Color Sensors

Fraunhofer Institute for Integrated Circuits

CMOS Color Sensors by Design of optical Nanostructures

Layer construction
Layer construction of a sensor with nanostructured metal layers (blue), isolation layers (yellow) and the photodiode (red)

We use nanostructured standard CMOS metal layers to implement optical functionality. Thus, standard photo sensors exhibit additional features like color or polarization sensitivity. An example for the resulting layer construction is shown on the left.

The described procedure makes it possible to adjust the spectral function of a filter only by the lateral structuring of a metal layer. Moreover, the sensors can be arranged arbitrarily in lines or arrays.

Examples for the transmission of color sensors:

spectr blue

spectr green

Applications

This evaluation allows to determine the wavelength definitely, i. e. the color of the incident light. The possible applications of spectral sensors are:

  • Control of LEDs in many lighting situations, e. g. LCD backlights
  • Application-specific color sensors for industrial automation with arbitrary spectral function
  • Color sensors for outdoor usage exposed to humidity and variation in temperature e. g. in cars
  • Miniaturized multi-spectral sensors for analysis of gases and fluids
  • Miniaturized perceptive sensors without the need for additional filter layers