02 February 2018
Leti, a research institute at CEA Tech, has developed a new curving technology for optical sensors and micro-displays that improves performance, enhances field of view and compensates for aberrations in optical applications.
According to a newly published scientific paper, the technology is able to curve components such as CMOS imagers and charged-couple device (CCD) imagers for a broad range of products such as mobile phones, cameras, telescopes, medical-imaging tools and industrial-control equipment.
Other uses include IR sensors for astronomy, defence, drones and micro-displays for automotive applications, augmented reality and virtual reality.
Leti has developed a fully functional prototype of this technology and unveiled its work in a paper, “Curved Sensors for Compact High-Resolution Wide Field Designs: Prototype Demonstration and Optical Characterization”, at Photonics West 2018, in collaboration with LAM (Laboratoire d’Astrophysique de Marseille).
“Curved sensor technology is a disruptive approach for imaging applications such as photography, videography, computer vision, surveillance and many other applications,” said Bertrand Chambion, one of the paper’s co-authors. “In recent years, we have seen very strong interest in curved electronics, particularly for opto-electronics systems whose performance improves, while size, complexity and cost are reduced.”
The demonstration comprises of a 1/1.8’’ format, 1.3-million-pixel CMOS image sensor. The standard sensor structure consists of a 7.74 x 8.12mm silicon die glued on a ceramic package. Electrical connections are wire bonded from the die to the package surface and, then, to the interconnection board. A glass cover is placed on top for mechanical protection.
Leti uses a grinding process to get the sensor below 100µm thick, which makes it mechanically flexible. It is then glued onto a curved substrate, which determines its final shape. A wire bonding process developed for electrical connections is used to prevent damages on the thinned dies. The radius of curvature is R=65mm.
The process is, according to the paper’s authors, compatible with any sensor size and with large-scale manufacturing processes.