SUPERJUNCTION SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING SAME
20230142541 · 2023-05-11
Inventors
Cpc classification
H01L29/66545
ELECTRICITY
H01L29/0696
ELECTRICITY
H01L29/7889
ELECTRICITY
H01L29/1095
ELECTRICITY
H01L29/0634
ELECTRICITY
International classification
H01L29/08
ELECTRICITY
H01L29/66
ELECTRICITY
Abstract
Disclosed is a superjunction semiconductor device and a method for manufacturing the same and, more particularly, to a superjunction semiconductor device and a method for manufacturing the same seeking to improve a switching speed and thus to improve switching characteristics by reducing a gate-to-drain parasitic capacitance (Cgd) and/or configuring a gate electrode as a floating dummy gate.
Claims
1. A superjunction semiconductor device, comprising: a substrate; a drain electrode on the substrate; an epitaxial layer on the substrate; a plurality of pillar regions spaced apart from each other in the epitaxial layer; a gate electrode on the epitaxial layer; a dummy gate on the epitaxial layer; a body region in the epitaxial layer; and a source region in the body region, wherein the source region is adjacent to or under the gate electrode or a sidewall thereof, but is not adjacent to or under the dummy gate or a sidewall thereof.
2. The superjunction semiconductor device of claim 1, comprising a plurality of gate electrodes, wherein the dummy gate extends in a same direction as the gate electrode, and is between adjacent ones of the gate electrodes.
3. The superjunction semiconductor device of claim 1, comprising a plurality of gate electrodes and a plurality of dummy gates, wherein the dummy gates extend in a same direction as the gate electrodes, and alternate with the gate electrodes.
4. The superjunction semiconductor device of claim 1, further comprising a gate node, wherein the dummy gate is physically separate from the gate node.
5. The superjunction semiconductor device of claim 1, wherein the pillar regions are spaced apart from each other in a first direction, and the gate electrode and the dummy gate extend in the first direction, and are spaced apart from an adjacent gate electrode and/or an adjacent dummy gate in a second direction.
6. The superjunction semiconductor device of claim 1, wherein the plurality of pillar regions alternate with portions of the epitaxial layer at a predetermined height.
7. A superjunction semiconductor device, comprising: a substrate; a drain electrode on the substrate; an epitaxial layer having a second conductivity type on the substrate; a plurality of pillar regions spaced apart from each other in a first direction in the epitaxial layer, and alternating with portions of the epitaxial layer along the first direction at a predetermined height or depth; a plurality of gate electrodes extending in a second direction on the epitaxial layer, and spaced apart from adjacent ones of the gate electrodes in the first direction; a plurality of dummy gates extending in the second direction on the epitaxial layer, and spaced apart from the adjacent ones of the gate electrodes and/or adjacent ones of the dummy gates in the first direction; a body region having a first conductivity type in the epitaxial layer and on one of the pillar regions; and a source region having the second conductivity type in the body region.
8. The superjunction semiconductor device of claim 7, wherein the superjunction semiconductor device comprises a plurality of body regions and a plurality of source regions, and there is only one source region in each of the body regions.
9. The superjunction semiconductor device of claim 7, wherein each of the gate electrodes at least partially overlaps a corresponding one of the source regions in a vertical direction, and each of the dummy gates has a shorter length in the second direction than the gate electrodes.
10. The superjunction semiconductor device of claim 9, wherein each of the dummy gates does not overlap any of the source regions in the vertical direction.
11. The superjunction semiconductor device of claim 10, wherein the dummy gates correspond one-to-one with the gate electrodes.
12. A method for manufacturing a superjunction semiconductor device, the method comprising: forming a plurality of epitaxial layers on a substrate; forming an implant layer including an impurity region having a first conductivity type in one or more of the epitaxial layers; forming a pillar region in the one or more epitaxial layers by diffusion; forming a gate electrode on or over the epitaxial layers; and forming a dummy gate on or over the epitaxial layers, wherein the gate electrode and the dummy gate extend in a direction substantially orthogonal to the pillar region.
13. The method for manufacturing a superjunction semiconductor device of claim 12, further comprising: forming a body region in the epitaxial layers connected to the pillar region and overlapping the gate electrode and/or the dummy gate; and forming a source region in the body region so that the source region does not overlap the dummy gate.
14. The method for manufacturing a superjunction semiconductor device of claim 12, wherein the source region overlaps a sidewall of the gate electrode in a vertical direction.
15. The method for manufacturing a superjunction semiconductor device of claim 12, wherein the dummy gate has a substantially same cross-sectional shape as the gate electrode.
16. The method for manufacturing a superjunction semiconductor device of claim 12, further comprising forming a gate node on or over the substrate and/or the epitaxial layers, and the dummy gate is formed so that it is not connected to the gate node.
17. A method for manufacturing a superjunction semiconductor device, the method comprising: forming an epitaxial layer on a substrate; forming a plurality of pillar regions spaced apart from each other in a first direction in the epitaxial layer; forming, in the epitaxial layer, a body region having a first body portion and a second body portion on one of the pillar regions; forming a source region in the first body region; forming a gate electrode on the epitaxial layer adjacent to and/or over the first body portion; and forming a dummy gate on the epitaxial layer adjacent to and/or over the second body portion.
18. The method for manufacturing a superjunction semiconductor device of claim 17, wherein the source region is not formed in the second body portion.
19. The method for manufacturing a superjunction semiconductor device of claim 18, wherein the dummy gate is floating.
20. The method for manufacturing a superjunction semiconductor device of claim 19, wherein the source region extends in a second direction with the gate electrode, the dummy gate, and the pillar regions.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The above and other objectives, features, and other advantages of the present disclosure will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
[0039]
[0040]
[0041]
[0042]
[0043]
[0044]
[0045]
[0046]
DETAILED DESCRIPTION OF THE INVENTION
[0047] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. The embodiments of the present disclosure may be modified in various forms, and the scope of the present disclosure should not be construed as being limited to the following embodiments, but should be construed based on the matters described in the claims. In addition, these embodiments are provided for reference in order to more completely explain the present disclosure to those skilled in the art.
[0048] As used herein, the singular form may include the plural form unless the context clearly dictates otherwise. Furthermore, as used herein, “comprise” and/or “comprising” refer to the specific existence of the recited shapes, numbers, steps, actions, members, elements and/or groups thereof, and do not exclude the presence or addition of one or more other shapes, numbers, actions, members, elements and/or groups.
[0049] Hereinafter, it should be noted that when one component (or layer) is described as being on another component (or layer), one component may be directly on another component, or one or more other components or layers may be between the components. In addition, when one component is expressed as being directly on or above another component, no other component(s) are located between the one component and the other component. Moreover, being located on “top,” “upper,” “lower,” “above,” “below,” “bottom” or “one (first) side” or “a side” of a component means a relative positional relationship.
[0050] The terms first, second, third, etc. may be used to describe various items such as various components, regions and/or parts. However, the items are not limited by these terms.
[0051] In addition, it should be noted that, where certain embodiments are otherwise feasible, certain process sequences may be performed other than those described below. For example, two processes described in succession may be performed substantially simultaneously or in the reverse order.
[0052] The term “metal oxide semiconductor” or “MOS” used below is a general term, and “M” is not limited to only metal and may refer to any of various types of conductors. Also, “S” may refer to a substrate or a semiconductor structure, and “O” is not limited to oxide and may include various types of organic or inorganic insulator materials.
[0053] Moreover, the conductivity type of a doped region or other component(s) may be defined as “p-type” or “n-type” according to the main carrier characteristics, but this is only for convenience of description, and the technical spirit of the present disclosure is not limited to what is illustrated. For example, the more general terms “first conductivity type” or “second conductivity type” will be used herein. For example, “first conductivity type” may refer to p-type, and “second conductivity type” may refer to n-type.
[0054] Furthermore, it should be understood that “high concentration” and “low concentration” referring to the doping concentration of an impurity region may mean a doping concentration of one component relative to another component.
[0055] Hereinafter, the term “first direction” should be understood to mean an x-axis direction or a y-axis direction in the illustrated drawings, and the term “second direction” should be understood to mean a direction orthogonal to the first direction in a horizontal plane. Hereinafter, for convenience, the first direction may refer to the x-axis direction in the drawings, and the second direction may refer to as the y-axis direction in the drawings, but the scope of the present disclosure is not limited thereto.
[0056]
[0057] Hereinafter, a superjunction semiconductor device 1 according to an embodiment (first embodiment) of the present disclosure will be described in detail with reference to the accompanying drawings.
[0058] Referring to
[0059] The superjunction semiconductor device 1 according to the first embodiment of the present disclosure includes a cell region C (which may be an active region of the device 1) and a ring region R (that may be a termination or peripheral region surrounding the cell region C). It should be noted that the structure of the superjunction semiconductor device 1 according to the first embodiment of the present disclosure is in the cell region C.
[0060] The structure of the device 1 will be described. The device 1 includes a substrate 101. The substrate 101 may include a silicon substrate or a germanium substrate, and may include a bulk (monolithic or single crystal) wafer and/or an epitaxial layer. The substrate 101 may comprise, for example, a lightly or heavily doped substrate having the second conductivity type.
[0061] An epitaxial layer 110, which may comprise an impurity-doped layer having the second conductivity type, is on the substrate 101 in the cell region C and the ring region R. In addition, a plurality of pillar regions 120 are in the epitaxial layer 110. The pillar regions 120 each comprise an impurity-doped region having the first conductivity type, and may extend to a predetermined depth in the epitaxial layer 110. The pillar regions 120 may be spaced apart from each other. For example, the plurality of pillar regions 120 may be spaced apart from each other in the first direction. That is, portions of the epitaxial layer 110 having the second conductivity type and the pillar regions 120 having the first conductivity type may alternate along the first direction. The pillar regions 120 may be in both the cell region C and the ring region R, but are not limited thereto.
[0062] A drain electrode 130 is on the substrate 101, on a major surface of the substrate 101 opposite from the epitaxial layer 120. In addition, a gate insulating film 140 is on the epitaxial layer 120. A plurality of gate electrodes 150 and a plurality of dummy gates 160 (to be described later) may be on the gate insulating film 140. The gate insulating film 140 comprises a silicon oxide (e.g., undoped or thermal silicon dioxide) layer, a high-k layer, or a combination thereof, and may be formed by, for example, atomic layer deposition (ALD), chemical vapor deposition (CVD), or physical vapor deposition (PVD).
[0063] The gate electrodes 150 may extend along the first direction and may be spaced apart from an adjacent or nearest gate electrode 150 in the second direction. Accordingly, the gate electrodes 150 may repeatedly cross the (alternating) epitaxial layer 110 portions and pillar regions 120. That is, in the device 1 according to the first embodiment of the present disclosure, unlike the second embodiment to be described later, the individual gate electrodes 150 and the dummy gates 160 extend (e.g., have a length) at an angle of about 90° to the horizontal extension direction (e.g., length, as opposed to height or depth) of the pillar regions 120.
[0064] As such, when the plurality of gate electrodes 150 extend in a direction substantially perpendicular to the alternating epitaxial layer 110 portions and pillar regions 120, it is relatively easy to adjust the separation distance in the second direction between adjacent or nearest gate electrodes 150 compared to the existing structure or the structure of a device 2 according to the second embodiment. That is, even when the distance between the gate electrodes 150 in the second direction is relatively long, the structure of the device 1 itself does not change compared to the structure of the existing device. Therefore, it is possible to easily adjust the channel density by adjusting the separation distance between the gate electrodes 150.
[0065] As previously described, the dummy gate 160 also extends in the first direction and may be spaced apart from the adjacent gate electrode 150 and/or the nearest dummy gate 160 in the second direction. The dummy gate 160 is electrically and physically separate from a gate node N (in the ring or peripheral region R) to maintain a floating state. In addition, the gate electrodes 150 and/or other dummy gates 160 may be adjacent to and/or spaced apart from a specific one of the dummy gates 160 in the second direction. That is, the plurality of dummy gates 160 may have sides along the second direction, or may alternate with the gate electrodes 150. The total area ratio between the dummy gate and the gate electrode 150 is variable and there is no special limitation thereto.
[0066] A plurality of body regions 170, each of which is an impurity-doped region having the first conductivity type, are in the epitaxial layer 110 and optionally under the gate electrodes 150 and the dummy gates 160. The body regions 170 may contact the pillar regions 120 in a lateral direction. The body regions 170 may alternate with the pillar regions 120 in the first direction. A source region 172 that is a heavily doped region having a second conductivity type is in each of the body regions 170.
[0067] The source region 172 may partially overlap the corresponding gate electrode 150. In addition, one or two source regions 172 may be in each individual body region 170. For example, when two source regions 172 are in an individual body region 170, two current paths may be formed. A side or portion of the body region containing a source region 172 is referred to as a first body portion, and a side or portion of the body region not containing a source region 172 is referred to as a second body portion.
[0068] In general high-voltage and high-current power systems, when a short-circuit occurs, high voltage and high current may simultaneously pass through the device, resulting in high power consumption. If this phenomenon continues, the junction temperature rises, which may eventually destroy the device. When two source regions 172 are in the body region 170, a current value (Isc) during a short-circuit may be relatively large. To solve this problem, only one source region 172 may be in the body region 170 in order to reduce the area of the source region 172 and/or the number of channels in the device.
[0069] Hereinafter, the structure of a conventional superjunction semiconductor device 9 and its problems, as well as the structure of the superjunction semiconductor device 1 according to the embodiment of the present disclosure for solving those problems will be described with reference to the accompanying drawings.
[0070] Referring to
[0071] In order to solve such problems, referring to
[0072]
[0073] Hereinafter, a superjunction semiconductor device 2 according to another embodiment (second embodiment) of the present disclosure will be described in detail with reference to the accompanying drawings. In describing the second embodiment, a detailed description of the content similar to or overlapping with the first embodiment will be omitted.
[0074] Referring to
[0075] A drain electrode 230 is on the bottom surface of the substrate 201, opposite from the epitaxial layer 210. In addition, a gate insulating film 240 is on the epitaxial layer 210, and a plurality of gate electrodes 250 are on the gate insulating film 240. Both the gate insulating film 240 and the gate electrodes 250 may extend in the second direction and may be spaced apart from adjacent gate insulating films 240 and adjacent gate electrodes 250 in the first direction. In addition, at least one dummy gate 260 may be between any pair of adjacent or nearest gate electrodes 250. The gate insulating film 240 may also be between each dummy gate 260 and the epitaxial layer 210. As described above, in the second embodiment, different from the first embodiment, the gate insulating film 240, the gate electrode 250, and the dummy gate 260 all extend in the second direction, so that they do not cross the alternating epitaxial layer 210 portions and pillar regions 220, but rather, extend in the same direction as the pillar regions 220. The dummy gate 260 is floating (e.g., neither physically nor electrically connected to the gate node N), which is the same as in the first embodiment.
[0076] Furthermore, a plurality of body regions 270 (i.e., impurity-doped regions having the first conductivity type) are in the epitaxial layer 210 and optionally under the gate electrodes 250 and the dummy gate(s) 260 (or sidewall[s] thereof). The body regions 270 also extend in the second direction and are spaced apart from adjacent body region(s) 270 in the first direction. At least one source region 272 may be in each of the body regions 270. The source region 272 is not adjacent to or under the dummy gate 260 or a sidewall thereof, and is preferably closer or adjacent to and/or under a sidewall of the nearest gate electrode 250. The source region 272 may also extend in the second direction and be spaced apart from the nearest source region(s) 272 in the first direction.
[0077]
[0078] Hereinafter, a method for manufacturing a superjunction semiconductor device according to an embodiment (first embodiment) of the present disclosure will be described in detail with reference to the accompanying drawings.
[0079] Referring to
[0080] Thereafter, referring to
[0081] Thereafter, referring to
[0082] Thereafter, referring to
[0083] Finally, referring to
[0084]
[0085] Hereinafter, a method of manufacturing a superjunction semiconductor device according to another embodiment (second embodiment) of the present disclosure will be described in detail with reference to the accompanying drawings.
[0086] First, referring to
[0087] Thereafter, referring to
[0088] Thereafter, referring to
[0089] Thereafter, referring to
[0090] Thereafter, referring to
[0091] The above detailed description is illustrative of the present disclosure. In addition, the above description shows and describes various embodiments of the present disclosure, and the present disclosure can be used in various other combinations, modifications, and environments. That is, changes or modifications are possible within the scope of the concept of the disclosure herein, the scope equivalent to the written disclosure, and/or within the scope of skill or knowledge in the art. The above-described embodiments describe various ways for implementing the technical idea(s) of the present disclosure, and various changes for specific applications or fields of use of the present disclosure are possible. Accordingly, the detailed description of the present disclosure is not intended to limit the present disclosure to the disclosed embodiments.