Manufacturing method of composite piezoelectric substrate for surface acoustic wave device

Abstract

The invention provides a method for manufacturing a composite piezoelectric substrate for a surface acoustic wave device. The method comprises the following steps of providing a silicon wafer and a piezoelectric wafer which are provided with polishing surfaces, and performing semiconductor-level cleaning on the silicon wafer and the piezoelectric wafer; forming a first bonding body; sequentially thinning and polishing the piezoelectric wafer of the first bonding body; performing ion injection onto the piezoelectric wafer in the first bonding body after thinning and polishing; forming a secondbonding body; heating the second bonding body to achieve thermal separation of the piezoelectric wafer so as to obtain the composite piezoelectric substrate and a third bonding body; and annealing thecomposite piezoelectric substrate. The third bonding body is obtained after recycling and thermal separation, so that the raw material utilization ratio is improved.

Description

technical field [0001] The invention relates to a manufacturing method of a composite piezoelectric substrate for a surface acoustic wave device. Background technique [0002] The high-speed growth of mobile data volume puts forward higher requirements for data transmission. For the fifth generation mobile communication system, in the long-term evolution of the LTE system, the frequency difference of the frequency division duplex communication technology is getting smaller and smaller. In this case, it is necessary to equip filters with characteristics such as excellent frequency band selectivity, high Q value, and low insertion loss. At the same time, in the 5G communication era, the increase in high-frequency communication and the number of frequency bands will greatly increase the demand for filters. [0003] Lithium tantalate wafer is a commonly used piezoelectric substrate for making filters, which is usually prepared directly from lithium tantalate die. However, the ...

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Problems solved by technology

When the stress is too large, it will cause cracking of lithium tantalate and silicon substrate

[0006] The lithium tantalate layer in the bonding body needs to be thinned before separation, and the removal of lithium tantalate is relatively large, and the separated lithium tantalate cannot be reused, resulting in serious waste of materials

[0007] Due to the large thermal expansion coefficient of the lithium tantalate wafer during ion implantation, when the backside cooling is applied, a large stress will be generated due to the huge temperature difference between the two surfaces of the lithium tantalate wafer, resulting in cracking. crack; if not cooled, its injection efficiency is limited by the injection temperature

And the thermal conductivity of lithium tantalate wafers is low, resulting in low efficiency of backside cooling

[0008] The production process is complicated, which increases the risk and cost of the production process

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