WO2021149117A1

WO2021149117A1 - Charged particle beam image analysis device, inspection system, and program

Info

Publication number: WO2021149117A1
Application number: PCT/JP2020/001764
Authority: WO
Inventors: 信裕岡井; 山口　敦子; 直正鈴木; 堤　貴志
Original assignee: 株式会社日立ハイテク
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2021-07-29

Abstract

The present invention makes it possible to accurately measure the shape of a sample. To that end, a charged particle beam image analysis device (200) comprises an image acquisition unit (212) for acquiring a first image that is of a sample (330) having a groove formed therein, has been captured using a charged particle beam device (100) with the sample (330) in a first orientation (φ = φ0), and includes portions corresponding to a pair of bottom edges on the bottom surface of the groove, and a second image that is of the sample (330), has been captured using a charged particle beam device (100) with the sample (330) in a second orientation (φ = φ1) more inclined than the first orientation (φ = φ0), and is based on charged particles having energies greater than or equal to a prescribed energy, and a depth calculation unit (220) for calculating the depth of the groove on the basis of the first image and second image.

Description

Charged particle beam image analyzers, inspection systems and programs

The present invention relates to an analyzer for charged particle beam images, an inspection system, and a program.

As a background technology in this technical field, the following Patent Document 1 describes a manufacturing process of a MOS gate power device having a trench MOS gate structure. Further, in Non-Patent Document 1 below, an atomic force microscope (AFM; Atomic Force Microscope) is described in order to evaluate the recess amount, which is a shape index that affects the characteristics of the device, in the inspection process in the middle of the manufacturing process of the trench MOSFET device. ) Is used.

Japanese Unexamined Patent Publication No. 2007-49204

However, with conventionally known techniques, it has been difficult to accurately measure the recess amount with high throughput in shape measurement in the inspection process of a trench MOSFET device.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an analyzer, an inspection system, and a program for a charged particle beam image capable of accurately measuring the shape of a sample.

In order to solve the above problems, the charged particle beam image analyzer of the present invention is an image of a grooved sample taken by the charged particle beam device in the first posture, and is formed on a pair of bottom edges on the bottom surface of the groove. A first image including the corresponding portion and an image of the sample taken by the charged particle beam device in a second posture tilted from the first posture and having an energy equal to or higher than a predetermined energy. An image storage unit that stores a second image based on particles, a depth calculation unit that calculates the depth of the groove based on the first image and the second image, and a depth calculation unit. It is characterized by having.

According to the present invention, the shape of the sample can be accurately measured.

It is a block diagram which shows an example of the semiconductor inspection system 1 by a preferable 1st Embodiment. It is a figure which shows an example of the manufacturing process of a sample. It is a schematic diagram which shows the measurement principle of a recess amount. It is a schematic diagram which shows the measurement principle of the bottom width. It is a schematic diagram which shows the measurement principle of the x-coordinate value of a top center point. It is a schematic diagram which shows the measurement principle of the x-coordinate value of the bottom center point at the time of inclination based on the secondary electron intensity. It is a schematic diagram which shows the measurement principle of the x-coordinate value of the bottom center point at the time of inclination based on the reflected electron intensity. It is a flowchart of the measurement processing routine executed in the analysis apparatus. It is an operation explanatory figure which the analyzer performs edge detection. It is a figure which illustrates the display screen displayed on the display. It is a figure which illustrates other display screens displayed on a display. It is a figure which illustrates other display screens displayed on a display. It is a figure which illustrates other display screens displayed on a display. It is a figure which illustrates other display screens displayed on a display. It is a schematic diagram which shows the measurement principle which measures the recess amount of a sample in a comparative example. It is a figure which shows an example of the measurement result of the interval with respect to various inclination angles. It is a schematic diagram which shows the measurement principle which measures the recess amount of another sample in a comparative example.

[First Embodiment]
<Structure of the first embodiment>
FIG. 1 is a block diagram showing an example of a semiconductor inspection system 1 (inspection system) according to a preferred first embodiment.
In FIG. 1, the semiconductor inspection system 1 includes an electron microscope 100 (charged particle beam device), an analyzer 200 (charged particle beam image analyzer, computer), a display 260, and an input device 262. .. In the illustrated example, the electron microscope 100 is a SEM (Scanning Electron Microscope).

(Electron microscope 100)
The electron microscope 100 includes an electric field emitting cathode 101, an extraction electrode 102, an anode 104, a focusing lens 105, a focusing unit 106 for a primary electron beam, an adjustment knob 107, an upper scanning deflector 108, and a lower scanning deflector. 109,

electron detectors

110, 124, Wien filter 114, pull-up electrode 115, objective lens 118, electric field correction electrode 119, stage 121, electron gun control device 141, focusing lens control device 142. , Scan deflector control device 143, Wien filter control device 144, pull-up electrode control device 145, objective lens control device 146, electric field correction electrode control device 147, stage control device 148, control device 150, and the like. It includes a storage device 152, a control table 154, a display 156, an input device 158, and an image memory 160.

In the electron microscope 100, electrons are emitted by applying an extraction voltage between the field emission cathode 101 and the extraction electrode 102. The emitted electrons are further accelerated between the extraction electrode 102 and the anode 104 at ground potential with respect to the extraction electrode 102. The emitted electrons are referred to as a primary electron beam B1 (charged particle beam). The energy of the primary electron beam B1 that has passed through the anode 104 coincides with the acceleration voltage of the electron gun (including the field emission cathode 101 and the extraction electrode 102). The energy of the primary electron beam B1 may be, for example, about 200 eV to 50 keV. The primary electron beam B1 that has passed through the anode 104 is focused by the focusing lens 105. Then, the primary electron beam B1 is subjected to scanning deflection by the upper scanning deflector 108 and the lower scanning deflector 109, and then is finely focused on the sample 330 by the objective lens 118.

The storage device 152 stores a control table 154 that defines control conditions such as voltage and current of each part of the electron microscope 100. The control device 150 reads out the control table 154 and controls the electron microscope 100 via the devices 141 to 148 according to the control conditions specified here. The user can input the measurement conditions via the input device 158. When the user inputs the measurement conditions, the control device 150 reads out the control table 154 stored in the storage device 152 and sets the control parameters.

The objective lens 118 includes a magnetic pole 116 and an objective lens coil 117. The objective lens 118 converges the primary electron beam B1 by leaking the magnetic field generated by the objective lens coil 117 from the gap of the magnetic pole 116 and concentrating it on the optical axis. The strength of the objective lens 118 is adjusted by changing the amount of current of the objective lens coil 117. Here, a negative voltage is applied to the stage 121. The primary electron beam B1 that has passed through the objective lens 118 is decelerated by the deceleration electric field generated between the objective lens 118 and the sample 330, and reaches the sample 330.

The opening angle of the primary electron beam B1 in the objective lens 118 is determined by the primary electron beam diaphragm portion 106 installed below the focusing lens 105. The user can adjust the centering of the primary electron beam diaphragm unit 106 with the adjustment knob 107. The primary electron beam B1 finely focused by the objective lens 118 is scanned on the sample 330 by the upper scanning deflector 108 and the lower scanning deflector 109. At this time, the deflection directions and intensities of the upper scanning deflector 108 and the lower scanning deflector 109 are adjusted so that the scanned primary electron beam B1 always passes through the center of the objective lens 118.

When the primary electron beam B1 irradiates the sample 330, secondary electrons C (charged particles) and backscattered electrons D (charged particles) are generated. The secondary electron C is, for example, an electron having an energy of less than 50 eV, and the backscattered electron D is, for example, an electron having an energy of 50 eV or more. The reflected electrons D have a distribution centered on the specular reflection direction with respect to the primary electron beam B1. Since the reflected electrons D have high energy, they reach the electron detector 124 for reflected electrons with almost no influence of the electric field generated between the objective lens 118 and the sample 330. The control device 150 constitutes the reflected electron image GD by using the intensity of the reflected electron D that has reached the electron detector 124 as a luminance modulation input signal. The reflected electron image GD is displayed on the display 156 and is also stored in the image memory 160.

On the other hand, the electric field generated between the objective lens 118 and the sample 330 acts as an accelerating electric field for the secondary electrons C. Since the secondary electrons C have low energy, they are attracted into the passage of the objective lens 118. Then, the secondary electrons C rise inside the objective lens 118 while being affected by the lens action by the accelerating electric field formed between the sample 330 and the magnetic pole 116 and the magnetic field of the objective lens 118.

Here, when a high voltage is applied to the magnetic pole 116 and the accelerating electric field becomes stronger, more secondary electrons C can be pulled up. The pull-up electrode 115 is arranged on the optical axis side with respect to the objective lens 118. A voltage higher than that of the magnetic pole 116 is applied to the pull-up electrode 115, whereby the secondary electrons C are pulled further upward. Further, an electrostatic lens is formed by the potential difference generated between the pull-up electrode 115 and the magnetic pole 116, and the secondary electrons C are subjected to a converging action by this electrostatic lens. As a result, it is possible to reduce the components of the secondary electrons C that collide with the inner wall of the pull-up electrode 115.

The accelerated and pulled secondary electron C is deflected off-axis by the Wien filter 114. Then, the secondary electrons C are detected by the electron detector 110 for the secondary electrons. The Vienna filter 114 in the illustrated example is referred to as an "ExB filter" and includes two

electrodes

131 and 132 and a coil 133. The electrode 132 arranged on the electron detector 110 side is formed in a mesh shape so that the secondary electrons C can pass through. When a voltage higher than that of the electrode 131 is applied to the electrode 132, an electric field 134 from the electrode 132 to the electrode 131 is generated.

Further, the coil 133 generates a magnetic field 135 in a direction orthogonal to the electric field 134. Both the electric field 134 and the magnetic field 135 have an action of deflecting the primary electron beam B1. Therefore, the Wien filter control device 144 adjusts the current supplied to the coil 133 and the voltage between the

electrodes

131 and 132 in order to cancel the two. That is, in the Wien filter control device 144, the direction in which the primary electron beam B1 is deflected by the electric field 134 and the direction in which the primary electron beam B1 is deflected by the magnetic field 135 are opposite to each other, and the absolute values of the deflection amounts of both are opposite. The Wien filter 114 is controlled to be equal. As a result, the Vienna filter 114 does not affect the orbit of the primary electron beam B1.

On the other hand, since the secondary electrons C travel in the opposite direction to the primary electron beam B1, the electric field 134 and the magnetic field 135 act to deflect the secondary electrons C in the same direction. As a result, the secondary electrons C deflected from the optical axis of the primary electron beam B1 pass through the electrode 132 and reach the detector 110. The control device 150 constitutes the secondary electron image GC by using the intensity of the secondary electrons C reaching the electron detector 110 as a luminance modulation input signal. The secondary electronic image GC is displayed on the display 156 and is also stored in the image memory 160. Hereinafter, the secondary electron image GC and the backscattered electron image GD may be collectively referred to as “electron image G (image)”.

Sample 330 is placed on the stage 121. The stage control device 148 controls the position and orientation of the sample 330 by driving the stage 121. That is, the stage control device 148 has a function of moving the sample 330 in the horizontal and vertical directions and a function of tilting and rotating the sample 330. The tilt angle of the stage 121, that is, the tilt angle of the sample 330 is called φ. When the sample 330 is not tilted, that is, when the tilt angle φ = 0 °, the electric field between the magnetic pole 116 and the sample 330 is axisymmetric, so that the primary electron beam B1 is not deflected and is vertically oriented to the sample 330. Is irradiated to. The secondary electrons C are efficiently guided above the objective lens 118 without being deflected by the action of this electric field and the action of the magnetic field of the objective lens 118.

On the other hand, when the sample 330 is tilted, the electric field between the magnetic pole 116 and the sample 330 is tilted, so that the secondary electrons C are deflected in a direction orthogonal to the optical axis. As a result, the secondary electrons C generated from the sample 330 often collide with the inner wall while passing through the objective lens 118 and the pull-up electrode 115, and the number of secondary electrons C that can reach the detector 110 decreases. .. Further, this asymmetric electric field causes aberration to occur, which causes a decrease in the resolution of the primary electron beam B1.

Therefore, in order to suppress the inclination of the electric field when the sample 330 is inclined, the electric field correction electrode 119 formed symmetrically is provided. Then, the electric field correction electrode control device 147 applies a negative voltage of an appropriate magnitude to the electric field correction electrode 119 in order to suppress the inclination of the electric field between the objective lens 118 and the sample 330. The deflection action of the primary electron beam B1 and the secondary electron C generated when the sample 330 is tilted depends on the voltage applied to the magnetic pole 116 and the stage 121 and the tilt angle. Therefore, the control device 150 sets the control conditions stored in the control table 154 to each part via the devices 141 to 148 of the electron microscope 100, thereby suppressing the deflection action of the primary electron beam B1 and the secondary electron C. do.

(Analyzer 200)
The analyzer 200 is equipped with hardware as a general computer such as a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an SSD (Solid State Drive). , OS (Operating System), application programs, various data, etc. are stored. The OS and application programs are expanded in RAM and executed by the CPU. In FIG. 1, the inside of the analysis device 200 shows a function realized by an application program or the like as a block.

That is, the analysis device 200 includes an image storage unit 210 (image storage means), an image acquisition unit 212 (depth calculation means), a UI control unit 214, and a depth calculation unit 220. The image storage unit 210 stores an electronic image G, an image to be displayed on the display 260, and the like. The image acquisition unit 212 acquires the electronic image G from the image memory 160 of the electron microscope 100 and stores it in the image storage unit 210.

The UI control unit 214 outputs the display image stored in the image storage unit 210 to the display 260, and receives input information from the input device 262 (for example, a keyboard, a mouse, etc.). By the way, a groove called a trench 312 (see S6 in FIG. 2) is formed in the sample 330, and the depth of the trench 312 (groove) is called a recess amount H. In FIG. 1, the depth calculation unit 220 calculates the recess amount H. The depth calculation unit 220 includes a bottom width calculation unit 222, a top edge position detection unit 224, a top center position calculation unit 226, a bottom edge position detection unit 228, a bottom center position calculation unit 230, and a depth. It is provided with a calculation unit 232. Details of each element in the depth calculation unit 220 will be described later together with the operation.

<Manufacturing process of sample 330>
FIG. 2 is a diagram showing an example of the manufacturing process of the sample 330 shown in FIG. In the example of FIG. 2, the sample 330 is a semiconductor device having a trench MOS gate structure.
In step S1 of the illustration, a hard mask 320 is formed on the surface of the single crystal silicon substrate 310 by using a lithography process. Next, in step S2, the substrate 310 is etched. Then, a trench 312, which is a groove-shaped recess, is formed on the upper surface of the substrate 310. After forming the trench 312, the hard mask 320 is removed.

Next, in step S3, a rounding process is performed on the trench 312. That is, the vicinity of the top edge of the trench 312 is chamfered by heat treatment or the like. Next, in step S4, an oxide film 314 of _{SiO 2 is formed on the surface of the substrate 310.} Next, in step S5, the gate electrode material 316 (for example, polysilicon containing high concentration phosphorus) is embedded in the trench 312.

Next, in step S6, the gate electrode material 316 is etched to a position lower than the height of the upper surface of the oxide film 314. The difference between the height of the upper surface of the oxide film 314 and the height of the gate electrode material 316 is referred to as "recess amount H". Then, in the present embodiment, the recess amount H is measured by the electron microscope 100 using the structure in step S6 as the sample 330.

<Measurement principle of recess amount H>
FIG. 3 is a schematic diagram showing the measurement principle of the recess amount H.
The surface 340 shown by the solid line is the surface of the sample 330 when the sample 330 is not tilted, that is, when the tilt angle φ is 0 °. The points where the surface 340 becomes horizontal near both ends of the trench 312 when not inclined are called top edges PT1 and PT2, and the intermediate point between the two is called the top center point P1. Further, both ends of the bottom surface 346 of the trench 312 are referred to as bottom edges PB1 and PB2, and the intermediate point between the two is referred to as a bottom center point P2. Further, the width of the bottom surface 346 is referred to as a bottom width Lb. Further, the x-axis, y-axis, and z-axis directions are defined as shown in the figure.

Since the trench 312 can be considered to be symmetrical, the recess amount H, which is the depth of the trench 312, is equal to the distance between the top center point P1 and the bottom center point P2. The surface 360 indicated by the alternate long and short dash line is the surface of the sample 330 when the inclination angle φ of the sample 330 is φ1 larger than 0 °.

However, the top center point of the surface 360 shall be equal to the top center point P1 of the surface 340. Let P3 be the bottom center point when the inclination angle φ = φ1. Here, let Δx be the difference value between the x-coordinate value of the top center point P1 and the x-coordinate value of the bottom center point P3 at the time of inclination. Then, the difference value Δx = Hsinφ1 is established with respect to the recess amount H. Since the inclination angle φ1 is known, the recess amount H can be obtained by H = Δx / sinφ1 when the difference value Δx is measured.

FIG. 4 is a schematic view showing the measurement principle of the bottom width Lb.
In the following description, the reference numerals starting with "GC" such as "GC2" are a part of the secondary electron image GC. Further, a code starting with "GD" such as "GD2" is a part of the reflected electron image GD. Both the secondary electron image and the backscattered electron image are two-dimensional images, and the result of integrating the pixel values along the y-axis (see FIG. 3) is called the secondary electron intensity and the backscattered electron intensity.

In FIG. 4, the secondary electron intensity IC2 and the backscattered electron intensity ID2 are attached to the secondary electron image GC2 (first image) and the backscattered electron image GD2 (first image) acquired by setting the inclination angle φ to φ0. This is an example of the underlying strength. Here, φ0 is, for example, “0 °”. The x-coordinate values x1 and x4 are the x-coordinate values of the top edges PT1 and PT2, and the x-coordinate values x2 and x3 (first bottom edge positions) are the x-coordinate values of the bottom edges PB1 and PB2. In both the secondary electron intensity IC2 and the backscattered electron intensity ID2, remarkable edges appear at the x-coordinate values x2 and x3. Therefore, the x-coordinate values x2 and x3 can be specified from the secondary electron intensity IC2 or the backscattered electron intensity ID2 by using a well-known edge detection algorithm.

Then, the bottom width Lb can be obtained as the difference between the x coordinate values x2 and x3. In the regions of x <x1 and x4 <x, the surface of the sample 330 is flat, whereas the secondary electron intensity IC2 is not flat but slightly inclined. The reason is that when the oxide film 314 covering the surface of the sample 330 is an insulator and is charged by the primary electron beam B1 (see FIG. 1), the secondary electrons are deflected by the charging and the number of electrons reaching the detector changes. To do. The secondary electron intensity IC2 in the interval of x <x1 and x4 <x changes depending on the environmental conditions and measurement conditions at that time.

On the other hand, the reflected electron intensity ID2 in the section of x <x1 and x4 <x is almost constant. The reason is that the reflected electrons have high energy and are hardly subjected to the deflection action due to the charging of the oxide film 314. As described above, if the edge of the secondary electron intensity IC2 or the backscattered electron intensity ID2 can be detected at the x coordinate values x2 and x3, the bottom width Lb can be measured. Therefore, the inclination angle φ0 is not limited to “0 °” as long as these edges can be detected.

FIG. 5 is a schematic diagram showing the measurement principle of the x-coordinate value P1 (x) of the top center point P1.
In FIG. 5, the reflected electron intensity ID 4 is an example of the intensity based on the reflected electron image GD4 (second image) acquired by setting the inclination angle φ to φ1 (however, φ1> φ0). The x-coordinate values x11 and x14 (top edge positions) are the x-coordinate values of the top edges PT1 and PT2. As described above, since the reflected electrons have high energy, if the sample 330 is flat in the section of x <x11, x14 <x, the reflected electron intensity ID4 has a substantially constant value ID40 regardless of the charged state of the oxide film 314. Is equal to.

On the other hand, in the range of x11 <x <x14, the tilt angle of the surface of the sample 330 is different from the tilt angle φ1, so that the backscattered electron intensity ID4 deviates from the constant value ID40. Therefore, the x-coordinate values x11 and x14 can be specified by using a well-known edge detection algorithm. The x-coordinate value P1 (x) of the top center point P1 can be obtained as the average value of the x-coordinate values x11 and x14.

FIG. 6 is a schematic diagram showing the measurement principle of the x-coordinate value P3 (x) of the bottom center point P3 at the time of inclination based on the secondary electron intensity.
In FIG. 6, the secondary electron intensity IC 5 is an example of the intensity based on the secondary electron image GC5 (third image) acquired by setting the inclination angle φ to φ1 as in FIG. 5 described above. The x-coordinate value x13 (second bottom edge position) is the x-coordinate value of the bottom edge PB2. On the left side of the bottom edge PB2, the surface of the sample 330 is a gate electrode material 316 which is a conductor. Further, on the right side of the bottom edge PB2, the surface of the sample 330 is an oxide film 314 which is an insulator. As a result, at the x-coordinate value x13, a clear edge appears in the secondary electron intensity IC5, and the x-coordinate value x13 can be specified.

Then, when the bottom width Lb (see FIG. 4) is obtained as described above, the x-coordinate value P3 (x) of the bottom center point P3 at the time of inclination sets the distance Lx = (Lb · cos φ1) / 2 from the x-coordinate value x13. It can be obtained as a subtracted value. Then, when the x-coordinate value P1 (x) (see FIG. 5) of the top center point P1 is obtained as described above, the difference between the x-coordinate value P1 (x) and the x-coordinate value P3 (x) is the difference value Δx ( (See FIG. 3), and the recess amount H can be calculated by H = Δx / sinφ1.

FIG. 7 is a schematic diagram showing another measurement principle of the x-coordinate value P3 (x) of the bottom center point P3 at the time of inclination based on the intensity of backscattered electrons.
In FIG. 7, the reflected electron intensity ID 6 is an example of the intensity based on the reflected electron image GD6 (second image) acquired by setting the inclination angle φ to φ1 as in FIG. 5 described above. The x-coordinate value x13 is the x-coordinate value of the bottom edge PB2, and the x-coordinate value x14 is the x-coordinate value of the top edge PT2. In the example of FIG. 7, the inclination angle of the surface of the sample 330 is changed at the bottom edge PB2. Then, this change in the inclination angle appears as an edge at the x-coordinate value x13 of the reflected electron intensity ID6. Therefore, the x-coordinate value x13 can be specified by using a well-known edge detection algorithm.

Further, as in the case of FIG. 5, in the range of x11 <x <x14, the reflected electron intensity ID6 deviates from the constant value ID60, so that the x-coordinate values x11 and x14 can also be detected. Whether or not the edge of the x-coordinate value x13 appears in the reflected electron intensity ID 6 depends on the shape of the sample 330, the position of the electron detector 124 (see FIG. 1), and the inclination angle φ1. Then, as shown in the figure, when the x-coordinate values x11, x13, and x14 can be detected based on the backscattered electron intensity ID6, the recess amount is determined by the backscattered electron intensity ID2 (see FIG. 4) and ID6 without using the secondary electron image. H can be calculated.

<Operation of the first embodiment>
(Outline of operation)
FIG. 8 is a flowchart of a measurement processing routine executed by the analysis device 200.
Before this routine is executed, it is assumed that various electronic images G acquired at tilt angles φ = φ0 and φ1 are stored in the image memory 160 (see FIG. 1) of the electron microscope 100.
When the process proceeds to step S22 in FIG. 8, the image acquisition unit 212 (see FIG. 1) acquires an electronic image G for calculating the bottom width Lb (see FIG. 4) from the image memory 160, and the analysis device 200 It is stored in the image storage unit 210 inside. This electronic image G is an image at an inclination angle of φ = φ0, and is, for example, the secondary electron image GC2 or the backscattered electron image GD2 shown in FIG.

Next, when the process proceeds to step S24, the bottom width calculation unit 222 (see FIG. 1) calculates the bottom width Lb (see FIG. 4) based on the image acquired in step S22. That is, the bottom width calculation unit 222 calculates the bottom width Lb based on the x-coordinate values x2 and x3 of the bottom edges PB1 and PB2 shown in FIG. Next, when the process proceeds to step S26, the image acquisition unit 212 acquires an electronic image G for detecting the x-coordinate value P1 (x) of the top center point P1 (see FIG. 5) from the image memory 160. , Stored in the image storage unit 210 in the analyzer 200. This electronic image G is an image at an inclination angle φ = φ1, and is, for example, the reflected electronic images GD4 and GD6 shown in FIGS. 5 and 7.

Next, when the process proceeds to step S28, the top edge position detection unit 224 and the top center position calculation unit 226 (see FIG. 1) increase the x-coordinate value P1 of the top center point P1 based on the image acquired in step S26. (X) (see FIG. 5) is calculated. More specifically, the top edge position detection unit 224 detects the x-coordinate values x11 and x14 of the top edges PT1 and PT2 based on the electronic image G, and calculates the average value of these values to calculate the top center point P1. The x-coordinate value P1 (x) of is calculated.

Next, when the process proceeds to step S30, the image acquisition unit 212 generates an electronic image G for detecting the x-coordinate value P3 (x) of the bottom center point P3 (see FIG. 6) when tilted from the image memory 160. It is acquired and stored in the image storage unit 210 in the analyzer 200. The electron image G is an image at an inclination angle of φ = φ1, and is, for example, a secondary electron image GC5 (see FIG. 6) or a backscattered electron image GD6 (see FIG. 7). However, the image previously acquired in step S26 may be applicable to the detection of the x-coordinate value P3 (x) as in the reflected electron image GD6 (see FIG. 7). In such a case, in step S30, the image acquired in step S26 may be diverted.

Next, when the process proceeds to step S32, the bottom edge position detection unit 228 and the bottom center position calculation unit 230 use the x-coordinate value P3 (x) of the tilted bottom center point P3 based on the image acquired in step S30. (See FIG. 6) is calculated. More specifically, the bottom edge position detection unit 228 detects the x-coordinate value x13 of the bottom edge PB2 based on the electronic image G (for example, GC5 in FIG. 6 or GD6 in FIG. 7). Next, the bottom center position calculation unit 230 subtracts the distance Lx = (Lb · cos φ1) / 2 from the x-coordinate value x13 of the bottom edge PB2 to obtain the x-coordinate value P3 (x) of the bottom center point P3 at the time of inclination. calculate.

Next, when the process proceeds to step S34, the depth calculation unit 232 calculates the difference value Δx = P1 (x) −P3 (x) and calculates the recess amount H = Δx / sinφ1. This completes the processing of this routine.
In the above-described example, various electronic images G acquired at tilt angles φ = φ0 and φ1 are stored in the image memory 160 (see FIG. 1) in advance before the measurement processing routine (FIG. 8) is executed. However, it is not always necessary to store these images in advance. For example, the tilt angle φ is set to φ0, the electron microscope 100 is operated to acquire an electronic image G, then the above steps S22 and S24 are executed, and then the tilt angle φ is changed to φ1 to obtain an electron microscope. The electron image G may be acquired by operating 100, and then steps S26 to S34 described above may be executed.

(Details of edge detection)
FIG. 9 is an operation explanatory view in which the analysis device 200 (see FIG. 1) performs edge detection.
The electron images G1 to G4 shown in FIG. 9 are secondary electron image GC or backscattered electron image GD. Here, the electronic images G1 and G2 are images when the inclination angle φ (see FIG. 3) is 0 °, and the top edges PT1 and PT2 are not shown.

In the example shown in the electronic image G1, the analyzer 200 (see FIG. 1) sets one length measuring box B10 wider than the bottom width Lb. Next, the analysis device 200 adds pixel values from the minimum value to the maximum value of the y coordinate value for each x coordinate value within the range of the length measurement box B10. The result of the addition is the electron strength (secondary electron strength or backscattered electron strength). Then, the analysis device 200 detects the edge with respect to the electron intensity from the center position (not shown) in the x-axis direction of the length measuring box B10 toward the outside, thereby detecting the x-coordinate values of the bottom edges PB1 and PB2. ..

Further, in the example shown in the electronic image G2, the analysis device 200 sets two length measuring boxes B21 and B22 narrower than the bottom width Lb. Next, the analysis device 200 adds the pixel values from the minimum value to the maximum value of the y coordinate value for each x coordinate value within the range of the length measurement boxes B21 and B22 to acquire the electron strength. Next, the analysis device 200 detects the edge with respect to the electron intensity from the x-coordinate values x41 and x42 of the opposite sides of the length measuring boxes B21 and B22 toward the outside, thereby detecting the x-coordinate values of the bottom edges PB1 and PB2. do.

Further, the electronic images G3 and G4 are images when the inclination angle φ is φ1 (see FIG. 3). In the example shown in the electronic image G3, the analyzer 200 (see FIG. 1) sets one length measuring box B30 wider than the top width Lt. Then, the analysis device 200 detects the x-coordinate values of the top edges PT1 and PT2 by the same procedure as the detection of the x-coordinate values of the bottom edges PB1 and PB2 in the electronic image G1 described above, and if possible, the bottom. The x-coordinate values of the edges PB1 and PB2 are also detected.

Further, in the example shown in the electronic image G4, the analysis device 200 sets two length measuring boxes B41 and B42 narrower than the top width Lt. Then, the analysis device 200 detects the x-coordinate values of the top edges PT1 and PT2 by the same procedure as the detection of the x-coordinate values of the bottom edges PB1 and PB2 in the above-mentioned electronic image G2, and if possible, the bottom. The x-coordinate values of the edges PB1 and PB2 are also detected.

<User interface>
Next, the user interface of this embodiment will be described.
10 to 14 are diagrams illustrating display screens 502 to 520 displayed on the display 260.
(Display screen 502)
When the process proceeds to step S22 in the above-mentioned measurement processing routine (FIG. 8), the UI control unit 214 (see FIG. 1) causes the display 260 to display, for example, the display screen 502 shown in FIG. The display screen 502 includes a progress status display field 410, an image display field 412, a read button 414, a clear button 416, and an image acquisition condition display unit 418.

The progress status display column 410 is a column for displaying the progress status of the measurement process. The image display field 412 is a field for displaying the electronic image G10 to be processed. Here, the electronic image G10 is, for example, GC2 or GD2 shown in FIG. 4, and is an image acquired at an inclination angle φ = φ0. However, when the display screen 502 is displayed, the image display field 412 is blank. The read button 414 is a button for instructing the read of the electronic image G10 to be processed.

When the user presses the read button 414 (for example, when clicked with the mouse), a file selection dialog (not shown) is displayed on the display 260 (see FIG. 1), in which the electronic image stored in the image memory 160 is displayed. For example, it is displayed in a list format of image data files. Then, when the user selects a desired electronic image, the electronic image is read into the image storage unit 210 as the electronic image G10 to be processed. Further, when the user presses the clear button 416, the electronic image G10 is erased from the image storage unit 210.

Further, the image acquisition condition display unit 418 displays the image acquisition conditions of the electronic image G10, that is, various parameters in the electron microscope 100 when the electronic image G10 is acquired. The content of the image acquisition condition display unit 418 is based on the content embedded in the electronic image G10 in, for example, an XMP (Extensible Metadata Platform) format. Therefore, before the electronic image G10 is selected, the image acquisition condition display unit 418 is blank.

(Display screen 504)
After that, when the user performs a predetermined operation, the UI control unit 214 causes the display 260 to display, for example, the display screen 504 shown in FIG. On the display screen 504, instead of the read button 414, the clear button 416, and the image acquisition condition display unit 418 on the display screen 502, a length measurement box adjustment button 422, a length measurement button 424, and a length measurement condition designation field 430 are used. The bottom width display field 426 and the like are included. Further, in the image display field 412, the length measuring box B50 is displayed by superimposing on the electronic image G10.

Further, the length measurement condition designation field 430 includes a length measurement box number designation field 432, a length measurement algorithm designation field 434, and a threshold value designation field 436. Each time the user presses the length measurement box adjustment button 422, the on / off state is toggled. Then, when the length measuring box adjustment button 422 is on, the user can adjust the position and dimensions of the length measuring box B50.

Further, the user can specify the number of the length measuring boxes B50 from "1" or "2" in the length measuring box number designation field 432. Further, the user can specify the edge detection algorithm of the electronic image G10 in the length measurement algorithm designation field 434. In addition, the user can specify a threshold value applied to edge detection in the threshold value designation field 436. In the illustrated example, "Threshold" is specified as the algorithm and "10%" is specified as the threshold. This is, for example, in the secondary electron intensity IC2 shown in FIG. 4, the position at which the threshold value is "10%" or more away from the level of the flat section (between x coordinate values x2 and x3). Is determined to be an edge. "

The smaller this threshold value, the higher the possibility that the bottom width Lb can be detected accurately. However, if the threshold value is set too small, noise may be determined as the edge position. Various algorithms for determining edges in image data are known, not limited to the threshold method. In the present embodiment, the user can select the most preferable algorithm according to the electronic image G and the waveform of the electronic intensity. In this way, when the user presses the length measurement button 424 after determining the position and dimensions of the length measurement box B50 and setting the length measurement conditions, the process proceeds to step S24 in the measurement processing routine (FIG. 8), and the bottom The width calculation unit 222 (see FIG. 1) calculates the bottom width Lb (see FIG. 4).

(Display screen 506)
When the bottom width Lb is calculated, the UI control unit 214 (see FIG. 1) causes the display 260 to display the display screen 506 shown in FIG. 11, for example.
On the display screen 506, in the image display field 412, the signal profile P10 is displayed by superimposing on the electronic image G10. Here, the signal profile P10 is a graph of the intensity (for example, IC2 or ID2 shown in FIG. 4) corresponding to the electronic image G10. Further, the calculated bottom width Lb value is displayed in the bottom width display column 426.

(Display screen 508)
Here, when the user performs a predetermined operation on the input device 262 (see FIG. 1), the process proceeds to step S26 in the measurement processing routine (FIG. 8). In step S26, the UI control unit 214 (see FIG. 1) causes the display 260 to display, for example, the display screen 508 shown in FIG.

Similar to the display screen 502 (see FIG. 10), the display screen 508 includes a progress status display field 410, an image display field 412, a read button 414, a clear button 416, an image acquisition condition display unit 418, and the like. Includes. However, immediately after the display screen 508 is displayed, the image display field 412 and the image acquisition condition display unit 418 are blank.

When the user performs the same operation as described above on the display screen 502, such as pressing the read button 414, the electronic image G20 to be processed is read from the image memory 160 (see FIG. 1) into the image storage unit 210. Here, the electronic image G20 is, for example, the reflected electron images GD4 and GD6 shown in FIGS. 5 and 7, and is a reflected electron image acquired at an inclination angle φ = φ1. When the electronic image G20 is read into the image storage unit 210, the UI control unit 214 (see FIG. 1) causes the electronic image G20 to be displayed in the image display field 412. Further, the UI control unit 214 causes the image acquisition condition display unit 418 to display the image acquisition conditions of the electronic image G20.

(Display screen 510)
After that, when the user performs a predetermined operation, the UI control unit 214 causes the display 260 to display, for example, the display screen 510 shown in FIG. Similar to the display screen 504 (see FIG. 10), the display screen 510 includes a progress status display field 410, an image display field 412, a length measurement box adjustment button 422, a length measurement button 424, and a length measurement condition specification field 430. And, including. The functions of these elements are similar to those of the display screen 504. However, in the image display field 412, an electronic image G20 having an inclination angle φ = φ1 and a length measuring box B60 having dimensions corresponding to the electronic image G20 are displayed.

Further, the display screen 510 includes a left edge coordinate display field 442, a right edge coordinate display field 444, and a top center coordinate display field 446 instead of the bottom width display field 426 (see FIG. 10). These are for displaying the left edge coordinate, that is, the x coordinate value x11, the right edge coordinate, that is, the x coordinate value x14, and the top center coordinate, that is, the x coordinate value P1 (x) of the top center point P1 in FIG. It is a column.

However, when the display screen 510 is displayed, these

display fields

442, 444, 446 are blank. When the user presses the length measurement button 424 after determining the position and dimensions of the length measurement box B60 and setting the length measurement conditions, the process proceeds to step S28 in the measurement processing routine (FIG. 8). As described above, in step S28, the top edge position detection unit 224 (see FIG. 1) detects the x-coordinate values x11 and x14, and the top center position calculation unit 226 detects the x-coordinate value P1 (x) of the top center point P1. ) (See FIG. 5).

(Display screen 512)
When the x-coordinate value P1 (x) of the top center point P1 is calculated, the UI control unit 214 (see FIG. 1) causes the display 260 to display the display screen 512 shown in FIG. 12, for example. On the display screen 512, the signal profile P20 is displayed by superimposing on the electronic image G20 in the image display field 412. Here, the signal profile P20 is a graph of the intensities (for example, ID4 and ID6 shown in FIGS. 5 and 7) corresponding to the electronic image G20. Further, the left edge coordinates, the right edge coordinates, and the top center coordinates are displayed in the display columns 442,444,446, respectively.

(Display screen 514)
Next, when the user performs a predetermined operation, the process proceeds to step S30 in the measurement processing routine (FIG. 8). Here, the UI control unit 214 causes the display 260 to display, for example, the display screen 514 shown in FIG.

Similar to the display screens 502 and 508 (see FIGS. 10 and 11), the display screen 514 includes a progress status display field 410, an image display field 412, a read button 414, a clear button 416, and an image acquisition condition display unit. 418 and. The functions of these elements are the same as those of the display screens 502 and 508. Immediately after the display screen 514 is displayed, the image display field 412 and the image acquisition condition display unit 418 are blank.

Further, the display screen 514 includes an image diversion button 415. The image diversion button 415 specifies that the already read electronic image G20 (see FIG. 12) is diverted as the electronic image G30 to be processed this time. That is, the user may operate the read button 414 or the like to read the new electronic image G30 from the image memory 160 (see FIG. 1) into the image storage unit 210, or operate the image diversion button 415 to read the electronic image. G20 may be diverted as the electronic image G30.

Here, the electronic image G30 is, for example, a secondary electronic image GC5 (see FIG. 6) or a backscattered electron image GD6 (see FIG. 7), and is an image acquired at an inclination angle φ = φ1. When the electronic image G30 is acquired (or diverted), the UI control unit 214 (see FIG. 1) causes the electronic image G30 to be displayed in the image display field 412. Further, the UI control unit 214 causes the image acquisition condition display unit 418 to display the image acquisition condition of the electronic image G30.

(Display screen 516)
After that, when the user performs a predetermined operation, the UI control unit 214 causes the display 260 to display, for example, the display screen 516 shown in FIG. Similar to the display screens 504 and 510 (see FIGS. 10 and 12), the display screen 516 measures the progress status display field 410, the image display field 412, the length measurement box adjustment button 422, and the length measurement button 424. The long condition designation field 430 and the like are included. The functions of these elements are similar to those of the display screens 504 and 510. However, in the image display field 412, an electronic image G30 and a length measuring box B70 having dimensions corresponding to the electronic image G30 are displayed.

Further, the display screen 516 includes a bottom edge coordinate display field 450 and a bottom center coordinate display field 452 instead of the bottom width display field 426 (see FIG. 10). These are columns for displaying the bottom edge coordinates, that is, the x-coordinate value x13 in FIG. 6, and the bottom center coordinates, that is, the x-coordinate value P3 (x) of the bottom center point P3 at the time of inclination.

However, when the display screen 516 is displayed, these

display fields

450 and 452 are blank. When the user presses the length measurement button 424 after determining the position and dimensions of the length measurement box B70 and setting the length measurement conditions, the process proceeds to step S32 in the measurement processing routine (FIG. 8). As described above, in step S32, the bottom edge position detection unit 228 (see FIG. 1) detects the x-coordinate value x13 of the bottom edge PB2 (see FIG. 6), and the bottom center position calculation unit 230 is the bottom center when tilted. The x-coordinate value P3 (x) of the point P3 is calculated.

(Display screen 518)
When the x-coordinate value P3 (x) of the bottom center point P3 at the time of inclination is calculated, the UI control unit 214 (see FIG. 1) causes the display 260 to display, for example, the display screen 518 shown in FIG. On the display screen 518, the signal profile P30 is displayed by superimposing on the electronic image G30 in the image display field 412. Here, the signal profile P30 is a graph of the intensities (for example, GC5 and ID6 shown in FIGS. 6 and 7) corresponding to the electronic image G30. Further, the bottom edge coordinates and the bottom center coordinates are displayed in the

display columns

450 and 452, respectively.

(Display screen 520)
Next, when the user performs a predetermined operation, the process proceeds to step S34 in the measurement processing routine (FIG. 8). Here, the UI control unit 214 causes the display 260 to display, for example, the display screen 520 shown in FIG. The display screen 520 includes a progress status display field 410, a bottom width display field 426, a top center coordinate display field 446, and a bottom center coordinate display field 452. The functions of these elements are the same as those of the display screens 506, 512, 518, with the functions of the

display columns

426, 446, 452 described above.

Further, the display screen 520 includes a recess amount calculation button 460 and a recess amount display field 462. When the user presses the recess amount calculation button 460, the depth calculation unit 232 calculates the recess amount H = Δx / sinφ1, and the UI control unit 214 displays the recess amount H in the recess amount display column 462.

<Comparison example>
Hereinafter, a comparative example will be described in order to clarify the effect of the present embodiment. The hardware configuration applied to the comparative example is the same as that of the present embodiment (see FIG. 1), but in the comparative example, the recess amount H is measured based only on the secondary electron image GC.
FIG. 15 is a schematic diagram showing a measurement principle for measuring the recess amount H of the sample 700 in the comparative example.
Here, the sample 700 is entirely a conductor, and a recess 702 recessed in a substantially trapezoidal shape is formed on the upper surface thereof. The

top edges

704 and 706 of the recess 702 are not rounded. The angle formed by the bottom surface and the side surface of the recess 702 is defined as the side surface inclination angle θ, and the inclination angle of the sample 700 is defined as φ. The secondary electron intensity IC10 is the intensity based on the secondary electron image GC10 acquired for this sample 700. Let the x-coordinate values of the

top edges

704 and 706 be x52 and x56, and the x-coordinate values of the bottom edge 710 be x54. Further, the interval between the x-coordinate values x54 and x56 is called Δxs.

The interval Δxs is a value obtained by “Δxs = (H / sinθ) cos (θ−φ)”, and is a function of the inclination angle φ because the recess amount H and the side inclination angle θ are constants. At the x-coordinate value x56 of FIG. 5, a clear edge appears. Further, since the sample 700 is entirely a conductor, the analyzer 200 (see FIG. 1) can also detect the rise at the x-coordinate value x54. Thereby, the interval Δxs can be measured based on the secondary electron intensity IC10. Then, the user measures the interval Δxs while changing the inclination angle φ to various values.

FIG. 16 is a diagram showing an example of measurement results of the interval Δxs with respect to various inclination angles φ.
In FIG. 16, the measurement points Q11 to Q15 are measurement points in which the interval Δxs is measured while changing the inclination angle φ, and the approximate curve QC is a curve approximation of these measurement points Q11 to Q15 by the least squares method or the like. .. Since the shape of the approximate curve QC is determined by the recess amount H and the side inclination angle θ, if the approximate curve QC is obtained, the recess amount H and the side inclination angle θ can be obtained by fitting. However, in order to obtain an accurate approximate curve QC, it is necessary to acquire a relatively large number of measurement points (for example, "5" or more), which causes a problem that the number of measurement times increases.

FIG. 17 is a schematic diagram showing a measurement principle for measuring the recess amount H of another sample 740 in the comparative example.
Although the sample 740 is composed of a conductor, the overall shape is the same as that of the sample 330 (see FIG. 4) in the above embodiment. That is, a recess 752 recessed in a substantially trapezoidal shape is formed on the upper surface of the sample 740, and rounding is provided near the

top edges

744 and 746 of the recess 752. Further, the line connecting the bottom edge 750 and the top edge 746 is called an inclined line 754, and the angle formed by the bottom surface of the recess 752 and the inclined line 754 is called a side inclined angle θ.

The secondary electron intensity IC12 is the intensity based on the secondary electron image GC12 acquired for the sample 740. The x-coordinate value of the bottom edge 750 is x64, the x-coordinate value of the top edge 746 is x66, and the distance between the two is called Δxs. Further, since the sample 740 is entirely a conductor, the secondary electron intensity IC 12 becomes flat on the left side of the x-coordinate value x64 and on the right side of the x-coordinate value x66.

Therefore, the x-coordinate values x64 and x66 can be detected by detecting the rising and falling points of the secondary electron intensity IC 12, and the interval Δxs can be obtained. The recess amount H of the sample 740 can be obtained in the same manner as the recess amount H of the sample 700 (see FIG. 15) described above. However, since an error is likely to be mixed in the measurement of the x-coordinate value x66 of the top edge 746, it is necessary to acquire more measurement points in order to obtain an accurate recess amount H.

Next, referring to FIG. 6 again, consider measuring the recess amount H of the sample 330 according to a comparative example. In the above-described embodiment, the x-coordinate values x11 and x14 of the top edges PT1 and PT2 are detected based on the backscattered electron images GD4 and GD6 (see FIGS. 5 and 7), but in the comparative example, the secondary electron image GC5 The x-coordinate values x11 and x14 are detected based on the above. However, in FIG. 6, when trying to detect the x-coordinate values x11 and x14 based on the waveform of the secondary electron intensity IC5, the error becomes large.

The reason for the large error is that the oxide film 314 on the surface of the sample 330 is an insulator and is charged by the primary electron beam B1 (see FIG. 1). The state of charge is difficult to predict in advance and varies from time to time. Since the waveform of the secondary electron intensity IC5 fluctuates greatly depending on the state of charging, it becomes difficult to accurately identify the positions corresponding to the x-coordinate values x11 and x14. In order to suppress the influence of the error, the number of measurement points must be further increased, which further lengthens the total measurement time.
As described above, when the recess amount H of the sample 330 is to be measured by the technique of the comparative example, the measurement time becomes long and the measurement error of the recess amount H also becomes large.

<Effect of the first embodiment>
As described above, according to the present embodiment, the sample 330 in which the groove (312) is formed is an image taken by the charged particle beam device (100) in the first posture (φ = φ0) of the groove (312). The first image (GC2, GD2) including the portion corresponding to the pair of bottom edges PB1 and PB2 on the bottom surface 346 and the second posture (φ = φ0) in which the sample 330 is tilted from the first posture (φ = φ0). Image acquisition to acquire a second image (GD4, GD6) based on a charged particle having an energy of a predetermined energy (100 eV) or more, which is an image taken by a charged particle beam device (100) at φ = φ1). A depth calculation unit 220 that calculates the depth (H) of the groove (312) based on the unit 212, the first image (GC2, GD2), and the second image (GD4, GD6). To be equipped.

As described above, according to the present embodiment, the second image (GD4, GD6) can be acquired by the second posture (φ = φ1) in which the sample 330 is tilted from the first posture (φ = φ0). .. Then, since the second image (GD4, GD6) of the charged particles having high energy is applied, the depth (H) of the groove (312) can be accurately measured.

Further, the image acquisition unit 212 is an image of the sample 330 taken by the charged particle beam device (100) in the second posture (φ = φ1) and has an energy of less than a predetermined energy (100 eV). The third image (GC5) based on the above is acquired, and the depth calculation unit 220 acquires the first image (GC2, GD2), the second image (GD4, GD6), and the third image. It is preferable to calculate the depth (H) based on (GC5).
In this way, by using the first image (GC2, GD2), the second image (GD4, GD6), and the third image (GC5), which have different measurement conditions, the depth (H) is increased. ) Can be calculated accurately.

Further, the depth calculation unit 220 detects a pair of first bottom edge positions (x2, x3) corresponding to the positions of the pair of bottom edges PB1 and PB2 based on the first image (GC2, GD2). , It is preferable to include a bottom width calculation unit 222 that calculates the bottom width (Lb), which is the width of the bottom surface 346, based on the pair of first bottom edge positions (x2, x3).
Thereby, the bottom width (Lb) can be accurately calculated based on the first image (GC2, GD2) having a small inclination.

Further, the depth calculation unit 220 is based on the second image (GD4, GD6) and is the position of the pair of top edges PT1 and PT2 of the groove (312) in the second posture (φ = φ1). Top edge position detection unit 224 that detects the position (x11, x14) and top center position calculation unit 226 that calculates the top center position (P1 (x)) that is the midpoint between the pair of top edge positions (x11, x14). It is preferable to further prepare.
As a result, based on the second image (GD4, GD6) of the charged particles with high energy, the top edge position (x11, x14) and the top center position (P1 (x)) while suppressing the influence of the charge on the sample 330. Can be calculated.

Further, the depth calculation unit 220 has a second bottom edge corresponding to one of the positions of the pair of bottom edges PB1 and PB2 based on the second image (GD4, GD6) or the third image (GC5). Based on the bottom edge position detection unit 228 that detects the position (x13), the second bottom edge position (x13), and the bottom width Lb, the bottom center position (P3) in the second posture (φ = φ1). It is preferable to further include a bottom center position calculation unit 230 for calculating (x)).
As a result, if the second bottom edge position (x13) of at least one of the pair of bottom edges PB1 and PB2 can be detected in the second image (GD4, GD6), the bottom center position (P3 (x)) is calculated. be able to.

Further, the charged particle beam device (100) irradiates the sample 330 with the charged particle beam (B1), and the depth calculation unit 220 performs the charged particle beam in the second posture (φ = φ1). When the angle between the direction orthogonal to the path of (B1) and the line connecting the pair of top edges PT1 and PT2 of the groove (312) is φ1, the top center position (P1 (x)) and the bottom center It is preferable to further include a depth calculation unit 232 for calculating the depth (H) by dividing the difference from the position (P3 (x)) by sinφ1.
In this way, the depth (H) can be calculated accurately by calculating the depth (H) based on the top center position (P1 (x)) and the bottom center position (P3 (x)). can.

[Modification example]
The present invention is not limited to the above-described embodiment, and various modifications are possible. The above-described embodiments are exemplified for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, another configuration may be added to the configuration of the above embodiment, and a part of the configuration may be replaced with another configuration. In addition, the control lines and information lines shown in the figure show what is considered necessary for explanation, and do not necessarily show all the control lines and information lines necessary for the product. In practice, it can be considered that almost all configurations are interconnected. Possible modifications to the above embodiment are, for example, as follows.

(1) In the above embodiment, an example in which the electron microscope 100 is applied as an example of the "charged particle beam device" has been described, but the charged particle beam device is not limited to the electron microscope 100. That is, the electron microscope 100 applies electrons as "charged particles", but the charged particles are not limited to electrons and may be ion particles or the like.

(2) Since the hardware of the analysis device 200 in the above embodiment can be realized by a general computer, the flowchart shown in FIG. 8 and other programs for executing various processes described above are stored in a storage medium or a transmission line. It may be distributed via.

(3) Each of the above-mentioned processes has been described as a software-like process using a program in the above embodiment, but a part or all of them may be an ASIC (Application Specific Integrated Circuit; IC for a specific application) or an FPGA (Field). It may be replaced with hardware-like processing using Programmable Gate Array) or the like. Further, the image storage unit 210 shown in FIG. 1 may be provided in a cloud on a network (not shown).

(4) In the above embodiment, the method of measuring the recess amount for the structure in which the top edge is rounded, which is described in step S6 of FIG. 2 as the sample 330, has been described. However, the present invention may also be applied to a sample 700 (see FIG. 15) having a structure in which the top edge is not rounded, which is described as a comparative example. In the structure of the sample 700, the x-coordinate values (x52 and x56) of the top edge can be calculated from the secondary electron intensity IC10. That is, by setting these x52 and x56 as PT1 and PT2, respectively, the recess amount can be measured in the same manner.

1 Semiconductor inspection system (inspection system)
100 electron microscope (charged particle beam device)
200 analyzer (charged particle beam image analyzer, computer)
212 Image acquisition unit (image acquisition means)
220 Depth calculation unit (depth calculation means)
222 Bottom width calculation unit 224 Top edge position detection unit 226 Top center position calculation unit 228 Bottom edge position detection unit 230 Bottom center position calculation unit 232 Depth calculation unit 312 Trench (groove)
330 Sample 346 Bottom surface C Secondary electrons (charged particles)
D Reflected electron (charged particle)
G electronic image (image)
B1 primary electron beam (charged particle beam)
Lb bottom width GC2 secondary electron image (first image)
GC5 secondary electron image (third image)
GD2 reflected electron image (first image)
GD4, GD6 reflected electron image (second image)
PB1, PB2 Bottom edge PT1, PT2 Top edge x2, x3 x coordinate value (first bottom edge position)
x11, x14 x coordinate value (top edge position)
x13 x coordinate value (second bottom edge position)

Claims

An image of a grooved sample taken with a charged particle beam device in a first posture, the first image including a portion corresponding to a pair of bottom edges on the bottom surface of the groove, and the sample are the first. An image acquisition unit that acquires an image taken by the charged particle beam device in a second posture inclined from the posture of the above and based on a charged particle having an energy equal to or higher than a predetermined energy, and an image acquisition unit.
An analysis device for a charged particle beam image, comprising: a depth calculation unit for calculating the depth of the groove based on the first image and the second image.
The image acquisition unit further acquires a third image based on the charged particles having an energy less than the predetermined energy, which is an image of the sample taken by the charged particle beam device in the second posture. It is a thing
The charge according to claim 1, wherein the depth calculation unit calculates the depth based on the first image, the second image, and the third image. Analytical device for particle beam images.
The depth calculation unit
A pair of first bottom edge positions corresponding to a pair of the bottom edge positions are detected based on the first image, and a bottom width which is the width of the bottom surface based on the pair of first bottom edge positions. The charged particle beam image analysis apparatus according to claim 2, further comprising a bottom width calculation unit for calculating.
The depth calculation unit
Based on the second image, a top edge position detecting unit that detects a top edge position that is a position of a pair of top edges of the groove in the second posture, and a top edge position detecting unit.
The analysis device for a charged particle beam image according to claim 3, further comprising a top center position calculation unit that calculates a top center position that is an intermediate point between the pair of top edge positions.
The depth calculation unit
A bottom edge position detecting unit that detects a second bottom edge position corresponding to one of the positions of the pair of bottom edges based on the second image or the third image.
4. The fourth aspect of the present invention is characterized in that the bottom center position calculation unit for calculating the bottom center position in the second posture is further provided based on the second bottom edge position and the bottom width. Charged particle beam image analyzer.
The charged particle beam device irradiates the sample with a charged particle beam.
In the second posture, the depth calculation unit said that the angle between the direction orthogonal to the path of the charged particle beam and the line connecting the pair of top edges of the groove is φ1. The analyzer for a charged particle beam image according to claim 5, further comprising a depth calculation unit that calculates the depth by dividing the difference between the top center position and the bottom center position by sinφ1.
A charged particle beam device that irradiates a sample with a charged particle beam and forms an image based on the charged particles generated in the sample.
An image of the grooved sample taken with the charged particle beam device in the first posture, including a portion corresponding to a pair of bottom edges on the bottom surface of the groove, and the sample. An image taken by the charged particle beam device in a second posture inclined from the first posture and based on a charged particle having an energy equal to or higher than a predetermined energy, and a second image based on the charged particle beam device are shown in the charged particle beam device. Image acquisition unit to be acquired from
An inspection system including a depth calculation unit that calculates the depth of the groove based on the first image and the second image.
Computer,
An image of a grooved sample taken with a charged particle beam device in a first posture, the first image including a portion corresponding to a pair of bottom edges on the bottom surface of the groove, and the sample are shown in the first image. Image acquisition means for acquiring an image taken by the charged particle beam device in a second posture tilted from the posture of the above and based on a charged particle having an energy equal to or higher than a predetermined energy. Depth calculation means for calculating the depth of the groove based on the image of 1 and the second image.
A program to function as.