Abstract: The present invention relates to a seed crystal assembly for growing a single crystal boule in a physical vapor transport, PVT, process. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. A seed crystal assembly comprises a base structure which is connectable to a crucible, the base structure having a base diameter across a central axis of the seed crystal assembly and base height along the central axis, and a single crystal seed crystal which is designed for growing the single crystal boule on a growth surface. The single crystal seed crystal is attached to the base structure, the seed crystal having a seed crystal diameter across the central axis and a seed crystal height along the central axis, wherein a specific heat conductivity of the base structure differs by less than or equal to 25% from a specific heat conductivity of the seed crystal at a growth temperature between 2000° C. and 2600° C.

Abstract: The present invention relates to a chamfered silicon carbide substrate which is essentially monocrystalline, and to a corresponding method of chamfering a silicon carbide substrate. A silicon carbide substrate according to the invention comprises a main surface (102), wherein an orientation of said main surface (102) is such that a normal vector ({right arrow over (O)}) of the main surface (102) includes a tilt angle with a normal vector ({right arrow over (N)}) of a basal lattice plane (106) of the substrate, and a chamfered peripheral region (110), wherein a surface of the chamfered peripheral region includes a bevel angle with said main surface, wherein said bevel angle is chosen so that, in more than 75% of the peripheral region, normal vectors ({right arrow over (F)}_i) of the chamfered peripheral region (110) differ from the normal vector of the basal lattice plane by less than a difference between the normal vector of the main surface and the normal vector of the basal lattice plane of the substrate.

Abstract: The present invention relates to a silicon carbide (SiC) substrate with improved mechanical and electrical characteristics. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. The silicon carbide substrate comprises an inner region (102) which constitutes at least 30% of a total surface area of said substrate (100), a ring shaped peripheral region (104) radially surrounding the inner region (102), wherein a mean concentration of a dopant in the inner region (102) differs by at least 1·1018 cm?3 from the mean concentration of this dopant in the peripheral region (104).

Abstract: The present disclosure relates to a layered seed for growing a volume mono crystal by gas phase growth in a direction of growth (Y) in a crucible. The layered seed comprises a monocrystalline growing layer with a growing surface for growing the volume mono crystal and an opposing heat spreader facing surface for coupling the growing layer to a heat spreader layer. The layered seed further comprises the heat spreader layer with a growing layer facing surface for coupling to the heat spreader facing surface and an opposing mounting surface for mounting the heat spreader layer to the crucible, wherein the heat spreader layer comprises a polycrystalline material having thermally coupled grains that are piled in the direction of growth (Y), the piled grains for equalizing hot spots of the crucible thermally coupled to the mounting surface.

Abstract: The present invention provides a multilayer seed which is designed such as to offer a virtually unstressed surface onto which a single-crystal can grow without the negative impact of the internal stress carried by monocrystalline seeds, in particular at the high temperatures conventionally used in sublimation processes. The multilayer seed for growing a single-crystal comprise at least two seed layers, wherein each of the at least two seed layers is a monocrystalline layer characterized by one or more parameters associated with a respective degree of internal stress. The one or more parameters are selected such that the at least two seed layers are adapted to counter-act the respective internal stresses from each other.

Abstract: The present disclosure relates to a layered substrate for growing an epitaxial layer in a direction of growth (Y) in a reactor. The layered substrate comprises a monocrystalline growing layer with a growing surface for growing the epitaxial layer and an opposing heat spreader facing surface for coupling the growing layer to a heat spreader substrate. The layered substrate further comprises the heat spreader substrate with a growing layer facing surface for coupling to the heat spreader facing surface and an opposing mounting surface for mounting the heat spreader substrate to the reactor, wherein the heat spreader substrate comprises a polycrystalline material having thermally coupled grains that are piled in the direction of growth (Y), the piled grains for equalizing hot spots of the reactor thermally coupled to the mounting surface.

Abstract: A bulk SiC single crystal is produced by sublimation growth. A stress measurement to detect initial internal mechanical seed stresses is carried out on a wafer-shaped single crystalline SiC seed crystal. The seed crystal is classified, according to the stress measurement, into a first class when the initial seed stresses are below a first stress boundary value, into a second class when the initial seed stresses lie between the first stress boundary value and a second stress boundary value, and into a third class when the initial seed stresses exceed the second stress boundary value. The actual sublimation growth for growing the bulk SiC single crystal is carried out with the SiC seed crystal only when it has been classified into the first or second class, and when it is classified into the second class, at least one stress-reducing measure is carried out.

Abstract: A seed unit for growing a bulk SiC single crystal has a wafer-like single crystalline SiC seed crystal with a growth surface arranged on a wafer front side for growing the bulk SiC single crystal to be grown. The SiC seed crystal has a crystal longitudinal mid-axis extending in an axial direction. A radial direction is oriented perpendicular to the axial direction. The seed unit also has a rear side layer component arranged on a wafer rear side of the SiC seed crystal, the structure of which changes starting from the crystal longitudinal mid-axis in the radial direction, and so a radial temperature gradient is adjusted during the growth of the bulk SiC single crystal within the SiC seed crystal.

Abstract: The present invention relates to a crucible with a cavity for growing a SiC volume mono crystal by sublimation growth in a direction of growth (Y). The crucible comprises an end wall (110) with a seed holder (112) for holding a SiC seed crystal in the cavity, the end wall (110) extending in a direction (r) perpendicular to the direction of growth (Y); a side wall (140) extending in the direction of growth (Y), the side wall (140) preventing permeation of a doping gas from an external into the cavity, the doping gas for doping the SiC volume mono crystal during the sublimation growth; and a diffusion region (114) allowing permeation of the doping gas from the external in the cavity, wherein the diffusion region (114) is located between the seed holder (112) and an edge (142) of the side wall (140).

Abstract: An arrangement for growing a SiC volume monocrystal in a cavity (110) by sublimation growth in the direction of growth (Y) includes a susceptor (100) for absorbing electromagnetic energy and heating the cavity (110). An insulator (200) surrounds the susceptor (100) to thermally insulate it from the exterior. The insulator (200) features a thermal insulation wall (202) that reduces radial heat transfer (r) from the susceptor (100). A thermally conductive layer (210) is positioned between the susceptor (100) and the thermal insulation wall (202) to distribute heat and minimize or reduce thermal conduction to the insulator (200), enhancing the insulator's reflectivity and reducing waviness.

Abstract: The present invention relates to a silicon carbide substrate for use as a crystal seed, comprising a monocrystalline silicon carbide disk covered with a protective oxide layer. The protective oxide layer is intended to be removed to expose an ideal, clean surface of the monocrystalline silicon carbide disk. The present invention also relates to a method of producing at least one bulk silicon carbide single-crystal by sublimation growth using the silicon carbide substrate with protective oxide layer as a seed crystal. The protective oxide layer is removed from the seed crystal surface to expose the underlying monocrystalline silicon carbide disk by a back-etching process performed in-situ in the crystal growth crucible, i.e. after the seed crystal is arranged inside the growth crucible and before the sublimation deposition on the growth surface starts.

Abstract: Thermal post-treatment of a silicon carbide (SiC) volume monocrystal which has a substantially cylindrical basic shape with a crystal length in an axial direction, a crystal diameter in a radial direction, a crystal central longitudinal axis extending in the axial direction, and with three boundary surfaces, namely, a bottom surface, a top surface and a circumferential edge surface. The SiC volume monocrystal is brought to a post-treatment temperature in order to reduce mechanical stresses present in the SiC volume monocrystal after completion of the previous growth, wherein an inhomogeneous temperature profile with a radial thermal gradient is set in the SiC volume monocrystal, which rises continuously from the crystal central longitudinal axis to the circumferential edge surface, and a heat exchange of the SiC volume monocrystal with a surrounding free space takes place via free heat radiation on at least two of the three boundary surfaces.

Abstract: The present invention relates to systems and methods for growing bulk semiconductor single crystals, and more specifically, for growing bulk semiconductor single crystals, such as silicon carbide, based on physical vapor transport. The sublimation system comprises a crucible (202) having a longitudinal axis (212) and a sidewall (218) extending along the longitudinal axis (212), wherein the crucible (202) comprises a fixing means for at least one seed crystal (210) and at least one source material compartment (204) for containing a source material (208); and a heating system for generating a temperature field around a circumference of the crucible (202) along the longitudinal axis (212) of the crucible (202); a thermally insulating unit (214) arranged within the source material compartment (204) at the sidewall (218) of the crucible (202).

Abstract: The present invention relates to systems and methods for growing bulk semiconductor single crystals, and more specifically, for growing bulk semiconductor single crystals, such as silicon carbide, based on physical vapor transport. The sublimation system comprises a crucible (102) having a longitudinal axis (120) and a sidewall (116) extending along the longitudinal axis (120), wherein the crucible comprises a fixing means for at least one seed crystal (110) and at least one source material compartment (104) for containing a source material (108), and a heating system being formed to generate a temperature field around a circumference of the crucible along the longitudinal axis of the crucible, wherein the crucible (102) comprises at least one first heat radiation cavity (118), which is arranged opposite to the fixing means and adjacent to the source material compartment (104), the first heat radiation cavity (118) being closed on all of its sides.

Abstract: The present invention relates to systems and methods for growing bulk semiconductor single crystals, and more specifically, for growing a bulk semiconductor single crystals, such as silicon carbide, based on physical vapor transport. A sublimation system for growing at least one single crystal of a semiconductor material by means of a sublimation growing process comprises a crucible (102) having a longitudinal axis (120) and comprising a fixing means for at least one seed crystal (110) and at least one source material compartment (104) for containing a source material (108); a heating system being formed to generate an irregular temperature field around a circumference of the crucible at one or more defined heights along the longitudinal axis of the crucible; a rotary drive that is operable to cause a rotational movement of the fixing means around the longitudinal axis relative to the heating system.

Abstract: The present invention relates to systems and methods for growing bulk semiconductor single crystals, and more specifically, for growing a bulk semiconductor single crystals, such as silicon carbide, based on physical vapor transport. A sublimation system for growing at least one single crystal of a semiconductor material by means of a sublimation growing process comprises a crucible (102) having a longitudinal axis (120) and comprising a fixing means for at least one seed crystal (110) and at least one source material compartment (104) for containing a source material (108); a heating system being formed to generate an irregular temperature field around a circumference of the crucible (102) and/or along the longitudinal axis of the crucible (102); a thermal insulation unit (117) at least partly surrounding the crucible (102), wherein the thermal insulation unit (117) has a radially and/or axially asymmetric form to compensate the irregular temperature field.

Abstract: An SiC volume monocrystal is processed by sublimation growth. An SiC seed crystal is placed in a crystal growth region of a growing crucible and SiC source material is introduced into an SiC storage region. During growth, at a growth temperature of up to 2,400° C. and a growth pressure between 0.1 mbar and 100 mbar, an SiC growth gas phase is generated by sublimation of the SiC source material and by transport of the sublimated gaseous components into the crystal growth region, where an SiC volume monocrystal grows by deposition from the SiC growth gas phase on the SiC seed crystal. A mechanical stress is introduced into the SiC seed crystal at room temperature prior to the start of the growth to cause seed screw dislocations present in the SiC seed crystal to undergo a dislocation movement so that seed screw dislocations recombine.

Abstract: A SiC volume monocrystal is produced by sublimation growth. An SiC seed crystal is placed in a crystal growth region of a growing crucible and SiC source material is introduced into an SiC storage region. During growth, at a growth temperature of up to 2,400° C. and a growth pressure between 0.1 mbar and 100 mbar, an SiC growth gas phase is generated by sublimation of the SiC source material and by transport of the sublimated gaseous components into the crystal growth region, where an SiC volume monocrystal grows by deposition from the SiC growth gas phase on the SiC seed crystal. Prior to the start of growth, the SiC seed crystal is examined at the growth surface for the presence of seed screw dislocations, nucleation centers are generated, wherein the nucleation centers are starting points for at least one compensation screw dislocation during the growth carried out subsequently.

Abstract: The present invention relates to a silicon carbide (SiC) substrate with improved mechanical and electrical characteristics. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. The silicon carbide substrate comprises an inner region (102) which constitutes at least 30% of a total surface area of said substrate (100), a ring shaped peripheral region (104) radially surrounding the inner region (102), wherein a mean concentration of a dopant in the inner region (102) differs by at maximum 5·1018 cm?3, preferably 1·1018 cm?3, from the mean concentration of this dopant in the peripheral region (104).

Abstract: The present invention relates to a silicon carbide (SiC) substrate with improved mechanical and electrical characteristics. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. The silicon carbide substrate comprises an inner region (102) which constitutes at least 30% of a total surface area of said substrate (100), a ring shaped peripheral region (104) radially surrounding the inner region (102), wherein a mean concentration of a dopant in the inner region (102) differs by at least 1·1018 cm?3 from the mean concentration of this dopant in the peripheral region (104).