CN100474589C

CN100474589C - Semiconductor anti-static protection structure

Info

Publication number: CN100474589C
Application number: CNB200610118439XA
Authority: CN
Inventors: 苏庆
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2006-11-17
Filing date: 2006-11-17
Publication date: 2009-04-01
Anticipated expiration: 2026-11-17
Also published as: CN101188237A

Abstract

The invention discloses an Anti-static protection structure for a semiconductor, and the structure comprises a P type substrate. The P type substrate comprises an N well injection region and a P well injection region, which comprise respectively a P type injection region and an N type injection region. The P type injection region and the N type injection region are separated by a separation region of oxide layer. The P type injection region in the N well injection region and the N type injection well in the P well injection region are separated by another separation region of oxide layer. A polysilicon is arranged on the separation region of oxide layer between the P type injection region in N well injection region and the N type injection region in the P well injection region. The invention effectively decreases the threshold voltage of the thyristor. On one hand, the process condition is not increased; on the other hand, the parasitic NPN pipe and the PNP pipe which are used for ESD discharge become easier to be opened. The invention gives full play to ESD capability.

Description

Semiconductor anti-static protection structure

Technical field

The present invention relates to a kind of semiconductor device structure, especially a kind of semiconductor anti-static protection structure.

Background technology

Current popular technology uses SCR (SCR structure) as ESD (static discharge) protection device, as shown in Figure 1, comprises P type substrate 1, includes N trap injection region 2 and P trap injection region 11 on described P type substrate 1; In described N trap injection region 2, include a P type injection region 3 and a N type injection region 4, separated by an oxide layer isolated area 5 between P type injection region 3 in the described N trap injection region 2 and the N type injection region 4; Also include a P type injection region 6 and a N type injection region 7 in described P trap injection region 11, separated by another oxide layer 8 isolated areas between the P type injection region 6 of described P trap injection region 11 and the N type injection region 7; P type injection region 3 in the described N trap injection region 2 is separated by another oxide layer isolated area 9 with the N type injection region 7 of described P trap injection region 11.ESD electric charge injection end is connected with N type injection region with the P type injection region of described N trap injection region.P type injection region in the P trap injection region, the N trap injection region in the P trap injection region, P-N-P-N four-level semiconductor structure has been formed in the N type injection region in P type injection region in the N trap injection region and the N trap injection region.This also is the structure that causes metal oxide layer transistor latch-up problem.On the protective capacities of ESD, this structure can provide the highest ESD protective capacities under the layout area of minimum.Its cut-in voltage is equivalent to the junction breakdown voltage of N trap injection region and P trap injection region.Because the N trap injects and to have lower doping content, so its puncture voltage has so high puncture voltage up to 30-50V, makes its internal circuit that will protect just to be broken by the ESD electrostatic charge early than its unlatching.

The equivalent electric circuit of this electrostatic-proof protection device can be referring to Fig. 2; include a PNP pipe and a NPN pipe; the emitter of described PNP pipe is received the base stage of this PNP pipe by a resistance; the collector electrode of described PNP pipe is connected to the base stage of described NPN pipe; the base stage of described PNP pipe is also connected to the collector electrode of described NPN pipe; the emitter of described NPN pipe is connected to the base stage of this NPN pipe by another resistance, the grounded emitter of described NPN pipe, and the emitter of described PNP pipe is as the Anode anode.When ESD took place, the electrostatic charge of releasing can cause two parasitic triodes of protection device, i.e. pipe of PNP among Fig. 2 and the conducting of NPN pipe, and as shown in Figure 3, device can produce the phenomenon of Snapback (step recovery).But because the unlatching of these two parasitic triodes needs the reverse PN junction of N trap to puncture, its puncture voltage has so high puncture voltage up to 30-50V, makes its internal circuit that will protect just to be broken by the ESD electrostatic charge early than its unlatching.

Summary of the invention

Technical problem to be solved by this invention provides a kind of semiconductor anti-static protection structure, can when static discharge take place, and parasitic NPN pipe and PNP pipe can in time be opened, and fully device are protected.

For solving the problems of the technologies described above, the technical scheme of semiconductor anti-static protection structure of the present invention is, comprises P type substrate, includes N trap injection region and P trap injection region on described P type substrate; In described N trap injection region, include a P type injection region and a N type injection region, separated by an oxide layer isolated area between P type injection region in the described N trap injection region and the N type injection region; Also include a P type injection region and a N type injection region in described P trap injection region, separated by another oxide layer isolated area between the P type injection region of described P trap injection region and the N type injection region; The N type injection region of P type injection region in the described N trap injection region and described P trap injection region is separated by another oxide layer isolated area, is provided with a polysilicon above the oxide layer isolated area between the N type injection region of P type injection region in described N trap injection region and described P trap injection region.

The present invention isolates the triggering structure of forming by increased polysilicon and oxide layer on the basis of traditional SCR structure, has effectively reduced the silicon controlled cut-in voltage, and has not influenced its protective capability.Both guarantee not increase new process conditions, and made the parasitic NPN pipe and the PNP that are used for esd discharge manage easier unlatching again, can give full play to its ESD ability.

Description of drawings

The present invention is further detailed explanation below in conjunction with drawings and Examples:

Fig. 1 is the structural representation of conventional semiconductor electrostatic-proof protection device;

Fig. 2 is the equivalent circuit diagram of conventional semiconductor anti-electrostatic protecting structure;

Fig. 3 recovers the electric current-voltage curve of phenomenon for producing step;

Fig. 4 is the structural representation of semiconductor anti-static protection structure of the present invention;

Fig. 5 is the equivalent circuit diagram of semiconductor anti-static protection structure of the present invention.

Reference numeral is among the figure, 1.P type substrate; 2.N trap injection region; 3.P type injection region; 4.N type injection region; 5. oxide layer isolated area; 6.P type injection region; 7.N type injection region; 8. oxide layer isolated area; 9. oxide layer isolated area; 10. polysilicon; 11.P trap injection region; 12. earth terminal; 13.ESD electric charge injection end; 14. electric capacity; 15. resistance.

Embodiment

Semiconductor anti-static protection structure of the present invention can comprise P type substrate 1 referring to shown in Figure 4, includes N trap injection region 2 and P trap injection region 11 on described P type substrate 1; In described N trap injection region 2, include a P type injection region 3 and a N type injection region 4, separated by an oxide layer isolated area 5 between P type injection region 3 in the described N trap injection region 2 and the N type injection region 4; Also include a P type injection region 6 and a N type injection region 7 in described P trap injection region 11, separated by another oxide layer 8 isolated areas between the P type injection region 6 of described P trap injection region 11 and the N type injection region 7; P type injection region 3 in the described N trap injection region 2 is separated by another oxide layer isolated area 9 with the N type injection region 7 of described P trap injection region 11, is provided with a polysilicon 10 above the oxide layer isolated area 9 between the N type injection region 7 of P type injection region 3 in described N trap injection region 2 and described P trap injection region 11.

Described polysilicon is connected with circuits for triggering.Described circuits for triggering comprise a resistance 15 and an electric capacity 14, one end of described resistance 15 is connected with described polysilicon 10, one end of described electric capacity 14 also is connected with described polysilicon 10, the other end of described resistance 15 connects earth terminal 12, and the other end of described electric capacity 14 is connected to ESD electric charge injection end 13.

The equivalent electric circuit of semiconductor anti-static protection structure of the present invention as shown in Figure 5; include a PNP pipe and a NPN pipe; the emitter of described PNP pipe is received the base stage of this PNP pipe by a resistance; the collector electrode of described PNP pipe is connected to the base stage of described NPN pipe; the base stage of described PNP pipe is also connected to the collector electrode of described NPN pipe; the emitter of described NPN pipe is connected to the base stage of this NPN pipe by another resistance; the grounded emitter of described NPN pipe, the emitter of described PNP pipe is as ESD electric charge injection end.One end of electric capacity 14 is connected to ESD electric charge injection end, and the other end connects and is connected with an end of resistance 15, the other end ground connection of resistance 15, and the end that electric capacity 14 is connected with resistance 15 produces triggering signal, control NPN pipe.

Add polysilicon on this silicon controlled rectifier and trigger structure, when ESD takes place, having a positive voltage is added on the polysilicon 10, below polysilicon 10 and oxide layer isolated area 9, P type area between N type injection region 7 and N trap injection region, have the induction electron production, the ion that these inductions generate has been expanded the depletion layer area of N trap injection region 2, reduce distance with N type injection region 7, at this moment since the ESD accumulation in N trap injection region 2, improved the voltage of N trap injection region 2, punchthrough effect (punch through) has just taken place further to horizontal expansion in the depletion region that causes N trap injection region 2 when contacting with N type injection region 7, electric current sharply rises, cause parasitic NPN pipe and the conducting of PNP pipe to enter the electric current amplification region, bleed off the ESD electric charge.And under non-ESD generation state, polysilicon is by big resistance 15 ground connection, and N trap injection region 2 punchthrough effect can not take place with N type injection region 7.

Claims

1. a semiconductor anti-static protection structure comprises P type substrate, includes N trap injection region and P trap injection region on described P type substrate; In described N trap injection region, include a P type injection region and a N type injection region, separated by an oxide layer isolated area between P type injection region in the described N trap injection region and the N type injection region; Also include a P type injection region and a N type injection region in described P trap injection region, separated by another oxide layer isolated area between the P type injection region of described P trap injection region and the N type injection region; The N type injection region of P type injection region in the described N trap injection region and described P trap injection region is separated by another oxide layer isolated area, it is characterized in that, be provided with a polysilicon above the oxide layer isolated area between the N type injection region of P type injection region in described N trap injection region and described P trap injection region.

2. semiconductor anti-static protection structure according to claim 1 is characterized in that, described polysilicon is connected with circuits for triggering.

3. semiconductor anti-static protection structure according to claim 2; it is characterized in that; described circuits for triggering comprise a resistance and an electric capacity; one end of described resistance is connected with described polysilicon; one end of described electric capacity also is connected with described polysilicon; the other end ground connection of described resistance, the other end of described electric capacity are connected to the electric charge injection end of static discharge.