SiCp-type and low resistivity crystals, boules, wafers, and devices, and methods for making same

Abstract

Doped SiOC liquid starting material provides p-type polymer-derived ceramic SiC crystal materials, including boules and wafers; p-type SiC electronic devices; low resistivity SiC crystals, wafers, and boules with phosphorus as a dopant; polymer-derived ceramic doped SiC molded charge raw material for deposition growth of doped SiC crystals.

Description

[Technical field]

[0001] This application claims priority to and the benefit under 35 U.S.C. § 119(e)(1) of U.S. Provisional Application No. 63 / 220,132, filed July 9, 2021, and U.S. Provisional Application No. 63 / 337,088, filed April 30, 2022, the entire disclosures of each of which are incorporated herein by reference.

[0002] The present invention relates to p-type SiC crystals, ingots, boules, and wafers, low resistivity SiC crystals, ingots, boules, and wafers, methods of making p-type SiC crystals, ingots, boules, and wafers, methods of making low resistivity SiC crystals, ingots, boules, and wafers, devices made from and uses of these wafers. [Background technology]

[0003] Pure silicon carbide (SiC) crystals are electrically neutral, with a balance of positive and negative charges in the crystalline material. Impurities are typically added to SiC crystals during growth to create a charge imbalance in the crystal and affect the electrical conductivity of SiC, making them useful for the manufacture of semiconductor diodes and transistors. Impurity atoms that add a positive charge to SiC are called donor atoms. Donor atoms are typically identified by the column to the right of the column containing Si and C in the periodic table (e.g., column 15, VA). Typical donor atoms in SiC are nitrogen (N) and phosphorus (P). Impurity atoms that add a negative charge to SiC are called acceptor atoms. Typically, acceptor atoms are identified by the column to the left of the column containing Si and C in the periodic table (e.g., 13 or IIIA). Typical acceptor atoms in SiC are boron (B) and aluminum (Al). SiC crystals typically contain impurities that are both donor and acceptor atoms. In order for a donor or acceptor impurity atom to affect the net charge in the crystal and become electrically active (i.e. affect the conductivity / resistivity of the crystal), the impurity atom must usually substitute for either a Si or C atom in their position in the crystal, in which case the impurity atom is called a substitutional impurity. The impurity atom may also be located between a Si atom and a C atom. In this case the impurity atom is called an interstitial impurity and may not affect the net charge in the crystal or may have a small effect on the charge and in some circumstances may not affect the net charge in the crystal. Thus, the terms "electrically active atomic impurities", "electrically active impurities", and "electrically active" are used to describe atoms added to a material, e.g., a SiC crystal material, including substitutional and interstitial atoms that affect the net charge of the crystal. Thus, all substitutional impurities are electrically active impurities, but interstitial impurities can be either electrically active or electrically inactive impurities. As a result, the atomic concentration of donor or acceptor impurities (the number of impurity atoms relative to the total number of atoms in the crystal) can be equal to or greater than the atomic concentration of electrically active impurities, such as substitutional impurity atoms.If there are more electrically active, e.g., substitutional donor atoms than there are electrically active, e.g., substitutional acceptor atoms, the SiC crystal is n-type, n standing for negative, i.e., there is an excess of negative charge. Conversely, if there are more electrically active, e.g., substitutional acceptor atoms than there are donor atoms, the SiC crystal is p-type, p standing for positive, i.e., there is an excess of positive charge in the SiC crystal.

[0004] Prior to the present invention, it has not been possible to industrially produce and commercially make p-type SiC substrates greater than 100 mm in diameter for use in the manufacture of SiC semiconductor devices. It is believed that prior attempts to produce p-type SiC crystals have failed to provide a manufacturable process for producing high quality, low defect p-type SiC material, e.g., SiC crystals, SiC boules, and p-type SiC wafers cut from these boules. Thus, prior to the present invention, the benefits of SiC semiconductor devices having p-type SiC material have been largely unavailable and commercially unavailable.

[0005] In this specification, unless otherwise noted, there are two types of charge carriers in semiconductor materials: holes and electrons. Holes can be considered the "opposite" of electrons. Unlike electrons, which have a negative charge, holes have a positive charge of the opposite polarity to but equal to the charge of an electron. Holes can sometimes be confusing because they are not physical particles like electrons, but are the absence of an electron in an atom. Holes can move from atom to atom when an electron leaves its position in a semiconductor. To use an analogy, think of people standing in a line on a staircase. When the first person in the line moves up a step, they make a hole. When everyone else moves up a step, the vacant step (hole) moves down a step. Holes are formed when an atom's electron moves from the valence band (the outermost electron shell, usually completely filled with electrons) to the conduction band (the region in the atom where electrons can easily escape) and are ubiquitous in semiconductors.

[0006] As used herein, unless otherwise specified, the terms "p-type," "p-type wafer," "p-type crystal," "p-type boule," and similar such terms are intended to be given the broadest possible meaning and include SiC crystal materials having more electrically active acceptor atom impurities, e.g., substitutional acceptor atom impurities, than electrically active donor atom impurities, e.g., substitutional donor impurity atoms. Thus, for example, a SiC crystal material having a net amount of electrically active acceptor atoms per unit volume of 1×10 10 / cm 3 ~1×10 22 / cm 3 , about 1×10 18 / cm 3 ~1×10 20 / cm 3 , about 1×10 18 / cm 3 ~1×10 23 / cm 3 , about 1×10 18 / cm 3 ~1×10 23 / cm 3 , about 1×10 18 / cm 3 ~Approx. 1×10 24 / cm 3 , about 1×10 9 / cm 3 Larger, about 1 x 10 15 / cm 3 Larger, about 1 x 10 18 / cm 3 Larger, about 1 x 10 19 / cm 3 The larger SiC crystal material is characterized as p-type SiC crystal material.

[0007] Additionally, unless otherwise specified, to be considered a p-type SiC crystal material, the Net Carrier concentration will have an excess of acceptor atom impurities, as given by equation (1).

[0008] (1) Nc = N D -N A

[0009] where Nc is the net carrier concentration. N D is the concentration of electrically active donor impurity atoms. N A is the concentration of electrically active acceptor impurity atoms. By convention, Nc is negative for p-type materials, indicating a deficiency of electrons.

[0010] As used herein, unless otherwise specified, the terms "p-type device," "p-type semiconductor," and similar such terms are to be given the broadest possible meaning and include any semiconductor, microelectronic device, or electronic device having a p-type layer or based on a p-type wafer, chip, or substrate.

[0011] As used herein, unless otherwise specified, "p + ", "p + "p-type," and similar such terms, refer to p-type crystalline SiC material, e.g., p-type boules, wafers, etc., that have a high amount of dopant, e.g., highly doped (N D >10 18 / cm 3 ), and therefore has low resistivity (<0.03 Ω cm). + The mold material is 10 18 / cm 3 ~about 10 20 / cm 3 N A , 10 18 / cm 3 ~about 10 21 / cm 3 N A , 10 19 / cm 3 Less than N A , about 1×10 18 / cm 3 ~1×10 23 / cm 3 , about 1×10 18 / cm 3 ~1×10 24 / cm 3 , and about 10 20 / cm 3 N ATypically, p + The resistivity of the mold material can be 0.03 Ω·cm or less, less than about 0.025 Ω·cm, less than about 0.020 Ω·cm, less than about 0.015 Ω·cm, between about 0.030 Ω·cm and about 0.01 Ω·cm, between about 0.025 Ω·cm and about 0.008 Ω·cm, or between about 0.020 Ω·cm and about 0.005 Ω·cm.

[0012] As used herein, unless otherwise specified, "p - ", "p-type," and similar such terms refer to p-type crystalline material, e.g., p-type boules, wafers, etc., that has a low amount of dopant, e.g., lightly doped (N D <10 18 / cm 3 ), and therefore has a high resistivity. Typically, these resistivities are 0.03 Ω cm or higher. Thus, p-type materials have a resistivity of 10 18 / cm 3 About 10 10 / cm 3 and smaller value of N A Typically, the resistivity of p-type materials ranges from 0.03 Ω cm to 10 8 Ω·cm and above.

[0013] As used herein, unless otherwise specified, the terms "n-type," "n-type wafer," "n-type crystal," "n-type boule," and similar such terms are to be given their broadest possible meaning and include SiC crystal material having a negative charge, electrically active donor atom, e.g., a higher impurity of substitutional donor atoms than other types of impurity atoms. Thus, for example, a SiC crystal material having a net amount of electrically active donor atoms per unit volume of 1×10 10 / cm 3 ~1×10 22 / cm 3 , about 1×10 18 / cm 3 ~1×10 20 / cm 3 , about 1×10 9 / cm 3 Larger, about 1 x 10 15 / cm3 Larger, about 1 x 10 18 / cm 3 Larger, about 1 x 10 19 / cm 3 The larger SiC crystal material is characterized as n-type SiC crystal material.

[0014] Furthermore, unless otherwise stated, to be considered an n-type SiC crystal material, the net carrier concentration indicates an excess of donor atom impurities as given by the formula: By convention, in n-type materials, Nc is positive, signifying an excess of electrons.

[0015] The term “n + ", "n + "N-type" and similar such terms refer to a semiconductor having a high amount of dopant, e.g., a highly doped (N A >10 18 / cm 3 ), and therefore refers to n-type materials that have low resistivity (<0.03 Ω cm), e.g., n-type boules, wafers, etc. Typically, these resistivities can be 0.03 Ω cm or less.

[0016] The term “n - ", "n - "N-type" and similar such terms refer to a material having a low amount of dopant, e.g., lightly doped (N A <10 18 / cm 3 ), and thus refers to n-type materials that have high resistivity, e.g., n-type boules, wafers, etc. Typically, these resistivities are greater than 0.03 Ω cm, and generally greater than 0.03 Ω cm.

[0017] As used herein, unless otherwise indicated, the terms "physical hole," "physical void," and "physical cavity" refer to a physical property, not an electrical property, and are used in their common and ordinary manner to refer to a void in a solid body or surface, an absence of material in a structure or surface, or an empty space within a surface or solid.

[0018] As used herein, unless otherwise specified, "vapor deposition" ("VD"), "vapor deposition technique", "vapor deposition process" and similar such terms are given their broadest meaning and include, for example, processes in which a solid or liquid starting material is converted to a gaseous or vaporous state and the gas or vapor is then deposited to form, e.g., grow, a solid material. Vapor deposition techniques as used herein include growth by epitaxy, where a layer is provided from a gaseous or vaporous phase. Vapor deposition techniques are further classified as follows: chemical vapor deposition ("CVD"), physical vapor deposition ("PVD"), plasma CVD, physical vapor deposition ("PVT"), etc. Examples of vapor deposition apparatus include hot-wall chemical vapor deposition reactors, multi-wafer chemical vapor deposition reactors, chemical vapor deposition chimney reactors, etc. Physical vapor deposition (PVT) refers to and requires the use of at least one solid starting material that is sublimated to provide the vapor (e.g., flux) required for the growth of the crystal.

[0019] As used herein, unless otherwise indicated, the term "vaporization temperature" is given its broadest possible meaning and includes the temperature at which a material transitions from a liquid to a gaseous state, the temperature at which a material transitions from a solid to a gaseous state, or both (e.g., the transition from solid to liquid to gas occurs over a very small temperature range, e.g., below about 20° C., below about 10° C., and below about 5° C.). Unless otherwise indicated, the vaporization temperature will be the temperature corresponding to the particular pressure at which such transition occurs, e.g., 1 atmosphere, 0.5 atmosphere, etc. When discussing the vaporization temperature of a material used in a particular application, method, or particular apparatus, such as a PVT apparatus, the vaporization temperature is at the pressure used or typically used in that application, method, or apparatus, unless expressly stated otherwise.

[0020] Silicon carbide generally does not have a liquid phase and does not become liquid under typical PVT process conditions, instead sublimating under vacuum at temperatures of about 1700°C or higher. (Note that at very high pressures, SiC can exist in the liquid phase.) Typically, in industrial and commercial applications, conditions are set such that sublimation occurs at temperatures of about 2,500°C or higher. As silicon carbide sublimes, a vapor flux is formed that is generally composed of various species of silicon and carbon, the composition of the vapor flux being a function of the raw materials as well as the temperature and pressure. However, the present invention provides the ability to control the ratio of these components through the use of raw materials (e.g., shaped charges) in addition to the selection of liquid starting raw materials (e.g., polysilocarb precursors), and the temperature and pressure during the PVT process.

[0021] As used herein, unless otherwise specified, the terms "crystal," "ingot," "boule," and similar such terms are to be given the broadest possible meaning and refer to a crystalline structure having a diameter of about 50 mm to about 250 mm, a diameter greater than 100 mm, a diameter greater than 250 mm, and typically a diameter of about 150 mm, and a height (i.e., distance from seed end to tail end) of about 25 mm to about 250 mm, a height of about 75 mm to about 150 mm, a height of 75 mm or more, a height of about 100 mm or more, a height of about 150 mm, and typically a height of about 100 mm to about 150 mm. The term "crystal" generally refers to a structure that is first grown and then removed from the growth apparatus. The term "ingot" generally refers to a crystal that has been processed, e.g., flattened, at one or both of its ends. The term "boule" generally refers to an ingot that has been further processed, e.g., a flattened portion formed on the boule and is ready for wafer processing (i.e., production of wafers from the boule). Typically, the crystals are grown by a deposition process using deposition equipment, specifically PVT equipment and processes.

[0022] As used herein, the terms crystal, ingot, and boule are generally interchangeable with each other, unless expressly stated otherwise or clear from the context, and detailed descriptions herein of the properties, crystal structure, macrodefects, microdefects, and composition of one of them are applicable to the other.

[0023] As used herein, unless otherwise specified, "wafer," "SiC wafer," "p-type SiC wafer," "n-type SiC wafer," and similar such terms refer to a crystalline material that is a structure cut from a larger structure of the same crystalline material (e.g., a p-type SiC wafer is cut from a p-type SiC boule). Typically, a wafer 700 is a disk-like structure, which can be circular and / or semicircular in shape 705, and can have one flat or multiple flats. A wafer has a top or upper surface, a bottom or lower surface, and a thickness. The outer edge of a wafer can be tapered, beveled, chamfered, square, circular, etc.

[0024] Typically, SiC wafers are formed by cutting wafers generally transverse to the c-axis (growth axis) of a large crystal (e.g., boule). Typically, the wafers can be on the growth axis (i.e., on-axis) or a few degrees off this axis (i.e., off-axis), typically about 0.1 degrees to about 5 degrees off the growth axis for off-axis wafers. The wafers can have a thickness of about 80 μm to about 600 μm and a diameter of about 50 mm to about 250 mm, but preferably have a diameter of about 150 mm. When cut on-axis or slightly off-axis, SiC wafers typically have a carbon or carbon surface and a silicon or silicon surface. Wafers can be cut along the growth axis or at any other orientation relative to the growth axis.

[0025] Generally, before the development of commercial SiC MOSFETs, silicon (Si) IGBTs were mainly used in the power industry (above 500V). These are bipolar devices and can handle high currents (Amperes) and power (Watts or W) due to low conduction losses. However, their high power losses during the turn-off phase (the transition between conduction and cut-off) limit their operating frequency. The operating frequency is important because the higher the frequency, the smaller the passive elements (e.g. inductors) in the converter / inverter can be, helping to reduce the volume and weight of the device. Reducing the volume, weight, and both of these devices (MOSFETs and IGBTs) is a long-standing challenge in the field and a key metric for end users. MOSFETs are unipolar devices, which means they have lower switching losses (especially at turn-off). However, their on-resistance (conduction losses) is high and increases with voltage, so IGBTs are preferred at high voltages (above 500V for Si). Thus, the art has presented a long-standing and unsolved paradigm of optimizing (ie, minimizing) both the conduction and transition losses in semiconductor devices.

[0026] Additionally, the transition from silicon-based devices to SiC-based devices has faced substantial and long-standing problems. In particular, the transition from p-type silicon devices to SiC-based devices (e.g., n-type in these early prior attempts) is difficult, requiring significant expense, time, and effort to redesign the p-type silicon devices (e.g., circuitry, masks, configurations, etc.) to use n-type SiC. The failure of prior art to provide high quality p-type SiC wafers has left this long-standing problem and need unsolved.

[0027] The history of power electronics devices and circuits begins with semiconductor devices made from silicon.

[0028] Many designs of power electronic devices employ p-channel field effect transistors and / or n-channel field effect transistors, the most common of which is the MOSFET (metal-oxide-semiconductor field effect transistor). In this specification, unless otherwise noted, a p-channel MOSFET is a type of MOSFET in which the channel of the MOSFET is composed of a majority of holes as current carriers. When a MOSFET is activated and in the on-state, most of the current flowing is holes moving through the channel. Another type of MOSFET is the n-channel MOSFET, in which the majority of the current carriers are electrons. N-channel or p-channel MOSFETs can be made in two ways: enhancement type MOSFETs and depletion type MOSFETs.

[0029] A depletion-type MOSFET is normally on (full current flows from source to drain) when there is no voltage difference between the gate and source terminals. However, when a voltage is applied to the gate lead, the drain-source channel becomes more resistive and the transistor shuts off completely until the gate voltage becomes very high. An enhancement-type MOSFET is the opposite: when the gate-source voltage is 0V (VGS=0), it is normally off. However, when a voltage is applied to the gate lead, the drain-source channel becomes less resistive.

[0030] A typical application for power devices is the design and manufacture of power circuits such as inverters, converters and power supplies. These circuits are designed using n-channel or p-channel MOSFETs, or both. An example where both types are needed is an H-bridge power drive circuit, whose function is to drive current in either direction through a load (i.e. to drive a DC motor, such as the motors in electric automated guided vehicles and all-electric vehicles, in either forward or reverse direction).

[0031] To increase the energy efficiency of modern power management circuits, designers are now employing silicon carbide MOSFETs based on 4H-SiC crystalline substrates. Silicon carbide MOSFETs offer the opportunity to design circuits that operate at higher voltages and higher frequencies than circuits using silicon MOSFETs. Using SiC MOSFETs, the power circuits mentioned above can typically operate at voltages from 600V to over 10kV and amperages from 5A to over 200A.

[0032] Currently, SiC MOSFETs can only be manufactured on n-type SiC substrates because p-type SiC substrates are not commercially available. Therefore, most SiC MOSFETs are manufactured as n-channel devices. Since only SiC MOSFETs using n-type substrates were commercially available, SiC MOSFETs could not be widely deployed in power circuits.

[0033] There has long been a need to make n-channel IGBTs, a type of MOSFET transistor, commercially viable because they can achieve lower on-resistance and / or higher blocking voltage than p-channel IGBTs. Furthermore, n-channel devices, which have a positive voltage polarity and are similar to conventional power MOSFETs, may be more attractive from a systems perspective. To date, such devices have been fabricated using p-type SiC material formed as an epitaxial layer on an n-type SiC substrate, which is then polished away to remove the substrate. Such devices have been unsatisfactory due in part to the difficulty of removing the substrate. The present invention provides, among other things, the ability to provide such SiC IGBT devices that are easy to fabricate and commercially acceptable.

[0034] There has been a long-standing need for SiC LDMOSFETs (Lateral Diffused Metal Oxide Semiconductor Field Effect Transistors). These devices have been developed in silicon for high power applications such as cellular and UHF broadcast transmission, and their number is growing exponentially. This is because Si LDMOSFETs offer higher gain and better linearity than bipolar devices. However, prior to this invention, this design could not be realized in SiC because only n-type SiC substrates existed, and historically any p-type epitaxially molded SiC substrates had too high a resistivity compared to silicon, leading to undesirable LDMOSFET device performance.

[0035] In general, power MOSFETs tend to perform better when fabricated on n-channel than p-channel. However, to achieve even better performance, such devices typically need to be epitaxially grown on low-resistivity p-type substrates. However, currently commercially available p-type 4H-SiC substrates have relatively high resistivity (~2.5 Ω·cm), which is about two orders of magnitude higher than the resistivity of n-type substrates. This advantage of n-channel SiC devices has long been sought but has not been realized due to the high resistivity found in prior p-type substrates. The p-type wafer of the present invention achieves low resistivity that solves this long-standing need, enabling n-channel SiC devices with improved performance compared to devices fabricated on n-type SiC substrates.

[0036] As used herein, unless otherwise specified, the term "specific gravity", also called "apparent density", should be given the broadest possible meaning and generally refers to the mass per unit volume of a structure, e.g., a volumetric shape of a material. This property also includes the internal porosity of the particle as a fraction of the volume. This property can be measured, among others, using a low viscosity fluid that wets the particle surface.

[0037] As used herein, unless otherwise specified, the term "actual density" (sometimes referred to as "true density") should be used in the broadest possible sense and generally refers to the mass per unit volume of a material when no voids are present in the material. This measurement and property is one that substantially (i.e., below levels detectable by standard measurement techniques) excludes internal voids in the material, e.g., does not include voids in the material.

[0038] As used herein, unless otherwise noted, "room temperature" is 25° C. and "standard ambient temperature and pressure" is 25° C. and 1 atmosphere pressure. Unless expressly stated otherwise, all tests, test results, physical properties, and temperature and / or pressure dependencies, including viscosity, are given at standard ambient temperature and pressure.

[0039] In general, as used herein, the term "about" and the symbol "~" are meant to encompass a variation or range of ±10%, and the greater of the experimental or instrumental error associated with obtaining the stated value, unless otherwise specified.

[0040] In this specification, unless otherwise specified, the terms %, weight %, and mass % are used interchangeably and refer to, for example, the percentage of the weight of a first component relative to the total weight of a composition, mixture, preform, material, structure, or product. X / Y or XY indicates the weight % of X and the weight % of Y in a composition, unless otherwise specified. X / Y / Z or XYZ indicates the weight % of X, the weight % of Y, and the weight % of Z in a composition, unless otherwise specified.

[0041] As used herein, unless otherwise specified, "volume %" and "% volume" and similar such terms refer to the volume of a first component as a percentage of the overall volume of, for example, a composition, mixture, preform, material, structure, or article.

[0042] As used herein, unless expressly stated otherwise, the term "raw material" used in the context of boule growth, deposition apparatus, epitaxy, crystal growth and deposition processes should be given the broadest possible definition and refers to powdered SiC material, SiC volume shapes (e.g., shaped charges), or other forms of solid SiC material that are placed in a growth chamber or placed in a crystal growth, epitaxy, or SiC deposition apparatus to form a flux.

[0043] Terms such as "purity," "purity level," "impurity," "contaminant," and the like, as used herein, should be viewed in context and generally relate to undesirable materials that were not intentionally added to the SiC material or polymer resulting from the process of producing the SiC crystal. These terms do not include dopants (e.g., impurity atoms, atomic impurities, substitutional impurities, interstitial impurities, electrically active impurities, and similar terms) or other elements or materials that are intentionally added to or incorporated into the SiC crystal to provide or affect the charge, semiconducting properties, or other properties and characteristics of the SiC crystal. These terms do not include starting materials, polysilocarb precursors, hardening materials, first ceramic materials, raw materials, and materials that are intentionally incorporated into or combined with one or more of these to impart characteristics to the SiC crystal, particularly the SiC wafer. The amount of dopant is considered (i.e., counted) as part of the SiOC or SiC material when making purity and purity level determinations. Thus, as defined and used herein, dopants or doping materials are not "impurities." In this manner, a doped (e.g., with atomic impurities) SiOC material or a doped (e.g., with atomic impurities) SiC material, for example, having only dopants and Si, O and C, or only dopants and Si and C, can be 100% pure.

[0044] As used herein, unless expressly stated otherwise, "existing materials," "conventional materials," "current materials," "currently available materials," "existing deposition equipment," "current deposition equipment," and similar such terms refer to raw materials and equipment that exist or existed prior to the present invention. Use of the terms is not to be taken as, and does not constitute, an admission of prior art. It is merely intended to describe the current state of the art as a baseline or reference point against which significant and revolutionary improvements of embodiments of the present invention can be evaluated, contrasted, and measured.

[0045] This "Background" section is intended to introduce various aspects of art that may be related to embodiments of the present invention. As such, the preceding discussion in this section is intended to provide a framework for better understanding the present invention, and is not intended to be construed as admissions of prior art. Summary of the Invention [Problem to be solved by the invention]

[0046] There is a long-standing and ever-increasing need for high temperature, high volume, high performance semiconductor devices, power devices, and electronics. Silicon carbide (SiC) wafers provide a substrate that is preferred for these applications and meets the required performance characteristics, e.g., high temperature, power, bandgap, etc. However, prior to the present invention, p-type SiC crystals, p-type SiC ingots, p-type SiC boules, and p-type SiC wafers made from such boules were not commercially available or were largely unavailable. In particular, such p-type material was not obtained by the PVT process. Thus, the advantages, benefits, and potential of semiconductor devices based on p-type SiC wafers have not been realized, and in particular have not been utilized in a commercially and economically acceptable manner.

[0047] A further long-standing problem in previous attempts to dope SiC, including incorporating electrically active acceptor atoms into the SiC crystal, has been the lack of uniformity both side-to-side and top-to-bottom of the crystal or wafer. The present invention addresses and solves this long-standing problem in embodiments of the doped SiC crystals and wafers of the present invention by providing methods, raw materials, that provide crystals having a highly uniform distribution of electrically active atomic impurities both side-to-side and top-to-bottom.

[0048] The present invention addresses these long-standing needs by, among other things, providing formulations, methods and apparatus for obtaining p-type SiC materials and semiconductor devices utilizing those p-type SiC materials.

[0049] The present invention solves these problems and long-standing needs by providing, inter alia, the compositions, materials, articles of manufacture, devices, and processes taught and disclosed herein and as claimed.

[0050] The present invention solves these problems and long-standing needs by, among other things, providing high quality, low defect p-type SiC materials, including p-type SiC crystals, p-type SiC ingots, p-type SiC boules, and p-type SiC wafers obtained from those boules. The present invention solves these problems and long-standing needs by, among other things, providing p-type SiC materials, including p-type SiC crystals, p-type SiC ingots, p-type SiC boules, and p-type wafers that are suitable or viable for economical, commercial manufacture, or both, of semiconductor devices. The present invention solves these problems and long-standing needs by, among other things, providing the advantages of SiC semiconductor devices having p-type SiC materials, and, among other things, making the uses and advantages thereof widely available by providing those devices in an economical and commercially viable manner.

[0051] There has also been a long-standing need for low resistivity SiC materials, including low resistivity SiC crystals, SiC ingots, SiC boules, and SiC wafers derived from these boules, particularly low resistivity SiC wafers, and devices that may be built on or from these wafers. These low resistivity wafers include p-type wafers or n-type wafers. The present invention solves these problems and long-standing needs by, among other things, providing low resistivity SiC materials, such as low resistivity SiC crystals, SiC ingots, boules, and wafers, that are suitable or viable for economical and / or commercial manufacture of semiconductor devices. [Means for solving the problem]

[0052] Thus, there is provided a doped polysilocarb precursor material for use in producing doped SiC crystals, comprising: a dopant having a number of donor atoms, a number of acceptor atoms, or both, and silicon, carbon, and oxygen; the dopant is about 10% by weight or less of a total weight of the doped polysilocarb precursor material, said dopant being covalently bonded to at least one of the silicon, carbon, and oxygen, and the doped polysilocarb precursor material defines a potential net carrier concentration (pNc), where pNc = number of donor atoms - number of acceptor atoms.

[0053] Also provided is a doped formed charge raw material for use in producing p-type SiC crystals, the doped formed charge raw material having a porous matrix comprising Si, C, and a number of impurity atoms, the impurity atoms comprising a number of donor atoms, a number of acceptor atoms, or both, the impurity atoms being in a weight ratio of less than 5% of the total weight of the doped formed charge raw material, and the doped formed charge raw material defining a potential net carrier concentration (pNc), where pNc = number of donor atoms - number of acceptor atoms.

[0054] Also provided is a method of producing a doped shaped charge feedstock for use in producing p-type SiC crystals, the method comprising the steps of: providing a liquid precursor composition comprising silicon, carbon, oxygen, and a dopant, the dopant comprising acceptor atoms; curing the liquid precursor to provide a hardened solid precursor, the hardened solid precursor composition comprising silicon, carbon, oxygen, and the acceptor atoms, the acceptor atoms being retained by the hardened solid precursor; pyrolyzing the hardened solid precursor to provide a doped SiC precursor; mixing the doped SiC precursor with a binder and an additional source of acceptor atoms to provide a mixture; forming the mixture into a volumetric shape; hardening the volumetric shape; and pyrolyzing the volumetric shape to provide a shaped charge feedstock consisting essentially of silicon, carbon, and the acceptor atoms.

[0055] Further provided is a method of producing a doped shaped charge raw material for use in producing low resistivity n-type SiC crystals, comprising the steps of: preparing a liquid precursor composition comprising silicon, carbon, oxygen, and a dopant, the dopant comprising donor atoms; curing the liquid precursor composition to provide a hardened solid precursor, the hardened solid precursor composition comprising silicon, carbon, oxygen, and acceptor atoms, the donor atoms being retained by the hardened solid precursor; mixing the hardened solid precursor with a binder and an additional source of donor atoms to provide a mixture; forming the mixture into a volumetric shape; and pyrolyzing the volumetric shape to provide a shaped charge raw material consisting essentially of silicon, carbon, and donor atoms.

[0056] Still further provided is a liquid doped polysilocarb precursor material for use in producing a p-type SiC crystal, the liquid doped polysilocarb precursor material comprising a dopant comprising one or more elements from group 13 of the periodic table, the selected element providing a number of acceptor atoms, silicon, carbon and oxygen, the dopant being in an amount by weight of less than 10% of the total weight of the liquid doped polysilocarb precursor material, the liquid doped polysilocarb precursor material defining a negative potential net carrier concentration (pNc), where pNc = number of donor atoms - number of acceptor atoms.

[0057] Also provided is a liquid doped polysilocarb precursor material for use in producing low resistivity n-type SiC crystals, comprising a dopant comprising one or more elements from Group 15 of the periodic table, the selected element providing a number of donor atoms, and silicon, carbon, and oxygen, the dopant being in an amount by weight of less than 10% of the total weight of the liquid doped polysilocarb precursor material, and the liquid doped polysilocarb precursor material defining a positive potential net carrier concentration (pNc), where pNc = number of donor atoms - number of acceptor atoms.

[0058] These methods, compositions and materials are further provided having one or more of the following characteristics: pNc is positive; 18 more donor atoms; 1 x 10 acceptor atoms 14 The number of acceptor atoms is less than 1 x 10 10the donor atom is selected from one or more elements in Group 15 of the Periodic Table; the donor atom comprises phosphorus; the donor atom consists essentially of phosphorus; the donor atom comprises phosphorus and a covalent bond is formed with the phosphorus, and the polysilocarb precursor further comprises one or more of: ∼Si-OPR (where R is an alkyl group, a phenyl group, or a styrenyl group), ∼Si-C-CPR (where R is an alkene group, a styrenyl group, an alkyl group, or a phenyl group), and (∼Si-O)3-P=O, (as used in these reactions, "∼Si" and "Si-" represent reactive Si functional groups or sites that are attached to a larger structure such as a polymer backbone or a ligand backbone); the precursor material is a hardened solid material; the impurity atoms are immobilized in the porous matrix; the impurity atoms are immobilized in and retained by the porous matrix.

[0059] Further provided are these methods, compositions and materials having one or more of the following features: pNc is positive; 18 more donor atoms; 1×10 14 The number of donor atoms is less than 1 x 10 10the acceptor atom is less than; the acceptor atom is selected from one or more elements of group 13 of the periodic table; the acceptor atom comprises boron; the acceptor atom consists essentially of boron; the acceptor atom comprises aluminum; the acceptor atom consists essentially of aluminum; the acceptor atom comprises aluminum and the precursor material does not comprise an alloy, thereby being alloy free; the acceptor atom consists essentially of aluminum and the precursor material does not comprise an alloy, thereby being alloy free; the precursor does not comprise an alloy, thereby being alloy free; the acceptor atom comprises aluminum and a covalent bond is formed with aluminum, further comprises one or more of 2Al-(O-Si~)3, 2Al-(O-Si~)3, and Al2O3; the acceptor atom comprises boron and a covalent bond is formed with the boron, and the polysilocarb precursor further comprises one or more of 2B-(O-Si~)3 and BCC-Si~ (as used in these reactions, "~Si" and "Si~" represent reactive Si functional groups or sites that are attached to a larger structure, such as a polymer backbone or ligand backbone); the precursor material is a hardened solid material; the impurity atoms are immobilized in the porous matrix; the impurity atoms are immobilized in and held by the porous matrix.

[0060] Further provided are these methods, compositions and materials having one or more of the following features: the impurity atoms are immobilized in the porous matrix; the impurity atoms are immobilized in and held by the porous matrix.

[0061] Further provided are these methods, compositions and materials having one or more of the following features: the dopant is less than 8% by weight of the total weight of the liquid doped polysilocarb precursor material; the dopant is less than 3% by weight of the total weight of the liquid doped polysilocarb precursor material; the weight % of dopant is about 2% to about 5%; the weight % of dopant is less than about 5%; the weight % of dopant is about 1% to about 5%; the weight % of impurity atoms is about 0.2% to about 2%; the weight % of impurity atoms is about 0.5% to about 1%. [Brief description of the drawings]

[0062] [Figure 1] 1 is a photograph showing one embodiment of a 150 mm p-type SiC crystal according to the present invention.

[0063] [Figure 2A] FIG. 1 is a plan schematic diagram of one embodiment of a doped SiC wafer according to the present invention.

[0064] [Figure 2B] FIG. 2B is a schematic cross-sectional view of the wafer taken along line BB in FIG. 2A.

[0065] [Diagram 3] FIG. 1 is a process flow diagram of one embodiment of the system and method according to the present invention.

[0066] [Figure 4] 1 is a schematic cross-sectional view of an embodiment of a deposition apparatus and process according to the present invention.

[0067] [Diagram 5] FIG. 1 is a schematic cross-sectional view showing one embodiment of an N-channel E-MOSFET device using a p-type SiC wafer according to the present invention.

[0068] [Figure 6] FIG. 1 is a schematic cross-sectional view showing one embodiment of a P-channel E-MOSFET device using a p-type SiC wafer according to the present invention.

[0069] [Figure 7] FIG. 1 is a schematic cross-sectional view showing an embodiment of an N-channel D-MOSFET device using a p-type SiC wafer according to the present invention.

[0070] [Figure 8] FIG. 1 is a schematic cross-sectional view showing one embodiment of a P-channel D-MOSFET device using a p-type SiC wafer according to the present invention.

[0071] [Figure 9] 1 is a schematic cross-sectional view showing one embodiment of an IGBT device using a p-type SiC wafer according to the present invention.

[0072] [Figure 10] FIG. 1 is a schematic cross-sectional view showing one embodiment of a lateral diffused MOSFET (LDMOS) device utilizing a p-type SiC wafer according to the present invention.

[0073] [Figure 11] FIG. 1 is a schematic cross-sectional view showing one embodiment of a VMOS MOSFET device using a p-type SiC wafer according to the present invention.

[0074] [Figure 12] FIG. 1 is a schematic cross-sectional view showing one embodiment of a UMOS MOSFET device using a p-type SiC wafer according to the present invention.

[0075] [Figure 13] FIG. 1 is a schematic cross-sectional view showing one embodiment of an IGTB device using a p-type SiC wafer according to the present invention.

[0076] [Figure 14] FIG. 1 is a schematic cross-sectional view showing one embodiment of a CMOS compound device using a p-type SiC wafer according to the present invention.

[0077] [Figure 15] 1 is a schematic cross-sectional view showing one embodiment of a flash memory device using a p-type SiC wafer according to the present invention.

[0078] [Figure 16] FIG. 1 is a schematic cross-sectional view showing one embodiment of an fCMOS compound device using a p-type SiC wafer according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] Generally, the present invention relates to silicon carbide (SiC) crystals, ingots, boules, and wafers, processes for making same, and devices fabricated from or based on those wafers.

[0080] In general, embodiments of the present invention relate to these crystals, ingots, boules, and wafers that are produced using sublimation growth processes, such as physical vapor deposition (PVT), and apparatus for performing sublimation growth processes (e.g., PVT apparatus) using starting materials comprised of polysilocarb precursor materials in a polymer-derived ceramic-based process.

[0081] In general, embodiments of the invention relate to p-type SiC crystals, including ingots, boules, and wafers, processes for producing p-type items thereof, and devices produced from or based on those p-type wafers. In particular, embodiments of the invention relate to cubic p-type SiC crystals, ingots, boules, and wafers, processes for producing p-type items thereof, and devices produced from or based on those p-type wafers. In particular, embodiments of the invention relate to hexagonal p-type SiC crystals, including ingots, boules, and wafers, processes for producing p-type items thereof, and devices produced from or based on those p-type wafers.

[0082] In general, in embodiments, the invention relates to low resistivity SiC crystals, including ingots, boules, and wafers, processes for producing them, and devices produced from or based on those wafers. In particular, in embodiments, the invention relates to n-type and p-type SiC wafers having resistivity of 0.010 Ω·cm or less, preferably 0.005 Ω·cm or less. These low resistivity wafers can be p-type or n-type wafers. In embodiments, these low resistivity wafers have a cubic or hexagonal crystal structure and are p-type or n-type wafers, respectively.

[0083] In general, embodiments of the present invention are based on or include polymer-derived ceramic ("PDC") materials, products and applications that use, are based on, or comprise PDC materials. Examples of PDC materials, compositions, precursors, starting materials, and apparatus and methods for producing such materials are disclosed, for example, in U.S. Pat. Nos. 9,657,409, 9,815,943, 10,091,370, 10,322,936, and 11,014,819, as well as U.S. Patent Publication No. 2018 / 0290893, and U.S. Pat. Nos. 9,499,677, 9,481,781, 8,742,008, 8,119,057, 7,714,092, 7,087,656, 5,153,295, and 4,657,991, the disclosures of each of which are incorporated herein by reference in their entireties.

[0084] A preferred PDC is a "polysilocarb" material, which is a PDC material that contains silicon (Si), oxygen (O), and carbon (C). Polysilocarb materials and their methods of manufacture are disclosed and taught in U.S. Patent Nos. 9,815,943, 9,657,409, 10,322,936, 10,753,010, 11,014,819, and 11,091,370, and U.S. Patent Publication No. 2018 / 0290893, the disclosures of each of which are incorporated herein by reference in their entirety.

[0085] In general, embodiments of the invention include a liquid-to-solid to ceramic-to-crystal process using a PDC liquid precursor material that is hardened to a solid material (e.g., a plastic-like material, a hardened material). This hardened PDC material is converted (e.g., pyrolyzed) to a first PDC ceramic material, and then this first ceramic material is converted (e.g., pyrolyzed) to a PDCSiC raw material. Typically, these steps or transitions are performed as separate heating operations, but can also be performed in a single heating operation. The PDCSiC raw material can be further formed into a shaped charge raw material. The PDCSiC raw material is then used to grow PDCSiC crystals (e.g., by vapor deposition, preferably PVT). Typically, the precursor material is a liquid, but may be a solid, a molten solid, and a melt.

[0086] In general, one or more dopants (e.g., additive materials, e.g., atomic impurities, etc., intended to impart one or more predetermined properties to the SiC crystal material, e.g., crystals, ingots, boules, and wafers) can be added to the PDC material. These dopants are selected to provide predetermined properties, characteristics, or both (e.g., electrical or semiconductor related properties or characteristics) to the SiC crystals (including ingots, boules, and wafers) grown or produced from the PDC precursor. In preferred embodiments, the predetermined electrical or semiconductor properties or characteristics include, for example, resistivity, conductivity, crystal sites (substitutional or interstitial), distribution of donor atoms (i.e., absence of electrons), and electron, concentration, crystal sites and distribution of electrically active atomic impurities, concentration, crystal sites, ratios and distributions of substitutional and interstitial atomic impurities, Nc value, N A value, and N D These characteristics include the value of the carrier concentration, Ne, Nh, and the change in the electronic band structure relative to the valence band energy or conduction band energy or Fermi energy. These characteristics include p-type crystals, low resistivity n-type or p-type crystals, and those with cubic or hexagonal crystal structures.

[0087] Dopants can be added to the liquid PDC precursor material, the hardened solid PDC material, the first PDC ceramic, and combinations and variations thereof. Dopants can also be added to or part of a binder used to form a shaped charge, e.g., a volumetric shape of SiC, for use as a raw material in a vapor deposition (e.g., PVT) process to grow SiC crystals. The preparation and use of shaped charge SiC raw material for vapor deposition (e.g., PVT) growth of SiC crystals is disclosed in U.S. Patent Publication No. 2018 / 0290893, the entire disclosure of which is incorporated herein by reference.

[0088] Generally, in embodiments of the present invention, the dopant is preferably an inseparable part of the PDC material, the SiC feedstock, and both. Thus, the dopant may be (i) chemically bound to the PDC material (e.g., part of a polymer chain in a liquid PDC material, part of a hardened polymer in a solid hardened PDC material, or both), (ii) held (chemically, mechanically, or both) within the matrix (e.g., a nanocomposite) of the PDC material as disclosed and taught in U.S. Patent No. 10,633,400, the disclosure of which is incorporated herein by reference in its entirety, (iii) held (chemically, mechanically, or both) in the SiC feedstock, and (iv) combinations and variations thereof.

[0089] Having the dopant as an inseparable part of the SiC raw material provides several advantages over conventional methods of introducing dopants into a crystal growth deposition process. For example, having the dopant as an inseparable part of the SiC raw material allows the dopant to be sublimated with the Si and C of the raw material to form a flux in the deposition process and apparatus (e.g., PVT). In this method, the dopant is not added separately to the flux after it is formed. Instead, the dopant is formed with the flux and as part of the flux. Having the dopant as an inseparable part in the flux formation allows for better control over the entire process than adding the dopant to the flux after it is formed, such as through gas flow or separate sublimation of the dopant. Thus, generally, preferred embodiments of the present invention avoid the need to have a dopant source separate from the SiC raw material. This includes avoiding the use of dopant-based gas flows to the deposition apparatus, avoiding the use of separate solid dopant sources in the deposition apparatus, and combinations thereof. It is understood that in other embodiments, a different dopant-based gas flow, for example with a second type of dopant, can be used.

[0090] Generally, the location, distribution, and both of the dopants (e.g., atomic impurities) within and throughout the SiC raw material (e.g., formed charge raw material) are fixed. More preferably, the dopants remain fixed in their predetermined location and distribution, and preferably remain fixed throughout most and throughout the deposition process for growing the SiC crystal. In this manner, the dopants can be distributed uniformly throughout the SiC raw material. Also, the concentration, location, and distribution within the SiC raw material can be varied to account for changes in the flux formation and growth of the SiC crystal. In this latter aspect, the predetermined location of the dopants is not uniform, but the distribution of the dopants within the SiC crystal is uniform as a result. In this manner, in an embodiment of the doped formed charge raw material, a matrix of Si, C, and atomic impurities (e.g., donor atoms, acceptor atoms, or both) is provided. The doped formed charge is a porous matrix of this Si, C, and atomic impurities, the matrix retaining the atomic impurities, immobilizing the atomic impurities, or both.

[0091] When using shaped charge SiC raw material embodiments, the predetermined location and distribution of the dopant (e.g., atomic impurities) remains fixed in the solid raw material until the dopant sublimes with the solid raw material. Thus, the dopant can remain fixed in the solid raw material for at least 60%, 70%, 80%, 90%, and 100% of the crystal growth cycle in the deposition (e.g., PVT) process and apparatus to the extent that the solid raw material has not yet sublimated. In other words, in these embodiments, the solid dopant does not change location in the shaped charge relative to the solid SiC during the crystal growth cycle.

[0092] Additionally, fixing dopants (e.g., atomic impurities) at predetermined locations and distributions in the SiC raw material (e.g., SiC compact charge raw material) provides the ability to obtain a high ratio of substitutional impurities to interstitial impurities in the SiC crystal (i.e., greater or more efficient use of atomic impurities). More efficient use of atomic impurities can reduce the adverse effects (e.g., stress) that interstitial impurities cause in the SiC crystal. Incorporation into the growing boule at a uniform concentration throughout growth is more assured, as both the SiC and the doping element sublimate when the dopant atoms come to the surface.

[0093] It is understood that the dopant (e.g., atomic impurity) remains "fixed" during the crystal growth cycle for the unsublimed portion of the raw material (i.e., the remaining portion that has not yet been sublimed). When the raw material sublimes during the deposition process, the dopant also sublimes. In this way, the dopant is formed in and as part of the flux, together with the Si- and C-based components of the flux. Moreover, in this method, preferably, the dopant is not added independently to the flux after it is formed. Instead, the dopant is an integral part of the flux, and even an integral part of the flux formation.

[0094] In general, embodiments of the present invention relate to compositions and methods for providing doped raw materials to produce SiC wafers of a given type. In these embodiments, the starting materials (e.g., precursors) are typically liquids and then hardened into solid materials. The solid starting materials usually contain dopants (e.g., atomic impurities). The solid starting materials are then pyrolyzed into ceramics containing the dopants. This ceramic is further converted to SiC containing the dopants, forming the basis of the raw materials used to grow SiC crystals of a given type, e.g., p-type, low resistivity p-type, low resistivity n-type, etc. These given crystal types are then processed into SiC wafers of, e.g., p-type, low resistivity p-type, low resistivity n-type, etc., respectively.

[0095] In general, embodiments of the present invention relate to compositions and methods for providing doped raw materials to produce SiC wafers of a given type. In these embodiments, the starting materials (e.g., precursors) are typically liquids and then hardened into solid materials. The solid starting materials usually contain dopants (e.g., atomic impurities). The solid starting materials are then pyrolyzed into ceramics containing the dopants. This ceramic is further converted to SiC containing the dopants, forming the basis of the raw materials used to grow SiC crystals of a given type, e.g., p-type, low resistivity p-type, low resistivity n-type, etc. These given crystal types are then processed into SiC wafers of, e.g., p-type, low resistivity p-type, low resistivity n-type, etc., respectively.

[0096] The dopant may be or be based on any element capable of forming electrically active atomic impurities in the SiC crystal and wafer, or any element that provides the SiC crystal and wafer with one or more predetermined electrical, semiconducting, or physical properties. By way of example, the dopant may be or be based on elements selected from Group 13, IIIA (boron (B), aluminum (Al), etc.), Group 2, IIA (beryllium (Be), etc.), and Group 15, VA (nitrogen (N), phosphorus (P), arsenic (As), antimony (Ab), etc.) of the periodic table. The dopant may also be selected from elements in Group 16, VIA (e.g., oxygen (O), sulfur (S), etc.). The dopant may be selected from transition metals such as Ti, Cr, Mn, Ni, Fe, Co, etc. In embodiments, transition metal elements can add properties to the crystalline material, and thus the doped SiC wafers, that provide new classes of performance in devices such as spintronics, photonic bandgaps, and electrochemical devices.

[0097] The preferred dopants for p-type SiC crystals, ingots, boules and wafers are aluminum and boron. For producing n-type low resistivity wafers, the preferred dopants are phosphorus, nitrogen, possibly sulfur, and combinations of phosphorus, sulfur and nitrogen.

[0098] While this specification focuses on SiC deposition techniques, and in particular SiC PVT techniques, it should be understood that the invention is not so limited and is applicable to other SiC crystal growth processes, bonding processes, and other applications. Precursors and Raw Materials - Overview

[0099] Embodiments of the present invention preferably use, are based on, or consist of "polysilocarb" materials, i.e., materials comprising silicon (Si), oxygen (O), and carbon (C), as well as embodiments of such materials that have been cured, pyrolyzed, and converted to SiC for use as a feedstock. Silicon oxycarbide, SiOC compositions, and similar terms refer to polysilocarb materials, unless otherwise specified, and include liquid materials, solid uncured materials, cured materials, ceramic materials, and combinations and variations thereof. Polysilocarb materials and methods of making such materials are disclosed and taught in U.S. Pat. Nos. 9,815,943, 9,657,409, 10,322,936, 10,753,010, 11,014,819, and 11,091,370, and U.S. Patent Publication No. 2018 / 0290893, the disclosures of each of which are incorporated herein by reference in their entireties.

[0100] The polysilocarb material may be of high purity and extra high purity. Thus, it may be 99.99% pure, 99.999% pure, or 99.9999% pure. The polysilocarb material may also include other elements. In particular, in a preferred embodiment, the polysilocarb material includes dopants (e.g., atomic impurities). (Dopants are not counted as impurities when calculating the purity percentage, but are counted as part of the SiC material for purposes of calculating the purity percentage). The polysilocarb material is made from one or more polysilocarb precursors or precursor compositions. The polysilocarb precursor formulation includes one or more functionalized silicon polymers or monomers, non-silicon based crosslinkers, and potentially other components, such as inhibitors, catalysts, dopants, and other additives. Dopants may include, for example, one or more of metals, metal compounds, metal complexes, alloys, non-metals, and combinations and variations thereof.

[0101] Thus, for example, the p-type dopant can include or be based on one or more elements selected from Group 13 (such as boron). A particularly preferred dopant for the production of p-type SiC crystals, ingots, boules, and wafers is aluminum.

[0102] To produce low resistivity p-type crystals and wafers, the amount of dopant included in the starting polysilicon material must be sufficient to provide sufficient dopant to the SiC wafer material and to drive the process of providing sufficient electrically active atomic impurities in the p-type crystal material to have low resistivity. As used herein, "low resistivity" SiC p-type crystals, ingots, boules, and wafers have a resistivity of 0.03 Ω·cm or less, about 0.010 Ω·cm or less, about 0.007 Ω·cm or less, about 0.005 Ω·cm or less, about 0.003 Ω·cm or less, about 0.01 Ω·cm to about 0.001 Ω·cm, about 0.009 Ω·cm to about 0.004 Ω·cm, or about 0.006 Ω·cm to about 0.002 Ω·cm, unless otherwise specified.

[0103] Preferred dopants for low resistivity n-type SiC crystal material are phosphorus, nitrogen, sulfur (as dual donors), and combinations thereof.

[0104] To produce low resistivity n-type crystals and wafers, the amount of dopant included in the starting polysilicon material must be sufficient to provide sufficient dopant to the SiC wafer feedstock and sufficient electrically active atomic impurities to the n-type crystal material to drive the process so that it has low resistivity. As used herein, "low resistivity" SiC n-type crystals, ingots, boules and wafers have a resistivity of 0.03 Ω·cm or less, about 0.010 Ω·cm or less, about 0.007 Ω·cm or less, about 0.005 Ω·cm or less, about 0.003 Ω·cm or less, about 0.01 Ω·cm to about 0.001 Ω·cm, about 0.009 Ω·cm to about 0.004 Ω·cm, about 0.006 Ω·cm to about 0.002 Ω·cm, unless otherwise specified.

[0105] Generally, the polysilocarb precursor composition is initially a liquid. The liquid precursor is cured to form a solid or semi-solid SiOC (i.e., a "cured material"). The solid or semi-solid SiOC is then pyrolyzed to form ceramic SiOC, which is then pyrolyzed to form SiC. These steps or transitions may occur in a single step, separate steps, or individual steps, or combinations or variations thereof.

[0106] Precursor compositions that can be used as starting materials to which dopants (e.g., donor atom, acceptor atom, or both sources) are added, and methods for making those precursor compositions are disclosed and taught in U.S. Pat. No. 11,091,370, the entire disclosure of which is incorporated by reference. These compositions can provide carbon-rich and carbon-deficient SiC raw materials. Depending on the type of donor or acceptor atoms and other conditions, a predetermined stoichiometry of the raw material (e.g., carbon-rich, carbon-deficient) can be beneficial, for example, the predetermined stoichiometry can allow for greater incorporation of dopants as substitutional impurities in the SiC crystal.

[0107] The precursor composition can be made from a variety of precursors.

[0108] The precursor may be a siloxane backbone additive, such as methyl hydrogen (MH), of the formula shown below. TIFF2024528580000002.tif48170

[0109] The MH can have a molecular weight of about 400 mw to about 10,000 mw, about 600 mw to about 3,000 mw ("mw" can be measured as weight average molecular weight in amu or g / mol), and preferably a viscosity of about 20 cps to about 60 cps. The percentage of methylsiloxane units "X" can be 1% to 100%. The percentage of dimethylsiloxane units "Y" can be 0% to 99%. This precursor can be used to impart crosslinked structural frameworks, as well as other characteristics and properties to the cured preforms and ceramic materials. This precursor can also be modified, particularly by reacting with unsaturated carbon compounds, to produce new or additional precursors. Typically, methylhydrogen fluids (MHF) have a minimal amount of "Y", and more preferably "Y" is practically zero.

[0110] The precursor may be a vinyl substituted polydimethylsiloxane, the chemical formula of which is shown below: TIFF2024528580000003.tif46170

[0111] The precursor may have a molecular weight (mw) of about 400 mw to about 10,000 mw, and preferably a viscosity of about 50 cps to about 2,000 cps. The percentage of methylvinylsiloxane units "X" may be 1% to 100%. The percentage of dimethylsiloxane units "Y" may be 0% to 99%. Preferably, X is about 100%. The precursor may be used to reduce crosslink density, improve toughness, and impart other characteristics and properties to the cured preform and ceramic materials.

[0112] The precursor may be a vinyl substituted and vinyl terminated polydimethylsiloxane, the chemical formula of which is shown below. TIFF2024528580000004.tif42170

[0113] The precursor may have a molecular weight (mw) of about 500 mw to about 15,000 mw, preferably about 500 mw to 1,000 mw, and preferably a viscosity of about 10 cps to about 200 cps. The percentage of methylvinylsiloxane units "X" may be 1% to 100%. The percentage of dimethylsiloxane units "Y" may be 0% to 99%. The precursor may be used to impart branching, lower cure temperatures, and other characteristics and properties to the cured preform and ceramic materials.

[0114] The precursor may be tetravinylcyclotetrasiloxane ("TV"), the formula of which is shown below: TIFF2024528580000005.tif55170

[0115] The precursor may be a siloxane backbone additive such as methyl-terminated phenylethylpolysiloxane (also called styrene vinylbenzene dimethylpolysiloxane), the formula of which is: TIFF2024528580000006.tif54170

[0116] The precursor may have a molecular weight (mw) of about 800 mw to at least about 10,000 mw or at least about 20,000 mw, and a viscosity of preferably about 50 cps to about 350 cps. The percentage of styrene vinyl benzene siloxane units "X" may be 1% to 60%. The percentage of dimethyl siloxane units "Y" may be 40% to 99%. The precursor may be used to impart improved toughness, reduce reaction cure exotherms, alter the refractive index, tune the refractive index of the polymer to match the refractive index of various types of glass, for example, to provide transparent glass fibers, as well as impart other characteristics and properties to the cured preforms and ceramic materials.

[0117] The precursor may be divinylbenzene.

[0118] The precursor may also be any of the precursors and liquid starting materials disclosed and taught in US Pat. No. 11,091,370.

[0119] Precursor compositions to which dopants (e.g., sources of donor atoms, acceptor atoms, or both) can be added to provide doped SiC raw materials include, for example, the following precursor compositions:

[0120] A precursor composition consisting of 41 wt% linear methylhydrogenpolysiloxane (MHF) and 59 wt% tetravinylcyclotetrasiloxane (TV).

[0121] A precursor consisting of 90% methyl terminated phenylethyl polysiloxane (having 27% X) and 10% TV mixed at room temperature. The precursor composition has 1.05 moles of hydride, 0.38 moles of vinyl, 0.26 moles of phenyl, and 1.17 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000007.tif53170

[0122] The SiOC obtained from this formulation has a calculated C content of 2.31 moles after removing all the CO, with an excess of C of 98%.

[0123] A precursor composition of 70% methyl terminated phenylethyl polysiloxane (having 14% X) and 30% TV mixed at room temperature. The precursor composition has 0.93 moles of hydride, 0.48 moles of vinyl, 0.13 moles of phenyl, and 1.28 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000008.tif53170

[0124] It is calculated that the SiOC obtained from this formulation has a calculated 1.77 moles of C after removing all the CO, with an excess of C of 38%.

[0125] A precursor composition of 50% methyl terminated phenylethyl polysiloxane (with 20% X) and 50% TV mixed at room temperature. The precursor composition has 0.67 moles of hydride, 0.68 moles of vinyl, 0.10 moles of phenyl, and 1.25 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000009.tif53170

[0126] It is calculated that the SiOC obtained from this formulation has a calculated C of 1.93 moles after removing all the CO, with an excess of C of 55%.

[0127] A precursor composition of 65% methyl terminated phenylethyl polysiloxane (with 40% X) and 35% TV mixed at room temperature. The precursor composition has 0.65 moles of hydride, 0.66 moles of vinyl, 0.25 moles of phenyl, and 1.06 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000010.tif54170

[0128] It is calculated that the SiOC obtained from this formulation has a calculated C of 2.81 moles after removing all the CO, with an excess C of 166%.

[0129] A precursor consisting of 65% MHF and 35% dicyclopentadiene (DCPD) mixed at room temperature. The precursor composition has 1.08 moles of hydride, 0.53 moles of vinyl, 0.0 moles of phenyl, and 1.08 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000011.tif55170

[0130] It is calculated that the SiOC obtained from this formulation has a calculated C of 2.65 moles after removing all the CO, with an excess C of 144%.

[0131] A precursor composition consisting of 82% MHF and 18% dicyclopentadiene (DCPD) mixed at room temperature. The precursor composition has 1.37 moles of hydride, 0.27 moles of vinyl, 0.0 moles of phenyl, and 1.37 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000012.tif55170

[0132] The SiOC resulting from this formulation has a calculated 1.37 moles of C and 0% excess C after removing all the CO.

[0133] A precursor composition of 46% MHF, 34% TV, and 20% VT mixed at room temperature. The precursor composition has 0.77 moles of hydride, 0.40 moles of vinyl, 0.0 moles of phenyl, and 1.43 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000013.tif50170

[0134] If we calculate, the SiOC obtained from this formulation, after removing all the CO, will have a calculated C deficiency of 63%, i.e., it is deficient in 63%.

[0135] A precursor composition of 70% MHF, 20% TV, and 10% VT mixed at room temperature. The precursor composition has 1.17 moles of hydride, 0.23 moles of vinyl, 0.0 moles of phenyl, and 1.53 moles of methyl. The precursor composition has the following molar amounts of Si, C, and O based on 100 g of composition: TIFF2024528580000014.tif50170

[0136] By calculation, the SiOC obtained from this formulation, after removing all the CO, has a calculated C deficiency of 78%, i.e., it is 78% deficient in C, with 0.33 moles of C.

[0137] A precursor composition having 50% methyl terminated phenylethyl polysiloxane (having 20% ​​X) and 50% TV, 95% MHF.

[0138] A precursor composition having 54% methyl terminated phenylethyl polysiloxane (having 25% X) and 46% TV.

[0139] A precursor composition having 57% methyl-terminated phenylethyl polysiloxane (having 30% X) and 43% TV.

[0140] The precursor composition may also be any of the precursor compositions disclosed and taught in US Pat. No. 11,091,370.

[0141] One or more dopants (e.g., compositions or materials based on or including atomic impurities to provide donor or acceptor atoms in the flux during the crystal growth process) can be added to one or more of the liquid precursors, and thus to the liquid precursor composition, where the dopants become part of the cured SiOC material, and thus of the SiOC ceramic and SiC. The dopants can be chemically reacted, i.e., chemically bonded, with the components of the liquid precursor in the liquid state. The dopants can be part of the mixture, e.g., a solution or suspension, of the liquid polysilocarb precursor. In this situation, the dopants can be chemically bonded to the polysilocarb material during the curing step, and thus to the cured SiOC material, to the ceramic SiOC material during the pyrolysis step, or to the doped SiC raw material during the conversion step (chemically or mechanically), and combinations and variations thereof are possible. This can be the case for either p-type doped SiC raw material (providing or growing p-type crystals) or low-resistivity doped SiC raw material (providing or growing low-resistivity crystals of either n-type or p-type).

[0142] The dopant can be part of the mixture, e.g., a solid mixed with the hardening material, the SiOC ceramic, or both, where the dopant can be chemically bonded to the SiOC material during one or more subsequent steps to provide a p-type doped SiC raw material or a low resistivity SiC raw material.

[0143] Generally, in the embodiment of the present invention, the dopant is preferably an inseparable part of the SiOC material, the SiC raw material, and both.Therefore, the dopant can be (i) chemically bonded to the SiOC material (e.g., part or composition of one or more polymer chains of the liquid SiOC precursor material, part of the cured polymer in the cured SiOC material, or both), (ii) held (chemically, mechanically, or both) in the matrix (e.g., nanocomposite) of the SiOC material as disclosed and taught in U.S. Patent No. 10,633,400, or (iii) held (chemically, mechanically, or both) in the SiC raw material.

[0144] In embodiments of the starting materials, intermediate materials, and processes for providing p-type SiC material, the dopant is covalently bonded to one or more of the Si, C, O atoms in the SiOC composition. Thus, for example, upon conversion of the cured SiOC material to SiC, the dopant becomes covalently bonded to Si, C, or both and uniformly distributed throughout the SiC source material (i.e., powder), SiC compact charge (if used), for a deposition process, e.g., PVT, to grow p-type SiC crystal.

[0145] Typically, two types of reactions can be employed to covalently incorporate dopant molecules into the polymer network: hydrosilylation and condensation. Generally, hydrosilylation uses at least one alkene functionality on the dopant molecule. In preferred embodiments, for example, they have two functional groups, more preferably three to four functional groups. Condensation reactions use alkoxide, alcohol, or hydroxide groups (-OR), where R is usually a small alkane or hydrogen.

[0146] In some embodiments, upon pyrolysis, graphene, graphite, amorphous carbon structures, and combinations and variations thereof are present in the Si-OC ceramic. A distribution of silicon species consisting of SiOxCy structures resulting in SiO4, SiO3C, SiO2C2, SiOC3, and SiC4 is formed in various ratios resulting from the choice of precursors and their processing history. In these embodiments, dopants can be bonded together with the amorphous carbon structures between adjacent carbon and silicon atoms. In general, for SiOC, in the ceramic state, carbon is poorly coordinated to oxygen atoms, therefore oxygen is heavily coordinated to silicon, and dopants are heavily coordinated to either silicon or carbon depending on their starting structure.

[0147] In a preferred embodiment, the starting material for a deposition process for growing p-type crystals, e.g., PVT, has a dopant selected from one or more elements selected from group 13 of the periodic table (e.g., boron). The dopant is covalently bonded to the Si, C, or both of the source material and is uniformly distributed throughout the source material. In a more preferred embodiment, the starting material is configured as a shaped charge, and the dopant is distributed throughout the shaped charge in a predetermined manner, e.g., uniformly, in layers of various concentrations, etc. This source material is then used to perform a deposition process, e.g., as described in the "Crystal Growth - General" subsection of this specification.

[0148] In a preferred embodiment, the starting material for a deposition process, e.g., PVT, for growing low resistivity n-type crystals, has a dopant selected from one or more elements selected from group 15 of the periodic table (e.g., nitrogen). The dopant is covalently bonded to the Si, C, or both of the source material and is uniformly distributed throughout the source material. In a more preferred embodiment, the starting material is configured as a shaped charge, and the dopant is distributed throughout the shaped charge in a predetermined manner, e.g., uniformly, in layers of various concentrations, etc. This source material is then used to perform a deposition process, e.g., as described in the "Crystal Growth - General" subsection of this specification.

[0149] In one embodiment of the p-type material and process of the present invention, the dopant, acceptor impurity atoms are part of the SiC raw material, e.g., chemically bonded, covalently bonded, or trapped within the SiC matrix. Furthermore, in this embodiment, the dopant and its acceptor impurity atoms are not present in the starting material in the form of an alloy. For example, the dopant can be aluminum, which is present in the raw material and not present as an alloy. Thus, in this manner, during deposition, e.g., during flux formation, and thereafter, the dopant, and acceptor impurity atoms are not alloyed or otherwise formed into an alloy. It is believed that the use of alloys, this alloying step, or avoidance of alloy formation, provides significant advantages over the prior art, resulting in improved crystal growth, formation, and properties. (As used herein, an alloy is a material of two or more metals or a metal and a nonmetal that are usually intimately bound together by fusing and dissolving together when melted. An alloy can have different metals present in ratios of 99:1, 90:10, 80:20 to 50:50.) The term alloy-free, or non-forming alloy, refers to not having or forming alloys having ratios of 90:10, 80:20 to 50:50. In embodiments, alloys having ratios of 99:1 to 91:9 may also be avoided and thus not present in the starting materials or found or formed in the deposition equipment.

[0150] In one embodiment, the dopant can be a high purity aluminum / silicon alloy or aluminum doped silicon powder as a precursor component. The doped silicon powder can be reacted with carbon to form Al doped SiC powder. This powder can be the molding charge raw material.

[0151] FIG. 3 provides a schematic perspective flow diagram of one embodiment of a system and method for producing doped SiC feedstock, (p-type doped feedstock, low resistivity p-type doped feedstock, or low resistivity n-type doped feedstock), including a shaped charge (e.g., volumetric shape) of doped SiC feedstock. The SiC feedstock is obtained from doped SiOC precursors and intermediate materials. The doped SiC feedstock and shaped charge are preferably of high purity (e.g., 3-nines, 4-nines, 5-nines or higher, preferably 6-nines or higher). The lines, valves, and internal surfaces of the system, including the precursors and other materials, are made of or coated with materials that do not contaminate the SiOC, derived SiC, and SiC volumetric shapes, e.g., do not provide a contaminant feedstock.

[0152] In embodiments where only p-type dopants (i.e., dopants that are a source of acceptor atoms) are used, the presence of raw materials that are considered or are a source of donor atoms, such as nitrogen, should be minimized, mitigated, or eliminated. (Note that in other embodiments, nitrogen may be present in lesser amounts than p-type dopants, resulting in p-type raw materials, i.e., raw materials configured to grow crystals with a negative Nc.)

[0153] Similarly, in embodiments where only n-type dopants (i.e., dopants that provide a source of donor atoms) are used, the presence of raw materials that provide a source of acceptor atoms, such as boron or aluminum, should be minimized, mitigated, or eliminated. (Note that in other embodiments, boron or aluminum may be present in smaller amounts than the n-type dopants to provide n-type raw materials, i.e., raw materials configured to grow crystals having a positive Nc.)

[0154] Storage tanks 150a, 150b store the liquid polysilocarb precursors, and the dopants can be contained in another storage tank, hopper, or bin 150c. If multiple dopants are used, there can also be multiple tanks, hoppers, or bins. The dopants can be added to the storage tank or mixer 152. In this embodiment, to remove contaminants from the liquid precursors, one or both of the precursors can be passed through distillation apparatus 151a and distillation apparatus 151b, or neither precursor can be passed through. Care must be taken not to damage the dopants or affect their properties.

[0155] The liquid precursors and dopants are then transferred to a mixing vessel 152 where they are mixed to form a doped precursor batch (e.g., p-type, low resistivity p-type, or low resistivity n-type) and catalyzed. The precursor batch is then poured into a vessel 153 (preferably in a clean room environment 157a) for entry into a furnace 154. The furnace 154 may have a sweep gas inlet 161 and an off-gas outlet line 162. Typically the sweep gas is an inert gas such as argon. The furnace hardens the liquid polysilocarb material and reacts the dopants with the polysilocarb material, causing the dopants to bond to the hardened polysilocarb material or become part of the polysilocarb material.

[0156] The hardened material, i.e., solid doped SiOC (e.g., p-type, low resistivity p-type, or low resistivity n-type), is then transferred, preferably under clean room conditions, to one, preferably several pyrolysis furnaces 155a, 155b, 155c, where the doped SiOC is converted to doped SiC raw material (e.g., p-type, low resistivity p-type, or low resistivity n-type). (Note that in this embodiment, the SiOC ceramic is the phase that is formed during conversion to SiC in furnace 155a, for example). The furnaces have sweep gas inlets 158a, 158b, 158c, respectively, and two off-gas removal lines 159a and 160a, 159b and 160b, 159c and 160c, respectively. Typically, the sweep gas is an inert gas such as argon. The off-gas can be treated, cleaned, and starting materials recovered in an off-gas treatment assembly 163 that has an inlet 164 that collects the off-gas from various units in the system.

[0157] The resulting powdered doped SiC raw material (e.g., p-type, low resistivity p-type, or low resistivity n-type) is then transferred to a volume shape forming area 190, preferably under clean room conditions. In area 190, the doped SiC material is fed into a mixing vessel 172 having a mixing device 173 (e.g., blades, paddles, agitators, etc.). Binder from a binder tank 170 is added to vessel 172 via line 171. In mixing vessel 172, the SiC is mixed with the binder to form a slurry or blend. The viscosity of the slurry should be such that it facilitates subsequent shaping operations. The SiC-binder slurry is then transferred to a forming apparatus 175 where the slurry is formed into volumetric shapes, such as pellets, disks, blocks, etc., preferably doped formed charge raw material (e.g., p-type, low resistivity p-type, or low resistivity n-type), and fed to an oven 177 where the binder is cured to impart the desired strength to the volumetric shapes, and preferably pyrolyzed.

[0158] The volume shapes can then be transferred to packaging equipment 180 where they can be packaged. Preferably, these operations are performed under clean room conditions, and more preferably in separate clean rooms, i.e., clean room areas 190a, 190b, 190c. The shaped charge can also be fed directly to a deposition equipment (e.g., PVT) for growing doped SiC crystals (e.g., p-type, low resistivity p-type, or low resistivity n-type).

[0159] Preferably, in producing p-type doped SiC, low resistivity p-type doped SiC, or low resistivity n-type doped SiC raw material, in a preferred embodiment, the polysiloxane precursor and dopant can be mixed in clean air at about 1 atmosphere pressure.

[0160] Preferably, in producing SiC and materials for use in producing SiC, the curing of the doped, preferably catalyzed precursor material is carried out at temperatures ranging from about 20°C to about 150°C, about 75°C to about 125°C, and about 80°C to about 90°C, as well as variations and combinations of these temperatures, and all values ​​within these temperature ranges. Curing is preferably carried out for a period of time that results in a hard cured product. Curing can be carried out in air or in an inert atmosphere, preferably in an argon atmosphere at ambient pressure. Preferably, for high purity materials, the furnace, vessel, handling equipment, and other components of the curing apparatus are clean and do not contain or contribute substantially to the cured material elements or materials that would be considered impurities or contaminants. It is noted that in preferred embodiments, the source of donor atoms or the source of acceptor atoms may be considered contaminants depending on the type of crystal being grown.

[0161] Preferably, in the production of doped SiC raw material (e.g., p-type, low resistivity p-type, or low resistivity n-type), pyrolysis is carried out at temperatures ranging from about 800°C to about 1300°C, from about 900°C to about 1200°C, and from about 950°C to about 1150°C, and all values ​​within these temperature ranges. Pyrolysis is preferably carried out for a time period that results in complete pyrolysis of the hardened doped SiOC material to p-type doped SiC raw material. Preferably, pyrolysis is carried out in an inert gas, such as argon, more preferably in flowing argon gas at about atmospheric pressure. The gas can be made to flow at about 1,200cc / min to about 200cc / min, from about 800cc / min to about 400cc / min, and about 500cc / min, and all values ​​within these flow ranges. Preferably, the initial evacuation of the process furnace is at least 1×10 -3 The evacuation is completed to below 1×10 Torr and repressurized with an inert gas, e.g., argon, to above 100 Torr. More preferably, the evacuation is completed to below 1×10 Torr before repressurizing with the inert gas. -5 The vacuum pumping process is completed to a pressure of less than 100 Torr. The evacuation process can be performed anywhere from 0 to 4 or more times. Preferably, for high purity materials, the furnace, vessel, handling equipment, and other components of the curing apparatus are clean and substantially free of contaminants, and do not contribute or contribute any elements or materials that would be considered contaminants to the pyrolyzed materials.

[0162] Pyrolysis can be carried out in any heating device capable of maintaining the required temperature and environmental control, such as pressure furnaces, box furnaces, tube furnaces, crystal growth furnaces, graphite box furnaces, arc melting furnaces, induction furnaces, kilns, MoSi2 heating element furnaces, carbon furnaces, vacuum furnaces, gas furnaces, electric furnaces, direct heated, indirect heated, fluidized bed, RF furnaces, kilns, tunnel kilns, box kilns, shuttle kilns, direct heated, indirect heated, fluidized bed, RF furnaces, kilns, tunnel kilns, box kilns, shuttle kilns, coking equipment, lasers, microwaves, other electromagnetic radiation, and combinations and variations of these and other heating devices and systems capable of obtaining the required temperatures for pyrolysis.

[0163] Preferably, in the production of doped SiC raw material, the ceramic doped SiOC is converted to SiC in a subsequent or continuous pyrolysis or conversion step. The conversion step from the doped SiOC may be, for example, part of the pyrolysis of the doped SiOC cured material, may be continuous, or may be a completely separate step in time, place, and both. Depending on the type of doped SiC desired, the conversion step (SiOC to SiC) may be carried out at about 1,200°C to about 2,550°C, about 1,300°C to 1,700°C, and all values ​​within these temperature ranges.

[0164] Generally, temperatures between about 1600°C and 1900°C promote the formation of the β form over time. Temperatures above 1900°C promote the formation of the α form over time. Preferably, the conversion is carried out in an inert gas, such as argon, more preferably flowing argon gas at about atmospheric pressure. The gas can flow at about 600cc / min to about 10cc / min, about 300cc / min to about 50cc / min, and about 80cc / min to about 40cc / min, and all values ​​within these flow ranges. Preferably, for high purity materials, the furnace, vessel, handling equipment, and other components of the curing apparatus are clean and substantially free of and do not contribute to elements or materials that are considered impurities or contaminants to SiC.

[0165] The subsequent yield of doped SiC from the doped SiOC is generally about 10% to 50%, typically 30% to 40%, although higher and lower ranges and all values ​​within these percentage ranges can be obtained.

[0166] It is further understood that when constraining the amount of dopant to be present in the doped SiOC precursor material, e.g., in mixer 152 or in the hardened solid SiOC, one should consider the loss of dopant throughout the process, including during crystal growth. Thus, sufficient dopant should be present in the SiC wafer to reach a predetermined dopant level, e.g., a predetermined amount of electrically active atoms in the crystal grown from the source material, and thus in the wafers produced from the crystal, to provide the predetermined intended electrical and semiconducting properties of the crystal and wafer.

[0167] The binder for forming the doped volume shape feedstock, e.g., the doped molded charge feedstock, can be any binder used to hold the SiC in a given shape during processing, curing, and later use of the volume shape. Binder embodiments can preferably be oxygen-free. Binder embodiments can preferably be composed of materials having only carbon and hydrogen. Binder embodiments can be made from materials having oxygen. Binder embodiments can be any sintering aid used in sintering SiC. Binder embodiments can be fused silica. Binder embodiments can be polysilocarb precursor materials, including all of the liquid precursors described herein. Combinations and variations of these and other materials can also be used as binders. The binder can also include a dopant, which can be the same or different from the dopant in the SiC powder used to make the molded charge.

[0168] The binder can be cured and pyrolyzed to the extent necessary under conditions used to cure the polysilocarb precursor or under conditions necessary to transform the binder into a material that is sufficiently hard (e.g., tough) to maintain the shape of the volumetric shape. Thus, curing, hardening, setting up, or setting up, as the case may be, should be done based on the properties of the binder.

[0169] Examples of oxygen-free binder embodiments include polyethylene, silicon metal, hydrocarbon waxes, polystyrene, polypropylene, and combinations and variations thereof.

[0170] Examples of binder embodiments that contain only carbon and hydrogen include polyethylene, hydrocarbon waxes, carbon or carbon graphite powder, carbon black, HDPE, LDPE, UHDPE, and PP, as well as combinations and variations thereof.

[0171] Examples of oxygen-containing binder embodiments include boric acid, boron oxide, silicon dioxide, polyalcohols, polylactic acid, cellulosic materials, sugars and saccharides, polyesters, epoxies, siloxanes, silicates, silanes, silsesquioxanes, acetates such as ethyl vinyl acetate (EVA), polyacrylates such as PMMA, polymer-derived ceramic precursors, and combinations and variations thereof.

[0172] Examples of embodiments of binders that are sintering aids include silicon, boron oxide, boric acid, boron carbide, silicon and carbon powders, silica, silicates and polymer-derived ceramic precursors, as well as combinations and variations thereof.

[0173] The binder should be selected so as not to interfere with or inhibit the dopant, the growth of the doped SiC crystal, the properties of the doped SiC crystal, and the wafer.

[0174] Binder embodiments include both catalyzed and non-catalyzed precursor compositions, such as those disclosed and taught in U.S. Patent Nos. 9,815,943, 9,657,409, 10,322,936, 10,753,010, 11,014,819, and 11,091,370, and U.S. Patent Publication No. 2018 / 0290893, the entire disclosures of each of which are incorporated herein by reference. Methods of curing these binders are disclosed and taught in these patents and publications, the entire disclosures of each of which are incorporated herein by reference.

[0175] Catalysts such as Ashbys are largely unaffected by aluminum-doped precursor compositions. Phosphorus-containing precursor compositions may cause some catalytic inhibition. Catalyst inhibition by dopants can be overcome by non-catalytic means (e.g., promoting the reaction despite the absence of a catalyst), for example, by supplementing thermal energy during the curing process.

[0176] In a preferred embodiment, doped volume shapes, e.g., molded charges, feedstock (e.g., p-type, low resistivity p-type, or low resistivity n-type) are produced using one or more of the polysilocarb precursor compositions disclosed and taught in the above-listed patents and publications. The binder is pyrolyzed to SiC to provide a hard, durable doped molded charge feedstock. The dopants in the molded charge feedstock are immobilized.

[0177] In one embodiment, the binder is the same polysiloxane precursor used in the production of the SiC feedstock, with or without dopant. Thus, the amount of dopant present in the binder can be from 0% to about 50%. The dopant in the binder can be used to adjust or fine-tune the amount of dopant present in a particular doped SiC molding charge feedstock.

[0178] Although preferred, it is understood that doped SiC crystals and boules can be grown without the use of a molding charge, for example, directly from a doped SiC polymer-derived powder charge or starting material. Additionally, less desirable forms of SiC powder (e.g., not made from a polymer-derived ceramic) can also be used to form the doped SiC molding charge raw material.

[0179] The ability to start with a doped liquid material, e.g., a precursor batch, having substantially all the components, e.g., Si and C and dopants, needed to make a doped SiC feedstock powder (e.g., not made from a polymer-derived ceramic) provides significant advantages in controlling contamination and in creating a predetermined distribution of Si, C, and dopants in the doped feedstock to control flux formation and crystal growth in PVT processes and equipment. Also, based in part on the performance of the inventive polymer-derived p-type doped SiC in deposition equipment and p-type crystal growth, it is theorized that polymer-derived SiC is different from non-polymer-derived SiC and prior use of metal alloys, metal gases, or both in crystal growth processes. Thus, synergistic advantages in crystal growth and purity, wafer yield and device yield further result from one or more of the individual advantages of the polymer-doped ceramic raw materials including bulk density, grain size, phase of doped SiC (beta vs. alpha), stoichiometry, oxygen content (very low or no and no oxide layer), high purity (e.g., 99.999% purity) and ultra-high purity (99.9999%). Dopant Materials - Overview

[0180] In general, a dopant can be any material or combination of such materials that can be used in a PDC process (e.g., PDC based on polysilicon materials) to form SiC raw material and that does not interfere with the PDC process and imparts predetermined atomic impurities (e.g., donor atoms, acceptor atoms, and combinations thereof) into the SiC raw material, which is then used in a vapor flux process to produce a flux having these atomic impurities and grow a crystal from the flux, which also has these atomic impurities as electrically active atomic impurities.

[0181] For p-type crystals, ingots, boules, and wafers, and p-type low resistivity crystals, ingots, boules, and wafers, aluminum and boron are the preferred atomic impurities, and therefore the preferred dopants are materials capable of providing these atomic impurities.

[0182] For example, dopant materials that can provide aluminum to the source material and provide electrically active impurities of aluminum atoms to the SiC crystal structure are generally reactive aluminum materials, non-reactive aluminum materials, and pure alumina materials.

[0183] Typically, reactive aluminum materials are added to liquid precursor materials (e.g., precursor compositions) and then chemically react with these precursor materials during the curing step. Reactive aluminum materials include, for example: (i) Aluminum alkoxides: AL(OR)3 where R is an alkyl or phenyl group. The reaction with polysilocarb precursor materials is generally as follows: 2Al(OR)3 + 6SiH → 2Al-(O-Si~)3 + 6RH; (It should be noted that the "~Si" and "Si~" used in these reactions represent reactive Si functional groups, attached to a larger structure such as a polymer backbone or ligand backbone.) (ii) Aluminum hydroxide (R is hydrogen). The reaction with polysilocarb precursor material is generally as follows: 2Al(OH)3+ 6SiH → 2Al-(O-Si~)3+ 3H2; (iii) Bauxite, gibbsite, boehmite, diaspore. Reaction with polysilocarb precursor materials is generally via the hydroxide functional groups of these minerals, similar to (ii). (iv) Trimethylaluminum. The reaction with polysilocarb precursor materials is generally as follows: 2(Al(Me)3) + 3H2O → Al2O3 + 6CH4

[0184] Typically, the non-reactive aluminum material is added to the liquid precursor material (e.g., "precursor composition"), but can also be added to the hardening material, ceramic SiOC, SiC raw materials, and combinations and variations thereof. The non-reactive material is retained by or incorporated into the SiOC and SiC ceramic materials during pyrolysis. Non-reactive materials include, for example, aluminosilicate materials. Examples of such materials include: neosilicate powders such as mullite, kyanite, sillimanite, andalusite, dumortierite, kaolinite, halloysite, pyrophyllite, tectosilicates (feldspars), zeolites, and the like.

[0185] Typically, the pure alumina material is added to the liquid precursor material (e.g., precursor composition), but can also be added to the hardening material, ceramic SiOC, SiC raw materials, and combinations and variations thereof. The pure alumina material is retained by or incorporated into the SiOC and SiC ceramic materials during pyrolysis. Pure alumina materials include, for example, alumina powder Al2O3 and corundum (including sapphire, ruby, etc.).

[0186] All of the aforementioned aluminum dopant materials provide aluminum in the form of a ceramic oxide in, for example, the SiC feedstock material, rather than as an alloy.

[0187] For example, dopant materials capable of providing boron in the source material and providing boron atomic electrically active impurities in the SiC crystal structure are generally: reactive boron materials; non-reactive boron materials.

[0188] Typically, reactive boron materials are added to liquid precursor compositions (e.g., precursor composition (1)) and then chemically react with those precursor materials during the curing step. Reactive boron materials include, for example: (i) Boric acid, B(OH)3. The reaction with the polysilocarb precursor material generally proceeds as follows: 2B(OH)3+ 6SiH → 2B-(O-Si~)3+ 3H2; (ii) Borax (N A2 B4O7-10H2O). The reaction with the SiOC precursor is generally a condensation reaction. (iii) Boronic acid RB(OH)2, where R is an alkene group such as a vinyl group. The reaction with the polysilocarb precursor material is generally a condensation reaction. (iv) Divinylboronic acid Vi-B(OH)-Vi reacts with polysiloxane precursor materials, typically B-Vi + ~SiH → BCC-Si~.

[0189] Typically, the non-reactive boron material is added to the liquid precursor material (e.g., precursor composition), but can also be added to the curing material, ceramic SiOC, SiC raw materials, and combinations and variations thereof. The non-reactive material is retained by or incorporated into the SiOC and SiC ceramic materials during pyrolysis. Non-reactive materials include, for example: borosilicate glass, B2O3, boron carbide.

[0190] For n-type crystals, ingots, boules, and wafers, and n-type low resistivity crystals, ingots, boules, and wafers, nitrogen and phosphorus are the preferred atomic impurities, with phosphorus being an especially preferred atomic impurity, and therefore preferred dopants are materials capable of providing these atomic impurities.

[0191] Nitrogen-containing or nitrogen-donating materials can be added to the liquid precursor material (e.g., precursor composition). Such dopants include amines; amides; azo & diazos; carbamates; urethanes; carboimides; C and N heterocycles; ureas; isocyanates; as potential candidate functional groups to incorporate. Nylon or other N-containing carbon-based polymers can also be added to the composition to react during pyrolysis. However, it should be noted that adding too much nitrogen can introduce undesirable stress, stacking faults, and related defects into the crystals.

[0192] Typically, reactive phosphorus materials are added to liquid precursor materials (e.g., precursor compositions) and then chemically react with those precursor materials during the curing step. Reactive phosphorus materials include, for example:

[0193] (i) Reactive oxides of P such as (R)3-phosphine oxides (R = alkyl, phenyl, styrenyl) including triphenylphosphine oxide shown below. TIFF2024528580000015.tif45170 and phosphorus pentoxide shown below. TIFF2024528580000016.tif49170 The reaction of the polysilocarb precursor material with these dopants is generally carried out as follows. R3-P=0 * + ~Si-H → ~Si-OP-R3

[0194] (ii) Reactive organic phosphines, such as (R1)n - (R2) 3-nOrganic phosphines (where R1 = alkene group, styrenyl group, R2 = alkyl group, phenyl group) For example, diphenylvinylphosphine shown below TIFF2024528580000017.tif38170Divinylphenylphosphine shown below TIFF2024528580000018.tif40170Diphenylstyrylphosphine as shown below TIFF2024528580000019.tif34170 Triarylphosphine (n=3). TIFF2024528580000020.tif29170Reaction of the polysilocarb precursor material with these dopants is generally carried out as follows. R3-PC=C + ~Si-H → ~Si-CCP-R3

[0195] (iii) Phosphines such as PH3, PCl3, PF3, and PBr3. The reaction of the polysilocarb precursor material with these dopants is generally as follows. PX3+ 3~SiH → P-(Si~)3+ HX, where X is a halogen or hydrogen

[0196] (iv) acids including phosphoric acid (H3PO4); polyphosphoric acid (CAS#8017-16-1); ammonium polyphosphate (CAS#68333-79-9); (OR)3, where R is any alkyl group, or phenyl group, or hydrogen; O=P(OR)3, where R is any alkyl group, or phenyl group, or hydrogen; triisopropyl phosphite, as shown below.

[0197] TIFF2024528580000021.tif38170

[0198] Triisopropyl phosphate as shown below

[0199] TIFF2024528580000022.tif39170

[0200] The reaction of the polysilocarb precursor material with these dopants is generally as follows.

[0201] 2(OH)3P=O + 6~Si-H → 2(~Si-O)3-P=O + 3H2

[0202] Typically, the non-reactive phosphorus material is added to the liquid precursor material (e.g., precursor composition), but can also be added to the curing material, ceramic SiOC, SiC raw materials, and combinations and variations thereof. The non-reactive material is retained by or incorporated into the SiOC and SiC ceramic materials during pyrolysis. Non-reactive materials include, for example, phosphorus compounds such as those shown below.

[0203] TIFF2024528580000023.tif59170

[0204] M+ includes sodium, potassium, calcium, lithium, and ammonium.

[0205] Phosphorus pentoxide as shown below

[0206] TIFF2024528580000024.tif62170

[0207] Apatite group (phosphate minerals such as Ca5(PO4)3R, where R is F, Cl, or OH).

[0208] Inorganic dopants containing both N and P can also be used. These are added to the liquid precursor composition (e.g., precursor composition (1)), but can also be added to the cured, ceramic SiOC, SiC raw materials, and combinations and variations thereof. The inorganic materials are either retained by or incorporated into the SiOC and SiC ceramic materials during pyrolysis. These raw materials offer the ability to co-dope both N and P from a single dopant source. Examples of co-dopants include struvite ((NH4)MgPO4-8H20), phosphorus nitride, and triphosphorus pentanonitride (P3N5).

[0209] Other co-dopants (sources of N and P) are cyclophosphazene compounds, polyphosphazene compounds, and hexachlorotriphosphazene compounds, which are added to liquid precursor materials (e.g., precursor compositions) and then chemically react with these precursor materials during curing, pyrolysis, or both.

[0210] Additionally, as previously mentioned, any of the aforementioned dopants may be added to the binder used to form the doped SiC compact charge raw material.

[0211] The dopant can be added to the precursor composition at a weight percentage of about 1%, about 2%, about 2.5%, about 5%, 2% to about 10%, about 1% to about 10%, less than 15%, less than 10%, less than 8%, and about 2% to about 8%. The dopant can be added to the binder at a weight percentage of about 1%, about 1% to about 10%, about 2%, about 2.5%, about 5%, about 2% to about 10%, less than 15%, less than 10%, less than 8%, and about 2% to about 8%.

[0212] The curing and each pyrolysis step incur material losses, e.g., yield losses. These yield losses include losses of dopant material. Therefore, it is necessary to add a sufficient amount of dopant to provide the necessary amount of dopant atoms in the SiC raw material for flux formation and crystal growth, taking into account these yield losses. Doped Crystal Growth - Overview

[0213] Silicon carbide generally does not have a liquid phase and sublimes under vacuum at temperatures above about 1,700-1,800 °C. In industrial and commercial applications, conditions are generally set so that sublimation occurs at temperatures above about 2,500 °C. As silicon carbide sublimes, it typically forms a vapor consisting of several different species of silicon and carbon. It is generally understood that the composition and shape of the raw material (e.g., molding charge), temperature, and pressure determine the ratio of gas-phase components in the silicon-carbon vapor.

[0214] The present invention provides, inter alia, for predetermining, preselecting and controlling the presence of dopants (e.g., additives, elements, compounds intended to provide specific, predetermined properties to SiC wafers) in SiC raw materials, e.g., SiOC starting materials present in powders used in vapor deposition crystal growth processes.

[0215] As silicon carbide sublimes, it forms a vapor of various types of silicon and carbon, e.g., Si, C, SiC, Si2C, and SiC2.

[0216] In general, the present invention uses PVT methods and PVT equipment well understood and known in the art (e.g., U.S. Pat. No. 4,866,005, the disclosure of which is incorporated herein by reference in its entirety) to grow the present p-type, low resistivity p-type and low resistivity n-type crystals. Sublimation crystal growth typically involves sublimation of an elemental source of silicon and carbon or SiC powder to produce a vapor flux of Si and C atoms that condenses on a seed crystal and ultimately forms a large crystal. To control the electrical properties (e.g., resistivity / conductivity) of the SiC crystal, impurity atoms are added to the vapor stream and are incorporated into the crystal along with silicon and carbon atoms. The incorporation of impurities into the crystal is influenced by the seed temperature, pressure, seed surface (silicon or carbon), and the atomic ratio of carbon to silicon in the vapor stream. The ratio of carbon to silicon in the vapor stream is related to the feedstock design, feedstock temperature, and pressure.

[0217] The atomic sizes of silicon and aluminum are similar, and as a result, aluminum impurity atoms will primarily locate at silicon sites in the crystal (as electrically active atomic impurities) or interstitially. To increase the likelihood that aluminum atoms will reside at silicon sites, a carbon-rich vapor flow is desirable.

[0218] In typical sublimation growth of SiC using conventional non-PDC raw materials, the vapor flow is usually richer in silicon than carbon. As a result, aluminum atoms must compete with silicon atoms to occupy silicon sites. This characteristic of SiC sublimation growth based on inorganic sources such as silicon metal, graphite, and SiC abrasives makes it difficult to incorporate enough aluminum into the crystal so that wafers cut from the crystal are electrically conductive and useful for semiconductor device fabrication.

[0219] Embodiments of the present invention overcome this problem, particularly by having the ability to have a raw material with excess carbon and for the dopants to be incorporated into and retained by the raw material. Thus, these doped PDC raw materials can unexpectedly provide favorable flux conditions for highly efficient incorporation of p-type dopants into the SiC crystal. This improves the electrical properties of the p-type crystal, making wafers cut from the crystals of higher quality and superior electrical properties that are particularly commercially useful for semiconductor device manufacturing.

[0220] In embodiments, from the use of PDC molded charge feedstock, the ability to influence and control the Si / C ratio of the flux provides the unexpected in that it provides the ability to create a Si / C ratio that is more likely to promote the incorporation of p-type dopant atom impurities into the crystal when grown on the C-face of the crystal. Although the Si / C ratio of the flux at the seed may decrease over time, it will not decrease below a value of 1, promoting the incorporation of p-type dopants. Thus, embodiments of the molded charge feedstock of the present invention provide the ability to grow p-type SiC crystals in a PVT process using C-face or Si-face seeds. In particular, p-type crystals can be grown on C- or Si-face, 4H or 6H seeds.

[0221] Preferred embodiments of the boule are single crystal and have only a single polytype, it being understood that embodiments of boules having multiple polytypes, multiple crystals, and both are also contemplated by this specification.

[0222] In one embodiment, the liquid PDC starting material, preferably a polysilocarb precursor, more preferably a liquid polysilocarb precursor, is doped with or contains (e.g., chemically bonded, chemically complexed, in solution, in the backbone of a polymer, in a mixture, etc.) certain dopants to provide certain properties to the SiC crystal.

[0223] The dopant is preferably present in the liquid starting material, but can also be added, combined, or mixed with, for example, the cured SiOC material, the ceramic SiOC material, and the molded charge. In some circumstances, such as nitrogen, the dopant can also be added as a gas during the SiC crystal growth process.

[0224] The dopants can be a single material, e.g. an element, or two, three or more elements typically selected from the same column of the periodic table. The use of combinations of different materials from the same column of the periodic table is believed to reduce stress in the SiC crystals (hence similar electronic valence structures but slightly different sizes), resulting in higher quality and more usable boules and wafers.

[0225] Preferred dopants for producing p-type SiC crystals, boules, and wafers are elements selected from Group 13, such as boron. Preferred dopants for producing p-type SiC crystals, boules, and wafers are aluminum. Preferred dopants for producing n-type SiC crystals, boules, and wafers are elements selected from Group 15, such as nitrogen. Preferred dopants for producing n-type SiC crystals, boules, and wafers are nitrogen, phosphorus, and combinations thereof.

[0226] The use of phosphorus, and combinations of nitrogen and phosphorus, as dopants (preferably in liquid polysilacarb materials) can provide SiC wafers with low resistivity.

[0227] In less preferred embodiments of doped crystals (e.g., p-type, low-resistance p-type, low-resistance n-type), the dopant is not uniform across the length of the crystal. In this embodiment, the concentration of dopant (as an electrically active atomic impurity) varies from the seed bottom (the side where crystal growth begins) to the tail top (the side where growth ends), and this variation may vary radially across the diameter of the crystal (as a ratio of the maximum dopant concentration to the minimum dopant concentration of the crystal), which may range from about 300% to 5%.

[0228] In preferred embodiments, the use of doped shaped charge feedstock embodiments reduces these variations to about 100%-5%, less than 200%, less than 150%, less than 100%, less than 50%, and less than 25%, and less than 105%, both tail to seed (i.e., length or height of the crystal) and radially (across the diameter of the crystal). Such reduction in variation can further be obtained in a consistent manner, where the majority, substantially all (i.e., 90% or more), of the crystals grown in the PVT apparatus have the same low variation.

[0229] In embodiments, doped SiC crystals (e.g., p-type, low resistivity p-type, low resistivity n-type) have a substantially uniform distribution of dopants throughout the structure of the crystal, which is obtained by using a predetermined doped formed charge raw material with dopants distributed in the formed charge in a manner that provides uniformity of dopant incorporation into the crystal. Thus, the variation in dopant concentration or electrically active atomic impurity concentration across length (e.g., tail side to seed side ("up and down")) and radial direction (side to side measurement moving along a diameter ("side to side")) in crystal, ingot, boule, or wafer embodiments is less than about 10%, less than about 5%, less than about 2%, and less than 1%. Thus, the entirety of these crystalline materials exhibits the intended electrical properties (e.g., p-type electrical behavior, p-type low resistivity electrical behavior, n-type low resistivity electrical behavior) to the same extent. This allows the crystal, e.g., boule, to be converted into a SiC wafer, and the intended electrical behavior is present throughout the wafer, particularly throughout the thickness of the wafer. Those materials in which the dopants or electrically active impurities are substantially uniformly distributed throughout the material (i.e., with less than 10% vertical and horizontal variation, as discussed above) are referred to herein as "uniformly" or "uniformly" doped SiC wafers, ingots, crystals, or boules.

[0230] Thus, in an embodiment, the p-type SiC wafer is devoid of a layer of n-type material. Moreover, in a preferred embodiment, the p-type SiC wafer (also p-type crystals and p-type boules) has electrically active donor atoms distributed throughout the wafer (also p-type crystals and p-type boules), particularly throughout the thickness of the wafer. Moreover, in a preferred embodiment, the p-type SiC wafer (also p-type crystals and p-type boules) has electrically active atomic impurities distributed throughout the wafer (also p-type crystals and p-type boules), particularly throughout the thickness of the wafer. These materials in which the dopants or electrically active impurities are substantially uniformly distributed throughout the material (i.e., less than 10% vertical and horizontal variation as generally described above) are referred to herein as "uniform p-type SiC" wafers, ingots, crystals, or boules. These uniform p-type SiC crystals, ingots, boules, and wafers include p + Type and p - Also includes type.

[0231] Low resistivity SiC wafers include n-type and p-type. Preferably, for n-type low resistivity SiC wafers, the dopant is phosphorus or a mixture of phosphorus and nitrogen. Preferably, the dopant in the low resistivity crystals, ingots, boules, and wafers is distributed throughout the crystal matrix with less than 100%, less than 50%, less than 25% variation, and more preferably is a homogenous low resistivity SiC material.

[0232] The present invention provides embodiments of methods and processes for growing a boule, e.g., deposition of SiC to form a single crystal boule of p-type SiC or low resistivity p-type or n-type SiC, that is very flat, e.g., has a limited amount of curvature or arc in the face of the boule. The very flat profile of the boule is achieved primarily by using a SiC puck of a preselected shape that is placed in the deposition apparatus. The preselected shape, e.g., shaped charge, is configured such that during the deposition process, the area of ​​the vapor flux and the flow within that area remains constant throughout the boule growth process. In this way, the rate and amount of SiC deposited on the surface of the boule as it grows remains consistent and uniform throughout the boule growth process. Thus, for example, when growing a 6 inch diameter boule, the flux flow area is 28.27 inches. 2 and the flow rate and amount of SiC flowing through that area will be uniform across the area during growth of the boule, e.g., a 3 inch long boule or a 4 inch long boule. Even though the amount and location of SiC available for sublimation changes within the pack during the process, the shape of the pack directs the flux in a manner that keeps the flux flow, e.g., referred to as "directional flux," uniform across the area immediately adjacent the face of the boule. Shaped charges and the use of the charges to grow SiC crystals are disclosed and taught in U.S. Patent Publication 2018 / 0290893, the disclosure of which is incorporated herein by reference in its entirety.

[0233] In one embodiment, the flux is not maintained constant throughout the growth process. Thus, in this embodiment, the rate, distribution of the flux across the growth surface is managed, e.g., controlled in a predetermined manner, to provide a predetermined growth of the boule or region of the growth surface. Thus, for example, at later stages of growth, the flux can be directed in a predetermined manner to compensate for non-uniformities that have occurred in the growth of the boule. In this example, areas that had a high flux in the early stages of growth will have a low flux in the later stages of growth, and similarly, areas that had a low flux in the early stages of growth will have a high flux in the later stages of growth. In this way, the final boule growth surface minimizes the curvature of the boule surface, i.e., maximizes the radius of curvature.

[0234] In one embodiment, a controlled flux, and more preferably a directional flux, can be used to provide a 4-8 inch diameter p-type SiC or low resistivity SiC boule having a characteristic shape defined by a tail end that has a positive radius of curvature when directed above the seed end. This radius is typically in the range of 10-200 inches for a 4-8 inch diameter SiC crystal.

[0235] In embodiments, the radius of curvature (i.e., the inverse of the curvature) of the tail can be at least about 6 inches, at least about 8 inches, at least about 20 inches, at least about 60 inches, and approaching infinity (i.e., flat), as well as all values ​​within these ranges of values. In one embodiment of a 6 inch boule, its radius of curvature (i.e., the inverse of the curvature) is at least about 10 inches, at least about 15 inches, at least about 25 inches, at least about 60 inches, and all values ​​within these ranges of values, as well as approaching infinity (i.e., flat). In one embodiment, the radius of curvature of the boule face is at least 2 times the length of the boule face, at least 5 times the length of the boule face, at least 10 times the length of the boule face, and at least 25 times the length of the boule face, as well as up to and including all values ​​within this range, until the boule face becomes flat.

[0236] In one embodiment, the flux can be manipulated not only by temperature but also by pressure, in addition to the composition and make-up of the PDC raw materials. At a given growth temperature, growth can be slowed down by increasing the chamber pressure. The fastest rates are usually under "full" vacuum (e.g., vacuum pump on, keeping chamber pressure as low as possible). So, as an example, to grow a boule at 400 μm / hr, one can grow it at temperature T1 under full vacuum at P1, or at temperatures T2>T1 with argon partial pressures from a few mBar to tens of mBar (P2>P1). In this way, the flux and growth rate can be "tuned".

[0237] In an embodiment, the polymer-derived doped SiC provides better polytype stability in p-type SiC or low resistivity SiC boules due to a more consistent flux composition over time. This embodiment, i.e., controlled polytype stability, is valuable and important to boule manufacturers because polytype shifts during growth mean that only a portion of the boule is of the original polytype, which typically adversely affects electronic properties that affect device performance of chips manufactured therefrom.

[0238] FIG. 4 shows a schematic cross-sectional view of an apparatus for growing p-type or low resistivity p-type or n-type SiC crystals and crystal structures. Vapor deposition apparatus and processes, particularly PVT apparatus and processes using PDC SiC raw materials, are disclosed in U.S. Pat. No. 10,753,010 and Published Application No. 2018 / 0290893, the entire disclosures of each of which are incorporated herein by reference. The deposition apparatus 1800 is a vessel having a sidewall 1808, a bottom or bottom wall 1809, and a top or top wall 1810. The walls 1808, 1809, 1810 can have ports 1806, 1807, 1805, which can be openings, nozzles, valves, and can control or allow the flow of gas into or out of the apparatus 1800. The apparatus 1800 is associated with a heating element 1804. The heating element can be configured and operated to provide a single temperature zone, or multiple temperature zones, within the apparatus 1800. Inside the apparatus 1800 is a shaped charge 1801 made from doped SiC particles formed together into a doped SiC volume shape (note that in one embodiment the dopant can be incorporated into or part of the binder used to make the SiC volume shape).

[0239] The formed charge 1801 can have a predetermined porosity and density. The SiC particles can have a predetermined porosity and density. The SiC particles are preferably held together by a binder. The formed charge 1801 can be carbon rich, carbon deficient, or stoichiometric. The formed charge 1801 can have zones or layers that are carbon rich, carbon deficient, or stoichiometric. Preferably, the SiC particles are SiC from a SiOC polymer. Non-polymer derived SiC can also be used as part or all of the formed charge. The formed charge 1801 has a height, indicated by arrow 1821, and a cross section or diameter 1820. The formed charge 1801 has an upper side or surface 1823 and a lower surface 1824. In this embodiment, the formed charge 1801 is shown as a flat top and bottom cylinder, it being understood that any of the volumetric shapes contemplated by this specification can be used in the apparatus 1800.

[0240] On top 1810 of apparatus 1800 is a seed crystal 1802, which can have the same type and amount of doping as is intended to be found in the crystal grown on seed crystal 1802. Seed crystal 1800 has a surface 1802a. Seed crystal 1802 has a cross section or diameter 1822 and a height 1823. In some embodiments, the seed crystal can be mounted on a movable platform 1803 to adjust the distance between surface 1802a and surface 1823.

[0241] The diameter 1820 of the shaped charge 1801 can be larger than, smaller than, or the same as the diameter 1822 of the seed crystal 1802 .

[0242] During operation, heating element 1804 raises the temperature of molded charge 1801 to a temperature at which the SiC and dopants sublime. This sublimation results in the formation of a gas having various species of silicon, carbon and dopants. This gas, or flux, resides in area 1850 between surfaces 1802a and 1823. Depending on porosity or other factors, flux may also reside within molded charge 1801. The flux rises through area 1850 into device 1800 where it deposits p-type SiC or n-type, or p-type low resistivity SiC on surface 1802a. Surface 1802a must be kept at a temperature cool enough for the gaseous silicon carbon species and dopant atom impurities to precipitate on the surface forming doped SiC crystals. In this manner, the seed crystal 1802 is grown into a p-type, or n-type, or p-type low resistivity SiC crystal by successively adding grown SiC with dopants on its surface in a polytype-matching orientation. Thus, unless conditioned by the device 1803 (shown in a fully retracted position), during boule growth, the surface 1803 grows toward the bottom 1809, and thus the distance between the surface 1802a and the bottom 1809 decreases. The shape of the molded charge can be used to create a predetermined temperature difference within the molded charge during the deposition process. This predetermined temperature difference can address, reduce and eliminate the deleterious effects of passivation, a condition where seeds accumulate within the molded charge during a process that reduces or prevents the formation of vapor.

[0243] In embodiments where only p-type dopants are used, the presence of raw materials that are considered or are sources of donor atoms such as nitrogen should be minimized, minimized, and eliminated. (Note that in other embodiments, nitrogen may be present in amounts less than the p-type dopants and still result in p-type raw materials, i.e., raw materials configured to grow crystals with negative Nc).

[0244] It is theorized that the process of sublimation and deposition takes place on the surface and within the volumetric shape of the raw material itself, e.g., a molded charge, and follows a naturally occurring thermal gradient in the raw material, or that the thermal gradient can be determined by the shape of the volumetric shape. In an embodiment, the binder preferably remains present during the sublimation temperature, maintaining the shape and integrity of the volumetric shape, and therefore does not sublime below the sublimation temperature of SiC. This thermal gradient is typically upward from the exterior to the interior. It is theorized that the material constantly sublimes and redeposits on adjacent grains, thus undergoing reflux or solid-state "fractional distillation" or "fractional sublimation" of the Si-C species as well as the dopants.

[0245] Additionally, in one embodiment, it is theorized that the volume feature and its predetermined gradient may cause some heavy impurities to be trapped at the bottom of the growth chamber within the structure of the volume feature, while lighter elements may sublimate with the Si-C vapor and be carried to the seed, theoretically allowing dopants or other additives to be released at predetermined times in the process or growth cycle.

[0246] In one embodiment, a shaped charge provides a more consistent flux formation rate for a given temperature. The shape of the shaped charge can be tailored to provide a more uniform temperature throughout the shape, allowing a higher volume fraction of the shape to be sublimated at once, operating at a higher flux rate at the seed / vapor interface at a given temperature than a standard pile of powder or a cylindrical powder. Thus, growth of polytypes that require a lower temperature growth process are not limited to slower growth rates as a result.

[0247] Sublimation rate is measured in grams / hour. Flux is measured in grams / cm 2·hr (i.e., the velocity of material passing through an area). The area of ​​interest is therefore the flux area, which corresponds to the instantaneous surface area of ​​the boule growth face, e.g., the face of the boule on which SiC is being deposited. Typically, the flux area and the area of ​​the boule face are approximately the same, and these areas are usually slightly smaller than the cross-sectional area of ​​the deposition equipment growth chamber.

[0248] For purposes of calculations and this analysis, the cross-sectional area of ​​the growth chamber is assumed to be equal to the flux and the area of ​​the boule face for ease of calculation. Therefore, the growth rate of the boule (μm / hr) is multiplied by the area of ​​the boule face (cm 2 ), the vapor flux can be equated to μm / hr → g / hr (fully dense SiC has a density of 3.21 g / cc). In situ measurements can be made by X-ray imaging or X-ray computed tomography (CT). Also, the average growth rate can be determined by measuring the weight of the boule before and after growth.

[0249] Typical commercial growth rates are in the range of 200-500 μm / hr. Embodiments of the process and volumetric features of the present invention far exceed these existing commercial rates while providing boules of equal or better quality. For example, embodiments of the present invention can have growth rates of about 550 to about 1,1000 μm / hr, about 800 to about 1,000 μm / hr, about 900 to about 1,100 μm / hr, about 700 μm / hr, about 800 μm / hr, about 900 μm / hr, about 1,000 μm / hr, and 1,100 μm / hr at high temperatures and low pressures. Higher rates are contemplated, but slower rates can also be used, as well as all rates within these ranges.

[0250] In general, the growth rate is governed by 1) the temperature and 2) the gas pressure (Ar, N2, etc.) supplied. Higher gas pressures dilute the vapor pressure of the silicon carbon species at the seed and boule surfaces, slowing the growth rate at a given temperature. Thus, pressure can be used to "dial-in" the growth rate.

[0251] Thus, embodiments of a volumetric shape, e.g., a shaped charge, given a constant temperature can maintain a consistent flux generation rate, e.g., constant, throughout the operation of growing p-type SiC or low resistivity SiC crystals, including such crystals having diameters from about 4 inches to about 10 inches, from about 6 inches to about 8 inches, about 4 inches, about 6 inches, about 8 inches, larger, and smaller, and all diameters within these ranges of values. Embodiments of the volumetric shape can maintain the flux generation rate, and thus the boule growth rate, at a constant rate, a rate of change of less than about 0.001%, a rate of change of less than about 0.01%, a rate of change of less than about 1%, a rate of change of less than about 5%, a rate of change of less than about 20%, a rate of change from about 0.001% to about 15%, a rate of change from about 0.01% to about 5%, combinations and variations thereof during crystal growth, and all values ​​within these ranges of values, when the temperature is constant throughout the p-type SiC or low resistivity SiC crystal growth process. In embodiments, at constant temperature, the flux formation rate remains from about 99.999% to about 60% of its maximum rate; from about 99% to about 95% of its maximum rate; from about 99.99% to about 80% of its maximum rate; from about 99% to about 70% of its maximum rate; from about 95% to about 70% of its maximum rate; from about 99% to about 95% of its maximum rate; and combinations and variations thereof, and all values ​​within these percentage ranges, during growth of the boule.

[0252] Embodiments provide for different stoichiometries, different binder contents, different dopant contents, and all of the above distributions of powders throughout a feature, such as a layer, zone, area, etc., with, for example, different types of powder starting materials, different binders, and combinations and variations thereof. This predetermined distribution of different stoichiometries, different binder contents, and both, provides several advantages, including: It allows customization of the sublimation composition as the raw material is consumed from the outside in, resulting in less shift in composition from the beginning to the end of the growth cycle. The predetermined distribution of different stoichiometries, different binder contents, and both, can also increase the stability of the polytype since the composition of the vapor is constant.

[0253] Embodiments of the present invention include the use of doped SiC in the manufacture of p-type or low resistivity SiC wafers for electronics and semiconductor applications. Doped (preferably high purity) SiC is required in both the deposition equipment and processes for making p-type or low resistivity SiC crystals and the subsequent p-type or low resistivity SiC wafers.

[0254] The polysilocarb p-type or low resistivity SiC embodiments of the present invention, and the p-type or low resistivity SiC boules, p-type SiC or low resistivity SiC wafers, and other structures made from polysilocarb-derived SiC, exhibit polymorphism, commonly referred to as polytypicity. Thus, polysilocarb-derived p-type or low resistivity SiC can exist in many, theoretically infinite, different polytypes. As used herein, unless expressly stated otherwise, polytypicity, polytype, and similar such terms should be given the broadest possible meaning, and shall not be construed as limiting the scope of the invention as defined by the appended claims. 4 ) are comprised in a variety of different frames, structures, or arrangements. Generally, these polytypes are divided into two categories: α (alpha) and β (beta).

[0255] The α category of polysilocarb derived p-type or low resistivity SiC embodiments typically include hexagonal (H), rhombohedral (R), trigonal (T) structures, and may include combinations of these. The β category typically includes cubic (C) or zincblende structures. Thus, for example, polysilocarb derived p-type or low resistivity SiC polytypes include: 3C-SiC (β-SiC or β3C-SiC) with a stacking sequence of ABCABC...; 2H-SiC with a stacking sequence of ABAB...; 4H-SiC with a stacking sequence of ABCBABCB...; and 6H-SiC (a common form of alpha silicon, α6H-SiC) with a stacking sequence of ABCACBABCACB.... Examples of other forms of alpha silicon carbide include 8H, 10H, 16H, 18H, 19H, 15R, 21R, 24H, 33R, 39R, 27R, 48H, 51R, etc.

[0256] Embodiments of p-type SiC or low resistivity SiC derived from polysirocarb may be polycrystalline or single crystalline. Generally, in polycrystalline materials, grain boundaries exist as interfaces between two grains or crystallites of the material. These grain boundaries can be between the same polycrystalline body with different orientations, or between different polycrystalline bodies with the same or different orientations, and combinations and variations thereof. Single crystalline structures are composed of a single polytype and have substantially no grain boundaries. In preferred embodiments, the p-type SiC or low resistivity SiC is single crystalline.

[0257] Embodiments of the method result in boules, preferably p-type SiC single crystal or low resistivity SiC boules. These boules can have lengths of about ½ inch to about 5 inches, about ½ inch to about 3 inches, about 1 inch to about 2 inches, greater than about ½ inch, greater than about 1 inch, and greater than about 2 inches. Larger and smaller sizes and all values ​​within these size ranges are contemplated. The boules can have cross sections, e.g., diameters, of about ½ inch to about 9 inches, about 2 inches to about 8 inches, about 1 inch to about 6 inches, greater than about 1 inch, greater than about 2 inches, about 4 inches, about 6 inches, about 8 inches, about 12 inches, and about 18 inches. Other sizes and all values ​​within these size ranges are contemplated. P-type and low resistivity wafers - Overview

[0258] Generally, the process of producing electronic components from p-type SiC or low resistivity SiC boules involves sawing the p-type SiC or low resistivity SiC single crystal boules into thin wafers. The produced SiC wafers are the starting point for the production of SiC-based semiconductor devices. SEMI (www.semi.org) has developed and published standards for the specifications of SiC wafers of various diameters up to 150 mm. These standards are well known and understood by those skilled in the art. As the SiC industry has previously limited the commercialization of p-type SiC crystals and wafers and only n-type, nitrogen-doped SiC crystals and wafers have been commercialized, the most well-known methods for producing SiC wafers suitable for use in the production of semiconductor devices are based on SiC n-type wafers, which can be used to produce p-type, n-type low resistivity, and p-type low resistivity wafers.

[0259] Doped wafer embodiments of the invention have a diameter of the cut boule, typically having a thickness of about 100 μm to about 500 μm. Preferably, the p-type electrical property or low resistivity property is distributed throughout the entire length of the boule or the entire thickness of the wafer. More preferably, the p-type electrical property or low resistivity property is uniformly distributed throughout the entire length of the boule or the entire thickness of the wafer. The p-type or low resistivity SiC wafer is then polished on one or both sides. The polished wafer is used as a substrate for the manufacture of microelectronic semiconductor devices. In this way, the p-type or low resistivity SiC wafer serves as a substrate for the microelectronic devices that are built on the wafer. The manufacture of these microelectronic devices includes microfabrication steps such as epitaxial growth, doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. Once manufactured from the p-type or low resistivity SiC wafer, the wafer, and thus the individual microcircuits, are separated into individual semiconductor devices in a process known as dicing. These devices are used, for example, in the manufacture of various large scale semiconductor and electronic devices.

[0260] Embodiments of the methods and resulting p-type or low resistivity SiC wafers of the present invention include, among others, wafers having a diameter of about 2 inches or less and smaller, about 3 inch diameter wafers, about 4 inch diameter wafers, about 5 inch diameter wafers, about 6 inch diameter wafers, about 7 inch diameter wafers, about 12 inch diameter wafers, and potentially larger wafers having a diameter of about 2 inches to about 8 inches, about 4 inches to about 6 inches, square, circular, and other shaped wafers, and wafers having a surface area of ​​about 1 square inch, about 4 square inches, about 8 square inches, or more. inch, about 10 square inches, about 12 square inches, about 30 square inches, about 50 square inches and larger or smaller surface area wafers, about 100 μm thick, about 200 μm thick, about 300 μm thick, about 500 μm thick, about 700 μm thick, about 50 μm to about 800 μm thick, about 100 μm to about 700 μm thick, about 100 μm to about 400 μm thick, about 100 μm to about 300 μm thick, about 100 μm to about 200 μm thick, and greater and lesser thicknesses, as well as combinations and variations thereof, and all values ​​within these dimensional ranges.

[0261] Embodiments of the method and the resulting sawn and polished p-type or low resistivity SiC wafers can also include being used to initiate the growth of a boule (i.e., as a "seed") that conforms to the structure of the remainder of the grown boule. The p-type or low resistivity SiC wafers, or p-type or low resistivity SiC seeds, can be used to grow a boule of any desired shape, shape, or size, including, among others, wafers having a diameter of about 2 inches or less, wafers having a diameter of about 3 inches or less, wafers having a diameter of about 4 inches or less, wafers having a diameter of about 5 inches or less, wafers having a diameter of about 6 inches or less, wafers having a diameter of about 7 inches or less, wafers having a diameter of about 12 inches and larger, wafers having a diameter of about 2 inches to about 8 inches, wafers having a diameter of about 4 inches to about 6 inches, wafers having a diameter of about 12 inches to about 8 inches, wafers having a diameter of about 4 inches to about 6 inches, wafers having a surface area of ​​about 4 square inches, about 8 square inches, and wafers having a surface area of ​​about 12 square inches to about 8 square inches. , about 12 inch square wafers, about 30 inch square wafers, about 100 μm thick, about 200 μm thick, about 300 μm thick, about 500 μm thick, about 1500 μm thick, about 2500 μm thick, about 50 μm to about 2000 μm thick, about 500 μm to about 1800 μm thick, about 800 μm to about 1500 μm thick, about 500 μm to about 1200 μm thick, about 200 μm to about 2000 μm thick, about 50 μm to about 2500 μm thick, and wafers of greater and lesser thicknesses, and combinations and variations thereof, and wafers having all values ​​within these dimensional ranges.

[0262] Embodiments of the p-type SiC or low resistivity SiC boules, p-type SiC or low resistivity SiC wafers, and microelectronics made from these wafers of the invention may find application and use in, among other things, diodes, wideband amplifiers, military communications, radar, telecommunications, data links and tactical data links, satellite communications and point-to-point wireless power electronics, LEDs, lasers, lighting, and sensors. Additionally, these embodiments may find application and use in transistors such as high electron mobility transistor (HEMT) based monolithic microwave integrated circuits (MMICs) and HEMTs including IGBTs. These transistors may employ distributed (traveling wave) amplifier design approaches and can achieve extremely wide bandwidths in small footprints due to the large band gap of SiC. Thus, embodiments of the invention include those devices and articles made from or based on the methods, deposition techniques, polymer derived SiC, SiC boules, SiC wafers, and microelectronics made from these wafers of the invention.

[0263] Polysirocarb-derived p-type or low resistivity SiC, particularly high purity SiC embodiments, have many unique properties that are advantageous and desirable for use in the electronics, solar, and power transmission industries and applications, among others. High purity SiC acts as a very stable p-type or low resistivity semiconductor material, making it suitable for several demanding applications, including high power, high frequency, high temperature, corrosive environments and applications. Polymer-derived p-type or low resistivity SiC is a very hard material with a Young's modulus of 424 GPa.

[0264] In one embodiment, if a dopant needs to be added to the material, the dopant can be added by the precursor, and thus can be present in a controlled manner and amount for growth into a boule or other structure. Embodiments of the precursor composition can have a dopant, or a complex that carries and bonds the dopant to the ceramic and converted SiC, such that the dopant is in an available and usable form during the deposition process.

[0265] Additionally, dopants or other additives provide custom or predetermined properties to wafers, layers, and structures produced from the polymer-derived SiC embodiments. In these embodiments, such property-enhancing additives are not considered impurities because they are intended and required to be included in the final product. The property-enhancing additives can be incorporated into the liquid precursor material. Depending on the nature of the property-enhancing additive, it can be part of the precursor backbone, complexed for incorporation into the liquid precursor, part of a complex, or in other forms that allow it to remain (e.g., in a form that allows it to function as intended in the final material). The property-enhancing additives can be added as a coating to the SiC or SiOC powder material, added as a vapor or gas during processing, or powdered and mixed with the polymer-derived SiC or SiOC particles. In one embodiment, the property-enhancing additives constitute or are part of the binder of the volume shape. In an embodiment, the property-enhancing additives can be a coating on the volume shape. Furthermore, the form and manner in which the property enhancing additives are present should preferably be such that they have minimal, and more preferably no, adverse effect on processing conditions, processing times, and final product quality. p-Type Devices - Overview

[0266] These p-type SiC wafers provide the ability to fabricate circuits, semiconductor devices, and chips that were previously designed on p-type silicon wafers, minimizing the need to rewrite or redesign the circuits or chips. Thus, in one embodiment, circuits and devices designed using p-type silicon substrates can be directly built, and instead devices fabricated on SiC p-type wafers are used, eliminating the need to modify, configure, or adapt circuits based on silicon devices.

[0267] Thus, embodiments of the present invention address the gap faced by power circuit designers in taking full advantage of the benefits derived from using SiC devices by providing a manufacturable method for producing 4H-SiC or 6H-SiC p-type substrates (e.g., wafers) with low defectivity, resistivity properties and substrate diameters that match current requirements for producing devices such as Schottky Barrier Diodes (SBDs), Junction Barrier Schottky Diodes (JBSs), devices such as MOSFETs, transistors such as gate turn-off transistors (GTOs), integrated gate bipolar transistors (IGBTs), and variations of these transistors and devices, as well as 6H-SiC p-type substrates (e.g., wafers) with low defectivity properties and substrate diameters that match current requirements for producing such devices. Embodiments of the present invention enable the production of p-type substrates with diameters and resistivities that match and preferably exceed those currently commercially produced from n-type SiC crystals. The p-type SiC wafers disclosed and taught herein provide device manufacturers the ability to extend the utility of SiC to p-type SiC for devices in all voltage and amperage ranges currently manufactured with n-type SiC, thereby allowing device manufacturers to extend the utility of SiC. Based on the p-type wafers disclosed and contemplated herein, power circuit designers will be able to extend the benefits of SiC devices to all power management applications, particularly for circuit designs of all voltage ranges, voltage polarities, and amperages.

[0268] Embodiments of the present invention may have or utilize one or more of the embodiments, features, functions, parameters, components, processes, or systems of the teachings of the "Precursors and Raw Materials - Overview", "Dopant Materials - Overview", "Doped Crystal Growth - Overview", "p-Type and Low Resistivity Wafers - Overview", "p-Type Devices - Overview" sections herein, and the examples and figures.

[0269] Working Example

[0270] The following examples are provided to illustrate various embodiments of the systems, processes, compositions, applications, and materials of the present invention. These examples are for illustrative purposes and may be prophetic, but should not be construed as limiting the scope of the present invention. The percentages used in the examples are, for example, weight percentages of the entire composition, mixture, product, or structure, unless expressly stated otherwise. The use of X / Y or XY indicates the % of X and the % of Y in a composition, unless otherwise stated. The use of X / Y / Z or XYZ indicates the % of X, the % of Y, and the % of Z in a composition, unless otherwise stated.

[0271] Example 1

[0272] In one embodiment, a 2.5 wt% dispersion of 5 μm mullite powder (MU-101, MicronMetals) is added to a precursor composition of 41% MHF 59% TV with 30 ppb of Pt added as an Ashbys catalyst. The doped precursor composition is cured and pyrolyzed to SiC. The SiC powder is formed into a molding charge using the doped precursor composition as a molding charge binder, formed into shaped bodies, and cured to a green body. The green body is pyrolyzed and converted to doped SiC molding charge raw material. Further details are provided in Examples 1A to 1D.

[0273] Example 1A

[0274] Liquid Al-doped precursor compositions as shown in Table 1 for use in producing p-type SiC feedstock for use in growing p-type SiC crystals. The target weight ratio of mullite to the precursor composition weight is 2.5%. * Linear methylhydrogenpolysiloxane (MHF) 41wt%, tetravinylcyclotetrasiloxane (TV) 59wt%.

[0275] Example 1B

[0276] The cured Al-doped precursor composition of Example 1A is pyrolyzed to provide the Al-doped SiC materials shown in Table 2. TIFF2024528580000026.tif63170

[0277] Example 1C

[0278] The ceramic Al-doped SiC material of Example 1B is formed into volume shapes and cured as shown in Table 3. Mullite is added with a binder in forming the volume shapes. TIFF2024528580000027.tif49170 * Linear methylhydrogenpolysiloxane (MHF) 41wt%, tetravinylcyclotetrasiloxane (TV) 59wt%.

[0279] Example 1D

[0280] The hardened volume shape of Example 1C is pyrolyzed as shown in Table 4 to provide Al-doped SiC compact charge raw material for use in PVT growth of p-type SiC crystals. TIFF2024528580000028.tif44170

[0281] Example 2

[0282] The same general formulations and procedures as in Examples 1A-1D are followed, except that instead of aluminum dopant, trialkylphosphine is added to the liquid pressurizing agent (1%-15% by weight trialkylphosphine relative to the precursor composition) and may also be added with the binder (1%-15% by weight trialkylphosphine relative to the P-doped SiC powder and binder), to form a hardened P-doped SiC volume shape which is pyrolyzed to form a P-doped SiC compact charge feedstock which is used for PVT growth of low resistivity n-type SiC crystals.

[0283] Example 3

[0284] FIG. 1 shows a photograph of a p-type SiC crystal with a diameter of about 150 mm. The crystal was grown using the PVT process and apparatus using an Al-doped SiC compact charge feedstock of the type of Example 1D. The p-type crystal has 70 ppm Al. The p-type crystal has a diameter of 5.5×10 18 Al atoms / cc. The length of the crystal is about 23 mm. A thin slice of the crystal was prepared and polished, and it appeared blue-purple in transmission. No evidence of polytype switching from 4H to any other polytype was observed.

[0285] Example 4

[0286] FIG. 2A shows a top schematic view of a doped SiC wafer 700. FIG. 2B shows a cross-sectional view of the wafer 700 along line BB. The wafer 700 can be a p-type SiC wafer, the wafer 700 can be a low resistivity p-type SiC wafer, or the wafer 700 can be a low resistivity n-type SiC wafer. The wafer 700 is a semicircular disc-like crystal structure 705 having a flat portion 706. It is understood that the wafer may be circular and may have one or more flat portions. The wafer 700 has an edge 730. The wafer 700 has a top or upper surface 710, a bottom or lower surface 711, and a thickness indicated by arrow 712. Both the top and bottom surfaces of the wafer 700, as well as the entire thickness 712, are doped SiC crystal. It is understood that one surface is typically the C-face of the SiC crystal and the other surface is the Si-face of the SiC crystal. One or both surfaces may be polished to a finish for use in device fabrication. The outer edge 730 of the wafer 700 may be tapered, chamfered, beveled, square, rounded, etc.

[0287] Wafer 700 is cut from a doped SiC boule having a length significantly greater (eg, 10x, 20x, 50x, 70x or more) than thickness 712 of wafer 700.

[0288] Thus, wafer 700 is not a thin doped SiC layer that has been grown or deposited on a substrate layer of a different type of material and then the substrate layer is removed. Such thin, e.g., less than 1 mm, less than 0.5 mm, substrate-grown doped SiC layers from which the substrate has been removed have significantly different electrical and physical properties than doped SiC wafers cut from doped SiC boules. Such substrate-grown thin doped layers have unacceptable stresses in the material, exhibit warping or curvature, and are generally not suitable for semiconductor device fabrication of any kind.

[0289] Example 5

[0290] 6 inch (150 mm) p-type SiC wafer. Polytype 4H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.015-0.028Ω·cm.

[0291] Example 6

[0292] 6 inch (150 mm) low resistivity p-type SiC wafer. Polytype 4H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. -SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0293] Example 7

[0294] 6 inch (150 mm) p-type SiC wafer. Polytype 6H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. -SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.015-0.028Ω·cm.

[0295] Example 8

[0296] 6 inch (150 mm) low resistivity p-type SiC wafer. Polytype 6H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. -SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0297] Example 9

[0298] 6 inch (150 mm) low resistivity n-type SiC wafer. Polytype 4H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0299] Example 10

[0300] 6 inch (150 mm) low resistivity n-type SiC wafer. Polytype 6H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0301] Example 11

[0302] FIG. 5 shows a schematic diagram of an N-channel E-MOSFET device 500 from a p-type SiC wafer. The device 500 has a gate 512, a metal electrode 505, and a metal oxide layer 504. The device 500 has a source 509, a drain 508, and a body 510. A circuit 511 is formed between the source 509 and the body 510. The source 509 is connected to the n-type SiC 502 through a metal electrode. The drain 508 is connected to the n-type SiC 503 through a metal electrode. The device 500 has a p-type substrate 501 made from a p-type wafer cut from a p-type boule. A metal oxide layer 507 is adjacent to the p-type substrate 501. The body 510 is connected to the p-type substrate 501 through electrode 507.

[0303] Example 12

[0304] FIG. 6 shows a schematic diagram of a P-channel E-MOSFET device 600 using a p-type SiC wafer. The device 600 has a gate 612, a metal electrode 605, and a metal oxide layer 604. The device 600 has a source 609, a drain 608, and a body 610. A circuit 611 is formed between the source 609 and the body 610. The source 609 is connected to the p-type SiC 602 through a metal electrode. The drain 608 is connected to the p-type SiC 603 through a metal electrode. The p-type SiC 602, 603 are made from a p-type wafer cut from a p-type boule. The device 600 has an n-type substrate 601. A metal oxide layer 607 is adjacent to the n-type substrate 601. The body 610 is connected to the n-type substrate 601 through an electrode 607.

[0305] Example 13

[0306] FIG. 7 shows a schematic diagram of an N-channel D-MOSFET device 750 using a p-type SiC wafer. The device 750 has a gate 762, a metal electrode 755, and a metal oxide layer 754. The device 750 has a source 759, a drain 758, and a body 760. A circuit 761 is formed between the source 759 and the body 760. The source 759 is connected to the n-type SiC 752 through a metal electrode. The drain 758 is connected to the n-type SiC 753 through a metal electrode. The device 750 has an N-channel 751 with a channel length as indicated by the arrow 764. The device 750 has a p-type substrate 763 cut from a p-type wafer. A metal oxide layer 756 is adjacent to the p-type substrate 763 and a portion of the N-channel 751. The body 760 is connected to the p-type substrate 763 through an electrode 757.

[0307] Example 14

[0308] FIG. 8 shows a schematic diagram of a P-channel D-MOSFET device 800 using a p-type SiC wafer. The device 800 has a gate 812, a metal electrode 805, and a metal oxide layer 804. The device 800 has a source 809, a drain 808, and a body 810. A circuit 811 is formed between the source 809 and the body 810. The source 809 is connected to the p-type SiC 802 through a metal electrode, and the drain 808 is connected to the p-type SiC 803 through a metal electrode. The p-type SiC 802 and 803 are made from a p-type wafer cut from a p-type boule. The device 800 has a P-channel 801 made from a p-type wafer cut from a p-type boule. Arrow 814 indicates the channel length. The device 800 has an n-type substrate 813. A metal oxide layer 806 is adjacent to the n-type substrate 813 and a portion of the P-channel 801. The base 810 is connected to an n-type substrate 813 via an electrode 807 .

[0309] Example 15

[0310] 9 shows a cross-sectional schematic diagram of a SiC IGBT device 900. The device 900 comprises a p-type SiC IGBT device 900 that forms a layer 901 as well as other p-type materials in the multi-layer structure of the device 900. + p cut out of type bool + The other layers of the device may be based on PDCn type SiC wafers.

[0311] Example 16

[0312] 10 shows a cross-sectional schematic diagram of a SiC laterally diffused MOSFET (LDMOS) device 1000. The device 1000 includes a p-type SiC MOSFET forming layer 1001 as well as other p-type materials in the multi-layer structure of the device 1000. + p cut out of type bool + The other layers of the device may be based on PDCn type SiC wafers.

[0313] Example 17

[0314] 11 shows a cross-sectional schematic of device 1100. Device 1100 is based on a p-type wafer cut from a p-type boule that forms the p-type material of the multi-layer structure of device 1100. Other layers of the device may also be based on PDCn-SiC wafers.

[0315] Example 18

[0316] 12 shows a cross-sectional schematic of a SiC UMOS MOSFET device 1200. Device 1200 is based on a p-type wafer cut from a p-type boule that forms the p-type material of the multi-layer structure of device 1200. Other layers of the device may also be based on PDCn-type SiC wafers.

[0317] Example 19

[0318] 13 shows a cross-sectional schematic diagram of a SiC IGBT device 1300. The device 1000 is based on a p-type wafer cut from a p-type boule that forms a p-substrate layer, as well as other p-type materials in the multi-layer structure of the device 1300. Other layers of the device may be based on PDCn-type SiC wafers.

[0319] Example 20

[0320] In FIG. 14, a cross-sectional schematic of a SiC CMOS compound device 1400 is shown. The device 1400 is based on a p-type wafer cut from a p-type boule that forms the p-substrate layer in the multi-layer and component structure of the device 1400. Here, PMOS and NMOS devices are built on a common p-type substrate based on a p-type wafer cut from a p-type boule. Shallow trench isolation (ST) provides electrical isolation between the devices. Multiple levels of metal lines are routed to interconnect the devices to form the circuits on the chip. Capacitors, resistors, and inductors can also be incorporated into the composite device 1400.

[0321] Example 21

[0322] 15 shows a cross-sectional schematic diagram of a SiC flash memory device 1500. Prior to the present invention, it was believed that it was not possible to fabricate a flash memory device from SiC. The SiC flash memory device 1500 has a line source 1501, a bit line 1502, a world line control gate 1503, a float gate 1504, an n-type SiC component 1505, a second n-type SiC component 1506, and a p-type layer 1507, which is based on a p-type wafer cut from a p-type boule.

[0323] Example 22

[0324] An embodiment of a SiC CMOS composite device 1600 is shown in Figure 16. Such a device can function as an analog and mixed signal device. The device has a p-type substrate layer based on a p-type wafer cut from a p-type boule.

[0325] Example 23

[0326] Low resistivity SiC wafers offer key advantages when manufacturing devices, such as eliminating the need for costly processing steps such as polishing and thinning the SiC substrate, while minimizing and ideally eliminating the need for any circuit design changes.

[0327] Example 24

[0328] Lower resistivity SiC wafers, with resistivity between 1 and 5 milliohm·cm.

[0329] Example 25

[0330] Nitrogen is much smaller than silicon. Therefore, it is theorized that smaller impurity atoms are more likely to occupy carbon sites in the crystal, while larger impurity atoms are more likely to occupy silicon sites. During SiC crystal growth, nitrogen can occupy either the Si or C sites in the crystal, or both.

[0331] Typically, doped SiC wafers contain 100-1,000 ppm of nitrogen dopant. The theory is that only 1 in 100 nitrogen atoms supplied during growth is absorbed into the crystal and becomes an electrically active atomic impurity. Thus, the source must be much higher than the desired dopant level. (The "absorption" of a dopant into the lattice is known as site competition). However, there is a limit to how much nitrogen can be put into the crystal, and too much will distort the crystal and cause stress. In the past, doping with high concentrations of nitrogen to reduce resistivity has resulted in a large number of stacking faults and other crystal quality defects that have adversely affected epitaxy and device performance. Phosphorus is very close in size to a silicon atom. Thus, it is theorized that in the SiC crystal lattice, phosphorus substitutes for silicon (as opposed to nitrogen replacing carbon), greatly reducing the stress introduced (and also reducing defects, since defect formation is caused by stress within the crystal). Therefore, based on the dopants required, it is theorized that the preferred amount of phosphorus-based dopant is less than 10% of the nitrogen-based dopant required in the raw material to produce phosphorus-based doped n-type SiC wafers. In a preferred embodiment, the process introduces more than 1% of the phosphorus from the raw material into the SiC crystal as an electrically active atomic impurity.

[0332] Example 26

[0333] In the sublimation process for growing SiC crystals, there is usually more Si vapor than C vapor, making it easier to incorporate nitrogen, but at the same time, the high concentration of Si vapor makes it unsuitable for incorporating aluminum or boron to create p-type materials. It is said that one in every 100 atoms of nitrogen or phosphorus is incorporated as a dopant, while only one in every 1,000 atoms of boron or aluminum is incorporated.

[0334] Therefore, for effective incorporation, it is believed that it is desirable for the doping source to have a vapor pressure equal to or greater than that of silicon. Aluminum has a higher vapor pressure than silicon, making it a suitable dopant for p-type wafers. Aluminum and silicon are adjacent to each other in the periodic table (they are essentially atoms of the same size).

[0335] Example 27

[0336] Conventional 4H silicon carbide p-type material, grown as an epitaxial layer on a substrate (typically n-type SiC), has been available for fabricating n-channel IGBTs, but has generally lacked both the quality and conductivity to operate well in an IGBT, and in particular, to operate as a commercially acceptable IGBT. The present invention specifically addresses and solves this problem by providing p-type SiC wafers that are cut from p-type SiC boules, which provide the ability to fabricate commercially acceptable and operational SiC IGBT devices.

[0337] Example 28

[0338] There has been a long-standing need for SiC LDMOSFETS (lateral metal-oxide-semiconductor field effect transistors). These devices were developed in silicon for high power applications such as cellular and UHF broadcast transmission, and are increasingly needed because silicon LDMOSFETS offer higher gain and better linearity than bipolar devices. However, prior to the present invention, devices of this design or type could not be fabricated in or based on SiC because only n-type SiC substrates existed and historically p-type epitaxially molded SiC substrates have too high a resistivity compared to silicon, leading to undesirable LDMOSFET device performance. The present invention specifically addresses and solves this problem by providing p-type SiC wafers, which are cut from p-type SiC boules, providing the ability to fabricate commercially acceptable and operational SiC LDMOSFET devices.

[0339] Example 29

[0340] A polysiloxane precursor composition having one or more dopants with a predetermined amount of acceptor impurity atoms and a predetermined amount of donor impurity atoms, the SiC source material having a predetermined amount of acceptor and donor impurity atoms and thus a predetermined ratio of acceptor and donor impurity atoms that provides a predetermined Nc value for doped SiC grown from the source material.

[0341] Example 30

[0342] In polysilocarb precursor embodiments, Si-OH functional siloxanes and silanes are utilized to incorporate Al-OH, P-OH, or B-OH functional groups without generating hydrogen. Exemplary reactions are shown below:

[0343] ~Si-OH + ~B-OH → ~Si-OB~ + H2O

[0344] Example 31

[0345] SiC IGBTs with a withstand voltage of 10kV or more, or 100kV or more.

[0346] Example 32

[0347] A medium voltage SiC IGBT with a withstand voltage of approximately 2kV.

[0348] Example 33

[0349] 4 inch (100 mm) p-type SiC wafer. Polytype 4H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.015-0.028Ω·cm.

[0350] Example 34

[0351] 4 inch (100 mm) low resistivity p-type SiC wafer. Polytype 4H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0352] Example 35

[0353] 6 inch (150 mm) p-type SiC wafer. Polytype 6H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.015-0.028Ω·cm.

[0354] Example 36

[0355] 6 inch (150 mm) low resistivity p-type SiC wafer. Polytype 6H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0356] Example 37

[0357] 4 inch (100 mm) p-type SiC wafer. Polytype 4H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 Wafer N A is 10 18 / cm 3 About 10 19 / cm 3 .

[0358] Example 38

[0359] 6 inch (150 mm) p-type SiC wafer. Polytype 4H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 Wafer N A is 10 18 / cm 3 About 10 19 / cm 3 .

[0360] Example 39

[0361] 6 inch (150 mm) p-type SiC wafer. Polytype 6H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 Wafer N A is 10 18 / cm 3 About 10 19 / cm 3 .

[0362] Example 40

[0363] 4 inch (100 mm) p-type SiC wafer. Polytype 4H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm-2 Wafer N A 10 18 / cm 3 ~about 10 19 / cm 3 .

[0364] Example 41

[0365] 4 inch (100 mm) p-type SiC wafer. Polytype 6H. Dopant Al. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 Wafer N A is 10 18 / cm 3 About 10 19 / cm 3 .

[0366] Example 42

[0367] 4 inch (100mm) low resistivity n-type SiC wafer. Polytype 4H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0368] Example 43

[0369] 4 inch (100 mm) low resistivity p-type SiC wafer. Polytype 6H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(average of 10mmx10mm)<4μm. MPD(micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0370] Example 44

[0371] 6 inch (150 mm) low resistivity n-type SiC wafer. Polytype 4H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0372] Example 45

[0373] 6 inch (150 mm) low resistivity p-type SiC wafer. Polytype 6H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0374] Example 46

[0375] 4 inch (100mm) low resistivity n-type SiC wafer. Polytype 4H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0376] Example 47

[0377] 4 inch (100 mm) low resistivity p-type SiC wafer. Polytype 6H. Dopant p. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0378] Example 48

[0379] 6 inch (150 mm) low resistivity n-type SiC wafer. Polytype 4H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm.

[0380] Example 49

[0381] 6 inch (150 mm) low resistivity p-type SiC wafer. Polytype 6H. Dopant P. Orientation <0001> + / -0.5 degree. Thickness 325-500μm. Bow<40μm. Warp<60μm. TTV<15μm. SBIR(LTV)(10mmx10mm average)<4μm. MPD(Micropipe)<0.2cm -2 TSD (threading screw dislocation density) <500cm -2 BPD (basal plane dislocation) <500cm -2 . Resistivity 0.010-0.003Ω·cm. Heading and embodiment

[0382] It should be understood that the use of headings in this specification is for clarity and is not limiting in any sense. Thus, the processes and disclosures described under the headings should be read in the context of the entire specification, including the various examples. The use of headings in this specification should not limit the scope of protection of the invention.

[0383] It should be noted that it is not necessary to provide or address the theory underlying any novel and innovative process, material, performance, or other beneficial features and characteristics that are the subject of or related to the embodiments of the present invention. Nevertheless, various theories are provided herein to further advance the art in this area. These theories presented herein are in no way intended to limit, restrict, or narrow the scope of protection afforded to the claimed inventions unless expressly stated otherwise. These theories are not required or implemented in order to utilize the present invention. Furthermore, it should be understood that the present invention may lead to new, previously unknown theories to explain the function-characteristics of the embodiments of the methods, articles, materials, devices, and systems of the present invention, and that such subsequently developed theories shall not limit the scope of protection afforded to the present invention.

[0384] The various examples of formulations, compositions, articles, plastics, ceramics, materials, parts, wafers, boules, volumetric structures, uses, applications, devices, methods, activities, and operations described herein can be used in a variety of other fields and in a variety of other activities, applications, and examples. Furthermore, these examples can be used with existing systems, articles, compositions, materials, operations, or activities, and with systems, articles, compositions, materials, operations, or activities that may be developed in the future, and with such systems, articles, compositions, materials, operations, or activities that may be modified based on the teachings herein. Furthermore, the various embodiments and examples described herein can be used with each other in whole or in part, and in various different combinations. Thus, for the examples, the configurations provided in the various embodiments herein can be used with each other. For the examples, the components of the examples having A, A', and B, and the components of the examples having A", C, and D can be used with each other in various combinations, such as A, C, D, and A, A", C, and D, in accordance with the teachings herein. Therefore, the scope of protection given to the present invention should not be limited to the specific embodiments, configurations, or arrangements set forth in the specific embodiments, examples, or embodiments of the specific figures.

[0385] The present invention may be embodied other than as specifically disclosed herein without departing from its spirit or essential characteristics, The described embodiments are to be considered in all respects only as illustrative and not restrictive.

Claims

1. A doped polysilocarb precursor material for use in the manufacture of doped SiC crystals, a) a dopant having a number of donor atoms, a number of acceptor atoms, or both, b) silicon, carbon, and oxygen, and c) the dopant is present in a weight of about 10% or less of the total weight of the doped polysilocarb precursor material, d) the dopant is covalently bonded to at least one of silicon, carbon, and oxygen, e) the doped polysilocarb precursor material defines a potential net carrier concentration (pNc), where pNc = number of donor atoms - number of acceptor atoms, The doped polysilocarb precursor material.

2. The doped polysilocarb precursor material according to claim 1, wherein the pNc is positive.

3. The doped polysilocarb precursor material according to claim 2, having at least 1×10 １８ more donor atoms than acceptor atoms.

4. The number of the acceptor atoms is less than 1×10 １４ The doped polysilocarb precursor material according to claim 3, wherein the number is less than 1×10

5. The number of the acceptor atoms is less than 1×10 １０ The doped polysilocarb precursor material according to claim 3, wherein the number of the acceptor atoms is less than 1×10

6. The doped polysilocarb precursor material according to any one of claims 1 to 5, wherein the donor atom is selected from one or more elements of Group 15 of the periodic table.

7. The doped polysilocarb precursor material according to any one of claims 1 to 5, wherein the donor atom contains phosphorus.

8. The doped polysilocarb precursor material according to any one of claims 1 to 5, wherein the donor atom consists essentially of phosphorus.

9. The donor atom contains phosphorus, the covalent bond is formed with phosphorus, and the polysilocarb precursor material further comprises a) -Si-O-P-R (where R is an alkyl group, a phenyl group, or a styrenyl group), and b) -Si-C-C-P-R (where R is an alkene group, a styrenyl group, an alkyl group, or a phenyl group), c) (~Si - O) ３ -P = O, and The doped polysilocarb precursor material according to any one of claims 1 to 5, which contains one or more of these.

10. The doped polysilocarb precursor material according to claim 1, wherein the polysilocarb precursor material is a solid material that has cured.

11. The doped polysilocarb precursor material according to claim 1, wherein the pNc is negative.

12. At least 1 × 10 more acceptor atoms than donor atoms １８ The doped polysilocarb precursor material according to claim 11, having acceptor atoms.

13. The number of the donor atoms is less than 1×10 １４ The doped polysilocarb precursor material according to claim 12, wherein the number is less than 1×10

14. The number of the donor atoms is less than 1×10 １０ The doped polysilocarb precursor material according to claim 12, wherein the number is less than 1×10

15. The doped polysilocarb precursor material according to claim 11, wherein the acceptor atom is selected from one or more elements of Group 13 of the periodic table.

16. The doped polysilocarb precursor material according to any one of claims 1 and 11 to 15, wherein the acceptor atom contains boron.

17. The doped polysilocarb precursor material according to any one of claims 11 to 15, wherein the acceptor atom consists essentially of boron.

18. The doped polysilocarb precursor material according to any one of claims 1 and 11 to 15, wherein the acceptor atom contains aluminum.

19. The doped polysilocarb precursor material according to any one of claims 11 to 15, wherein the acceptor atom consists essentially of aluminum.

20. The doped polysilocarb precursor material according to any one of claims 11 to 15, wherein the acceptor atom contains aluminum and the polysilocarb precursor material does not contain an alloy, whereby it is alloy-free.

21. The doped polysilocarb precursor material according to any one of claims 11 to 15, wherein the acceptor atom consists essentially of aluminum and the polysilocarb precursor material does not contain an alloy, whereby it is alloy-free.

22. The doped polysilocarb precursor material according to claim 1, which does not contain an alloy, whereby it is alloy-free.

23. The acceptor atom contains aluminum, the covalent bond is formed with aluminum, The polysilocarb precursor material further a) 2Al-(O-Si~) ３ and b) 2Al-(O-Si~) ３ and c) Al ２ O ３ and contains one or more of

24. The acceptor atom contains boron, the covalent bond is formed with boron, The polysilocarb precursor material further a) 2B-(O-Si~) ３ and b) B-C-C-Si~ and contains one or more of, the doped polysilocarb precursor material according to any one of claims 1, 11 to 15, and 22.

25. The doped polysilocarb precursor material according to claim 11, which is a cured solid material.

26. A liquid doped polysilocarb precursor material for use in the production of p-type SiC crystals, a) a dopant containing one or more elements selected from Group 13 elements of the periodic table, the selected element providing a certain number of acceptor atoms, b) silicon, carbon, and oxygen, and c) the dopant is present in a weight less than 10% of the total weight of the liquid-doped polysilocarb precursor material, d) the liquid-doped polysilocarb precursor material defines a negative potential net carrier concentration (pNc), where pNc = number of donor atoms - number of acceptor atoms, of the liquid-doped polysilocarb precursor material. **Claim 27** The liquid-doped polysilocarb precursor material according to claim 26, wherein the dopant is present in a weight less than 8% of the total weight of the liquid-doped polysilocarb precursor material. **Claim 28** The liquid-doped polysilocarb precursor material according to claim 26, wherein the dopant is present in a weight less than 3% of the total weight of the liquid-doped polysilocarb precursor material. **Claim 29** The liquid-doped polysilocarb precursor material according to any one of claims 26 to 28, wherein the acceptor atom contains boron. **Claim 30** The liquid-doped polysilocarb precursor material according to any one of claims 26 to 28, wherein the acceptor atom consists essentially of boron. **Claim 31** The liquid-doped polysilocarb precursor material according to any one of claims 26 to 28, wherein the acceptor atom contains aluminum. **Claim 32** The liquid-doped polysilocarb precursor material according to any one of claims 26 to 28, wherein the acceptor atom consists essentially of aluminum. **Claim 33** The liquid-doped polysilocarb precursor material according to any one of claims 26 to 28, wherein the acceptor atom contains aluminum and the polysilocarb precursor material does not contain an alloy, whereby it is alloy-free. **Claim 34** The liquid-doped polysilocarb precursor material according to any one of claims 26 to 28, wherein the acceptor atom consists essentially of aluminum and the polysilocarb precursor material does not contain an alloy, whereby it is alloy-free. **Claim 35** The liquid-doped polysilocarb precursor material according to claim 26, which does not contain an alloy, whereby it is alloy-free. **Claim 36** A liquid-doped polysilocarb precursor material for use in the manufacture of low-resistance n-type SiC crystals, a) a dopant comprising one or more elements selected from Group 15 elements of the periodic table, the selected element providing a certain number of donor atoms, b) comprising silicon, carbon, and oxygen; c) the dopant being present in a weight less than 10% of the total weight of the liquid-doped polysilocarb precursor material; d) the liquid-doped polysilocarb precursor material defining a positive potential net carrier concentration (pNc), where pNc = number of donor atoms - number of acceptor atoms, the liquid-doped polysilocarb precursor material. **Claim 37** The liquid-doped polysilocarb precursor material according to claim 36, wherein the dopant comprises phosphorus. **Claim 38** The liquid-doped polysilocarb precursor material according to claim 36, wherein the selected element comprises phosphorus. **Claim 39** The liquid-doped polysilocarb precursor material according to claim 36, wherein the selected element consists essentially of phosphorus. **Claim 40** The doped polysilocarb precursor material according to any one of claims 1 to 5, 10 to 15, 22, 25 to 28, and 35 to 39, wherein the weight percentage of the dopant is from about 2% to about 5%. **Claim 41** The doped polysilocarb precursor material according to any one of claims 1 to 5, 10 to 15, 22, 25 to 28, and 35 to 39, wherein the weight percentage of the dopant is less than about 5%. **Claim 42** The doped polysilocarb precursor material according to any one of claims 1 to 5, 10 to 15, 22, 25 to 28, and 35 to 39, wherein the weight percentage of the dopant is from about 1% to about 5%.