Signal measurement system

Abstract

The embodiment of the utility model provides a signal measurement system, and relates to the technical field of measurement. The signal measuring system comprises a measuring sensor, an amplifying circuit, a signal generator and a main control device, the measurement sensor measures a target object and inputs an original measurement signal which is obtained by measurement and at least comprises a target measurement signal into the amplification circuit; the signal generating device generates an initial reference signal and directly or indirectly sends the initial reference signal to the amplifying circuit; the amplifying circuit is used for amplifying the received signal; the main control device obtains a specified reference signal after the initial reference signal is amplified and a specified measurement signal after the target measurement signal is amplified from the output signal of the amplification circuit; determining a noise characteristic parameter of the amplification circuit based on the initial reference signal and the specified reference signal; and obtaining a target measurement signal based on the noise characteristic parameter and the specified measurement signal. According to the utility model, the noise in the measurement signal can be reduced and even eliminated.

Description

Technical Field

[0001] This utility model relates to the field of measurement technology, specifically to a signal measurement system. Background Technology

[0002] Measuring equipment or ultra-high precision machining equipment based on measurement can measure the object to be measured, such as measuring the surface of the object to be measured to obtain the morphology of the surface of the object to be measured; the noise required by the testing equipment during the measurement process is one of the main reasons for the limitation of the equipment performance, so the measurement and processing progress can be improved by reducing the noise.

[0003] In measuring (or processing) equipment, the noise that sensors can detect mainly comes from environmental noise and the noise of the equipment itself. Environmental noise generally includes environmental mechanical vibration, environmental electromagnetic interference, etc.; the noise of the equipment itself is also divided into mechanical vibration, electromagnetic interference, and electrical noise caused by the equipment's circuitry.

[0004] Taking atomic force microscopy as an example, environmental vibration noise accounts for the highest proportion of all noise. The typical noise amplitude is, for example, 5-20 nanometers. With the addition of passive and active damping stages, the vibration noise can be reduced to below 2 nanometers; however, the surface structure of many samples is below 1 nanometer, such as the height difference of atomic steps on the surface of SiC (silicon carbide) being 0.75 nanometers, and the height difference of atomic steps on the surface of graphite being 0.35 nanometers. It can be seen that only when the amplitude of vibration noise is reduced to below the sub-nanometer level can the nanostructure of the sample surface be measured more accurately without being affected by noise.

[0005] In many industrial applications, when it is necessary to observe defect structures of a few nanometers in surface quality assessment, any external environmental interference that introduces noise into the final surface measurement results is considered a "false defect," which can have a significant impact on the measurement results.

[0006] Currently, vibration noise can be eliminated by increasing the measurement time. For example, the initial measurement time can be t0, and the initial signal-to-noise ratio (SNR) can be 0. The relationship between the signal-to-noise ratio (SNR) and the measurement time is as follows:

[0007] SNR(t=t0=SNR0;

[0008] SNR(t=2t0)=1.414SNR0;

[0009] SNR(t=4t0=2SNR0;

[0010] SNR(t=100t0=10SNR0;

[0011] This shows that doubling the integration time or the number of samples only increases the signal-to-noise ratio (SNR) by 41.4%; even increasing the measurement time or the number of samples by 100 times only increases the SNR by 10 times. Such methods of improving the SNR are impractical in real-world applications due to the excessive time required. Furthermore, a longer integration time may introduce additional interference over a longer period, negating the SNR increase from the longer integration time; in other words, it does not actually improve the SNR.

[0012] Taking atomic force microscopy (AFM) measurements as an example, the method used in AFM is to scan an entire image of the sample surface in one pass, scanning one line per second, or 10 lines per second (i.e., 0.1 seconds per line), sampling 256 pixels or 1024 pixels per line. If the integration time for each line needs to be extended, the scanning time for each line becomes 1 second instead of 0.1 seconds. However, if the scanning time for each line is extended to 10 seconds, the scanning time for the entire image would extend to 10 x 1024 = 10240 seconds, or 2.8 hours. This would cause all the long-term drift of the measurement to be included in the scanning of the entire image, resulting in huge image distortion. Therefore, a longer measurement time is not always better.

[0013] As can be seen from the above, how to reduce the impact of noise on the measurement, thereby improving the signal-to-noise ratio of the measurement, remains a problem that needs to be solved. Utility Model Content

[0014] The purpose of this invention is to provide a signal measurement system that can remove noise from the measurement signal caused by the amplification circuit in the measurement sensor, reduce or even eliminate noise in the measurement signal, improve the signal-to-noise ratio of the measurement signal, and thus improve the accuracy of the obtained measurement signal.

[0015] To achieve the above objectives, this utility model provides a signal measurement system, comprising: a measurement sensor, an amplifier circuit, a signal generator, and a main control device; the measurement sensor is used to measure a target object, and inputs the obtained original measurement signal, which includes at least the target measurement signal, into the amplifier circuit; the signal generator is used to generate an initial reference signal and send the initial reference signal directly or indirectly to the amplifier circuit; the amplifier circuit is used to amplify the received signal; the main control device is used to: obtain a designated reference signal after the initial reference signal is amplified and a designated measurement signal after the target measurement signal is amplified from the output signal of the amplifier circuit; determine the noise characteristic parameters of the amplifier circuit based on the initial reference signal and the designated reference signal; and obtain the target measurement signal based on the noise characteristic parameters and the designated measurement signal.

[0016] This invention also provides a signal measurement method applied to the aforementioned signal measurement system. In the signal measurement system, a measurement sensor measures a target object to obtain an original measurement signal, which includes at least a target measurement signal, and this original signal is input to the amplification circuit. An initial reference signal generated by a signal generator is directly or indirectly input to the amplification circuit. The method includes: obtaining a designated reference signal amplified from the initial reference signal and a designated measurement signal amplified from the target measurement signal from the output signal of the amplification circuit; determining noise characteristic parameters of the amplification circuit based on the initial reference signal and the designated reference signal; and obtaining the target measurement signal based on the noise characteristic parameters and the designated measurement signal.

[0017] In one embodiment, the signal generating device is a first signal generator; the output terminal of the first signal generator is connected to the input terminal of the amplifier circuit.

[0018] The first signal generator is used to generate an initial reference signal and input it into the amplifier circuit.

[0019] In one embodiment, the signal generating device includes: a second signal generator and a vibration device; the vibration device is fixed to the target object;

[0020] The second signal generator is used to send a drive signal to the vibration device;

[0021] The vibration device is used to drive the target object to vibrate in a set direction perpendicular to the target object based on the received driving signal, so that the target object generates vibration in the set direction that characterizes the initial reference signal;

[0022] The original measurement signal obtained by the measurement sensor from the target object includes the target measurement signal obtained from the measurement of the surface of the target object and the initial reference signal.

[0023] In one embodiment, there are multiple measuring sensors, each of which is connected to a corresponding amplification circuit; all the measuring sensors are divided into a first type of sensor and a second type of sensor, the first type of sensor includes a plurality of first sensors, the second type of sensor includes a plurality of second sensors, and the second sensor measures a reference surface with a lateral resolution less than a preset resolution value and / or the reference surface is a plane;

[0024] The main control device is used to control at least one target first sensor among the plurality of first sensors and at least one target second sensor among the plurality of second sensors to perform measurements simultaneously;

[0025] The first target sensor is used to measure the target surface of the target object to obtain the surface detection signal of the target surface, and input it into the amplification circuit;

[0026] The second sensor of the target is used to measure the reference surface to obtain a reference measurement signal, which is mainly composed of noise signals formed by environmental influences, and input it into the amplification circuit;

[0027] The main control device is also used for:

[0028] From the output signals of the amplification circuit connected to the first target sensor and the second target sensor, obtain the amplified designated surface detection signal of the surface detection signal and the amplified designated reference measurement signal of the reference measurement signal;

[0029] The surface detection signal is obtained based on the noise characteristic parameters of the amplification circuit connected to the first sensor of the target and the specified surface detection signal corresponding to the first sensor of the target;

[0030] The reference measurement signal is obtained based on the noise characteristic parameters of the amplifier circuit connected to the second target sensor and the specified reference measurement signal corresponding to the second target sensor;

[0031] For each of the target first sensors, the surface detection signal of the target second sensor is corrected using the reference measurement signal of the target first sensor.

[0032] In one embodiment, the main control device is used to calculate the noise characteristic parameters of the amplifier circuit based on multiple initial reference signals with different amplitudes and corresponding designated reference signals. The noise characteristic parameters include the amplification factor noise and the noise floor of the amplifier circuit.

[0033] In one embodiment, the main control device is used to calculate multiple reference noise characteristic parameters of the amplifier circuit based on multiple initial reference signals of different frequencies and corresponding designated reference signals; the reference noise characteristic parameters include: the reference amplification factor noise and the noise floor of the amplifier circuit;

[0034] Based on the frequencies of the initial reference signals corresponding to the plurality of reference noise characteristic parameters, the functional relationship between the reference amplification factor noise and the corresponding frequencies of the initial reference signals is determined;

[0035] The process of obtaining the target measurement signal based on the noise characteristic parameters and the specified measurement signal includes:

[0036] Based on the frequency of the specified measurement signal and the functional relationship, determine the amplification factor noise corresponding to the specified measurement signal;

[0037] The target measurement signal is obtained based on the amplification factor noise corresponding to the specified measurement signal, the background noise, and the specified measurement signal.

[0038] In one embodiment, the frequency of the initial reference signal is a preset frequency or varies within a preset frequency range.

[0039] In one embodiment, the frequency of the initial reference signal is within the frequency band of the original measurement signal.

[0040] In one embodiment, the frequency of the initial reference signal does not overlap with the frequency in the frequency band of the original measurement signal.

[0041] In one embodiment, the measurement sensor is a probe sensor; the operating mode of the probe sensor includes any one or any combination of the following: atomic force microscopy operating mode, scanning probe conductivity operating mode, scanning probe magnetic force microscopy operating mode, scanning probe Kelvin microscopy operating mode, scanning probe photolithography operating mode, and scanning probe single ion implantation operating mode. Attached Figure Description

[0042] Figure 1 This is a block diagram of the signal measurement system according to the first embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the probe sensor S1 measuring the target object in the signal measurement system according to the first embodiment of the present invention;

[0044] Figure 3a This is a frequency diagram of the initial reference signal generated by the signal generating device according to the first embodiment of the present invention; wherein the frequency of the initial reference signal is greater than the maximum frequency value of the frequency band of the original measurement signal;

[0045] Figure 3b This is a frequency diagram of the initial reference signal generated by the signal generating device according to the first embodiment of the present invention; wherein the frequency of the initial reference signal is located within the frequency band of the original measurement signal;

[0046] Figure 4 This is a schematic diagram of the signal measurement system according to the first embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the probe sensor S10 and probe sensor S20 measuring the target object in the signal measurement system according to the first embodiment of this utility model;

[0048] Figure 6This is a schematic diagram of the probe sensor S1 measuring the target object in the signal measurement system according to the second embodiment of the present invention;

[0049] Figure 7 This is a schematic diagram of the probe sensor S10 and probe sensor S20 measuring the target object in the signal measurement system according to the second embodiment of the present invention;

[0050] Figure 8 This is a schematic diagram of a probe measuring the sample surface with different radii of curvature in the signal measurement system of this utility model;

[0051] Figure 9 This is a schematic diagram showing that the measuring probe and the reference probe are fixed on the same base in the signal measurement system according to this utility model;

[0052] Figure 10 This is a schematic diagram of the measuring probe and the reference probe fixed on different bases in the signal measurement system according to this utility model;

[0053] Figure 11 This is a schematic diagram illustrating the simultaneous measurement of a target measuring probe and a target reference probe according to this utility model.

[0054] Figure 12 This is a flowchart illustrating the signal measurement method according to the third embodiment of the present invention. Detailed Implementation

[0055] The embodiments of this utility model will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the purpose, features, and advantages of this utility model. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of this utility model, but are merely illustrative of the essential spirit of the technical solution of this utility model.

[0056] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0057] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0058] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0059] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to include the meaning of “or / and” unless otherwise expressly stated herein.

[0060] In the following description, in order to clearly demonstrate the structure and working method of this utility model, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0061] The first embodiment of this utility model relates to a signal measurement system, such as... Figure 1 As shown, the signal measurement system includes: a measurement sensor 1, an amplifier circuit 2, a signal generator 3, and a main control unit 4. The number of measurement sensors 1 and amplifier circuits 2 can be set as needed. Figure 1 Only one example is shown in the image.

[0062] Measurement sensor 1 is used to measure a target object, including but not limited to measuring the surface of the target object, or measuring some inherent properties of the target object. Measurement sensor 1 is connected to the signal input terminal of amplifier circuit 2, and sends the raw measurement signal obtained from measuring the target object, including at least the target measurement signal, to amplifier circuit 2. In one example, measurement sensor 1 is a probe sensor used to measure the surface morphology of the target object, and the raw measurement signal is the signal obtained by scanning a set area on the surface of the target object. The operating mode of the probe sensor includes any one or any combination of the following: atomic force microscopy mode, scanning probe conductive mode, scanning probe magnetic force microscopy mode, scanning probe Kelvin microscopy mode, scanning probe photolithography mode, and scanning probe single ion implantation mode.

[0063] The signal generator 3 is used to generate an initial reference signal and send the initial reference signal directly or indirectly to the amplifier circuit 2. The amplitude of the initial reference signal generated by the signal generator 3 will continuously change, for example, from 0 to a set value.

[0064] In one example, signal generating device 3 is a first signal generator, which is directly connected to the signal input terminal of amplifier circuit 2 and sends the generated initial reference signal to amplifier circuit 2. In this embodiment, signal generating device 3 is used as the first signal generator, and the first signal generator is directly connected to the signal input terminal of amplifier circuit 2. In this case, the first signal generator is used to generate the initial reference signal and input it into the amplifier circuit.

[0065] Amplifier circuit 2 is used to amplify the received signal, including the original measurement signal and the initial reference signal mentioned above. Amplifier circuit 2 includes at least a preamplifier circuit, and may further include multi-stage amplifier circuits, the number of which can be set according to requirements. Of course, regardless of the number of stages of amplifier circuits included in amplifier circuit 2, these multi-stage amplifier circuits can be understood as being combined into an amplifier circuit with a set amplification factor.

[0066] For amplifier circuit 2, the amplified signal inevitably carries noise, which can be divided into two parts: one part is the noise floor, meaning that even when the input signal to amplifier circuit 2 is 0, the amplifier circuit still outputs a noise signal. The other part is the noise introduced by the amplification factor β of amplifier circuit 2. The following explanation uses measuring sensor 1 as a probe sensor S1 as an example to illustrate the noise of amplifier circuit 2. Please refer to [link / reference]. Figure 2 The probe sensor S1 is used to scan and measure the three-dimensional surface topography of the target object D. The original measurement signal α obtained by the probe sensor S1 includes: the surface detection signal α of the target object D to be measured. S With environmental noise signal n a (Generally includes noise from the current environment and noise from vibrations).

[0067] α=α S +n a (1)

[0068] The original measurement signal α is input to amplifier circuit 2. The specified measurement signal after amplification by amplifier circuit 2 is denoted as γ, and its expression is:

[0069] γ=γ S +n γ (2)

[0070] Wherein, the specified measurement signal γ is composed of the signal part γ S and background noise part n γ Composition: Let β represent the amplification factor of amplifier circuit 2, then:

[0071] γ=α·β+n γ (3)

[0072] Even if the amplification factor of amplifier circuit 2 is 0, amplifier circuit 2 will still output a background noise n. γ .

[0073] The amplification factor β of amplifier circuit 2 will also introduce noise:

[0074] β=β0(1+n β (4)

[0075] Here, β0 is the amplification factor of amplifier circuit 2 without amplification noise, and n β The amplification factor and noise factor of amplifier circuit 2; therefore, β0n β This refers to the noise component in the amplification factor β of amplifier circuit 2.

[0076] As shown above, after the original measurement signal is amplified by amplifier circuit 2, noise will inevitably be mixed in. Therefore, it is necessary to remove the noise in amplifier circuit 2 to obtain the desired target measurement signal (i.e., surface detection signal α). S Based on this, a first signal generator is added to this application. The initial reference signal generated by the first signal generator is known. Therefore, based on the initial reference signal and the specified reference signal after the initial reference signal is amplified by the amplifier circuit 2, the noise characteristic parameters of the amplifier circuit 2 can be obtained. The noise characteristic parameters include: the amplification factor noise of the amplifier circuit 2 (i.e., the amplification factor noise factor mentioned above) and the noise floor. The specific process is as follows:

[0077] The main control device 4 is connected to the signal output terminal of the amplifier circuit 2, and is used to obtain the specified reference signal after the initial reference signal is amplified and the specified measurement signal after the target measurement signal is amplified from the output signal of the amplifier circuit. The main control device 4 and the amplifier circuit 2 form a dual-path connection, one path for obtaining the specified reference signal after the initial reference signal is amplified and the other path for obtaining the specified measurement signal after the target measurement signal is amplified.

[0078] For example, a T-type interface is connected to the signal output terminal of amplifier circuit 2. The main control device 4 integrates two different filtering devices on the two interfaces connected to amplifier circuit 2, which can filter out the specified reference signal and the specified measurement signal from the output signal of amplifier circuit 2 respectively. For example, the main control device 4 integrates a bandpass filter, which is connected to one interface of amplifier circuit 2. The bandpass filter can only allow signals that meet the frequency of the initial reference signal to pass through. Although the initial reference signal is amplified by amplifier circuit 2, its frequency does not change. Therefore, the main control device 4 can filter out the amplified initial reference signal from the signal output by amplifier circuit 2 through the bandpass filter, which is recorded as the specified reference signal.

[0079] The initial reference signal has a preset frequency or varies within a preset frequency range; the frequency bandwidth of the preset frequency range can be set very narrow to avoid affecting the noise spectrum in the measurement signal.

[0080] The frequency of the initial reference signal is set as follows:

[0081] Method 1: The frequency of the initial reference signal does not overlap with the frequency band of the original measurement signal. For example, the frequency of the initial reference signal is greater than the maximum frequency value in the frequency band of the original measurement signal. Figure 3a As shown, the frequency band of the original measurement signal is f. m to f M The frequency of the initial reference signal is a preset frequency value f. R1 f R1 >f M At this point, a low-pass filter can be configured in the main control device 4 (or between the main control device 4 and the amplifier circuit 2). The low-pass filter is configured to only allow frequencies below f. d The signal passes through, f M <f d <f M This allows the specified measurement signal to be filtered out from the output signal of amplifier circuit 2.

[0082] Method 2: The frequency of the initial reference signal is within the frequency band of the original measurement signal. Please refer to [link / reference]. Figure 3b The frequency band of the original measurement signal is f m to f M The frequency of the initial reference signal is a preset frequency value f. R2 f M <f R2 <f M At this point, a band-stop filter can be configured in the main control device 4 (or between the main control device 4 and the amplifier circuit 2). The band-stop filter can block frequencies up to f. R2 The signal passes through, that is, the specified measurement signal is filtered out from the output signal of the amplifier circuit 2, so that the main control device can obtain the specified measurement signal from the output signal of the amplifier circuit 2.

[0083] Based on the obtained initial reference signal and the specified reference signal, determine the noise characteristic parameters of the amplifier circuit; please refer to... Figure 2 The first signal generator is directly connected to the signal input terminal of amplifier circuit 2. The initial reference signal α generated by the first signal generator is... R After amplification by amplifier circuit 2, the specified reference signal γ is obtained. R Its expression is:

[0084] γ R = α R βR + n γR (5)

[0085] Where, α R n represents the initial reference signal. γR β represents the noise floor of amplifier circuit 2. R This represents the amplification factor of amplifier circuit 2; as mentioned before, the amplification factor of amplifier circuit 2 contains noise, therefore the above equation (5) can be further expressed as:

[0086] γ R = α R β 0R (1+n βγR )+ n γR (6)

[0087] Where, β 0R n represents the amplification factor of amplifier circuit 2 without amplification noise. βγR This represents the amplification factor and noise factor of amplifier circuit 2; therefore, β 0R ·n βγR That is, the amplification factor β of amplifier circuit 2. R The noise component.

[0088] In equation (5) above, the initial reference signal α R With the specified reference signal γ R All are known quantities. Signal generator 2 can continuously adjust the amplitude of the generated initial reference signal. Thus, the initial reference signal at each amplitude and the corresponding specified reference signal are substituted into equation (5) above to form an equation. Solving the equations obtained by combining multiple different amplitudes, the background noise n of amplifier circuit 2 in equation (5) above can be obtained. γR With magnification β R Furthermore, β R =β 0R (1+n βγR ), β 0R Given the quantities, the amplification factor and noise factor n of amplifier circuit 2 can be calculated. βγR .

[0089] Then, based on the noise characteristic parameters and the specified measurement signal, the target measurement signal is obtained. Specifically, by transforming equation (3), the expression for the original measurement signal α can be obtained:

[0090] α=(γ- n γ ) / β (7)

[0091] For the same amplifier circuit 2, if its noise characteristic parameters are considered constant (or change very little), the noise floor n of amplifier circuit 2 has been calculated in the aforementioned process. γR With magnification βR Therefore, β = β R n γ =n γR The obtained background noise n γR With magnification β R Substituting into equation (11) yields the original measurement signal α.

[0092] Since the original measurement signal does not contain the initial reference signal, the original measurement signal is the target measurement signal. In other words, the original measurement signal α is the target measurement signal after the noise of the amplifier circuit 2 has been removed. Furthermore, the target measurement signal can be multiplied by the amplification factor of the amplifier circuit 2 without amplification noise to obtain the amplified target measurement signal.

[0093] In one example, the functional relationship between the frequency of amplifier circuit 2 and the amplification factor noise can be determined first, and then the corresponding amplification factor noise can be selected based on different frequencies of the original measurement signal. When calculating the amplification factor noise of amplifier circuit 2 using an initial reference signal with a frequency greater than the maximum frequency value in the frequency band of the original measurement signal and a specified reference signal corresponding to the initial reference signal, the calculated amplification factor noise may be less than the noise in the frequency band range of the original measurement signal because the noise may decrease as the frequency increases. However, this embodiment selects different amplification factor noise for different frequencies by determining the functional relationship between the frequency of amplifier circuit 2 and the amplification factor noise, so as to minimize the error in amplification factor noise caused by different frequencies. The specific process is as follows:

[0094] The main control device 4 calculates multiple reference noise characteristic parameters of the amplifier circuit based on multiple initial reference signals of different frequencies and corresponding designated reference signals. The reference noise characteristic parameters include the reference amplification factor noise and the noise floor of the amplifier circuit. Thus, multiple initial reference signals of different frequencies and the amplification factor noise corresponding to each initial reference signal of different frequencies can be obtained.

[0095] Based on the frequencies of the initial reference signals corresponding to multiple reference noise characteristic parameters, the functional relationship between the reference amplification noise and the corresponding frequencies of the initial reference signals is determined. The initial reference signals at these multiple frequencies, and the amplification noise corresponding to each frequency, are fitted to obtain the functional relationship between frequency and amplification noise. This functional relationship can be linear or nonlinear, such as f = k * P + b, where f represents the frequency, k and b are constants obtained during the fitting process, and P is the amplification noise. Therefore, when adjusting the specified measurement signal based on the noise characteristic parameters, the amplification noise at the specified measurement signal frequency is first determined based on the frequency of the specified measurement signal and the aforementioned functional relationship between frequency and amplification noise. Then, based on this amplification noise, the noise floor of amplifier circuit 2, and the specified measurement signal, the target measurement signal is obtained.

[0096] Based on the aforementioned process, the target measurement signal α can be obtained, but the target measurement signal α still contains the environmental noise signal n. a Based on this, the environmental noise signal n in the target measurement signal α can also be removed using the following scheme. a .

[0097] There are multiple measuring sensors, each connected to a corresponding amplifier circuit; all measuring sensors are divided into a first type of sensor and a second type of sensor. The first type of sensor includes several first sensors, and the second type of sensor includes several second sensors.

[0098] Taking a probe sensor as an example, the signal measurement system in this embodiment is a scanning probe system. Please refer to [link / reference]. Figure 4 The scanning probe system includes: a first type of sensor, a second type of sensor, a carrier drive device, an amplifier circuit 2, a main control device 4, and multiple longitudinal controllers 5. The first type of sensor includes several first sensors (hereinafter referred to as measuring probes Cm), and the second type of sensor includes several second sensors (hereinafter referred to as reference probes Cr). The measuring probes Cm and reference probes Cr are both fixed on the carrier drive device, and the carrier drive device is communicatively connected to the main control device 4. The measuring probes Cm and reference probes Cr are both connected to the main control device 4 through the amplifier circuit 2. In this case, the probes and amplifier circuits 2 can correspond one-to-one, or one amplifier circuit 2 can correspond to multiple probes (including measuring probes Cm and / or reference probes Cr), or all probes can share one amplifier circuit 2 (this is an example in the figure).

[0099] Each measuring probe Cm corresponds to and is communicatively connected to a longitudinal controller 5, and each longitudinal controller 5 is communicatively connected to the main control device 4. The tips of the measuring probe Cm and the reference probe Cr face the surface of the target object 6 placed on the sample stage 8. The reference probe Cr corresponds to and is communicatively connected to each longitudinal controller 5. Furthermore... Figure 4 The communication connection lines shown are for illustrative purposes only; in practice, communication connections can be made using standardized wiring.

[0100] exist Figure 4 In this context, the reference surface is the surface of the reference object 7 placed on the sample stage 8, and the target surface is the surface of the target object 6. That is, the reference probe Cr is used to measure the surface of the reference object 7, and the measurement probe Cm is used to measure the surface of the target object 6. However, it is not limited to this. It is also possible to set the reference surface measured by the reference probe Cr and the target surface measured by the measurement probe Cm to be located on the surface of the target object 6.

[0101] Regardless of whether the target surface and the reference surface are located on the same object, it is necessary to ensure that: the lateral resolution of the reference surface measured by the reference probe Cr is less than the preset resolution value and / or the reference surface is a plane; specifically, when the reference surface is a plane, the undulations of the reference surface can avoid the changes in van der Waals force on the reference probe Cr, that is, avoid the vertical up and down movement of the reference probe Cr. Figure 1 The example shown is a plane, which is only for illustrative purposes. It can also have a three-dimensional shape with a lateral resolution lower than the preset resolution value.

[0102] The second sensor (reference probe Cr) is controlled to measure the lateral resolution of the reference surface to be less than a preset resolution value. In this case, the reference probe Cr is not sensitive to the undulations of the reference surface. In one example, the radius of curvature of the tip of the reference probe Cr can also be set to be greater than a preset radius of curvature, so that the lateral resolution of the reference surface measured by the reference probe Cr is less than the preset resolution value.

[0103] When scanning and measuring the surface of a target object (such as a wafer, silicon wafer, quartz wafer, etc.), the main control device selects at least one first sensor from a number of first sensors (measuring probes) as the target first sensor (hereinafter referred to as the target measuring probe). That is, the number of target measuring probes is greater than or equal to one and less than or equal to the number of measuring probes. In addition, the main control device will also select at least one target second sensor (hereinafter referred to as the target reference probe) from a number of second sensors (reference probes). The target measuring probe and the target reference probe perform measurements simultaneously.

[0104] The main control device, through a longitudinal controller communicatively connected to the target measurement probe and the target reference probe, controls the target measurement probe and the target reference probe to perform simultaneous measurements. Each target measurement probe is used to perform three-dimensional topographic scanning measurements on the target surface of the target object, and each target reference probe is used to measure the reference surface. Furthermore, the lateral resolution of each target reference probe measuring the reference surface is less than a preset resolution value, and / or the reference surface is planar. Additionally, the longitudinal controller can control the movement of the target measurement probe or target reference probe communicatively connected to it in the Z-direction.

[0105] For example, the distance S between the target reference probe and the reference surface being measured can be controlled before measurement. r Greater than the distance S between the target measurement probe and the target surface it measures T For example, distance S r For distance S T The measurement spatial resolution of the target reference probe on the reference surface is reduced by two to five times, which greatly reduces the influence of the undulating structure of the reference surface on the measurement value of the target reference probe. In other words, the reference surface measured by the reference probe can be regarded as a "flat" surface. Compared with the target measurement probe, the target reference probe can be considered to be measuring a plane.

[0106] The first sensor is used to measure the target surface of the target object to obtain the surface detection signal of the target surface, and input it into the amplifier circuit 2; the surface detection signal is a kind of raw measurement signal.

[0107] The second sensor is used to measure the reference surface to obtain a reference measurement signal, which is mainly composed of noise signals formed by environmental influences, and inputs it into the amplifier circuit 2; the reference measurement signal is a kind of original measurement signal.

[0108] by Figure 5 Taking this example, the first target sensor is S10 (target measurement probe), which is connected to the amplifier circuit A1. The second target sensor is S20 (target reference probe), which is connected to the amplifier circuit A2. Both the target surface and the reference surface are located on the surface of the target object.

[0109] The first sensor S10 measures the target surface to obtain the surface detection signal α of the target surface. 10 Includes: the detection signal α under noise-free conditions. S10 With environmental noise signal n a10 .

[0110] α 10 =α S10 +n a10 (12)

[0111] Surface detection signal α 10 The input is fed into the amplifier circuit A1 connected to the first target sensor S10, and its amplification factor is β. 10 Surface detection signal α 10 The amplified surface detection signal after amplification by amplifier circuit 2 is denoted as γ. 10 Its expression is:

[0112] γ 10 =γ S10 +n γ10 (13)

[0113] Specified surface detection signal γ 10 From the signal part γ S10 and background noise part n γ10 Composition, with β 10 Let the amplification factor of amplifier circuit 2 be:

[0114] γ 10 =α 10 ·β 10 +n γ10 (14)

[0115] The second sensor S20 measures the reference surface to obtain a reference measurement signal α, which is mainly composed of noise signals caused by environmental influences. 20 Includes: the detection signal α under noise-free conditions. S20 With environmental noise signal n a20 .

[0116] α 20 =α S20 +n a20 (15)

[0117] Reference measurement signal α 20 The input is fed into the amplifier circuit 2 connected to the second target sensor S20, and its amplification factor is β. 20 Reference measurement signal α 20 The specified reference measurement signal amplified by amplifier circuit 2 is denoted as γ. 20 Its expression is:

[0118] γ 20 =γ S20 +n γ20 (16)

[0119] Specify reference measurement signal γ 20 From the signal part γ S20 and background noise part n γ20 Composition, with β 20 Let the amplification factor of amplifier circuit 2 be:

[0120] γ 20 =α 20 β 20 +n γ20 (17)

[0121] The main control device obtains the amplified surface detection signal γ from the output signals of the amplification circuits connected to the first and second target sensors. 10 The specified reference measurement signal γ is amplified from the reference measurement signal. 20 .

[0122] exist Figure 5 In the circuit, the first signal generator is connected to amplifier circuits A1 and A2 respectively, and the first signal generator inputs the initial reference signal α to amplifier circuit A1. R1 The initial reference signal α is input to amplifier circuit A2. R2 The main control unit obtains the initial reference signal α from the output of amplifier circuit A1. R1 Amplified reference signal γ R1 Based on the initial reference signal α R1 With the specified reference signal γ R1 The noise floor n of amplifier circuit A1 can be calculated. γ10 With magnification β 10 .

[0123] Furthermore, the noise characteristic parameters (including the background noise n) of the amplifier circuit A1 connected to the first sensor of the target can be used as a basis. γ10 With magnification β 10 The designated surface detection signal γ corresponding to the first sensor S10 of the target 10 The target surface detection signal α is obtained. 10 Specifically, the noise floor n of amplifier circuit A1 γ10 With magnification β 10 Substituting into equation (14), the target surface detection signal α can be obtained. 10 Target surface detection signal α 10 The expression is:

[0124] α 10 =(γ) 10 -n γ10 ) / β 10 (18)

[0125] The main control unit obtains the initial reference signal α from the output of amplifier circuit A2. R2 Amplified reference signal γ R2 Based on the initial reference signal α R2 With the specified reference signal γR2 The noise floor n of amplifier circuit A2 can be calculated. γ20 With magnification β 20 Furthermore, based on the noise characteristic parameters (including the background noise n) of the amplifier circuit A2 connected to the second target sensor S20. γ20 With magnification β 20 The designated reference measurement signal γ corresponding to the second sensor S20 of the target 20 The target reference measurement signal α is obtained. 20 Specifically, this means reducing the noise floor n of amplifier circuit A2. γ20 With magnification β 20 Substituting into equation (17), the target reference measurement signal α can be obtained. 20 Target reference measurement signal α 20 The expression is:

[0126] α 20 =(γ) 20 -n γ20 ) / β 20 (19)

[0127] Since the first sensor S10 and the second sensor S20 are in similar environments and are performing measurements simultaneously, the noise signals affecting them are similar, and the target reference measurement signal α... 20 In this context, since the reference surface can be considered a plane, and the target's second measurement sensor is less affected by the undulations of the reference surface during measurement, the target reference measurement signal α... 20 This also reflects the noise contained in the surface detection signal measured by the first target sensor. Furthermore, the main control device can use the target reference measurement signal from the second target sensor to correct the target surface detection signals of each first target sensor; for example, the main control device can remove the environmental noise signal n from the first target sensor S10 using a differential method. a10 In order to obtain the final detection signal α 12 The specific calculation process is as follows:

[0128] α 12 =α 10 -α 20 =α S10 +n a10 -α S20 +n a20

[0129] Where α S20 =0, n a10 =n a20 ,but

[0130] αS10 =α 10 -α 20 Substituting into equations (18) and (19) above, we get:

[0131] α S10 =(γ) 10 -n γ10 ) / β 10 -(γ 20 -n γ20 ) / β 20

[0132] Therefore, the noise-free detection signal α obtained by the first sensor S10 measuring the target surface can be obtained. S10 .

[0133] As described above, by using the reference measurement signal of the second target sensor to remove the noise signal contained in the surface detection signal of each target first sensor, the noise signal contained in the surface detection signal of the first target sensor is reduced, and the signal-to-noise ratio of the surface detection signal of the first target sensor is improved; thus, the accuracy of the obtained measurement signal is further improved.

[0134] The second embodiment of this utility model relates to a signal measurement system. Compared with the first embodiment, in this embodiment, the initial reference signal generated by the signal generating device 3 is sent to the amplification circuit 2 through the measurement sensor 1, that is, the initial reference signal is introduced into the measurement signal of the measurement sensor 1.

[0135] Please refer to Figure 6 The signal generating device 3 includes: a second signal generator 31 and a vibration device 32; the vibration device 32 is fixed to the target object 6.

[0136] The second signal generator 31 is used to send a drive signal to the vibration device 32.

[0137] The vibration device 32 is used to drive the target object 6 to vibrate in a predetermined direction perpendicular to the surface of the target object 6 based on the received drive signal, so that the target object generates vibration in the predetermined direction that represents the initial reference signal; for example, if the target object is placed on a horizontal platform, the predetermined direction is not vertical. For example, the vibration device 32 is a vibration horn, and the vibration device 32 can be mounted on one edge of the target object 6. Figure 6 (Taking this as an example), but not limited to this, the vibration device 32 can also be a vibration support platform, on which the target object 6 is placed, and the vibration support platform drives the target object 6 to vibrate in a set direction.

[0138] In other words, the second signal generator 31 is used to generate a drive signal. After the drive signal is input to the vibration device 32, the vibration device 32 drives the target object 6 to vibrate in a set direction. The vibration is detected by the measuring sensor and becomes the initial reference signal. The amplitude and frequency of the vibration of the target object 6 driven by the vibration device can be adjusted by the magnitude of the drive signal input to the vibration device 32, so as to realize the control of the amplitude and frequency of the initial reference signal.

[0139] As shown above, the original measurement signal obtained by the measurement sensor 1 from the surface of the target object 6 includes the target measurement signal obtained from the measurement of the surface of the target object 6 and the initial reference signal.

[0140] exist Figure 6 Taking the measurement sensor 1 as an example, probe sensor S1 is used to scan and measure the three-dimensional shape of the surface of the target object 5. The original measurement signal α obtained by probe sensor S1 includes: the surface detection signal of the target object 5 (i.e., the target measurement signal) and the initial reference signal α. R The surface detection signal of target object 5 includes: the detection signal α under noise-free conditions. S With environmental noise signal n a (Generally including the noise of the current environment and the noise from vibrations), then:

[0141] α=α S +α R +n a (1)

[0142] The original measurement signal α is input to amplifier circuit 2, and the specified measurement signal after amplification by amplifier circuit 2 is denoted as γ. S1 Its expression is:

[0143] γ S1 = γ S + n γ (2)

[0144] Wherein, the specified measurement signal γ S1 From the signal part γ S and background noise part n γ Composition: Let β represent the amplification factor of amplifier circuit 2, then:

[0145] γ S1 =α·β+ n γ (3)

[0146] The amplification factor β of amplifier circuit 2 will also introduce noise:

[0147] β = β0(1+n β (4)

[0148] Here, β0 is the amplification factor of amplifier circuit 2 without amplification noise, and n β The amplification factor and noise factor of amplifier circuit 2; therefore, β0n β This refers to the noise component in the amplification factor β of amplifier circuit 2.

[0149] As mentioned above, after the original measurement signal is amplified by amplifier circuit 2, noise inevitably gets mixed in. Therefore, it is necessary to remove the noise in amplifier circuit 2 to obtain a more accurate surface detection signal. Based on this, a second signal generator 31 and a vibration device 32 are added in this application. The drive signal generated by the second signal generator 31 is sent to the vibration device 32 so that the target object 5 generates a signal α representing the initial reference signal through the vibration device 32. R The vibration; the initial reference signal is known (frequency and amplitude) and is determined by the magnitude of the driving signal.

[0150] The signal output by amplifier circuit 2 is the amplified version of the original measurement signal, which combines the surface detection signal of the target object and the initial reference signal α generated by the vibration of the vibration device. R The main control device 4 obtains the amplified specified measurement signal of the surface detection signal and the initial reference signal α from the signal output by the amplifier circuit 2 based on the frequency of the initial reference signal. R Amplified specified reference signal γ R .

[0151] Based on this initial reference signal α R The specified reference signal γ, amplified by amplifier circuit 2, is compared with the initial reference signal. R The noise characteristic parameters of amplifier circuit 2 are obtained, including: the amplification factor noise (i.e., the aforementioned amplification factor noise factor) and the noise floor of amplifier circuit 2; wherein, based on the initial reference signal α R The specified reference signal γ, amplified by amplifier circuit 2, is compared with the initial reference signal. R The specific method for obtaining the noise characteristic parameters of amplifier circuit 2 can be referred to the first embodiment, and will not be repeated here. The main difference is that in this example, the initial reference signal actually goes through the measurement sensor and its noise, as well as the subsequent amplifier circuit 2 and its noise. Thus, the measurement sensor and its noise are also reflected in the noise characteristic parameters of amplifier circuit 2. When the target measurement signal (surface detection signal) is determined based on the noise characteristic parameters and the specified measurement signal, the noise caused by the measurement sensor and amplifier circuit in the surface measurement signal can be removed at the same time, making the obtained target measurement signal (surface detection signal) more accurate.

[0152] Based on the aforementioned process, the target measurement signal can be obtained, but the target measurement signal still contains environmental noise signals; therefore, the environmental noise signals in the target measurement signal can be removed by the following scheme.

[0153] There are multiple measuring sensors, each connected to a corresponding amplifier circuit; all measuring sensors are divided into a first type of sensor and a second type of sensor. The first type of sensor includes several first sensors, and the second type of sensor includes several second sensors.

[0154] Taking a probe sensor as an example, the signal measurement system in this embodiment is a scanning probe system. Figure 7 For example, the selected target first sensor is S10 (target measurement probe), which is connected to the amplifier circuit A1. The selected target second sensor is S20 (target reference probe), which is connected to the amplifier circuit A2. The target surface and the reference surface are both located on the surface of the target object. The target object is equipped with a vibration device 32. The second signal generator 31 is connected to the vibration device 32. The second signal generator 31 sends the generated drive signal to the vibration device 32. The vibration device 32 causes the target object 6 to vibrate, which represents the initial reference signal.

[0155] The first sensor S10 measures the target surface to obtain the original measurement signal α. 10 Includes: surface detection signals of the target surface and initial reference signal α R10 The surface detection signal includes: the detection signal α under noise-free conditions. S10 With environmental noise signal n a10 ; Original measurement signal α 10 The expression is as follows:

[0156] α 10 =α S10 +n a10 +α R10 (20)

[0157] Original measurement signal α 10 The input is fed into the amplifier circuit 2 connected to the first target sensor S10, and its amplification factor is β. 10 The original measurement signal α 10 The amplified surface detection signal after amplification by amplifier circuit 2 is denoted as γ. 10 Its expression is:

[0158] γ 10 = γ S10 + n γ10 (twenty one)

[0159] Specified surface detection signal γ 10 From the signal part γ S10 and background noise part n γ10 Composition, with β 10 Let the amplification factor of amplifier circuit 2 be:

[0160] γ 10 =α 10 ·β 10 + n γ10 (twenty two)

[0161] The second sensor S20 measures the reference surface to obtain the original measurement signal α. 20 The original measurement signal α 20 The reference measurement signal α mainly consists of noise signals caused by environmental influences. 20 With the initial reference signal α R20 Reference measurement signal α 20 Includes: the detection signal α under noise-free conditions S20 With environmental noise signal n a20 ; Original measurement signal α 20 The expression is as follows:

[0162] α 20 =α S20 +n a20 +α R20 (twenty three)

[0163] Original measurement signal α 20 The input is fed into the amplifier circuit 2 connected to the second target sensor S20, and its amplification factor is β. 20 The original measurement signal α 20 The specified reference measurement signal amplified by amplifier circuit 2 is denoted as γ. 20 Its expression is:

[0164] γ 20 = γ S20 + n γ20 (twenty four)

[0165] Specify reference measurement signal γ 20 From the signal part γ S20 and background noise part n γ20 Composition, with β 20 Let the amplification factor of amplifier circuit 2 be:

[0166] γ 20 =α 20 ·β 20 + n γ20 (25)

[0167] The main control unit obtains the initial reference signal α from the output of amplifier circuit A1. R10 The specified reference signal γ after being amplified by amplifier circuit A1 R10 Based on the initial reference signal α R10 With the specified reference signal γ R10 The noise floor n of amplifier circuit A1 can be calculated. γ10 With magnification β 10 .

[0168] Similarly, the main control unit obtains the initial reference signal α from the output of amplifier circuit A2. R20 The specified reference signal γ after being amplified by amplifier circuit A2 R20 Based on the initial reference signal α R20 With the specified reference signal γ R20 The noise floor n of amplifier circuit A2 can be calculated. γ20 With magnification β 20 .

[0169] The main control device obtains the amplified surface detection signal γ from the output signals of the amplification circuits connected to the first and second target sensors. 10 The specified reference measurement signal γ is amplified from the reference measurement signal. 20 .

[0170] Furthermore, the noise characteristic parameters (including the background noise n) of the amplifier circuit A1 connected to the first sensor of the target can be used as a basis. γ10 With magnification β 10 The designated surface detection signal γ corresponding to the first sensor S10 of the target 10 The target surface detection signal α is obtained. 10 Specifically, the noise floor n of amplifier circuit A1 γ10 With magnification β 10 Substituting into equation (14), the target surface detection signal α can be obtained. 10 Target surface detection signal α 10 The expression is:

[0171] α 10 =(γ) 10 - n γ10 ) / β 10 (26)

[0172] Based on the noise characteristic parameters (including the background noise n) of the amplifier circuit A2 connected to the second sensor S20 of the target. γ20 With magnification β 20 The designated reference measurement signal γ corresponding to the second sensor S20 of the target 20 The target reference measurement signal α is obtained.20 Specifically, this means reducing the noise floor n of amplifier circuit A2. γ20 With magnification β 20 Substituting into equation (18), the target reference measurement signal α can be obtained. 20 Target reference measurement signal α 20 The expression is:

[0173] α 20 =(γ) 20 - n γ20 ) / β 20 (27)

[0174] Initial reference signal α R10 With the initial reference signal α R20 All of these are generated by the vibration of the vibrating device, therefore α R10 =α R20 Therefore, the surface detection signal α can be used to... 10 Compared with the reference measurement signal α 20 The initial reference signal is removed by differential grading.

[0175] Since the first sensor S10 and the second sensor S20 are in similar environments and are performing measurements simultaneously, the noise signals affecting them are similar, and the target reference measurement signal α... 20 In this context, since the reference surface can be considered a plane, and the target's second measurement sensor is less affected by the undulations of the reference surface during measurement, the target reference measurement signal α... 20 It can also reflect the noise contained in the surface detection signal measured by the first sensor of the target. Therefore, the main control device can use the target reference measurement signal from the second sensor of the target to correct the target surface detection signals of each target's first sensor; for example, n... a10 With n a20 Assuming they are approximately equal, the main control device removes the environmental noise signal n from the first target sensor S10 using a differential method. a10 .

[0176] As shown above, the initial reference signal α in the surface measurement signal can be removed simultaneously through differential grading. R10 With environmental noise signal n a10 To obtain the final detection signal α 12 The specific calculation process is as follows:

[0177] α 12 =α 10 -α 20 =α S10 +n a10 +α R10-α S20 +n a20 +α R20

[0178] Where α S20 =0, n a10 =n a20 α R10 =α R20 ,but:

[0179] α S10 =α 10 -α 20 Substituting into equations (26) and (27) above, we get:

[0180] α S10 =(γ) 10 -n γ10 ) / β 10 -(γ 20 -n γ20 ) / β 20

[0181] Therefore, the noise-free detection signal α obtained by the first sensor S10 measuring the target surface can be obtained. S10 .

[0182] As described above, by using the reference measurement signal of the second target sensor to remove the noise signal contained in the surface detection signal of each target first sensor, the noise signal contained in the surface detection signal of the first target sensor is reduced, and the signal-to-noise ratio of the surface detection signal of the first target sensor is improved.

[0183] It should be noted that the second embodiment corresponds to this embodiment, therefore this embodiment can be implemented in conjunction with the second embodiment. The relevant technical details mentioned in the second embodiment remain valid in this embodiment, and the technical effects achievable in the second embodiment can also be achieved in this embodiment. To reduce repetition, they will not be repeated here. Correspondingly, the relevant technical details mentioned in this embodiment can also be applied to the second embodiment.

[0184] It should also be noted that in the first or second embodiment, a correspondence can be established between the first sensor and the second sensor, with each first sensor corresponding to at least one second sensor. When the first sensor is controlled to perform a measurement, its corresponding second sensor is also controlled to perform a measurement simultaneously. If the target first sensor corresponds to multiple second sensors, when the first sensor is controlled to perform a measurement, its corresponding multiple target second sensors are also controlled to perform measurements simultaneously. When correcting the surface detection signal of the target first sensor using the reference measurement signals of multiple target second sensors, the average or median of the reference measurement signals of multiple target second sensors can be used to obtain a signal for correcting the surface detection signal of the target first sensor. However, this is not the only possibility; it is also possible to eliminate the need for a correspondence between the first and second sensors, simply ensuring that at least one second sensor performs a measurement simultaneously while each target first sensor measures the target surface.

[0185] In one example, the tip shape of the aforementioned reference probe can be any of the following: a three-dimensional sphere, a planar square, or a planar circle, so that the radius of curvature of the reference probe tip is greater than a preset radius of curvature, and the lateral resolution of the reference surface measured by the reference probe is less than a preset resolution value. The larger the radius of curvature of the probe, the lower the lateral resolution of the three-dimensional topography of the reference surface it measures. Figure 8 As shown, the radius of curvature of the left probe tip is smaller than that of the right probe tip. When these two probes measure the same sample surface structure, the lateral resolution of the sample surface morphology measured by the left probe is greater than that measured by the right probe. The distance from the left probe to the sample surface is also smaller than that from the right probe to the sample surface, resulting in a greater lateral resolution of the sample surface morphology measured by the left probe. Furthermore, the proportion of noise signal in the signal measured by the left probe is less than that measured by the right probe.

[0186] In one example, the distance between the tip of the reference probe and the reference surface is greater than a first preset distance value. The greater the distance between the reference probe and the reference surface, the lower the lateral resolution of the reference probe in measuring the reference surface. Setting the distance between the tip of the reference probe and the reference surface to be greater than the first preset distance value can make the lateral resolution of the reference surface measured by the reference probe less than the preset resolution value.

[0187] For example, if the radius of curvature of the target measurement probe is 1-50 nanometers, then the radius of curvature of the reference probe can be selected to be 20 times that of the target measurement probe. In this case, the radius of curvature of the reference probe is 20-50 nanometers. Although the increased tip area of ​​the reference probe will increase the van der Waals force between the probe and the reference surface, the distance between the tip of the reference probe and the reference surface is greater than the first preset distance value. That is, the reference probe is far away from the reference surface, and the van der Waals force will be reduced to the set measurement range. This greatly reduces the spatial resolution of the reference probe on the reference surface, and greatly reduces the influence of the undulation structure of the reference surface on the measurement value of the reference probe. That is, the reference surface measured by the reference probe can be regarded as a "flat" surface. At this time, even if the reference surface measured by the reference probe and the target surface measured by the target measurement probe are located on the same sample surface, the reference probe will not be affected by the surface undulation of the sample.

[0188] In this embodiment, the measurement probe can be either an active or passive probe, and the reference probe can also be either an active or passive probe. Specifically, for a passive probe, the bending of the cantilever beam causes a laser beam emitted to the back of the cantilever beam. After emission, the beam enters a position sensor, which records the bending of the cantilever beam, thereby obtaining the distance signal from the probe to the surface. For an active probe, the cantilever beam is composed of a bimetallic structure, and the resistance wire deposited on it changes. The change in the resistance wire reflects the bending of the cantilever beam, thereby obtaining the distance signal from the probe to the surface. The operating modes of the measurement probe include any one or any combination of the following: atomic force microscopy mode, scanning probe conductivity mode, scanning probe magnetic force microscopy mode, scanning probe Kelvin microscopy mode, scanning probe photolithography mode, and scanning probe single ion implantation mode.

[0189] The drive unit includes a drive unit 11 and at least one scanner 12. Several measuring probes Cm can be divided into one or more probe groups, each probe group corresponding to a scanner. The probes in each probe group are fixed on the corresponding scanner. The scanner is used to drive the probes fixed on it to move within a small range in the X, Y, and Z three-dimensional space. The drive unit is used to drive all the scanners to move all the probes within a large range in the X, Y, and Z three-dimensional space. In addition, the drive unit 11 can be used to fix the probe array and can also rotate in the X and Y axis directions for angle adjustment. The main control unit 4 is connected to the drive unit 11 and each scanner respectively. The main control unit 4 can also be connected to each scanner through the wiring on the drive unit 11, so as to control the movement of the drive unit 11 in the X, Y, and Z axes, control the movement of the scanner 12 in the X, Y, and Z axes, and / or adjust the angle rotation in the X and Y axis directions. It should be noted that multiple probe groups can share the same scanner, meaning multiple probe groups are fixed on the same scanner, or each probe group can have its own dedicated scanner, meaning each scanner has only one probe group.

[0190] In this design, the measuring probe Cm in the first type of sensor and the reference probe Cr in the second type of sensor have different vibration frequencies. Both types of sensors are located on the same probe base. Specifically, the base can be a scanner that carries the driving device. Since the measuring probe Cm and the reference probe Cr have different vibration frequencies, they can be fixed to the same scanner on the driving device. Because the measuring probe Cm and the reference probe Cr have different vibration frequencies, resonance will not affect the normal operation of the probes. Figure 9 As shown, a measurement probe Cm and a reference probe Cr form a MEMS probe array. The two are fixed on the same base (scanner). Except for the probe being able to move freely in the Z direction, the two move simultaneously in other degrees of freedom. Since the environments in which the two are located are very similar, the noise signals they perceive are also very similar.

[0191] Alternatively, the measuring probe Cm in the first type of sensor and the reference probe Cr in the second type of sensor have the same vibration frequency. In this case, the measuring probe Cm and the reference probe Cr can be fixed on different scanners on the drive device, which can avoid the adverse effects of resonance between the measuring probe Cm and the reference probe Cr on the probe's operation. Figure 10As shown, the measuring probe Cm and the reference probe Cr are fixed on different bases (scanners). In this case, the reference probe Cr does not need to follow the measuring probe Cm for scanning. The reference probe Cr measures the reference surface without moving, obtaining a purer noise signal. Alternatively, the distance between the first type of probe and the second type of probe can be directly set to be greater than a second preset distance value. That is, when the probes are fixed on the scanner, ensure that the distance between the measuring probe Cm and the reference probe Cr is greater than a set distance value. In this case, even if the measuring probe Cm and the reference probe Cr have the same vibration frequency, resonance will not occur.

[0192] In the aforementioned process, environmental vibration noise in the first target sensor (target measurement probe) is removed using a differential method. However, this is not the only method; the surface detection signal of the target measurement probe can also be corrected using the reference measurement signal of the second target sensor (target reference probe), as detailed below:

[0193] Method 1: For each target measurement probe, the surface detection signal of the target measurement probe is corrected using the reference measurement signal of the target reference probe, including: calculating the product of the reference measurement signal of the target reference probe and the preset weighting coefficient; for each target measurement probe, the corrected surface detection signal of the target measurement probe is obtained by subtracting the product from the surface detection signal of the target measurement probe.

[0194] Method 2: For each target measurement probe, the surface detection signal of the target measurement probe is corrected using the reference measurement signal of the reference probe, including: calculating the product of the reference measurement signal of the reference probe and the preset weighting coefficient; for each target measurement probe, the distance between the target measurement probe and the target surface is adjusted based on the product of the reference measurement signal of the target reference probe and the preset weighting coefficient, and the surface detection signal of the target measurement probe is reacquired as the corrected surface detection signal of the target measurement probe.

[0195] The following is combined with Figure 4 and Figure 11 The measurement method of the scanning probe system in this embodiment will be described in detail. Taking only one target measurement probe CT and one target reference probe Cr as an example, the target measurement probe CT is used to measure the surface of the target object 6, and the target reference probe Cr is used to measure the reference surface of the reference object 7.

[0196] During a measurement, the main control device 4 controls the target measurement probe CT and the target reference probe Cr to perform measurements simultaneously at time t. The main control device 4 acquires the surface detection signal obtained by the target measurement probe CT measuring the surface of the target object 6, and acquires the reference measurement signal obtained by the target reference probe Cr at the same time, which is mainly composed of noise signal formed by environmental influence.

[0197] The surface probe signal Z along the Z-axis direction obtained by the target measurement probe CT at time t. T (t) is determined by the three-dimensional topography of the target surface and the noise signal, and can be obtained as follows:

[0198] Z TD (t)= Z TC (t)+ΔN T (t) Equation (28)

[0199] Among them, Z TD (t) represents the surface detection signal of the target surface obtained by the target measurement probe CT at time t, Z TC (t) represents the height signal of the target measurement probe CT at time t when there is no noise signal. ΔN T (t) represents the height change signal caused by the noise signal to the target measurement probe CT at time t.

[0200] Similarly, the reference measurement signal Z obtained by the target reference probe Cr at time t is... rD (t) can be represented as:

[0201] Z rD (t)= Z rC (t)+ΔN r (t) Equation (29)

[0202] Among them, Z rD (t) represents the reference measurement signal obtained by the target reference probe Cr at time t, Z rC (t) represents the height signal of the target reference probe Cr at time t when there is no noise signal, ΔN r (t) represents the height change signal caused by the noise signal to the target reference probe Cr at time t.

[0203] Since the target measurement probe CT and the target reference probe Cr are in similar environments, the noise signals they experience are similar. However, due to differences in their performance and distance from the measured surface, their bending amplitudes differ, resulting in different signals measured by the target measurement probe CT and the target reference probe Cr. This leads to the noise signals they perceive being not entirely equal, thus indicating a certain correlation between these two noise signals. Therefore, a preset weighting coefficient α exists, such that:

[0204] ΔN T (t)= αΔN r (t) Equation (30)

[0205] With h r (t) represents the elevation of the three-dimensional shape of the reference surface relative to the plane on the reference object at time t, H r Let represent the pre-defined distance from the target reference probe Cr to the reference surface, which is a fixed value; then the above equation (29) can be converted to:

[0206] Z rD (t)=H r +h r (t)+ΔN r (t) Equation (31)

[0207] Since the target reference probe Cr is not sensitive to the height undulations of the reference surface, the reference surface can be considered as an approximately flat surface. In this case, h r (t) = 0.

[0208] Then the above equation (31) can be transformed into:

[0209] Z rD (t)=H r +ΔN r (t) Equation (32)

[0210] Furthermore, ΔN r (t)=Z rD (t)-H r Equation (33)

[0211] Similarly, with h T (t) represents the elevation of the three-dimensional topography of the target surface relative to the reference plane on the sample surface at time t, H T This represents the pre-defined distance between the target measurement probe CT and the target surface, which is a fixed value, Z. TA (t) represents the reference plane on the sample surface, which is a fixed value; then the above equation (28) can be converted to:

[0212] ZTD (t)-Z TA (t)=H T +h T (t)+ΔN T (t) Equation (34)

[0213] h T (t)=Z TD (t)-ΔN T (t)-H T -Z TA (t) Equation (35)

[0214] Substituting equation (35) into equation (30) above, we get:

[0215] h T (t)=Z TD (t)-αΔN r (t)-H T -Z TA (t) Equation (36)

[0216] Substituting equation (36) into equation (33) above, we get:

[0217] h T (t)=Z TD (t)-α(Z rD (t)-H r )-H T -Z TA (t) Equation (37)

[0218] Equation (10) above represents h in this measurement. T The expression for (t), due to H r H T Z TA If (t) are all fixed values, then the h measured in this study will be... T When (t) is subtracted from the height of the reference point, it can be eliminated, and the above equation (37) can be simplified to:

[0219] h T (t)=Z TD (t)-αZ rD (t) Equation (38)

[0220] Therefore, Z can be... TD (t)-αZ rD (t) represents the surface detection signal after removing noise during this measurement process, i.e., the surface detection signal Z of the target measurement probe CT using the above method. TD (t) is corrected.

[0221] Furthermore, the h measured in this study... TSubtracting the height of the reference point from the height of the reference point (t) yields the difference between the sample surface and the reference point measured at time t. For example, the difference between h measured at time t-1 and the reference point is... T Using (t-1) as the reference point, we can obtain:

[0222] Δ x h T (X)=h T (t)-h T (t-1)=Z TD (t)-α(Z rD (t)-H r )-H T -Z TA (t)-(Z TD (t-1)-α(Z rD (t-1)-H r )-H T -Z TA (t-1))=Z TD (t)-Z TD (t-1)-α(Z rD (t)-Z rD (t-1)) Equation (39)

[0223] Based on the above derivation process, it can be seen that for each target measurement probe, the height change of the target surface after removing the noise signal can be obtained based on the surface detection signal obtained by the target measurement probe in this measurement and the reference measurement signal obtained by the target reference probe in this measurement, as well as the surface detection signal obtained by the target measurement probe in the previous measurement and the reference measurement signal obtained by the target reference probe in the previous measurement.

[0224] If the above method two is used to measure the surface detection signal Z of the target measurement probe CT TD (t) is corrected because the target reference probe Cr is not sensitive to the height fluctuations of the reference surface. Therefore, the reference measurement signal Z obtained by the target reference probe Cr in this measurement is corrected. rD (t) and the reference measurement signal Z obtained from the previous measurement rD The change between (t-1) represents the change in the noise signal.

[0225] The longitudinal controller 5, connected to the target reference probe Cr, will read the reference measurement signal Z measured by the target reference probe Cr. rD (t) is sent to the main control device 4, and the main control device 4 can transmit the reference measurement signal Z. rD The product of (t) and the preset weighting coefficient α is input to the longitudinal controller 5, αZ, which is connected to the target measurement probe CT. rD (t) The height change brought to the target reference probe Cr may be upward or downward, which is reflected in Z.rD (t) on; αZ rD (t) is input to the longitudinal controller 5, which is connected in communication with the target measurement probe CT. The longitudinal controller 5 then bases the input on αZ. rD (t) By controlling the target measurement probe CT to move in the opposite direction to the influence of the noise signal by a corresponding height change value, the movement in the Z direction caused by the noise signal interference can be compensated. This is equivalent to removing the noise signal from the control signal input to the target measurement probe CT by the longitudinal controller 5. At this time, the main control device 4 reads the surface detection signal Z of the target measurement probe CT. TD’ (t), Z TD’ (t) is the surface detection signal after removing noise, which is the corrected surface detection signal.

[0226] In the above process, the setting of the preset weighting coefficient α is very important. The preset weighting coefficient is set as follows: both the measurement probe and the reference probe are controlled to perform non-scanning measurements; the preset weighting coefficient is set based on the relationship between the first measurement signal obtained by the measurement probe and the second measurement signal obtained by the reference probe.

[0227] The setting of the preset weighting coefficient α will be explained below in conjunction with the above derivation process. Please refer to [link / reference]. Figure 11 The figure shows the change in height of the target measurement probe CT and the target reference probe Cr in the Z direction over time due to the influence of noise signals.

[0228] The main control unit 4 controls both the target measurement probe CT and the target reference probe Cr to perform non-scanning measurements, that is, to measure while remaining at the same surface position. If there is no noise signal, the measured values ​​of the target measurement probe CT and the target reference probe Cr are both constant values, reflecting the magnitude of the attraction force exerted on the probe by the surface, that is, reflecting the distance between the probe and the surface.

[0229] By adjusting the preset weighting coefficient α in equation (10), the noise term α(Z) in equation (10) is eliminated. rD (t)-H r The effect of the noise term on equation (10) is such that the change of the noise term does not affect equation (10). At this time, the preset weighting coefficient α is the preset weighting coefficient α between the target measurement probe CT and the target reference probe Cr. It can be used in the subsequent formal measurement process of the target measurement probe CT to eliminate the influence of noise signal on the target measurement probe CT.

[0230] It should be noted that for each measurement probe, the preset weighting coefficient α between it and the corresponding reference probe can be determined based on the above method; if there are multiple target reference probes, the reference measurement signals of multiple target reference probes can be weighted and the average value can be obtained to obtain the signal used to correct the surface detection signal of the target measurement probe.

[0231] In this embodiment, when the target measurement probe is performing measurements, a target reference probe is controlled to perform measurements simultaneously with the target measurement probe. The lateral resolution of the reference surface measured by the target reference probe is less than a preset resolution value and / or the reference surface is planar, meaning the target reference probe is insensitive to surface undulations. Therefore, the reference measurement signal output by the target reference probe is primarily composed of noise signals generated by environmental influences. Since the target reference probe and the target measurement probe perform measurements simultaneously, the reference measurement signal output by the target reference probe can also reflect the noise contained in the surface detection signal measured by the target measurement probe. This allows for the removal of noise signals contained in the surface detection signals of each target measurement probe using the reference measurement signal, reducing the noise in the surface detection signals of the target measurement probe and improving the signal-to-noise ratio of the surface detection signals. Thus, while maintaining the same signal-to-noise ratio requirement for the surface detection signals, the requirements of the scanning probe system for environmental vibration and sound insulation noise interference can be reduced, contributing to cost reduction.

[0232] The third embodiment of this utility model relates to a signal measurement method, which is applied to the signal measurement system in the first or second embodiment.

[0233] The specific process of the signal measurement method in this embodiment is as follows: Figure 12 As shown.

[0234] Step 101: Obtain the specified reference signal after the initial reference signal is amplified and the specified measurement signal after the target measurement signal is amplified from the output signal of the amplifier circuit.

[0235] Step 102: Determine the noise characteristic parameters of the amplifier circuit based on the initial reference signal and the specified reference signal.

[0236] Step 103: Based on the noise characteristic parameters and the specified measurement signal, obtain the target measurement signal.

[0237] Furthermore, the signal measurement method includes: controlling at least one target first sensor among a plurality of first sensors and at least one target second sensor among a plurality of second sensors to perform measurements simultaneously; obtaining a specified surface detection signal after the surface detection signal is amplified and a specified reference measurement signal after the reference measurement signal is amplified from the output signals of the amplification circuit connected to the target first sensor and the target second sensor; obtaining a surface detection signal based on the noise characteristic parameters of the amplification circuit connected to the target first sensor and the specified surface detection signal corresponding to the target first sensor; obtaining a reference measurement signal based on the noise characteristic parameters of the amplification circuit connected to the target second sensor and the specified reference measurement signal corresponding to the target second sensor; and for each target first sensor, correcting the surface detection signal of the target first sensor using the reference measurement signal of the target second sensor.

[0238] Since the first and second embodiments correspond to this embodiment, this embodiment can be implemented in conjunction with the first and second embodiments. The relevant technical details mentioned in the first and second embodiments remain valid in this embodiment, and the technical effects achievable in the first and second embodiments can also be realized in this embodiment. To reduce repetition, they will not be repeated here. Correspondingly, the relevant technical details mentioned in this embodiment can also be applied to the first and second embodiments.

[0239] The preferred embodiments of the present invention have been described in detail above, but it should be understood that, if necessary, aspects of the embodiments can be modified to utilize aspects, features, and concepts from various patents, applications, and publications to provide other embodiments.

[0240] In light of the detailed description above, these and other changes can be made to the embodiments. Generally, the terminology used in the claims should not be considered limited to the specific embodiments disclosed in the specification and claims, but should be understood to include all possible embodiments together with the full scope of equivalents enjoyed by these claims.

Claims

1. A signal measurement system, characterized in that, include: Measurement sensors, amplifier circuits, signal generators, and main control devices; The measurement sensor is used to measure the target object, and the original measurement signal, which includes at least the target measurement signal, is input to the amplification circuit. The signal generating device is used to generate an initial reference signal and send the initial reference signal directly or indirectly to the amplification circuit; The amplifier circuit is used to amplify the received signal; The main control device is used for: From the output signal of the amplifier circuit, obtain the designated reference signal after the initial reference signal is amplified and the designated measurement signal after the target measurement signal is amplified; Based on the initial reference signal and the specified reference signal, the noise characteristic parameters of the amplifier circuit are determined; The target measurement signal is obtained based on the noise characteristic parameters and the specified measurement signal.

2. The signal measurement system according to claim 1, characterized in that, The signal generating device is a first signal generator; the output terminal of the first signal generator is connected to the input terminal of the amplifier circuit. The first signal generator is used to generate an initial reference signal and input it into the amplifier circuit.

3. The signal measurement system according to claim 1, characterized in that, The signal generating device includes: a second signal generator and a vibration device; the vibration device is fixed to the target object; The second signal generator is used to send a drive signal to the vibration device; The vibration device is used to drive the target object to vibrate in a set direction perpendicular to the target object based on the received driving signal, so that the target object generates vibration in the set direction that characterizes the initial reference signal; The original measurement signal obtained by the measurement sensor from the target object includes the target measurement signal obtained from the measurement of the surface of the target object and the initial reference signal.

4. The signal measurement system according to claim 1, characterized in that, The number of measurement sensors is multiple, and each measurement sensor is connected to the corresponding amplification circuit; all the measurement sensors are divided into a first type of sensor and a second type of sensor. The first type of sensor includes a number of first sensors, and the second type of sensor includes a number of second sensors. The second sensor measures the lateral resolution of the reference surface, which is less than a preset resolution value and / or the reference surface is a plane. The main control device is used to control at least one target first sensor among the plurality of first sensors and at least one target second sensor among the plurality of second sensors to perform measurements simultaneously; The first target sensor is used to measure the target surface of the target object to obtain the surface detection signal of the target surface, and input it into the amplification circuit; The second sensor of the target is used to measure the reference surface to obtain a reference measurement signal, which is mainly composed of noise signals formed by environmental influences, and input it into the amplification circuit; The main control device is also used for: From the output signals of the amplification circuit connected to the first target sensor and the second target sensor, obtain the amplified designated surface detection signal of the surface detection signal and the amplified designated reference measurement signal of the reference measurement signal; The surface detection signal is obtained based on the noise characteristic parameters of the amplification circuit connected to the first sensor of the target and the specified surface detection signal corresponding to the first sensor of the target; The reference measurement signal is obtained based on the noise characteristic parameters of the amplifier circuit connected to the second target sensor and the specified reference measurement signal corresponding to the second target sensor; For each of the target first sensors, the surface detection signal of the target second sensor is corrected using the reference measurement signal of the target first sensor.

5. The signal measurement system according to claim 1, characterized in that, The main control device is used to calculate the noise characteristic parameters of the amplifier circuit based on multiple initial reference signals with different amplitudes and corresponding designated reference signals. The noise characteristic parameters include the amplification factor noise and the noise floor of the amplifier circuit.

6. The signal measurement system according to claim 5, characterized in that, The main control device is used to calculate multiple reference noise characteristic parameters of the amplifier circuit based on multiple initial reference signals of different frequencies and corresponding designated reference signals; The reference noise characteristic parameters include: the reference amplification factor noise and the noise floor of the amplifier circuit; Based on the frequencies of the initial reference signals corresponding to the plurality of reference noise characteristic parameters, the functional relationship between the reference amplification factor noise and the corresponding frequencies of the initial reference signals is determined; The process of obtaining the target measurement signal based on the noise characteristic parameters and the specified measurement signal includes: Based on the frequency of the specified measurement signal and the functional relationship, determine the amplification factor noise corresponding to the specified measurement signal; The target measurement signal is obtained based on the amplification factor noise corresponding to the specified measurement signal, the background noise, and the specified measurement signal.

7. The signal measurement system according to claim 1, characterized in that, The frequency of the initial reference signal is a preset frequency or varies within a preset frequency range.

8. The signal measurement system according to claim 1, characterized in that, The frequency of the initial reference signal is within the frequency band of the original measurement signal.

9. The signal measurement system according to claim 1, characterized in that, The frequency of the initial reference signal does not overlap with the frequency in the frequency band of the original measurement signal.

10. The signal measurement system according to claim 1, characterized in that, The measurement sensor is a probe sensor; The operating modes of the probe sensor include any one or any combination of the following: atomic force microscopy operating mode, scanning probe conductive operating mode, scanning probe magnetic force microscopy operating mode, scanning probe Kelvin microscopy operating mode, scanning probe photolithography operating mode, and scanning probe single ion implantation operating mode.

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