Various approaches are provided for automatically focusing particle beams for SPA. In one example, a method includes determining a focus adjustment for a region of a sample to achieve a targeted defocus based on at least one defocus measurement from at least one neighboring region of the sample, and causing an acquisition of an image of the sample at the region with the focus adjustment. In this way, a targeted defocus may be achieved across regions of a sample with reduced auxiliary imaging, thereby providing increased and uniform image quality while reducing the time and thus increasing the throughput of processing.

Apparatus and methods are disclosed for particle beam focusing, suitable for use in sample preparation or test environments, including SEM-based nanoprobing platforms. With a particle beam incident on a sample surface, stage current is used as an indicator of spot size. By scanning or searching settings of a working distance control, a control value having maximum (or minimum) stage current is used to set the beam waist at the sample surface. Alternatively, minima (or maxima) of reflected current can be used. Stigmator controls can be adjusted similarly to reduce astigmatism. The scan of control settings can be performed concurrently with sweeping the beam across a region of interest on the sample. Curved sweep patterns can be used. Energy measurements can be used as an alternative to current measurement. Applications to a nanoprobing workflow are disclosed.

There is provided a charged particle beam apparatus that can reduce the processing time. A charged particle beam apparatus includes: an excitation control unit that controls a focal position by changing a control value of excitation of an electronic lens; an electrostatic field control unit that controls the focal position by changing a control value of an electrostatic field; a focal position height estimation unit that estimates a height of the focal position from the control value of the excitation of the electronic lens; and a control unit that controls the excitation control unit and the electrostatic field control unit. The control unit compares the height of the focal position estimated by the focal position height estimation unit with a height of a sample surface of a sample to be observed, and according to a result of comparison, determines whether it is necessary to change the control value of the excitation of the electronic lens before observing the sample.

A control system of a charged particle beam apparatus obtains a first coefficient by performing multiple resolution analysis based on wavelet transform or discrete wavelet transform on at least a part of an image or a signal acquired by the charged particle beam apparatus. The control system obtains a second coefficient by performing, on at least a part of the first coefficient or an absolute value of the first coefficient, any one of calculation of a maximum value, calculation of a numerical value corresponding to a specified order in an order related to a magnitude, fitting to a histogram, calculation of an average value, and calculation of a total sum.

A charged particle beam system that improves throughput by applying an approximate expression created using a wafer to be actually measured is provided. The invention is directed to a charged particle beam system including a charged particle beam device that includes a detector configured to detect a signal particle obtained by irradiating a sample with a charged particle beam and a computer system that controls an operation of the charged particle beam device, in which the computer system executes a process of performing autofocus on each of a plurality of peripheral AF points set in the sample and outside a measurement area, and acquiring focus information of the plurality of AF points, a process of approximating focus distribution within the measurement area based on the focus information of the plurality of peripheral AF points, and a process of measuring each measurement point within the measurement area of the same sample as the sample from which the focus information is acquired, using the approximated focus distribution.

A focus adjustment method for a charged particle beam device having a magnetic field lens used for focus adjustment and an astigmatism corrector includes: acquiring a plurality of first images by varying an excitation current of the magnetic field lens within a focus search range, and determining a reference value of the excitation current; removing hysteresis from the magnetic field lens by setting the excitation current of the magnetic field lens outside the focus search range before and after varying the excitation current of the magnetic field lens within the focus search range; and acquiring a plurality of second images by varying the excitation current of the magnetic field lens using the reference value as a reference and varying a stigma correction value of the astigmatism corrector at each excitation current, and then determining optimum values of the excitation current and the stigma correction value.

A charged particle beam adjustment method includes scanning, with a charged particle beam an emission current of which is set to a first adjustment value smaller than a target value, an aperture substrate including a hole disposed to be a focus position of the charged particle beam using each of lens values in an electron lens and calculating first resolution, calculating a first function of lens values and the first resolution and calculating a lens value range, scanning, with the charged particle beam the emission current of which is set to a second adjustment value, the aperture substrate using each of lens values set to avoid the lens value range and calculating second resolution, calculating a second function of lens values and the second resolution and estimating a lens value at a just focus, and adjusting the electron lens to the lens value at the just focus.

The present invention addresses the problem of quickly specifying an optical condition of a wafer to be inspected, and in particular, accelerating optical condition setting after obtaining a customer wafer. An inspection apparatus automatic adjustment system according to the present invention comprises: an analysis condition setting interface 102 which inputs analysis conditions; an analysis execution unit 103 which performs analysis; an inspection device model and model DB 101 used for analysis; an analysis result DB 104 that stores analysis results; an observation condition setting interface 105 which inputs a wafer pattern, a focus point, an optimization index, and a priority; a wafer pattern search unit 106 which searches for a wafer pattern similar to the input wafer pattern; an optical condition extraction unit 107 which extracts, from the analysis result DB 104, the optimum optical condition for the similar wafer pattern and the focus point; and an optical condition setting unit 108 which generates a control signal corresponding to the optical condition and transmits the control signal to the inspection apparatus.

The present invention relates to an autofocus technique for a scanning electron microscope using interlaced scan. The autofocus method for a scanning electron microscope, includes: generating a thinned image of a pattern (160) formed on a surface of a specimen by repeatedly scanning the specimen with an electron beam while shifting a scanning position of the electron beam by predetermined plural pixels in a direction perpendicular to a scanning direction; performing said generating a thinned image of the pattern (160) plural times, while changing a focal position and an irradiation position of the electron beam, to generate thinned images of the pattern (160); calculating a plurality of sharpness levels of the respective thinned images; and determining an optimum focal position based on the sharpness levels.

A control system of a charged particle beam apparatus obtains a first coefficient by performing multiple resolution analysis based on wavelet transform or discrete wavelet transform on at least a part of an image or a signal acquired by the charged particle beam apparatus. The control system obtains a second coefficient by performing, on at least a part of the first coefficient or an absolute value of the first coefficient, any one of calculation of a maximum value, calculation of a numerical value corresponding to a specified order in an order related to a magnitude, fitting to a histogram, calculation of an average value, and calculation of a total sum.