PCB: Sensitive elements of microelectromechanical systems (MEMS)

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2021: Start of MEMS production for promising satellites

On September 23, 2021, the Russian Space Systems company (RKS, part of the Roscosmos State Corporation) announced that it had begun production of sensitive elements of microelectromechanical systems (MEMS) of the latest generation. These domestic serial microcomponents will become the basis of gyroscopes and accelerometers, which will be installed on promising spacecraft - from cubsats to interplanetary stations. Aerial, ground unmanned systems and industrial equipment, the use of MEMS will provide autonomous high-precision navigation.

Each sensor element of the inertial sensor is a solid-state crystal that converts the external effects of acceleration and rotation into electrical signals. The crystals themselves are made according to the technology of microelectromechanical systems, which the RCC has been developing since 2007.

"Combined into an inertial system weighing up to 100 g, with dimensions less than 5x5x5 cm and low power consumption, such sensors calculate and analyze the movements of the object and store data on its location and orientation in space. Solutions based on such sensitive elements have a high potential for use in aerospace technology and the industrial industry, in particular in autonomous orientation and navigation systems in interplanetary missions, when the mass and size requirements of the spacecraft are set and there is no possibility of remote control, " says research engineer at the Center for Microelectronics RKS Maxim Kharlamov.

Among domestic accelerometer sensors measuring acceleration, the most accurate is with a quartz pendulum inside. Accelerometers with a quartz pendulum are already used on returned Soyuz-TMA spacecraft. The achievements of the developers of the RKS Microelectronics Center made it possible to implement mass production of quartz pendulums with high accuracy characteristics in the reproducibility of geometry, and therefore the accuracy of the sensor itself with a simultaneous reduction in cost.

Other sensitive elements - silicon - are used in accelerometers due to the mastery and low cost of micro-processing technologies. The rich experience of RKS technologists in the formation of microstructures in silicon made it possible to establish the production of an array of versions of these single-axis sensitive elements: silicon pendulums with a beam suspension, with a torsion suspension, pendulums with magneto-electric feedback, pendulums for an inclinometer, annular silicon resonators for a gyroscope - in all these structures, deviations of key dimensions of sensitive elements are less than 1 μm.

The development of combined inertial systems on one crystal is recognized as a promising direction for the development of inertial sensors. The RKS holding has mastered the formation of complex 3D microstructures using plate splicing - this will make it possible to create multi-axis accelerometers and gyroscopes on one sealed evacuated crystal using Wafer-Level packaging technology, when the inertial system is made in a shell-free version.

"The solution is dictated by the constantly growing requirements for the mass dimensions of spacecraft. In the future, such orientation systems will complement the classical ones - by stars or by the Earth's magnetic field, allowing a significant reduction in the weight and energy consumption of satellites, "- notes the deputy head of the department for the development of micromechanical systems of the RKS Andrei Korpukhin.

Serial production of a variety of microelectromechanical systems of sensitive elements and other high-end electronics samples on its own production and technological platform allowed the RCC to move away from the practice of piece-by-piece, "manual" manufacture of sensitive elements. As of September 2021, they are manufactured only on the plate by the group method without the "human factor." Reliability, speed of manufacturing of elements and their cost are reduced many times.