Preparation method of composite substrate, composite substrate and composite film

Abstract

The invention provides a preparation method of a composite substrate, the composite substrate and a composite film. The preparation method of the composite substrate comprises the following steps of: cleaning a monocrystalline silicon substrate to obtain a monocrystalline silicon substrate layer with a clean surface; growing polycrystalline silicon on the clean surface of the monocrystalline silicon substrate layer, and executing a planarization process to form a first polycrystalline silicon layer; and focusing laser on the side surface, close to the monocrystalline silicon substrate layer, of the first polycrystalline silicon layer until a monocrystalline silicon fusion layer is formed, and stopping laser focusing to obtain a composite substrate. The composite substrate sequentially comprises a monocrystalline silicon substrate layer, a monocrystalline silicon fusion layer and a second polycrystalline silicon layer from bottom to top. By adopting the scheme, the position, the distribution and the size of a monocrystalline silicon fusion region are accurately controlled by adjusting the power, the focal length and the position of the laser, so that the bonding force of a target region at a target interface can be improved according to the actual conditions of the monocrystalline silicon substrate layer and the polycrystalline silicon layer, and the deposition adhesion of polycrystalline silicon on the silicon substrate is improved.

Description

technical field [0001] The present application relates to the field of semiconductor technology, in particular to a method for preparing a composite substrate, a composite substrate and a composite thin film. Background technique [0002] RF filters are widely used in the transceiver links of wireless communication terminals, allowing signals of specific frequencies or frequency bands to pass through while filtering out unwanted interference or spurious signals. RF filters mainly include surface acoustic wave filter (SAWFilter) and bulk acoustic wave filter (BAW Filter), whose frequency ranges from 800 to 2500MHz. Among them, the energy of the surface acoustic wave in the surface acoustic wave filter is focused on the surface of the substrate, so that the wave propagates without loss on the substrate. By simultaneously controlling the linear expansion coefficient of the substrate and the speed of sound to reduce the frequency temperature coefficient, the electrode generates ...

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Problems solved by technology

[0005] This application provides a method for preparing a composite substrate, a composite substrate, and a composite film to solve the problem that in the prior art, during the cutting process, the composite film is easily debonded at the interface with poor bonding force, causing the functional film to fall off and affecting this area. In addition, the weak binding force will also increase the risk of debonding during the use of RF filters and reduce the service life of RF filters

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