CN103326695B - A kind of restructural matching network adaptation containing mems switch - Google Patents

Abstract

The invention relates to a reconfigurable matching network matcher containing MEMS switches, which includes six MEMS bridge units, ground wires, signal wires and six bias pads, and the first ground wires and signal wires are sequentially arranged in parallel on the substrate Above, the six MEMS bridge units are sequentially arranged on the substrate perpendicular to the two ground lines, and each MEMS bridge unit includes two cantilever beam bridge membranes, a supporting beam bridge membrane and four bridge piers. Its beneficial effects are: the MEMS switch on the silicon chip replaces the traditional PIN switching diode, varactor diode or FET and other switching devices to realize the frequency reconstruction of the filter; the coplanar waveguide transmission line replaces the coplanar waveguide transmission line on the traditional PCB board ; Compact and simple structure, small size, low power consumption of the control circuit, high operating frequency; compatible with traditional IC technology, mature technology, low cost, suitable for mass production.

Description

A Reconfigurable Matching Network Matcher Containing MEMS Switches

technical field

The invention relates to the interdisciplinary technical field of micromechanical systems and microwaves, in particular to a reconfigurable matching network matcher including MEMS switches.

Background technique

Matching network is one of the important parts in microwave wireless communication system. In microwave relay communication, satellite communication, radar, broadband amplifier and multiplier, electronic countermeasure and its microwave measurement system, reconfigurable matching network has a wide range of applications, RF MEMS reconfigurable matching network can reduce the loss at the input of the antenna , Improving its performance can enable the power amplifier to obtain higher system efficiency, which is mainly used in multi-band communication systems, radar and wide-band tracking receivers, and image rejection mixer applications.

The reconfigurable matching technology network of RF MEMS is composed of MEMS switches, coplanar CPW transmission lines, varactors, etc. In addition, RF MEMS devices produce very low intermodulation distortion, so the reconfigurable circuits composed of them meet the requirements of low insertion loss and high linearity; before they are applied to low noise amplifiers/mixers.

Can be used in military systems that require very wide and continuous bands, such as 2~18GHz or 0.1~6GHz, which can be effectively realized by using reconfigurable antennas, matching networks and filters, and reconfigurable MEMS circuits can also Used to produce a wide range of impedance variations, which is necessary for transistor and diode characteristics.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art above, and provide a reconfigurable matching network matcher containing MEMS switches with small volume, good isolation, and low insertion loss. Specifically, the following technical solutions are implemented:

The reconfigurable matching network matcher containing MEMS switches includes six MEMS bridge units, first ground wires, second ground wires, signal wires and six bias pads, the first ground wires, signal wires, The second ground line is arranged parallel to the substrate in turn, and the six MEMS bridge units are arranged on the substrate perpendicular to the two ground lines in turn, and each MEMS bridge unit includes two cantilever bridge membranes, a support beam bridge membrane and four bridge piers, the supporting beam bridge membrane is arranged between two cantilever beam bridge membranes and spans the signal line through the bridge piers connected to both ends, the two cantilever beam bridge membranes are opposite to the supporting beam bridge membrane The corresponding end is a free end, and the other end is a fixed end connected to the bridge pier. The six bias pads are respectively connected to the cantilever bridge membranes on the corresponding sides of the six MEMS bridge units.

A further design of the reconfigurable matching network matcher including MEMS switches is that the position of the signal line relative to the bridge membrane of the supporting beam is isolated from the bridge membrane by a glass nitride insulating sheet.

The further design of the reconfigurable matching network matcher containing MEMS switches is that it also includes three input terminals and three output terminals, and the input terminals are respectively arranged on the first and second ground lines and one end of the signal line. , and the three output terminals are correspondingly arranged on the first and second ground lines and the other end of the signal line respectively.

The further design of the reconfigurable matching network matcher containing MEMS switches is that the bridge piers connected to the fixed end of the cantilever beam bridge film are respectively distributed on the substrate along the ground wires on the corresponding side, and the bridge piers connected with the supporting beam bridge are respectively distributed on the substrate. Six pairs of bridge piers connected at both ends of the film are distributed on the substrate along both sides of the signal line.

The reconfigurable matching network matcher containing MEMS switches provides a preparation method, using a total of six mask plates, and the specific operation steps are as follows:

1) Put a 500μm thick glass piece in a mixture of H ₂ O ₂ :H ₂ SO ₄ =1:1, wash it with deionized water, then put the glass piece into No. 1 cleaning solution and boil for 10 minutes, deionized Washing with water, the No. 1 cleaning solution is a mixture of NH ₄ OH, H ₂ O ₂ and deionized water. Finally, put the glass sheet into No. 2 cleaning solution and boil until boiling, rinse with deionized water, spin dry, and dry , the No. 2 cleaning solution is a mixture of HCl, H ₂ O ₂ and deionized water;

2) On the silica glass layer, the chromium layer and the gold layer are sequentially evaporated and deposited, the thicknesses are 800Å and 3000Å respectively, and the process conditions are: the temperature and vacuum degree in the evaporation furnace are 250°C and 10×10 ^-5 Torr, respectively;

3) Use the No. 1 mask plate to cover the positive glue on the surface of the area other than the No. 1 mask pattern of the glass sheet, leaving the pattern that needs to be electroplated, electroplating gold to form the input end, output end, bridge piers and bias pads, electroplating The thickness of the layer is 2μm, and the glue is removed to prepare for the next operation;

4) The method of positive photolithography No. 1 mask plate is respectively photolithography No. 2 mask plate and No. 3 mask plate, and electroplating gold to form ground wire, signal wire, bias voltage wire, and the thickness is 2 μm respectively. In addition, the electroplating Increase the thickness of the input and output terminals, bias pads and bridge piers from 2 μm to 3 μm, remove the glue and prepare for the next operation;

5) Negative photolithography No. 2 mask plate, after development, put it in an oven at 120°C to harden the film for 30 minutes, then plasma etch for 20 seconds, and finally etch away the gold layer and titanium layer of the unplated part in turn at room temperature , retain the input and output terminals, ground wires, signal wires, bias pads, bias wires and piers, the formula of the solution for corroding gold is KI: I ₂ : H ₂ O=20g: 6g: 100ml, the solution for corroding chromium is phosphoric acid ;

6) Oxygen plasma etching is used to remove the glue, and the etching power, oxygen flow rate, and etching time are 50W, 60ml/min, and 20 seconds respectively;

7) Deposit a layer of silicon nitride film with a thickness of 0.3 μm on the surface of the glass sheet by chemical vapor deposition, the flow rate of ammonia gas, the flow rate of glassane and the temperature are 28ml/min, 560ml/min and 280°C;

8) Cover the graphics on the No. 4 board with positive glue to protect the required glass nitride film. Then use SF ₆ gas plasma to etch the glass nitride film, the power, the flow rate of SF ₆ gas and the etching time are respectively 50w, 2.4ml/s and 1 minute 20 seconds;

9) At a speed of 2000 rpm, spin-coat a layer of polyimide film with a thickness of Spin-coat a positive resist with a thickness of 2 μm, pass through No. 5 mask plate photolithography, remove the positive resist after development, and obtain a sacrificial layer pattern, and then cure the glass sheet at 260°C for 1 hour;

10) Under a vacuum of 5×10 ^-5 Torr, evaporate and deposit an aluminum-glass alloy film containing 4% glass and a thickness of 0.5 μm on the surface of the glass sheet;

11) Negative photolithography No. 6 mask plate, put the glass piece in the H ₃ PO ₄ solution with a concentration ≥ 85% at 70°C, etch the aluminum-glass alloy film until the bubbles emerging from the phosphoric acid solution are very weak, forming The bridging membrane and glass slides were quickly cleaned with deionized water;

12) Plasma etching to remove the negative resist and sacrificial layer, the plasma etching power, oxygen flow rate and nitrogen flow rate are 50w, 60ml/s and 2.8ml/s respectively, to obtain six suspended support bridge membrane structures and twelve Cantilever beam bridge membrane structure, which is the movable contact piece of MEMS switch.

The advantages of the present invention are as follows:

1. The impedance network matcher is composed of a MEMS switch deposited on a glass sheet and a coplanar waveguide transmission line. The former replaces traditional PIN switching diodes, varactor diodes or FETs to realize the frequency reconstruction of the matcher, and the latter replaces Instead of the traditional coplanar waveguide transmission line on the PCB, it has the advantages of compact and simple structure, small size, good isolation, low insertion loss, low power consumption of the control circuit, and high operating frequency.

2. The filter is compatible with the traditional IC technology, integrated on the glass substrate, the technology is mature, the cost is low, and it is suitable for mass production.

Description of drawings

Fig. 1 is a structural diagram of the network matcher.

Fig. 2 is a sectional view of AA' in Fig. 1 .

FIG. 3 is a schematic diagram of the No. 1 mask pattern.

FIG. 4 is a schematic diagram of the No. 2 mask pattern.

FIG. 5 is a schematic diagram of the No. 3 mask pattern.

FIG. 6 is a schematic diagram of the No. 4 mask pattern.

FIG. 7 is a schematic diagram of No. 5 mask pattern.

Fig. 8 shows the S-parameters of the impedance matching test results of several frequency points selected between the frequency bands before the reconfigurable matching network is reconfigured.

Fig. 9 is the S parameter after reconstruction of the reconfigurable matching network.

In the figure, 1-MEMS bridge unit, 11-bridge pier, 12-cantilever bridge membrane, 13-support beam bridge membrane, 21-first ground wire, 22-second ground wire, 3-signal wire, 4-input terminal , 5-output terminal, 6-bias pad, 7-substrate, 8-glass nitride insulating sheet.

detailed description

The solution of the present invention will be described in detail below in conjunction with the accompanying drawings.

The reconfigurable matching network matcher containing MEMS switches provided in this embodiment includes six MEMS bridge units, a first ground wire, a second ground wire, a signal wire and six bias pads, a first ground wire, a signal wire 1. The second ground line is arranged parallel to the substrate in turn, and six MEMS bridge units are arranged on the substrate perpendicular to the two ground lines in turn. Each MEMS bridge unit includes two cantilever beam bridge membranes, a supporting beam bridge membrane and four bridge piers, the supporting beam bridge membrane is set between the two cantilever bridge membranes and spans the signal line through the bridge piers connected to both ends, the two cantilever beam bridge membranes are free ends relative to the corresponding ends of the supporting beam bridge membranes, and the other end is The fixed end is connected to the bridge pier, and the six bias pads are respectively connected to the cantilever bridge membrane on the corresponding side of the six MEMS bridge units. Bridge piers connected to the fixed ends of the cantilever beam bridge membrane are respectively distributed on the substrate along the ground wires on the corresponding side, and six pairs of bridge piers connected to both ends of the support beam bridge membrane are distributed on the substrate along both sides of the signal line. The position of the signal line relative to the bridge membrane of the supporting beam is isolated from the bridge membrane by a glass nitride insulating sheet.

The network matcher provided in this embodiment also includes three input terminals and three output terminals, the input terminals are respectively arranged on the first and second ground wires and one end of the signal wire, and the three output ends are respectively arranged on the first, second ground wires and one end of the signal wire. The second ground wire and the other end of the signal wire.

The reconfigurable matching network obtains reconfigurable functions by turning off and on six MEMS support beam switches and twelve cantilever beam switches. Before reconfiguration, no voltage was applied to the MEMS bridge. When a voltage of 28V was applied to the MEMS bridge, the MEMS bridge was pulled down by electrostatic force, which caused the capacitance to change and the impedance to change, thereby realizing the reconstruction of the reconfigurable impedance matching network.

The reconfigurable impedance matching network of the present invention is particularly suitable for use in phased arrays as a multi-band and broadband reconfigurable matching network, and has the advantages of small size, high frequency, and small insertion loss. In addition, it can also be used for radio frequency device integration and contribute to the development of future mobile communications. MEMS reconfigurable matching networks will become a new generation of wireless communication systems, such as highly reconfigurable, low-cost and low-power wireless and satellite communication networks, radars, reconfigurable navigation position recognition systems, and self-guiding devices for smart weapons. An important part of the intelligent RF front-end, the adaptive system composed of MEMS technology can maintain low loss and good linearity of the RF front-end, and can reduce off-chip components.

According to the network matcher, this embodiment provides a preparation method, using six mask plates, and the specific operation steps are as follows:

1) Put a 500μm thick glass piece in a mixture of H ₂ O ₂ :H ₂ SO ₄ =1:1, wash it with deionized water, then put the glass piece into No. 1 cleaning solution and boil for 10 minutes, deionized Washing with water, the No. 1 cleaning solution is a mixture of NH ₄ OH, H ₂ O ₂ and deionized water, and the proportion is 27% NH ₄ OH: 30% H ₂ O ₂ : deionized water = 1: 2: 5. Finally, put the glass sheet into No. 2 cleaning solution and boil until boiling, rinse with deionized water, spin dry, and dry. The No. 1 cleaning solution is a mixture of HCL, H ₂ O ₂ and deionized water. 37% HCL: 30% H ₂ O ₂ : deionized water = 1:2:8.

2) On the silica glass layer, the chromium layer and the gold layer are sequentially evaporated and deposited, the thicknesses are 800Å and 3000Å respectively, and the process conditions are: the temperature and vacuum degree in the evaporation furnace are 250°C and 10×10 ^-5 Torr, respectively.

3) Use the No. 1 mask plate to cover the positive glue on the surface of the area other than the No. 1 mask pattern of the glass sheet, leaving the pattern that needs to be electroplated, electroplating gold to form the input end, output end, bridge piers and bias pads, electroplating The thickness of the layer is 2 μm, and the glue is removed to prepare for the next operation.

4) The method of positive photolithography No. 1 mask plate is respectively photolithography No. 2 mask plate and No. 3 mask plate, and electroplating gold to form ground wire, signal wire, bias voltage wire, and the thickness is 2 μm respectively. In addition, the electroplating Increase the thickness of the input and output terminals, bias pads and bridge piers from 2 μm to 3 μm, remove the glue and prepare for the next operation.

5) Negative photolithography No. 2 mask plate, after development, put it in an oven at 120°C to harden the film for 30 minutes, then plasma etch for 20 seconds, and finally etch away the gold layer and titanium layer of the unplated part in turn at room temperature , retain the input and output terminals, ground wires, signal wires, bias pads, bias wires and piers, the formula of the solution for corroding gold is KI: I ₂ : H ₂ O=20g: 6g: 100ml, the solution for corroding chromium is phosphoric acid .

6) Oxygen plasma etching is used to remove the glue, and the etching power, oxygen flow rate, and etching time are 50W, 60ml/min, and 20 seconds, respectively.

7) Deposit a layer of silicon nitride film with a thickness of 0.3 μm on the surface of the glass sheet by chemical vapor deposition, the flow rate of ammonia gas, the flow rate of glassane and the temperature are 28ml/min, 560ml/min and 280°C respectively.

8) Cover the graphics on the No. 4 board with positive glue to protect the required glass nitride film. Then use SF ₆ gas plasma to etch the glass nitride film, the power, the flow rate of SF ₆ gas and the etching time are respectively 50w, 2.4ml/s and 1 minute 20 seconds.

9) At a speed of 2000 rpm, spin-coat a layer of polyimide film with a thickness of Spin coat a positive resist with a thickness of 2 μm, pass photolithography through No. 5 mask plate, remove the positive resist after development, and obtain a sacrificial layer pattern, and then cure the glass sheet at 260°C for 1 hour.

10) Under a vacuum of 5×10 ^-5 Torr, evaporate and deposit an aluminum-glass alloy film containing 4% glass and a thickness of 0.5 μm on the surface of the glass sheet.

11) Negative photolithography No. 6 mask plate, put the glass piece in the H ₃ PO ₄ solution with a concentration ≥ 85% at 70°C, etch the aluminum-glass alloy film until the bubbles emerging from the phosphoric acid solution are very weak, forming The bridging membrane and glass slides were quickly cleaned with deionized water.

12) Plasma etching to remove the negative resist and sacrificial layer, the plasma etching power, oxygen flow rate and nitrogen flow rate are 50w, 60ml/s and 2.8ml/s respectively, to obtain eight suspended support bridge membrane structures and 16 cantilevers The membrane structure of the beam bridge is the movable contact piece of the MEMS switch.

Claims (1)

1. a preparation method of a reconfigurable matching network matcher containing a MEMS switch is characterized in that, a total of six mask plates are used, and the concrete steps are as follows: 1) Put a 500μm thick glass sheet in a mixture of H ₂ O ₂ :H ₂ SO ₄ =1:1, wash it with deionized water, then put the glass sheet in No. 1 cleaning solution and boil for 10 minutes, deionized Washing with water, the No. 1 cleaning solution is a mixture of NH ₄ OH, H ₂ O ₂ and deionized water, and finally put the glass sheet into the No. 2 cleaning solution to boil, rinse with deionized water, spin dry, and dry , the No. 2 cleaning solution is a mixture of HCl, H ₂ O ₂ and deionized water; 2) On the silica glass layer, a chromium layer and a gold layer are sequentially evaporated and deposited, and the thicknesses are respectively with The process conditions are: the temperature and vacuum in the evaporation furnace are 250°C and 10×10 ^-5 Torr, respectively; 3) Cover the positive glue on the surface of the area outside the No. 1 mask pattern of the glass sheet through the No. 1 mask plate, leave the pattern that needs to be electroplated, electroplate gold to form the input end, output end, bridge pier and bias pad, and electroplate The thickness of the layer is 2μm, and the glue is removed to prepare for the next operation; 4) The method of positive resist lithography No. 1 mask plate is photolithographically etched No. 2 mask plate and No. 3 mask plate respectively, and electroplating gold to form ground wire, signal wire, bias voltage wire, and the thickness is 2 μm respectively. In addition, the electroplating Increase the thickness of the input and output terminals, bias pads and bridge piers from 2 μm to 3 μm, remove the glue and prepare for the next operation; 5) Negative photolithography No. 2 mask plate, after development, place it in an oven at 120°C for 30 minutes to harden the film, then plasma etch for 20 seconds, and finally etch away the gold layer and titanium layer of the unplated part in sequence at room temperature , keep the input and output terminals, ground wires, signal wires, bias pads, bias wires and bridge piers, the formula of the solution for corroding gold is KI: I ₂ : H ₂ O = 20g: 6g: 100ml, the solution for corroding chromium is phosphoric acid ; 6) Oxygen plasma etching is used to remove the glue, and the etching power, oxygen flow rate, and etching time are respectively 50W, 60ml/min, and 20 seconds; 7) Deposit a silicon nitride film with a thickness of 0.3 μm on the surface of the glass sheet by chemical vapor deposition, and the flow rate of ammonia gas, the flow rate of glassane and the temperature are respectively 28ml/min, 560ml/min and 280°C; 8) Cover the pattern on No. 4 board with positive resist to protect the required glass nitride film, and then use SF ₆ gas plasma to etch the glass nitride film. The power, flow rate of SF ₆ gas and etching time are 50w, 2.4 ml/s and 1 minute 20 seconds; 9) At the speed of 2000 rpm, spin-coat a layer of polyimide film with a thickness of Spin-coat a positive resist with a thickness of 2 μm, pass through No. 5 mask plate photolithography, remove the positive resist after development, and obtain a sacrificial layer pattern, and then cure the glass sheet at 260°C for 1 hour; 10) Under a vacuum degree of 5×10 ^-5 Torr, evaporate and deposit an aluminum-glass alloy film containing 4% glass and a thickness of 0.5 μm on the surface of the glass sheet; 11) Negative photolithography No. 6 mask plate, place the glass sheet in a H ₃ PO ₄ solution with a concentration ≥ 85% at 70°C, etch the aluminum-glass alloy film until the bubbles emerging from the phosphoric acid solution are very weak, forming The bridging membrane and glass slides were quickly cleaned with deionized water; 12) Plasma etching to remove the negative resist and sacrificial layer, the plasma etching power, oxygen flow rate and nitrogen flow rate are 50w, 60ml/s and 2.8ml/s respectively, to obtain six suspended support bridge membrane structures and twelve Cantilever beam bridge membrane structure, which is the movable contact piece of MEMS switch.