TWI383506B - Schottky diode device and method for fabricating the same - Google Patents

Description

Xiaoji diode device and manufacturing method thereof

The present invention relates to semiconductor devices, and more particularly to a Schottky diode device and a method of fabricating the same.

A Schottky diode is a semiconductor device having a metal-semiconductor junction, and the current-voltage characteristics of the metal-semiconductor junction structure depend on the polarity of the applied voltage.

When the Schottky diode is in a forward bias (ie, a positive voltage is applied to the anode and a negative voltage is applied to the cathode), the carrier can be turned on, and when the Schottky diode is in a reverse bias (ie, the anode is applied with a negative voltage and When a positive voltage is applied to the cathode, the carrier is not easily conductive, and thus has the same unidirectional conduction characteristics as a general pn junction diode. In addition, since the Xiaoji two-pole system moves as a single carrier, it has a relatively low threshold voltage in the forward bias and a very fast response speed in the forward bias switching.

Referring to Figure 1, a cross-sectional view of a conventional Schottky diode device 100 is shown. As shown in FIG. 1, the Schottky diode device 100 includes an n-type drift region 104, an anode electrode 112, a cathode electrode 114, and n+ formed in an n-drift region 104. Main components such as doped region 116. The n-type drift region 104 is formed in the surface of the p-type germanium substrate 102, and two separate field oxides 108 are formed on the surface of the n-type drift region 104 to define the field oxide 108 on the surface of the n-type drift region 104. The anode region 150 and the cathode region 160 are separated. A patterned interlayer dielectric layer 110 is formed on the surface of the n-type drift region 104, which covers a portion of the surface oxide 108 and its adjacent n-type drift region 104 and n+ doped region 116, and is made of titanium. The anode electrode 112 and the cathode electrode 114 formed of a metal material such as titanium nitride, tungsten or aluminum respectively cover and penetrate the interlayer dielectric layer 110 to physically contact the n-type drift region 104 located in the anode region 150 and at the cathode, respectively. The n+ doped region 116 within region 160. A p-type doped region 106 is formed in the n-type drift region 104 adjacent to the field oxide 108 in the anode region 150 to avoid formation of a high electric field in the region of the electrode 112 adjacent to the n-type drift region 104 and the field oxide 108. In order to enhance the voltage collapse performance of the Xiaoji diode device 100 under the reverse bias. The interface between the anode electrode 112 in the Xiaoji diode device 100 and the n-type drift region 104 in contact with each other is a metal-semiconductor junction 120.

In addition, in order to further increase the breakdown voltage under the reverse bias of the Schottky diode device 100, the n-type dopant concentration in the n-type drift region 104 is generally not higher than 2.0*10 ¹⁶ atoms/cm ³ . The doping concentration of the n-type drift region 104 helps to increase the breakdown voltage performance of the Schottky diode device 100 under reverse bias, but causes the Schottky diode device 100 to circulate under forward bias. The current per unit area between the anode region 150 and the cathode region 160 is limited.

Therefore, there is a need for a novel Schottky diode device that meets the high breakdown voltage at reverse voltage and high unit area current under forward bias.

In view of the above, the present invention provides a Xiaoji diode device and a method of fabricating the same to improve the electrical performance of the breakdown voltage and current per unit area.

According to an embodiment, the present invention provides a Schottky diode device comprising: a p-type semiconductor structure; an n-type drift region disposed on a surface of the p-type semiconductor structure, wherein the n-type drift region includes a dopant concentration Dividing a first n-type doped region and a second n-type doped region, and the second n-type doped region surrounds a sidewall of the first n-type doped region and has a first n-type The doped region is a high dopant concentration; a plurality of isolation structures are disposed in the second n-type doping region of the n-type drift region to define an anode region and a cathode region, wherein the anode region is exposed a surface of the first n-type doped region and the cathode region partially exposing a surface of the second n-type doped region; a third n-type doped region disposed at a second n-type doping partially exposed for the cathode region a surface of the impurity region, wherein the third n-type doped region has a dopant concentration higher than the second n-type doped region; an anode electrode disposed over the first n-type doped region in the anode region And a cathode electrode disposed above the third n-type doped region in the cathode region.

According to another embodiment, the present invention provides a method of fabricating a Schottky diode device, comprising: providing a p-type semiconductor layer; forming an n-type drift region in a surface of the p-type semiconductor layer, wherein the n-type drift The region includes a first n-type doped region and a second n-type doped region surrounding the first n-type doped region, and the second n-type doped region has a higher than the first n-type doped region a concentration of the dopant; forming a plurality of isolation structures in the second n-type doped region adjacent to the first n-type doped region, thereby defining an anode region and a cathode region on the p-type semiconductor layer, Wherein the anode region exposes a portion of the first n-type doped region and the second n-type doped region adjacent to the first n-type doped region, and the cathode region exposes only the second n-type doping Another portion of the region; forming a third n-type doped region within the second n-type doped region exposed by the cathode region; and forming an anode electrode and a cathode electrode in the anode region and the cathode region, respectively And physically contacting the first n-type doped region and the third n-type doped region, respectively.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

2-6 are a series of cross-sectional views showing a method of fabricating a Schottky diode device in accordance with an embodiment of the present invention.

Referring to FIG. 2, a p-type semiconductor structure, such as a p-type semiconductor layer 202, is first provided. The p-type semiconductor layer 202 is, for example, an epitaxial layer of a semiconductor material containing germanium or germanium or a portion of a substrate. A plurality of patterned mask layers 204 are then formed on the surface of the semiconductor substrate 202 to expose portions of the p-type semiconductor layer 202. Next, an ion implantation process 206 is performed on the p-type semiconductor layer 202 and the mask layer 204 is used as an ion implantation mask, thereby forming a plurality of phase-separated n-type dopings in the p-type semiconductor layer 202. Area 208. The ion implantation process 206 uses n-type dopants such as phosphorus and arsenic, and the ion implantation energy used is about 500KeV~800KeV, and the n-type dopant dose is about 2*10 ¹² ~8. *10 ¹² atoms/cm ² .

As shown in FIG. 2, since a plurality of separate mask layers 204 are formed on the p-type semiconductor layer 202, the n-type doped regions 208 are separated from the formed phase after the ion implantation process 206 is performed. There is a p-type strip region 210 which is not doped with n-type, respectively, which still has the same doping characteristics and dopant concentration as the p-type semiconductor layer 202. Here, the mask layers 204 each have a width W of 0.4 μm to 0.8 μm and a distance P between 0.4 μm and 0.8 μm between adjacent mask layers 204. Thus, the number and range of the p-type strip regions 210 formed by the control can be adjusted by adjusting the number of the mask layers 204 formed on the p-type semiconductor layer 202, the width W thereof, and the distance P between the adjacent mask layers 204. With contours.

Referring to FIG. 3, after removing the mask layer 204 formed on the p-type semiconductor layer 202 (see FIG. 2), a tempering process (not shown) is performed to maintain a temperature of 1000 to 1100 ° C. The tempering process is performed. Therefore, after the tempering process is performed, a first n-type doping region 214 and a second n-type doping region 212 surrounding one of the sidewalls of the first n-type doping region 214 are formed on the surface of the p-type semiconductor layer 202. The first n-type doped region 214 and the bottom surface of the second n-type doped region 212 respectively contact the p-type semiconductor layer 202. Here, the dopant concentration in the second n-type doping region 212 is about 2*10 ¹⁶ ~8*10 ¹⁶ atoms/cm ³ , and the dopant concentration in the first n-type doping region 214 is about 4*. 10 ¹⁵ ~ 2 * 10 ¹⁶ atoms / cm ³ , and the dopant concentration in the second n-type doping region 212 is higher than the dopant concentration in the first n-type doping region 214, and the previous p-type strip region 210 After the tempering procedure was implemented, it no longer existed. The first n-type doped region 214 and the second n-type doped region 212 constitute an n-type drift region 250 of the Schottky diode device.

Referring to FIG. 3, a patterned mask layer 216 is then formed on the surface of the n-type drift region 250 and a portion of the second n-type doping region 212 on both sides of the first n-type doping region 214 is exposed. Then, an ion implantation process 218 is performed by using the mask layer 216 as an ion implantation mask to form a p in the second n-type doping region 212 on both sides of the first n-type doping region 214. Type doped region 220. The ion implantation process 218 uses a p-type dopant such as boron, which uses an ion implantation energy of about 40 KeV to 80 KeV, and the implanted p-type dopant dose is about 8*10 ¹³ ~5*. 10 ¹⁴ atoms/cm ² .

Referring to FIG. 4, after removing the mask layer 216 (see FIG. 3), two separate isolation structures 222 are formed on the surface of the second n-type doping region 212 in the n-type drift region 250 and therein. The anode region 260 and the cathode region 270 of the Schottky diode device are defined on the surface of the n-type drift region 250. Here, the isolation structure 222 is shown as a conventional filed oxide and can be formed by a conventional field oxide process, but the invention is not limited thereto, and the isolation structure 222 can also adopt other types of isolation structures. . When the isolation structure 222 is formed, the previously formed p-type doping region 220 (see FIG. 3) may be simultaneously tempered, and after the isolation structure 222 is formed, the isolation structure 222 is simultaneously formed into adjacent and covered isolation structures 222. The p-doped region 220 of the one corner. The p-doped region 220 also extends partially into the first n-type doped region 214. A patterned mask layer 224 is then formed to substantially cover the isolation structure 222 and the anode region 260 and expose the surface of the second n-type doped region 212 within the cathode region 270. An ion implantation process 226 is then performed to form an n+ doped region 228 on the surface of the second n-type doped region 212 for use as a cathode junction. The ion implantation process 226 uses n-type dopants such as phosphorus and arsenic, and the ion implantation energy used is about 40KeV~60KeV, and the n-type dopant dose is about 1*10 ¹⁵ ~5. *10 ¹⁵ atoms/cm ² .

Referring to FIG. 5, after removing the mask layer 224 (see FIG. 4), a patterned interlayer dielectric layer 230 is formed, which substantially covers the isolation structure 222 and a portion of the p-type dopant adjacent to the isolation structure 222. The impurity region 220 and the n+ doping region 228. Openings 235 and 237 are formed in the interlayer dielectric layer 230 to expose the entire surface of the first n-type doping region 214 and a portion of the surface of the n+ doping region 228, respectively.

Referring to FIG. 6, a patterned electrode layer 232 and 234 are formed, wherein the electrode layer 232 is disposed over the p-type doping region 220 and the first n-type doping region 214 and partially cover the adjacent interlayer dielectric layer. 230, and the electrode layer 234 is disposed over the n+ doped region 228 and partially covers the adjacent interlayer dielectric layer 234. The electrodes 232 and 234 are used as an anode electrode and a cathode electrode, respectively, and may be formed of a metal material such as titanium, titanium nitride, tungsten, aluminum, or the like, and may be formed by a conventional process such as deposition, grinding, and etching.

As shown in FIG. 6, a Schottky diode device according to an embodiment of the present invention is shown, which mainly includes: a p-type semiconductor structure (for example, p-type semiconductor layer 202); an n-type drift region, which is disposed on a p-type semiconductor structure surface, wherein the n-type drift region comprises a first n-type doped region (eg, a first n-type doped region 214) and a second n-type doped region (eg, a second) having different dopant concentrations An n-type doped region 212), and the second n-type doped region surrounds a sidewall of the first n-type doped region and has a higher dopant concentration than the first n-type doped region; a plurality of isolation structures ( For example, the isolation structure 222) is disposed in the second n-type doping region of the n-type drift region to define an anode region (eg, the anode region 260) and a cathode region (eg, the cathode region 270), wherein the anode region is exposed. a surface of the first n-type doped region and a portion of the cathode region exposing a surface of the second n-type doped region; a third n-type doped region (eg, n+ doped region 228) disposed to be partially exposed for the cathode region a second n-type doped region surface, wherein the third n-type doped region has a higher dopant concentration than the second n-type doped region; an anode electrode (eg, an anode) 232), disposed on the first n-doped region of the anode region; and a cathode over the electrode (e.g., cathode electrode 234), disposed on the third n-type doped region of the cathode region.

In this embodiment, the Schottky diode device includes a first n-type doping region 214 having a relatively low dopant concentration and a second n-type doping region 212 having a relatively high dopant concentration. An n-type drift region 250, wherein the first n-type doped region 214 is in physical contact with the anode electrode 232, based on its relatively low n-type dopant concentration, thereby contributing to the elevation of the anode electrode 232 and the first n-type The breakdown voltage at the reverse bias of the metal-semiconductor junction 280 between the doped regions 214. In addition, since the second n-type doping region 212 between the anode region 260 and the cathode region 270 has a relatively high n-type dopant concentration, the amount of current per unit area of the Schottky diode device can be improved.

Further, referring to the manufacturing flow of FIGS. 2 to 6, the manufacturing method of the Schottky diode device of the present invention is for forming the n-type drift region 104 in the conventional Schottky diode device as shown in FIG. The pattern mask is modified to form an n-type drift region 250 composed of two different n-type doping regions of different n-type dopant concentrations as shown in FIG. 6 without causing light required for the manufacturing process. The number of masks is increased, and the purpose of controlling the n-type dopant concentration under the Schottky junction 280 can be achieved by appropriately adjusting the number and width of the p-type strip regions 210 and the spacing between the p-type strip regions 210.

While the present invention has been described above by way of a preferred embodiment, it is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

100. . . Xiaoji diode device

102. . . P-type germanium substrate

104. . . N-type drift region

106. . . P-doped region

108. . . Field oxide

110. . . Interlayer dielectric layer

112. . . Anode electrode

114. . . Cathode electrode

116. . . n+ doped region

120. . . Metal-semiconductor junction

150. . . Anode region

160. . . Cathode region

202. . . P-type semiconductor layer

204. . . Mask layer

206. . . Ion implantation procedure

208. . . N-doped region

210. . . P-type strip

212. . . Second n-doped region

214. . . First n-doped region

216. . . Mask layer

218. . . Ion implantation procedure

220. . . P-doped region

222. . . Isolation structure

224. . . Mask layer

226. . . Ion implantation procedure

228. . . n+ doped region

230. . . Interlayer dielectric layer

232, 234. . . electrode

235, 237. . . Opening

250. . . N-type drift region

260. . . Anode region

270. . . Cathode region

280. . . Metal-semiconductor junction

W. . . Width of the mask layer/p-type strip

P. . . Mask layer / p-type strip area

Figure 1 shows a cross-sectional view of a conventional Xiaoji diode device;

2-6 are a series of cross-sectional views showing a method of fabricating a Schottky diode device in accordance with an embodiment of the present invention.

202. . . P-type semiconductor layer

212. . . Second n-doped region

214. . . First n-doped region

220. . . P-doped region

222. . . Isolation structure

228. . . n+ doped region

230. . . Interlayer dielectric layer

232, 234. . . electrode

250. . . N-type drift region

260. . . Anode region

270. . . Cathode region

280. . . Metal-semiconductor junction

Claims (18)

A Schottky diode device comprising: a p-type semiconductor structure; an n-type drift region disposed on a surface of the p-type semiconductor structure, wherein the n-type drift region comprises a first n-type doping different in dopant concentration a doped region and a second n-type doped region, the second n-type doped region surrounding and contacting the sidewall of the first n-type doped region and having a higher doping than the first n-type doped region a concentration of the first n-type doped region physically contacting the p-type semiconductor structure; a plurality of isolation structures disposed in the second n-type doped region of the n-type drift region to define a An anode region and a cathode region, wherein the anode region exposes a surface of the first n-type doped region and the cathode region partially exposes a surface of the second n-type doped region; a third n-type doped region is disposed on a surface of the second n-type doped region partially exposed by the cathode region, wherein the third n-type doped region has a dopant concentration higher than the second n-type doped region; an anode electrode is disposed at the anode Above the first n-type doped region in the region; and a cathode electrode, the third n-type doped region disposed in the cathode region On. The Xiaoji diode device according to claim 1, wherein the first n-type doping region has a dopant concentration of 4*10 ¹⁵ ～2*10 ¹⁶ atoms/cm ³ , and the first The two n-type doped regions have a dopant concentration of between 2*10 ¹⁶ and 8*10 ¹⁶ atoms/cm ³ . Such as the Xiaoji diode device described in claim 1 of the patent scope, The bottom surface of the second n-type doped region contacts the p-type semiconductor structure. The Xiaoji diode device according to claim 1, further comprising a p-type doping region disposed on the first n-type doping region and the second n-type doping exposed for the anode region. Within the surface of the miscellaneous region and covering the corners of one of the isolation structures. The Schottky diode device of claim 4, wherein the p-type doped region has a dopant concentration of between 8*10 ¹⁵ and 5*10 ¹⁶ atoms/cm ³ . The Xiaoji diode device according to claim 4, further comprising an interlayer dielectric layer disposed between the isolation structure and the anode electrode and the cathode electrode, wherein the interlayer dielectric layer covers the plurality of layers An isolation structure and a portion of the adjacent p-type doped region and the third n-type doped region. The Schottky diode device of claim 4, wherein the anode electrode physically contacts the p-type doped region and the first n-type doped region. The Xiaoji diode device according to claim 1, wherein the third n-type doping region has a dopant concentration of between 1*10 ¹⁷ and 5*10 ¹⁷ atoms/cm ³ . The Schottky diode device of claim 1, wherein the anode electrode and the cathode electrode comprise titanium, titanium nitride, tungsten or aluminum. A method for fabricating a Schottky diode device, comprising: providing a p-type semiconductor layer; forming an n-type drift region in a surface of the p-type semiconductor layer, wherein the n-type drift region comprises a first n-type doped region And surrounding and contacting a second n-type doped region of the first n-type doped region, wherein the second n-type doped region has a dopant concentration higher than the first n-type doped region, and wherein First n-type doping The bottom surface of the impurity region physically contacts the p-type semiconductor structure; and a plurality of isolation structures are formed in the second n-type doped region adjacent to the first n-type doped region, thereby defining a p-type semiconductor layer An anode region and a cathode region, wherein the anode region exposes a portion of the first n-type doping region and the second n-type doping region adjacent to the first n-type doping region, and the cathode region is exposed only Another portion of the second n-type doped region; forming a third n-type doped region within the second n-type doped region exposed by the cathode region; and forming respectively in the anode region and the cathode region An anode electrode and a cathode electrode respectively physically contact the first n-type doped region and the third n-type doped region. The manufacturing method of the Schottky diode device according to claim 10, wherein the first n-type doping region has a dopant concentration of 4*10 ¹⁵ ～2*10 ¹⁶ atoms/cm ³ , The second n-type doped region has a dopant concentration of between 2*10 ¹⁶ and 8*10 ¹⁶ atoms/cm ³ , and the third n-type doped region has a range of 1*10 ¹⁷ to 5*10 ¹⁷ The dopant concentration of atoms/cm ³ . The method of manufacturing a Schottky diode device according to claim 10, wherein the forming the n-type drift region in the surface of the p-type semiconductor layer comprises: forming a plurality of spacers on the p-type semiconductor layer a mask layer; performing a first ion implantation process, using the first mask layer as an implantation mask, forming a plurality of spaced fourth n-type doped regions in the p-type semiconductor layer and located a plurality of p-type strip regions of the fourth n-type doping region; removing the first mask layers; Performing a first tempering process to form the first n-type doped region and the second n-type doped region surrounding the first n-type doped region in the p-type semiconductor layer, thereby forming the n-type Drift zone. The method for manufacturing a Schottky diode device according to claim 12, wherein the p-type strip regions have a width of between 0.4 μm and 0.8 μm and the p-type strip regions are interposed therebetween. Between 0.4μm and 0.8μm. The method for manufacturing a Schottky diode device according to claim 10, wherein before forming the isolation structures, the method further comprises: forming a first mask layer partially exposed adjacent to the first n-type doping region a portion of the second n-type doped region; and performing a first ion routing process using the first mask layer as an implant mask to be adjacent to the second of the first n-type doped regions The surface of the n-type doped region forms a p-type doped region. The manufacturing method of the Schottky diode device of claim 14, wherein the forming the isolation structure further comprises: simultaneously converting the p-type doped region into the first n-type doped region; And a p-type guard ring connected to the second n-type doping region to cover a corner of the isolation structure. The method for manufacturing a Schottky diode device according to claim 15, wherein the p-type guard ring has a dopant concentration of 8*10 ¹⁵ atoms/cm ³ to 5*10 ¹⁶ atoms/cm ³ . . The method of manufacturing a Schottky diode device according to claim 10, wherein the isolation structures are field oxides. Such as the Xiaoji diode device described in claim 15 A manufacturing method, wherein the anode electrode and the cathode electrode comprise titanium, titanium nitride, tungsten or aluminum.