45 results about "Wien filter" patented technology

A sample is evaluated at a high throughput by reducing axial chromatic aberration and increasing the transmittance of secondary electrons. Electron beams emitted from an electron gun 1 are irradiated onto a sample 7 through a primary electro-optical system, and electrons consequently emitted from the sample are detected by a detector 12 through a secondary electro-optical system. A Wien filter 8 comprising a multi-pole lens for correcting axial chromatic aberration is disposed between a magnification lens 10 in the secondary electro-optical system and a beam separator 5 for separating a primary electron beam and a secondary electron beam, for correcting axial chromatic aberration caused by an objective lens 14 which comprises an electromagnetic lens having a magnetic gap defined on a sample side.

A sample is evaluated at a high throughput by reducing axial chromatic aberration and increasing the transmittance of secondary electrons. Electron beams emitted from an electron gun 1 are irradiated onto a sample 7 through a primary electro-optical system, and electrons consequently emitted from the sample are detected by a detector 12 through a secondary electro-optical system. A Wien filter 8 comprising a multi-pole lens for correcting axial chromatic aberration is disposed between a magnification lens 10 in the secondary electro-optical system and a beam separator 5 for separating a primary electron beam and a secondary electron beam, for correcting axial chromatic aberration caused by an objective lens 14 which comprises an electromagnetic lens having a magnetic gap defined on a sample side.

A noise cancellation apparatus includes a noise estimation module for receiving a noise-containing input speech, and estimating a noise therefrom to output the estimated noise; a first Wiener filter module for receiving the input speech, and applying a first Wiener filter thereto to output a first estimation of clean speech; a database for storing data of a Gaussian mixture model for modeling clean speech; and an MMSE estimation module for receiving the first estimation of clean speech and the data of the Gaussian mixture model to output a second estimation of clean speech. The apparatus further includes a final clean speech estimation module for receiving the second estimation of clean speech from the MMSE estimation module and the estimated noise from the noise estimation module, and obtaining a final Wiener filter gain therefrom to output a final estimation of clean speech by applying the final Wiener filter gain.

A detection unit of a charged particle imaging system includes a multi type detection subunit in the charged particle imaging system, with the assistance of a Wien filter (also known as an E×B charged particle analyzer). The imaging system is suitable for a low beam current, high resolution mode and a high beam current, high throughput mode. The unit can be applied to a scanning electron inspection system as well as to other systems that use a charged particle beam as an observation tool.

This invention provides a multi-pole type Wien filter, which acts more purely approaching its fundamentally expected performance. A 12-electrode electric device acts as an electric deflector, or acts as an electric deflector and an electric stigmator together. A cylindrical 4-coil magnetic device with a magnetic core acts as a magnetic deflector. Both can produce a dipole field while only incurring a negligibly-small 3rd order field harmonic. The magnetic core enhances the strength and more preciously regulates the distribution of the magnetic field originally generated by the coils. Then two ways to construct a Wien filter are proposed. One way is based on both of the foregoing electric and magnetic devices, and the other way is based on the foregoing electric device and a conventional magnetic deflector. The astigmatism in each of such Wien filters can be compensated by the electric stigmator of the electric device.

A Wien filter is provided in which a less amount of secondary aberration is produced than conventional. This filter has 12 poles. These poles have front ends facing the optical axis. These front ends have a 12-fold rotational symmetry about the optical axis within the XY-plane perpendicular to the optical axis.

An electron beam apparatus for providing an evaluation of a sample, such as a semiconductor wafer, that includes a micro-pattern with a minimum line width not greater than 0.1 μm with high throughput. A primary electron beam generated by an electron gun is irradiated onto a sample and secondary electrons emanating from the sample are formed into an image on a detector by an image projection optical system. An electron gun 61 has a cathode 1 and a drawing electrode 3, and an electron emission surface 1a of the cathode defines a concave surface. The drawing electrode 3 has a convex surface 3a composed of a partial outer surface of a second sphere facing the electron emission surface 1a of the cathode and an aperture 73 formed through the convex surface for passage of the electrons. An aberration correction optical apparatus comprises two identically sized multi-polar Wien filters arranged such that their centers are in alignment with a ¼ plane position and a ¾ plane position, respectively, along an object plane-image plane segment in the aberration correction optical apparatus, and optical elements having bidirectional focus disposed in an object plane position, an intermediate image-formation plane position and an image plane position, respectively, in the aberration correction optical apparatus.

An electron beam emitted from an electron gun (G) forms a reduced image on a sample (S) through a non-dispersion Wien-filter (5-1), an electromagnetic deflector (11-1), a beam separator (12-1), and a tablet lens (17-1) as an objective lens. The beam separator (12-1) is configured such that a distance by which a secondary electron beam passes through the beam separator is approximately three times longer than a distance by which a primary electron beam passes through the beam separator. Therefore, even if a magnetic field in the beam separator is set to deflect the primary electron beam by a small angle equal to or less than approximately 10 degrees, the secondary electron beam can be deflected by approximately 30 degrees, so that the primary and secondary electron beams are sufficiently separated. Also, since the primary electron beam is deflected by a small angle, less aberration occurs in the primary electron beam. Accordingly, since a light path length of a primary electro-optical system, it is possible to reduce the influence of space charge and the occurrence of deflection aberration.

A detection unit of a charged particle imaging system includes a multi type detection subunit in the charged particle imaging system, with the assistance of a Wien filter (also known as an E×B charged particle analyzer). The imaging system is suitable for a low beam current, high resolution mode and a high beam current, high throughput mode. The unit can be applied to a scanning electron inspection system as well as to other systems that use a charged particle beam as an observation tool.

This invention provides a multi-pole type Wien filter, which acts more purely approaching its fundamentally expected performance. A 12-electrode electric device acts as an electric deflector,or acts as an electric deflector and an electric stigmator together. A cylindrical 4-coil magnetic device with a magnetic core acts as a magnetic deflector. Both can produce a dipole field while only incurring a negligibly-small 3rd order field harmonic. The magnetic core enhances the strength and more preciously regulates the distribution of the magnetic field originally generated by the coils. Then two ways to construct a Wien filter are proposed. One way is based on both of the foregoing electric and magnetic devices, and the other way is based on the foregoing electric device and a conventional magnetic deflector. The astigmatism in each of such Wien filters can be compensated by the electric stigmator of the electric device.

The present invention provides an improved electron-optical apparatus for the inspection and review of the specimen, and for the defect inspection, an inspection mode of operation is performed to generate inspection data, wherein the large beam current is formed by a magnetic immersion lens to scan the specimen, and preferably the objective lens system, a swing objective retarding immersion lens, focuses the beam current and generates the large scanning field, and for the defect review, the review mode of operation is performed to analyze the defects, wherein the large beam current is abandoned and the small beam current is adopted to examine the specimen without a large scanning field, and in order to properly select and detect signal charged particles excited from the specimen, a first Wien filter is utilized to select the acquired signal particles and a second Wien filter is used to compensate the aberrations induced when the signal particles pass through the first Wien filter.

The monochromator for reducing energy spread of a primary charged particle beam in charged particle apparatus comprises a beam adjustment element, two Wien-filter type dispersion units and an energy-limit aperture. In the monochromator, a dual proportional-symmetry in deflection dispersion and fundamental trajectory along a straight optical axis is formed, which not only fundamentally avoids incurring off-axis aberrations that actually can not be compensated but also ensures the exit beam have a virtual crossover which is stigmatic, dispersion-free and inside the monochromator. The present invention also provides two ways to build a monochromator into a SEM, in which one is to locate a monochromator between the electron source and the condenser, and another is to locate a monochromator between the beam-limit aperture and the objective. The former provides an additional energy-angle depending filtering, and obtains a smaller effective energy spread.

An ExB Wien mass filter providing a method and structure for mechanically adjusting the magnetic field distributions at the mass filter entrance and exit end caps. The reluctance of the flux return path may be modified by configuring pluralities of magnetic shims within slots at the outer diameters of the entrance and exit end caps, and also by configuring pluralities of magnetic plug shims within circular flux dams surrounding the entrance and exit apertures. Advantages of purely mechanical adjustment for the magnetic fields of the present invention, compared with prior art electromagnet adjustment methods include greater reliability, simplicity, lower cost, and lack of power dissipation. The invention may employ either permanent magnets or electromagnets for generation of the mass-separation magnetic field.

An isotope ratio mass spectrometer has an ion source, a static field mass filter, a reaction cell to induce a mass shift reaction, and a sector field mass analyser for spatially separating ions from the reaction cell according to their m / z. A detector platform detects a plurality of different ion species separated by the sector field mass analyser. The static field mass filter has a first Wien filter that deflects ions away from a longitudinal symmetry axis of the spectrometer in accordance with the ions' m / z, and a second Wien filter that deflects ions back towards the longitudinal symmetry axis in accordance with the ions' m / z. An inverting lens is positioned along the longitudinal axis between the Wien filters to invert the direction of deflection of the ions from the first Wien filter. The static field mass filter provides high transmission and improved spectrometer sensitivity. The first and second Wien filters permit simple tuning.

A noise cancellation apparatus includes a noise estimation module for receiving a noise-containing input speech, and estimating a noise therefrom to output the estimated noise; a first Wiener filter module for receiving the input speech, and applying a first Wiener filter thereto to output a first estimation of clean speech; a database for storing data of a Gaussian mixture model for modeling clean speech; and an MMSE estimation module for receiving the first estimation of clean speech and the data of the Gaussian mixture model to output a second estimation of clean speech. The apparatus further includes a final clean speech estimation module for receiving the second estimation of clean speech from the MMSE estimation module and the estimated noise from the noise estimation module, and obtaining a final Wiener filter gain therefrom to output a final estimation of clean speech by applying the final Wiener filter gain.

The invention provides a speech enhancement method that can restrain noise component in noisy voice and improve voice quality and intelligibility in noise environment. According to the method of the present invention, it specifically includes the following steps: 1) first, estimating the noise spectrum of the speech using endpoint detection technology; 2) removing noise using two-step Wiener filter technology; 3) meanwhile, adjusting the filter parameters according to auditory masking curve. The de-noising method in the invention has undertaken a thorough study and consideration on the signal level and perceptual level. For the estimation of noise, it uses the endpoint detection method, which has good robustness, to accurate estimate the noise spectrum as far as possible. Furthermore, it uses a two-step Wiener filter to solve this problem. Meanwhile, taking into account people's ears, by using auditory masking curve, it decreases the signal distortion. Thus, the eventually enhanced signal has a big increase on the voice quality and intelligibility.