Method of fabricating an ion sensitive field effect transistor with a Ta.sub.2 O.sub.5 hydrogen ion sensing membrane
First Claim
1. A method of fabricating an ion sensitive field effect transistor with a Ta2 O5 hydrogen ion sensing membrane, comprising the steps of:
- forming a Si3 N4 /SiO2 dielectric layer over a gate region of said ion sensitive field effect transistor;
depositing a film of Ta2 O5 having a thickness of about 400 to 500 Å
on said Si3 N4 /SiO2 dielectric layer on said ion sensitive field effect transistor; and
annealing the resultant film at a temperature of about 375°
to 450°
C. in oxygen gas ambience.
1 Assignment
0 Petitions
Accused Products
Abstract
A fabricating method of an ion sensitive field effect transistor (ISFET) with a Ta2 O5 hydrogen ion sensing membrane, which comprises the steps of forming Ta2 O5 film with a thickness of about 400 to 500 A by RF reactive sputtering on a Si3 N4 /SiO2 gate dielectric layer of the pH-ISFET, and annealing the resultant film at about 375° to 450° C. in oxygen gas ambience for about one hour. In forming the Ta2 O5 film on the pH-ISFET, the Ta2 O5 film formed in the area except the gate region of the pH-ISFET is removed by a lift-off process utilizing a positive PR film. The Ta2 O5 gate pH-ISFET according to the present invention has higher sensitivity and more stable operation characteristics than those of the conventional pH-ISFET, while the productivity and stability thereof are greatly improved by effecting a whole wafer process.
142 Citations
20 Claims
-
1. A method of fabricating an ion sensitive field effect transistor with a Ta2 O5 hydrogen ion sensing membrane, comprising the steps of:
-
forming a Si3 N4 /SiO2 dielectric layer over a gate region of said ion sensitive field effect transistor; depositing a film of Ta2 O5 having a thickness of about 400 to 500 Å
on said Si3 N4 /SiO2 dielectric layer on said ion sensitive field effect transistor; andannealing the resultant film at a temperature of about 375°
to 450°
C. in oxygen gas ambience. - View Dependent Claims (2, 3, 8)
-
-
4. An ion sensitive field-effect transistor, comprising:
-
a semiconductor substrate of a first conductivity type having first and second diffusion regions of a second conductivity type separated and spaced-apart by a gate region, said first and second diffusion regions respectively defining a source region and a drain region; a dielectric layer positioned upon the surface of said semiconductor substrate covering said source region, said gate region and said drain region; an ion sensitive membrane formed on the dielectric layer over said gate region, said ion sensitive membrane being a Ta2 O5 compound having a thickness of approximately 400-500 Å
; andfirst and second metal layers formed in V-shape and positioned upon the dielectric layer over said source region and said drain region, each of said first and second metal layers having a base at a center of one of said source region and said drain region. - View Dependent Claims (5, 6, 7, 9)
-
-
10. A method of fabricating an ion sensitive field effect transistor on a semiconductor substrate of a first conductivity type having first and second diffusion regions of a second conductivity type separated and spaced-apart by a gate region, said first and second diffusion regions respectively defining a source region and a drain region, comprising the steps of:
-
forming a dielectric layer over the surface of said semiconductor substrate covering said source region, said gate region and said drain region; forming first and second metal layers in V-shape positioned upon the dielectric layer over said source region and said drain region, each of said first and second metal layers having a base at a center of one of said source region and said drain region; depositing an ion sensitive layer of Ta2 O5 compound having a thickness of approximately 400-500 Å
on the dielectric layer over said gate region; andannealing said ion sensitive layer of Ta2 O5 compound at a temperature in the range of 375°
to 425°
C. in a reactive gas ambience. - View Dependent Claims (11, 12, 13, 14)
-
-
15. A method of fabricating an ion sensitive field effect transistor on a semiconductor substrate of a first conductivity type having first and second diffusion regions of a second conductivity type separated and spaced-apart by a gate region, each of said first and second diffusion regions respectively defining a source region and a drain region, comprising the steps of:
-
forming an insulation layer over the surface of said semiconductor substrate covering said source region, said gate region and said drain region; forming first and second metal layers in a V-shape, positioned upon the insulation layer over said source region and said drain region, each of said first and second metal layers having a base at a center of each of said source and drain regions, and a channel having two ends extending in opposite directions away from the center of each of said source and drain regions; depositing a photoresist layer on the surface of said first and second metal layers, thereby exposing said gate region; sputtering a film of Ta2 O5 having a thickness of approximately 400-500 Å
over the surface of said photoresist layer and said gate region in a first gas ambience; andremoving said photoresist layer, thereby exposing the film of Ta2 O5 having a thickness of approximately 400-500 Å
over said gate region; andannealing said semiconductor substrate having said film of Ta2 O5 over the gate region in a second gas ambience. - View Dependent Claims (16, 17, 18)
-
-
19. An ion sensitive field effect transistor, comprising:
-
a semiconductor substrate of a first conductivity type having first and second diffusion regions of a second conductivity type separated and spaced-apart by a gate region, each of said first and second diffusion regions respectively defining a source region and a drain region; an insulation layer disposed over the surface of said semiconductor substrate covering said source region, said gate region and said drain region; first and second metal layers positioned upon the insulation layer over said source region and said drain region, each of said first and second metal layers having a base at a center of each of said source and drain regions, and a channel having two ends extending in opposite directions away from the center of each of said source and drain regions; and an ion sensitive layer of Ta2 O5 having a thickness of approximately 400-500 Å
disposed on the insulation layer over the gate region, wherein said ion sensitive layer being disposed on said insulation layer over the gate region comprises the steps of;depositing a photoresist layer on the surface of said first and second metal layers, thereby exposing said gate region; sputtering said ion sensitive layer of Ta2 O5 having a thickness of approximately 400-500 Å
over the surface of said photoresist layer and said gate region in a first gas ambience of argon and oxygen; andremoving said photoresist layer, thereby exposing said ion sensitive layer of Ta2 O5 having a thickness of approximately 400-500 Å
over said gate region; andannealing said semiconductor substrate having said ion sensitive layer of Ta2 O5 over the gate region in a second gas ambience of oxygen. - View Dependent Claims (20)
-
Specification