SOI substrate-based micro-mechanical impedance matching network tuner with defected ground structure and manufacturing method thereof

Abstract

The invention discloses a micro-mechanical impedance matching network tuner with a defected ground structure based on an SOI substrate and a manufacturing method of the micro-mechanical impedance matching network tuner. SOI is adopted as the substrate of a tuner device, loss can be effectively reduced, device structures are sequentially and symmetrically arranged on the two sides of a signal line, one end is a signal input end, and the other end is a signal output end; six high-resistance bias pads are arranged at the two ends of the device respectively, two transmission lines are symmetrically arranged on the two sides of a signal line, two DGS structures are arranged on the signal line, an MEMS bridge is arranged on the transmission lines and connected with the signal line in parallel through a wire, and variable capacitance and effective medium value are achieved through switching of the MEMS bridge so that variable impedance can be achieved. The two DGS structures on the signal line enable the structure to be compact and the impedance to be adjusted.

Description

Technical Field

[0001] The present invention belongs to the cross field of micromechanical system, microelectronic technology and microwave subject, and specifically relates to a micromechanical impedance matching network tuner with defective structure based on SOI substrate and a manufacturing method thereof. Background Art

[0002] Matching network is one of the important parts in microwave wireless communication system. Reconfigurable matching network has a wide range of applications in microwave relay communication, satellite communication, radar, broadband amplifier and multiplier, electronic countermeasure and microwave measurement system. It can reduce the loss at the antenna input, improve its performance, and enable the power amplifier to play a higher system efficiency. It is mainly used in multi-band communication system, radar and wide-band tracking receiver and image rejection mixer application needs.

[0003] The reconfigurable matching technology network is based on the periodic placement of DGS structures along the CPW line of the SOI substrate, thereby increasing the effective dielectric constant due to its slow wave effect and its characteristic impedance. Its structure consists of SOI substrate, CPW line, DGS structure, MEMS switch, etc. This device has simple process manufacturing, low cost, good product stability and reliable quality. Therefore, the reconfigurable circuit composed of it meets their low insertion loss and high linearity; it can meet the requirements of low noise amplifier / mixer. This device can be used in military systems that require a wide and continuous band. The DGS structure has a relatively high self-resonance frequency, so it can also cover a wide range of impedance changes. Summary of the invention

[0004] The present invention aims at the problems existing in the prior art and provides a micromechanical impedance matching network tuner based on an SOI substrate with a defective ground structure. The present invention combines a periodic defective ground structure (DGS) to make the tuner small in size, good in isolation, and low in insertion loss, thereby improving the power handling capability.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A micromechanical impedance matching network tuner based on an SOI substrate with a defective ground structure, characterized by a package substrate, an insulating layer, a metal layer, a signal transmission line, a plurality of high-resistance bias pads, a distributed MEMS transmission line, a plurality of MEMS switches, a defective ground structure, and an insulating block;

[0006] An insulating layer is attached to the substrate, a metal layer is attached to the insulating layer, a signal transmission line is buried in the metal layer, one end of the signal transmission line is used as a signal input end, and the other end is used as a signal output end; the signal transmission line divides the metal layer into two areas;

[0007] A first distributed MEMS transmission line and a second distributed MEMS transmission line are respectively arranged in the two regions, and the first distributed MEMS transmission line and the second distributed MEMS transmission line are arranged parallel to the signal transmission line in pairs and at equal distances; high-resistance bias pads are respectively arranged at both ends of the first distributed MEMS transmission line, the second distributed MEMS transmission line, and the signal transmission line;

[0008] Several groups of defective ground structures are arranged in sequence between the high-resistance bias pads at both ends of the signal transmission line, and each group includes a first defective ground structure and a second defective ground structure; an insulating block is arranged between the first defective ground structure and the second defective ground structure, and between every two groups of defective ground structures, and a MEMS switch is arranged on the insulating block to form a MEMS bridge. The capacitance is variable and the value of the effective medium is achieved through the switch of the MEMS bridge to realize the variable impedance. The two groups of defective ground structures can adjust the impedance.

[0009] Furthermore, the aforementioned substrate is made of silicon, quartz, ceramic, gallium arsenide, or silicon carbide.

[0010] Furthermore, the aforementioned insulating layer is formed by deposition through a photolithography process technology.

[0011] Furthermore, in the aforementioned micromechanical impedance matching network tuner based on an SOI substrate with a defective ground structure, two groups of defective ground structures are sequentially arranged between the high-resistance bias pads at both ends of the signal transmission line.

[0012] The present invention also provides a method for preparing a micromechanical impedance matching network tuner having a defective structure based on an SOI substrate, characterized in that it comprises the following steps:

[0013] S1. Sputter chromium and gold on SOI silicon, quartz, ceramic, gallium arsenide and other substrates to make transmission lines and microstrip signal transmission lines, bias pad seed layers, so as to prepare for subsequent metal electroplating films and firmly adhere to the base substrate;

[0014] S2, electroplating gold to form a thickness that meets the requirements of microstrip transmission lines and MEMS bridge piers and their bias pads, and meet the requirements of high-frequency microwave circuits. The thickness and quality requirements of the electroplated gold are preset based on the microwave frequency;

[0015] S3, photolithography to form the geometric figures of microstrip lines and defective ground structure figures;

[0016] S4, forming a deposited insulating layer material by photolithography technology;

[0017] S5, depositing a sacrificial layer material, and forming it after photolithography and development; the sacrificial layer material includes silicon nitride;

[0018] S6, photolithography masking out the MEMS bridge pattern, using a lift-off process to form the MEMS bridge;

[0019] S7, using gas etching to release the sacrificial layer, MEMS bridge is formed

[0020] S8. Use chemical vapor deposited polysilicon as a high resistance bias pad.

[0021] Furthermore, in the aforementioned step S2, the thickness of the electroplated gold is set according to the microwave frequency.

[0022] Furthermore, the aforementioned step S3 also includes photolithography to form other geometric patterns of the preset microwave circuit.

[0023] Furthermore, the aforementioned step S6 also includes evaporating Au, Al MEMS bridge materials and photolithographically masking a MEMS bridge pattern.

[0024] Compared with the prior art, the beneficial technical effects of the present invention using the above technical solution are as follows:

[0025] (1) The impedance network tuner is composed of a MEMS bridge and its defective ground structure (DGS) as a variable capacitor and a coplanar waveguide transmission line, which replaces MEMS switches and traditional PIN switch diodes, varactor diodes or FETs to achieve tuner matching reconstruction. The overall device has the advantages of compact and simple structure, small size, low power consumption of the control circuit, and high operating frequency.

[0026] (2) The impedance network tuner uses SOI structural material as the substrate, which effectively reduces substrate loss.

[0027] (3) The substrate material can be changed to, for example, silicon, silicon carbide, quartz, ceramics, gallium arsenide, etc.

[0028] (4) It is compatible with IC technology and can be integrated on substrates of various materials. The technology is relatively mature and the cost is low.

[0029] (5) Using the device of the invention to replace the existing switch device to realize the matching reconstruction of the matcher can reduce the process steps and improve the overall wafer production efficiency.

[0030] (6) The matching range can be extended by cascading multiple MEMS bridges and their defective ground surface (DGS) structures or changing the size of the DGS structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 is an overall structural diagram of the tuner of the present invention.

[0032] Figure 2 is a cross-sectional view of a tuner of the present invention.

[0033] In the figure, 1-high-resistance bias pad, 2-distributed MEMS transmission line, 3-signal transmission line, 4-first defective ground structure, 5-second defective ground structure, 6-MEMS switch, 7-insulating block. DETAILED DESCRIPTION

[0034] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings.

[0035] Various aspects of the invention are described herein with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the invention are not limited to those described in the accompanying drawings. It should be understood that the invention is implemented by any of the various concepts and embodiments described above, as well as the concepts and embodiments described in detail below, because the concepts and embodiments disclosed in the invention are not limited to any implementation. In addition, some aspects disclosed in the invention may be used alone or in any appropriate combination with other aspects disclosed in the invention.

[0036] refer to Figure 1 and Figure 2 On the one hand, the present invention provides a micromechanical impedance matching network tuner based on an SOI substrate with a defective ground structure, comprising a substrate, an insulating layer, a metal layer, a signal transmission line 3, a plurality of high-resistance bias pads, a distributed MEMS transmission line 2, a plurality of MEMS switches, defective ground structures of different sizes, and an insulating block. The substrate is made of silicon, quartz, ceramic, gallium arsenide, or silicon carbide, and the insulating layer is formed by deposition using a photolithography process. The defective ground structures of different sizes are used to achieve matching at different frequency points; furthermore, the SOI substrate is used to achieve the purpose of gradually reducing the loss.

[0037] An insulating layer is adhered on the substrate, a metal layer is adhered on the insulating layer, a signal transmission line 3 is buried in the metal layer, one end of the signal transmission line is used as a signal input end, and the other end is used as a signal output end; the signal transmission line divides the metal layer into two areas;

[0038] A first distributed MEMS transmission line and a second distributed MEMS transmission line are respectively arranged in the two regions, and the first distributed MEMS transmission line and the second distributed MEMS transmission line are arranged in parallel with the signal transmission line 3 in pairs and at equal distances; high-resistance bias pads 1 are respectively arranged at both ends of the first distributed MEMS transmission line, the second distributed MEMS transmission line, and the signal transmission line 3;

[0039] Two groups of defective ground structures are sequentially arranged between the high-resistance bias pads at both ends of the signal transmission line 3, each group includes a first defective ground structure 4 and a second defective ground structure 5; an insulating block 7 is arranged between the first defective ground structure 4 and the second defective ground structure 5, and between the two groups of defective ground structures, and a MEMS switch 6 is arranged on the insulating block 7 to form a MEMS bridge. The capacitance is variable and the value of the effective medium is achieved by the switch of the MEMS bridge to realize the variable impedance. The two groups of defective ground structures can adjust the impedance. The two defective ground structures located on the signal transmission line 3 make the structure compact and can adjust the impedance.

[0040] By using the slow-wave characteristics of the defective ground structure on the transmission line 3, the characteristic impedance and effective dielectric constant of the transmission line can be changed by opening and closing the MEMS bridge. The periodic DGS structure applied to microwave bandpass and band-stop filters can replace traditional switching devices such as varactor diodes or FETs, MEMS capacitors, etc. to achieve reconstructed impedance matching; the overall structure of the device is compact and simple, the size is small, the control circuit power consumption is low, and the operating frequency is high; it is partially compatible with traditional IC processes, the process is simple and mature, the cost is low, and it is suitable for mass production; and the loss is low, which can improve the performance of the matching network. Using the proposed design as the transmission line of the distributed MEMS matching network can further improve the impedance distribution of limited size.

[0041] The present invention proposes a micromechanical impedance matching network tuner based on a defective ground structure of an SOI substrate, which achieves the function of impedance matching reconstruction through three variable capacitors containing MEMS switches and a distributed transmission line slow wave system containing two DGS structures. Before reconstruction, no voltage is applied to the MEMS, and a certain impedance matching can be achieved in combination with the DGS structure; when voltage is applied to it, the pull-down capacitance of the MEMS bridge changes, and the inductive reactance property of the DGS structure changes, thereby causing the impedance to change, thereby realizing the function of reconfigurable impedance matching adjustment. The MEMS bridge and DGS structure are mainly used to change the characteristic impedance and effective dielectric constant of the transmission line to achieve the adjustment of impedance changes.

[0042] The reconfigurable impedance matching network of the present invention is suitable for the matching design of various radio frequency devices. It can be used as a multi-band and broadband reconfigurable matching network in a phased radar array. It has the advantages of small size, high frequency width, and low insertion loss. It minimizes the loss caused by different impedances when transmitting between different ports, so that the power transmission is in an optimized state. This reconfigurable impedance matching network can be used in multi-band RF transceivers working in different frequency bands. To meet the parallel path structure of repeated components required in multi-band transceivers. The development of the next generation of multi-band transceivers is driven by the establishment of adaptive and reconfigurable building blocks, such as adjustable filters, phase shifters, adaptive power amplifiers (PA), adjustable low noise amplifiers (LNA) and adaptive matching networks. Furthermore, this device can reduce the total chip area and cost by sharing as many building blocks as possible between various standards to replace the traditional parallel path concept. It can also improve power efficiency and linearity by switching the operating band or adjusting the output power level to compensate for the input / output impedance changes between different building blocks of the transceiver. In addition, it can also be used for radio frequency device integration to contribute to the development of future mobile communications. MEMS variable capacitors and defective ground structures are ideal for reconfigurable matching networks and can be integrated on low dielectric constant substrates, which is very important for high-performance tunable filters, antennas and low-loss matching networks. The adaptive impedance matching system composed of MEMS technology can maintain low loss in the RF front end and reduce off-chip components. It will become an important component of the intelligent RF front end of the new generation of wireless communication systems, such as highly reconfigurable, low-cost and low-power wireless and satellite communication networks, as well as radars, reconfigurable navigation and location recognition systems, and self-guided devices of smart weapons.

[0043] On the other hand, the present invention also provides a method for preparing a micromechanical impedance matching network tuner based on an SOI substrate with a defective structure, comprising the following steps:

[0044] S1. Sputter chromium (nickel, titanium) and gold on SOI silicon, quartz, ceramic, gallium arsenide and other substrates to make transmission lines and microstrip signal transmission lines, bias pad seed layers, so as to prepare for subsequent metal electroplating films and firmly adhere to the base substrate;

[0045] S2, electroplating gold to form a thickness that meets the microstrip transmission line and MEMS bridge piers and their bias pads, meeting the preset requirements of high-frequency microwave circuits;

[0046] S3, photolithography to form the geometric figures of microstrip lines and DGS structure figures;

[0047] S4, forming a deposited insulating layer material by photolithography technology;

[0048] S5, depositing sacrificial layer (silicon nitride, etc.) materials, and forming them after photolithography and development;

[0049] S6, photolithography mask out the MEMS bridge pattern, and evaporate Au, Al and other MEMS bridge materials, and adopt the stripping process to form the MEMS bridge;

[0050] S7, using gas etching to release the sacrificial layer, MEMS bridge is formed

[0051] S8. Use chemical vapor deposited polysilicon as a high resistance bias pad.

[0052] Although the present invention has been described above with preferred embodiments, it is not intended to limit the present invention. A person skilled in the art of the present invention may make various modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the definition of the claims.

Claims

1. A micromechanical impedance matching network tuner based on a SOI substrate with a defective structure, characterized in that: A package substrate, an insulating layer, a metal layer, a signal transmission line (3), a plurality of high-resistance deflection pads (1), a distributed MEMS transmission line (2), a plurality of MEMS switches (6), a defective ground structure, and an insulating block (7); An insulating layer is adhered on the substrate, a metal layer is adhered on the insulating layer, a signal transmission line (3) is buried in the metal layer, one end of the signal transmission line is used as a signal input end, and the other end is used as a signal output end; the signal transmission line divides the metal layer into two areas; A first distributed MEMS transmission line and a second distributed MEMS transmission line are respectively arranged in the two regions, and the first distributed MEMS transmission line and the second distributed MEMS transmission line are arranged parallel to the signal transmission line (3) in pairs and at equal distances; high-resistance bias pads (1) are respectively arranged at both ends of the first distributed MEMS transmission line, the second distributed MEMS transmission line, and the signal transmission line (3); A plurality of groups of defective ground structures are sequentially arranged between the high-resistance bias pads at both ends of the signal transmission line (3), each group comprising a first defective ground structure (4) and a second defective ground structure (5); an insulating block (7) is arranged between the first defective ground structure (4) and the second defective ground structure (5), and between every two groups of defective ground structures, and a MEMS switch (6) is arranged on the insulating block (7) to form a MEMS bridge. The capacitance is variable and the value of the effective medium is achieved by the switch of the MEMS bridge to realize the variable impedance. The two groups of defective ground structures can adjust the impedance.

2. The micromechanical impedance matching network tuner based on SOI substrate with defective structure according to claim 1, characterized in that: The substrate is made of silicon, quartz, ceramic, gallium arsenide or silicon carbide.

3. The micromechanical impedance matching network tuner based on SOI substrate with defective structure according to claim 1, characterized in that: The insulating layer is deposited by photolithography technology.

4. The micromechanical impedance matching network tuner based on SOI substrate with defective structure according to claim 1, characterized in that: Two groups of defective ground structures are arranged in sequence between the high-resistance bias pads at both ends of the signal transmission line.

5. A method for preparing a micromechanical impedance matching network tuner based on an SOI substrate with a defective structure, characterized in that: The following steps are involved: S1. Sputter chromium and gold on SOI silicon, quartz, ceramic, gallium arsenide and other substrates to make transmission lines and microstrip signal transmission lines, bias pad seed layers, so as to prepare for subsequent metal electroplating films and firmly adhere to the base substrate; S2, electroplating gold to form a thickness that meets the requirements of microstrip transmission lines and MEMS bridge piers and their bias pads, and meet the requirements of high-frequency microwave circuits. The thickness and quality requirements of the electroplated gold are preset based on the microwave frequency; S3, photolithography to form the geometric figures of microstrip lines and defective ground structure figures; S4, forming a deposited insulating layer material by photolithography technology; S5, depositing sacrificial layer materials, and forming them after photolithography and development; The sacrificial layer material includes silicon nitride; S6, photolithography masking out the MEMS bridge pattern, using a lift-off process to form the MEMS bridge; S7, using gas etching to release the sacrificial layer, MEMS bridge is formed S8. Use chemical vapor deposited polysilicon as a high resistance bias pad.

6. The method for preparing a micromechanical impedance matching network tuner based on a SOI substrate with a defective structure according to claim 5, characterized in that: The following steps are involved: In step S2, the thickness of the electroplated gold is set according to the microwave frequency.

7. The method for preparing a micromechanical impedance matching network tuner based on a SOI substrate with a defective structure according to claim 5, characterized in that: Step S3 also includes photolithography to form other geometric patterns of the preset microwave circuit.

8. The method for preparing a micromechanical impedance matching network tuner based on a SOI substrate with a defective structure according to claim 5, characterized in that: Step S6: evaporate Au, Al MEMS bridge material and photolithography mask out MEMS bridge pattern.

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