US 4,357,540 AGranted

Semiconductor device array mask inspection method and apparatus

AssigneeInternational Business Machines Corporation

InventorsCharles E. Benjamin, David J. Crawford

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Abstract

This describes an automatic beam alignment and defect inspection system for masks. The system causes each field or sub-field to be individually aligned for inspection irrespective of the previous alignment of the mask or any other field or sub-field. This is accomplished by scanning a preselected portion of each field of sub-field, with a beam and adjusting the position of the deflection based on the reflected signal while scanning a pre-established portion of the selected field or sub-field. In this way a portion of each selected field or sub-field is used as an alignment mark and stepping errors avoided. Once alignment is achieved a beam spot, comparable to the size of the minimum defect to be detected is scanned over the selected field or sub-field with an overlapping scan to find defects such as mask material in improper places or points where the mask material is missing.

Claims10

Dependent claims

A method of inspecting a patterned mask comprising the steps of:

placing a patterned mask to be inspected in an inspection apparatus,
said mask being provided with a multiplicity of patterns on a surface thereon,
directing a beam to scan a first selected region overlying a portion of a selected first pattern on said mask,
measuring the information received from said first region,
comparing the measured information against the information used to create said mask and using the compared information to align said mask to a first predetermined position,
directing the beam to scan the entire selected pattern,
measuring the information received from said entire first selected pattern,
comparing said received information to the information used to create said mask to detect errors in said selected pattern,
moving said mask to a different position,
directing the beam to scan a second selected region overlying a portion of a selected second pattern on said mask,
comparing the measured information against the information used to create said mask and using the compared information to align said mask to a second predetermined position,
directing the beam to scan the entire second selected pattern,
measuring the information received from said entire second selected pattern, and
comparing said received information from said second pattern to the information used to create said mask to detect errors in said second selected pattern.

11 more elements

Dependencies are inferred from the claim text.