CN101202281A

CN101202281A - SCR electrostatic protection device and method of manufacture

Info

Publication number: CN101202281A
Application number: CNA2006101194461A
Authority: CN
Inventors: 徐向明
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2006-12-12
Filing date: 2006-12-12
Publication date: 2008-06-18

Abstract

The invention discloses an SCR electrostatic protection device and the manufacturing method thereof. The structure of the device comprises a P-type injection region (2) in a P well (4), an N-type injection region (1) in the P well (4), a P-type injection region (2) in an N well (3) and an N-type injection well (1) in the N well (3), and the P well is added with the P-type injection region (2), and a capacitance is arranged between the input terminal and the added P-type injection region. by adding the P-type injection region and the capacitance in the P well of the traditional SCR structure, the invention can reduce the turn-on voltage of the silicon controlled rectifier effectively without affecting protection ability, and the SCR structure is earlier and easier to be triggered, thus achieving better electrostatic protection effect.

Description

A kind of SCR electrostatic protection device and manufacture method

Technical field

The present invention relates to a kind of semiconductor electrostatic resist technology, relate in particular to a kind of SCR (SiliconControlled Rectifier, silicon controlled rectifier) electrostatic protection device and manufacture method.

Background technology

Be extensive use of SCR as static discharge (ESD, Electrostatic Discharge) protection device in the semiconductor electrostatic protection at present.As shown in Figure 1, be the structural representation of the SCR that uses always, formed P-N-P-N four-level semiconductor structure by the P type injection region in the P trap, the N type injection region in the P trap, the P type injection region in the N trap, the N type injection region in the N trap.Fig. 3 is the equivalent electric circuit of above-mentioned SCR commonly used, as shown in Figure 3, can form the coupling of parasitic NPN and parasitic PNP triode, can form triggering as shown in Figure 4 when static arrives the arrival certain voltage, thereby form discharge prevention.On the protective capacities of ESD, this structure can provide higher ESD protective capacities under less layout area, and its cut-in voltage is equivalent to the junction breakdown voltage of N trap injection region and P type substrate zone.Because the N trap injects and to have lower doping content, so its puncture voltage can have high puncture voltage like this up to 30-50V (decide according to concrete technology), makes its internal circuit that will protect just to be broken by the ESD electrostatic charge early than its unlatching.Therefore the cut-in voltage that how suitably to reduce the SCR electrostatic protection device becomes a problem.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of SCR electrostatic protection device and manufacture method, can solve the too high and problem that causes protective capability not to be not fully exerted of SCR cut-in voltage.

For solving the problems of the technologies described above; the present invention proposes a kind of SCR electrostatic preventing structure; also form by the P type injection region in the P trap, the N type injection region in the P trap, the P type injection region in the N trap, the N type injection region in the N trap; but in above-mentioned P trap, add a P type injection region, between the P of input and increase type injection region, add an electric capacity simultaneously.Above-mentioned capacitance is less than 150 pico farads.Above-mentioned SCR electrostatic protection device can be applicable in the semiconductor electrostatic protective circuit that trigger voltage is 5V-40V.For making above-mentioned electrostatic protection device, only need utilize common process, promptly in described P trap, add a P type injection region, between the described P type injection region of input and increase, insert an electric capacity simultaneously.

The present invention is because after having increased a P type injection region and electric capacity in the P trap of traditional SCR structure; can effectively reduce the silicon controlled cut-in voltage; and do not influence its protective capability, make the easier triggering more early of SCR structure, thereby can access better electrostatic protection effect.

Description of drawings

Fig. 1 is the structural representation of the SCR that uses always;

Fig. 2 is the structural representation of a specific embodiment of the present invention;

Fig. 3 is the equivalent circuit diagram of SCR commonly used shown in Figure 1;

Fig. 4 is the triggering schematic diagram when using the SCR electrostatic protection always, and V is a voltage, and I is an electric current;

Fig. 5 is the equivalent circuit diagram of specific embodiment shown in Figure 2;

Reference numeral: 1 is N type injection region, and 2 is P type injection region, and 3 is N trap injection region, and 4 is P trap injection region, and 5 is P type substrate.

Embodiment

The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

At first sketch principle of the present invention:

As previously mentioned, Fig. 1 is the structural representation of the SCR that uses always, and its equivalent electric circuit such as Fig. 3 show, can form the coupling of parasitic NPN and parasitic PNP triode, and arriving as static to form as shown in Figure 4 triggering when arriving certain voltage, thereby forms discharge prevention.Because the opening point of NPN triode is to be determined by the base stage of the NPN PN junction forward conduction with emitter; the present invention consider shown in Figure 1 in the P trap, add a P type injection region and electric capacity after; form the RC coupling of electric capacity and R1 resistance (shown in Figure 3); the base stage of a triggering signal to NPN can be provided in the process that static is come in; make the easier triggering more early of SCR structure, thereby can access better electrostatic protection effect.

The present invention considers to add a P type active area shown in Figure 1 in PWell; add a capacitor C (as Fig. 2) at input and the design of this active area simultaneously; the RC coupling that after adding capacitor C 1, can form C1 electric capacity and R1 resistance shown in Figure 3; thereby can make the easier triggering of SCR structure, thereby can access better electrostatic protection effect.

Embodiment:

As shown in Figure 2, be the structural representation of a specific embodiment of the present invention, wherein: 1 is N type injection region, and 2 is P type injection region, and 3 is N trap injection region, and 4 is P trap injection region, 5 is P type substrate.SCR has still comprised P-N-P-N four-level semiconductor structure in the present embodiment, but consider above-mentioned inventive principle, present embodiment adds a P type injection region and capacitor C 1 (100 pico farad) in P trap (PWell) shown in Figure 1 after, as shown in Figure 5, C1 electric capacity and R1 resistance can form the RC coupling, the base stage of a triggering signal to NPN can be provided in the process that static is come in, make the easier triggering more early of SCR structure, that is: triggering signal adopts electric capacity to add the method that resistance is formed the RC circuit, when input has the ESD electric charge to enter, P type injection region has electric charge induction, current potential improves, can cause the base stage of NPN triode and the PN forward diode conducting of emitter, open NPN bleed off ESD electric charge in advance; And under non-ESD generation state, P type injection region is by resistance R ground connection, can not open NPN.

In addition, according to experimental data, capacitance should be less than 150 pico farads in the foregoing circuit.SCR electrostatic protection device of the present invention, can be applicable to trigger voltage is in the semiconductor electrostatic protective circuit of 5V-40V.

Must emphasize,, only need utilize common process, promptly in described P trap, add a P type injection region, between the described P type injection region of input and increase, insert an electric capacity simultaneously for making above-mentioned electrostatic protection device.

Compare with traditional SCR electrostatic protection device, the SCR electrostatic protection device of present embodiment can obtain better electrostatic protection effect.The present invention need not to increase new process conditions, can be applied to protect internal circuit to avoid the static injury.

In sum; the present invention is increasing P type injection region in P trap injection region on the basis of traditional SCR structure, make parasitic NPN and the easier unlatching of PNP be used for esd discharge, can effectively reduce the cut-in voltage of SCR; and do not influence its protective capability, give full play to the ESD ability of device.

Claims

1. SCR electrostatic protection device; form by the P type injection region in the P trap, the N type injection region in the P trap, the P type injection region in the N trap, the N type injection region in the N trap; it is characterized in that; in described P trap, add a P type injection region, between the described P type injection region of input and increase, add an electric capacity simultaneously.

2. SCR electrostatic protection device according to claim 1 is characterized in that described capacitance is less than 150 pico farads.

3. SCR electrostatic protection device according to claim 2 is characterized in that, can be applicable to trigger voltage is in the semiconductor electrostatic protective circuit of 5V-40V.

4. a method of making claim 1 or 2 described electrostatic protection devices is characterized in that, utilizes common process to add a P type injection region in described P trap, inserts an electric capacity simultaneously between the described P type injection region of input and increase.