CN104201212B - Floating junction silicon carbide SBD device with block groove and buried regions - Google Patents

Abstract

The present invention relates to a kind of floating junction silicon carbide SBD device with bulk trench and buried layer, it is characterized in that, it comprises metal, SiO ₂ isolation medium, trench, primary N ^- epitaxial layer, P ⁺ ion implantation region, secondary The secondary N ^- epitaxial layer, N ⁺ substrate area and ohmic contact area, the P + ion implantation area is on the surface of the secondary N ^- epitaxial layer, the groove is aligned with the P ⁺ ion implantation area up and down, and the shape is the same, or it is the same as the P ⁺ ion implantation area. The ion implantation regions are aligned up and down and have the same shape, and the floating junction adopts a circular, hexagonal or square block buried layer. The invention has a floating junction silicon carbide SBD device with a block trench and a buried layer. The device not only has the advantages of large trench-type silicon carbide SBD Schottky contact area and large forward conduction current, but also has the advantages of a floating junction silicon carbide SBD The advantage of high breakdown voltage.

Description

Floating Junction SiC SBD Devices with Bulk Trench and Buried Layer

technical field

The invention relates to the technical field of microelectronics, in particular to a floating junction silicon carbide SBD device with a bulk trench and a buried layer.

Background technique

Semiconductor materials have made great leaps in the past few decades. Wide bandgap semiconductor materials are the third-generation semiconductor materials represented by materials such as silicon carbide and gallium nitride. Among them, silicon carbide materials are especially famous. Silicon carbide materials In the 1980s and 1990s, it began to enter people's research sight, and it has developed rapidly in the past ten years. Silicon carbide technology has gradually matured and entered the market, and many silicon carbide technologies have been industrialized. Silicon carbide material has better electrical properties than Si, which makes it very suitable for high voltage, high power and high frequency fields. And its development pace has surpassed other wide bandgap semiconductors, and it has wider applications than other wide bandgap semiconductors.

The SiC material has a large band gap, which can reach more than 3eV. The critical breakdown electric field can reach more than 2MV/cm. SiC material has high thermal conductivity (about 4.9W/cm.K), and the device is resistant to high temperature, which is more suitable for high-current devices than Si. SiC carrier lifetime is short, only a few nanoseconds to hundreds of nanoseconds. The radiation resistance of SiC materials is also excellent, and the electron-holes introduced by radiation are much less than Si materials. Therefore, the excellent physical properties of SiC make SiC devices widely used in aerospace electronics, high-temperature radiation harsh environments, military electronic wireless communications, radar, automotive electronics, high-power phased array mines, radio frequency RF and other fields, and in the future The field of new energy has extremely good application prospects.

The floating junction structure can nearly double the breakdown voltage of devices under the same doping concentration. SiC floating junction devices have been successfully fabricated for the first time in the laboratory by T Hatakeyama et al. Schottky diodes are widely used in power devices due to their low voltage drop and high current. In order to achieve greater current, someone proposed a SiC trench Schottky diode (TSBD) in the 1990s. Trench Schottky diodes greatly increase the area of the Schottky contact, enabling lower voltage drop and higher current.

However, the floating junction silicon carbide Schottky diode (SiC FJ-SBD), the buried layer introduced in the epitaxial layer of the device, narrows the conduction channel of the forward conduction current, and the forward conduction current of the device becomes smaller. Conventional The strip-shaped buried layer makes the duty cycle of the conductive channel at the floating junction not high. However, the trench corners of the trenched SiC SBD cause the device to introduce a peak electric field under the action of the reverse voltage, which reduces the breakdown voltage of the device.

In view of the above-mentioned defects, the author of the present invention has finally obtained this creation through long-term research and practice.

Contents of the invention

The object of the present invention is to provide a floating junction silicon carbide SBD device with bulk trenches and buried layers to overcome the above-mentioned technical defects.

To achieve the above object, the present invention provides a floating junction silicon carbide SBD device with bulk trenches and buried layers, which includes metal, SiO ₂ isolation medium, trenches, primary N- epitaxial layer ^, P ⁺ ion implantation region, Secondary N ^- epitaxial layer, N ⁺ substrate area and ohmic contact area,

The P+ ion implantation region is located on the surface ^of the secondary N- epitaxial layer, the groove is aligned up and down with the P ⁺ ion implantation region, and has the same shape, or is vertically aligned with the P ⁺ ion implantation region, and has the same shape, and the floating junction adopts a circular or elliptical shape. Shaped or hexagonal massive buried layer.

Further, the groove has the same shape and area as the P ⁺ ion implantation region, and the groove is aligned with the edge of the bulk P ⁺ ion implantation region below the groove.

Further, the groove has the same shape and area as the non-P ⁺ ion implantation region, and the groove is aligned with the edge of the non-P ⁺ ion implantation region below the groove.

Further, the P ⁺ ion implantation region adopts a circular or elliptical block-shaped buried layer, and the circular or elliptical arrangement includes multiple rows of circular or elliptical rows arranged in parallel, and multiple rows of staggered circular or elliptical rows. shape.

Further, the P ⁺ ion implantation region adopts a hexagonal block buried layer, and the arrangement of the hexagons includes multiple rows of hexagons arranged in parallel, multiple rows of staggered hexagons and hexagons arranged in a honeycomb shape shape.

Further, the P+ ion implantation region adopts a square block buried layer, and the square arrangement includes multiple rows of squares arranged in parallel, non-adjacent and staggered squares, and adjacent staggered squares.

Further, the depth of the groove is 1-3 μm.

Further, the doping concentration of the P ⁺ ion implantation region is 1×10 ¹⁷ cm ⁻³ to 1×10 ¹⁹ cm ⁻³ , and the thickness is 0.4˜0.6 μm.

Furthermore, the thickness of the uppermost end and the bottom of the N- epitaxial layer is 20 μm, the doping concentration thereof is 1×10 ¹⁵ cm ^-3 to 1×10 ¹⁶ cm ^-3 , ^{and the thickness of the primary N - epitaxial} layer is 5-15 μm.

Further, the metal and the SiO ₂ isolation medium are located above the secondary N- epitaxial layer ^; the metal and the SiO ₂ isolation medium are adjacent.

Compared with the prior art, the beneficial effect of the present invention is that: the present invention has a floating junction silicon carbide SBD device with a block trench and a buried layer. The advantage of large current flow, and the advantage of large breakdown voltage of floating junction silicon carbide SBD.

The device provided by the invention introduces a circular, hexagonal or square block-shaped buried layer. Compared with the traditional strip-shaped buried layer, the conductive channel is wider and the forward conduction current is larger.

The device provided by the invention has the advantages of short switching time and strong radiation resistance, and can be widely used in the field of power electronics.

Description of drawings

Figure 1a is a schematic cross-sectional view of a trench-type floating junction silicon carbide SBD device in which the trench and the P+ ion implantation region are aligned up and down according to the present invention;

Fig. 1b is a top view of a trench-type floating junction silicon carbide SBD device with multiple rows of parallel-arranged circular block-shaped buried layers when the trench and the P+ ion implantation region are aligned up and down according to the present invention;

2 is a schematic cross-sectional view of a trench-type floating junction silicon carbide SBD device in which the trench and the non-P+ ion implantation region are aligned up and down according to the present invention;

3 is a top view of a grooved floating junction silicon carbide SBD device with multiple rows of parallel-arranged circular block-shaped buried layers when the groove is aligned up and down with the non-P+ ion implantation region of the present invention;

Fig. 4 is a top view of a trench-type floating junction silicon carbide SBD device with multiple rows of staggered circular block-shaped buried layers when the trench and the P+ ion implantation region are aligned up and down in the present invention;

Fig. 5 is a top view of a trench type floating junction silicon carbide SBD device with multiple rows of parallel arranged hexagonal block buried layers when the trench and the P+ ion implantation region are aligned up and down according to the present invention;

Fig. 6 is a top view of a trench type floating junction silicon carbide SBD device with multiple rows of parallel hexagonal block buried layers when the trench is aligned up and down with the non-P+ ion implantation region;

Fig. 7 is a top view of a trench type floating junction silicon carbide SBD device with multiple rows of staggered hexagonal block buried layers when the trenches are aligned up and down with the P+ ion implantation region of the present invention;

Fig. 8 is a top view of a trench type floating junction silicon carbide SBD device with a hexagonal block buried layer arranged in a hexagonal shape when the trench and the P+ ion implantation region are vertically aligned according to the present invention.

Fig. 9 is a top view of a trench-type floating junction silicon carbide SBD device with multiple rows of parallel-arranged square block-shaped buried layers when the trench and the P+ ion implantation region are aligned up and down according to the present invention;

Fig. 10 is a top view of a trench-type floating junction silicon carbide SBD device with multiple rows of parallel-arranged square block-shaped buried layers when the trench and the non-P+ ion implantation region are aligned up and down according to the present invention;

Fig. 11 is a top view of a trench type floating junction silicon carbide SBD device with non-adjacent staggered square block buried layers when the trenches and P+ ion implantation regions are aligned up and down according to the present invention;

Fig. 12 is a top view of a trench-type floating-junction silicon carbide SBD device with adjacent staggered square block-shaped buried layers in the present invention when the trenches are aligned up and down with the P+ ion implantation region.

detailed description

The above and other technical features and advantages of the present invention will be described in more detail below in conjunction with the accompanying drawings.

Please refer to Fig. 1a, the device structure adopted by the floating junction silicon carbide SBD device of the present invention includes: metal 1, _SiO2 isolation medium 2, trench 3 ^, primary N- epitaxial layer 4, P ⁺ ion implantation region 5, Secondary N ^- epitaxial layer 6, N ⁺ substrate region 7, ohmic contact region 8.

As shown in Figure 1b, the N ⁺ substrate 7 is an N-type SiC substrate, and the primary N ^- epitaxial layer 4 is located on the N + substrate 7 with a thickness of 5-15 μm, wherein the doping concentration of nitrogen ions is The impurity concentration is 1x10 ¹⁵ cm ^-3 to 1x10 ¹⁶ cm ^-3 .

The P ⁺ ion implantation region 5 is located on the surface of the primary N ^- epitaxial layer 4, the doping concentration is 1x10 ¹⁷ cm ^-3 ~ 1x10 ¹⁹ cm -3 , the ion implantation depth is 0.4 ~ 0.6 μm, and the secondary N ^- epitaxial layer 6 is located Above the primary N ^- epitaxial layer 4 , the thickness is 5-15 μm and the doping concentration is 1x10 ¹⁵ cm ^-3 -1x10 ¹⁶ cm ^-3 . The total thickness of the primary N ^- epitaxial layer 4 and the secondary N ^- epitaxial layer 6 is 20 μm.

The metal 1 and SiO ₂ isolation dielectric 2 are located above the secondary N ^- epi layer 6 . The metal 1 is adjacent to the SiO ₂ isolation medium 2 , and the metal 1 and the SiO ₂ isolation medium 2 have overlapping positions 12 . The groove 3 has a depth of 1-3 μm and is located below the metal 1 . The groove 3 and the metal 1 are provided with overlapping places 13 , on the surface of the secondary N ⁻ epitaxial layer 6 .

Please refer to FIG. 1b, FIG. 3, FIG. 7, and FIG. 8. In FIG. 1b ^and FIG. In Fig. 3 and Fig. 8, the trench 3 and the P ⁺ ion implantation region 5 are completely staggered so that the trench 3 and the non-P ⁺ ion implantation region 5 have the same shape and are aligned up and down, which has no influence on the breakdown voltage of the device, while the positive different conduction currents.

Please refer to Fig. 1b, Fig. 5 and Fig. 7, the present invention adopts a circular, hexagonal or square block-shaped buried layer, the circular and elliptical shapes have no corners, and the angles of the hexagonal corners are very large. And in the actual process, the corners will be very smooth. When these shapes have the same duty cycle, the forward conduction current is the same, but the reverse breakdown voltage is different.

The arrangement of the circular block-shaped buried layer can be arranged in two different ways as shown in Figure 1b and Figure 4. The circle in Figure 1b is a circle arranged in parallel in multiple rows, and the circle in Figure 4 is a multi-row staggered arrangement. The area of the floating junction remains unchanged in these two arrangements, and only the arrangement of the floating junction is changed. The forward current of the device does not change, but the reverse breakdown voltage does.

The arrangement of the hexagonal block buried layer can be arranged in three different ways as shown in Fig. 5, Fig. 7 and Fig. 8. In Fig. 5, the hexagonal shape is arranged in parallel in multiple rows, and in Fig. 7, the hexagonal shape is arranged in multiple rows in a staggered manner; The area of the floating junction in the two arrangements remains the same, only the arrangement of the floating junction is changed, the forward current of the device will not change, but the reverse breakdown voltage is different; in Figure 8, the hexagonal shape is Hexagonal arrangement, the area of each hexagonal floating junction in Figure 8 is the same as the area of each hexagonal floating junction in the other two figures, the arrangement of floating junctions becomes tighter and more uniform, and it is sensitive to engraving deviation The sensitivity is lower than that of engraving deviation in the other two figures.

Figure 9, Figure 11 and Figure 12 can be used to arrange the square block buried layers in three different ways; among them, the squares in Figure 9 are arranged in parallel in multiple rows, the squares in Figure 11 are non-adjacent and staggered, and the squares in Figure 12 are arranged in parallel. The adjacent staggered arrangement; wherein, in Figure 9 and Figure 11, the area of the floating junction is unchanged, only the arrangement of the floating junction is changed; the forward current of the device will not change, but the reverse breakdown voltage is different. The area of each floating junction in Figure 12 is the same as that of each floating junction in the other two figures. The floating junctions become more tightly packed and less sensitive to engraving bias than in the other two figures.

Embodiment one:

Referring to Figure 1a and Figure 1b, the structure of the trench type floating junction silicon carbide SBD device with circular or hexagonal and elliptical bulk buried layers in the present invention is as follows:

The N ⁺ substrate is an N ^- type SiC substrate, the primary N- epitaxial layer is located on the N ⁺ substrate, the P ⁺ ion implantation area is located on the surface of the primary N- epitaxial layer ^{, and the secondary N- epitaxial layer is located above the primary N - epitaxial} layer .

The metal and the SiO ₂ isolation medium are located above the secondary N ^- epitaxy layer, the metal and the SiO ₂ isolation medium are adjacent, and the metal and the SiO ₂ isolation medium overlap. The trench is located beneath the metal, secondary to the surface of the N ^- epi layer.

The thickness of the primary N ^- epitaxial layer is 5 μm, and the doping concentration of nitrogen ions is 1×10 ¹⁶ cm ^-3 . The doping concentration of the P ⁺ ion implantation region is 7× ^{10 17} cm ^-3 , and the ion implantation depth is 0.6 μm. The thickness of the secondary N ^- epitaxial layer is 15μm and the doping concentration is 1x10 ¹⁶ cm ^-3 .

The depth of the groove was 1 μm.

The trenches in the Schottky contact region have the same shape as the P ⁺ ion implantation region, aligned up and down. The P ⁺ ion implantation area is a circular bulk buried layer arranged in parallel in multiple rows.

Embodiment two:

Referring to Figure 1a and Figure 5, the structure of the trench type floating junction silicon carbide SBD device with circular or hexagonal and elliptical or block buried layers in the present invention is as follows:

The N ⁺ substrate is an N ^- type SiC substrate, the primary N- epitaxial layer is located on the N ⁺ substrate, the P ⁺ ion implantation area is located on the surface of the primary N- epitaxial layer ^{, and the secondary N- epitaxial layer is located above the primary N - epitaxial} layer .

Metal and SiO ₂ spacer dielectrics are located above the secondary N ^- epi layer. The metal is adjacent to the SiO ₂ isolation medium, and the metal and the SiO ₂ isolation medium overlap. The trench is located beneath the metal, secondary to the surface of the N ^- epi layer.

The thickness of the primary N ^- epitaxial layer is 10 μm, and the doping concentration of nitrogen ions is 5x10 ¹⁵ cm ^-3 . The doping concentration of the P ⁺ ion implantation region is 3×10 ¹⁸ cm ^-3 , and the ion implantation depth is 0.5 μm. The thickness of the secondary N ^- epitaxial layer is 10 μm, and the doping concentration is 5x10 ¹⁵ cm ^-3 .

The depth of the groove was 2 μm.

The trenches in the Schottky contact region have the same shape as the P ⁺ ion implantation region, aligned up and down. The P ⁺ ion implantation area is a square block buried layer in which adjacent rows are arranged vertically and non-staggered.

Embodiment three:

Referring to Fig. 2 and Fig. 8, the structure of the groove type floating junction silicon carbide SBD device with a circular or hexagonal and elliptical block buried layer in the present invention is as follows:

The N ⁺ substrate is an N ^- type SiC substrate, the primary N- epitaxial layer is located on the N ⁺ substrate, the P ⁺ ion implantation area is located on the surface of the primary N- epitaxial layer ^{, and the secondary N- epitaxial layer is located above the primary N - epitaxial} layer .

Metal and SiO ₂ spacer dielectrics are located above the secondary N ^- epi layer. The metal is adjacent to the SiO ₂ isolation medium, and the metal and the SiO ₂ isolation medium overlap. The trench is located beneath the metal, secondary to the surface of the N ^- epi layer.

The thickness of the primary N ^- epitaxial layer is 5 μm, and the doping concentration of nitrogen ions is 3x10 ¹⁵ cm ^-3 . The doping concentration of the P ⁺ ion implantation region is 1×10 ¹⁹ cm-3, and the ion implantation depth is 0.4 μm. The thickness of the secondary N ^- epitaxial layer is 15μm and the doping concentration is 3x10 ¹⁵ cm ^-3 .

The depth of the groove was 3 μm.

The trenches in the Schottky contact region have the same shape as the non-P ⁺ ion-implanted region, aligned up and down. The P ⁺ ion implantation area is a hexagonal block buried layer arranged in parallel in multiple rows.

The above descriptions are only preferred embodiments of the present invention, and are only illustrative rather than restrictive to the present invention. Those skilled in the art understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the invention, but all will fall within the protection scope of the present invention.

Claims (9)

1. a kind of floating junction silicon carbide SBD device with block groove and buried regions, it is characterised in that it includes metal, SiO₂Every From medium, groove, a N^-Epitaxial layer, P⁺Ion implanted region, secondary N^-Epitaxial layer, N⁺Substrate zone and ohmic contact regions,

Metal and SiO₂Spacer medium is located above secondary N- epitaxial layers, metal and SiO₂Spacer medium is adjacent, and metal with and SiO₂In place of spacer medium coincides, groove is located at below metal, the surface of secondary N- epitaxial layers；

The P+ ion implanted regions are in a N^-The surface of epitaxial layer, groove and P⁺Ion implanted region consistency from top to bottom, shape phase Together, or with non-P⁺Ion implanted region consistency from top to bottom, shape is identical, and floating junction is buried using circular, six prismatics or square bulk Layer, a N^-Epitaxial layer is located at the N+ substrates, and thickness is 5~15 μm, the secondary N^-Epitaxial layer is located at described one Secondary N^-Above epitaxial layer, thickness is 5~15 μm, a N^-Epitaxial layer and the secondary N^-The gross thickness of epitaxial layer is 20 μm, The depth of the groove is 1~3 μm.

2. the floating junction silicon carbide SBD device according to claim 1 with block groove and buried regions, it is characterised in that The groove and P⁺Ion implanted region shape is identical, area equation, and groove and the block P of this beneath trenches⁺Ion implanted region Align at edge.

3. the floating junction silicon carbide SBD device according to claim 1 with block groove and buried regions, it is characterised in that Described groove and non-P⁺Ion implanted region shape is identical, area equation, and groove and the non-P of this beneath trenches⁺Ion implanted region Edge alignment.

4. the floating junction silicon carbide SBD device according to claim 3 with block groove and buried regions, it is characterised in that The P⁺Ion implanted region includes the circular, more of more parallel rows arrangement using circular block buried regions, the arrangement mode of circular shape The staggered circle of row.

5. the floating junction silicon carbide SBD device according to claim 3 with block groove and buried regions, it is characterised in that The P⁺Ion implanted region uses the block buried regions of six prismatics, and the arrangement mode of six prismatics includes six ribs of more parallel rows arrangement Shape, multirow are staggered six prismatics of six prismatics and honeycomb arrangement.

6. the floating junction silicon carbide SBD device according to claim 3 with block groove and buried regions, it is characterised in that The P⁺Ion implanted region uses square block buried regions, and square arrangement mode includes square, the not phase of more parallel rows arrangement Adjacent staggered square and interleaved adjacent arranges square.

7. the floating junction silicon carbide SBD device according to claim 1 or 2 with block groove and buried regions, its feature exist In P⁺The doping concentration of ion implanted region is 1x10¹⁷cm^-3~1x10¹⁹cm^-3, thickness is 0.4~0.6 μm.

8. the floating junction silicon carbide SBD device according to claim 7 with block groove and buried regions, it is characterised in that N^-Epitaxial layer and the secondary N^-The doping concentration of epitaxial layer is 1x10¹⁵cm^-3~1x10¹⁶cm^-3。

9. the floating junction silicon carbide SBD device according to claim 7 with block groove and buried regions, it is characterised in that The metal and SiO₂Spacer medium is located at secondary N^-Above epitaxial layer；Metal and SiO₂Spacer medium is adjacent.