摘要
A high-Q diaphragm-structure film bulk acoustic resonator （FBAR） with a flat support diaphragm, made of Si3 N4/SiOz/Si3 N4 composite films ,is proposed. The N/O/N composite diaphragm overcomes the wrinkling in the released support diaphragm caused by the residual stress of a single Si3N4 or SiO2 diaphragm. ZnO piezoelectric film deposited employing a DC reactive magnetron sputtering method is used as the piezoelectric material for the FBAR device. The XRD 0- 20 scan indicates that the ZnO film has the preferred c-axis orientation growth,implying good piezoelectric properties. The S parameter measurement shows that there＇ are three primary resonances in the frequency range from 0.4 to 2.6GHz. The series resonant frequency,parallel resonant frequency, Kett^2, and quality factors of the three resonances are calculated. The third one,with a frequency of about 2.4GHz,has the highest quality factor about 500. Thus,it is expected to be a candidate to form a 2.4GHz low-phase-noise oscillator.
研制了一种采用氮化硅/二氧化硅/氮化硅复合膜作为支持薄膜的高Q薄膜体声波谐振器.当采用单层氮化硅膜或二氧化硅膜作为谐振器的支持薄膜时,由于残余应力的作用,释放完的薄膜往往会出现褶皱的现象,极大地降低了薄膜体声波谐振器的Q值;上述复合膜结构有效地解决了这个问题.采用直流磁控溅射法制备了氧化锌压电薄膜,X射线衍射结果表明制备的氧化锌薄膜具有很好的c轴择优取向,意味着氧化锌薄膜具有较好的压电性.S参数测试结果表明该薄膜体声波谐振器在0.4~2.6GHz的频率范围内具有3个明显的谐振模式,计算了这些谐振模式的串联谐振频率、并联谐振频率、有效机电耦合系数和Q值.在这3个模式中,第3个谐波模式的工作频率约为2.4GHz,具有最高的Q值（约为500）,可用来制备2.4GHz的低相噪射频振荡源.
基金
the National Natural Science Foundation of China(No.90607012)~~
