Download ISFET specifications

Consejo Superior de Investigaciones Científicas
Instituto de Microelectrónica de Barcelona
Centro Nacional de Microelectrónica
pH-ISFET CHARACTERISTICS
General
Substrate
p-type 4-inch silicon wafers
Chip dimensions
3 x 3 mm
Gate length
10 μm
Gate width
≥ 500 μm
Gate structure
Silicon oxide / Silicon nitride (Standard)
Electrical Specifications
Operational drain voltage, Vd
0.5 - 2.0 V
Operational drain current, Id
0.1 - 1.0 mA
Transconductance, Gm
> 0.5 mA / V
Threshold voltage, Vth
-2.0 – 1.0 V at pH 7 versus Ag/AgCl reference electrode
Leakage current, Il
< 10 nA
Chemical Specifications
Sensitivity, S
≥ 55 mV / pH
Linear range
1 - 13 pH
Accuracy
0.05 pH
Selectivity coefficients
< 10-5 to alkaline metal ions
Long term drift
≤ 1.0 mV/h (after preconditioning)
Lifetime
> 8 months in continuous immersion at pH=7
Standard parameters for silicon nitride gate dielectric.
Consejo Superior de Investigaciones Científicas
Instituto de Microelectrónica de Barcelona
Centro Nacional de Microelectrónica
0.3
1233-12-138
0.2
1233-12-140
0.1
1233-12-139
600
560
0
Potential (mV)
1233-12-141
-0.1
-0.2
-0.3
-0.4
520
480
440
400
-0.5
360
-0.6
0
0
2
4
6
8
10
12
100
200
300
500
600
700
800
Time (min)
Figure 1. Calibration plots for several
Si3N4 pH-ISFET (slope average: 56.8
±0.1 mV 7pH)
Figure 2. Study of pH-ISFET stability for
pH 4 and 7 jumps.
100
90
80
70
60
50
40
30
20
10
0
-1.5
400
14
pH
Id (uA)
Vout, V
0.4
-1
-0.5
0
0.5
1
Vg (V)
Figure 3.Current-voltage characteristics of a pHISFET measured at VD :0.5 V during 8 months
immersed in aqueous solution.
1.5
900
1000