Feasibility study on the concept of thermal contact sensor for nanometre-level defect inspections on smooth surfaces

Yuki Shimizu, Wenjian Lu, Yuta Ohba, I Ko

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

This paper presents a feasibility study on the concept of a thermal contact sensor that detects nanometre-scale defects on smoothly finished surfaces such as bare silicon wafers, magnetic disks and so on. The contact sensor has a thermal element, which is composed of thin-film structures with a thermally sensitive area of several tens of μm2 on its tip surface. In the proposed concept, the thermal element detects the existence of asperity-type defects on smooth surfaces by capturing frictional heats due to slight contacts between the thermal element surface and defects. During the defect detection, a gap between the thermal element surface and the smooth surface being rotated by a precision spindle would be maintained. By monitoring deviation of the electrical resistance of the thermal element while scanning the contact sensor across the rotating surface, defects on the target surface can be detected. In this paper, a fabrication process for the thermal element has been designed based on the photolithography process, and the first prototype of the thermal element has been fabricated. Results of laser exposure tests have revealed that the fabricated thermal element can detect a rate of heat supply of 10μW, which is the same order as the rate of heat supply assumed to be generated at defect detection by the contact sensor. In addition, results of contact detection tests have confirmed the feasibility of the fabricated thermal element as a contact detection sensor.

Original languageEnglish
Article number064006
JournalMeasurement Science and Technology
Volume25
Issue number6
DOIs
Publication statusPublished - 2014 Jan 1

Keywords

  • contact sensor
  • defect inspection
  • frictional heat
  • photolithography

ASJC Scopus subject areas

  • Instrumentation
  • Engineering (miscellaneous)
  • Applied Mathematics

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