Resonator, forming method thereof and electronic equipment

Abstract

The invention discloses a resonator, a forming method thereof and electronic equipment. The method comprises the following steps: for an SOI wafer comprising a top silicon layer, a buried oxide layer and a bottom silicon layer, sequentially forming a patterned piezoelectric layer and a bottom electrode on the top silicon layer; inverting the current semiconductor structure and bonding the current semiconductor structure to the lower silicon cap, wherein a lower cavity is formed between the current semiconductor structure and the lower silicon cap; removing the bottom silicon layer; forming a beam structure, wherein the top silicon layer serves as a driven layer of the beam structure; and bonding the upper silicon cap to the current semiconductor structure, wherein an upper cavity is formed between the current semiconductor structure and the upper silicon cap. According to the method, the packaging technology that a device is inverted for bonding to achieve a resonator vacuum cavity is adopted, the use of an SOI silicon wafer with a cavity is avoided, and the cost is greatly reduced. Meanwhile, the stress problem caused by the fact that the bent cavity SOI top silicon recovers to be straight after the cavity SOI top silicon is formed and the stress problem caused by hard bonding of the bottom silicon and the buried oxide layer is solved.

Description

technical field [0001] The invention relates to the technical field of micro / nano electromechanical systems, in particular to a resonator, a forming method thereof, and an electronic device. Background technique [0002] At present, devices with cantilever beams such as resonators are mostly made of SOI silicon wafers with cavities. Taking the resonator as an example, the fabrication of the beam in the traditional process is generally as follows: sequentially deposit and pattern the lower electrode, the piezoelectric layer, and the upper electrode on the SOI with a cavity, and then the free end of the beam and the top silicon on both sides and the The buried oxide layer is etched away to form the beam, and finally packaged by bonding a silicon cap. There are many shortcomings in this process, first of all, as figure 1 As shown, because the air pressure in the cavity 1004 of the cavity SOI is low, usually the top silicon 1001 on the cavity 1004 will be depressed under atmos...

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Problems solved by technology

There are many shortcomings in this process, first of all, as figure 1 As shown, because the air pressure in the cavity 1004 of the cavity SOI is low, usually the top silicon 1001 on the cavity 1004 will be depressed under atmospheric pressure, and the device fabricated on the cavity 1004 will also bend accordingly; as figure 2 When the cavity 1004 is connected to the atmosphere after the beam is formed, the top silicon 1001 and the buried oxide layer 1002 tend to return to a straight state while the initial state of the electrode layers 1005, 1007 and the piezoelectric layer 1006 is a curved state, so the top Greater stress is generated between the silicon 1001 and the piezoelectric layer 1006

This stress will lead to a decrease in the device quality factor Q

Secondly, since both silicon and silicon oxide are hard materials in the SOI manufacturing process, the two hard materials are bonded to form a large stress; although the cantilever beam is formed, its fixed end is bonded by the original silicon-silicon oxide of SOI. The interface is fixed on the bottom silicon 1003, so the parasitic stress in SOI seriously affects the performance of the device

Finally, because SOI with a cavity is difficult in processing technology and has a long production cycle, the SOI silicon wafer with a cavity is very expensive, so the process cost of using a cavity SOI is also high

Therefore, it is difficult to further improve the quality factor and the cost is too high for devices manufactured by SOI with cavity and traditional packaging technology, which has become a key obstacle to commercialization of products

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