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:
Jan. 12, 1993
Filed:
May. 15, 1991
Lauren M Peterson, Ann Arbor, MI (US);
Environmental Research Institute of Michigan, Ann Arbor, MI (US);
Abstract
A system for detecting minute amounts of water contaminant in semi-conductor microelectronic integrated circuits (MIC) includes two lasers 11,12 producing electromagnetic radiation at two discrete wavelengths. Each laser beam being sent through a chopper 13 and 14 respectively and combined via mirror 16 and beam splitter 17 to form a single two part beam along optical axis 22. The beam passes through a reflective beam splitter 26, a quarter wave plate 28 and lens 29 to be directed to a MIC 31 that is mounted onto drive mechanisms 31 and 32. Diffuse reflections from the bottom of the MIC or specular reflections from metallization layers pass back through MIC 31, lens 29, quarter wave plate 28, beam splitter 27 and through lens 48 to detector 47 which compares the intensity of the radiation at the two wavelengths with the intensities of the wavelengths as detected by detector 21 through a lock-in amplifier 49.