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验证了用铌酸锂作压电基片的声表面波器件的一种潜在失效机理.它涉及用作叉指换能器的铝膜上生长氧化铝.在排除了氧化膜生长所必要的条件后成功地消除了高可靠器件中的这种失效机理.这必要的条件就是在换能器上有直流电场存在.导致氧化物生长的确切条件至今还未确定.但已经知道在125℃温度和10~4伏/厘米量级的电场下,经过168小时就能生长氧化物.氧化物的生长使有效声耦合系数下降,从而使器件的插损增大,射频通带特性也逐渐变坏.
A potential failure mechanism of a surface acoustic wave device using lithium niobate as a piezoelectric substrate was verified, which involves the growth of aluminum oxide on an aluminum film used as an interdigital transducer. After eliminating the conditions necessary for the growth of the oxide film The successful elimination of such a failure mechanism in highly reliable devices necessitates the existence of a direct current field on the transducer The exact conditions leading to the growth of oxides have not been established so far but it is known that at temperatures of 125C Oxides grow after 168 hours under the electric field of the order of 10-4 volts per centimeter, and the growth of oxide reduces the effective acoustic coupling coefficient, so the insertion loss of the device increases and the radio frequency passband characteristic also gradually deteriorates.