Millimeter wave artificial surface plasmon transmission line based on self-curling technology

Abstract

The invention discloses a millimeter wave artificial surface plasmon transmission line based on a self-curling technology, belongs to the technical field of millimeter wave devices, and uses the self-curling technology to curl a metal sawtooth structure in a plane sawtooth SSPPs along a groove direction to form an on-chip three-dimensional multi-turn cylindrical structure. By combining the unique strong field binding capacity of the SSPPs metamaterial with the on-chip three-dimensional miniaturization technology of the self-curling process, the occupied area of the SSPPs is greatly reduced while the transmission performance equivalent to that of traditional plane zigzag SSPPs is guaranteed, the occupied area of a metal sawtooth array in the SSPPs is expected to be reduced by 5-10 times by increasing the number of self-curling turns, and the service life of the metal sawtooth array in the SSPPs is prolonged. A novel miniaturized high-performance SSPPs transmission line is realized, and a new thought and a new method are introduced for a high-integration circuit and a high-integration system.

Description

Technical Field

[0001] The present invention belongs to the technical field of millimeter wave devices, and in particular relates to a millimeter wave artificial surface plasmon transmission line based on self-curling technology. Background Art

[0002] In the rapidly developing intelligent information age, the rapid rise of artificial intelligence and sixth-generation mobile communications (6G) technologies are placing increasingly stringent demands on fundamental millimeter-wave devices, integrated circuits, and various information systems (such as communications, radar, and imaging). These common cutting-edge technological requirements include miniaturization of devices, circuits, and systems; excellent signal integrity between subsystems; and interference suppression capabilities between highly integrated channels. However, for traditional integrated circuit-based millimeter-wave circuits and systems, the inherent spatial guidance modes, propagation wavelengths, and mode coupling create mutually restrictive and conflicting requirements in traditional devices and circuits based on transmission lines such as microstrip and coplanar waveguides, severely limiting further improvements in millimeter-wave integrated circuit performance.

[0003] Surface plasmon polaritons (SSPPs) transmission lines possess unique strong field confinement properties, combined with near-field enhancement and subwavelength operation. They combine high speed, low loss, and low crosstalk in highly integrated circuits, making them a key transmission medium for achieving breakthroughs in millimeter-wave integrated circuits and systems. The dispersion characteristics and electromagnetic confinement capabilities of SSPPs are primarily determined by their geometry: larger sizes result in stronger field confinement, lower cutoff frequencies, and reduced crosstalk between lines. However, the increasing size of SSPPs conflicts with the goal of device miniaturization, making this a difficult compromise.

[0004] Therefore, there is an urgent need for SSPPs that can achieve both low line crosstalk performance and device miniaturization. Summary of the Invention

[0005] To address the technical problem of traditional SSPPs occupying a large area, the present invention provides a millimeter-wave artificial surface plasmon transmission line based on self-curling technology. The self-curling technology is used to achieve the curling of the sawtooth part in the planar zigzag SSPPs. While ensuring low line crosstalk performance, the footprint of the SSPPs is greatly reduced, and it has broad application prospects in miniaturized devices.

[0006] The technical solutions adopted in the present invention are as follows:

[0007] A millimeter-wave artificial surface plasmon transmission line based on self-curling technology uses self-curling technology to curl the metal zigzag structure in the planar zigzag SSPPs along the groove direction to form a multi-turn cylindrical structure as a whole.

[0008] Furthermore, the planar zigzag SSPPs include a metal strip and a plurality of metal zigzag structures connected to the same side of the metal strip.

[0009] Furthermore, the cutoff frequency of the millimeter-wave artificial surface plasmon transmission line based on the self-curling technology decreases as the diameter of the multi-turn cylindrical structure increases.

[0010] Furthermore, the equivalent length of the millimeter-wave artificial surface plasmon transmission line based on the self-curling technology increases as the number of turns of the multi-turn cylindrical structure increases.

[0011] Furthermore, the outer curled surface of the planar zigzag SSPPs is covered with two layers of SiN with reverse stress. x film.

[0012] Furthermore, the specific process of curling using the self-curling technology is as follows:

[0013] Step 1: sequentially preparing an oxide layer and a germanium sacrificial layer on a substrate;

[0014] Step 2: Using plasma enhanced chemical vapor deposition (PECVD) method, by adjusting the frequency, a compressive internal stress SiN is deposited on the germanium sacrificial layer. x Thin film and tensile internal stress SiN x Double-layer SiN film x film;

[0015] Step 3: Remove part of the germanium sacrificial layer and the double-layer SiN by etching or photolithography x Film, forming a curled table top;

[0016] Step 4: Prepare planar zigzag SSPPs made of metal on the curling table;

[0017] Step 5: Deposit a protective layer on the curved mesa obtained in step 4, and remove the germanium sacrificial layer under the metal sawtooth structure in the planar sawtooth SSPPs by opening an etching window to release the double-layer SiN x Film stress, which in turn drives the double-layer SiN x The film curls up on its own, driving the metal serrated structure to curl along the groove direction.

[0018] Furthermore, the compressive internal stress SiN x The film is deposited under low frequency conditions to stretch the internal stress SiN x The thin films are deposited under high frequency conditions.

[0019] The beneficial effects of the present invention are:

[0020] The present invention proposes a millimeter-wave artificial surface plasmon transmission line based on self-curling technology. The metal sawtooth structure in the planar sawtooth SSPPs is curled along the groove direction using the self-curling technology to form an on-chip three-dimensional multi-turn cylindrical structure. By combining the unique strong field binding ability of the SSPPs metamaterial with the on-chip three-dimensional miniaturization technology of the self-curling process, the present invention greatly reduces the footprint of the SSPPs while ensuring transmission performance (low return loss and insertion loss) comparable to that of traditional planar sawtooth SSPPs. By increasing the number of self-curling turns, it is expected to reduce the footprint of the metal sawtooth array in the SSPPs by 5 to 10 times, realizing a new type of miniaturized and high-performance SSPPs transmission line, introducing new ideas and methods for highly integrated circuits and systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of a millimeter-wave artificial surface plasmon transmission line based on self-curling technology proposed in Example 1 of the present invention;

[0022] Figure 2 Schematic diagram of the structure of the millimeter-wave artificial surface plasmon unit based on the self-curling technology in Example 1 of the present invention;

[0023] Figure 3 Schematic diagram of the structure of traditional planar zigzag SSPPs;

[0024] Figure 4 The simulation results of traditional planar zigzag SSPPs are shown;

[0025] Figure 5 These are the simulation results of the millimeter-wave artificial surface plasmon transmission line based on the self-curling technology proposed in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Although limited embodiments are described below, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0027] Example 1

[0028] This embodiment provides a millimeter wave artificial surface plasmon transmission line based on self-curling technology, which uses the self-curling technology to curl the metal sawtooth structure in the planar sawtooth SSPPs along the groove direction to form a whole. Figure 1 The on-chip three-dimensional multi-turn cylindrical structure shown in FIG. 1 is a structure of a millimeter-wave artificial surface plasmon unit. The structure of the millimeter-wave artificial surface plasmon unit is as shown in FIG. Figure 2As shown, it presents a single-turn cylindrical structure.

[0029] In this embodiment, the specific process of curling using the self-curling technology is as follows:

[0030] Step 1: First, a silicon dioxide (SiO2) isolation layer is prepared on the silicon substrate, and then a germanium sacrificial layer is formed by electron beam evaporation; wherein, the thickness uniformity and surface flatness of the germanium sacrificial layer will affect the double-layer SiN x The speed of film stress release and the yield of the final curled structure;

[0031] Step 2: Using the PECVD method, compressive internal stress SiN is first deposited on the germanium sacrificial layer under low frequency conditions. x Thin film, then tensile internal stress SiN is deposited under high frequency conditions x film, forming a double-layer SiN x film;

[0032] Step 3: Remove part of the germanium sacrificial layer and double-layer SiN by photolithography x Film, forming a curled table top;

[0033] Step 4: Use photolithography to define the required metal layer pattern on the curled table, use electron beam to deposit the metal layer, and form planar zigzag SSPPs through a lift-off process. The structure is as follows Figure 3 As shown, it includes a metal belt and a plurality of metal sawtooth structures connected to the same side of the metal belt;

[0034] Step 5: Atomic layer deposition (ALD) is used to deposit a 10 nm thick Al2O3 protective layer on the curved mesa obtained in step 4. By opening an etching window, the germanium sacrificial layer under the metal sawtooth structure in the planar sawtooth SSPPs is removed to release the double-layer SiN x Film stress, which in turn drives the double-layer SiN x The film curls up, driving the metal sawtooth structure to curl along the groove direction, forming a Figure 2 The single-turn cylindrical structure shown in FIG. 1 is a structure in which multiple single-turn cylindrical structures are arranged periodically along the transmission line direction, and the structure is as follows: Figure 1 The on-chip three-dimensional multi-turn cylindrical structure shown is a millimeter-wave artificial surface plasmon transmission line based on self-winding technology. The diameter of a single-turn cylindrical structure can be set between 1μm and 1000μm.

[0035] As Figure 3 The SSPPs structure shown is a traditional planar zigzag SSPPs with a zigzag length of 350 μm and a transmission line length of 3000 μm. The simulation results are shown in Figure 4 As shown in the figure, it can be seen that the return loss of traditional planar zigzag SSPPs is better than 10dB in the range of 0 to 90GHz, and the in-band insertion loss is about 0.2dB.

[0036] In order to compare the transmission performance of the millimeter-wave artificial surface plasmon transmission line based on the self-curling technology obtained in this embodiment with that of the traditional planar zigzag SSPPs, this embodiment uses a millimeter-wave artificial surface plasmon transmission line based on the self-curling technology with the same transmission line length of 3000 μm. When the diameter of the single-turn cylindrical structure is 200 μm, according to the following Figure 5 The simulation results shown in the figure show that S 11 The transmission performance is better than -10dB in the 0-100GHz range, and the in-band insertion loss is less than 0.2dB, indicating that its transmission performance is comparable to that of traditional planar zigzag SSPPs. However, a millimeter-wave artificial surface plasmon transmission line based on self-winding technology with a single-turn cylindrical structure diameter of 200μm can reduce the footprint of traditional planar zigzag SSPPs with a zigzag length of 350μm to 57%.

[0037] In summary, by using self-curling technology to curl the metal zigzag structure in planar zigzag SSPPs along the groove direction, the footprint of SSPPs can be greatly reduced while maintaining the same cutoff frequency and field binding strength as traditional planar zigzag SSPPs. By increasing the number of self-curling turns, it is expected to reduce the footprint of the metal zigzag array in SSPPs by 5 to 10 times, realizing a new type of miniaturized and high-performance SSPPs transmission line, and introducing new ideas and methods for highly integrated circuits and systems.

[0038] The above embodiments only illustrate the principles and advantages of the present invention, and are not intended to limit the present invention. They are only for helping to understand the principles of the present invention. The scope of protection of the present invention is not limited to the above configurations and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the disclosed technology without departing from the essence of the present invention, but they are still within the scope of protection of the present invention.

Claims

1. A millimeter-wave artificial surface plasmon transmission line based on self-curling technology, characterized in that: The metal zigzag structure in the planar zigzag SSPPs is curled along the groove direction using the self-curling technology to form a multi-turn cylindrical structure.

2. The millimeter-wave artificial surface plasmon transmission line based on self-curling technology according to claim 1, characterized in that: The cutoff frequency of the millimeter-wave artificial surface plasmon transmission line based on the self-curling technology decreases as the diameter of the multi-turn cylindrical structure increases.

3. The millimeter-wave artificial surface plasmon transmission line based on self-curling technology according to claim 1, characterized in that: The equivalent length of the millimeter-wave artificial surface plasmon transmission line based on the self-curling technology increases as the number of turns of the multi-turn cylindrical structure increases.

4. The millimeter-wave artificial surface plasmon transmission line based on self-curling technology according to claim 1, characterized in that: The planar zigzag SSPPs include a metal strip and a plurality of metal zigzag structures connected to the same side of the metal strip.

5. The millimeter-wave artificial surface plasmon transmission line based on self-curling technology according to claim 4, characterized in that: The outer curled surface of the planar zigzag SSPPs is covered with two layers of SiN with reverse stress. x film.

6. The millimeter wave artificial surface plasmon transmission line based on self-curling technology according to claim 5, characterized in that: The specific process of curling using self-curling technology is as follows: Step 1: sequentially preparing an oxide layer and a germanium sacrificial layer on a substrate; Step 2: Using PECVD method, by adjusting the frequency, depositing SiN with compressive internal stress on the germanium sacrificial layer. x Thin film and tensile internal stress SiN x Double-layer SiN film x film; Step 3: Remove part of the germanium sacrificial layer and the double-layer SiN by etching or photolithography x Film, forming a curled table top; Step 4: Prepare planar zigzag SSPPs made of metal on the curling table; Step 5: Deposit a protective layer on the curved mesa obtained in step 4, and remove the germanium sacrificial layer under the metal sawtooth structure in the planar sawtooth SSPPs by opening an etching window to release the double-layer SiN x Film stress, which in turn drives the double-layer SiN x The film curls up on its own, driving the metal serrated structure to curl along the groove direction.

7. The millimeter-wave artificial surface plasmon transmission line based on self-curling technology according to claim 6, characterized in that: The compressive internal stress SiN x The film is deposited under low frequency conditions to stretch the internal stress SiN x The thin films are deposited under high frequency conditions.

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