JPH11248442A - Step measuring method and step measuring device - Google Patents

Abstract

(57) [Summary] [Problem] To provide a step measurement method capable of measuring the size of a step with high accuracy using a scanning electron microscope without destroying a sample. An electron beam scanning step of scanning an electron beam on a sample by an electron lens barrel, and using a secondary electron detector to measure the intensity of secondary electrons α jumping out of the sample by scanning the electron beam. A secondary electron detection step of detecting, a detection step of detecting a detection signal profile based on the intensity of the secondary electrons α obtained in the secondary electron detection step, and a detection signal profile obtained in the detection step and a predetermined A calculating step of calculating the depth of the step by comparing the detection signal profile with the detection signal profile at the step of the depth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step measuring method and a step measuring apparatus for measuring the depth of a step on a sample in a scanning electron microscope.

[0002]

2. Description of the Related Art A conventional scanning electron microscope can observe the surface structure of a sample such as a semiconductor wafer in detail, and can measure the dimensions of the surface structure. On the other hand, the depth of the step is measured by destroying the sample and observing the cross section, or obliquely observing the sample without destroying it.

[0003]

The above-mentioned conventional scanning electron microscope has the following problems. That is,
In order to measure the depth of the step with a scanning electron microscope, it was necessary to break the sample. On the other hand, when the sample is not desired to be destroyed, the sample is inclined and observed. However, there are problems such as a complicated mechanism for moving and tilting the sample.

Accordingly, an object of the present invention is to provide a step measuring method and a step measuring apparatus capable of measuring the size of a step with high accuracy using a scanning electron microscope without destroying or tilting the sample. And

[0005]

Means for Solving the Problems In order to solve the above problems and achieve the object, an invention according to claim 1 is a method for measuring the depth of a step on a sample, the method comprising: An electron beam scanning step of scanning an electron beam with an electron column, a secondary electron detection step of detecting the intensity of secondary electrons that have jumped out of the sample by scanning the electron beam using a secondary electron detector, A detection step of detecting a detection signal profile based on the intensity of the secondary electrons obtained in the secondary electron detection step, and a detection signal profile obtained in the detection step and a detection signal profile at a step of a predetermined depth. And a calculating step of calculating the depth of the step by comparing.

According to a second aspect of the present invention, in the first aspect, before the secondary electron detecting step, a potential distribution controlling step of changing a potential distribution acting on the secondary electrons is performed. It was prepared.

According to a third aspect of the present invention, in the second aspect of the invention, the potential distribution control step changes a secondary electron attracting voltage of the secondary electron detector.

According to a fourth aspect of the present invention, in the second aspect of the invention, the electric potential distribution controlling step changes an orientation of the secondary electron detector with respect to the sample.

According to a fifth aspect of the present invention, in the second aspect of the present invention, the potential distribution controlling step changes a relative position of the secondary electron detector with respect to the sample.

According to a sixth aspect of the present invention, in the second aspect of the invention, the potential distribution controlling step changes a local potential applied to the vicinity of the sample.

According to a seventh aspect of the present invention, in the second aspect of the invention, the electric potential distribution controlling step changes a relative position of the electron lens barrel with respect to the secondary electron detector and the sample. Things.

The invention according to claim 8 is a step measurement method for measuring a depth of a step on a sample, wherein the electron beam scanning step of scanning an electron beam on the sample by an electron lens barrel; A backscattered electron detecting step of detecting the intensity of backscattered electrons reflected on the sample by the scanning using a backscattered electron detector, and calculating a detection signal profile based on the backscattered electron intensity obtained in the backscattered electron detection step. A detection step; and an operation step of calculating the depth of the step by comparing the detection signal profile obtained in the detection step with a detection signal profile at a step having a predetermined depth.

According to a ninth aspect of the present invention, in the above-described eighth aspect, a detection position control step of changing a detection position of the reflected electrons is provided before the reflected electron detection step. .

The invention described in claim 10 is the ninth invention.
In the invention described in the above, the detection position control step,
The position of the backscattered electron detector relative to the sample is changed.

The invention described in claim 11 is the ninth invention.
In the invention described in the above, the detection position control step,
The relative position of the electron lens barrel with respect to the sample is changed.

According to a twelfth aspect of the present invention, in the step measuring device for measuring the depth of a step on a sample, an electron beam scanning section for scanning an electron beam on the sample and the electron beam scanning section using the electron beam scanning section. A secondary electron detector that detects the intensity of secondary electrons that have jumped out of the sample by electron beam scanning, and a detector that detects a detection signal profile based on the intensity of the secondary electrons obtained by the secondary electron detector. And a calculation unit that calculates the depth of the step by comparing a detection signal profile obtained by the detection unit with a detection signal profile at a step having a predetermined depth.

According to a thirteenth aspect of the present invention, there is provided a step measuring device for measuring a depth of a step on a sample, wherein the electron beam scanning section scans the sample with an electron beam by using an electron column; A backscattered electron detector that detects the intensity of backscattered electrons reflected by the sample using the backscattered electron detector, and calculates a detection signal profile based on the backscattered electron intensity obtained in the backscattered electron detection step. A detection unit is provided with an arithmetic unit that calculates the depth of the step by comparing the detection signal profile obtained by the detection unit with the detection signal profile at a step of a predetermined depth.

As a result of taking the above-described measures, the following operation occurs. That is, according to the first aspect of the present invention, the intensity of the secondary electrons jumping out of the sample by the scanning of the electron beam is detected using the secondary electron detector, and the detection signal profile is detected based on the intensity of the secondary electrons. Detect and detect
The depth of the step can be calculated by comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth.

According to the second aspect of the present invention, before the secondary electron detecting step, a potential distribution controlling step of changing a potential distribution acting on the secondary electrons is provided. Can be obtained, and the depth of the step can be calculated with high accuracy.

According to the third aspect of the present invention, the potential distribution acting on the secondary electrons can be changed by changing the secondary electron attracting voltage of the secondary electron detector. Claim 4
In the invention described in (1), the distribution of the potential acting on the secondary electrons can be changed by changing the direction of the secondary electron detector with respect to the sample.

According to the fifth aspect of the present invention, the potential distribution acting on the secondary electrons can be changed by changing the relative position of the secondary electron detector with respect to the sample. Claim 6
In the invention described in (1), the potential distribution acting on the secondary electrons can be changed by changing the local potential applied to the vicinity of the sample.

According to the seventh aspect of the present invention, the potential distribution acting on the secondary electrons can be changed by changing the relative positions of the electron lens barrel with respect to the secondary electron detector and the sample. According to the invention described in claim 8, the intensity of the reflected electrons jumping out of the sample by the scanning of the electron beam is detected by using the reflected electron detector, and the detection signal profile is detected based on the intensity of the reflected electrons. Then, the depth of the step can be calculated by comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth.

According to the ninth aspect of the present invention, a plurality of detection signal profiles can be obtained because a potential distribution control step of changing a detection position of the backscattered electrons is provided before the backscattered electron detection step. Thus, the depth of the step can be calculated with high accuracy.

According to the tenth aspect, the relative position of the backscattered electron detector with respect to the sample can be changed to change the backscattered electron detection position. According to the eleventh aspect, the detection position of the reflected electrons can be changed by changing the relative position of the electron lens barrel with respect to the sample.

According to the twelfth aspect of the present invention, the intensity of secondary electrons jumping out of the sample by scanning of the electron beam is detected using a secondary electron detector, and a detection signal is detected based on the intensity of the secondary electrons. The depth of the step can be calculated by detecting the profile and comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth.

According to the thirteenth aspect of the present invention, the intensity of the reflected electrons jumping out of the sample by the scanning of the electron beam is detected using the reflected electron detector, and the detection signal profile is detected based on the intensity of the reflected electrons. Then, the depth of the step can be calculated by comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a schematic diagram showing a step measuring device 10 according to a first embodiment of the present invention.
In FIG. 1, W indicates a sample such as a wafer, and a concave portion Wa is formed on the surface thereof. Step measuring device 10
Is a device for measuring the depth of the recess Wa.

The step measuring device 10 includes a measurement chamber 11 on which a sample W is placed, an electron lens barrel 12 attached to the ceiling of the measurement chamber 11 for focusing an electron beam ε on the sample W, and a sample W
Electron detector 1 that attracts and detects secondary electrons α from
3 and a sample stage 14 on which the sample W is placed. That is, the level difference measuring device 10 is a type of a scanning electron microscope. The level difference measuring device 10 includes a potential distribution control unit that changes a potential distribution acting on secondary electrons, and can change a potential distribution acting on secondary electrons.

In such a step measuring device 10, the depth of the recess Wa is measured as follows. When the electron beam ε is converged on the sample W and scanned along the direction of the arrow X in FIG. 1A, a signal intensity profile of the secondary electrons α as shown in FIG. 1B is detected. That is, the secondary electrons α that are emitted once increase at the edge of the recess Wa, so that the signal intensity increases. However, when the lower part is irradiated with the electron beam ε, the secondary electrons α are blocked by the inner wall. Since the blocked secondary electrons α do not reach the secondary electron detector 13, the signal intensity is low.

On the other hand, when the step of the recess Wa changes from t1 to t2 as shown in FIG. 1C, the number of secondary electrons α blocked by the inner wall increases, and the signal intensity becomes (d) in FIG. ).

That is, the depth of the step is calculated from the detected signal profile by previously measuring the relationship between the depth of the step and the widths a1 and a2 and the signal strengths b1 and b2 of the portion where the signal intensity is reduced. Can be.

As described above, according to the step measuring apparatus 10 according to the first embodiment, when measuring the depth of the step on the sample W, the detection signal is determined in accordance with the depth of the step. Utilizes that the profile changes. For this reason, if the relationship between the depth of the step and the detection signal profile is measured in advance, the sample W will not be broken or tilted,
The depth of the step can be calculated based on the obtained detection signal profile.

FIGS. 2A to 2C show observation examples of tungsten buried in the contact holes (recesses), and FIGS. 2D to 2F show respective detection signal profiles. ing. The depth of the step is (a),
It becomes larger in the order of (b) and (c). Since the secondary detector 13 is located in the lower left direction of the image, part of the secondary electrons α from the bottom left of the contact hole is blocked by the inner wall of the contact hole, which appears as a shadow in the image. The size of this shadow increases in the order of (a), (b), and (c), and the widths Pa and P of the portions where the signal intensity of the detection signal profile is small.
b and Pc also increase in this order.

FIG. 3 is a schematic diagram showing a level difference measuring apparatus 10A according to a second embodiment of the present invention. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The level difference measuring device 10A measures the detection signal profile in the same manner as the level difference measuring device 10 described above, and then increases the secondary electron attracting voltage of the secondary electron detector 13 to measure the detection signal profile again. I have to.

The level difference measuring device 10A includes a potential distribution control unit for changing the secondary electron attracting voltage of the secondary electron detector 13. The secondary electron attraction voltage is, for example, 0
Measure 9 times in 9 steps from ｋ8 kV. The case where the secondary electron attracting voltage is high as shown in FIGS. 3C and 3D is compared with the case where the secondary electron attracting voltage is low as shown in FIGS. 3A and 3B. Has the property that the ratio of being blocked by the inner wall of the recess Wa increases, and the range in which the signal intensity decreases is widened. For this reason, since the change in the depth of the step is more emphasized, the change is reflected in the detection signal profile, and the measurement of the depth of the step can be performed with higher accuracy.

As described above, the depth of the step can be measured with higher precision by changing the secondary electron attracting voltage and measuring a plurality of detection signal profiles. FIG.
Is a level difference measuring device 10B according to the third embodiment of the present invention.
FIG. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the step measuring device 10B, after measuring the detection signal profile in the same manner as the above-described step measuring device 10, the direction of the secondary electron detector 13 is changed and the detection signal profile is measured again.

The level difference measuring device 10B includes a potential distribution control section for changing the potential distribution acting on the secondary electrons, and can control the direction of the secondary electron detector 13 with respect to the sample W.

The orientation of the secondary electron detector 13 is measured three times in three steps, for example. As shown in FIGS. 4 (a) and 4 (b), the secondary electron detector 13 is directed toward the recess Wa side as shown in FIGS. 4 (c) and 4 (d). When the secondary electron detector 13 is not facing the recess Wa side,
The ratio of being blocked by the inner wall of the recess Wa increases, and the range in which the signal intensity decreases is widened. For this reason,
Since the change in the depth of the step is more emphasized, the change is reflected in the detection signal profile, and the measurement of the depth of the step can be performed with higher accuracy.

As described above, by changing the direction of the secondary electron detector 13 and measuring a plurality of detection signal profiles, the depth of the step can be measured with higher accuracy.
FIG. 5 shows a level difference measuring device 1 according to a fourth embodiment of the present invention.
It is a schematic diagram which shows OC. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the step measuring device 10C, after measuring the detection signal profile in the same manner as the above-described step measuring device 10, the relative position between the sample W and the secondary electron detector 13 is changed to measure the detection signal profile again. Like that.

The level difference measuring device 10C includes a potential distribution control unit for changing the potential distribution acting on the secondary electrons, and can control the relative position of the secondary electron detector 13 with respect to the sample W.

The relative position between the sample W and the secondary electron detector 13 is measured three times, for example, in three stages. As shown in FIGS. 5A and 5B, the sample W and the secondary electron detector 1 were used.
5 (c) and (c) of FIG.
As shown in (d), when the distance between the sample W and the secondary electron detector 13 is large, the ratio of being blocked by the inner wall of the concave portion Wa increases, and the range in which the signal intensity decreases is widened. . For this reason, since the change in the depth of the step is more emphasized, the change is reflected in the detection signal profile, and the measurement of the depth of the step can be performed with higher accuracy.

As described above, the depth of the step can be measured with higher accuracy by changing the secondary electron attracting voltage and measuring a plurality of detection signal profiles. FIG.
Is a level difference measuring device 10E according to a fifth embodiment of the present invention.
FIG. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the step measuring device 10E, a mesh electrode 15 is provided near the sample W. Step measurement device 10E
In the first embodiment, after measuring the detection signal profile in the same manner as the above-described step measurement device 10, the local potential applied to the vicinity of the sample W is changed and the detection signal profile is measured again. That is, the potential applied to the electrode 15 is measured five times in five steps within a range of, for example, ± 1 kV.

The level difference measuring device 10E includes a potential distribution control unit for changing the potential distribution acting on the secondary electrons, and can control a local potential applied to the vicinity of the sample W.

When the voltage applied to the electrode 15 is low as shown in FIGS. 6A and 6B, the voltage applied to the electrode 15 is high as shown in FIGS. 6C and 6D. Has the property that the ratio of being blocked by the inner wall of the recess Wa increases, and the range in which the signal intensity decreases is widened. For this reason, since the change in the depth of the step is more emphasized, the change is reflected in the detection signal profile, and the measurement of the depth of the step can be performed with higher accuracy.

As described above, the depth of the step can be measured with higher accuracy by changing the voltage applied to the electrode 15 and measuring a plurality of detection signal profiles. FIG.
Is a level difference measuring device 10F according to the sixth embodiment of the present invention.
FIG. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the step measuring apparatus 10F, an electrode 16 is provided below the objective lens of the electron lens barrel 12. In the step measurement device 10F, after measuring the detection signal profile in the same manner as the above-described step measurement device 10, the local potential applied to the vicinity of the sample W (between the electron lens barrel 12 and the sample W) is changed, and the step is measured again. The detection signal profile is measured. That is, the potential applied to the electrode 16 is, for example, ± 10
The measurement is performed five times in five steps in the range of V.

The level difference measuring device 10 includes a potential distribution control unit that changes a potential distribution acting on secondary electrons, and controls a local potential applied between the electron lens barrel 12 and the sample W. Can be.

When the voltage applied to the electrode 16 is low as shown in FIGS. 7A and 7B, the voltage applied to the electrode 16 is high as shown in FIGS. 7C and 7D. Has the property that the ratio of being blocked by the inner wall of the recess Wa increases, and the range in which the signal intensity decreases is widened. For this reason, since the change in the depth of the step is more emphasized, the change is reflected in the detection signal profile, and the measurement of the depth of the step can be performed with higher accuracy.

As described above, the depth of the step can be measured with higher accuracy by changing the voltage applied to the electrode 16 and measuring a plurality of detection signal profiles. FIG.
Is a level difference measuring device 10G according to the seventh embodiment of the present invention.
FIG. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The step measuring device 10G includes a potential distribution control section for changing a potential distribution acting on secondary electrons, and controls the relative positions of the electron column 12 with respect to the secondary electron detector 13 and the sample W. can do.

In the step measuring device 10G, after measuring the detection signal profile in the same manner as in the step measuring device 10 described above, the electron beam tube 1 for the secondary electron detector 13 and the sample W is measured.
The detection signal profile is measured again by changing the relative position of No.2.

The relative position is measured three times, for example, in three stages. In addition, when the relative position is far as shown in FIGS. 8C and 8D, the recess Wa is smaller than the case where the relative position is closer as shown in FIGS. 8A and 8B. There is a property that the ratio of being blocked by the inner wall increases and the range in which the signal strength decreases is widened. For this reason, since the change in the depth of the step is more emphasized, the change is reflected in the detection signal profile, and the measurement of the depth of the step can be performed with higher accuracy.

As described above, the secondary electron detector 13 and the sample W
The depth of the step can be measured with higher accuracy by changing the relative position of the electron lens barrel 12 with respect to and measuring a plurality of detection signal profiles.

FIG. 9 is a schematic view showing a level difference measuring device 10H according to an eighth embodiment of the present invention. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the step measuring device 10H, after measuring the detection signal profile in the same manner as in the above-described step measuring device 10, the electron beam tube 1 for the secondary electron detector 13 and the sample W is measured.
The detection signal profile is measured again by changing the direction of No. 2.

The direction of the electronic lens barrel 12 is measured three times, for example, in three stages. In addition, as shown in FIGS. 9 (c) and 9 (d), compared with the case where the electron lens barrel 12 is directed straight toward the sample W side as shown in FIGS. 9 (a) and 9 (b). When the lens barrel 12 faces at an angle from the sample W side,
The ratio of being blocked by the inner wall of the recess Wa increases, and the range in which the signal intensity decreases is widened. For this reason,
Since the change in the depth of the step is more emphasized, the change is reflected in the detection signal profile, and the measurement of the depth of the step can be performed with higher accuracy.

As described above, the secondary electron detector 12 and the sample W
The depth of the step can be measured with higher accuracy by changing the direction of the electron lens barrel 12 and measuring a plurality of detection signal profiles.

FIG. 10 is a schematic diagram showing a level difference measuring apparatus 10I according to a ninth embodiment of the present invention. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The step measuring device 10I is provided with two secondary electron detectors 13. The step measurement device 10I can simultaneously detect two types of detection signal profiles as shown in FIGS. 10B and 10C.

By using a plurality of detection signal profiles as described above, the depth of the step can be measured with higher accuracy. FIG. 11A is a schematic view showing a level difference measuring device 20 according to a tenth embodiment of the present invention. In addition,
In FIG. 11, W indicates a sample such as a wafer, and a concave portion Wa is formed on the surface thereof. The level difference measuring device 20 is a device that measures the depth of the recess Wa.

The step measuring device 20 includes a measuring chamber 21 on which the sample W is placed, an electron lens barrel 22 attached to the ceiling of the measuring chamber 21 for focusing the electron beam ε on the sample W,
Backscattered electron detector 23 for detecting backscattered electrons β reflected by
And a sample table 24 on which the sample W is placed. That is, the step measurement device 20 is a type of a scanning electron microscope.

In such a step measuring device 20, the depth of the recess Wa is measured as follows. When the electron beam ε is converged on the sample W and scanned along the arrow X direction in FIG. 11A, a signal intensity profile of the reflected electrons β as shown in FIG. 11B is detected. That is, the recess Wa
When the electron beam ε is irradiated to the lower part of the surface, the reflected electrons β are blocked by the inner wall. Since the shielded backscattered electrons β do not reach the backscattered electron detector 23, the signal intensity decreases.

On the other hand, when the step of the recess Wa changes from t3 to t4 as shown in FIG. 11 (c), the number of reflected electrons β blocked by the inner wall increases, and the signal intensity decreases as shown in FIG. 11 (d). It is as shown in

That is, the depth of the step can be calculated from the detection signal profile by measuring the depth of the step and the widths a3 and a4 of the portion where the signal intensity is small in advance.

FIGS. 12A to 12C show observation examples of tungsten buried in the contact holes (concave portions), and FIGS. 12D to 12F show respective detection signal profiles. ing. The depth of the step increases in the order of (a), (b), and (c). Since the backscattered electron detector 23 is annular so as to surround the image, a part of the backscattered electrons β from the bottom of the contact hole is blocked by the inner wall of the contact hole, which appears as a shadow in the image. The size of the shadow increases in the order of (a), (b), and (c), and the widths Qa, Qb, and Qc of the portion where the signal intensity of the detection signal profile is small also increase in this order.

FIG. 13 is a schematic view showing a level difference measuring device 20A according to an eleventh embodiment of the present invention. In this figure, the same functional parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The step measuring device 20A includes a detection position control section for changing the detection position of the backscattered electrons, and can control the relative positions of the backscattered electron detector 23 and the electron lens barrel 22 with respect to the sample W.

In the step measuring device 20A, after measuring the detection signal profile in the same manner as in the step measuring device 20, the electron column 22 and the backscattered electron detector 2 for the sample W are measured.
The relative position of No. 3 is changed, and the detection signal profile is measured again.

The relative position is measured three times, for example, in three stages. Note that the detection signal profiles are different between the relative positions shown in FIGS. 13A and 13B and the relative positions shown in FIGS. 13C and 13D.

By measuring a plurality of detection signal profiles while changing the relative position in this way, the depth of the step can be measured with higher accuracy. It should be noted that the present invention is not limited to the embodiments, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

[0075]

According to the first aspect of the present invention, the intensity of secondary electrons jumping out of the sample by scanning of the electron beam is detected using a secondary electron detector, and the intensity of the secondary electrons is detected. Detecting detecting signal profile based on detecting,
The depth of the step can be calculated by comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth. The depth of the step can be measured without breaking or tilting the sample.

According to the eighth aspect of the invention, the intensity of the reflected electrons jumping out of the sample by the scanning of the electron beam is detected using the reflected electron detector, and the detection signal profile is determined based on the intensity of the reflected electrons. Is detected, and the depth of the step can be calculated by comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth. The depth of the step can be measured without breaking or tilting the sample.

According to the twelfth aspect of the present invention, the intensity of the secondary electrons jumping out of the sample by the scanning of the electron beam is detected by using the secondary electron detector, and based on the intensity of the secondary electrons, Detect detecting signal profile,
The depth of the step can be calculated by comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth. The depth of the step can be measured without breaking or tilting the sample.

According to the thirteenth aspect of the present invention, the intensity of the reflected electrons jumping out of the sample by the scanning of the electron beam is detected using the reflected electron detector, and the detected signal profile is determined based on the intensity of the reflected electrons. Detect and detect
The depth of the step can be calculated by comparing the obtained detection signal profile with the detection signal profile at the step having a predetermined depth. The depth of the step can be measured without breaking or tilting the sample.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a step measuring device according to a first embodiment of the present invention, and a diagram showing a detection signal profile obtained by the step measuring device.

FIG. 2 is a diagram showing a micrograph showing an image obtained by a secondary electron detector by the same level measuring device and a detection signal profile.

FIG. 3 is a schematic diagram showing a level difference measuring device according to a second embodiment of the present invention, and a diagram showing a detection signal profile obtained by the level difference measuring device.

FIG. 4 is a schematic diagram showing a step measuring device according to a third embodiment of the present invention and a diagram showing a detection signal profile obtained by the step measuring device.

FIG. 5 is a schematic diagram showing a level difference measuring device according to a fourth embodiment of the present invention and a diagram showing a detection signal profile obtained by the level difference measuring device.

FIG. 6 is a schematic diagram showing a step measurement device according to a fifth embodiment of the present invention, and a diagram showing a detection signal profile obtained by the step measurement device.

FIGS. 7A and 7B are a schematic diagram showing a step measuring device according to a sixth embodiment of the present invention and a diagram showing a detection signal profile obtained by the step measuring device.

FIG. 8 is a schematic diagram showing a step measurement device according to a seventh embodiment of the present invention, and a diagram showing a detection signal profile obtained by the step measurement device.

FIG. 9 is a schematic diagram showing a step measurement device according to an eighth embodiment of the present invention, and a diagram showing a detection signal profile obtained by the step measurement device.

FIG. 10 is a schematic diagram showing a step measuring device according to a ninth embodiment of the present invention and a diagram showing a detection signal profile obtained by the step measuring device.

FIG. 11 is a schematic diagram showing a level difference measuring device according to a tenth embodiment of the present invention, and a diagram showing a detection signal profile obtained by the level difference measuring device.

FIG. 12 is a diagram showing a micrograph showing an image obtained by a backscattered electron detector by the step measurement device and a detection signal profile.

FIG. 13 is a schematic diagram showing a step measurement device according to an eleventh embodiment of the present invention, and a diagram showing a detection signal profile obtained by the step measurement device.

[Explanation of symbols]

 10, 20: step measuring device 11, 21, measuring chamber 12, 22, electron column 13: secondary electron detector 23: backscattered electron detector

Claims (13)

[Claims] 1. A step measuring method for measuring a depth of a step on a sample, comprising: an electron beam scanning step of scanning an electron beam on the sample with an electron lens barrel; A secondary electron detecting step of detecting the intensity of secondary electrons using a secondary electron detector, and a detecting step of detecting a detection signal profile based on the intensity of the secondary electrons obtained in the secondary electron detecting step And a calculation step of calculating the depth of the step by comparing the detection signal profile obtained in the detection step with a detection signal profile at a step of a predetermined depth. Method. 2. The step measuring method according to claim 1, further comprising a potential distribution controlling step of changing a potential distribution acting on the secondary electrons before the secondary electron detecting step. 3. The step measuring method according to claim 2, wherein the potential distribution controlling step changes a secondary electron attracting voltage of the secondary electron detector. 4. The step measuring method according to claim 2, wherein the step of controlling the potential distribution changes a direction of the secondary electron detector with respect to the sample. 5. The step measuring method according to claim 2, wherein the step of controlling the potential distribution changes a relative position of the secondary electron detector with respect to the sample. 6. The step measurement method according to claim 2, wherein the potential distribution control step changes a local potential applied to a vicinity of the sample. 7. The step measurement method according to claim 2, wherein the potential distribution control step changes a relative position of the electron lens barrel with respect to the secondary electron detector and the sample. 8. A step measuring method for measuring a depth of a step on a sample, comprising: an electron beam scanning step of scanning an electron beam on the sample by an electron lens barrel; A backscattered electron detection step of detecting the intensity of the backscattered electrons using a backscattered electron detector; a detection step of calculating a detection signal profile based on the backscattered electron intensity obtained in the backscattered electron detection step; A step of calculating the depth of the step by comparing the obtained detection signal profile with a detection signal profile at a step of a predetermined depth. 9. The step measuring method according to claim 8, further comprising a detection position control step of changing a detection position of the reflected electrons before the reflected electron detection step. 10. The step measuring method according to claim 9, wherein said detecting position control step changes a relative position of said backscattered electron detector with respect to said sample. 11. The step measuring method according to claim 9, wherein the detecting position control step changes a relative position of the electron lens barrel with respect to the sample. 12. A step measuring device for measuring a depth of a step on a sample, comprising: an electron beam scanning section for scanning an electron beam on the sample; and an electron beam scanning section for scanning the sample by the electron beam. A secondary electron detector that detects the intensity of the secondary electrons that have jumped out; a detector that detects a detection signal profile based on the intensity of the secondary electrons obtained by the secondary electron detector; A step calculator for calculating the depth of the step by comparing the detected signal profile with a detection signal profile at a step having a predetermined depth. 13. A step measuring device for measuring a depth of a step on a sample, comprising: an electron beam scanning section for scanning an electron beam on the sample by an electron lens barrel; A backscattered electron detector that detects the intensity of backscattered electrons using a backscattered electron detector; a detector that calculates a detection signal profile based on the backscattered electron intensity obtained in the backscattered electron detection step; A step measuring device, comprising: an arithmetic unit for calculating the depth of the step by comparing the obtained detection signal profile with a detection signal profile at a step having a predetermined depth.