Pattern test apparatus

• US 4,962,541 A
• Filed: 02/10/1988
• Issued: 10/09/1990
• Est. Priority Date: 02/27/1987
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd., Hitachi Video Engineering Incorporated
• Original Assignee: Hitachi, Ltd., Hitachi Video Engineering Incorporated
• Inventors: Shinada, Satoshi, Doi, Hideaki, Hara, Yasuhiko, Sase, Akira
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): Razavi, Michael
• Application Number:
  US07/154,239
• Time in Patent Office: 972 Days
• Field of Search: 382/30, 382/34, 382/8, 382/54, 382/22, 382/51, 382/27, 358/107, 358/138, 358/284, 358/101, 358/106, 358/447
• US Class Current: 382/144
• CPC Class Codes: G01N 21/95607 using a comparative method
• CPC Class Codes: G03F 1/84 Inspecting
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/001 using an image reference approach

Abstract

Disclosed is a pattern test apparatus for detecting a fault on the basis of comparison/collation between a test reference pattern and a test target pattern, the apparatus being arranged such that a picture element area is defined by a circle with a predetermined radius on a reference matter having at test reference pattern, and when the number of the picture elements located on the reference pattern is larger than the number of the picture elements located outside the reference pattern, a part of the reference pattern corresponding to a picture element located in the center of the circle is deleted. By such an arrangement, the test reference pattern can be made analogous to the real test target pattern regardless of the shape thereof, so that misjudgment of a normal test target pattern for a fault pattern can be prevented.

Claims

1. An apparatus for testing a testing circuit pattern, comprising:

an imaging means for detecting an image signal by scanning a photo-image of the testing circuit pattern;

a binary coding circuit for converting said image signal to a binary picture element signal;

a reference binary pattern generating means for generating a reference binary pattern signal in synchronism with said scanning;

processing means, including a picture image selecting means for selecting a picture element area having a desired dimension from said reference binary pattern signal, an adding means for calculating a sum of all of binary picture element signals derived from said selected picture element area and a comparing means for comparing the sum with a predetermined reference value and giving a reference binary picture element signal obtained by the comparison to a center picture element of said picture element area so that said center picture element is reformed to be substantially analogous to the binary picture element signal of the testing circuit pattern; and

means for detecting a defect by comparing said binary picture element signal with said reference binary picture element signal for preventing misjudgment of the corner of said testing circuit pattern.

2. An apparatus according to claim 1, in which said picture element area is defined by a circle with a predetermined radius.

3. An apparatus according to claim 1, in which said reference binary pattern generating means includes a magnetic tape device carrying pattern designating data recorded thereon.

4. A method for testing a testing circuit pattern, comprising the steps of:

detecting image signals by scanning a photo-image of the testing circuit pattern;

converting said image signals to binary picture element signals;

generating reference binary pattern signals in synchronism with said scanning;

selecting from said reference binary pattern signals, a picture element area having a desired dimension;

calculating a sum of all of said binary picture element signals derived from said selected picture element area;

comparing the sum with a predetermined reference value in order to produce a reference binary picture element signal;

passing the reference binary picture element signal obtained by the comparison to a center picture element of said picture element area so that said center picture is reformed to be substantially analogous to the binary picture element signal of the testing circuit pattern; and

comparing said binary picture element signal with said reference binary picture element signal for preventing misjudgment of the corner of said testing circuit pattern.

5. A pattern test apparatus for testing circuit patterns which have a corner portion thereof rounded over several picture elements the apparatus comprising:

an imaging means for detecting image signals by scanning a photo-image of the testing circuit pattern;

a binary coding circuit for converting said image signals to binary picture element signals;

a reference binary pattern generating means for generating a reference binary pattern signal in synchronism with said scanning;

a processing means, said processing means including

picture image selecting means for selecting from said reference binary pattern signal a picture element area having a desired dimension,

adding means for calculating a sum of all of binary picture element signals derived from said selected picture element area, and

comparing means for comparing the sum with a predetermined reference value to pass a reference binary picture element signal obtained by the comparison to a center picture element of said picture element area so that said center picture element is reformed to be substantially analogous to the binary picture element signal of the testing circuit pattern; and

means for detecting a defect by comparing said binary picture element signal with said reference binary picture element signal for preventing misjudgment of the testing circuit pattern.