MEMS sensor is today's hottest sensor manufacturing technology, but also an important impetus for sensor miniaturization and intelligence, MEMS technology has promoted the great development of sensors.
MEMS mainly uses microelectronic technology to shape the mechanical structure of the sensor under the volume of micro and nano. This article illustrates the manufacturing process and principle of MEMS sensor chips in the clearest and clearest way!
Avoid missing out on in-depth information and reports on the sensor industry, as well as sensor technology, sensor and test technology, IoT sensor technology... and other sensor knowledge, please pay attention to the sensor expert network public number, set as a star, view the previous content.
MEMS is an abbreviation for Micro Electro Mechanical Systems, which has a tiny stereoscopic structure (three-dimensional structure) and is a general term for systems that process various input and output signals.
It is a high value-added component that integrates mechanical parts, electronic circuits, sensors, and actuators on a circuit board using microfabrication technology.
MEMS process
The MEMS process is based on conventional semiconductor processes such as film forming, lithography, etching.
Some of the key technologies of the MEMS process are described below.
Wafers
SOI wafers
SOI, short for Silicon On Insulator, refers to a silicon wafer that forms a monocrystalline silicon layer on an oxide film. It has been widely used in power components and MEMS, etc., in MEMS can use the oxide film layer as a barrier layer for silicon etching, so it is possible to form a complex three-dimensional structure.
TAIKO Grinding "TAIKO" is a trademark of DISCO Corporation
TAIKO grinding is a technology developed by DISCO that preserves the outermost edges when grinding wafers and grinds only the inside of them.
Taiko grinding has the advantages of "reduced wafer warpage", "higher wafer strength", "easy handling", and "higher integration with other processes" compared with normal grinding.
Wafer bonding/hot-peeling sheet process
By using support wafers and hot-peel wafers, thinning wafers can be easily processed, for example.
Wafer bonding
Wafer bonding is roughly divided into two categories: "direct bonding" and "bonding through the middle layer".
Direct bonding does not use adhesives, etc., but is a bonding that uses the intermolecular forces generated by heat treatment to bond the wafers to each other, and is used to make SOI wafers.
Bonding through the middle layer is a bonding method that bonds wafers to each other with the help of adhesives.
etch
Isotropic etching and anisotropic etching
By discharging the plasma in low vacuum, the plasma is produced by ionizing the plasma, and the technique of etching with this particle is called reactive ion etching.
There are charge-carrying ions and neutral free radicals mixed in the plasma, which have two kinds of etching effects: isotropic etching using free radicals and anisotropic etching using ions.
Silicon depth etching
Bosch process technology, which combines the advantages of anisotropic etching and isotropic etching, has become the mainstream technology for deep etching of silicon.
Longitudinal deep etching can be performed by repeated Si-etched polymer deposition bottom surface polymer removal.
The convexity of the side walls is shaped like scallops and is called "scallop morphology".
Film formation
ALD (Atomic Layer Deposition)
ALD, short for Atomic Layer Deposition, is a film-forming method in which atoms are deposited layer by step by repeating material supply (precursor) and exhaust, using surface reactions with substrates.
In this way, as long as there is a gap through which the film-forming material can pass, it can be controlled by the nano-level film thickness, and the film can be formed in the sidewall of the small hole and the bottom of the deep hole, and a uniform film-forming can be formed in MEMS processing such as polymer deposition during deep etching.
Related terms for MEMS
The content of the star = the content you care about, according to the principle of WeChat public account recommendation, without the sensor expert network public account home page [set as a star], will not be able to get the latest information of the sensor industry in time!
Disclaimer: The content of this article is the personal opinion of the author and does not represent the views or positions of the Sensor Expert Network. For more views, please leave a comment.