Schottky diode structure and electronic device

Abstract

This invention provides a Schottky diode structure and an electronic device. The structure includes a substrate and a first doped region formed therein. The first doped region includes a cathode active region and an anode active region. A second N-type doped region and a cathode metallization layer are sequentially formed within the cathode active region. The anode active region includes a first region and an anode metallization layer formed thereon. A metallization barrier layer is formed on the substrate surrounding the first region and at least covers a portion of the anode active region adjacent to the cathode active region. By providing a metallization barrier layer on the substrate between the cathode and anode of the Schottky diode and covering a portion of the anode active region, the electric field distribution at the edge of the Schottky barrier can be effectively optimized and surface leakage current can be suppressed. This effectively improves the reverse breakdown voltage without increasing the anode-cathode spacing or affecting the forward conduction performance, and saves device area and cost.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices, and more particularly to a Schottky diode structure and electronic device. Background Technology

[0002] With the rapid development of high-frequency switching power supplies, power management integrated circuits, automotive electronics, and consumer electronics, the market is placing increasingly stringent demands on the switching speed, conduction loss, integration density, and manufacturing cost of power rectifier devices. Schottky barrier diodes (SBDs), with their unique device structure and electrical performance, have become a core choice for medium- and low-voltage high-frequency power applications. These devices form a Schottky barrier through metal-semiconductor contact, classifying them as majority carrier conduction devices. They do not suffer from minority carrier storage hysteresis and possess key characteristics such as nanosecond-level ultrafast reverse recovery speed, extremely low forward voltage drop, small junction capacitance, and excellent high-frequency response.

[0003] However, existing Schottky diodes still have shortcomings such as limited reverse voltage withstand and large reverse leakage current, making it difficult to achieve a synergistic optimization of high voltage withstand and low conduction loss, and thus failing to fully meet the stringent operating conditions required by high-end automotive, industrial control and other scenarios.

[0004] In existing technologies, increasing the distance between the anode and cathode is commonly used to improve the reverse breakdown voltage. However, increasing the anode-cathode distance results in an excessively long electric field conduction path between the Schottky barrier region and the device edge, which easily leads to local electric field distortion, a surge in surface leakage current, and premature surface breakdown, thus lowering the reverse breakdown voltage threshold. Furthermore, this degradation effect is further exacerbated at high temperatures. Simultaneously, increasing the anode-cathode distance also causes a sharp increase in on-resistance, forward conduction loss, and forward voltage drop, completely negating the core advantage of low on-resistance Schottky devices and increasing the device area and cost.

[0005] Therefore, finding a suitable balance between low forward voltage drop and high reverse withstand voltage in Schottky diodes has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] In view of the above problems, the present invention provides a Schottky diode structure and electronic device to improve the reverse breakdown voltage of the Schottky diode without affecting its normal conduction performance.

[0007] According to a first aspect of the present invention, a Schottky diode structure is provided, comprising: A substrate having a first doped region formed therein; wherein the first doped region includes a cathode active region and an anode active region, and the cathode active region and the anode active region are isolated by a first isolation structure; The second N-type doped region is located within the cathode active region; A cathode metallization layer is located on the substrate and covers and contacts the second N-type doped region; A cathode metal electrode is located on the cathode metallization layer; An anode metallization layer is located on the substrate and covers a first region of the anode active region; a Schottky contact is formed between the anode metallization layer and the anode active region within the first region; An anode metal electrode is located on the anode metallide layer; A metallization barrier layer is located on the substrate surrounding the first region and at least covers the substrate surface between the first region and the first isolation structure; wherein the extent of the first region is smaller than the extent of the anode active region.

[0008] Optionally, the length of the portion of the metallization barrier layer covering the anode active region is greater than 0 nm and less than 50 nm.

[0009] Optionally, the first doped region further includes a second P-type doped region, which is located on the upper surface of the first doped region and at the edge of the anode active region.

[0010] Optionally, the metallization barrier layer also covers a portion of the first isolation structure.

[0011] Optionally, the length of the portion of the first isolation structure covered by the metallization barrier layer is greater than 0 nm and less than the width of the first isolation structure.

[0012] Optionally, the material of the metallization barrier layer is an oxide material or a nitride material.

[0013] Optionally, it further includes: a first N-type well region located within the cathode active region, wherein the second N-type doped region is located within the first N-type well region.

[0014] Optionally, the substrate is a P-type substrate, and the first doped region is an N-type deep well.

[0015] Optionally, the doping concentration of the second N-type doped region is greater than the doping concentration of the first N-type well region, and the doping concentration of the first N-type well region is greater than the doping concentration of the N-type deep well.

[0016] According to a second aspect of the present invention, an electronic device is also provided, the electronic device comprising the Schottky diode structure as described in the first aspect above.

[0017] The Schottky diode structure provided by this invention includes a substrate and a first doped region formed in the substrate; wherein the first doped region includes a cathode active region and an anode active region, and the cathode active region and the anode active region are isolated by a first isolation structure; a second N-type doped region is formed in the cathode active region and a cathode metallization layer is formed thereon; the anode active region includes a first region and an anode metallization layer formed thereon; a metallization barrier layer is formed on the substrate surrounding the first region, and at least covers a portion of the substrate region between the first region and the first isolation structure; wherein the range of the first region is smaller than the range of the anode active region, so that the metallization barrier layer covers a portion of the anode active region. By providing a metallization barrier layer on the substrate between the cathode and anode of the Schottky diode and covering a portion of the anode active region, the electric field distribution at the edge of the Schottky barrier can be effectively optimized and surface leakage current can be suppressed, thereby effectively improving the reverse breakdown voltage capability without increasing the anode-cathode spacing or affecting the forward conduction performance, and saving device area and cost. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the layout structure of a Schottky diode structure provided in an embodiment of the present invention; Figure 2 It corresponds Figure 1 A schematic diagram of the cross-sectional structure of section A-A'; Figure 3 This is a schematic cross-sectional view of a Schottky diode structure including a first N-type well region provided in an embodiment of the present invention; Figure 4 This is a schematic cross-sectional view of a Schottky diode structure including a second P-type doped region provided in an embodiment of the present invention; Figure 5 This is a cross-sectional schematic diagram of a Schottky diode structure including a first P-type well region provided in an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 101 - Substrate; 1021 - First isolation structure; 1022 - Second isolation structure; 103 - First doped region; 20 - Cathode active region; 201 - Second N-type doped region; 202 - Cathode metallization layer; 203 - Cathode metal electrode; 204 - First N-type well region; 30 - Anode active region; 301 - Zone 1; 302 - Anode metallization layer; 303 - Metallization barrier layer; 304 - Anode metal electrode; 305 - Second P-type doped region; 306 - First P-type well region. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] As described in the background section, existing technologies typically increase the reverse breakdown voltage of Schottky diodes by increasing the distance between the anode and cathode. However, increasing the anode-cathode distance can easily trigger surface breakdown prematurely, thus lowering the reverse breakdown voltage threshold. This leads to a sharp increase in on-resistance, increased forward conduction loss, and a significant increase in forward voltage drop, completely negating the core advantage of low conduction loss in Schottky devices. Furthermore, it increases the device area and cost. In view of this, the present invention provides a Schottky diode structure, which includes a substrate and a first doped region formed in the substrate; wherein the first doped region includes a cathode active region and an anode active region, and the cathode active region and the anode active region are isolated by a first isolation structure; a second N-type doped region is formed in the cathode active region and a cathode metallization layer is formed thereon; the anode active region includes a first region and an anode metallization layer formed thereon; a metallization barrier layer is formed on the substrate surrounding the first region, and at least covers a portion of the substrate region between the first region and the first isolation structure; wherein the range of the first region is smaller than the range of the anode active region, so that the metallization barrier layer covers a portion of the anode active region. By providing a metallization barrier layer on the substrate between the cathode and anode of the Schottky diode and covering a portion of the anode active region, the electric field distribution at the edge of the Schottky barrier can be effectively optimized and surface leakage current can be suppressed, thereby effectively improving the reverse breakdown voltage capability without increasing the anode-cathode spacing or affecting the forward conduction performance, and saving device area and cost. Example 1:

[0024] Please refer to Figures 1-3 An embodiment of the present invention provides a Schottky diode structure, which may include: a substrate 101, wherein a first doped region 103 is formed in the substrate 101.

[0025] The first doped region 103 may include a cathode active region 20 and an anode active region 30, and the cathode active region 20 and the anode active region 30 are isolated by a first isolation structure 1021.

[0026] As an example, the material of substrate 101 can be, for example, single-crystal silicon. Of course, the present invention is not limited to this, and other types of substrate materials, such as single-crystal germanium and single-crystal silicon carbide, are also within the scope of protection of the present invention.

[0027] In one specific implementation, the substrate 101 is, for example, a P-type substrate, and the first doped region 103 is, for example, an N-type deep well, and the type of the N-type deep well is, for example, a conventional voltage-domain N-type deep well (DNW).

[0028] In a preferred embodiment, the first doped region 103 can be, for example, a high-voltage domain N-type deep well (HVNW). Compared to DNW, HVNW has a lighter doping concentration and a thicker well layer, which can support a wider depletion layer extension. This allows the depletion layer of the Schottky diode structure to extend sufficiently in the longitudinal / lateral direction within the HVNW under reverse bias, effectively dispersing the electric field peak and preventing the local electric field from reaching the avalanche breakdown threshold prematurely, thereby improving the reverse breakdown voltage capability. At the same time, the more uniform doping distribution and wider depletion layer of HVNW can effectively suppress reverse leakage current at high temperatures, improving the reliability of the device.

[0029] As an example, the first isolation structure 1021 can be a field oxygen structure (LOCOS) or a shallow trench isolation structure (STI). Of course, the present invention is not limited to this, and other types of active region isolation structures are also within the protection scope of the present invention.

[0030] In one specific implementation, the first doped region 103 is isolated from adjacent devices by a second isolation structure 1022.

[0031] Specifically, the second isolation structure 1022 can be, for example, a field oxygen structure (LOCOS) or a shallow trench isolation structure (STI).

[0032] In this embodiment, please continue to refer to Figure 2 The Schottky diode structure may also include a second N-type doped region 201, a cathode metallization layer 202, and a cathode metal electrode 203.

[0033] The second N-type doped region 201 is located within the cathode active region 20.

[0034] In this embodiment, the cathode metallization layer 202 is located on the substrate 101, and covers and contacts the second N-type doped region 201.

[0035] In this embodiment, the cathode metal electrode 203 is located on the cathode metallization layer 202.

[0036] As an example, the cathode metallization layer may be a metal silicide layer or a metal germanide layer, depending on the type of substrate material, and the metal material forming the metallization may be, for example, cobalt, nickel, or titanium. Of course, this invention is not limited to these types, and other types of cathode metallization layer materials are also within the scope of this invention.

[0037] In one specific implementation, the cathode metallization layer forms an ohmic contact with the upper surface of the second N-type doped region 201 to reduce the contact resistance of the cathode, thereby reducing the forward conduction loss of the Schottky diode structure.

[0038] As a preferred embodiment, the Schottky diode structure provided by the present invention may further include: a first N-type well region 204 located within the cathode active region 20, and a second N-type doped region 201 located within the first N-type well region 204, such as... Figure 3 As shown.

[0039] The doping concentration of the second N-type doped region 201 is greater than that of the first N-type well region 204, and the doping concentration of the first N-type well region 204 is greater than that of the N-type deep well (first doped region 103).

[0040] In the above embodiments, by providing a first N-type well region 204 and a second N-type doped region 201 within the first N-type well region 204, and by providing a doping concentration gradient that gradually decreases from the second N-type doped region 201 to the first N-type well region 204 to the first doped region 103, the steep doping gradient from the high doping concentration of the second N-type doped region 201 (which is beneficial for reducing the ohmic contact resistance with the cathode metallization layer) to the low doping concentration of the N-type deep well can be avoided, thus reducing the series resistance during forward conduction and helping to reduce the forward conduction voltage drop. When the Schottky diode structure is reverse biased, the depletion layer is mainly located in the lightly doped first doped region 103 (N - Diffusion occurs within the drift region, while the first N-type well region 204 acts as a buffer layer, smoothing the electric field distribution and preventing diffusion between the heavily doped cathode (second N-type doped region 201) and the lightly doped N-type region. - The drift region directly contacts and generates electric field spikes, preventing premature breakdown in the bottom region of the cathode, thereby significantly improving the reverse breakdown capability.

[0041] As an example, the first N-type well region 204 can be a conventional N-type well (NW, medium doping concentration, shallow depth). As a preferred embodiment, the first N-type well region 204 can be an N-type drift well, where the lower doping concentration and deeper well depth can further effectively improve the reverse breakdown voltage capability.

[0042] In one embodiment, the Schottky diode structure may further include: an anode metallization layer 302 and an anode metal electrode 304.

[0043] The anode metallization layer 302 is located on the substrate 101 and covers the first region 301 in the anode active region 30; a Schottky contact is formed between the anode metallization layer 302 and the anode active region in the first region 301.

[0044] In this embodiment, the anode metal electrode 304 is located on the anode metallization layer 302.

[0045] As an example, the anode metallization layer may be a metal silicide layer or a metal germanide layer, depending on the type of substrate material, and the metal material forming the metallization may be, for example, cobalt, nickel, or titanium. Of course, this invention is not limited to these types, and other types of anode metallization layer materials are also within the scope of this invention.

[0046] As a specific implementation, the size of the first region 301 is determined according to the requirements of the forward conduction and reverse breakdown voltage characteristics of the Schottky diode. The larger the area of ​​the first region 301, the larger the forward conduction current, the smaller the forward voltage drop, and the correspondingly larger the reverse breakdown voltage. However, an excessively large area of ​​the first region 301 will also lead to an increase in the total reverse leakage current, increasing the power consumption of the device. The number of anode metal electrodes 304 can be set to a single metal electrode or an array of metal electrodes, depending on the size of the first region 301.

[0047] In one embodiment, the Schottky diode structure may further include: a metallization barrier layer 303 located on a substrate surrounding the first region 301, and covering at least a portion of the substrate region between the first region 301 and the first isolation structure 1021; wherein the range of the first region 301 is smaller than the range of the anode active region 30, such that the metallization barrier layer 303 covers a portion (L1) of the anode active region 30.

[0048] As an example, the metallization barrier layer 303 is made of an oxide material or a nitride material. Of course, this invention is not limited to this, and other types of materials for the metallization barrier layer 303 are also within the scope of protection of this invention.

[0049] In one specific implementation, a metallization barrier layer 303 surrounds the first region 301, and the length (L1) of the portion of the anode active region 30 covered by the metallization barrier layer 303 is greater than 0 nm and less than 50 nm.

[0050] By placing a metallization barrier layer on the substrate between the cathode and anode of a Schottky diode structure and covering a portion of the anode active region, the electric field distribution at the edge of the Schottky barrier can be effectively optimized without increasing the distance between the anode and cathode. This allows the electric field peak to shift from the barrier edge to the drift region (first doped region 103) below the portion of the anode active region covered by the metallization barrier layer (L1), preventing the local electric field from reaching the avalanche breakdown critical value prematurely, preferentially delaying avalanche breakdown, and improving the reverse breakdown voltage. Simultaneously, the metallization barrier layer covering a portion of the anode region forms a physical barrier layer, blocking external charges from reaching the anode. The interference of the surface electric field and the suppression of surface leakage current allow the depletion layer to diffuse more uniformly laterally within the first doped region, avoiding premature breakdown caused by surface electric field interference and leakage current, thus improving the withstand voltage stability at high temperatures. At the same time, by controlling the length (L1) of the metallide barrier layer covering the anode active region, the forward conduction characteristics of the Schottky diode structure are almost unaffected. Therefore, without affecting the forward conduction characteristics, area, and cost of the Schottky diode structure, the reverse withstand voltage and reliability of the Schottky diode are effectively improved. Moreover, no additional process steps are required; it can be achieved using conventional process frameworks and conditions, resulting in high process compatibility.

[0051] In a preferred embodiment, the metallization barrier layer 303 also covers a portion (L2) of the first isolation structure 1021.

[0052] As an example, the length (L2) of the portion of the first isolation structure 1021 covered by the metallide barrier layer 303 is greater than 0 nm and less than the width of the first isolation structure 1021. By using the metallide barrier layer 303 to cover a portion of the first isolation structure 1021, excess metallization due to process residues (such as silicon residue) on the surface of the first isolation structure 1021 can be effectively avoided, thus preventing surface leakage between the anode and cathode and ensuring that the forward voltage of the Schottky diode falls entirely in the anode region. Example 2:

[0053] As a preferred embodiment, such as Figure 4 As shown in the structural schematic diagram, the first doped region 103 may also include a second P-type doped region 305, which is located on the upper surface of the first doped region 103 and at the edge of the anode active region 30.

[0054] By setting a second P-type doped region 305 at the edge of the anode active region 30, when the Schottky diode structure is reverse biased, the second P-type doped region 305 and the lower first doped region 103 form a reverse-biased PN junction. Its depletion layer will extend to both sides, effectively blocking the tunneling and diffusion of thermally excited carriers at the metal-semiconductor interface, thereby significantly reducing the reverse leakage current. At the same time, the second P-type doped region 305 can disperse the electric field peaks at the edge of the Schottky barrier, transferring the electric field peaks to the drift region (first doped region 103), delaying the occurrence of avalanche breakdown, and improving the reverse breakdown voltage. In addition, when the Schottky diode structure is subjected to surge or overcurrent conditions, the PN junction formed by the second P-type doped region 305 and the lower first doped region 103 will conduct forward, providing an additional current path to shunt excessive forward current, thereby improving the Schottky diode structure's tolerance to transient overcurrent and ESD impact, and improving the reliability of the Schottky diode structure.

[0055] As a preferred embodiment, the Schottky diode structure provided by the present invention may further include: a first P-type well region 306 located within the first doped region 103, and a second P-type doped region 305 located within the first P-type well region 306, such as... Figure 5 As shown. The doping concentration of the second P-type doped region 305 is greater than that of the first P-type well region 306.

[0056] By setting a first P-type well region 306 and a second P-type doped region 305 located in the first P-type well region 306, and setting a doping concentration gradient that decreases from the second P-type doped region 305 to the first P-type well region 306, the first P-type well region 306 and the N-type drift region (first doped region 103) can form a deeper PN junction, and its depletion layer can be extended over a larger range, so that the electric field peak is transferred from the surface to a deeper level inside the drift region (first doped region 103), thereby further improving the reverse breakdown voltage capability and the device reliability in high-temperature scenarios.

[0057] As an example, the first P-type well region 306 can be a conventional P-type well (PW, medium doping concentration, shallow depth). In a preferred embodiment, the first P-type well region 306 can be a P-type drift well. The lower doping concentration and deeper well depth of the P-type drift well can further effectively improve the reverse breakdown voltage capability of the Schottky diode structure.

[0058] According to one embodiment of the present invention, an electronic device is also provided, which may include the aforementioned Schottky diode structure.

[0059] Those skilled in the art will understand that the embodiments provided by the present invention can be provided as methods, apparatus, or electronic devices. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Schottky diode structure, characterized in that, include: A substrate in which a first doped region is formed; wherein the first doped region includes a cathode active region and an anode active region, and the cathode active region and the anode active region are isolated by a first isolation structure; The second N-type doped region is located within the cathode active region; A cathode metallization layer is located on the substrate and covers and contacts the second N-type doped region; A cathode metal electrode is located on the cathode metallization layer; An anode metallization layer is located on the substrate and covers a first region of the anode active region; a Schottky contact is formed between the anode metallization layer and the anode active region within the first region; An anode metal electrode is located on the anode metallide layer; A metallization barrier layer is located on the substrate surrounding the first region and at least covers the substrate surface between the first region and the first isolation structure; wherein the extent of the first region is smaller than the extent of the anode active region.

2. The Schottky diode structure according to claim 1, characterized in that, The length of the portion of the anode active region covered by the metallization barrier layer is greater than 0 nm and less than 50 nm.

3. The Schottky diode structure according to claim 1, characterized in that, The first doped region also includes a second P-type doped region, which is located on the upper surface of the first doped region and at the edge of the anode active region.

4. The Schottky diode structure according to any one of claims 1-3, characterized in that, The metallization barrier layer also covers a portion of the first isolation structure.

5. The Schottky diode structure according to claim 4, characterized in that, The portion of the first isolation structure covered by the metallide barrier layer has a length greater than 0 nm and a width less than the width of the first isolation structure.

6. The Schottky diode structure according to claim 1, characterized in that, The metallization barrier layer is made of oxide or nitride materials.

7. The Schottky diode structure according to claim 1, characterized in that, Also includes: The first N-type well region is located within the cathode active region, and the second N-type doped region is located within the first N-type well region.

8. The Schottky diode structure according to claim 7, characterized in that, The substrate is a P-type substrate, and the first doped region is an N-type deep well.

9. The Schottky diode structure according to claim 8, characterized in that, The doping concentration of the second N-type doped region is greater than the doping concentration of the first N-type well region, and the doping concentration of the first N-type well region is greater than the doping concentration of the N-type deep well.

10. An electronic device, characterized in that, Includes the Schottky diode structure as described in any one of claims 1 to 9.

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