Caeleste

Caeleste is a design house for turnkey high-end, high-performance image sensors, custom sensor designs, IP and long-term R&D consultancy.

The unique technology of the company enables the production of hybrid or mixing circuits, which offers a multitude of advantages over monolithic solutions. This applies, among other things, the noise immunity and the signal-to-noise ratio, but also the reading with ultra-low noise while using a large number of fast switching digital logic circuits in the pixels as well as high fill factors and gated pixels.

In addition, high-yield X-ray photon counter arrays are available that provide unprecedented noise, energy and MTF performance.

The team consists of experienced designers, scientists and machine vision experts who have acquired their expertise in designing many advanced image sensors at FillFactory, Cypress Semiconductor, IMEC, CEA-LETI, ULIS and Texas Instruments.

Caeleste focuses on applications in medical and space imaging, as well as demanding niches in Automotive, Factory automation, Biometrics, Scientific imaging and Spectroscopy.

For more information, please visit the Caeleste website.

From single photon pixels to chip-on-board

Customer-specific production of image sensors guarantees long-term availability and optimal properties

Image sensors today are critical components of a wide variety of work processes, and depending on the application, they must meet very specific requirements in order to achieve the required performance. If a proven sensor is discontinued by the manufacturer—as recently Sony's CCD series—this can be a serious problem for camera manufacturers or measuring tools.

An alternative to this is provided by custom-made sensors, which can not only be tailored exactly to the task spectrum, but also remain available over the entire product lifetime. Eureca has already implemented various OEM projects in this area in cooperation with the Belgian design house Caeleste, such as very sensitive UV sensors for chemical analysis or precise high-speed sensors with global shutter. The basis of the developments is state-of-the-art CMOS technology, which ensures long-term availability.

Just how big the dependency of the digital imaging sector is on some suppliers was the upheaval in the industry when Sony announced the end of its CCD sensors in February 2015. Meanwhile, the group has extended the terms of some types again under pressure from customers, but the problem was only postponed. Companies in which imaging systems with specific characteristics and functionalities are essential for production—for example in quality assurance, analysis or monitoring—as well as the manufacturers of such devices increasingly rely on individually manufactured sensors due to such delivery risks. These are produced in a targeted manner, if and how the customer needs them, which ensures a high level of availability security over the entire product life cycle. Unmediated changes to devices that have proven themselves in practice can thus be avoided. In principle, the availability would be guaranteed for such customer-specific models, as long as there is still the necessary production technology somewhere in the world.

The right sensor for every task

The second big advantage with this approach is that the performance characteristics of the sensors can be tailored to the application requirement. Unnecessary features, which are simply part of the package for standard sensors, can be eliminated and other important functions optimized instead. This gives the customer an optimal sensor for him with the best possible specifications, which are not achievable with standard components.

In addition to sensors with low noise and high photosensitivity, for example, high-speed sensors for extreme sharpness can be created during the fastest movements by processing the acquired data in large numbers in parallel. For other applications, solutions with ultra-high dynamic range within an exposure are possible in which the pixel information is read several times with different amplification levels after only one exposure. The special tuning of the read-out processes prevents a falsification of the image data and guarantees highest linearity.

For metrology tasks, for example, Eureca and Caeleste are also able to produce especially UV-sensitive sensors. In addition to the usual backside thinning, the front side is also etched away in order to minimize the loss of UV quanta through absorption in the dielectric stack. Even the detection of individual photons can be achieved by means of so-called »single-photon avalance diodes« (SPAD), in which the charges generated by the detected light particles are amplified in the pixel itself. Depending on requirements, the sensors are not only manufactured as stand-alone units with their own housing, but can also be mounted directly on a circuit board, which saves installation space and production costs.

On-site consulting and implementation by specialized partners

In order to determine the relevant specifications within an economic framework, Eureca consults intensively with the respective customer and, if necessary, also looks after on site during the entire development and production period. This close collaboration allows for short distances and easy communication. With the help of a specially developed calculation program, the imaging of different sensor specifications can even be virtually simulated in advance in order to check whether it meets the requirements.

Once a first specification has been prepared, the specifications will be handed over to Caeleste. The designers there take care of the technical realization, for example, they create the masks for photolithography and search from all available production sites for a production partner with the production know-how appropriate for the specific sensor model.

The latter makes it possible to offer a wide range of different specifications, which would not be possible with a solid supplier specialized in one type of sensor. The fact that Caeleste, as a Belgian company, is more or less in the neighborhood and also works to European standards, ensures uncomplicated cooperation and fast project execution. Contracts that already have a base of requirements can sometimes be implemented in less than a year. But even projects that have to start from the drawing board usually last only one to two years.