US 8,663,754 B2Granted

Pulsed laser micro-deposition pattern formation

AssigneeImra America, Inc.

InventorsBing Liu, Zhendong Hu, Makoto Murakami, Jingzhou Xu, Yong Che

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Abstract

A method of forming patterns on transparent substrates using a pulsed laser is disclosed. Various embodiments include an ultrashort pulsed laser, a substrate that is transparent to the laser wavelength, and a target plate. The laser beam is guided through the transparent substrate and focused on the target surface. The target material is ablated by the laser and is deposited on the opposite substrate surface. A pattern, for example a gray scale image, is formed by scanning the laser beam relative to the target. Variations of the laser beam scan speed and scan line density control the material deposition and change the optical properties of the deposited patterns, creating a visual effect of gray scale. In some embodiments patterns may be formed on a portion of a microelectronic device during a fabrication process. In some embodiments high repetition rate picoseconds and nanosecond sources are configured to produce the patterns.

Claims38

Dependent claims

A method of pulsed laser deposition to produce a pattern on a medium, said medium being substantially transparent at a wavelength of said pulsed laser, said method comprising:

generating pulsed laser beams from a pulsed laser source, wherein said pulsed laser source generates pulses at a repetition rate from about 100 kHz to 100 MHz;
directing said pulsed laser beams through said medium and focusing said pulsed laser beams onto a target during scanning of said pulsed laser beams along a path in a scan direction, said target producing ejecta in response to an interaction of said target and said pulsed laser beams at said repetition rate;
and
accumulating at least a portion of said ejecta on said medium to form material deposits on said medium, and to form a spatial pattern having varying optical density that produces a visual effect of grayscale,
wherein said interaction causes ejecta to expel sideways relative to said scan direction and to concentrate ejecta toward the periphery of the path of said pulsed beams such that the material deposits are formed with central low thickness portions bounded by immediately adjacent, thicker outer portions,
wherein said medium and said target are spaced apart by a gap within about 100 μm, or are in direct physical contact, and the thickness of said deposits is controlled with said repetition rate and a scanning speed of said pulsed laser beams.

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Dependencies are inferred from the claim text.