Disclosure of Invention
The application mainly aims to provide an LDMOS terminal structure and a manufacturing method of the LDMOS terminal structure, which are used for solving the problem of poor performance of a device due to low breakdown voltage of the device in the prior art.
According to an aspect of an embodiment of the present application, there is provided an LDMOS terminal structure, the LDMOS terminal structure including a substrate, an epitaxial layer, a body region and a drift region, wherein the substrate includes a substrate, the epitaxial layer is located on a surface of the substrate, the body region and the drift region are disposed in the epitaxial layer in a spaced manner, doping types of the epitaxial layer and the body region are the same, doping types of the drift region and the epitaxial layer are different, and doping concentration of the drift region is greater than that of the epitaxial layer; the field plate structure is located the epitaxial layer keep away from one side of substrate, just the field plate structure includes field plate portion and is located the arc field plate of field plate portion one side, field plate portion with arc field plate contact sets up, the field plate structure has first through-hole, first through-hole is located field plate portion with between the arc field plate, the projection of arc field plate in the basement covers some drift region, the projection of field plate portion in the basement covers some the body region, the body region with the projection of epitaxial layer in the field plate structure between the drift region is located in the first through-hole.
Optionally, the base further comprises a source contact region, a drain contact region, a source and a drain, wherein the source contact region is located in the body region, a surface of the source contact region away from the substrate is flush with a surface of the epitaxial layer away from the substrate, and doping types of the source contact region and the body region are different; the drain contact region is positioned in the drift region, the surface of the drain contact region, which is far away from the substrate, is flush with the surface of the drift region, which is far away from the substrate, and the doping type of the drain contact region is the same as that of the drift region; the source electrode is positioned on a part of the surface of the source contact region, which is far away from the substrate; the drain electrode is located on a portion of a surface of the drain contact region remote from the substrate.
Optionally, the LDMOS terminal structure further includes a gate dielectric layer, a gate electrode, and a dielectric layer, where the gate dielectric layer is located on a portion of a surface of the substrate, the gate dielectric layer covers a portion of the body region and a portion of the epitaxial layer, and the gate dielectric layer is not in contact with the source contact region; the grid electrode is positioned on the surface, far away from the substrate, of the grid dielectric layer, and the projection of the grid electrode in the field plate structure is positioned in the first through hole; the gate dielectric layer, the gate electrode and the surface of the epitaxial layer, which is far away from the substrate, are covered by the dielectric layer, the surface of the dielectric layer, which is far away from the epitaxial layer, is a plane, the source electrode and the drain electrode penetrate through the dielectric layer, and the field plate structure is positioned on the surface of the dielectric layer, which is far away from the substrate.
Optionally, the epitaxial layer is located on a part of a predetermined surface of the substrate, the LDMOS terminal structure further comprises a first metal layer, the first metal layer is located on another part of the predetermined surface of the substrate, a surface of the first metal layer away from the substrate is flush with a surface of the dielectric layer away from the substrate, the first metal layer is used for electrically connecting the source contact region and the substrate, and the field plate structure is in contact with the first metal layer.
Optionally, the LDMOS terminal structure further includes a second metal layer, the second metal layer is located on a portion of the surface of the dielectric layer away from the substrate, the second metal layer is in contact with the drain electrode, the second metal layer is spaced from the field plate structure, and the second metal layer and the field plate structure expose a portion of the dielectric layer.
Optionally, the doping type of the epitaxial layer is P-type, and the doping type of the drift region is N-type.
According to another aspect of the present application, there is also provided a method for manufacturing an LDMOS terminal structure, the method comprising: providing a substrate, wherein the substrate comprises a substrate, an epitaxial layer, a body region and a drift region, the epitaxial layer is positioned on the surface of the substrate, the body region and the drift region are arranged in the epitaxial layer in a space mode, the doping types of the epitaxial layer and the body region are the same, the doping types of the drift region and the epitaxial layer are different, and the doping concentration of the drift region is larger than that of the epitaxial layer; the field plate structure comprises a field plate body and an arc-shaped field plate positioned on one side of the field plate body, the field plate body is in contact with the arc-shaped field plate, the field plate structure is provided with a first through hole, the first through hole is positioned between the field plate body and the arc-shaped field plate, the projection of the arc-shaped field plate in the substrate covers part of the drift region, the projection of the field plate body in the substrate covers part of the body region, and the projection of the epitaxial layer between the body region and the drift region in the field plate structure is positioned in the first through hole.
Optionally, providing a substrate, comprising: providing the substrate and the epitaxial layer which are stacked; forming a gate dielectric layer on a part of the surface of the epitaxial layer, which is far away from the substrate, and forming a gate on the surface of the gate dielectric layer, which is far away from the base; and performing ion implantation in the gate dielectric layer and the epitaxial layer at two sides of the gate to form a body region, a drift region, a source contact region and a drain contact region, wherein the gate dielectric layer covers part of the body region and part of the epitaxial layer, the gate dielectric layer is not contacted with the source contact region, the projection of the gate dielectric layer and the gate in the field plate structure is positioned in the first through hole, the source contact region is positioned in the body region, the surface of the source contact region, which is far away from the substrate, is flush with the surface of the epitaxial layer, which is far away from the substrate, the doping type of the source contact region is different from that of the body region, the drain contact region is positioned in the drift region, the surface of the drain contact region, which is far away from the substrate, is not contacted with the surface of the drift region, which is far away from the substrate, and the doping type of the drain contact region is flush with that of the drift region.
Optionally, forming a gate dielectric layer on a portion of a surface of the epitaxial layer away from the substrate, and forming a gate on a surface of the gate dielectric layer away from the base, including: forming a laminated preparation gate dielectric layer and a preparation gate on the surface of the epitaxial layer, which is far away from the substrate; and removing part of the preparation gate dielectric layer and part of the preparation gate, forming the gate dielectric layer by the rest of the preparation gate dielectric layer, and forming the gate by the rest of the preparation gate.
Optionally, before forming the field plate structure on a side of the epitaxial layer remote from the substrate, the method further comprises: forming a preparation medium layer on the exposed surface of the epitaxial layer, wherein the surface of the preparation medium layer, which is far away from the epitaxial layer, is a plane, and the field plate structure is positioned on the surface of the preparation medium layer, which is far away from the substrate; removing part of the preparation medium layer to form a second through hole and a third through hole, wherein the second through hole and the third through hole expose part of the source contact area and part of the drain contact area respectively; removing part of the preparation medium layer, part of the source contact region, part of the body region and part of the epitaxial layer to form a fourth through hole, wherein part of the substrate is exposed by the fourth through hole, and the rest of the preparation medium layer forms a medium layer; and forming metal materials in the second through hole, the third through hole and the fourth through hole, and respectively forming a source electrode, a drain electrode and a first metal layer, wherein the first metal layer is used for electrically connecting the source contact area and the substrate, and the field plate structure is in contact with the first metal layer.
Optionally, forming a field plate structure on a side of the epitaxial layer away from the substrate, including: forming a preparation field plate structure on the surface of the dielectric layer far away from the substrate; and removing part of the preparation field plate structure to expose part of the dielectric layer, wherein the rest of the preparation field plate structure forms the field plate structure and a second metal layer which are arranged at intervals, and the second metal layer is in contact with the drain electrode.
By applying the technical scheme of the application, the LDMOS terminal structure comprises a substrate and a field plate structure, wherein the substrate comprises a substrate, an epitaxial layer, a body region and a drift region, the epitaxial layer and the substrate are arranged in a stacked manner, the body region and the drift region are arranged in the epitaxial layer in a spaced manner, the doping types of the epitaxial layer and the body region are the same, the doping types of the drift region and the epitaxial layer are different, and the doping concentration of the drift region is larger than that of the epitaxial layer; the field plate structure is located the epitaxial layer keep away from one side of substrate, just the field plate structure includes field plate portion and is located the arc field plate of field plate portion one side, field plate portion with arc field plate contact sets up, in addition, the field plate structure has first through-hole, field plate portion with enclose between the arc field plate first through-hole, the projection of arc field plate in the basement covers the part drift region, the projection of field plate portion in the basement covers the part the body region, the body region with the projection of epitaxial layer in the field plate structure between the drift region is located in the first through-hole. Compared with the problem of poor performance of a device caused by low breakdown voltage of the device in the prior art, the LDMOS terminal structure provided by the application has the advantages that the substrate comprising the substrate, the epitaxial layer, the body region and the drift region is provided, in addition, the LDMOS terminal structure further comprises the field plate structure, the field plate structure comprises the field plate body and the arc-shaped field plate, the electric field distribution in the drift region can be optimized through the field plate structure due to the fact that the projection of the arc-shaped field plate in the substrate covers part of the drift region, in addition, the projection of the epitaxial layer between the body region and the drift region in the field plate structure is positioned in the first through hole, namely, the field plate structure enables part of the epitaxial layer to be hollowed out, the field plate structure has small influence on the electric field of the epitaxial layer, the electric field distribution of the LDMOS device is optimized, the breakdown voltage of the LDMOS device is ensured to be higher, and further the performance of the semiconductor device is ensured to be better.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the application herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Furthermore, in the description and in the claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element or "connected" to the other element through a third element.
As described in the background art, in order to solve the problem in the prior art that the device performance is poor due to the low breakdown voltage of the device, in an exemplary embodiment of the present application, an LDMOS terminal structure and a method for manufacturing the LDMOS terminal structure are provided.
According to an exemplary embodiment of the present application, as shown in fig. 8 and 9, there is provided an LDMOS terminal structure, the LDMOS terminal structure includes a substrate 10 and a field plate structure 20, wherein the substrate 10 includes a substrate 101, an epitaxial layer 102, a body region 103 and a drift region 104, the epitaxial layer 102 is located on a surface of the substrate 101, the body region 103 and the drift region 104 are spaced apart from each other and are disposed in the epitaxial layer 102, doping types of the epitaxial layer 102 and the body region 103 are the same, doping types of the drift region 104 and the epitaxial layer 102 are different, and doping concentration of the drift region 104 is greater than that of the epitaxial layer 102; the field plate structure 20 is located on a side of the epitaxial layer 102 away from the substrate 101, and the field plate structure 20 includes a field plate base 201 and an arc field plate 202 located on a side of the field plate base 201, the field plate base 201 is disposed in contact with the arc field plate 202, the field plate structure 20 has a first through hole 203, the first through hole 203 is located between the field plate base 201 and the arc field plate 202, a projection of the arc field plate 202 in the substrate 10 covers the drift region 104, a projection of the field plate base 201 in the substrate 10 covers the body region 103, and a projection of the epitaxial layer 102 between the body region 103 and the drift region 104 in the field plate structure 20 is located in the first through hole 203.
The LDMOS terminal structure comprises a substrate, an epitaxial layer, a body region and a drift region, wherein the substrate comprises the substrate, the epitaxial layer and the substrate are stacked, the body region and the drift region are arranged in the epitaxial layer in a spaced mode, the doping types of the epitaxial layer and the body region are the same, the doping types of the drift region and the epitaxial layer are different, and the doping concentration of the drift region is larger than that of the epitaxial layer; the field plate structure is located on one side of the epitaxial layer far away from the substrate, the field plate structure comprises a field plate base and an arc-shaped field plate located on one side of the field plate base, the field plate base is in contact with the arc-shaped field plate, the field plate structure is provided with a first through hole, the first through hole is formed between the field plate base and the arc-shaped field plate in a surrounding mode, a projection covering part of the arc-shaped field plate in the substrate covers the drift region, a projection covering part of the field plate base in the substrate covers the body region, and a projection of the epitaxial layer between the body region and the drift region in the field plate structure is located in the first through hole. Compared with the problem of poor performance of a device caused by lower breakdown voltage of the device in the prior art, the LDMOS terminal structure of the application further comprises the field plate structure by providing the substrate comprising the substrate, the epitaxial layer, the body region and the drift region, wherein the field plate structure comprises the field plate body and the arc-shaped field plate, the electric field distribution in the drift region can be optimized through the field plate structure due to the fact that the projection of the arc-shaped field plate in the substrate covers part of the drift region, and in addition, the projection of the epitaxial layer between the body region and the drift region in the field plate structure is positioned in the first through hole, namely the field plate structure enables part of the epitaxial layer to be hollowed out, so that the field effect of the field plate structure on the epitaxial layer is smaller, the electric field distribution of the LDMOS device is optimized, the breakdown voltage of the device is ensured to be higher, and the performance of the semiconductor device is further ensured to be better.
In addition, as the body region and the drift region are arranged at intervals, and the doping concentration of the drift region is larger than that of the epitaxial layer, the epitaxial layer with smaller concentration exists between the body region and the drift region, and the doping types of the epitaxial layer and the drift region are different, so that a reverse PN junction is formed between the epitaxial layer and the drift region, and pressure bearing can be carried out through the reverse PN junction, the electric field distribution of the semiconductor device is guaranteed to be good, the breakdown voltage of the semiconductor device is guaranteed to be high, and the performance of the semiconductor device is further guaranteed to be good.
Specifically, the principle of the field plate modulating the breakdown voltage and the surface electric field of the drift region is described as follows: as shown in fig. 8, when the doping types of the epitaxial layer 102 and the body region 103 are P-type and the doping types of the drift region 104 and the drain contact region 106 are N-type, and when the entire device receives an external breakdown voltage, a positive voltage is applied to the electrode corresponding to the drain electrode 108, the electrode corresponding to the source electrode 107 and the first metal layer 60 is shorted to ground, and in this case, a positive voltage is applied to the drain electrode 108, electrons in the N-region gather in the region of the drain contact region 106 having a high potential, the depletion region at the junction interface between the epitaxial layer 102 and the drift region 104 expands until the spatial integral of the electric field formed by the fixed charges in the depletion region is equal to the external applied voltage, and the depletion region expansion stops, at which time the PN junction reaches a reverse bias balance state at a certain voltage. It will be appreciated that the location of the strongest electric field intensity of the entire reverse biased junction should occur at the junction interface, and in the ideal case of uniform doping, the electric field intensity should decrease linearly along the junction interface to the depletion region boundary, and the electric field intensity at both sides of the junction interface forms a triangle (as shown by the triangle dashed line in fig. 8), and the area (integral) of the triangle is the reverse bias voltage that the reverse biased junction can withstand. Specifically, fig. 8 is a schematic diagram showing that the electric field intensities of the N-type region of the drift region 104 and the P-type region of the epitaxial layer 102 are distributed along the vertical junction interface in the two directions, after the ground field plate (the field plate base 201 and the arc field plate 202) is introduced, it may be assumed that the field plate gradually approaches to the drain electrode as a low potential point, so as to promote the electrons in the region of the drain contact region 106 to be more concentrated, i.e. to assist the depletion of the non-depleted region near the drain contact region 106, and the vertex of the corresponding triangular electric field in the drift region 104 may move to the right, so that the triangular area is increased, thereby ensuring the increase of the bearing voltage of the LDMOS terminal structure, and at the same time, adjusting the height of the field plate, i.e. the distance near the N region, may promote the electric field intensity at the corresponding position of the N region, i.e. the edge of the triangular electric field near the drain contact region 106 may bulge, and similarly enhance the bearing voltage of the device. However, the P-type region is covered in the process that the field plate extends to the upper portion of the N-type region from the region of the drain contact region 106 crossing the PN junction interface, which leads to the pressure-bearing reduction of the P-type region.
According to an embodiment of the present application, as shown in fig. 8 and 9, the substrate 10 further includes a source contact region 105, a drain contact region 106, a source 107, and a drain 108, wherein the source contact region 105 is located in the body region 103, a surface of the source contact region 105 away from the substrate 101 is flush with a surface of the epitaxial layer 102 away from the substrate 101, and doping types of the source contact region 105 and the body region 103 are different; the drain contact region 106 is located in the drift region 104, a surface of the drain contact region 106 away from the substrate 101 is flush with a surface of the drift region 104 away from the substrate 101, and a doping type of the drain contact region 106 is the same as a doping type of the drift region 104; the source electrode 107 is located on a portion of the surface of the source contact region 105 remote from the substrate 101; the drain electrode 108 is located on a portion of the surface of the drain contact region 106 remote from the substrate 101. The substrate further comprises the source contact region, the drain contact region, the source electrode and the drain electrode, so that the source electrode can be led out through the source contact region, the drain electrode can be led out through the drain contact region, the performance of the LDMOS device can be realized, and the better performance of the LDMOS device is further ensured.
According to another embodiment of the present application, as shown in fig. 8 and 9, the LDMOS terminal structure further comprises a gate dielectric layer 30, a gate electrode 40 and a dielectric layer 50, wherein the gate dielectric layer 30 is located on a part of the surface of the substrate 10, the gate dielectric layer 30 covers a part of the body region 103 and a part of the epitaxial layer 102, and the gate dielectric layer 30 is not in contact with the source contact region 105; the gate electrode 40 is located on a surface of the gate dielectric layer 30 away from the substrate 10, and projections of the gate dielectric layer 30 and the gate electrode 40 in the field plate structure 20 are located in the first through hole 203; the dielectric layer 50 covers the gate dielectric layer 30, the gate electrode 40, and the surface of the epitaxial layer 102 away from the substrate 101, the surface of the dielectric layer 50 away from the epitaxial layer 102 is a plane, the source electrode 107 and the drain electrode 108 penetrate the dielectric layer 50, and the field plate structure 20 is located on the surface of the dielectric layer 50 away from the substrate 10. The LDMOS terminal structure further comprises the gate dielectric layer, the grid electrode and the dielectric layer, so that the performance of the LDMOS device can be realized through the grid electrode, and the better performance of the LDMOS device is further ensured.
In one embodiment, as shown in fig. 8, the surface area of the gate electrode 40 near the substrate 10 is smaller than the surface area of the gate electrode 40 near the substrate 10. That is, the angle of the grid electrode, which is close to the substrate, is not a right angle, so that the grid electrode has an optimization function on the electric field of the substrate, the breakdown voltage of the semiconductor device is guaranteed to be higher, and the performance of the semiconductor device is further guaranteed to be better.
In order to further ensure that the performance of the LDMOS termination structure is better, according to a further embodiment of the application, the epitaxial layer is located on a part of the predetermined surface of the substrate, as shown in fig. 8 and 9, the LDMOS termination structure further comprises a first metal layer 60, the first metal layer 60 being located on a further part of the predetermined surface of the substrate 101, and a surface of the first metal layer 60 remote from the substrate 101 being level with a surface of the dielectric layer 50 remote from the substrate 101, the first metal layer 60 being for electrically connecting the source contact region 105 to the substrate 101, the field plate structure 20 being in contact with the first metal layer 60. Because the epitaxial layer is positioned on the preset surface of the part of the substrate, and the first metal layer is positioned on the preset surface of the other part of the substrate, namely the epitaxial layer is contacted with the first metal layer and is positioned on the substrate, and because the first metal layer is used for electrically connecting the source contact area and the substrate, the source contact area can be connected with the substrate through the first metal layer, namely the grounding is realized, and the device of the LDMOS is further ensured to be better.
Specifically, the predetermined surface is a surface of the substrate adjacent to the epitaxial layer, the epitaxial layer is located on a part of the surface of the substrate, the first metal layer is in contact with the epitaxial layer, and the first metal layer is located on another part of the predetermined surface of the substrate.
According to an embodiment of the present application, as shown in fig. 8 and 9, the LDMOS terminal structure further includes a second metal layer 70, the second metal layer 70 is located on a portion of the surface of the dielectric layer 50 away from the substrate 10, the second metal layer 70 is in contact with the drain 108, the second metal layer 70 is spaced apart from the field plate structure 20, and the second metal layer 70 and the field plate structure 20 expose a portion of the dielectric layer 50. The LDMOS terminal structure further comprises the second metal layer, and the second metal layer is in contact with the drain electrode, so that the drain contact region can be led out through the second metal layer and the drain electrode, namely, the drain electrode and the drain contact region can be connected through the second metal layer, and the better performance of the LDMOS device is further ensured.
According to another embodiment of the application, the material of the field plate structure comprises aluminum. Of course, the structure of the field plate is not limited to aluminum, and other materials such as tungsten and copper may be selected, and the structure is not limited thereto.
In order to further ensure that the performance of the LDMOS device is better, according to still another embodiment of the present application, the doping type of the epitaxial layer is P-type, and the doping type of the drift region is N-type. Because the doping type of the epitaxial layer is P type, the doping type of the drift region is N type, namely, a reverse PN junction is formed between the epitaxial layer of P type and the drift region of N type, so that pressure bearing can be carried out through the formed reverse PN junction, the distribution optimization of the electric field of the LDMOS terminal device is realized, the breakdown voltage of the LDMOS is ensured to be higher, and the performance of the LDMOS device is further ensured to be better.
Specifically, the terminal voltage-resistant structure of the current LDMOS device is generally a reverse PN junction formed between a P heavily doped region at a source and an N-type drift region, and the main design thought of the terminal structure of the current drain-wrapped source is to add a P shallow doped region between the P heavily doped region of the source and the N-type drift region of the drain, so that the voltage-resistant value of the whole terminal is improved by forming a more slowly-changed PN junction, the possibility of process implementation is generally considered, the P shallow doped region is generally borne by a P-type epitaxial layer, but the electric field strength is rapidly reduced within the range of the N-type drift region due to the injection concentration difference between the P-type epitaxial layer and the N-type drift region, so that the breakdown voltage lifting amplitude of the LDMOS device is limited, the surface electric field of the N-type region can be optimized for the reverse PN junction through a field plate, and the breakdown voltage is lifted, however, the P-type region is covered by the design field plate, the voltage-resistant equipotential line is produced due to the low potential of the field plate, and the strength of the P-type drift region is reduced with the voltage-resistant force of the P-type region. According to the LDMOS terminal structure, the field plate structure comprising the field plate body and the arc-shaped field plate is designed, on one hand, the electric field distribution of the terminal is optimized through bearing the reverse PN junction formed between the P-type epitaxial layer and the N-type drift region, on the other hand, the electric field distribution in the drift region can be optimized through the arc-shaped field plate above the N-type drift region, and on the other hand, the projection of the epitaxial layer between the body region and the drift region in the field plate structure is positioned in the first through hole, namely, the corresponding part of the field plate structure is hollowed out of the P-type epitaxial layer, so that the electric field influence of the field plate structure on the P-type epitaxial layer is smaller, the electric field optimization effect on the P-type epitaxial layer region is realized, the breakdown voltage of the LDMOS device is further ensured to be higher, and the LDMOS device performance is further ensured to be better.
In a specific embodiment, by performing an actual potential line distribution test on the LDMOS terminal structure of the non-hollowed-out field plate in the prior art and the LDMOS terminal structure including the hollowed-out field plate in the application, it can be obtained that, although the field plate of the LDMOS terminal structure in the prior art can play a role in enhancing the surface electric field of the NLDD (N-type low doped drain region), the equipotential lines are pinned by the zero potential field plate, so that the bearing capacity of the P-type epitaxial region of the LDMOS terminal structure is reduced, the full bearing capacity of the LDMOS terminal structure in the prior art cannot be exerted, the actual test can be obtained, and by setting the field plate structure of the hollowed-out field plate, part of the potential lines of the drain terminal are released, so that the bearing capacity of the epitaxial layer is enhanced, and in addition, the electric field strength distribution diagram of the field plate structure of the LDMOS terminal structure (i.e. the hollowed-out field plate) of the LDMOS terminal structure in the prior art is not too much reduced.
According to the embodiment of the application, a manufacturing method of the LDMOS terminal structure is also provided.
Fig. 10 is a flowchart of a method for fabricating an LDMOS termination structure according to an embodiment of the application. As shown in fig. 10, the method includes the steps of:
step S101, as shown in fig. 3, providing a base 10, where the base 10 includes a substrate 101, an epitaxial layer 102, a body 103 and a drift region 104, the epitaxial layer 102 is located on the surface of the substrate 101, the body 103 and the drift region 104 are spaced apart from each other and are disposed in the epitaxial layer 102, the doping types of the epitaxial layer 102 and the body 103 are the same, the doping types of the drift region 104 and the epitaxial layer 102 are different, and the doping concentration of the drift region 104 is greater than the doping concentration of the epitaxial layer 102;
in step S102, as shown in fig. 8 and 9, a field plate structure 20 is formed on a side of the epitaxial layer 102 away from the substrate 101, the field plate structure 20 includes a field plate base 201 and an arc field plate 202 located on a side of the field plate base 201, the field plate base 201 is disposed in contact with the arc field plate 202, the field plate structure 20 has a first through hole 203, the first through hole 203 is located between the field plate base 201 and the arc field plate 202, a projection of the arc field plate 202 covers the drift region 104 in the base 10, a projection of the field plate base 201 covers the body region 103 in the base 10, and a projection of the epitaxial layer 102 between the body region 103 and the drift region 104 in the field plate structure 20 is located in the first through hole 203.
In the method for manufacturing the LDMOS terminal structure, firstly, a substrate is provided, the substrate comprises a substrate, an epitaxial layer, a body region and a drift region, the epitaxial layer is positioned on the surface of the substrate, the body region and the drift region are arranged in the epitaxial layer in a spacing mode, the doping types of the epitaxial layer and the body region are the same, the doping types of the drift region and the epitaxial layer are different, and the doping concentration of the drift region is larger than that of the epitaxial layer; then, a field plate structure is formed on a side of the epitaxial layer away from the substrate, the field plate structure includes a field plate base and an arc field plate located on a side of the field plate base, the field plate base is in contact with the arc field plate, the field plate structure has a first through hole, the first through hole is located between the field plate base and the arc field plate, a projection of the arc field plate in the substrate covers the drift region, a projection of the field plate base in the substrate covers the body region, and a projection of the epitaxial layer between the body region and the drift region in the field plate structure is located in the first through hole. Compared with the problem of poor performance of the device caused by lower breakdown voltage of the device in the prior art, the manufacturing method of the LDMOS terminal structure of the application comprises the steps of providing the substrate comprising the substrate, the epitaxial layer, the body region and the drift region, forming the field plate structure on one side of the epitaxial layer far away from the substrate, wherein the field plate structure comprises the field plate body and the arc-shaped field plate, and the arc-shaped field plate covers part of the drift region due to the fact that the projection of the arc-shaped field plate in the substrate covers part of the drift region, so that the electric field distribution in the drift region can be optimized through the field plate structure, and in addition, the projection of the epitaxial layer between the body region and the drift region in the field plate structure is positioned in the first through hole, namely the field plate structure enables part of the epitaxial layer to be hollowed out, the electric field effect of the field plate structure on the epitaxial layer of the LDMOS is smaller, the electric field distribution of the LDMOS device is optimized, and the breakdown voltage of the device is higher, and the better performance of the semiconductor device is guaranteed.
Specifically, compared with the prior art, the process for forming the substrate and the field plate structure does not need additional design or additional process steps, and in the manufacturing process of the LDMOS terminal structure, the process integration level of the LDMOS terminal structure is high and simple only by designing the hollowed-out field plate structure.
In a specific embodiment, the position of the field plate structure and/or the width of the first through hole may be adjusted according to actual requirements, so that the breakdown voltage of the LDMOS device is higher.
According to a specific embodiment of the present application, there is provided a substrate comprising: as shown in fig. 1, the substrate 101 and the epitaxial layer 102 are provided as a stack; as shown in fig. 2, a gate dielectric layer 30 is formed on a portion of the surface of the epitaxial layer 102 away from the substrate 101, and a gate electrode 40 is formed on a surface of the gate dielectric layer 30 away from the base 10; as shown in fig. 3, ion implantation is performed in the epitaxial layer 102 on both sides of the gate dielectric layer 30 and the gate electrode 40 to form the body region 103, the drift region 104, a source contact region 105 and a drain contact region 106, the gate dielectric layer 30 covers a portion of the body region 103 and a portion of the epitaxial layer 102, the gate dielectric layer 30 is not in contact with the source contact region 105, the projections of the gate dielectric layer 30 and the gate electrode 40 in the field plate structure 20 are located in the first through hole 203, the source contact region 105 is located in the body region 103, a surface of the source contact region 105 away from the substrate 101 is flush with a surface of the epitaxial layer 102 away from the substrate 101, the source contact region 105 is different in doping type from the body region 103, the drain contact region 106 is located in the drift region 104, a surface of the drain contact region 106 away from the substrate 101 is flush with a surface of the drift region 104 away from the substrate 101, and the doping type of the drain contact region 106 is the same as the drift region 104. The substrate and the epitaxial layer are provided in a stacked mode, the gate dielectric layer is formed on the part of the surface, far away from the substrate, of the epitaxial layer, the grid electrode is formed on the surface, far away from the substrate, of the gate dielectric layer, and finally the body region, the drift region, the source contact region and the drain contact region are obtained through ion implantation of the epitaxial layer, so that the substrate can be obtained through a simpler process, and the manufacturing process of the LDMOS device is simpler.
In addition, as the body region and the drift region are arranged at intervals, and the doping concentration of the drift region is larger than that of the epitaxial layer, the epitaxial layer with smaller concentration exists between the body region and the drift region, and the doping types of the epitaxial layer and the drift region are different, so that a reverse PN junction is formed between the epitaxial layer and the drift region, and pressure bearing can be carried out through the reverse PN junction, the electric field distribution of the semiconductor device is guaranteed to be good, the breakdown voltage of the semiconductor device is guaranteed to be high, and the performance of the semiconductor device is further guaranteed to be good.
In order to further ensure that the manufacturing process of the LDMOS terminal structure is simpler, according to another embodiment of the present application, forming a gate dielectric layer on a portion of the surface of the epitaxial layer away from the substrate, and forming a gate electrode on a surface of the gate dielectric layer away from the substrate, includes: as shown in fig. 1, a preliminary gate dielectric layer 80 and a preliminary gate 90 are formed on a surface of the epitaxial layer 102 remote from the substrate 101; as shown in fig. 2, a portion of the preliminary gate dielectric layer 80 and a portion of the preliminary gate electrode 90 are removed, the remaining preliminary gate dielectric layer 80 forms the gate dielectric layer 30, and the remaining preliminary gate electrode 90 forms the gate electrode 40. By forming the laminated preparation gate dielectric layer and the preparation gate electrode on the surface of the epitaxial layer far away from the substrate and removing part of the preparation gate dielectric layer and part of the preparation gate electrode, the gate dielectric layer and the gate electrode can be obtained through a simpler process, and the manufacturing process of the LDMOS terminal structure is further ensured to be simpler.
According to a further embodiment of the present application, before forming the field plate structure on the side of the epitaxial layer remote from the substrate, the method further comprises: as shown in fig. 4, a preliminary dielectric layer 100 is formed on the exposed surface of the epitaxial layer 102, the surface of the preliminary dielectric layer 100 away from the epitaxial layer 102 is a plane, and the field plate structure 20 is located on the surface of the preliminary dielectric layer 100 away from the substrate 10; as shown in fig. 4 and 5, a portion of the preliminary dielectric layer 100 is removed, and a second via hole 110 and a third via hole 120 are formed, wherein the second via hole 110 and the third via hole 120 expose a portion of the source contact region 105 and a portion of the drain contact region 106, respectively; as shown in fig. 5, a portion of the preliminary dielectric layer 100, a portion of the source contact region 105, a portion of the body region 103, and a portion of the epitaxial layer 102 are removed to form a fourth via 130, the fourth via 130 exposes a portion of the substrate 101, and the remaining preliminary dielectric layer 100 forms a dielectric layer 50; as shown in fig. 6, a metal material is formed in the second via hole 110, the third via hole 120, and the fourth via hole 130, and a source electrode 107, a drain electrode 108, and a first metal layer 60 are formed, respectively, the first metal layer 60 is used to electrically connect the source contact region 105 and the substrate 101, and the field plate structure 20 is in contact with the first metal layer 60. The second via hole and the third via hole are obtained by forming the preliminary dielectric layer on the exposed surface of the epitaxial layer, and then removing part of the preliminary dielectric layer, and the fourth via hole is obtained by removing part of the preliminary dielectric layer, part of the source contact region, part of the body region and part of the epitaxial layer, the second via hole, the third via hole and the fourth via hole expose the source contact region, the drain contact region and the substrate, respectively, and then the source electrode, the drain electrode and the first metal layer are obtained by depositing the metal materials in the second via hole, the third via hole and the fourth via hole, respectively, so that the source contact region can be led out through the source electrode, the drain contact region can be led out through the drain electrode, the source contact region and the substrate can be electrically connected through the first metal layer, and the grounding of the source contact region can be realized, and the device performance can be further ensured.
Specifically, the epitaxial layer is located on a portion of the predetermined surface of the substrate, and the first metal layer is located on another portion of the predetermined surface of the substrate.
According to a specific embodiment of the present application, a field plate structure is formed on a side of the epitaxial layer away from the substrate, including: as shown in fig. 7, a preliminary field plate structure 140 is formed on a surface of the dielectric layer 50 away from the substrate 10; as shown in fig. 8, a portion of the preliminary field plate structure 140 is removed, so that a portion of the dielectric layer 50 is exposed, and the remaining preliminary field plate structure 140 forms the field plate structure 20 and the second metal layer 70 disposed at intervals, and the second metal layer 70 contacts the drain electrode 108. The field plate structure and the second metal layer are formed by forming the preparation field plate structure on the surface of the dielectric layer far away from the substrate and removing part of the preparation field plate structure, and the field plate structure comprises the field plate base and the arc-shaped field plate positioned at one side of the field plate base, and the projection of the arc-shaped field plate in the substrate covers part of the drift region, so that the electric field distribution in the drift region can be optimized through the field plate structure.
In addition, by forming the second metal layer and making the second metal layer contact with the drain electrode, the drain contact region can be led out through the second metal layer and the drain electrode, that is, the drain electrode and the drain contact region can be connected through the second metal layer, so that better performance of the LDMOS device is further ensured.
Specifically, the metal material includes tungsten, but the metal material is not limited to tungsten, and other metal materials such as copper may be selected, and the metal material is not limited thereto.
In the foregoing embodiments of the present application, the descriptions of the embodiments are emphasized, and for a portion of this disclosure that is not described in detail in this embodiment, reference is made to the related descriptions of other embodiments.
From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:
1) The LDMOS terminal structure comprises a substrate, an epitaxial layer, a body region and a drift region, wherein the substrate comprises the substrate, the epitaxial layer and the substrate are stacked, the body region and the drift region are arranged in the epitaxial layer in a spacing mode, the doping types of the epitaxial layer and the body region are the same, the doping types of the drift region and the epitaxial layer are different, and the doping concentration of the drift region is larger than that of the epitaxial layer; the field plate structure is located on one side of the epitaxial layer far away from the substrate, the field plate structure comprises a field plate base and an arc-shaped field plate located on one side of the field plate base, the field plate base is in contact with the arc-shaped field plate, the field plate structure is provided with a first through hole, the first through hole is formed between the field plate base and the arc-shaped field plate in a surrounding mode, a projection covering part of the arc-shaped field plate in the substrate covers the drift region, a projection covering part of the field plate base in the substrate covers the body region, and a projection of the epitaxial layer between the body region and the drift region in the field plate structure is located in the first through hole. Compared with the problem of poor performance of a device caused by lower breakdown voltage of the device in the prior art, the LDMOS terminal structure of the application further comprises the field plate structure by providing the substrate comprising the substrate, the epitaxial layer, the body region and the drift region, wherein the field plate structure comprises the field plate body and the arc-shaped field plate, the electric field distribution in the drift region can be optimized through the field plate structure due to the fact that the projection of the arc-shaped field plate in the substrate covers part of the drift region, and in addition, the projection of the epitaxial layer between the body region and the drift region in the field plate structure is positioned in the first through hole, namely the field plate structure enables part of the epitaxial layer to be hollowed out, so that the field effect of the field plate structure on the epitaxial layer is smaller, the electric field distribution of the LDMOS device is optimized, the breakdown voltage of the device is ensured to be higher, and the performance of the semiconductor device is further ensured to be better.
2) In the method for manufacturing the LDMOS terminal structure, firstly, a substrate is provided, the substrate comprises a substrate, an epitaxial layer, a body region and a drift region, the epitaxial layer is positioned on the surface of the substrate, the body region and the drift region are arranged in the epitaxial layer in a space mode, the doping types of the epitaxial layer and the body region are the same, the doping types of the drift region and the epitaxial layer are different, and the doping concentration of the drift region is larger than that of the epitaxial layer; then, a field plate structure is formed on a side of the epitaxial layer away from the substrate, the field plate structure includes a field plate base and an arc field plate located on a side of the field plate base, the field plate base is in contact with the arc field plate, the field plate structure has a first through hole, the first through hole is located between the field plate base and the arc field plate, a projection of the arc field plate in the substrate covers the drift region, a projection of the field plate base in the substrate covers the body region, and a projection of the epitaxial layer between the body region and the drift region in the field plate structure is located in the first through hole. Compared with the problem of poor performance of the device caused by lower breakdown voltage of the device in the prior art, the manufacturing method of the LDMOS terminal structure of the application comprises the steps of providing the substrate comprising the substrate, the epitaxial layer, the body region and the drift region, forming the field plate structure on one side of the epitaxial layer far away from the substrate, wherein the field plate structure comprises the field plate body and the arc-shaped field plate, and the arc-shaped field plate covers part of the drift region due to the fact that the projection of the arc-shaped field plate in the substrate covers part of the drift region, so that the electric field distribution in the drift region can be optimized through the field plate structure, and in addition, the projection of the epitaxial layer between the body region and the drift region in the field plate structure is positioned in the first through hole, namely the field plate structure enables part of the epitaxial layer to be hollowed out, the electric field effect of the field plate structure on the epitaxial layer of the LDMOS is smaller, the electric field distribution of the LDMOS device is optimized, and the breakdown voltage of the device is higher, and the better performance of the semiconductor device is guaranteed.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.