CN103579307A - Novel diode component structure - Google Patents

Abstract

The invention discloses a novel diode device structure; the diode device structure of the present invention is composed of a channel and a drift region; Reverse current; when the diode device is forward biased, the potential barrier in the channel is reduced simultaneously, allowing the current to pass through, and the adjustable channel parameters realize a relatively low turn-on voltage; the present invention is applicable to the vertical Structural Diode Devices.

Description

A new type of diode device

technical field

The invention relates to the technical field of power electronics, and relates to electrical equipment in almost all application occasions, including a novel diode device in the fields of AC motors, frequency converters, switching power supplies, traction drives and the like.

Background technique

As an important power semiconductor device, diode devices mainly include two types based on PN junction barrier and Schottky barrier. The PN junction barrier has a relatively high barrier height, low reverse leakage current, but high forward conduction voltage drop, and there is a problem of reverse recovery current at the same time; while the Schottky barrier has good forward characteristics, There is no problem of reverse recovery current, but when subjected to a high reverse electric field, it will be affected by the lowering of the potential barrier and the tunneling effect, resulting in a large increase in the reverse leakage current, which has an impact on the long-term reliability of the device . How to simultaneously optimize and balance the forward and reverse characteristics of diode devices is an important issue in the design of semiconductor devices.

Contents of the invention

The invention proposes a new diode structure, which is suitable for diode devices of all semiconductor materials. Compared with current diodes based on Schottky barriers or direct PN junction barriers, the diode structure proposed by the present invention has the following characteristics:

1. Significantly reduced leakage current. By adjusting the channel doping and width, the reverse leakage current can be significantly reduced.

2. Adjustable forward turn-on voltage. With changes in channel width and doping, the turn-on voltage can be tuned and greatly reduced.

3. Good reverse recovery characteristics. Under the condition of forward conduction, it is unipolar operation, the current mainly flows through the channel, and there is no obvious minority carrier injection phenomenon, so it has the same characteristics of no reverse recovery current as the Schottky diode.

4. The simple structure without Schottky junction is conducive to the reliability of the device under long-term operation.

Description of drawings

Figure 1 is a cross-sectional view of the structure of the invention based on doping direct implantation;

Fig. 2 is a structural cross-sectional view of the invention based on trench-type P doping;

Figure 3 is a cross-sectional view of the trench structure based on only vertical doping;

Figure 4 is a cross-sectional view of the structure of the invention based on an inclined channel;

Figure 5 is a cross-sectional view of the structure of the invention based on the horizontal channel;

6 is a cross-sectional view of a horizontal channel structure including an insulating structure;

7 is a cross-sectional view of a horizontal channel adjacent to an N+/P+ doped region;

Fig. 8 is a cross-sectional view of a horizontal channel of an N+/P+ doped connection including an insulating structure;

FIG. 9 is a schematic structural diagram of an example of a P-type diode corresponding to the structure in FIG. 1 .

in,

1. Channel, the first semiconductor type;

2. The heavily doped region, the second semiconductor type;

3. Drift region, the first semiconductor type;

4. Electric field stop layer, the first semiconductor type;

5. Substrate, the first semiconductor type;

6. Ohmic contact layer, the first semiconductor type;

7. Anode metal;

8. Cathode metal;

9. The lateral channel indicates the doped region, the second semiconductor type;

10. Oxide.

specific implementation plan

Example 1

FIG. 1 is a structural cross-sectional view of a novel diode device of the present invention, which will be described in detail with reference to FIG. 1 .

As shown in Figure 1, a diode device with a new structure includes: a substrate 5, above which is a drift region 3; whether an electric field stop layer 4 can be added above the substrate layer; a conductive channel 1 is located above the drift region 3 , and between two adjacent heavily doped regions 2; the anode metal 7 is located on the top surface of the device, which is the lead-out electrode of the device; between the channel 1 and the anode metal 7 is a heavily doped ohmic contact layer 6 ; The cathode metal 8 is located at the bottom of the device structure, connected with the substrate 5, and leads out the electrodes.

In this example, the first semiconductor type is an N-type semiconductor conductive material, and the second semiconductor type is a P-type semiconductor material, thus forming an N-type diode; a possible manufacturing process includes the following steps:

The first step, according to whether the electric field cut-off layer 4 is needed, determines whether to grow and form the cut-off layer 4 above the N-type substrate 5; (optional)

The second step is to continue the upward epitaxial growth to obtain the drift region 3 and the N-type epitaxy corresponding to the channel concentration and length;

The third step is directly doping P-type doping at designated positions on the upper surface of the device by means of ion implantation or diffusion to form a P-type heavily doped region 2, and at the same time obtain a channel 1 sandwiched between the P-type doped regions;

The fourth step is to dope the surface of the channel 1 with high-concentration N-type doping by ion implantation, diffusion, epitaxy or other methods to obtain the ohmic contact layer 6;

The fifth step is to deposit metal on the upper and lower surfaces of the device respectively to form ohmic contacts, obtain anode metal 7 and cathode metal 8, and lead out electrodes, as shown in FIG. 1 .

Example 2

FIG. 2 is a structural sectional view of a novel diode device of the present invention, which will be described in detail in conjunction with FIG. 2 .

As shown in Figure 2, a diode device with a new structure includes: a substrate 5, above which is a drift region 3; whether an electric field stop layer 4 can be added above the substrate layer; the conductive channel 1 is located above the drift region 3 , and between two adjacent heavily doped regions 2; the anode metal 7 is located in the groove above the top surface of the device and the heavily doped region 2, and is the lead-out electrode of the device; between the channel 1 and the anode metal 7 Between them is a heavily doped ohmic contact layer 6; the cathode metal 8 is located at the bottom of the device structure, connected to the substrate 5, and leads out electrodes.

In this example, the first semiconductor type is an N-type semiconductor conductive material, and the second semiconductor type is a P-type semiconductor material, thus forming an N-type diode; a possible manufacturing process includes the following steps:

The first step, according to whether the electric field cut-off layer 4 is needed, determines whether to grow and form the cut-off layer 4 above the N-type substrate 5; (optional)

The second step is to continue the upward epitaxial growth to obtain the drift region 3 and the N-type epitaxy corresponding to the channel concentration and length;

The third step is to etch at the specified position to obtain a trench for dopant implantation;

The fourth step is to perform lateral and vertical P-type doping implantation in the obtained trench to form a P-type heavily doped region 2, and at the same time obtain a channel 1 sandwiched between the P-type doped regions;

In the fifth step, doping high-concentration N-type doping on the surface of the channel 1 by ion implantation or diffusion or epitaxy or other methods to obtain the ohmic contact layer 6;

The sixth step is to deposit metal on the upper surface of the device and in the trench to form an ohmic contact to obtain an anode metal 7; make an ohmic contact on the lower surface of the device to generate a cathode metal 8 and lead out the electrodes, as shown in Figure 2.

Fig. 3 is a structural sectional view of a novel diode device of the present invention, its structure is based on Fig. 2, does not carry out lateral implantation in the groove, only carries out vertical implantation to form P-doped region 2 and channel 1 .

FIG. 4 is a structural cross-sectional view of a novel diode device of the present invention. The structure is based on FIG. 2 , and an inclined etching method is used in the etching step to obtain an inclined channel 1 .

Example 3

FIG. 5 is a structural cross-sectional view of a novel diode device of the present invention, which will be described in detail in conjunction with FIG. 5 .

As shown in Figure 5, a diode device with a new structure includes: a substrate 5, above which is a drift region 3; whether an electric field stop layer 4 can be added above the substrate layer; the conductive channel 1 is connected to the drift region 3, and between the upper and lower adjacent heavily doped regions 2 and surface heavily doped regions 9; the anode metal 7 is located on the uppermost surface of the device and is respectively connected to the surface doped region 9, the channel 1, and the heavily doped region 2, And it is the lead-out electrode of the device; between the terminal of the channel 1 and the anode metal 7 is a heavily doped ohmic contact layer 6; the cathode metal 8 is located at the bottom of the device structure, connected to the substrate 5, and lead out the electrode.

In this example, the first semiconductor type is an N-type semiconductor conductive material, and the second semiconductor type is a P-type semiconductor material, thus forming an N-type diode; a possible manufacturing process includes the following steps:

The first step, according to whether the electric field cut-off layer 4 is needed, determines whether to grow and form the cut-off layer 4 above the N-type substrate 5; (optional)

The second step is to continue the upward epitaxial growth to obtain the drift region 3 respectively, and do P-type doping on its surface to obtain the heavily doped region 2;

The third step is to continue to grow upward to obtain N-type epitaxy according to the concentration and width design of the channel;

The fourth step is to dope P-type doping at designated positions on the upper surface of the device by ion implantation, diffusion, epitaxy, or other methods to form a surface heavily doped region 9, thereby obtaining a doped region 2 and a doped region 9 channel between 1;

The fifth step is to dope the surface of the device corresponding to the terminal of the channel 1 with high-concentration N-type doping by means of ion implantation or diffusion to obtain the ohmic contact layer 6, and etch the middle of it first to expose the heavily doped region 2 ;

The sixth step is to deposit metal on the upper and lower surfaces of the device respectively to form ohmic contacts, obtain anode metal 7 and cathode metal 8, and lead out electrodes, as shown in FIG. 5 .

Fig. 6 is a structural sectional view of a novel diode device of the present invention, the structure of which is based on Fig. 5, and an additional oxide 10 is added between the surface heavily doped region 9 and the ohmic contact layer 6 on the device surface as isolation.

FIG. 7 is a structural cross-sectional view of a novel diode device of the present invention. Its structure is based on FIG. 5 , and the ohmic contact layer 6 is connected to the heavily doped region 2 when it is formed.

FIG. 8 is a structural cross-sectional view of a novel diode device according to the present invention. Its structure is based on FIG. 5 , and the oxide 10 isolation is increased, and the ohmic contact layer 6 is connected to the heavily doped region 2 at the same time.

Example 4

The above-mentioned FIGS. 1 to 8 show structural cross-sectional views of several types of N-type diodes, each of which can correspond to a corresponding P-type diode structure. At this time, the first semiconductor type is a P-type semiconductor conductive material, and the second semiconductor type is an N-type semiconductor conductive material. At the same time, the positions of the anode metal and the cathode metal are exchanged to obtain the corresponding P-type diode, as shown in Figure 1 The first diode structure will be described as an example.

FIG. 9 is a structural cross-sectional view of a novel diode device of the present invention, which corresponds to the N-type diode structure shown in FIG. 1 , and will be described in detail in conjunction with FIG. 9 .

As shown in Figure 9, a diode device with a new structure includes: a substrate 5, above which is a drift region 3; whether an electric field stop layer 4 can be added above the substrate layer; the conductive channel 1 is located above the drift region 3 , and between two adjacent heavily doped regions 2; the cathode metal 8 is located on the top surface of the device, which is the lead-out electrode of the device; between the channel 1 and the cathode metal 8 is a heavily doped ohmic contact layer 6 ; The anode metal 7 is located at the bottom of the device structure, connected with the substrate 5, and leads out the electrodes.

In this example, the first semiconductor type is a P-type semiconductor conductive material, and the second semiconductor type is an N-type semiconductor material, thus forming a P-type diode; a possible manufacturing process includes the following steps:

In the first step, according to whether the electric field stop layer 4 is needed, it is decided whether to grow and form the stop layer 4 above the P-type substrate 5; (optional)

The second step is to continue the upward epitaxial growth to obtain the drift region 3 and the P-type epitaxy corresponding to the channel concentration and length;

The third step is to dope N-type doping directly on the upper surface of the device by means of ion implantation or diffusion at designated positions to form N-type heavily doped regions 2, and at the same time obtain channels 1 sandwiched between N-type doped regions 2;

In the fourth step, the surface of the channel 1 is doped with high-concentration P-type doping by means of ion implantation or diffusion to obtain an ohmic contact layer 6;

The fifth step is to deposit metal on the upper and lower surfaces of the device to form ohmic contacts, obtain cathode metal 8 and anode metal 7, and lead out electrodes, as shown in FIG. 9 .

FIG. 2 to FIG. 8 correspond to their respective P-type diode structures in the same way, so details are not repeated here.

The present invention has been illustrated by the above examples, while other examples can also be used to realize the present invention.

Claims (5)

1. A novel diode device structure is characterized in that: the method comprises the following steps:

the channel is formed by adjacent doping regions of corresponding types, required barrier height is formed at the same time, and one end of the diode is formed through ohmic contact;

and a drift region made of a semiconductor material, connected to the channel, and having the other end of the diode obtained through the substrate and the ohmic contact.

2. The diode device of claim 1, wherein: the diode device may employ any semiconductor material including silicon, silicon carbide, gallium nitride, diamond, and the like.

3. The diode device of claim 1, wherein: the diode device may be a P-type diode or an N-type diode.

4. The diode device of claim 1, wherein: the semiconductor channel can be in a vertical type, a transverse type and a tilted type structure, wherein the doping can be uniform doping or non-uniform doping.

5. The diode device of claim 1, wherein: the semiconductor drift region may or may not include an electric field stop layer.

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