In this study we are interested in the implementation of mixed processes for the realization of symmetrical structures shaped in thin layers for integrated photonics and based on silicon plus organic UV210. We used the so called UV210 polymer for shaping the core waveguide. The UV210 polymer made up of poly (p-hydroxystyrene) and poly (t-butyl acrylate) is a chemically amplified resin; a photo-acid generator is added to the matrix of the copolymer in order to increase the sensitivity of the resin and create a chain reaction during developments so as to develop sub-wavelength patterns. Several families of multilayers structures have been produced by specific sub-wavelength lithography plus PECVD, and then properly characterized by including stoichiometry analyses plus imaging by Raman. The advantage of achieving Si/SiO2/UV210/Si/SiO2 symmetry relates first of all to the equations of electromagnetism and guidance which no longer impose a cut-off thickness (or frequency) during extreme miniaturization, but also for an adequate protection of the components by an upper layer of silicon covering the surface of the chip for sensor applications and specific detection of aggressive substances / agents. All structures, including the addition of silicon directly onto the organic, exhibit excellent mechanical strength and optical stability; the last silicon/silica bilayer also acts as a thin protective shell. Various families of resonant photonic structures could be cleanly characterized on platform. Furthermore, by statistical measurements of resonance parameters, we conclude that the processes and properties of the materials obtained have good reproducibility. This opens the way to the realization of sensors dedicated to aggressive substances directly in contact with the resonant elements probing it.
The paper deals with a very high sensitive integrated humidity sensor compatible with CMOS technology. This sensor is a polysilicon Suspended Gate Thin Film Transistor (SGTFT), fabricated using a low temperature surface micromachining process. Microtechnology technics using sacrificial layer are used to fabricate polysilicon bridge which acts as the transistor gate. Transistors are characterized at various humidity rates and transfer characteristics show highly sensitive dependence with humidity. The small air-gap (0.5 μm) between the gate and the channel explains the amplifying effect of the sensitivity: threshold voltage shift is more than 17V when the humidity ratio varies from 20 to 70%.
This paper presents a new device for the pH detection. It is based on a suspended polysilicon gate field effect transistor (SGFET). The sensitive layer is made of silicon nitride as for ISFET technology. The suspended bridge, used as gate electrode, is formed with doped polysilicon covered with silicon nitride layers for electrical insulation. The layers are deposited by Low Pressure Chemical Vapor Deposition (LPCVD). Surface micro-technology allows to obtain a small height (0.5μm) suspended-bridge. In this case, the solution penetrates under the gate.
The high field effect in the gap between the gate and the channel is enough to change the charges distribution. Very high pH sensitivity, greater than 200 mV/pH, is found with this new structure and it is much higher than the usual Nernstian sensitivity of ISFETs. The device concept, electrical characteristics, and the effect of the thickness of the gap between the bridge and the sensitive layer on the pH sensitivity are discussed in this study.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.