Monolithic and heterogeneous integration of RGB micro-LED arrays with pixel-level optics array and CMOS image processor to enable small form-factor display applications

We report on Quantum Photonic Imager (QPI) device, which is comprised of a spatial array of digitally addressable multicolor micro-scale pixels, wherein each pixel is a vertical stack of Red, Green, Blue light emitting diodes (LEDs) with RGB light emission sharing the same optical aperture. Starting with Blue, Green and Red epi-wafers first processed to create any desired size micro-LED arrays with 5-10 μm pixel pitch (pixelated), each of the 3 processed epi-wafers are sequentially bonded to a single receiving handle wafer followed by substrate removal and backside process to create a handle wafer with Blue, Green and Red micro-LED pixel arrays stacked vertically on top of each other. The handle wafer, which encapsulates stacked RGB pixel array, is also monolithically pre-processed to incorporate micro-scale pixel level optical elements array that is designed to collimate and directionally modulate the multi-color light emitted from the individual pixels of the LED array. A proprietary CMOS image processor is then bonded to the handle wafer combining the vertically stacked arrays of micro-scale pixel-level optics and LEDs. The QPI device alleviates inefficiencies associated with spatially or temporally multiplexed color pixel architectures, enabling high pixel density leading to small form-factor display system design. Low power display system operation is enabled by the QPI device. Small form-factor multi-color "wearable" AR displays with sub-1W power consumption utilizing QPI optically coupled to the edge of the AR combining lens have been demonstrated. Additionally, QPI enabled compact light field displays, head-up displays and pico projectors have also been demonstrated.