CN216389378U - Groove type power device - Google Patents
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- CN216389378U CN216389378U CN202123057017.5U CN202123057017U CN216389378U CN 216389378 U CN216389378 U CN 216389378U CN 202123057017 U CN202123057017 U CN 202123057017U CN 216389378 U CN216389378 U CN 216389378U
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Abstract
The utility model discloses a trench type power device, comprising: a substrate; a drift region formed on the first surface of the substrate; a body region formed on the drift region, wherein the doped ions in the body region are heavy ions; a first electrode layer formed on the body region; a trench extending from a surface of the first electrode layer remote from the substrate into the drift region; a gate insulating layer and a polysilicon gate formed in the trench; an isolation layer covering the first electrode layer and the trench; electrode contact holes extending from the surface of the isolation layer away from the substrate to at least the body region away from the substrate surface; a metal plug formed in the contact hole, electrically connected to the first electrode layer; a second electrode layer formed on a second surface of the substrate opposite the first surface. According to the trench type power device, heavy ions which are not easy to diffuse are used as doping ions, a body area which is uniform in concentration and basically flat can be provided, a more complex process is not required to be considered, the process difficulty of device manufacturing is reduced, and the risk of device breakdown is effectively reduced.
Description
Technical Field
The utility model relates to the technical field of semiconductors, in particular to a trench type power device.
Background
Power Semiconductor devices are basic electronic components for energy conversion and control of power electronic systems, and the continuous development of power electronic technology has opened up a wide application Field for power Semiconductor devices, and power Semiconductor devices represented by Metal-Oxide-Semiconductor Field-Effect transistors (MOSFETs) and Insulated Gate Bipolar Transistors (IGBTs) are the mainstream in the Field of power electronic devices today.
The gate structures of MOSFETs and IGBTs include a trench type and a planar type. The groove type power device has the advantages that the grid electrode is located in the groove, the tube core area is greatly reduced, the utilization rate of the wafer is improved, and the groove type power device has the characteristics of high input impedance, low driving power, no minority carrier storage effect, lower on resistance, grid-leakage charge density, larger current capacity and the like in the aspect of electrical performance, so that the groove type power device has lower switching power consumption and higher switching speed.
In the conventional trench power device, as shown in fig. 1, the reverse voltage is mainly borne by forming an inversion blocking region 12 (i.e. the body region of the device), wherein the inversion blocking region 12 is formed after the trench 11 is formed, and then performing one or more inversion ion implantations on the epitaxial region 10, and implanting light ions (e.g. implanting light ions in the N-type epitaxial region 10)11B+(ii) a Or P31 implanted in the P-type epitaxial region) is then formed by annealing the push junction. Therefore, this region is very susceptible to ion diffusionA certain concentration gradient (gradually decreasing from top to bottom) is formed. The channel is formed on the surface of the inversion blocking region 12 in contact with the gate insulating layer 14, and due to the existence of the concentration gradient, the channel resistance of the inversion blocking region 12 is relatively dispersed, so that the partial pressure of each section of the channel is different, and the process control is challenged.
In addition, because the gate insulating layer has the characteristics of absorbing boron and discharging phosphorus, the junction depth of the inversion blocking region near the gate insulating layer becomes shallow in the conventional inversion blocking, specifically, the junction depth of the inversion blocking region near the trench gate is smaller than the junction depth of the inversion blocking region at other parts (such as the bending region of the inversion blocking region in fig. 1), and the PN junction formed between the inversion blocking region and the epitaxial region 10 also causes the reduction of the breakdown voltage due to the bending, which reduces the voltage withstanding performance of the device.
Furthermore, in the conventional process, the trench is usually deep (e.g. 1 to 2 μm), when the gate insulating layer is formed in the trench, the insulating layer formed at a position closer to the bottom of the trench, especially at a transition region between the sidewall and the bottom wall, tends to be uneven and thin, and in the case where the inversion layer has a bending region, the uneven gate insulating layer is exposed at the bending region, so that the region is easily broken down.
Secondly, during the manufacturing process, the uneven distance between the source terminal (metal plug) 16 and the adjacent gate channel region may cause the uneven distribution of the base resistance of the transistor, i.e. the source region 18, the inversion blocking region 12, and the epitaxial region 10, which theoretically requires that R1 ≠ R2 in fig. 1, if the source terminal 16 is shifted (registration deviation occurs during photolithography), R1 ≠ R2 will be caused, so that the voltage obtained by the base terminal of the transistor shown in fig. 1 is different, and once the resistance is increased to a degree enough to turn on the transistor, the body transistor is turned on, and the device is not enough to withstand the expected withstand voltage value of the device, so that the device is broken down or even burned out. Therefore, the distance from the source terminal to the adjacent gate channel region has to be increased to increase the base resistance (increasing the distance from the terminal to the gate can increase the resistances of R1 and R2, and increase the resistance to an extent that the base of the transistor does not satisfy the turn-on condition), or increase the registration accuracy of the source terminal (if the photolithography registration is not accurate and has an offset, the left and right R1 ≠ R2 is caused, in order to avoid that a certain terminal R increases to turn on the transistor as shown in fig. 1, the offset needs to be strictly controlled, if the offset is too large, rework is needed to perform photolithography again, which undoubtedly affects the processing efficiency of the product and increases the additional processing cost), and the manufacturing difficulty of the product is increased.
SUMMERY OF THE UTILITY MODEL
In order to solve at least one of the above problems occurring in the prior art, the present invention provides a trench type power device, including:
a substrate having opposing first and second surfaces;
a drift region formed on the first surface of the substrate;
a body region formed on the drift region, wherein the doping ions in the body region are heavy ions;
a first electrode layer formed on the body region;
a trench extending from a surface of the first electrode layer remote from the substrate into the drift region;
a gate insulating layer and a polysilicon gate formed in the trench;
an isolation layer covering the first electrode layer and the trench;
electrode contact holes extending from the surface of the isolation layer away from the substrate at least to the surface of the body region away from the substrate surface;
a metal plug formed in the contact hole, electrically connected to the first electrode layer;
a second electrode layer formed on the second surface of the substrate.
In a specific embodiment, the body region is disposed between regions from 1/5 trench depth to 3/4 trench depth from the bottom of the trench in the vertical substrate direction.
In a specific embodiment, the body region is disposed closer to the bottom of the trench than to the top of the trench.
In a specific embodiment, the trench is a U-shaped trench including an arcuate region between a sidewall and a bottom wall, wherein the body region wraps around the arcuate region.
In one particular embodiment of the present invention,
the conductive type of the substrate is N type;
the conduction type of the body region is P type, wherein heavy ions are BF2Ions.
In one particular embodiment of the present invention,
the conductive type of the substrate is P type;
the conduction type of the body region is N type, wherein the heavy ions are As ions.
In one particular embodiment of the present invention,
the doping concentration of the drift region and the first electrode layer is smaller than that of the substrate;
and the doping concentration of the body region is 10-100 times of the doping concentration of the drift region and the first electrode layer.
In a specific embodiment, the device further comprises:
and a first metal barrier layer and a second metal barrier layer formed between the electrode contact hole and the metal plug, wherein the first metal barrier layer is in contact with an inner wall of the contact hole, and the second metal barrier layer is in contact with the metal plug.
In one particular embodiment of the present invention,
the first metal barrier layer is made of Ti;
the second metal barrier layer is made of TiN;
the material of the metal plug is W.
In one particular embodiment of the present invention,
the groove type power device is an MOSFET, wherein the first electrode layer is a source electrode, and the second electrode layer is a drain electrode; or
The trench power device is an IGBT, wherein the first electrode layer is an emitter, and the second electrode layer is a collector.
The utility model has the following beneficial effects:
the trench type power device disclosed by the utility model adopts the heavy ions which are not easy to diffuse as the doping ions, and can provide the inversion region (namely the body region) with uniform concentration and basically flat. The body region enables the channel resistance to be more uniform, and the base resistance of the body triode is also more uniformly distributed, so that the complex process in the prior art is not required to be considered, and the process difficulty is reduced; and the basically flat body region can effectively reduce the risk that the device does not reach the expected withstand voltage value in the region and breaks down in advance. On the other hand, the body region of the trench device can be arranged at the bottom of the trench, particularly a transition region covering the side wall and the bottom wall of the trench, so that the region is not easy to break down.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings;
figure 1 shows a schematic diagram of a trench-type power device according to the prior art;
figure 2 shows a schematic diagram of a trench-type power device according to one embodiment of the present invention;
fig. 3a-3f show intermediate schematic diagrams corresponding to a method of fabricating a trench-type power device according to an embodiment of the utility model.
Fig. 4 shows a schematic diagram of a trench-type power device according to another embodiment of the utility model.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.
The references to "on … …", "formed on … …" and "disposed on … …" in this disclosure may mean that one layer is formed or disposed directly on another layer, or that one layer is formed or disposed indirectly on another layer, i.e., there is another layer between the two layers.
It should be noted that, although the terms "first", "second", etc. may be used herein to describe various elements, components, elements, regions, layers and/or sections, these elements, components, elements, regions, layers and/or sections should not be limited by these terms. Rather, these terms are used to distinguish one element, component, element, region, layer or section from another.
As shown in fig. 2, an embodiment of the present invention provides a trench type power device, which may be specifically a trench type MOSFET, an IGBT, or other power devices.
The power device includes:
a substrate 300, the substrate 300 having a first surface (i.e., the top surface of the substrate in the figure) and a second surface (i.e., the bottom surface of the substrate in the figure) opposite to each other;
a drift region 305 formed on the first surface of the substrate 300;
a body region 310 formed over the drift region 305, wherein the dopant ions in the body region 310 are heavy ions;
a first electrode layer 315 formed on the body region 310;
a trench (see reference numeral 320 in subsequent fig. 3 d) extending from the surface of the first electrode layer 315 remote from the substrate 300 (i.e. the top surface of the first electrode layer in the figure) through the body region 310 into the drift region 305;
a gate insulating layer 325 and a polysilicon gate 330 formed in the trench;
an isolation layer 335 covering the first electrode layer 315 and the trench 320;
contact holes (see reference numeral 340 in subsequent figure 3 f) extending from the surface of the isolation layer 335 remote from the substrate 300 (i.e., the top surface of the isolation layer in the figure) at least to the surface of the body region 310 remote from the substrate 300 (i.e., the top surface of the body region in the figure);
a metal plug 345 formed in the contact hole and electrically connected to the first electrode layer 315;
a second electrode layer 355 formed on the second surface of the substrate 300.
In a specific example, the substrate 300 of the power device is typically a silicon substrate, a silicon carbide substrate, but the utility model is not limited thereto.
In addition, the doping types of the substrate 300 and the drift region 305 are not particularly limited in the present invention. If the trench power device is a MOSFET, the substrate 300 and the drift region 305 are usually doped with the same type, for example, the substrate 300 and the drift region 305 are both doped N-type or both doped P-type. If the trench power device is an IGBT, the doping types of the substrate 300 and the drift region 305 may be different, for example, the substrate 300 is P-type doped, and the drift region 305 is N-type doped. The utility model is not limited thereto, and the doping types of the two can be controlled according to the actual device type and parameter requirements.
As for the doping concentration, in the trench type power device, the doping concentration of the substrate 300 is generally controlled to be greater than that of the drift region 305. The present invention is not limited thereto and the doping concentrations of both may be controlled according to the actual device type and parameter requirements.
In addition, the larger the thickness of the drift region 305, the more favorable the breakdown voltage of the device, especially in an IGBT, but the less favorable the miniaturization of the device. The thickness of the substrate 300 and the drift region 305 can be determined by one skilled in the art according to actual requirements. In a specific example, the thickness of the drift region 305 is greater than the depth of a subsequently fabricated trench; in other embodiments, the thickness of the drift region 305 may be less than or equal to the depth of the subsequently fabricated trench.
In the power device of the present invention, the dopant ions in the body region 310 are heavy ions. The heavy ions referred to in the present invention are ions having a relative atomic mass of more than 40. For example, when the conductivity type of the dopant ions of the body region 310 is P-type, the dopant ions may be BF2Ions, e.g. most commonly used11BF2 +(ii) a When the conductivity type of the dopant ions of the body region 310 is N-type, the dopant ions may be As ions.
The inventor finds that when heavy ions which are not easy to diffuse are doped to form the body region 310, an inversion region (i.e., an inversion blocking region, as shown in fig. 2) with uniform and substantially flat doped ions can be provided, so that the inversion blocking region in the power device is mainly concentrated in a designated region, the body region 310 enables channel resistance to be uniform, base resistance of the body triode is also uniform, and therefore the complex process mentioned in the prior art does not need to be considered, and the process difficulty is reduced; moreover, the substantially flat body region 310 can effectively reduce the risk of premature breakdown of the device in the region where the device does not reach the desired breakdown voltage.
In one specific example, body region 310 may be formed using different doping concentrations and thicknesses as desired by the application.
In a specific example, the doping concentration of the body region 310 is higher than that of the drift region 305, and preferably, the doping concentration of the body region is 10-100 times that of the drift region, and the concentration range is 1E15/cm3～2E16/cm3。
In a specific example, the doping type of the first electrode layer 315 is the same as the doping type of the drift region 305.
In the trench type power device, similarly, the doping concentration of the first electrode layer 315 is also smaller than that of the substrate 300. The present invention is not limited thereto and the doping concentrations of both may be controlled according to the actual device type and parameter requirements.
It will be appreciated by those skilled in the art that during fabrication, due to the inevitable high temperature processing involved, the doped ions in the body region 310 will move up and down (back-diffusion), thereby forming buffer layers (not shown) between the body region 310 and the drift region 305, and between the body region 310 and the first electrode layer 315. The buffer layer prevents the doped ions in the body region 310 from continuing to back-expand toward the drift region 305 and the first electrode layer 315 in the subsequent manufacturing process, so that the buffer region does not substantially affect the performance of the device.
In one particular example, the trench 320 is a U-shaped trench.
In one particular example, the trench 320 extends through the body region 310 into the drift region 305.
In other examples, the depth of the trench 320 may be set by one skilled in the art according to actual needs, for example, the bottom of the trench 320 may reach the surface of the substrate 300 through the drift region 305.
In one specific example, the position of the body region 310 in the vertical substrate direction is designed to be related to the depth of the trench 320.
Preferably, body region 310 is disposed between trench depth-3/4 trench depth regions from the bottom 1/5 of trench 320 in the vertical substrate direction, that is, both the top and bottom surfaces of body region 310 are between trench depth-3/4 trench depth regions from the bottom 1/5 of trench 320.
In an actual process, when the gate insulating layer 325 is formed later, the gate insulating layer material on the sidewall of the trench is less likely to be deposited further into the trench (i.e., closer to the bottom of the trench), and the gate insulating layer in these regions is more likely to be thinned, so that the region is easily broken down and the voltage resistance is reduced. Accordingly, in a preferred example, the body region 310 is disposed closer to the bottom of the trench 320 than the top of the trench 320, as shown in fig. 4, for protecting a region where the gate insulating layer is thin.
In the above example where the trench 320 is a U-shaped trench, the gate insulating layer 325 in the arc region between the sidewall and the bottom wall is easily thin, and therefore, it is more preferable that the body region 310 is positioned so as to wrap around the arc region, as shown in fig. 4. That is, the bottom surface of body region 310 is closer to substrate 300 than the arc region (even if the bottom surface of body region 310 is flush with the bottom wall of trench 320), and the top surface of body region 310 is farther from substrate 300 than the arc region.
In fact, in the present invention, since the body region 310 is formed first, it is necessary to design the position of the body region 310 first according to the depth of the trench 320 or the depth of the trench 320 according to the position of the body region 310 in consideration of the above-mentioned situation, which are related.
In one specific example, the material of the gate insulating layer 325 may include one of silicon oxide, silicon oxynitride, and a high-K gate dielectric material. The thickness of the gate insulating layer 325 may be set according to the requirement of the threshold voltage.
In one particular example, the material of the isolation layer 335 may include silicon oxide or silicon nitride.
In the case where the power device is a MOSFET, the first electrode layer 315 between the metal plug 345 and the trench 320 constitutes a source. In the case where the power device is an IGBT, the first electrode layer 315 between the metal plug 345 and the trench 320 constitutes an emitter, and the metal plug 345 serves as a lead-out terminal of the source or the emitter and is electrically connected thereto.
Preferably, a metal barrier layer (not shown) is also formed in the contact hole 340. The metal barrier layer may specifically include a first metal barrier layer contacting an inner wall of the contact hole 340 and a second metal barrier layer contacting the metal plug 345. That is, the first metal barrier layer covers the second metal barrier layer, and the second metal barrier layer covers the metal plug 345.
In a specific example, Ti and TiN are used for the material of the first metal barrier layer and the material of the second metal barrier layer, respectively. Wherein, Ti can form metal silicide with the first electrode layer (Si material) to reduce the contact resistance, and TiN can also block the sharp pricks caused by the alloy process.
In one particular example, the power device may further include a passivation layer 350 covering the surface of the device.
In a specific example, when the trench power device is a MOSFET, the second electrode layer 355 serves as a drain.
In another specific example, when the trench type power device is an IGBT, the second electrode layer 355 serves as a collector.
Fig. 3a to 3f are schematic diagrams illustrating device structures corresponding to steps of an exemplary manufacturing method of the trench type power device shown in fig. 2. It should be noted that this method is merely exemplary, and the trench type power device shown in fig. 2 can be manufactured by not only the following method.
Referring to fig. 3a, a substrate 300 is provided.
In a specific example, the substrate 300 of the power device is typically a silicon substrate, a silicon carbide substrate, but the utility model is not limited thereto.
A drift region 305 is formed on the substrate 300.
For example, the drift region 305 can be obtained by depositing an epitaxial layer on the surface of the substrate 300 by using a Chemical Vapor Deposition (CVD) or Physical Vapor Deposition (PVD) process.
In another alternative example, the drift region 305 may be formed by ion implantation at the first surface of the substrate 300.
The present invention is not particularly limited with respect to the doping types of the substrate 300 and the drift region 305. If the trench power device is a MOSFET, the doping types of the substrate 300 and the drift region 305 are the same, for example, both the substrate 300 and the drift region 305 are doped N-type or P-type. If the trench power device is an IGBT, the doping types of the substrate 300 and the drift region 305 may be different, for example, the substrate 300 is P-type doped, and the drift region 305 is N-type doped. The utility model is not limited thereto, and the doping types of the two can be controlled according to the actual device type and parameter requirements.
As for the doping concentration, in the trench type power device, the doping concentration of the substrate 300 is generally controlled to be greater than that of the drift region 305. The present invention is not limited thereto and the doping concentrations of both may be controlled according to the actual device type and parameter requirements.
In addition, the larger the thickness of the drift region 305, the more favorable the breakdown voltage of the device, especially in an IGBT, but the less favorable the miniaturization of the device. The thickness of the substrate 300 and the drift region 305 can be determined by one skilled in the art according to actual requirements. In a specific example, the thickness of the drift region 305 is greater than the depth of a subsequently fabricated trench, such that the bottom of the trench is located in the drift region 305; in other embodiments, the thickness of the drift region 305 may be less than or equal to the depth of the subsequently fabricated trench.
Referring to fig. 3b, a body region 310 is formed on the drift region 305.
In one example, the body region 310 may be specifically formed according to a conventional technique in the art, for example, by performing an inversion implantation on the surface of the drift region, or by using a diffusion process, or by using an epitaxial process, or by using any other feasible process, which is not particularly limited herein.
In the power device of the present invention,the dopant ions in body region 310 are heavy ions. The heavy ions referred to in the present invention are ions having a relative atomic mass of more than 40. For example, when the conductivity type of the dopant ion of the body region is P-type, the dopant ion may be BF2Ions, e.g.11BF2 +(ii) a When the conductivity type of the dopant ions of the body region 310 is N-type, the dopant ions may be As ions.
The inventor finds that when heavy ions which are not easy to diffuse are doped to form the body region 310, an inversion region (i.e. an inversion blocking region, as shown in the figure) with uniform and basically flat doped ions can be provided, so that the inversion blocking region in the power device is mainly concentrated in a specified region, the channel resistance is uniform through the body region 310, the base resistance distribution of the body triode is uniform, the complex process mentioned in the prior art is not required to be considered, and the process difficulty is reduced; moreover, the substantially flat body region 310 can effectively reduce the risk of premature breakdown of the device in the region where the device does not reach the desired breakdown voltage.
In one specific example, body region 310 may be formed using different doping concentrations and thicknesses as desired by the application.
In a specific example, the doping concentration of the body region 310 is higher than that of the drift region 305, and preferably, the doping concentration of the body region is 10-100 times that of the drift region, and the concentration range is 1E15/cm3～2E16/cm3。
The conventional semiconductor process for manufacturing a power device with a trench gate usually performs ion implantation and annealing after the trench gate structure is manufactured to form a body region, and this process easily results in unexpected device performance. In a specific example of the present application, the above-mentioned problem can be avoided by performing ion implantation to form the body region before the trench gate structure is fabricated.
Referring to fig. 3c, a first electrode layer 315 is formed on the body region 310.
In one example, the first electrode layer may be specifically formed according to techniques conventional in the art, such as using an epitaxial process, a physical vapor deposition process, and the like.
The doping type of the first electrode layer is the same as the doping type of the drift region.
In the trench type power device, similarly, the doping concentration of the first electrode layer 315 is also smaller than that of the substrate 300. The present invention is not limited thereto and the doping concentrations of both may be controlled according to the actual device type and parameter requirements.
It will be appreciated by those skilled in the art that during fabrication, due to the inevitable high temperature processing involved, the doped ions in the body region 310 will move up and down (back-diffusion), thereby forming buffer layers (not shown) between the body region 310 and the drift region 305, and between the body region 310 and the first electrode layer 315. The buffer layer prevents the doped ions in the body region 310 from continuing to back-expand toward the drift region 305 and the first electrode layer 315 in the subsequent manufacturing process, so that the buffer region does not substantially affect the performance of the device.
Referring to fig. 3d, a trench 320 is formed extending from the first electrode layer 315 into the drift region 305 away from the first surface (i.e., top surface) of the substrate 300.
In a specific example, a mask is disposed on the surface of the first electrode layer 315 to define a formation region of the trench 320, and the first electrode layer 315 is anisotropically etched through a window on the mask to form the trench 320.
In one particular example, the trench 320 is a U-shaped trench.
The etching solution can be obtained by anisotropic etching means such as ion milling etching, plasma etching, reactive ion etching, laser ablation and the like, and is not particularly limited. The depth of the trench can be specifically adjusted by controlling the etching time and the etching rate.
Further, in order to avoid a tip problem of a subsequently formed trench gate structure, the trench may be rounded, so that the inner wall of the trench 320 is smooth.
In one particular example, the trench 320 extends through the body region 310 into the drift region 305.
In other embodiments, the depth of the trench may be set by those skilled in the art according to actual needs, for example, the bottom of the trench may even reach the surface of the substrate 300 through the drift region 305.
To improve device performance, in one example, the location of body region 310 in the vertical substrate direction is designed to correlate with the depth of trench 320.
Preferably, body region 310 is disposed between trench depth-3/4 trench depth regions from the bottom 1/5 of trench 320 in the vertical substrate direction, that is, both the top and bottom surfaces of body region 310 are between trench depth-3/4 trench depth regions from the bottom 1/5 of trench 320.
In an actual process, when the gate insulating layer 325 is formed later, the gate insulating layer material on the sidewall of the trench 320 is less likely to be deposited further into the trench 320, and the gate insulating layer 325 in these regions is more likely to be thinned, so that the region is easily broken down and the voltage resistance is reduced. Accordingly, in a preferred example, the body region 310 is disposed closer to the bottom of the trench 320 than the top of the trench 320, as shown in fig. 4, for protecting a thinner region of the gate insulating layer 325.
In the above example where the trench 320 is a U-shaped trench, the gate insulating layer 325 in the arc region between the sidewall and the bottom wall is easily thin, and therefore, it is more preferable that the body region 310 is positioned so as to wrap around the arc region, as shown in fig. 4. That is, the bottom surface of body region 310 is closer to substrate 300 than the arc region (even if body region 310 bottom surface is flush with the bottom wall of trench 320), and the top surface of body region 310 is farther from substrate 300 than the arc region.
In fact, in the present invention, since the body region 310 is formed first, it is necessary to design the position of the body region 310 first according to the depth of the trench 320 or the depth of the trench 320 according to the position of the body region 310 in consideration of the above-mentioned situation, which are related.
Referring to fig. 3e, an insulating layer is grown on the entire device surface and polysilicon filling is performed, thereby forming a gate insulating layer 325 and a polysilicon gate electrode 330 in the trench 320.
Specifically, an insulating layer may be grown by a thermal oxidation process, a chemical vapor deposition process, or the like, and the insulating layer covers the inner wall of the trench 320 and the surface of the first electrode layer 315.
In one specific example, the material of the insulating layer may include one of silicon oxide, silicon oxynitride, and a high-K gate dielectric material. The thickness of the insulating layer can be set according to the threshold voltage requirement.
After the insulating layer is grown, the trench may be filled with polysilicon by a CVD process, and the polysilicon may be doped by thermal diffusion, post-ion implantation annealing, and the like. The doping to the polysilicon can adopt an in-situ doping process, namely the doping is completed simultaneously in the growth process of the polysilicon. The thickness of the polysilicon can be set according to actual requirements as long as the trench is completely filled. Generally, the thickness of the polysilicon needs to be no less than half the width of the widest part of the trench to ensure that the trench 320 is completely filled.
The polysilicon is then subjected to chemical mechanical polishing and etch back so that the upper surface of the polysilicon does not exceed the upper surface of the trench, forming a polysilicon gate 330.
Specifically, the polysilicon is etched by using a dry etching process, a wet etching process, or a dry and wet combined etching process, so as to form the polysilicon gate 330.
Referring to fig. 3f, an isolation layer 335 is formed covering the first electrode layer 315 and the trench.
In one particular example, the isolation layer 335 may be formed by a deposition process. The material of the isolation layer 335 may include silicon oxide or silicon nitride.
With continued reference to fig. 3f, electrode contact holes 340 are formed extending from the surface of isolation layer 335 away from substrate 300 to at least the surface of body region 310 away from the substrate surface.
Specifically, the isolation layer on both sides of the trench is etched using a mask to form an opening that passes through the isolation layer 335, the gate insulating layer 325, and the first electrode layer 315, exposing the upper surface of the body region 310.
In another alternative embodiment, body region 310 may be etched into, i.e., the bottom of contact hole 340 is located in body region 310.
Referring to fig. 2, a metal plug 345 is formed in the contact hole 340.
In the case where the power device is a MOSFET, the first electrode layer 315 between the metal plug 345 and the trench 320 constitutes a source. In the case where the power device is an IGBT, the first electrode layer 315 between the metal plug 345 and the trench 320 constitutes an emitter, and the metal plug 345 serves as a lead-out terminal of the source or the emitter and is electrically connected thereto.
Preferably, before forming the metal plug 345, a first metal barrier layer and a second metal barrier layer (not shown) may also be formed in the contact hole, wherein the first metal barrier layer is in contact with the inner wall of the contact hole 340, and the second metal barrier layer is in contact with the subsequently formed metal plug 345. That is, the first metal barrier layer covers the second metal barrier layer, and the second metal barrier layer covers the metal plug 345.
In a specific example, Ti and TiN may be used for the material of the first metal barrier layer and the material of the second metal barrier layer, respectively. Wherein, Ti can form metal silicide with the second doping layer (Si material) to reduce the contact resistance, and TiN can also block the sharp pricks caused by the alloy process.
After the above structure is completed, a passivation layer 350 covering the surface of the device may be fabricated as desired.
The process for manufacturing the passivation layer is a conventional process and is not described in detail.
It is also possible to thin the second surface (i.e., the backside) of the substrate 300 and form a second electrode layer 355 on the backside of the substrate 300.
In one specific example, the second electrode layer 355 is formed by depositing a metal through a deposition process.
When the trench type power device is formed as a MOSFET, the second electrode layer 355 serves as a drain.
When the trench power device is an IGBT, the substrate 300 is thinned, a PN junction is formed in the substrate 300, and finally metal is deposited on the back surface of the substrate 300 to obtain a second electrode layer 355 serving as a collector.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations and modifications can be made on the basis of the above description, and all embodiments cannot be exhaustive, and all obvious variations and modifications belonging to the technical scheme of the present invention are within the protection scope of the present invention.
Claims (9)
1. A trench-type power device, comprising:
a substrate having opposing first and second surfaces;
a drift region formed on the first surface of the substrate;
a body region formed on the drift region, wherein the doping ions in the body region are heavy ions;
a first electrode layer formed on the body region;
a trench extending from a surface of the first electrode layer remote from the substrate into the drift region;
a gate insulating layer and a polysilicon gate formed in the trench;
an isolation layer covering the first electrode layer and the trench;
electrode contact holes extending from the surface of the isolation layer away from the substrate at least to the surface of the body region away from the substrate surface;
a metal plug formed in the contact hole, electrically connected to the first electrode layer;
a second electrode layer formed on the second surface of the substrate.
2. The trench power device of claim 1,
the body region is disposed between regions of trench depth-3/4 trench depth from the bottom 1/5 of the trench in the vertical substrate direction.
3. The trench power device of claim 2,
the body region is disposed closer to a bottom of the trench than to a top of the trench.
4. The trench power device of claim 3,
the groove is a U-shaped groove and comprises an arc-shaped area between a side wall and a bottom wall, wherein the body area wraps the arc-shaped area.
5. The trench power device of claim 1,
the conductive type of the substrate is N type;
the conduction type of the body region is P type, wherein heavy ions are BF2Ions.
6. The trench power device of claim 1,
the conductive type of the substrate is P type;
the conduction type of the body region is N type, wherein the heavy ions are As ions.
7. The trench power device of claim 1, further comprising:
and a first metal barrier layer and a second metal barrier layer formed between the electrode contact hole and the metal plug, wherein the first metal barrier layer is in contact with an inner wall of the contact hole, and the second metal barrier layer is in contact with the metal plug.
8. The trench power device of claim 7,
the first metal barrier layer is made of Ti;
the second metal barrier layer is made of TiN;
the material of the metal plug is W.
9. The trench power device of claim 1,
the groove type power device is an MOSFET, wherein a first electrode layer between the metal plug and the groove is a source electrode, and a second electrode layer is a drain electrode; or
The trench type power device is an IGBT, wherein a first electrode layer between the metal plug and the trench is an emitter, and a second electrode layer is a collector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123057017.5U CN216389378U (en) | 2021-12-07 | 2021-12-07 | Groove type power device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123057017.5U CN216389378U (en) | 2021-12-07 | 2021-12-07 | Groove type power device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216389378U true CN216389378U (en) | 2022-04-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123057017.5U Active CN216389378U (en) | 2021-12-07 | 2021-12-07 | Groove type power device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216389378U (en) |
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2021
- 2021-12-07 CN CN202123057017.5U patent/CN216389378U/en active Active
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