MEMS (micro-electro-mechanical system) chip with getters and wafer level packaging method thereof

Abstract

The invention discloses an MEMS (micro-electro-mechanical system) chip with getters and a wafer level packaging method thereof. The MEMS chip comprises a cover plate, an MEMS structure layer and a bottom plate, wherein cover plate cavities are formed in the lower surface of the cover plate; bottom plate cavities are formed in the upper surface of the bottom plate; the cover plate cavities and the bottom plate cavities jointly form seal cavities; MEMS structures are arranged in the seal cavities; cover plate insulating layers are arranged between the cover plate and the MEMS structure layer; the bottom plate is bonded with the MEMS structure layer by bottom plate bond layers; pyramids or frustums of prisms are manufactured in the cover plate cavities or the bottom plate cavities and are covered by getters. The pyramids or frustums of prisms are formed while the bottom plate cavities or the cover plate cavities are etched. A plurality of pyramids or frustums of prisms are manufactured in the seal cavities of the MEMS chip under the conditions that processing steps are not added and the area of the MEMS chip is not increased, and the getters are sputtered or evaporated on the surfaces the pyramids or frustums of prisms to increase the surface areas of the getters. The getters are used for adsorbing gas molecules in the seal cavities, ensuring the vacuum degrees of the seal cavities and providing a work environment with high vacuum degree for the MEMS structures.

Description

technical field [0001] The invention belongs to the field of chip packaging, in particular to a MEMS chip with a getter, and also relates to a wafer-level packaging method for the MEMS chip with a getter. Background technique [0002] The wafer-level packaging of MEMS chips is to seal the MEMS structure in a cavity with a cover plate and a bottom plate during the MEMS wafer manufacturing process; the function of the sealing cavity is to provide a free space for the MEMS structure sealed in the cavity. The space for movement, at the same time, ensures that the MEMS structure is not disturbed by the external environment. [0003] Some MEMS devices, such as gyroscopes and clock oscillators, use their MEMS structures to vibrate continuously under the drive of electrostatic force or inverse piezoelectric effect, which requires a sealed cavity on the MEMS chip to surround the MEMS structure. In a sealed cavity with a higher vacuum degree, the higher the vacuum degree in the seale...

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Problems solved by technology

Patent EP2813465A1 describes making a getter on the MEMS structure layer, which will increase the area of ​​the MEMS chip or affect the performance of the MEMS chip

Patent US2016 / 0101976A1 describes that the surface area of ​​a rectangular cavity is increased by etching or depositing hemispherical polysilicon, and the getter is made on the surface of the rectangular cavity, but this method requires additional process steps to form a rough surface, Second, when the getter is sputtered, the movement direction of the metal ions or atoms constituting the getter is basically perpendicular to the bottom surface of the rectangular cavity, which cannot completely cover its vertical side, and the utilization rate of the side is not high.

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