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Laser-Induced Dry Plasma Etching

IP.com Disclosure Number: IPCOM000039329D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Coufal, H: AUTHOR [+3]

Abstract

Etching and micromachining of materials by means of an intense laser beam is improved if the process is carried out in a reactive gas atmosphere under the influence of an electric field which returns the reactive gas ions to the sample surface for ion and impact etching. In the figure, the sample to be etched, preferably a dielectric, is embedded between a conductive mask 2 and a counterelectrode 3 which are connected to a voltage source U0 to generate an electric field, e.g., in craters 4 formed under openings of mask 2. Mask 2 is homogeneously or selectively irradiated by a pulsed laser beam 5 with intensities of the order of 100 MW/cm2 which are sufficient to vaporize a surface layer of dielectric 1 and to heat the vaporized material into a plasma 6 having a high escape speed (plasma jet).

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Laser-Induced Dry Plasma Etching

Etching and micromachining of materials by means of an intense laser beam is improved if the process is carried out in a reactive gas atmosphere under the influence of an electric field which returns the reactive gas ions to the sample surface for ion and impact etching. In the figure, the sample to be etched, preferably a dielectric, is embedded between a conductive mask 2 and a counterelectrode 3 which are connected to a voltage source U0 to generate an electric field, e.g., in craters 4 formed under openings of mask 2. Mask 2 is homogeneously or selectively irradiated by a pulsed laser beam 5 with intensities of the order of <N> 100 MW/cm2 which are sufficient to vaporize a surface layer of dielectric 1 and to heat the vaporized material into a plasma 6 having a high escape speed (plasma jet). In the presence of a reactive gas, e.g., a mixture of oxygen and helium in the 50 Torr range, the plasma jet is slowed down, generating oxygen ions which are then redirected under the influence of the electric field to dielectric 1 for increased etching. Particulars of the etch process are determined by the nature and the pressure of the reaction gas and by the electric field applied; a suitable choice of these parameters yields craters 4 with vertical or even undercut walls, e.g., in dielectric substrates with a maximum thickness in the mm range.

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