Terahertz broadband high-sensitivity sensor chip based on local field enhancement and its manufacturing method

Abstract

The present invention provides a terahertz broadband high-sensitivity sensor chip based on local field enhancement and a manufacturing method thereof, which includes a Vivaldi antenna, an artificial surface plasmon waveguide with a metal groove structure, a terahertz wave is input through an input end waveguide, and the Vivaldi antenna at one end couples the terahertz wave to the artificial surface plasmon waveguide, and the terahertz wave is transmitted in the waveguide under the constraint of the artificial surface plasmon waveguide, and the terahertz wave on the waveguide is coupled back to the free space by the Vivaldi antenna at the other end and is received by the terahertz detector; a circular metal area is provided at the inner edge of the artificial surface plasmon waveguide to increase the effective working bandwidth of the sensor chip. The present invention has high sensing sensitivity and high effective working bandwidth, can reduce reflection, and improve coupling efficiency, thereby solving the resonance peak generated by the metamaterial sensor due to its special structural design, has a simple preparation process, and has low equipment price, and can be applied on a large scale.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a terahertz broadband high-sensitivity sensor chip based on local field enhancement and a method for manufacturing the sensor chip. Background Art

[0002] Terahertz waves at special spectral positions are not only in a special transition region from the electronic band to the optical band, but are also compatible with both classical macroscopic and microscopic quantum theories. Such special electromagnetic properties give it the advantages of low photon energy, wide bandwidth, and good penetration into many non-polar materials. In addition, basic physical processes such as rotational transitions and vibrational transitions of biological or chemical molecules, lattice vibrations of solids, intra-band transitions of semiconductor materials, and even energy band transitions of superconductors are all related to the terahertz characteristic spectra of these materials, which makes the study of the terahertz characteristic spectra of material materials of great academic significance and practical application prospects.

[0003] However, the wavelength of terahertz waves is relatively large, so the smallest terahertz spot after focusing the test light path is also in the millimeter range under the limitation of diffraction limit. The traditional free-space terahertz time-domain spectroscopy detection technology is to irradiate the focused terahertz waves onto the target material. After interacting with the target material, the terahertz waves will be received by the detector to obtain the corresponding spectral information of the target material. When using traditional terahertz spectroscopy technology to detect thin materials, it is often impossible to extract the spectral information of the target material because the interaction strength between the terahertz wave and the target material is not strong enough or even no interaction occurs at all.

[0004] At present, terahertz metamaterial sensing technology has proposed a new idea for the sensing and detection of trace substances by terahertz time-domain spectroscopy technology. The effective dielectric constant and permeability of metamaterials can be adjusted by artificially designing structures that natural materials do not have. This outstanding feature enables terahertz sensing to surpass the physical properties of natural materials with high spatial constraints and break through the diffraction limit.

[0005] However, the metamaterial structure itself leads to poor stability of the technology and limited sensing targets. On the one hand, the structure used in metamaterial sensing technology is complex and small in size, so the stability of metamaterial preparation will affect the stability and repeatability of the sensor to a certain extent. On the other hand, due to its special structural design, metamaterial sensors usually have a resonance peak at a specific frequency point, and this sensing technology can usually only analyze the target material based on the changes in the resonance absorption peak.

[0006] In order to give full play to the advantages of the wide bandwidth of terahertz waves and realize the sensing detection of trace substances under wide bandwidth conditions, researchers have proposed a sensing detection technology based on on-chip enhancement. Terahertz on-chip enhanced sensing technology is a high-sensitivity sensing technology that uses artificial surface plasmon waveguides to constrain terahertz waves to enhance the degree of interaction between them and target substances. In the terahertz on-chip enhanced sensing system, the terahertz wave is constrained in a sub-wavelength range on the surface of the artificial surface plasmon waveguide that is much smaller than the diffraction limit. Therefore, the electric field intensity in this area is greatly enhanced, and the degree of interaction between the terahertz wave and the target substance is also stronger, which can realize the sensing detection of trace substances.

[0007] However, due to the lack of more efficient confinement of terahertz waves in the on-chip system, the interaction between terahertz waves and target materials is weak, resulting in low sensing sensitivity of the on-chip system. In addition, most of the on-chip systems reported so far use low-temperature grown gallium arsenide (LT-GaAs) as a photoconductive switch. This material has an extremely low carrier lifetime and extremely high photoconductivity, making it an ideal material for making ultrafast photoconductive switches. However, the cumbersome preparation process behind this material and the high equipment price indirectly raise the research threshold of terahertz on-chip enhanced sensing systems, and also hinder the development of portable sensing detection of this technology to a certain extent.

[0008] Metal waveguide is one of the most common waveguides in terahertz on-chip enhanced sensing technology. One of the solutions is microstrip line, which can play a certain role in constraining terahertz waves while transmitting them. This solution detects the target material by using the evanescent field generated when terahertz waves are transmitted on the microstrip line.

[0009] However, the coupling method of traditional terahertz artificial surface plasmon enhanced sensing has problems such as low integration, low coupling efficiency, and small working bandwidth, which limits the development of the corresponding terahertz sensing technology.

[0010] Therefore, the shortcomings of the prior art are:

[0011] (1) The sensing sensitivity of the sensor chip to trace substances needs to be improved;

[0012] (2) The effective working bandwidth of sensor chips needs to be improved;

[0013] (3) The coupling efficiency needs to be improved;

[0014] (4) Metamaterial sensors usually have a resonance peak at a specific frequency due to their special structural design;

[0015] (5) The preparation process is complicated and the equipment is expensive. Summary of the invention

[0016] In order to solve the above problems existing in the prior art, the purpose of the present invention is to provide a terahertz broadband high-sensitivity sensor chip and method based on local field enhancement, which can improve the sensing sensitivity of the sensor chip to trace substances, increase the effective working bandwidth of the sensor chip, reduce reflection, improve coupling efficiency, solve the resonance peak generated by the special structural design of the metamaterial sensor, simplify the preparation process, reduce the equipment price, and enable it to be applied on a large scale.

[0017] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0018] A terahertz broadband high-sensitivity sensor chip based on local field enhancement, comprising:

[0019] An input port, an output port, a Vivaldi antenna, and an artificial surface plasmon waveguide with a metal groove structure. The terahertz wave is input through the input port, and sequentially passes through the Vivaldi antenna, the artificial surface plasmon waveguide, another Vivaldi antenna, and then reaches the output port. The Vivaldi antenna at the input end couples the terahertz wave in the free space to the artificial surface plasmon waveguide. Then, the terahertz wave is transmitted in the waveguide under the constraint of the artificial surface plasmon waveguide. The terahertz wave on the waveguide is coupled back to the free space by the Vivaldi antenna at the output end and is received by the terahertz detector.

[0020] A circular metal area is arranged at the inner edge of the artificial surface plasmon waveguide to improve the effective working bandwidth of the sensor chip.

[0021] A terahertz broadband high-sensitivity sensor chip based on local field enhancement provided by the present invention also includes a substrate, and the Vivaldi antenna and the artificial surface plasmon waveguide are both arranged on the substrate.

[0022] According to a terahertz broadband high-sensitivity sensor chip based on local field enhancement provided by the present invention, the substrate is an insulating dielectric film.

[0023] According to a terahertz broadband high-sensitivity sensor chip based on local field enhancement provided by the present invention, the structure of the Vivaldi antenna is a gradual transition from a narrower transmission slot line to a wider transmission slot line, and the transmission slot line changes exponentially, and the formed trumpet-mouth structure can radiate outward or receive electromagnetic waves inward.

[0024] According to a terahertz broadband high-sensitivity sensor chip based on local field enhancement provided by the present invention, the artificial surface plasmon waveguide includes a right-angle bent slot line waveguide, and the right-angle bent slot line waveguide is connected to the two ends of the Vivaldi antenna, so that the electric field polarization directions of the terahertz signal are orthogonal to each other at the input end and the output end.

[0025] According to a terahertz broadband high-sensitivity sensor chip based on local field enhancement provided by the present invention, the right-angle bent slot waveguide is a deep sub-wavelength slot line with a gradually narrowing middle part, and its two end parts are smooth line designs.

[0026] According to a terahertz broadband high-sensitivity sensor chip based on local field enhancement provided by the present invention, the metal groove structure on the artificial surface plasmon waveguide is smoothly connected with the right-angle bent slot line waveguide.

[0027] According to a terahertz broadband high-sensitivity sensor chip based on local field enhancement provided by the present invention, the metal groove structure includes a transition region, the transition region includes a plurality of metal grooves, and the depth of the plurality of metal grooves varies with a gradient. When the depth of the metal groove is small, the transmission mode is a waveguide mode; and as the depth of the metal groove gradually increases, the waveguide mode gradually transforms into a surface plasmon mode.

[0028] A method for manufacturing a terahertz broadband high-sensitivity sensor chip based on local field enhancement, the method is used to manufacture the above-mentioned terahertz broadband high-sensitivity sensor chip based on local field enhancement, and the method comprises the following steps:

[0029] Sample preparation: providing an insulating dielectric film, performing a pre-operation on the insulating dielectric film, and then evenly attaching the insulating dielectric film to a single crystal silicon substrate;

[0030] Spin coating: Spin the photoresist evenly on the surface of the insulating dielectric film at a fixed speed within a predetermined time; and use a heating table to heat the photoresist to remove excess organic solvents in the photoresist.

[0031] UV exposure: Use a UV mask exposure machine to expose the sample to achieve patterning of the photoresist layer;

[0032] Development: Use developer to develop the sample after UV exposure;

[0033] Electron beam sputtering: using a multi-cavity coating apparatus to deposit a metal layer on the surface of a patterned insulating dielectric film;

[0034] Stripping process: using organic solvent to dissolve the photoresist layer, and stripping the insulating dielectric film with the metal layer from the silicon wafer while removing the photoresist;

[0035] At this point, the sensor chip with the insulating dielectric film as the substrate is completed.

[0036] It can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention uses a Vivaldi antenna to achieve efficient coupling of terahertz waves from free space to the on-chip system, and optimizes the design of the sensor chip to achieve single-mode transmission;

[0038] (2) The present invention utilizes artificial surface plasmon enhancement to improve the degree of interaction between terahertz waves and target substances in the on-chip system, thereby improving the sensing sensitivity of the sensor chip to trace substances;

[0039] (3) The present invention utilizes progressive waveguides to enhance the confinement of electromagnetic fields;

[0040] (4) The effective working bandwidth of the sensor chip can reach 1.35 THz, which can realize the wide-spectrum fingerprint recognition of various substances;

[0041] (5) The present invention has a competition suppression mode, which can improve the purity of the spectrum;

[0042] (6) The preparation process of the present invention is relatively simple and can be prepared in large quantities. The sensor chip has great application potential in the field of convenient sensing detection.

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of a uniform slot line waveguide in an embodiment of a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention.

[0045] Figure 2 It is a structural schematic diagram of an intermediate gradually narrowing deep subwavelength slot line waveguide in an embodiment of a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention.

[0046] Figure 3 It is a schematic diagram of terahertz time domain signal comparison of a sensor chip with metal areas of different shapes and sizes in an embodiment of a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention and its actual reference diagram.

[0047] Figure 4 This is a comparison diagram of terahertz time domain signal results of a large-area metal layer sensor chip and a sensor chip with a circular metal area in an embodiment of a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention.

[0048] Figure 5 It is a schematic diagram of dispersion curves of artificial surface plasmon waveguides with different design structures in an embodiment of a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention.

[0049] Figure 6It is a schematic diagram of an artificial surface plasmon waveguide structure with cutoff frequencies of 1.0 and 0.7 THz respectively in an embodiment of a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention.

[0050] Figure 7 This is a diagram of simulation results of the transmission coefficient and reflection coefficient of an artificial surface plasmon waveguide with and without a transition region in an embodiment of a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention.

[0051] Figure 8 It is a production flow chart of an embodiment of a method for producing a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention.

[0052] Fig. 9 It is a schematic diagram of the results related to the processing and preparation of the sensor chip in an embodiment of a method for manufacturing a terahertz broadband high-sensitivity sensor chip based on local field enhancement of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The Vivaldi antenna is a broadband antenna. Its working principle is based on the theory of transmission lines. Through clever design, electromagnetic waves are gradually guided and accelerated inside the antenna, eventually forming a radiation beam with specific directionality. Its transmission line part usually uses microstrip lines or other types of transmission lines, while the radiation part uses a series of gradually widening metal slots or gaps. This design makes the Vivaldi antenna have the characteristics of broadband characteristics, miniaturization, simple structure, strong directivity, good impedance matching and easy integration with other components. It is widely used in wireless communications, imaging, sensing and other fields.

[0055] A terahertz broadband high-sensitivity sensor chip embodiment based on local field enhancement

[0056] See also Figures 1 to 7The embodiment provides a terahertz broadband high-sensitivity sensor chip based on local field enhancement, including: an input port, an output port, a Vivaldi antenna 10, and an artificial surface plasmon waveguide 20 with a metal groove structure. The terahertz wave is input through the input port, passes through the Vivaldi antenna 10, the artificial surface plasmon waveguide 20, another Vivaldi antenna 10 in sequence, and then reaches the output port. The Vivaldi antenna 10 at the input end couples the terahertz wave in the free space to the artificial surface plasmon waveguide 20, and then the terahertz wave is transmitted in the waveguide under the constraint of the artificial surface plasmon waveguide 20. The terahertz wave on the waveguide is coupled back to the free space by the Vivaldi antenna 10 at the output end and is received by the terahertz detector.

[0057] A circular metal area is provided at the inner edge of the artificial surface plasmon waveguide 20 to improve the effective working bandwidth of the sensor chip. It can be seen that this embodiment introduces a circular structure design at the inner edge of the artificial surface plasmon waveguide 20 to suppress the competition mode, thereby improving the effective working bandwidth of the sensor chip.

[0058] In this embodiment, the sensor chip further includes a substrate 50, and the Vivaldi antenna 10 and the artificial surface plasmon waveguide 20 are both disposed on the substrate 50. The substrate 50 is an insulating dielectric film.

[0059] Specifically, the substrate 50 used in the sensor chip of this embodiment is an insulating dielectric film. There are two main reasons: on the one hand, the insulating dielectric film has excellent heat resistance, excellent strength, rigidity and compatibility with micro-nano processing technology, and is currently a relatively good material with good combination performance. On the other hand, the thinner insulating dielectric film can well suppress the transmission competition of the high-order base mode of electromagnetic waves, allowing only the basic mode to be transmitted.

[0060] In this embodiment, the structure of the Vivaldi antenna 10 gradually transitions from a narrow transmission slot line to a wider transmission slot line, and the transmission slot line changes exponentially, and the formed trumpet structure can radiate outward or receive electromagnetic waves inward. And precisely because its opening slot line changes exponentially, this antenna can receive or transmit electromagnetic waves at different frequencies by different opening parts, and the antenna therefore has a very wide operating frequency band. In addition, the Vivaldi antenna 10 with good radiation directivity and stable gain also has the advantage of a simple structure, which not only enables it to achieve a good connection with the slot waveguide, but also can be well compatible with micro-nano processing technology.

[0061] In this embodiment, the artificial surface plasmon waveguide 20 includes a right-angle bent slot waveguide, which is connected to both ends of the Vivaldi antenna 10 so that the electric field polarization directions of the terahertz signal are orthogonal to each other at the input end and the output end.

[0062] The right-angle bent slot waveguide of the present embodiment includes various types of slot waveguides, including but not limited to a smooth and uniform width slot waveguide, a middle gradually narrowing slot waveguide, and a sawtooth slot waveguide (corresponding to Figure 1 , Figure 2 , Figure 6 ).

[0063] In this embodiment, the metal groove structure on the artificial surface plasmon waveguide 20 is smoothly connected with the right-angle bent slot line waveguide.

[0064] In this embodiment, the metal groove structure includes a transition region, and has a waveguide design in the transition region to strengthen the confinement of the electromagnetic field. The transition region includes a plurality of metal grooves, and the depth gradient between the plurality of metal grooves varies. When the depth of the metal groove is small, the transmission mode is a waveguide mode; and as the depth of the metal groove gradually increases, the waveguide mode gradually transforms into a surface plasmon mode. It can be seen that an artificial surface plasmon waveguide 20 with a metal groove structure is introduced into the sensor chip to excite the artificial surface plasmon transmission mode.

[0065] Specifically, a 90° curved slot waveguide is connected to the Vivaldi antennas 10 at both ends, such as Figure 2 As shown, the slot line waveguide is a deep subwavelength slot line with a gradually narrowing middle part, and the two end parts are connected by smooth lines. The waveguide with a transition area can exert a tighter constraint on the electromagnetic field. The slot line waveguide is selected because it can support the transmission of electromagnetic wave quasi-transverse electromagnetic mode within a wide working bandwidth while exerting a tight constraint on the electromagnetic field, and can realize efficient interconnection with the Vivaldi antenna 10.

[0066] In order to further enhance the degree of interaction between terahertz waves and matter, this embodiment introduces an artificial surface plasmon waveguide 20 with a metal groove structure in the sensor chip to stimulate the artificial surface plasmon transmission mode. Compared with the slot waveguide, the artificial surface plasmon waveguide 20 with metal grooves has a stronger confinement effect on electromagnetic waves, which can slow down its transmission speed, thereby enhancing the interaction between electromagnetic waves and target substances. In addition, the deeper metal grooves have a stronger local effect, so that the artificial surface plasmon waveguide 20 with a lower cutoff frequency further strengthens the confinement effect on electromagnetic waves.

[0067] In this embodiment, the artificial surface plasmon waveguide 20 is designed to be bent at 90° so that the electric field polarization directions of the terahertz signal are orthogonal to each other at the input end and the output end. In this way, the terahertz signal that is not coupled to the sensor chip cannot be received because the electric field polarization direction is orthogonal to the direction that the receiver can recognize, that is, the terahertz signal that is not coupled to the slot line waveguide is eliminated, thereby making the received signal purer. For this reason, a terahertz time domain spectroscopy system suitable for a sensor chip bent at 90° is required.

[0068] Its working principle is: the Vivaldi antenna 10 at the input end couples the terahertz wave in the free space into the artificial surface plasmon waveguide 20. Then, the terahertz wave will be transmitted in the waveguide under the constraint of the artificial surface plasmon waveguide 20, or after strong interaction with the object to be detected added in the area, it will be transmitted in the waveguide carrying the corresponding information of the object to be detected. Finally, the terahertz wave on the waveguide is coupled back to the free space by the Vivaldi antenna at the output end and received by the terahertz detector.

[0069] Regarding the singleness of the transmission mode, this embodiment found during the test of the sensor chip that a small oscillation peak appears before the main peak signal in the terahertz time-domain spectrum. The existence of this oscillation peak will have a serious impact on the terahertz frequency-domain spectrum signal after the fast Fourier transform. Therefore, this embodiment intercepts a small unit segment of the slot waveguide and uses the finite-difference time-domain method to perform numerical simulation of the eigenmode. The results show that in addition to the target transmission mode, there is a competing mode 1 at the outer edge of the waveguide, and there is another competing mode 2 at the inner edge of the waveguide.

[0070] After determining that the oscillation peak is caused by the competition mode inside the waveguide, a circular metal area is introduced at the inner edge of the artificial surface plasmon waveguide 20, the purpose is to extend the transmission distance of the competition mode 2, so that the oscillation signal caused by it in the time domain signal disappears or moves away from the main peak, so that in subsequent tests, no other interference signals except the main peak will appear in the sampling window, thereby not affecting the subsequent fast Fourier transform results. In view of the shape and size of the metal area, this embodiment sets up relevant experiments for comparison, specifically two schemes of circular and triangular shapes, and sets different sizes for comparison, such as Figure 3 As shown, Figure 3 A comparison of terahertz time-domain signals of sensor chips with metal areas of different shapes and sizes and their actual photos.

[0071] Specifically, Figure 3-a shows that the circular design has a better suppression effect on competitive mode 2 than the triangular design. In addition, as the circular area continues to increase, the oscillation signal becomes weaker and weaker, that is, the suppression effect on competitive mode 2 becomes better and better. However, the area of ​​the newly introduced metal area is not necessarily larger. The test results show that although the large metal area can significantly suppress competitive mode 2, the measured terahertz signal size shows a significant attenuation phenomenon at the same time. The reason is that the large area of ​​the metal layer leads to an increase in the ohmic loss of the electromagnetic wave.

[0072] Finally, in order to verify the inhibitory effect of the introduction of the circular metal area on the competition mode, this embodiment tested the sensor chip with and without the circular design. The results are as follows: Figure 4 As shown by Figure 4 It can be seen that after the circular metal area is introduced (red curve), the oscillation signal in the sensor chip test results almost disappears. This result shows that the introduction of a circular structure in the waveguide can effectively suppress the competitive mode 2, so that this oscillation signal no longer appears in the sampling time window.

[0073] In order to ensure that only one mode is transmitted on the metal groove, that is, to ensure the singleness and purity of the transmission mode, this embodiment designs three different structures of metal grooves and performs numerical simulations on them respectively. Common transmission channels have grooves on both sides and are symmetrical bilateral symmetrical structures, bilateral asymmetric staggered structures, and unilateral structures with grooves on only one side. Then, numerical simulations are performed on these three different metal groove structures to solve their dispersion curves in transmission mode 1 and transmission mode 2 respectively. Figure 5 As shown, Figure 5 Comparison results of dispersion curves of two transmission modes for three different metal groove structures are shown.

[0074] By Figure 5 It can be seen that for the metal grooves with double-sided structures, whether they are symmetrical or asymmetrical staggered structures, the two dispersion curves of artificial surface plasmon modes 1 and 2 that they can support are very close to each other, indicating that the momentum of the two transmission modes is not much different, so it is easy for transmission mode crosstalk to occur. In contrast, the two dispersion curves of artificial surface plasmon modes 1 and 2 that can be supported by metal grooves with single-sided structures have a significant spacing, so the artificial surface plasmon modes supported by this structure are not easy to cause crosstalk between modes, which can ensure the purity of the transmission mode, thereby improving the credibility of the sensor chip test results.

[0075] Since the metal groove introduced on the sensor chip is connected to the original 90° bent slot waveguide, a transition area is specially designed in this embodiment. The transition area is composed of a plurality of metal grooves with gradient depth changes, such as Figure 6The purpose of adding the transition region is to solve the momentum mismatch problem between the slot waveguide and the plasma waveguide. Numerical simulations are performed on two sections of plasma waveguides without and with transition regions to solve the transmission coefficients and reflection coefficients of the two waveguides, respectively, as shown in Figure 7 shown.

[0076] The above results show that the transition region can achieve good momentum matching between the artificial surface plasmon waveguide 20 and the slot waveguide. This is because the transition region has a groove with a gradually changing depth, so it can support both the surface plasmon mode and the guided wave mode of the slot waveguide transmission. When the depth of the groove is small, the main transmission mode is the guided wave mode; and as the depth of the groove gradually increases, the guided wave mode gradually transforms into the surface plasmon mode.

[0077] In summary, the present embodiment utilizes the Vivaldi antenna 10 to realize efficient coupling of terahertz waves from free space to the on-chip system, and realizes single-mode transmission by optimizing the design of the sensor chip; the present embodiment utilizes artificial surface plasmon enhancement to improve the degree of interaction between terahertz waves and target substances in the on-chip system, thereby improving the sensing sensitivity of the sensor chip to trace substances; the present embodiment utilizes progressive waveguides to strengthen the confinement of electromagnetic fields; the effective working bandwidth of the sensor chip can reach 1.35 THz, and wide-spectrum fingerprint recognition of a variety of substances can be realized; the present embodiment has a competition suppression mode, which can improve the purity of the spectrum.

[0078] A method for manufacturing a terahertz broadband high-sensitivity sensor chip based on local field enhancement

[0079] See also Figures 8 to 9 The present embodiment provides a method for manufacturing a terahertz broadband high-sensitivity sensor chip based on local field enhancement. The method is used to manufacture the above-mentioned terahertz broadband high-sensitivity sensor chip based on local field enhancement, and the method comprises the following steps:

[0080] Step S1, sample preparation: providing an insulating dielectric film, performing a pre-operation on the insulating dielectric film, and then evenly attaching the insulating dielectric film to the single crystal silicon substrate 50;

[0081] Step S2, coating: coating the photoresist uniformly on the surface of the insulating dielectric film by spinning the photoresist at a fixed rotation speed within a predetermined time; and heating the photoresist on a heating table to remove excess organic solvent in the photoresist.

[0082] Step S3, ultraviolet exposure: using an ultraviolet mask exposure machine to perform an exposure operation on the sample to achieve patterning of the photoresist layer;

[0083] Step S4, developing: using a developer to develop the sample after UV exposure;

[0084] Step S5, electron beam sputtering: using a multi-cavity coating apparatus to evaporate a metal layer on the surface of the patterned insulating dielectric film;

[0085] Step S6, stripping process: using an organic solvent such as acetone to dissolve the photoresist layer, and stripping the insulating dielectric film with the metal layer from the silicon wafer while removing the photoresist;

[0086] At this point, the sensor chip with the insulating dielectric film as the substrate is completed.

[0087] In practical applications, the sensor chip of this embodiment is prepared by using ultraviolet mask exposure and electron beam evaporation coating process, such as Figure 8 As shown, Figure 8 The main processing flow of preparing sensor chips using micro-nano processing technology is demonstrated. Fig. 9 Results related to the processing and preparation of sensor chips: (a) Insulating dielectric film attached to a 4-inch silicon wafer; (b) Mask prepared using laser direct writing technology; (c) Sensor chip after electron beam evaporation coating; (d) Sensor chips with antennas of different lengths prepared in large quantities.

[0088] In the above step S1, the insulating dielectric film needs to be evenly attached to the single crystal silicon substrate 50, such as Fig. 9 (a) is shown. Then, the surface of the insulating dielectric film is blown clean with an air gun to remove tiny dust particles on the surface of the insulating dielectric film. The adhesion layer between the insulating dielectric film and the silicon substrate uses the same photoresist AR-N 4340 negative photoresist used in the UV mask exposure process, and the bubbles in the adhesion layer are removed as much as possible by evacuating the sample box. The reason for pre-operation of the insulating dielectric film is that, on the one hand, a flat and hard silicon substrate is conducive to micro-nano processing operations on the soft insulating dielectric film; on the other hand, the selected photoresist will be dissolved by the organic solvent in the subsequent degumming process, and the insulating dielectric film will be separated from the silicon substrate without loss.

[0089] In the above step S2, the AR-N 4340 photoresist is evenly spin-coated on the surface of the insulating dielectric film at a rotation speed of 4000 rad / min for 60 seconds; and the photoresist is heated at 90° C. for 60 seconds using a heating table to remove excess organic solvent in the photoresist.

[0090] In the above step S3, the specific process flow of UV mask exposure includes:

[0091] Pre-baking: Bake at 90°C for 1 min to completely evaporate the solvent;

[0092] Exposure: Fig. 9As shown in (b), the pattern of the sensor chip is transferred from the pre-prepared mask plate to the photoresist layer through ultraviolet mask exposure; wherein the ultraviolet irradiation dose is 140mJ / cm2;

[0093] Post-baking: The exposed samples were baked at 95°C for 2 min for post-baking.

[0094] In the above step S4, development was performed with AR 300-47 developer at 21°C for 60 seconds, followed by rinsing in DI-H2O for 30 seconds.

[0095] In the above step S5, after the photolithography process is completed, a 10nm thick titanium layer, a 300nm thick silver layer and a 10nm thick titanium layer are sequentially deposited by electron beam evaporation on the insulating dielectric film substrate 50 after the patterned photolithography operation. Among them, the first titanium layer serves as a bonding layer between the insulating dielectric film and the silver layer, and the second titanium layer is a protective layer to prevent the silver layer from being rapidly oxidized. Silver is selected because of its high conductivity to reduce ohmic loss. The sample after the electron beam evaporation coating is as follows Fig. 9 (c) as shown.

[0096] Finally, the organic solvent acetone is used to fully dissolve the two photoresist layers, including the patterned layer above the insulating dielectric film substrate 50 and the adhesive layer between the insulating dielectric film substrate 50 and the silicon wafer, and then rinsed with DI-H2O. So far, the sensor chip with the insulating dielectric film as the substrate has been successfully prepared by means of ultraviolet exposure technology and micro-nano processing such as electron beam evaporation coating, and the finished product is Fig. 9 (d) is shown.

[0097] In summary, the preparation process of this embodiment is relatively simple and can be prepared in large quantities. The sensor chip has great application potential in the field of convenient sensing detection.

[0098] It should be understood that the embodiments described above are only illustrative. The embodiments described in this embodiment may be implemented in hardware, software, firmware, middleware, or any combination thereof.

[0099] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A terahertz broadband high-sensitivity sensor chip based on local field enhancement, characterized in that: include: An input port, an output port, a Vivaldi antenna, and an artificial surface plasmon waveguide with a metal groove structure. The terahertz wave is input through the input port, and sequentially passes through the Vivaldi antenna, the artificial surface plasmon waveguide, another Vivaldi antenna, and then reaches the output port. The Vivaldi antenna at the input end couples the terahertz wave in the free space to the artificial surface plasmon waveguide. Then, the terahertz wave is transmitted in the waveguide under the constraint of the artificial surface plasmon waveguide. The terahertz wave on the waveguide is coupled back to the free space by the Vivaldi antenna at the output end and is received by the terahertz detector. A circular metal area is provided at the inner edge of the artificial surface plasmon waveguide to increase the effective working bandwidth of the sensor chip; The artificial surface plasmon waveguide includes a right-angle bent slot waveguide, and the right-angle bent slot waveguide is connected to two ends of the Vivaldi antenna, so that the electric field polarization directions of the terahertz signal are orthogonal to each other at the input end and the output end; The right-angle bent slot waveguide is a deep sub-wavelength slot with a gradual narrowing in the middle, and its two end portions are smooth line designs; The metal groove structure on the artificial surface plasmon waveguide is connected to the right-angle bent slot line waveguide; The metal groove structure includes a transition region, which includes multiple metal grooves. The depth of the multiple metal grooves varies in a gradient. When the depth of the metal groove is small, the transmission mode is a waveguide mode; and as the depth of the metal groove gradually increases, the waveguide mode gradually transforms into a surface plasmon mode.

2. The sensor chip according to claim 1, characterized in that: It also includes a substrate, and the Vivaldi antenna and the artificial surface plasmon waveguide are both arranged on the substrate.

3. The sensor chip according to claim 2, characterized in that: The substrate is an insulating dielectric film material.

4. The sensor chip according to claim 1, characterized in that: The structure of the Vivaldi antenna is a gradual transition from a narrow transmission slot line to a wider transmission slot line, and the transmission slot line changes exponentially, and the formed horn-mouth structure can radiate outwards or receive electromagnetic waves inwards.

5. A method for manufacturing a terahertz broadband high-sensitivity sensor chip based on local field enhancement, characterized in that: The method is used to manufacture a terahertz broadband high-sensitivity sensor chip based on local field enhancement as described in any one of claims 1 to 4, and comprises the following steps: Sample preparation: providing an insulating dielectric film, pre-treating the insulating dielectric film, and then evenly attaching the insulating dielectric film to a single crystal silicon substrate; Spin coating: Spin coating the photoresist evenly on the surface of the insulating dielectric film at a fixed speed within a predetermined time; and use a heating table to heat the photoresist to remove excess organic solvents in the photoresist; UV exposure: Use a UV mask exposure machine to expose the sample to achieve patterning of the photoresist layer; Development: Use developer to develop the sample after UV exposure; Electron beam sputtering: using a multi-cavity coating apparatus to deposit a metal layer on the surface of a patterned insulating dielectric film; Stripping process: using organic solvent to dissolve the photoresist layer, and stripping the insulating dielectric film with the metal layer from the silicon wafer while removing the photoresist; At this point, the sensor chip with the insulating dielectric film as the substrate is completed.

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