Terahertz near-field system internal imaging height calibration method and device

Abstract

The invention provides a terahertz near-field system internal imaging height calibration method and device, relates to the field of terahertz near-field imaging, and solves the technical problem that the specific value of the terahertz near-field system internal imaging depth is difficult to determine in the prior art. The method specifically comprises the following steps: acquiring a surface image and an internal image of terahertz near-field imaging; dividing an internal material area into a uniform area and a non-uniform area based on the surface graph and the internal graph; calculating a first coefficient of the uniform region, and converting a voltage value of the internal graph of the uniform region into a first height based on the first coefficient; calculating a second coefficient of the non-uniform region in a segmented manner, and converting the voltage value of the internal graph of the non-uniform region into a second height based on the second coefficient corresponding to each segment; and calculating height compensation based on the surface graph and the internal graph of the substrate, superposing the first height and the height compensation to obtain an internal height calibration value of the uniform region, and superposing the second height and the height compensation to obtain an internal height calibration value of the non-uniform region. The method is used for terahertz internal imaging height calibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of terahertz near-field imaging, in particular to a height calibration method and device for internal imaging of a terahertz near-field system. BACKGROUND

[0002] The terahertz near-field imaging technology has important application significance in the fields of depth calibration of cell organelles inside cells and detection of micro-defects inside materials, due to its nanoscale imaging accuracy and non-invasive penetration capability for biological and semiconductor materials. The current terahertz near-field imaging system can simultaneously complete surface imaging and internal imaging of a sample. The surface image is directly annotated with height as a unit to intuitively present the surface structure characteristics, and the internal image is obtained by collecting the voltage value of the residual signal after the material absorbs the terahertz signal, and then fitting the image by point-by-point scanning. However, there is a lack of clear and universal conversion logic between the voltage value of the internal image and the actual height value. Especially when there are differences in material uniformity inside the sample, it is difficult to directly convert the voltage value into quantifiable depth information, and it is also difficult to achieve height calibration of different material regions in a unified way, resulting in that the specific depth position of the target such as cell organelles or micro-defects in materials cannot be accurately obtained in actual application. Therefore, the prior art has the technical problem that the depth of the internal imaging of the terahertz near-field system is difficult to determine. SUMMARY

[0003] The present application provides a height calibration method and device for internal imaging of a terahertz near-field system, which solves the technical problem that the depth of the internal imaging of the terahertz near-field system is difficult to determine in the prior art.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect, a height calibration method for internal imaging of a terahertz near-field system is provided, comprising: obtaining a surface image and an internal image of terahertz near-field imaging; dividing an internal material region into a uniform region and a non-uniform region based on the comparison of image features of the surface image and the internal image; calculating a first coefficient of the uniform region, and converting the voltage value of the internal image of the uniform region into a first height based on the first coefficient; calculating a second coefficient of the non-uniform region in segments, and converting the voltage value of the internal image of the non-uniform region into a second height based on the corresponding second coefficient of each segment; calculating a height compensation based on the surface image and the internal image of the substrate, and superimposing the first height and the height compensation to obtain an internal height calibration value of the uniform region, and superimposing the second height and the height compensation to obtain an internal height calibration value of the non-uniform region.

[0005] In a possible implementation manner of the first aspect, the internal material region is divided into a uniform area and a non-uniform area based on a comparison of image features of the surface map and the internal map, including: determining whether the height feature of the surface map is consistent, and whether the internal map voltage size feature of the same pixel area of the surface map is consistent; if there is no pixel point with color depth change in the same pixel area, the same pixel area is determined as the uniform area; if there is at least one pixel with color depth change inconsistent with the surrounding pixels in the same pixel area, the same pixel area is determined as the non-uniform area.

[0006] In a possible implementation manner of the first aspect, the first coefficient of the uniform area is calculated, and the voltage value of the internal map of the uniform area is converted into the first height based on the first coefficient, including: selecting feature points A and B at the same positions of the surface map and the internal map of the uniform area; obtaining the surface height value of the feature point A corresponding to the surface map, the surface height value of the feature point B corresponding to the surface map, the voltage value of the feature point A corresponding to the internal map, and the voltage value of the feature point B corresponding to the internal map; calculating the first coefficient of the uniform area; traversing all pixel points of the uniform area, obtaining the voltage value of each pixel point in the internal map , and calculating the first height of the pixel point based on the first coefficient and .

[0007] In a possible implementation manner of the first aspect, the first height of the pixel point calculated based on the first coefficient and satisfies the following formula:

[0008] wherein, the first height , the first coefficient satisfies: .

[0009] In a possible implementation manner of the first aspect, the second coefficient of the non-uniform area is calculated in segments, and the voltage value of the internal map of the non-uniform area is converted into the second height based on the second coefficient corresponding to each segment, including: dividing the non-uniform area into n continuous subsegments; for each subsegment, selecting feature points C and D at the same positions of the surface map and the internal map of the subsegment, respectively; obtaining the surface height value of the feature point C corresponding to the surface map of the subsegment, the surface height value of the feature point D corresponding to the surface map of the subsegment, the voltage value of the feature point C corresponding to the internal map of the subsegment, and the voltage value of the feature point D corresponding to the internal map of the subsegment; calculating the second coefficient corresponding to the subsegment; traversing all pixel points of each subsegment, obtaining the voltage value of each pixel point in the internal map , the second coefficient of the sub-section and the corresponding The second height of the pixel point is calculated.

[0010] In a possible implementation manner of the first aspect, the second coefficient of the sub-section and the corresponding The second height of the pixel point is calculated.

[0011] wherein, is the second height of the pixel point in the i th sub-section, i is a sub-section index, and i satisfies i = 1, 2,..., n, is the second coefficient corresponding to the i th sub-section, and satisfies: , is the surface height value corresponding to the feature point C in the surface map of the i th sub-section, is the surface height value corresponding to the feature point D in the surface map of the i th sub-section, is the voltage value corresponding to the feature point C in the internal map of the i th sub-section, is the voltage value corresponding to the feature point D in the internal map of the i th sub-section, is the voltage value of the pixel point in the i th sub-section in the internal map.

[0012] In a possible implementation manner of the first aspect, the height compensation is calculated based on the surface map and the internal map of the substrate, including: obtaining a substrate surface height value of the substrate region in the surface map, and a substrate internal voltage value of the substrate region in the internal map at a position corresponding to the substrate surface height value; calculating a substrate preliminary height of the substrate region; and determining a difference between the substrate surface height value and the substrate preliminary height as the height compensation.

[0013] In a possible implementation manner of the first aspect, the first height and the height compensation are superimposed to obtain an internal height calibration value in the uniform region, and the second height and the height compensation are superimposed to obtain an internal height calibration value in the non-uniform region, including: performing summation operation on the first height and the height compensation of each pixel point in the uniform region to obtain an internal height calibration value corresponding to the pixel point in the uniform region; and performing summation operation on the second height and the height compensation of each pixel point in each sub-section of the non-uniform region to obtain an internal height calibration value corresponding to the pixel point in the non-uniform region.

[0014] In a possible implementation manner of the first aspect, the substrate region is a sample-free coverage region.

[0015] In a second aspect, a height calibration device for internal imaging of a terahertz near-field system is provided, and includes a communication unit and a processing unit. The communication unit is configured to obtain a surface image and an internal image of terahertz near-field imaging. The processing unit is configured to divide an internal material region into a uniform region and a non-uniform region based on a comparison of image features of the surface image and the internal image. The processing unit is further configured to calculate a first coefficient of the uniform region, and convert a voltage value of the internal image of the uniform region into a first height based on the first coefficient. The processing unit is further configured to calculate a second coefficient of the non-uniform region in segments, and convert a voltage value of the internal image of the non-uniform region into a second height based on the second coefficient corresponding to each segment. The processing unit is further configured to calculate a height compensation based on the surface image and the internal image of the substrate, superimpose the first height and the height compensation to obtain an internal height calibration value of the uniform region, and superimpose the second height and the height compensation to obtain an internal height calibration value of the non-uniform region.

[0016] In a third aspect, a height calibration device for internal imaging of a terahertz near-field system is provided, and includes a processor and a storage medium. The storage medium includes instructions, and the processor is configured to execute the instructions to implement the method described in the first aspect and any possible implementation manner of the first aspect. The height calibration device for internal imaging of the terahertz near-field system can be an electronic device, or a chip in the electronic device.

[0017] In a fourth aspect, a height calibration system for internal imaging of a terahertz near-field system is provided, and includes a terahertz imaging device and an electronic device. The terahertz imaging device is configured to collect a surface image and an internal image of terahertz near-field imaging. The electronic device is configured to obtain the surface image and the internal image of the terahertz near-field imaging. The electronic device is further configured to divide an internal material region into a uniform region and a non-uniform region based on a comparison of image features of the surface image and the internal image. The electronic device is further configured to calculate a first coefficient of the uniform region, and convert a voltage value of the internal image of the uniform region into a first height based on the first coefficient. The electronic device is further configured to calculate a second coefficient of the non-uniform region in segments, and convert a voltage value of the internal image of the non-uniform region into a second height based on the second coefficient corresponding to each segment. The electronic device is further configured to calculate a height compensation based on the surface image and the internal image of the substrate, superimpose the first height and the height compensation to obtain an internal height calibration value of the uniform region, and superimpose the second height and the height compensation to obtain an internal height calibration value of the non-uniform region.

[0018] In a fifth aspect, a computer-readable storage medium is provided, and the computer-readable storage medium stores instructions. When the instructions are executed on a height calibration device for internal imaging of a terahertz near-field system, the height calibration device for internal imaging of the terahertz near-field system performs the method described in the first aspect and any possible implementation manner of the first aspect.

[0019] In a sixth aspect, the present application provides a computer program product comprising instructions which, when the computer program product runs on the terahertz near-field system internal imaging height calibration device, causes the terahertz near-field system internal imaging height calibration device to perform the method as described in the first aspect and any possible implementation manner of the first aspect.

[0020] The present application provides a terahertz near-field system internal imaging height calibration method and device, by acquiring a sample surface image and an internal image and dividing uniform and non-uniform regions based on image feature comparison, calculating a first coefficient for the uniform region and a second coefficient for the non-uniform region, realizing accurate conversion of internal image voltage values to height values in different material regions, and combining surface image and internal image of the substrate region to calculate height compensation to correct conversion deviation, finally obtaining accurate internal height calibration values of the uniform and non-uniform regions; it not only continues the non-destructive characteristics of terahertz technology, but also has the advantages of simple operation and convenient calculation, and can complete height calibration without complex equipment or additional processes, solving the technical problem that the specific value of the terahertz near-field system internal imaging depth is difficult to determine in the prior art.

[0021] It should be understood that the description of technical features, technical solutions, beneficial effects or similar language in the present application does not imply that all features and advantages can be achieved in any single embodiment. On the contrary, it can be understood that the description of a feature or beneficial effect means that the specific technical feature, technical solution or beneficial effect is included in at least one embodiment. Therefore, the description of technical features, technical solutions or beneficial effects in the specification does not necessarily refer to the same embodiment. Further, the technical features, technical solutions and beneficial effects described in the embodiments can be combined in any appropriate manner. Those skilled in the art will understand that the embodiments can be implemented without one or more specific technical features, technical solutions or beneficial effects of a particular embodiment. In other embodiments, additional technical features and beneficial effects can be identified in specific embodiments that do not embody all embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A system architecture diagram of a terahertz near-field system internal imaging height calibration system provided by an embodiment of the present application; Figure 2 A flowchart of a terahertz near-field system internal imaging height calibration method provided by an embodiment of the present application; Figure 3 A near-field imaging surface image diagram provided by an embodiment of the present application; Figure 4 A near-field imaging internal image diagram provided by an embodiment of the present application; Figure 5A near-field imaging surface image selection uniform region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 6 A near-field imaging internal image selection uniform region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 7 A near-field imaging surface image and selection non-uniform region schematic diagram provided for an embodiment of the present application; Figure 8 A near-field imaging internal image and selection non-uniform region schematic diagram provided for an embodiment of the present application; Figure 9 A near-field imaging surface image selection non-uniform region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 10 Another near-field imaging surface image selection non-uniform region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 11 A near-field imaging internal image selection non-uniform region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 12 Another near-field imaging internal image selection non-uniform region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 13 A near-field imaging surface image and substrate region schematic diagram provided for an embodiment of the present application; Figure 14 A near-field imaging internal image and substrate region schematic diagram provided for an embodiment of the present application; Figure 15 A near-field imaging surface image substrate region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 16 A near-field imaging internal image substrate region profile height analysis schematic diagram provided for an embodiment of the present application; Figure 17 A structure schematic diagram of a terahertz near-field system internal imaging height calibration device provided for an embodiment of the present application; Figure 18 A hardware structure schematic diagram of a terahertz near-field system internal imaging height calibration device provided for an embodiment of the present application. DETAILED DESCRIPTION

[0023] In the description of the present application, unless otherwise specified, " / " means "or", for example, A / B can mean A or B. "And / or" in this article is only a description of the relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean: A exists alone, A and B exist together, and B exists alone. In addition, "at least one" means one or more, and "multiple" means two or more. "First", "second", and the like do not limit the quantity and execution order, and "first", "second", and the like do not necessarily mean different.

[0024] It should be noted that in this application, "exemplary" or "for example" means to serve as an example, illustration, or description. Any embodiment or design scheme described as "exemplary" or "for example" in this application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the use of "exemplary" or "for example" is intended to present the relevant concept in a specific manner.

[0025] The internal height calibration method of the terahertz near-field system provided by the embodiments of the present application can be applied to the internal height calibration system of the terahertz near-field system as shown in the figure, which comprises a terahertz imaging device 101 and an electronic device 102. Figure 1 As shown in the figure, the internal height calibration system of the terahertz near-field system comprises a terahertz imaging device 101 and an electronic device 102.

[0026] The terahertz imaging device 101 is used to collect the surface image and internal image of the terahertz near-field imaging; the electronic device 102 is used to obtain the surface image and internal image of the terahertz near-field imaging; based on the comparison of the image features of the surface image and the internal image, the internal material region is divided into a uniform region and a non-uniform region; the first coefficient of the uniform region is calculated, and the voltage value of the internal image of the uniform region is converted into the first height based on the first coefficient; the second coefficient of the non-uniform region is calculated in segments, and the voltage value of the internal image of the non-uniform region is converted into the second height based on the corresponding second coefficient of each segment; the height compensation is calculated based on the surface image and the internal image of the substrate, the first height and the height compensation are superimposed to obtain the internal height calibration value of the uniform region, and the second height and the height compensation are superimposed to obtain the internal height calibration value of the non-uniform region.

[0027] To solve the technical problem that the specific value of the internal imaging depth of the existing terahertz near-field system is difficult to determine, the embodiment of the present application provides a kind of terahertz near-field system internal imaging height calibration method, the method comprises: using terahertz near-field imaging system to obtain the surface graph and internal graph of sample, and the uniform area and non-uniform area of internal material are divided by comparing the image features of the two; the first coefficient is calculated for the uniform area, and the voltage value of the internal graph of the uniform area is converted into the first height based on the first coefficient; the second coefficient is calculated for the non-uniform area, and the voltage value of the corresponding internal graph is converted into the second height based on the second coefficient of each segment; then, based on the surface graph and internal graph of the substrate, the height compensation is calculated, and the first height and the second height are superimposed with the height compensation respectively to obtain the internal height calibration value of the uniform area and the non-uniform area, based on which, the present method can accurately realize the conversion of internal voltage value to height value, effectively solve the problem of difficult determination of internal imaging depth, and has the characteristics of non-injury, which can be adapted to the depth calibration of biological cell organelle, material internal microdefect and other scenes, and is simple in operation and convenient in calculation, which significantly improves the practicality and accuracy of terahertz near-field imaging system in analyzing the depth information of sample internal structure.

[0028] As shown in Figure 2 , the terahertz near-field system internal imaging height calibration method provided by the embodiment of the present application comprises: S201, obtain the surface graph and internal graph of terahertz near-field imaging.

[0029] Among them, the surface graph refers to the image generated after the sample surface is scanned by the terahertz near-field imaging system, which stores the height value of each position with pixel coordinates as index; the internal graph refers to the image generated after the sample internal scanning by the system, which stores the residual voltage value of each position terahertz signal with the same pixel coordinates as the surface graph as index.

[0030] In the embodiment of the present application, the terahertz imaging device synchronously scans the whole domain of the sample, synchronously collects the height signal of the sample surface and the voltage signal remaining after the internal material absorbs the terahertz energy, then fits the collected height signal into the surface graph and the voltage signal into the internal graph, and stores the two images in the local cache with the same pixel coordinates, and the electronic device obtains the surface graph and internal graph of terahertz near-field imaging by calling the local cache.

[0031] It should be pointed out that the scanning process of the surface graph and the internal graph is synchronous, and the pixel coordinates of the two are completely aligned, which ensures that the feature comparison and data conversion of each position can be realized based on the same coordinate basis.

[0032] As an example, a high-speed matrix terahertz camera is used to collect the surface graph and the internal graph, and the electronic device obtains the near-field imaging surface image as shown in Figure 3 and the internal image as shown in Figure 4The near-field imaging internal image is shown, and each pixel coordinate of the two images corresponds one by one.

[0033] Based on the above steps, the core data of the sample surface and the interior can be synchronously obtained, thereby providing complete and aligned original data support for subsequent material region division, voltage and height conversion.

[0034] S202, based on the image feature comparison of the surface map and the internal map, the internal material region is divided into uniform regions and non-uniform regions.

[0035] The image features include the height depth features of the surface map and the voltage size features of the internal map.

[0036] In the embodiments of the present application, the electronic device first extracts the height depth feature value of each pixel in the surface map and the voltage size feature value of the same pixel in the internal map, and then traverses the continuous pixel region of the sample whole domain to determine whether the height depth features of the surface map are consistent and whether the voltage size features of the internal map of the same pixel region are consistent. If there is no pixel point with color depth change in the same pixel region, it is determined as a uniform region; if there is at least one pixel with color depth change inconsistent with the surrounding pixels in the same pixel region, it is determined as a non-uniform region.

[0037] As an example, Figure 4 The color of region A suddenly becomes deep, and Figure 3 The light color feature of the corresponding region does not match, and is marked as a non-uniform region.

[0038] Based on the above steps, the uniformity difference of the internal material of the sample can be accurately identified, and the conversion error caused by the difference in material uniformity can be avoided.

[0039] S203, calculating a first coefficient of the uniform region, and converting the voltage value of the internal map of the uniform region into a first height based on the first coefficient.

[0040] The first coefficient refers to the ratio of "surface height difference to internal voltage difference" in the uniform region, and is used to establish the conversion relationship between the voltage value and the height value of the uniform region; the first height refers to the preliminary height value obtained by converting the voltage value of the internal map of the uniform region by the first coefficient.

[0041] In the embodiments of the present application, the electronic device selects feature points A and B at the same position of the surface map and the internal map of the uniform region; obtains the surface height value of the feature point A , the surface height value of the feature point B , the voltage value of the feature point A , and the voltage value of the feature point B Then, the surface height difference ΔH = HB - HA and the voltage difference ΔV = VB - VA are calculated, and the ratio of the height difference to the voltage difference is used to obtain the first coefficient. Finally, all pixels in the uniform region are traversed, and the voltage value V1 of each pixel is read. Based on the first coefficient and... Calculate the first height of the pixel.

[0042] Optionally, based on the first coefficient and The first height of this pixel is calculated according to the following formula:

[0043] in, As the highest point, As the first coefficient, it satisfies: .

[0044] As an example, draw a line in the surface view and the interior view respectively, such as Figure 3 and Figure 4 As shown, a cross-sectional analysis of the line is then performed, as follows. Figure 5 and Figure 6 As shown, Figure 5 Select feature points , Read the surface image The corresponding HA=257nm The corresponding HB=466nm, such as Figure 6 Read the image The corresponding VA = 0.16V The corresponding VB = -0.01V; calculate ΔH = 466 - 257 = 209nm, ΔV = -0.01 - 0.16 = -0.17V, and obtain the first coefficient. =209 / -0.17≈-1229nm / V, If the voltage value V1 = 0.16V, then its first height H1 is calculated to be approximately -1229 × 0.16 ≈ -197nm.

[0045] It should be noted that the surface and internal images are selected from the same locations on the sample. and , Figure 5 Displayed in A very small height value before the location indicates that there is no sample on the surface. This marks a turning point where the altitude begins to rise. This marks a turning point after an increase in altitude followed by a decrease. (Corresponding to...) Figure 6 middle The voltage drop before the position is small. The location marks a turning point where the descent begins. The inflection point is the point where the voltage drops and then rises again. The surface plot and the internal plot correspond to each other, representing the surface and internal voltages of a uniform sample.

[0046] Based on the above steps, the accurate conversion of voltage values ​​to height values ​​within the uniform region is achieved.

[0047] S204. Calculate the second coefficient of the non-uniform region segment by segment, and convert the voltage value of the internal diagram of the non-uniform region into the second height based on the second coefficient corresponding to each segment.

[0048] Here, segmentation refers to the continuous pixel region divided by the boundary of abrupt change in voltage magnitude in a non-uniform region; the second coefficient is the ratio of the surface height difference to the internal voltage difference in each sub-segment, used to establish the voltage-height conversion relationship of the corresponding sub-segment; the second height is the preliminary height value obtained after the internal image voltage value in the sub-segment is converted by the corresponding second coefficient.

[0049] In this embodiment, the non-uniform region is divided into n continuous sub-segments; for each sub-segment i (i=1,2,...,n), feature points C and D are selected at the same positions in the surface and internal maps of the sub-segment, respectively; the surface height value corresponding to feature point C in the surface map of the sub-segment is obtained. Surface height value corresponding to feature point D Obtain the voltage value corresponding to feature point C in the sub-segment internal graph. Voltage value corresponding to feature point D Calculate the second coefficient corresponding to the sub-segment; iterate through all pixels of each sub-segment and obtain the voltage value of each pixel in the internal graph. The second coefficient based on the sub-segment and the corresponding Calculate the second height of this pixel.

[0050] Optionally, the second coefficient based on the sub-segment and the corresponding The second height of this pixel is calculated according to the following formula:

[0051] in, Let i be the second height of a pixel within the i-th sub-segment, where i is the sub-segment index, satisfying i=1,2,...,n. The second coefficient corresponding to the i-th sub-segment satisfies: , Let C be the surface height value corresponding to feature point C in the surface map of the i-th sub-segment. Let D be the surface height value corresponding to feature point D in the surface map of the i-th sub-segment. Let C be the voltage value corresponding to feature point C in the internal graph of the i-th sub-segment. Let be the voltage value corresponding to feature point D in the graph of the i-th sub-segment. The voltage value of the pixel point in the internal graph in the i-th sub-section.

[0052] As an example, as shown in Figure 7 With Figure 8 The line is divided into two sub-sections by profile analysis of the line, as shown in Figure 9 The first section contains feature points y1 and y2, as shown in Figure 10 The second section contains feature points y2 and y3; H1=261nm corresponding to y1 in the first section, H2=407nm corresponding to y2, as shown in Figure 11 V1=0.11V corresponding to y1, V2=-0.09V corresponding to y2, as shown in ΔH1=407-261=146nm, ΔV1=-0.09-0.11=-0.20V, Figure 10 =146 / -0.20=-730nm / V; as shown in Figure 12 H3=523nm corresponding to y3 in the second section, as shown in V3=-0.17V corresponding to y3, as shown in ΔH2=523-407=116nm, ΔV2=-0.17-(-0.09)=-0.08V, =116 / -0.08=-1450nm / V; traverse the first section pixel, such as the internal graph voltage value of feature point y1 is =0.11V, as shown in

[0053] =-730*0.11≈-80nm.

[0054] Based on the above steps, the material absorption characteristics of each sub-section of the non-uniform area are accurately matched with the voltage-height correlation law, the conversion deviation problem caused by the material difference of the non-uniform area is solved, and the accuracy and fitting degree of the internal height conversion of the non-uniform area are improved.

[0055] Wherein, the height compensation is the compensation amount for correcting the deviation between the preliminary height value and the actual height value; the base area is the blank area without sample coverage, and the surface height is the known actual height, which can be used as the reference for deviation correction.

[0056] In the embodiment of the present application, the substrate surface height value of the substrate region in the surface image and the substrate internal voltage value of the substrate region in the internal image corresponding to the position of the substrate surface height value are obtained, the substrate preliminary height of the substrate region is calculated based on the first coefficient mode calculated in S203; the difference between the substrate surface height value and the substrate preliminary height is determined as the height compensation; finally, all pixels in the uniform region are traversed, the first height is superimposed with the height compensation to obtain the internal height calibration value of the uniform region, and the second height is superimposed with the height compensation to obtain the internal height calibration value of the non-uniform region, and the pixel coordinates are stored as the height calibration map.

[0057] As an example, as shown in Figure 13 and Figure 14 , the lines are drawn in the surface image and the internal image of the substrate respectively, as shown in Figure 15 , the surface height value h0=248(253)nm of the region is obtained, as shown in Figure 16 , the voltage value v0=0.166(0.17)V of the corresponding region is obtained; the substrate preliminary height is calculated according to the ratio, h0’=-1229*0.166≈-204nm; the height compensation =248-(-204)=452nm is obtained; the first height-197nm in S203 is superimposed with 452nm to obtain the internal height calibration value 255nm of the uniform region of the pixel; the second height-80nm of the first segment y1 in S204 is superimposed with 452nm to obtain the internal height calibration value 372nm of the non-uniform region of the pixel.

[0058] Based on the above steps, the systematic deviation between the preliminary height value and the actual height value is effectively eliminated, and the finally obtained internal height calibration value accurately reflects the actual depth of the internal structure of the sample.

[0059] Based on the above technical solution, from the original image acquisition to the output of the final height calibration value, the core problem that the specific value of the internal imaging depth is difficult to determine in the prior art is solved, the calibration accuracy is ensured through partition conversion and substrate compensation, and the non-destructive characteristics of terahertz technology are reserved. The depth calibration demand of biological cell organelle, semiconductor material micro-defect and other scenes can be flexibly adapted, the operation process is simple, and the calculation logic is clear.

[0060] The above describes the scheme of the embodiments of the present application mainly from the perspective of device implementation. It can be understood that, in order to implement the above functions, each device, for example, the internal height calibration device of the terahertz near-field system, comprises at least one of the corresponding hardware structure and software module for executing each function. Those skilled in the art should easily realize that, in combination with the units and algorithm steps of the examples described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is implemented in hardware or computer software driven hardware depends on the specific application of the technical scheme and the design constraint conditions. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0061] The embodiments of the present application can divide the functional units of the internal height calibration device of the terahertz near-field system according to the above method examples, for example, each functional unit can be divided according to each function, or two or more functions can be integrated in one processing unit. The above integrated unit can be implemented in the form of hardware or software functional unit. It should be noted that the division of units in the embodiments of the present application is illustrative, and is only a logical functional division. When actually implemented, there can be another division method.

[0062] In the case of using integrated units, Figure 17 A possible structure schematic diagram of the internal height calibration device of the terahertz near-field system (denoted as internal height calibration device of the terahertz near-field system 170) involved in the above embodiments is shown, which comprises a processing unit 1701 and a communication unit 1702, and can further comprise a storage unit 1703. Figure 17 The structure schematic diagram shown can be used to illustrate the structure of the internal height calibration device of the terahertz near-field system involved in the above embodiments.

[0063] When Figure 17 When the structure schematic diagram is used to illustrate the structure of the internal height calibration device of the terahertz near-field system involved in the above embodiments, the processing unit 1701 is used to control and manage the actions of the internal height calibration device of the terahertz near-field system, the communication unit 1702 is used for communication between the internal height calibration device of the terahertz near-field system and other devices, and the storage unit 1703 is used to store the program code and data of the internal height calibration device of the terahertz near-field system.

[0064] For example, the communication unit 1702 is used to obtain the surface image and internal image of the terahertz near-field imaging; The processing unit 1701 is configured to divide the internal material region into a uniform area and a non-uniform area based on a comparison of image features of the surface image and the internal image; calculate a first coefficient of the uniform area, and convert a voltage value of the internal image of the uniform area into a first height based on the first coefficient; calculate a second coefficient of the non-uniform area in segments, and convert a voltage value of the internal image of the non-uniform area into a second height based on the second coefficient corresponding to each segment; calculate a height compensation based on the surface image and the internal image of the substrate, superimpose the first height and the height compensation to obtain an internal height calibration value of the uniform area, and superimpose the second height and the height compensation to obtain an internal height calibration value of the non-uniform area.

[0065] In a possible implementation, the processing unit 1701 is further configured to divide the internal material region into a uniform area and a non-uniform area based on a comparison of image features of the surface image and the internal image, including: determining whether the height feature of the surface image is consistent, and whether the internal image voltage size feature of the same pixel region of the surface image is consistent; if there is no pixel point with color depth change in the same pixel region, the same pixel region is determined as the uniform area; and if there is at least one pixel with color depth change inconsistent with the surrounding pixels in the same pixel region, the same pixel region is determined as the non-uniform area.

[0066] In a possible implementation, the processing unit 1701 is further configured to calculate a first coefficient of the uniform area, and convert a voltage value of the internal image of the uniform area into a first height based on the first coefficient, including: selecting feature points A and B at the same positions of the surface image and the internal image of the uniform area; obtaining a surface height value corresponding to the feature point A , a surface height value corresponding to the feature point B , a voltage value corresponding to the feature point A , and a voltage value corresponding to the feature point B in the internal image; calculating the first coefficient of the uniform area; traversing all pixel points of the uniform area to obtain a voltage value of each pixel point in the internal image, and calculating a first height of the pixel point based on the first coefficient and .

[0067] In a possible implementation, the first height of the pixel point calculated based on the first coefficient and satisfies the following formula:

[0068] wherein, h is the first height, and a is the first coefficient, and satisfies: .

[0069] In a possible implementation, the processing unit 1701 is further configured to calculate the second coefficient of the non-uniform area in segments, and convert the voltage value of the internal graph of the non-uniform area to the second height based on the corresponding second coefficient of each segment, including: dividing the non-uniform area into n continuous subsegments; for each subsegment, selecting a feature point C and a feature point D at the same position of the surface graph and the internal graph of the subsegment, respectively; obtaining the surface height value corresponding to the feature point C in the surface graph of the subsegment , the surface height value corresponding to the feature point D , the voltage value corresponding to the feature point C in the internal graph of the subsegment , the voltage value corresponding to the feature point D ; calculating the second coefficient corresponding to the subsegment; traversing all pixel points of each subsegment to obtain the voltage value of each pixel point in the internal graph , calculating the second height of the pixel point based on the second coefficient of the subsegment and the corresponding .

[0070] In a possible implementation, the calculation of the second height of the pixel point based on the second coefficient of the subsegment and the corresponding satisfies the following formula:

[0071] wherein, h i is the second height of the pixel point in the i th subsegment, i is the subsegment index, and i satisfies i = 1, 2,..., n, is the second coefficient corresponding to the i th subsegment, and satisfies: , is the surface height value corresponding to the feature point C in the surface graph of the i th subsegment, is the surface height value corresponding to the feature point D in the surface graph of the i th subsegment, is the voltage value corresponding to the feature point C in the internal graph of the i th subsegment, is the voltage value corresponding to the feature point D in the internal graph of the i th subsegment, is the voltage value of the pixel point in the i th subsegment in the internal graph.

[0072] In a possible implementation, the processing unit 1701 is further configured to calculate the height compensation based on the surface graph and the internal graph of the substrate, including: obtaining the substrate surface height value of the substrate area in the surface graph, and the substrate internal voltage value of the substrate area in the internal graph corresponding to the substrate surface height value; calculating the substrate preliminary height of the substrate area; and determining the difference between the substrate surface height value and the substrate preliminary height as the height compensation.

[0073] ​In a possible implementation, the processing unit 1701 is further configured to superimpose the first height and the height compensation to obtain the uniform intra-zone height calibration value, and superimpose the second height and the height compensation to obtain the non-uniform intra-zone height calibration value, by: performing summation operation on the first height and the height compensation of each pixel point in the uniform zone to obtain the uniform intra-zone height calibration value corresponding to the pixel point; and performing summation operation on the second height and the height compensation of each pixel point in each sub-section of the non-uniform zone to obtain the non-uniform intra-zone height calibration value corresponding to the pixel point.

[0074] In a possible implementation, the substrate region is a sample-free coverage region.

[0075] The processing unit 1701 can be a processor or a controller, and the communication unit 1702 can be a communication interface, a transceiver, a transceiver, a transceiver circuit, a transceiver device, or the like. The communication interface is a general term, and can include one or more interfaces. The storage unit 1703 can be a memory. When the terahertz near-field system internal imaging height calibration device 170 is a chip, the processing unit 1701 can be a processor or a controller, and the communication unit 1702 can be an input interface and / or an output interface, a pin or a circuit, or the like. The storage unit 1703 can be a storage unit (for example, a register, a cache, or the like) in the chip, or can be a storage unit (for example, a read-only memory (ROM), a random access memory (RAM), or the like) located outside the chip.

[0076] The communication unit can also be referred to as a transceiving unit. The antenna and control circuit with transceiving function in the terahertz near-field system internal imaging height calibration device 170 can be regarded as the communication unit 1702 of the terahertz near-field system internal imaging height calibration device 170, and the processor with processing function can be regarded as the processing unit 1701 of the terahertz near-field system internal imaging height calibration device 170. Optionally, the device for realizing the receiving function in the communication unit 1702 can be regarded as a communication unit, and the communication unit is configured to perform the receiving steps in the embodiments of the present application, and the communication unit can be a receiver, a receiver, a receiving circuit, or the like. The device for realizing the sending function in the communication unit 1702 can be regarded as a sending unit, and the sending unit is configured to perform the sending steps in the embodiments of the present application, and the sending unit can be a transmitter, a transmitter, a sending circuit, or the like.

[0077] Figure 17The integrated units in the above embodiments, if realized in the form of software function modules and sold or used as independent products, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the embodiments of the present application essentially or say the parts that make contributions to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to perform all or part of the steps of the methods described in the embodiments of the present application. The storage medium storing the computer software product includes a U disk, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk, and various media that can store program codes.

[0078] Figure 17 The units in the above embodiments can also be referred to as modules, for example, the processing unit can be referred to as a processing module.

[0079] The present application also provides a hardware structure diagram of a terahertz near-field system internal imaging height calibration device (denoted as terahertz near-field system internal imaging height calibration device 180), which is shown in Figure 18 The terahertz near-field system internal imaging height calibration device 180 includes a processor 1801, and optionally, a memory 1802 connected with the processor 1801.

[0080] In a first possible implementation, referring to Figure 18 The terahertz near-field system internal imaging height calibration device 180 further includes a transceiver 1803. The processor 1801, the memory 1802 and the transceiver 1803 are connected through a bus. The transceiver 1803 is configured to communicate with other devices or communication networks. Optionally, the transceiver 1803 can include a transmitter and a receiver. The device for realizing the receiving function in the transceiver 1803 can be regarded as a receiver, and the receiver is configured to perform the receiving steps in the embodiments of the present application. The device for realizing the sending function in the transceiver 1803 can be regarded as a transmitter, and the transmitter is configured to perform the sending steps in the embodiments of the present application.

[0081] Based on the first possible implementation, Figure 18 The structure diagram shown in the above can be used to show the structure of the terahertz near-field system internal imaging height calibration device involved in the above embodiments.

[0082] Among them, Figure 18 The system chip in the terahertz near-field system internal imaging height calibration device can also be shown. In this case, the actions performed by the above terahertz near-field system internal imaging height calibration device can be realized by the system chip, and the specific actions performed can be referred to in the above, which will not be described here.

[0083] In the implementation process, the steps in the method provided by the embodiment can be completed by the integrated logic circuit of hardware in the processor or the instructions in the form of software. The steps of the method disclosed by the embodiment of the present application can be directly embodied as hardware processor execution completion, or execution completion by hardware and software module combination in the processor.

[0084] The processor in the present application can include but is not limited to at least one of the following: central processing unit (CPU), microprocessor, digital signal processor (DSP), microcontroller unit (MCU), or various types of computing devices running software such as artificial intelligence processors, each of which can include one or more cores for executing software instructions to perform operations or processing. The processor can be a separate semiconductor chip, or can be integrated with other circuits as a semiconductor chip, for example, it can form a SoC (system on chip) with other circuits (such as coding and decoding circuits, hardware acceleration circuits, or various bus and interface circuits), or it can be integrated as a built-in processor in the ASIC. The ASIC that integrates the processor can be packaged separately or packaged together with other circuits. In addition to including cores for executing software instructions to perform operations or processing, the processor can further include necessary hardware accelerators, such as field programmable gate arrays (FPGA), PLDs (programmable logic devices), or logic circuits that implement special logic operations.

[0085] The memory in the embodiment of the present application can include at least one of the following types: read-only memory (ROM) or other types of static storage devices that can store static information and instructions, random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, and electrically erasable programmable read-only memory (EEPROM). In some scenarios, the memory can also be a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage medium or other magnetic storage device, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited to this.

[0086] The embodiment of the present application further provides a computer readable storage medium, including instructions, which, when executed on a computer, cause the computer to perform any of the above methods.

[0087] The embodiment of the present application further provides a computer program product including instructions, which, when executed on a computer, cause the computer to perform any of the above methods.

[0088] The embodiment of the present application further provides a chip, including a processor and an interface circuit, the interface circuit being coupled with the processor, the processor being configured to execute computer programs or instructions to implement the above method, and the interface circuit being configured to communicate with other modules outside the chip.

[0089] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable apparatus. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (for example, coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (for example, infrared, wireless, microwave, etc.) manner. The computer readable storage medium can be any available medium that can be accessed by a computer or data storage device including one or more servers, data centers, etc. integrated with the medium. The available medium can be a magnetic medium (for example, floppy disk, hard disk, magnetic tape), an optical medium (for example, DVD), or a semiconductor medium (for example, solid state disk (solid state disk, SSD)) and the like.

[0090] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0091] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if such modifications and modifications of this application fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A method for calibrating the internal imaging height of a terahertz near-field system, characterized in that, The method comprises the following steps: obtaining a surface image and an internal image of terahertz near-field imaging; dividing an internal material region into a uniform region and a non-uniform region based on a comparison of image features of the surface image and the internal image; calculating a first coefficient of the uniform region, and converting a voltage value of the internal image of the uniform region into a first height based on the first coefficient; calculating a second coefficient of the non-uniform region in segments, and converting a voltage value of the internal image of the non-uniform region into a second height based on the second coefficient corresponding to each segment; calculating a height compensation based on the surface image and the internal image of the substrate, superimposing the first height and the height compensation to obtain an internal height calibration value of the uniform region, and superimposing the second height and the height compensation to obtain an internal height calibration value of the non-uniform region.

2. The method of claim 1, wherein, The step of dividing the internal material region into a uniform region and a non-uniform region based on a comparison of image features of the surface image and the internal image comprises the following steps: determining whether the depth features of the surface image are consistent, and whether the voltage size features of the internal image of the same pixel region of the surface image are consistent; if there is no pixel point with color depth change in the same pixel region, the same pixel region is determined as a uniform region; if there is at least one pixel with color depth change inconsistent with the surrounding pixels in the same pixel region, the same pixel region is determined as a non-uniform region.

3. The method of claim 1, wherein, The step of calculating a first coefficient of the uniform region, and converting a voltage value of the internal image of the uniform region into a first height based on the first coefficient comprises the following steps: selecting feature points A and B at the same positions of the surface image and the internal image of the uniform region; obtaining a surface height value corresponding to the feature point A in the surface map obtaining a surface height value corresponding to the feature point B obtaining a voltage value corresponding to the feature point A in the internal map obtaining a voltage value corresponding to the feature point B ; calculating the first coefficient of the uniform region. Traverse all pixel points of the uniform area, and obtain a voltage value of each pixel point in the internal graph , and calculate a first height of the pixel point based on the first coefficient and the ​ 4. The method of claim 3, wherein, based on the first coefficient and the The first height of the pixel point satisfies the following formula: wherein is the first height, is the first coefficient, satisfying: .

5. The method of claim 1, wherein, The step of calculating a second coefficient of the non-uniform region in segments, and converting a voltage value of the internal image of the non-uniform region into a second height based on the second coefficient corresponding to each segment comprises the following steps: dividing the non-uniform region into n continuous sub-segments; selecting feature points C and D at the same positions of the surface image and the internal image of each sub-segment; obtaining a surface height value corresponding to the feature point C in the sub-section surface map obtaining a surface height value corresponding to the feature point D obtaining a voltage value corresponding to the feature point C in the sub-section internal map obtaining a voltage value corresponding to the feature point D ; calculating the second coefficient corresponding to each sub-segment. Traverse all pixel points of each sub-section, obtain voltage value of each pixel point in internal graph , based on the second coefficient of the sub-section and the corresponding Calculate the second height of the pixel point.

6. The method of claim 5, wherein, based on the second coefficient of the sub-segment and the corresponding The second height of the pixel point satisfies the following formula: wherein, is a second height of a pixel point in the i-th sub-section, i is a sub-section index, satisfying i = 1, 2, …, n, is a second coefficient corresponding to the i-th sub-section, satisfying: , is a surface height value corresponding to the feature point C in the i-th sub-section surface graph, is a surface height value corresponding to the feature point D in the i-th sub-section surface graph, is a voltage value corresponding to the feature point C in the i-th sub-section internal graph, is a voltage value corresponding to the feature point D in the i-th sub-section internal graph, is a voltage value of a pixel point in the i-th sub-section in the internal graph.

7. The method of claim 1, wherein, The step of calculating a height compensation based on the surface image and the internal image of the substrate comprises the following steps: obtaining a substrate surface height value of the substrate region in the surface image, and a substrate internal voltage value of the substrate region in the internal image corresponding to the position of the substrate surface height value; calculating a substrate preliminary height of the substrate region; determining the difference between the substrate surface height value and the substrate preliminary height as the height compensation.

8. The method of claim 7, wherein, The step of superimposing the first height and the height compensation to obtain an internal height calibration value of the uniform region, and superimposing the second height and the height compensation to obtain an internal height calibration value of the non-uniform region comprises the following steps: performing summation operation on the first height of each pixel point in the uniform region and the height compensation to obtain the internal height calibration value of the uniform region corresponding to the pixel point; for each sub-segment of the non-uniform region, performing summation operation on the second height of each pixel point in the sub-segment and the height compensation to obtain the internal height calibration value of the non-uniform region corresponding to the pixel point.

9. The method of claim 7, wherein, The substrate region is a sample-uncovered region.

10. An apparatus for calibrating height inside a terahertz near-field system, characterized in that, The device comprises a communication unit and a processing unit. The communication unit is configured to obtain a surface image and an internal image of terahertz near-field imaging. The processing unit is configured to divide the internal material region into a uniform area and a non-uniform area based on a comparison of image features of the surface image and the internal image; calculate a first coefficient of the uniform area, and convert a voltage value of the internal image of the uniform area into a first height based on the first coefficient; calculate a second coefficient of the non-uniform area in segments, and convert a voltage value of the internal image of the non-uniform area into a second height based on the second coefficient corresponding to each segment; calculate a height compensation based on the surface image and the internal image of the substrate; superimpose the first height and the height compensation to obtain an internal height calibration value of the uniform area; and superimpose the second height and the height compensation to obtain an internal height calibration value of the non-uniform area.

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