CN114335147A - Terminal structure, manufacturing method thereof and semiconductor device - Google Patents
Terminal structure, manufacturing method thereof and semiconductor device Download PDFInfo
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- CN114335147A CN114335147A CN202111675351.9A CN202111675351A CN114335147A CN 114335147 A CN114335147 A CN 114335147A CN 202111675351 A CN202111675351 A CN 202111675351A CN 114335147 A CN114335147 A CN 114335147A
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Abstract
The invention provides a terminal structure, a manufacturing method thereof and a semiconductor device, wherein the terminal structure is positioned in a terminal area of a substrate, the substrate also comprises a cellular area, and the terminal area surrounds the cellular area; the terminal structure includes: the VLD voltage division ring is formed at one end, close to the cellular region, of the terminal region and extends towards the direction of the other end, far away from the cellular region, and comprises a plurality of connected doped rings; and the groove stopping ring is formed at the other end, far away from the cellular region, of the terminal region, the substrate is arranged between the groove stopping ring and the VLD voltage dividing ring at intervals, and the depth of the groove stopping ring is greater than or equal to that of the doped ring closest to the groove stopping ring. The technical scheme of the invention can avoid the depletion region from being depleted to the scribing channel to form a leakage channel, and can also reduce the width of the terminal region.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a terminal structure, a manufacturing method of the terminal structure and a semiconductor device.
Background
Among termination techniques for semiconductor devices, the Variable Lateral Doping (VLD) termination technique has been widely used because of its high termination efficiency. The termination typically prevents depletion of the depletion region by adding a stop ring at the tail.
Referring to fig. 1, a termination structure of a semiconductor device is formed in a termination region a1 in an N-type substrate 11, the N-type substrate 11 further includes a cell region (not shown) surrounded by the termination region a1, a gate structure 14 is formed in a transition region a2 between the cell region and the termination region a1, and a scribe lane (not shown) is formed at the periphery of the termination region a 1; a P-type VLD voltage divider ring 12 is formed in the termination region a1, the VLD voltage divider ring 12 extends from the transition region a2 toward the end of the termination region a1 away from the cell region, and a P-type stopper ring 13 is formed at the end of the termination region a1 away from the cell region to prevent depletion of the depletion region 15 formed by the N-type substrate 11 and the P-type VLD voltage divider ring 12. However, since the stopper ring 13 is formed by ion implantation together with the body region (not shown) of the cell region, the junction depth of the stopper ring 13 is much shallower than the depth of the portion of the VLD strap 12 closest to the stopper ring 13 (for example, the junction depth of the stopper ring 13 is only about 3 μm), the stopper ring 13 can only block the depletion of the surface of the substrate 11, and cannot block the movement of the depletion region 15 inside the substrate 11, and the depletion region 15 passes through from below the stopper ring 13 (as shown in fig. 1) and is depleted into the scribe lane, thereby forming a leakage path; to avoid forming a leakage path, the distance between VLD voltage dividing ring 12 and stop ring 13 needs to be increased to increase the distance between depletion region 15 and stop ring 13 to avoid forming a leakage path, but the width of termination region a1 is increased to increase the cost.
Therefore, how to reduce the width of the termination region while preventing the depletion region from depleting the scribe line to form a leakage channel is a problem that needs to be solved.
Disclosure of Invention
The invention aims to provide a terminal structure, a manufacturing method thereof and a semiconductor device, which can prevent a depletion region from being depleted to a scribing channel to form a leakage channel and can reduce the width of a terminal region.
In order to achieve the above object, the present invention provides a terminal structure located in a terminal region of a substrate, the substrate further comprising a cell region, the terminal region surrounding the cell region; the terminal structure includes:
the VLD voltage division ring is formed at one end, close to the cellular region, of the terminal region and extends towards the direction of the other end, far away from the cellular region, and comprises a plurality of connected doped rings;
and the groove stopping ring is formed at the other end, far away from the cellular region, of the terminal region, the substrate is arranged between the groove stopping ring and the VLD voltage dividing ring at intervals, and the depth of the groove stopping ring is greater than or equal to that of the doped ring closest to the groove stopping ring.
Optionally, the termination structure further includes a doping stop ring, the doping stop ring is located in the substrate on the bottom surface and the side surface of the trench stop ring, so that the doping stop ring surrounds the trench stop ring, and the substrate is spaced between the doping stop ring and the VLD voltage-dividing ring.
Optionally, the cell region is formed with a gate structure, and the gate structure and the trench stop ring have the same depth.
Optionally, the terminal structure further includes:
and the drift region is formed in the substrate and surrounds the VLD voltage division ring, the groove stopping ring and the doping stopping ring.
Optionally, the material of the trench stop ring is doped polysilicon, and the doping concentration of the trench stop ring is greater than the doping concentration of the drift region.
Optionally, a doping concentration of the doping stop ring is greater than a doping concentration of the drift region.
Optionally, the VLD voltage divider ring has a first conductivity type, and the trench stop ring, the doping stop ring and the drift region have a second conductivity type.
The invention also provides a manufacturing method of the terminal structure, the terminal structure is positioned in a terminal area of a substrate, the substrate also comprises a cellular area, and the terminal area surrounds the cellular area; the manufacturing method of the terminal structure comprises the following steps:
forming a VLD voltage dividing ring at one end of the terminal area close to the cellular area, wherein the VLD voltage dividing ring extends towards the other end of the terminal area far away from the cellular area, and the VLD voltage dividing ring comprises a plurality of connected doped rings;
and forming a groove stopping ring at the other end of the terminal area far away from the cellular area, wherein the substrate is arranged between the groove stopping ring and the VLD voltage division ring at intervals, and the depth of the groove stopping ring is greater than or equal to that of the doped ring closest to the groove stopping ring.
Optionally, the method for manufacturing the terminal structure further includes:
and forming a doping stop ring in the substrate on the bottom surface and the side surface of the groove stop ring, so that the doping stop ring surrounds the groove stop ring, and the substrate is arranged between the doping stop ring and the VLD voltage division ring at intervals.
Optionally, the step of forming the trench stop ring and the doping stop ring comprises:
forming a first trench in the substrate of the termination region distal from the other end of the cell region;
filling a polysilicon layer containing doped ions in the first trench;
and performing an annealing process to form the polycrystalline silicon layer into the groove stop ring and diffuse the doping ions into the substrate on the bottom surface and the side surface of the groove stop ring to form the doping stop ring.
Optionally, a second trench is formed in the substrate of the cell region while forming the first trench in the substrate of the other end of the termination region away from the cell region; and forming a gate structure in the second groove.
Optionally, before forming the VLD voltage divider ring at an end of the termination region near the cell region, the method for manufacturing the termination structure further includes:
and forming a drift region in the substrate, wherein the drift region surrounds the VLD voltage divider ring, the trench stop ring and the doping stop ring.
Optionally, a doping concentration of the trench stop ring is greater than a doping concentration of the drift region.
Optionally, a doping concentration of the doping stop ring is greater than a doping concentration of the drift region.
Optionally, the VLD voltage divider ring has a first conductivity type, and the trench stop ring, the doping stop ring and the drift region have a second conductivity type.
The invention also provides a semiconductor device comprising a cell region in a substrate and a termination region surrounding the cell region, the termination region being formed with the termination structure.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1. the terminal structure comprises the VLD voltage division ring which is formed at one end of the terminal area, close to the cellular area, and extends towards the direction of the other end, far away from the cellular area, wherein the VLD voltage division ring comprises a plurality of connected doped rings; the substrate is arranged between the trench stop ring and the VLD voltage division ring at intervals, the trench stop ring is formed in a trench filling mode, the depth of the trench stop ring is larger than or equal to that of a doping ring closest to the trench stop ring, so that a depletion region can be prevented from penetrating through the trench stop ring and being depleted to a scribing channel, and a leakage channel is prevented from being formed; in addition, the distance between the depletion region and the trench stop ring can be reduced, so that the width of the terminal region is reduced, and the cost is saved.
2. The manufacturing method of the terminal structure comprises the steps that a VLD voltage division ring is formed at one end, close to a cell area, of a terminal area, the VLD voltage division ring extends towards the other end, far away from the cell area, of the terminal area, and the VLD voltage division ring comprises a plurality of connected doped rings; forming a trench stop ring at the other end, far away from the cell region, of the terminal region in a trench filling mode, wherein the substrate is arranged between the trench stop ring and the VLD voltage division ring at intervals, and the depth of the trench stop ring is greater than or equal to that of a doped ring closest to the trench stop ring, so that a depletion region can be prevented from penetrating through the trench stop ring and being depleted to a scribing channel, and a leakage channel is prevented from being formed; in addition, the distance between the depletion region and the trench stop ring can be reduced, so that the width of the terminal region is reduced, and the cost is saved.
3. The semiconductor device comprises a cellular region positioned in a substrate and a terminal region surrounding the cellular region, wherein the terminal region is provided with the terminal structure, so that the size of the semiconductor device can be reduced while a leakage channel is prevented from being formed in the semiconductor device.
Drawings
Fig. 1 is a schematic diagram of a conventional terminal structure;
fig. 2 is a schematic diagram of a terminal structure according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method of manufacturing a terminal structure according to an embodiment of the present invention;
fig. 4a to 4h are schematic views of devices in the method of manufacturing the termination structure shown in fig. 3.
Wherein the reference numerals of figures 1 to 4h are as follows:
11-a substrate; a 12-VLD voltage divider ring; 13-a stop ring; 14-a gate structure; 15-depletion region;
20-a drift region; 21-VLD grading ring; 22-a trench stop ring; 221-a first trench; 222-a polysilicon layer; 23-doping a stop ring; 24-an insulating dielectric layer; 25-an oxide layer; 26-stop ring metal; 27-a buffer layer; 28-collector region; 29-collector metal; 30-depletion region; 311-gate oxide layer; 312-gate layer; 313-a second trench; 32-a source region; 33-a conductive plug; 34-emitter metal.
Detailed Description
In order to make the objects, advantages and features of the present invention more apparent, the terminal structure, the method of manufacturing the same and the semiconductor device according to the present invention will be described in further detail. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
An embodiment of the present invention provides a terminal structure, where the terminal structure is located in a terminal area of a substrate, the substrate further includes a cell area, the terminal area surrounds the cell area, a transition area is located between the terminal area and the cell area, and a scribing channel is surrounded around the terminal area; the terminal structure includes: the VLD voltage division ring is formed at one end, close to the cellular region, of the terminal region and extends towards the direction of the other end, far away from the cellular region, and comprises a plurality of connected doped rings; and the groove stopping ring is formed at the other end, far away from the cellular region, of the terminal region, the substrate is arranged between the groove stopping ring and the VLD voltage dividing ring at intervals, and the depth of the groove stopping ring is greater than or equal to that of the doped ring closest to the groove stopping ring.
The terminal structure of the present embodiment will be described in more detail with reference to fig. 2, and fig. 2 is a schematic longitudinal cross-sectional view of the terminal structure.
The substrate may be made of any suitable material known to those skilled in the art, such as monocrystalline silicon, silicon germanium, silicon carbide, and the like.
The VLD (Variation of Lateral Doping) strap 21 is formed at one end of the terminal region B1 close to the cell region (not shown), and the VLD strap 21 extends toward the other end of the terminal region B1 away from the cell region, and the VLD strap 21 surrounds the cell region; the VLD grading ring 21 comprises a plurality of connected doped rings (in the embodiment shown in fig. 2, the number of doped rings is 5).
Between the terminal region B1 and the cell region is a transition region B2, and the doped ring of the VLD voltage divider ring 21 closest to the cell region may also extend from the terminal region B1 into the transition region B2.
From one end of the terminal region B1 close to the cell region to the other end far from the cell region, the depths, widths and doping concentrations of the plural connected doped rings are reduced one by one; or the depth, the width and the doping concentration of the doping ring closest to the cell area are the deepest, the width and the doping concentration are the largest, and the depth, the width and the doping concentration of each of the other doping rings are the same and are correspondingly smaller than those of the doping ring closest to the cell area.
An oxide layer 25 may be formed on the substrate, and a partial thickness of the oxide layer 25 may be located in the substrate; the oxide layer 25 extends from the top of the doped ring closest to the cell region to a direction away from the cell region, so that the oxide layer 25 covers part of the top of the doped ring closest to the cell region and the top of all other doped rings.
The trench stopper ring 22 is formed at the other end of the terminal region B1 away from the cell region, the trench stopper ring 22 surrounding the VLD voltage divider ring 21; the substrate is arranged between the groove stopping ring 22 and the VLD voltage dividing ring 21 at intervals, and the depth of the groove stopping ring 22 is larger than or equal to that of a doping ring closest to the groove stopping ring 22.
The material of the trench stop ring 22 is doped polysilicon, that is, the trench stop ring 22 is formed by filling the doped polysilicon in the trench.
The termination structure may further include a doping cut-off ring 23, where the doping cut-off ring 23 is located in the substrate at the bottom and the side of the trench cut-off ring 22, so that the doping cut-off ring 23 surrounds the trench cut-off ring 22, and the substrate is spaced between the doping cut-off ring 23 and the VLD voltage divider ring 21. Since the depth of the trench stop ring 22 is greater than or equal to the depth of the doping ring closest to the trench stop ring 22, the depth of the doping stop ring 23 is greater than the depth of the doping ring closest to the trench stop ring 22.
In addition, a gate structure is further formed in the substrate of the transition region B2 and the cell region, the depth of the gate structure may be the same as the depth of the trench stop ring 22, and the doped ring closest to the cell region may surround the gate structure in the transition region B2. The gate structure includes a gate oxide layer 311 and a gate layer 312, and the gate layer 312 is made of polysilicon.
The width of the trench stop ring 22 is greater than the width of the gate structure, for example, the width of the trench stop ring 22 is 4 μm to 5 μm, and the width of the gate structure is 0.7 μm to 0.9 μm.
The termination structure further comprises a drift region 20, the drift region 20 being formed in the substrate, the drift region 20 surrounding the VLD voltage divider ring 21, the trench stopper ring 22 and the doping stopper ring 23.
Wherein the doping concentration of the trench stop ring 22 is greater than the doping concentration of the drift region 20. If the termination structure further comprises the doping stop ring 23, the doping concentration of the doping stop ring 23 is preferably also greater than the doping concentration of the drift region 20.
The terminal structure may further include: and an insulating dielectric layer 24 covering the top surface of the substrate. The insulating dielectric layer 24 extends from over the termination region B1 to over the transition region B2; the insulating medium layer 24 buries the VLD voltage division ring 21, the oxide layer 25, the trench stop ring 22, the doping stop ring 23 and the gate structure; and a stop ring metal 26 formed on the insulating dielectric layer 24 above the trench stop ring 22, wherein the stop ring metal 26 is insulated from the trench stop ring 22.
In addition, an active electrode region 32 is formed on the transition region B2 and the top of the substrate of the cellular region; a plurality of conductive plugs 33 are formed at the junctions of the transition region B2 and the transition region B2 and the termination region B1, the conductive plugs 33 penetrate through the insulating dielectric layer 24 and enter the substrate, an emitter metal 34 electrically connected with the conductive plugs 33 is formed on the insulating dielectric layer 24 of the transition region B2, and the emitter metal 34 is electrically connected with the source region 32 and the doping ring closest to the cell region through the conductive plugs 33.
The terminal structure may further include:
a buffer layer 27 formed in the substrate at the bottom surface of the drift region 20;
a collector region 28 formed in the substrate on the bottom surface of the buffer layer 27;
and a collector metal 29 formed on the bottom surface of the substrate.
Wherein the VLD grading ring 21 and the collector region 28 have a first conductivity type and the substrate, the trench stop ring 22, the doping stop ring 23, the drift region 20, the source region 32 and the buffer layer 27 have a second conductivity type. The first conduction type is a P type, and the second conduction type is an N type; or, the first conductivity type is N-type, and the second conductivity type is P-type. In the operating state, the VLD voltage divider ring 21 having the first conductivity type forms a depletion region 30 with the drift region 20 having the second conductivity type.
In summary, in the termination structure provided by the present invention, since the trench stop ring 22 is formed at the other end of the termination region B1, which is far away from the cell region, the trench stop ring 22 is formed by trench filling, and the depth of the trench stop ring 22 is greater than or equal to the depth of the doped ring closest to the trench stop ring 22 in the VLD shunt ring 21, so that compared with the stop ring 13 formed by ion implantation shown in fig. 1, the depletion region 30 of the present invention can contact the trench stop ring 22 before being depleted to the scribe lane, so that the depletion region 30 is stopped by the trench stop ring 22, and the depletion region 30 is prevented from passing through the trench stop ring 22 and being depleted to the scribe lane, thereby preventing a leakage channel from being formed; further, the distance between the depletion region 30 and the trench stopper ring 22 can be reduced, and the width of the termination region B1 can be reduced, thereby saving cost.
When the depletion region 30 is depleted to be in contact with the trench stop ring 22, the doping concentration of the trench stop ring 22 is greater than that of the drift region 20, so that the doping concentration of the region with the N-type conductivity is increased, the width of the depletion region 30 is reduced, the depletion region 30 is depleted quickly, that is, the depletion region 30 is cut off by the trench stop ring 22, and the depletion region 30 is prevented from being depleted to a scribe lane.
Further, if the termination structure further includes the doping stop ring 23, since the depth of the doping stop ring 23 is greater than the depth of the doping ring closest to the trench stop ring 22, and the doping concentration of the doping stop ring 23 is greater than the doping concentration of the drift region 20, the depletion region 30 can be in contact with the doping stop ring 23 and the trench stop ring 22 before being depleted to the scribe lane, the doping concentration of the region with the N-type conductivity is increased, and the trench stop ring 22 and the doping stop ring 23 can stop the depletion of the depletion region 30 together, so that the stop effect is further improved.
An embodiment of the present invention provides a method for manufacturing a terminal structure, where the terminal structure is located in a terminal area of a substrate, the substrate further includes a cell area, the terminal area surrounds the cell area, a transition area is located between the terminal area and the cell area, and a scribe lane is surrounded on the periphery of the terminal area; referring to fig. 3, fig. 3 is a flowchart of a method for manufacturing a terminal structure according to an embodiment of the present invention, where the method for manufacturing a terminal structure includes:
step S1, forming a VLD voltage dividing ring at one end of the terminal region close to the cell region, wherein the VLD voltage dividing ring extends towards the other end of the terminal region far from the cell region, and the VLD voltage dividing ring comprises a plurality of connected doped rings;
step S2, forming a trench stop ring at the other end of the termination region away from the cell region, the substrate being spaced between the trench stop ring and the VLD voltage divider ring, the trench stop ring having a depth greater than or equal to the depth of the doped ring closest to the trench stop ring.
The method for manufacturing the terminal structure according to the present embodiment is described in more detail with reference to fig. 4a to 4h, and fig. 4a to 4h are schematic longitudinal cross-sectional views of the terminal structure.
According to step S1, referring to fig. 4a, a VLD (Variation of Lateral Doping) strap 21 is formed at one end of the terminal region B1 close to the cell region (not shown), and the VLD strap 21 extends toward the other end of the terminal region B1 away from the cell region, and the VLD strap 21 surrounds the cell region; the VLD grading ring 21 comprises a plurality of connected doped rings (in the embodiment shown in fig. 4a, the number of doped rings is 5).
Between the terminal region B1 and the cell region is a transition region B2, and the doped ring of the VLD voltage divider ring 21 closest to the cell region may also extend from the terminal region B1 into the transition region B2.
From one end of the terminal region B1 close to the cell region to the other end far from the cell region, the depths, widths and doping concentrations of the plural connected doped rings are reduced one by one; or the depth, the width and the doping concentration of the doping ring closest to the cell area are the deepest, the width and the doping concentration are the largest, and the depth, the width and the doping concentration of each of the other doping rings are the same and are correspondingly smaller than those of the doping ring closest to the cell area.
Taking the example that the doping ring closest to the cell region has the deepest depth, the largest width and the largest doping concentration, the step of forming the VLD grading ring 21 may include: first, forming a first patterned photoresist layer (not shown) on the substrate, wherein the first patterned photoresist layer has a plurality of ion implantation windows for forming doped rings, the ion implantation windows have the same width, and performing a first ion implantation to form a plurality of ion implantation regions in the substrate exposed by the ion implantation windows, and a gap exists between the ion implantation regions; then, forming an oxide layer 25 on the substrate, wherein a part of the thickness of the oxide layer 25 may be located in the substrate, the oxide layer 25 extends from the ion implantation region farthest from the cell region to the direction of the cell region, so that the oxide layer 25 covers the ion implantation region other than the ion implantation region closest to the cell region, and the oxide layer 25 does not cover the ion implantation region closest to the cell region; then, taking the oxide layer 25 as a mask, performing a second ion implantation on the ion implantation region closest to the cell region, so that the doping concentration of the ion implantation region closest to the cell region is greater than that of other ion implantation regions; and then, performing an annealing process to enable ions in each ion implantation region to be diffused and then enable adjacent ion implantation regions to be mutually overlapped and connected, so that each connected doping ring is correspondingly formed, and the depth of each doping ring is correspondingly greater than that of each ion implantation region. And because the ion implantation area closest to the cellular area is also subjected to secondary ion implantation, the doped ring closest to the cellular area is deeper in depth, larger in width and higher in doping concentration compared with other doped rings.
Forming a trench stopper ring 22 at said other end of said termination region B1 away from said cell region, said trench stopper ring 22 surrounding said VLD voltage divider ring 21, according to step S2; the substrate is arranged between the groove stopping ring 22 and the VLD voltage dividing ring 21 at intervals, and the depth of the groove stopping ring 22 is larger than or equal to that of a doping ring closest to the groove stopping ring 22.
The step of forming the groove stopper ring 22 includes: first, referring to fig. 4B, a first trench 221 is formed in the substrate of the other end of the termination region B1 away from the cell region; then, referring to fig. 4d, a polysilicon layer 222 containing doped ions is filled in the first trench 221, and the polysilicon layer 222 covers the substrate, the oxide layer 25 and the VLD strap 21; then, referring to fig. 4e, the polysilicon layer 222 above the top surface of the substrate is removed, so that the polysilicon layer 222 in the first trench 221 is formed as the trench stop ring 22.
The method of manufacturing the terminal structure may further include: and forming a doping stop ring 23 in the substrate on the bottom surface and the side surface of the trench stop ring 22, so that the doping stop ring 23 surrounds the trench stop ring 22, and the substrate is spaced between the doping stop ring 23 and the VLD voltage division ring 21. Since the depth of the trench stop ring 22 is greater than or equal to the depth of the doping ring closest to the trench stop ring 22, the depth of the doping stop ring 23 is greater than the depth of the doping ring closest to the trench stop ring 22.
If the termination structure further includes the dopant stop ring 23, the step of forming the trench stop ring 22 and the dopant stop ring 23 may include: first, referring to fig. 4B, a first trench 221 is formed in the substrate of the other end of the termination region B1 away from the cell region; then, referring to fig. 4d, a polysilicon layer 222 is filled in the first trench 221, the polysilicon layer 222 covers the substrate, the oxide layer 25 and the VLD strap 21, and the polysilicon layer 222 contains doped ions; then, referring to fig. 4e, the polysilicon layer 222 above the top surface of the substrate is removed, and only the polysilicon layer 222 in the first trench 221 remains; then, referring to fig. 4f, an annealing process is performed to form the polysilicon layer 222 in the first trench 221 into the trench stop ring 22, and to diffuse the dopant ions into the substrate on the bottom and side of the trench stop ring 22 to form the dopant stop ring 23, wherein the dopant stop ring 23 surrounds the trench stop ring 22, and the substrate is spaced between the dopant stop ring 23 and the VLD voltage divider ring 21. Wherein, the temperature of the annealing process can be 1100-1200 ℃, and the time can be 90-110 min; it should be noted that the temperature and time of the annealing process are not limited to the above ranges, and can be adjusted according to the requirements of the depth and width of the doping cut-off ring 23.
In addition, referring to fig. 4B, while forming the first trench 221 in the substrate of the other end of the termination region B1 away from the cell region, a second trench 313 may be formed in the substrate of the transition region B2 and the cell region, the depth of the first trench 221 and the second trench 313 is the same, and the doped ring closest to the cell region may surround the second trench 313 in the transition region B2; referring to fig. 4c, before filling the polysilicon layer 222 in the first trench 221, a gate oxide layer 311 may be formed on the inner wall of the second trench 313; referring to fig. 4d and 4e, while the polysilicon layer 222 is filled in the first trench 221, the polysilicon layer 222 is also filled in the second trench 313, so that after the polysilicon layer 222 above the top surface of the substrate is removed, the polysilicon layer 222 in the second trench 313 serves as a gate layer 312, and a gate structure is formed in the second trench 313, where the gate structure includes the gate oxide layer 311 and the gate layer 312. Wherein, since the first trench 221 and the second trench 313 are formed simultaneously and the polysilicon layer 222 is filled in the first trench 221 and the second trench 313 simultaneously, the process steps can be simplified.
The width of the first trench 221 (i.e., the width of the trench stopper 22) is greater than the width of the second trench 313, for example, the width of the first trench 221 is 4 μm to 5 μm, and the width of the second trench 313 is 0.7 μm to 0.9 μm.
In addition, before the forming the VLD grading ring 21 at the end of the termination region B1 close to the cell region, the method for manufacturing the termination structure further includes: referring to fig. 4a, a drift region 20 is formed in the substrate, the drift region 20 surrounding the VLD voltage divider ring 21, the trench stop ring 22 and the doping stop ring 23.
Wherein the doping concentration of the trench stop ring 22 is greater than the doping concentration of the drift region 20. If the termination structure further comprises the doping stop ring 23, the doping concentration of the doping stop ring 23 is preferably also greater than the doping concentration of the drift region 20.
The method for manufacturing the terminal structure further includes: referring to fig. 4g, an insulating dielectric layer 24 is formed overlying the top surface of the substrate. The insulating dielectric layer 24 extends from over the termination region B1 to over the transition region B2; the insulating medium layer 24 buries the VLD voltage divider ring 21, the oxide layer 25, the trench stopper ring 22, the doping stopper ring 23, and the gate structure therein.
In addition, referring to fig. 4f, after forming the doping cut-off ring 23 and before forming the insulating dielectric layer 24, a source region 32 may be formed in the transition region B2 and the cell region; referring to fig. 4g, after forming the insulating dielectric layer 24, a contact hole (not shown) may be formed at the transition region B2 and the boundary between the transition region B2 and the termination region B1, and metal is filled into the contact hole and covers the insulating dielectric layer 24, an emitter metal 34 is formed on the insulating dielectric layer 24 of the transition region B2 after etching the metal, and a stop ring metal 26 is formed on the insulating dielectric layer 24 above the trench stop ring 22, a conductive plug 33 is formed in the contact hole, the emitter metal 34 is electrically connected to the source region 32 and the doped ring closest to the cellular region through the conductive plug 33, and the stop ring metal 26 is insulated from the trench stop ring 22.
Also, referring to fig. 4h, after forming the emitter metal 34 and the stop ring metal 26, the method of fabricating the termination structure further includes:
forming a buffer layer 27 in the substrate at the bottom of the drift region 20;
forming a collector region 28 in the substrate at the bottom of the buffer layer 27;
a collector metal 29 is formed on the bottom surface of the substrate.
Wherein the VLD grading ring 21 and the collector region 28 have a first conductivity type and the substrate, the trench stop ring 22, the doping stop ring 23, the drift region 20, the source region 32 and the buffer layer 27 have a second conductivity type. The first conduction type is a P type, and the second conduction type is an N type; or, the first conductivity type is N-type, and the second conductivity type is P-type. Referring to fig. 4h, in operation, the VLD strap 21 having the first conductivity type and the drift region 20 having the second conductivity type form a depletion region 30.
In summary, in the manufacturing method of the termination structure provided by the present invention, since the trench stop ring 22 is formed at the other end of the termination region B1 away from the cell region by a trench filling method, and the depth of the trench stop ring 22 is greater than or equal to the depth of the doped ring closest to the trench stop ring 22 in the VLD strap 21, compared with the stop ring 13 formed by ion implantation shown in fig. 1, the depletion region 30 of the present invention can contact the trench stop ring 22 before being depleted to the scribe lane, so that the depletion region 30 is stopped by the trench stop ring 22, and the depletion region 30 is prevented from passing through the trench stop ring 22 and being depleted to the scribe lane, thereby preventing a leakage channel from being formed; further, the distance between the depletion region 30 and the trench stopper ring 22 can be reduced, and the width of the termination region B1 can be reduced, thereby saving cost.
When the depletion region 30 is depleted to be in contact with the trench stop ring 22, the doping concentration of the trench stop ring 22 is greater than that of the drift region 20, so that the doping concentration of the region with the N-type conductivity is increased, the width of the depletion region 30 is reduced, the depletion region 30 is depleted quickly, that is, the depletion region 30 is cut off by the trench stop ring 22, and the depletion region 30 is prevented from being depleted to a scribe lane.
Further, if the termination structure further includes the doping stop ring 23, since the depth of the doping stop ring 23 is greater than the depth of the doping ring closest to the trench stop ring 22, and the doping concentration of the doping stop ring 23 is greater than the doping concentration of the drift region 20, the depletion region 30 can be in contact with the doping stop ring 23 and the trench stop ring 22 before being depleted to the scribe lane, the doping concentration of the region with the N-type conductivity is increased, and the trench stop ring 22 and the doping stop ring 23 can stop the depletion of the depletion region 30 together, so that the stop effect is further improved.
An embodiment of the present invention provides a semiconductor device, including a cell region located in a substrate and a terminal region surrounding the cell region, the terminal region being surrounded by a scribe lane; the terminal region is formed with the terminal structure.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (16)
1. A termination structure located in a termination region of a substrate, the substrate further comprising a cell region, the termination region surrounding the cell region; characterized in that, the terminal structure includes:
the VLD voltage division ring is formed at one end, close to the cellular region, of the terminal region and extends towards the direction of the other end, far away from the cellular region, and comprises a plurality of connected doped rings;
and the groove stopping ring is formed at the other end, far away from the cellular region, of the terminal region, the substrate is arranged between the groove stopping ring and the VLD voltage dividing ring at intervals, and the depth of the groove stopping ring is greater than or equal to that of the doped ring closest to the groove stopping ring.
2. The termination structure of claim 1, further comprising a doped stop ring in the substrate at the bottom and sides of the trench stop ring such that the doped stop ring surrounds the trench stop ring, the doped stop ring spaced from the VLD shunt ring by the substrate.
3. The termination structure of claim 1, wherein said cell region is formed with a gate structure, said gate structure being the same depth as said trench stop ring.
4. The terminal structure of claim 2, wherein the terminal structure further comprises:
and the drift region is formed in the substrate and surrounds the VLD voltage division ring, the groove stopping ring and the doping stopping ring.
5. The termination structure of claim 4, wherein said trench stop collar is doped polysilicon and has a doping concentration greater than that of said drift region.
6. The termination structure of claim 4, wherein a doping concentration of the doping stop ring is greater than a doping concentration of the drift region.
7. The termination structure of claim 4, wherein the VLD voltage divider ring has a first conductivity type, and the trench stop ring, the doped stop ring, and the drift region have a second conductivity type.
8. A method of fabricating a termination structure, the termination structure being located in a termination region of a substrate, the substrate further comprising a cell region, the termination region surrounding the cell region; the manufacturing method of the terminal structure is characterized by comprising the following steps:
forming a VLD voltage dividing ring at one end of the terminal area close to the cellular area, wherein the VLD voltage dividing ring extends towards the other end of the terminal area far away from the cellular area, and the VLD voltage dividing ring comprises a plurality of connected doped rings;
and forming a groove stopping ring at the other end of the terminal area far away from the cellular area, wherein the substrate is arranged between the groove stopping ring and the VLD voltage division ring at intervals, and the depth of the groove stopping ring is greater than or equal to that of the doped ring closest to the groove stopping ring.
9. The method of manufacturing a terminal structure according to claim 8, further comprising:
and forming a doping stop ring in the substrate on the bottom surface and the side surface of the groove stop ring, so that the doping stop ring surrounds the groove stop ring, and the substrate is arranged between the doping stop ring and the VLD voltage division ring at intervals.
10. The method of fabricating a termination structure according to claim 9, wherein the step of forming the trench stop collar and the dopant stop collar comprises:
forming a first trench in the substrate of the termination region distal from the other end of the cell region;
filling a polysilicon layer containing doped ions in the first trench;
and performing an annealing process to form the polycrystalline silicon layer into the groove stop ring and diffuse the doping ions into the substrate on the bottom surface and the side surface of the groove stop ring to form the doping stop ring.
11. The method of claim 10, wherein a second trench is formed in the substrate of the cell region while forming the first trench in the substrate of the other end of the termination region away from the cell region; and forming a gate structure in the second groove.
12. The method of manufacturing a termination structure of claim 10, wherein prior to forming the VLD voltage divider ring at an end of the termination region proximate to the cell region, the method of manufacturing a termination structure further comprises:
and forming a drift region in the substrate, wherein the drift region surrounds the VLD voltage divider ring, the trench stop ring and the doping stop ring.
13. The method of claim 12, wherein the trench stop ring has a doping concentration greater than a doping concentration of the drift region.
14. The method of claim 12, wherein the doping concentration of the doping stop ring is greater than the doping concentration of the drift region.
15. The method of fabricating a termination structure according to claim 12, wherein the VLD voltage divider ring has a first conductivity type, and the trench stop ring, the doped stop ring and the drift region have a second conductivity type.
16. A semiconductor device comprising a cell region in a substrate and a termination region surrounding said cell region, said termination region being formed with a termination structure as claimed in any one of claims 1 to 7.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI795286B (en) * | 2022-05-06 | 2023-03-01 | 國立陽明交通大學 | Method for stabilizing breakdown voltages of floating guard ring |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TWI795286B (en) * | 2022-05-06 | 2023-03-01 | 國立陽明交通大學 | Method for stabilizing breakdown voltages of floating guard ring |
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