Semiconductor apparatus and horizontal register for solid-state image pickup apparatus with protection circuit for bypassing an excess signal

• US 5,641,981 A
• Filed: 06/14/1996
• Issued: 06/24/1997
• Est. Priority Date: 06/29/1992
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Hibi, Hiroshi, Isono, Hideto
• Primary Examiner(s): Ngo , Ngan V.
• Application Number:
  US08/663,609
• Time in Patent Office: 375 Days
• Field of Search: 257/356, 257/360, 257/361, 257/362, 257/363, 257/355, 257/357, 257/358, 257/359
• US Class Current: 257/360
• CPC Class Codes: H01L 27/0251 for MOS devices

Abstract

A semiconductor apparatus connected between a signal input line and a grounding line is formed on a semiconductor substrate with a protection circuit connected between the signal input line and the grounding line, in parallel with the semiconductor apparatus. The protection circuit is formed, for example, of bipolar transistors, diodes, or MOS transistors. The protection circuit is designed to prevent an excess signal supplied on the signal line from damaging the semiconductor apparatus, such as by breaking down a dielectric layer formed at a gate of a MOS transistor. The protection circuit may further be connected to a potential line that is connected to an external source of voltage.

Claims

1. An electric circuit, comprising:

a circuit section including a capacitor portion having a first node connected to a signal input line inputting a voltage signal thereto and a second node connected to a reference voltage line; and

a protection circuit connected between said signal input line and said reference voltage line, said protection circuit protecting said capacitor portion such that, when said capacitor portion receives a voltage which would break said capacitor portion, an electric current flows between said signal input line and said reference voltage line through said protection circuit, wherein said protection circuit comprises;

a first voltage line;

a second voltage line whose voltage is higher than said reference voltage line;

a first diode having a first anode and a first cathode, said first anode being connected to said first voltage line and said first cathode being connected to said signal input line;

a second diode having a second anode and a second cathode, said second anode being connected to said signal input line and said second cathode being connected to said second voltage line;

a third diode having a third anode and a third cathode, said third anode being connected to said first voltage line and said third cathode being connected to said reference voltage line; and

a fourth diode having a fourth anode and a fourth cathode, said fourth anode being connected to said reference voltage line and said fourth cathode being connected to said second voltage line.

2. An electric circuit, comprising:

a circuit section including a capacitor portion having a first node connected to a signal input line inputting a voltage signal thereto and a second node connected to a reference voltage line; and

a protection circuit connected between said signal input line and said reference voltage line, said protection circuit protecting said capacitor portion such that, when said capacitor portion receives a voltage which would break said capacitor portion, an electric current flows between said signal input line and said reference voltage line through said protection circuit, wherein said protection circuit comprises;

a voltage line;

a first MOS transistor connected between said signal input line and said voltage line, a channel thereof being connected to said voltage line and a gate thereof being connected to both said signal input line through a first capacitor and said voltage line through a first resistor; and

a second MOS transistor connected between said reference voltage line and said voltage line, a channel thereof being connected to said voltage line and a gate thereof being connected to both said reference voltage line through a second capacitor and said voltage line through a second resistor.

3. A semiconductor apparatus, comprising:

a semiconductor structure;

a first portion of said semiconductor structure being connected to a reference voltage line;

an insulating film covering at least a second portion of said semiconductor structure;

an electrode formed on said insulating film such that said electrode is above said second portion of said semiconductor structure, said electrode being connected to a signal input line inputting a voltage signal thereto; and

a protection circuit having a first terminal connected to said signal input line and a second terminal connected to said reference voltage line;

said protection circuit directing an excess signal on said signal input line from said input signal line, through said protection circuit, and to said reference voltage line, said excess signal having a magnitude at least as large as a break down voltage of said insulating film;

wherein said protection circuit comprises a first MOS transistor having one of a drain and source as said first terminal and the other of said drain and source connected to a line of potential and a second MOS transistor having said other of said drain and source connected to said line of potential and said one of said drain and source as said second terminal.

5. The semiconductor apparatus as set forth in claim 3, wherein said semiconductor structure comprises a MOS transistor with said electrode being a gate electrode and said insulating film comprising a gate oxide layer.

6. The semiconductor apparatus as set forth in claim 3, wherein said semiconductor structure comprises a CCD with said electrode comprising a gate transfer electrode and said second portion of said semiconductor structure comprising an output gate of said CCD.

8. A semiconductor apparatus as set forth in claim 3, wherein a gate of said first transistor is connected through a capacitor to said first terminal and through a resistor to said line of potential.

9. A semiconductor apparatus as set forth in claim 8, wherein a gate of said second transistor is connected through a capacitor to said first terminal and through a resistor to said line of potential.

10. A semiconductor apparatus as set forth in claim 3, wherein said semiconductor structure is connected between said first and second terminals.

4. A protection circuit for use with an electronic apparatus having a first node connected to a signal input line for receiving a voltage signal and a second node connected to a reference voltage line, said protection circuit comprising:

a first circuit having a first terminal connected to said signal input line and a second terminal connected to a potential line, which is connected to an external source;

a second circuit having a first terminal connected to said reference voltage line and a second terminal connected to said potential line;

wherein said first circuit receives an excess signal superimposed on said input signal line and applies a potential to said potential line to activate said second circuit and to produce a protection path from said input signal line, to said first terminal of said first circuit, to said second terminal of said first circuit, to said second terminal of said second circuit, and to said reference voltage line whereby said excess signal bypasses said electronic apparatus;

wherein said first and second circuits each comprises a MOS transistor with said first terminal being one of a source and drain and said second terminal being the other of said source and drain.

7. The protection circuit as set forth in claim 4, wherein each MOS transistor has a resistor and a capacitor connected in series between said first terminal and said second terminal with a gate of said MOS transistor being connected between said resistor and said capacitor.