PhD Defense of Romain GIRARD-DESPROLET

GImage sensors have experienced a renewed interest with the prominent market growth of wireless communication, together with a diversification of functionalities.
In particular, a recent application known as Ambient Light Sensing (ALS) has emerged for a smarter screen backlight management of display-based handheld devices. Technological progress has led to the fabrication of thinner handsets, which imposes a severe constraint on light sensors’ heights. This thickness reduction can be achieved with the use of an innovative, thinnest and entirely on-chip spectral filter.
 In this work, we present the investigation and the demonstration of plasmonic filters aimed for commercial ALS products. The most-efficient filtering structures are identified with strong emphasis on the stability with respect to the light angle of incidence and polarization state. Integration schemes are proposed according to CMOS compatibility and wafer-scale fabrication concerns. Plasmon resonances are studied to reach optimal optical properties and a dedicated methodology was used to propose optimized ALS performance based on actual customers’ specifications.
The robustness of plasmonic filters to process dispersions is addressed through the identification and the simulation of typical 300 mm fabrication inaccuracies and defects. In the light of these studies, an experimental demonstration of ALS plasmonic filters is performed with the development of a wafer-level integration and with the characterization and performance evaluation of the fabricated structures
to validate the plasmonic solution.

Membres du jury :

Membres du jury :
• Guy VITRANT : Supervisor
• Salim BOUTAMI : Co-supervisor
• Sandrine LHOSTIS : Co-supervisor
• Michael CANVA - Examiner
• Nathalie DESTOUCHES - Rapporteur
• Evgeni POPOV - Rapporteur
• David R.S. CUMMING - Examiner