning a laser beam in a first laser scan direction of relative movement and the step of scanning the same laser beam or a different laser beam in a second laser scan direction.

15 . The method of claim 1 , wherein the laser beam processing axis moves within a scan field, wherein the step of scanning a laser beam in a first laser scan direction of relative movement and the step of scanning the same laser beam or a different laser beam in a second laser scan direction are each performed over multiple neighboring scan fields over the workpiece while maintaining the predominant gas flow direction of the gas input flow and the gas outtake flow.

16 . The method of claim 1 , wherein laser beam impingement of the workpiece creates 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, and wherein the first ands second laser scan directions with respect to the predominant gas flow direction inhibit the one or more localized adverse gas characteristics.

17 . The method of claim 1 , wherein the workpiece includes one or more features having a feature orientation, wherein the processing station has a first process

Assignees

• Electro Scient Ind Inc

Inventors

• Finn Daragh
• Ferguson Robert A

Classifications

• B23K26/14

  using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor (B23K26/12 takes precedence) · CPC title

• B23K26/10

  using a fixed support {, i.e. involving moving the laser beam} · CPC title

• B23K26/38 Primary

  by boring or cutting · CPC title

• G01N1/22

  in the gaseous state {(specially adapted for biological material G01N33/497; measuring breath flow A61B5/087)} · CPC title

• G01N21/8851 Primary

  Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges (G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002) · CPC title