JP5071815B2 - Calibration standard of scanning microscope using nanometer scale measurement standard sample and nanometer scale measurement standard sample - Google Patents

Description

  The present invention relates to a measurement standard sample of a nanometer scale and a method of calibrating a scanning microscope using the measurement standard sample of a nanometer scale. Alternatively, the present invention relates to a nanometer-scale measurement standard sample as a length measurement standard sample and a scanning microscope calibration method using the nanometer-scale measurement standard sample.

  Scanning microscopes such as scanning electron microscopes (SEM), scanning tunneling microscopes (STM), scanning atomic force microscopes (AFM), and scanning laser microscopes (SLM) are mainly used for nanometer scale measurement. It is used. SEM is mainly used for line width measurement. Scanning probe microscopes (SPM) such as AFM and STM are used not only for measuring length and height but also for measuring surface roughness. At that time, standard materials for calibrating the length and height are required. Conventionally, a single crystal silicon substrate (silicon standard sample) having an atomically flat terrace and an atomic step with a height of 0.31 nm on the surface is used as a measurement standard document of AFM (Non-patent Document 1).

  However, when the silicon standard sample according to Non-Patent Document 1 is exposed to the atmosphere, an oxide film is generated on the surface. On the other hand, calibration of AFM is usually performed in the atmosphere, and the flatness of the terrace of the silicon standard sample is lost with time, so that it easily deviates from the calibration value of 0.31 nm height. There was a problem that.

  In order to improve them, a standard sample using sapphire having a step structure stable in the atmosphere has been developed (Patent Document 1).

JP 2006-284316 A

Japan Electronics and Information Technology Industries Association Standards “AFM height calibration method on the order of 1 nm” p. 3-5 July 2002

  However, since sapphire is a compound composed of two elements of aluminum and oxygen, its crystal completeness is inferior to that of a single element material. As a result, roughness equal to or greater than the step height exists in the terrace portion of the sapphire substrate having the step terrace structure. That is, as compared with the silicon standard sample, the increase in the roughness of the terrace with time can be suppressed, but there is a problem that it is difficult to perform accurate height calibration because the roughness originally exists.

  Moreover, since sapphire is an insulator, it is not suitable for SEM and STM standard samples.

  In order to perform nanometer-scale measurement, a measurement standard sample having a three-dimensional structure controlled at the atomic scale, stable in the atmosphere, and having conductivity that can be observed by SEM or STM is required. However, until now, no such measurement standard has been provided.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a nanometer-scale measurement standard sample and a scanning microscope calibration method using the nanometer-scale measurement standard sample. There is to do.

  In order to achieve the above object, the present invention provides, as a first aspect, a nanometer-scale measurement standard sample according to the present invention having a single off angle within 10 degrees from the main surface {111} plane or {111} plane. A crystal diamond substrate, and a triangular structure having n layers (an integer of n ≧ 1) having a step height of 0.206 nm formed on the single crystal diamond substrate and having an atomically flat terrace surface of 0.206 nm. It is characterized in that a straight line of a triangle connecting two vertices of the structure is used as a standard length.

  Moreover, the present invention provides, as a second aspect, a nanometer-scale measurement standard sample according to the present invention having a single crystal diamond substrate with an off angle of 10 degrees or less from the main surface {111} plane or {111} plane, 1 step height formed on a single crystal diamond substrate; a triangular structure having n layers (an integer of n ≧ 1) having an atomically flat terrace surface of 0.206 nm, and 1 of the triangles of the triangular structure The feature is that the side is used as a standard for linearity.

  Moreover, the present invention provides, as a third aspect, a nanometer-scale measurement standard sample according to the present invention having a single crystal diamond substrate with an off angle of 10 degrees or less from the main surface {111} plane or {111} plane, 1 step height formed on a single-crystal diamond substrate; a triangular structure having n steps (an integer of n ≧ 1) having an atomically flat terrace surface of 0.206 nm; It is characterized by a standard height.

  In this case, in the nanometer-scale measurement standard sample according to the present invention, the triangle of the triangular structure is a regular triangle, and the length of one side of the triangle of the triangular structure is a triangle positioned in the upper stage. As short as possible.

  In the nanometer-scale measurement standard sample according to the present invention, the atomically flat terrace surface includes a plurality of triangular structures having different lengths on one side on the main surface. In addition, the single crystal diamond of the single crystal diamond substrate has a hydrogen termination.

  The nanometer-scale measurement standard sample according to the present invention is for a scanning microscope, and is suitably used in a scanning probe microscope (SPM) or a scanning electron microscope (SEM).

  As another aspect, the present invention provides a scanning microscope calibration method using the nanometer-scale measurement standard sample.

  As a first aspect, the SPM calibration method using the nanometer-scale measurement standard sample provided by the present invention includes a step of setting the standard sample in a scanning probe microscope (SPM) apparatus and designation of the standard sample surface. Moving the SPM measurement range with an optical microscope to the position of the mesa structure, obtaining an SPM image of an n-stage (n ≧ 1 integer) triangular structure designated as the calibration location, and the obtained SPM A step of extracting a cross-sectional profile including a designated n-stage triangular structure from the image, and in the extracted cross-sectional profile, the left and / or right terraces at the bottom of the triangular structure are part of a straight line. The same terrace part on the left and / or the right is used for all terraces of a triangular structure different from the terrace. Is regarded as a part of a straight line, linear approximation is performed while matching the slope with the reference line, and the difference between the straight line and the reference line is set as an apparent height, and the apparent height is a standard sample. And a step of changing the height parameter of the apparatus so as to coincide with n times the height of 0.206 nm described in the above.

  As a second aspect, the SPM calibration method using the nanometer-scale measurement standard sample provided by the present invention includes the step of setting the standard sample in the SPM apparatus, and the position of the specified mesa structure on the standard sample surface. The step of moving the measurement range of the SPM with an optical microscope, the step of acquiring the SPM image of the triangular structure designated as the calibration location, and the appearance of the three vertices of the designated triangular structure from the acquired SPM image The step of extracting the upper coordinates and the calculation of three linear distances from the three extracted coordinates, which are the apparent lengths, respectively, and the apparent lengths match the lengths described in the standard sample, respectively. And a step of changing length parameters in the X direction, the Y direction, and the Z direction of the apparatus.

  Further, as a third aspect, the SEM calibration method using the nanometer scale measurement standard sample provided by the present invention includes a step of setting the standard sample in the SEM apparatus, and a specified mesa structure on the surface of the standard sample. A step of moving the SEM measurement range to a position, a step of performing SEM observation, tilting the standard sample so that it is in focus over the entire atomically flat surface on the surface of the mesa structure, and a triangular structure designated as a calibration location Obtaining an SEM image of the body, extracting apparent coordinates of the three vertices of the designated triangular structure in the obtained image, and calculating three linear distances from the extracted three coordinates. The length parameters in the X and Y directions of the apparatus so that each of the three apparent lengths corresponds to the length described in the standard sample. It is characterized in further comprising a step of changing.

  Since the nanometer-scale measurement standard sample of the present invention is composed of a single crystal diamond substrate that is stable even in the atmosphere having a flat surface and a step structure on the atomic scale, it is provided as a nanometer-scale measurement standard sample and scanned. It is suitably used in calibration of a type microscope.

  Diamond has the highest hardness in the substance and the lowest coefficient of thermal expansion in the substance, is stable in the atmosphere, has strong acid resistance and strong basicity, and is the most physically and chemically stable material. Therefore, it is the best material for measurement standard samples, and this property can be utilized.

  In particular, diamond terminated with hydrogen has a conductive layer on its surface, and therefore can be suitably used as a measurement standard sample in SEM and STM.

  In the nanometer-scale measurement standard sample of the present invention, since the shape of an equilateral triangle structure determined crystallographically is used, two-dimensional length and width on one screen are determined by the length of one known side. There is an advantage that calibration can be performed at the same time. Furthermore, since one side of the equilateral triangular structure is a straight line determined crystallographically, it can be a standard sample of linearity.

It is a figure explaining the preparation procedure of the mesa structure of the measurement standard sample of the nanometer scale of this invention. It is a figure explaining the measurement standard sample 1 of the nanometer scale of this invention. It is a figure explaining the measurement standard sample 2 of the nanometer scale of this invention. It is a figure explaining the triangular structure of {111} diamond. It is the 1st figure explaining the height calibration method of SPM using the measurement standard sample of the height of a single atom step. It is a 2nd figure explaining the height calibration method of SPM using the measurement standard sample of the height of a single atom step. It is the 3rd figure explaining the height calibration method of SPM using the measurement standard sample of the height of a single atom step. It is the 4th figure explaining the height calibration method of SPM using the measurement standard sample of the height of a single atom step. It is the 1st figure explaining the height calibration method of SPM by the present invention using n height measurement standard samples. It is a 2nd figure explaining the height calibration method of SPM by this invention using n measurement standard samples. It is the 3rd figure explaining the height calibration method of SPM by this invention using n measurement standard samples of height. It is the 4th figure explaining the height calibration method of SPM by the present invention using n measurement standard samples of height. It is a 1st figure explaining the length calibration method of SPM using the length measurement standard sample which has a triangular structure. It is a 2nd figure explaining the length calibration method of SPM using the length measurement standard sample which has a triangular structure. It is a 3rd figure explaining the length calibration method of SPM using the length measurement standard sample which has a triangular structure. It is a 4th figure explaining the length calibration method of SPM using the length measurement standard sample which has a triangular structure. It is a 1st figure explaining the length calibration method of SEM using the length measurement standard sample which has a triangular structure. It is a 2nd figure explaining the length calibration method of SEM using the length measurement standard sample which has a triangular structure. It is a 3rd figure explaining the length calibration method of SEM using the length measurement standard sample which has a triangular structure. It is a 4th figure explaining the length calibration method of SEM using the length measurement standard sample which has a triangular structure. It is a figure explaining the measurement standard sample 3 of the nanometer scale of this invention. It is the 1st figure explaining the length calibration method of SPM using the length measurement standard sample which has a plurality of triangular structures. It is the 2nd figure explaining the length calibration method of SPM using the length measurement standard sample which has a plurality of triangular structures. It is a 3rd figure explaining the length calibration method of SPM using the length measurement standard sample which has a some triangular structure. It is the 4th figure explaining the length calibration method of SPM using the length measurement standard sample which has a plurality of triangular structures. It is the 1st figure explaining the length calibration method of SEM using the length measurement standard sample which has a plurality of triangular structures. It is the 2nd figure explaining the length calibration method of SEM using the length measurement standard sample which has a plurality of triangular structures. It is a 3rd figure explaining the length calibration method of SEM using the length measurement standard sample which has a some triangular structure. It is the 4th figure explaining the length calibration method of SEM using the length measurement standard sample which has a plurality of triangular structures. FIGS. 2A to 2F are a plan view, a left side view, a right side view, a front view, a rear view, and a rear view, respectively, of the triangular structure of diamond having a height of 0.206 nm in FIG. It is. It is a figure explaining the measurement standard sample 4 of the nanometer scale of this invention.

  Hereinafter, modes for carrying out the present invention will be described. In one embodiment, the nanometer-scale measurement standard sample of the present invention is a nanometer-scale measurement standard sample having a flat surface and a step structure on an atomic scale formed on a single crystal diamond substrate. The scanning microscope described below is an atomic force microscope (AFM), a scanning tunneling microscope (STM), a scanning electron microscope (SEM), a scanning laser microscope (SLM), or the like.

  A single crystal diamond substrate used as an embodiment of a nanometer-scale measurement standard sample according to the present invention has a {111} plane or a plane having an off angle within 10 degrees from the {111} plane as a main plane. Is used. About the single crystal diamond substrate, one or a plurality of mesa structures are formed on the main surface. As a method for forming the mesa structure, photolithography, electron beam lithography, focused ion beam, or the like is used.

  A single crystal diamond substrate having a mesa structure formed by the above formation method is subjected to homoepitaxial growth with two-dimensional nucleation using chemical vapor deposition after removing surface deposits by means such as washing. By doing so, a convex triangular structure surrounded by an atomically flat terrace and a single step is formed on the surface of the mesa structure. The growth method is preferably a microwave plasma vapor deposition method. As the growth conditions, the microwave output is 400 to 5000 W, the pressure is 10 to 200 Torr, the substrate temperature is 400 to 1200 ° C., and the methane / hydrogen ratio in the introduced gas is 0.001 to 10%. Furthermore, it is preferable that the microwave output is 800 to 3000 W, the pressure is 20 to 100 Torr, the substrate temperature is 500 to 1000 ° C., and the methane / hydrogen ratio in the introduced gas is 0.005 to 2.0%.

  Here, an atomically flat surface is formed on the surface of the mesa structure, and a triangular structure is formed thereon. The surface of the structure is also an atomically flat surface and is an equilateral triangle controlled on an atomic scale. The island of this triangular structure is surrounded by steps, and the height per step of the step is 0.206 nm which is the single step height of the bilayer of diamond {111}. This height is determined from the lattice constant. That is, the equilateral triangular structure is a three-dimensional structure having a structure controlled on an atomic scale.

  Since the structure is an equilateral triangle, it has three vertices, three sides are equal, and each vertex has an angle of 60 degrees. This feature is very effective in determining the length. For example, since each vertex of a triangle gives its spatial coordinates, a straight line connecting two points is an absolute standard for length. Also, the two sides connecting the remaining vertices have the same length. Since the islands of this triangular structure are controlled on an atomic scale, their vertices become nanometer scales. Furthermore, since the surface can be observed with atomic resolution, each atom becomes an atomic scale.

  This single-step structure can be formed, for example, in multiple stages on the surface of the mesa structure by continuing the growth accompanied by two-dimensional nucleation (multi-step structure). For this reason, that is, this structure is a structure in which triangular structures are stacked in multiple stages, and has a size of n × 0.206 nm (n: 1, 2, 3,...) For measurement in the nanometer scale in the height direction. Standard samples can be provided.

  In addition, by forming a plurality of triangular structures having different lengths on one side, a standard sample having a plurality of length scales can be provided. For this reason, the length can be calibrated with a plurality of values, and the calibrated measurement system can perform more accurate measurement.

  Furthermore, since it is possible to perform growth while completely suppressing two-dimensional nucleation, it is possible to lengthen the uppermost triangular side by growing only in the lateral direction after nucleation by the above method. it can. That is, it is possible to provide a standard sample having an optimum structure for each measurement system.

  The standard sample manufactured by the above method is used for calibration of measured values in the vertical direction of the SPM as follows. After measuring a region having a triangular structure (for example, a surface of a mesa structure with a side of 5 μm) by SPM, the step structure on the surface of the region is expanded by AFM and measurement is performed.

  Next, image processing is performed so that each terrace is two-dimensionally horizontal. As an image processing method, cross-sectional observation is performed in parallel with the scanning direction, the height of the step corresponding to the same layer is measured, and the difference is brought close to zero. Here, by performing calibration using a plurality of levels of terraces facing the same triangular structure, terraces can be leveled more two-dimensionally, and calibration accuracy of height data can be further increased. .

  It is also possible to use an image processing method in which a histogram of the total height data of the measurement data is created and two-dimensional horizontal processing is performed so that the peak of the height value corresponding to each step height becomes sharper. . At this time, the height peak interval is set to 0.206 nm, and the scanner and apparatus of the SPM apparatus are calibrated.

  Further, as a standard height, not only single step 0.206 nm but also n × 0.206 nm (n: 1, 2, 3,...) Can be configured, and the optimum height for each AFM apparatus. Can be calibrated.

  The production of the structure of the nanometer-scale measurement standard sample according to the present invention is not limited to the embodiment using the single-step structure of the triangular structure formed on the single crystal diamond substrate. For example, a single crystal diamond substrate having a main surface with an off angle of 10 degrees or less from the (111) plane can be produced by wet processing, hydrogen plasma processing, or homoepitaxial growth, and formed on the main surface. The present invention is also applicable to an SPM height calibration plate using a single step structure or a multi-step structure.

  Diamond is stable in the air, and the structure of a standard sample once produced is unchanged. Therefore, by making the mesa structure a size that can be observed with an optical microscope or SLM, it is possible to easily measure the same part. This is because, for example, the measurement of the exact same part can be evaluated by using an SPM device in a completely different place, that is, the diamond standard sample of the present invention is not only a standard sample for calibrating the SPM but also an absolute value. It can also be applied as a nanometer-scale measurement standard substance.

  From the above, the present invention can be used for calibration of measured values not only in the SPM height but also in the lateral direction. For accurate calibration, after performing horizontal processing by the above method, the length of a straight line connecting the vertices of the triangular structure is measured using an SPM having sufficient accuracy. In this case, the diamond substrate is a standard sample in which the side length of the triangular structure is defined. Based on the standard, SPM lateral calibration can be performed in the same manner as described above.

  It is also possible to perform calibration by measuring the atomic spacing by measuring a diamond standard sample using an SPM apparatus having atomic resolution.

  The nanometer-scale measurement standard sample of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

A description will be given with reference to FIG. ZEP520A is applied to the surface of an Ib type diamond (111) substrate obtained by high-temperature and high-pressure synthesis, and the substrate is rotated by a spin coater to form a resist film (see FIG. 1a). Next, a desired portion of the resist was removed by electron beam exposure (see FIG. 1b), and then gold was deposited to provide a gold layer on the surface of the diamond substrate (see FIG. 1c). The resist portion with gold was then lifted off, leaving a gold layer deposited directly on the diamond (see FIG. 1d). Next, a diamond substrate was processed by applying a bias in O ₂ and CF ₄ and performing diamond etching with inductively coupled plasma to form a mesa structure (see FIG. 1e). Next, the gold layer was removed with a mixed acid, and the substrate was washed (see FIG. 1f). Thereafter, homoepitaxial growth with two-dimensional nucleation was performed using microwave plasma chemical vapor deposition. The growth conditions at that time were 1200 W, 50 Torr, hydrogen concentration 99.95%, and methane concentration 0.05%.

  FIG. 2A shows an image obtained by observing the surface of the grown mesa structure in the atmosphere with an atomic force microscope (AFM). It can be seen that after growth, the surface of the mesa structure is flatter than the substrate surface removed by etching. In addition, as shown in FIG. 2B, an atomically flat region and a triangular structure were formed on the surface of the mesa structure. Further, as shown in the sectional view of FIG. 2C, the step was 0.21 nm. That is, the step portion of the triangular structure is composed of a diamond (111) bilayer single step (0.206 nm). Thus, a measurement standard sample having a height of 0.206 nm can be provided using diamond that is stable even in the air.

  FIG. 3 shows an AFM image in which a triangular structure having a five-step single step structure is formed. As a result, the step difference of the step structure can be 5 × 0.206 = 1.03 nm. That is, as shown in FIG. 3, it is possible to provide a measurement standard sample having a height that is an integral multiple of 0.206 nm. Moreover, a measurement standard sample having a stepped step height may be used.

  Since the side of the triangular structure formed on the mesa structure surface is a straight line, it can be used as a measurement standard sample in the lateral direction. The horizontal measurement standard sample is preferably in the range of 1 nm to 5 μm. The state of the carbon atoms constituting the triangular structure formed on the mesa structure surface is shown in FIG. Actually, hydrogen and the like are terminated at these carbon atoms. The distance between the nearest carbon atoms in this same layer is 0.252 nm. That is, it is possible to use a length that is an integral multiple of 0.252 nm as a measurement standard sample.

An SPM height calibration method using a single measurement standard sample will be described. SPM is AFM or STM. The standard sample is, for example, a diamond sample having a standard height of 0.206 nm as shown in FIG.
(Step 1): A standard sample is set in the SPM apparatus.
(Step 2): The SPM measurement range is moved with the optical microscope to the designated mesa structure on the surface of the standard sample.
(Step 3); An SPM image including a triangular structure designated as a calibration location is acquired (see FIG. 6).
(Step 4): For example, a cross-sectional profile including a triangular structure is extracted from the acquired SPM image as a straight line BB ′ shown in FIG.
(Step 5); In the extracted cross-sectional profile, straight line approximation is performed by regarding the lower left and / or right terrace portions of the triangular structure as a part of a straight line, and this is used as a reference line (see FIG. 7). ).
(Step 6); In the extracted cross-sectional profile, the upper part of the triangular structure is regarded as a part of a straight line, linear approximation is performed while matching the inclination with the reference line, and the difference between the straight line and the reference line is apparently apparent. (See FIG. 8).
(Step 7): The height parameter of the apparatus is changed so that the apparent height matches the height of 0.206 nm described in the standard sample.

Next, an SPM height calibration method using n height measurement standard samples will be described. SPM is AFM or STM. The standard sample is a diamond sample having standard heights of n heights of 0.206 nm, 0.412 nm, 0.618 nm,..., That is, 0.206 × n (n ≧ 1). Here, a height calibration method using a height standard sample of n = 5 will be described with reference to FIG.
(Step 1): A standard sample is set in the SPM apparatus.
(Step 2): The SPM measurement range is moved with the optical microscope to the designated mesa structure on the surface of the standard sample.
(Step 3); An SPM image of a five-stage triangular structure designated as a calibration location is acquired (see FIG. 10).
(Step 4): For example, a cross-sectional profile including a five-stage triangular structure designated as a straight line BB ′ shown in FIG. 10 is extracted from the acquired SPM image.
(Step 5); In the extracted cross-sectional profile, the left and / or right terrace portions at the bottom of the triangular structure are regarded as a part of a straight line, and linear approximation is performed, and this is used as a reference line (FIG. 11). reference).
(Step 6): In the extracted cross-sectional profile, for all the terraces of the triangular structure different from the terraces, the same left and right terrace portions are regarded as a part of a straight line, and the reference line and the slope are set. Straight line approximation is performed while matching them, and the difference between these straight lines and the reference line is set as apparent heights h1, h2, h3, h4, and h5, respectively. (See Figure 12)
(Step 7); the apparent heights h1, h2, h3, h4, and h5 are set to the heights 0.206 nm, 0.412 nm, 0.618 nm, 0.824 nm, and 1.030 nm described in the standard sample. Change the height parameter of the device to match each other.

Next, an SPM length calibration method using a length measurement standard sample will be described. SPM is AFM or STM. The standard sample is, for example, a diamond sample having a triangular structure as shown in FIG.
(Step 1): A standard sample is set in the SPM apparatus.
(Step 2): The SPM measurement range is moved with the optical microscope to the designated mesa structure on the surface of the standard sample.
(Step 3); An SPM image of a triangular structure designated as a calibration location is acquired. (See Figure 14)
(Step 4); Apparent coordinates (x1, y1, z1), (x2, y2, z2), (x3, y3, z3) of the three vertices of the designated triangular structure from the acquired SPM image To extract. (See Figure 15)
(Step 5); Three straight line distances are calculated from the extracted three coordinates, and set as apparent lengths L1 ′, L2 ′, and L3 ′, respectively. (See Figure 16)
(Step 6): Length parameters in the X, Y, and Z directions of the apparatus so that the three apparent lengths match the lengths (L1, L2, L3) described in the standard sample, respectively. To change.

Next, an SEM length calibration method using a length measurement standard sample will be described. The standard sample is, for example, a diamond sample having a triangular structure as shown in FIG.
(Step 1): A standard sample is set in an SEM apparatus.
(Step 2): The SEM measurement range is moved to the position of the specified mesa structure on the standard sample surface.
(Step 3): SEM observation is performed, and the standard sample is tilted so that the whole surface of the atomically flat surface on the mesa structure is in focus.
(Step 4); An SEM image of the triangular structure designated as the calibration location is acquired. (See Figure 18)
(Step 5): In the acquired image, apparent coordinates (x1, y1), (x2, y2), (x3, y3) of the three vertices of the designated triangular structure are extracted. (See Figure 19)
(Step 6); Three straight line distances are calculated from the extracted three coordinates, and set as apparent lengths L1 ′, L2 ′, and L3 ′, respectively. (See Figure 20)
(Step 7): The length parameters in the X direction and the Y direction of the apparatus are changed so that the three apparent lengths match the lengths (L1, L2, L3) described in the standard sample, respectively. .

  FIG. 21 shows an image obtained by observing the convex surface after growth using the same growth method as described above in the atmosphere by AFM. 3 shows a structure in which three triangular structures are formed on the same convexity after growth. In this case, a straight line connecting arbitrary vertices of these different triangular structures can be used as a measurement standard sample in the horizontal direction. The lateral measurement standard sample is preferably in the range of 100 nm to 10 μm. The growth condition at this time is a condition capable of forming a two-dimensional structure. For example, the methane concentration in the gas phase can be increased to 0.5%.

Next, an SPM length calibration method using a length measurement standard sample will be described. SPM is AFM or STM. The measurement standard sample of this length is diamond having a different triangular structure on the convex near the center of the sample (see FIG. 22a). This measurement standard sample has, for example, three triangular structures on a convex surface as shown in FIG. 22b. A straight line connecting arbitrary vertices of the different triangular structures is used as a measurement standard sample for length. The length is, for example, 1 μm, 2 μm, and 3 μm as shown in FIG. 22c.
(Step 1): A standard sample is set in the SPM apparatus.
(Step 2): The SPM measurement range is moved with the optical microscope to the designated mesa structure on the surface of the standard sample.
(Step 3); An SPM image of a triangular structure designated as a calibration location is acquired (see FIG. 23).
(Step 4); Apparent coordinates (x1, y1, z1), (x2, y2, z2), (x3, y3, z3) of the three vertices of the designated triangular structure from the acquired SPM image Is extracted (see FIG. 24).
(Step 5); Three straight line distances are calculated from the extracted three coordinates and set as apparent lengths L1 ′, L2 ′, and L3 ′, respectively (see FIG. 25).
(Step 6): Length parameters in the X, Y, and Z directions of the apparatus so that the three apparent lengths match the lengths (L1, L2, L3) described in the standard sample, respectively. To change.

Next, an SEM length calibration method using a length measurement standard sample will be described. The measurement standard sample of this length is diamond having a different triangular structure on the convex near the center of the sample (see FIG. 26a). This measurement standard sample has, for example, three triangular structures on a convex surface as shown in FIG. 26b. The periphery of the triangular structure is made of a material having an electron affinity or work function different from that of diamond. A straight line connecting arbitrary vertices of the different triangular structures is used as a measurement standard sample for length. The length is, for example, 1 μm, 2 μm, and 3 μm as shown in FIG. 26c.
(Step 1): A standard sample is set in an SEM apparatus.
(Step 2): The SEM measurement range is moved to the position of the specified mesa structure on the standard sample surface.
(Step 3): SEM observation is performed, and the standard sample is tilted so that the whole surface of the atomically flat surface on the mesa structure is in focus.
(Step 4); An SEM image of the triangular structure designated as the calibration location is acquired (see FIG. 27).
(Step 5): In the acquired image, the apparent coordinates (x1, y1), (x2, y2), (x3, y3) of the three vertices of the designated triangular structure are extracted (see FIG. 28). .
(Step 6); Three straight line distances are calculated from the extracted three coordinates and set as apparent lengths L1 ′, L2 ′, and L3 ′, respectively (see FIG. 29).
(Step 7): The length parameters in the X direction and the Y direction of the apparatus are changed so that the three apparent lengths match the lengths (L1, L2, L3) described in the standard sample, respectively. .

  Further, by using an etching method, a concave triangular structure can be formed on the diamond surface. FIG. 31a shows a triangular structure formed by etching a crystal defect portion in a microwave plasma CVD chamber using hydrogen plasma treatment at a hydrogen flow rate of 400 sccm, an input power of 1200 W, a pressure of 50 Torr, and a sample temperature of 850 ° C. Is shown. The step in the sectional view of the concave triangular structure (see FIG. 31b) is 2.06 nm, and this triangular structure is a height measurement standard sample composed of a 10-step single step structure. Measurement of the height and length of a diamond having a triangular structure formed on the above-mentioned substrate The diamond having the concave triangular structure using the same method as the standard sample (a structure in which the height direction is reversed) Can also be used as a measurement standard sample for height and length. The crystal defect can be formed at an intentional location by using, for example, an electron or ion beam or an indentation method. The crystal defect portion can be found using X-ray topography.

  The present invention can provide a measurement standard sample of height and / or length on the nanometer or atomic scale that is stable even in the atmosphere. In recent years, nanometer-scale structures have been produced in the fields of nanoelectronics typified by silicon LSI, biotechnology, and medicine. Therefore, the present invention makes it possible to correctly measure whether the fabricated structure is the designed height and / or length, and diagnoses the processing apparatus and process and the reliability of the fabricated device characteristics or functions. It can be expected to secure.

Claims (11)

A single crystal diamond substrate with an off angle of 10 degrees or less from the main surface {111} plane or {111} plane, and one step height formed on the single crystal diamond substrate; 0.206 nm atomically flat terrace surface A triangular structure having n layers (n ≧ 1).
A measurement standard sample on a nanometer scale, characterized in that a straight line of a triangle connecting two vertices of the triangular structure is used as a standard of length. A single crystal diamond substrate with an off angle of 10 degrees or less from the main surface {111} plane or {111} plane, and one step height formed on the single crystal diamond substrate; 0.206 nm atomically flat terrace surface A triangular structure having n layers (n ≧ 1).
A measurement standard sample on a nanometer scale, wherein one side of the triangle of the triangular structure is used as a standard for linearity. A single crystal diamond substrate with an off angle of 10 degrees or less from the main surface {111} plane or {111} plane, and one step height formed on the single crystal diamond substrate; 0.206 nm atomically flat terrace surface A triangular structure having n stages (n ≧ 1).
A nanometer-scale measurement standard sample, characterized in that the step difference of the triangular structure is used as a standard of height. The measurement standard sample of the nanometer scale according to any one of claims 1 to 3, wherein the triangle of the triangular structure is a regular triangle. 4. The nanometer-scale measurement standard sample according to claim 1, wherein a length of one side of the triangle of the triangular structure is shorter as a triangle located at an upper stage. 5. The nanometer-scale measurement standard according to any one of claims 1 to 3, wherein the atomically flat terrace surface includes a plurality of triangular structures having different lengths on one side on the main surface. sample. 4. The nanometer-scale measurement standard sample according to claim 1, wherein the single crystal diamond of the single crystal diamond substrate has a hydrogen termination. 5. The nanometer-scale measurement standard sample according to any one of claims 1 to 3, wherein the nanometer-scale measurement standard sample is for a scanning microscope. Setting a standard sample in a scanning probe microscope (SPM) device;
Moving the SPM measurement range with an optical microscope to a specified mesa structure on the standard sample surface;
Acquiring an SPM image of an n-stage (n ≧ 1 integer) triangular structure designated as a calibration location;
Extracting a cross-sectional profile including a designated n-stage triangular structure from the acquired SPM image;
In the extracted cross-sectional profile, a straight line approximation is performed by regarding the same left and right terrace portions of the triangular structure as a part of a straight line, and this is used as a reference line, which is different from the terrace. For all the terraces of the triangular structure, the left and / or the same terrace portion is regarded as a part of a straight line and a straight line approximation is performed while matching the inclination with the reference line, and the straight line and the reference line are And changing the height parameter of the apparatus so that the apparent height matches n times the height of 0.206 nm described in the standard sample, respectively,
Calibration method for SPM using a nanometer-scale measurement standard sample. Setting the standard sample in the SPM device;
Moving the SPM measurement range with an optical microscope to a specified mesa structure on the standard sample surface;
Obtaining an SPM image of a triangular structure designated as a calibration location;
Extracting apparent coordinates of the three vertices of the designated triangular structure from the acquired SPM image;
Three straight line distances are calculated from the extracted three coordinates, and are set as apparent lengths, and the X direction and Y direction of the apparatus are set so that the apparent lengths match the lengths described in the standard sample, respectively. Changing the direction parameter and the length parameter in the Z direction;
Calibration method for SPM using a nanometer-scale measurement standard sample. Setting the standard sample in the SEM apparatus;
Moving the SEM measurement range to the position of the specified mesa structure on the standard sample surface;
Performing a SEM observation and tilting the standard sample so that the whole surface of the mesa structure on the atomically flat surface is in focus;
Obtaining an SEM image of a triangular structure designated as a calibration location;
Extracting the apparent coordinates of the three vertices of the designated triangular structure in the acquired image;
Three straight line distances are calculated from the three extracted coordinates, and are set as apparent lengths, respectively, and the X direction of the apparatus is set so that the three apparent lengths correspond to the lengths described in the standard sample, respectively. And changing the length parameter in the Y direction;
SEM calibration method using a nanometer-scale measurement standard sample.