Draft:Silicon Sensing

Silicon Sensing Systems, Limited (SSSL) is an Anglo-Japanese joint venture company which was inaugurated in 1999. It has two equal (50/50) shareholders; Collins Aerospace (Plymouth - UK) and Sumitomo Precision Products (Amagasaki - Japan).

Offering

The company develops, manufactures, markets and sells MEMS (Micro-Electro[1]Mechanical Systems) inertial sensors; gyroscopes and accelerometers, and IMUs (Inertial Measurement Units). In addition it offers a MEMS foundry service producing other customers' MEMS device wafers. MEMS = use of semiconductor processing techniques to make tiny, micro-scale, electromechanical devices. Inertial Sensors = Gyroscopes, Accelerometers and IMUs measure motion of whatever they are attached to.

Markets Products: SSSL's product customers can be summarised as any industrial, commercial, automotive or aerospace equipment manufacturer requiring inertial sensors or systems to help either stabilise, point, guide or navigate what is generally referred to as a 'platform'. Platforms range from Autonomous Underwater Vehicles to Low Earth Orbit satellites. Customer's applications are very diverse. Foundry Services: Customers using SSSL's MEMS foundry service are equally diverse. The company is, for example, producing MEMS chips for a company making solid-state LiDAR systems used in cars for next generation Advanced Driver Assistance Systems. One of the company's key MEMS processing capabilities is the deposition of thin-film PZT; a piezoelectric material which can be either used to make micro-actuators or micro-sensors. Most of its business is exporting of inertial sensor products and MEMS foundry services on a worldwide basis to over 150 active customers in well over 30 countries. Most sales are to developed nations with advanced engineering industries. Their products and services are highly advanced technologies used in equally 'hi-tech' equipment such as say a precision agricultural robot or an Earth observation satellite.

Market Forces and Business Evolution: Over the last 25 years Silicon Sensing has witnessed growth in competition from the USA, Europe and the Far East, primarily from lower-cost (lower-spec) providers entering the market. Through engineering excellence and innovation the company's products and technology are now widely considered to be the benchmark when it comes to the measurement sensitivity of MEMS based inertial sensors. This technological advantage has been capitalised by developing and offering a range of lower-cost high-precision MEMS alternatives to expensive optical-based inertial sensors (e.g. Ring Laser Gyros).

A brief history: Silicon Sensing Systems, Ltd. was formed 24 years ago by two aerospace companies; British Aerospace (BAe Plymouth), and; Sumitomo Precision Products (SPP Amagasaki). The purpose was to commercially exploit the potential of new Silicon MEMS manufacturing processes for mass producing low-cost solid-state gyroscopes required by the automotive industry for a newly emerging generation of intelligent car braking and safety systems; namely ESC (Electronic Stability Control) and roll-over protection. Until the advent of MEMS processing, British Aerospace was producing gyroscopes only for its traditional defence and aerospace customers. It was manufacturing non-MEMS solid-state CVG (Coriolis Vibrating Gyroscopes) on a modest scale and had forged a business relationship with SPP to allow CVG manufacture under licence in Japan. However the cost of manufacture was still prohibitively high to allow mass uptake of CVGs by the high volume passenger car and commercial vehicle market. In the mid-1990s SPP acquired Silicon MEMS processing capability and together, BAe and SPP embarked on a bold adventure to jointly develop the first Si MEMS based CVG. Both companies quickly understood that creating a new company with it's own organisation, culture, identity and brand to distinguish it from its aerospace parents was an imperative for success selling MEMS CVGs into commercial / consumer industries.

A new JV company: Silicon Sensing Systems, Limited, was formed 12th May, 1999. Over the first 12 years SSSL steadily became established as a tier 2/3 supplier of highly reliable MEMS gyroscopes to most automotive OEMs in Europe and North America for ESC, roll-over protection and in-dash SatNav aiding. Over 25 million were delivered and many millions of these sensors are still in daily use in cars around the world. Other products were developed using the MEMS CVG technology in order to address demand from adjacent commercial markets such as Segway, robotic industrial machinery, unmanned aerial vehicles (aka drones) to name just a few of the hundreds of new uses for affordable, reliable and small gyroscopes. BAe Plymouth (later to become AIS - Atlantic Inertial Systems, Ltd) took advantage of the reliability and cost of the MEMS CVG sensors from Silicon Sensing and has successfully established itself as a market leader in the manufacture and export of MEMS IMUs for guided munitions. AIS received the Queens Award for Enterprise 2021 in recognition of this achievement in defence markets. Since 2015 Silicon Sensing faced increasing competition from lower-cost entrants seeking to capitalise on the growing demand for the now highly commoditised supply of MEMS gyroscopes, accelerometers and IMUs. Very high-volume markets for consumer (mobile phone) and automotive grade sensors have relaxed specifications to meet cost and power targets, the company has instead now focuses on 'higher-end' civil applications where the superior sensitivity of its technology scores favourably. In the last six years Silicon Sensing has been regenerating its business developing new high-integrity MEMS inertial sensors and systems, and has diversified into now offering a MEMS device wafer fabrication service for 'fabless' MEMS customers

Technology: Over the last two decades, the landscape of the inertial sensor market has undergone a transformative shift with the rise of ‘solid state’ non-rotating rate sensors, commonly mislabeled as gyroscopes. Silicon Sensing was one of the original pioneering companies, that led to the commercialisation of solid-state gyroscopes in the 1990’s, with the launch of the VSG (Vibrating Structure Gyro). MEMS gyroscopes, specifically MEMS angular rate sensors, are crucial for precisely measuring rate of turn (°/s) without a fixed reference point. This sets gyros apart from traditional rotation measurement tools like tachometers or potentiometers. All Silicon Sensing's MEMS gyros use a unique, patented VSG resonating ring technology to detect rotation rate through the Coriolis phenomenon. VSG technology has evolved into three generations – Inductive, Capacitive, and PZT. This evolution enables us to offer a diverse range of MEMS VSG gyros, spanning from cost-effective, precision chipscale sensors. VSG gyros employ a groundbreaking approach – utilising a vibrating or resonating ring, fabricated using a DRIE (Deep Reactive Ion Etch) bulk silicon process. The annular ring is intricately supported in free space by eight pairs of symmetrical spokes. This fabrication, coupled with our unique patented ring design, ensures close tolerance geometrical properties, allowing precise balance and thermal stability. Unlike other MEMS VSG gyros, our design eliminates small gaps that create problems with interference and stiction. This enables us to create high quality products with unparalleled bias and scale factor stability, regardless of temperature, vibration, or shock exposure. Moreover, our patented design boasts inherent immunity to acceleration induced rate error, commonly known as ‘G-sensitivity’. At the heart of our MEMS VSG gyros is an integration of actuators and transducers which are strategically attached to the upper surface of the silicon ring perimeter. These components are electrically connected to bond pads on the silicon via tracks embedded on the spokes. These actuators serve a dual purpose, they either actuate or ‘drive’ the ring into its Cos2θ mode of vibration (like rubbing a wet finger on wine glass, causing it to vibrate and ‘ring’), or the detect radial motion of the ring perimeter. This radial motion can be induced by either the primary drive actuator or the Coriolis force effect, especially when the gyro is in rotation about its sensing axis – positioned through the centre of the ring.

The fusion of cutting-edge transducer technology and secondary pick-off transducers enhances the VSG’s signal-to-noise ratio. The result? An ultra-low noise device with unparalleled bias instability and Angular Random Walk (ARW) performance.

Background and Context: In the past markets for inertial (motion) sensors could be considered very niche, but this has all now changed and MEMS gyroscopes, accelerometers and IMUs are ubiquitous - they are in mobile phones and spacecraft, and every conceivable moving item of equipment in-between. The products offered by Silicon Sensing can be regarded as commodities, however SSSL distinguishes itself by having the highest performing Si MEMS-based CVG gyroscopes in the market, elevating its position as an inertial supplier, thus positioning it as a UK exporter of high-end technology. This is now big business and there are very many players in the field of MEMS inertial sensors located in North America, Europe and the Far East, thus making it all the more important to maintain the distinction of being at the pinnacle of sensor sensitivity and performance.

Global Trend: It is increasingly important to recognise, at the earliest onset, changes and global trends in the industry which may impact Silicon Sensing's markets. Having a global footprint and network facilitates the assimilation of market intelligence and provides ease of access to the 'players'. Geo-Political Factors As MEMS inertial technology evolves it is becoming more and more sensitive and recent future advancements mean low-cost MEMS sensors are now capable of being used for passive precision guidance of missiles and drones over increasingly long distances, so there is a geo-political dimension to consider as export controls and trade sanctions become increasingly significant factors. Size Matters in MEMS Any MEMS-based device company needs to access medium or mass-markets for its products or services in order to achieve optimum economy of scale and thus survive in the mid-to-long-term, Silicon Sensing is no exception. Silicon Sensing's position in the MEMS inertial sensor industry is at the upper end of the price-v-performance spectrum. Its vision for the inertial sensor product business has two main strands: 1. Penetrate established markets for higher-cost, traditional (non-MEMS) inertial sensors (e.g. Ring Laser Gyroscope) and take market share with its much smaller, lighter, lower-cost and reliable MEMS-based alternatives. 2. Address the needs of emerging medium-scale markets requiring affordable high-end inertial sensors. A prime example of this is the growing market-pull for 'tactical' / 'navigation' grade low-cost inertial sensors for future automotive ADAS (Advanced Driver Assistance Systems) and AV (Autonomous Vehicles).