Yield based, in-line defect sampling method
First Claim
1. A method for processing semiconductor dice on a wafer comprising:
- determining defects on the semiconductor dice on the wafer;
classifying each of the defects by size and location, determining and classifying comprising classifying each of the defects into one of size range populations of defects;
assigning a weight to each of the defects representing an estimated effect of each defect on die yield for the semiconductor dice;
determining an estimated die yield loss (DYL) for each semiconductor die of the semiconductor dice based on number and weight of the defect(s) on each semiconductor die of the semiconductor dice, determining the estimated DYL including calculating an estimated die yield loss having lower and upper limits;
summing all of the DYL of the semiconductor dice on the wafer to obtain a wafer yield loss (WYL);
subdividing the defects into a plurality of size range populations of defects for the semiconductor dice; and
determining a relative contribution of each size range population of defects of the plurality of the semiconductor dice to the wafer yield loss WYL.
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Abstract
A test method provides a sample of wafer level defects most likely to cause yield loss on a semiconductor wafer subdivided into a plurality of integrated circuits (ICs). Defect size and location data from an inspection tool is manipulated in an algorithm based on defect sizes and geometry parameters. The defects are classified by defect size to form size based populations. The contribution of each size range of defect population to yield loss is calculated and random samples for review are selected from each defect size population. The number of samples from each size defect population is proportional to the predicted yield impact of each sample. The method is rapid and permits on-line process modification to reduce yield losses.
30 Citations
18 Claims
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1. A method for processing semiconductor dice on a wafer comprising:
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determining defects on the semiconductor dice on the wafer;
classifying each of the defects by size and location, determining and classifying comprising classifying each of the defects into one of size range populations of defects;
assigning a weight to each of the defects representing an estimated effect of each defect on die yield for the semiconductor dice;
determining an estimated die yield loss (DYL) for each semiconductor die of the semiconductor dice based on number and weight of the defect(s) on each semiconductor die of the semiconductor dice, determining the estimated DYL including calculating an estimated die yield loss having lower and upper limits;
summing all of the DYL of the semiconductor dice on the wafer to obtain a wafer yield loss (WYL);
subdividing the defects into a plurality of size range populations of defects for the semiconductor dice; and
determining a relative contribution of each size range population of defects of the plurality of the semiconductor dice to the wafer yield loss WYL. - View Dependent Claims (2, 3, 4)
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5. A method for semiconductor dice on a wafer comprising:
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determining defects on the semiconductor dice on the wafer;
classifying each of the defects by size and location, determining and classifying comprising classifying each of the defects into one of size range populations of defects;
assigning a weight to each of the defects representing an estimated effect of the defects on die yield for the semiconductor dice;
determining an estimated die yield loss (DYL) for each semiconductor die of the semiconductor dice based on number and weight of the defects on each semiconductor die of the semiconductor dice;
summing all DYL of the semiconductor dice on the wafer to obtain a wafer yield loss (WYL);
subdividing the defects into a plurality of size range populations of defects; and
determining a relative contribution of each size range population of defects of the plurality to the WYL, wherein determining the relative contribution of each size range population of defects of the plurality to the wafer yield loss comprises;
discarding data for each size range population of defects of the plurality and calculating, in turn, a drop in the WYL for combined size range populations excepting the discarded data;
summing the calculated WYL to obtain a drop sum;
dividing the drop sum to determine a relative drop attributable to each size range population of defects of the plurality; and
randomly selecting defects from each size range population of defects of the plurality. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A method for semiconductor dice in wafer form comprising:
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determining defects of the semiconductor dice;
classifying each of the defects by size and location;
assigning a weight to each of the defects representing an estimated effect of each defect on die yield;
determining an estimated die yield loss (DYL) for each of the semiconductor dice based on number and weight of the defects on each of the semiconductor dice;
summing all DYL of the semiconductor dice on the wafer to obtain a wafer yield loss (WYL);
subdividing the defects into a plurality of size range populations of defects;
determining a relative contribution of each size range population of defects of the plurality to the WYL;
randomly selecting defects from each size range population of defects of the plurality, a number selected from each size range population of defects of the plurality in proportion to the relative contribution thereof, the randomly selected defects weighted to represent defects having a greatest effect on yield losses; and
reviewing the randomly selected defects. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification