Measuring instrument and measuring method for thickness of wafer metal film

Abstract

The present disclosure provides a measuring instrument and a measuring method for the thickness of a metal film on a wafer, wherein the measuring method is used for a measuring instrument for the thickness of a metal film on a wafer. The measuring instrument includes: a carrier plate for carrying a wafer, wherein the upper surface of the wafer is covered with a metal film; an eddy current sensor, disposed above the carrier plate, configured to utilize the eddy current effect to excite an eddy current magnetic field in the metal film of the wafer, and detect the intensity of the eddy current magnetic field to generate a corresponding output signal; and a ranging sensor, disposed above the carrier plate, for measuring the lift-off height of the eddy current sensor from the wafer. The measuring method includes: when the carrier plate carries the wafer to be detected, respectively obtaining a target output signal generated by the eddy current sensor and a target lift-off height measured by the ranging sensor; and determining the thickness of the metal film of the wafer to be detected according to the target output signal and the target lift-off height.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and more specifically to a measuring instrument and a measuring method for the thickness of a wafer metal film, an electronic device, a computer-readable storage medium, and a computer program product. Background Art

[0002] Integrated Circuit (IC) is the core and lifeblood of the development of the information technology industry. Integrated circuits are generally formed by depositing a conductive layer, a semiconductor layer or an insulating layer on a silicon wafer. As a result, a thin film formed by a filler layer is deposited on the surface of the wafer. In the manufacturing process, it is necessary to continuously flatten the filler layer until the patterned top surface is exposed to form a conductive path between the raised patterns.

[0003] With the rapid development of semiconductor materials and semiconductor production processes, there are more and more research programs on the characteristics of metal film thickness on the wafer surface. At present, not only reliable semiconductor substrate materials and semiconductor process preparation capabilities are needed, but also stable and reliable testing tools are needed to accurately judge the morphology of metal films on the wafer surface. However, there is currently no relevant measurement equipment on the market that can accurately measure the thickness of metal films on the wafer surface.

[0004] The methods described in this section are not necessarily methods that have been previously conceived or employed. Unless otherwise indicated, it should not be assumed that any method described in this section is considered to be prior art simply because it is included in this section. Similarly, unless otherwise indicated, the issues mentioned in this section should not be considered to have been recognized in any prior art. Summary of the invention

[0005] According to a first aspect of an embodiment of the present disclosure, a method for measuring the thickness of a metal film on a wafer is provided, wherein the measuring method is used for a measuring instrument for the thickness of a metal film on a wafer, the measuring instrument comprising: a carrying plate for carrying a wafer, wherein the upper surface of the wafer is covered with a metal film; an eddy current sensor, disposed above the carrying plate and configured to utilize an eddy current effect to excite an eddy current magnetic field in the metal film of the wafer, and detect the strength of the eddy current magnetic field to generate a corresponding output signal; and a ranging sensor, disposed above the carrying plate and used to measure the lift-off height of the eddy current sensor from the wafer, the measuring method comprising: when the carrying plate carries a wafer to be inspected, respectively obtaining a target output signal generated by the eddy current sensor and a target lift-off height measured by the ranging sensor; and determining the thickness of the metal film of the wafer to be inspected according to the target output signal and the target lift-off height.

[0006] According to a second aspect of an embodiment of the present disclosure, there is provided an instrument for measuring the thickness of a metal film on a wafer, comprising: a carrying plate for carrying a wafer, wherein the upper surface of the wafer is covered with a metal film; an eddy current sensor, disposed above the carrying plate and configured to utilize the eddy current effect to excite an eddy current magnetic field in the metal film of the wafer, and detect the strength of the eddy current magnetic field to generate a corresponding output signal; a ranging sensor, disposed above the carrying plate and configured to measure the lift-off height of the eddy current sensor from the wafer; and a processor, communicatively connected to the eddy current sensor and the ranging sensor, configured to respectively obtain a target output signal generated by the eddy current sensor and a target lift-off height measured by the ranging sensor when the carrying plate carries the wafer to be inspected; and determine the thickness of the metal film of the wafer to be inspected according to the target output signal and the target lift-off height.

[0007] According to a third aspect of an embodiment of the present disclosure, there is provided an electronic device, comprising: at least one processor; and at least one memory on which a computer program is stored, wherein when the computer program is executed by the at least one processor, the at least one processor executes the above-mentioned method for measuring the thickness of a metal film on a wafer.

[0008] According to a fourth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the processor executes the above-mentioned method for measuring the thickness of a metal film on a wafer.

[0009] According to a fourth aspect of an embodiment of the present disclosure, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the processor executes the above-mentioned measurement method.

[0010] According to one or more embodiments of the present disclosure, when measuring the thickness of a metal film on a wafer, the output signal size of the eddy current sensor and the influence of the lift-off height on the measurement result are comprehensively considered. Therefore, the thickness value of the metal film obtained using the measurement method of the present disclosure is more accurate than the thickness value determined only by using the output signal of the eddy current sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings exemplarily illustrate the embodiments and constitute a part of the specification, and together with the text description of the specification, are used to illustrate the exemplary implementation of the embodiments. The embodiments shown are for illustrative purposes only and do not limit the scope of the claims. In all drawings, the same reference numerals refer to the same elements or similar but not necessarily the same elements.

[0012] Figure 1 is a schematic structural diagram showing an instrument for measuring the thickness of a metal film on a wafer according to an embodiment of the present disclosure;

[0013] Figure 2 is a flow chart showing a method for measuring the thickness of a wafer metal film according to an embodiment of the present disclosure;

[0014] Figure 3 is a flow chart showing a method for measuring the thickness of a wafer metal film according to an embodiment of the present disclosure;

[0015] Figure 4 is a flowchart illustrating a method for determining a first mapping relationship according to an embodiment of the present disclosure;

[0016] Figure 5 is a flowchart illustrating a method for determining a second mapping relationship according to an embodiment of the present disclosure;

[0017] Figure 6 A curve relationship diagram of a lift-off height and a corresponding output signal obtained for a sample wafer according to an embodiment of the present disclosure is shown;

[0018] Figure 7 is a flowchart illustrating a method for obtaining a target output signal and a target lift-off height according to an embodiment of the present disclosure; and

[0019] Figure 8 is a schematic diagram showing a preset path according to an embodiment of the present disclosure;

[0020] Fig. 9 is a longitudinal cross-sectional schematic diagram showing a measuring instrument according to an embodiment of the present disclosure;

[0021] Fig.10 A schematic diagram showing a 2D graphical display of the thickness of a metal film of a wafer to be inspected is shown;

[0022] Fig.11 A schematic diagram showing a 3D graphical display of the thickness of a metal film of a wafer to be inspected is shown;

[0023] Fig.12 An example configuration of an electronic device is shown that may be used to implement the methods described herein. DETAILED DESCRIPTION

[0024] The present disclosure is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. In addition, it should be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0025] It should be noted that, in the absence of conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other. Unless the context clearly indicates otherwise, if the number of elements is not specifically limited, the element can be one or more. In addition, the numbering of the steps or functional modules used in the present disclosure is only used to identify each step or functional module, and is not used to limit the execution order of each step or the connection relationship between each functional module.

[0026] In the present disclosure, unless otherwise specified, the use of the terms "first", "second", etc. to describe various elements is not intended to limit the positional relationship, temporal relationship, or importance relationship of these elements, and such terms are only used to distinguish one element from another element. In some examples, the first element and the second element may refer to the same instance of the element, and in some cases, based on the description of the context, they may also refer to different instances.

[0027] In this disclosure, the terms used in the description of various examples are only for the purpose of describing specific examples and are not intended to be limiting. Unless the context clearly indicates otherwise, if the number of elements is not specifically limited, the element can be one or more. In addition, the term "and / or" used in this disclosure covers any one of the listed items and all possible combinations.

[0028] The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0029] According to an embodiment of the present disclosure, a method for measuring the thickness of a wafer metal film is first proposed, and the method is used for a wafer metal film thickness measuring instrument of the present disclosure. In order to introduce the measuring method of the embodiment of the present disclosure in more detail, the measuring instrument for the wafer metal film thickness is first described here.

[0030] Figure 1 FIG. 1 is a schematic diagram showing a structure of a measuring instrument 100 for measuring the thickness of a metal film on a wafer according to an embodiment of the present disclosure. Figure 1As shown, the measuring instrument 100 includes: a carrier plate 30, an eddy current sensor 20 and a distance sensor 50. The carrier plate 30 is used to carry a wafer, wherein the upper surface of the wafer is covered with a metal film. The carrier plate 30 may have an adsorption function, which can adsorb the wafer it carries so that the wafer remains stationary relative to the carrier plate 30. The above-mentioned adsorption function can be achieved, for example, by a vacuum adsorption device. The eddy current sensor 20 is arranged above the carrier plate 30, and is configured to utilize the eddy current effect to excite an eddy current magnetic field in the metal film of the wafer, and detect the intensity of the eddy current magnetic field to generate a corresponding output signal. As an example, the eddy current sensor 20 may include an excitation coil, an induction coil, a coil skeleton and a shielding shell. The excitation coil is fed with an AC signal of a fixed frequency to generate an alternating magnetic field, thereby generating an induced electromotive force in the metal film and the induction coil, and a coupled electromagnetic induction relationship exists between the excitation coil, the induction coil and the metal film. As the core part of the measuring instrument 100, the eddy current sensor 20 is mainly used to excite the alternating electromagnetic field in the metal film and sense the changes in the induced electromotive force caused by the mutual inductance effect caused by the metal films of different thicknesses. Under the condition that other conditions remain unchanged, there is a one-to-one correspondence between the induced electromotive force and the thickness of the metal film. Therefore, the output signal of the eddy current sensor 20 is related to the thickness of the metal film. The ranging sensor 50 is arranged above the carrier plate 30 to measure the lift-off height of the eddy current sensor 20 from the wafer. The ranging sensor 50 includes but is not limited to millimeter wave sensors, laser ranging sensors, infrared ranging sensors, etc. During the measurement process, the sampling frequency of the ranging sensor 50 is, for example, consistent with the sampling frequency of the eddy current sensor 20, so as to output the lift-off height of the eddy current sensor 20 from the wafer in real time.

[0031] Continue to refer to Figure 1 In some embodiments, the measuring instrument 100 further includes a distance adjustment device 11, on which the eddy current sensor 20 and the distance sensor 50 are fixed, and the distance adjustment device 11 is configured to adjust the lift-off height from the wafer surface. Exemplarily, the distance adjustment device 11 may include a stepper motor, the output end of which is fixedly connected to the eddy current sensor 20 and the distance sensor 50 to drive the two to move. Figure 1 In some other embodiments, the distance adjustment device 11 may also include other driving mechanisms besides the stepping motor, as long as the distance adjustment device 11 can drive the eddy current sensor 20 and the distance measuring sensor 50 to move in the vertical direction, and the present disclosure does not limit the specific structure of the distance adjustment device 11.

[0032] Figure 2 A flow chart of a method 200 for measuring the thickness of a metal film on a wafer according to an embodiment of the present disclosure is shown.

[0033] like Figure 2 As shown, the measurement method 200 includes:

[0034] Step 210, when the carrier plate 30 carries the wafer to be inspected, respectively obtaining the target output signal generated by the eddy current sensor 20 and the target lift-off height measured by the distance sensor 50; and

[0035] Step 220 , determining the thickness of the metal film of the wafer to be inspected according to the target output signal and the target lift-off height.

[0036] In step 210, the tester may place the wafer to be tested on the carrier plate 30, and adjust the positions of the eddy current sensor 20 and the distance sensor 50 in the space above the carrier plate 30 so that they reach the preset measurement points. Then, the readings of the eddy current sensor 20 and the distance sensor 50 are obtained, that is, the target output signal and the target lift-off height.

[0037] As mentioned above, when other conditions remain unchanged, there is a one-to-one correspondence between the output signal of the eddy current sensor 20 and the thickness of the metal film. In addition, the lift-off height will also affect the resolution of the eddy current sensor 20, so the output signal of the eddy current sensor 20 is also related to the lift-off height. Therefore, in step 220, the thickness of the metal film of the wafer to be detected can be determined based on the target output signal and the target lift-off height. In some embodiments, the functional relationship between the thickness of the metal film and the output signal of the eddy current sensor 20 and the lift-off height can be predetermined, and then the target output signal and the target lift-off height are substituted into the above functional relationship to obtain the thickness of the metal film.

[0038] According to the measurement method 200 of one or more embodiments of the present disclosure, when measuring the thickness of the metal film of the wafer, the output signal size of the eddy current sensor 20 and the influence of the lift-off height on the measurement result are comprehensively considered. Therefore, the thickness value of the metal film obtained by the measurement method of the present disclosure is more accurate than the thickness value determined only by using the output signal of the eddy current sensor 20.

[0039] Figure 3 A flow chart of a method 300 for measuring the thickness of a metal film on a wafer according to an embodiment of the present disclosure is shown.

[0040] like Figure 3 As shown, the measurement method 300 includes:

[0041] Step 310, determining a first mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor 20 when the lift-off height measured by the distance measuring sensor 50 is a preset standard height, wherein the coefficient in the first mapping relationship is related to the resolution of the eddy current sensor 20;

[0042] Step 320, determining a second mapping relationship between the lift-off height and the resolution of the eddy current sensor 20;

[0043] Step 330, modifying the coefficients in the first mapping relationship according to the second mapping relationship to obtain a third mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor 20 when the lift-off height measured by the ranging sensor 50 is the target lift-off height; and

[0044] Step 340 : Determine the thickness of the metal film of the wafer to be inspected according to the target output signal based on the third mapping relationship.

[0045] In step 310, the preset standard height may be the lift-off height at which the eddy current sensor 20 has the best detection effect, and the size of the above standard height is related to the specific model and parameters of the measuring instrument 100. In some embodiments, the first mapping relationship may be predetermined and stored in a related memory of the measuring instrument 100, and the first mapping relationship may be retrieved from the memory when calculating the thickness. In other embodiments, the first mapping relationship may also be determined before measuring the thickness of the metal film of the wafer to be detected. For example, the above first mapping relationship may be fitted by obtaining the output signal of the eddy current sensor 20 corresponding to a plurality of metal film samples of different thicknesses and known thicknesses. The first mapping relationship may be expressed as:

[0046] T=f(x) (1)

[0047] Wherein, T represents the thickness of the metal film, and x is the output signal of the eddy current sensor 20. In some embodiments, f(x) can be a cubic function, that is,

[0048] T=Ax 3 +Bx 2 +Cx+D (2)

[0049] Among them, A, B, and C are coefficients in the first mapping relationship, and these coefficients are directly related to the resolution of the eddy current sensor 20. Those skilled in the art can understand that the resolution of the eddy current sensor 20 is defined as the rate of change of the measured value (i.e., the output signal size of the eddy current sensor 20) as the thickness of the metal film changes. Whenever the thickness of the metal film changes by unit thickness, if the output signal of the eddy current sensor 20 changes more, it means that its resolution is greater; conversely, the resolution is smaller. Therefore, according to the above definition, the coefficients A, B, and C in formula (2) are related to the resolution of the eddy current sensor 20.

[0050] As mentioned above, the lift-off height will affect the resolution of the eddy current sensor 20. Therefore, there is a second mapping relationship between the lift-off height and the resolution of the eddy current sensor 20. Generally speaking, the higher the lift-off height, the smaller the resolution of the eddy current sensor 20. In step 320, similar to the first mapping relationship, the second mapping relationship can be predetermined and stored in the relevant memory of the measuring instrument 100. When calculating the thickness, the second mapping relationship can be retrieved from the memory. In some other embodiments, the second mapping relationship can also be determined before measuring the thickness of the metal film of the wafer to be inspected. For example, the second mapping relationship can be determined by obtaining the output signal of the eddy current sensor 20 corresponding to the metal film of different thicknesses and known thickness at different lift-off heights. The second mapping relationship can be expressed as:

[0051] K=g(h) (3)

[0052] Wherein, K represents the resolution of the eddy current sensor 20, and h represents the lift-off height. In addition, each coefficient A, B, and C in formula (2) is related to K.

[0053] In step 330, the coefficients A, B, and C in equation (2) are corrected according to equation (3). Specifically, h=h1 (where h1 represents the target lift-off height) can be substituted into equation (3) to calculate the target resolution K1 of the eddy current sensor 20 at the target lift-off height. Subsequently, the target resolution K1 is used to correct the coefficients A, B, and C in equation (2) to obtain the corrected coefficients A1, B1, and C1, and finally the third mapping relationship between the thickness of the metal film and the output signal of the eddy current sensor 20 at the target lift-off height is obtained. The third mapping relationship can be expressed as:

[0054] T=A1x 3 +B1x 2 +C1x+D (4)

[0055] In step 340, the value of the target output signal obtained in the previous step is substituted into equation (4), and the thickness of the metal film of the wafer can be calculated.

[0056] It should be noted that, although in the present embodiment, f(x) is shown as a cubic function, it is understandable that f(x) may also be in other function forms such as a linear function, a quadratic function, etc. Similarly, g(h) may also be in a variety of function forms such as a linear function or a quadratic function, and the embodiments of the present disclosure do not limit the specific function form of f(x) or g(h). In addition, when f(x) is in other function forms, the number of coefficients to be corrected included therein may also be different. For example, in some examples, the coefficients to be corrected may be 1 or 2, and in other examples, the coefficients to be corrected may be 3 or more.

[0057] Figure 4 FIG. 4 is a flow chart showing a method 400 for determining a first mapping relationship according to an embodiment of the present disclosure. Figure 4 As shown, the method 400 includes:

[0058] Step 410, after the eddy current sensor 20 is adjusted to a position of a standard height, the eddy current sensor 20 is used to detect a plurality of sample wafers in the sample wafer set respectively, so as to obtain an output signal of the eddy current sensor 20 corresponding to each sample wafer in the plurality of sample wafers, wherein the upper surface of each sample wafer included in the sample wafer set is covered with a metal film of different and known thickness; and

[0059] Step 420 : fitting a first mapping relationship according to the thickness of each sample wafer among the multiple sample wafers and the output signal of the eddy current sensor 20 corresponding to the sample wafer.

[0060] In the method of this embodiment, a sample wafer set prepared in advance can be used to determine the first mapping relationship. The sample wafer set includes multiple sample wafers, for example, 5, 6, 8 or 10 sample wafers. These sample wafers can have wafer bodies of the same size, but the metal films covered on the upper surfaces of the wafers are different, and the metal films of these wafers have different thickness values. Specifically, these sample wafers can have metal films with successively increasing thicknesses.

[0061] Before executing the method of this embodiment, the distance adjustment device 11 of the measuring instrument 100 is used to adjust the lift-off height to the standard height, and the above adjustment can be completed by observing the reading of the distance sensor 50. In step 410, multiple sample wafers in the sample wafer set can be placed on the carrier plate 30 in sequence, and then the output signal of the eddy current sensor 20 is obtained when each sample wafer is placed on the carrier plate 30. Finally, a series of metal film thickness and corresponding output signal data are obtained.

[0062] Table 1 shows relevant data of a plurality of sample wafers included in a set of sample wafers according to an embodiment of the present disclosure.

[0063] Sample wafer number Thickness / nm Output signal 1 72.6 145.6 2 146 335.5 3 208.5 475.8 4 303.1 598.4 5 382 711.8 6 559.5 818.1

[0064] Table 1

[0065] In step 420, the relationship between the output signal of the eddy current sensor 20 and the thickness of the metal film of the sample wafer is established, and the first mapping relationship can be determined by fitting. The fitting method includes but is not limited to piecewise linear fitting, least squares fitting and other methods.

[0066] The method of this embodiment can use a sample wafer set to determine the first mapping relationship on site. Compared with determining the first mapping relationship in advance and storing it in a memory, the first mapping relationship calculated using the method of this embodiment will be more accurate. This is because different measuring instruments 100 may have individual differences. Using the first mapping relationship determined in advance cannot accurately reflect the relevant working parameters of the measuring instrument 100 that should be actually operated, while the first mapping relationship determined on site can accurately reflect the above-mentioned relevant working parameters, so that the thickness of the metal film calculated later is more accurate.

[0067] Figure 5 FIG. 5 is a flow chart of a method 500 for determining a second mapping relationship according to an embodiment of the present disclosure. Figure 5 As shown, the method 500 includes:

[0068] Step 510, sequentially adjusting the eddy current sensor 20 to the position of each sample height among a plurality of sample heights;

[0069] Step 520, at each sample height, determines the resolution corresponding to the eddy current sensor 20, wherein step 520 further includes:

[0070] Step 521, using the eddy current sensor 20 to detect each sample wafer in the sample wafer set, so as to obtain an output signal of the eddy current sensor 20 corresponding to each sample wafer at the position of the sample height; and

[0071] Step 522, determining the resolution of the eddy current sensor 20 at the sample height according to the thickness of each sample wafer in the sample wafer set and the output signal of the eddy current sensor 20 corresponding to each sample wafer at the sample height; and

[0072] Step 530 : determining a second mapping relationship according to the multiple sample heights and the resolution of the eddy current sensor 20 corresponding to each of the multiple sample heights.

[0073] The plurality of sample heights may be pre-determined lift-off heights, and the sample heights may be in the form of an arithmetic progression, for example, that is, two adjacent sample heights have the same height difference. In step 510, the lift-off height may be adjusted to a certain sample height position using the distance adjustment device 11 of the measuring instrument 100, and the adjustment may be completed by observing the reading of the distance sensor 50.

[0074] In step 521, at any sample height, multiple sample wafers in the sample wafer set are sequentially placed on the carrier plate 30, and then when each sample wafer is placed on the carrier plate 30, the output signal of the eddy current sensor 20 is obtained. Finally, a series of metal film thickness and corresponding output signal data are obtained.

[0075] Finally, a series of data on the thickness of the metal film and the corresponding output signal are obtained. The output signal data corresponding to each sample wafer is similar to the data shown in Table 1. However, due to different lift-off heights, the output signals corresponding to each sample wafer are not the same as the output signals shown in Table 1.

[0076] In step 522 , the resolution of the eddy current sensor 20 at the position of the sample height can be directly calculated using the data obtained in step 521 .

[0077] To simplify the description, it is assumed that the first mapping relationship T=f(x) is in the form of a linear function, that is, T=Cx, then the resolution of the eddy current sensor 20 (or the coefficient in the first mapping relationship) can be directly calculated using the data of two sample wafers with different metal film thicknesses. Specifically, the thickness difference of the metal film thickness of the two sample wafers and the signal difference of the output signals corresponding to the two sample wafers can be calculated respectively, and then the thickness difference is divided by the signal difference to obtain the resolution of the eddy current sensor 20 at the sample height. It can be understood that in some embodiments, the first mapping relationship T=f(x) can be in the form of a more complex function. In this case, more sample wafer data may be required to calculate the resolution of the eddy current sensor 20. The specific calculation method is determined according to the function form of f(x), which will not be described in detail here.

[0078] After the resolution of the eddy current sensor 20 at each sample height is determined in step 520 , the functional relationship between the resolution of the eddy current sensor 20 and the lift-off height, ie, the second mapping relationship, can be determined in step 530 by fitting or the like.

[0079] In some other embodiments, the second mapping relationship may be determined by using a curve relationship diagram of different lift-off heights and corresponding sensor output signals. Figure 6FIG. 4 shows a curve relationship diagram of the lift-off height and the corresponding sensor output signal obtained for a sample wafer according to an embodiment of the present disclosure, in FIG. Figure 6 The relationship between the output signal y and the lift-off height x can be expressed as a quadratic curve y = -1.197088x 2 +4.250079x+0.163580. Using the method described above, for a certain sample wafer, multiple sets of data of the output signals corresponding to the sample wafer at different sample heights can be obtained, and these data can be used to further fit the following: Figure 6 Finally, based on multiple different sample wafers, multiple Figure 6 The relationship between the resolution and the lift-off height, ie, the second mapping relationship mentioned above, can be determined based on these curves.

[0080] The following provides an implementation method for determining the first mapping relationship and the second mapping relationship and performing actual metal film thickness measurement.

[0081] The first mapping relationship of the eddy current sensor 20 is established, and the first mapping relationship is fitted. The fitting method can adopt the piecewise linear fitting, least squares fitting, etc. mentioned above. The above first mapping relationship can be expressed by a polynomial equation as follows:

[0082] T=A0+A1x 1 +A2x 2 +···+A n x n (5)

[0083] The above formula can be expressed as T = f(x), where T is the thickness of the measured sample, x is the output signal value of the eddy current sensor 20, A0...A n is a coefficient related to the resolution of the eddy current sensor 20 .

[0084] By different lift-off heights H0, H1…H n By calibrating the same group of sample wafers with different thicknesses, a relationship model between the output of the eddy current sensor 20 and the lift-off height H and the sample thickness T can be obtained. The relationship model can be expressed as a matrix, that is,

[0085]

[0086] T0, T1…T n They represent the eddy current sensor 20 at different lift-off heights H0, H1...H n Under the above conditions, for the output value of the sensor of the same sample wafer, the calculated thickness obtained by calculation should be as close as possible to the actual thickness T of the sample. The above formula (6) actually includes the second mapping relationship between the lift-off height and the resolution of the eddy current sensor 20.

[0087] Assume that the lift-off height H is taken as the reference and a set of lift-off heights is set with a step size of λ. For example, each lift-off height is set at H-nλ,…,H-λ,H,H+λ,…,H+nλ, marked as H -n 、H0…H n The same set of samples with different thicknesses are used for calibration to obtain the relationship model between the output of the eddy current sensor 20 and the lift-off height H and the sample thickness T. The coefficients A in the above formula (6) are obtained: 00 …A nn Afterwards, the actual metal film thickness can be measured.

[0088] When the measurement starts, the distance measuring sensor 50 provides real-time feedback of the actual lift-off height h at each point, and the processor of the measuring instrument 100 determines h at In the range of y =H+yλ, and the characteristic curve at this time is determined according to the above formula (6): T com =A y0 +A y1 x 1 +A y2 x 2 +···+A yn x n The eddy current sensor 20 calculates the thickness of the measured sample based on this characteristic curve.

[0089] Back to Figure 1 The measuring instrument 100 further includes a driving assembly configured to drive the eddy current sensor 20 and the distance sensor 50 to move relative to the carrier plate 30. The driving assembly may include: a swing arm 10 and a rotating device 40. The eddy current sensor 20 and the distance sensor 50 are fixed to the swing arm 10, and the swing arm 10 is configured to drive the eddy current sensor 20 and the distance sensor 50 to move in a direction parallel to the diameter direction of the carrier plate 30, that is, along Figure 1 The rotating device 40 is connected to the carrier plate 30 and is configured to drive the carrier plate 30 to rotate. Figure 1 As shown, the rotating device 40 drives the carrier plate 30 to rotate in the direction indicated by the arrow. Both the swing arm 10 and the rotating device 40 can be realized by a motor (for example, a stepping motor and a rotary motor). By combining the translational movement of the swing arm 10 and the distance adjustment device 11 and the rotation of the rotating device 40, the eddy current sensor 20 and the distance measuring sensor 50 can be set to any position in the space above the carrier plate 30.

[0090] Figure 7 FIG. 7 is a flow chart of a method 700 for obtaining a target output signal and a target lift-off height according to an embodiment of the present disclosure. Figure 7As shown, the method 700 includes:

[0091] Step 710, using a driving device to move the eddy current sensor 20 and the distance sensor 50 along a preset path to a plurality of positions to be tested relative to the wafer to be tested; and

[0092] Step 720, at each of the multiple test positions, respectively obtain the target output signal generated by the eddy current sensor 20 and the target lift-off height measured by the ranging sensor 50 to determine the thickness of the metal film of the wafer to be inspected at each of the multiple test positions.

[0093] Since the thickness of the metal film of the wafer is not uniform, or in other words, the metal film may have different thicknesses at different positions, therefore, when measuring the thickness, first determine the position of the wafer where the thickness needs to be measured. In some embodiments, in order to detect the overall morphology of the metal film of the wafer, the thickness of the metal film at multiple different positions can be measured in sequence, and then the overall thickness of the metal film can be derived or simulated using relevant calculation software. In step 710, the eddy current sensor 20 and the ranging sensor 50 can be moved to multiple positions to be tested relative to the wafer to be detected according to a preset path. In step 720, at each position to be tested, the target output signal generated by the eddy current sensor 20 and the target lift-off height measured by the ranging sensor 50 are respectively obtained, thereby obtaining a set of relevant data for multiple positions to be tested. Subsequently, the thickness of the metal film at the position to be tested can be calculated based on the relevant data of each position to be tested.

[0094] In some embodiments, the preset path includes: a straight path on a horizontal plane that coincides with the diameter of the wafer to be inspected; and / or a circular path on a horizontal plane with the center of the wafer to be inspected as the center of the circle. Figure 8 A schematic diagram of a preset path according to an embodiment of the present disclosure is shown. Figure 8 The solid line in the figure represents the edge of the wafer, and the dashed line represents a possible preset path. Figure 8Two preset paths are shown, wherein path a coincides with the diameter of the wafer to be detected. When the preset path selects path a, the rotating device 40 can remain stationary, and only the swing arm 10 drives the eddy current sensor 20 and the distance sensor 50 to move above the carrier plate 30 along the diameter direction of the carrier plate 30. In this case, the measuring instrument 100 can measure the relevant data of multiple positions to be measured on the wafer diameter. Path b coincides with a concentric circle of the wafer to be detected. When the preset path selects path b, the swing arm 10 can remain stationary, and only the rotating device 40 drives the carrier plate 30 to rotate. In this case, the measuring instrument 100 can measure the relevant data of multiple positions to be measured on the concentric circles of the wafer. In some other embodiments, the preset path can also be other more complex motion paths, and the positions to be measured are multiple points on the motion path. It can be understood that no matter what shape the preset path is, the eddy current sensor 20 and the distance sensor 50 can be controlled by controlling the drive component to realize the movement of the path.

[0095] In some embodiments, the measuring instrument 100 further includes an on-position sensor 60. The on-position sensor 60 is configured to detect the position of a notch of the wafer to be inspected when the rotating device 40 drives the carrier plate 30 to rotate. Fig. 9 FIG. 1 is a schematic longitudinal cross-sectional view of a measuring instrument 100 according to an embodiment of the present disclosure. The position of the in-situ sensor 60 is set to be aligned with the notch of the wafer in the radial direction of the wafer so as to be able to detect the notch of the wafer. Fig. 9 As shown, the in-position sensor 60 can be a beam-type in-position sensor 60, which has a transmitting end and a receiving end. The transmitting end emits red light or infrared light, and the receiving end is used to receive the light emitted by the transmitting end. When the wafer is between the transmitting end and the receiving end, the light transmission is cut off, and the receiving end cannot receive the light signal; when the notch of the wafer passes between the two, the receiving end can receive the light signal, and the in-position sensor 60 outputs a detection signal. Therefore, when the wafer rotates until its notch reaches the position of the in-position sensor 60, the trigger switch of the in-position sensor 60 is triggered. The relevant processor of the measuring instrument 100 is configured to: determine the current rotation position of the wafer to be detected according to the detection result of the in-position sensor for the notch, so as to set the driving component to drive the eddy current sensor 20 and the distance sensor 50 to move according to the preset path. Exemplarily, during the rotation of the wafer, the relevant processor can record the rotation angle of the carrier plate 30 within a certain period of time, so that the current rotation position of the wafer can be determined according to the moment when the in-position sensor detects the notch and the rotation angle of the carrier plate 30 after that moment. The subsequent reference wafer rotation position at each moment, combined with the rotation of the carrier plate 30 and the radial movement of the swing arm 10, can make the eddy current sensor 20 and the wafer move relative to each other along the above-mentioned preset path.

[0096] In some embodiments, an edge compensation algorithm is used to correct the data for edge measurement of the metal film of the wafer. Eddy current measurement generates an eddy current magnetic field, which exists in an area of ​​a certain area on the surface of the metal film. Therefore, the thickness value finally measured is essentially the average thickness of a certain area on the surface of the metal film that produces the eddy current effect. In addition, in the process of the sensor magnetic field being projected completely into the wafer, part of the magnetic field is projected outside the wafer, so there is a certain magnetic field attenuation, resulting in a deviation in the measurement of the edge position of the wafer. On the other hand, according to the measured data, there is a certain shrinkage phenomenon when comparing the eddy current measurement data with the actual wafer metal film thickness model. An edge attenuation model is established based on the measured data, and the measured film thickness information is corrected to a certain extent within the threshold distance range from the edge. The above threshold distance range can be, for example, 5mm, 10mm, 15mm, etc.

[0097] The above correction includes: correcting the coordinates of the position to be measured; and / or correcting the thickness measurement value corresponding to the position to be measured. For example, the coordinate information of the position to be measured corresponding to the measured thickness can be pre-corrected, and (r, θ, T) can be corrected to (r+Δr, θ, T), where r, θ are the coordinates of the position to be measured in the polar coordinate system, and T is the measured thickness; or the measured value obtained by the position to be measured can be compensated and corrected, and (r, θ, T) can be corrected to (r, θ, T+ΔT).

[0098] Fig.10 A schematic diagram of 2D graphical display of the thickness of the metal film of the wafer to be inspected is shown, wherein: Fig.10 The horizontal axis represents the radial coordinate r of the position to be measured, and the vertical axis represents the thickness measurement value of the position to be measured. In some embodiments, the above-mentioned correction of the coordinates of the position to be measured includes: for each position to be measured: keeping the thickness measurement value corresponding to the position to be measured unchanged, and increasing the coordinate value of the position to be measured, wherein the increase in the coordinate value of the position to be measured close to the edge of the wafer to be detected is greater than the increase in the coordinate value of the position to be measured far from the edge of the wafer to be detected. Specifically, Fig.10 As shown, curve 1 represents the thickness measurement value of the metal film obtained by contact measurement such as four-probe measurement. Due to the contact measurement, curve 1 is close to the true value of the thickness of the metal film; curve 2 represents the thickness measurement value measured by the method of the present disclosure but without edge compensation; curve 3 represents the thickness measurement value measured by the method of the present disclosure and edge compensation. In this embodiment, the radial coordinates of each position to be measured are compensated, that is, the data (r, θ, T) of each position to be measured is corrected to (r+Δr, θ, T). This compensation can be understood as the curve 2 in Fig.10 The curve 3 is obtained by stretching in the direction of the horizontal axis.

[0099] In some other embodiments, the correction of the thickness measurement value corresponding to the position to be measured includes: for each position to be measured: keeping the coordinates of the position to be measured unchanged, increasing the thickness measurement value corresponding to the position to be measured, wherein the increase in the thickness measurement value of the position to be measured close to the edge of the wafer to be detected is greater than the increase in the thickness measurement value of the position to be measured far from the edge of the wafer to be detected. Fig.10 As shown, in these embodiments, the radial coordinates of each position to be measured are compensated, that is, the data (r, θ, T) of each position to be measured is corrected to (r, θ, T+ΔT). This compensation can be understood as the edge portion of the curve 2 being corrected to the radial coordinates of each position to be measured. Fig.10 The material is pulled in the direction of the vertical coordinate to obtain curve 3.

[0100] Although two different correction methods are described in the above embodiments, in some other embodiments, the two correction methods can be used simultaneously, that is, coordinate correction and thickness measurement value correction are performed simultaneously. Fig.10 As shown, the corrected curve 3 is closer to the true curve (ie, curve 1 ) than the uncorrected curve 2 .

[0101] After measuring the thickness of the metal film at multiple test positions, the thickness of the metal film at each position of the wafer can be calculated or deduced, and then the average thickness, maximum value, minimum value, standard deviation and other data of the metal film within the statistical radius of the wafer can be calculated and displayed in 2D or 3D graphics. Fig.11 A schematic diagram showing a 3D graphical display of the thickness of a metal film on a wafer to be inspected.

[0102] According to another aspect of the present disclosure, a measuring instrument 100 for measuring the thickness of a metal film on a wafer is provided, comprising: a carrier plate 30 for carrying a wafer, wherein the upper surface of the wafer is covered with a metal film; an eddy current sensor 20, disposed above the carrier plate 30, configured to utilize the eddy current effect to excite an eddy current magnetic field in the metal film of the wafer, and to detect the strength of the eddy current magnetic field to generate a corresponding output signal; a distance sensor 50, disposed above the carrier plate 30, for measuring the lift-off height of the eddy current sensor 20 from the wafer; and a processor, communicatively connected to the eddy current sensor 20 and the distance sensor 50, configured to respectively obtain the target output signal generated by the eddy current sensor 20 and the target lift-off height measured by the distance sensor 50 when the carrier plate 30 carries the wafer to be detected; and determine the thickness of the metal film of the wafer to be detected according to the target output signal and the target lift-off height. The processor of the measuring instrument 100 can be communicatively connected to other components of the measuring instrument 100 to control these components or obtain data generated by these components. For a description of each component in the measuring instrument 100, see the description of each component in the measuring instrument 100. Figure 1 The description is not repeated here.

[0103] In some embodiments, the processor is further configured to: determine a first mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor 20 when the lift-off height measured by the ranging sensor 50 is a preset standard height, wherein the coefficient in the first mapping relationship is related to the resolution of the eddy current sensor 20; determine a second mapping relationship between the lift-off height and the resolution of the eddy current sensor 20; correct the coefficient in the first mapping relationship according to the second mapping relationship to obtain a third mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor 20 when the lift-off height measured by the ranging sensor 50 is a target lift-off height; and determine the thickness of the metal film of the wafer to be inspected based on the third mapping relationship according to the target output signal.

[0104] In some embodiments, the processor is further configured to: when the eddy current sensor 20 is adjusted to a standard height, use the eddy current sensor 20 to detect multiple sample wafers in the sample wafer set respectively to obtain an output signal of the eddy current sensor 20 corresponding to each sample wafer in the multiple sample wafers, wherein the upper surface of each sample wafer included in the sample wafer set is covered with a metal film of different thickness and known thickness; and fit a first mapping relationship according to the thickness of each sample wafer in the multiple sample wafers and the output signal of the eddy current sensor 20 corresponding to the sample wafer.

[0105] In some embodiments, the processor is further configured to: sequentially adjust the eddy current sensor 20 to the position of each sample height among a plurality of sample heights, and at each sample height: use the eddy current sensor 20 to detect each sample wafer in the sample wafer set to obtain an output signal of the eddy current sensor 20 corresponding to each sample wafer at the position of the sample height; and determine the resolution of the eddy current sensor 20 at the sample height according to the thickness of each sample wafer in the sample wafer set and the output signal of the eddy current sensor 20 corresponding to each sample wafer at the sample height; and determine a second mapping relationship according to the plurality of sample heights and the resolution of the eddy current sensor 20 corresponding to each sample height among the plurality of sample heights.

[0106] In some embodiments, the measuring instrument 100 also includes: a driving component, configured to drive the eddy current sensor 20 and the ranging sensor 50 to move relative to the supporting plate 30, wherein the processor is further configured to: use the driving component to move the eddy current sensor 20 and the ranging sensor 50 to a plurality of positions to be measured according to a preset path relative to the wafer to be inspected; and at each of the plurality of positions to be measured, respectively obtain a target output signal generated by the eddy current sensor 20 and a target lift-off height measured by the ranging sensor 50, so as to determine the thickness of the metal film of the wafer to be inspected at each of the plurality of positions to be measured.

[0107] According to one aspect of the present disclosure, an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory. The processor is configured to execute the computer program to implement the steps of any method embodiment described above.

[0108] According to one aspect of the present disclosure, a non-transitory computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of any method embodiment described above are implemented.

[0109] According to one aspect of the present disclosure, a computer program product is provided, which includes a computer program. When the computer program is executed by a processor, the steps of any method embodiment described above are implemented.

[0110] In the following, combined Fig.12 Illustrative examples of such electronic devices, non-transitory computer-readable storage media, and computer program products are described.

[0111] Fig.12 An example configuration of an electronic device 1200 that can be used to implement the methods described herein is shown. For example, the above-mentioned measuring instrument 120 for wafer metal film thickness may include a structure similar to the electronic device 1200, or may be fully or at least partially implemented by the electronic device 1200 or a similar device or system.

[0112] The electronic device 1200 may include at least one processor 1202, memory 1204, communication interface(s) 1206, a display device 1208, other input / output (I / O) devices 1210, and one or more mass storage devices 1212, which can communicate with each other, such as via a system bus 1214 or other appropriate connection.

[0113] The processor 1202 may be a single processing unit or multiple processing units, all of which may include a single or multiple computing units or multiple cores. The processor 1202 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuits, and / or any device that manipulates signals based on operating instructions. Among other capabilities, the processor 1202 may be configured to retrieve and execute computer-readable instructions stored in the memory 1204, mass storage device 1212, or other computer-readable media, such as program code of an operating system 1216, program code of an application program 1218, program code of other programs 1220, and the like.

[0114] The memory 1204 and the mass storage device 1212 are examples of computer-readable storage media for storing instructions that are executed by the processor 1202 to implement the various functions described above. For example, the memory 1204 may generally include both volatile memory and non-volatile memory (e.g., RAM, ROM, etc.). In addition, the mass storage device 1212 may generally include a hard drive, a solid-state drive, a removable medium, including external and removable drives, a memory card, a flash memory, a floppy disk, an optical disk (e.g., a CD, a DVD), a storage array, a network attached storage, a storage area network, etc. The memory 1204 and the mass storage device 1212 may all be collectively referred to herein as memory or computer-readable storage media, and may be a non-transitory medium capable of storing computer-readable, processor-executable program instructions as computer program code, which may be executed by the processor 1202 as a specific machine configured to implement the operations and functions described in the examples herein.

[0115] A number of programs may be stored on mass storage device 1212. These programs include operating system 1216, one or more application programs 1218, other programs 1220, and program data 1222, and they may be loaded into memory 1204 for execution. Examples of such applications or program modules may include, for example, computer program logic (e.g., computer program code or instructions) for implementing the following components / functions: methods 120 to method 600 (including any suitable steps of the methods), and / or other embodiments described herein.

[0116] Although in Fig.121204 of the electronic device 1200, but modules 1216, 1218, 1220, and 1222, or portions thereof, may be implemented using any form of computer-readable media accessible by the electronic device 1200. As used herein, "computer-readable media" includes at least two types of computer-readable media, namely, computer-readable storage media and communication media.

[0117] Computer-readable storage media include volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information, such as computer-readable instructions, data structures, program modules or other data. Computer-readable storage media include but are not limited to RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD), or other optical storage device, magnetic cassette, magnetic tape, magnetic disk storage device or other magnetic storage device, or any other non-transmission medium that can be used to store information for access by electronic devices. In contrast, communication media can embody computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transmission mechanism. Computer-readable storage media as defined herein do not include communication media.

[0118] One or more communication interfaces 1206 are used to exchange data with other devices, such as through a network, a direct connection, etc. Such communication interfaces can be one or more of the following: any type of network interface (e.g., a network interface card (NIC)), a wired or wireless (such as IEEE 802.11 wireless LAN (WLAN)) wireless interface, a Worldwide Interoperability for Microwave Access (Wi-MAX) interface, an Ethernet interface, a Universal Serial Bus (USB) interface, a cellular network interface, a Bluetooth interface, a cellular network ... TM The communication interface 1206 may facilitate communication within a variety of network and protocol types, including wired networks (e.g., LAN, cable, etc.) and wireless networks (e.g., WLAN, cellular, satellite, etc.), the Internet, etc. The communication interface 1206 may also provide for communication with external storage devices (not shown) such as in a storage array, network attached storage, storage area network, etc.

[0119] In some examples, a display device 1208 such as a monitor may be included for displaying information and images to the user. Other I / O devices 1210 may be devices that receive various inputs from the user and provide various outputs to the user, and may include a touch input device, a gesture input device, a camera, a keyboard, a remote control, a mouse, a printer, an audio input / output device, and the like.

[0120] The technology described herein can be supported by these various configurations of the electronic device 1200, and is not limited to the specific examples of the technology described herein. For example, the function can also be implemented in whole or in part on the "cloud" by using a distributed system. The cloud includes and / or represents a platform for resources. The platform abstracts the underlying functions of the hardware (e.g., server) and software resources of the cloud. Resources can include applications and / or data that can be used when performing computing processing on a server away from the electronic device 1200. Resources can also include services provided through the Internet and / or through a subscriber network such as a cellular or Wi-Fi network. The platform can abstract resources and functions to connect the electronic device 1200 to other electronic devices. Therefore, the implementation of the functions described herein can be distributed throughout the cloud. For example, the functions can be implemented partially on the electronic device 1200 and partially through a platform that abstracts the functions of the cloud.

[0121] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) to form a technical solution.

Claims

1. A method for measuring the thickness of a metal film on a wafer, wherein: The measuring method is used for a measuring instrument for the thickness of a wafer metal film, the measuring instrument comprising: a carrier plate for carrying a wafer, wherein the upper surface of the wafer is covered with a metal film; an eddy current sensor, arranged above the carrier plate, configured to excite an eddy current magnetic field in the metal film of the wafer by using an eddy current effect, and detect the intensity of the eddy current magnetic field to generate a corresponding output signal; and a distance sensor, arranged above the carrier plate, for measuring the lift-off height of the eddy current sensor from the wafer, the eddy current sensor and the distance sensor being configured to be able to move in a horizontal and vertical direction as a whole, the measuring method comprising: When the carrier plate carries the wafer to be inspected, respectively obtaining the target output signal generated by the eddy current sensor and the target lift-off height measured by the distance measuring sensor; and determining the thickness of the metal film of the wafer to be inspected according to the target output signal and the target lift-off height, Wherein, determining the thickness of the metal film of the wafer to be inspected according to the target output signal and the target lift-off height includes: Determine a first mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor when the lift-off height measured by the distance measuring sensor is a preset standard height, wherein a coefficient in the first mapping relationship is related to a resolution of the eddy current sensor; Determining a second mapping relationship between the lift-off height and the resolution of the eddy current sensor; Correcting the coefficients in the first mapping relationship according to the second mapping relationship to obtain a third mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor when the lift-off height measured by the ranging sensor is the target lift-off height; and According to the target output signal, the thickness of the metal film of the wafer to be inspected is determined based on the third mapping relationship.

2. The measuring method according to claim 1, wherein: Determining that, when the lift-off height measured by the distance measuring sensor is a preset standard height, the first mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor includes: After the eddy current sensor is adjusted to the position of the standard height, the eddy current sensor is used to detect a plurality of sample wafers in the sample wafer set respectively to obtain an output signal of the eddy current sensor corresponding to each sample wafer in the plurality of sample wafers, wherein the upper surface of each sample wafer included in the sample wafer set is covered with a metal film of different and known thickness; and The first mapping relationship is fitted according to the thickness of each sample wafer among the plurality of sample wafers and the output signal of the eddy current sensor corresponding to the sample wafer.

3. The measuring method according to claim 2, wherein: Determining a second mapping relationship between the lift-off height and the resolution of the eddy current sensor includes: The eddy current sensor is adjusted to the position of each sample height among a plurality of sample heights in sequence, and at the position of each sample height: Using the eddy current sensor to detect each sample wafer in the sample wafer set to obtain an output signal of the eddy current sensor corresponding to each sample wafer at the position of the sample height; and determining a resolution of the eddy current sensor at the sample height according to the thickness of each sample wafer in the sample wafer set and an output signal of the eddy current sensor corresponding to each sample wafer at the sample height; and The second mapping relationship is determined according to the multiple sample heights and a resolution of the eddy current sensor corresponding to each of the multiple sample heights.

4. The measuring method according to any one of claims 1 to 3, wherein: The measuring instrument further includes a driving component configured to drive the eddy current sensor and the distance measuring sensor to move relative to the carrier plate, and when the carrier plate carries the wafer to be tested, respectively obtaining the target output signal generated by the eddy current sensor and the target lift-off height measured by the distance measuring sensor further includes: Using the driving device, the eddy current sensor and the distance measuring sensor are moved to a plurality of positions to be tested relative to the wafer to be tested according to a preset path; and At each of the multiple test positions, the target output signal generated by the eddy current sensor and the target lift-off height measured by the ranging sensor are respectively obtained to determine the thickness of the metal film of the wafer to be inspected at each of the multiple test positions.

5. The measuring method according to claim 4, further comprising: Performing data correction on a plurality of positions to be measured and their corresponding measured thicknesses, wherein the plurality of positions to be measured include a plurality of positions whose distances from the edge of the wafer to be detected are within a threshold distance range, and the data correction includes: Correcting the coordinates of the position to be measured; and / or Correct the thickness measurement value corresponding to the position to be measured.

6. The measuring method according to claim 5, wherein: Correction of the coordinates of the position to be measured includes: For each position to be measured: keep the thickness measurement value corresponding to the position to be measured unchanged, and increase the coordinate value of the position to be measured, wherein the increase in the coordinate value of the position to be measured close to the edge of the wafer to be detected is greater than the increase in the coordinate value of the position to be measured far from the edge of the wafer to be detected.

7. The measuring method according to claim 5, wherein: Correction of the thickness measurement value corresponding to the position to be measured includes: For each position to be measured: keep the coordinates of the position to be measured unchanged, and increase the thickness measurement value corresponding to the position to be measured, wherein the increase in the thickness measurement value of the position to be measured close to the edge of the wafer to be detected is greater than the increase in the thickness measurement value of the position to be measured far from the edge of the wafer to be detected.

8. A measuring instrument for measuring the thickness of a metal film on a wafer, comprising: A carrier plate, used for carrying a wafer, wherein the upper surface of the wafer is covered with a metal film; an eddy current sensor, disposed above the carrier plate, configured to utilize an eddy current effect to excite an eddy current magnetic field in the metal film of the wafer, and detect the intensity of the eddy current magnetic field to generate a corresponding output signal; a distance measuring sensor, disposed above the carrier plate, for measuring a lift-off height of the eddy current sensor from the wafer, wherein the eddy current sensor and the distance measuring sensor are configured to move in a horizontal and vertical direction as a whole; and A processor is in communication with the eddy current sensor and the distance sensor, and is configured to respectively obtain a target output signal generated by the eddy current sensor and a target lift-off height measured by the distance sensor when the carrier plate carries the wafer to be inspected; and determine the thickness of the metal film of the wafer to be inspected according to the target output signal and the target lift-off height, Wherein, the processor is further configured to: Determine a first mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor when the lift-off height measured by the distance measuring sensor is a preset standard height, wherein a coefficient in the first mapping relationship is related to a resolution of the eddy current sensor; Determining a second mapping relationship between the lift-off height and the resolution of the eddy current sensor; Correcting the coefficients in the first mapping relationship according to the second mapping relationship to obtain a third mapping relationship between the thickness of the metal film of the wafer and the output signal of the eddy current sensor when the lift-off height measured by the ranging sensor is the target lift-off height; and According to the target output signal, the thickness of the metal film of the wafer to be inspected is determined based on the third mapping relationship.

9. The measuring instrument according to claim 8, wherein: The processor is further configured to: After the eddy current sensor is adjusted to the position of the standard height, the eddy current sensor is used to detect a plurality of sample wafers in the sample wafer set respectively to obtain an output signal of the eddy current sensor corresponding to each sample wafer in the plurality of sample wafers, wherein the upper surface of each sample wafer included in the sample wafer set is covered with a metal film of different and known thickness; and The first mapping relationship is fitted according to the thickness of each sample wafer among the plurality of sample wafers and the output signal of the eddy current sensor corresponding to the sample wafer.

10. The measuring instrument according to claim 9, wherein: The processor is further configured to: The eddy current sensor is adjusted to the position of each sample height among a plurality of sample heights in sequence, and at the position of each sample height: Using the eddy current sensor to detect each sample wafer in the sample wafer set, so as to obtain an output signal of the eddy current sensor corresponding to each sample wafer at a position of the sample height; as well as Determine the resolution of the eddy current sensor at the sample height according to the thickness of each sample wafer in the sample wafer set and the output signal of the eddy current sensor corresponding to each sample wafer at the sample height; as well as The second mapping relationship is determined according to the multiple sample heights and a resolution of the eddy current sensor corresponding to each of the multiple sample heights.

11. The measuring instrument according to claim 8, further comprising: A distance adjustment device, the eddy current sensor and the distance measuring sensor are both fixed on the distance adjustment device, and the distance adjustment device is configured to adjust the lift-off height from the wafer surface.

12. The measuring instrument according to any one of claims 8 to 11, further comprising: A driving assembly is configured to drive the eddy current sensor and the distance measuring sensor to move relative to the carrier plate, wherein: The processor is further configured to: Using the driving assembly to move the eddy current sensor and the distance sensor to a plurality of positions to be tested along a preset path relative to the wafer to be tested; and At each of the multiple test positions, the target output signal generated by the eddy current sensor and the target lift-off height measured by the ranging sensor are respectively obtained to determine the thickness of the metal film of the wafer to be inspected at each of the multiple test positions.

13. The measuring instrument according to claim 12, wherein: The drive assembly comprises: a swing arm, the eddy current sensor and the distance measuring sensor being fixed to the swing arm, the swing arm being configured to drive the eddy current sensor and the distance measuring sensor to move in a direction parallel to a diameter direction of the carrier plate; and The rotating device is connected to the carrying plate and is configured to drive the carrying plate to rotate.

14. The measuring instrument according to claim 13, further comprising: The in-position sensor is configured to detect the notch of the wafer to be inspected during the process in which the rotating device drives the carrier plate to rotate, wherein The processor is further configured to: The current rotation position of the wafer to be detected is determined according to the detection result of the in-situ sensor on the notch, so as to make the eddy current sensor and the distance measuring sensor move according to the preset path.

15. The measuring instrument according to claim 12, wherein: The preset path includes: A straight line path on a horizontal plane that coincides with the diameter of the wafer to be inspected; and / or A circular path on a horizontal plane with the center of the wafer to be inspected as the center.

16. An electronic device, comprising: at least one processor; as well as at least one memory having a computer program stored thereon, When the computer program is executed by the at least one processor, the at least one processor is caused to perform the measurement method according to any one of claims 1 to 7. 17 . A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the processor is caused to perform the measurement method according to any one of claims 1 to 7.

18. A computer program product, comprising a computer program, which, when executed by a processor, causes the processor to perform the measurement method according to any one of claims 1 to 7.

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