CN101763987A - RF MEMES switch and manufacture method thereof - Google Patents
RF MEMES switch and manufacture method thereof Download PDFInfo
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- CN101763987A CN101763987A CN200910263942A CN200910263942A CN101763987A CN 101763987 A CN101763987 A CN 101763987A CN 200910263942 A CN200910263942 A CN 200910263942A CN 200910263942 A CN200910263942 A CN 200910263942A CN 101763987 A CN101763987 A CN 101763987A
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Abstract
The invention discloses an RF MEMES switch and a manufacture method thereof, which are applied to the field of MEMS switches. The RF MEMES switch comprises a substrate, a signal transmission line, lower electrodes, a dielectric layer, suspending metal and a bridge type metal electrode, wherein the substrate is provided with an insulating layer; the signal transmission line and the lower electrodes are formed on the substrate; the dielectric layer and the suspending metal are sequentially deposited on the signal transmission line; the bridge type metal electrode is anchored on and connected to the lower electrodes; the bridge type metal electrode and the suspending metal are opposite to each other, a clearance is reserved between the bridge type metal electrode and the suspending metal, and the signal transmission line is positioned between the two lower electrodes. The RF MEMES switch is characterized in that drive electrodes coated with dielectric layers are arranged between the two lower electrodes on the substrate and both sides of the signal transmission line. The structure prevents the arc effect caused by the direct-current biasing function and solves the problem of invalid switch in a contact point of the suspending metal and the bridge type metal electrode due to melting and adhesion of metal, thereby prolonging the service life of the switch.
Description
Technical field
The present invention relates to a kind of MEMS element, relate in particular to the radio-frequency micro electromechanical switch (RF MEMS Switch) and the manufacture method thereof of the high capacitance ratio that a kind of MEMS of utilization process technology makes.
Background technology
Because mems switch has low-loss, low-power consumption, good isolation, good linearity, microminiaturization and high integration, have the performance of high-quality more and be widely used in the wireless communication system than GaAs FET switch or PIN type diode switch.
General RF mems switch mainly be by fixed electrode, with respect to the traveling electrode of fixed electrode setting and be arranged on traveling electrode and fixed electrode between dielectric constitute.When between traveling electrode and fixed electrode, applying voltage, thereby between will produce electrostatic force traveling electrode is attracted on the fixed electrode, make two distance between electrodes that change take place.Because change has taken place distance between electrodes, therefore, electric capacity changes, i.e. change has taken place in impedance, thereby signal is switched on or ends.Therefore, the RF mems switch is also referred to as the capacitive character mems switch, is also referred to as static driven formula mems switch according to its type of drive.
The RF performance is the capacity ratio (C by on off state for switch
Down/ C
Up) determined, this ratio formula is as follows:
Wherein, d
AirBe the space length between two traveling electrodes and fixed electrode, d
DielBe dielectric thickness, ε
rBe dielectric dielectric constant, A
OverlapIt is the coupling area of traveling electrode and fixed electrode.Capacity ratio is high more, and the RFMEMS switch performances is good more.In order to increase capacity ratio, publication number is that the patent document of CN 1922755A discloses a kind of capacitive character mems switch, this switch fixing one deck suspension metal on dielectric, the suspension metal has bigger relative coupling area with fixed electrode, when traveling electrode is subjected to electrostatic force sucking action and suspension Metal Contact,, be equivalent to the coupling area that has increased between traveling electrode and fixed electrode owing to be in equipotential, therefore greatly improve capacity ratio, improved the performance of capacitive character mems switch.But, because fixed electrode is a drive electrode is again signal transmssion line, the suspension metal is positioned on the signal transmssion line, therefore, in use because the electric arc effect that the effect of Dc bias produces can make metal contact melt, thereby traveling electrode and suspension metal are sticked together, make switch failure.In addition, the dielectric large tracts of land covers fixed electrode, in use because there is the electric charge injection effect in dielectric, can produce electrostatic force between dielectric and traveling electrode, and traveling electrode can not return to initial position under the effect of electrostatic force, make switch failure.
Summary of the invention
The technical problem to be solved in the present invention is by increasing independent drive electrode, the problem that the electric arc effect can make hard contact melt takes place after applying driving voltage in solution on traveling electrode and suspension metal, thereby reach the optimization switch performance, prolong the purpose of switch life.
For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of RF mems switch, its structure comprises: the substrate of tape insulation layer, signal transmssion line and the bottom electrode of preparation on insulating barrier, the dielectric layer and the suspension metal that deposit successively on the signal transmssion line, the bridge-type metal electrode of anchor connection on bottom electrode; And the with a gap setting relative of bridge-type metal electrode with the suspension metal, signal transmssion line is between two bottom electrodes; Key is: preparation has the drive electrode that is covered with dielectric layer between two bottom electrodes on the substrate and in the signal transmssion line both sides.Dielectric layer on the drive electrode is the surface that block structure is distributed in drive electrode.
The preparation method of above-mentioned RF mems switch, its step comprises:
1) adopt sputtering technology to prepare signal transmssion line and bottom electrode having on the substrate of insulating barrier;
2) deposition is prepared the dielectric layer on the signal transmssion line;
3) sputter prepares the suspension metal;
4) adopt sacrifice layer process to prepare the bridge-type metal electrode;
Key is: prepare drive electrode in preparation signal transmssion line and bottom electrode.
Adopt the beneficial effect that technique scheme produced to be: owing to adopt independent drive electrode setting, drive electrode is separated with signal transmssion line, make radiofrequency signal and DC driven signal separate like this, avoided because the electric arc effect that the effect of Dc bias causes, solved the place, contact of suspension metal and bridge-type metal electrode because metal melts, adhesion makes the problem of switch failure, thereby prolonged the useful life of switch.In addition, the contact area that the lump-shaped media layer has reduced dielectric layer and bridge-type metal electrode is set on drive electrode, can effectively prevents because bridge-type metal electrode that the electric charge injection effect causes and the adhesion between dielectric layer.
Description of drawings
Fig. 1 is the cross-sectional schematic of switch internal structure of the present invention;
Fig. 2 is that structure shown in Figure 1 applies the structural representation after the Dc bias on off state changes;
Among the figure: 1 substrate, 2 insulating barriers, 3 signal transmssion lines, 4 bottom electrodes, 5 dielectric layers, 6 suspension metals, 7 drive electrodes, 8 hard contacts, 9 bridge-type metal electrodes.
Embodiment
Below in conjunction with accompanying drawing the present invention is described in further detail.
A kind of RF mems switch provided by the invention, its structure comprises: the substrate 1 of tape insulation layer 2, be generally silicon chip, signal transmssion line 3 and the bottom electrode 4 of preparation on insulating barrier 2, the dielectric layer 5 and the suspension metal 6 that deposit successively on the signal transmssion line 3, the bridge-type metal electrode 9 of anchor connection on bottom electrode 4; Bridge-type metal electrode 9 and the 6 relative and settings with a gap of suspension metal, signal transmssion line 3 is between two bottom electrodes 4; Key is: preparation has the drive electrode 7 that is covered with dielectric layer 5 between two bottom electrodes 4 on the substrate 1 and in signal transmssion line 3 both sides.Dielectric layer 5 on the drive electrode 7 is the surface that block structure is distributed in drive electrode 7.The block structure of dielectric layer 5 can have any shape, and should be as far as possible little of to reduce the contact area of dielectric layer 5 and bridge-type metal electrode 9, reaches the influence that effective reduction dielectric layer 5 electric charge injection effects produce switch performance.
Above-mentioned suspension metal 6 can be rectangle, square or other shapes, be preferably the thin H shape in wide centre, two ends here, thereby increasing between bridge-type metal electrode 9 and the signal transmssion line 3 in the coupling area, also reduced the contact area of bridge-type metal electrode 9, improved switch performances with suspension metal 6.Suspension metal 6 adopts Ti/Pt complex metal layer structure, and lower floor is that Ti contacts as adhesion layer and dielectric layer 5, and the upper strata is that Pt contacts with bridge-type metal electrode 9 as contact layer, and thickness is
Adopting Pt and not adopting Au is consideration for reliability, switch in the course of the work, owing to exist impact, contact zone to be easy to generate problems such as material transfer, pitting attack, hardness and the fusing point of Pt are higher, so better reliability during Metal Contact.
As preferred version further, plated metal contact 8 on above-mentioned suspension metal 6, hard contact 8 is preferably rectangle structure, also can be other shapes, assurance along the size of bridge-type metal electrode 9 Widths greater than bridge-type metal electrode width 9, thereby contact fully with hard contact 8 when guaranteeing that bridge-type metal electrode 9 is drop-down.More exquisite in the selection of material, hard contact 8 is because pitting attack appears in frequent collision and generation electric arc effect easily, material transfer and little fuse effect cause switch failure, therefore must adopt low contact resistance, high-melting-point, the metal or alloy material of good in oxidation resistance.Traditional metal material such as Al, Cu, Au etc. adopt Pt (platinum) because fusing point and hardness can't meet the demands than low, Ru (ruthenium), Rh (rhodium), Ir fusing point height such as (iridium), hardness metal material moderate and good in oxidation resistance is comparatively suitable.Preferably adopt Pt as hard contact 8 materials in the present embodiment.In addition, owing to increased hard contact 8, make and be higher than the height of dielectric layer 5 on the drive electrode 7 by the height of hard contact 8 (difference in height generally is controlled in 0.5 μ m～1 mu m range, difference in height too conference influences the planarization of bridge-type metal electrode), therefore, when bridge-type metal electrode 9 is drop-down owing to the effect that is subjected to electrostatic force, can fully contact with hard contact 8.
Concrete operation principle of the present invention is:
Referring to Fig. 2, add direct voltage this moment is 0V, and bridge-type metal electrode 9 is in the nature vacant state, and electric current transmits on signal transmssion line 3.When after applying Dc bias on drive electrode 7 and the bottom electrode 4, referring to shown in Figure 3, because bridge-type metal electrode 9 is anchored on bottom electrode 4, bottom electrode 4 is a ground wire, bridge-type metal electrode 9 and bottom electrode 4 are in the same point position, therefore, 7 of bridge-type metal electrode 9 and drive electrodes produce electrostatic force, bridge-type metal electrode 9 is moved down also contact with the dielectric layer 5 of drive electrode 7.Because drive electrode 7 is distributed in the both sides of signal transmssion line 3, and also has layer of metal contact 8 on the suspension metal 6, therefore causing between drive electrode 7 and the hard contact 8 has a difference in height, and this difference in height can guarantee that 8 formation well contact bridge-type metal electrode 9 with hard contact.Can make the electric capacity between bridge-type metal electrode 9 and the signal transmssion line 3 increase tens times after bridge-type metal electrode 9 and hard contact 8 contacts, this moment, impedance between the two sharply reduced, again because bridge-type metal electrode 9 forms ground wire by bottom electrode 4, therefore form the short circuit of microwave frequency, ended the transmission of signal.Bridge-type metal electrode 9 returns to initial condition under the effect of elastic-restoring force after cancelling Dc bias, realizes the break-make of signal thus.
Below be the concrete manufacturing process steps of RF mems switch shown in the present:
1) thermal oxidation on the substrate 1: selecting silicon for use is substrate 1 material, and as insulating barrier 2, thickness is the employing thermal oxidation technology at High Resistivity Si superficial growth silica
The purpose of preparation silica is because switch drive voltage is applied between bottom electrode and the silicon chip center line, therefore must carry out electricity and isolate between two lines.
2) preparation of signal transmssion line 3 and drive electrode 7: adopt sputter to prepare the Ti/Au metal structure, thickness is
In order to reduce the influence of skin effect, adopt electroplating technology thickening Au layer, signal transmssion line 3 gross thickness are 2 μ m～5 μ m;
3) preparation of dielectric layer 5: because the existence of metal, adopt PECVD low temperature to prepare dielectric layer 5 films (silicon nitride or silica), the thickness that as far as possible reduces dielectric layer 5 can increase the switching capacity ratio, however since dielectric layer cross and thin the pin hole problem can occur, deposition thickness can not less than
And dielectric layer 5 must be able to bear driving voltage, and (10V～60V) and do not puncture is so according to above requirement, the thickness of dielectric layer 5 is
4) preparation of suspension metal 6: adopt sputter to prepare Ti/Pt complex metal layer structure, lower floor is that Ti contacts as adhesion layer and dielectric 5, and the upper strata is that Pt contacts with bridge-type metal electrode 9 as contact layer, and thickness is
5) preparation of hard contact 8: sputter Pt metal level, photoetching, etching are peeled off and are formed hard contact 8;
6) preparation of sacrifice layer: alternative sacrificial layer material is a lot, comprise metal, oxide and organic substance, polysilicon membrane also is the sacrificial layer material of using always, owing to have dielectric in the structure of the present invention, metal and silicon, so preferred photoresist is as sacrificial layer material, the thickness of photoresist is selected the type of photoresist and the revolution that rotation applies photoresist according to the requirement of bridge-type metal electrode 9 flying heights.
7) preparation of anchor point: directly photoetching, etching are finished the anchor point preparation on sacrifice layer.
8) preparation of bridge-type metal electrode 9: adopt the material of Au as bridge-type metal electrode 9, this is because the chemical property of Au is stable.Sputter Au metal level, etches the preparation of bridge-type metal electrode 9 at photoetching.
9) release of sacrifice layer: adopted dry technique, promptly the dry plasma technology is removed sacrifice layer, realizes the release of micro mechanical structure.
Wherein, the method for photoetching, etching, sputter, photoresist type, coating photoresist is content well-known to those skilled in the art, does not repeat them here.
Claims (9)
1. RF mems switch, its structure comprises: the substrate (1) of tape insulation layer (2), signal transmssion line (3) and the bottom electrode (4) of preparation on insulating barrier (2), the dielectric layer (5) and the suspension metal (6) that deposit successively on the signal transmssion line (3), the bridge-type metal electrode (9) of anchor connection on bottom electrode (4); Bridge-type metal electrode (9) and with a gap setting relative with suspension metal (6), signal transmssion line (3) is positioned between two bottom electrodes (4); It is characterized in that: preparation has the drive electrode (8) that is covered with dielectric layer (5) between two bottom electrodes (4) and in signal transmssion line (3) both sides.
2. RF mems switch according to claim 1 is characterized in that the dielectric layer (5) on the drive electrode (7) is the surface that block structure is distributed in drive electrode (7).
3. RF mems switch according to claim 1, the metal (6) that it is characterized in that suspending is H shape.
4. according to claim 1 or 3 described RF mems switches, it is characterized in that above-mentioned suspension metal (6) adopts Ti/Pt complex metal layer structure, Ti is as adhesion layer, and Pt is as contact layer.
5. according to claim 1 or 3 described RF mems switches, it is characterized in that going up plated metal contact (8) at above-mentioned suspension metal (6), hard contact (8) material therefor is the Pt material.
6. RF mems switch according to claim 1, the length that it is characterized in that above-mentioned bridge-type metal electrode (9) are 200 μ m～400 μ m, and width is 25 μ m～180 μ m, and bridge-type metal electrode (9) surface is provided with runs through the thick perforate of bridge.
7. RF mems switch according to claim 1, the thickness that it is characterized in that signal transmssion line (3) and bottom electrode (4) are 2 μ m～5 μ m.
8. the preparation method of the described RF mems switch of claim 1, its step comprises:
1) goes up the employing sputtering technology at the substrate that is covered with insulating barrier (2) (1) and prepare signal transmssion line (3) and bottom electrode (4);
2) deposition is prepared the dielectric layer (5) on the signal transmssion line (3);
3) sputter prepares suspension metal (6);
4) adopt sacrifice layer process to prepare bridge-type metal electrode (9);
It is characterized in that: in preparation signal transmssion line (3) and bottom electrode (4), prepare drive electrode (8).
9. the preparation method of RF mems switch according to claim 8 is characterized in that the step at step 3) back increase preparation hard contact (8).
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103943417A (en) * | 2014-04-09 | 2014-07-23 | 苏州锟恩电子科技有限公司 | Capacitive RF MEMS switch |
| CN103943421A (en) * | 2014-04-18 | 2014-07-23 | 苏州锟恩电子科技有限公司 | Driving electrode plate and capacitor upper electrode plate separating type RF MEMS switch |
| CN103943418A (en) * | 2014-04-14 | 2014-07-23 | 苏州锟恩电子科技有限公司 | Elastic micro-bridge type RF MEMS switch |
| CN104150434A (en) * | 2014-08-19 | 2014-11-19 | 中国电子科技集团公司第五十四研究所 | Preparation method of millimeter wave RF-MEMS (radio frequency-micro-electromechanical system) switch |
| CN106373830A (en) * | 2016-11-21 | 2017-02-01 | 清华大学 | Capacitive radio-frequency micro-electromechanical system switch with signal lines and drive lines separated |
| WO2021237770A1 (en) * | 2020-05-26 | 2021-12-02 | 瑞声声学科技(深圳)有限公司 | Mems capacitive switch and electronic device |
| WO2023082187A1 (en) * | 2021-11-12 | 2023-05-19 | 京东方科技集团股份有限公司 | Phase shifter |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US6635506B2 (en) * | 2001-11-07 | 2003-10-21 | International Business Machines Corporation | Method of fabricating micro-electromechanical switches on CMOS compatible substrates |
| US20070278075A1 (en) * | 2004-07-29 | 2007-12-06 | Akihisa Terano | Capacitance Type Mems Device, Manufacturing Method Thereof, And High Frequency Device |
| KR100661347B1 (en) * | 2004-10-27 | 2006-12-27 | 삼성전자주식회사 | Micro thin film structure, micro electro mechanical system switch using the same and manufacturing method of them |
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2009
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103943417A (en) * | 2014-04-09 | 2014-07-23 | 苏州锟恩电子科技有限公司 | Capacitive RF MEMS switch |
| CN103943418A (en) * | 2014-04-14 | 2014-07-23 | 苏州锟恩电子科技有限公司 | Elastic micro-bridge type RF MEMS switch |
| CN103943421A (en) * | 2014-04-18 | 2014-07-23 | 苏州锟恩电子科技有限公司 | Driving electrode plate and capacitor upper electrode plate separating type RF MEMS switch |
| CN104150434A (en) * | 2014-08-19 | 2014-11-19 | 中国电子科技集团公司第五十四研究所 | Preparation method of millimeter wave RF-MEMS (radio frequency-micro-electromechanical system) switch |
| CN104150434B (en) * | 2014-08-19 | 2016-09-21 | 中国电子科技集团公司第五十四研究所 | A kind of preparation method of millimeter wave RF mems switch |
| CN106373830A (en) * | 2016-11-21 | 2017-02-01 | 清华大学 | Capacitive radio-frequency micro-electromechanical system switch with signal lines and drive lines separated |
| WO2021237770A1 (en) * | 2020-05-26 | 2021-12-02 | 瑞声声学科技(深圳)有限公司 | Mems capacitive switch and electronic device |
| WO2023082187A1 (en) * | 2021-11-12 | 2023-05-19 | 京东方科技集团股份有限公司 | Phase shifter |
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| CN101763987B (en) | 2012-05-23 |
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