JP2007109560A - Focused ion-beam device and processing-position setting method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focused ion-beam device capable of accurately setting a processing-position, without giving damages on a sample. <P>SOLUTION: This focused ion-beam device displays an enlarged image of an original image by enlarging it with a pixel-by-pixel interpolation, wherein the original image is generated by second particle signals sent from a detector. When a zoom ratio is large, the device recaptures an image once in the range of a beam deflection resolution, and performs a pixel by pixel linear interpolation on it being regarded as an original image, thereby an image with a high-zoom ratio can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention obtains a scanning ion microscope (SIM) image of a sample and sets a processing position of the focused ion beam device having a function of setting a region to be processed by the focused ion beam based on the image. Regarding the method.

  A scanning electron microscope (SEM) or a transmission electron microscope (TEM) is used for analyzing defects or defects of semiconductor elements. Sample fragments to be introduced into these observation apparatuses are produced by a focused ion beam (FIB) apparatus. The focused ion beam apparatus has high beam focusing performance, and performs fine processing by utilizing a sputtering phenomenon.

  In fine processing in a focused ion beam apparatus, processing positioning on a sample is necessary. Processing positioning is performed using a scanned image by a focused ion beam. In this processing positioning, beam deflection and pixel information acquisition processing that matches the display resolution (for example, 512 × 512 pixels) of the sample image on the control computer are performed, and a scanning ion microscope (Scanning Ion Microscope: SIM) image is displayed, The machining position is set based on this.

  In recent years, due to miniaturization of semiconductor elements and the like, the size of the characteristic part of a sample to be processed is very small. Therefore, in order to find the processing position and arrange it at the center of the field of view, a high magnification or high-definition scanning ion microscope image must be acquired. However, this increases the amount of ion beam applied to the sample and damages the sample.

  An object of the present invention is to provide a focused ion beam apparatus that can perform positioning with high accuracy while minimizing damage to a sample.

  According to the present invention, the focused ion beam device generates a zoom image by enlarging the original image generated by the secondary particle signal from the detector to a predetermined zoom rate and simultaneously performing pixel interpolation.

  According to the present invention, damage to the sample can be minimized and positioning with high accuracy can be performed.

  FIG. 1 is a diagram showing a schematic configuration of a focused ion beam apparatus of the present invention. The focused ion beam device generates the focused ion beam 120 and irradiates the sample 111 with the FIB column 10, the detector 112 that detects the secondary electrons 121 from the sample 111, the control device 20, and the image generation unit 30. And an input device 35 and a display device 36. The image generation unit 30 receives the secondary electron beam signal from the detector 112 and generates a scanning ion microscope (SIM) image. The image generation unit 30 includes a zoom unit 31, a shift unit 32, and a pixel interpolation unit 33 that performs pixel interpolation of the zoom image.

  In order to realize zooming and shifting, at least the beam deflection point resolution needs to be larger than the image display resolution. In this example, the beam deflection point resolution is 4096 × 4096 points, and the display resolution is 512 × 512 pixels. Therefore, zooming up to 8 times is possible.

  The image generation unit 30 may be a computer 201 or a program executed by the computer.

  FIG. 2 is a detailed view of the FIB column 10 of the focused ion beam apparatus of the present invention. The FIB column 10 includes a liquid metal ion source emitter 100, an extraction electrode 101, a condenser lens 102, a variable aperture 103, an aligner stigma 104, a blanker 105, a blanking aperture 106, a Faraday cup 107, a deflector 108, and an objective lens 109. The focused ion beam apparatus further includes a detector 112 that detects secondary electrons emitted from the sample 111, a gas source 113 that supplies a gas near the sample surface, and a manipulator 115 that picks up a fine sample.

  Ions from the liquid metal ion source emitter 100 are extracted by the extraction electrode 101 and focused on the sample 111 by the condenser lens 102 and the objective lens 109. In the blanking operation by the blanker 105, the ion beam enters the Faraday cup 107.

  The focused ion beam apparatus of this example is equipped with a deposition gas source 113 and a manipulator 115, and a fine sample piece can be extracted from a local region of the sample by a microsampling method.

  An example of the control apparatus 20 of the focused ion beam apparatus of the present invention will be described with reference to FIG. The control device 20 includes a high-voltage power supply 203, an aperture control power supply 204, an aligner / stigma control power supply 205, a beam current measuring amplifier 206, a blanking control power supply 207, a deflection amplifier 208, a preamplifier 209, a stage control power supply 210, a scanner 211, and an image memory. 212, an exhaust control power supply 213, a gas control power supply 214, and a manipulator control power supply 215. Each control power source is centrally controlled by the computer 201 via the control bus 202.

  The high voltage power source 203 applies a high voltage to the ion source emitter 100, the extraction electrode 101, the condenser lens 102, and the objective lens 109. The aperture control power source 204 controls the variable aperture 103 and selects a desired aperture diameter. A small-diameter aperture is selected for image observation, and a large-diameter aperture is selected for large-area machining. The aligner / stigma control power supply 205 controls the eight-pole electrode voltage of the aligner / stigma 104 to perform electrical axis alignment and astigmatism correction. The beam current measuring amplifier 206 measures the beam current flowing into the Faraday cup 107 during blanking. A blanking control power source 207 drives the blanking electrode of the blanker 105 to perform beam blanking.

  The deflection amplifier 208 inputs a scanning signal from the scanner 211 and drives the deflector 108 which is an 8-pole 2-stage electrostatic deflector. The preamplifier 209 converts the signal from the detector 112 into a luminance voltage signal, converts it into a digital value, and writes it into the image memory 212. The image stored in the image memory 212 is displayed on the display device 36.

  The gas control power source 214 performs temperature control of the gas source 113 and valve opening / closing control. The manipulator control power source controls fine movement of the manipulator 115 and detects contact with the sample.

  FIG. 4 is a diagram for explaining a part of the deflection control system and the image generation system of the control device 20 in the first example of the focused ion beam apparatus of the present invention. The scanner 211 includes counters 41 and 42 and DA converters 43 and 44 for 9-bit beam scanning in the X direction and the Y direction. The digital scanning signals xd and yd from the counters 41 and 42 are converted into analog scanning signals xa and ya by DA converters 43 and 44 and output to the deflection amplifier 208.

  The preamplifier 209 has an AD converter 45 that AD converts the analog secondary electron signal from the detector 112. The digital secondary electron signal from the AD converter 45 is stored in the image memory 212 together with the digital scanning signals xd and yd from the counters 41 and 42. A microscope image of the sample is formed in the image memory 212 by synchronizing the writing of the image and the scan. Thus, an image of 512 × 512 pixels is stored in the image memory 212.

  A first example of the focused ion beam apparatus of the present invention will be described with reference to FIG. FIG. 5 shows an example of the screen of the display device 36. The screen 500 includes an image display area 511, a vertical slide bar 512, and a horizontal slide bar 513. The image display area 511 displays the sample image as an image of 512 × 512 pixels. The vertical slide bar 512 and the horizontal slide bar 513 are used to move the image displayed in the image display area 511. The length of the black indicator included in the vertical slide bar 512 and the horizontal slide bar 513 represents the zoom rate. The position of the indicator indicates in which position of the entire image the area displayed in the image display area 511 is located. When the zoom factor is 1, the black indicator extends over the entire area of each slide bar. Therefore, when the zoom factor is 1, the entire sample image is displayed in the image display area 511, and this image cannot be moved by the vertical slide bar 512 and the horizontal slide bar 513.

  The screen 500 further includes an image acquisition button 514 and a zoom rate setting button 515. The image acquisition button 514 is provided to scan a beam at the current zoom rate and shift position and newly acquire a sample image. The image acquisition button 514 will be described later in a second example of the present invention. The zoom rate setting button 515 is used for setting the zoom rate. In this example, the zoom ratio is 1 to 8 times.

  According to this example, pixel interpolation is performed simultaneously with the zoom rate change. On the initial screen, an image with a zoom factor of 1 is displayed in the image display area 511. As shown in the figure, when the user changes the zoom ratio from 1 to 4, a part of the image magnified four times is displayed in the image display area 511. An image with a zoom factor of 4 results in a coarse image, but in this example, a clear image is obtained because the interpolated pixels are embedded in the area between the pixels. When a part 516 of the image display area 511 is enlarged and drawn, it can be seen that interpolation data pixels are arranged between actual data pixels. The pitch of pixels to be interpolated corresponds to the zoom rate. For example, when the zoom rate is 4, interpolation pixels are inserted at a 4-pixel pitch. Thereby, a smoother image can be obtained as compared with the case where pixel interpolation is not performed. As a pixel interpolation method in this example, for example, a process (bilinear method) using a two-dimensional average value as interpolation information may be used.

  In the image display area 511, an image of the sample enlarged by 4 times and subjected to pixel interpolation in terms of software is displayed. The sample processing object 520 is clearly displayed, and the user can set the processing frame 521 accurately. If the object to be processed 520 is not displayed in the image display area 511, the object to be processed 520 is displayed in the image display area 511 by moving the field of view with the vertical slide bar 512 and the horizontal slide bar 513. Can be made. According to this example, in order to clearly display the workpiece 520, accurate machining positioning can be performed with an irradiation amount 1/16 of the normal beam irradiation amount. In this way, damage to the sample can be reduced.

  A second example of the focused ion beam apparatus of the present invention will be described with reference to FIG. FIG. 6 shows an example of the screen of the display device 36. The screen 500 includes an image display area 511, a vertical slide bar 512, a horizontal slide bar 513, an image acquisition button 514, and a zoom rate setting button 515. In this example, the zoom rate can be 1 ×, 2 ×, 4 ×, 8 ×, 16 ×, and 32 ×.

  In the first example of the present invention described with reference to FIG. 5, zooming is performed and image definition is ensured by pixel interpolation. However, the sharpness of the image can be ensured by pixel interpolation only when the zoom rate is about 8 times (4 to 8 times). When the zoom ratio exceeds 8 times, a clear and accurate image cannot be obtained even if pixel interpolation is performed. Therefore, in this example, a method for re-acquiring an image after zooming is used in combination to ensure a wide zoom rate setting range and improve the accuracy of processing positioning. In order to realize this, the beam deflection point resolution must be at least larger than the display resolution. In this example, the display resolution is 512 × 512 pixels, but the zoom deflection point resolution is 4096 × 4096 points.

  Here, a case where an image with a zoom factor of 32 is obtained will be described as an example. First, an image is acquired at a zoom ratio of 8 times. Next, this image is subjected to pixel interpolation and enlarged four times. Thus, a zoom image of 32 times can be obtained by zooming 8 times and 4 times.

  On the initial screen, an image with a zoom factor of 1 is displayed in the image display area 511. When the zoom factor is 1, 4096 × 4096 beam deflection points are thinned out to 1/8 by the beam deflection function to obtain an image of 512 × 512 pixels. Next, when the zoom rate is changed from 1 to 8, an image enlarged by 8 times by pixel interpolation is displayed in the image display area 511.

  Next, the image acquisition button 514 is pressed. Thereby, a new image is obtained at the current zoom rate and shift position. A new original image of 512 × 512 points is acquired with the current zoom ratio of 8 times.

  FIG. 6A shows an image after the image acquisition button is pressed in a state where the zoom rate is 8 times. When a part 611 of the image display area 511 is enlarged and drawn, it can be seen that the image display area 511 is composed of only actual data pixels. However, in the image display area 511, only a part of the scanning ion microscope image with 4096 × 4096 beam deflection points is displayed. In order to display other portions of the scanning ion microscope image, the image may be shifted using the vertical slide bar 512 and the horizontal slide bar 513.

  FIG. 6B shows an image when the zoom factor is set to 32 times by the zoom factor setting button 515. The image displayed in the image display area 511 is an image obtained by enlarging an original image acquired at a zoom rate of 8 times by a factor of 4 by pixel interpolation. When a part 612 of the image display area 511 is enlarged and drawn, it can be seen that interpolation data pixels are arranged between actual data pixels. In this state, a one-to-one relationship is not established between the beam deflection point and the image pixel of the image image display area 511. In the image display area 511, only a part of the scanning ion microscope image magnified 32 times is displayed. In order to display other portions of the scanning ion microscope image, the image may be shifted using the vertical slide bar 512 and the horizontal slide bar 513. With this function, it is possible to observe a wide area of the sample with high resolution without moving the sample stage.

  In this way, in this example, high-precision machining positioning can be performed with the zoom ratio being 32 times.

  It is convenient to be able to distinguish whether there is a one-to-one relationship between the beam deflection point and the image pixels in the image display area 511. Therefore, in this example, when the zoom rate is 1, 2, 4 or 8 times, the display color of the zoom rate is blue. When the zoom rate is 16 or 32 times, the display color is red. The state of the zoom function is now understood.

  Processing in the second example of the focused ion beam apparatus of the present invention will be described with reference to FIG. In step S <b> 101, the image generation unit 30 of the focused ion beam apparatus generates an initial screen and displays it on the screen of the display device 36. On the initial screen, an image with a zoom factor of 1 is displayed. In step S102, the image generation unit 30 determines whether or not the zoom rate input by the user is 8 times or less.

  In step S102, when the zoom rate is 8 times or less, the process proceeds to step S103, and pixel interpolation is performed. In step S102, if the zoom rate is not 8 times or less, the process proceeds to step S104, and the image is re-acquired once in a state where the zoom rate is 8 times, and then the process proceeds to step S103 to perform pixel interpolation. . An image is displayed in step S105 after pixel interpolation.

  FIG. 8 is a diagram showing an example of the deflection control system and the image generation system of the control device 20 in the second example of the focused ion beam apparatus of the present invention. The scanner 211 includes counters 61 and 62 for 12-bit beam scanning in the X and Y directions, barrel shifters 63 and 64, shift registers 65 and 66, adders 67 and 68, and DA converters 69 and 70.

  The counters 61 and 62 operate in a 12-bit mode when acquiring a high-definition image or processing a sample, and operate in a 9-bit mode when acquiring an image by pressing the image acquisition button 514. FIG. 8 shows the number of bits in the 9-bit mode. The shift bits of the barrel shifters 63 and 64 correspond to the zoom rate. The values in the registers 65 and 66 correspond to the movement amounts by the vertical slide bar 512 and the horizontal slide bar 513. Image shift is realized by the registers 65 and 66 without moving the sample stage.

  Digital scanning signals xd and yd from the counters 61 and 62 are shifted by the barrel shifters 63 and 64 and sent to the adder 67. The adder 67 adds the signals from the barrel shifters 63 and 64 and the signals from the shift registers 65 and 66 and sends them to the DA converters 69 and 70. The DA converters 69 and 70 convert the added signals into analog scanning signals xa and ya and output them to the deflection amplifier 208.

  The preamplifier 209 includes an AD converter 71 that AD converts an analog secondary electron signal from the detector 112. The digital secondary electron signal from the AD converter 71 is stored in the image memory 212 together with the digital scanning signals xd and yd from the counters 61 and 62. A microscope image of the sample is formed in the image memory 212 by synchronizing the writing of the image and the scan. Thus, an image of 512 × 512 pixels is stored in the image memory 212.

  According to the present invention, when an image of a sample is obtained for processing positioning, sample damage is minimized, and processing positioning accuracy is further increased. Therefore, even when a small sample fragment is obtained by microsampling, the surface of the sample is less damaged and the target site can be extracted more accurately.

  In particular, when repeating patterns (cells) of a semiconductor memory are counted (cell count), pixel interpolation makes it easy to determine cell boundaries, and a large number of cells can be counted at one time. In addition, when used together with a CAD navigation system, an effect of reducing sample damage during alignment work or location search can be expected.

  According to the present invention, accurate processing positioning can be performed with little sample damage. Further, even if a rough image is acquired, accurate processing position alignment is possible, so that it is possible to save image acquisition time.

  The example of the present invention has been described above, but the present invention is not limited to the above-described example, and various modifications can be made by those skilled in the art within the scope of the invention described in the claims. It will be understood.

It is a figure which shows the outline of a structure of the focused ion beam apparatus of this invention. It is detail drawing of the FIB column of the focused ion beam apparatus of this invention. It is a block diagram of the control apparatus of the focused ion beam apparatus of this invention. It is a figure explaining a part of deflection control system and image generation system of the control apparatus in the 1st example of the focused ion beam apparatus of the present invention. It is a figure which shows the example of the screen of the display apparatus in the 1st example of the focused ion beam apparatus of this invention. It is a figure which shows the example of the screen of the display apparatus in the 2nd example of the focused ion beam apparatus of this invention. It is a figure which shows the flow of a process in the 2nd example of the focused ion beam apparatus of this invention. It is a figure which shows the example of the deflection | deviation control system and image generation system of the control apparatus in the 2nd example of the focused ion beam apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... FIB column, 20 ... Control apparatus, 30 ... Image generation part, 35 ... Input device, 36 ... Display apparatus, 100 ... Emitter, 101 ... Extraction electrode, 102 ... Condenser lens, 103 ... Variable aperture, 104 ... Aligner stigma , 105 ... Blanker, 106 ... Blanking aperture, 107 ... Faraday cup, 108 ... Deflector, 109 ... Objective lens, 111 ... Sample, 112 ... Detector, 113 ... Gas source, 115 ... Manipulator, 120 ... Ion beam, 121 ... Secondary electron, 201 ... Computer, 202 ... Control bus, 203 ... High voltage power supply, 204 ... Aperture control power supply, 205 ... Aligner / stigma control power supply, 206 ... Beam current measuring amplifier, 207 ... Blanking control power supply, 208 ... Deflection amplifier 209 ... Preamplifier 210 ... Stage Your power, 211 ... scanner, 212 ... image memory, 213 ... exhaust control power, 214 ... Gas control power, 215 ... manipulator control power

Claims (20)

An irradiation system for irradiating the sample with a focused ion beam, a deflection control system for deflecting the focused ion beam, a detector for detecting a secondary particle signal from the sample, and scanning of the sample from the signal from the detector An original image generation unit for generating an ion microscope image, a display device for displaying all or part of the generated original image, and a region for locally irradiating a focused ion beam based on the displayed microscope image are set. A processing position setting unit to perform, and an input device for inputting an instruction from the user,
A focused ion beam apparatus having a function of displaying an original image by interpolating pixels on the image display unit.   2. The focused ion beam apparatus according to claim 1, wherein the deflection control system has a beam deflection point resolution larger than the display resolution of the display device and a function of thinning and deflecting the beam deflection point, and is generated by pixel interpolation. A focused ion beam apparatus comprising a digital zoom ratio changing function in a range where a beam deflection point corresponding to a pixel exists.   2. The focused ion beam apparatus according to claim 1, wherein the deflection control system has a beam deflection point resolution larger than the display resolution of the display device and a function of thinning and deflecting the beam deflection point, and is generated by pixel interpolation. A digital zoom ratio changing function in a range where a beam deflection point corresponding to a pixel exists, and a digital zoom ratio changing function in a range where a beam deflection point corresponding to a pixel generated by pixel interpolation does not exist Focused ion beam device.   2. The focused ion beam apparatus according to claim 1, wherein the deflection control system has a beam deflection point resolution larger than the display resolution of the display device and a function of decimating and deflecting the beam deflection point, and zooming from the input device. A focused ion beam apparatus, wherein pixel interpolation processing is performed when a specified ratio value is a zoom ratio in a range where there is no beam deflection point corresponding to a pixel to be generated.   2. The focused ion beam apparatus according to claim 1, wherein the image generation unit has a digital zoom function and an image shift function, and can perform observation and designation of a processing position with high resolution over a wide range of a sample. Beam device.   2. The focused ion beam apparatus according to claim 1, wherein when the display resolution of the display device is x × y pixels, the beam deflection point resolution of the deflection control system is (4 × x) × (4 × y) points or ( 8. A focused ion beam apparatus characterized by 8 × x) × (8 × y) points.   2. The focused ion beam apparatus according to claim 1, wherein the image generation unit includes an image memory for storing a scanning ion microscope image of the sample, and the image memory is synchronized with a scanning signal from the deflection control system. A focused ion beam apparatus for writing a scanning ion microscope image of a sample.   2. The focused ion beam apparatus according to claim 1, wherein the deflection control system includes a scanner that outputs scanning signals in the X and Y directions, and a deflection amplifier that receives the scanning signals from the scanner and generates a signal for driving the deflector. And a focused ion beam device.   2. The focused ion beam apparatus according to claim 1, wherein the display device includes an image display region for displaying the original image or the zoom image and a region for displaying a set zoom rate, and the zoom rate is generated by pixel interpolation. Focused ions characterized in that zoom ratios are displayed in different colors in a range where a beam deflection point corresponding to a pixel exists and a range where a beam deflection point corresponding to a pixel generated by pixel interpolation does not exist Beam device.   2. The focused ion beam apparatus according to claim 1, wherein a screen displayed by the display device has an image acquisition button, and when the image acquisition button is pressed, a beam at a display image resolution at a set zoom rate. A focused ion beam apparatus characterized in that an image is re-acquired by deflection and the image is displayed.   2. The focused ion beam apparatus according to claim 1, wherein a screen displayed by the display device includes a vertical slide bar for moving the image displayed in the image display area in the vertical direction and a horizontal slide for moving in the horizontal direction. It has a slide bar, and the zoom rate is reflected in the length of the slide bar, and the position of the slide bar indicates in which position of the entire image the area displayed in the image display area is Focused ion beam device.   2. The focused ion beam apparatus according to claim 1, wherein a deposition gas source and a manipulator are provided, and a fine sample piece can be extracted from a local region of the sample by a microsampling method. A focused ion beam device.   Irradiating the sample with a focused ion beam, deflecting the focused ion beam, detecting a secondary particle signal from the sample, and scanning ion microscope image of the sample from the signal from the detector Generating, displaying all or part of the generated original image, displaying the original image with pixel interpolation on the image display unit, and focusing ions based on the displayed microscopic image A region for locally irradiating the beam, and a processing position setting method for the focused ion beam apparatus. The processing position setting method of the focused ion beam apparatus according to claim 13,
The focused ion beam apparatus is configured such that the beam deflection point is thinned and deflected, a pixel corresponding to a part or all of the deflection point thinned out by pixel interpolation is generated, and the beam deflection point corresponding to the generated pixel exists. Machining position setting method. The processing position setting method of the focused ion beam apparatus according to claim 13,
Digital zoom ratio change in a range where a beam deflection point corresponding to a pixel generated by pixel interpolation exists, and digital zoom ratio change in a range where a beam deflection point corresponding to a pixel generated by pixel interpolation does not exist A method for setting a processing position of a focused ion beam device, which is selectively used depending on circumstances. The processing position setting method of the focused ion beam apparatus according to claim 13,
A processing position setting method for a focused ion beam apparatus, wherein pixel interpolation processing is performed when a specified zoom ratio is a zoom ratio in a range where there is no beam deflection point corresponding to a pixel to be generated. The processing position setting method of the focused ion beam apparatus according to claim 13,
A processing position setting method for a focused ion beam apparatus that uses a digital zoom function and an image shift function together to acquire an image with high resolution over a wide range of a sample. The processing position setting method of the focused ion beam apparatus according to claim 13,
When the display resolution is x × y pixels, the beam deflection point resolution of the deflection control system is set to (4 × x) × (4 × y) points or (8 × x) × (8 × y) points. A processing position setting method for a focused ion beam device.   Displaying a scanning ion microscope image with a zoom factor of 1 on the screen of the display device, determining whether or not the zoom factor input by the user is equal to or less than a fixed factor, and Re-acquires an image of a certain magnification without pixel interpolation, and if the zoom factor is more than a certain factor, performs pixel interpolation and generates a scanning ion microscope image with the zoom factor specified by the user. A processing position setting method for the focused ion beam apparatus, comprising: setting a processing region based on the obtained image.   A computer-readable program for causing a computer to execute the processing position setting method for a focused ion beam apparatus according to any one of claims 13 to 19.

Images