Systems and methods for pulsed voltage contrast detection and capture of charging dynamics

Patent metadata

Field	Value
Publication number	US-12567558-B2
Application number	US-202118019088-A
Country	US
Kind code	B2
Filing date	Jul 27, 2021
Priority date	Jul 31, 2020
Publication date	Mar 3, 2026
Grant date	Mar 3, 2026

Abstract

Systems and methods of observing a sample using a charged-particle beam apparatus in voltage contrast mode are disclosed. The charged-particle beam apparatus comprises a charged-particle source, an optical source, a charged-particle detector configured to detect charged particles, and a controller having circuitry configured to apply a first signal to cause the optical source to generate the optical pulse, apply a second signal to the charged-particle detector to detect the second plurality of charged particles, and adjust a time delay between the first and the second signals. In some embodiments, the controller having circuitry may be further configured to acquire a plurality of images of a structure, to determine an electrical characteristic of the structure based on the rate of gray level variation of the plurality of images of the structure, and to simulate, using a model, a physical characteristic of the structure based on the determined electrical characteristic.

First claim

The invention claimed is:

1 . A charged-particle beam apparatus comprising:
a charged-particle source configured to generate a primary charged-particle beam along a primary optical axis; an optical source configured to generate a pulsed optical beam interacting with a sample, the interaction generating a first plurality of charged particles; a charged-particle detector configured to detect a second plurality of charged particles generated from a probe spot on the sample formed by the primary charged-particle beam and modified by interaction with a portion of the first plurality of charged particles; and a controller having circuitry configured to:
apply a first signal with a first timing to cause the optical source to generate the pulsed optical beam;
apply a second signal with a second timing to the charged-particle detector to initiate pulsed detection of the second plurality of charged particles; and
adjust a time delay that is based on a timing difference between pulses of the first signal and the second signal.

2 . The apparatus of claim 1 , wherein the first plurality of charged particles comprises photoelectrons and the second plurality of charged particles comprises secondary electrons, backscattered electrons, or auger electrons.

3 . The apparatus of claim 1 , wherein the controller includes circuitry further configured to adjust the first signal to cause an adjustment of a characteristic of an excitation pulse of the pulsed optical beam.

4 . The apparatus of claim 3 , wherein the characteristic of the excitation pulse comprises an intensity, a width, a repetition rate, or a phase of the excitation pulse.

5 . The apparatus of claim 4 , wherein the width of the excitation pulse is adjustable and is in a range of 0.05 picoseconds (ps) to 1 nanosecond (ns).

6 . The apparatus of claim 4 , wherein the repetition rate of the excitation pulse is adjustable and is in a range of 100 kHz to 1 GHz.

7 . The apparatus of claim 3 , wherein the controller includes circuitry further configured to adjust the second signal based on the characteristic of the excitation pulse, and wherein the second signal comprises a detection signal that enables detection of the second plurality of charged particles.

8 . The apparatus of claim 7 , wherein an adjustment of the second signal comprises an adjustment of a repetition rate, a width, or a phase of the detection signal.

9 . The apparatus of claim 7 , wherein the controller includes circuitry further configured to, based on an adjustment of the time delay, adjust a timing between the excitation pulse and the detection signal to adjust a sensitivity of the second plurality of charged particles detected by the charged-particle detector.

10 . The apparatus of claim 9 , wherein adjustment of the time delay comprises an adjustment of a phase of the detection signal.

11 . The apparatus of claim 10 , wherein the adjustment of the phase of the detection signal causes the detection signal and the excitation pulse to be out-of-phase with each other.

12 . The apparatus of claim 1 , wherein the optical source comprises a solid-state laser, a semiconductor laser, a gas laser, a dye laser, a chemical laser, a diode-pumped fiber laser, a gain-switched laser, or gain-switched laser diodes coupled with fiber amplifiers.

13 . The apparatus of claim 1 , wherein the pulsed optical beam comprises a pulsed laser beam having a photon wavelength in a range of 150 nm to 2 μm.

14 . The apparatus of claim 1 , wherein a noise associated with the pulsed optical beam is reduced using a technique comprising homodyne detection, heterodyne detection, lock-in amplification, or a combination thereof.

15 . A non-transitory computer readable medium storing a set of instructions that is executable by one or more processors of a charged-particle beam apparatus comprising a charged-particle source, an optical source, a charged-particle detector, and a controller, to cause the charged-particle beam apparatus to perform operations for forming an image of a sample, the operations comprising:
activating the charged-particle source to generate a primary charged-particle beam along a primary optical axis; activating the optical source to generate a pulsed optical beam with a first timing that interacts with the sample, the interaction generating a first plurality of charged particles; applying a signal with a second timing to the charged-particle detector to detect a second plurality of charged-particles generated from a probe spot on the sample formed by the primary charged-particle beam and modified by interaction with a portion of the first plurality of charged particles; adjusting a time delay that is based on a timing difference between pulses of the pulsed optical beam and the signal; and forming an image of the sample based on the detected second plurality of charged-particles and the adjusted time delay.

16 . A controller of a charged-particle beam apparatus, the controller comprising:
circuitry configured to:
apply a first signal with a first timing to cause an optical source to generate a pulsed optical beam interacting with a sample, the interaction generating a first plurality of charged particles;
apply a second signal with a second timing to a charged-particle detector to detect a second plurality of charged-particles generated from a probe spot on the sample formed by a primary charged-particle beam and modified by interaction with a portion of the first plurality of charged particles; and
adjust a time delay that is based on a timing difference between pulses of the pulsed optical beam and the signal.

17 . The controller of claim 16 , further comprising circuitry configured to adjust the first signal to adjust a characteristic of an excitation pulse of the pulsed optical beam, the characteristic of the excitation pulse comprising an intensity, a width, a repetition rate, or a phase of the excitation pulse.

18 . The controller of claim 17 , further comprising circuitry configured to adjust the second signal based on the characteristics of the excitation pulse, the second signal comprising a detection signal.

19 . The controller of claim 18 , further comprising circuitry configured to, based on an adjustment of the time delay, adjust a timing between the excitation pulse and the detection signal to adjust a sensitivity of the second plurality of charged particles detected by the charged-particle detector.

20 . The controller of claim 16 , wherein the circuitry comprises a synchronous digital circuit, a master clock, or a synchronous driver circuit.

Assignees

• Asml Netherlands Bv

Inventors

• Gaury Benoit Herve
• Jiang Jun
• La Fontaine Bruno
• Hasan Shakeeb Bin
• Kanai Kenichi
• Van Rens Jasper Frans Mathijs
• Tabery Cyrus Emil
• Ma Long
• Patterson Oliver Desmond
• Zhang Jian
• Jen Chih-Yu
• Wang Yixiang

Classifications

• H01J2237/2482

  Optical means · CPC title

• H01J37/244 Primary

  Detectors; Associated components or circuits therefor · CPC title

• H01J37/228

  whereby illumination or light collection take place in the same area of the discharge · CPC title

• G01N23/2251

  using incident electron beams, e.g. scanning electron microscopy [SEM] · CPC title

• H01J37/265 Primary

  Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination · CPC title