TWM561916U - Diode structure - Google Patents

Abstract

The present utility model provides a diode structure, characterized in that a deeper second concave portion is formed in a first concave portion in order to have at least two concave portions formed thereon having different depths, thereby reducing the electric field intensity of a reverse bias voltage junction and thus electric leakages. Further, the two concave portions having different depths are used in conjunction with the thickness of first and second insulating layers to adjust the reverse bias voltage multi-peak structure, thereby enhancing the performance of the diode structure in reverse resistance to collapse and thus the capability of resistance to lightning.

Description

Dipolar structure

This creation is about a diode structure, especially a Schottky diode.

The Schottky diode system is a diode with a low turn-on voltage drop and allows high-speed switching. Its turn-on voltage is extremely low, which can improve the efficiency of electronic products such as power supplies. Currently, the trench Schottky two-pole system achieves a low forward voltage (VF) by designing a trench to reduce the impedance of the wafer used in the same voltage performance as a conventional planar Schottky.

1A to 1E are schematic cross-sectional views showing a conventional method of manufacturing a trench type Schottky diode 1 having a recess 100.

As shown in FIG. 1A, at least one recess 100 is formed on the surface 10a of one of the diode bodies 10 by using a patterned mask (not shown).

As shown in FIG. 1B, after the photomask is removed, a ceria layer (SiO ₂ ) 11 is formed on the surface 10a of the dipole body 10 along the wall surface 100a and the bottom surface 100b of the recess 100.

As shown in FIG. 1C, a polysilicon layer 12 is formed on the ceria layer 11.

Removing the surface 10a of the diode body 10 as shown in FIG. 1D The ruthenium dioxide layer 11 and the polysilicon layer 12 retain only the ruthenium dioxide layer 11 and the polysilicon layer 12 in the recess 100.

As shown in FIG. 1E, a Schottky metal layer 15 is formed on the surface 10a of the diode body 10, the ceria layer 11 and the polysilicon layer 12 to complete the trench metal oxide semiconductor Schottky (Trench MOS). Barrier Schottky, referred to as TMBS) diode 1.

However, in the conventional grooved Schottky diode 1 , since the depth of the recessed portion 100 is insufficient (the groove depth of the grooved Schottky product process is about 1 to 5 um), the Schottky cannot be effectively reduced. The reverse phase uses the electric field strength of the metal and the junction surface, so the strength of the reverse surface electric field will cause an effective barrier reduction (Barrier Lowering) and an increase in leakage.

Therefore, how to overcome the problems of the above-mentioned prior art has become a problem that is currently being solved.

In view of the above-mentioned various deficiencies of the prior art, the present invention provides a diode structure comprising: a diode body having a first recess formed on a surface thereof; and a first insulating layer formed on a wall surface of the first recess a first conductive layer is formed on the first insulating layer, and a first opening is formed on the first insulating layer and the first conductive layer, so that a part of the bottom surface of the first concave portion is exposed to the first surface Opening, the first recess is exposed on the bottom surface of the first opening to form a second opening, the first opening and the second opening are used as a second recess; and the second insulating layer is formed on the wall surface of the second recess And a bottom surface; and a second conductor layer formed on the second insulating layer.

It should be understood that the third recess or more can be continued in the same procedure. The fabrication of the multi-recesses, the number of recesses is defined by the size of the first recess opening and the parameters of the process.

The present invention also provides a method for fabricating a diode structure, comprising: forming a first recess on a surface of the body of the diode, and forming a first insulating layer along a wall surface and a bottom surface of the first recess; and the first insulating layer Forming a first conductive layer thereon; forming a first opening on the first insulating layer and the first conductive layer to expose a portion of the bottom surface of the first recess to the first opening; and exposing the first recess to the first opening Forming a second opening on a bottom surface of an opening such that the first opening and the second opening serve as a second recess; forming a second insulating layer along a wall surface and a bottom surface of the second recess; and forming a second layer on the second insulating layer Two conductor layers.

It should be understood that the fabrication of the third recess or more recesses can be continued in the same procedure.

In the foregoing diode structure and its manufacturing method, the diode structure is a Schottky diode.

In the foregoing diode structure and the method of manufacturing the same, the thickness of the first insulating layer is smaller than the thickness of the second insulating layer. It should be understood that the thickness of the second insulating layer may be less than the thickness of the third insulating layer, and so on.

In the foregoing diode structure and the method of manufacturing the same, the diode system is a semiconductor material.

In the foregoing diode structure and the method of manufacturing the same, the first insulating layer is a dielectric material such as cerium oxide or tantalum nitride.

In the foregoing diode structure and the method of manufacturing the same, the second insulating layer is a dielectric material such as ceria or tantalum nitride.

In the foregoing diode structure and the method of manufacturing the same, the first conductor layer is a conductive material such as a polysilicon or a metal material.

In the foregoing diode structure and the method of manufacturing the same, the second conductor layer is a conductive material such as a polysilicon or a metal material.

In the foregoing diode structure and method of manufacturing the same, the method further includes forming a metal layer on the surface of the diode body, the first and second insulating layers, and the first and second conductor layers. For example, the metal layer is a Schottky metal such as a titanium material.

It can be seen from the above that the diode structure of the present invention and its manufacturing method mainly form a second concave portion by autonomously aligning in the first concave portion to generate first and second concave portions having different depths, and thus in the reverse direction The internal electric field strength of the created diode structure is redistributed and the surface electric field can be reduced. Therefore, compared with the conventional technology, the method of the present invention can further reduce leakage.

In addition, by adjusting the thickness of the two recesses and the thickness of the first and second insulating layers, the tangential line of the electric field distribution under the reverse bias is multi-peak structure, and the reverse breakdown voltage performance of the fabricated diode under the same raw material is improved.

Moreover, since the diode enters the reverse surge (lightning strike) energy, the energy is converted into a product of the current and the breakdown voltage and time at the breakdown voltage (E=Pxt=VxIxt), and the excessive current passes through the pole. The reason for the substantial destruction of the microstructure in the body is that the current is absolutely related to the thickness of the raw material impedance. Therefore, in the case of components with the same raw materials facing the same surge (lightning strike) current, the higher component breakdown voltage can further improve the performance of the lightning strike capability of the reverse surge (lightning strike) of the diode original.

1‧‧‧Schottky diode

10,20‧‧‧dipole body

10a, 20a‧‧‧ surface

100‧‧‧ recess

100a, 201a, 202a‧‧‧ wall

100b, 201b, 202b‧‧‧ bottom

11‧‧‧ cerium oxide layer

12‧‧‧Polysilicon layer

15‧‧‧Schottky metal layer

2‧‧‧Diode structure

20b‧‧‧Isolation

201‧‧‧First recess

202‧‧‧Second recess

21‧‧‧First insulation

22‧‧‧First conductor layer

23‧‧‧Second insulation

24‧‧‧Second conductor layer

25‧‧‧metal layer

W1, W2‧‧‧ width

t,t’,d,d’‧‧‧ thickness

A‧‧‧first opening

B‧‧‧second opening

C1, C2, C3‧‧‧ curves

D, E‧‧‧ electric field curve

F1, F2‧‧‧ electric field

G1, G2‧‧‧ voltage

H1, H2‧‧‧ leakage current

Figures 1A to 1E are schematic cross-sectional views of a conventional diode structure Figure 2A to 2F is a schematic cross-sectional view of the manufacturing method of the diode structure of the creation; Figure 3 is the IV curve of the created diode structure and the conventional grooved Schottky diode. Fig. 4A is an electric field distribution diagram of a conventional trench Schottky diode under reverse bias; and Fig. 4B is an electric field distribution of a diode structure under reverse bias Figure 5A is a tangential diagram of the electric field distribution of a conventional trench Schottky diode under reverse bias; Figure 5B is the electric field of the created diode structure under reverse bias. Distribution tangential diagram, which has a characteristic bimodal structure, and the number of tangential peaks of the electric field is determined by the number of equal recesses; the 5C diagram is the reverse bias of the created diode structure and the conventional Schottky diode. The electric field distribution tangential alignment diagram; the 6A diagram is the electric field distribution comparison diagram of the two embodiments of the created diode structure under the same reverse bias; the 6B diagram is the second pole of the creation The tangential alignment diagram of the electric field distribution of the two embodiments of the bulk structure under the same reverse bias; the 6C diagram is the two realities of the diode structure of the present invention. Than the breakdown voltage versus the embodiment; FIG. 6D and a second graph based on the ratio of the drain behavior of the embodiment of the two kinds of diode structure of the present embodiment Creation.

The embodiments of the present invention are described below by way of specific embodiments, and those skilled in the art can readily appreciate other advantages and functions of the present invention from the disclosure of the present disclosure.

It is to be understood that the structure, the proportions, the size and the like of the drawings are only used in conjunction with the disclosure of the specification for the understanding and reading of those skilled in the art, and are not intended to limit the implementation of the present invention. The conditions are limited, so it is not technically meaningful. Any modification of the structure, change of the proportional relationship or adjustment of the size should remain in this book without affecting the effectiveness and the purpose of the creation. The technical content revealed by the creation can be covered. In the meantime, the terms “upper”, “first”, “second”, “one” and “the” are used in this specification for the convenience of description, and are not intended to limit the scope of the creation. Changes or adjustments in their relative relationship are considered to be within the scope of the creation of the creation of the product without substantial changes.

2A to 2F are schematic cross-sectional views showing the manufacturing method of the diode structure 2 of the present invention. In this embodiment, the diode structure 2 is a Schottky diode.

As shown in FIG. 2A, a first recess 201 is formed on the surface 20a of a diode body 20 by using a patterned mask (not shown), and after the mask is removed, the diode body 20 is A first insulating layer 21 is formed on the surface 20a along the wall surface 201a and the bottom surface 201b of the first recess 201, and a first conductor layer 22 is formed on the first insulating layer 21.

In this embodiment, the diode body 20 is a semiconductor material, such as silicon, and the first insulating layer 21 is a dielectric layer, such as a cerium oxide (SiO ₂ ) material, and the first The conductor layer 22 is a polysilicon material.

Furthermore, the material of the diode body 20 can be removed by laser, etching or other suitable means to form the first recess 201, and the first insulating layer 21 can be formed by coating or other suitable manner. First conductor layer 22.

Moreover, the isolation layer 20b is selectively formed on the surface 20a of the diode body 20.

As shown in FIG. 2B, a portion of the first insulating layer 21 and the first conductive layer 22 on the surface 20a of the diode body 20 are removed, and the first insulating layer on the bottom surface 201b of the first recess 201 is removed. 21 and the first conductor layer 22 to form a first opening A on the first insulating layer 21 and the first conductor layer 22 such that a portion of the bottom surface 201b of the first recess 201 is exposed to the first opening A.

In this embodiment, the first insulating layer 21 and the first conductive layer 22 may be removed by laser, etching or other suitable means.

As shown in FIG. 2C, the first insulating layer 21 and the first conductive layer 22 are used as a photomask, and the first recess 201 is exposed on the bottom surface 201b of the first opening A to form a second opening B. The first opening A and the second opening B are used as the second recess 202.

In this embodiment, the material of the diode body 20 (ie, the bottom surface 201b of the first recess 201) may be removed by laser, etching or other suitable means to form the second recess 202.

Moreover, it should be understood that the width W1 of the first concave portion 201 is greater than the width W2 of the second concave portion 202, so that the second concave portion 202 is located at the first In a recess 201.

It should be understood that the fabrication of the third recess or more recess structures can be performed in the same manner.

As shown in FIG. 2D, a second insulating layer 23 is formed on the surface 20a of the diode body 20 along the wall surface 202a and the bottom surface 202b of the first insulating layer 21, the first conductor layer 22, and the second recess 202. A second conductor layer 24 is formed on the second insulating layer 23.

In this embodiment, the second insulating layer 23 is a dielectric layer, such as a cerium oxide material, and the second conductive layer 24 is a polycrystalline bismuth material.

Furthermore, the second insulating layer 23 and the second conductor layer 24 are formed by coating or other suitable means.

As shown in FIG. 2E, the second insulating layer 23 and the second conductive layer 24 on the surface 20a of the diode body 20, above the first insulating layer 21 and above the first conductor layer 22 are removed. Only the second insulating layer 23 and the second conductor layer 24 in the second recess 202 are retained.

In this embodiment, the thickness t of the first insulating layer 21 in the lateral direction is smaller than the thickness d of the second insulating layer 23 in the lateral direction, and the thickness t' of the first insulating layer 21 in the longitudinal direction is smaller than the second insulating layer 23 The thickness d' in the longitudinal direction.

As shown in FIG. 2F, the isolation layer 20b is removed, and a metal layer 25 is formed on the surface 20a of the diode body 20, the first and second insulating layers 21, 23, and the first and second conductor layers 22, 24 on. In the present embodiment, the metal layer 25 is made of titanium or other metal.

In this embodiment, the material of the isolation layer 20b may also be a common insulating material for the process, such as a cerium oxide material. By thickness and different insulation layers The control of the process can remove the isolation layer 20b while the second insulating layer 23 is removed.

Therefore, the method of the present invention is to form the second concave portion 202 by autonomously aligning the first concave portion 201 to produce first and second concave portions 201, 202 (or more concave portions) having different depths. Therefore, in the case of applying a reverse bias, the electric field intensity of the diode body 20 is redistributed and the surface electric field can be reduced. Therefore, compared with the prior art, the method of the present invention can further reduce leakage, that is, A diode structure 2 with ultra-low leakage performance is produced.

Furthermore, the method of the creation of this creation uses the autonomous orientation to produce different shades of recesses. Therefore, compared with the conventional technique, the number of masks used in the creation method of this creation is the same, and thus the production cost is not increased.

Fig. 3 is a reverse IV (current-voltage) graph of the diode structure 2 of the present invention and the conventional trench Schottky diode 1. As shown in FIG. 3, the position of the curve C1 of the diode structure 2 of the present invention is higher than the position of the curve C3 of the conventional trench Schottky diode 1, wherein the X axis represents a reverse voltage, The unit is volts (V) and the Y-axis represents current density in amps/area (A/um ² ). In this embodiment, the thickness t, t' of the first insulating layer 21 of the diode structure 2 of the present invention can be reduced by 0.05 micrometers (μm), so that the position of the curve C2 is slightly lower than the original curve C1 of the present creation. The position is still higher than the position of the curve C3 of the conventional grooved Schottky diode 1 .

4A is a distribution diagram of the electric field under the reverse bias of the conventional Schottky diode 1 , and FIG. 4B is a map of the electric field under the reverse bias of the diode structure 2 of the present invention, wherein The X axis represents the width in microns (um) and the Y axis represents the length in microns (um). Like 4A and 4B As shown in the figure, the surface electric field of the diode structure 2 of the present invention is lower than that of the conventional trench type Schottky diode 1 , so the diode structure 2 of the present invention effectively reduces the leakage.

Figure 5A is a tangential diagram of the electric field distribution under the reverse bias of the conventional trench Schottky diode 1 and Fig. 5B is the electric field distribution under the reverse bias of the diode structure 2 of the present invention. A tangential diagram in which the X-axis represents a tangent position in the Y direction, the unit is in micrometers (um), and the Y-axis represents electric field strength, the unit of which is in volts/cm (V/cm).

As shown in FIGS. 5A and 5B, the electric field distribution tangent D of the conventional trench type Schottky diode 1 under reverse bias shows that the electric field at the contact surface of the metal and the semiconductor material (X=0) is obvious. The electric field curve E of the diode structure 2 of the present invention is higher, and the electric field at the contact surface of the metal and the semiconductor material is significantly lower.

In the present embodiment, as shown in FIG. 5C, after the two electric field curves D and E are overlapped, the electric field distribution tangent E under the reverse bias of the diode structure 2 of the present invention can be specifically shown in the metal and the semiconductor. The electric field at the contact surface of the material is lower than the electric field curve D of the conventional trench Schottky diode 1 at the contact surface between the metal and the semiconductor material. Therefore, the diode structure 2 of the present invention effectively reduces the effectiveness of the Schottky. Barrier Lowering and leakage.

Specifically, from the electrical simulation of 100 volt (V) grains, the leakage density of the conventional trench Schottky diode 1 is 5.75 based on the use of identical semiconductor material epitaxy materials. (E-12A/μm ² ), and the leakage density of the diode structure 2 of the present invention is 1.56 (E-12A/μm ² ), that is, the creation is reduced by about 3 times, and the diode structure 2 of the present invention is based on In this leakage reduction mode, the power consumption reversed at the same use temperature is one-third that of the conventional trench Schottky diode 1. Therefore, under the same heat dissipation conditions, the diode structure 2 of the present invention can raise the safe operable temperature range by about 10 to 15 ° C compared with the conventional grooved Schottky diode 1 and can be used on the same raw materials. Further increase in voltage results in savings in raw materials and can increase efficiency.

6A to 6D are alignment diagrams of two embodiments of the created diode structure, wherein the first embodiment is the created diode structure 2, and the second embodiment is the first The thickness t, t' of the insulating layer 21 is reduced by 0.05 μm.

As shown in Fig. 6A, the electric field distribution ratio map under reverse bias is different from the electric field distribution portion under the reverse bias of the first and second embodiments of the present invention, wherein the X axis represents the width and the unit is micron. (um), the Y axis represents the length, and its unit is micron (um).

As shown in FIG. 6B, the electric field tangential alignment diagram under reverse bias, the electric field F1 at the metal-semiconductor contact surface of the first embodiment is slightly higher than the electric field F2 at the metal-semiconductor contact surface of the second embodiment, Wherein, the X axis represents a tangent position along the Y direction, the unit is micrometer (um), and the Y axis represents electric field strength, and the unit is volts/cm (V/cm).

As shown in FIG. 6C, the voltage G2 of the second embodiment is slightly lower than the voltage G1 of the first embodiment, because the thickness of the first insulating layer 21 of the second embodiment is relatively thin. The X axis represents the reverse bias voltage in volts (V) and the Y axis represents the current density in amps/area (A/um ² ).

As shown in FIG. 6D, the leakage behavior of the reverse bias is shown in FIG. 6D. When the voltage is 25 to 70 volts, the leakage current H2 of the second embodiment is lower than the leakage current H1 of the first embodiment, wherein X The axis represents the reverse bias voltage in volts (V) and the Y axis represents the current density in amps/area (A/um ² ).

In summary, the diode structure of the present invention is formed by abutting a second recess in the first recess to create first and second recesses of different depths, with different thicknesses. The first and second insulating layers can thereby reduce the electric field strength of the metal-semiconductor contact surface. Therefore, the diode structure and the method of the same can improve the pressure resistance of the product and reduce the leakage performance under reverse bias.

The above embodiments are intended to illustrate the principles of the present invention and its effects, and are not intended to limit the present invention. Anyone who is familiar with the art may modify the above embodiments without departing from the spirit and scope of the creation. Therefore, the scope of protection of this creation should be as listed in the scope of patent application described later.

Claims (10)

A diode structure includes: a diode body having a first recess formed on a surface thereof; a first insulating layer formed on a wall surface and a bottom surface of the first recess; a first conductor layer formed on the body Forming a first opening on the first insulating layer and the first insulating layer, and exposing a portion of the bottom surface of the first recess to the first opening, so that the first recess is exposed to the first opening a second opening is formed on a bottom surface of an opening, the first opening and the second opening are formed as a second recess; a second insulating layer is formed on the wall surface and the bottom surface of the second recess; and the second conductor layer is Formed on the second insulating layer. The diode structure of claim 1, wherein the diode structure is a Schottky diode. The diode structure of claim 1, wherein the first insulating layer has a thickness smaller than a thickness of the second insulating layer. The diode structure according to claim 1, wherein the diode system is a semiconductor material. The diode structure of claim 1, wherein the first insulating layer is cerium oxide or tantalum nitride. The diode structure of claim 1, wherein the second insulating layer is cerium oxide or tantalum nitride. Such as the diode structure described in claim 1, wherein the A conductor layer is a polycrystalline tantalum or metal. The diode structure of claim 1, wherein the second conductor layer is a polycrystalline tantalum or a metal. The diode structure according to claim 1, wherein the metal layer is formed on the surface of the diode body, the first and second insulating layers, and the first and second conductor layers. The diode structure of claim 9, wherein the metal layer is a titanium material or a Schottky metal.