CN104299921A

CN104299921A - Manufacturing method of high-temperature metal micro electrode for large-power RF MEMS switch

Info

Publication number: CN104299921A
Application number: CN201410452346.5A
Authority: CN
Inventors: 张洪泽; 李志宏
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2014-09-05
Filing date: 2014-09-05
Publication date: 2015-01-21

Abstract

The invention discloses a manufacturing method of a high-temperature metal micro electrode for a large-power RF MEMS switch. The manufacturing method includes eight steps. The high-temperature refractory metal electrode is adopted to realize large-power processing capacity for the RF MEMS switch. Usually, high-temperature refractory metal is high in hardness and internal stress, the Yong's modulus of iridium and ruthenium is six to seven times larger than that of gold, and the Yong's modulus of platinum is two times larger than that of gold. In order to realize high reliability of the RF MEMS switch, the high-temperature metal micro electrode for the RF MEMS switch needs to have a smooth surface and edges. In order to resolve the problem of generation of internal stress of platinum group metal, a specially designed stripping process for two layers with a metal layer is adopted, an added buffering layer is used for reducing the internal stress of upper-layer platinum group high-temperature melting metal, and the smooth surface and edges of the high-temperature metal micro electrode are realized. The performance and reliability of the device are improved.

Description

A kind of preparation method of the high-temperature metal microelectrode for high-power RF mems switch

Technical field

The present invention relates to semiconductor microactuator process technology, be specifically related to a kind of preparation method of the high-temperature metal microelectrode for high-power RFMEMS switch.

Background technology

RF mems switch is a kind of New-type radio-frequency device based on micro electro mechanical system (MEMS) technology, with traditional radio-frequency (RF) switch (PIN switch, relay etc.) compare that to have insertion loss low, quiescent dissipation is low, the plurality of advantages such as isolation is high, and volume is little, and application band is wide, at phase array assembly, the radio frequency applications such as tunable antenna show huge application potential.High-power RF mems switch be the key areas of present stage RF mems switch exploitation, the practical and national defense applications of RF mems switch has very important position.Solve high-power RF mems switch and process the series of problems in preparing to realizing the practical of high-power RF mems switch, the technical strength strengthening China's national defense electronics has very important meaning.

In order to improve the power handling capability of RF mems switch, we have selected high temperature refractory as the basic material of the microelectrode of high-power RF mems switch.Platinum group metal is commonly high temperature refractory, wherein the fusing point 1769 DEG C of metal platinum, the fusing point of metal iridium 2443 DEG C, the fusing point of metal Ru 2334 DEG C, and the fusing point of metal osmium is 3033 DEG C; And there is very strong chemical inertness platinum group metal, corrosion resistance is very strong, this feature is conducive to the surface-stable realizing switch electrode, and to improve the reliability of device, but the problem brought equally is the micro-structural that cannot realize platinum group metal by the method for conventional etch.Simultaneously the hardness of high temperature refractory is very high and internal stress is large especially, the Young's modulus of metal iridium and metal Ru is than golden large 6 ~ 7 times, the Young's modulus of metal platinum is than golden large 2 times, in order to solve the problem that platinum group metal internal stress produces, the resilient coating increased in the present invention is for reducing the internal stress of platinum group metal, upper strata.Simultaneously in order to realize the high reliability of device, the high-temperature metal microelectrode being applied to RF mems switch also needs smooth surface and edge, and this is that Conventional processing methods is difficult to realize.

Summary of the invention

In order to realize the platinum family high temperature refractory microelectrode structure being applied to high-power RF mems switch, the present invention proposes a kind of preparation method being applied to high-power RF mems switch high-temperature metal microelectrode.

This method can complete the preparation of high-temperature metal microelectrode on multiple substrate, as glass, and quartz, High Resistivity Si, GaAs, gallium nitride etc.

The first step, the substrate disk that semiconductor grade is smooth grows the certain thickness metal be easily etched of one deck, as copper, and aluminium, titanium etc.; Method can be sputtering, and evaporation, MOCVD etc., as shown in Fig. 1 (a).

Second step, first layer metal carries out photoetching.The photoresist stayed is as the mask of post processing.

3rd step, the metal level grown with corresponding wet etching liquid or dry etching gas etching ground floor.And by controlling etch thicknesses, realize specific over etching.Form the eaves structure of upper strata photoresist, as shown in Fig. 1 (b).

4th step, the adhesion layer of sputtering or evaporation microelectrode, optional chromium, tungsten, titanium, aluminium etc., as shown in Fig. 1 (c).

5th step, the resilient coating of sputtering or evaporation microelectrode, optional copper, gold, plumbous, iron etc., as shown in Fig. 1 (d).

6th step, the high temperature refractory layer of sputtering or evaporation microelectrode, optional platinum, iridium, ruthenium, rhodium, osmium etc., as shown in Fig. 1 (e).

7th step, removes clean patterned photoresist with organic solvent, completes stripping technology, as shown in Fig. 1 (f).

8th step, removes the metal of ground floor growth, as shown in Fig. 1 (g) with corresponding wet etching liquid or dry etching gas.

So far, the high-temperature metal microelectrode being applied to high-power RF mems switch completes processing preparation.

Accompanying drawing explanation

Fig. 1 is the technique generalized section of the preparation method of the high-temperature metal microelectrode being applied to RF mems switch;

Fig. 2 is the scanning electron microscope image with the high-temperature metal microelectrode at smooth surface and edge being applied to RF mems switch adopting the inventive method to prepare;

Fig. 3 is applied to the schematic diagram of the preparation structure of the high-temperature metal microelectrode of RF mems switch.

Wherein 1 is substrate, and 2 is first layer metal, and 3 is photoresist, and 4 is adhesion layer, and 5 is resilient coating, and 6 is high temperature refractory layer.

Beneficial effect

Actual experiment shows, after RF mems switch have employed high-temperature metal microelectrode prepared by the inventive method, power handling capability was significantly improved than previously adopting the RF mems switch of traditional gold electrode, and process yield there has also been remarkable lifting.

Embodiment

Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following examples for illustration of the present invention, but can not be used for limiting the scope of the invention.

The first step, at High Resistivity Si surface sputtering layer of metal copper, preferred thickness is 500nm.

Second step, spin coating photoresist on first layer metal exposure imaging.

3rd step, utilizes copper corrosion liquid etching copper 500nm.

4th step, sputtering adhesion layer chromium 10nm.

5th step, sputtering resilient coating aluminium 50nm.

6th step, sputtering high temperature refractory layer rhodium 200nm.

7th step, utilizes acetone to remove photoresist and metal level thereon.

8th step, utilizes copper corrosion liquid to remove copper.

So far the high-temperature metal microelectrode being applied to high-power RF mems switch completes preparation.

This embodiment demonstrates the feasibility being applied to the high-temperature metal microelectrode preparation method of high-power RF mems switch that we propose.

Last it is noted that obviously, above-described embodiment is only for the application's example is clearly described, and the restriction not to execution mode.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here exhaustive without the need to also giving all execution modes.And thus the apparent change of amplifying out or variation be still among the protection range of the application's type.

Claims

1. for the preparation method of the high-temperature metal microelectrode of high-power RF mems switch, it is characterized in that, described method step is as follows:

The first step, the substrate disk that semiconductor grade is smooth adopts common process to grow the metal of one deck, and described metal comprises copper, aluminium and titanium; Described preparation of metals technique comprises sputtering, evaporation and organic chemical vapor deposition;

Second step, first layer metal carries out photolithography patterning, and the photoresist stayed is as the mask of subsequent technique;

3rd step, the metal level grown with corresponding wet etching liquid or dry etching gas etching ground floor, and by controlling etch thicknesses, realize over etching, form the eaves structure of upper strata photoresist;

4th step, the adhesion layer of sputtering or evaporation microelectrode, material therefor is selected from chromium, tungsten, titanium or aluminium;

5th step, the resilient coating of sputtering or evaporation microelectrode, material therefor is selected from copper, gold, lead or iron;

6th step, the high temperature refractory layer of sputtering or evaporation microelectrode, material therefor is selected from platinum, iridium, ruthenium, rhodium, tungsten or osmium;

7th step, the clean patterned photoresist of removal of solvents, completes the metal-stripping on photoresist with photoresist;

8th step, removes the metal of ground floor growth with corresponding wet etching liquid or dry etching gas.

2. preparation method according to claim 1, is characterized in that: described preparation method can complete the preparation of high-temperature metal microelectrode on multiple substrate, and described substrate comprises glass, quartz, High Resistivity Si, GaAs and gallium nitride.

3. preparation method according to claim 1, is characterized in that: described method can prepare surperficial and that edge is all very smooth high-temperature metal microelectrode, may be used for the preparation of high-power RF mems switch device.