Parts of an apparatus of silicon controlled rectifier can obtain taller ESD to defend with lesser domain area grade, accordingly, this kind of parts of an apparatus already was in integrated circuit piece on electrostatic position is occupied in defending. But be in deep inferior the drawback that parts of an apparatus of the SCR in micron CMOS craft still has tall open voltage, touch hair voltage 20V of general prep above, and the voltage of puncture of bar oxidation layer of class of prep above input. As the ceaseless progress of craft level, the ply of bar oxidation layer is reduced ceaselessly, puncture voltage is reduced further, accordingly, avoid parts of an apparatus of layer of oxidation of kernel circuit thin bar the necessary step of permanent damage is to reduce voltage of open of SCR parts of an apparatus to raise open rate. If the graph is shown 1 times,be profile of parts of an apparatus of simple and transverse SCR, reduce the structure of parts of an apparatus that touchs hair voltage to have MLSCR and LVTSCR in the light of this structure; The common method that raises open rate in the light of this structure is to use auxiliary spark circuit, for example, grid coupling technology, heat carries stream child spark technology, underlay sparks technology, double spark the technology. Article introduction reduces the method that touchs hair voltage to raise open rate a few kinds.

 

Graph profile of parts of an apparatus of 1 simple and transverse SCR

 

1, improve model SCR (Modified Lateral SCR, MLSCR)

 

If the graph is shown 2 times, MLSCR is passed in N trap / N+ increases to diffuse on the knot face of P trap the avalanche puncture voltage that the area will come to reduce this tie. Through this the law can reduce open tension 12V, but the layer of thin bar oxidation that still can’t protect input class, accordingly, same need of MLSCR and LSCR and parts of an apparatus of 2 class protection cooperate to realize the electrostatic protection that inputs class. Of course, as a result of its open voltage reduce, 2 class protect the domain area of parts of an apparatus to be able to be reduced. And to outputting class, the circuit that as a result of two class ESD protection can give regular job to fall brings signal delay time, LSCR and MLSCR are general need not the electrostatic protection at outputting class.

 

Profile of parts of an apparatus of graph 2 MLSCR

 

2, low touch hair voltage SCR (Low-Voltage Triggering SCR, LVTSCR)

 

If the graph is shown 3 times, LVTSCR embeds through be in the structure open voltage reduces parts of an apparatus of a NMOS general to make an appointment with 7V, with the leakage puncture voltage of short channel NMOS or break-through voltage close. This parts of an apparatus can use the input class ESD that regards CMOS as integrated circuit to protect independently, the domain that reduced ESD to protect circuit greatly realizes an area. And when as output class is protected, need joins the effectiveness that little series connection resistance protects with assuring ESD between LVTSCR and output level.

 

Graph profile of 3 LVTSCR parts of an apparatus

 

3, the LVTSCR of grid coupling (Gate-Coupled LVTSCR)

 

If the graph is shown 4 times,be complementary model grid coupling LVTSCR, this parts of an apparatus uses mechanism of blame avalanche puncture to come open. Through reasonable setting the capacitance of Cn and Cp is worth, can make coupling is in to the voltage on bar circuit is less than below regular job status inside the threshold value voltage that embeds NMOS/PMOS, and be more than when ESD stress comes inside the threshold value voltage that embeds NMOS/PMOS. The open voltage of LVTSCR can be passed adjust inside the coupling voltage that embeds NMOS/PMOS grid will install. Coupling voltage is bigger, the open voltage of LVTSCR is lower, the LVTSCR of fast open can protect an input effectively / output level.

 

Graph the structure of LVTSCR parts of an apparatus of 4 grid coupling

 

4, underlay sparks SCR (Substrate-Triggered SCR, STSCR)

 

If the graph is shown 5 times,be P model spark with N underlay SCR parts of an apparatus, they part to diffuse through P+ or N+ are being joined in traditional LSCR parts of an apparatus the area serves as spark node. Underlay sparks the open mechanism of SCR parts of an apparatus belongs to electric current to spark incident. Be added in the underlay of SCR parts of an apparatus when electric current, also namely when the base of parasitism dynatron, SCR can spark quickly and enter latch state. Touch those who send electric current to increase as underlay, open voltage drops, open time shortens. Of course, the application of this parts of an apparatus needs adscititious RC to diagnose circuit.

 

Graph the structure of SCR parts of an apparatus that 5 underlay spark