Method for manufacture of a selective chemical sensitive FET transducer

Claim 1

A method for manufacturing a chemical selective field-effect transistor device, which comprises the steps of: forming spaced apart diffusion layers on one surface of a semiconductor wafer made of silicon, said diffusion layers having a predetermined doping polarity opposite to that of the semiconductor wafer; forming electroconductive channel stopper layers, one for each two of said diffusion layers, between the adjacent two of the diffusion layers except for one end portion of said diffusion layers and on said one surface of the semiconductor wafer, for avoiding formation of an electroconductive channel between said adjacent two of the diffusion layers, said channel stopper layer having a doping polarity opposite to that of the diffusion layers; forming a cut-out portion in the semiconductor wafer so as to leave a substantially comb-shaped arrangement of elongated bodies of the semiconductor wafer in which said one end portion of the diffusion layers is located; applying a layer of silicon dioxide over the entire surface area of the semiconductor wafer subsequent to the formation of the cut-out portion in the semiconductor wafer; applying an electrically insulating layer sensitive to change in pH value and having an impermeability to a solution containing a particular chemical substance to which the device is exposed during measurement, over the silicon dioxide layer; and trimming the semiconductor wafer along scribing lines, to provide separate chemical sensitive field-effect transistors.

Claim 2

A method for manufacturing a chemical selective field-effect transistor device, which comprises the steps of: forming spaced apart diffusion layers on one surface of a semiconductor wafer made of silicon, said diffusion layers having a predetermined doping polarity opposite to that of the semiconductor wafer; forming electroconductive channel stopper layers, one for each two of said diffusion layers, between the adjacent two of the diffusion layers except for one end portion of said diffusion layers and on said one surface of the semiconductor wafer, for avoiding formation of an electroconductive channel between said adjacent two of the diffusion layers, said channel stopper layer having a doping polarity opposite to that of the diffusion layers; forming a cut-out portion in the semiconductor wafer so as to leave a substantially comb-shaped arrangement of elongated bodies of the semiconductor wafer in which said one end portion of the diffusion layers is located; applying a layer of silicon dioxide over the entire surface area of the semiconductor wafer subsequent to the formation of the cut-out portion in the semiconductor wafer; applying an electrically insulating layer sensitive to change in pH value and having an impermeability to a solution containing a particular chemical substance to which the device is exposed during measurement, over the silicon dioxide layer; and trimming the semiconductor wafer along scribing lines, to provide separate chemical sensitive field-effect transistors.