Patent Description:
Concerning semiconductor micronization, the road map IRDS (International Roadmap for Device and System) formulated in <NUM> by IEEE specifies goals of a pattern size in a logic device until <NUM>, in which a half pitch is <NUM>, and a line edge roughness (LER) is less than <NUM>, and pattern manufacturing methods and inspection methods for the goals have been discussed. Note that the LER represents the unevenness of the edge of a resist pattern used as a mask in a lithography technique.

As an LER evaluation method, measurement using a microscope capable of performing observation in a nanometer size (having a resolution in a nanometer size), such as an atomic force microscope (AFM), can be used. In measurement of this type, to accurately measure roughness using an image output from a measurement device such as a SEM, noise included in an image signal is removed (see Patent literature <NUM>). In this technique, to remove noise included in the image signal, a standard sample whose LER is controlled in advance is used.

Also, in a measurement technique such as AFM, to guarantee a resolution or an error, measurement by a probe in a nanometer size is executed using a standard sample whose minimum structure has a size of <NUM> or less, and the resolution is obtained from obtained image data (see Patent literature <NUM>). In this standard sample, however, although the size is decided, the shape of the pattern edge is indefinite.

On the other hand, as a currently used standard sample, a standard sample prepared by the NIST (the National Institute of Standards and Technology) in U. This standard sample is a nanowire with a minimum size of <NUM>.

In Japan, the National Institute of Advanced Industrial Science and Technology (AIST) conducts certifications in the length direction using a tungstendot array. However, the minimum size of this standard sample is <NUM>, which is not small enough to evaluate presently problematic unevenness on several nm order.

Also, although the AIST conducts certifications for structures of <NUM> or more, no technique is specified yet concerning how to correctly measure a shape whose size is on the order of <NUM>.

Further, <CIT> describes a semiconductor member having a pattern made of an array of first diffraction gratings and also including an array of second diffraction gratings different from the first diffraction grating in a predetermined cycle.

It is considered that the above-described standard sample is manufactured using, for example, semiconductor device manufacturing techniques such as a deposition technique, a lithography technique, and an etching technique. However, in a periodical pattern formed by these manufacturing methods, an LER with a nanometer size is generated in the edge portion of the pattern, and it is difficult to clarify the difference from a defect with a nanometer size. For this reason, it is not sufficient as a standard sample.

The present invention has been made to solve the above-described problem, and has as its object to provide a standard sample capable of evaluating a line edge roughness on the order of <NUM>. Means of Solution to the Problem.

According to claim <NUM> of the present invention, there is provided a standard sample used to evaluate a microscope capable of performing observation in a nanometer size, including a scanning probe microscope, comprising a substrate made of a crystal with a main surface that is a (<NUM>) plane, and a recess formed from the main surface of the substrate to an inside of the substrate, wherein the recess includes a side surface that forms one plane perpendicular to the main surface of the substrate, and the side surface is a facet surface and is a tilting surface tilted from a (<NUM>) plane.

According to claim <NUM> of the present invention, there is also provided a manufacturing method of a standard sample used to evaluate a microscope capable of performing observation in a nanometer size, including a scanning probe microscope, comprising a first step of forming a mask pattern including an opening with a linear portion in a planar view on a substrate made of a crystal with a main surface that is a (<NUM>) plane, and a second step of etching the substrate by etching processing with crystal anisotropy using the mask pattern as a mask, thereby forming a recess formed from the main surface of the substrate to an inside of the substrate, wherein the recess includes a side surface that forms one plane perpendicular to the main surface of the substrate, and the side surface is a facet surface and is a tilting surface tilted from a (<NUM>) plane.

As described above, according to the present invention, since a recess including a side surface that is a facet surface and is a tilting surface tilted from the (<NUM>) plane is formed in a substrate whose main surface is the (<NUM>) plane, it is possible to provide a standard sample capable of evaluating a line edge roughness on the order of <NUM>.

A manufacturing method of a standard sample according to the embodiment of the present invention will now be described with reference to <FIG>. This manufacturing method is a manufacturing method of a standard sample used to evaluate a microscope capable of performing observation in a nanometer size (having a resolution in a nanometer size), including a scanning probe microscope.

First, as shown in <FIG>, a mask pattern <NUM> is formed on a substrate <NUM> that is made of a crystal and includes a main surface that is the (<NUM>) plane (first step). The mask pattern <NUM> includes an opening <NUM> with a linear portion in a planar view. The substrate <NUM> is made of, for example, a single crystal of silicon. The substrate <NUM> can also be made of a crystal of GaAs or InP. The opening <NUM> has, for example, a rectangular shape in a planar view. For example, the opening <NUM> is formed such that a side surface 103a of a side in the longitudinal direction of a rectangle in a planar view becomes a surface parallel to the facet surface of the substrate <NUM> made of single crystal silicon, which is tilted by <NUM>° from the (<NUM>) plane. For example, if the longitudinal direction of the above-described rectangle is set to extend in a direction rotated by <NUM>° from the <<NUM>> direction, the side surface 103a can be the surface parallel to the facet surface tilted by <NUM>° from the (<NUM>) plane.

A plurality of openings <NUM> are formed. The mask pattern <NUM> is called a line-and-space pattern in which, for example, the plurality of openings <NUM> form a space pattern. For example, the line width can be <NUM>, and the space width can be <NUM>. For example, the mask pattern <NUM> can be formed by a known lithography technique.

Next, as shown in <FIG>, using the mask pattern <NUM> as a mask, the substrate <NUM> is etched by etching processing with crystal anisotropy, thereby forming recesses <NUM> from the main surface of the substrate <NUM> to the inside of the substrate <NUM> (second step). For example, for the substrate <NUM> made of single crystal silicon, etching processing with crystal anisotropy can be performed by wet etching using an alkaline solution as an etchant. As is well known, if single crystal silicon is etched using an alkaline solution, the (<NUM>) plane is hardly etched because the etching rate is lower by <NUM>/<NUM> than on the (<NUM>) plane or (<NUM>) plane.

Hence, if the substrate is etched by an alkaline solution using the mask pattern <NUM> as a mask, the (<NUM>) plane of the substrate <NUM>, which is exposed to the bottom surface of each opening <NUM>, is etched, and the etching progresses in the thickness direction of the substrate <NUM>. On the other hand, side surfaces <NUM> of the recesses <NUM>, which are formed along with the progress of the etching and are parallel to the side surfaces 103a of the openings <NUM>, are almost (<NUM>) planes, and the etching hardly progresses. As a result, a cross section of the recess <NUM> perpendicular to the longitudinal direction has a rectangular shape. Note that since the opening <NUM> of the mask pattern <NUM> has a rectangular shape in a planar view, the opening of the recess <NUM> has a rectangular shape in a planar view, and the recess <NUM> is formed into, for example, a rectangular parallelepiped shape.

Note that in the above-described etching using an alkaline solution, for example, an aqueous solution of potassium hydroxide with a concentration of <NUM> wt% is used as the alkaline solution, and the etching processing is performed for, for example, about <NUM>. After the recesses <NUM> are formed in this way, the mask pattern <NUM> is removed. Then, as shown in <FIG>, a standard sample with the recesses <NUM> formed in the substrate <NUM> is obtained. The recess <NUM> in this standard sample includes the side surface <NUM> that forms one plane perpendicular to the main surface of the substrate <NUM>. The side surface <NUM> is a facet surface and is a tilting surface tilted from the (<NUM>) plane (for example, tilted by <NUM>°).

As described above, the side surface <NUM> formed by anisotropic etching is a facet surface tilted from the (<NUM>) plane of the single crystal silicon. For this reason, the edge portion of the recess <NUM>, which is formed by the main surface of the substrate <NUM> and the side surface <NUM>, has a level difference by a step (atomic step) <NUM> of the side surface <NUM>, as shown in <FIG>. If the side surface <NUM> is tilted by <NUM>° from the (<NUM>) plane, the above-described level difference has a size of about <NUM> and periodically occurs at an interval of <NUM>. Hence, a periodical level difference structure on a nanometer order is formed in the edge portion of the recess <NUM>, which is formed by the main surface of the substrate <NUM> and the side surface <NUM>. This standard sample can be used to calibrate a scanning probe microscope such as an AFM or an electron microscope such as a critical dimension-scanning electron microscope (CD-SEM).

Note that the size of the level difference by the step <NUM> changes depending on the angle of tilt from the (<NUM>) plane. If the angle of tilt from the (<NUM>) plane becomes large, the level difference by the step <NUM> also becomes large. Hence, the angle of tilt from the (<NUM>) plane can be adapted to the desired size of the level difference.

A case where the substrate <NUM> is made of a single crystal of silicon has been described above. However, the present invention is not limited to this. The substrate <NUM> can also be made of a crystal of InP or GaAs. In this case, the side surface <NUM> can be a tilting surface tilted from the (<NUM>)A plane.

For example, if the substrate <NUM> is made of InP, an aqueous solution of bromine and hydrobromic acid or an aqueous solution of hydrochloric acid and phosphoric acid can be used as an etchant. In this wet etching, the (<NUM>)A plane of InP is difficult to etch as compared to other crystal surfaces. Hence, etching processing with crystal anisotropy as described above can be performed, and the recesses <NUM> can be formed using the mask pattern <NUM>.

Also, if the substrate <NUM> is made of GaAs, a liquid mixture of an aqueous ammonia solution and a hydrogen peroxide solution can be used as an etchant. In this wet etching as well, the (<NUM>)A plane of GaAs is difficult to etch as compared to other crystal surfaces. Hence, etching processing with crystal anisotropy as described above can be performed, and the recesses <NUM> can be formed using the mask pattern <NUM>.

As described above, according to the present invention, a recess including a side surface that is a facet surface and is a tilting surface tilted from the (<NUM>) plane is formed in the substrate whose main surface is the (<NUM>) plane. It is therefore possible to provide a standard sample capable of evaluating a line edge roughness on the order of <NUM>.

Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications and combinations can be made by those having ordinary knowledge in the art within the technical concept of the present invention as in the appended claims.

Claim 1:
A standard sample used to evaluate a microscope capable of performing observation in a nanometer size, including a scanning probe microscope, comprising:
a substrate (<NUM>) made of a crystal with a main surface that is a (<NUM>) plane; and
a recess (<NUM>) formed from the main surface of the substrate (<NUM>) to an inside of the substrate (<NUM>),
wherein the recess (<NUM>) includes a side surface (<NUM>) that forms one plane perpendicular to the main surface of the substrate (<NUM>), and an edge portion formed by the main surface of the substrate (<NUM>) and the side surface (<NUM>),
characterized in that
the side surface (<NUM>) is a facet surface and is a tilting surface tilted from a (<NUM>) plane, and
the edge portion includes a periodical level difference structure on a nanometer order.