Acoustic surface wave transducer with multi-order transverse mode suppression and manufacturing method thereof

Abstract

The invention discloses an acoustic surface wave transducer with multi-order transverse mode suppression and a manufacturing method. The surface acoustic wave transducer comprises a wafer substrate, an interdigital metal layer and a temperature compensation layer which are sequentially arranged from bottom to top, the load layer adopts one of the following structures or a combination of the following structures; according to a first structure, a load layer is arranged on or in a temperature compensation layer, the load layer does not make contact with an interdigital metal layer, and the load layer covers all or part of finger strip ends in the interdigital metal layer; according to a second structure, the load layer is arranged in the wafer substrate, the load layer is located at the position corresponding to the finger strip end of the interdigital metal layer, and the load layer is made of a conductive material; and according to a third structure, the load layer is located between the interdigital metal layer and the temperature compensation layer, the load layer covers all or part of finger strip ends in the interdigital metal layer, and the load layer is made of a non-metal material. An end area of the finger strip is processed to block a transverse mode, and an electrical performance index and a quality Q value are improved; a load layer of the first structure is isolated from an interdigital metal layer through a temperature compensation layer and is not connected with the interdigital metal layer to be short-circuited.

Description

technical field [0001] The invention relates to the field of surface acoustic wave devices and manufacturing techniques thereof, in particular to a multi-order transverse mode suppressed surface acoustic wave transducer and a manufacturing method. Background technique [0002] Mobile communication has developed from the initial 2G to 3G, and then to today's 4G / 5G, frequency resources are becoming more and more crowded, and the guard interval between frequency bands of different communication systems is getting smaller and smaller. For example, for the transmitter (Tx) and receiver (Rx) duplexer frequency bands (Band2, 3, 8, 25), etc., the frequency interval between Tx and Rx is very narrow. If the frequency is changed, the frequency may drift, and Tx and Rx will affect each other, resulting in a serious deterioration of the overall performance. Therefore, temperature stability requirements are put forward for the surface acoustic wave filter as the main filter device for ra...

AI Technical Summary

Problems solved by technology

However, when a layer of temperature compensation material (such as SiO2, etc.) is plated on the surface of the interdigital transducer of the SAW filter chip, although the temperature characteristics are greatly improved, it will bring about changes in chip performance. After the temperature compensation layer, the sound wave propagation and working mode in the entire chip structure will be different from the conventional STD-SAW. If the conventional SAW design method is still used, the resonator and RF filter will have strong transverse mode ripples, and the passband The clutter is serious, affecting the main wave modes in the original device, thus having a great impact on the performance of the surface acoustic wave device

[0004] In the existing transverse mode suppression methods, such as changing the length of the dummy finger to change the weight of the length of the overlapping area of ​​the IDT fire-ground electrode, it may affect the Q value of the resonator and increase the filter loss

Another example is Murata, Qualcomm and other foreign manufacturers leading the method of increasing the duty cycle at the end of the metal finger, or adding a second layer of metal. This method is good for suppressing the transverse mode, but it also requires the accuracy of the process. If the duty cycle If the ratio is too large or the alignment of the second layer is not accurate, a short circuit may occur

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