JP2870514B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a plurality of power supplies electrically separated from each other, and more particularly, to an electrostatic discharge (Electric Static Discharge) comprising a protection diode.
The present invention relates to an improvement in a semiconductor device including a discharge (ESD) protection circuit.

[0002]

2. Description of the Related Art Some semiconductor devices have a power supply for each circuit in the device. For example, when a semiconductor memory and a CMOS buffer capable of driving a large-capacity load outside the device are incorporated in the same semiconductor device, the power supply -GND at the time of buffer driving is used.
(Ground), the power supply-GND of the memory circuit is relatively sensitive to the potential fluctuation between the power supply and GND.
In order to prevent potential fluctuation between D, the power supply and GND of the buffer and the memory may be separated.

In recent years, as semiconductor devices have become more highly integrated and a single power supply cannot supply current to all circuits in the device, a single semiconductor device is provided with a plurality of power supply input terminals.
As a result, in one semiconductor device, a circuit in the device may have a power supply for each circuit.

Here, a conventional configuration in which an electrostatic discharge protection circuit (hereinafter referred to as a "protection circuit") is provided in such a semiconductor device having a plurality of power supplies will be described with reference to FIGS. 3, 4 and 5. FIG. explain. The semiconductor device shown in FIG. 3 has N circuits C1, C2, C3,..., CN, and the circuit C1 is connected to a power supply E1 and a GND (or a negative power supply) G1.
The circuit C2 is connected to the power supply E2 and GNDG2,
Each of the circuits C1 to CN respectively has a power source E1, E2, E
····· EN and each GND (or negative power supply) G1, G
2, G3,... GN.

Here, for example, a protection circuit 2-1 is provided between the power supply E1 and the power supply E2, a protection circuit 2-2 is provided between the power supply E1 and the power supply E3, and a protection circuit is provided between the GNDG1 and the GNDG2. A circuit 2-3 is inserted between GNDG1 and GNDG3, and a protection circuit 2-6 is inserted between GNDG1 and GNDG3, between each power supply and each other power supply, and between each GND and each other GND. And a protection circuit is inserted between them.

As shown in FIG. 4, this protection circuit is often composed of two diodes D1 and D2. Now, when the protection circuit shown in FIG. 4 is inserted between GNDG1 and GNDG2 shown in FIG. 3, as shown in FIG.
Is connected in series by two diodes, a diode D3 and a diode D1, between the terminal 1 operating on the basis of. At this time, even if a high voltage pulse due to electrostatic discharge is applied between the terminal 1 and GNDG2, D1 and D
The pulse is alleviated by the capacity of the two diodes 3 to prevent the internal circuit E1 from being destroyed by the high voltage pulse.

As described above, the semiconductor device has a plurality of power supplies and G
When ND is used, a circuit that operates based on one power supply and GND is protected from high voltage pulses due to electrostatic discharge applied to all other power supplies and GND, and internal circuit destruction is prevented. As shown in FIG. 3, a protection circuit is inserted between each power supply and each other power supply, and between each GND and each other GND.

[0008]

However, FIGS.
The conventional protection circuit insertion method as shown in FIG. 5 has a problem that the required number of protection circuits increases at an accelerating rate as the number of power supplies and the number of GNDs increase, which causes an increase in the area of the semiconductor integrated circuit. . That is, in the conventional method, the required number of protection circuits with respect to the number N of power supplies is obtained by the following equation (1).

[0009]

## EQU00001 ## Required number of protection circuits = (N-1) + (N-2) +... +1 For example, if the semiconductor device has six power supplies, 15 protection circuits are required. If the number of GNDs is six, the same number of protection circuits are required on the GND side, so a total of 30 protection circuits are required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to reduce the required number of protection circuits in a semiconductor device having a plurality of power supplies and GND. It is an object of the present invention to provide a semiconductor device capable of preventing an increase in the area of the semiconductor device due to a large number of semiconductor devices.

[0011]

In order to achieve the above object, a semiconductor device according to the present invention is a semiconductor device having a plurality of power supplies electrically separated from each other. , A protection circuit using an electrostatic discharge protection element is provided between the contact and each positive power supply, and each negative power supply or each ground is radially connected with a common contact as a center. A protection circuit using an electrostatic discharge protection element is provided between each negative power supply and each ground.

Further, the electrostatic discharge protection element is realized by a protection diode, and the protection circuit is provided between any positive power supply and each other positive power supply, or between any negative power supply or each ground and each other positive power supply. The circuit is characterized in that a plurality of protection diodes are connected in series between the negative power supply and each ground.

[0013]

According to the present invention, the number of power supplies N or the number of grounds N
, N protection circuits are required. In the conventional example, the number of protection circuits is required for the number of combinations of the power supply and the ground. Therefore, according to the present invention, the required number of protection circuits can be reduced as the number of power supply or the ground increases.
Therefore, when a plurality of (for example, six) or more power supplies and grounds are provided, the required number of protection circuits is reduced, and an increase in the area of the semiconductor device due to the large number of required protection circuits is prevented. be able to.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a semiconductor device according to the present invention. The semiconductor device shown in FIG. 1 has N circuits C1, C2, C3,. To CN are positive power supplies E
1, E2, E3,... EN and GND (or negative power supply) G1, G2, G3,.

Here, the positive power supplies E1 to EN are connected to a common contact A.
, And protection circuits 1-1 and 1-2 for protecting each circuit from a high voltage pulse due to electrostatic discharge between the contact A and each of the positive power supplies E1 to EN.
... 1-N is inserted. The negative power supplies (or GND) G1 to GN are radially connected around a common contact B, and the contact B and each negative power supply (or GND) are connected.
D) Between G1 and GN, protection elements 1-1 and 1- for protecting each circuit from high voltage pulses due to electrostatic discharge.
2,... 1-N are inserted.

Here, the protection circuits 1-1 to 1-N are realized by, for example, protection diodes, and include one positive power supply and another positive power supply or one negative power supply (or GN).
D) and another negative power supply (or GND) are connected by a circuit in which a plurality of protection diodes are connected in series.

According to the present embodiment, the number of protection circuits required for the number N of positive power supplies or the number N of negative power supplies (or GND) is N. In the conventional example, the number of protection circuits is required by the number of combinations of the positive power supply or the negative power supply (or GND). Therefore, according to the present embodiment, as the number of power supplies (GND) increases, the required number of the protection circuits is increased. It can be reduced.

In this embodiment, a protection diode is used as a protection element used in the protection circuit. However, the protection element in the present invention is not limited to a protection diode. Further, the circuit configuration of the protection circuit according to the present invention is not limited to those shown in FIGS.

[0019]

An embodiment according to the present invention will be described below with reference to FIG. FIG. 2 shows the number of power supplies and G of the semiconductor device according to the present invention.
An example when the number of NDs is 6 is shown.

The positive power sources E1 to E6 are radially connected around a common contact A, and the contact A and each of the positive power sources E1 to E6 are connected.
Protection circuits 5-1, 5-2, 5-3 for protecting each circuit from a high voltage pulse due to electrostatic discharge are provided between E6 and E6.
5-5, 5-10 and 5-12 are inserted. Also,
Each of the GNDG1 to G6 is radially connected around a common contact B, and a protection circuit 5-4 is provided between the contact B and each of the GNDG1 to G6 to protect each circuit from high voltage pulses due to electrostatic discharge. , 5-6, 5-7, 5-8, 5
-9 and 5-11 are inserted. These protection circuits are circuits in which any positive power supply and another positive power supply or any GND and another GND are connected in series by a plurality of protection diodes.

In this embodiment, the necessary number of protection circuits is 12 in total, each of which includes 6 protection circuits on the power supply side and 6 on the GND side. On the other hand, in the conventional protection circuit insertion method, a total of 30 protection circuits are required for each of the 15 power supply-side GNDs, and in this embodiment, the required number of protection circuits can be considerably reduced.

Here, considering the area of the protection diode required for the protection circuit, one protection circuit is connected between each power supply (or between each GND) in the conventional example, but is connected between each power supply (in the present invention). Or between each GND) is connected by two protection circuits. Because the protection circuit acts as a capacitor,
When two are connected in series, the capacity is halved. Therefore, in the present invention, if the capacity of the protection element between the power supplies is to be made the same as the conventional one, the size (area) of each diode must be doubled. Comparing the total area of the protection element according to the number of power supplies (GND) of the conventional example and the present invention based on this condition,
Table 1 below shows the case where the area of the diode in one protection circuit of the conventional example is 1.

[0023]

[Table 1] Number of combinations of power supply and GND 2 3 4 5 6 7 Total area of protection diode of conventional example 2 6 12 20 30 42 Total area of protection diode of the present invention 8 12 16 20 24 28 As shown in Table 1, It can be seen that when the number of power supplies and GNDs is 6 or more, the total area of the protection diodes is smaller in the protection circuit insertion method according to the present invention than in the conventional method.

[0024]

As described above, according to the present invention,
In a semiconductor device having a plurality of power supplies electrically separated from each other, a protection circuit in which each positive power supply is radially connected around a common contact and an electrostatic discharge protection element is provided between the contact and each positive power supply In addition, each negative power supply or each ground is radially connected around a common contact, and an electrostatic discharge protection element is used between the contact and the positive power supply, or between the contact and each negative power supply or each ground. Since the protection circuit is provided, the required number of protection circuits can be reduced as the number of power supplies or negative power supplies (grounds) increases, as compared with the conventional example. This is because the required number of protection circuits is large. An increase in the area of the semiconductor device can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a semiconductor device according to the present invention.

FIG. 2 is a block diagram showing a circuit configuration of an embodiment of the semiconductor device according to the present invention.

FIG. 3 is a block diagram illustrating a circuit configuration of a conventional semiconductor device.

FIG. 4 is a circuit diagram illustrating an example of a protection circuit.

FIG. 5 is a circuit diagram illustrating an example of a protection circuit.

[Explanation of symbols]

A, B contacts C1, C2, C3, C4, C5, C6, CN circuit E1, E2, E3, E4, E5, E6, EN power supply G1, G2, G3, G4, G5, G6, GN GND
(Ground) 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1
-7, 1-8 Protection circuit 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2
-7, 2-8, 2-9, 2-10, 2-11, 2-12
Protection circuit 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5
-7, 5-8, 5-9, 5-10, 5-11, 5-12
Protection circuit

Claims (4)

(57) [Claims] In a semiconductor device having a plurality of power supplies electrically separated from each other, each positive power supply is radially connected around a common contact, and an electrostatic discharge protection element is provided between the contact and each positive power supply. A semiconductor device, comprising: a protection circuit using the semiconductor device. 2. In a semiconductor device having a plurality of power supplies electrically separated from each other, each negative power supply or each ground is radially connected around a common contact, and between the contact and each negative power supply or each ground. A semiconductor device, further comprising a protection circuit using an electrostatic discharge protection element. 3. The semiconductor device according to claim 1, wherein the electrostatic discharge protection element is realized by a protection diode. 4. The protection circuit includes a plurality of protection diodes between any positive power supply and each other positive power supply, or between any negative power supply or each ground and each other negative power supply or each ground. The semiconductor device according to claim 1, wherein the semiconductor device is a circuit configured to be connected in series.