ANOMALY DETECTION METHOD, COMPUTER-READABLE NON-TRANSITORY STORAGE MEDIUM, AND ANOMALY DETECTION APPARATUS
In accordance with an embodiment, an anomaly detection method includes acquiring coordinate data of defects or particles generated on a wafer during a semiconductor manufacturing process, calculating an Eberhardt's index from the acquired data, calculating a first probability point, comparing the calculated Eberhardt's index with the first probability point, and judging presence/absence in state of a spatial point distribution relative to the defects or the particles. The first probability point is calculated based on a sample distribution of the Eberhardt's index.
1 . An anomaly detection method comprising:
acquiring coordinate data of defects or particles generated on a wafer during a semiconductor manufacturing process;
calculating an Eberhardt's index from the acquired data;
calculating a first probability point based on a sample distribution of the Eberhardt's index; and
comparing the calculated Eberhardt's index with the first probability point, and judging presence/absence in state of a spatial point distribution relative to the defects or the particles.
2 . The method of claim 1 ,
wherein a sample distribution of the Eberhardt's index is a sample distribution relative to a spatial point distribution according to a binomial distribution or a Poisson distribution.
3 . The method of claim 1 ,
wherein comparing the calculated Eberhardt's index with the first probability point comprises
comparing the calculated Eberhardt's index with a first Eberhardt's index control reference value.
4 . The method of claim 3 ,
wherein, when the calculated Eberhardt's index substantially coincides with the first Eberhardt's index control reference value, the spatial distribution is determined as a random spatial distribution.
5 . The method of claim 3 ,
wherein, when the calculated Eberhardt's index is significantly larger than the first Eberhardt's index control reference value, the spatial distribution is determined to be aggregative.
6 . The method of claim 5 , further comprising paying attention to presence of a cluster and examining characteristics of a spatial point distribution (Spatial Signature) of a wafer map.
7 . The method of claim 3 ,
wherein, when the calculated Eberhardt's index is significantly smaller than the first Eberhardt's index control reference value, the spatial distribution is determined to be regular.
8 . The method of claim 7 , further comprising examining presence/absence of a common defect.
9 . The method of claim 1 ,
wherein the acquired coordinate data is converted into a polar coordinate having the center of the wafer as an origin and acquired, and
the Eberhardt's index is an Eberhardt's index relative to a one-dimensional coordinate calculated based on projection of the polar coordinate onto a radius vector and an azimuthal component.
10 . The method of claim 2 , further comprising:
converting the acquired coordinate of the defect or the particle into a polar coordinate having the center of the wafer as an origin;
calculating a one-dimensional coordinate based on projection of the polar coordinate onto a radius vector and an azimuthal component;
calculating an Eberhardt's index relative to the one-dimensional coordinate; and
comparing an Eberhardt's index relative to the calculated primary coordinate with a second probability point calculated from an index distribution.
11 . The method of claim 10 ,
wherein comparing the Eberhardt's index relative to the calculated one-dimensional coordinate with the second probability point comprises comparing the Eberhardt's index relative to the calculated one-dimensional coordinate with a second Eberhardt's index control reference value.
12 . The method of claim 11 ,
wherein, when the calculated Eberhardt's index substantially coincides with the second Eberhardt's index control reference value, the spatial distribution is determined as a random spatial distribution.
13 . The method of claim 11 ,
wherein, when the calculated Eberhardt's index is significantly larger than the second Eberhardt's index control reference value, the spatial distribution is determined to be aggregative.
14 . The method of claim 11 ,
wherein, when the calculated Eberhardt's index is significantly smaller than the second Eberhardt's index control reference value, the spatial distribution is determined to be regular.
15 . The method of claim 1 , further comprising:
counting the number of the defects or the particles; and
comparing a result of counting with a predetermined quantity control limit value,
wherein the calculated Eberhardt's index is compared with the first probability point when the result of counting exceeds the quantity control limit value, and
the Eberhardt's index is subjected to tendency analysis when the result of counting exceeds the quantity control limit value.
16 . A non-transitory computer-readable recording medium containing a program which causes a computer to execute an anomaly detection, the anomaly detection comprising:
acquiring coordinate data of defects or particles generated on a wafer during a semiconductor manufacturing process;
calculating an Eberhardt's index from the acquired data;
calculating a first probability point based on a sample distribution of the Eberhardt's index; and
comparing the calculated Eberhardt's index with the first probability point, and judging presence/absence in state of a spatial point distribution relative to the defects or the particles.
17 . The medium of claim 16 ,
wherein a sample distribution of the Eberhardt's index is a sample distribution relative to a spatial point distribution according to a binomial distribution or a Poisson distribution.
18 . The medium of claim 16 ,
wherein the acquired coordinate data is converted into a polar coordinate having the center of the wafer as an origin and acquired, and
the Eberhardt's index is an Eberhardt's index relative to a one-dimensional coordinate calculated based on projection of the polar coordinate onto a radius vector and an azimuthal component.
19 . An anomaly detection apparatus comprising:
an arithmetic unit configured to calculate an Eberhardt's index from coordinate data of a defect or a particle generated on a wafer in manufacturing a semiconductor;
a storage unit configured to store a probability point based on a sample distribution of a previously calculated or determined Eberhardt's index; and
a first comparison unit configured to compare the calculated Eberhardt's index with the probability point.
20 . The apparatus of claim 19 ,
wherein the storage unit further stores a quantity control limit value of the defects or the particles, and
the apparatus further comprises:
a counting unit configured to count the number of the defects or the particles; and
a second comparison unit configured to compare the counted number with the quantity control limit value.