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:
Aug. 14, 1990
Filed:
Mar. 13, 1989
Makoto Imura, Noda, JP;
Akira Usami, Aichi, JP;
Mitsubishi Kinzoku Kabushiki Kaisha, Tokyo, JP;
Japan Silicon Co., Ltd., Tokyo, JP;
Abstract
This invention discloses a method for contactless evaluation of characteristics of semiconductor wafers and devices. The method includes the steps of (a) continuously irradiating focused microwaves on a surface of a semiconductor specimen; (b) continuously receiving reflected microwaves reflected from said surface; (c) irradiating a focused laser beam pulse on the specimen, energy of the pulse being in excess of the band-gap energy of the semiconductor material; (d) measuring lifetime .tau..sub.m from the time-history of the characteristics of the reflected microwaves; and (e) calculating the surface recombination velocity S and bulk lifetime .tau..sub.b. The focused microwaves and focused laser beam can improve the resolution during measurement. Furthermore, the method includes the steps of: (a) continuously irradiating microwaves on a surface of a semiconductor specimen; (b) continuously receiving reflected microwaves reflected from said surface; (c) irradiating a laser beam pulse on the specimen, energy of the pulse being in excess of the band-gap energy of the semiconductor material; and (d) changing the characteristic of the reflected microwaves to an electrical signal, for obtaining the intensity of the reflected microwaves at a predetermined moment, repeating those steps at a plurality of points on the surface, thereby obtaining electrical signals at the points according to surface recombination velocities S at the points, so that the surface condition of the specimen can be evaluated.