CN116504844A - High-power surge protection device and preparation method thereof - Google Patents
High-power surge protection device and preparation method thereof Download PDFInfo
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- CN116504844A CN116504844A CN202310462330.1A CN202310462330A CN116504844A CN 116504844 A CN116504844 A CN 116504844A CN 202310462330 A CN202310462330 A CN 202310462330A CN 116504844 A CN116504844 A CN 116504844A
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- 238000002360 preparation method Methods 0.000 title description 7
- 238000009792 diffusion process Methods 0.000 claims abstract description 147
- 239000002184 metal Substances 0.000 claims abstract description 65
- 229910052751 metal Inorganic materials 0.000 claims abstract description 65
- 238000002161 passivation Methods 0.000 claims abstract description 65
- 239000000758 substrate Substances 0.000 claims abstract description 55
- 230000000903 blocking effect Effects 0.000 claims abstract description 35
- 230000004888 barrier function Effects 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims description 29
- 238000005530 etching Methods 0.000 claims description 16
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 12
- 229910052796 boron Inorganic materials 0.000 claims description 12
- 229920002120 photoresistant polymer Polymers 0.000 claims description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 230000003647 oxidation Effects 0.000 claims description 8
- 238000007254 oxidation reaction Methods 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 6
- 238000000576 coating method Methods 0.000 claims description 6
- 238000005498 polishing Methods 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims 1
- 229910000679 solder Inorganic materials 0.000 abstract description 38
- 230000015572 biosynthetic process Effects 0.000 abstract description 7
- 238000003466 welding Methods 0.000 abstract description 5
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 230000002035 prolonged effect Effects 0.000 abstract description 3
- 239000004065 semiconductor Substances 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 21
- 239000000126 substance Substances 0.000 description 12
- 230000002457 bidirectional effect Effects 0.000 description 9
- 239000012466 permeate Substances 0.000 description 7
- 239000004020 conductor Substances 0.000 description 4
- 238000005476 soldering Methods 0.000 description 3
- 230000001052 transient effect Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 238000001962 electrophoresis Methods 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 208000025274 Lightning injury Diseases 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000012536 packaging technology Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/86—Types of semiconductor device ; Multistep manufacturing processes therefor controllable only by variation of the electric current supplied, or only the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched
- H01L29/861—Diodes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
- H01L23/31—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the arrangement or shape
- H01L23/3157—Partial encapsulation or coating
- H01L23/3171—Partial encapsulation or coating the coating being directly applied to the semiconductor body, e.g. passivation layer
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66083—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by variation of the electric current supplied or the electric potential applied, to one or more of the electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. two-terminal devices
- H01L29/6609—Diodes
- H01L29/66098—Breakdown diodes
- H01L29/66113—Avalanche diodes
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
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- Condensed Matter Physics & Semiconductors (AREA)
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- Manufacturing & Machinery (AREA)
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Abstract
The invention relates to the technical field of semiconductor devices, in particular to a high-power surge protection device, which comprises: the device comprises a substrate, a diffusion layer and a metal layer which are sequentially formed from the center of the device outwards, wherein two ends of the substrate and the diffusion layer are respectively etched to form a pair of continuous arc corners; a passivation area is formed on each arc corner; the top of the passivation region is higher than the diffusion layer; a blocking area is formed at an included angle between the top of the passivation area and the diffusion layer; the area between the two barrier regions is used to form the metal layer. The invention has the beneficial effects that: the blocking area is processed through the included angle between the passivation area and the diffusion layer, and the blocking area is adopted to limit the formation area of the metal layer, so that a concave structure for containing solder paste is formed through the blocking area and the metal layer in the subsequent welding, the problem of leakage current increase in the device caused by the overflow of the solder paste to the passivation area at high temperature is avoided, and the service life of the device is prolonged.
Description
Technical Field
The invention relates to the technical field of semiconductor devices, in particular to a high-power surge protection device and a preparation method thereof.
Background
The high-power transient surge protection device is a clamp type diode for releasing transient high voltage, which is realized by utilizing a PIN structure, PNP or NPN structure based on the principle of avalanche breakdown, and can clamp surge voltage caused by lightning stroke, plug and the like at a very low level in a short time. The protection device is used for protecting the main chip at the rear end and avoiding damage to the main chip caused by overvoltage. Along with the development of electric vehicles, various power interfaces on vehicles are more and more, and the electric vehicles are mainly divided into vehicle-mounted domain control applications and lamp control applications, and the electric vehicles have higher requirements on the reliability of devices because of the personal safety of certain applications of domain control.
In the prior art, a large number of high-power transient surge protection devices applied to a power supply circuit exist. The device shown in fig. 1 is a typical high-power surge protection device suitable for a vehicle, and instead, meets the load rejection requirement of IEO-16750, and meets the requirement of ensuring reliability by forming a groove structure at four end points of the device A1 respectively, forming a passivation layer A2 in the groove structure by coating or electrophoresis of lead-containing glass powder, and forming a finished product of corresponding package by combining a packaging technology of printing tin paste or soldering tin sheets.
However, in practice, the inventors have found that the device shown in fig. 1 has a relatively flat metal layer A3 on top of it, and that the metal layer A3 is used to apply solder paste A4. During the soldering process, the solder paste A4 easily flows at a high temperature, so that the solder paste A4 overflows from the end point of the metal layer A3 onto the passivation layer A2. Over time, the conductive material in the solder paste A4 penetrates through the passivation layer A2 to the device or junction region, so that the leakage current in the region gradually increases until the device is shorted, and the service life of the device is affected.
Disclosure of Invention
Aiming at the problems in the prior art, a high-power surge protection device is provided; on the other hand, a preparation method for preparing the high-power surge protection device is also provided.
The specific technical scheme is as follows:
the high-power surge protection device comprises a substrate, a diffusion layer and a metal layer which are sequentially formed from the center of the device outwards, and is characterized in that two ends of the substrate and the diffusion layer are respectively etched to form a pair of continuous arc corners;
a passivation area is formed on each arc corner;
the top of the passivation region is higher than the diffusion layer;
a blocking area is formed at an included angle between the top of the passivation area and the diffusion layer;
the area between the two barrier regions is used to form the metal layer.
Preferably, the substrate has a first doping type;
the diffusion layer includes:
a first diffusion layer formed over the substrate, the first diffusion layer having a second doping type;
a second diffusion layer formed under the substrate, the second diffusion layer having the second doping type;
the metal layer includes:
a top metal layer formed over the first diffusion layer in a region between an adjacent pair of the barrier regions;
and a bottom metal layer formed below the second diffusion layer in a region between an adjacent pair of the barrier regions.
Preferably, the substrate has a first doping type;
the diffusion layer includes:
a third diffusion layer formed over the substrate, the first diffusion layer having a second doping type;
the metal layer includes:
a top metal layer formed over the first diffusion layer in a region between an adjacent pair of the barrier regions;
and a bottom metal layer covering under the substrate.
Preferably, the lateral thickness of the blocking region is greater than 10um.
A preparation method of a high-power surge protection device is used for preparing the high-power surge protection device and comprises the following steps:
step S1: forming a diffusion layer on a substrate;
step S2: etching the two ends of the substrate and the diffusion layer respectively to form an arc corner, and then forming a passivation region on the arc corner;
step S3: forming the blocking region according to an included angle between the diffusion layer and the passivation region;
step S4: and forming a metal layer between the barrier regions.
Preferably, the step S1 includes:
step S11: double-sided polishing and cleaning are carried out on the substrate;
step S12: performing gaseous boron pre-diffusion treatment on a processing area of the surface of the substrate, wherein the processing area is scheduled to form the diffusion layer;
step S13: and carrying out boron re-expansion treatment on the processing area to form the diffusion layer.
Preferably, in the step S12, the temperature of the gaseous boron pre-diffusion treatment is 1085 ℃ for 50 minutes;
in the step S13, the temperature of the boron re-expansion treatment is 1250 ℃.
Preferably, the step S2 includes:
step S21: etching two ends of the diffusion layer respectively to form a pair of arc corners;
step S22: and forming the passivation areas on each arc corner respectively.
Preferably, the step S3 includes:
step S31: etching the surface of the diffusion layer so that the top end of the passivation region is higher than the diffusion layer;
step S32: coating photoresist on the diffusion layer to respectively generate growth windows at two ends of the diffusion layer;
step S33: and respectively growing the blocking areas in each growth window, and then removing the photoresist.
Preferably, in step S33, the barrier regions are alternately grown in the growth window by using a dry oxygen oxidation process and a wet oxygen oxidation process, respectively.
The technical scheme has the following advantages or beneficial effects: the blocking area is processed through the included angle between the passivation area and the diffusion layer, and the blocking area is adopted to limit the formation area of the metal layer, so that a concave structure for containing solder paste is formed through the blocking area and the metal layer in the subsequent welding, the problem of leakage current increase in the device caused by the overflow of the solder paste to the passivation area at high temperature is avoided, and the service life of the device is prolonged.
Drawings
Embodiments of the present invention will now be described more fully with reference to the accompanying drawings. The drawings, however, are for illustration and description only and are not intended as a definition of the limits of the invention.
FIG. 1 is a schematic diagram of a prior art device;
FIG. 2A is a schematic diagram of a bi-directional device in accordance with an embodiment of the present invention;
FIG. 2B is a schematic diagram of a unidirectional device in an embodiment of the invention;
FIG. 3A is a schematic illustration of a bi-directional device coating solder paste in accordance with an embodiment of the present invention;
FIG. 3B is a schematic illustration of a unidirectional device coated solder paste in accordance with an embodiment of the present invention;
FIG. 4A is a schematic diagram of a bi-directional device in accordance with an embodiment of the present invention;
FIG. 4B is a schematic diagram of a unidirectional device in an embodiment of the invention;
FIG. 5 is a schematic diagram of a preparation method according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of the substep of step S1 in an embodiment of the present invention;
FIG. 7A is a schematic diagram of a bi-directional device at the end of step S13 in an embodiment of the present invention;
FIG. 7B is a schematic diagram of a unidirectional device at the end of step S13 in an embodiment of the invention;
FIG. 8 is a schematic diagram of the substep of step S2 in an embodiment of the present invention;
FIG. 9A is a schematic diagram of a bi-directional device at step S21 according to an embodiment of the present invention;
FIG. 9B is a schematic diagram of a unidirectional device at step S21 in an embodiment of the present invention;
FIG. 10A is a schematic diagram of a bi-directional device at step S22 according to an embodiment of the present invention;
FIG. 10B is a schematic diagram of a unidirectional device at step S22 in an embodiment of the present invention;
FIG. 11 is a schematic diagram showing the sub-steps of step S3 in an embodiment of the present invention;
FIG. 12A is a schematic diagram of a bi-directional device at step S31 in an embodiment of the present invention;
FIG. 12B is a schematic diagram of a unidirectional device at step S31 in an embodiment of the present invention;
FIG. 13A is a schematic diagram of a bi-directional device at step S32 according to an embodiment of the present invention;
FIG. 13B is a schematic diagram of a unidirectional device at step S32 in an embodiment of the present invention;
FIG. 14A is a schematic diagram of a bi-directional device at step S33 according to an embodiment of the present invention;
fig. 14B is a schematic diagram of a unidirectional device at step S33 in an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The invention is further described below with reference to the drawings and specific examples, which are not intended to be limiting.
The invention comprises the following steps:
the high-power surge protection device comprises a substrate 1, a diffusion layer 2 and a metal layer 3 which are sequentially formed from the center of the device outwards, wherein two ends of the substrate 1 and the diffusion layer 2 are respectively etched to form a pair of continuous arc corners;
a passivation area 4 is formed on each arc corner;
the top of the passivation region 4 is higher than the diffusion layer 2;
a blocking region 5 is formed at an included angle between the top of the passivation region 4 and the diffusion layer 2;
the region between the two barrier regions 5 is used to form the metal layer 3.
Specifically, for the high-power surge protection device in the prior art, solder paste overflows into the passivation layer during the use process, so that conductive substances in the solder paste permeate into the device or junction regions to cause the problem of electric leakage, in this embodiment, the top of the passivation region 4 is higher than the diffusion layer 2 by etching the diffusion layer 2, and an included angle is formed between two end points of the diffusion layer 2. The included angle is used for growing the blocking area 5, so that the blocking area 5 can grow upwards from the diffusion layer 2 along the side wall of the passivation area 4, and further wraps the inner wall of the passivation area 4 in the center direction of the device, so that isolation is formed. The area between the two blocking areas 5 is used for forming the metal layer 3 in the subsequent process, and two ends of the formed metal layer 3 are wrapped by the blocking areas 5 to form a concave area for containing solder paste. As shown in fig. 3, the above structure can effectively limit the flow of solder paste during the soldering process, avoid the conductive material diffusion caused by the contact of the solder paste to the passivation region 4, further avoid the problem of electric leakage caused by the penetration of the conductive material into the device, and improve the reliability of the device.
In implementation, the device structure described above may be applied to a high-power surge protection device of a bi-directional structure as shown in fig. 2A or a unidirectional structure as shown in fig. 2B. In fig. 2A, diffusion layers are respectively disposed on the upper and lower surfaces of the substrate 1, then arc corners are required to be etched on both the front and back surfaces of the device to form passivation regions 4, and then barrier regions 5 are respectively grown on the sidewalls of the passivation regions 4 to define formation regions of the metal layer 3. In fig. 2B, the diffusion layer 2 is only arranged above the substrate 1, so that only arc corners need to be etched above the device and passivation regions 4 are formed, and then barrier regions 5 are respectively grown on the side walls of the passivation regions 4; at this time, the barrier region 5 on the upper surface of the device is used to define the formation region of the metal layer 3 on top, and the lower surface of the device is formed with the complete metal layer 3 on the lower surface of the substrate 1 by the prior art because the barrier region 5 is not present.
By adopting the above structure, the device is brought into the state shown in fig. 3A and 3B when the solder paste is applied. In the device of the bidirectional structure shown in fig. 3A, the solder paste only covers the areas where the top metal layer and the bottom metal layer are located, and is limited by the blocking area 5, and is not in contact with the passivation areas 4 at four corners, so that the problem of diffusion of conductive substances in the passivation areas 4 is avoided; fig. 3B shows a unidirectional device, in which the solder paste is limited by the blocking regions 5 in the upper surface of the device, and does not contact the passivation regions 4 on both sides, while the underlying metal layer 3 is the same as the prior art, and there is no overflow phenomenon of the solder paste at the end points, but there is no passivation region 4 and diffusion layer 2, so that the conductive material in the solder paste does not diffuse to the PN junction between the substrate 1 and diffusion layer 2 to cause leakage.
In a preferred embodiment, the barrier region has a lateral thickness greater than 10um.
Specifically, for the high-power surge protection device in the prior art, solder paste can overflow into the passivation layer in the use process, so that conductive substances in the solder paste permeate into the device or junction areas to cause the problem of electric leakage, in the embodiment, the compact blocking area 5 is prepared, the transverse thickness of the blocking area 5 is controlled to be larger than 10um, the conductive substances in the solder paste are prevented from being transversely diffused into the passivation area 4, and the reliability of the device is improved.
In a preferred embodiment, as shown in fig. 4A, the substrate 1 has a first doping type;
the diffusion layer 2 includes:
a first diffusion layer 21, the first diffusion layer 21 being formed over the substrate 1, the first diffusion layer 21 having a second doping type;
a second diffusion layer 22, the second diffusion layer 22 being formed under the substrate 1, the second diffusion layer 22 having a second doping type;
the metal layer 3 includes:
a top metal layer 31, the top metal layer 31 being formed over the first diffusion layer 21 in a region between an adjacent pair of barrier regions 5;
a bottom metal layer 32. The bottom metal layer 32 is formed under the second diffusion layer 22 in a region between an adjacent pair of barrier regions 5.
Specifically, for the high-power surge protection device in the prior art, solder paste overflows into the passivation layer during the use process, so that conductive substances in the solder paste permeate into the device or junction regions to cause the problem of electric leakage, in this embodiment, a pair of barrier regions 5 are formed on the first diffusion layer 21 and the second diffusion layer 22 on both sides of the device in advance, so that the formation regions of the top metal layer 31 and the bottom metal layer 32 are defined, so that the top metal layer 31 and the bottom metal layer 32 can be formed in the surrounding regions of the barrier regions 5, and the problem of solder paste overflow during the subsequent welding process is avoided.
In a preferred embodiment, as shown in fig. 4B, the substrate 1 has a first doping type;
the diffusion layer 2 includes:
a third diffusion layer 23, the third diffusion layer 23 being formed over the substrate 1, the third diffusion layer having a second doping type;
the metal layer 3 includes:
a top metal layer 31, the top metal layer 31 being formed over the first diffusion layer 23 in a region between an adjacent pair of barrier regions 5;
a bottom metal layer 32, the bottom metal layer 32 covering the underside of the substrate 1.
Specifically, for the high-power surge protection device in the prior art, solder paste overflows into the passivation layer during the use process, so that conductive substances in the solder paste permeate into the device or junction regions to cause the problem of electric leakage, in this embodiment, a pair of barrier regions 5 are formed in advance on the third diffusion layer 23 on the upper surface of the device, so that the formation region of the top metal layer 31 is defined, the top metal layer 31 can be formed in the surrounding region of the barrier regions 5, and the problem of solder paste overflow during the subsequent welding process is avoided.
A preparation method of a high-power surge protection device is used for preparing the high-power surge protection device, as shown in fig. 5, and comprises the following steps:
step S1: forming a diffusion layer 2 on a substrate 1;
step S2: etching the two ends of the substrate 1 and the diffusion layer 2 respectively to form arc corners, and then forming passivation areas 4 on the arc corners;
step S3: forming a blocking region 5 according to the included angle between the diffusion layer 2 and the passivation region 4;
step S4: a metal layer 3 is formed between the barrier regions 5.
Specifically, for the high-power surge protection device in the prior art, solder paste overflows into the passivation layer during the use process, so that conductive substances in the solder paste permeate into the device or junction area to cause the problem of electric leakage, in this embodiment, before the metal layer 3 is formed, the blocking area 5 is prepared in advance through an included angle between the passivation area 4 and the diffusion layer 2, so that isolation is formed between the metal layer 3 and the passivation area 4, and the solder paste on the metal layer 3 is prevented from contaminating the passivation area 4 to cause diffusion of the conductive substances.
In a preferred embodiment, as shown in fig. 6, step S1 includes:
step S11: double-sided polishing and cleaning are carried out on the substrate 1;
step S12: performing gaseous boron pre-diffusion treatment on a processing area of the surface of the substrate 1, wherein the processing area is scheduled to form a diffusion layer 3;
when the high-power surge protection device is a bidirectional structure device, the processing areas are respectively arranged on the upper surface and the lower surface of the substrate 1;
when the high-power surge protection device is a unidirectional structure device, the processing area is arranged on the upper surface of the substrate 1;
step S13: performing boron re-expansion treatment on the processing area to form a diffusion layer 2;
as shown in fig. 7A, when the high-power surge protection device is a bidirectional structure device, the diffusion layer 2 includes a first diffusion layer 21 and a second diffusion layer 22 provided on the upper surface of the substrate 1;
as shown in fig. 7B, when the high-power surge protection device is a unidirectional structure device, the diffusion layer 2 includes a third diffusion layer 23 provided on the upper surface of the substrate 1.
Specifically, in order to achieve a better yield of devices, in this embodiment, mechanical stress generated in the substrate 1 due to dicing of the substrate sheet is removed by mechanically polishing the substrate 1 in advance. Subsequently, the substrate 1 is cleaned with the RCA cleaning solution, thereby achieving a better cleanliness of the substrate 1.
In one embodiment, the thickness of the substrate sheet is 340 um.+ -.10 um and the thickness of the mechanical polishing is about 20um, so as to remove the mechanical stress better.
In a preferred embodiment, in step S12, the gaseous boron pre-diffusion treatment is carried out at a temperature of 1085 ℃ for a period of 50 minutes;
in step S13, the temperature of the boron re-expansion treatment is 1250 ℃.
In a preferred embodiment, as shown in fig. 8, step S2 includes:
step S21: etching the two ends of the diffusion layer 2 respectively to form a pair of arc corners;
as shown in fig. 9A, when the high-power surge protection device is a bidirectional structure device, two pairs of arc corners are formed at two ends of the first diffusion layer 21 and two ends of the second diffusion layer 22 respectively;
as shown in fig. 9B, when the high-power surge protection device is a unidirectional structure device, a pair of circular arc corners are formed at both ends of the third diffusion layer 23.
Step S22: passivation regions 4 are respectively formed on each arc corner;
as shown in fig. 10A, when the high-power surge protection device is a bidirectional structure device, four passivation regions 4 are formed on the arc corners at both ends of the first diffusion layer 21 and the arc corners at both ends of the second diffusion layer 22, respectively;
as shown in fig. 10B, when the high-power surge protection device is a unidirectional structure device, two passivation regions 4 are formed on the circular arc corners at both ends of the third diffusion layer 23.
Specifically, in order to achieve better load rejection performance of the device, in this embodiment, deep trench processes are selected to be used for etching on the end points of the first diffusion layer 21 and the second diffusion layer 22 respectively, so as to form a plurality of arc corners, and then a passivation region 4 is formed on the arc corners in a coating or electrophoresis mode to wrap the PN junction region of the device, so that better electrical performance is achieved.
In a preferred embodiment, as shown in fig. 11, step S3 includes:
step S31: etching the surface of the diffusion layer 2 so that the top end of the passivation region 4 is higher than the diffusion layer 2;
as shown in fig. 12A, when the high-power surge protection device is a bidirectional structure device, etching is performed on the first diffusion layer 21 and the second diffusion layer 22, respectively, and the thicknesses of the first diffusion layer 21 and the second diffusion layer 22 are reduced so that the top end of the passivation region 4 is higher than the first diffusion layer 21 or the second diffusion layer 22;
as shown in fig. 12B, when the high-power surge protection device is a unidirectional structure device, etching is performed on the third diffusion layer 23, and the thickness of the first diffusion layer 23 is reduced so that the top end of the passivation region 4 is higher than the third diffusion layer 23.
Step S32: coating photoresist 6 on the diffusion layer 2 to generate growth windows at two ends of the diffusion layer 2 respectively;
as shown in fig. 13A, when the high-power surge protection device is a bidirectional structure device, photoresist 6 is coated on the first diffusion layer 21 and the second diffusion layer 22, respectively, so as to define four growth windows at both ends of the first diffusion layer 21 and both ends of the second diffusion layer 22;
as shown in fig. 13B, when the high power surge protection device is a unidirectional structure device, a photoresist 6 is coated on the third diffusion layer 23 to define two growth windows at both ends of the third diffusion layer 23.
Step S33: respectively growing a blocking region 5 in each growth window, and then removing the photoresist 6;
when the high-power surge protection device is a bidirectional structure device, the photoresist 6 is removed to form a device shape shown in fig. 14A;
when the high-power surge protection device is a unidirectional structure device, the photoresist 6 is removed to form a device morphology as shown in fig. 14B.
Specifically, for the high-power surge protection device in the prior art, solder paste overflows into the passivation layer during the use process, so that conductive substances in the solder paste permeate into the device or junction area to cause the problem of electric leakage, in this embodiment, after the passivation region 4 is formed, shallow trench etching is performed on the surfaces of the first diffusion layer 21 and the second diffusion layer 22 respectively, so that the top end of the passivation region 4 is higher than the first diffusion layer 21 or the second diffusion layer 22. During etching, the etching depth does not exceed the peak point of the gaussian concentration distribution in the first diffusion layer 21 or the second diffusion layer 22. Then, a photoresist 6 with a certain length is coated on the central area of the first diffusion layer 21 and the second diffusion layer 22 according to the width of the barrier region 5 to be prepared, and a growth window is formed at the included angle between the diffusion layer and the passivation region 4, so as to facilitate the growth of the barrier region 5 along the side wall of the passivation region 4. The material of the blocking region 5 is preferably silicon dioxide, but may be implemented by other materials.
In a preferred embodiment, in step S33, the barrier regions 5 are grown alternately in the growth window using a dry oxygen oxidation process and a wet oxygen oxidation process, respectively.
Specifically, aiming at the high-power surge protection device in the prior art, solder paste overflows into a passivation layer in the using process, so that conductive substances in the solder paste permeate into a device or junction area to cause the problem of electric leakage, in the embodiment, a dense barrier area 5 with an internal interface is formed by alternately growing the barrier area 5 in a growth window by adopting a dry oxygen oxidation process and a wet oxygen oxidation process, thereby realizing a better barrier effect on the conductive substances and greatly reducing the diffusion speed of the conductive substances in a medium.
In a preferred embodiment, step S4 comprises: silver plating or electroless nickel plating between a pair of barrier regions 5 to form a metal layer 3;
specifically, when the high-power surge protection device is a bidirectional structure device, a pair of blocking regions 5 are respectively provided at both ends of the first diffusion layer 21 and both ends of the second diffusion layer 22, and a region between each pair of blocking regions 5 is a region for forming the top metal layer 31 or the bottom metal layer 32, in which the device morphology as shown in fig. 4A is formed using the above-described process.
When the high-power surge protection device is a unidirectional structure device, a pair of blocking regions 5 are provided at both ends of the third diffusion layer 21, and a region between the blocking regions 5 is a region for forming the top metal layer 31, in which the top metal layer 31 is formed by the above process, and at the same time, a bottom metal layer 32 covering the entire lower surface of the substrate 1 is formed under the substrate 1 by using the prior art, so as to form the device morphology as shown in fig. 4B.
The invention has the beneficial effects that: the blocking area is processed through the included angle between the passivation area and the diffusion layer, and the blocking area is adopted to limit the formation area of the metal layer, so that a concave structure for containing solder paste is formed through the blocking area and the metal layer in the subsequent welding, the problem of leakage current increase in the device caused by the overflow of the solder paste to the passivation area at high temperature is avoided, and the service life of the device is prolonged.
The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the embodiments and scope of the present invention, and it should be appreciated by those skilled in the art that equivalent substitutions and obvious variations may be made using the description and illustrations of the present invention, and are intended to be included in the scope of the present invention.
Claims (10)
1. The high-power surge protection device comprises a substrate, a diffusion layer and a metal layer which are sequentially formed from the center of the device outwards, and is characterized in that two ends of the substrate and the diffusion layer are respectively etched to form a pair of continuous arc corners;
a passivation area is formed on each arc corner;
the top of the passivation region is higher than the diffusion layer;
a blocking area is formed at an included angle between the top of the passivation area and the diffusion layer;
the area between the two barrier regions is used to form a metal layer.
2. The high power surge protection device of claim 1 wherein the substrate has a first doping type;
the diffusion layer includes:
a first diffusion layer formed over the substrate, the first diffusion layer having a second doping type;
a second diffusion layer formed under the substrate, the second diffusion layer having the second doping type;
the metal layer includes:
a top metal layer formed over the first diffusion layer in a region between an adjacent pair of the barrier regions;
and a bottom metal layer formed below the second diffusion layer in a region between an adjacent pair of the barrier regions.
3. The high power surge protection device of claim 1 wherein the substrate has a first doping type;
the diffusion layer includes:
a third diffusion layer formed over the substrate, the third diffusion layer having a second doping type;
the metal layer includes:
a top metal layer formed over the first diffusion layer in a region between an adjacent pair of the barrier regions;
and a bottom metal layer covering under the substrate.
4. The high power surge protection device of claim 1 wherein the lateral thickness of the blocking region is greater than 10um.
5. A method for manufacturing a high power surge protection device according to any one of claims 1 to 4, comprising:
step S1: forming a diffusion layer on a substrate;
step S2: etching the two ends of the substrate and the diffusion layer respectively to form an arc corner, and then forming a passivation region on the arc corner;
step S3: forming the blocking region according to an included angle between the diffusion layer and the passivation region;
step S4: and forming a metal layer between the barrier regions.
6. The method according to claim 5, wherein the step S1 comprises:
step S11: double-sided polishing and cleaning are carried out on the substrate;
step S12: performing gaseous boron pre-diffusion treatment on a processing area of the surface of the substrate, wherein the processing area is scheduled to form the diffusion layer;
step S13: and carrying out boron re-expansion treatment on the processing area to form the diffusion layer.
7. The method according to claim 6, wherein in the step S12, the temperature of the gaseous boron pre-diffusion treatment is 1085 ℃ for 50 minutes;
in the step S13, the temperature of the boron re-expansion treatment is 1250 ℃.
8. The method according to claim 6, wherein the step S2 comprises:
step S21: etching two ends of the diffusion layer respectively to form a pair of arc corners;
the bottom of each arc corner reaches the substrate;
step S22: and forming the passivation areas on each arc corner respectively.
9. The method according to claim 5, wherein the step S3 comprises:
step S31: etching the surface of the diffusion layer so that the top end of the passivation region is higher than the diffusion layer;
step S32: coating photoresist on the diffusion layer to respectively generate growth windows at two ends of the diffusion layer;
step S33: and respectively growing the blocking areas in each growth window, and then removing the photoresist.
10. The method according to claim 9, wherein in step S33, the barrier regions are alternately grown in the growth window using a dry oxygen oxidation process and a wet oxygen oxidation process, respectively.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310462330.1A CN116504844A (en) | 2023-04-25 | 2023-04-25 | High-power surge protection device and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310462330.1A CN116504844A (en) | 2023-04-25 | 2023-04-25 | High-power surge protection device and preparation method thereof |
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| CN116504844A true CN116504844A (en) | 2023-07-28 |
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| CN202310462330.1A Pending CN116504844A (en) | 2023-04-25 | 2023-04-25 | High-power surge protection device and preparation method thereof |
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| CN (1) | CN116504844A (en) |
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