TWI261362B - Fabrication of schottky barrier diode - Google Patents

Abstract

In this invention, Schottky barrier diode (SBD) with sophisticated edge termination (ET) structures including p<+>-poly-Si guard ring, p<+>-poly-Si floating ring, and RESURF-type lateral super-junction (LSJ) is disclosed. The ET schemes employed in this work are aimed at reducing the surface electric field to have a breakdown voltage approaching the ideal value. Also, it was found that the device could suppress the leakage current, and adjust the forward voltage drop and Schottky barrier height (SBH). Thus, the disclosed device will be successfully applicable to the field of the microwave and high power devices.

Description

1261362 IX. Description of the invention: [Technical field to which the invention pertains]: The present invention relates to a Schottky Barrier (Schottky Barrier)

Diode; SBD) and its manufacturing method, and in particular, a high power Schottky diode with high breakdown voltage, low leakage current density and low forward voltage drop and a method of manufacturing the same. 0 [Prior Art] In today's electronics industry, the rectifying diode is the basic active component necessary for general electronic products. The Xiaoji diode consisting of metal and semiconductor is one of them. The Xiaoji diode has a majority. The high-speed reaction of the carrier conduction and the low cut-in voltage make it more suitable for the high-frequency circuit that needs to be switched quickly than the P-type and n-type semiconductor. In the conventional Schottky diode, one side of the junction is made of metal such as gold, silver or platinum, the other side is doped with impurities (four) (usually forming an n-type semiconductor), # when there is no external bias, the η • type semiconductor The affinity energy of the free electrons contained in the region is smaller than the work function of the free electrons contained in the metal region (ie, the energy level is lower), and the difference in the magnitude of the energy (ie, the energy level) is called the Xiaoji barrier (Sch〇ttky; Sbh). When the forward-directed Fortune is applied to the Xiaoji diode, the freedom of the n-type semiconductor region, 1 can obtain sufficient energy to transition to a higher _, and thus can form a forward current across the junction region. When a reverse bias is applied, there is no charge storage due to metal, 'no 3 V-number carriers', and the reverse recovery time is extremely short. Therefore, the demand for high-power Schottky diodes in the application market is high-crash electric C low reading and low forward bias, wherein the breakdown voltage depends on the resistance value and thickness of the 12671362 substrate, and the thickness of the crucible substrate is Thick, the more the resistance value is π 'the voltage of the neck is relatively increased. However, the higher the resistance value, the greater the forward bias of the operating product, and the lower the forward current driving capability. In addition, in the outer periphery of the junction of the metal and the semiconductor of the large-area Schottky diode, the power line is easily concentrated at the edge of the element due to the Junction Curvature Effect, and the overall breakdown voltage is lowered. The height of the Xiaoji barrier determines the magnitude of the leakage current and the forward bias. The higher barrier height forms a lower leakage current, while the lower barrier height forms a lower forward bias. Get the right balance between the two. In view of the wide application of today's high-frequency communication equipment and high-power components, the physical characteristics of the Xiaoji diode are in need of further improvement, and the above problems can be improved by the present invention. SUMMARY OF THE INVENTION To solve the above and other problems and to attain the technical advantages of the present invention, the present invention provides a Schottky diode and a method of manufacturing the same to improve the performance of a conventional Schottky diode. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a Schottky diode having better physical properties for use in a variety of high frequency and high power devices requiring increased demand. Another object of the present invention is to provide a method for manufacturing a Xiaoji diode, which is combined with a side super junction structure, a polycrystalline ruthenium ring and a polycrystalline floating raft to enhance the base of the Xiaoji diode. Item physical characteristics. According to the above object of the present invention, a high power Schottky diode having physical characteristics such as high breakdown voltage, low leakage current density, and low forward bias is proposed. According to a preferred embodiment of the invention 1261362, the Schottky diode mainly comprises an epitaxial germanium substrate, a field oxide layer, and a surface super-contact surface of the REDuce SURface Field (RESURF1) type (Lateral Super Junction). ; LSJ) structure, Poly-Si Guard Ring, poly_Si F1〇ating Ring and Schottky Contact metal electrodes. In accordance with the purpose of the present invention, a method for manufacturing a Schottky diode is proposed to adjust the performance of various parameters such as component size, doping concentration, and ion implantation depth to obtain better breakdown voltage and leakage current characteristics. According to a preferred embodiment of the present invention, the method mainly comprises controlling physical properties such as a width-adjustable forward voltage value of the polysilicon guard ring and a height of the Xiaoji barrier; increasing the depth of the polysilicon guard ring to enhance the collapse Voltage value; controlling the width of the polysilicon floating ring can increase the breakdown voltage and reduce the leakage current density. [Embodiment] Referring to Figure 1, there is shown a cross-sectional view of a Schottky diode 100 according to a preferred embodiment of the present invention. The Schottky diode 1 is made of an epitaxial wafer 110. The side super-junction structure 丨20, the field oxide oxide layer 13〇, the polycrystalline germanium guard ring 140, the polysilicon floating ring 15〇, the first metal electrode 16〇 and the second metal electrode Π0 are combined. The cat day and day sun piece 110 can use a wafer wafer having a crystal orientation (Wafer 〇rientati〇n) of &lt;100&gt; or &lt;111&gt;, and having a doped type of η, the epitaxial wafer 11 is composed of two Partially composed, the first portion is a high concentration 11 type (11+) doped substrate 111'. The second portion is a low concentration n-type (n-) doped epitaxial layer 112 on the substrate (1). 1261362 The surface super-contact structure 120 of the reduced surface electric field type is a low-density p-type (p) doped diffusion formed by the diffusion of the TB/) cloth into the oxide layer on the epitaxial germanium wafer 11 The junction structure of the impurity region spaced apart from the low concentration n-type (η·) doped region (p7rT). The field yttrium oxide layer 130 is a ruthenium oxide layer formed on the epitaxial germanium wafer 11 about 5 Å to 600 nm (nm). • The high-concentration P-type (P+) doped region formed in the i-Crystal wafer 110 and the polycrystalline germanium guard ring 140 and the polysilicon floating ring 15 are diffused into the epitaxial germanium doped region. Junction structure (p+/n). The first metal electrode 160 and the second metal electrode 17 are electrically connected (E-gUn) or vapor-deposited (EvaP〇rati〇n) to the Xiaoji contact anode and the ohmic contact cathode of the Xiaoji diode 1〇〇. a metal electrode formed at both ends. earth

The material in contact with the material is selected from the group consisting of. Two 1 矽 矽 wafers form ohmic, faulty alloys and various groups thereof. The materials are selected from aluminum,

Below is a part of the polycrystalline halo 126132 ring 150 and the polysilicon guard ring 140 respectively formed by diffusion. When the width 141 of the polysilicon guard ring i4〇 is increased, the breakdown voltage is slightly increased, and the leakage current value is increased. Lowering - The increase in the south of the Xiaoji barrier, which in turn makes the Xiaoji barrier difficult to adjust; and the depth 142 of the polysilicon retaining ring 140 increases, the breakdown voltage also increases. The junction of the first metal electrode 160 and the smectite wafer 11 ^ contains the polycrystalline stone shi shi; the 裒 140 portion, the rest is the Xiaoji junction area (SCh〇ttkyRegion) 19 〇, can define the first The metal electrode ΐό〇 is the anode of the Xiaoji 2 pole body, and the second metal electrode 170 located below the epitaxial wafer 110 is defined as the cathode of the Xiaoji diode 1 。. Referring to Figure 3, there is shown a top plan view of a partial component in accordance with a preferred embodiment of the present invention. The figure shows the distribution of the side super-junction structure 12〇, the polycrystalline 矽 guard ring 140 and the polysilicon floating ring 15〇. In this embodiment, the width m and the width 151 are both about 30 micrometers (//called The width 141 ranges from about 18 to 50 microns. The side super junction structure 12 is a junction structure with a low concentration 1) doped region and a low concentration n-doped region, and a polysilicon The guard ring and the polysilicon floating ring are spaced apart by a width of 4 microns, and the polysilicon retaining ring 140 has an inner diameter of about 5 to 1000 microns. 1 to 3 are a preferred embodiment of the structural composition of the present invention - and a preferred embodiment of the manufacturing method of the present invention will be described with reference to the following Figures 4 through 9. Referring to Figure 4, there is shown a first step of a method of manufacturing a Xiaoji_polar body in accordance with a preferred embodiment of the present invention. The epitaxial wafer is composed of a high concentration n-type doped substrate 211 and a low concentration n-doped epitaxial layer 212 on the substrate 211, and the epitaxial germanium wafer 21 is cleaned and placed at a high temperature. In the furnace, a layer of emulsified sputum (Sl〇2) film 22〇 with a thickness of about 10 mils is formed by wet oxygen method, and a window is defined, followed by embossing and engraving on the ruthenium film. The planting energy is about the ion ion cloth 11 1 黾 黾 volt (keV), and the preparation is about ίο ions/cm 2 (i〇ns/cm 2 ). In the month, refer to Figure 5, i:络+ /六六;ain 4 /,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Boron ion

:; broadcast layer: 12 to diffuse to form a surface super-contact surface, σ 222. Then, after the wafer is washed monthly, it is placed in a high temperature furnace at about 1050. . And the wet oxygen side (four) into a layer thickness of about 400 to 5 nanometers of the field of oxidized stone layer 230, and then on the field of yttrium oxide layer 23 用 with a blouse, etching technology defined after, "in the middle, formed Shape and window required for field oxygen cutting, compound ring and complex structure. Fig. 6 is a diagram showing a third step of the method for manufacturing a base diode according to a preferred embodiment of the present invention. After cleaning the wafer, it is reduced in pressure

Pressure Chemical Vap〇r Deposition; l-pcvd) forms a polycrystalline film with a thickness of about nanometer, and then carries out the ion implantation of arsenic difluoride ion at the center of m-small m 24G. The planting energy is about 1 〇〇仟 electron volt, and the implantation dose is about (7) 丨 6 ions / cm ^ 2 . Reference is made to Fig. 7, which illustrates a first step of a method for fabricating a Xiaoji diode according to a preferred embodiment of the present invention. The wafer is placed in a high-temperature furnace at a temperature of about 95 (TC, time is 20 to 8 minutes, and the butterfly ions are diffused from the polycrystalline quartz film 240 into the insect layer 212 to form a high concentration p 1261362 type. The polycrystalline shredded ring 242 and the polycrystalline floating ring 243 of the junction structure of the modified region and the n-type doped crystal cut-and-seeded region. Referring to FIG. 8, a first embodiment of the present invention is illustrated in accordance with a preferred embodiment of the present invention. The fifth step of the Xiaoji diode manufacturing method is to remove the unnecessary field oxide layer 230 and the germanium film 240 by lithography and etching techniques to define the active layer 250 of the Schottky diode 200 and The polycrystalline germanium guard ring 244 and the polycrystalline germanium floating ring 245 formed by the polycrystalline germanium film are increased, and the width 246 of the polycrystalline germanium guard ring 244 is increased to a certain range (refer to Table 1), which will make Xiao Jiji The breakdown voltage of the polar body 200 is slightly increased, the leakage current value is lowered, and the height of the Xiaoji barrier is increased, so that the Xiaoji barrier has a variable range. Table 1 The width of the polycrystalline chopping ring (β m) Forward bias at current density of 1 A/cm2 (7) Xiaoji barrier (eV) leakage current with reverse bias of 100V Degree (&quot;A/cm2) Crash voltage (V) 18 0.45 0.764 3.5 155.1 26 0.48 0.771 3.3 156.4 34 0.52 0.776 3.2 158.5 50 0.56 0.784 2.9 160.7 Referring to Figure 9, a preferred embodiment of the present invention is illustrated in accordance with a preferred embodiment of the present invention. A sixth step of the manufacturing method of the Xiaoji diode. After the wafer is cleaned, after the metal layer is plated on the active layer 250 by an electron gun or an evaporation machine, the first metal electrode 260 is defined by lithography and etching technology. The anode of the Xiaoji diode 200 is additionally plated with a second metal electrode 270 defined on the bottom of the epitaxial wafer 210 as the cathode of the Xiaoji diode 200, and the first metal electrode 160 is sufficient for the formation of the Xiaoji barrier of 11 1261362. The material is selected from the group consisting of gold, aluminum, platinum, platinum platinum and various combinations thereof; and the second metal electrode 170 is a material capable of forming an ohmic contact with the germanium wafer, the material of which is A group selected from the group consisting of: an alloy, and various combinations thereof. Referring to FIG. 10, a current-voltage characteristic diagram of a Schottky diode according to a preferred embodiment of the present invention is shown. Via 95〇. Annealing, 20-minute high temperature furnace tube reaction time, the process parameters are the width of the polycrystalline ring guard ring is 50 / / m, the side super junction width is 30, the width of the polycrystalline floating ring is 30 / / m, found (a In the characteristics of the forward bias voltage, the ideal factor (Ideal Factor) is about 1·〇7, and there are 7 logarithmic scale working ranges; and (b) the data line is the breakdown voltage of the sample. Characteristic, it is found that the voltage of the sample ασ is about 1 60 volts, and the reverse saturation current is about 5.6 μA/cm 2 (# A/cm 2 ). In addition, when the width of the polycrystalline stone guard ring is changed, the reverse voltage and leakage current density of the Xiaoji diode will be affected, that is, when the width is wider, the breakdown voltage will be slightly increased, and at the same time The reverse leakage current is also reduced, and the height of the Xiaoji barrier is also increased, which in turn can be adjusted to the height of the Xiaoji barrier. Referring to FIG. 11 , there is shown a graph of the physical characteristics of the Schottky diode to the drive-in time of the furnace tube according to a preferred embodiment of the present invention. As the time grows, it becomes larger, and the joint depth of the Fusedite Guard Ring is also deepened. (a) The data line shows the relationship between the breakdown voltage and the reaction time of the tube, and (b) the data line shows the relationship between the depth of the joint of the polycrystalline stone and the reaction time of the tube, in other words, the complex crystal The deeper the junction surface, the higher the breakdown voltage, which is a good process choice for the acceptable furnace 12 I261362 tube reaction time. Referring to Figure 12, there is shown a statistical graph of the value of the Xiaoji diode collapse according to the preferred embodiment of the present invention, which is the average value measured by taking the sample of the group, and the collapse of the sample is known from the figure. The wire is approximately between 150 and 160 volts, with a certain degree of process reliability.

Therefore, in combination with the polycrystalline stone yoke ring, the double crystal bridge ring and the reduced surface electric field, the Xiaoji diode of the side super-contact structure not only prevents the edge of the component from being able to suppress the surface of the component. Leakage current. With the above structural composition and examples, the Xiaoji diode produced by the present invention has the following preferred physical characteristics as compared with the conventional ones. The high breakdown voltage is greater than 160 volts (V); the forward current is greater than! Ampere / square centimeter (A / cm2); leakage current density is less than 5.6 microamperes / square centimeter A / cm2" When the forward current is 1 amp / cm ^ 2, the forward bias can range from 〇 · 45 to 〇 · 56 volts; and the height of the Xiaoji barrier is adjustable from 764·764 to 784·784 eV.

Although the present invention has been described above in terms of a preferred embodiment, it is not intended to limit the invention, and it is obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; A section of a polar body of the Xiaoji II 13 1261362 example. A partial exploded perspective view of a reduced watch in accordance with a preferred embodiment of the present invention. A schematic diagram of a first stage of a method according to another preferred embodiment of the present invention is shown in accordance with another preferred embodiment of the present invention.

Figure 5 is! Will +, not according to another preferred embodiment of the present invention, a Xiaoji diode manufacturing square Mu 4 μ soil to the second phase of the schematic diagram. A third stage schematic diagram of a method of fabricating a diode according to another preferred embodiment of the present invention is shown. 7 is a schematic diagram showing a fourth stage of a method for manufacturing a Xiaoji diode according to another preferred embodiment of the present invention. &lt; Fig. 8 is a view showing a fifth stage of a method for manufacturing a Xiaoji diode according to another preferred embodiment of the present invention.

Brother 2 picture system|Meeting electric field type structure Fig. 3 is a top view of the sound element. Figure 9 is a schematic view showing the sixth stage of a method for manufacturing a Xiaoji diode according to another preferred embodiment of the present invention. FIG. 10 is a diagram showing a forward bias ((a) data line) and a reverse bias ((b) data line respectively applied to a Xiaoji body according to another preferred embodiment of the present invention. When plotted), the characteristic curve of current density. Figure 11 is a diagram showing the breakdown voltage of a Xiaoji diode according to another preferred embodiment of the present invention ((a) data line), the depth of the junction of the polysilicon ring ((b) data line Diagram of the relationship between the reaction time and the furnace tube. Figure 12 is a diagram showing the proportional distribution of the breakdown voltage of the Xiao 1261362 base diode according to another preferred embodiment of the present invention.

100: Xiaoji diode 110: 111: substrate 112: 120: side super junction structure 121: 130: field oxide layer 140: 141: width 142: 15 0. polycrystalline chopping float 151: 160 : first metal electrode 170 : 180 : polycrystalline germanium layer 190 : 200 : Xiaoji diode 210 : 211 : substrate 212 : 220 : ruthenium dioxide film 221 : 222 : side super junction structure 230 : 240 : complex Crystal film 241 : 242 : Polycrystalline ring 243 : 244 : Polycrystalline ring 245 : 246 : Width 250 : 260 : First metal electrode 270 : Stupid crystal cut wafer width Crystallized 矽 矽 depth Width second metal electrode Xiaoji junction area insect crystal broken wafer stray layer ion cloth plant field oxidized stone layer ion cloth planting compound crystal chopping floating bad compound crystal broken floating connection active layer brother two metal electrode 15

Claims (1)

1261362 X. Patent application scope: ' 丨. A Xiaoji diode, including: #一磊晶矽 wafer, one of the specific crystals for the positioning of the wafer; one side of the super junction structure, formed in a layer of oxidized stone a polycrystalline germanium retaining ring formed by a polycrystalline germanium layer and boron ions implanted therein on the side of the side surface super-junction structure of the reduced surface electric field; a polycrystalline floating ring, from which the polycrystalline crystal The ruthenium layer and the implanted therein are: • boron ions are formed on the outer surface of the reduced surface electric field type side super junction structure; the electrodes may be one of the anodes and ohms of the Schottky diode dipole contact Contact one of the cathodes. 2. The Schottky diode according to the scope of claim 2, wherein the specific crystal orientation of the stupid crystal wafer is &lt;1〇〇&gt;. 3. The Schottky diode according to claim 1, wherein the specific crystal orientation of the stray crystal wafer is &lt;111&gt;. • 4) The Xiaoji diode according to item 1 of the patent application scope, wherein the day of the day is made of a substrate having a concentration of n-type doping, and a low concentration of n-type dopant on the substrate One of the impurity layers of the epitaxial layer. 5. The Xiaoji diode according to claim 1, wherein the side super junction structure is a structure having a low concentration Ρ type doping and a low concentration η type doping interval 16 1261362, and the complex The spacing between the wafer guard ring and the polysilicon floating ring is '4 microns, respectively. 6. The Xiaoji diode according to claim 1, wherein the width of one of the polysilicon guard rings is increased, so that the breakdown voltage of the Xiaoji diode is increased, and the leakage current value is lowered. The barrier increased. • 7· The Xiaoji diode described in the first paragraph of the patent application, wherein one of the depths of the polycrystalline ring is increased, so that the breakdown voltage of the Xiaoji diode is increased. The Schottky diode of the above, wherein the polycrystalline spine has an inner diameter of about 500 to 1 micron. 9. The Xiaoji diode according to claim 1, wherein the #^ metal electrode is a material capable of forming a Xiaoji barrier, and the materials are selected from the group consisting of gold, aluminum, platinum, and platinum. a group of objects and their various combinations. 1G. The Xiaoji diode according to claim 1, wherein the genus electrode is a material capable of forming an ohmic contact with the ruthenium wafer, and the materials are selected from the group consisting of aluminum, aluminum alloy and A group of various combinations. 11. A method for producing a Schottky diode, the method comprising: (4) forming a hafnium oxide film on a cat wafer wafer, and performing a diboronation on the dioxygen 17 1261362 at the window An ion implantation of a window ion is defined on the ruthenium film; ^ After cleaning, it is placed in a high temperature furnace (4) to form an oxygen =, and then an oxygen oxide layer is defined in the oxygen cleavage layer, and a polycrystalline stone is produced. And a shape of a polycrystalline floating ring; (C)> after washing the 5th worm crystal wafer, forming a polycrystalline stone film on the % bismuth layer on the 兮 备 ^ On the crystal film, the -A 7 / film is etched into the ion of the boron ion (4) placing the crystal wafer in a "high temperature furnace" to diffuse the boron ions from the polycrystalline germanium film into one of the crystal layers of the crystallized wafer, respectively forming the double crystal a ring and the polysilicon floating ring; () removing the unnecessary field oxide layer and the polysilicon film to define the active layer of the f-based diode, formed by the complex (four) film a double-crystallized ring and a polysilicon floating ring; and (f) π after washing the epitaxial wafer, after the metal layer is plated on the active layer, the first metal is defined in the 4 metal layer Outside the electrode; 3, a second metal electrode is plated on the bottom of the wafer wafer. 12. The manufacture of the Xiaoji diode according to the first paragraph of the Shenqing patent scope, and the implantation energy of the ion implant of step (a) is about 20 angstrom electron volts. . 13. The manufacture of the Schottky diode according to the U of the U.S. patent application, the implantation of the ion implant in step (a) is about ίο11 18 1261362 ions/cm 2 . 14·&quot;Please refer to the manufacturing method of the f-based diode described in item n]. The environment setting of the high-temperature furnace in the step (8) is about temperature and it is difficult to form the field yttrium oxide layer by wet oxygen method. For example, according to the Xiaoji II described in Item 1 of the patent scope, the method of forming a 4稷 day film is a low-pressure chemical vapor deposition method. 16. The Xiaoji diode according to the scope of claim 11 The thickness of the polycrystalline germanium film was about 300 nm. Fang, 17. The manufacture of Xiaoji diode as described in the scope of patent application = Method 'where the ion implanted in step (4) - the implant energy is about (10) electron volts. 18. The manufacture of the Xiaoji diode according to the scope of claim 5, wherein one of the ion implantations of the step (c) is about 1 〇16 ions/cm 2 . 19. The method of manufacturing the Xiaoji diode according to item n of the patent application, wherein the temperature of the high temperature furnace in the step (d) is set to about 950 °C. The method of manufacturing the Schottky diode according to claim 11, wherein the high temperature furnace heating time of the step (d) is about 20 to 80 minutes. 21. The method of manufacturing a Schottky diode according to claim 11, wherein the polysilicon ring of the step (e) has a width of about 18 to 50 micrometers. The method for manufacturing a Schottky diode according to the invention, wherein the first metal electrode is an anode of the Schottky diode. 23. The method of manufacturing a Schottky diode according to claim 11, wherein the second metal electrode is a cathode of the Schottky diode ohmic contact. 20