Noncontact measuring system for electrical conductivity

• US 20040100280A1
• Filed: 05/20/2003
• Published: 05/27/2004
• Est. Priority Date: 11/27/2002
• Status: Active Grant

• Current Assignee: Tohoku Techno Arch Co., Ltd.
• Original Assignee: Tohoku Techno Arch Co., Ltd.
• Inventors: Abe, Hiroyuki, Ju, Yang, Saka, Masumi
• Granted Patent: US 6,879,167 B2
• Time in Patent Office: Days
• US Class Current: 324/642
• CPC Class Codes: G01N 22/02 Investigating the presence of flaws
• CPC Class Codes: G01R 27/06 Measuring reflection coefficients; Measuring standing-wave ratio
• CPC Class Codes: G01R 27/2658 Cavities, resonators, free space arrangements, reflexion or interference arrangements G01R27/2647 takes precedence; optical methods G01R27/2682
• CPC Class Codes: G01R 31/311 of integrated circuits G01R31/31728 takes precedence

Abstract

The invention provides a noncontact measuring system for electrical conductivity, which uses a microwave. In the measuring system for electrical conductivity, the microwave generated in a network analyzer (NA) 110 is guided to a surface of a silicon wafer (sample) 160 through a waveguide 130 and a sensor 140. The surface of the silicon wafer 160 is irradiated with the microwave, and the sensor 140 receives the reflected microwave. The electrical conductivity of the silicon wafer 160 is measured in such a manner that a computer (personal computer) 120 calculates the electrical conductivity from an amplitude ratio A and phase difference θ to a reflected wave of the silicon wafer 160, which is determined with the network analyzer 110. The computer 120 performs not only the calculation of the measurement but also whole control of the measuring system such as positioning of the sample.

Claims

1. A noncontact measuring system for electrical conductivity comprising:

microwave transmitting and receiving means which transmits and receives the microwave;

measuring means which measures an amplitude ratio of the transmitted microwave and a received-reflected wave; and

electrical conductivity calculating means which determines the electrical conductivity of a low frequency from the measured amplitude ratio.

2. A noncontact measuring system for electrical conductivity comprising:

microwave transmitting and receiving means which transmits and receives the microwave;

measuring means which measures an amplitude ratio and phase difference of the transmitted microwave and a received-reflected wave;

electrical conductivity calculating means which determines the apparent electrical conductivity from the measured amplitude ratio and phase difference; and

electrical conductivity calibration means which determines the electrical conductivity of a low frequency from the determined apparent electrical conductivity.