Back to results
US 4,044,373 AGranted
IGFET with gate protection diode and antiparasitic isolation means
AssigneeHitachi, Ltd.
InventorsKosei Nomiya, Toshihiko Kohisa, Isao Matsumura
Life of this patent
Estimating the term…
Abstract
Described are insulated gate-type field effect transistors used in capacitive memory circuits and having protective diodes for protecting the insulating films below the gate electrodes from electrical breakdown, in which parasitic transistor action which might be caused by minority carriers injected into semiconductor substrates by noise signals applied to the protective diodes are eliminated by means for suppressing injection of minority carriers or by means for preventing injected minority carriers from reaching the drain regions of the field effect transistors.
Claims7
In a semiconductor device comprising:
- an insulated gate type field effect element including a semiconductor substrate of first conductivity type, a pair of source and drain regions of second conductivity type opposite to said first conductivity type formed in a surface of said semiconductor substrate, an insulated gate electrode disposed on said surface between said source and drain regions, and an insulating film interposed between said insulated gate electrode and said semiconductor substrate;
- a protecting diode means formed unitarily with said field effect element and connected in parallel between said insulated gate electrode and said semiconductor substrate for preventing the insulating film below said gate electrode from breakdown, said protecting diode means including a semiconductor region and an electrode means with a rectifying barrier disposed therebetween, said rectifying barrier having a backward breakdown voltage lower than the breakdown voltage of the insulating film below said gate electrode;
- the improvement comprising
- isolation means for electrically isolating said semiconductor region of said protecting diode means from said semiconductor substrate in which said field effect element is formed;
- and wherein
- the conductivity type of said semiconductor region of said protecting diode means is said first conductivity type, and said isolation means includes a semiconductor layer of said second conductivity type interposed between said semiconductor region of said protecting diode means and said semiconductor substrate;
- and wherein
- said semiconductor layer is biased in the backward polarity to said semiconductor region of said protecting diode means and said semiconductor substrate;
- and wherein
- the semiconductor region of said protecting diode means is connected together with said semiconductor substrate.
7 more elements
A semiconductor device comprising:
- a semiconductor substrate of first conductivity type;
- an insulated gate type field effect element including a pair of source and drain regions of second conductivity type opposite to said first conductivity type formed in a surface of said semiconductor substrate, an insulated gate electrode disposed on said surface between said source and drain regions, and an insulating film interposed between said insulated gate electrode and said semiconductor substrate;
- a protective diode means including a terminal region formed in said surface of said semiconductor substrate with a rectifying barrier disposed between said terminal region of the protective diode means and said semiconductor substrate, said rectifying barrier having a backward breakdown voltage lower than a voltage which causes the insulating film below said gate electrode to breakdown;
- an auxiliary semiconductor region of said second conductivity type formed in said surface of said semiconductor substrate and disposed between said field effect element and said terminal region of the protecting diode means for preventing minority carriers injected through said rectifying barrier of said protecting diode means into said semiconductor substrate from reaching said drain region;
- and
- conductive means for connecting the terminal region of said protecting diode with said insulated gate electrode.
3 more elements
Dependencies are inferred from the claim text.