A multi-layer CCD is a CCD

image sensor An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of c ...

that captures true RGB using stacked CCD sensor layers. This concept was the subject of a 1978

Kodak The Eastman Kodak Company (referred to simply as Kodak ) is an American public company that produces various products related to its historic basis in analogue photography. The company is headquartered in Rochester, New York, and is incorpor ...

patent application (issued 1986),
Color responsive imaging device employing wavelength dependent semiconductor optical absorption
Bruce C. Burkey et al. but did not result in a working image sensor. The concept resurfaced as part of an April Fools' Day prank press release fro
dpreview.com
When the joke was released in 2000, a remarkably similar device was under development at

Foveon Foveon, Inc., is an American company that manufactures and distributes image sensor technology. It makes the Foveon X3 sensor, which captures images in some digital cameras. Foveon was founded in 1997 and is based in Santa Clara, California. In 2 ...

—the

Foveon X3 The Foveon X3 sensor is a digital camera image sensor designed by Foveon, Inc., (now part of Sigma Corporation) and manufactured by Dongbu Electronics. It uses an array of photosites that consist of three vertically stacked photodiodes. Each o ...

, which is multi-layered but is not a CCD. The Foveon sensor was announced o
dpreview.com
in 2002, wit
sample images

References

Image sensors {{photo-stub