Surface acoustic wave element and manufacturing method thereof

Abstract

Surface acoustic wave element and its manufacturing method. An object of the present invention is to provide a surface acoustic wave element having excellent frequency characteristics and pass characteristics, and a method of manufacturing the surface acoustic wave element. As a solution, the surface acoustic wave element (10) is formed with a semiconductor wiring region (20) and a SAW region (30) side by side on the same plane of the semiconductor substrate (silicon layer 50), and a grid pattern is formed on the wafer (1). Arranging the surface acoustic wave element (10), and arranging the semiconductor wiring regions (20) and the SAW regions (30) formed on the adjacent surface acoustic wave elements (10) in an alternate grid pattern, in the semiconductor wiring region (20) Insulating layers (71-74) on the same plane are formed on the top of the SAW region (30), and a piezoelectric layer (90) is formed on the surface of the uppermost insulating layer (74). In the SAW region (30) An IDT (40) is formed on the surface of the piezoelectric layer (90).

Description

technical field [0001] The present invention relates to a surface acoustic wave element formed on a semiconductor substrate and a method for manufacturing the surface acoustic wave element. Background technique [0002] In conventionally known surface acoustic wave devices and their manufacturing methods, an epitaxial layer and a SiO layer are sequentially formed on a semiconductor substrate such as a silicon substrate. 2 layer, on SiO 2 On the upper surface of the layer, a semiconductor wiring region and a SAW (Surface Acoustic Wave, Surface Acoustic Wave) region are arranged in parallel with the plane direction. In the SAW region, SiO 2 thicker SiO 2 A comb-shaped IDT (Interdigital Transducer, interdigital transducer) made of aluminum and a piezoelectric layer (ZnO) are formed on the layer, and in the semiconductor wiring area, SiO 2 layer formed on top of the aluminum wiring layer and silicon nitride (Si 3 N 4 ) composed of an insulating layer (for example, refer to ...

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Problems solved by technology

[0004] In such Non-Patent Document 1, the uppermost layer of the semiconductor wiring region and the SiO in the SAW region 2 The height of the layer is different, especially the uppermost layer of the semiconductor wiring area is lower than the SiO of the SAW area 2 The height above the layer, so in order to flatten the SiO in the SAW region where the IDT is formed 2 When the surface of the layer is polished by CMP (Chemical and Mechanical Polishing, chemical mechanical polishing), it is difficult to uniformly form SiO in the SAW region where the IDT is formed. 2 layer thickness

SiO in which the SAW region of the IDT is formed is known 2 Depending on the thickness of the layer, there is a difference in the speed of propagating sound waves (sonic speed), but since the frequency is proportional to the sound speed, when there are regions with different sound speeds in the same element, stable frequency characteristics and steep passage characteristics cannot be obtained. The problem

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