A quadrichromatic light-emitting diode (QLED) based visible light communication for mobile phone camera is proposed to improve data rate and enhance illumination effect at the same time. Different from color intensity modulation (CIM), we propose and use color ratio modulation (CRM) in CMOS image sensor based visible light communication to improve data rate. According to the spectral power distribution (SPD) of the QLED and the spectral response of the complementary-metal-oxide-semiconductor (CMOS) image sensor, color multiple-input multiple-output (CMIMO) channel model is set up first to obtain optimal 16-CRM constellation design. Taking full consideration of the high quality of color rendering index (CRI), tunable color temperature (CT), we design a specific data packet structure to realize illumination requirements. A decoding strategy is also addressed for demapping at the receiver. The experimental results demonstrate that the proposed scheme can realize a downlink data rate of 13.2kbit/s, meanwhile, the optical signal source is illumination compatible.

Low resistance metal silicides are widely used in advanced CMOS device as contact and interconnect materials. As device feature size shrinks, Ni silicides are widely used to replace Co silicides due to lower resistivity and ability to silicide narrower feature size (<4nm). During silicide formation, crystallization of the Ni silicide phase is controlled by Ni diffusion upon annealing since Ni is the diffusing species. First, Ni forms Ni 2 Si during annealing at 300ºC, then NiSi is formed at 250ºC and all of the deposited Ni is consumed. NiSi is the desired phase for CMOS device application because it has the lowest sheet resistance among Ni-based silicides. Finally, NiSi 2 is formed at higher temperatures of around 800ºC [1].