METHOD FOR DETERMINING ABNORMAL CHARACTERISTICS IN INTEGRATED CIRCUIT MANUFACTURING PROCESS
A method for determining abnormal characteristics in integrated circuit manufacturing process is disclosed. The method comprises obtaining a charged particle microscope image of a sample test structure, wherein the sample including a reference pattern and a test pattern; measuring gray levels of the reference pattern and the test pattern; calculating a standard deviation from a distribution of the gray levels of the reference pattern measured; and determining the abnormal characteristics of the test pattern based on the gray levels measured and the standard deviation.
1 . A method for determining abnormal characteristics in integrated circuit manufacturing process, comprising:
obtaining a charged particle microscope image of a sample, wherein said sample including a reference pattern and a test pattern;
measuring gray levels of said reference pattern and said test pattern;
calculating a standard deviation from a distribution of said gray levels of said reference pattern measured; and
determining the abnormal characteristics of said test pattern based on said gray levels measured and said standard deviation.
2 . The method for determining abnormal characteristics of claim 1 , wherein said gray levels are measured by using a charged particle beam.
3 . The method for determining abnormal characteristics of claim 2 , wherein said charged particle beam comprises an e-beam.
4 . The method for determining abnormal characteristics of claim 1 , wherein said abnormal characteristics indicate the level of leakage to the ground of said test pattern.
5 . The method for determining abnormal characteristics of claim 1 , wherein said determining the abnormal characteristics step comprising:
calculating an average gray level from said gray levels of said reference pattern measured;
calculating a factor based on said average gray level, said gray level of said test pattern and said standard deviation;
predetermining at least one characteristic value; and
comparing said factor to said characteristic value.
6 . The method for determining abnormal characteristics of claim 5 , wherein said factor is calculated by taking the difference of said average gray level and said gray level of said test patterns then divide the difference by said standard deviation.
7 . The method for determining abnormal characteristics of claim 5 , wherein said characteristic value is predetermined by an electrical test that using probes with different voltages to contact different parts of the sample and measure the leakage current.
8 . The method for determining abnormal characteristics of claim 1 , wherein the reference pattern comprises at least one integrated circuit device having source/drain-to-substrate short.
9 . The method for determining abnormal characteristics of claim 1 , wherein the reference pattern comprises at least one integrated circuit device having source/drain-to-well short.
10 . The method for determining abnormal characteristics of claim 1 , wherein the test pattern comprises at least one integrated circuit device to be tested.
11 . The method for determining abnormal characteristics of claim 10 , wherein said at least one integrated circuit device comprises a bright voltage contrast defect.
12 . The method for determining abnormal characteristics of claim 1 , wherein said charged particle microscope image is obtained after a silicide formation.
13 . The method for determining abnormal characteristics of claim 1 , wherein said charged particle microscope image is obtained after tungsten chemical mechanical polishing.
14 . The method for determining abnormal characteristics of claim 1 , wherein said sample comprises a static random access memory array.
15 . The method for determining abnormal characteristics of claim 14 , wherein said reference pattern comprises P+/N well.
16 . The method for determining abnormal characteristics of claim 14 , wherein said test pattern comprises N+/P well.
17 . The method for determining abnormal characteristics of claim 14 , wherein said test pattern comprises a gate at tungsten chemical mechanical polish layer.
18 . A computer readable medium encoded with a computer program for determining abnormal characteristics in integrated circuit manufacturing process, comprising:
obtaining a charged particle microscope image of a sample, wherein said sample including a reference pattern and a test pattern;
measuring gray levels of said reference pattern and said test pattern;
calculating a standard deviation from a distribution of said gray levels of said reference pattern measured; and
determining the abnormal characteristics of said test pattern based on said gray levels measured and said standard deviation.
19 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein said gray levels are measured by using a charged particle beam.
20 . The computer readable medium for determining abnormal characteristics of claim 19 , wherein said charged particle beam comprises an e-beam.
21 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein said abnormal characteristics indicate the level of leakage to the ground of said test pattern.
22 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein said determining the abnormal characteristics step comprising:
calculating an average gray level from said gray levels of said reference pattern measured;
calculating a factor based on said average gray level, said gray level of said test pattern and said standard deviation;
predetermining at least one characteristic value; and
comparing said factor to said characteristic value.
23 . The computer readable medium for determining abnormal characteristics of claim 22 , wherein said factor is calculated by taking the difference of said average gray level and said gray level of said test pattern then divide the difference by said standard deviation.
24 . The computer readable medium for determining abnormal characteristics of claim 22 , wherein said characteristic value is predetermined by an electrical test that using probes with different voltages to contact different parts of the sample and measure the leakage current.
25 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein the reference pattern comprises at least one integrated circuit device having source/drain-to-substrate short.
26 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein the reference pattern comprises at least one integrated circuit device having source/drain-to-well short.
27 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein the test pattern comprises at least one integrated circuit device to be tested.
28 . The computer readable medium for determining abnormal characteristics of claim 27 , wherein said at least one integrated circuit device comprises a bright voltage contrast defect.
29 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein said charged particle microscope image is obtained after a silicide formation.
30 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein said charged particle microscope image is obtained after tungsten chemical mechanical polishing.
31 . The computer readable medium for determining abnormal characteristics of claim 18 , wherein said sample comprises a static random access memory array.
32 . The computer readable medium for determining abnormal characteristics of claim 31 , wherein said reference pattern comprises P+/N well.
33 . The computer readable medium for determining abnormal characteristics of claim 31 , wherein said test pattern comprises N+/P well.
34 . The computer readable medium for determining abnormal characteristics of claim 31 , wherein said test pattern comprises a gate at tungsten chemical mechanical polish layer.