CN104183653B - junction barrier Schottky diode - Google Patents

Abstract

A junction barrier Schottky diode comprises: a silicon substrate having an upper surface, an N-type buried layer below, an N-type well between the upper surface and the N-type buried layer; a first P-type doped region arranged in the N-type well and extending downward from the upper surface; a metal layer covering the upper surface and located above one side of the first P-type doped region; a second P-type doped region arranged in the N-type well, extending downward from the upper surface and located on the other side of the first P-type doped region; and a first N-type doped region arranged in the N-type well, extending downward from the upper surface and located on the other side of the first P-type doped region.

Description

Junction barrier Schottky diode

【Technical field】

The present invention relates to a Junction Barrier Schottky Diode (JBS Diode), in particular to a Junction Barrier Schottky Diode with better electrostatic discharge (Electrostatic Discharge) effect.

【Background technique】

FIG. 1 is a cross-sectional structure diagram of a conventional junction barrier Schottky diode 100 . The junction barrier Schottky diode 100 includes a silicon substrate 110 , a field oxide layer (field oxide) 120 , a field oxide layer 130 , a plurality of P-type doped regions 140 , a metal layer 150 , and an N-type doped region 160 .

The silicon substrate 110 has an upper surface 111 . The silicon substrate 110 has an N-type buried layer 112 (N buried layer, NBL) below the upper surface 111 . An N-type well 113 (Nwell) is formed between the upper surface 111 of the silicon substrate 110 and the N-type buried layer 112 . The field oxide layer 120 and the field oxide layer 130 are respectively disposed in the N-type well 113 and extend downward from the upper surface 111 . A plurality of P-type doped regions 140 are located on one side of the field oxide layer 120, and the plurality of P-type doped regions 140 are respectively arranged in the N-type well 113, and each P-type doped region 140 extends from the upper surface 111 to the Extend down.

The metal layer 150 covers the upper surface 111 and is located above the plurality of P-type doped regions 140 . The metal layer 150 is also electrically extracted to form the anode contact 170 of the junction barrier Schottky diode 100 . The N-type doped region 160 is located between the field oxide layer 120 and the field oxide layer 130 and extends downward from the upper surface 111 . The N-type doped region 160 is mainly used to draw out the current in the N-type well 113 and form the cathode contact 180 of the junction barrier Schottky diode 100 .

In FIG. 1 , the Schottky diode assembly 101 represented by a dotted line is an equivalent schematic representation of the junction barrier Schottky diode 100 . Moreover, the extraction of the metal layer 150 forms the positive contact 170, and the extraction of the N-type doped region 160 forms the negative contact 180. The junction between the metal layer 150 and the N-type well 113 directly determines the main characteristics, and the main current The path then takes place in the N-type well 113 . In addition, a parasitic diode element 102 is formed between the P-type doped region 140 and the N-type well 113 , as shown by the dotted line in FIG. 1 . This parasitic diode assembly 102 is connected in parallel with the equivalent Schottky diode assembly 101, but since the forward conduction voltage of the Schottky diode assembly 101 is smaller than the forward conduction voltage of the diode assembly 102, it is used in normal forward conduction Above, the characteristics of the Schottky diode assembly 101 are still the main ones.

However, the commonly used junction barrier Schottky diode 100 is poor in electrostatic discharge capability, especially when static electricity occurs at both ends of the junction barrier Schottky diode 100 in the form of negative voltage. . A conventional solution is to connect a group of ESD components in parallel on the junction barrier Schottky diode 100 to enhance its ESD capability. However, the addition of ESD components will increase the size and cost of the device.

【Content of invention】

In order to solve the above problems, the present invention mainly provides a junction barrier Schottky diode, especially a junction barrier Schottky diode with better electrostatic discharge effect.

The invention provides a junction barrier Schottky diode, which includes a silicon substrate, a first P-type doped region, a metal layer, a second P-type doped region, and a first N-type doped region. The silicon substrate has an upper surface. The silicon substrate has an N-type buried layer below the upper surface. An N-type well is formed between the upper surface of the silicon substrate and the N-type buried layer and extends downward from the upper surface. The first P-type doped region is arranged in the N-type well and extends downward from the upper surface. The metal layer covers the upper surface and is located above one side of the first P-type doped region. The second P-type doped region is arranged in the N-type well, extends downward from the upper surface, and is located on the other side of the first P-type doped region. The first N-type doped region is arranged in the N-type well, extends downward from the upper surface, and is located on the other side of the first P-type doped region.

In one embodiment of the present invention, it further includes a plurality of third P-type doped regions, which are arranged in the N-type well, extend downward from the upper surface, and are located on one side of the first P-type doped region, and are located on the metal below the layer.

In one embodiment of the present invention, it further includes a plurality of first field oxide layers, which are arranged in the N-type well, extend downward from the upper surface, and are located on one side of the first P-type doped region, and are located on the side of the metal layer. below.

In one embodiment of the present invention, a second field oxide layer is further included, disposed in the N-type well, extending downward from the upper surface, and located between the first P-type doped region and the first N-type doped region .

In an embodiment of the present invention, the first N-type doped region is located between the second P-type doped region and the first P-type doped region.

In an embodiment of the present invention, the second P-type doped region is located between the first N-type doped region and the first P-type doped region.

In an embodiment of the present invention, the first N-type doped region is adjacent to the second P-type doped region.

In one embodiment of the present invention, it further includes a P-type lightly doped region, located below the second P-type doped region.

In one embodiment of the present invention, it further includes: a second N-type doped region, disposed in the N-type well, extending downward from the upper surface, and the second P-type doped region is located in the first N-type doped region and between the second N-type doped regions.

In an embodiment of the present invention, the first N-type doped region, the second P-type doped region, and the second N-type doped region are adjacent to each other.

In an embodiment of the present invention, it further includes: a third P-type doped region, disposed in the N-type well, extending downward from the upper surface, and the first N-type doped region is located in the second P-type doped region and between the third P-type doped regions.

In an embodiment of the present invention, the second P-type doped region, the first N-type doped region and the third P-type doped region are adjacent to each other.

The effect of the present invention is that the junction barrier Schottky diode disclosed in the present invention can utilize the parasitic PNP bipolar junction transistor component in its structure to encounter reverse static electricity when the junction barrier Schottky diode When it is impacted, its ability to conduct electrostatic charges is enhanced, so the reverse electrostatic discharge ability of the junction barrier Schottky diode is enhanced.

Regarding the characteristics, implementation and effects of this creation, the best embodiment is described in detail as follows in conjunction with the drawings.

【Description of drawings】

Figure 1: The cross-sectional structure diagram of a conventional junction barrier Schottky diode.

FIG. 2 is a cross-sectional structure diagram of the disclosed first embodiment of the junction barrier Schottky diode of the present invention.

FIG. 3 is a cross-sectional structure diagram of the disclosed second embodiment of the junction barrier Schottky diode of the present invention.

FIG. 4 is a cross-sectional structure diagram of the disclosed third embodiment of the junction barrier Schottky diode of the present invention.

FIG. 5 is a cross-sectional structure diagram of the disclosed fourth embodiment of the junction barrier Schottky diode of the present invention.

Fig. 6: The current-voltage relationship diagram and the reverse bias leakage current curve diagram of the junction barrier Schottky diode of the present invention and the conventional technology.

Description of main component symbols:

100, 200, 300, 400, 500 Junction barrier Schottky diode 140 P-type doped region

150, 250 metal layers

101, 201 Equivalent Schottky diode components 160 N-type doped region

170, 270 positive contacts

102 Parasitic Diode Assembly 180, 280 Negative Contact

110, 210 Silicon substrate 202 Parasitic PNP bipolar junction transistor

111, 211 Upper surface 220 Second field oxide layer

112, 212 N-type buried layer 230 Third field oxide layer

113, 213 N-type well 240 First P-type doped region

120, 130 Field oxide layer 245 Reverse bias leakage current suppression structure (third P-type doped region, first field oxide layer)

266 Second N-type doped region

260 The first N-type doped region 268 The third P-type doped region

262 Curves of the second P-type doped region 610, 620, 630, 640, 650, 660

264 P-type lightly doped region

【detailed description】

FIG. 2 is a cross-sectional structure diagram of the disclosed first embodiment of the junction barrier Schottky diode 200 of the present invention. The junction barrier Schottky diode 200 of the present invention is a component realized by semiconductor manufacturing process. The junction barrier Schottky diode 200 includes a silicon substrate 210 , a first P-type doped region 240 , a metal layer 250 , a second P-type doped region 262 , and a first N-type doped region 260 .

The silicon substrate 210 has an upper surface 211 . The silicon substrate 210 has an N-type buried layer 212 below the upper surface 211 . An N-type well 213 is formed between the upper surface 211 of the silicon substrate 210 and the N-type buried layer 212 . The N-type buried layer 212 is used to reduce the leakage current between the upper components, so that the components can be arranged more closely and the overall area can be reduced.

The first P-type doped region 240 is disposed in the N-type well 213 and extends downward from the upper surface 211 . The metal layer 250 covers the upper surface 211 and is located above one side of the first P-type doped region 240 . The junction between the metal layer 250 and the N-type well 213, that is, the metal-semiconductor (metal-semiconductor) junction that forms the junction barrier Schottky diode 200, directly determines the junction barrier Schottky diode 200. The main characteristic of the metal layer 250 is also electrically drawn out to form the anode contact 270 of the junction barrier Schottky diode 200 . The second P-type doped region 262 is disposed in the N-type well 213 , extends downward from the upper surface 211 , and is located on the other side of the first P-type doped region 240 . The first N-type doped region 260 is disposed in the N-type well 213 , extends downward from the upper surface 211 , and is located on the other side of the first P-type doped region 240 .

In the embodiment shown in FIG. 2, the first N-type doped region 260 is located between the second P-type doped region 262 and the first P-type doped region 240. The structure of the junction barrier Schottky diode 200 is not limited thereto.

In FIG. 2 , the Schottky diode component 201 indicated by a dotted line is an equivalent schematic component of the junction barrier Schottky diode 200 . Moreover, the extraction of the metal layer 250 forms the positive contact 270, and the extraction of the first N-type doped region 260 forms the negative contact 280. The junction between the metal layer 250 and the N-type well 213 directly determines the main characteristics, and The main current path occurs in the N-well 213 . In addition, the structure of the second P-type doped region 262, the N-type well 213, and the first P-type doped region 240 forms a parasitic PNP-type bipolar junction transistor (bipolar junction transistor, BJT) component 202, As shown by the dotted line in Figure 2. The potential of the N-type well 213 is determined by drawing out the first N-type doped region 260 . The emitter (emitter) and base (base) of this parasitic transistor assembly 202 are connected in parallel with the equivalent Schottky diode assembly 201, but because the forward conduction voltage of the Schottky diode assembly 201 is smaller than the emitter of the transistor assembly 202 The forward conduction voltage between the pole and the base, therefore, the characteristics of the Schottky diode assembly 201 are still the main factors in the use of normal forward conduction.

However, when the junction barrier Schottky diode 200 encounters a reverse electrostatic impact, a reverse-biased current will first be formed between the positive and negative contacts of the junction barrier Schottky diode 200, and this reverse-biased current is mainly It enters from the negative contact 280 , flows through the first N-type doped region 260 , the N-type well 213 , the metal layer 250 , and finally flows out from the positive contact 270 . When this reverse-biased current increases to a certain amount, so that the voltage drop caused in the N-type well 213 is large enough to cause conduction between the emitter and the base of the transistor component 202, the transistor component 202 is also That is, it is turned on, and the main channel of the transistor, that is, between the second P-type doped region 262 and the first P-type doped region 240, forms a strong conduction current capability, thus enhancing the ability to conduct electrostatic charges . In other words, the presence of the parasitic transistor component 202 enhances the reverse ESD capability of the junction barrier Schottky diode 200 .

To further illustrate, the junction barrier Schottky diode 200 disclosed in the present invention may further include a plurality of reverse bias leakage current suppression structures 245 disposed in the N-type well 213 and extending downward from the upper surface 211 , and located on one side of the first P-type doped region 240 , and located below the metal layer 250 . The reverse bias leakage current suppression structure 245 can be a plurality of P-type doped regions (for example, defined as a plurality of third P-type doped regions), or a plurality of field oxide layers (for example, defined as a plurality of first field oxide layers) The structure of the field oxide layer also includes the shallow trench isolation (Shallow Trench Isolation, STI) structure in the advanced process (after the 0.35 micron process). Between each reverse bias leakage current suppression structure 245, and in the region of the N-type well 213 between the reverse bias leakage current suppression structure 245 and the first P-type doped region 240, a junction barrier Schottky diode 200 is formed. main current path. The arrangement of the plurality of reverse bias leakage current suppression structures 245 can reduce the amount of leakage current between the positive and negative contacts of the junction barrier Schottky diode 200 when it is reverse biased.

Moreover, as shown in FIG. 2, the structure of the junction barrier Schottky diode 200 may further include a second field oxide layer 220, which is disposed in the N-type well 213, extends downward from the upper surface 211, and Located between the first P-type doped region 240 and the first N-type doped region 260 . The second field oxide layer 220 is a structure that is usually formed when the junction barrier Schottky diode 200 is manufactured with semiconductor manufacturing process, so it can be used as one of the structural features of the junction barrier Schottky diode 200 . But it should be noted that the second field oxide layer 220 is not a necessary structure. In addition, the junction barrier Schottky diode 200 may further include a third field oxide layer 230 located at the outermost layer of the junction barrier Schottky diode 200 to separate it from other components.

As shown in FIG. 2, in another embodiment of the present invention, the first N-type doped region 260 is adjacent to the second P-type doped region 262. This is a preferred implementation mode, which can make the junction barrier The area of the terky diode 200 is small to save hardware cost. However, the adjacent arrangement is not a necessary arrangement, and a specific distance can be spaced between the first N-type doped region 260 and the second P-type doped region 262 without affecting the junction barrier disclosed in the present invention. The main characteristics of the terky diode 200.

Moreover, as shown in FIG. 2 , in yet another embodiment of the present invention, a P-type lightly doped region 264 may be further included, located below the second P-type doped region 262 . The P-type lightly doped region 264 has a lighter P-type doping concentration than the first P-type doped region 240, thus enhancing the beta (β, beta) gain of the parasitic transistor component 202, that is, the transistor component 202 has a stronger current conduction effect, and thus enhances the reverse electrostatic discharge capability of the junction barrier Schottky diode 200 disclosed in the present invention.

FIG. 3 is a cross-sectional structural view of a second embodiment of a junction barrier Schottky diode 300 disclosed in the present invention. The junction barrier Schottky diode 300 of the present invention differs from the junction barrier Schottky diode 200 of the first embodiment in that the junction barrier Schottky diode 200 of the first embodiment has a first The N-type doped region 260 is located between the second P-type doped region 262 and the first P-type doped region 240, and the junction barrier Schottky diode 300 of the second embodiment, its second P-type doped The region 262 is located between the first N-type doped region 260 and the first P-type doped region 240 . The structure formed by the junction barrier Schottky diode 300 makes the first N-type doped region 260 far away from the first P-type doped region 240, so that when the junction barrier Schottky diode 300 is reverse-biased and When a reverse biased current is formed, at the same current value, a larger voltage drop in the N-type well 213 will be caused, so that the parasitic transistor component of the junction barrier Schottky diode 300 (such as the component 202 in FIG. 2 ) is easier to be turned on, so it has better reverse electrostatic discharge capability.

In addition, as shown in FIG. 3, the first N-type doped region 260 of the junction barrier Schottky diode 300 of the present invention is adjacent to the second P-type doped region 262. This is a preferred implementation mode, but it does not It is not limited thereto, and reference may be made to relevant descriptions in the first embodiment, which will not be repeated here. Furthermore, in yet another embodiment of the junction barrier Schottky diode 300 , it may further include a P-type lightly doped region 264 located below the second P-type doped region 262 .

FIG. 4 is a cross-sectional structural view of a third embodiment of a junction barrier Schottky diode 400 disclosed in the present invention. The difference from the junction barrier Schottky diode 200 of the first embodiment is that the junction barrier Schottky diode 400 further includes a second N-type doped region 266 disposed in the N-type well 213 , extending downward from the upper surface 211 , and the second P-type doped region 262 is located between the first N-type doped region 260 and the second N-type doped region 266 . This is a structural modification, and the function of its components can refer to the description of the first embodiment, and will not be repeated here.

In addition, as shown in FIG. 4, in another embodiment of the junction barrier Schottky diode 400 disclosed in the present invention, the first N-type doped region 260, the second P-type doped region 262, and The second N-type doped regions 266 are closely arranged in pairs adjacent to each other. This is a preferred implementation mode, but it is not limited thereto. Reference may be made to the relevant descriptions in the first embodiment, and no further description is made here. repeat.

FIG. 5 is a cross-sectional structural diagram of a fourth embodiment of a junction barrier Schottky diode 500 disclosed in the present invention. The difference from the junction barrier Schottky diode 200 of the first embodiment is that the junction barrier Schottky diode 500 further includes a third P-type doped region 268 disposed in the N-type well 213 , extending downward from the upper surface 211 , and the first N-type doped region 260 is located between the second P-type doped region 262 and the third P-type doped region 268 . This is a structural modification, and the function of its components can refer to the description of the first embodiment, and will not be repeated here.

In addition, as shown in FIG. 5, in another embodiment of the junction barrier Schottky diode 500 of the present invention, the second P-type doped region 262, the first N-type doped region 260 and the third P-type doped region The doped regions 268 are closely arranged in a manner of adjacent to each other, which is a preferred implementation manner, but not limited thereto. Reference may be made to relevant descriptions in the first embodiment, and details will not be repeated here.

FIG. 6 is a current-voltage relationship diagram and a reverse bias leakage current curve diagram of the junction barrier Schottky diode of the present invention and the conventional technology. Wherein the disclosure of the present invention takes the junction barrier Schottky diode 200 of the first embodiment as the measurement object, and further divides it into "not including the P-type lightly doped region 264" (square mark in the figure) and " It includes two types of P-type lightly doped regions 264" (marked by triangles in the figure). Those skilled in the art use the junction barrier Schottky diode 100 disclosed in FIG. 1 as the measurement object (marked with a rhombus in the figure). Among them, the curves 610, 620, and 630 are the relationship diagrams of the reverse current and the reverse bias voltage, and the horizontal axis should correspond to the lower axis, that is, "reverse bias voltage"; while the curves 630, 640, and 650 are the After the voltage measurement is completed, measure the reverse-bias leakage current with the reverse-bias voltage (for example, 5 volts) used in general applications. The horizontal axis should correspond to the upper axis, that is, "reverse-bias leakage current". From Figure 6, it can be found that the junction barrier Schottky diodes of the three structures, before excessive reverse bias voltage is applied to cause damage, the order of magnitude of the reverse bias leakage current of the three is similar, about 1 microampere So under normal application, its component characteristics should be not far from each other. Furthermore, when corresponding to a specific reverse bias voltage, such as 65 volts, it can be found that the junction barrier Schottky diode realized by conventional technology has the smallest conduction reverse current, that is to say, it can discharge the reverse electrostatic charge The ability of the worst, electrostatic discharge ability is the weakest. The second is the structure of the junction barrier Schottky diode "not including the P-type lightly doped region 264", and the largest is the structure of the junction barrier Schottky diode "including the P-type lightly doped region 264". structure, which just confirms the aforementioned "P-type lightly doped region 264 has a lighter P-type doping concentration than the first P-type doped region 240, thus strengthening the beta (β, beta) of the parasitic transistor component 202 ) gain, that is, the transistor component 202 has a stronger current conduction effect, and thus enhances the reverse electrostatic discharge capability of the junction barrier Schottky diode 200 disclosed in the present invention”.

Although the embodiments of the present invention are disclosed as above, they are not intended to limit the present invention. Anyone skilled in the relevant art can use the shapes, structures, and features described in the application scope of the present invention without departing from the spirit and scope of the present invention. and quantity can be slightly changed, so the scope of patent protection of the present invention must be defined by the scope of patent application attached to this specification.

Claims (9)

1. a junction barrier Schottky diode, characterized in that the junction barrier Schottky diode comprises: A silicon substrate has an upper surface, the silicon substrate has an N-type buried layer below the upper surface, and an N-type buried layer is located between the upper surface of the silicon substrate and the N-type buried layer. type well; a first P-type doped region, disposed in the N-type well, and extending downward from the upper surface; a metal layer covering the upper surface and located above one side of the first P-type doped region; a second P-type doped region, disposed in the N-type well, extending downward from the upper surface, and located on the other side of the first P-type doped region; and A first N-type doped region, disposed in the N-type well, extending downward from the upper surface, and located on the other side of the first P-type doped region; Wherein the first N-type doped region is located between the second P-type doped region and the first P-type doped region; Wherein the junction barrier Schottky diode further includes a second N-type doped region, disposed in the N-type well, extending downward from the upper surface, and the second P-type doped region The region is located between the first N-type doped region and the second N-type doped region. 2. The junction barrier Schottky diode as claimed in claim 1, characterized in that, the junction barrier Schottky diode further comprises a plurality of third P-type doped regions arranged in the N-type The well extends downward from the upper surface, is located on one side of the first P-type doped region, and is located below the metal layer. 3. The junction barrier Schottky diode according to claim 1, wherein the junction barrier Schottky diode further comprises a plurality of first field oxide layers disposed between the N-type wells , extending downward from the upper surface, and located on one side of the first P-type doped region, and located below the metal layer. 4. The junction barrier Schottky diode according to claim 1, wherein the junction barrier Schottky diode further comprises a second field oxide layer disposed in the N-type well , extending downward from the upper surface and located between the first P-type doped region and the first N-type doped region. 5. The junction barrier Schottky diode of claim 1, wherein the first N-type doped region is adjacent to the second P-type doped region. 6. The junction barrier Schottky diode according to any one of claims 1 to 5, characterized in that, the junction barrier Schottky diode further comprises a P-type lightly doped region located at the Below the second P-type doped region. 7. The junction barrier Schottky diode according to claim 1, wherein the first N-type doped region, the second P-type doped region and the second N-type doped region Miscellaneous areas are adjacent to each other. 8. A junction barrier Schottky diode, characterized in that the junction barrier Schottky diode comprises: A silicon substrate has an upper surface, the silicon substrate has an N-type buried layer below the upper surface, and an N-type buried layer is located between the upper surface of the silicon substrate and the N-type buried layer. type well; a first P-type doped region, disposed in the N-type well, and extending downward from the upper surface; a metal layer covering the upper surface and located above one side of the first P-type doped region; a second P-type doped region, disposed in the N-type well, extending downward from the upper surface, and located on the other side of the first P-type doped region; and A first N-type doped region, disposed in the N-type well, extending downward from the upper surface, and located on the other side of the first P-type doped region; Wherein the second P-type doped region is located between the first N-type doped region and the first P-type doped region; Wherein the junction barrier Schottky diode further includes a third P-type doped region, disposed in the N-type well, extending downward from the upper surface, and the first N-type doped region The region is located between the second P-type doped region and the third P-type doped region. 9. The junction barrier Schottky diode according to claim 8, wherein the second P-type doped region, the first N-type doped region and the third P-type doped region Miscellaneous areas are adjacent to each other.