A metrological standard and its preparation method

Abstract

This application discloses a metrological standard, comprising: a wafer carrier; a calibration micro / nano-scale standard sheet; a groove structure provided on the wafer carrier; and the calibration micro / nano-scale standard sheet being detachably fixed within the groove structure. The detachable calibration micro / nano-scale standard sheet in this metrological standard meets the requirements for periodic calibration and ensures the accuracy of measurement values ​​during long-term use.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a metrological standard and its preparation method. Background Technology

[0002] In the semiconductor manufacturing industry, each product undergoes hundreds of process and measurement steps from FAB IN to FAB OUT, involving at least thousands of measurement parameters. The quality of each measurement value directly affects the final product quality. Therefore, semiconductor measurement equipment plays a crucial role in the semiconductor industry. Semiconductor measurement equipment requires regular calibration to maintain the accuracy of its measurement values.

[0003] Currently, metrology institutions in various countries have gradually developed small-size chip-level nanometer metrology standards (such as nanometer-level linewidths and nanometer-level one-dimensional / two-dimensional periodic grids). However, semiconductor process line measurement equipment is entirely automated. These chip-level metrology standards cannot be directly used in the integrated circuit industry, resulting in a disconnect between nanometer metrology and industry. How to transfer chip-level nanometer metrology standards to large-size wafer carriers to form wafer-level nanometer metrology standards that are compatible with fully automated production lines and meet the online rapid metrology calibration needs of the semiconductor industry has become a major challenge for the metrology industry. On the other hand, ensuring the accuracy of measurement values ​​during long-term use is a pressing technical problem that needs to be solved at this stage. Summary of the Invention

[0004] In view of this, the present application provides a metrological standard to solve at least one problem existing in the background art.

[0005] To achieve the above objectives, the technical solution of this application is implemented as follows:

[0006] According to an embodiment of this application, a metrological standard is provided, comprising:

[0007] A wafer carrier; a calibration micro / nano-scale standard sheet; the wafer carrier has a groove structure; the calibration micro / nano-scale standard sheet is detachably fixed in the groove structure.

[0008] In some exemplary embodiments of this application, the bottom of the groove structure is provided with at least one air guide channel, the air guide channel connecting the groove structure and an external vacuum system, the external vacuum system being used to evacuate the air guide channel.

[0009] In some exemplary embodiments of this application, the wafer carrier includes a first wafer and a second wafer stacked together, the groove structure penetrates the first wafer, and the bottom surface of the groove structure is flush with the upper surface of the second wafer, wherein the upper surface of the second wafer is the surface of the second wafer facing the first wafer.

[0010] In some exemplary embodiments of this application, the roughness of the bottom of the groove structure and / or the roughness of the lower surface of the calibration micro / nano-scale standard sheet is less than or equal to 10 nm, wherein the lower surface of the calibration micro / nano-scale standard sheet is the surface of the calibration micro / nano-scale standard sheet facing the bottom of the groove structure.

[0011] In some exemplary embodiments of this application, the metrological standard further includes:

[0012] An adsorption-aiding membrane is located between the calibration micro / nano-scale standard sheet and the bottom of the groove structure, and the elastic modulus of the adsorption-aiding membrane is greater than that of the calibration micro / nano-scale standard sheet.

[0013] In some exemplary embodiments of this application, the gas guide channel is perpendicular to the wafer carrier, and the gas guide channel extends through the wafer carrier below the groove structure.

[0014] In some exemplary embodiments of this application, the opening sizes at the top of the plurality of air channels are equal, and the plurality of air channels are arranged at equal intervals.

[0015] In some exemplary embodiments of this application, the plurality of air channels are interconnected.

[0016] In some exemplary embodiments of this application, the number of top openings in the air guide channel is greater than the number of bottom openings.

[0017] In some exemplary embodiments of this application, the number of top openings in the air guide channel is less than the number of bottom openings.

[0018] In some exemplary embodiments of this application, the air guide channel is a through hole, and the diameter of the through hole on the side closer to the calibration micro-nano scale standard sheet is larger than the diameter on the side farther away from the calibration micro-nano scale standard sheet.

[0019] In some exemplary embodiments of this application, the depth of the groove structure is equal to the thickness of the calibration micro / nano-scale standard sheet.

[0020] This application also provides a method for preparing a metrological standard, including:

[0021] A wafer carrier is provided, and a groove structure is formed on the wafer carrier; at least one gas guide channel is formed at the bottom of the groove structure, and the gas guide channel connects the groove structure to an external vacuum system; the gas guide channel is evacuated by the external vacuum system; a calibration micro-nano scale standard sheet is provided, and the calibration micro-nano scale standard sheet is mounted in the groove structure.

[0022] In some exemplary embodiments of this application, forming a groove structure on the wafer carrier includes:

[0023] The groove structure is formed using a pulsed laser, wherein the pulse width of the pulsed laser is less than or equal to 100 ns, the power of the pulsed laser is 10 to 300 W, and the repetition frequency is 10 to 100 kHz.

[0024] In some exemplary embodiments of this application, providing a wafer carrier and forming a groove structure on the wafer carrier includes:

[0025] A first wafer is provided; a through-groove is formed on the first wafer; a second wafer is provided; the first wafer and the second wafer are bonded together, and a groove structure is formed between the through-groove and the surface of the second wafer.

[0026] In some exemplary embodiments of this application, after providing micro / nano-sized standard sheets for calibration, the method further includes:

[0027] An adsorption-aiding film is formed on the lower surface of the calibration micro-nano-scale standard sheet. The elastic modulus of the adsorption-aiding film is greater than that of the calibration micro-nano-scale standard sheet. The lower surface of the calibration micro-nano-scale standard sheet is the surface on which the calibration micro-nano-scale standard sheet is to be attached to the bottom of the groove structure.

[0028] In some exemplary embodiments of this application, at least one air guide channel is formed at the bottom of the groove structure, including:

[0029] The gas guiding channel is formed by a pulsed laser, wherein the pulse width of the pulsed laser is less than or equal to 50 ps, ​​the power of the pulsed laser is 10 to 100 W, and the repetition frequency is 100 to 2000 kHz.

[0030] This application provides a metrological standard, comprising: a wafer carrier; a calibration micro / nano-scale standard sheet; a groove structure provided on the wafer carrier; and the calibration micro / nano-scale standard sheet being detachably fixed within the groove structure. The detachable calibration micro / nano-scale standard sheet in this metrological standard meets the requirements for periodic calibration and ensures the accuracy of measurement values ​​during long-term use.

[0031] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0032] Figure 1 This is a cross-sectional schematic diagram of a metrological standard for related technologies;

[0033] Figure 2This is a cross-sectional schematic diagram of the metrological standard provided in the embodiments of this application;

[0034] Figure 3 A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0035] Figure 4a A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0036] Figure 4b A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0037] Figure 5 A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0038] Figure 6 A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0039] Figure 7 A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0040] Figure 8 A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0041] Figures 9a-9b A cross-sectional schematic diagram of a metrological standard provided in another embodiment of this application;

[0042] Figure 10 A flowchart illustrating the method for preparing the metrological standard provided in this application embodiment;

[0043] Figures 11a to 11d This is a schematic diagram of the device structure during the fabrication process of the metrological standard provided in the embodiments of this application. Detailed Implementation

[0044] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the disclosure of the present application to those skilled in the art.

[0045] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, to avoid confusion with this application, some technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0046] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0047] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0048] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0050] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solution of this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0051] Appendix Figure 1 This is a cross-sectional schematic diagram of a metrological standard for related technologies in the industry. The metrological standard includes: a wafer carrier 101; a calibration micro / nano-scale standard sheet 105; a groove structure 103 on the wafer carrier 101; and the calibration micro / nano-scale standard sheet 105 fixed in the groove structure 103 by an adhesive material 107. This metrological standard uses a dispensing process to transfer the calibration micro / nano-scale standard sheet to the wafer groove to form a wafer-level metrological standard. This adhesive fixing method means that the calibration micro / nano-scale standard sheet cannot be removed from the wafer carrier later, thus failing to meet the periodic calibration requirements of the metrological standard. This type of calibration micro / nano-scale standard sheet needs to be calibrated annually to ensure the accuracy of the measurement values. For example, integrated circuit manufacturing companies need standard sheets (such as nanometer linewidth standards) to calibrate fully automated scanning electron microscopes (SEMs). To ensure the process quality of the semiconductor industry, new calibrated standard sheets must be purchased and replaced, increasing production costs and increasing the production risk for companies due to the longer procurement cycle. Furthermore, the height of the adhesive material is difficult to control, making it impossible to accurately control the height difference between the calibration micro / nano-scale standard sheet and the wafer carrier surface, thus affecting the measurement results. In summary, the standard sheets produced by previous wafer-level metrology standard solutions were all certified only once. During long-term use, it is impossible to recertify the standard sheets, and the long-term accuracy of the measurement values ​​cannot be guaranteed.

[0052] Based on this, the embodiments of this application provide a metrological standard, with appendix... Figure 2 This is a cross-sectional schematic diagram of the metrological standard provided in an embodiment of this application. (See attached diagram.) Figure 2The metrological standard includes: a wafer carrier 101; a calibration micro / nano-scale standard sheet 105; a groove structure 103 is provided on the wafer carrier 101; and the calibration micro / nano-scale standard sheet 105 is detachably fixed within the groove structure 103. The calibration micro / nano-scale standard sheet in the metrological standard of this application is detachable, meeting the requirements for periodic calibration and ensuring the accuracy of the measurement values ​​during long-term use.

[0053] In practice, the wafer carrier 101 can be a silicon wafer, glass wafer, gallium nitride wafer, silicon carbide wafer, sapphire wafer, gallium arsenide wafer, etc. The thickness of the wafer carrier can be, for example, 775±20 μm. The size of the wafer carrier can be, for example, 6 inches, 8 inches, or 12 inches. The nano-geometric features of the calibration micro / nano-scale standard wafer include, but are not limited to, linewidth, latticework, steps, and film thickness.

[0054] In some embodiments of this application, the depth of the groove structure 103 is equal to the thickness of the calibration micro / nano-scale standard sheet 105. The dimensions of the groove structure 103 can be, for example, 20.05 × 20.05 × 300 μm (length × width × height), and it can be formed using wet or dry etching processes. The dimensions of the calibration micro / nano-scale standard sheet 105 can be, for example, 20 × 20 × 300 μm (length × width × height). Thus, embedding the calibration micro / nano-scale standard sheet into the groove reduces the volume of the calibration micro / nano-scale standard sheet exposed on the wafer carrier surface, increasing the stability of the calibration micro / nano-scale standard sheet on the wafer carrier.

[0055] In some embodiments of this application, as shown in the appendix Figure 2 As shown, the bottom of the groove structure 103 is provided with at least one gas guiding channel 109, which connects the groove structure 103 to the external vacuum system 111. The external vacuum system 111 is used to evacuate the gas guiding channel. When a metrological standard is needed, a calibration micro / nano-scale standard sheet can be adsorbed using the external vacuum system. After use, the standard can be removed. After long-term use, the calibration micro / nano-scale standard sheet needs to be certified and calibrated. The removed calibration micro / nano-scale standard sheet can be calibrated separately to ensure the accuracy of the measurement values ​​and meet the periodic calibration requirements. Furthermore, when either the wafer carrier or the calibration micro / nano-scale standard sheet is damaged, only the damaged one needs to be replaced. Manufacturing a new metrological standard is not only low-cost and fast, but also reduces the production risk for enterprises.

[0056] In practice, the gas guiding channel can be formed by etching or laser grooving.

[0057] In some embodiments of this application, the gas guide channel is perpendicular to the wafer carrier, and the gas guide channel 109 extends through the wafer carrier below the groove structure 103. This facilitates gas flow and improves the vacuuming efficiency of the external vacuum system.

[0058] In some embodiments of this application, as shown in the appendix Figure 3 As shown, the opening sizes W1 at the top of the plurality of gas guiding channels 109 are equal, and the plurality of gas guiding channels are arranged at equal intervals W2. In actual operation, the gas guiding channels can be, for example, cylindrical, with opening sizes W1 ranging from 10 to 2000 μm, and intervals W2 ranging from 100 to 4000 μm. The uniform arrangement of the plurality of gas guiding channels can improve the uniformity of the adsorption force when the external vacuum system evacuates.

[0059] In some embodiments of this application, the roughness of the bottom of the groove structure 103 and / or the roughness of the lower surface of the calibration micro / nano-scale standard sheet 105 is less than or equal to 10 nm, wherein the lower surface of the calibration micro / nano-scale standard sheet is the surface of the calibration micro / nano-scale standard sheet facing the bottom of the groove structure. Thus, by improving flatness, gas leakage is reduced, thereby improving the vacuum adsorption effect of the external vacuum system.

[0060] In some embodiments of this application, as shown in the appendix Figures 4a-4b As shown, the metrological standard further includes an aspiration-aiding membrane 113, which is located between the calibration micro / nano-scale standard sheet 105 and the bottom of the groove structure 103, and the elastic modulus of the aspiration-aiding membrane 113 is greater than the elastic modulus of the calibration micro / nano-scale standard sheet 105. In actual operation, as shown in the attached diagram... Figure 4a As shown, the adsorption-aiding membrane 113 can be coated or attached to the lower surface of the calibration micro / nano-scale standard sheet 105. Alternatively, as shown in the attached... Figure 4b As shown, the adsorption-aid membrane 113 can be coated or attached to the bottom of the groove structure 103. When the bottom of the groove or the calibration micro / nano-sized standard sheet is rough, a vacuum adsorption-aid membrane can be used to reduce gas leakage and improve the adsorption effect.

[0061] In some embodiments of this application, as shown in the appendix Figure 5As shown, the wafer carrier includes a first wafer 101-1 and a second wafer 101-2 stacked together. The groove structure 103 penetrates the first wafer 101-1, and the bottom surface of the groove structure 103 is flush with the upper surface 111 of the second wafer 101-2, wherein the upper surface of the second wafer is the surface of the second wafer facing the first wafer. In actual operation, the thickness of the first wafer 101-1 can be, for example, 300±10μm, and the thickness of the second wafer 101-2 can be, for example, 475±10μm. The groove structure can be formed using a pulsed laser. When the groove is formed using an etching process, the surface roughness of the bottom of the groove is poor, affecting the adsorption effect, and etching requires a photomask, resulting in high process costs. This solution uses two wafers, and the groove structure and gas guide channel are formed in each wafer using a pulsed laser. Using the upper surface of the second wafer as the bottom surface of the groove structure can achieve a lower roughness and improve the adsorption effect. In actual operation, the roughness of the upper surface of the second wafer can be controlled by a grinding and polishing process. On the other hand, pulsed lasers are more efficient than etching for grooving and do not require the cost of a photomask.

[0062] In some embodiments of this application, as shown in the appendix Figure 6 As shown, the multiple gas guiding channels 109 are interconnected. In actual operation, this can be achieved through longitudinal etching and lateral etching, or by forming gas guiding channels in multiple wafers separately and then bonding the multiple wafers together. The interconnection of multiple gas guiding channels ensures a consistent vacuum level within the channels, resulting in more uniform adsorption force, and also avoids the problem of decreased adsorption force caused by blockage of multiple gas guiding channels.

[0063] In some embodiments of this application, as shown in the appendix Figure 7 As shown, the number of top openings 109-1 in the air guiding channel is greater than the number of bottom openings 109-2. The more top openings in the air guiding channel, the larger the effective adsorption area, and the greater and more uniform the adsorption force.

[0064] In some embodiments of this application, as shown in the appendix Figure 8 As shown, the number of top openings 109-1 in the gas guiding channel is less than the number of bottom openings 109-2. General structures have varying degrees of air leakage, but the more bottom openings in the gas guiding channel, the greater the airflow, i.e., the higher the pumping speed, which can improve the vacuum level and thus enhance or stabilize the adsorption force.

[0065] In some embodiments of this application, as shown in the appendix Figure 9aAs shown, the gas guiding channel 109 is a through-hole, and the diameter W3 of the through-hole on the side closer to the calibration micro / nano-scale standard sheet is larger than the diameter W4 on the side farther away from the calibration micro / nano-scale standard sheet. In practice, the gas guiding channel can be, for example, a frustum with a taper of less than 0.2. This makes the adsorption force more uniform and improves the stability of the calibration micro / nano-scale standard sheet on the wafer carrier. On the other hand, when forming the gas guiding channel using an etching process, a frustum-shaped gas guiding channel is easier to implement and less expensive than a vertical column. In some other embodiments, as shown in the attached... Figure 9b The air guiding channel can also be a cylindrical channel with different widths at the top and bottom. For example, the air guiding channel includes a cylindrical channel 109-1 with an upper width of W5 and a cylindrical channel 109-2 with a lower width of W6, wherein W5 is greater than W6. In some embodiments, the air guiding channel includes cylindrical channels with different widths at the top and bottom, the width of the upper air guiding channel is greater than the width of the lower air guiding channel, and the upper air guiding channel is a frustum with a taper of less than 0.2.

[0066] This application also provides a method for preparing a metrological standard; please refer to the appendix for details. Figure 10 As shown in the figure, the method includes:

[0067] Step 1001: Provide a wafer carrier and form a groove structure on the wafer carrier;

[0068] Step 1002: At least one air guide channel is formed at the bottom of the groove structure, and the air guide channel connects the groove structure with the external vacuum system;

[0069] Step 1003: Vacuum the gas guide channel using the external vacuum system;

[0070] Step 1004: Provide a calibration micro / nano-scale standard sheet and attach the calibration micro / nano-scale standard sheet into the groove structure.

[0071] The preparation method of the metrological standard provided in this application will be further described in detail below with reference to specific embodiments.

[0072] Figures 11a to 11d This is a schematic diagram of the device structure during the fabrication process of the metrological standard provided in the embodiments of this application.

[0073] First, execute step 1001, see [link / reference] Figure 11aA wafer carrier 101 is provided, on which a groove structure 103 is formed. The wafer carrier 101 can be a silicon wafer, glass wafer, gallium nitride wafer, silicon carbide wafer, sapphire wafer, gallium arsenide wafer, etc. The thickness of the wafer carrier can be, for example, 775±20μm. The size of the wafer carrier can be, for example, 6 inches, 8 inches, or 12 inches.

[0074] In some embodiments of this application, forming a groove structure on the wafer carrier includes: forming the groove structure using a pulsed laser, wherein the pulse width of the pulsed laser is less than or equal to 100 ns, the power of the pulsed laser is 10 to 300 W, and the repetition frequency is 10 to 100 kHz.

[0075] Next, see Figure 11b In step 1002, at least one gas guiding channel 109 is formed at the bottom of the groove structure 101, the gas guiding channel connecting the groove structure to the external vacuum system. In actual operation, the gas guiding channel can be formed by etching or laser grooving processes.

[0076] In some embodiments of this application, providing a wafer carrier and forming a groove structure on the wafer carrier includes: providing a first wafer; forming a through-groove on the first wafer; providing a second wafer; and bonding the first wafer and the second wafer together, with the through-groove forming a groove structure with the surface of the second wafer. In practice, the thickness of the first wafer may be, for example, 300±10 μm, and the thickness of the second wafer may be, for example, 475±10 μm.

[0077] In some embodiments of this application, at least one air guide channel is formed at the bottom of the groove structure, including: forming the air guide channel using a pulsed laser, wherein the pulse width of the pulsed laser is less than or equal to 50 ps, ​​the power of the pulsed laser is 10 to 100 W, and the repetition frequency is 100 to 2000 kHz.

[0078] In some embodiments of this application, the gas guide channel is perpendicular to the wafer carrier, and the gas guide channel 109 extends through the wafer carrier below the groove structure 103.

[0079] In some embodiments of this application, the opening sizes at the top of the plurality of air guide channels 109 are equal, and the plurality of air guide channels are arranged at equal intervals. In actual operation, the air guide channels can be, for example, cylindrical, with an opening size W1 of 10–2000 μm, and the interval W2 between the plurality of air guide channels can be 100–4000 μm.

[0080] In some embodiments of this application, the plurality of the air guide channels 109 are interconnected.

[0081] In some embodiments of this application, the number of top openings in the air guide channel is greater than the number of bottom openings.

[0082] In some embodiments of this application, the number of top openings in the air guide channel is less than the number of bottom openings.

[0083] In some embodiments of this application, the gas guiding channel 109 is a through hole, and the diameter of the through hole on the side closer to the calibration micro / nano-scale standard sheet is larger than the diameter on the side farther from the calibration micro / nano-scale standard sheet. In some other embodiments, the gas guiding channel may also be a cylindrical channel with different widths at the top and bottom. In some embodiments, the gas guiding channel includes cylindrical channels with different widths at the top and bottom, the width of the upper gas guiding channel is greater than the width of the lower gas guiding channel, and the upper gas guiding channel is a frustum with a taper of less than 0.2.

[0084] Then, see Figure 11c Step 1003 is executed, in which the gas guide channel is evacuated by the external vacuum system 111.

[0085] Finally, referring to 11d, perform step 1104, provide a calibration micro / nano-scale standard sheet 105, and attach the calibration micro / nano-scale standard sheet 105 into the groove structure 103.

[0086] In some embodiments of this application, the depth of the groove structure 103 is equal to the thickness of the calibration micro / nano-scale standard sheet 105. The dimensions of the groove structure 103 can be, for example, 20.05 × 20.05 × 300 μm (length × width × height), and it can be formed using wet or dry etching processes. The dimensions of the calibration micro / nano-scale standard sheet 105 can be, for example, 20 × 20 × 300 μm (length × width × height). The nano-geometric features of the calibration micro / nano-scale standard sheet include, but are not limited to, linewidth, grid, steps, and film thickness.

[0087] In some embodiments of this application, the roughness of the bottom of the groove structure 103 and / or the roughness of the lower surface of the calibration micro / nano-scale standard sheet 105 is less than or equal to 10 nm, wherein the lower surface of the calibration micro / nano-scale standard sheet is the surface of the calibration micro / nano-scale standard sheet facing the bottom of the groove structure.

[0088] In some embodiments of this application, after providing a calibration micro / nano-scale standard sheet, the method further includes: forming an adsorption-aiding film on the lower surface of the calibration micro / nano-scale standard sheet, wherein the elastic modulus of the adsorption-aiding film is greater than the elastic modulus of the calibration micro / nano-scale standard sheet, wherein the lower surface of the calibration micro / nano-scale standard sheet is the surface of the calibration micro / nano-scale standard sheet to be attached to the bottom of the groove structure.

[0089] In summary, the calibration micro-nano scale standard sheet in the metrological standard of this application is detachable, meets the requirements of periodic calibration, and can ensure the accuracy of the measurement values ​​during long-term use.

[0090] It should be noted that the metrological standard and its preparation method provided in the embodiments of this application can be applied to the online calibration of high-precision measuring instruments in any wafer-level semiconductor production line, such as scanning electron microscopes, atomic force microscopes, and fully automated optical microscopes. The technical features described in each embodiment can be arbitrarily combined without conflict.

[0091] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A metrological standard, characterized in that, include: wafer carrier; Calibration micro / nano-scale standard sheets; The wafer carrier is provided with a groove structure; The calibration micro / nano-scale standard sheet is detachably fixed within the groove structure; The wafer carrier includes a first wafer and a second wafer stacked together. The groove structure penetrates the first wafer, and the bottom surface of the groove structure is flush with the top surface of the second wafer. The top surface of the second wafer is the surface of the second wafer facing the first wafer. The roughness of the bottom of the groove structure and / or the roughness of the lower surface of the calibration micro / nano-scale standard sheet is less than or equal to 10 nm, wherein the lower surface of the calibration micro / nano-scale standard sheet is the surface of the calibration micro / nano-scale standard sheet facing the bottom of the groove structure.

2. The metrological standard as described in claim 1, characterized in that, The bottom of the groove structure is provided with at least one air guide channel, which connects the groove structure to an external vacuum system. The external vacuum system is used to evacuate the air guide channel.

3. The metrological standard as described in claim 2, characterized in that, Also includes: An adsorption-aiding membrane is located between the calibration micro / nano-scale standard sheet and the bottom of the groove structure, and the elastic modulus of the adsorption-aiding membrane is greater than that of the calibration micro / nano-scale standard sheet.

4. The metrological standard as described in claim 2, characterized in that, The gas guide channel is perpendicular to the wafer carrier and extends through the wafer carrier below the groove structure.

5. The metrological standard as described in claim 2, characterized in that, The openings at the top of the plurality of air channels are of equal size, and the plurality of air channels are arranged at equal intervals.

6. The metrological standard as described in claim 2, characterized in that, The multiple air guide channels are interconnected.

7. The metrological standard as described in claim 6, characterized in that, The number of openings at the top of the air guide channel is greater than the number of openings at the bottom.

8. The metrological standard as described in claim 6, characterized in that, The number of openings at the top of the air guide channel is less than the number of openings at the bottom.

9. The metrological standard as described in claim 2, characterized in that, The air guide channel is a through hole, and the diameter of the through hole on the side closer to the calibration micro-nano scale standard sheet is larger than the diameter on the side farther away from the calibration micro-nano scale standard sheet.

10. The metrological standard as described in claim 1, characterized in that, The depth of the groove structure is equal to the thickness of the calibration micro / nano-scale standard sheet.

11. A method for preparing a metrological standard according to any one of claims 1-10, characterized in that, include: A wafer carrier is provided, on which a groove structure is formed; At least one air guide channel is formed at the bottom of the groove structure, and the air guide channel connects the groove structure to the external vacuum system; The gas guide channel is evacuated using the external vacuum system. A calibration micro-nano scale standard sheet is provided, and the calibration micro-nano scale standard sheet is mounted in the groove structure.

12. The method for preparing the metrological standard as described in claim 11, characterized in that, The process of forming a groove structure on the wafer carrier includes: The groove structure is formed using a pulsed laser, wherein the pulse width of the pulsed laser is less than or equal to 100 ns, the power of the pulsed laser is 10 to 300 W, and the repetition frequency is 10 to 100 kHz.

13. The method for preparing the metrological standard as described in claim 11, characterized in that, The provision of a wafer carrier, on which a groove structure is formed, includes: Provide the first wafer; A through-groove is formed on the first wafer; Provide a second wafer; The first wafer and the second wafer are bonded together, and the through-groove forms a groove structure with the surface of the second wafer.

14. The method for preparing the metrological standard as described in claim 11, characterized in that, After providing micro / nano-sized standard sheets for calibration, the method further includes: An adsorption-aiding film is formed on the lower surface of the calibration micro-nano-scale standard sheet. The elastic modulus of the adsorption-aiding film is greater than that of the calibration micro-nano-scale standard sheet. The lower surface of the calibration micro-nano-scale standard sheet is the surface on which the calibration micro-nano-scale standard sheet is to be attached to the bottom of the groove structure.

15. The method for preparing the metrological standard as described in claim 11, characterized in that, At least one air guide channel is formed at the bottom of the groove structure, including: The gas guiding channel is formed by a pulsed laser, wherein the pulse width of the pulsed laser is less than or equal to 50 ps, ​​the power of the pulsed laser is 10 to 100 W, and the repetition frequency is 100 to 2000 kHz.

Images