Electro Scientific Industries, Inc.

James N O'Brien

Yunlong Sun

Lian-Cheng Zou

Brian W Baird

Richard S Harris

Peter Pirogovsky

Michael J Wolfe

Kevin P Fahey

Mark Douglas Owen

Haibin Zhang

David Barsic

Yasu Osako

Clint R Vandergiessen

Andy E Hooper

Jeffery A Albelo

Laser machining fired ceramic and other hard and/or thick materials includes scribing a workpiece with a laser beam along a sequence of parallel laser paths within a cutout region of the workpiece. The scribing creates a kerf in the cutout region that widens as the laser beam advances along the sequence. The sequence may begin with an inner portion of the cutout region and end with an outer edge thereof such that debris is directed away from the laser paths to increase throughput and create a high quality opening in the workpiece. High quality structures may also be cut out from the workpiece. The method includes directing a high velocity stream of gas to an interlace of the laser beam and the workpiece to redirect the flow of debris and cool the interface. The method may also adjust a focus depth of the laser beam as it deepens the kerf.

Laser machining of fired ceramic and other hard and/or thick materials

An improved method for singulation of compound electronic devices is presented. Compound electronic devices are manufactured by combining two or more substrates into an assembly containing multiple devices. Presented are methods for singulation of compound electronic devices using laser processing. The methods presented provide fewer defects such as cracking or chipping of the substrates while minimizing the width of the kerf and maintaining system throughput.

Method for laser singulation of chip scale packages on glass substrates

UV laser cutting throughput through silicon and like materials is improved by dividing a long cut path () into short segments (), from about 10 &#x3bc;m to 1 mm. The laser output () is scanned within a first short segment () for a predetermined number of passes before being moved to and scanned within a second short segment () for a predetermined number of passes. The bite size, segment size (), and segment overlap () can be manipulated to minimize the amount and type of trench backfill. Real-time monitoring is employed to reduce rescanning portions of the cut path(112)where the cut is already completed. Polarization direction of the laser output () is also correlated with the cutting direction to further enhance throughput. This technique can be employed to cut a variety of materials with a variety of different lasers and wavelengths.A multi-step process can optimize the laser processes for each individual layer.

Laser segmented cutting, multi-step cutting, or both

Laser segmented cutting

Laser machining fired ceramic and other hard and/or thick materials includes scribing a workpiece with a laser beam along a sequence of parallel laser paths within a cutout region of the workpiece. The scribing creates a kerf in the cutout region that widens as the laser beam advances along the sequence. The sequence may begin with an inner portion of the cutout region and end with an outer edge thereof such that debris is directed away from the laser paths to increase throughput and create a high quality opening in the workpiece. High quality structures may also be cut out from the workpiece. The method includes directing a high velocity stream of gas to an interface of the laser beam and the workpiece to redirect the flow of debris and cool the interface. The method may also adjust a focus depth of the laser beam as it deepens the kerf.

A solution to failure mechanisms caused by mechanical sawing of a mechanical semiconductor workpiece entails use of a laser beam to cut and remove the electrically conductive and low-k dielectric material layers from a dicing street before saw dicing to separate semiconductor devices. A laser beam forms a laser scribe region such as a channel in the electrically conductive and low-k dielectric material layers, the bottom of the channel ending on a laser energy transparent stop layer of silicon oxide lying below all of the electrically conductive and low-k dielectric material layers. The disclosed process entails selection of laser parameters such as wavelength, pulse width, and fluence that cooperate to leave the silicon oxide layer stop layer completely or nearly undamaged. A mechanical saw cuts the silicon oxide layer and all other material layers below it, as well as the substrate, to separate the semiconductor devices.

Use of laser energy transparent stop layer to achieve minimal debris generation in laser scribing a multilayer patterned workpiece

UV laser cutting throughput through silicon and like materials is improved by dividing a long cut path ( ) into short segments ( ), from about 10 &mgr;m to 1 mm. The laser output ( ) is scanned within a first short segment ( ) for a predetermined number of passes before being moved to and scanned within a second short segment ( ) for a predetermined number of passes. The bite size, segment size ( ), and segment overlap ( ) can be manipulated to minimize the amount and type of trench backfill. Real-time monitoring is employed to reduce rescanning portions of the cut path where the cut is already completed. Polarization direction of the laser output ( ) is also correlated with the cutting direction to further enhance throughput. This technique can be employed to cut a variety of materials with a variety of different lasers and wavelengths.

The output of a continuously pumped, Q-switched, Nd:YAG laser (10) is frequency converted to provide ultraviolet light (62) for forming vias (72, 74) in multi-layered targets (40). The parameters of the output pulses (62) are selected to facilitate substantially clean, simultaneous or sequential drilling or via formation in a wide variety of materials such as metals, organic dielectrics, and reinforcement materials having different thermal absorption characteristics in response to ultraviolet light. These parameters typically include at least two of the following criteria: high average power of greater than about 100 milliwatts measured over the beam spot area, a temporal pulse width shorter than about 100 nanoseconds, a spot diameter of less than about 50 microns, and a repetition rate of greater than about one kilohertz. The laser system (10) and method circumvent conventional depth of cut saturation limitations and can achieve an increased depth of cut per pulse in a target (40) formed of either single- or multi-layered material.

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Bend, OR, United States of America

James N O'Brien