CN111354780A - A super junction terminal with inversion implanted sidewalls and method of making the same - Google Patents

Abstract

A super junction terminal with inversion injection and a fabrication method thereof are disclosed. The super junction terminal formed by the sidewall implantation includes an epitaxial column, an inversion implanted sidewall and a trench, and the epitaxial column and the trench are doped semiconductor regions formed by epitaxial growth on the substrate, and formed by etching, The inversion implanted sidewalls are formed by ion implantation on the sidewalls of the trenches, the trenches and the epitaxial pillar regions are arranged alternately, and are located between two adjacent epitaxial pillar regions. The super junction terminal with inversion injection can make the edge electric field distribution of the active region relatively uniform when the device blocks the voltage, thereby improving the withstand voltage of the edge region and giving full play to the withstand voltage capability of the active region.

Description

A super junction terminal with inversion implanted sidewalls and method of making the same

technical field

The present invention relates to a semiconductor device, in particular to a super junction terminal with inversion implanted sidewalls and a fabrication method thereof.

Background technique

In recent years, more and more attention has been paid to energy conservation and emission reduction in the world, which puts forward higher requirements for loss control and efficiency improvement of large power electronic equipment. As an important part of power electronic equipment, semiconductor power devices have received extensive attention in the industry.

Breakdown voltage is an important indicator of semiconductor power devices, indicating the maximum voltage that the device can withstand. The active area of the power device can obtain a breakdown voltage of several thousand volts through reasonable design, so it is suitable for higher power applications. However, the active region is not infinitely extended. At the edge of the active region, that is, the terminal of the semiconductor power device, if there is no reasonable design, the realization of the withstand voltage of the active region will be greatly limited. In order to form a terminal with the highest possible withstand voltage in the smallest area possible, various types of design solutions have been proposed in the industry. These include trench termination, tilt termination, junction termination, field limiting ring termination, composite floating junction termination, spatial modulation junction termination and many other types.

The existing terminal technology can achieve a large breakdown voltage, but because the electric field distribution in the terminal area is not uniform enough when blocking large voltages, the maximum withstand voltage of the active area design cannot be maximized, and the required terminal area is relatively large. big.

SUMMARY OF THE INVENTION

In order to solve the problems raised in the background art, this patent proposes a super junction terminal with inversion implanted sidewalls and a fabrication method thereof.

According to an embodiment of the present invention, a super junction terminal with inversion implanted sidewalls, the super junction terminal is located at an edge of an active region, including: a substrate; a plurality of epitaxial pillar regions located above the substrate, and is located around the active region and surrounds the active region, each epitaxial column region includes an epitaxial column and an inversion implanted sidewall, and the inversion implanted sidewall is located on the sidewall of the epitaxial column ; and a plurality of trenches alternately arranged with the plurality of epitaxial pillar regions, each trench being located between two adjacent epitaxial pillar regions.

According to an embodiment of the present invention, a method for fabricating a super junction terminal with inversion implanted sidewalls, wherein the superjunction terminal with inversion implanted sidewalls is located at the edge of an active region, the fabricating method includes: on a substrate growing an epitaxial layer on top; etching a plurality of epitaxial pillars on the epitaxial layer by using a mask, the plurality of epitaxial pillars are located around the active region and enclose the active region; and in each Ion implantation is performed on one or both sidewalls of the epitaxial pillars to form inverse implantation sidewalls; a trench is formed between two adjacent epitaxial pillars, and the trenches and the epitaxial pillars are alternately arranged.

A super junction terminal with an inversion injection sidewall and a manufacturing method thereof proposed by the present invention, based on the super junction principle, can form a terminal with the highest possible withstand voltage in the smallest area possible, and can be widely used in semiconductor power devices , set the doping type of the inversion implant sidewall to be opposite to the doping type of the epitaxial column to achieve alternately distributed P-type and N-type doping regions, form charge balance, and make the electric field distribution more uniform, so that the same size and epitaxial doping can be achieved. In the case of miscellaneous conditions, it can withstand higher voltages.

Description of drawings

FIG. 1 is a three-dimensional perspective view of a super junction terminal with inversion implanted sidewalls according to an embodiment of the present invention;

2 is a three-dimensional perspective view of a super junction terminal with an inversion injection sidewall in a certain direction of a PN diode according to an embodiment of the present invention;

3 is a three-dimensional perspective view of a super junction terminal with inversion implanted sidewalls of a super junction Schottky diode parallel to a pillar region direction according to an embodiment of the present invention;

4 is a three-dimensional perspective view of a super junction terminal with inversion implanted sidewalls of a super junction Schottky diode perpendicular to the direction of the epitaxial pillar region according to an embodiment of the present invention.

Detailed ways

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments described herein are only used for illustration and are not used to limit the present invention. In the following description, numerous specific details are set forth in order to facilitate a thorough understanding of the present invention. However, one of ordinary skill in the art will understand that these specific details are not required to practice the present invention. Furthermore, in some embodiments, well-known circuits, materials, or methods have not been described in detail in order to avoid obscuring the present invention.

Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in the present invention in at least one embodiment. Thus, appearances of the phrases "in one embodiment," "in an embodiment," "one example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures or characteristics may be combined in any suitable combination and/or subcombination in one or more embodiments or examples. Furthermore, those of ordinary skill in the art will appreciate that the figures provided herein are for illustrative purposes, wherein like reference numerals refer to like elements. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. "Left", "right", "inner", "outer", "front", "rear", "upper", "lower", "top", "bottom", "outer", "left", "right", "inside", "outside", "front", "rear", "upper", "lower" "Above," "under," or similar descriptions are for illustrative purposes only, and are not used to describe fixed relative positions. It is to be understood that the above terms are interchangeable under appropriate circumstances so that corresponding embodiments may function properly in other orientations. In addition, "contact" appearing in the specification or claims may be direct contact or indirect contact, such as contact through wire connection.

Super junction technology is a technology that uses alternately arranged N-type and P-type doping regions to make adjacent regions compensate each other and achieve charge balance, thereby approximating the charge distribution of zero doping, which can be expressed in various types; Impurity diffusion, repeated epitaxial growth and ion implantation, etc.

FIG. 1 is a three-dimensional perspective view of a super junction terminal with inversion implanted sidewalls according to an embodiment of the present invention. The super junction terminal with inversion implanted sidewalls includes: a substrate 6; an epitaxial pillar region 4 located above the substrate 6, including an epitaxial pillar 2 and an inversion implanted sidewall 3, and the epitaxial pillar 2 is located at the top of the substrate 6. Around the active area 1, its extending direction is perpendicular to the edge 7 of the active area 1, surrounding the active area 1, and may or may not be in contact with the active area 1, wherein the active area 1 is the power In the area where the main function is realized in the device, the inversion implanted sidewalls 3 are located on both sides or sidewalls of the epitaxial pillar 2; the trenches 5 are arranged alternately with the epitaxial pillar region 4 and are located in two adjacent between the epitaxial pillar regions 4 .

In one embodiment, the doping type of the inversion implant sidewall 3 is opposite to that of the epitaxial pillar 2 . In one embodiment, the inversion implanted sidewalls 3 are formed by ion implantation on the sidewalls of the epitaxial pillars 2 . In one embodiment, the width refers to the dimension parallel to the edge of the active region, the width of the epitaxial pillar region 2 is less than 10 μm, and the width of the trench 5 is less than 10 μm, because the larger epitaxial pillar region 4 and trench The groove width 5 cannot realize the mutual depletion of the N-type region and the P-type region charge or can deplete each other, but the electric field at the junction of the epitaxial column 2 and the inversion sidewall 3 is too large, which reduces the withstand voltage. In one embodiment, the thickness of the epitaxial column region 4 is greater than 1 μm, because the smaller thickness of the epitaxial column region 4 cannot well modulate the electric field in the region below it, resulting in a drop in withstand voltage.

In one embodiment, the actual manufacturing process includes:

The first step is to grow a semiconductor epitaxial layer on the N-type semiconductor substrate, and its doping is still N-type doping, and the doping concentration is 1×10 ¹⁵ cm ^-3 -1×10 ¹⁷ cm ^-3 , and then pass through A series of processes form the active area;

In the second step, the active area is protected, and strip-shaped trenches are etched in the terminal area by dry etching at a certain distance, the distance is less than 10 μm, and the etching depth is greater than 5 μm.

In the third step, P-type impurities are implanted on the sidewall of the trench by ion implantation on the inclined sidewall, the doping concentration is 1×10 ¹⁵ cm ^-3 -1×10 ¹⁹ cm ^-3 , the implantation depth is less than 3 μm, and the implantation is controlled. The amount makes the total amount of impurities in the P-type impurity and N-type epitaxial pillar regions approximately the same, forming a charge balance.

The super junction terminal with inversion implanted sidewalls thus formed, through the alternately arranged N-type and P-type doped regions, that is, the alternately arranged inversion implanted sidewalls 3 and epitaxial pillars 2, makes the device block when the voltage is , the charges in the adjacent epitaxial column 2 and the inversion injection sidewall 3 compensate each other to achieve charge balance, thereby approaching the charge distribution of zero doping, which can make the electric field distribution of the terminal very uniform, that is, the electric field strength at each point of the terminal The magnitude difference is smaller, resulting in a larger breakdown voltage in a smaller area. Note that the N-type and P-type doping described in this embodiment can be interchanged, and similar effects can also be produced.

FIG. 2 is a three-dimensional perspective view of a super junction terminal with an inversion injection sidewall in a certain direction of a PN diode according to an embodiment of the present invention. The super junction terminal with inversion implanted sidewalls includes: a substrate 6; an active region 1 including a P-type implanted region 8 and an N-type drift region 9; an epitaxial column region 4 located above the substrate 6, It includes an epitaxial pillar 2 and an inversion implanted sidewall 3. The epitaxial pillar 2 is located around the active region 1, and its extension direction is perpendicular to the edge 7 of the active region 1, and surrounds the active region 1. The active area 1 is in contact or not, wherein the active area 1 is the area in the power device that realizes the main function, and the inversion implanted sidewalls 3 are located on both sides or sidewalls of the epitaxial pillar 2 ; The trenches 5 are arranged alternately with the epitaxial column regions 4 and are located between two adjacent epitaxial column regions 4 .

In one embodiment, the P-type implanted region 8 and the N-type drift region 9 are in contact with each other to form the active region 1 together, and form the PN junction of the PN diode. In one embodiment, the doping type of the inversion implant sidewall 3 is opposite to that of the epitaxial pillar 2 . In one embodiment, the inversion implanted sidewalls 3 are formed by ion implantation on the sidewalls of the epitaxial pillars 2 . In one embodiment, the epitaxial pillar 2 is perpendicular to the active region 1 . In one embodiment, the width refers to the dimension parallel to the edge of the active region, the width of the epitaxial pillar region 2 is less than 10 μm, and the width of the trench 5 is less than 10 μm, because the larger epitaxial pillar region 4 and trench The groove width 5 cannot realize the mutual depletion of the N-type region and the P-type region charge or can deplete each other, but the electric field at the junction of the epitaxial column 2 and the inversion sidewall 3 is too large, which reduces the withstand voltage. In one embodiment, the thickness of the epitaxial column region 4 is greater than 1 μm, because the smaller thickness of the epitaxial column region 4 cannot well modulate the electric field in the region below it, resulting in a drop in withstand voltage. In one embodiment, the P-type implanted region 8 is a P-type doped region formed by P-type ion implantation after epitaxially growing a semiconductor region with N-type doping on the substrate 6 . In one embodiment, the top of epitaxial pillar region 4 is lower than the top of active region 1 in order to isolate the termination region from the top of active region 1 .

In one embodiment, the actual manufacturing process includes:

The first step is to grow a semiconductor epitaxial layer on the N-type semiconductor substrate, and its doping is still N-type doping, and the doping concentration is 1×10 ¹⁵ cm ^-3 -1×10 ¹⁷ cm ^-3 , and then pass through Ion implantation forms a P-type implantation region, and the doping concentration is greater than 1×10 ¹⁷ cm ^-3 ;

The second step is to protect the active area, use dry etching to etch away the P-type implanted area in the terminal area, and then etch strip-shaped trenches at a certain distance, the distance is less than 10μm, and the etching depth is greater than 5μm.

In the third step, P-type impurities are implanted on the sidewall of the trench by ion implantation on the inclined sidewall, the doping concentration is 1×10 ¹⁵ cm ^-3 -1×10 ¹⁹ cm ^-3 , the implantation depth is less than 3 μm, and the implantation is controlled. The amount makes the total amount of impurities in the P-type impurity and N-type epitaxial pillar regions approximately the same, forming a charge balance.

A PN diode with this super junction terminal with inverse injection sidewalls in all four directions on the surface, when a positive voltage is applied to the cathode and the anode is grounded, a uniform electric field distribution can be obtained in the terminal area, so that in a smaller area A larger breakdown voltage is achieved, so that the breakdown voltage of the terminal is greater than that of the active region. Note that the N-type and P-type doping described in this embodiment can be interchanged, and similar effects can also be produced.

3 is a three-dimensional perspective view of a super junction terminal with inversion implanted sidewalls of a super junction Schottky diode parallel to the direction of the pillar region according to an embodiment of the present invention. The super junction terminal formed by the sidewall implantation includes: a substrate 6 ; Active region epitaxial pillars 10 and active region trenches 11, arranged alternately to form a super junction structure in the active region; Epitaxial pillar region 4, located above the substrate 6, including epitaxial pillars 2 and inversion implanted sidewalls 3. The epitaxial pillar 2 is located around the active region 1, and its extension direction is perpendicular to the edge 7 of the active region 1, parallel to the extension direction of the active region epitaxial pillar 10, and surrounds the active region 1 It can be in contact with or not in contact with the active region 1 , wherein the active region 1 is the region in the power device that realizes the main function, and the inversion implanted sidewalls 3 are located on both sides or one side of the epitaxial pillar 2 The trenches 5 are arranged alternately with the epitaxial column regions 4 and are located between two adjacent epitaxial column regions 4 .

4 is a three-dimensional perspective view of a super junction terminal with inversion implanted sidewalls of a super junction Schottky diode perpendicular to the direction of the epitaxial pillar region according to an embodiment of the present invention. The super junction terminal formed by the sidewall implantation includes: substrate 6; active region epitaxial pillars 10 and active region trenches 11, which are arranged alternately to form a super junction structure of the active region; epitaxial pillar region 4, located in the Above the substrate 6, including epitaxial pillars 2 and inversion implanted sidewalls 3, the epitaxial pillars 2 are located around the active region 1, and its extension direction is perpendicular to the edge 7 of the active region 1 and perpendicular to the active region 1. The extension direction of the active region epitaxial pillar 8 surrounds the active region 1 and may or may not be in contact with the active region 1, wherein the active region 1 is the region in the power device that realizes the main function, and the inversion implantation The sidewalls 3 are located on two sides or one sidewall of the epitaxial pillar 2 ; the trenches 5 are arranged alternately with the epitaxial pillar regions 4 and are located between two adjacent epitaxial pillar regions 4 .

Referring to FIGS. 3 and 4 , in one embodiment, the sidewalls of the active region epitaxial pillars 10 are provided with an inversion injection layer 12 , so as to form a super junction structure in the active region. In one embodiment, the doping type of the inversion implant sidewall 3 is opposite to that of the epitaxial pillar 2 . In one embodiment, the inversion implanted sidewalls 3 are formed by ion implantation on the sidewalls of the epitaxial pillars 2 . In one embodiment, the epitaxial pillar 2 is perpendicular to the active region 1 . In one embodiment, the width refers to the dimension parallel to the edge of the active region, the width of the epitaxial pillar region 2 is less than 10 μm, and the width of the trench 5 is less than 10 μm, because the larger epitaxial pillar region 4 and trench The groove width 5 cannot realize the mutual depletion of the N-type region and the P-type region charge or can deplete each other, but the electric field at the junction of the epitaxial column 2 and the inversion sidewall 3 is too large, which reduces the withstand voltage. In one embodiment, the thickness of the epitaxial column region 4 is greater than 1 μm, because the smaller thickness of the epitaxial column region 4 cannot well modulate the electric field in the region below it, resulting in a drop in withstand voltage. In one embodiment, the top of epitaxial pillar region 4 is lower than the top of active region 1 in order to isolate the termination region from the top of active region 1 .

In one embodiment, the actual manufacturing process includes:

In the first step, a semiconductor epitaxial layer is grown on the N-type semiconductor substrate, and its doping is still N-type doping, and the doping concentration is 1×10 ¹⁵ cm ^-3 -1×10 ¹⁷ cm ^-3 ;

The second step is to protect the active area, and use dry etching to etch away the P-type implanted area in the terminal area;

The third step is to remove the protective material in the active area, and draw the active area super junction stripes and terminal super junction stripe patterns on the surface of the epitaxial layer by photolithography as shown in Figure 3 and Figure 4. The stripe spacing is less than 10μm, and the etching depth is greater than 5μm.

In the third step, through two inclined sidewall ion implantation, P-type impurities are implanted into the sidewalls of the active region trench and the terminal trench, and the doping concentration is 1×10 ¹⁵ cm ^-3 -1×10 ¹⁹ cm ^{- 3.} The implantation depth is less than 3 μm, and the implantation amount is controlled so that the total amount of impurities in the P-type impurity and N-type epitaxial pillar regions is approximately the same to form a charge balance.

The resulting super junction Schottky diodes are super junction terminals with inversion sidewalls around the active region. When a positive voltage is applied to the cathode and the anode is grounded, a uniform electric field distribution can be obtained in the terminal region. Thus, a larger breakdown voltage is achieved in a smaller area, so that the breakdown voltage of the terminal is greater than that of the active region. Note that the N-type and P-type doping described in this embodiment can be interchanged, and similar effects can also be produced.

While the present invention has been described with reference to several exemplary embodiments, it is to be understood that the terms used are of description and illustration, and not of limitation. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it is to be understood that the above-described embodiments are not limited to any of the foregoing details, but are to be construed broadly within the spirit and scope defined by the appended claims Therefore, all changes and modifications that come within the scope of the claims or their equivalents should be covered by the appended claims.

Claims (11)

1. A super junction termination with inversion implanted sidewalls, the super junction termination at an edge of an active region, comprising:

a substrate;

the epitaxial column regions are positioned above the substrate and around the active region to surround the active region, each epitaxial column region comprises an epitaxial column and an inversion injection side wall, the inversion injection side wall is positioned on the side wall of the epitaxial column, and the doping type of the inversion injection side wall is opposite to that of the epitaxial column; and

and a plurality of trenches alternately arranged with the plurality of epitaxial pillar regions, each trench being located between two adjacent epitaxial pillar regions.

2. The super-junction termination of claim 1 wherein the inversion implant sidewalls are formed by ion implantation at sidewalls of the epitaxial pillar.

3. The super junction termination of claim 1, wherein an extension direction of the epitaxial pillar of the super junction termination is perpendicular to an edge of the active region.

4. The super-junction termination of claim 1 wherein the active region comprises an active region epitaxial pillar, the extension direction of the epitaxial pillar of the super-junction termination being parallel or perpendicular to the extension direction of the active region epitaxial pillar.

5. The super-junction termination of claim 4 wherein sidewalls of the active region epitaxial pillar comprise an inversion implant layer, the inversion implant layer being of the same doping type as the inversion implant sidewalls of the super-junction termination.

6. The super junction termination of claim 1, wherein a top of the epitaxial pillar region is lower than a top of the active region.

7. The super-junction termination of claim 1 wherein the width of the epitaxial pillar is less than 10 μ ι η, the width of the trench is less than 10 μ ι η, and the thickness of the epitaxial pillar is greater than 1 μ ι η.

8. A method of fabricating a super junction termination with inversion implantation sidewalls at the edge of an active region, the method comprising:

growing an epitaxial layer on a substrate;

etching a plurality of epitaxial columns on the epitaxial layer by using a mask, etching the epitaxial columns to the substrate or etching the epitaxial columns to a distance above the substrate, wherein the plurality of epitaxial columns are positioned around the active region and surround the active region; and

performing ion implantation on one or two side walls of each epitaxial column to form inversion implantation side walls, wherein the doping type of the inversion implantation side walls is opposite to that of the epitaxial columns; wherein

And a groove is formed between two adjacent epitaxial columns and is alternately arranged with the epitaxial columns.

9. The method of claim 8, wherein the extension direction of the epitaxial pillar of the super junction termination is perpendicular to the edge of the active region.

10. The method of manufacturing of claim 8, further comprising:

drawing patterns of active region super junction stripes and terminal super junction stripes on the surface of the epitaxial layer through photoetching;

forming an active region groove; and

and injecting P-type impurities into the side walls of the active region groove and the terminal groove by two times of inclined side wall ion injection.

11. The method of manufacturing of claim 8, further comprising: the total amount of impurities in the implanted sidewall and the total amount of impurities in the epitaxial column are controlled to be approximately the same.

Images