Sample inspection apparatus

Patent metadata

Field	Value
Publication number	US-12546805-B2
Application number	US-202118560608-A
Country	US
Kind code	B2
Filing date	May 21, 2021
Priority date	May 21, 2021
Publication date	Feb 10, 2026
Grant date	Feb 10, 2026

Abstract

Provided is a sample inspection apparatus capable of identifying a capacitive fault or a potential faulty point where an electrical tolerance is low. The sample inspection apparatus includes: a charged particle optical system configured to irradiate a sample 19 with a charged particle beam; a first probe 21 a configured to come into contact with the sample; an amplifier 23 having an input terminal to which the first probe is connected; and a phase detection unit 40 to which an output signal of the amplifier is input, in which an AC voltage is applied to the first probe, and the phase detection unit detects the output signal of the amplifier using a reference signal synchronized with the AC voltage and having the same frequency as the AC voltage.

First claim

The invention claimed is:

1 . A sample inspection apparatus comprising:
a charged particle optical system configured to irradiate a sample with a charged particle beam; a first probe configured to come into contact with the sample; an amplifier having an input terminal to which the first probe is connected; and a phase detection unit to which an output signal of the amplifier is input, wherein an AC voltage is applied to the first probe, and the phase detection unit detects the output signal of the amplifier using a reference signal synchronized with the AC voltage and having the same frequency as the AC voltage.

2 . The sample inspection apparatus according to claim 1 , further comprising:
a system control unit; a first detection system including a detector configured to detect secondary particles emitted when the sample is irradiated with the charged particle beam; a charged particle control unit configured to control the charged particle optical system; and an image processing unit configured to form an image from an output signal input from the first detection system or a second detection system including the first probe, the amplifier, and the phase detection unit, wherein the system control unit outputs a scanning signal that causes the charged particle control unit to scan the sample with the charged particle beam, and the image processing unit forms the image by calculating a gray value per pixel from a detection signal input from the first detection system or the second detection system based on a control signal input from the system control unit in synchronization with the scanning signal.

3 . The sample inspection apparatus according to claim 2 ,
wherein the phase detection unit converts the output signal of the amplifier into polar coordinates to output an amplitude signal and a phase signal, and the second detection system outputs the amplitude signal or the phase signal to the image processing unit.

4 . The sample inspection apparatus according to claim 3 ,
wherein the phase detection unit includes a first phase detector to which the output signal of the amplifier and the reference signal are input, a second phase detector to which the output signal of the amplifier and a signal obtained by phase-shifting the reference signal by 90° are input, and an arithmetic unit configured to calculate the amplitude signal and the phase signal from a first DC signal output from the first phase detector and a second DC signal output from the second phase detector.

5 . The sample inspection apparatus according to claim 2 ,
wherein the second detection system includes a frequency generator configured to generate the AC voltage, and the system control unit sets a voltage and a frequency of the AC voltage generated by the frequency generator.

6 . The sample inspection apparatus according to claim 5 ,
wherein the second detection system further includes a second probe configured to come into contact with the sample and to apply the AC voltage to the sample, the amplifier is a differential amplifier, and the first probe and the second probe are connected to input terminals of the differential amplifier, respectively.

7 . The sample inspection apparatus according to claim 6 ,
wherein the second probe is connected to the frequency generator through a phase shifter, and the system control unit controls the phase shifter such that a phase of the AC voltage applied to the second probe is the same as or opposite to a phase of the AC voltage applied to the first probe or such that the AC voltage applied to the second probe is interrupted.

8 . The sample inspection apparatus according to claim 5 ,
wherein the frequency generator generates the AC voltage as a square wave.

9 . The sample inspection apparatus according to claim 2 , further comprising a pulse generator configured to generate a frequency signal as a square wave,
wherein the charged particle control unit controls the charged particle optical system such that the charged particle beam is pulsed and emitted to the sample based on the frequency signal, and the AC voltage synchronized with the frequency signal and having the same frequency as the frequency signal is applied to the first probe, and the phase detection unit detects the output signal of the amplifier using the reference signal synchronized with the frequency signal and having the same frequency as the frequency signal.

10 . A sample inspection apparatus comprising:
a charged particle optical system configured to irradiate a sample with a charged particle beam; a first probe configured to come into contact with the sample; an amplifier having an input terminal to which the first probe is connected; a frequency generator configured to generate a reference signal; a phase detection unit configured to detect an output signal of the amplifier using the reference signal generated by the frequency generator; a system control unit; a charged particle control unit configured to control the charged particle optical system; and an image processing unit configured to form an image from an output signal input from the phase detection unit, wherein the system control unit outputs a scanning signal that causes the charged particle control unit to scan the sample with the charged particle beam, the image processing unit forms the image by calculating a gray value per pixel from a detection signal input from the phase detection unit based on a control signal input from the system control unit in synchronization with the scanning signal, and the system control unit sets a frequency of the reference signal generated by the frequency generator to a value higher than or equal to a sampling rate that is a reciprocal of an electron beam irradiation time per pixel of the image.

11 . The sample inspection apparatus according to claim 10 , further comprising a second probe configured to come into contact with the sample,
wherein the amplifier is a differential amplifier, and the first probe and the second probe are connected to input terminals of the differential amplifier, respectively.

12 . The sample inspection apparatus according to claim 11 ,
wherein a predetermined DC voltage is applied between the input terminals of the differential amplifier.

Assignees

• Hitachi High Tech Corp

Inventors

• SHIMAMORI Tomoko
• Nara Yasuhiko
• Fuse Junichi
• Kageyama Akira

Classifications

• H01J2237/221

  Image processing · CPC title

• H01J37/222

  Image processing arrangements associated with the tube · CPC title

• G01R31/305

  using electron beams {(investigating or analysing materials by measuring photoelectric effect G01N23/227)} · CPC title

• G01R1/28

  Provision in measuring instruments for reference values, e.g. standard voltage, standard waveform · CPC title

• G01R1/06766

  Input circuits therefor · CPC title