Method and apparatus for inspecting an object using terahertz electromagnetic wave

• US 7,557,588 B2
• Filed: 03/27/2007
• Issued: 07/07/2009
• Est. Priority Date: 04/28/2006
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ouchi, Toshihiko, Kasai, Shintaro
• Primary Examiner(s): Nguyen; Vincent Q
• Assistant Examiner(s): NATALINI, JEFF WILLIAM
• Application Number:
  US11/727,588
• Publication Number:
  US 20070252604A1
• Time in Patent Office: 833 Days
• Field of Search: 324/637
• US Class Current: 324/637
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation

Abstract

An inspection apparatus including a transmission line for propagating an electromagnetic wave; an electromagnetic wave supply unit for supplying a terahertz wave to the transmission line; an electromagnetic wave detection unit for detecting the terahertz wave from the transmission line; a conductive region; an inspection object supply unit; and a deposition unit. The conductive region is arranged at a site including at least a part of the range to which an electric field distribution of the electromagnetic wave propagating through the transmission line extends. The inspection object supply unit holds and supplies the inspection object to the outside, and the deposition unit deposits the inspection object selectively on the conductive region by electrostatic force. The electromagnetic wave supplied from the electromagnetic wave supply unit and propagated through the transmission line is detected by the electromagnetic wave detection unit to obtain information on the inspection object.

Claims

1. An inspection method of detecting an electromagnetic wave in a frequency range between 30 GHz and 30 THz which is propagated through a transmission line to obtain information on an inspection object deposited on a conductive region located in a site including at least a part of a range to which an electric field distribution of the electromagnetic wave propagating through the transmission line extends, comprising:

supplying the inspection object from an inspection object supply unit for holding and supplying the inspection object to an outside;

applying a voltage between the conductive region and an inspection object holding portion of the inspection object supply unit to generate an electric field;

guiding the supplied inspection object with an electrostatic force to deposit the object depositing selectively on the conductive region; and

obtaining information on the inspection object by superimposing an alternating current component on the voltage to be applied to the inspection object holding portion of the inspection object supply unit to vary a rate of the deposition of the inspection object onto the conductive region, and carrying out a synchronous detection with this variation.

2. An inspection method according to claim 1, wherein information on the inspection object is obtained by obtaining a plurality of changes of a signal of the detected electromagnetic wave continuously or intermittently for an elapse of time, correspondingly to a temporal change of a deposition amount of the inspection object onto the conductive region.

3. An inspection method according to claim 2, further comprising stopping supply of the inspection object when a rate of the change of the signal of the detected electromagnetic wave becomes small with respect to the elapse of time or when the rate of the change is estimated to be small.