Patent · US Expired

Method and controlling system for preventing the scratching of wafer backs by the fetch arm of a stepper machine

US6097992A · kind A · utility

0Cited by
10References
10Claims
0Family size

Assignee

Inventors

Key dates

Filing dateDec 16, 1997
Grant dateAug 1, 2000
Priority date—
Expiry dateDec 16, 2017

Classification

  • Technology area (CPC H)Electricity
  • CPC primaryH01L21/6838
  • WIPO fieldSemiconductors
  • WIPO sectorElectrical engineering

Abstract

A method for avoiding scratching of wafer backs being held by a vacuum to a fetch arm of a stepper machine for insertion into a cassette holder includes releasing the vacuum in the suction head of the fetch are before the wafer enters the cassette holder. The release of vacuum reduces frictional force between the wafer back and the suction head when the wafer accidentally hits the side of the cassette holder. Therefore, the vacuum release method avoids scratching of wafer backs by the suction head of the fetch arm. The invention requires a separate vacuum release controller to release the vacuum in the suction head for a prescribed delaying period after the fetch arm starts moving toward the cassette holder.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.