CN110707147A - Variable-angle field limiting ring terminal structure and preparation method thereof - Google Patents
Variable-angle field limiting ring terminal structure and preparation method thereof Download PDFInfo
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- 230000000670 limiting effect Effects 0.000 title claims abstract description 165
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 33
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 31
- 238000000034 method Methods 0.000 claims description 29
- 239000000758 substrate Substances 0.000 claims description 14
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Abstract
The invention relates to a field limiting ring terminal structure with a variable angle and a preparation method thereof, wherein the field limiting ring terminal structure comprises: a semiconductor layer (101); the field limiting ring structures (102) are distributed in the surface area of the semiconductor layer (101) at intervals, a preset included angle is formed between a first edge (103) of each field limiting ring structure (102) and a first top surface (104) of each field limiting ring structure (102), and the preset included angle is 30-60 degrees; the active region (105) is located in the surface area of the semiconductor layer (101) and located inside a ring formed by the field limiting ring structures (102), and the preset included angle is formed between the second edge (106) of the active region (105) and the second top surface (107) of the active region (105). The edges of the field limiting ring structure and the active region in the field limiting ring terminal structure both have certain inclination angles, so that the breakdown voltage of the device is effectively improved, and the reverse voltage withstanding stability of the device is improved.
Description
Technical Field
The invention belongs to the technical field of microelectronics, and particularly relates to a field limiting ring terminal structure with a variable angle and a preparation method thereof.
Background
With the rapid development of microelectronic technology, the conventional silicon-based power electronic device cannot fully meet the requirements of high-voltage and high-power devices on radiation resistance, small electric leakage, high temperature, high voltage and the like due to the restriction of the material characteristics of the silicon material such as narrow forbidden band, low thermal conductivity, low critical electric field and the like. Silicon carbide (SiC), one of the third generation semiconductor materials, has material characteristics of a forbidden bandwidth (3 times that of silicon), a high thermal conductivity (3.3 times that of silicon), and a large breakdown electric field (10 times that of silicon). The forbidden bandwidth determines that the high-performance radiation-resistant material has good radiation resistance, the high heat conductivity determines that the high-performance radiation-resistant material is suitable for a high-temperature working environment, and the heat dissipation of a power electronic system is facilitated, so that the system efficiency is improved; the breakdown electric field greatly determines that the silicon carbide power device is more pressure-resistant than a silicon material, and can effectively meet various high-voltage working requirements, so that the silicon carbide power device has wide application prospect. In recent years, silicon carbide (SiC) -based high-voltage power devices have been widely studied in various layers such as substrate development and epitaxial technology, but due to the fact that electric field concentration exists at the edge position of a PN junction under reverse bias operation, premature breakdown of the devices is caused. In order to improve the reliability of the device under reverse bias high voltage, the terminal structure technology is widely applied. Among them, the Field Limiting ring terminations (FLRs) structure is widely used because its fabrication process is simple, and it can be formed simultaneously with the active region by using a single mask.
The field limiting ring terminals which are unevenly distributed are generally adopted in the conventional field limiting ring terminal structure at present. For a silicon carbide-based device, an active region and each floating field ring are formed by ion implantation, and due to the low thermal diffusivity of impurities in a silicon carbide material, even if high-temperature activation annealing is carried out, the implanted impurity atoms can not generate an obvious high-temperature junction pushing phenomenon. Therefore, in the silicon carbide-based device, the formed injection type PN junction structure generally has an approximately ideal cylindrical or spherical junction edge, namely the macroscopic cross-sectional structure of the structure presents a quasi-rectangular doping edge morphology characteristic. The electric field concentration effect is very significant due to the small radius of curvature at the edges of the rectangle. This results in: 1) the breakdown voltage of a traditional field limiting ring structure with quasi-rectangular doping edge appearance characteristics cannot completely meet target design requirements due to edge electric field concentration, and the number of rings is increased to achieve the target breakdown voltage, so that the area of a chip is increased, and the cost is increased; 2) the actual process preparation of the traditional field limiting ring structure with the quasi-rectangular doping edge morphology features has the minimum line width dimension, the optimal ring spacing is prone to deviation caused by process precision limitation or fluctuation, and the deviation of the ring spacing can cause instability of reverse breakdown voltage of a device.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a field limiting ring termination structure with a variable angle and a method for manufacturing the same. The technical problem to be solved by the invention is realized by the following technical scheme:
the embodiment of the invention provides a field limiting ring terminal structure with a variable angle, which comprises:
a semiconductor layer;
the field limiting ring structures are distributed in the surface area of the semiconductor layer at intervals, a preset included angle is formed between a first edge of each field limiting ring structure and a first top surface of each field limiting ring structure, and the preset included angle is 30-60 degrees;
the active region is positioned in the surface area of the semiconductor layer and is positioned in an annular formed by the field limiting ring structures, and the preset included angle is formed between the second edge of the active region and the second top surface of the active region.
In one embodiment of the present invention, the cross-sectional shape of the field limiting ring structure and the cross-sectional shape of the active region are both inverted trapezoids.
In one embodiment of the invention, the depth of the field limiting ring structure and the depth of the active region are both 0-1 μm, and the width of the bottom of the field limiting ring structure is 2-5 μm.
In one embodiment of the present invention, the distance between the bottoms of two adjacent field limiting ring structures is:
Sn＝S1+(n-1)×d
wherein S isnThe distance between the bottoms of two adjacent field limiting ring structures is less than or equal to S with the diameter of 1 mu mn≤10μm，S1Is the first ring spacing, and S is more than or equal to 1 mu m1N is the number of rings of the field limiting ring structure along the direction from the active region to the field limiting ring structure, n is not less than 5 and not more than 30, d is the increment of the ring spacing, and d is not less than 0.1 mu m and not more than 0.5 mu m.
In one embodiment of the present invention, the doping concentration of the active region and the doping concentration of the field limiting ring structure are both 1 × 1018～2×1019cm-3。
In one embodiment of the present invention, further comprising:
a silicon carbide substrate layer, the semiconductor layer being located on the silicon carbide substrate layer;
a passivation layer on the semiconductor layer and in contact with a surface portion of the active region.
Another embodiment of the present invention provides a method for manufacturing a field limiting ring termination structure with a variable angle, including the steps of:
preparing a mask layer with a plurality of first openings on the semiconductor layer, wherein a preset included angle is formed between the edge of the mask layer and the bottom surface of the mask layer, and the preset included angle is 30-60 degrees;
performing ion implantation on the semiconductor layer from the first opening to form an active region and a plurality of field limiting ring structures, wherein the preset included angle is formed between a first edge of each field limiting ring structure and the top surface of the corresponding field limiting ring structure, and between a second edge of each active region and the top surface of the corresponding active region;
and removing the mask layer and activating implanted ions.
In an embodiment of the present invention, preparing a mask layer having a plurality of first openings on the semiconductor layer, wherein a predetermined included angle is formed between an edge of the mask layer and a bottom surface of the mask layer, includes:
growing the mask layer on the semiconductor layer;
preparing photoresist with a plurality of second openings on the surface of the mask layer;
and controlling the etching selection ratio of the mask layer and the photoresist, and etching the mask layer to form a plurality of first openings, so that the preset included angle is formed between the edge of the mask layer and the bottom surface of the mask layer.
Compared with the prior art, the invention has the beneficial effects that:
in the field limiting ring terminal structure, the first edge of the field limiting ring structure and the first top surface as well as the second edge of the active region and the second top surface form included angles of 30-60 degrees, so that the edges of the field limiting ring structure and the active region have certain inclination angles, the edge curvature radius of the PN junction edge of the field limiting ring is equivalently increased, the macroscopic electric field distribution of a device is optimized, and the breakdown voltage of the device is effectively improved; meanwhile, the field limiting ring structure and the edge of the active region both have a certain inclination angle, so that the sensitivity of the design to the process size, precision and fluctuation is weakened, the problem of device breakdown voltage fluctuation caused by ring spacing change due to process fluctuation is solved, and the reverse voltage withstanding stability of the device is improved.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Drawings
Fig. 1 is a schematic cross-sectional view of a terminal structure of a field limiting ring with a variable angle according to an embodiment of the present invention;
fig. 2 is a schematic flowchart of a method for manufacturing a field limiting ring termination structure with a variable angle according to an embodiment of the present invention;
fig. 3a to fig. 3h are schematic diagrams illustrating a method for manufacturing a variable angle field limiting ring termination structure according to an embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view of a prior art termination structure for a field limiting ring with a quasi-rectangular doped edge profile feature;
FIG. 5 is a diagram of simulation results of a change rule of breakdown voltage with junction edge angles of a field limiting ring structure according to an embodiment of the present invention;
fig. 6 is a comparison graph of the lateral electric field distribution at the bottom of the ring junction when the field limiting ring terminal structure with the variable-angle inverted-trapezoidal doping edge profile having the junction edge angle of 30 ° and the field limiting ring terminal structure with the quasi-rectangular doping edge profile having the junction edge angle of 85 ° are reversely broken down according to the embodiment of the present invention;
FIG. 7 shows simulated breakdown voltages of the field limiting ring terminal structure with variable-angle inverse-trapezoidal doping edge profile having a junction edge angle of 45 degrees and the field limiting ring terminal structure with quasi-rectangular doping edge profile having a junction edge angle of 85 degrees according to the first-ring spacing S of the field limiting ring according to the embodiment of the present invention1Comparative schematic of the changes.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
Example one
Referring to fig. 1, fig. 1 is a schematic cross-sectional view of a variable angle field limiting ring termination structure according to an embodiment of the present invention. The schematic diagram in fig. 1 is a cross-sectional view of a half cell.
This field limiting ring terminal structure includes: a semiconductor layer 101, a plurality of field limiting ring structures 102, and an active region 105. Wherein a plurality of field limiting ring structures 102 are distributed at intervals in the surface area of the semiconductor layer 101, and in each field limiting ring structure 102, a first edge 103 thereof forms a preset included angle θ with the first top surface 104. The active region 105 is located in a surface region of the semiconductor layer 101 and inside a ring formed by the plurality of field limiting ring structures 102, the active region 105 being unconnected to adjacent field limiting ring structures 102; the second edge 106 of the active region 105 forms a predetermined included angle θ with the second top surface 107. Further, the predetermined included angle θ formed in the field limiting ring structure 102 and the predetermined included angle θ formed in the active region 105 are equal, and the predetermined included angle θ may be referred to as a junction edge angle. Specifically, the preset included angle theta is 30-60 degrees, and under the angle range, the breakdown voltage of the field limiting ring terminal structure is increased greatly.
In this embodiment, since the field limiting ring structure 102 and the active region 105 are both located in the surface region, the first top surface 104 and the second top surface 107 thereof both belong to a portion of the surface of the semiconductor layer 101. Wherein surface region refers to the surface and the region below the surface.
Furthermore, the cross-sectional shapes of the field limiting ring structure 102 and the active region 105 are both inverted trapezoids, that is, the field limiting ring structure 102 and the active region 105 have inverted trapezium doping edge morphology features, and the edges of the inverted trapezoids have a certain inclination angle and form an included angle of 30-60 degrees with the corresponding part of the surface of the semiconductor layer 101.
Preferably, the structural parameters of the field limiting ring structure 102 and the active region 105 are as follows:
the depth h of the field limiting ring structure 102 is 0-1 μm, and the bottom width w is 2-5 μm; the depth h of the active region 105 is consistent with the depth h of the field limiting ring structure 102 and is 0-1 μm; the width of the bottom of the active region 105 is selected according to the actual design, and may be, for example, 200 μm or 400 μm, and this embodiment is not limited further.
The distance between the bottoms of two adjacent field limiting ring structures 102 in the plurality of field limiting ring structures 102 is: sn＝S1+ (n-1). times.d; wherein S isnIs the distance between the bottoms of two adjacent field limiting ring structures 102, and S is more than or equal to 1 mu mn≤10μm；S1The distance between the first ring and the first ring, i.e. the distance between the bottom of the active region 105 and the bottom of the first field limiting ring structure 102 close to the active region 105, is 1 μm ≤ S1Less than or equal to 2 mu m; n is the number of rings of the field limiting ring structure 102 along the direction from the active region 105 to the field limiting ring structure 102, and n is more than or equal to 5 and less than or equal to 30; d is the increment of the ring spacing, and d is more than or equal to 0.1 mu m and less than or equal to 0.5 mu m.
Specifically, the semiconductor layer 101 is made of a lightly doped N-type SiC material having the first conductivity type with a doping concentration of 3 × 1015～1×1016cm-3The thickness is 5 to 30 μm. The plurality of field limiting ring structures 102 and the active region 105 are each formed of a P-type SiC material having a second conductivity type with a doping concentration of 1 × 1018～2×1019cm-3。
In a specific embodiment, the variable angle field limiting ring termination structure is suitable for a silicon carbide power device, and further comprises a silicon carbide substrate layer 108 and a passivation layer 109.
Silicon carbide substrate layer 108 is formed with a doping concentration of 5 x 1018cm-3The thickness of the N-type SiC material is 300-400 mu m; semiconductor layer 101 is formed on silicon carbide substrate layer 108.
The passivation layer 109 covers the surface of the semiconductor layer 101 and has an insulation protection effect; the passivation layer 109 is in contact with a surface of the field limiting ring structure 102 and in contact with a surface portion of the active region 105.
The field limiting ring terminal structure in the embodiment has the inverted trapezoid doping edge shape characteristic with a variable angle, is suitable for a silicon carbide power device, sets the edge profile doping shape of an active area and each field limiting ring structure as the inverted trapezoid shape with a certain inclination angle at the edge, and equivalently increases the edge curvature radius of the PN junction edge of the field limiting ring, thereby optimizing the macroscopic electric field distribution of the device and effectively improving the breakdown voltage of the device; meanwhile, the sensitivity of the design to the process size, precision and fluctuation is weakened, the problem of device breakdown voltage fluctuation caused by ring spacing change due to process fluctuation is solved, and the reverse voltage withstanding stability of the device is improved.
Example two
On the basis of the foregoing embodiments, please refer to fig. 2 and fig. 3a to 3h in combination, where fig. 2 is a schematic flow chart of a method for manufacturing a field limiting ring terminal structure with a variable angle according to an embodiment of the present invention, and fig. 3a to 3h are schematic diagrams of a method for manufacturing a field limiting ring terminal structure with a variable angle according to an embodiment of the present invention.
The preparation method comprises the following steps:
s1, a first semiconductor layer 101 of the first conductivity type is formed by epitaxial growth on the silicon carbide substrate layer 108, see fig. 3 a.
S2, preparing a mask layer 110 having a plurality of first openings 111 on the semiconductor layer 101, wherein a predetermined angle is formed between an edge of the mask layer 110 and a bottom surface of the mask layer 110. The method specifically comprises the following steps:
s21, a mask layer 110 is deposited on the semiconductor layer 101, see fig. 3 b.The material of the mask layer 110 may be SiO2. Please refer to fig. 3 b.
S22, preparing a photoresist 112 having a plurality of second openings 113 on the surface of the mask layer 110. Please refer to fig. 3 c.
Specifically, a photoresist 112 is spin-coated on the surface of the mask layer 110, and the photoresist 112 is processed by, but not limited to, Ultraviolet (UV) light irradiation, low temperature hardening, and the like. Then, exposing and developing the photoresist 112 to form a photoresist 112 mask with a second opening 113;
s23, controlling the etching selectivity of the mask layer 110 and the photoresist 112, forming a plurality of first openings 111 on the mask layer 110. Please see fig. 3d and fig. 3 e.
Specifically, an ICP plasma etching method is adopted, and SiO is controlled by optimally adjusting ICP etching process parameters2The photoresist etching selection ratio controls the inclination angle of the opening edge of the mask layer 110, the mask layer 110 is dry etched to form a plurality of first openings 111, and then the photoresist 112 is removed, and the finally formed mask layer 110 has a plurality of first openings 111. At each first opening 111, the mask layer 110 has a feature with a slope, and a predetermined included angle θ is formed between the edge and the bottom surface, and the predetermined included angle θ is 30-60 °.
S3, performing ion implantation from the first opening 111 to the semiconductor layer 101 to form the active region 105 and the plurality of field limiting ring structures 102. Please see fig. 3f and fig. 3 g.
Specifically, ion implantation is performed based on the slope implantation mask layer 110 formed as described above, and the active region 105 having the second conductivity type and the field limiting ring structure 102 including a plurality of rings are formed on the surface of the semiconductor layer 101. The doping edge profile of the active region 105 and each field limiting ring structure 102 is a copy transfer of the edge profile of the ion implantation mask layer 110, that is, the active region 105 and the field limiting ring structure 102 having the inverted trapezoid doping edge profile feature are formed, and an included angle between the doping edge of the active region 105 and the corresponding part of the surface of the first semiconductor layer 101 (the corresponding part of the active region 105 and the corresponding part of the field limiting ring structure 102) is 30-60 °.
S4, removing the mask layer 110, and activating the implanted ions.
Specifically, the mask layer 110 is cleaned and removed, carbon film deposition protection is performed on the surface of the semiconductor layer 101, and implanted ions are activated by high-temperature annealing.
S5, removing the carbon film, covering the passivation layer 109 on the surface of the semiconductor layer 101, and contacting the passivation layer 109 with the surface of the field limiting ring structure 102 and with the surface portion of the active region 105, as shown in fig. 3 h.
In this embodiment, by controlling the inclination angle of the edge of the opening of the implantation mask layer 110, the doping profile of the edge of the active region 105 and each field limiting ring structure 102 is changed into an inverted trapezoid profile with a specific angle determined by the inclination angle of the edge of the mask layer, which not only effectively improves the breakdown voltage of the device, but also the inclination angle of the edge of the opening of the mask layer 110 can be accurately controlled, thereby weakening the sensitivity of the design to the process size, precision and fluctuation, improving the process tolerance window of the structural parameter design, reducing the complexity of the process, and thus integrally improving the reverse voltage withstanding stability of the device.
EXAMPLE III
On the basis of the above embodiments, the present embodiment further verifies the improvement of the breakdown voltage by simulating the field limiting ring terminal structure with the variable-angle inverted-trapezoidal doping edge profile feature.
The field limiting ring termination structure with quasi-rectangular doping edge profile feature involved in the simulation of the present embodiment is shown in fig. 4, and fig. 4 is a schematic cross-sectional view of a field limiting ring termination structure with quasi-rectangular doping edge profile feature provided in the prior art, and includes a substrate layer 201, a semiconductor layer 202, a plurality of field limiting rings 203, an active region 204, and a passivation layer 205. The field limiting ring termination structure in fig. 4 is fabricated using a conventional mask, and due to the limitations of the existing process, it has a nearly vertical rectangular shape, and the junction edge angle is typically 80-90 °.
On the basis of the field limiting ring terminal structure shown in fig. 1, the simulation of the field limiting ring terminal structure with the variable-angle inverted-trapezoidal doping edge profile feature in this embodiment is performed based on the following structural parameters: silicon carbide substrate layer 108 is formed with a doping concentration of 5 x 1018cm-3Thick of N-type SiC materialThe degree was 350. mu.m. The semiconductor layer 101 has a doping concentration of 6 × 1015cm-3Is made of the lightly doped N-type SiC material with the thickness of 10 mu m. The field limiting ring structure 102 and the active region 105 are formed by doping with a concentration of 1.0 × 1018cm-3P-type SiC material of (1). The junction edge angles of the active region 105 and the field limiting ring structure 102 are both 30-60 degrees. The depth h of the active region 105 and the field limiting ring structure 102 are both 0.4 μm, and the bottom width w of the field limiting ring structure 102 is 3 μm. First ring spacing S11.5 mu m, the number of rings n is 15, and the distance between the bottom of each of the rest field limiting ring structures and the bottom of the previous field limiting ring structure is Sn，Sn＝S1+(n-1)×d，d＝0.1μm，1<n<16. The thickness of the passivation layer 109 was 1 μm.
Referring to fig. 5, fig. 5 is a simulation result diagram of a variation rule of breakdown voltage with junction edge angle of the field limiting ring structure according to an embodiment of the present invention. As can be seen in fig. 5, the junction edge angle of the field limiting ring structure decreases, with a consequent increase in breakdown voltage. Therefore, compared with the traditional field limiting ring terminal device with the quasi-rectangular doping edge appearance characteristic, the breakdown voltage of the field limiting ring terminal device with the variable-angle inverted-trapezoid doping edge appearance characteristic provided by the first embodiment of the invention is improved; preferably, the average simulated breakdown voltage value of the field limiting ring terminal device with the inverted-trapezoid doping edge morphology features with the junction edge angle of 30-60 degrees is greatly improved, and the increase amplitude reaches 27%.
Referring to fig. 6, fig. 6 is a comparison graph of the lateral electric field distribution at the bottom of the ring junction when the field limiting ring termination structure with the variable-angle inverted-trapezoidal doping edge profile having the junction edge angle of 30 ° and the field limiting ring termination structure with the quasi-rectangular doping edge profile having the junction edge angle of 85 ° provided by the embodiment of the present invention are in reverse breakdown. As can be seen from fig. 6, under the same condition as the parameters (ring width, spacing, etc.) of the field limiting ring terminal structure in fig. 1, the edge curvature radius of the bottom of the ring junction is smaller due to the quasi-rectangular doping edge morphology of the conventional field limiting ring structure, the maximum peak electric field is located at the edge of the active region of the main junction, and the macro electric field is very unevenly distributed in the field limiting ring terminal region, which means that the concentration of the main electric field is not sufficiently relieved, the number of effective rings depleted and pierced through is small, and the breakdown voltage is low. In contrast, an inverted trapezoidal doping edge with a preferably variable angle can be equivalent to an increase in the radius of curvature of the bottom of the ring junction, which improves the electric field distribution throughout the field limiting ring termination region: the maximum peak electric field is positioned in the field limiting ring terminal area, the main junction electric field is concentrated and relieved, and the macroscopic electric field is uniformly distributed, so that the breakdown voltage of the device is effectively improved. Therefore, the field limiting ring terminal with the inverted-trapezoidal doping edge morphology feature with the optimized variable angle provided by the figure 1 equivalently increases the edge curvature radius of the bottom of the ring junction, so that the macroscopic electric field distribution of the device is optimized, and the reverse withstand voltage of the device is effectively improved.
Example four
On the basis of the above embodiments, the present embodiment further verifies the reverse voltage stability by simulating the field limiting ring terminal structure with the variable-angle inverted-trapezoidal doping edge profile feature.
Referring to fig. 4, a related conventional field limiting ring terminal structure with a quasi-rectangular doped edge profile feature is shown.
Based on the field limiting ring terminal structure of the first embodiment, the simulation of the field limiting ring terminal structure with the variable-angle inverted-trapezoidal doping edge morphology feature in the first embodiment is performed based on the following structural parameters: silicon carbide substrate layer 108 is formed with a doping concentration of 5 x 1018cm-3Is 350 μm thick. The semiconductor layer 101 has a doping concentration of 6 × 1015cm-3Is made of the lightly doped N-type SiC material with the thickness of 10 mu m. The field limiting ring structure 102 and the active region 105 are formed by doping with a concentration of 1.0 × 1018cm-3P-type SiC material of (1). The junction edge angles of the active region 105 and the field limiting ring structure 102 are both 30-60 degrees. The depth h of the active region 105 and the field limiting ring structure 102 are both 0.4 μm, and the bottom width w of the field limiting ring structure 102 is 3 μm. First ring spacing S11.2 μm, the number of rings n is 10, and the distance between the bottom of each of the remaining field limiting ring structures 102 and the bottom of the preceding field limiting ring structure 102 is Sn，Sn＝S1+(n-1)×d，d＝0.2μm，1<n<11. Thickness of passivation layer 109The degree was 1 μm.
Referring to fig. 7, fig. 7 shows simulated breakdown voltages of a field limiting ring terminal structure with variable-angle inverse-trapezoidal doping edge profile having a junction edge angle of 45 ° and a field limiting ring terminal structure with quasi-rectangular doping edge profile having a junction edge angle of 85 ° according to the first ring spacing S of the field limiting rings in an embodiment of the present invention1Comparative schematic of the changes. As can be seen in FIG. 7, the conventional field limiting ring termination structure is at S11.2 μm, a breakdown voltage of 1.4kV at S1The breakdown voltage changes greatly under the simulated process size fluctuation of increasing (1.5 mu m) or decreasing (1 mu m), and S1The breakdown voltage at 1.5 μm was 1.27kV, which was reduced by about 10%. And a field limiting ring structure device with the preferred variable-angle inverted-trapezoidal doping edge profile characteristic is arranged at S11.2 μm, a breakdown voltage of 1.55kV at S1The change of breakdown voltage is smaller under the simulated process size fluctuation of increasing (1.5 mu m) or reducing (1 mu m), and S is1The breakdown voltage was 1.48kV at 1.5 μm, which was only about 4.5% lower. In addition, the breakdown voltage of the field limiting ring structure device with the inverted trapezoidal doping edge profile feature with the optimized variable angle is within any S1The lower is larger than the conventional structure. Therefore, the field limiting ring structure with the inverted trapezoidal doping edge morphology features with the optimized variable angle not only can effectively optimize electric field distribution and improve reverse breakdown voltage of the device, but also effectively inhibits the breakdown voltage of the device along with the first ring spacing S1Degradation attenuation caused by fluctuation has important design value for the preparation of actual device technology: the sensitivity of the design to the process size, the precision and the fluctuation is weakened, namely, the process tolerance window of the structural parameter design is improved, the process complexity is reduced, and therefore the reverse voltage resistance stability of the device is integrally improved.
EXAMPLE five
On the basis of the above embodiments, the present embodiment further provides two field limiting ring terminal structures having an inverted trapezoidal doping edge profile feature with a variable angle, the two field limiting ring terminal structures have different structural parameters, and the specific structures thereof are both shown in fig. 1.
The first method comprises the following steps: based on a device design with a breakdown voltage of 700V level and a variable angle field limiting ring terminal, a silicon carbide substrate layer 108 is formed by doping with a concentration of 5 x 1018cm-3Is 300 μm thick. The semiconductor layer 101 is formed by doping with a concentration of 1 × 1016cm-3Is made of the lightly doped N-type SiC material with the thickness of 5 mu m. The field limiting ring structure 102 and the active region 105 are formed by doping with a concentration of 1.0 × 1019cm-3P-type SiC material of (1). The depths h of the active region 105 and the field limiting ring structure 102 are both 0.8 μm, and the junction edge angles are both 45 degrees; the bottom width w of the field limiting ring structure 102 is 5 μm; first ring spacing S11.8 μm, the number of rings n is 7, and the distance between the bottom of each of the remaining field limiting ring structures 102 and the bottom of the preceding field limiting ring structure 102 is Sn，Sn＝S1+(n-1)×d，d＝0.5μm，1<n<8. The thickness of the passivation layer 109 was 1 μm.
And the second method comprises the following steps: based on a device design with a breakdown voltage of 3300V grade and a variable angle field limiting ring terminal, silicon carbide substrate layer 108 is formed by doping with a concentration of 5 x 1018cm-3Is 400 μm thick. The semiconductor layer 101 has a doping concentration of 3 × 1015cm-3Is made of the lightly doped N-type SiC material with the thickness of 30 mu m. The field limiting ring structure 102 and the active region 105 are formed by doping with a concentration of 5.0 × 1018cm-3P-type SiC material of (1). The junction edge angles of the active region 105 and the field limiting ring structure 102 are both 60 degrees, and the depths h are both 1 μm; the bottom width w of the field limiting ring structure 102 is 4 μm; first ring spacing S 12 μm, the number of rings n is 25, and the distance between the bottom of each of the remaining field limiting ring structures 102 and the bottom of the preceding field limiting ring structure 102 is Sn，Sn＝S1+(n-1)×d，d＝0.1μm，1<n<26. The thickness of the passivation layer 109 was 1 μm.
The field limiting ring terminal structure in the embodiment is provided with different structural parameters, so that different breakdown voltages can be realized, and different design requirements can be met.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (8)
1. A field limiting ring termination structure having a variable angle, comprising:
a semiconductor layer (101);
the field limiting ring structures (102) are distributed in the surface area of the semiconductor layer (101) at intervals, a preset included angle is formed between a first edge (103) of each field limiting ring structure (102) and a first top surface (104) of each field limiting ring structure (102), and the preset included angle is 30-60 degrees;
the active region (105) is located in the surface area of the semiconductor layer (101) and located inside a ring formed by the field limiting ring structures (102), and the preset included angle is formed between the second edge (106) of the active region (105) and the second top surface (107) of the active region (105).
2. The variable angle field limiting ring termination structure of claim 1, wherein a cross-sectional shape of the field limiting ring structure (102) and a cross-sectional shape of the active region (105) are each inverted trapezoidal.
3. The variable angle field limiting ring termination structure of claim 2, wherein the depth of the field limiting ring structure (102) and the depth of the active region (105) are both 0-1 μm, and the width of the bottom of the field limiting ring structure (102) is 2-5 μm.
4. The variable angle field limiting ring termination structure of claim 1, wherein the distance between the bottoms of two adjacent field limiting ring structures (102) is:
Sn＝S1+(n-1)×d
wherein S isnIs the distance between the bottoms of two adjacent field limiting ring structures (102), and S is more than or equal to 1 mu mn≤10μm，S1Is the distance between the head ring and the ring，1μm≤S1Is less than or equal to 2 mu m, n is the number of rings of the field limiting ring structure (102) along the direction from the active region (105) to the field limiting ring structure (102), n is less than or equal to 30 and is greater than or equal to 5, d is the increment of the ring spacing, and d is less than or equal to 0.1 mu m and less than or equal to 0.5 mu m.
5. The variable angle field limiting ring termination structure of claim 1, wherein the doping concentration of the active region (105) and the doping concentration of the field limiting ring structure (102) are each 1 x 1018～2×1019cm-3。
6. The variable angle field limiting ring termination structure of claim 1, further comprising:
a silicon carbide substrate layer (108), the semiconductor layer (101) being located on the silicon carbide substrate layer (108);
a passivation layer (109) on the semiconductor layer (101) and in contact with a surface portion of the active region (105).
7. A method for preparing a field limiting ring terminal structure with a variable angle is characterized by comprising the following steps:
preparing a mask layer (110) with a plurality of first openings (111) on the semiconductor layer (101), wherein a preset included angle is formed between the edge of the mask layer (110) and the bottom surface of the mask layer (110), and the preset included angle is 30-60 degrees;
performing ion implantation from the first opening (111) to the semiconductor layer (101) to form an active region (105) and a plurality of field limiting ring structures (102), wherein the preset included angle is formed between a first edge (103) of the field limiting ring structure (102) and a top surface (104) of the field limiting ring structure (102), and between a second edge (106) of the active region (105) and a top surface (107) of the active region (105);
the mask layer (110) is removed and implanted ions are activated.
8. The method of claim 7, wherein forming a mask layer (110) having a plurality of first openings (111) on the semiconductor layer (101), wherein forming a predetermined angle between an edge of the mask layer (110) and a bottom surface of the mask layer (110) comprises:
growing the mask layer (110) on the semiconductor layer (101);
preparing a photoresist (112) with a plurality of second openings (113) on the surface of the mask layer (110);
and controlling the etching selection ratio of the mask layer (110) to the photoresist (112), and etching the mask layer (110) to form a plurality of first openings (111), so that the preset included angle is formed between the edge of the mask layer (110) and the bottom surface of the mask layer (110).
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04321274A (en) * | 1991-04-19 | 1992-11-11 | Shindengen Electric Mfg Co Ltd | Schottky barrier semiconductor device |
| CN106783956A (en) * | 2016-12-27 | 2017-05-31 | 西安电子科技大学 | Groove field limiting ring terminal structure and preparation method with side wall variable-angle |
| CN107591324A (en) * | 2017-08-24 | 2018-01-16 | 西安电子科技大学 | The preparation method and structure of knot terminal terminal extension structure |
| CN107623026A (en) * | 2016-07-14 | 2018-01-23 | 丰田自动车株式会社 | Semiconductor device and its manufacture method |
-
2019
- 2019-08-30 CN CN201910816910.XA patent/CN110707147A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04321274A (en) * | 1991-04-19 | 1992-11-11 | Shindengen Electric Mfg Co Ltd | Schottky barrier semiconductor device |
| CN107623026A (en) * | 2016-07-14 | 2018-01-23 | 丰田自动车株式会社 | Semiconductor device and its manufacture method |
| CN106783956A (en) * | 2016-12-27 | 2017-05-31 | 西安电子科技大学 | Groove field limiting ring terminal structure and preparation method with side wall variable-angle |
| CN107591324A (en) * | 2017-08-24 | 2018-01-16 | 西安电子科技大学 | The preparation method and structure of knot terminal terminal extension structure |
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