Rear-gate ISFET with a membrane locking structure using an ultrahigh concentration selective boron diffusion technique

A new rear-gate ISFET with a membrane locking structure has been developed in order to enhance mechanically the adhesion strength in the sensitive membrane. It is necessary to form a deeply diffused ultrahigh concentration region of boron in order to construct a well-shaped and mechanically strong l...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 1993-05, Vol.13 (1), p.212-216
Main Authors: Yagi, Hitoshi, Sakai, Tadashi
Format: Article
Language:English
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Summary:A new rear-gate ISFET with a membrane locking structure has been developed in order to enhance mechanically the adhesion strength in the sensitive membrane. It is necessary to form a deeply diffused ultrahigh concentration region of boron in order to construct a well-shaped and mechanically strong locking structure using selective anisotropic wet etching. A novel selective boron diffusion technique characterized by patterning a liquid-type diffusion source has been investigated and optimum conditions have been obtained for the first time. Applying the conditions, a rear-gate ISFET with a sufficiently mechanically strong locking structure has been fabricated. The characteristics (fundamental FET characteristics, pH response and potassium ion response) of the new ISFET are satisfactory and it is confirmed that the sensor durability is imporved by adding the locking structure.
ISSN:0925-4005
1873-3077
DOI:10.1016/0925-4005(93)85364-G