A kind of SAW resonator of novel electrode structure
阅读说明：本技术 一种新型电极结构的声表面波谐振器 (A kind of SAW resonator of novel electrode structure ) 是由 王韬 汤正杰 于 2019-09-22 设计创作，主要内容包括：本发明属于声表面波器件领域,具体为一种新型电极结构的声表面波谐振器。本发明通过加入下电极,设计优化上电极结构,上电极采用周期性等间距排列的N根矩形金属条,将矩形金属条通过金属汇流条相连通,其中N≥2。其中上电极一个周期单元只需一根矩形金属条电极,传统叉指电极结构的声表面波谐振器中一个周期单元有两根矩形金属条电极,在相同的矩形金属条电极宽度下,本发明声表面波谐振器的周期比叉指电极结构谐振器的周期小一倍,本发明可以在相同光刻线宽条件下,实现更高的谐振频率；并且能减小谐振器尺寸,增加系统的集成度。(The invention belongs to SAW device field, specially a kind of SAW resonator of novel electrode structure.Rectangular metal item is connected, wherein N >=2 by the present invention by the way that lower electrode, design optimization top electrode structure, top electrode is added using the N root rectangular metal item periodically equidistantly arranged by metal bus bars.Wherein top electrode a cycle unit only needs a rectangular metal strip electrode, a cycle unit has two rectangular metal strip electrodes in the SAW resonator of traditional interdigitated electrode structure, under identical rectangular metal strip electrode width, the period of SAW resonator of the present invention is one times smaller than the period of interdigitated electrode structure resonator, the present invention can realize higher resonance frequency under the conditions of identical lithographic line width；And resonator dimensions can be reduced, increase the integrated level of system.)
1. a kind of SAW resonator of novel electrode structure, is successively folded by substrate, hearth electrode, piezoelectric membrane and top electrode Add composition, it is characterised in that:
The top electrode is made of the N root rectangular metal strip electrode periodically equidistantly arranged, wherein N >=2, rectangular metal item electricity Pole is connected by metal bus bars, and a cycle unit of top electrode has and an only rectangular metal strip electrode；Rectangle gold The width Le for belonging to strip electrode is 25%P≤Le≤50%P, and length is 10P to 100P；Wherein P is top electrode a cycle unit Length, 0.1 micron≤P≤100 micron.
2. the SAW resonator of novel electrode structure as described in claim 1, it is characterised in that: the material of the piezoelectric membrane Material is aluminium nitride AIN or lithium niobate LiNbO3, the thickness h of piezoelectric membranepFor 10%P≤hp≤ 80%P.
3. the SAW resonator of novel electrode structure as described in claim 1, it is characterised in that: the hearth electrode and power on The material of pole is molybdenum Mo, aluminium Al, gold Au or platinum Pt, two electrodes with a thickness of 1%P~10%P, but hearth electrode thickness hbWith power on Pole thickness heIt can be equal or unequal.
Technical field
The invention belongs to SAW device field, specially a kind of SAW resonator of novel electrode structure.
Background technique
SAW device has extensive purposes, such as the detection of temperature dynamic detection, Pressure behaviour, mobile communication etc. Deng.For SAW device using SAW resonator as basic unit, the principle of SAW resonator is in piezoelectric material table Electric signal is transformed into acoustical signal, excitation is spoken using the inverse piezoelectric effect of piezoelectric material by the electric field that face applies a cycle Surface wave.
It is to grow one layer of week in piezoelectric material surface that current SAW resonator, which is used to excite the method for surface acoustic wave, Phase property interdigital electrode, i.e. interdigital transducer.The velocity of sound and sound table of the resonance frequency of SAW resonator with surface acoustic wave The wavelength of surface wave is related, and the wavelength of surface acoustic wave is equal with the period of interdigital transducer, and formula can be written as F=V/P, wherein F is the resonance frequency of SAW resonator, and V is the velocity of sound of surface acoustic wave, and P is the period of interdigital transducer.
Since the velocity of sound V of surface acoustic wave is that device material itself is determined, in the case where device material determines, Velocity of sound V just has determined.And in order to improve the resonance frequency F of SAW resonator, it can only be by reducing interdigital transducer Period is realized, i.e., synchronous to reduce inter-digital electrode width and electrode gap width；And the smaller interdigital transducer of fabrication cycle needs The higher lithographic equipment of photolithography limitation is wanted, to improve the requirement to lithographic equipment.
Since the integrated level of present integrated system is higher and higher, the size of individual devices in integrated system is required also more Height, and the size of current SAW resonator also has the space further reduced.
Summary of the invention
For existing high-frequency sound surface wave resonator on the make in the high request of lithographic accuracy and integrated system To the high request of device size；Smaller in order under the conditions of limited photolithography limitation, produce area, resonance frequency is higher SAW resonator, the present invention provides a kind of SAW resonators of novel electrode structure.
Specific technical solution is as follows:
A kind of SAW resonator of novel electrode structure by substrate, hearth electrode, piezoelectric membrane and top electrode successively Superposition is constituted.
The top electrode is made of the N root rectangular metal strip electrode periodically equidistantly arranged, wherein N >=2, rectangular metal Strip electrode is connected by metal bus bars.The a cycle unit of top electrode has and an only rectangular metal strip electrode, square The width Le of shape metal strip electrode is 25%P≤Le≤ 50%P, length are 10P to 100P；Wherein P is top electrode a cycle 0.1 micron≤P≤100 micron of length；That is metallization ratio η of the top electrode in a cycle unit be 25%P≤η≤ 50%P.
Further, the material of the piezoelectric membrane is aluminium nitride (AIN) or lithium niobate (LiNbO3), the thickness of piezoelectric membrane Spend hpFor 10%P≤hp≤ 80%P.
Further, the hearth electrode and the material of top electrode be molybdenum (Mo), aluminium (Al), golden (Au) or platinum (Pt), two electricity The thickness range of pole is 1%P~10%P, hearth electrode thickness hbWith top electrode thickness heIt can be equal or unequal.
The SAW resonator of the novel electrode structure generates periodically after receiving electric signal in piezoelectric thin film layer Electric field, to excite surface acoustic wave by inverse piezoelectric effect.Its hearth electrode is deposited on substrate table by magnetically controlled sputter method Then face grows piezoelectric membrane on hearth electrode surface using atomic layer deposition coating technique, recycles magnetically controlled sputter method growth The pattern of top electrode, is finally transferred on metallic film, by etching technics in gold by one layer of metallic film by photoetching technique Belong to and etches the preparation that top electrode pattern completes SAW resonator on film.
Top electrode structure designed by the present invention, using the N root rectangular metal strip electrode periodically equidistantly arranged, wherein Rectangular metal strip electrode is connected by N >=2 by metal bus bars；Its top electrode a cycle unit has and an only square Shape metal strip electrode, and a cycle unit has two rectangular metal items in the SAW resonator of traditional interdigitated electrode structure Electrode, so the resonator of the rectangular metal strip electrode width and interdigitated electrode structure of the SAW resonator of this design When rectangular metal strip electrode width is equal, of the invention to power on polar period one times smaller than the period of interdigitated electrode structure resonator, Since the resonance frequency F of SAW resonator and the period P of electrode are inversely proportional, so when SAW resonator of the present invention It is of the invention when the width of rectangular metal strip electrode is equal with the width of rectangular metal strip electrode of interdigitated electrode structure resonator Resonance frequency can be doubled than the resonance frequency of interdigital electrode transducer architecture resonator；Surface acoustic wave of the invention simultaneously is humorous In periodicity having the same, surface acoustic wave of the invention is humorous for vibration device and interdigital electrode transducer architecture SAW resonator The area of vibration device is also smaller.
In conclusion the present invention can realize higher resonance frequency under the conditions of identical lithographic line width；And it can reduce Resonator area increases the integrated level of system.
Detailed description of the invention
Fig. 1 is the SAW resonator top view of the novel transducer electrode structure of embodiment；
Fig. 2 is the SAW resonator sectional view of the novel transducer electrode structure of embodiment；
Fig. 3 is that the section field distribution of embodiment emulates schematic diagram；
Appended drawing reference: substrate -100, hearth electrode -200, piezoelectric membrane -300, top electrode -400, metal bus bars -500.
Specific embodiment
The present invention is described further with reference to the accompanying drawings and examples.