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DE-102019114312-B4 - SILICON CARBIDE DEVICE WITH COMPENSATION AREA AND MANUFACTURING METHOD

DE102019114312B4DE 102019114312 B4DE102019114312 B4DE 102019114312B4DE-102019114312-B4

Abstract

Method for manufacturing a silicon carbide device, comprising: a provision of a silicon carbide substrate (700) comprising a drift layer (730) of a first conductivity type and a trench (770) extending from a main surface (701) of the silicon carbide substrate (700) into the drift layer (730), wherein a polytype of the silicon carbide substrate (700) is 4H, 6H or 2H; an implantation of first dopants through a first trench side wall (771) of the trench (770), wherein the first dopants have a second conductivity type and are implanted into the silicon carbide substrate (700) at a first implantation angle (γ1), wherein channeling occurs at the first implantation angle (γ1), and wherein the first dopants form a first compensation layer (181) of a compensation structure (180) having vertical pn junctions, and wherein the first compensation layer (181) extends parallel to the first trench side wall (771), and further comprising: a formation of a fill structure (170) in the trench (770), a formation of an epitaxial layer (780) on the main surface (701), a further trench (785) forming in the epitaxial layer (780), the further trench (785) exposing the fill structure (170), and an implantation of further first dopants through a further first side wall (781) of the further trench (785) to form a compensation layer extension (181d) of the first compensation layer (181) in the epitaxial layer (780).

Inventors

  • Hans-Joachim Schulze
  • Moriz Jelinek
  • Werner Schustereder
  • Romain Esteve
  • Caspar Leendertz

Assignees

  • INFINEON TECHNOLOGIES AG

Dates

Publication Date
20260513
Application Date
20190528

Claims (19)

  1. Method for producing a silicon carbide device, comprising: providing a silicon carbide substrate (700) having a drift layer (730) of a first conductivity type and a trench (770) extending from a main surface (701) of the silicon carbide substrate (700) into the drift layer (730), wherein a polytype of the silicon carbide substrate (700) is 4H, 6H or 2H; an implantation of first dopants through a first trench side wall (771) of the trench (770), wherein the first dopants have a second conductivity type and are implanted into the silicon carbide substrate (700) at a first implantation angle (γ1), wherein channeling occurs at the first implantation angle (γ1), and wherein the first dopants form a first compensation layer (181) of a compensation structure (180) having vertical pn junctions, and wherein the first compensation layer (181) extends parallel to the first trench side wall (771), and further comprising: the formation of a filling structure (170) in the trench (770), forming an epitaxial layer (780) on the main surface (701), forming a further trench (785) in the epitaxial layer (780), wherein the further trench (785) exposes the filling structure (170), and implanting further first dopants through a further first side wall (781) of the further trench (785) to form a compensation layer extension (181d) of the first compensation layer (181) in the epitaxial layer (780).
  2. A method according to the preceding claim, further comprising: implanting a second dopant through the first trench side wall (771), wherein the second dopants have the first conductivity type and form a second compensation layer (182b) and wherein the first and the second compensation layers (181, 182b) form a pn junction.
  3. Method according to the preceding claim, wherein the second dopants are implanted under a second implantation angle (γ2) under which channeling occurs in the silicon carbide substrate (700).
  4. A method for producing a silicon carbide device, comprising: providing a silicon carbide substrate (700) having a drift layer (730) of a first conductivity type and a trench (770) extending from a main surface (701) of the silicon carbide substrate (700) into the drift layer (730); implanting first dopants through a first trench side wall (771) of the trench (770) at a first implantation angle (γ1), wherein the first dopants have a second conductivity type and form a first compensation layer (181) extending parallel to the first trench side wall (771); and an implantation of second dopants through the first trench sidewall (771) at a second implantation angle (γ2), wherein the second dopants have the first conductivity type and form a second compensation layer (182b), wherein channeling occurs in the silicon carbide substrate (700) at the second implantation angle (γ2), wherein the first and second compensation layers (181, 182b) form a pn junction, and wherein the first compensation layer (181) is arranged between the first trench sidewall (771) and the second compensation layer (182b), and further comprising: a formation of a filling structure (170) in the trench (770), a formation of an epitaxial layer (780) on the main surface (701), a formation of a further trench (785) in the epitaxial layer (780), wherein the further trench (785) exposes the filling structure (170), and an implantation of further first dopants through a further first side wall (781) of the further trench (785) to form a compensation layer extension (181d) of the first compensation layer (181) in the epitaxial layer (780).
  5. Method according to the preceding claim, wherein channeling occurs in the silicon carbide substrate (700) at the first implantation angle (γ1).
  6. A method according to any of the preceding claims, further comprising: implanting further first dopants through a second trench side wall (772), wherein the second trench side wall (772) is opposite the first trench side wall (771) and wherein the further first dopants form a further first compensation layer (181) parallel to the second trench side wall (772).
  7. Method according to the preceding claim, further comprising: an implantation of further second dopants through the second trench side wall (772), wherein the further second dopants form a further second compensation layer (181) parallel to the second trench side wall (772).
  8. Method according to one of the two preceding claims, wherein the further first and/or the further second dopants are implanted at an implantation angle at which channeling occurs in the silicon carbide substrate (700).
  9. A method according to any of the preceding claims, further comprising: implanting third dopants of the second conductivity type through the first trench side wall (771) at an implantation angle at which channeling occurs in the silicon carbide substrate (700), wherein the third dopants form a third compensation layer (181b) on a side of the second compensation layer (182) facing away from the trench (770).
  10. Method according to one of the preceding claims, further comprising: forming a filling structure (170) in the trench (770) and forming a gate electrode (155) between the main surface (701) and the filling structure (170).
  11. Method according to any of the preceding claims: wherein the first dopants or the first dopants and the second dopants are also implanted through the main surface (701) and form horizontal areas of the first compensation layer (181) or horizontal areas of the first and second compensation layers (181, 182b) on the main surface (701), wherein after forming the first compensation layer (181) or after forming the first and second compensation layers (181, 182b) a sacrificial layer (790) is removed from the main surface (701) of the silicon carbide substrate (700), wherein the sacrificial layer (790) contains the horizontal areas.
  12. Procedure according to one of the Claims 1 until 8 , further comprising: forming, prior to forming the first compensation layer (181) or the first and second compensation layers (181, 182b), an implantation mask (430) on the main surface (701), wherein an opening (435) in the implantation mask (430) exposes the trench (770).
  13. A method according to one of the preceding claims, further comprising: implanting fourth dopants of the second conductivity type through a bottom of the trench (770), wherein the implanted dopants form a first supplementary compensation area (281).
  14. Silicon carbide device comprising: a silicon carbide body (100); a gate structure (150) extending from a first surface (101) into the silicon carbide body (100); a filling structure (170) formed between the gate structure (150) and a second surface (102) of the silicon carbide body (100), the second surface (102) being opposite the first surface (101); a compensation region (182) of a first conductivity type, the compensation region (182) being formed in the silicon carbide body (100) between the gate structure (150) and the second surface (102); a first compensation layer (181) of a second conductivity type, wherein the first compensation layer (181) is formed between a first side wall (171) of the filling structure (170) and the compensation area (182), and a second compensation layer (182a) of the first conductivity type, wherein the second compensation layer (182a) extends parallel to the first side wall (171) and wherein the first compensation layer (181) and the second compensation layer (182a) form a pn junction; and a shielding region (160) of the second conductivity type, wherein at least one area of the shielding region (160) is formed between the gate structure (150) and the second surface (102), wherein the shielding region (160) is in contact with at least one section of a gate bottom surface (157) of the gate structure (150) and with the first compensation layer (181).
  15. Silicon carbide device according to the preceding claim, wherein a maximum dopant concentration in the first compensation layer (181) is at least 10 16 cm -3 .
  16. Silicon carbide device according to one of the two preceding claims, further comprising: a further first compensation layer (181) of the second conductivity type, wherein the further first compensation layer (181) extends along a second side wall (172) of the filling structure (170).
  17. Silicon carbide device according to one of the three preceding claims, further comprising: a first supplementary compensation area (281) of the second conductivity type between the filling structure (170) and the second surface (102), wherein the first supplementary compensation area (281) is in contact with the filling structure (170) and with the first compensation layer (181).
  18. Silicon carbide device according to one of the four preceding claims, wherein a horizontal longitudinal axis of the gate structure (150) is inclined to a horizontal longitudinal axis of the filling structure (170).
  19. Silicon carbide device according to one of the five preceding claims, wherein the filling structure (170) contains a dielectric material.

Description

TECHNICAL AREA Examples of the present disclosure relate to a silicon carbide device, in particular a silicon carbide device with a compensation structure, and to methods for manufacturing silicon carbide devices with a compensation structure. BACKGROUND The most significant difference between conventional power semiconductor devices and superjunction power semiconductor devices is a series of lateral junctions between n-doped and p-doped regions in the voltage-holding layer of the superjunction power semiconductor device. Exemplary disclosures concerning superjunction power semiconductor devices and their properties are found in the publications. DE 10 2017 131 274 B3 , US 2019 / 0 088 482 A1 US 2015 / 0 028 350 A1 , US 9 070 580 B2 , US 2017 / 0 338 302 A1 , DE 10 2014 106 094 A1 , COSTA, ARG: Lattice sites of ion-implanted Mn, Fe and Ni in 6H-SiC. In: Semiconductor science and technology, Vol. 33, 2018, No. 1, Article no. 015021, pp. 1-10 US 2016 / 0 380 117 A1 , DE 10 2016 104 256 B3 This is well known. A lateral depletion effect within the voltage-holding layer enables high voltage-blocking capability with a comparatively low one-state or on-resistance. A prerequisite for high voltage-blocking capability is sufficient charge balance between the n-doped and p-doped regions in the voltage-holding layer. The fabrication of silicon superjunction devices typically involves a multi-epitaxy/multi-implantation process with masked p-type doping or doping with both a masked p-type and a masked n-type per layer, a multi-implantation process at different implantation energies, or a trench etching process combined with epitaxial growth in the trench, or with a gas-phase doping process of the trench wall. Forming compensation structures with sufficiently well-defined charge compensation becomes more challenging if the diffusion coefficient of the semiconductor material is low. There is a need to provide a silicon carbide device that incorporates a compensation structure with well-defined charge compensation at competitive costs. SUMMARY The invention is defined in the independent claims. Further developments are the subject of the dependent claims. An example of the present disclosure relates to a method for fabricating a silicon carbide device. The method comprises providing a silicon carbide substrate containing a drift layer of a first conductivity type and a trench extending from a major surface of the silicon carbide substrate into the drift layer. First dopants are implanted through a first trench sidewall. The first dopants have a second conductivity type and are implanted into the silicon carbide substrate at a first implantation angle, whereby channeling or a lattice-guiding effect occurs at the first implantation angle. The first dopants form a first compensation layer extending parallel to the first trench sidewall. Another example in the present disclosure relates to a method for fabricating a silicon carbide device. The method comprises providing a silicon carbide substrate containing a drift layer of a first conductivity type and a trench extending from a major surface of the silicon carbide substrate into the drift layer. First dopants are implanted through a first trench sidewall. The first dopants have a second conductivity type and form a first compensation layer extending parallel to the first trench sidewall. Second dopants are implanted through the first trench sidewall. The second dopants have the first conductivity type and form a second compensation layer. The first and second compensation layers form a pn junction. Another example from the present disclosure relates to a silicon carbide device containing a silicon carbide body. A gate structure extends from a first surface into the silicon carbide body. A filling structure is formed between the gate structure and a second surface of the silicon carbide body, the second surface being opposite to the first surface. A compensation region of a first conductivity type is formed between the gate structure and the second surface. A first compensation layer of a second conductivity type is formed between a first sidewall of the filling structure and the compensation region. A second compensation layer of the first conductivity type extends parallel to the first sidewall. and the second compensation layer forms a pn junction. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are enclosed to provide a further understanding of the embodiments and are incorporated into and form part of this patent description. The drawings illustrate embodiments of a silicon carbide device and a method for manufacturing a silicon carbide device and, together with the description, serve to explain the principles of the embodiments. Further embodiments are described in detail in the following description and claims. 1A - 1C simplified vertical cross-sectional views of an area of a silicon carbide substrate are shown to illustrate a method for forming a silicon c