Patent ID: 6559412
Filing Date: 2003-05-06
Classification: B23K,H01L

Abstract:
A method of vaporizing a target structure on a silicon substrate, comprising the steps of:calculating, as a function of wavelength, an incident beam energy necessary to deposit unit energy in the target structure sufficient to vaporize the target structure; calculating, for the incident beam energy, energy expected to be deposited in the silicon substrate as a function of wavelength; identifying a wavelength below an absorption edge of the silicon substrate, the wavelength corresponding to a relatively low value of the energy expected to be deposited in the silicon substrate, the low value being substantially less than a value of the energy expected to be deposited in the silicon substrate at a higher wavelength below the absorption edge of the silicon substrate; providing a laser system configured to produce a laser output at the wavelength corresponding to the relatively low value of the energy expected to be deposited in the silicon substrate; and directing the laser output at the target structure on the silicon substrate at the wavelength corresponding to the relatively low value of the energy expected to be deposited in the silicon substrate and at the incident beam energy, in order to vaporize the target structure, the silicon substrate being positioned beneath the target structure with respect to the laser output; wherein the incident beam energy at which the target structure is vaporized is reduced relative to an incident beam energy necessary to deposit unit energy in the target structure sufficient to vaporize the target structure at the higher wavelength.