The present invention relates to electrical circuit inspection and more particularly to automatic optical electrical circuit inspection apparatus and methods.
There exist in the art a variety of automatic optical electric circuit inspection systems, including inter alia, systems described in whole or in part by U.S. Pat. Nos. 5,774,573; 5,774,572; 5,699,447; 5,619,588; 5,495,535; 5,369,431; 5,216,479; 5,153,668; 5,058,982; 5,008,743 and 4,758,888 of the present assignee.
There is also known a family of inspection devices, known collectively as the AIM 2000 family of Products, which are commercially available from AEI of San Diego, Calif. 92121.
The present invention seeks to provide an improved inspection system.
There is thus provided in accordance with a preferred embodiment of the present invention apparatus for post etching inspection of electrical circuits including:
an optical inspection assembly viewing an electrical circuit at various regions thereon and providing output indications of etching characteristics of the electrical circuit at the various regions; and
output circuitry receiving the output indications of etching characteristics of the electrical circuit at the various regions and providing an output indication of variations in the etching characteristics between at least some of the various regions.
Preferably, the output circuitry includes at least one and most preferably all of the following elements:
a line segment identifier receiving an output from the inspection assembly and identifying conductor portions having a uniform width over at least a minimum length;
an indication point generator, which defines at least one point location which represents at least one of the location and length of a line segment having a uniform width over at least a selected minimum length;
a line width measurer, which measures the line width of each line segment having a uniform width over at least a selected minimum length;
a report generator which indicates the line width of each line segment having a uniform width over at least a selected minimum length in a graphical manner; and
a report generator which indicates a statistical distribution of the line widths of line segments each having a uniform width over at least a selected minimum length in a graphical manner.
There is also provided in accordance with a preferred embodiment of the present invention a method for post etching inspection of electrical circuits including the steps of:
viewing an electrical circuit at various regions thereon and providing output indications of etching characteristics of the electrical circuit at the various regions; and
receiving the output indications of etching characteristics of the electrical circuit at the various regions and providing an output indication of variations in the etching characteristics between at least some of the various regions.
Preferably, the step of providing an output indication includes at least one and most preferably all of the following elements:
line segment identification including receiving an output from the inspection assembly and identifying conductor portions having a uniform width over at least a minimum length;
indication point generation, which defines at least one point location which represents at least one of the location and length of a line segment having a uniform width over at least a selected minimum length;
line width measurement, which measures the line width of each line segment having a uniform width over at least a selected minimum length;
report generation which indicates the line width of each line segment having a uniform width over at least a selected minimum length in a graphical manner; and
report generation which indicates a statistical distribution of the line widths of line segments each having a uniform width over at least a selected minimum length in a graphical manner.
Preferably the statistical distribution has sub-pixel accuracy.