Automatic inspection method
First Claim
1. A method for automatically inspecting semiconductor die comprising:
- obtaining an image of the semiconductor die;
performing a direction edge enhancement and selecting a first and a second threshold value of an edge enhanced image;
conditionally dilating the second threshold value with the first threshold value to conditionally grow prominent edge features; and
determining the semiconductor die location and rotation by correlating discrete die perimeter edge points, wherein the discrete die perimeter edge points are weighted, shifted and summed to perform the correlating.
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Abstract
A method for automatically inspecting articles or work pieces uses a solid state television camera to obtain images of the article. An edge enhancement is done to obtain a first and a second threshold level which are dilated to eliminate noise edges. An edge correlation is then performed to determine orientation of the article. Gray scale or gray level imaging of the surface of the device is then performed and compared against a known device surface in order to determine acceptability of the device under inspection. The gray scale imaging techniques used are robust gray scale image processing that are tolerant to significant variations in image luminance or image degradation and is capable of identifying and classifying image features consistently while in the presence of such luminance variations. The data is then statistically characterized and the results used for real time statistical process control of the work piece process.
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Citations
7 Claims
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1. A method for automatically inspecting semiconductor die comprising:
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obtaining an image of the semiconductor die; performing a direction edge enhancement and selecting a first and a second threshold value of an edge enhanced image; conditionally dilating the second threshold value with the first threshold value to conditionally grow prominent edge features; and determining the semiconductor die location and rotation by correlating discrete die perimeter edge points, wherein the discrete die perimeter edge points are weighted, shifted and summed to perform the correlating. - View Dependent Claims (2, 3, 4, 5)
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6. A method for automatically inspecting a semiconductor die, comprising:
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determining average gray level value for each of a plurality of regions into which a surface of the semiconductor die has been divided; subtracting the average gray level values against predetermined values for each of the plurality of regions to obtain difference values; sorting the difference values from largest to smallest value to obtain normalized values; calculating difference between a normalized center value and a smaller value to obtain a first index; calculating difference between the normalized center value and a largest value to obtain a second index; and determining acceptability of the semiconductor die from magnitude of the first and second indices. - View Dependent Claims (7)
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Specification