Device for protecting semiconductor IC
View Patent ↗Embodiments relate to a device for protecting a semiconductor IC device from an electrostatic discharge (ESD). According to embodiments, the device may have a rapid response speed and a stable operation against an ESD and may efficiently protect an internal circuit of a semiconductor IC from an ESD voltage lower than a junction breakdown voltage. According to embodiments, the device for protecting the semiconductor IC may include a pad, an internal circuit electrically connected to the pad, and a protection circuit which forms a discharge path between the pad and the internal circuit and disconnects the pad and the internal circuit, when an overvoltage due to an electrostatic discharge is applied to the pad.
1. A device, comprising:
a pad;
an internal circuit electrically connected to the pad; and
a protection circuit coupled between the pad and the internal circuit, wherein the protection circuit comprises:
a plurality of grounded gate NMOSs (GGNMOSs) connected in parallel between the pad and the internal circuit in a multi-stage form, and
a high-voltage transistor connected between the pad and the plurality of GGNMOSs,
wherein a gate and a drain of the high-voltage transistor are connected to the pad in parallel, and a source of the high-voltage transistor is connected to ground.
2. The device of claim 1 , wherein when a nominal voltage is applied to the pad, the protection circuit is turned off to send the applied nominal voltage to the internal circuit, and when the overvoltage higher than the nominal voltage is applied to the pad, the protection circuit is turned on to form the discharge path.
3. The device of claim 1 , wherein drains of the plurality of GGNMOSs are commonly connected to the pad, and gates and sources of the plurality of GGNMOSs are commonly connected to ground in parallel.
4. The device of claim 1 , wherein a source of the high-voltage transistor and gates and sources of the plurality of GGNMOSs are connected to ground via a well of the GGNMOSs.
5. The device of claim 1 , wherein a threshold voltage of the high-voltage transistor is equal to or greater than twice an operation voltage of the internal circuit and is less than a junction breakdown voltage.
6. The device of claim 1 , wherein when a nominal voltage is applied to the pad, a voltage lower than a threshold voltage of the high-voltage transistor is applied to the high-voltage transistor, the high-voltage transistor is turned off, and the applied nominal voltage is sent to the internal circuit, and wherein when the overvoltage higher than the nominal voltage is applied to the pad, the high-voltage transistor is turned on to form the discharge path to ground.
7. The device of claim 6 , wherein, when a potential difference across a well of the GGNMOSs increases due to current flowing through the high-voltage transistor which is turned on, the increased potential difference decreases an operation voltage of the protection circuit.
8. The device of claim 1 , wherein the protection circuit comprises a resistor connected between gates of the plurality of GGNMOSs and ground.
9. The device of claim 8 , wherein the resistor and the gates of the plurality of GGNMOSs are commonly connected to a source of the high-voltage transistor.
10. The device of claim 1 , wherein the protection circuit comprises:
a silicon controlled rectifier (SCR) including a npn bipolar transistor and a pnp bipolar transistor; and
a high-voltage transistor connected between a well of the SCR and the pad.
11. The device of claim 10 , wherein the SCR comprises a 2-terminal/4-layer pnpn structure including the npn bipolar transistor and the pnp bipolar transistor.
12. The device of claim 10 , wherein the high-voltage transistor is connected between a P-well of the npn bipolar transistor and the pad.
13. The device of claim 10 , wherein when the overvoltage higher than a nominal voltage is applied to the pad, the high-voltage transistor is turned on, and a potential difference across a P-well of the npn bipolar transistor drives the npn bipolar transistor due to current flowing through the high-voltage transistor, which is turned on.
14. The device of claim 13 , wherein, when the npn bipolar transistor is driven, the pnp bipolar transistor is driven at a lower trigger voltage.
15. A device, comprising:
a pad;
an internal circuit electrically connected to the pad; and
a protection circuit coupled between the pad and the internal circuit,
wherein the protection circuit comprises:
a plurality of grounded gate NMOSs (GGNMOSs) connected in parallel between the pad and the internal circuit in a multi-stage form;
a high-voltage transistor connected between the pad and the plurality of GGNMOSs; and
a resistor connected between gates of the plurality of GGNMOSs and ground,
wherein a gate and a drain of the high-voltage transistor are connected to the pad in parallel and a source of the high-voltage transistor and gates of the plurality of GGNMOSs are commonly connected to the resistor.
16. The device of claim 15 , wherein the resistor comprises polycrystalline silicon.
17. The device of claim 15 , wherein drains of the plurality of GGNMOSs are commonly connected to the pad, gates of the plurality of GGNMOSs are commonly connected to the resistor, and sources of the plurality of GGNMOSs are commonly connected to ground.
18. The device of claim 15 , wherein a source of the high-voltage transistor and gates of the plurality of GGNMOSs are connected to ground via the resistor, and sources of the plurality of GGNMOSs are commonly connected to ground.
19. A device, comprising:
a pad;
an internal circuit electrically connected to the pad; and
a protection circuit coupled between the pad and the internal circuit, wherein the protection circuit comprises:
a plurality of grounded gate NMOSs (GGNMOSs) connected in parallel between the pad and the internal circuit in a multi-stage form;
a high-voltage transistor connected between the pad and the plurality of GGNMOSs; and
a resistor connected between gates of the plurality of GGNMOSs and ground,
wherein when the overvoltage higher than a nominal voltage is applied to the pad, the high-voltage transistor is turned on, a voltage corresponding to a potential difference across the resistor is applied to gates of the plurality of GGNMOSs due to current flowing through the high-voltage transistor which is turned on, and an operation voltage of the GGNMOSs decreases.