Parylene supported 20um*20um uncooled thermoelectric infrared detector with high fill factor

Mohammad J. Modarres-Zadeh; Zachary S. Carpenter; Mark G. Rockley; Reza Abdolvand

doi:10.1117/12.920864

31 May 2012 Parylene supported 20um*20um uncooled thermoelectric infrared detector with high fill factor

Mohammad J. Modarres-Zadeh, Zachary S. Carpenter, Mark G. Rockley, Reza Abdolvand

Proceedings Volume 8353, Infrared Technology and Applications XXXVIII; 83531K (2012) https://doi.org/10.1117/12.920864
Event: SPIE Defense, Security, and Sensing, 2012, Baltimore, Maryland, United States

Abstract

Presented is a novel design for an uncooled surface-micromachined thermoelectric (TE) infrared (IR) detector. The detector features a P-doped polysilicon/Nichrome (Cr20-Ni80) thermocouple, which is embedded into a thin layer of Parylene-N to provide structural support. The low thermal conductivity (~0.1W/m.K), chemical resistance, and ease of deposition/patterning of Parylene-N make it an excellent choice of material for use in MEMS thermal detectors. This detector also features an umbrella-like IR absorber composed of a three layer stack of NiCr/SiN/NiCr to optimize IR absorption. The total device area is 20 um * 20 um per pixel with an absorber area of ~19 um * 19 um resulting in a fill factor of 90%. At room temperature, a DC responsivity of ~170V/W with a rise time of less than 8 ms is measured from the fabricated devices in vacuum when viewing a 500K blackbody without any concentrating optics. The dominant source of noise in thermoelectric IR detectors is typically Johnson noise when the detectors are operating in an open circuit condition. The fabricated detectors have resistances about 85KOhm which results in Johnson noise of about 38nV/Hz^0.5. The D* is calculated to be 9 * 10⁶ cm*Hz^0.5/ W. Preliminary finite element analysis indicates that the thermal conduction from the hot junction to the substrate through the TE wires is dominant ( G_TE >> G_parylene) considering the fabricated dimensions of the parylene film and the TE wires. Thus, by further reducing the size of the TE wires, G_TE can be decreased and hence, responsivity can be improved while the parylene film sustains the structural integrity of the cell.

Citation Download Citation

Mohammad J. Modarres-Zadeh, Zachary S. Carpenter, Mark G. Rockley, and Reza Abdolvand "Parylene supported 20um*20um uncooled thermoelectric infrared detector with high fill factor", Proc. SPIE 8353, Infrared Technology and Applications XXXVIII, 83531K (31 May 2012); https://doi.org/10.1117/12.920864

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

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.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available