Process for inspecting and automatically sorting objects showing patterns with constant dimensional tolerances and apparatus for carrying out said process
First Claim
1. A process for inspecting and automatically sorting objects showing patterns provided with constant dimensional tolerances, of the type including the comparison of image Iref of a reference object with image Iexa of an object to be inspected, wherein image Iexa being able to show geometrical defects with respect to the reference object, said process characterized in that it includes the following steps:
- Step 1, processing images Iref and Iexa to provide electronic binary images IREF and IEXA, respectively,Step 2, defining a structuring element B for each image point of the said electronic binary image and adapted to the dimensional tolerances of the said object to be inspected and the construction of the electronic images IREF max and IREF min which consist in image IREF expanded and eroded respectively by structuring element B,Step 3, forming the images of the "spreading" or "lack" type defects by respectively carrying out the following logic operations;
space="preserve" listing-type="equation">[I.sub.REF max OR I.sub.EXA ] EXC. OR I.sub.REF max and
space="preserve" listing-type="equation">[I.sub.REF min OR I.sub.EXA ] EXC. OR I.sub.EXA andStep 4, analyzing the defects with respect to a reject criterion which defines a maximum allowed size for the defects.
1 Assignment
0 Petitions
Accused Products
Abstract
This invention relates to a process for inspecting and sorting objects showing patterns with constant dimensional tolerances as masks, integrated circuit chips, modules currently in use in the electronic industry. The process is based on the comparison of the image of a reference object Iref with the image of an object to be inspected Iexa. Images Iref and Iexa after being picked up and sampled, are thresheld to produce binary electronic images which are cleaned, then centered to allow the comparison of resulting electronic images IREF and IEXA to be carried out. The image processing includes the following operations: First of all constructing electronic images IREF max and IREF min respectively which are images IREF expanded and eroded by a structuring element adapted to the dimensional tolerances of the object to be inspected. Then, the images of the defects of the "spreading" type and of the "lack" type are constructed by respectively carrying out the following logic operations: [IREF max OR IEXA ] EXC.OR IREF max and [IREF min OR IEXA ] EXC.OR IEXA. Then, the defect images are analyzed with respect to a predetermined reject criterion. At last, final sorting step is carried out. This invention also relates to an apparatus for carrying out said process. Said apparatus can comprise a digital computer for automatizing the various steps which are indicated above.
-
Citations
16 Claims
-
1. A process for inspecting and automatically sorting objects showing patterns provided with constant dimensional tolerances, of the type including the comparison of image Iref of a reference object with image Iexa of an object to be inspected, wherein image Iexa being able to show geometrical defects with respect to the reference object, said process characterized in that it includes the following steps:
-
Step 1, processing images Iref and Iexa to provide electronic binary images IREF and IEXA, respectively, Step 2, defining a structuring element B for each image point of the said electronic binary image and adapted to the dimensional tolerances of the said object to be inspected and the construction of the electronic images IREF max and IREF min which consist in image IREF expanded and eroded respectively by structuring element B, Step 3, forming the images of the "spreading" or "lack" type defects by respectively carrying out the following logic operations;
space="preserve" listing-type="equation">[I.sub.REF max OR I.sub.EXA ] EXC. OR I.sub.REF max and
space="preserve" listing-type="equation">[I.sub.REF min OR I.sub.EXA ] EXC. OR I.sub.EXA andStep 4, analyzing the defects with respect to a reject criterion which defines a maximum allowed size for the defects. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. Apparatus for carrying out the process for inspecting and automatically sorting objects showing patterns with constant dimensional tolerances, of the type including the comparison of image Iref of a reference object with image Iexa of an object to be inspected, wherein image Iexa being able to show geometrical defects with respect to the reference object, characterized in that it includes:
-
means for processing images Iref and Iexa to provide electronic binary images IREF and IEXA, respectively, means for picking up at least image Iexa of the object to be inspected, means for constructing binary electronic images IREF and IEXA, processing means including means for constructing electronic images IREF max and IREF min, respectively, which are the images of IREF expanded and eroded respectively by a previously determined structuring element B and directly linked to the dimensional tolerances of said patterns, compare means for constructing the images of the "lack" and "spreading" type defects by performing the following logic operations;
space="preserve" listing-type="equation">[I.sub.REF max OR I.sub.EXA ] EXCL. OR I.sub.REF max and [I.sub.REF min OR I.sub.EXA ] EXCL. OR I.sub.EXA,and means for analyzing defects with repect to predetermined reject criteria and means for sorting and selecting the objects which are accepted. - View Dependent Claims (11, 12, 13, 14, 15, 16)
-
Specification