VV6501
Defect Categorisation
8.6 Physical aberrations
Silicon surface irregularities and external marks, both pits and deposits, on the package glass lids
can cause a deterioration in image quality. STMicroelectronics recognize that this could
compromise the product quality and therefore have introduced a specific test algorithm to identify
and reject samples that display these phenomena. The pass/fail criteria for this test are given in
Section 8.6.1.
8.6.1 Test details
Figure 35: Test area definition
The test defines 2 areas:
q A small area: 9 by 9 pixels with pixel under test at the centre of this area (shaded blue in
Figure 35)
q A large region, 31 by 31 pixels (shaded red in Figure 35)
An average value is calculated for both the ‘small’ and ‘large’ areas.The areas then scan across the
whole array so that every pixel is evaluated. Due to the nature of the test, only the red pixels are
used. The next stage of the test is the creation of a pixel map with the coordinates of the failing
pixels. A pixel location is identified as a fail in the map if it satisfies the criteria outlined in Table 26
below.
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