Inspection system
Provided is an inspection system capable of estimating electric characteristics of a sample with high accuracy regardless of an initial charging state of a wafer. The inspection system includes a charged particle beam device and a computer system, and inspects the electric characteristics of the sample. The inspection system evaluates initial charging of an inspection region including inspection patterns based on reference data indicating a secondary charged particle signal from a reference pattern corresponding to a plurality of pulse conditions. The reference pattern has the same electric characteristics as the inspection pattern and initial charging therein caused by electric charges that are not emitted according to a discharge time constant of the sample is negligible. The reference pattern is obtained by irradiating the reference pattern with a pulse charged particle beam under a plurality of pulse conditions.
1 . An inspection system for inspecting electric characteristics of a sample, the inspection system comprising: a charged particle beam device and a computer system, wherein
a plurality of inspection regions are set in the sample, and respective inspection points are set for a plurality of specific inspection patterns included in the inspection region,
the charged particle beam device includes
a charged particle optical system configured to irradiate the sample with a pulse charged particle beam,
a detection system configured to detect secondary charged particles emitted when the sample is irradiated with the pulse charged particle beam, and output a secondary charged particle signal corresponding to an amount of detected secondary charged particles, and
a control unit configured to control the charged particle optical system to irradiate the sample with the pulse charged particle beam under a plurality of pulse conditions,
the computer system is configured to
obtain determination data indicating a secondary charged particle signal from the inspection pattern included in the inspection region corresponding to the plurality of pulse conditions based on measurement data indicating a secondary charged particle signal from the inspection pattern corresponding to the plurality of pulse conditions, the measurement data being obtained by irradiating the inspection pattern with the pulse charged particle beam under the plurality of pulse conditions for each of the plurality of inspection points included in the inspection region, and
instruct the control unit to execute a static elimination sequence for eliminating charging of the inspection region when an error between the determination data and reference data is equal to or greater than a predetermined threshold, the reference data being data indicating the secondary charged particle signal from a reference pattern corresponding to the plurality of pulse conditions, the reference data being obtained by irradiating the reference pattern with the pulse charged particle beam under the plurality of pulse conditions, and
the reference pattern is a pattern that has the same electric characteristics as the inspection pattern and in which initial charging caused by electric charges that are not emitted according to a discharge time constant of the sample is negligible.
2 . The inspection system according to claim 1 , wherein
the plurality of pulse conditions are conditions in which cut-off times during which the charged particle optical system does not irradiate the sample with the pulse charged particle beam are different, or conditions in which charging times from when the charged particle optical system irradiates the sample with the pulse charged particle beam to a sampling timing of the detection system are different.
3 . The inspection system according to claim 1 , wherein
the charged particle beam device further includes an optical system configured to irradiate the sample with light, and
the control unit of the charged particle beam device is configured to receive, from the computer system, an instruction to execute the static elimination sequence, and control the optical system to irradiate a light irradiation region in the inspection region with the light under a predetermined light irradiation condition.
4 . The inspection system according to claim 3 , wherein
the light irradiation region includes at least one of the inspection pattern and a related pattern related to the inspection pattern.
5 . The inspection system according to claim 1 , wherein
the control unit of the charged particle beam device is configured to receive, from the computer system, an instruction to execute the static elimination sequence, and control the charged particle optical system so as to scan a charging control region in the inspection region with a charged particle beam under a predetermined charged particle beam irradiation condition, and
the charging control region includes the inspection region.
6 . The inspection system according to claim 1 , wherein
the computer system is configured to output an inspection result of the inspection region as an error when the error between the determination data and the reference data is equal to or greater than the predetermined threshold even when the static elimination sequence is executed a predetermined number of times.
7 . The inspection system according to claim 1 , wherein
the computer system is configured to estimate the electric characteristics of the inspection patterns at the inspection points as an inspection result of the inspection region based on the measurement data for each of the inspection points when the error between the determination data and the reference data is less than the predetermined threshold.
8 . The inspection system according to claim 7 , wherein
the computer system is configured to output the inspection result of the inspection region including the error between the determination data and the reference data when the measurement data used for estimating the electric characteristics of the inspection pattern at the inspection point is acquired.
9 . The inspection system according to claim 1 , wherein
the computer system is configured to calculate the determination data as an average value of the measurement data for each of the inspection points in the inspection region.