High-precision electrical parameter measurement structure and method, and scanning probe microscope

Abstract

The invention relates to the technical field of scanning probe microscopes, and discloses a high-precision electrical parameter measurement structure, which is at least applied to a scanning probe microscope, and comprises a probe capable of forming an equivalent capacitance structure with the surface of a sample; wherein the capacitance value of the equivalent capacitance structure responds to the surface state of the sample; the circuit board is integrated with a resonance circuit, and the resonance circuit is connected with the probe so as to form a resonance circuit with the equivalent capacitor structure; wherein the resonance characteristic of the resonance circuit responds to the capacitance value of the equivalent capacitance structure. The resonant circuit is integrated on the circuit board and is physically connected with the probe, so that the equivalent capacitance structure formed by the probe and the surface of the sample is directly used as a component of the resonant circuit, and the probe and the resonant circuit are connected without an independent signal line. Energy loss generated in the signal transmission process is effectively avoided, interference of transmission line stray capacitance on measurement is eliminated, and therefore test sensitivity is improved. The invention also discloses a measuring method and a scanning probe microscope.

Description

Technical Field

[0001] This application relates to the technical field of scanning probe microscopy, for example, to a high-precision electrical parameter measurement structure and method, and a scanning probe microscope. Background Art

[0002] Currently, in the technical field of scanning probe microscopy, existing measurement methods mainly obtain surface topography and electrical information through physical contact or tunneling effect between the probe and the sample. However, for key parameters such as doping concentration, type, and interface state of semiconductor materials or heterostructure samples, traditional capacitance detection techniques suffer from insufficient detection sensitivity and are difficult to capture capacitance changes at the sub-attofarad level at the micro-nano scale. Especially at the nano scale, the weak capacitance change between the sample surface and the probe is easily unable to be stably detected due to signal drowning, resulting in insufficient measurement accuracy and dynamic response ability.

[0003] To improve capacitance detection performance, related technologies have tried to improve the spacing control algorithm between the probe and the sample, such as a multi-stage piezoelectric feedback system, or introduce impedance spectroscopy analysis combined with fixed-frequency excitation and lock-in amplification techniques to suppress noise. Some solutions also use highly nonlinear devices as probes to achieve high-resolution imaging in the ultra-wideband microwave band using their quantum noise limit sensitivity.

[0004] In the process of implementing the embodiments of the present disclosure, it is found that there are at least the following problems in the related technologies: The related technologies have improved the test sensitivity to a certain extent. However, in practical applications, the probe and the resonant circuit are usually connected by independent signal lines. This connection method will introduce energy loss during the signal line transmission, and the parasitic capacitance generated by the transmission line is often large, which may mask the extremely weak capacitance change on the sample surface, resulting in low test sensitivity and difficulty in meeting the high-precision measurement requirements.

[0005] The information disclosed in the background art section is only used to enhance the understanding of the background of this application, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. The summary is not a comprehensive review, nor is it intended to identify key / important elements or delineate the scope of protection of these embodiments, but rather serves as a prelude to the subsequent detailed description.

[0007] Embodiments of the present disclosure provide a high-precision electrical parameter measurement structure and a scanning probe microscope to reduce the influence of signal line transmission loss and parasitic capacitance during the test process and improve the test sensitivity.

[0008] In some embodiments, the high-precision electrical parameter measurement structure is applied to at least one type of scanning probe microscope; the measurement structure includes: a probe that can form an equivalent capacitance structure with the surface of the sample; wherein, the capacitance value of the equivalent capacitance structure responds to the surface state of the sample; a circuit board integrating a resonant circuit, and the resonant circuit is connected to the probe to form a resonant loop with the equivalent capacitance structure; wherein, the resonant characteristics of the resonant loop respond to the capacitance value of the equivalent capacitance structure.

[0009] Optionally, the measurement structure further includes: a clamping structure that can fix the probe, and at least part of the circuit board is located in the accommodation cavity formed by the clamping structure itself or together with the probe.

[0010] Optionally, at least part of the clamping structure forms an electrical shield between the circuit board and the external environment.

[0011] Optionally, the clamping structure includes: a base; an elastic pressing piece, the first end of which is fixed on the surface of the base, and the second end can apply a pressing force to the side of the base surface under the action of elastic deformation to fix the probe between the second end and the base; wherein, the main body part connecting the first end and the second end can enclose an accommodation cavity with the base surface.

[0012] Optionally, the end of the clamping structure for fixing the probe clamps the probe and / or the circuit board.

[0013] Optionally, the measurement structure further includes: a shielding structure that at least partially covers the resonant circuit area of the circuit board to form an electrical shield between the resonant circuit and the external environment.

[0014] Optionally, when the tip of the probe contacts the sample, at least a structure form of metal, oxide, or semiconductor is formed to form an equivalent capacitance structure.

[0015] Optionally, the measurement structure further includes: a bias voltage module for applying a DC and / or AC bias voltage to the sample and / or the probe.

[0016] In some embodiments, the high-precision electrical parameter measurement method is applied to the high-precision electrical parameter measurement structure described in any one of the above; the measurement method includes: making the probe and the sample form an equivalent capacitance structure; wherein, the equivalent capacitance structure and the resonant circuit on the circuit board form a resonant loop; making the resonant loop in a preset resonant working state; applying an electrical excitation signal to the probe and / or the sample to obtain a response signal; wherein, the electrical excitation signal includes a DC bias voltage and / or an AC bias voltage; collecting and processing the response signal to obtain the signal characteristic parameters of the response signal.

[0017] Optionally, the measurement method further includes: controlling the measurement structure to scan the sample along a preset path; wherein, an equivalent capacitance structure is formed at at least some positions of the preset path; recording the spatial position information of the scan points and / or the sample height information and / or the signal characteristic parameters of the response signal; and generating at least the topography and / or doping concentration and / or doping type of the sample according to the spatial position information of the scan points and / or the sample height information and / or the signal characteristic parameters of the response signal.

[0018] In some embodiments, the scanning probe microscope includes: the high-precision electrical parameter measurement structure described in any one of the above.

[0019] The high-precision electrical parameter measurement structure, method, and scanning probe microscope provided by the embodiments of the present disclosure can achieve the following technical effects: The probe can form an equivalent capacitance structure with the sample surface, and the capacitance value of the equivalent capacitance structure responds to the surface state of the sample. The circuit board integrates a resonant circuit, and the resonant circuit is connected to the probe to form a resonant loop with the equivalent capacitance structure. The resonant characteristics of the resonant loop respond to the capacitance value of the equivalent capacitance structure. By integrating the resonant circuit on the circuit board and establishing a physical connection with the probe, the equivalent capacitance structure formed between the probe and the sample surface directly serves as a component of the resonant loop, without the need to connect the probe and the resonant circuit through an independent signal line. Since the signal line transmission link is omitted, the energy loss generated during signal transmission can be effectively avoided, and at the same time, the parasitic capacitance of the transmission line to the measurement can be eliminated, thereby reducing the influence of the above factors on the test process and significantly improving the test sensitivity of the measurement structure to changes in the sample surface state.

[0020] The above general description and the following description are only exemplary and explanatory, and are not used to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations and the drawings do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation, and among them: Figure 1 is a schematic structural diagram of a high-precision electrical parameter measurement structure provided by an embodiment of the present disclosure; Figure 2 is a schematic structural diagram of another high-precision electrical parameter measurement structure provided by an embodiment of the present disclosure; Figure 3 is a schematic structural diagram of another high-precision electrical parameter measurement structure provided by an embodiment of the present disclosure; Figure 4 is a schematic structural diagram of another high-precision electrical parameter measurement structure provided by an embodiment of the present disclosure; Figure 5 It is a schematic structural diagram of another high-precision electrical parameter measurement structure provided by an embodiment of the present disclosure; Figure 6 It is a schematic structural diagram of another high-precision electrical parameter measurement structure provided by an embodiment of the present disclosure.

[0022] Reference numerals: 10: clamping structure; 11: probe; 12: circuit board; 13: base; 14: elastic pressing sheet; 141: first end; 142: second end; 143: main body part; 15: accommodation cavity; 16: shielding structure; 17: metal layer; 18: oxide layer; 19: semiconductor layer; 20: light source; 21: detector; 22: sample; 23: displacement stage; 24: signal amplifier; 25: detector; 26: high-pass filter; 27: lock-in amplifier; 28: controller; 29: radio frequency source; 30: bias voltage module; 31: ground terminal; 32: fixing part; 33: tip. Detailed implementation manners

[0023] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are only for reference and illustration purposes and are not intended to limit the embodiments of the present disclosure. In the following technical description, for the sake of explanation, a sufficient understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, well-known structures and devices can be shown in a simplified manner.

[0024] The terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the embodiments of the present disclosure are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so as to implement the embodiments of the present disclosure described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0025] In the embodiments of the present disclosure, the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "middle", "outer", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the embodiments of the present disclosure and their embodiments, and are not used to limit that the indicated device, element or component must have a specific orientation, or be constructed and operated in a specific orientation. Moreover, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0026] In addition, the terms "arranged", "connected", "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there is internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0027] Unless otherwise specified, the term "plurality" means two or more.

[0028] In the embodiments of the present disclosure, the character " / " indicates that the front and rear objects are in an "or" relationship. For example, A / B means: A or B.

[0029] The term "and / or" is a description of the association relationship of an object, indicating that there can be three relationships. For example, A and / or B means: A or B, or, A and B these three relationships.

[0030] It should be noted that, without conflict, the embodiments in the embodiments of the present disclosure and the features in the embodiments can be combined with each other.

[0031] Combined Figure 1-6 As shown, the embodiments of the present disclosure provide a high-precision electrical parameter measurement structure, which is at least applied to a scanning probe 11 microscope. The measurement structure includes a probe 11 and a circuit board 12. The probe 11 can form an equivalent capacitance structure with the surface of the sample 22. Among them, the capacitance value of the equivalent capacitance structure responds to the surface state of the sample 22. The circuit board 12 integrates a resonant circuit, and the resonant circuit is connected to the probe 11 to form a resonant loop with the equivalent capacitance structure. Among them, the resonant characteristics of the resonant loop respond to the capacitance value of the equivalent capacitance structure.

[0032] In an embodiment of the present disclosure, the resonant circuit includes a first port and / or a second port and / or a third port. The first port is connected to an excitation source, which may be a radio frequency source 29 or a pulse voltage source or others; the second port is connected to the probe 11; the third port is connected to a signal processor. The signal processor includes a signal amplifier 24 and / or a detector 25 and / or a high-pass filter 26 (such as a DC blocking circuit) and / or a lock-in amplifier 27, and the lock-in amplifier 27 may be integrated into the controller 28. Specifically, a quarter-wavelength transmission line structure can be integrated on the circuit board 12 as the resonant circuit. The transmission line can be made based on a low-loss dielectric material, such as designing a specific conductive pattern on a low-loss dielectric substrate. The physical length of the transmission line can be determined proportionally according to the wavelength corresponding to the center frequency of the target operating frequency band. The transmission line is respectively configured with a radio frequency input port (the first port), a probe 11 connection port (the second port), and a signal output port (the third port). Among them, the probe 11 connection port is electrically connected to the probe 11 directly through a microstrip line or a solder joint, so that the equivalent capacitance structure formed by the probe 11 and the sample 22 becomes an inherent component of the resonant circuit. The transmission line exhibits a band-pass filtering response characteristic in the target frequency band. By optimizing the dielectric substrate material and the conductor width, the quality factor is controlled, so that the resonant characteristic is sensitive to minute capacitance changes. In some other embodiments, a parallel LC oscillation circuit can also be constructed on the circuit board 12 using a patch inductor and a capacitor element as the resonant circuit. The resonant frequency can be made to cover the preset operating frequency band by adjusting the ratio of the inductance to the capacitance. The inductor element can be a high-permeability winding structure, and the capacitor element can use a dielectric material with a low temperature drift coefficient. The probe 11 connection end (the second port) of the resonant circuit is connected to the probe 11 directly through gold wire bonding or a micro pad, and the signal output end (the third port) is connected to the signal amplifier processor through an impedance matching network.

[0033] Using the high-precision electrical parameter measurement structure provided by the embodiments of the present disclosure, the probe 11 can form an equivalent capacitance structure with the surface of the sample 22, and the capacitance value of the equivalent capacitance structure responds to the surface state of the sample 22. The circuit board 12 integrates a resonant circuit, and the resonant circuit is connected to the probe 11 to form a resonant loop with the equivalent capacitance structure, and the resonant characteristics of the resonant loop respond to the capacitance value of the equivalent capacitance structure. The probe 11 can form an equivalent capacitance structure with the surface of the sample 22, and the capacitance value of the equivalent capacitance structure responds to the surface state of the sample 22. The circuit board 12 integrates a resonant circuit, and the resonant circuit is connected to the probe 11 to form a resonant loop with the equivalent capacitance structure, and the resonant characteristics of the resonant loop respond to the capacitance value of the equivalent capacitance structure. By integrating the resonant circuit on the circuit board 12 and establishing a physical connection with the probe 11, the equivalent capacitance structure formed between the probe 11 and the surface of the sample 22 directly serves as a component of the resonant loop, without the need to connect the probe 11 and the resonant circuit by means of an independent signal line. Since the signal line transmission link is omitted, the energy loss generated during the signal transmission process can be effectively avoided, and at the same time, the parasitic capacitance of the transmission line to the measurement can be eliminated, thereby reducing the influence of the above factors on the test process and significantly improving the test sensitivity of the measurement structure to the change of the surface state of the sample 22.

[0034] Optionally, the measurement structure further includes a clamping structure 10. The clamping structure 10 can fix the probe 11, and at least a part of the circuit board 12 is located in the accommodation cavity 15 formed by the clamping structure 10 itself or together with the probe 11.

[0035] In the embodiments of the present disclosure, when the clamping structure 10 does not install the probe 11, at least a part of the circuit board 12 is located in the accommodation cavity 15 of the clamping structure 10 itself. When the clamping structure 10 installs the probe 11, at least a part of the circuit board 12 is located in the accommodation cavity 15 formed by the clamping structure 10 and the probe 11 together.

[0036] In this way, clamping the probe 11 by the clamping structure 10 can avoid the offset of the equivalent capacitance structure caused by the shaking of the probe 11 during the scanning process and ensure the accuracy of the capacitance value measurement. Moreover, arranging the circuit board 12 in the accommodation cavity 15 can isolate the resonant circuit area of the circuit board 12 from the external environment, thereby effectively blocking the influence of external environmental interference on the resonant loop and reducing the resonant characteristic fluctuation. Through the dual effects of mechanical fixation and electromagnetic shielding, the measurement error caused by the position offset of the probe 11 and the external environmental interference can be reduced, and the stability and sensitivity of the response of the measurement structure to the change of the surface state of the sample 22 are improved.

[0037] Optionally, at least a part of the clamping structure 10 forms an electrical shield between the circuit board 12 and the external environment.

[0038] In an embodiment of the present disclosure, the clamping structure 10 blocks the influence of electromagnetic interference in the external environment on the circuit board 12 by surrounding or covering at least a part of the area of the circuit board 12. The electrically shielding part of the clamping structure 10 can be electrically connected to the grounding end 31 of the circuit board 12 to form a complete electrically shielding loop. Alternatively, an independent grounding wire can also be provided for the electrically shielding part of the clamping structure 10 to form an electrically shielding loop.

[0039] In this way, by designing the clamping structure 10 to at least partially form an electrical shield between the circuit board 12 and the external environment, the influence of electromagnetic interference in the external environment on the resonant circuit on the circuit board 12, such as radio frequency signals, stray electromagnetic fields, etc., can be effectively blocked, and the resonant characteristics of the resonant loop, such as frequency, amplitude, etc., are prevented from fluctuating due to interference signals, so that the resonant loop can maintain a precise response to the minute changes in the equivalent capacitance structure formed by the probe 11 and the sample 22.

[0040] Optionally, the clamping structure 10 includes a base 13 and an elastic pressing piece 14. The first end 141 of the elastic pressing piece 14 is fixed to the surface of the base 13, and the second end 142 can apply a pressing force to the surface side of the base 13 under the action of elastic deformation to fix the probe 11 between the second end 142 and the base 13. Among them, the main body part 143 connecting the first end 141 and the second end 142 can enclose a receiving cavity 15 with the surface of the base 13.

[0041] In an embodiment of the present disclosure, the receiving cavity 15 can be a closed cavity or an incompletely closed cavity. For example, positioning holes or mounting holes can be provided in the main body part 143 of the elastic pressing piece 14, etc.

[0042] In this way, the first end 141 of the elastic pressing piece 14 is fixed to the surface of the base 13, and the second end 142 applies a pressing force to the base 13 through elastic deformation. The pressing force can be used to stably fix the probe 11 between the second end 142 and the base 13, so that the position deviation of the probe 11 caused by mechanical vibration or displacement during the scanning process can be effectively avoided. Moreover, the receiving cavity 15 formed by the enclosure of the main body part 143 connecting the two ends of the elastic pressing piece 14 and the surface of the base 13 can accommodate the circuit board 12 and its integrated resonant circuit, and a closed or semi-closed electrically shielding space is formed by using the part of the shielding material of the clamping structure 10 to block the influence of external electromagnetic interference on the resonant loop, reduce the resonant characteristic fluctuation, and the stable detection of the sub-attofarad-level capacitance change on the surface of the sample 22 can be realized. By combining the mechanical fixing function of the elastic pressing piece 14 and the electromagnetic shielding function of the receiving cavity 15, the measurement error caused by the loose fixing of the probe 11 and external interference is reduced, and the accuracy of the test result is improved.

[0043] Optionally, one end of the clamping structure 10 for fixing the probe 11 clamps the probe 11 and / or the circuit board 12.

[0044] In an embodiment of the present disclosure, the second end 142 of the clamping structure 10 clamps the probe 11, or the circuit board 12, or the probe 11 and the circuit board 12.

[0045] In an embodiment of the present disclosure, the probe 11 includes a fixing portion 32 and a tip 33. As Figure 1 shown, the circuit board 12 and the probe 11 can be vertically stacked and connected. At this time, the fixing portion 32 includes a first portion connected to the circuit board 12, a second portion extending out of the circuit board 12, and a cantilever connected to the second portion. The tip 33 is located on the cantilever. The first portion of the fixing portion 32 can be vertically fixed on the surface of the circuit board 12 by conductive adhesive or micro-solder joints. The second portion of the fixing portion 32 extends along the circuit board 12 away from the accommodating cavity 15. The output node of the resonant circuit of the circuit board 12 can be directly connected to the first portion of the fixing portion 32 through a metallized pad. As Figure 2 shown, the circuit board 12 and the probe 11 can also be horizontally extended and connected. The fixing portion 32 and the circuit board 12 are coplanar and can be horizontally connected by an embedded copper strip. A groove is opened at the edge of the circuit board 12, and the fixing portion 32 can be embedded in the groove. The resonant circuit node extends to the side wall of the groove to achieve direct connection.

[0046] In the embodiments of the present disclosure, the fixing manner of the probe 11 and the circuit board 12 can be determined according to the connection manner between the probe 11 and the circuit board 12. When the circuit board 12 and the probe 11 are vertically stacked and connected, the second end 142 can apply a pressing force to the surface side of the base 13 under the action of elastic deformation to fix the probe 11 and / or the circuit board 12 between the second end 142 and the base 13. Among them, when the probe 11 is not installed, the clamping structure 10 can clamp the circuit board 12 between the second end 142 and the surface of the base 13; when the probe 11 is installed, the clamping structure 10 can clamp the circuit board 12 and the probe 11 between the second end 142 and the surface of the base 13; when neither the probe 11 nor the circuit board 12 is clamped, the second end 142 can be in direct contact with the surface of the base 13 or a gap can be formed between the second end 142 and the surface of the base 13, and the height of the gap is less than the height of the fixing portion 32 or the height of the circuit board 12 or the sum of the heights of the fixing portion 32 and the circuit board 12. When the circuit board 12 and the probe 11 are horizontally extended and connected, the second end 142 can apply a pressing force to the surface side of the base 13 under the action of elastic deformation to fix the probe 11 or the circuit board 12 between the second end 142 and the base 13. Among them, when the clamping structure 10 neither clamps the probe 11 nor the circuit board 12, the second end 142 can be in direct contact with the surface of the base 13 or a gap can be formed between the second end 142 and the surface of the base 13, and the height of the gap is less than the height of the fixing portion 32 or the height of the circuit board 12; when the clamping structure 10 clamps the probe 11, the second end 142 of the elastic pressing piece 14 can directly press the fixing portion 32 on the surface of the base 13, and the circuit board 12 can be fixed in the accommodating cavity 15; when the clamping structure 10 clamps the circuit board 12, the second end 142 of the elastic pressing piece 14 only presses the circuit board 12 on the surface of the base 13, and the fixing portion 32 is embedded in the slot of the circuit board 12, and the probe 11 can be indirectly fixed by mechanical positioning.

[0047] In this way, by designing the clamping structure 10 to fix one end of the probe 11 and clamp the probe 11 and / or the circuit board 12 at the same time, the physical distance between the probe 11 and the circuit board 12 can be shortened through the integrated clamping method, avoiding the transmission loss and parasitic capacitance introduced by the long signal line in the separated connection, so as to ensure that the equivalent capacitance structure formed by the probe 11 and the sample 22 is directly connected to the resonant circuit, improving the capacitance detection sensitivity. Moreover, the clamping structure 10 can wrap the connection end of the probe 11 and the circuit board 12 together in the shielding space to form a continuous electrical shielding circuit, blocking the influence of external electromagnetic interference on the resonant circuit and maintaining the stability of the resonant characteristics. By integrating the clamping to eliminate the transmission loss and interference of the separated connection, while ensuring that the cantilever and the tip 33 of the probe 11 are exposed to contact the sample 22, the accurate detection of sub-attofarad-level capacitance sensitivity can be realized through the protection of the shielding space for the core circuit.

[0048] Optionally, the measurement structure further includes a shielding structure 16. The shielding structure 16 at least partially covers the resonant circuit region of the circuit board 12 to form an electrical shield between the resonant circuit and the external environment.

[0049] In an embodiment of the present disclosure, the shielding structure 16 can be electrically connected to the ground terminal 31 of the circuit board 12 to form a complete electrical shielding loop. Alternatively, an independent ground wire can be provided for the shielding structure 16 to form an electrical shielding loop. As Figure 3 and Figure 4 shown, the shielding structure 16 can be disposed inside the accommodation cavity 15 or outside the accommodation cavity 15. The shielding structure 16 can completely cover the resonant circuit region of the circuit board 12 and / or the physical connection position between the probe 11 and the circuit board 12. It can also only partially cover the resonant circuit region of the circuit board 12 and / or the physical connection position between the probe 11 and the circuit board 12.

[0050] In this way, by providing an independent shielding structure 16 to at least partially cover the resonant circuit region of the circuit board 12 to form a closed or semi-closed electrical shielding space in addition to the clamping structure 10, the influence of electromagnetic interference in the external environment on the resonant circuit can be effectively blocked, thereby avoiding fluctuations in the resonant characteristics of the resonant loop caused by interference signals and providing additional electrical shielding protection for the test.

[0051] Optionally, when the tip of the probe 11 contacts the sample 22, at least a metal-oxide-semiconductor structure form is formed to form an equivalent capacitance structure.

[0052] In the embodiments of the present disclosure, when the probe 11 (metal tip 33) contacts the silicon-based semiconductor sample 22, the natural oxide layer (such as SiO2) on the surface of the sample 22 serves as an insulating medium and can jointly form a MOS capacitor structure with the metal probe 11 and the semiconductor substrate. Without the need to prepare an additional insulating layer, it can be applied to detect semiconductor materials that are prone to natural oxidation, such as conventional silicon wafers and gallium arsenide. When testing compound semiconductors (such as GaN) or metal electrodes, an artificial dielectric layer (such as Al2O3, HfO2) can be pre-deposited on the surface of the sample 22, and then a controllable MOS structure can be formed by contacting with the probe 11. It can be applied to materials with low oxidation activity, and the dielectric layer can enhance the sensitivity to changes in interface states. The metal-oxide-semiconductor structure is composed of a metal layer 17, an oxide layer 18, and a semiconductor layer 19 in sequence. Among them, the metal layer 17 refers to the conductive tip 33 of the probe 11 (such as a platinum-iridium alloy coating, a doped diamond tip 33), which can serve as the upper electrode of the MOS capacitor, directly contact the dielectric layer, and apply a bias voltage. The semiconductor layer 19 can refer to the substrate material of the sample 22 to be measured (such as silicon, GaAs, silicon carbide wafer). The oxide layer 18 refers to the insulating dielectric layer on the surface of the sample 22, including the natural oxide layer and the artificially deposited layer. The natural oxide layer can be SiO2 formed by exposing the silicon wafer to air; the artificially deposited layer can be Al2O3 / HfO2 deposited by atomic layer deposition (ALD).

[0053] In this way, by forming a metal-oxide-semiconductor structural form when the tip of the probe 11 contacts the sample 22, an equivalent capacitance structure responsive to the surface state of the sample 22 can be constructed. In the equivalent capacitance structure, the oxide layer 18 between the metal probe 11 and the semiconductor sample 22 forms a dielectric medium, such as a natural oxide layer or an artificially prepared insulating layer, etc., thereby generating a capacitance effect directly related to the doping concentration and type of the sample 22 between the probe 11 and the sample 22. When the doping characteristics on the surface of the sample 22 change, such as the carrier concentration and impurity type change, the capacitance value of the equivalent capacitance structure will change accordingly, and directly modulate the resonant characteristics of the resonant circuit of the circuit board 12 that forms a resonant circuit with it, such as the resonant frequency, amplitude, etc. Utilizing the correlation between the capacitance characteristics of the metal-oxide-semiconductor structure and the electrical parameters of the sample 22, through the highly sensitive response of the resonant circuit, precise detection of the nanoscale doping concentration and type on the surface of the sample 22 is achieved, providing a reliable physical basis for the high-resolution characterization of semiconductor materials.

[0054] Optionally, the measurement structure further includes a bias voltage module 30. The bias voltage module 30 is used to apply a DC and / or AC bias voltage to the sample 22 and / or the probe 11.

[0055] In an embodiment of the present disclosure, the bias voltage module 30 can apply an adjustable DC bias voltage to the semiconductor sample 22 through a DC voltage source. When a negative DC bias voltage is applied to the p-type semiconductor, the hole concentration on the surface of the semiconductor sample 22 increases, resulting in a contraction of the depletion layer width, an increase in the depletion layer capacitance, and thus an increase in the total equivalent capacitance value. When a positive DC bias voltage is applied, a depletion region is formed on the semiconductor surface, resulting in an expansion of the depletion layer width, a decrease in the depletion layer capacitance, and thus a decrease in the total equivalent capacitance value. By scanning the DC bias voltage and monitoring the resonance frequency shift, a capacitance-voltage characteristic curve is generated, and the difference in the turning voltages in this curve can be used to distinguish the semiconductor doping type (such as n-type or p-type) and quantitatively calculate the doping concentration.

[0056] In an embodiment of the present disclosure, the bias voltage module 30 can output a DC bias voltage and an AC bias voltage (such as a high-frequency AC small signal) simultaneously. The DC bias voltage sets the static operating point to fix the basic capacitance value; the AC bias voltage (whose frequency matches the operating frequency band of the resonance circuit) can be superimposed on the DC bias voltage to form a composite excitation signal. The AC bias voltage generates a small capacitance change on the equivalent capacitance structure, and this change amount is proportional to the slope of the capacitance-voltage curve and the amplitude of the AC voltage. This small capacitance change can modulate the amplitude and phase of the resonance circuit, and the modulated AC signal is extracted by the phase-locked amplifier 27. The phase-locked amplifier 27 can improve the signal-to-noise ratio of the weak capacitance change signal, thereby achieving sub-attofarad-level capacitance resolution.

[0057] In this way, by setting the bias voltage module 30 to apply a DC bias voltage and an AC bias voltage to the sample 22 and / or the probe 11, multi-dimensional electrical parameter detection can be realized based on the capacitance characteristics of the metal-oxide-semiconductor structure. The DC bias voltage is used to adjust the depletion layer state on the surface of the sample 22 and change the basic capacitance value of the equivalent capacitance structure, while the AC bias voltage, such as a radio frequency signal within a preset range, excites the resonance circuit and modulates the resonance characteristics, such as frequency shift, amplitude change, etc., through capacitance changes. By enabling samples 22 with different doping concentrations and types to present their capacitance and voltage response curves under the action of the bias voltage, and by extracting the amplitude and phase information of the response signal through the phase-locked amplifier 27, where the amplitude change reflects the doping concentration of the semiconductor device and the phase change reflects the doping type, high-resolution characterization of the carrier distribution of semiconductor materials at the nanoscale can be achieved. The introduction of the bias voltage module 30 not only endows the measurement structure with the ability to adjust the equivalent capacitance operating point, but also enhances the response sensitivity of the resonance circuit to changes in the surface state of the sample 22 through the synergistic effect of the AC and DC biases, providing precisely controllable excitation conditions for obtaining multi-dimensional parameters such as the morphology, doping concentration, and type of the sample 22. Thus, it is ensured that the measurement structure can adapt to the detection requirements of different semiconductor materials and device structures.

[0058] An embodiment of the present disclosure provides a high-precision electrical parameter measurement method, which is applied to the high-precision electrical parameter measurement structure of any one of the above. Any one of the following methods can be executed in a scanning probe microscope, or can be executed in a server or a terminal device communicatively connected to the scanning probe microscope.

[0059] The measurement method includes: forming an equivalent capacitance structure between the probe 11 and the sample 22; wherein, the equivalent capacitance structure and the resonant circuit on the circuit board 12 form a resonant loop. Making the resonant loop in a preset resonant working state. Applying an electrical excitation signal to the probe 11 and / or the sample 22 to obtain a response signal; wherein, the electrical excitation signal includes a DC bias voltage and / or an AC bias voltage. Collecting and processing the response signal to obtain the signal characteristic parameters of the response signal.

[0060] By using the high-precision electrical parameter measurement method provided by the embodiment of the present disclosure, by forming an equivalent capacitance structure between the probe 11 and the sample 22 and forming a resonant loop by directly integrating the equivalent capacitance structure with the resonant circuit on the circuit board 12, the energy loss and parasitic capacitance interference caused by the transmission of independent signal lines are eliminated, thereby improving the capacitance detection sensitivity. And, by making the resonant loop work in a preset resonant working state and using the amplification effect of the resonant characteristic on the capacitance change, the weak change of the surface state of the sample 22 can be converted into a detectable resonant characteristic offset, such as converting the doping concentration and / or doping type into frequency and / or amplitude changes, etc. Then, by applying a DC bias voltage to the probe 11 and / or the sample 22, the nonlinear C-V characteristic of the equivalent capacitance structure is used to distinguish different doping parameters. Finally, by collecting the response signal and using a lock-in amplifier 27 and other processing to extract the signal characteristic parameters, such as amplitude and / or phase, etc., the amplitude is associated with the doping concentration and the phase is associated with the doping type, so as to realize high-resolution imaging of the morphology and electrical parameters of the sample 22 at the nanoscale.

[0061] Optionally, the measurement method further includes: controlling the measurement structure to scan the sample 22 along a preset path; wherein, an equivalent capacitance structure is formed at at least part of the positions on the preset path. Recording the spatial position information of the scanning point and / or the height information of the sample 22 and / or the signal characteristic parameters of the response signal. At least for generating the morphology and / or doping concentration and / or doping type of the sample 22 according to the spatial position information of the scanning point and / or the height information of the sample 22 and / or the signal characteristic parameters of the response signal.

[0062] In this way, by controlling the measurement structure to scan the sample 22 along a preset path, an equivalent capacitance structure is formed at the scanning point position, and the spatial position, the height of the sample 22, and the characteristic parameters of the response signal are synchronously recorded, realizing the precise spatial correlation between the topography and the electrical parameters. Based on the spatial position, a scanning reference coordinate system is constructed. The height of the sample 22 directly generates the topography of the sample 22. At the same time, the two-dimensional doping distribution map is generated by using the signal characteristic parameters in combination with the calibration model, so as to synchronously obtain the topography, doping concentration, and doping type of the sample 22 in a single scan.

[0063] In the actual application process, such as Figure 5 and Figure 6As shown, the controller 28 is respectively connected to the detector 21, the radio frequency source 29, the signal processor and the displacement stage 23. The sample 22 is arranged on the displacement stage 23, and the sample 22 can be connected to the bias voltage module 30. The clamping structure 10 and / or the shielding structure 16 are made of shielding material and are connected to the ground terminal 31 to form a shielding loop. Among them, the distance between the ground terminal 31 and the clamping structure 10 is less than the distance between the circuit board 12 and the ground terminal 31. The third port of the circuit board 12 in the accommodation cavity 15 formed by the clamping structure 10 is sequentially connected to the signal amplifier 24, the detector 25, the high-pass filter 26 and the controller 28. The first port of the circuit board 12 is sequentially connected to the radio frequency source 29 and the controller 28. The second port of the circuit board 12 is connected to the probe 11. Specifically, the probe 11 can be approximated to the surface of the sample 22. By maintaining the signal of the detector 21 constant, the probe 11 is kept in a constant contact state with the sample 22 to form a metal-oxide-semiconductor equivalent capacitance structure. Among them, during the test, the detection light emitted by the light source 20 (such as a laser, etc.) is reflected by the probe 11 cantilever and irradiated on the detector 21 (such as a PSD or a quadrant detector, etc.). At this time, it is necessary to detect the signal of the detector 21 in real time, and by controlling the displacement of the displacement stage 23 along the Z axis to maintain the signal of the detector 21 constant, so as to keep the contact state between the probe 11 and the sample 22 and the deflection of the probe 11 cantilever constant, thereby eliminating the influence of the sample 22 morphology change on the response signal. During this process, the height of the sample 22 can be obtained, that is, the morphology of the sample 22, namely the height of the sample 22, is obtained by maintaining the signal of the detector 21 constant through closed-loop feedback. Then, the radio frequency source 29 can be used to perform a frequency sweep operation on the resonant circuit including the equivalent capacitance structure within a preset frequency range to obtain a frequency sweep curve, and the drive frequency of the resonant circuit is determined according to the frequency sweep curve, so that the resonant circuit is in a preset resonant working state matching the equivalent capacitance structure. Then, a DC bias voltage and an AC bias voltage are applied to the probe 11 and / or the sample 22, and the resonant characteristics of the resonant circuit are modulated through the equivalent capacitance structure, so that the resonant circuit generates a response signal, and the amplitude and phase information of the response signal are extracted through a signal processor (such as a lock-in amplifier 27). Among them, the response signal can characterize the capacitance value change of the equivalent capacitance structure, the amplitude reflects the doping concentration of the sample 22, and the phase reflects the doping type. Then, the controller 28 controls the displacement stage 23 to scan according to a preset path, and synchronously records the coordinates of the scan points and / or the height of the sample 22 and / or the amplitude and phase of the response signal. Among them, the change in the amplitude and phase of the response signal corresponds to the real-time change of the equivalent capacitance structure with the surface state of the sample 22. Finally, the amplitude and / or phase of the response signal are correspondingly converted into the doping concentration and / or doping type of the sample 22 through a calibration model, and a two-dimensional doping concentration image and a two-dimensional doping type image are generated in combination with the displacement signal of the scan points, and a morphology image of the sample 22 is generated through the height of the sample 22.In addition, the controller 28 can also be connected to a displacement sensor. During the process that the controller 28 controls the displacement stage 23 to perform a scanning operation, the position of the displacement stage 23 can be calibrated in real time in combination with the displacement sensor to eliminate temperature drift and hysteresis errors. The controller 28 integrates a field programmable gate array (FPGA), a high-performance analog-to-digital converter (ADC), and a digital-to-analog converter (DAC) chip, and is used to collect the response signals of the resonant circuit in real time; filter, amplify, and perform phase-locked processing on the response signals through a signal processor; generate control signals to drive the displacement stage 23 to scan along a preset path; communicate with the host computer and transmit the collected signal data and scanning coordinate information.

[0064] An embodiment of the present disclosure provides a scanning probe microscope, and the scanning probe microscope includes the high-precision electrical parameter measurement structure of any one of the above.

[0065] The above description and the drawings fully illustrate the embodiments of the present disclosure so that those skilled in the art can practice them. Other embodiments may include structural and other changes. The embodiments only represent possible variations. Unless explicitly required, the individual components and functions are optional, and the order of operations can vary. Parts and features of some embodiments can be included in or replaced by parts and features of other embodiments. The embodiments of the present disclosure are not limited to the structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.

Claims

1. A high-precision electrical parameter measurement structure, characterized in that, Applied at least to a scanning probe microscope; the measurement structure includes: A probe that can form an equivalent capacitance structure with the surface of a sample; wherein, the capacitance value of the equivalent capacitance structure responds to the surface state of the sample. A circuit board integrating a resonant circuit, the resonant circuit is connected to the probe to form a resonant loop with the equivalent capacitance structure; wherein, the resonant characteristics of the resonant loop respond to the capacitance value of the equivalent capacitance structure.

2. The structure according to claim 1, characterized in that, It further includes: A clamping structure that can fix the probe, and at least part of the circuit board is located in a receiving cavity formed by the clamping structure itself or together with the probe.

3. The structure according to claim 2, wherein The clamping structure at least partially forms an electrical shield between the circuit board and the external environment.

4. The structure according to claim 2, wherein The clamping structure includes: A base; A resilient pressing piece, the first end is fixed to the surface of the base, and the second end can apply a pressing force to the side of the base surface under the action of elastic deformation to fix the probe between the second end and the base. Wherein, the main body part connecting the first end and the second end can enclose a receiving cavity with the surface of the base.

5. The structure according to claim 2, wherein One end of the clamping structure for fixing the probe clamps the probe and / or the circuit board.

6. The structure according to any one of claims 1 to 5, characterized in that, It further includes: A shielding structure that at least partially covers the resonant circuit area of the circuit board to form an electrical shield between the resonant circuit and the external environment.

7. The structure according to any one of claims 1 to 5, wherein When the probe tip contacts the sample, at least a structural form of metal, oxide, or semiconductor is formed to form an equivalent capacitance structure.

8. The structure according to any one of claims 1 to 5, characterized in that, It further includes: A bias voltage module for applying a DC and / or AC bias voltage to the sample and / or the probe.

9. A high-precision electrical parameter measurement method, characterized in that, Applied to the high-precision electrical parameter measurement structure according to any one of claims 1-8; the method includes: Making the probe and the sample form an equivalent capacitance structure; wherein, the equivalent capacitance structure and the resonant circuit on the circuit board form a resonant loop. Making the resonant loop be in a preset resonant operating state. Applying an electrical excitation signal to the probe and / or the sample to obtain a response signal; wherein, the electrical excitation signal includes a DC bias voltage and / or an AC bias voltage. Collecting and processing the response signal to obtain the signal characteristic parameters of the response signal.

10. The method according to claim 9, wherein It further includes: Controlling the measurement structure to scan the sample along a preset path; wherein, an equivalent capacitance structure is formed at at least part of the positions on the preset path. Recording the spatial position information of the scanning points and / or the sample height information and / or the signal characteristic parameters of the response signal. According to the spatial position information of the scanning points and / or the sample height information and / or the signal characteristic parameters of the response signal, at least used to generate the topography and / or doping concentration and / or doping type of the sample.

11. A scanning probe microscope, characterized in that, Including the high-precision electrical parameter measurement structure according to any one of claims 1 to 8.

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