Si nanostructure standard material of 5 nm or less, and manufacturing method therefor

Abstract

The present invention relates to a Si nanostructure standard material of 5 nm or less, and a manufacturing method therefor, and to a microscope evaluation method using the standard material. Specifically, the present invention provides a standard material having a reduced critical dimension through two etching processes, and thus can improve the evaluation precision of a microscope.

Description

Standard material for SI nanostructures of 5 nm or less and method for manufacturing the same

[0001] The present invention relates to a standard material for a Si nanostructure of 5 nm or less and a method for producing the same, and to a microscopic evaluation method using the standard material.

[0002] Atomic force microscopes (AFMs) and scanning electron microscopes (SEMs) are nano-measurement instruments that measure nanoscale critical dimensions (CDs) and pitches in semiconductor device manufacturing processes. Current measurements using nano-measurement instruments can deviate from actual values ​​depending on the conditions under which the instrument is used.

[0003] Particularly with the recent advancements in the system semiconductor industry, the ability to accurately measure line widths, pitches, and step heights, which are just a few nanometers in size, has become one of the most critical process analysis issues in the semiconductor industry. Furthermore, as semiconductor device sizes shrink, the development of even smaller devices necessitates precise definition of the difference between measured and actual values.

[0004] At this time, in order to calibrate the microscope by evaluating the difference between the actual value and the measured value, a standard material manufactured with a certain size value is used, and the microscope is calibrated by comparing the actual value and the measured value of the line width of the standard material.

[0005] However, conventional standard materials used in microscopic evaluation were manufactured to have line widths and pitches equal to or greater than 8–10 nm, and it was difficult to manufacture standard materials with line widths and pitches lower than these. Thus, the problem arose that conventional standard materials could not measure line widths and pitches below 8 nm.

[0006] According to one aspect of the present disclosure, a standard material having a reduced line width can be provided that allows for evaluating the performance of a microscope in finer units.

[0007] The present invention is a nano-structure standard material used for performance evaluation of a microscope, comprising: a plurality of base layers having a predetermined thickness and spaced apart at regular intervals; and a plurality of intermediate layers interposed between the plurality of base layers; wherein the plurality of base layers and the plurality of intermediate layers are alternately laminated to form a multi-layer structure.

[0008] On one side of the multilayer structure, a convex portion having a relatively high height and a concave portion formed to be concave by being sunken to a certain depth and having a relatively low height compared to the convex portion are formed, and the convex portion and the concave portion are each formed in multiple numbers so that the convex portion and the concave portion form a repetitive arrangement, and the convex portion may be formed from the base layer, and the concave portion may be formed from the intermediate layer and a portion of the base layer at both ends where the intermediate layer is interposed.

[0009] The above base layer is made of Si, and the above intermediate layer is It is made of, and the convex and concave portions can be formed through two etching processes.

[0010] The plurality of convex portions may each have different thicknesses, and the thickness of the plurality of convex portions may be configured to increase from one side to the other side along the direction in which the multilayer structure is laminated.

[0011] The thickness of the thinnest convex portion among the plurality of convex portions may be 3 nm or more and 5 nm or less.

[0012] The thickness of the above base layer may be 8 nm or more.

[0013] It may further include a support layer supporting both ends of the above multilayer structure.

[0014] The present invention relates to a method for manufacturing a standard material including a plurality of base layers and a plurality of intermediate layers each inserted between the plurality of base layers, which are used for performance evaluation of a microscope, and which may include a lamination process in which the plurality of base layers and the plurality of intermediate layers are alternately laminated to form a multilayer structure; a first etching process in which the plurality of intermediate layers are removed by a predetermined depth so as to be sunken compared to the base layer; an oxidation process in which an oxide film having a predetermined thickness is formed on the surfaces of the base layer and the intermediate layer; and a second etching process in which the oxide film is removed.

[0015] By the second etching process, a convex portion having a relatively high height and a concave portion having a relatively low height and a predetermined depth lower than the convex portion are formed on one surface of the multilayer structure, and the convex portion and the concave portion are formed in a repetitive arrangement on one surface of the multilayer structure, and the convex portion may be formed from the base layer, and the concave portion may be formed from the intermediate layer and a portion of the base layer at both ends where the intermediate layer is interposed.

[0016] The above base layer is made of Si, and the above intermediate layer is It can be made of.

[0017] The thickness of the above oxide film may be 1.5 nm or more and 2.5 nm or less. The thickness of the base layer may be 8 nm or more.

[0018] The present invention relates to a method for evaluating the performance of a microscope using a standard material, comprising: a step of determining an authentication value based on a predetermined standard by using the actual thickness of the convex portion as an authentication value; a step of placing the standard material on a specimen stage of a microscope and illuminating one side of a multilayer structure in which the convex portion and the concave portion are formed; a step of measuring the thickness of the convex portion using a microscope; and a step of evaluating the performance of the microscope by comparing the authentication value with the thickness of the convex portion measured using the microscope.

[0019] The criterion for determining the above authentication value can be determined by the lattice constant value of Si.

[0020] A standard material according to one embodiment of the present disclosure is manufactured to have a minimum line width of 5 nm or less, providing the advantage of enabling the performance of the microscope to be evaluated in finer units.

[0021] Additionally, by evaluating the performance of the microscope with a standard material according to one embodiment of the present disclosure, the measurement accuracy and reliability of the nanometer can be improved.

[0022] Figure 1 schematically illustrates a front view of a standard material according to an example of the present disclosure.

[0023] Figure 2 is an enlarged view of area A of Figure 1.

[0024] Figure 3 schematically illustrates a process for manufacturing a standard material according to an example of the present disclosure.

[0025] Figure 4 is a flowchart showing a manufacturing process of a standard material according to an example of the present disclosure.

[0026] FIG. 5 is a drawing illustrating a method for evaluating a microscope using a standard material according to an example of the present disclosure.

[0027] FIG. 6 is a graph showing the quantification of the spatial resolution measurement of a microscope using a standard material according to an example of the present disclosure.

[0028] Hereinafter, the present disclosure will be described in detail with reference to the attached drawings. However, these are merely exemplary and the present disclosure is not limited to the specific embodiments described as examples.

[0029] A standard material (1000) according to an example of the present disclosure is a material used for evaluating the performance of a microscope, and can be widely applied in the fields of atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and other microscopy techniques for observing nano-scale objects.

[0030] Specifically, a standard material (1000) according to an example of the present invention can be used for the purpose of evaluating spatial resolution during performance evaluation of a microscope, correcting magnification of a microscope, etc., thereby providing an advantage of improving the evaluation precision of a microscope.

[0031] Hereinafter, a standard material (1000) and its manufacturing method according to an example of the present invention will be described.

[0032] Hereinafter, FIG. 1 is a front view of a standard material (1000) according to an example of the present disclosure, and the standard material (1000) according to an example of the present disclosure will be described with reference thereto.

[0033] The standard material (1000) is a nanostructure used for evaluating the performance of a microscope, and includes a plurality of base layers (10) and a plurality of intermediate layers (20) interposed between the plurality of base layers (10).

[0034] A plurality of base layers (10) and a plurality of intermediate layers (20) are alternately laminated to form a multilayer structure (100) having multiple layers as shown in FIG. 1. Furthermore, the standard material (1000) may further include a support layer (30) that supports both ends of the multilayer structure (100) to maintain the shape of the multilayer structure (100). That is, as in FIG. 1, the multilayer structure (100) may be arranged between the support layers (30) located at the leftmost and rightmost positions, respectively, and the multilayer structure (100) may form a multilayer structure in which base layers (10) and intermediate layers (20) are alternately laminated.

[0035] At this time, the base layer (10) and the intermediate layer (20) may be composed of different materials. Through a structure in which the base layer (10) and the intermediate layer (20) composed of different materials are alternately laminated, the base layer (10) is maintained as is during the etching process, but only a portion of the intermediate layer (20) can be removed, and thereby a high convex portion (300) and a low concave portion (400) are formed on one surface of the multilayer structure (100), resulting in a height difference on one surface of the multilayer structure (100).

[0036] When a height difference exists on one surface of a multilayer structure (100) and the surface with the height difference is illuminated and observed under a microscope, the part with the higher height is relatively close to the objective lens of the microscope, so a bright image is generated, and the part with the lower height is relatively far from the objective lens of the microscope, so a dark image is generated.

[0037] In this way, by measuring the gap between the different thicknesses of the bright and dark parts of the image observed through the microscope and comparing it with the certified values ​​of the standard material (100), the spatial resolution of the microscope can be evaluated, magnification can be corrected, etc.

[0038] Next, FIG. 2 is a drawing showing an enlarged portion of part A of FIG. 1, and with reference to this, the convex portion (300) and the concave portion (400) formed on one surface of the multilayer structure (100) will be described.

[0039] One side of the multilayer structure (100), i.e., the upper side of FIG. 2, may be provided with a convex portion (300) that is a relatively high portion and a concave portion (400) that is formed by being sunken to a certain depth at the height of the convex portion (300). One side of the multilayer structure (100) is provided with a plurality of convex portions (300) and concave portions (400), and has a shape in which one convex portion (300) and one concave portion (400) form a unit and are repeatedly arranged.

[0040] At this time, the convex portion (300) may be formed from the base layer (10), and the concave portion (400) may be formed from the intermediate layer (20) and a portion of the base layer (10a, 10b) at both ends where the intermediate layer (20) is interposed.

[0041] Looking at the upper surface of FIG. 2, which is a surface having a convex portion (300) and a concave portion (400) among the surfaces of the multilayer structure (100), the surface of the part having the convex portion (300) is entirely made of a base layer (10), whereas the surface of the part having the concave portion (400) is made of a middle layer (20) in the central surface, the left surface of the central portion is made of a base layer (10a) arranged on the left side of the middle layer (20), and the right surface of the central portion is made of a base layer (10b) arranged on the right side of the middle layer (20).

[0042] This structure is formed by etching the multilayer structure (100) (first etching process), oxidizing the base layer (10) to form an oxide film (oxidation process), and then re-etching (second etching process). This feature will be described later in FIG. 3.

[0043] Meanwhile, the plurality of convex portions (300) may have different thicknesses, and the thickness of the plurality of convex portions (300) may be configured to increase from one side to the other side along the direction in which the multilayer structure (100) is laminated. In this case, the thickness of the plurality of convex portions (300) may be determined according to a designated authentication value, so that the characteristics of the microscope may be evaluated by comparing the measured thickness value of the convex portions (300) with the designated authentication value.

[0044] In other words, as shown in FIG. 1, n convex portions (300) can be formed in a multilayer structure (100), and if the convex portions located on the far left among the n convex portions are respectively referred to as a first convex portion, a second convex portion, a second convex portion, and an n-th convex portion, the thickness from the first convex portion to the n-th convex portion can be configured to gradually increase, and the thickness of each convex portion can be determined according to a specified authentication value.

[0045] The thickness of the first convex portion, which is the thinnest convex portion among the n convex portions, may be 3 nm or more and 5 nm or less, and the details thereof will be described later.

[0046] Meanwhile, the base layer (10) is made of silicon (Si, hereinafter referred to as Si), and the intermediate layer (20) is made of silicon dioxide ( , below It can be made up of (called).

[0047] At this time, the Si forming the base layer (10) may be purified Si in a pure form, or may be a material grown as a single crystal. Si is a core material in the semiconductor industry, and since single crystal growth and processing technology is highly developed, it is advantageous in reproducing identical samples, making it suitable for adoption as a length standard.

[0048] The intermediate layer (20) can be removed at a certain portion through hydrogen fluoride (HF, hereinafter referred to as HF) as in Equation 1 below. It can be made of.

[0049] [Formula 1]

[0050] Referring to FIG. 3 below, a standard material (1000) and a method for manufacturing the same according to an example of the present disclosure are described.

[0051] Figures 3(a) to 3(d) are drawings sequentially showing the steps in which a standard material (1000) is manufactured. As in Figure 3(a), a base layer (10) made of Si and The intermediate layers (20) made of have the same height and can be alternately stacked to form a multilayer structure (100).

[0052] At this time, an etching process (hereinafter referred to as the first etching process) is performed to expose one side of the multilayer structure (100), i.e., the upper surface of Fig. 3(a) to HF gas or an aqueous solution containing HF. The intermediate layer (20) composed of Si is removed by corrosion to a predetermined depth, and as shown in Fig. 3(b), the intermediate layer (20) is reduced in height compared to the base layer (10) composed only of Si.

[0053] The surface of the multilayer structure (100) can be oxidized in a state as in Fig. 3(b), and after this oxidation process, an oxide film (50) can be formed on the surface of the multilayer structure (100) as in Fig. 3(c). Si and When oxidizing a multilayer structure (100) composed of, its surface passes through [Formula 2] below. An oxide film (50) having a predetermined thickness can be formed.

[0054] [Formula 2]

[0055] After the oxide film (50) is formed, a re-etching process (hereinafter referred to as the second etching process) is performed. The oxide film (50) formed by the oxide film is corroded and removed.

[0056] Hereinafter, a comparison is made between the material of FIG. 3(b) that has undergone only the first etching process and the standard material (100) according to an example of the present disclosure that has undergone up to the second etching process of FIG. 3(d). Even in the case where only the first etching process has been performed, the heights of the base layer (10) and the intermediate layer (20) are different from each other, so that a relatively high portion and a relatively low portion may be formed. However, in this case, the thickness of the relatively high portion If you say so, There is a problem that the value cannot be manufactured at a level below 5nm, which is the desired level.

[0057] This is related to the smallest unit in which quantum dots of silicon appear. According to previous literature (F. Iacona, J. Appl. Phys. 88, 8165 (2000)), quantum dots are formed in Si and SiO2 of 0.9 nm to 2.6 nm, and in Si of 8 nm or more, quantum dots are not formed and the Si structure is maintained.

[0058] Therefore, it can be seen that the shape of the structure is maintained and can function as a standard material when the thickness of the base layer (10) and the intermediate layer (20) is at least 8 nm or more. In other words, when only the first etching process is performed, the thickness of the relatively high part, i.e. the base layer (10) ( ) can be at least 8 nm, which raises the problem that the microscope cannot be evaluated at units finer than 8 nm.

[0059] However, when the oxidation process and the second etching process are performed after the first etching process, a portion of the surface of the base layer (10) and the intermediate layer (20) is oxidized to form an oxide film (50) having a predetermined thickness, and when the oxide film (50) is removed through the second etching process, the thickness is reduced by the thickness of the oxide film formed on the left and right sides of the base layer (100). ) is formed. That is, according to one embodiment of the present disclosure, the thickness of the high portion in the material that has undergone only the first etching process through two etching processes ( ) with reduced thickness ( A standard material (1000) having can be provided.

[0060] The thickness of the base layer (10) may be 8 nm or more to maintain its shape, and at this time, the thickness of the oxide film (50) may be 1.5 nm to 2.5 nm. An oxide film (50) may be formed on each of the left and right sides of the base layer (10), so that when the oxide film (50) is removed, the thickness of the convex portion (300) formed from the base layer (10) may be 3 nm or more (corresponding to the value obtained by subtracting 2.5 nm, which is the thickness of the left oxide film, and 2.5 nm, which is the thickness of the right oxide film from the thickness of the base layer (10) of 8 nm) and 5 nm or less (corresponding to the value obtained by subtracting 1.5 nm, which is the thickness of the left oxide film, and 1.5 nm, which is the thickness of the right oxide film from the thickness of the base layer (10) of 8 nm).

[0061] As described above, a standard material according to an example of the present disclosure can be configured so that the thickness of the thinnest convex portion among the plurality of convex portions (300) is 3 nm or more and 5 nm or less.

[0062] The multilayer structure (100) can be configured so that the thickness of the n convex portions (300) increases from one side to the other side of the multilayer structure (100), so that in order to form the convex portions (300) from the base layer (10), the thickness of the base layer (10) ) can also be configured to increase from one side to the other side of the multilayer structure (100).

[0063] For example, as shown in Fig. 3(d), let the thicknesses from the first convex portion to the eighth convex portion according to the specified authentication value be 3 nm, 4 nm, 5 nm, 6 nm, 8 nm, 10 nm, 15 nm, and 20 nm, respectively. In order to form eight convex portions having the above-described thicknesses, the base layer (10) forming each convex portion can be manufactured to have a thickness of 8 nm, 9 nm, 10 nm, 11 nm, 13 nm, 15 nm, 20 nm, and 25 nm, as shown in FIG. 3(a), and through a process of forming an oxide film (50) having a thickness of 2.5 nm (oxidation process) and a process of removing the formed oxide film (second etching process), as shown in FIG. 3(c), the first to eighth convex portions having a thickness (3 nm, 4 nm, 5 nm, 6 nm, 8 nm, 10 nm, 15 nm, and 20 nm) corresponding to a designated authentication value can be formed.

[0064] Next, a method for manufacturing a standard material (1000) according to an example of the present disclosure will be described with reference to FIG. 4.

[0065] According to one example of the present disclosure, the method may include a lamination process (S100) in which a plurality of base layers (10) and a plurality of intermediate layers (20) are alternately laminated to form a multilayer structure (100), a first etching process (S200) in which the plurality of intermediate layers (20) are removed by a predetermined depth so as to be sunken compared to the base layer (20), an oxidation process (S300) in which an oxide film (50) having a predetermined thickness is formed on the surfaces of the base layer (10) and the intermediate layer (20), and a second etching process in which the oxide film (50) is removed to form a convex portion (300) having a relatively high height on one surface of the multilayer structure (100) and a concave portion (400) sunken to a predetermined depth in the convex portion (300).

[0066] As described above, one example of the present disclosure provides the advantage of being able to form the thinnest convex portion (300) to a thickness of 5 nm or less through two etching processes, thereby enabling more precise evaluation of the microscope.

[0067] Next, a method for evaluating a microscope using a standard material (1000) according to an example of the present disclosure will be described with reference to FIG. 5.

[0068] Figure 5(a) is an image of a standard material (1000) taken with a microscope, converted into a contrast distribution, and Figure 5(b) is a thickness ( ) is shown as a convex portion (300) and a concave portion (400) having values ​​that are repeatedly arranged and formed.

[0069] A method for evaluating the spatial resolution of a microscope using a standard material (1000) may include a step of determining an authentication value based on a predetermined standard by using the actual thickness (wa) of a convex portion (300) as an authentication value, a step of placing the standard material on a sample stage of a microscope and illuminating one side of a multilayer structure in which the convex portion and the concave portion are formed, a step of measuring the thickness of the convex portion (300) using a microscope, and a step of evaluating the spatial resolution of the microscope by comparing the authentication value with a thickness measurement value (wm) of the convex portion (300) measured using a microscope.

[0070] When a standard material (1000) is observed by illuminating it with a microscope as in Fig. 5(a), a bright image or high contrast value is obtained from a convex portion (300) located relatively close to the objective lens of the microscope, and a dark image or low contrast value is obtained from a concave portion (400) located relatively far from the objective lens of the microscope.

[0071] That is, the thickness of the convex portion (300) can be measured through the thickness of the portion where a high contrast value is obtained, and the spatial resolution of the microscope can be evaluated by comparing the measured value for the thickness of the convex portion (300) with the actual thickness of the convex portion (300) of FIG. 5(b).

[0072] At this time, if the actual thickness (wa) of the convex portion (300) is referred to as the authentication value, the authentication value can be determined through a predetermined standard. The predetermined standard for determining the authentication value can be determined by the single crystal Si lattice constant value (α=0.5431020511 nm), and since the authentication value is determined based on the single crystal Si lattice constant, it provides the advantage of enabling accurate microscopic evaluation.

[0073] Figure 6 shows a graph that can evaluate the spatial resolution of a microscope using a standard material (1000). In a microscope, due to factors such as the diffraction limit of light or the edge effect of an electron beam, a point that cannot be resolved occurs below a certain thickness, resulting in a resolution lower than the theoretical spatial resolution. Here, the spatial resolution is one of the indicators representing the performance of a microscope. Therefore, this is certified as a value () using a standard material (1000) with a thickness between 3 nm and 30 nm. ) Thickness measurements measured from a contrast microscope ( ) can be used to measure the spatial resolution of an actual microscope rather than a theoretical value by representing a graph. The slope of the graph starts from a convex portion (300) with a thick thickness and shows linearity, but below a convex portion (300) with a certain thickness (~10 nm), a point where linearity is not shown appears. Here, the point of saturation varies depending on the performance of the microscope. From this point, the actual spatial resolution of the microscope can be found out through the measured thickness value at the minimum thickness of the certified value. In addition, by evaluating the difference between the actual value and the measured value using a standard material (1000) and calibrating the microscope, it can be used to improve the performance of the microscope and correct the magnification.

[0074] While the embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical concept or essential features thereof. Therefore, the embodiments described above should be understood to be illustrative in all respects and not restrictive.

Claims

1. As a nanostructure standard material used to evaluate the performance of a microscope, A plurality of base layers having a predetermined thickness and spaced apart at regular intervals; and It comprises a plurality of intermediate layers, each of which is interposed between the plurality of base layers; The above multiple base layers and multiple intermediate layers are alternately laminated to form a multilayer structure. Standard material.

2. In paragraph 1, On one side of the above multilayer structure, a convex portion having a relatively high height and a concave portion formed by being sunken to a certain depth and having a relatively low height compared to the convex portion are formed. The above convex portions and concave portions are formed in multiple numbers, and are configured so that the convex portions and concave portions form a repetitive arrangement. The above convex portion is formed from the base layer, The above concave portion is formed from a portion of the base layer at both ends where the intermediate layer is interposed. Standard material.

3. In paragraph 2, The above base layer is made of Si, and the above intermediate layer is It is composed of, The above convex and concave portions are formed through two etching processes. Standard material.

4. In paragraph 3, The above plurality of convex portions each have different thicknesses, and the thickness of the above plurality of convex portions is configured to increase from one side to the other side along the direction in which the multilayer structure is laminated. Standard material.

5. In paragraph 4, The thickness of the thinnest convex portion among the above plurality of convex portions is 3 nm or more and 5 nm or less. Standard material.

6. In paragraph 3, The thickness of the above base layer is 8 nm or more, Standard material.

7. In paragraph 2, Further comprising a support layer supporting both ends of the multilayer structure, Standard material.

8. A method for manufacturing a standard material including a plurality of base layers and a plurality of intermediate layers each inserted between the plurality of base layers, which are used for evaluating the performance of a microscope. A lamination process in which a plurality of base layers and a plurality of intermediate layers are alternately laminated to form a multilayer structure; A first etching process in which the plurality of intermediate layers are removed to a predetermined depth so as to be sunken compared to the base layer; An oxidation process for forming an oxide film having a predetermined thickness on the surfaces of the base layer and the intermediate layer; and A second etching process for removing the oxide film; Method for preparing standard materials.

9. In paragraph 8, Through the second etching process, a convex portion having a relatively high height and a concave portion having a relatively low height and a predetermined depth are formed on one surface of the multilayer structure. The above convex and concave portions are formed in a repetitive arrangement on one side of the multilayer structure, The above convex portion is formed from the base layer, The above concave portion is formed from a portion of the base layer at both ends where the intermediate layer is interposed. Method for preparing standard materials.

10. In paragraph 8, The above base layer is made of Si, and the above intermediate layer is Consisting of, Method for preparing standard materials.

11. In paragraph 8, The thickness of the above oxide film is 1.5 nm or more and 2.5 nm or less. Method for preparing standard materials.

12. In paragraph 8, The thickness of the above base layer is 8 nm or more, Method for preparing standard materials.

13. A method for evaluating the performance of a microscope using the standard material of Article 2, A step of determining an authentication value based on a predetermined standard, with the actual thickness of the convex portion being referred to as the authentication value; A step of placing the above standard material on a microscope specimen stage and illuminating one side of the multilayer structure in which the convex and concave portions are formed; A step of measuring the thickness of the convex portion using a microscope; and Comprising a step of evaluating the performance of the microscope by comparing the thickness of the convex portion measured by the microscope with the authentication value. Microscopic evaluation method using standard materials.

14. In paragraph 13, The criterion for determining the above authentication value is determined by the lattice constant value of Si. Microscopic evaluation method using standard materials.

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