Manufacturing method of interdigital transducer of surface acoustic wave filter

Abstract

The invention discloses a method for manufacturing an interdigital transducer of a surface acoustic wave filter, which comprises the following steps of: evaporating metal Ti on the back surface of a substrate to form a Ti metal layer, then carrying out an IDT process on the front surface of the substrate to form an IDT metal layer, and finally removing the Ti metal layer through a wet etching process. The Ti metal layer not only can realize shading in the IDT process, but also has good heat-conducting property, so that inconsistent photoresist morphology caused by non-uniform wafer heating in the curing process of the yellow light process can be avoided, and the CD uniformity of the IDT metal layer on the lithium tantalate or lithium niobate wafer is effectively improved. In addition, the metal Ti has a relatively low thermal expansion coefficient and a good heat dissipation effect, so that the wafer substrate is prevented from being broken due to non-uniform heating in the yellow light manufacturing process. Compared with other metals such as nickel, the titanium complex generated by etching the Ti metal layer does not cause environmental pollution, and the removal operation safety of the Ti metal layer is high.

Description

technical field [0001] The invention relates to the field of surface acoustic wave filters, in particular to a method for manufacturing an interdigital transducer of a surface acoustic wave filter. Background technique [0002] The surface acoustic wave filter is mainly composed of a wafer substrate with piezoelectric characteristics and an interdigital transducer (IDT) fabricated on the substrate. The interdigital transducer is formed by interlacing metal films. The principle of the surface acoustic wave filter is mainly to use its piezoelectric effect and the physical characteristics of surface acoustic wave propagation to realize acoustic-electric conversion. The surface acoustic wave filter plays a good role in suppressing high-order harmonics, image information, emission leakage signals and various spurious clutter interference of electronic information equipment, so it can achieve the required amplitude-frequency characteristics and phase-frequency with any precision ...

AI Technical Summary

Problems solved by technology

In the manufacturing process of the interdigital transducer of the surface acoustic wave filter, the yellow light process is required. In the yellow light process, the wafer needs to be placed in the exposure machine for exposure. At this time, the light is irradiated from the through wafer to the bottom. The upper disk, the upper disk will reflect part of the light back to the wafer to affect the morphology of the photoresist, and due to the area of ​​the upper disk and the unevenness of the surface, the light reflected by the upper disk is inconsistent, resulting in different wafer surfaces. The photoresist in the area eventually presents the problem of uneven CD, which affects the poor morphology of the IDT, resulting in the frequency failure of the designed filter device

In addition, lithium tantalate and lithium niobate materials are brittle and have poor thermal conductivity, especially when the wafer is placed on a hot plate, uneven heating can easily lead to wafer breakage

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