CN113324488A - Thickness measurement method and system - Google Patents
Thickness measurement method and system Download PDFInfo
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- CN113324488A CN113324488A CN202110530270.3A CN202110530270A CN113324488A CN 113324488 A CN113324488 A CN 113324488A CN 202110530270 A CN202110530270 A CN 202110530270A CN 113324488 A CN113324488 A CN 113324488A
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- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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Abstract
The embodiment of the application discloses a thickness measuring method and a system, wherein the method comprises the following steps: acquiring a TEM image of a sample to be detected under a preset under-focus amount; automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured; obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve; and compensating the measured thickness based on the thickness drift amount to obtain the actual thickness of the sample to be measured.
Description
Technical Field
The embodiment of the application relates to the field of semiconductor manufacturing, in particular to a thickness measuring method and system.
Background
Transmission Electron Microscopes (TEMs) are widely used for measuring the thickness of semiconductor microstructures due to their extremely high resolving power. The special illumination and optical system of TEM can focus the electrons accelerated by electric field and project them on very thin sample. The transmitted electron beams with the structural and composition information of the sample finally pass through an imaging system, and the microscopic appearance of the sample can be clearly shown.
At present, the thickness of a film layer in a three-dimensional memory is mostly measured by taking a TEM image after a Focused Ion Beam (FIB) slice is taken. However, when the thickness measurement of the target observation object is performed using the TEM image, the thickness measurement is affected by other structures around the target observation object, so that the accuracy and efficiency of the measurement are further reduced.
Disclosure of Invention
In view of the above, embodiments of the present application provide a thickness measuring method and system to solve at least one problem in the prior art.
In order to achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:
in a first aspect, an embodiment of the present application provides a thickness measurement method, where the method includes:
acquiring a TEM image of a sample to be detected under a preset under-focus amount;
automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured;
obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve;
and compensating the measured thickness based on the thickness drift amount to obtain the actual thickness of the sample to be measured.
In an alternative embodiment, before acquiring the TEM image of the sample to be tested at the preset under-focus amount, the method further comprises:
acquiring TEM images of standard samples under different under-focus amounts;
automatically measuring the thickness of the TEM image of the standard sample to obtain thicknesses corresponding to different under-focus amounts;
and obtaining an under-focus-thickness fitting curve according to the thickness and the under-focus corresponding to the thickness.
In an alternative embodiment, before acquiring the TEM image of the sample to be tested at the preset under-focus amount, the method further comprises:
and determining the optimal under-focus range according to the under-focus amount-thickness fitting curve.
In an alternative embodiment, the preset under-focus amount is a value within an optimal under-focus range; the optimal under-focus range is 100nm-250 nm.
In an alternative embodiment, the obtaining the thickness drift amount at the preset under-focus through an under-focus-thickness fitting curve includes:
obtaining the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample through an under-focus amount-thickness fitting curve;
and obtaining the thickness drift amount under the preset under-focus according to the thickness of the standard sample corresponding to the preset under-focus and the zero under-focus thickness of the standard sample.
In an alternative embodiment, the sample to be tested comprises a channel hole and an aluminum oxide layer surrounding the channel hole;
the automatic thickness measurement of the TEM image of the sample to be measured is carried out to obtain the measured thickness of the sample to be measured, and the method comprises the following steps:
and automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the alumina layer in the sample to be measured.
In a second aspect, an embodiment of the present application provides a thickness measurement system, including:
the acquisition module is used for acquiring a TEM image of a sample to be detected under a preset under-focus amount;
the measuring module is used for automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured;
the calculation module is used for obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve;
and the compensation module is used for compensating the measured thickness based on the thickness drift amount so as to obtain the actual thickness of the sample to be measured.
In an alternative embodiment, the acquiring module is further configured to acquire TEM images of the standard sample at different under-focus amounts;
the measuring module is also used for automatically measuring the thickness of the TEM image of the standard sample to obtain the thicknesses corresponding to different under-focus amounts;
further comprising:
and the function module is used for obtaining an under-focus-thickness fitting curve according to the thickness and the under-focus corresponding to the thickness.
In an optional embodiment, the method further comprises:
and the determining module is used for determining the optimal under-focus range according to the under-focus amount-thickness fitting curve.
In an alternative embodiment, the preset under-focus amount is a value within the optimal under-focus range; the optimal under-focus range is 100nm-250 nm.
In an optional embodiment, the calculation module is specifically configured to obtain, through an under-focus-thickness fitting curve, a thickness of the standard sample corresponding to the preset under-focus amount and a zero under-focus thickness of the standard sample;
and obtaining the thickness drift amount under the preset under-focus according to the thickness of the standard sample corresponding to the preset under-focus and the zero under-focus thickness of the standard sample.
In an alternative embodiment, the sample to be tested comprises a channel hole and an aluminum oxide layer surrounding the channel hole;
and the measuring module is used for automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the alumina layer in the sample to be measured.
The embodiment of the application discloses a thickness measuring method and a system, wherein the method comprises the following steps: acquiring a TEM image of a sample to be detected under a preset under-focus amount; automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured; obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve; and compensating the measured thickness based on the thickness drift amount to obtain the actual thickness of the sample to be measured. By establishing the corresponding relation between the under-focus amount and the thickness, the thickness drift amount under the under-focus amount can be calculated according to the under-focus amount. Therefore, the measured thickness under the default under-focus amount is compensated according to the thickness drift amount, and the accurate actual thickness is obtained.
Drawings
Fig. 1 is a schematic flow chart illustrating an implementation of a thickness measurement method according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of a local sample to be tested according to an embodiment of the present disclosure;
FIG. 3 is a TEM image of a target measurement structure provided by an embodiment of the present application;
FIG. 4a is a TEM image of a target measurement structure in a positive focus provided by an embodiment of the present application;
FIG. 4b is a TEM image of the target measurement structure at a slight under-focus provided by an embodiment of the present application;
FIG. 4c is a TEM image of the target measurement structure under large under-focus provided by the embodiment of the present application;
FIG. 5 is a schematic diagram of thickness measurement curves of a standard sample at different amounts of under-focus provided by an embodiment of the present application;
FIG. 6 is a schematic view of an under-focus-thickness fitted curve of a standard sample provided in an example of the present application;
FIG. 7 is a TEM image and an FFT image provided by an embodiment of the present application;
FIG. 8 is a thickness profile provided in accordance with an embodiment of the present application;
fig. 9 is a schematic structural diagram of a thickness measurement system according to an embodiment of the present disclosure.
Detailed Description
Exemplary embodiments disclosed in the present application will be described in more detail below 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 embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the present application may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the present application; that is, not all features of an actual embodiment are described herein, and well-known functions and structures are not described in detail.
In the drawings, the size of layers, regions, elements, and relative sizes may be exaggerated for clarity. Like reference numerals refer to like elements throughout.
It will be appreciated that spatial relationship terms, such as "under … …," "under … …," "under … …," "over … …," "over," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below … …" and "below … …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
An embodiment of the present application provides a thickness measurement method, and fig. 1 is a schematic view illustrating an implementation flow of the thickness measurement method provided in the embodiment of the present application, where as shown in fig. 1, the method mainly includes the following steps:
and 110, acquiring a TEM image of the sample to be detected under a preset under-focus amount.
In one embodiment, the target measurement structure is included in the sample to be tested. Here, the sample to be tested may include a semiconductor substrate, a stack structure on the semiconductor substrate, and a trench hole penetrating the stack structure; the stacked structure is formed by alternately stacking insulating layers and gate electrode layers; the target measurement structure and the surrounding structure constitute the gate layer, while the target measurement structure surrounds the channel hole in a direction parallel to the semiconductor substrate.
In some embodiments, the target measurement structure is a high-k dielectric layer in the gate layer, and in practical applications, the material of the high-k dielectric layer may be aluminum oxide (Al)2O3). The surrounding structure is an adhesion layer and a conductive layer in the gate layer, and in practical application, the adhesion layer may be made of titanium nitride (TiN), and the conductive layer may be made of tungsten (W).
In some embodiments, the channel hole comprises, in order radially inward of the channel hole, a barrier layer, a charge trap layer, a tunneling layer, and a channel layer. The material of the barrier layer may be silicon oxide (SiO)2) (ii) a The material of the charge trap layer may be silicon nitride (Si)3N4) (ii) a The tunneling layer may be made of silicon oxide (SiO)2) (ii) a The material of the channel layer may be a conductive material, such as polysilicon (poly).
Here, the sample to be measured may be a chip (chip) or a partial structure including a target measurement structure in a chip. In some embodiments, the test sample may also be a die (die), or a portion of a die that includes a target measurement structure.
Fig. 2 is a schematic view of a local sample to be tested according to an embodiment of the present application, and it should be noted that fig. 2 is a cross-sectional view taken along a direction perpendicular to the semiconductor substrate. As shown in fig. 2, the sample to be tested includes a stacked structure 200 on the semiconductor substrate and a trench hole 210 penetrating through the stacked structure 200; the stack structure 200 is formed by alternately stacking insulating layers 220 and gate layers 230; the target measurement structure 231 and the surrounding structure 232 constitute the gate layer 230; the target measurement structure 231 surrounds the channel hole 210 in a direction parallel to the semiconductor substrate. The surrounding structure 232 includes an adhesion layer 2321 and a conductive layer 2322. In some embodiments, the stacked structure 200 herein may be a structure of a step region (stir Case).
The method for forming the gate layer 230 includes forming a high-k dielectric layer (the target measurement structure 231), forming an adhesion layer 2321, and finally forming a conductive layer 2322, where the conductive layer 2322 is disposed in a direction parallel to the substrate, and the conductive layer 2322 is disposed in the high-k dielectric layer (the target measurement structure 231) and the adhesion layer 2321. Since the thickness of the adhesion layer (TiN) is small and the boundary thereof is relatively rough, the adhesion layer cannot maintain a complete and independent shape after the conductive layer 2322 is formed, and the contrast of the adhesion layer (TiN) and the high-k dielectric layer is similar, the boundary between the target measurement structure 231 and the adhesion layer 2321 is difficult to distinguish under the influence of the adhesion layer (TiN), and therefore, when the thickness of the target measurement structure (high-k dielectric layer) is measured, the accuracy and repeatability of the thickness measurement data of the target measurement structure can be affected.
Fig. 3 is a TEM image of a target measurement structure provided in an embodiment of the present application, and it should be noted that fig. 3 is a plane TEM image along a direction parallel to the semiconductor substrate. As shown in fig. 3, the target measurement structure 231 surrounds the channel hole 210, and the surrounding structure (the attachment layer 2321 and the conductive layer 2322) surrounds the target measurement structure 231. Here, in fig. 2, inside the dotted line is a trench hole 210. It can be seen that the boundary of the adhesion layer 2321 is rough, and the boundary between the target measurement structure 231 and the adhesion layer 2321 is difficult to distinguish under the influence of the contrast of the adhesion layer 2321.
Further, it is because the boundary between the target measurement structure 231 and the adhesion layer 2321 is difficult to distinguish, so that when the thickness of the target measurement structure 231 is measured purely manually, the results obtained by different people are obviously different; and the recognition success rate of the semi-automatic recognition software iYA is low, the results obtained by clicking different positions can be greatly different. Although there is a method of removing the adhesion layer and the conductive layer first and then preparing the flat polished sample, this method is complicated in steps and high in cost, and online monitoring (inline monitor) cannot be realized. There are also methods of replacing the adhesion layer material with an oxidized material to obtain good contrast and measurement results, but such methods require a single wafer (wafer) run, which is expensive to measure and does not allow for practical monitoring of the condition of the final product.
In the embodiment of the application, the thickness identification success rate and the numerical accuracy are improved by automatically measuring the thickness of the TEM image under the preset under-focus amount; then, by establishing a corresponding relation between the under-burnt amount and the thickness, the thickness drift amount of the sample can be calculated according to the under-burnt amount; and compensating the measured thickness obtained by automatic measurement based on the thickness drift amount so as to obtain accurate actual thickness. By the thickness measurement method provided by the embodiment of the application, accurate actual thickness can be obtained by measurement on the premise of ensuring the accuracy and repeatability of the thickness measurement data of the sample to be measured without additionally processing the sample.
It should be noted that the thickness measurement method provided in the embodiment of the present application is generally applicable to thickness measurement of various film layers, and is not limited to thickness measurement of a high-k dielectric layer, and the embodiment of the present application only takes thickness measurement of a high-k dielectric layer as an example for description.
FIG. 4a is a TEM image of a target measurement structure in a positive focus provided by an embodiment of the present application; FIG. 4b is a TEM image of the target measurement structure at a slight under-focus provided by an embodiment of the present application; fig. 4c is a TEM image of the target measurement structure under large under-focus provided by the embodiment of the present application. The positive focus is a state where the amount of under-focus is 0 nm. The upper graphs in fig. 4a to 4c are schematic diagrams of the automatic boundary identification results corresponding to the TEM images, and the ordinate of the upper graphs in fig. 4a to 4c is the identification error rate and the abscissa is the boundary size. As shown in fig. 4a and 4b, in the case of the positive focus or the slight under focus, the boundary of the target measurement structure is very fuzzy, the boundary identification is very difficult, and the error rate of the automatic boundary identification is high. As shown in fig. 4c, the boundary of the target measurement structure becomes obvious in the case of large under-focus, and a regular boundary can be obtained in the case of sufficiently large under-focus, so that the error rate of automatic boundary identification is obviously reduced. As shown in fig. 4a to 4c, the larger the under-focus amount is, the Fresnel Fringe gradually appears at the boundary of the target measurement structure as the under-focus amount gradually increases (i.e. two "bright edges" of the target measurement structure in fig. 4b and 4c, one being the boundary between the target measurement structure and the adhesion layer and one being the boundary between the target measurement structure and the channel hole). As the amount of under focus increases, the "bright edge" boundary of the target measurement structure becomes more apparent, and thus the error rate of automatic boundary identification becomes lower and lower. Thus, the boundary in the TEM image under the large under-focus amount is more obvious, so that the thickness identification success rate is high when automatic thickness measurement is carried out.
In the embodiment of the application, the TEM image acquired under the default amount of focus is used for automatic thickness measurement, and the boundary of the sample to be measured under the default amount of focus is more obvious, so that the thickness identification success rate is high and the measured thickness is more accurate when the automatic thickness measurement is performed. And then, obtaining the thickness drift amount under the preset under-focus amount through the under-focus amount-thickness fitting curve, and compensating the measured thickness based on the thickness drift amount to obtain the accurate actual thickness.
In an embodiment of the present application, before step 110, the method further includes: acquiring TEM images of standard samples under different under-focus amounts; automatically measuring the thickness of the TEM image of the standard sample to obtain thicknesses corresponding to different under-focus amounts; and obtaining an under-focus-thickness fitting curve according to the thickness and the under-focus corresponding to the thickness.
Here, the amount of under-focus may be in the range of 0nm to 300 nm. The zero under-focus state is obtained when the under-focus amount is 0 nm.
Fig. 5 is a schematic diagram of a thickness measurement curve of a standard sample under different amounts of under-focus provided in this embodiment, and it should be noted that fig. 5 illustrates that the standard sample includes a target measurement structure, and the target measurement structure is a high-k dielectric layer. The standard sample may include a plurality of rows (e.g., nine rows) of channel holes arranged in a staggered manner, with R1-1 through R1-9 being the 9 target measurement structures in the first row of the standard sample and R5-1 through R5-9 being the 9 target measurement structures in the fifth row of the standard sample in FIG. 5. Here, the 9 target measurement structures in the first row are target measurement structures surrounded by the 9 channel holes in the first row in the standard sample, and the 9 target measurement structures in the fifth row are target measurement structures surrounded by the 9 channel holes in the fifth row in the standard sample. In FIG. 5, under the under-focus range of 0nm-300nm, the under-focus is selected with 50nm as the step length, and the thickness data are obtained by respective measurement. In some embodiments, the amount of under-focus may also be selected in steps of 10nm, 20nm, 30nm, etc. to obtain more thickness data. In the embodiment of the application, in the process of selecting the under-focus amount, an equidistant step length selecting mode can be adopted, and an unequal step length selecting mode can also be adopted.
Fig. 6 is a schematic diagram of an under-focus-thickness fitted curve of a standard sample provided in an embodiment of the present application, and it should be noted that fig. 6 is obtained by fitting the measurement data in fig. 5. In FIG. 6, L1-1 is a mean curve from R1-1 to R1-9, L1-2 is a linear fit curve from R1-1 to R1-9, L2-1 is a mean curve from R5-1 to R5-9, and L2-2 is a linear fit curve from R5-1 to R5-9. As shown in fig. 6, the measured thickness gradually increases as the amount of under-focus increases because the "bright edge" boundary of the target measurement structure widens as the amount of under-focus increases. In the embodiment of the application, the thickness of the standard sample under different under-focus amounts is obtained, and the relation between the under-focus amount and the thickness is quantified based on the thickness data. From the fitted curve shown in FIG. 6, it can be seen that the thickness is in the range of 100nm to 250nm in the amount of under-focusThe stability of the measurement is good. Therefore, the optimal under-focus range can be set to be 100nm-250nm, and then the preset under-focus amount is selected from the optimal under-focus range. In some preferred embodiments, the optimal under-focus range may also be set to 150nm-200 nm. From the comparison of L1-1 and L1-2 and the comparison of L2-1 and L2-2, it can be seen that the measurement error caused by the amount of under-focus is less than that in the optimum under-focus range of 100nm-250nm
(0.05nm), and under the optimal under-focus range of 100nm-250nm, the measurement precision of the target measurement structure can reach
(0.1nm)。
Here, the preset under-focus amount is a value in an optimum under-focus range for measuring the sample to be measured. Under the default under-focus quantity, the boundary of the sample to be measured is clear, and automatic thickness measurement is facilitated, so that the automatic measurement accuracy and precision are improved.
In the embodiment of the application, an optimal under-focus range is determined according to the under-focus-thickness fitting curve, a preset under-focus amount is selected in the optimal under-focus range, and a TEM image of a sample to be detected is acquired under the preset under-focus amount, in other words, the range of the preset under-focus amount is 100nm-250 nm. In practical application, the default under-focus amount is only one under-focus amount in the under-focus amount range of 100nm to 250 nm.
And 120, automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured.
In the embodiment of the application, based on the TEM image acquired under the preset under-focus amount, automatic thickness measurement is performed to obtain the measured thickness of the sample to be measured.
In one embodiment, the amount of under-focus may be determined from a Fast Fourier Transform (FFT) image of the TEM image at the time the TEM image is acquired. Fig. 7 is a TEM image and an FFT image provided in the embodiment of the present application, and it should be noted that fig. 7 illustrates an example in which the target measurement structure is a high-k dielectric layer, and a small image at the lower right corner of the TEM image in fig. 7 is the FFT image. It should be further noted that the under-focus amount at the upper left corner of the TEM image in fig. 7 is an added identifier for illustrating the under-focus amounts corresponding to different FFT images in the embodiment of the present application, and is not the under-focus amount of the TEM image itself in the actual test. As shown in FIG. 7, when 3-4 circles are displayed in the FFT image, it can be determined that the amount of under-focus is in the range of 150-200 nm. Therefore, the under-focus amount under the current magnification can be determined according to the FFT image, and the TEM image of the sample to be detected under the preset under-focus amount is obtained. At the moment, the boundary of the target measurement structure in the TEM image is clear, and the boundary of the target measurement structure can be very easily identified through automatic thickness measurement, so that the accurate measurement thickness is obtained.
And step 130, obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve.
In the embodiment of the application, the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample are obtained through an under-focus amount-thickness fitting curve; and obtaining the thickness drift amount under the preset under-focus according to the thickness of the standard sample corresponding to the preset under-focus and the zero under-focus thickness of the standard sample. Here, the zero under-focus thickness is a thickness corresponding to a 0nm under-focus amount (thickness in the case of positive focus).
In this embodiment of the application, a difference value between the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample is the thickness drift amount under the preset under-focus amount.
And 140, compensating the measured thickness based on the thickness drift amount to obtain the actual thickness of the sample to be measured.
In the embodiment of the application, the measured thickness is compensated according to the difference value between the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample, so as to obtain the actual thickness of the sample to be measured. For example, the measured thickness of the sample to be measured under the default under-focus amount is x, the thickness of the standard sample corresponding to the default under-focus amount is y and the zero under-focus thickness of the standard sample is z, which are obtained through an under-focus amount-thickness fitting curve. Therefore, the thickness drift amount is the difference y-z between the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample, and the actual thickness of the sample to be measured is obtained by subtracting the thickness drift amount y-z from the measured thickness x of the sample to be measured under the preset under-focus amount.
In the embodiment of the application, the standard sample and the sample to be detected are the same type of sample, and the structure and the material of the standard sample and the sample to be detected are the same. For example, the structure of the sample to be measured is an aluminum oxide layer surrounding the channel hole, and the structure of the calibration sample is also an aluminum oxide layer surrounding the channel hole. The calibration sample and the sample to be tested both comprise an aluminum oxide layer. Further, one sample among samples to be measured may be selected as the standard sample so that the standard sample has a referential property.
The thickness measuring method provided by the embodiment of the application can be suitable for measuring the thickness of various film layers, and is wide in application range.
| Number of |
9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | Average |
| T1-C | 3.546 | 3.464 | 3.431 | 3.367 | 3.378 | 3.417 | 3.485 | 3.567 | 3.457 | |
| T140-C | 3.282 | 3.250 | 3.228 | 3.237 | 3.232 | 3.239 | 3.248 | 3.271 | 3.296 | 3.253 |
Table one is data measured based on the thickness measurement method provided in the embodiment of the present application; wherein T1-C is the 1 st layer of the stacked structure in the sample to be tested, T140-C is the 140 th layer of the stacked structure in the sample to be tested, and the row numbers 1-9 are respectively surrounded by the channel holes of the first row to the ninth row in the sample to be testedA target measurement structure. Where row number 1 (first row) and row number 9 (ninth row) are located on the outside (Outer) and row number 5 (fifth row) is located on the inside (Inner). It should be noted that, in the layer 1 of the stacked structure in the sample to be measured, since the top select gate cut (TSG cut) exists in the middle row (the fifth row), the thickness data of the target measurement structure cannot be measured. FIG. 8 is a graph diagram illustrating the data obtained from Table I, and it can be seen from FIG. 8 that the thickness measurement method provided by the embodiment of the present application can distinguish the target measurement structure
(0.1nm), as shown in fig. 8, the data measured based on the thickness measurement method provided in the embodiment of the present application can very accurately distinguish the difference between the Outer side (Outer) and the Inner side (Inner) of the target measurement structure, and the difference between the target measurement structure at T1-C (layer 1) and T140-C (layer 140).
The embodiment of the application discloses a thickness measuring method and a system, wherein the method comprises the following steps: acquiring a TEM image of a sample to be detected under a preset under-focus amount; automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured; obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve; and compensating the measured thickness based on the thickness drift amount to obtain the actual thickness of the sample to be measured. By establishing the corresponding relation between the under-focus amount and the thickness, the thickness drift amount under the under-focus amount can be calculated according to the under-focus amount. Therefore, the measured thickness under the default under-focus amount is compensated according to the thickness drift amount, and the accurate actual thickness is obtained. According to the thickness measuring method, the thickness of the sample can be measured quickly and accurately without additional equipment. The measurement process is convenient and quick, the thickness can be automatically measured only by acquiring a TEM image under the preset under-focus amount, the thickness drift amount of the sample is calculated according to the corresponding relation between the under-focus amount and the thickness, and the measured thickness is compensated, so that the measurement period is short.
Based on the same technical concept of the foregoing thickness measurement method, an embodiment of the present application provides a thickness measurement system, and in some embodiments, the thickness measurement system may be implemented in a software module, and fig. 9 is a schematic structural diagram of a thickness measurement system provided in an embodiment of the present application, and referring to fig. 9, a thickness measurement system 900 provided in an embodiment of the present application includes:
an obtaining module 901, configured to obtain a TEM image of a sample to be detected at a preset under-focus amount;
a measuring module 902, configured to perform automatic thickness measurement on the TEM image of the sample to be measured, so as to obtain a measured thickness of the sample to be measured;
a calculating module 903, configured to obtain a thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve;
and a compensation module 904, configured to compensate the measured thickness based on the thickness drift amount to obtain an actual thickness of the sample to be measured.
In other embodiments, the acquiring module 901 is further configured to acquire TEM images of the standard sample at different under-focus amounts;
the measurement module 902 is further configured to perform automatic thickness measurement on the TEM image of the standard sample to obtain thicknesses corresponding to different amounts of under-focus;
further comprising: and the function module 905 is used for obtaining an under-focus-thickness fitting curve according to the thickness and the under-focus amount corresponding to the thickness.
In other embodiments, further comprising:
a determining module 906 for determining an optimal under-focus range according to the under-focus-thickness fitted curve.
In other embodiments, the preset under-focus amount is a value within the optimal under-focus range; the optimal under-focus range is 100nm-250 nm.
In other embodiments, the calculating module 903 is specifically configured to obtain the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample through an under-focus amount-thickness fitting curve;
and obtaining the thickness drift amount under the preset under-focus according to the thickness of the standard sample corresponding to the preset under-focus and the zero under-focus thickness of the standard sample.
In other embodiments, the sample to be tested comprises a channel hole and an aluminum oxide layer surrounding the channel hole;
the measuring module 902 is configured to perform automatic thickness measurement on the TEM image of the sample to be measured, so as to obtain a measured thickness of the alumina layer in the sample to be measured.
The components in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware or a form of a software functional module.
Based on the understanding that the technical solution of the embodiments of the present application, or a part thereof contributing to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a device having a processor function (such as a transmission electron microscope) to execute all or part of the steps of the method of the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
It is to be understood that the embodiments described herein may be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the Processing units may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), general purpose processors, controllers, micro-controllers, microprocessors, other electronic units configured to perform the functions described herein, or a combination thereof.
For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory and executed by a processor. The memory may be implemented within the processor or external to the processor.
It should be appreciated that reference throughout this specification to "an embodiment" or "some embodiments" means that a particular feature, structure or characteristic described in connection with the embodiments is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in embodiments of the present application" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiments. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
The methods disclosed in the several method embodiments provided in the present application may be combined arbitrarily without conflict to obtain new method embodiments.
The features disclosed in the several apparatus embodiments provided in the present application may be combined in any combination to arrive at new apparatus embodiments without conflict.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (12)
1. A method of thickness measurement, the method comprising:
acquiring a TEM image of a sample to be detected under a preset under-focus amount;
automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured;
obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve;
and compensating the measured thickness based on the thickness drift amount to obtain the actual thickness of the sample to be measured.
2. The thickness measurement method according to claim 1, wherein before acquiring the TEM image of the sample to be measured at the preset under-focus amount, the method further comprises:
acquiring TEM images of standard samples under different under-focus amounts;
automatically measuring the thickness of the TEM image of the standard sample to obtain thicknesses corresponding to different under-focus amounts;
and obtaining an under-focus-thickness fitting curve according to the thickness and the under-focus corresponding to the thickness.
3. The thickness measurement method according to claim 1, wherein before acquiring the TEM image of the sample to be measured at the preset under-focus amount, the method further comprises:
and determining the optimal under-focus range according to the under-focus amount-thickness fitting curve.
4. The thickness measurement method according to claim 3,
the preset under-focus amount is a value in the optimal under-focus range; the optimal under-focus range is 100nm-250 nm.
5. The method of claim 1, wherein the obtaining the thickness drift amount at the preset under-focus amount through an under-focus-thickness fitting curve comprises:
obtaining the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample through an under-focus amount-thickness fitting curve;
and obtaining the thickness drift amount under the preset under-focus according to the thickness of the standard sample corresponding to the preset under-focus and the zero under-focus thickness of the standard sample.
6. The thickness measurement method according to claim 2, wherein the sample to be measured includes a channel hole and an aluminum oxide layer surrounding the channel hole;
the automatic thickness measurement of the TEM image of the sample to be measured is carried out to obtain the measured thickness of the sample to be measured, and the method comprises the following steps:
and automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the alumina layer in the sample to be measured.
7. A thickness measurement system, comprising:
the acquisition module is used for acquiring a TEM image of a sample to be detected under a preset under-focus amount;
the measuring module is used for automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the sample to be measured;
the calculation module is used for obtaining the thickness drift amount under the preset under-focus amount through an under-focus amount-thickness fitting curve;
and the compensation module is used for compensating the measured thickness based on the thickness drift amount so as to obtain the actual thickness of the sample to be measured.
8. The thickness measurement system of claim 7,
the acquisition module is also used for acquiring TEM images of the standard samples under different under-focus amounts;
the measuring module is also used for automatically measuring the thickness of the TEM image of the standard sample to obtain the thicknesses corresponding to different under-focus amounts;
further comprising:
and the function module is used for obtaining an under-focus-thickness fitting curve according to the thickness and the under-focus corresponding to the thickness.
9. The thickness measurement system of claim 8, further comprising:
and the determining module is used for determining the optimal under-focus range according to the under-focus amount-thickness fitting curve.
10. The thickness measurement system of claim 9, wherein the preset amount of under-focus is a value within the optimal under-focus range; the optimal under-focus range is 100nm-250 nm.
11. The thickness measurement system of claim 9,
the calculation module is specifically used for obtaining the thickness of the standard sample corresponding to the preset under-focus amount and the zero under-focus thickness of the standard sample through an under-focus amount-thickness fitting curve;
and obtaining the thickness drift amount under the preset under-focus according to the thickness of the standard sample corresponding to the preset under-focus and the zero under-focus thickness of the standard sample.
12. The thickness measurement system of claim 11, wherein the sample to be tested comprises a channel hole and an aluminum oxide layer surrounding the channel hole;
and the measuring module is used for automatically measuring the thickness of the TEM image of the sample to be measured to obtain the measured thickness of the alumina layer in the sample to be measured.
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