TWI413229B - Electrostatic discharge structure - Google Patents

Abstract

An electrostatic discharge structure including a substrate, a first diffusion region, a first doped region, a second doped region, a third doped region, a fourth doped region and a first isolation region. The substrate includes a first conductive type. The first diffusion region is formed in the substrate and comprises a second conductive type. The first and the second doped regions are formed in the first diffusion region. The first doped region includes the first conductive type. The second doped region includes the second conductive type. The third doped region, the fourth doped region and the first isolation region are formed in the substrate. The third doped region includes the second conductive type. The fourth doped region includes the first conductive type. During releasing an ESD current, the second doped region does not connect to a first power line.

Description

Electrostatic discharge protection structure

The present invention relates to a protective structure, and more particularly to an electrostatic discharge (ESD) protective structure.

Component damage due to electrostatic discharge has become one of the most important reliability issues for integrated circuit products. In particular, as the size is continuously reduced to a depth of a micron, the gate oxide layer of the MOS semiconductor is also thinner and thinner, and the integrated circuit is more susceptible to damage due to the electrostatic discharge phenomenon.

In the general industry standard, the input/output pins (I/O pins) of integrated circuit products must pass the human body mode electrostatic discharge test of 2000 volts or more and the mechanical mode electrostatic discharge test of 200 volts or more. Therefore, in the integrated circuit product, the ESD protection component must be placed near all the input and output pads to protect the internal core circuit from the electrostatic discharge current.

The present invention provides an electrostatic discharge protection structure including a substrate, a first diffusion region, a first doped region, a second doped region, a third doped region, a first isolation region, and a fourth doped region. Miscellaneous area. The substrate has a first conductivity type. The first diffusion region is formed in the substrate and has a second conductivity type. The first doped region is formed in the first diffusion region and has a first conductivity type. The second doped region is formed in the first diffusion region and has a second conductivity type. The third doped region is formed in the substrate and has a second conductivity type. The first isolation region is formed in the substrate, covers a portion of the first diffusion region, and is located between the second and third doped regions. The fourth doped region is formed in the substrate and has a first conductivity type. When the first doping region is coupled to a first power line, and the third and fourth operating regions are coupled to a second power line, an electrostatic discharge current from the first power line can be released to the second power cable. When the electrostatic discharge current is released, the second doped region is not electrically connected to the first power line.

In order to make the features and advantages of the present invention more comprehensible, the preferred embodiments are described below, and are described in detail with reference to the accompanying drawings.

Fig. 1A is a possible embodiment of the electrostatic discharge protection structure of the present invention. As shown, the ESD protection structure 100 includes a substrate 101, a diffusion region 111, doped regions 121-124, and an isolation region 131. The substrate 101 has a first conductivity type. The diffusion region 111 is formed in the substrate 101 and has a second conductivity type. In this embodiment, the first conductivity type is a P type, and the second conductivity type is an N type. In other embodiments, the first conductivity type is N-type and the second conductivity type is P-type.

Doped regions 121 and 122 are both formed in the diffusion region 111. In this embodiment, the doped region 121 has a first conductivity type and the doped region 122 has a second conductivity type. Figure 1B is a top plan view of doped regions 121 and 122. The doped region 122 surrounds the doped region 121 in an annular manner.

In FIG. 1A, doped regions 123 and 124 are both formed in the substrate 101. In the present embodiment, the doped region 123 has a second conductivity type, and the doped region 124 has a first conductivity type.

The isolation region 131 is formed in the substrate 101, covers a portion of the diffusion region 111, and is located between the doping regions 122 and 123. The isolation region 131 may be a shallow trench isolation or a field oxide. In this embodiment, the electrostatic discharge protection structure 100 further includes isolation regions 132-134. The isolation region 132 is disposed between the doping regions 123 and 124. The isolation region 133 is disposed on the left side of the doping region 124. The isolation region 134 is disposed on the right side of the doping region 122.

In the present embodiment, the doping region 121 is coupled to the power supply line VDD, and the dummy regions 123 and 124 are coupled to the power supply line VSS. When an electrostatic discharge event occurs in the power line VDD and the power line VSS is grounded, an electrostatic discharge current from the power line VDD can be discharged to the ground through the doping region 121, the diffusion region 111, the substrate 101, and the doping regions 123 and 124. . When the electrostatic discharge current is released, the doping region 122 is not electrically connected to the power supply line VDD.

Since the doping region 122 is disposed between the doping region 121 and the isolation region 131, the traveling path of the electrostatic discharge current can be changed to prevent the electrostatic discharge current from directly colliding with the isolation region 131. In addition, by controlling the width D of the doping region 122, the holding voltage of the electrostatic discharge protection structure 100 can be adjusted. In a possible embodiment, the width D is between about 0.5 μ and 5 μ.

In the present embodiment, the doping region 122 on the left side of the doping region 121 (hereinafter referred to as the left doping region 122) simultaneously contacts the isolation region 131 and the doping region 121. In other embodiments, the left doped region 122 has a gap between at least one of the isolation region 131 and the doped region 121.

Figure 2 is another possible embodiment of the electrostatic discharge protection structure of the present invention. Figure 2 is similar to Figure 1A, with the difference that Figure 2 has more well 212 and gate 241. The substrate 201, the diffusion region 211, the doping regions 221 to 224, and the isolation regions 231 to 234 of FIG. 2 are similar to the substrate 101, the diffusion region 111, the doping regions 121 to 124, and the isolation regions 131 to 134 of FIG. Therefore, no further explanation is given.

As shown, the well region 212 is formed in the substrate 201 and has a second conductivity type. The well region 212 includes a partial diffusion region 211 and a partially doped region 222. Doped region 221 is formed in well region 212. In the present embodiment, well region 212, diffusion region 211, and doped region 222 have the same conductivity type. In a possible embodiment, the doped region 222 has a heavy concentration of N dopant (N+), the diffusion region 211 is an N-type drain drift (NDD), and the well region 212 is An N-type well area (NW).

The gate 241 is formed over the substrate 201 between the isolation region 231 and the doping region 223 and covers a portion of the isolation region 231. The gate 241 and the doped regions 221, 223, and 224 constitute a double diffused drain double MOSFET (DDMOSFET). In this embodiment, the doping region 221 is a drain of the DDMOSFET, the doping region 223 is a source of the DDMOSFET, and the doping region 224 is a bulk of the DDMOSFET.

In addition, when the electrostatic discharge current is released, the gate 241 is coupled to the power line VSS, and the doped region 222 is not electrically connected to the power line VDD. In a possible embodiment, the doped region 222 is in a floating state.

In this embodiment, there is a gap between the doping region 222 and the isolation region 231. By controlling the width D of the doped region 222, the sustain voltage of the electrostatic discharge protection structure 200 can be controlled.

Fig. 3A is another possible embodiment of the electrostatic discharge protection structure of the present invention. Figure 3A is similar to Figure 1A, except that Figure 3A has more diffusion regions 312A-314A and doped regions 325A.

The diffusion region 312A is formed in the diffusion region 313A and has a first conductivity type. In the present embodiment, the doping regions 323A, 324A and the isolation regions 332A are both formed in the diffusion region 312A. In one possible embodiment, the impurity concentration of the diffusion region 312A is less than the impurity concentration of the doped region 324.

The diffusion region 313A is formed in the substrate 301A and has a second conductivity type. In the present embodiment, the diffusion regions 311A and 312A are formed in the diffusion region 313A. In one possible embodiment, the diffusion region 311A is an N-type drain drift region (NDD) and the diffusion region 313A is a high voltage N-well region (HVNW).

The diffusion region 314A is formed in the substrate 301A and has a first conductivity type, and the doping region 325A is formed in the diffusion region 314A and has a first conductivity type as a metal contact of the diffusion region 314A. In one possible embodiment, the doped region 325A is a high pressure P-type well region (HVPW).

In the present embodiment, the doping regions 323A, 324A, and 325A are coupled to the power supply line VSS, and the doping region 321A is coupled to the power supply line VDD. Doped region 322A is not coupled to power supply line VDD. By doping the region 322A, it is possible to prevent the electrostatic discharge current from the power supply line VDD from directly colliding with the isolation region 331A, thereby increasing the sustain voltage of the electrostatic discharge protection structure 300A.

Figure 3B is another possible embodiment of the electrostatic discharge protection structure of the present invention. Fig. 3B is similar to Fig. 3A except that the gate 341B is added to Fig. 3B. The gate 341B is formed over the diffusion regions 311B and 312B and covers the partially doped region 323B and the isolation region 331B.

In this embodiment, there is a gap between the isolation region 331B and the doping region 323B. In addition, the gate 341B and the doped regions 321B, 323B, and 324B constitute a laterally diffused metal oxide semiconductor (LDMOS) transistor. When the electrostatic discharge current is released, the gate 341B is coupled to the power line VSS, and the doped region 322B is not coupled to the power line VDD.

In this embodiment, the diffusion regions 311B and 312B have a second conductivity type and a first conductivity type, respectively. In one possible embodiment, the diffusion region 311B is HVNW and the diffusion region 312B is HVPW.

Figure 4 is another possible embodiment of the electrostatic discharge protection structure of the present invention. Figure 4 is similar to Figure 3B, except that Figure 4 has a buried layer 451. In the present embodiment, a buried layer 451 is formed in the substrate 401 and has a second conductivity type. Diffusion regions 411, 412, and 415 are formed over buried layer 451.

In a possible embodiment, the buried layer 451 is an N-type buried layer. In the present embodiment, the diffusion regions 411 and 415 are a high pressure N-type well region (HVNW), and the diffusion region 412 is a high pressure P-type well region (HVPW).

In the present embodiment, the doping region 421 is coupled to the power line VDD, and the doping regions 423, 424 and the gate 441 are coupled to the power line VSS. Since the doping region 422 is provided between the doping region 421 and the isolation region 431, the electrostatic discharge current from the power supply line VDD can be prevented from directly colliding with the isolation region 431, and the sustain voltage of the electrostatic discharge protection structure 400 can be improved.

Unless otherwise defined, all terms (including technical and scientific terms) are used in the ordinary meaning Moreover, unless expressly stated, the definition of a vocabulary in a general dictionary should be interpreted as consistent with the meaning of an article in its related art, and should not be interpreted as an ideal state or an overly formal voice.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

100, 200, 300A, 300B, 400. . . Electrostatic discharge protection structure

101, 201, 301A, 301B, 401. . . Base

111, 211, 311A~314A, 311B, 312B, 411, 412, 415. . . Diffusion zone

121~124, 221~224, 321A~325A, 321B~324B, 421~424. . . Doped region

131~134, 231~234, 331A~335A, 331B~334B, 431~434. . . quarantine area

212. . . Well area

241, 341B, 441. . . Gate

451. . . Buried layer

Fig. 1A is a possible embodiment of the electrostatic discharge protection structure of the present invention.

Fig. 1B is a partial plan view showing the electrostatic discharge protection structure of the present invention.

2, 3A, 3B and 4 are other possible embodiments of the electrostatic discharge protection structure of the present invention.

100. . . Electrostatic discharge protection structure

101. . . Base

111. . . Diffusion zone

121~124. . . Doped region

131~134. . . quarantine area

Claims (9)

An electrostatic discharge protection structure comprising: a substrate having a first conductivity type; a first diffusion region formed in the substrate and having a second conductivity type; a first doped region formed in Between the first diffusion region and having the first conductivity type; a second doped region formed in the first diffusion region, having the second conductivity type, wherein the second doping region surrounds The first doped region is in direct contact with the first doped region; a third doped region is formed in the substrate and has the second conductive type; a first isolation region is formed on the substrate Covering a portion of the first diffusion region between the second and third doped regions; and a fourth doped region formed in the substrate and having the first conductivity type; When the first doped region is coupled to a first power line, and the third and fourth operating regions are coupled to a second power line, an electrostatic discharge current from the first power line can be released. To the second power line; wherein the second doped region is not electrically discharged when the electrostatic discharge current is released Connected to the first power line. The electrostatic discharge protection structure of claim 1, further comprising: a well region formed in the substrate and having the second conductivity type, the well region including a portion of the first diffusion region and a portion The second doping region, the first a doped region is formed in the well region; and a gate is formed over the substrate between the first isolation region and the third doped region and covers a portion of the first isolation region, the gate The pole and the first, third and fourth doping regions form a double-diffused diode double-diffused Drain MOSFET, and the gate is coupled to the second power source when the electrostatic discharge current is released line. The electrostatic discharge protection structure of claim 1, further comprising: a second diffusion region formed in the substrate, having the first conductivity type, wherein the third and fourth doped regions are formed Among the second diffusion regions, a third diffusion region is formed in the substrate and has the second conductivity type, and the first and second diffusion regions are formed in the third diffusion region. The electrostatic discharge protection structure according to claim 3, wherein the first diffusion region is an N-type drain drift, and the third diffusion region is a high-pressure N-type. Well area (HVNW). The electrostatic discharge protection structure of claim 1, further comprising: a second diffusion region formed in the substrate, having the first conductivity type, wherein the third and fourth doped regions are formed a second diffusion region; and a gate formed over the first and second diffusion regions and covering portions of the first and second diffusion regions, the gate, the first, third, and The four doped regions form a laterally diffused metal oxide semiconductor (LDMOS) transistor, and the gate is coupled to the second power line when the electrostatic discharge current is released. The electrostatic discharge protection structure of claim 1, further comprising: a second diffusion region formed in the substrate, having the first conductivity type, wherein the third and fourth doped regions are formed And a buried layer formed in the substrate and having the second conductivity type, the first and second diffusion regions being formed on the buried layer. The electrostatic discharge protection structure according to claim 6, wherein the first diffusion zone is a high pressure N-type well zone (HVNW), and the second diffusion zone is a high pressure P-type well zone (HVPW). The electrostatic discharge protection structure of claim 1, wherein the second doped region contacts at least one of the first doped region and the first isolated region. The electrostatic discharge protection structure of claim 1, wherein the second doped region and the first isolation region have a gap therebetween.