An electron beam apparatus is provided for reliably measuring a potential contrast and the like at a high throughput in a simple structure. The electron beam apparatus for irradiating a sample, such as a wafer, formed with a pattern with an electron beam to evaluate the sample comprises an electron-optical column for accommodating an electron beam source, an objective lens, an E×B separator, and a secondary electron beam detector; a stage for holding the sample, and relatively moving the sample with respect to the electron-optical column; a working chamber for accommodating the stage and capable of controlling the interior thereof in a vacuum atmosphere; a loader for supplying a sample to the stage; a voltage applying mechanism for applying a voltage to the sample, and capable of applying at least two voltages to a lower electrode of the objective lens; and an alignment mechanism for measuring a direction in which dies are arranged on the sample. When the sample is evaluated, a direction in which the stage is moved is corrected to align with the direction in which the dies are arranged.

Electron beam apparatus and device manufacturing method using same

A defect inspection method and device for irradiating a linear region on a surface-patterned sample mounted on a table, with illumination light from an inclined direction to the sample, next detecting in each of a plurality of directions an image of the light scattered from the sample irradiated with the illumination light, then processing signals obtained by the detection of the images of the scattered light, and thereby detecting a defect present on the sample; wherein the step of detecting the scattered light image in the plural directions is performed through oval shaped lenses in which elevation angles of the optical axes thereof are different from each other, within one plane perpendicular to a plane formed by the normal to the surface of the table on which to mount the sample and the longitudinal direction of the linear region irradiated with the irradiation light.

Defect Inspection Method and Defect Inspection Device

The invention relates to a method of determining the distortions in the projection system of a TEM, and a method of correcting for these aberrations. The aberrations are determined by collecting a large number of images of a sample, the sample slightly displaced between each acquisition of an image. On the images sub-fields (303, 304-i) showing identical parts of the sample are compared. These sub-fields (303, 304-i) will show small differences, corresponding to differential aberrations. In this way the differential aberrations in a large number of points can determined, after which the aberrations for each point can be determined by integration. By now correcting the position of each detected pixel in an image to be displayed, the displayed image has much reduced aberrations. An advantage of the method according to the invention is that no highly accurate steps of the sample are needed, nor is a sample with known geometry needed.

Method for determining distortions in a particle-optical apparatus

According to the ITRS Roadmap, the EUV mask requirement for 2X nm technology node is detection of defect size of
20 nm. The history of optical mask inspection tools involves continuous efforts to realize higher resolution and higher
throughput. In terms of productivity, considering resolution, throughput and cost, we studied the capability of EUV light
inspection and Electron Beam (EB) inspection, using Scanning Electron Microscope (SEM), including prolongation of
the conventional optical inspection. As a result of our study, the solution we propose is EB inspection using Projection
Electron Microscope (PEM) technique and an image acquisition technique to acquire inspection images with Time Delay
Integration (TDI) sensor while the stage is continually moving. We have developed an EUV mask inspection tool,
EBeyeM, whole design concept includes these techniques. EBeyeM for 2X nm technology node has the following targets,
for inspection sensitivity, defects whose size is 20 nm must be detected and, for throughput, inspection time for particle
and pattern inspection mode must be less than 2 hours and 13 hours in 100 mm square, respectively. Performance of the
proto-type EBeyeM was reported. EBeyeM for 2X nm technology node was remodeled in light of the correlation
between Signal to Noise Ratio (SNR) and defect sensitivity for the proto-type EBeyeM. The principal remodeling points
were increase of the number of incident electrons to TDI sensor by increasing beam current for illuminating optics and
realization of smaller pixel size for imaging optics.
This report presents the performance of the remodeled EBeyeM (=EBeyeM for 2X nm) and compares it with that of the
proto-type EBeyeM. Performances of image quality, inspection sensitivity and throughput reveal that the EBeyeM for
2X nm is improved. The current performance of the EBeyeM for 2X nm is inspection sensitivity of 20 nm order for both
pattern and particle inspection mode, and throughput is 2 hours in 100 mm square for particle inspection mode.

Performance of EBeyeM for EUV mask inspection

The charged particle beam device of this invention separately detects secondary signal particles emitted from the surface of a sample, dark field signal particles scattered within and transmitted through the sample, bright field signal particles transmitted through the sample without being scattered within the sample, and thereby allows the operator to observe the image with an optimum contrast according to applications. In order to detect only the dark field transmitted signal particles scattered within the sample, among the transmitted signal particles obtained by the primary charged particle beams having transmitted through the thin film sample, the device includes a transmitted signal conversion member having an opening through which the bright field transmitted signal particles not being scattered within the sample can pass, and a detection means for detecting signals colliding against the conversion member.

Charged particle beam device

An electron beam inspection system based on the projection imaging electron microscope was developed and the proof-of-concept system has been constructed and evaluated. The secondary electrons are projected through the projection imaging optics and imaged onto the image detection system. The projected secondary electron image is amplified by the microchannel plate and converted to an optical image by the fluorescent screen and detected by the 2048 element, eight-tap time delay and integration (TDI) image sensor. The stage is linearly moved in synchronism with the TDI signal output data rate, and then, the secondary electron image is continuously captured. The spatial resolution of around 0.1 μm has been obtained in this experiment. Several images obtained by the TDI imaging mode are also demonstrated.

Electron beam inspection system based on the projection imaging electron microscope

We have developed a proof of concept system, utilizing a projection electron microscope for the next generation EB inspection system. In this POC system, the image quality of secondary electrons is quite sensitive to the homogeneity of wafer surface potential. In logic devices with a random pattern layout, both image distortion and inhomogeneous image contrast are serious problems. By homogenizing the wafer surface potential with negative charging of the semiconductor device, we could eliminate image distortion and inhomogeneous image contrast using a pretreatment dosage of 12 mC/cm2. Furthermore, by imaging the reflection electrons with 4000 V, a high image quality can be obtained, even with contact/via layers. By selecting the optimum energy of the imaging electrons, the imaging capability of this EB inspection system could be widely improved. We can also confirm the practicality of this technology for wafer inspection of ULSI devices.

Development of an electron optical system using EB projection optics in reflection mode for EB inspection

A pattern matching method includes: detecting an edge of a pattern in a pattern image obtained by imaging the pattern; segmenting the detected pattern edge to generate a first segment set consisting of first segments; segmenting a pattern edge on reference data which serves as a reference for evaluating the pattern to generate a second segment set consisting of second segments; combining any of the segments in the first segment set with any of the segments in the second segment set to define a segment pair consisting of first and second segments; calculating the compatibility coefficient between every two segment pairs in the defined segment pairs; defining new segment pairs by narrowing down the defined segment pairs by calculating local consistencies of the defined segment pairs on the basis of the calculated compatibility coefficients and by excluding segment pairs having lower local consistencies; determining an optimum segment pair by repeating the calculating the compatibility coefficient and the defining new segment pairs by narrowing down the segment pairs; calculating a feature quantity of a shift vector that links the first and second segments making up the optimum segment pair; and performing position matching between the pattern image and the reference data on the basis of the calculated feature quantity of the shift vector.

Pattern matching method, program and semiconductor device manufacturing method

Optical inspection systems and/or electron beam inspection systems are quite useful tools for the yield management in the semiconductor process. However, they have some issues of difficulties for the application to the yield management after 100nm-technology node generation. Optical inspection systems have a resolution limit by diffraction phenomena. On the other hand, electron beam inspection systems based on scanning electron microscopy (EBI-SEM) have the limit of inspection speed. Both limits are serious matter for the application to yield management after 100nm-technology node generation. We have developed the electron beam inspection system based on projection electron microscopy (EBI-PEM), having both performances of inspection speed of optical types and spatial resolution of EBI-SEM. The system has been improved on the signal electron collection efficiency and transmittance of the electron optical system. We also have developed high rate and sensitive signal detection system. Then we considered that the inspection speed of several times faster than the conventional EBI-SEM is feasible at the spatial resolution less than 100nm.

Electron beam inspection system for semiconductor wafer based on projection electron microscopy: II

A defect inspection apparatus includes a charged particle beam source which emits a charged particle beam to illuminate the charged particle beam onto a sample as a primary beam; an image pickup which includes an imaging element having a light receiving face receiving at least one of a secondary charged particle, a reflective charged particle, and a back-scattered charged particle generated from the sample by the illumination of the primary beam and which outputs a signal indicating a state of the surface of the sample; a mapping projection system which maps/projects at least one of the secondary charged particle, the reflective charged particle, and the back-scattered charged particle as a secondary beam and which makes the beam to form an image on the light receiving face of the imaging element; a controller which adjusts a beam diameter of the primary beam in such a manner as to apply the beam to the sample with a size smaller than that of an imaging region as a target of review to scan the imaging region and which allows the image pickup to pick up a plurality of frame images; an image processor which processes the plurality of obtained frame images to prepare a review image; and a defect judgment unit which judges a defect of the sample based on the review image.

Onishi Atsushi

Papers

Electron beam inspection system based on the projection imaging electron microscope

Development of an electron optical system using EB projection optics in reflection mode for EB inspection

Pattern matching method, program and semiconductor device manufacturing method

Electron beam inspection system for semiconductor wafer based on projection electron microscopy: II

Defect inspection apparatus, program, and manufacturing method of semiconductor device