Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Patent
1989-03-13
1990-08-14
Karlsen, Ernest F.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
324158D, 324642, G01R 3126, G01R 2706
Patent
active
049490346
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.
REFERENCES:
patent: 3939415 (1976-02-01), Terasawa
Imura Makoto
Usami Akira
Japan Silicon Co., Ltd.
Karlsen Ernest F.
Mitsubishi Kinzoku Kabushiki Kaisha
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