Electro Scientific Industries, Inc.

William J Jordens

Mark Alan Unrath

Hisashi Matsumoto

Xiaoyuan Peng

James S Ismail

Brian J Lineburg

Brian W Baird

David Barsic

Qi S Wang

Yunlong Sun

Kelly Bruland

David Martin Hemenway

Richard S Harris

Glenn Simenson

Stephen Neal Swaringen

Yasu Osako

Weisheng Lei

David A Watt

Daragh Finn

Robert M Pailthorp

Andrew Edwin Hooper

Lei Sun

Lynn Sheehan

Lindsey M Dotson

Jim Dumestre

A laser processing system for micromachining a workpiece includes a laser source to generate laser pulses for processing a feature in a workpiece, a galvanometer-driven (galvo) subsystem to impart a first relative movement of a laser beam spot position along a processing trajectory with respect to the surface of the workpiece, and an acousto-optic deflector (AOD) subsystem to effectively widen a laser beam spot along a direction perpendicular to the processing trajectory. The AOD subsystem may include a combination of AODs and electro-optic deflectors. The AOD subsystem may vary an intensity profile of laser pulses as a function of deflection position along a dither direction to selectively shape the feature in the dither direction. The shaping may be used to intersect features on the workpiece. The AOD subsystem may also provide rastering, galvo error position correction, power modulation, and/or through-the-lens viewing of and alignment to the workpiece.

Acousto-optic deflector applications in laser processing of dielectric or other materials

Tailored laser pulse shapes are used for processing workpieces. Laser dicing of semiconductor device wafers on die-attach film (DAF), for example, may use different tailored laser pulse shapes for scribing device layers down to a semiconductor substrate, dicing the semiconductor substrate, cutting the underlying DAF, and/or post processing of the upper die edges to increase die break strength. Different mono-shape laser pulse trains may be used for respective recipe steps or passes of a laser beam over a scribe line. In another embodiment, scribing a semiconductor device wafer includes only a single pass of a laser beam along a scribe line using a mixed-shape laser pulse train that includes at least two laser pulses that are different than one another. In addition, or in other embodiments, one or more tailored pulse shapes may be selected and provided to the workpiece on-the-fly. The selection may be based on sensor feedback.

Methods and systems for laser processing a workpiece using a plurality of tailored laser pulse shapes

Two pulsed lasers () or sets of lasers propagate beams of pulses () having orthogonally related polarization states. A beam combiner () combines the orthogonal beams to form a combined beam propagating along a common beam path () to intersect an optical modulator () that selectively changes the polarization state of selected pulses of either beam to provide a composite beam () including similarly polarized pulses from the orthogonal beams. The composite polarized beam has a composite average power and a composite repetition rate that are greater than those provided by either laser. The optical modulator can also selectively control the polarization states of pulses from either laser to pass through or be blocked by a downstream polarizer (). Additional modulators may facilitate pulse shaping of the pulses. The system is scalable by addition of sets of single lasers or pairs of lasers with beam combiners and modulators.

Combining multiple laser beams to form high repetition rate, high average power polarized laser beam

Laser pulse shaping techniques produce tailored laser pulse spectral output. The laser pulses can be programmed to have desired pulse widths and pulse shapes (such as sub-nanosecond to 10 ns-20 ns pulse widths with 1 ns to several nanoseconds leading edge rise times). Preferred embodiments are implemented with one or more electro-optical modulators receiving drive signals that selectively change the amount of incident pulsed laser emission to form a tailored pulse output. Triggering the drive signal from the pulsed laser emission suppresses jitter associated with other stages of the link processing system and substantially removes jitter associated with pulsed laser emission build-up time.

Laser micromachining using programmable pulse shapes

A programmable laser pulse combines electrical modulation of the pulse frequency and optical modulation of the pulse shape to form laser pulses of prescribed pulse shapes. A prescribed pulse shape features high peak power and low average power. The laser system disclosed also allows for power-scaling and nonlinear conversions to other (shorter or longer) wavelengths. The system provides an economical reliable alternative to using a laser source with high repetition rates to achieve shaped pulses at a variety of wavelengths. The combinatorial scheme disclosed is inherently more efficient than existing subtractive methods.

Generating laser pulses of prescribed pulse shapes programmed through combination of separate electrical and optical modulators

A specially shaped laser pulse energy profile characterized by different laser wavelengths at different times of the profile provides reduced, controlled jitter to enable semiconductor device micromachining that achieves high quality processing and a smaller possible spot size.

Synchronization technique for forming a substantially stable laser output pulse profile having different wavelength peaks

High speed removal of material from a specimen employs a beam positioner for directing a laser beam axis along various circular and spiral laser tool patterns. A preferred method of material removal entails causing relative movement between the axis of the beam and the specimen, directing the beam axis at an entry segment acceleration and along an entry trajectory to an entry position within the specimen at which laser beam pulse emissions are initiated, moving the beam axis at a circular perimeter acceleration within the specimen to remove material along a circular segment of the specimen, and setting the entry segment acceleration to less than twice the circular perimeter acceleration.

Methods for processing holes by moving precisely timed laser pulses in circular and spiral trajectories

A method and system increase the quality of results achieved by laser micromachining systems. Data relating to parameters controlling laser micromachining process are recorded during the micromachining process, identified by the feature associated with the parameters used to micromachine, and stored on the system. The stored data can be either retrieved during the micromachining process to enable real time control or retrieved after workpiece processing to conduct statistical process control.

Energy monitoring or control of individual vias formed during laser micromachining

A Q-switched solid state laser system (,) operates in a pulse processing control system (,) that employs an autopulse mode and a pulse-on-position mode to stabilize the pulse-to-pulse laser energy delivered to a workpiece (,) that is moved by an X-Y positioner (,). In the autopulse mode, laser pulses are emitted at a near maximum PRF, but the pulses are blocked from reaching the workpiece by an external modulator (,), such as an acousto-optic modulator (&ldquo;AOM&rdquo;) or electro-optic modulator (also referred to as a Pockels cell). In the pulse-on-position mode, the laser emits a pulse in response to the positioner moving to a location on the workpiece that coincides with a commanded coordinate location. The processing control system delivers a stream of coordinate locations, some requiring processing, at a rate that moves the positioner and triggers the laser at about the near maximum PRF. The pulse processing control system sets the AOM to a transmissive state whenever a coordinate location requiring processing is commanded and otherwise sets the AOM to a blocking state. This pulse timing technique provides a nearly constant interpulse period for the laser, thereby improving its pulse-to-pulse energy stability at the near maximum PRF.

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Beaverton, OR, United States of America

William J Jordens