The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 13, 2001
Filed:
May. 15, 1997
Winfried Denk, Berkeley Heights, NJ (US);
Chunhui Xu, Berkeley Heights, NJ (US);
Lucent Technologies Inc., Murray Hill, NJ (US);
Abstract
Semiconductor devices are imaged using two-photon absorption. The method is similar to conventional optical beam induced imaging except that the light beams used have frequencies (photon energies) insufficient to excite electrons across the semiconductor bandgap. Rather the instantaneous intensity of the lower frequency light is increased, as by using a pulsed laser source, so that electron transitions occur by two-photon absorption predominately in the localized region where the beam is focused. The result is minimal absorption during passage through the substrate and maximal absorption in the component-rich active layer where the beam is focused. This enhances imaging of fine-detail semiconductor devices. Specifically, the quadratic dependence of free carrier generation on the excitation intensity both enhances the resolution and provides a three-dimensional sectioning capability.