MEMS wafer level vacuum packaging process

Abstract

The invention discloses an MEMS glass microcavity vacuum packaging process with long vacuum maintaining time, which comprises the following steps of: firstly, etching a deep packaging groove on a Si wafer by using an Si microprocessing process and etching a relatively shallower annular vacuum buffer groove at the periphery of the deep packaging groove; then bonding the Si wafer etched with the microgroove and a glass wafer so that the glass wafer and the specific pattern form a packaging cavity; heating and preserving the temperature of the bonded wafer at atmosphere pressure and leading softened glass to flow into the packaging cavity by a pressure difference inside and outside the cavity so as to form a microcavity structure corresponding to the microcavity pattern structure; cooling and annealing and removing stress of the wafer at normal pressure; then corroding to remove the Si wafer; and carry out anode bonding on the Si wafer and the glass wafer at the atmosphere of 1Pa-10Pa toform the integral vacuum packaging. The invention improves the maintaining capability of vacuum degree in the packaging cavity by manufacturing the annular vacuum buffer cavity at the periphery of the packaging cavity.

Description

technical field [0001] The invention relates to a MEMS (micro-electro-mechanical system) packaging technology, in particular to a MEMS wafer-level vacuum packaging method. Background technique [0002] In the field of MEMS packaging, since devices generally contain movable parts, it is necessary to use a micron-sized microcavity structure to hermetically package the device during packaging, so that the movable parts have room for movement and provide physical protection for the device. Some such as Devices such as resonators, gyroscopes, and accelerometers also require a vacuum and airtight packaging environment. The cavity made of inorganic material glass can provide a better vacuum and sealing environment, and the anodic bonding process can provide very good air tightness, which is the most commonly used vacuum sealing bonding process. The vacuum packaging of MEMS devices can be achieved by forming a microcavity structure on Pyrex7740 glass and anodic bonding with a Si su...

AI Technical Summary

Problems solved by technology

The reason is that as the depth of the molded cavity increases, more glass needs to be supplemented into the silicon cavity of the mold around the microcavity, so that the thickness of the glass around the microcavity of the glass wafer decreases, so that it is different from the plane of the non-flowing part of the glass wafer. Causes a large height difference, resulting in uneven glass surface

The surface roughness has a great influence on the bonding strength of anodic bonding, and also leads to a large package stress caused by the bonding process

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