CN103474478A - Silicon carbide SBD device - Google Patents

Abstract

The present invention relates to the field of microelectronics technology, in particular to a silicon carbide SBD device with a slot-type termination, including a Schottky contact region, a _SiO2 isolation region, a termination region, an N ^- epitaxy layer, N ⁺ substrate area and ohmic contact area, the terminal area is located at the upper surface of the ^N- epitaxial layer and connected to the edge of the Schottky contact area, and the terminal area is a continuous circle at the edge of the Schottky contact area, The terminal area has a groove structure, and the connection end between the lower surface of the metal edge of the Schottky contact area and the terminal area is provided with a groove matching the groove structure. The beneficial effects of the above-mentioned technical solution of the present invention are as follows: under the condition of satisfying the breakdown voltage required by the traditional silicon carbide SBD device, the terminal of the traditional SBD device is changed into a groove type or a ladder type, the process is simplified, the manufacturing difficulty is reduced, and the production efficiency is improved. , Reduce production costs and increase product pass rate.

Description

A silicon carbide SBD device

technical field

The invention relates to the technical field of microelectronics, in particular to a silicon carbide SBD device with bulk floating junctions.

Background technique

Wide bandgap semiconductor materials are the third generation of semiconductor materials developed after the first generation of silicon, germanium and the second generation of gallium arsenide, indium phosphide and other materials. Among the third-generation semiconductor materials, silicon carbide (SiC) and gallium nitride (GaN) are among the best. Silicon carbide material technology is mature, and high-quality 4-inch wafers are available. However, gallium nitride materials do not have a gallium nitride substrate, and epitaxy can only rely on other materials. Its thermal conductivity is only a quarter of that of silicon carbide, and p-type doping cannot be achieved. This limits the application of gallium nitride materials in high-voltage and high-power aspects. In comparison, the advantages of silicon carbide materials in the field of power electronics applications are particularly significant.

Traditional JTE and GR SBD devices generally use ion implantation technology, which is relatively complicated and has cumbersome manufacturing steps. The manufacturing process is difficult, resulting in low production efficiency and a certain impact on the pass rate of the product.

Contents of the invention

The technical problem to be solved by the present invention is to provide a silicon carbide SBD device, change the terminal of the traditional SBD device into a slot type or a ladder type, and simplify the process under the condition of meeting the breakdown voltage required by the traditional SiC SBD device Realized, reducing the production difficulty.

In order to solve the above technical problems, an embodiment of the present invention provides a silicon carbide SBD device, including a Schottky contact region, a SiO ₂ isolation region, a terminal region, ^{an N-} epitaxial layer, an N ⁺ The substrate area and the ohmic contact area, the terminal area is located on the upper surface of the N ^- epitaxial layer and connected to the edge of the Schottky contact area, the terminal area is a continuous circle at the edge of the Schottky contact area, and the terminal area It is a groove structure, and the connection end between the lower surface of the metal edge of the Schottky contact area and the terminal area is provided with a groove matching the groove structure.

Preferably, the termination region is a circle of cuboid grooves on the edge of the Schottky contact region under the three-dimensional structure.

Preferably, the terminal area is a continuous circle at the edge of the Schottky contact area, the terminal area is in a stepped structure, and the connection end between the lower surface of the metal edge of the Schottky contact area and the terminal area is provided with a step Grooves that match the structure.

Preferably, the thickness between the top surface and the bottom surface of the N ^- epitaxial layer is 20 μm, and its nitrogen ion doping concentration is 1×10 ¹⁵ to 1×10 ¹⁶ cm ^-3 .

Preferably, the terminal region has a thickness of 2 μm and a width of 10 μm.

Preferably, the distance between the inner edge of the terminal region and the Schottky contact region is 2 μm.

Preferably, the metal edge of the Schottky contact region is located on the dielectric layer inside the terminal region.

The beneficial effects of the above-mentioned technical solution of the present invention are as follows: under the condition of satisfying the breakdown voltage required by the traditional silicon carbide SBD device, the terminal of the traditional SBD device is changed into a groove type or a ladder type, the process is simplified, the manufacturing difficulty is reduced, and the production is improved. Efficiency, reduce production costs, improve product qualification rate.

Description of drawings

FIG. 1 is a schematic structural diagram of an embodiment of a silicon carbide SBD device with a slot terminal in the present invention.

Fig. 2 is a schematic structural diagram of an embodiment of a silicon carbide SBD device with a stepped slot terminal according to the present invention.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

The present invention provides a silicon carbide SBD device aimed at the existing deficiencies, as shown in Figure 1, including Schottky contact region 1, SiO ₂ isolation region 2, terminal region 3, ^N- Epitaxial layer 4, N ⁺ substrate region 5 and ohmic contact region 6, the terminal region is located on the upper surface of the ^N- epitaxial layer and connected to the edge of the Schottky contact region, and the terminal region is continuous at the edge of the Schottky contact region The terminal area has a groove structure, and the connection end between the lower surface of the metal edge of the Schottky contact area and the terminal area is provided with a groove matching the groove structure.

Under the three-dimensional structure, the terminal area is a circle of rectangular parallelepiped grooves on the edge of the Schottky contact area.

Among them, the terminal area 3 acts as a protection area for the edge of the Schottky contact area, relieves the peak electric field at the edge of the Schottky contact area, and achieves the effect similar to other common terminals, and does not introduce additional junction capacitance and increase reverse leakage current.

The thickness between the top surface and the bottom surface of the N ^- epitaxial layer is 20 μm, and its nitrogen ion doping concentration is 1×10 ¹⁵ -1×10 ¹⁶ cm ^-3 .

The terminal region has a thickness of 2 μm and a width of 10 μm.

The distance between the inner edge of the terminal region and the Schottky contact region is 2 μm.

The metal edge of the Schottky contact area is located on the dielectric layer inside the termination area.

As shown in Figure 2, the terminal area is a continuous circle at the edge of the Schottky contact area, the terminal area is in a stepped structure, and the connection end between the lower surface of the metal edge of the Schottky contact area and the terminal area is set There are grooves to match the stepped structure.

The thickness between the top surface and the bottom surface of the N ^- epitaxial layer is 20 μm, and its nitrogen ion doping concentration is 1×10 ¹⁵ -1×10 ¹⁶ cm ^-3 .

The terminal region has a thickness of 2 μm and a width of 10 μm.

The distance between the edge of the termination region and the Schottky contact region is 2 μm.

The metal edge of the Schottky contact area is located on the dielectric layer inside the terminal area.

In the specific implementation process, some flexible designs can be made according to the specific situation and under the condition that the basic structure remains unchanged. For example:

1. In the case of meeting the device’s withstand voltage of 1500V, the concentration of the N ^- epitaxial layer can be designed to be 3×10 ¹⁵ cm ^-3 , 5×10 ¹⁵ cm ^-3 and 7×10 ¹⁵ cm ^-3 in three different ways . The increase of the concentration will reduce the slope of the electric field, and the withstand voltage will also decrease accordingly. .

2. In the case of meeting the withstand voltage of the device at 1500V, the thickness of the terminal area can be designed in three different ways: 2 μm, 5 μm and 10 μm. The thickness of the formed groove structure has a great influence on the breakdown voltage of the device. The thicker the terminal, the stronger the protection for the edge of the Schottky contact area, and the higher the breakdown voltage.

3. In the case of meeting the withstand voltage of the device at 1500V, the length of the terminal area can be designed in three different ways: 10 μm, 20 μm and 30 μm. Increase the length of the termination region and the appropriate width of the diffraction depletion region to achieve the purpose of increasing the breakdown voltage.

4. The structure of the terminal area can be in two different ways as shown in Figure 1 and Figure 2. Figure 1 shows a groove-shaped structure in the terminal area, and Figure 2 shows a stepped structure in the terminal area, in which the thickness increases sequentially from the inside to the outside. Both structures can protect the edge of the Schottky junction without affecting the forward characteristics of the device.

Using the silicon carbide SBD device with slot-type terminals of the present invention, the structure of the terminal region will be optimized as much as possible, including depth, length and Schott The distance of the base contact area, etc., so that it can achieve the best performance. With the development of semiconductor technology, more new high-power devices can be produced by adopting the invention.

The present invention also provides a method for manufacturing the above-mentioned silicon carbide SBD device. In this method, the termination region is realized by silicon carbide dry etching. Include the following specific steps:

A10, making the first epitaxial layer on the silicon carbide substrate by an epitaxial process to form a drift region of the N ^- epitaxial layer;

A20. The metal layer is deposited by ion beam evaporation, and the window of the groove terminal is formed by etching, and the silicon carbide dry etching forms the groove structure, that is, the groove terminal;

A30, front deposition SiO ₂ isolation medium;

A40, making the ohmic contact area on the bottom surface and the Schottky metal area on the top surface;

A50, PI glue passivation.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (7)

1. a carborundum SBD device, is characterized in that, comprises from top to down Schottky contact region, SiO that layering successively arranges ₂isolated area, termination environment, N ^-epitaxial loayer, N ⁺substrate zone and ohmic contact regions, described termination environment is positioned at N ^-the epitaxial loayer upper surface is connected with Schottky contact region edge, described termination environment is at a circle of Schottky contact region continuous edge, described termination environment is trench structure, and described Schottky contact region metal edge place lower surface is provided with the link of termination environment the groove matched with trench structure.

2. a kind of carborundum SBD device as claimed in claim 1, is characterized in that, described termination environment is the circle cuboid groove at the Schottky contacts area edge under three-dimensional structure.

3. a kind of carborundum SBD device as claimed in claim 1, it is characterized in that, described termination environment is at a circle of Schottky contact region continuous edge, described termination environment is the notch cuttype structure, and described Schottky contact region edge lower surface is provided with the link of termination environment the groove matched with the notch cuttype structure.

4. a kind of carborundum SBD device as described as claim 1 or 3, is characterized in that described N ^-the end face of epitaxial loayer and the thickness between bottom surface are 20 μ m, and its nitrogen ion doping concentration is 1 * 10 ¹⁵～1 * 10 ¹⁶cm ^-3.

5. a kind of carborundum SBD device as claimed in claim 4, is characterized in that, described termination environment thickness is 2 μ m, and width is 10 μ m.

6. a kind of carborundum SBD device as claimed in claim 5, is characterized in that, the distance between described termination environment inward flange and Schottky contact region is 2 μ m.

7. a kind of carborundum SBD device as claimed in claim 6, is characterized in that, described Schottky contact region metal edge is positioned on the dielectric layer of inside, termination environment.

Images