CN103579372A - Schottky barrier diode and manufacturing method thereof - Google Patents

Abstract

The invention provides a Schottky Barrier Diode (SBD) and a manufacturing method thereof. A schottky barrier diode formed on a substrate, comprising: a gallium nitride (GaN) layer formed on the substrate; an aluminum gallium nitride (AlGaN) layer formed on the GaN layer; an insulating layer formed on the AlGaN layer; an anode conducting layer formed on the insulating layer, wherein a part of the anode conducting layer is in Schottky contact with the GaN layer or the AlGaN layer, and the other part of the anode conducting layer is separated from the AlGaN layer by the insulating layer; and a cathode conductive layer formed on the AlGaN layer and forming ohmic contact with the AlGaN layer, wherein the cathode conductive layer is not directly connected with the anode conductive layer.

Description

Schottky barrier diode and manufacturing method thereof

technical field

The present invention relates to a Schottky barrier diode (Schottky barrier diode, SBD) and its manufacturing method, in particular to an SBD with reduced leakage current and its manufacturing method.

Background technique

1 shows a prior art Schottky barrier diode (SBD) 100, formed on a silicon substrate 11, comprising a gallium nitride (GaN) layer, an aluminum gallium nitride (AlGaN) layer, an anode conductive layer 14, and Cathode conductive layer 15 . SBD is a semiconductor element. Compared with the p-n junction diode, it uses the Schottky barrier (Schottky barrier) generated by the Schottky contact between the metal and the semiconductor, which makes the forward current larger during operation. And the response time is short. However, when the SBD is operated under the reverse bias voltage, a large leakage current will be generated, resulting in loss of electric energy.

In view of this, the present invention aims at the above-mentioned deficiencies in the prior art, and proposes a Schottky barrier diode and a manufacturing method thereof, so that when the Schottky barrier diode is in operation, the leakage current is reduced to reduce the Schottky barrier diode. Power loss during diode operation.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies and defects of the prior art, and propose a Schottky barrier diode and a manufacturing method thereof.

In order to achieve the above object, in terms of one of the viewpoints, the present invention provides a Schottky barrier diode formed on a substrate, comprising: a gallium nitride (gallium nitride, GaN) layer formed on the substrate; An aluminum gallium nitride (aluminum gallium nitride, AlGaN) layer formed on the GaN layer; an insulating layer formed on the AlGaN layer; an anode conductive layer formed on the insulating layer, and part of the anode conductive layer A Schottky contact is formed with the GaN layer or the AlGaN layer, and another part of the anode conductive layer is separated from the AlGaN layer by the insulating layer; and a cathode conductive layer is formed on the AlGaN layer and is connected with the AlGaN layer. An ohmic contact is formed between the AlGaN layers, and the cathode conductive layer is not directly connected to the anode conductive layer.

From another point of view, the present invention also provides a Schottky barrier diode manufacturing method, comprising: forming a gallium nitride (gallium nitride, GaN) layer on a substrate; forming an aluminum gallium nitride (aluminum gallium Nitride, AlGaN) layer on the GaN layer; form an insulating layer on the AlGaN layer; form an anode conductive layer on the insulating layer, and part of the anode conductive layer and the GaN layer or the AlGaN layer form a Schott base contact, and another part of the anode conductive layer is separated from the AlGaN layer by the insulating layer; and a cathode conductive layer is formed on the AlGaN layer, and forms an ohmic contact with the AlGaN layer, and the cathode The conductive layer is not directly connected to the anode conductive layer.

In one of the preferred implementation forms, the insulating layer is in a grid shape viewed from a plan view, and is formed between the anode conductive layer and the GaN layer or the AlGaN layer.

In another preferred embodiment, the substrate includes an insulating substrate or a conductive substrate.

In yet another preferred implementation form, the thickness of the insulating layer is less than 1 micron (um).

In another preferred embodiment, the insulating layer has a dielectric constant higher than 3.9.

The following will be described in detail through specific embodiments, so that it is easier to understand the purpose, technical content, characteristics and effects of the present invention.

Description of drawings

Figure 1 shows a prior art Schottky barrier diode (SBD) 100;

Figure 2 shows a first embodiment of the present invention;

Figure 3 shows a second embodiment of the present invention;

4A-4C show a third embodiment of the present invention;

Figure 5 shows a fourth embodiment of the present invention;

6A-6B show plots of anodic current versus anode voltage for prior art SBDs (FIG. 6A) and SBDs utilizing the present invention (FIG. 6B);

7A-7B show the cross-sectional two-dimensional electric field simulation characteristic diagrams of the prior art SBD (FIG. 7A) and the SBD using the present invention (FIG. 7B);

Figures 8A-8B show the electric field simulation characteristic diagrams of the prior art SBD (Figure 8A) and the SBD using the present invention (Figure 8B) in the vertical direction of the anode edge;

9A-9B show the electric field simulation characteristic diagrams of the prior art SBD (FIG. 9A) and the SBD using the present invention (FIG. 9B) in the transverse direction of the channel.

Explanation of symbols in the figure

11,21 Substrate

12,22 GaN layers

13,23 AlGaN layer

14,24,34 anode conductive layer

15,25,35 Cathode conductive layer

26 insulation layer

100,200,300,400 Schottky barrier diodes

Et,Ep Anode edge electric field

Detailed ways

The drawings in the present invention are all schematic, mainly intended to represent the manufacturing process steps and the upper and lower sequence relationship between each layer, as for the shape, thickness and width, they are not drawn to scale.

Figure 2 shows a first embodiment of the invention. As shown in FIG. 2 , the SBD 200 is, for example, formed on a substrate 21 , and the substrate 21 is, for example but not limited to, an insulating substrate or a conductive substrate such as a silicon substrate, a silicon carbide substrate, or a sapphire substrate. And on the substrate 21 , for example but not limited to, a gallium nitride (GaN) layer 22 is formed by epitaxial technology. In addition to the GaN layer 22 , the SBD 200 also includes an aluminum gallium nitride (AlGaN) layer 23 , an insulating layer 24 , an anode conductive layer 25 , and a cathode conductive layer 26 . Among them, the AlGaN layer 23 is formed on the GaN layer 22; the insulating layer 24 is formed on the AlGaN layer 23; the anode conductive layer 25 is formed on the insulating layer 24, and a part of the A anode conductive layer 25 and the AlGaN layer 24 form a Schottky contact, and another part of the B anode conductive layer 25 is separated from the AlGaN layer 23 by an insulating layer 24; the cathode conductive layer 26 is formed on the AlGaN layer 23, and forms an ohmic contact with the AlGaN layer 23, and the cathode conductive layer 26 is not directly connected to the anode conductive layer 25.

The difference between this embodiment and the prior art is that the insulating layer 24 is used to form a multi-electric field plate, and the Schottky barrier between the anode metal layer 25 and the AlGaN layer 23 is adjusted to improve the SBD when it is not conducting. breakdown voltage.

Fig. 3 shows a second embodiment of the present invention. This embodiment shows a schematic cross-sectional view of an SBD300 applying the present invention. Different from the first embodiment, part of the anode conductive layer 35 in this embodiment forms a Schottky contact with the GaN layer 22 instead of the AlGaN layer 23 .

Please refer to FIGS. 4A-4C , which show a schematic cross-sectional view of the manufacturing process of the SBD 200 according to the third embodiment of the present invention. As shown in FIG. 4A , on the substrate 21 , a GaN layer 22 is formed on the substrate 21 . The substrate 21 can be a non-conductive insulating substrate, such as but not limited to a sapphire substrate, or a conductive substrate, such as but not limited to a silicon carbide (SiC) substrate. Then an AlGaN layer 23 is formed on the GaN layer 22 .

Then, as shown in FIG. 4B , an insulating layer 24 is formed on the AlGaN layer 23 . The insulating layer 24 is made of, for example but not limited to, high dielectric material, and its dielectric constant is higher than 3.9 of silicon dioxide.

Next, as shown in FIG. 4C , an anode conductive layer 25 is formed on the insulating layer 24 ; and a cathode conductive layer 26 is formed on the AlGaN layer 23 . Among them, part of the anode conductive layer 25 and the AlGaN layer 23 form a Schottky contact, and another part of the anode conductive layer 25 and the AlGaN layer 23 are separated by an insulating layer 24; and the cathode conductive layer 26 and the AlGaN23 layer form an ohmic contact. Ohmic contact, and the cathode conductive layer 26 is not directly connected to the anode conductive layer 25.

Fig. 5 shows a fourth embodiment of the present invention. This embodiment shows a schematic cross-sectional view of an SBD400 applying the present invention. Different from the first embodiment, the insulating layer 34 of this embodiment is viewed as a grid from a plan view (not shown), and is formed between the anode conductive layer 25 and the GaN layer 22 or the AlGaN layer 23 .

Please refer to Figures 6A-6B, which show the characteristic diagrams of the anode current to the anode voltage of the SBD of the prior art and the SBD of the present invention, as shown in Figures 6A-6B, compared with the prior art SBD, the SBD of the present invention is used in Under the same anode voltage, the anode current is larger, indicating that the SBD of the present invention has better conduction characteristics.

Please refer to Figures 7A-7B, which show the two-dimensional electric field simulation characteristic diagrams of the cross-section of the prior art SBD and the SBD utilizing the present invention, as shown in Figure 6A-6B, compared with the SBD of the prior art, the SBD of the present invention is utilized Under the same operating voltage, the electric field at the edge of the anode is dispersed into two peaks, and the peak value is lower, which means that the electric field is relieved by using the SBD of the present invention, thereby increasing the breakdown voltage.

Please refer to Figures 8A-8B, which show the electric field simulation characteristic diagrams of the prior art SBD and the SBD using the present invention in the vertical direction of the anode edge, as shown in Figures 8A-8B, compared with the prior art SBD, using the present invention Under the same operating voltage of the SBD, the electric field at the edge of the anode is lower, which means that the electric field is relieved by using the SBD of the present invention, thereby increasing the breakdown voltage.

Please refer to Figures 9A-9B, which show the electric field simulation characteristic diagrams of the SBD of the prior art and the SBD of the present invention in the lateral direction of the channel, as shown in Figures 9A-9B, compared with the SBD of the prior art, the SBD of the present invention is used Under the same operating voltage, the electric field at the edge of the anode is lower, that is, Ep<Et, which means that the electric field is relaxed by using the SBD of the present invention, thereby increasing the breakdown voltage.

It should be noted that the thickness of the insulating layer applied to the SBD of the present invention is less than 1 micron (um), and a more preferred embodiment is less than 0.1 micron (um). It means that the insulating layer is used to change the work function of the anode conductive layer, instead of directly using a thicker insulating layer to isolate the electric field and weaken it.

The present invention has been described above with reference to preferred embodiments, but the above description is only for those skilled in the art to easily understand the content of the present invention, and is not intended to limit the scope of rights of the present invention. Under the same spirit of the present invention, various equivalent changes can be conceived by those skilled in the art. For example, without affecting the main characteristics of the device, other process steps or structures can be added, such as defining and etching the ohmic contact area before the cathode position of the SBD before forming the cathode conductive layer. The scope of the present invention is intended to cover the above and all other equivalent variations.

Claims (10)

1. a Schottky potential barrier diode, is formed on a substrate, it is characterized in that, comprises:

One gallium nitride layer, is formed on this substrate;

One aluminium gallium nitride alloy layer, is formed on this gallium nitride layer;

One insulating barrier, is formed on this aluminium gallium nitride alloy layer;

One anode conductive layer, is formed on this insulating barrier, and this anode conductive layer of part and this gallium nitride layer or this aluminium gallium nitride alloy layer, forms Schottky contacts, and this anode conductive layer of another part and this aluminium gallium nitride alloy interlayer, by this insulating barrier, is separated; And

One cathode conductive layer, is formed on this aluminium gallium nitride alloy layer, and with this aluminium gallium nitride alloy layer or this aluminium gallium nitride alloy interlayer, form an ohmic contact, and this cathode conductive layer is not directly connected with this anode conductive layer.

2. Schottky potential barrier diode as claimed in claim 1, wherein, what this insulating barrier was looked by vertical view is trellis, is formed between this anode conductive layer and this gallium nitride layer or this aluminium gallium nitride alloy layer.

3. Schottky potential barrier diode as claimed in claim 1, wherein, this substrate comprises an insulated substrate or a conductor substrate.

4. Schottky potential barrier diode as claimed in claim 1, wherein, this thickness of insulating layer is less than 1 micron.

5. Schottky potential barrier diode as claimed in claim 1, wherein, this insulating barrier has one higher than 3.9 dielectric constant.

6. a Schottky potential barrier diode fabricating method, is characterized in that, comprises:

Form a gallium nitride layer on a substrate;

Form an aluminium gallium nitride alloy layer on this gallium nitride layer;

Form an insulating barrier on this aluminium gallium nitride alloy layer;

Form an anode conductive layer on this insulating barrier, and this anode conductive layer of part and this gallium nitride layer or this aluminium gallium nitride alloy layer, form Schottky contacts, and this anode conductive layer of another part and this aluminium gallium nitride alloy interlayer, by this insulating barrier, separated; And

Form a cathode conductive layer on this aluminium gallium nitride alloy layer, and with this aluminium gallium nitride alloy layer or this aluminium gallium nitride alloy interlayer, form an ohmic contact, and this cathode conductive layer is not directly connected with this anode conductive layer.

7. Schottky potential barrier diode fabricating method as claimed in claim 6, wherein, what this insulating barrier was looked by vertical view is trellis, is formed between this anode conductive layer and this gallium nitride layer or this aluminium gallium nitride alloy layer.

8. Schottky potential barrier diode fabricating method as claimed in claim 6, wherein, this substrate comprises an insulated substrate or a conductor substrate.

9. Schottky potential barrier diode fabricating method as claimed in claim 6, wherein, this thickness of insulating layer is less than 1 micron.

10. Schottky potential barrier diode fabricating method as claimed in claim 6, wherein, this insulating barrier has one higher than 3.9 dielectric constant.

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