KR20060092810A - Methods of scanning an object that includes multile regions of interest using an array of scanning beams - Google Patents

Abstract

The present invention relates to a multi-beam inspection method and system. The inspection system includes: (i) a beam array generator adapted to generate an array of beams characterized by beam array axes; And (ii) at least one mechanism adapted to position the object under the beam array such that at least two beams disposed along the beam array axis scan the region of interest of at least two portions of the object substantially simultaneously. The axis is oriented relative to the beam array axis.

Description

METHODS OF SCANNING AN OBJECT THAT INCLUDES MULTILE REGIONS OF INTEREST USING AN ARRAY OF SCANNING BEAMS

1 shows an inspection system according to an embodiment of the invention.

2 shows a wafer including multiple dies.

3 illustrates multiple spots corresponding to multiple beams in accordance with one embodiment of the present invention.

4-6 illustrate exemplary relationships between beams and multiple regions of interest in accordance with various embodiments of the present invention.

7 shows a number of additional areas and regions of interest 8 scanned according to an embodiment of the invention.

8 is a flowchart of a method according to an embodiment of the present invention.

9 illustrates a portion of a scan path of a raster scan shape in accordance with one embodiment of the present invention.

This application claims priority to US Application Serial No. 60 / 581,817, entitled "Scanning Regions of Interest Using Multi-Beam Systems," filed June 21, 2004, which application is incorporated herein by reference. do.

FIELD OF THE INVENTION The present invention relates to scanning an object comprising a plurality of regions of interest using a scanning beam array, and more particularly to scanning an object such as a wafer or a reticle using a charged particle beam array.

Inspection of objects such as wafers or reticles using scanning electron beam inspection tools is known in the art. The single beam inspection tool scans the wafer or reticle using one beam. The relative size difference between the wafer size and the beam crossing section limits the throughput of such a system.

Various techniques have been proposed to increase the throughput of inspection and metrology systems. The first technique involves scanning only a portion of the wafer or reticle. This portion typically includes a plurality of regions of interest located at various locations.

Another technique involves using multiple beam scanning arrays. Some multi-beam systems include a fixed beam array starting from a line array to a two dimensional grid array.

The following U.S. patents and U.S. patent applications, both incorporated herein by reference, provide a brief overview of some conventional multi-beam scanning systems: "Multiple parallel charged particle beams and multiple secondary-electron-detector arrays. US Pat. No. 6,465,783 to Nakasuji, entitled "High-throughput Sample-Inspection Devices and Methods Used;" US Pat. No. 6,734,428 to Parker et al. Entitled “Multi-beam Multi-Column Electron Beam Inspection System”; US 6,750,455 to Lo et al. Entitled “Methods and Apparatus for Multiple Charged Particle Beams”; US Pat. No. 6,803,572 to Veneklasen et al. Entitled “Apparatus and Method for Secondary Electron Emission Microscopes Using Double Beam”; And US Patent Application Publication No. 2002/0015143 to Yin et al. Entitled "Multi-beam Multi-Column Electron Beam Inspection System."

There is a need to provide an efficient system and method for scanning objects using multiple beam arrays.

The present invention provides an inspection system, comprising: (i) a beam array generator suitable for generating a beam array characterized by a beam array axis; And (ii) positioning the object below the beam array such that at least two beams located along the beam array axis, the first axis being directed relative to the beam array axis, to scan at least two regions of interest of the object substantially simultaneously. At least one mechanism.

In general, the system further includes a controller suitable for determining a first spatial relationship between at least two regions of interest located along one axis of interest region. In general, at least one mechanism is suitable for rotating an object in relation to a beam array. In general, at least one mechanism is suitable for rotating the beam array in relation to an object. In general, the system is suitable for determining spatial relationships by providing image processing.

In general, the system is suitable for scanning at least two regions of interest after the inspected object is located below the beam array.

A method for inspecting an object that includes a plurality of regions of interest includes: determining a first spatial relationship between at least two regions of interest located along a region of interest axis; And at least two beams of the beam array positioned along the beam array axis whose first axis is oriented relative to the beam array axis in response to at least the first spatial relationship such that the plurality of beam arrays scan at least two regions of interest substantially simultaneously. Positioning the object under the beam.

Generally, positioning includes rotating an object in relation to the array of beams. In general, the positioning step includes rotating the beam array in relation to the object. In general, the determining step includes an image processing step. In general, the method includes scanning at least two regions of interest.

In general, the aggregate area of the multiple regions of interest is very small compared to the size of the object surface. Generally, the object is a wafer or reticle. In general, the beam array comprises a beam grid.

In general, the beam is a charged particle beam. In general, the angle of orientation between the first axis and the beam array axis is in response to the ratio of beam array spacing and is between the region of interest spacing.

In order to understand the present invention and to understand how it is actually performed, preferred embodiments are described with reference to the accompanying drawings, but examples of the present invention are not limited to these embodiments.

DETAILED DESCRIPTION The following detailed description of the preferred and other embodiments of the present invention refers to the accompanying drawings. Those skilled in the art will appreciate that other embodiments and modifications are possible without departing from the concept of the invention.

To facilitate the description, the following description relates to a system for inspecting a wafer by an electron beam array. In accordance with another embodiment of the present invention, the disclosed systems and methods may be applied to metrology, such as lithography. The test object may be a reticle, a flat panel display, a MEMS device, or the like. The array shape may be different from the two-dimensional grid, and the beam may include an ion beam or a light beam.

1 shows an inspection system 10 according to an embodiment of the invention. System 10 includes a beam generator 20 that can generate a charged particle beam array 202. Beam generator 20 can be implemented in a variety of ways. According to the first embodiment a plurality of tips generates a plurality of beams. According to another embodiment a single tip generates a beam that is later converted into multiple beams.

스테이지(32)상에 위치된다.The beam generator also includes an optical system that focuses the beam array on an inspection object, such as wafer 100. Wafer 100 typically has X, Y stages 30, 31 and optionally

It is located on the stage 32.

Wafer 100 is inspected in vacuum chamber 40 and inserted into system 10 by cassette 50 having pre-alignment capability. These capabilities allow the wafer to be inserted at a predetermined tilted angle about the imaginary X and Y axes of the stage. It should be noted that parts other than cassette 50 may have pre-alignment capabilities. For example, the robot or pre-aligner may perform the required rotation before the wafer is placed on the X-Y stages 30-31.

System 10 further includes one or more detectors 60 and a processor 70 capable of receiving detector signals and locating defects. The processor 70 may also be used at an initial stage of positioning the region of interest. The positioning involves acquiring an image portion of the wafer until the region of interest is positioned.

The processor 70 may also be used to detect the angle of orientation between the beam array and the inspection wafer. It should be noted that the processor 70 may include a number of components that may be integrated with each other or located in various locations. For simplicity, various parts including the optical system are omitted.

It should be noted that the apparatus shown in FIG. 1 is one of various configurations of the inspection system 10 and may be a different architecture than the architecture shown.

2 shows a wafer 100 including a plurality of dies 102. Each die 102 has at least one region of interest, such as eight. For ease of explanation, it is assumed that each die includes a single region of interest and all these regions of interest are located at about the same location within the die. It is also assumed that the regions of interest 8 are arranged in a grid that is parallel to each other and corresponds to an arrangement of multiple dies.

The spacing between adjacent regions of interest along the first axis, such as the imaginary X axis, is defined by region of interest space (ROID) 111. Other limitations may be used and the imaginary axis X is used only for brief description.

Typically the dies are identical to each other. Thus, the region of interest is located at approximately the same location in each die. If a single region of interest is included in each die, the regions of interest included in multiple dies have the same shape and are typically parallel to each other. This need not be done if the method is used to specifically inspect objects other than wafers. It should be noted that if the die has areas other than a single region of interest, they may differ in shape, orientation, size, and the like.

3 shows multiple spots corresponding to multiple beams 202 in accordance with an embodiment of the present invention. The beam 202 of FIG. 2 forms a regular grid. 1 and 2 show a beam array and an array of regions of interest having the same shape (the spacing between adjacent members of the grid may be different), but this need not be the case.

Beam 202 of beam array 200 forms a number of columns along an imaginary beam array, such as the X 'axis. The spacing between adjacent beams along the X 'axis is considered the beam array spacing (BAD) 222.

If the BAD 222 is the same as the ROID 111, the wafer 100 is positioned below the beam generator such that the first axis X is parallel to the first beam array axis X ′. In such cases, multiple regions of interest may be located under multiple beam arrays. The amount of region of interest that can be scanned simultaneously depends on the amount of region of interest and the amount of beams, and assumes that the beam array is approximately the same shape as the imaginary grid formed by the region of interest.

If the BAD 222 is different from the ROID 11, it is necessary to orient the beam array relative to the wafer. Orientation can be achieved in a variety of ways, including wafer 100 rotation, beam 202 rotation, or both. Rotation may be applied after wafer 100 is placed in an inspection system or before being provided under a beam array.

스테이지(30-32) 상에 위치된다.Rotation may also be accomplished by various electric, magnetic and / or electromagnetic fields or combinations of these fields and mechanical means for rotating the beam array. Typically, wafers are XY and

Are positioned on stages 30-32.

The orientation angle follows the relationship between the BAD 222 and the ROID 111. In mathematical terms k * BAD = m * ROID * cos (θ), where θ is defined as the angle of orientation between the X and X 'axes, and m and k are positive integers.

It should be noted that in some cases, the above formula may be satisfied by the values of m and k rather than integers. In this case, the throughput of the system may be greater than that of a single beam system. If k or m is almost an integer, there may be a partial overlap between the first region of interest scanning by the first beam and another region of interest scanning, m ROID, the beam displaced by K * BAS from the first beam. Is displaced by

4-6 show exemplary relationships between beam 202 and multiple regions of interest 8. 4 and 5 show tilted orientation angles and FIG. 6 shows two beam rows that are rotated 90 degrees to scan multiple regions of interest. It should be noted that these figures and other figures herein are reduced. In particular, but not necessarily, the beam is typically significantly smaller than the guam core region.

4 shows a first exemplary relationship between the beam 202 and the region of interest 8.

According to embodiments of the present invention, additional regions as well as regions of interest may be scanned during the scanning process. These additional zones are defined corresponding to various parameters including scanning inaccuracy, region of interest location inaccuracy, differences in each region of interest within different dies, and mechanical movement limitations.

The wafer is scanned as the wafer moves along an imaginary axis, such as the Y axis. In many cases, the continuous movement of the wafer causes the beam to scan the stretch region between regions of interest.

7 shows a number of additional zones 110 and regions of interest 8 that are scanned according to an embodiment of the invention. The additional zone 110 is slightly larger than the region of interest 8. Each additional zone 110 surrounds a column of the region of interest 8. It should be noted that Figure 6 shows continuous additional zones but is not required.

In accordance with an embodiment of the present invention, the inspection system only processes signals from the region of interest, but is not required. The inspection system can be applied to various comparison methods including die to die, cell to cell, and the like.

We use a beam array that includes two rows of 5 beams each. It should be noted that other arrays can be used, including arrays containing more beams and arrays shaped in different ways.

In some cases, the regions of interest are arranged in columns and the inventors could increase throughput by applying a 90 degree orientation angle.

8 is a flowchart of a method 400 for inspecting an object that includes a plurality of regions of interest.

The method 400 begins at stage 410 to determine a first spatial relationship between at least two regions of interest located along the axis of the region of interest. Typically, stage 410 includes rotating an object about a beam array. Typically, stage 410 includes rotating a beam array about an object. Typically the beam is a charged particle beam.

Stage 410 continues to stage 420 where the beam is positioned under multiple beams of the beam array in response to at least a first spatial relationship such that at least two beams of the beam array positioned along the beam array axis are at least two interests. Scanned almost simultaneously with the area, the first axis is oriented about the beam array axis.

Typically, the angle of orientation between the first axis and the beam array axis follows the ratio between the beam array space and the region of interest space. Typically, stage 420 involves image processing.

Stage 420 continues to stage 430 scanning at least two regions of interest.

Typically, stage 420 includes orienting an object about a beam array axis prior to inserting the object into an inspection system that includes a beam array generator.

9 shows a portion of a raster scan shape scan path 201 formed by mechanical movement along the Y axis and deflection of a single beam along the X axis.

Typically, the aggregation zone of the multiple regions of interest is considerably smaller than the size of the object surface, typically the concentrated size of the scanned zone. Typically, the object is a wafer or reticle. Typically the beam array comprises a beam grid.

The invention can be carried out using conventional tools, measurements and components. Accordingly, details of such tools, components, and measurements are not disclosed herein. In the preceding description, various specific embodiments are disclosed, such as test structures and shapes of materials, which are electro-optically activated for understanding of the present invention. However, it will be appreciated that the invention may be practiced without the specific details.

Exemplary and only a few embodiments of the invention have been shown and disclosed herein. The invention may be modified and modified within the scope of the appended claims.

In accordance with the present invention, an efficient system and method for scanning an object using a multi-beam array can be provided.

Claims (22)

A method of inspecting an object that includes a plurality of regions of interest, Determining a first spatial relationship between at least two portions of the region of interest disposed along the axis of the region of interest; And In response to at least the first spatial relationship, the object is placed below the plurality of beams of the beam array such that at least two beams of the beam array disposed along the beam array scan substantially simultaneously the region of interest of the at least two portions. Disposing; wherein the first axis is oriented relative to the beam array axes. 2. The method of claim 1, wherein the placing step comprises rotating the object relative to the array of beams. 2. The method of claim 1, wherein the placing step comprises rotating the array of beams with respect to the object. The method of claim 1 wherein the beams are charged particle beams. 2. The method of claim 1, wherein the orientation angle between the first axis and the particle beam axis follows a ratio between the beam array space and the region of interest space. The method of claim 1, wherein the determining step comprises an image processing step. The method of claim 1, further comprising scanning the at least two portions of the region of interest. The method of claim 1, wherein the collection area of the plurality of regions of interest is relatively small relative to the size of the surface of the object. The method of claim 1, wherein the object is a wafer or a reticle. The method of claim 1 wherein the array of beams comprises a grating of the beams. 10. The method of claim 1, wherein the placing step includes rotating the object relative to the beam array before introducing the object into an inspection system comprising the array generator of beams. Inspection system, A beam array generator adapted to generate an array of beams characterized by the beam array axis; And At least two beams disposed along the beam array axis include at least one mechanism applied to position the object below the beam array such that at least two portions of the object scan the region of interest substantially simultaneously. And orienting about the beam array axis. 13. The inspection system of claim 12 further comprising a processor adapted to determine a first spatial relationship between at least two portions of the regions of interest disposed along the axis of the region of interest. 13. The inspection system of claim 12, wherein the at least one mechanism is adapted to rotate the object relative to the array of beams. 13. The inspection system of claim 12, wherein the at least one mechanism is adapted to rotate the array of beams with respect to the object. 13. The inspection system of claim 12, wherein the beams are charged particle beams. 13. The object inspection system of claim 12, wherein the orientation angle between the first axis and the particle beam axis follows a ratio between beam array space and region of interest space. 13. The inspection system of claim 12, wherein the inspection system is adapted to be determined by image processing. 13. The inspection system of claim 12, adapted to scan at least two portions of the region of interest. 13. The inspection system of claim 12, wherein the aggregation zone of the plurality of regions of interest is relatively small relative to the size of the surface of the object. 13. The inspection system of claim 12, wherein the object is a wafer or a reticle. 13. The inspection system of claim 12, wherein said array of beams comprises a grating of beams.

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