CN-121995084-A - Microwave atomic force microscope probe based on coplanar waveguide structure and preparation method

CN121995084ACN 121995084 ACN121995084 ACN 121995084ACN-121995084-A

Abstract

The invention discloses a microwave atomic force microscope probe based on a coplanar waveguide structure and a preparation method thereof, belonging to the field of micro-nano detection and atomic force microscope. The probe comprises a clamping part and a cantilever beam, wherein central conductors are paved on the axes of the upper surfaces of the clamping part and the cantilever beam, grounding metal layers are symmetrically arranged on two sides of the central conductor at intervals, the grounding metal layers are parallel to the central conductor and have equal lengths, gaps among the central conductor, the grounding metal layers and the central conductor and the grounding metal layers form a coplanar waveguide structure of the clamping part, the central conductor and the grounding metal layers of the clamping part are respectively connected with the central conductor and the grounding metal layers of the cantilever beam to form a microwave transmission circuit, and the microwave transmission circuit is converted into a coaxial transmission line structure at a needle point to transmit microwave signals to the needle point, so that the transmission and the reception of near-field microwave signals are realized. The invention has flexible design and easy integration, is beneficial to the transmission of microwave signals with low loss and low dispersion, reduces the complexity and the manufacturing cost of probe design, and provides effective support for micro-nano detection and atomic force microscope technology.

Inventors

JU YANG
MA TONG
XU CHENQIAN
YIN HAILONG

Assignees

浙江大学

Dates

Publication Date: 20260508
Application Date: 20260408

Claims (10)

1. The microwave atomic force microscope probe based on the coplanar waveguide structure is characterized by comprising a clamping part and a cantilever beam; the clamping part is of a flat rectangular structure and comprises a substrate and a coplanar waveguide structure arranged on the upper surface of the substrate; The cantilever beam is in an elongated rectangular shape, and the upper surface of the cantilever beam is provided with a coplanar waveguide structure; The microwave transmission circuit comprises a clamping part, a cantilever beam, a central conductor, a metal grounding layer, a strip-shaped conduction band, a coplanar waveguide structure, a microwave transmission circuit and a microwave transmission circuit, wherein the central conductor is paved on the axes of the upper surfaces of the clamping part and the cantilever beam, the metal grounding layer is symmetrically arranged on two sides of the central conductor, and a gap is reserved between the metal grounding layer and the central conductor; The free end of the cantilever beam is provided with a raised needle point, the microwave transmission circuit is converted into a coaxial transmission line structure arranged on the surface of the needle point at the needle point, the coaxial transmission line structure is sequentially provided with an inner conductor, an intermediate layer and an outer conductor from inside to outside, the inner conductor is connected with a central conductor on the cantilever beam, and the outer conductor is connected with a metal grounding layer on the cantilever beam.
2. The probe of claim 1, wherein to achieve impedance matching for 75-110GHz microwave transmission, a width of the center conductor at the rear end of the clamping portion ranges from 320 to 440 μm, a width of the metal ground layer at the rear end of the clamping portion ranges from 440 to 480 μm, and a width of a gap between the center conductor at the rear end of the clamping portion and the metal ground layer ranges from 50 to 150 μm.
3. The probe of claim 1, wherein to achieve impedance matching for 75-110GHz microwave transmission, the width of the center conductor of the cantilever is in the range of 5-15 μm, the width of the metal ground layer of the cantilever is in the range of 8-12 μm, the width of the gap between the center conductor of the cantilever and the metal ground layer is 3-8 μm, and the coplanar waveguide structure at the front end of the clamping part is kept consistent with the size of the cantilever.
4. The probe of claim 1, wherein the coplanar waveguide structure at the rear end of the clamping portion comprises a rear end center conductor and two rear end metal ground layers, the rear end center conductor being laid along the axis of the rear end of the clamping portion, the two rear end metal ground layers being symmetrically laid on both sides of the rear end center conductor, the two rear end metal ground layers being parallel to and equal in length to the rear end center conductor, and a gap being provided between the two rear end metal ground layers and the rear end center conductor.
5. The probe of claim 1, wherein the back end of the clamping portion is further provided with an impedance match line, the impedance match line tapering back-to-front to form an impedance transition, and the coplanar waveguide structure of the back end of the clamping portion tapers along the impedance transition.
6. The probe of claim 1, wherein the coplanar waveguide structure on the cantilever beam comprises a cantilever beam center conductor and two cantilever beam metal ground layers, wherein the axis of the cantilever beam center conductor coincides with the axis of the cantilever beam, the two cantilever beam metal ground layers are symmetrically laid on two sides of the cantilever beam center conductor, the two cantilever beam metal ground layers are parallel to and equal in length to the cantilever beam center conductor, and a gap is formed between the two cantilever beam metal ground layers and the cantilever beam center conductor.
7. The probe according to claim 1, wherein the coplanar waveguide structure of the front end of the clamping part comprises a front end central conductor and two front end metal grounding layers, the axis of the front end central conductor is coincident with the axis of the front end of the clamping part, the two front end metal grounding layers are symmetrically laid on two sides of the front end central conductor, the two front end metal grounding layers are parallel to the front end central conductor and have equal length, and a gap is formed between the two front end metal grounding layers and the front end central conductor.
8. The probe of claim 1, wherein the free end of the cantilever beam has a triangular configuration and the tip has a pyramid configuration.
9. A method for preparing a microwave atomic force microscope probe based on a coplanar waveguide structure, which is used for preparing the microwave atomic force microscope probe based on the coplanar waveguide structure as set forth in claim 5, and is characterized by comprising the following steps: Step S1, establishing an electromagnetic simulation model of a microwave atomic force microscope probe based on a coplanar waveguide structure, performing simulation analysis, deriving characteristic impedance and scattering matrix data of a microwave transmission circuit on the upper surface of the probe, and obtaining all dimensional parameters of the coplanar waveguide structure meeting the characteristic impedance requirements according to a microwave target working frequency band; S2, cleaning the probe substrate, performing surface modification, and then performing HMDS surface pretreatment and maintaining for 30-50min; Step S3, coating photoresist on the upper surface of the probe, removing redundant photoresist on the upper surface of the probe after the photoresist is dripped for 10-14S, and drying the probe for 220-260S after the photoresist is spun, so that the photoresist is shaped; S4, performing first exposure and development on the probe, manufacturing a central conductor pattern and an inner conductor structure of a needle point on the probe, forming a gold film on the central conductor through an electron beam evaporation process, and stripping the redundant gold film to form the central conductor; S5, wrapping the tail end of the needle point by using tinfoil, reserving the position of an outer conductor structure of the needle point, and growing a silicon dioxide isolation layer on the upper surface of the probe through plasma chemical vapor deposition; And S6, repeating the step S3, performing secondary exposure development on the probe, manufacturing a metal grounding layer pattern and an outer conductor structure of the needle point on the probe, forming a metal grounding layer gold film through an electron beam evaporation process, and forming a metal grounding layer after removing the redundant gold film to finish the preparation.
10. The method of manufacturing as claimed in claim 9, wherein the dimensional parameters of the coplanar waveguide structure in step S1 include widths of the central conductor and the metal ground layer, widths of gaps between the central conductor and the metal ground layer, thicknesses of the central conductor, the metal ground layer, and the impedance match line.

Description

Microwave atomic force microscope probe based on coplanar waveguide structure and preparation method Technical Field The invention belongs to the field of micro-nano measurement and atomic force microscopy, and provides a microwave atomic force microscopy probe based on a coplanar waveguide structure and a preparation method thereof. Background An atomic force microscope (Atomic Force Microscope, AFM) is a high resolution microscopy technique that utilizes the interaction force between a microcantilever probe of a nanoscale needle tip and atoms on the surface of a sample to characterize the surface morphology and physicochemical properties of the material. The working modes of the probe are mainly divided into a contact type, a tapping type and a non-contact type according to the interaction modes of the probe and the sample. In order to realize the characterization of the microwave morphology of the sample and the measurement of the local electrical property, a microwave atomic force microscope (Microwave Atomic Force Microscope, M-AFM) is developed, and the microwave detection is combined with the atomic force microscope, so that the simultaneous acquisition of the morphology and the local electrical property of the sample under the nanoscale is realized by utilizing the interaction of near-field microwaves and the sample. Most of the existing probes for the microwave atomic force microscope adopt a parallel plate waveguide structure to transmit microwaves, however, the characteristic impedance of the transmission mode can only be designed by adjusting the thickness of a probe substrate, and the design flexibility is limited. In addition, in the high-frequency microwave transmission process, the loss of the parallel plate waveguide is high, and the measurement accuracy and the signal transmission efficiency of the probe are affected. In addition, in terms of manufacturing process, the preparation of the microwave atomic force microscope probe generally adopts a self-wafer processing method, which comprises etching, photoetching, coating, releasing and other processes. Although the method can realize batch production, the method has the problems of long preparation period, complex process, low success rate and the like. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a preparation method of a microwave atomic force microscope probe based on a coplanar waveguide structure, which aims to overcome the defect of low success rate of manufacturing the microwave atomic force microscope probe. Therefore, the invention provides a probe preparation method based on microwave transmission channel construction. The core of the probe is that a coplanar waveguide (Coplanar Waveguide, CPW) transmission line is integrated on the probe structure, the structure is extended to a needle point area along a cantilever beam so as to be converted into a coaxial transmission line structure, the advantages of low loss, flexible design and the like of the coplanar waveguide under a high-frequency condition are fully utilized, and the integrated integration of microwave transmission and the probe structure is realized, so that a brand new probe design scheme is provided. In order to achieve the above object, a first aspect of the present invention discloses a microwave atomic force microscope probe based on a coplanar waveguide structure, which comprises a clamping part and a cantilever beam; the clamping part is of a flat rectangular structure and comprises a substrate and a coplanar waveguide structure arranged on the upper surface of the substrate; The cantilever beam is in an elongated rectangular shape, and the upper surface of the cantilever beam is provided with a coplanar waveguide structure; The microwave transmission circuit comprises a clamping part, a cantilever beam, a central conductor, a metal grounding layer, a strip-shaped conduction band, a coplanar waveguide structure, a microwave transmission circuit and a microwave transmission circuit, wherein the central conductor is paved on the axes of the upper surfaces of the clamping part and the cantilever beam, the metal grounding layer is symmetrically arranged on two sides of the central conductor, and a gap is reserved between the metal grounding layer and the central conductor; The free end of the cantilever beam is provided with a raised needle point, the microwave transmission circuit is converted into a coaxial transmission line structure arranged on the surface of the needle point at the needle point, the coaxial transmission line structure is sequentially provided with an inner conductor, an intermediate layer and an outer conductor from inside to outside, the inner conductor is connected with a central conductor on the cantilever beam, and the outer conductor is connected with a metal grounding layer on the cantilever beam. Preferably, in order to achieve impedance matching for 75-110GHz microwave transmission, the width of