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James N. O'brien

Bio: James N. O'brien is an academic researcher from Electro Scientific Industries, Inc.. The author has contributed to research in topics: Laser & Wafer dicing. The author has an hindex of 9, co-authored 15 publications receiving 745 citations.

Papers
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Patent
06 Jul 1995
TL;DR: In this paper, the output of a continuously pumped, Q-switched, Nd:YAG laser (10) is frequency converted to provide ultraviolet light for forming vias (72, 74) in multi-layered targets (40).
Abstract: 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.

258 citations

Patent
07 Jun 2002
TL;DR: In this paper, a long cut path is divided into short segments, from about 10 µm to 1 mm, and the laser output is scanned within a first short segment for a predetermined number of passes before being moved to and scanned within another short segment (122) for a certain time interval.
Abstract: UV laser cutting throughput through silicon and like materials is improved by dividing a long cut path (112) into short segments (122), from about 10 µm to 1 mm. The laser output (32) is scanned within a first short segment (122) for a predetermined number of passes before being moved to and scanned within a second short segment (122) for a predetermined number of passes. The bite size, segment size (126), and segment overlap (136) 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 (32) 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.

208 citations

Patent
27 Mar 2009
TL;DR: In this article, an improved method for singulation of compound electronic devices using laser processing has been presented, which provides fewer defects such as cracking or chipping of the substrates while minimizing the width of the kerf and maintaining system throughput.
Abstract: 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.

94 citations

Patent
21 May 2007
TL;DR: In this paper, a q-switched CO 2 laser is used to scribe wafers to reduce or eliminate chipping and cracking in the passivation and/or encapsulation layers.
Abstract: Systems and methods are provided for scribing wafers (300) to efficiently ablate passivation and/or encapsulation layers (302, 304) while reducing or eliminating chipping and cracking in the passivation and/or encapsulation layers (302, 304). Short laser pulses are used to provide high peak powers and reduce the ablation threshold. In one embodiment, the scribing is performed by a q-switched CO 2 laser.

46 citations

Patent
28 Jun 2002
TL;DR: In this paper, a multistep process (28) for dicing of, or drilling of vias in, workpieces (12) such as wafers, that support one or more layers (24) facilitates the optimization of laser or non-laser processes for each layer including the substrate, to improve quality and throughput while reducing adverse affects to the other layers.
Abstract: A multistep process (28) for dicing of, or drilling of vias in, workpieces (12), such as wafers, that support one or more layers (24) facilitates the optimization of laser or nonlaser processes (28) for each layer (24), including the substrate (26), to improve quality and throughput while reducing adverse affects to the other layers (24). An exemplary process employs a UV laser (14) for cutting through layers (24) that are transparent to IR or visible wavelengths and a different laser (14) or cutting blade for dicing the substrate (26) to minimize damage to the layers (24). A multistep processing technique can be used to mitigate or repair damage that occurs during dicing or drilling processes, to improve the lifetime of the mechanical saw, or to facilitate singulation of the greatest number of undammaged dies from a workpiece (12).

33 citations


Cited by
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Patent
02 Feb 2005
TL;DR: In this article, a method of dividing a wafer having a plurality of devices, which are formed in a plurality-of areas sectioned by streets forming in a lattice pattern on the front surface, and having test metal patterns formed on the streets, is described.
Abstract: A method of dividing a wafer having a plurality of devices, which are formed in a plurality of areas sectioned by streets formed in a lattice pattern on the front surface, and having test metal patterns which are formed on the streets, comprising the steps of: a laser beam application step for carrying out laser processing to form a dividing start point along a street on both sides of the test metal patterns by applying a laser beam along the street on both sides of the test metal patterns in the street formed on the wafer; and a dividing step for dividing the wafer which has been laser processed to form dividing start points along the dividing start points by exerting external force to the wafer, resulting in leaving the streets having the test metal patterns formed thereon behind.

262 citations

Patent
27 Nov 2002
TL;DR: In this article, the uniformity of laser annealing can be improved by the minimum number of homogenizers, which is shown to be the case in the case of linear laser light.
Abstract: There are disposed two homogenizers for controlling an irradiation energy density in the longitudinal direction of a laser light transformed into a linear one which is inputtted into the surface to be irradiated. Also, there is disposed one homogenizer for controlling an irradiation energy density in a width direction of the linear laser light. According to this, the uniformity of laser annealing can be improved by the minimum number of homogenizers.

259 citations

Patent
19 Dec 2000
TL;DR: In this article, an energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided.
Abstract: An energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided. The system includes a controller for generating a processing control signal and a signal generator for generating a modulated drive waveform based on the processing control signal. The waveform has a sub-nanosecond rise time. The system also includes a gain-switched, pulsed semiconductor seed laser for generating a laser pulse train at a repetition rate. The drive waveform pumps the laser so that each pulse of the pulse train has a predetermined shape. Further, the system includes a laser amplifier for optically amplifying the pulse train to obtain an amplified pulse train without significantly changing the predetermined shape of the pulses. The amplified pulses have little distortion and have substantially the same relative temporal power distribution as the original pulse train from the laser. Each of the amplified pulses has a substantially square temporal power density distribution, a sharp rise time, a pulse duration and a fall time. The system further includes a beam delivery and focusing subsystem for delivering and focusing at least a portion of the amplified pulse train onto the target material. The rise time (less than about 1 ns) is fast enough to efficiently couple laser energy to the target material, the pulse duration (typically 2-10 ns) is sufficient to process the target material, and the fall time (a few ns) is rapid enough to prevent the undesirable changes to the material surrounding the target material.

234 citations

Patent
07 Jun 2002
TL;DR: In this paper, a long cut path is divided into short segments, from about 10 µm to 1 mm, and the laser output is scanned within a first short segment for a predetermined number of passes before being moved to and scanned within another short segment (122) for a certain time interval.
Abstract: UV laser cutting throughput through silicon and like materials is improved by dividing a long cut path (112) into short segments (122), from about 10 µm to 1 mm. The laser output (32) is scanned within a first short segment (122) for a predetermined number of passes before being moved to and scanned within a second short segment (122) for a predetermined number of passes. The bite size, segment size (126), and segment overlap (136) 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 (32) 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.

208 citations

Patent
28 Jul 2010
TL;DR: In this paper, a method of cutting a glass sheet that has been thermally or chemically strengthened along a predetermined line, axis, or direction with high speed and with minimum damage on the cut edges is presented.
Abstract: A method of cutting a glass sheet that has been thermally or chemically strengthened along a predetermined line, axis, or direction with high speed and with minimum damage on the cut edges. The strengthened glass sheet may be cut into at least two pieces, one of which having a predetermined shape or dimension. At least one damage line is formed within the strengthened glass sheet. The at least one damage line is formed outside the strengthened compressive stress surface layers and within the tensile stress layer of the strengthened glass sheet. The at least one damage line may be formed by laser treatment. A crack is initiated in the strengthened glass sheet and propagated along the at least one damage line to separate the strengthened glass sheet along the predetermined line, axis, or direction into at least two pieces.

200 citations