Managing growth of silicon carbide crystal

Abstract

To provide a method and apparatus for growing silicon carbide (SiC) crystals.SOLUTION: A physical vapor transport (PVT) apparatus for growth of silicon carbide (SiC) ingots can be improved by incorporating a moveable source. During growth of the ingot, the shape of the growth interface can be maintained as a convex shape by keeping a substantially constant distance between the growth interface and the source material. It is shown that temperature gradients during the growth phase are also influenced by the shape of the growth interface. By moving the source during crystal growth, the resulting SiC ingot can be taller with fewer defects, and can be less likely to crack during subsequent grinding or polishing operations.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This patent application claims the benefit of U.S. Patent Application No. 18 / 738,193, entitled "Managing the Growth of Silicon Carbide Crystals," filed June 10, 2024, which is incorporated herein by reference in its entirety.

[0002] FIELD OF THE INVENTION This specification relates to methods and apparatus for growing silicon carbide (SiC) crystals for use in the electronics industry. More particularly, this specification relates to controlled SiC crystal growth in a physical vapor transport (PVT) furnace. [Background technology]

[0003] Silicon carbide can be used as an alternative substrate material to silicon in the manufacture of integrated circuits. Some useful properties of SiC-based microchips, such as metal-oxide-semiconductor field-effect transistors (MOSFETs), include reduced weight, low power consumption, and the ability to sustain high-temperature operation. While silicon devices operate at temperatures up to approximately 120°C, SiC devices can operate at temperatures as high as 500°C–800°C. This is due to SiC's high thermal conductivity, which is approximately 3.5 times higher than that of silicon. Therefore, SiC devices are particularly suitable for power applications such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and solar panels, as well as industrial applications. SiC devices are being introduced into EV production in vehicle components such as DC-DC converters and on-board fast battery chargers. Summary of the Invention

[0004] In some aspects, the techniques described herein relate to an apparatus that includes a crucible having an upper region and a lower region, a silicon carbide (SiC) precursor disposed within a movable source capsule in the lower region, a SiC seed disposed in the upper region, and an induction heating coil surrounding at least a portion of a sidewall of the crucible.

[0005] In some aspects, the techniques described herein relate to a system that includes a process chamber for growing SiC crystals, a movable SiC source capsule disposed within the process chamber, a heater disposed around a side of the process chamber, and a controller configured to control the position of the movable SiC source capsule.

[0006] In some aspects, techniques described herein relate to a method of forming silicon carbide, the method including disposing a SiC precursor in a movable source capsule in a lower region of a crucible, disposing SiC seeds in a stationary seed module in an upper region of the crucible, heating the source capsule, forming SiC crystals by condensing SiC on surfaces of the SiC seeds, and moving the source capsule relative to the stationary seed module while forming the SiC crystals. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a physical vapor transport (PVT) device according to an implementation of the present disclosure. [Figure 2] FIG. 1 is a detailed cross-sectional view of a physical vapor transport (PVT) device according to an implementation of the present disclosure. [Figure 3] FIG. 1 is a detailed cross-sectional view of a physical vapor transport (PVT) device according to an implementation of the present disclosure. [Figure 4A] FIG. 1 is a side view of a crystal boule according to an implementation of the present disclosure. [Figure 4B] 1 is an example of a convex growth interface according to an implementation of the present disclosure. [Figure 4C] 1 is an example of a convex growth interface according to an implementation of the present disclosure. [Figure 5A] 1 is a simulated temperature profile of a SiC boule with a convex growth interface. [Figure 5B] 1 is a simulated temperature profile of a SiC boule having a substantially flat growth interface. [Figure 5C] 1 is a simulated temperature profile of a SiC boule with a concave growth interface. [Figure 6] 1A and 1B are cross-sectional views of a PVT apparatus illustrating the effect of source motion on temperature gradients during a simulated crystal growth process, according to an implementation of the present disclosure. [Figure 7] 1A-1C are cross-sectional views of a PVT apparatus illustrating the effect of source motion on growth interface shape during a simulated crystal growth process, according to an implementation of the present disclosure. [Figure 8] FIG. 1 is a flow diagram illustrating a method of forming a SiC boule according to an implementation of the present disclosure. [Figure 9] FIG. 8 is a system block diagram of a computer system capable of providing feedback control to the process shown in FIG. 7 according to a possible implementation of the present disclosure.

[0008] Aspects of the present disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, according to common practice in the industry, various features have not necessarily been drawn to scale. Dimensions of various features may be arbitrarily increased or decreased for clarity of illustration. In the drawings, the same reference numbers in different views may indicate the same and / or similar components (elements, structures, etc.). The drawings generally illustrate various implementations discussed in the present disclosure, by way of example, and not by way of limitation. Reference numbers shown in one drawing may not be repeated for the same and / or similar elements in associated figures. Reference numbers repeated in multiple drawings may not be specifically discussed with respect to each of those drawings, but are provided for context between the associated figures. Also, when multiple examples of an element are shown, not all of the same elements in the drawings are specifically referred to with a single reference number. DETAILED DESCRIPTION OF THE INVENTION

[0009] Silicon carbide ingots used in the manufacture of integrated circuits can be grown in a physical vapor transport (PVT) furnace. A PVT furnace can have the form of a vertical cylindrical chamber, or crucible, with a seed crystal at one end. The crucible can receive silicon and carbon source materials, which are heated until they vaporize. The resulting silicon and carbon gases rise within the chamber, and when they encounter the seed crystal, they crystallize around the seed crystal, causing crystal growth radially outward and axially downward. Such crystal growth forms a cylindrical boule that can be subsequently sliced ​​into SiC wafers used as substrates in semiconductor manufacturing processes.

[0010] Process control during SiC crystal growth is challenging. At least one problem encountered during the crystal growth process is the continuous change in the distance between the crystallization surface of the growing crystal and the source zone as the boule extends downward from the seed crystal. As growth progresses, the growing crystal approaches the source zone due to the advancement of the solid-gas interface. As a result, the length of the boule is limited because the distance available for expansion is constantly shrinking. Meanwhile, the shape of the crystal growth interface changes from convex to flat to concave as the growth interface moves downward. Such changes in interface shape and the associated temperature profile can cause variations in the growth rate and quality of the crystal; for example, dislocation defects may form in the crystal structure. To minimize dislocation density within the boule, it may be desirable to control the crystal-gas interface to maintain a convex shape throughout the growth process. In addition, maintaining an isothermal temperature profile at the growth interface can help produce boules with uniform, defect-free crystal structures.

[0011] At least one way to control the interface shape and temperature isotherm at the crystal growth interface is to move the source or seed to compensate for the moving crystallization interface and thus maintain a constant distance between them. Additionally, if a coil heater (e.g., an RF coil heater) is disposed at one or both ends of the crucible, it may be possible to maintain the desired temperature isotherm by moving the coil relative to the hot zone instead of moving the source or seed. (This approach is the subject of another patent application from the same inventor as this patent application.) However, moving the heater does not change the distance between the source and seed and therefore may not address the interface shape. Moving the seed appears to be a simpler and more straightforward option. However, if the device monitoring the seed temperature is fixed in a position adjacent to the seed, temperature measurements will be inaccurate if the seed position changes. Unfortunately, placing a temperature detector on the growing crystal itself may not be practical. With these considerations in mind, a technique for controlling crystal growth by moving the source is described below.

[0012] 1 shows a cross-sectional view of a PVT furnace 100 according to some implementations of the present disclosure. In some implementations, the PVT furnace 100, e.g., a sublimation furnace, can include an outer shell 102, a crucible 105, a seed crystal 106, a movable source 108, and a heater 112.

[0013] In some implementations, the outer shell 102 can be a multi-layered cylindrical structure including an outer chamber wall 103 and an insulating sleeve 104 outside the crucible 105. In some implementations, the crucible 105 can be an enclosed vessel defining a growth cell 107. The growth cell 107 can be evacuated so that the SiC boule can be grown in a high-purity, low-pressure environment. In some implementations, the outer chamber wall 103 can be made of quartz, the insulating sleeve 104 can be made of low-density graphite, and the crucible 105 can be made of high-density graphite. Because graphite is a high conductor of both heat and electricity, the graphite material supports inductive heating of the crucible 105 surrounding the growth cell 107.

[0014] In some implementations, the SiC seed crystal 106 can be attached to a seed module suspended from the top of the crucible 105. In some implementations, the SiC seed crystal 106 can have a z-thickness of about 1 mm. In some implementations, a pyrometer can be attached adjacent to the seed crystal 106 to monitor the temperature of the seed crystal 106.

[0015] In some implementations, a gap 109 may separate the outer chamber wall 103 from the insulating sleeve 104. In some implementations, the width of the gap 109 may range from about 3 mm to about 7 mm. In some implementations, another inert gas, such as nitrogen gas (N), may be used instead of air in the gap 109.

[0016] In some implementations, the heater 112 can be disposed around the outer shell 102, e.g., the sidewall, of the crucible, outside the "hot zone." In some implementations, the heater 112 can take the form of a stationary RF induction coil that wraps around the outer shell 102 and surrounds the sidewall of the crucible 105, the coil wraps being represented by circles in FIG. 1 . The induction coil of the heater 112 induces a current to flow within the crucible 105. In some implementations, the heater 112 can be considered a horizontal heating element because it affects a temperature gradient in the xy plane along the z-axis, i.e., the radial plane.

[0017] In the PVT furnace 100, the SiC source material can be disposed in a lower region of the crucible 105, while the seed crystal 106 is disposed in an upper region of the crucible 105. In some implementations, the SiC source material, e.g., a SiC precursor, can be in the form of a powder having a 1:1 silicon-to-carbon ratio. The SiC source material can be contained within a source capsule of the movable source 108. In some implementations, the movable source 108 can be in the form of a donut-shaped (or toroidal) source capsule, which excludes the center of the crucible 105, which is furthest from the heater 112, allowing the heater 112 to maintain a substantially uniform temperature. Using the heater, the crucible 105 can be heated to a temperature ranging from about 1800°C to about 2500°C until the solid SiC source material sublimes to form a gas 110. The gas 110 rises within the growth cell 107 toward the seed crystal 106, which is at a lower temperature than the gas 110. When the gas 110 encounters the seed crystal 106, the gas 110 condenses on the side and bottom opposing surfaces of the seed crystal 106, causing crystal growth to proceed radially outward from the seed crystal 106 and axially downward in the -z direction. The movable source 108 can translate downward as the crystal boule grows within the growth cell 107 to maintain a substantially constant distance d between the source zone, e.g., the movable source 108, and the crystal growth interface. In some implementations, it may be desirable for the distance d to correspond to the growth of an ingot having a final length of at least about 60 mm, e.g., in the range of about 55 mm to about 65 mm, so that multiple wafers can be produced from the ingot. In some implementations, the movable source 108 can move in response to the expansion or contraction of material within the source capsule. For example, smart materials can be used to construct the source capsule and / or crucible 105 to expand and contract with temperature changes. Thus, the top surface of the movable source 108 can contract as the boule grows to maintain a substantially constant distance d and a substantially constant temperature difference between the source and the boule.

[0018] 2 and 3 show close-up views of the PVT furnace 100, according to some implementations of the present disclosure. 2 and 3 further illustrate details of the PVT furnace 100 with respect to the movable source 108. In particular, 2 and 3 show a motive device that can be used to adjust the position of the movable source capsule relative to the SiC ingot during growth of the SiC ingot.

[0019] 2 shows a minimal example in which the movable source 108 can be moved up and down inside the closed graphite crucible 105 by a first drive assembly 202 attached to the movable source 108. The first drive assembly 202 can be configured for one-dimensional, e.g., vertical translational, movement of the movable source 108. In some implementations, the first drive assembly 202 can include a rigid connector 204, a central drive shaft 206, and a drive motor 208. The rigid connector 204 can be attached to the movable source 108, e.g., to a lower surface of the movable source 108. The rigid connector 204 can be configured to couple the movable source 108 to the central drive shaft 206. In some implementations, the central drive shaft 206 extends through the sealed bottom wall of the crucible 105 to the drive motor 208. In some implementations, the drive motor 208 can be rotatably coupled to the drive shaft 206 such that rotation of the drive motor 208 causes vertical translation of the drive shaft 206 and rigid connector 204 along a central z-axis, thereby changing the vertical position of the movable source 108.

[0020] 3 illustrates an example in which a second drive assembly 302 coupled to the movable source 108 can move the movable source 108 up and down within a closed graphite crucible 105. Similar to the first drive assembly 202, the second drive assembly 302 can be configured for one-dimensional, e.g., vertical translational, movement of the movable source 108. In some implementations, the second drive assembly 302 can include a rigid connector 204, a central drive shaft 206, and an elevation mechanism 308, such as a scissor jack, screw jack, inflatable jack, floor jack, or other type of equipment elevation device, that can be disposed below the crucible 105. The rigid connector 204 can be attached to the movable source 108, e.g., to an underside of the movable source 108. The rigid connector 204 can be configured to couple the movable source 108 to the central drive shaft 206. In some implementations, the central drive shaft 206 extends through the sealed bottom wall of the crucible 105 and couples with an elevator mechanism 308. In some implementations, the elevator mechanism 308 can be secured to the drive shaft 206, for example, by tightening a coupling ring 310. The expansion and contraction of the elevator mechanism 308 can be controlled by turning a screw 312. Raising and lowering the elevator mechanism 308 then causes vertical translation of the drive shaft 206 and rigid connector 204 along the central z-axis, thereby changing the vertical position of the movable source 108.

[0021] 4A-4C are side views of crystal growth according to some implementations of the present disclosure. FIG. 4A shows a crystal isotropically grown outward from a seed crystal 106 in the direction of the arrow perpendicular to a dome-shaped solid-gas interface 402a. In some implementations, the solid-gas interface 402a initially forms a convex surface, e.g., a dome, that changes over time as the boule grows. FIG. 4B shows a highly convex interface 402b characterized by high thermoelastic stress, which provides good polytype stability. The highly convex interface 402b represents the initial shape of the dome early in the growth cycle. FIG. 4C shows a slightly convex interface 402c, which is nearly flat and characterized by low thermoelastic stress with poor polytype stability, a crystalline form with specific unit cell dimensions. The slightly convex interface 402c represents the degraded shape of the dome later in the growth cycle. If the growth cycle is long enough, the shape of the interface can become completely flat or concave. A concave interface can result in polytype switching and instability. As shown in Figures 4A-4C and described below, it is desirable to maintain an interface shape similar to that shown in Figure 4B throughout the crystal growth time interval. By moving the source capsule downward as crystal growth progresses, a substantially constant distance can be maintained between the source and the solid-gas interface, maintaining a highly convex interface 402b throughout the growth cycle.

[0022] 5A-5C are simulation results showing isotherms for various shapes of crystal boules according to some implementations of the present disclosure. Each isotherm is a surface of constant temperature across the entire boule. Spatially uniform isotherms indicate temperature stability, which tends to result in a low defect density within the crystal. FIG. 5A is a plot 500 showing simulated isotherms 502 for the highly convex crystal shown in FIGS. 4A and 4B. FIG. 5B is a plot 510 showing simulated isotherms 512 for the slightly convex crystal shown in FIG. 4C. By comparing isotherms 502 to 512, it is clear that the width of isotherms 502 for the highly convex crystal is more uniform across the boule in both the + / -x and + / -z directions than the width of isotherms 512 for the slightly convex crystal, and therefore more desirable. FIG. 5C is a plot 520 showing simulated isotherms 522 for a concave crystal. The isotherm 522 is shown to be severely distorted, indicating significant temperature variations across the boule in both the + / -x and + / -z directions. Figures 5A-5C demonstrate that avoiding concave interfaces is important for producing high quality SiC crystals.

[0023] FIG. 6 is a cross-sectional view of a PVT furnace 100, illustrating the effect of source movement on temperature, according to some implementations of the present disclosure. The crucible 105 is heated to a temperature of approximately 2200°C by a heater 112, e.g., a high-frequency induction heater. Because the crucible is made of graphite, which is an excellent conductor of heat and electricity, the temperature of the crucible quickly reaches equilibrium, and therefore the temperature of the crucible is approximately the same on all sides. Temperature contours 600 are shown on the left when the movable source 108 is in its uppermost position adjacent to the crystal boule and on the right when the movable source 108 is in its lowermost position, a maximum distance d=60 mm from the crystal growth interface. The temperature contours appear to be equivalent on both sides of the crucible 105 and on both sides of the crystal boule. T2 represents the source temperature, and T1 represents the seed temperature at the growth interface. The difference T2-T1 is measured to be in the range of approximately 28°C to approximately 30°C on both sides of the growth cell 107. Thus, there is essentially no difference between the temperature profiles on the left and right, indicating that the axial temperature gradient is maintained by moving the source. As a result, the crystal growth rate remains unchanged by the source motion.

[0024] FIG. 7 is a side view of a crystal boule illustrating the effect of source movement on the crystal's growth interface shape, according to some implementations of the present disclosure. A series of simulated shape profiles 700 of the growth interface are shown for an "up" source position on the left and for a "down" source position on the right. The growth front is shown at the beginning 702, middle 704, and final 706 stages of crystal growth. The series of shape profiles 700 shows that the shape of the growth interface remains convex for both extreme source positions at all stages of crystal growth. Thus, varying the position of the movable source 108 to maintain a constant distance d from the surface of the boule easily maintains the desired convex shape of the growth interface.

[0025] FIG. 8 is a flow diagram illustrating a method 800 for forming a SiC boule according to some implementations of the present disclosure. Operations 802-812 of method 800 can be performed to form a SiC boule according to some implementations such as those described above with reference to FIGS. 1, 2, 3, 4A, 4B, 4C, 5A, 5B, 5C, 6, and 7. The operations of method 800 can be performed in a different order or not at all, depending on the particular application. Note that method 800 may not completely form a SiC boule. Thus, it should be understood that additional processes may be provided before, during, or after method 800, and that some of these additional processes may be briefly described herein.

[0026] At 802, the method 800 includes providing a crucible, such as the crucible 105, for a sublimation furnace, such as the PVT furnace 100. In some implementations, the crucible 105 can have an upper region and a lower region.

[0027] At 804 , the method 800 includes disposing a SiC precursor in a movable source capsule within a lower region of the crucible 105 .

[0028] At 806 , the method 800 includes disposing a SiC seed crystal, for example, seed crystal 106 , in a stationary seed module suspended in an upper region of the crucible 105 .

[0029] At 808, the method 800 includes heating the crucible 105, for example using the heater 112, to sublimate the SiC precursor.

[0030] At 810, the method 800 includes growing a crystalline SiC ingot or boule by condensing SiC onto the surface of a SiC seed.

[0031] At 812, the method 800 includes growing a crystalline SiC ingot or boule using a movable source 108 to control temperature gradients during the growth process. By continuously retracting the movable source 108 in the direction of crystal growth, a constant distance between the source and the solid-gas interface can be maintained to maintain a convex interface shape throughout the growth process. This can result in longer ingots with lower defect densities than can be obtained using a fixed source capsule.

[0032] FIG. 9 is a diagram of an exemplary computing system 900 capable of implementing various embodiments of the present disclosure. The computing system 900 can be any known computing system capable of performing the functions and operations described herein. For example, without limitation, the computing system 900 can provide a hardware platform for implementing the process control schemes described above. The computing system 900 can be used, for example, to perform one or more operations in the method 800 describing the exemplary method for forming a SiC ingot. In some implementations, the computing system 900 can function as a feedback control system for the PVT furnace. For example, the computing system 900 can be implemented as a controller coupled to the PVT furnace 100 that monitors one or more temperatures associated with the PVT furnace 100, e.g., using a pyrometer, and accordingly engages a motive device to move the source capsule as described above, providing enhanced process control during the crystal growth process and / or the post-annealing process.

[0033] The computing system 900 includes one or more processors (also referred to as central processing units, or CPUs), such as processor 904. Processor 904 is connected to a communications infrastructure or bus 906. The computing system 900 also includes input / output devices 903, such as a monitor, keyboard, and pointing device, that communicate with the communications infrastructure or bus 906 via an input / output interface 902. The processor 904 can receive instructions via the input / output device 903 to perform the functions and operations described herein, such as method 800 of FIG. 8 . For example, the processor 904 can be programmed to operate a driver device, such as drive assembly 202 or drive assembly 302, to adjust the position of the source capsule relative to the seed crystal while growing a SiC crystal boule or while performing an annealing process after completing growth of a SiC ingot. In some implementations, the processor 904 can be programmed to operate the driver device according to temperature measurements. In some implementations, the processor 904 can be programmed to engage the driver device according to a defined schedule. The computing system 900 also includes a primary or main memory 908, such as random access memory (RAM). The main memory 908 may include one or more levels of cache. The main memory 908 stores control logic (e.g., computer software) and / or data internally. In some embodiments, the control logic (e.g., computer software) and / or data may include one or more of the operations described above with respect to the method 800 of FIG. 8.

[0034] The computing system 900 may also include one or more secondary storage devices or secondary memories 910. The secondary memories 910 may include, for example, a hard disk drive 912 and / or a removable storage device or drive 914. The removable storage drive 914 may be a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, a tape backup device, and / or any other storage device / drive.

[0035] The removable storage drive 914 can interface with a removable storage unit 918. The removable storage unit 918 includes a computer-usable or readable storage device that stores computer software (control logic) and / or data. The removable storage unit 918 can be a floppy disk, magnetic tape, compact disk, DVD, optical storage disk, thumb drive, and / or any other computer data storage device. The removable storage drive 914 reads from and / or writes to the removable storage unit 918 in well-known fashion.

[0036] According to some embodiments, secondary memory 910 may include other methods, means, or other techniques for allowing computer programs and / or other instructions and / or data to be accessed by computing system 900. Such methods, means, or other techniques may include, for example, removable storage unit 922 and interface 920. Examples of removable storage unit 922 and interface 920 may include a program cartridge and cartridge interface (such as those found in video game devices), a removable memory chip (such as an EPROM or PROM) and associated socket, a memory stick and USB port, a memory card and associated memory card slot, and / or any other removable storage unit and associated interface. In some embodiments, secondary memory 910, removable storage unit 918, and / or removable storage unit 922 may include one or more of the operations described above with respect to method 800 of FIG. 8.

[0037] Computing system 900 may further include a communications or network interface 924. Communications interface 924 allows computing system 900 to communicate and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referred to as remote devices 928). For example, communications interface 924 may allow computing system 900 to communicate with remote devices 928 over communications path 926, which may be wired and / or wireless and may include any combination of a LAN, a WAN, the Internet, etc. Control logic and / or data may be transmitted to or received from computing system 900 via communications path 926.

[0038] The operations in the aforementioned embodiments may be implemented in a wide variety of configurations and architectures. Thus, some or all of the operations in the aforementioned embodiments, e.g., method 800 of FIG. 8, may be performed in hardware, software, or both. In some embodiments, a tangible apparatus or article of manufacture comprising a tangible computer-usable or readable medium having control logic (software) stored thereon is also referred to herein as a computer program product or program storage device. This includes, but is not limited to, a computing system 900, a main memory 908, a secondary memory 910, and removable storage units 918 and 922, as well as tangible articles of manufacture embodying any combination of the above. Such control logic, when executed by one or more data processing devices (e.g., computing system 900), causes such data processing devices to operate as described herein.

[0039] As mentioned above, the addition of a movable source capsule to a PVT system can assist in controlling SiC crystal formation. The benefits of tighter process control are primarily obtained by controlling the shape of the crystal growth interface and by reducing axial and radial temperature variations.

[0040] In the foregoing description, when an element, such as a layer, region, or substrate, is referred to as being on, connected to, electrically connected to, coupled to, or electrically coupled with another element, it will be understood that it can be directly disposed on, connected to, or coupled with the other element, or that one or more intervening elements may be present. Conversely, when an element is referred to as being directly on, directly connected to, or directly coupled with another element or layer, no intervening elements or layers are present. Throughout the detailed description of the present invention, the terms directly, directly connected, or directly coupled may not be used, but elements shown as being directly on, directly connected, or directly coupled may be referred to as such. The claims of this application may be amended to describe the example relationships described herein or shown in the figures.

[0041] As used herein, the singular can include the plural unless the context clearly dictates otherwise. Spatially relative terms (e.g., throughout, above, above, below, lower, underneath, lower, top, bottom, etc.) are intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the drawings. In some implementations, the relative terms above and below can include vertically above and vertically below, respectively. In some implementations, the term adjacent can include laterally adjacent or horizontally adjacent.

[0042] Some implementations may be implemented using various semiconductor processing and / or packaging technologies, such as, but not limited to, silicon (Si), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), and / or other types of semiconductor processing technologies associated with semiconductor substrates.

[0043] While certain features of the described implementations have been illustrated as described herein, those skilled in the art will now recognize numerous modifications, substitutions, changes, and equivalents. For example, features illustrated with respect to one implementation may, where appropriate, be included in other implementations. It will therefore be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the implementations. These have been presented by way of example only, and not limitation, and it will be understood that various changes in form and detail may be made. Any portions of the apparatus and / or methods described herein may be combined in any combination except mutually exclusive combinations. The implementations described herein may include various combinations and / or subcombinations of functions, components, and / or features of the different implementations described.

Claims

1. 1. An apparatus comprising: a crucible having an upper region and a lower region; a silicon carbide (SiC) precursor disposed within a movable source capsule within the lower region; a SiC seed disposed in the upper region; an induction heating coil surrounding at least a portion of the side wall of the crucible; a drive shaft and a drive motor configured to change the position of the movable source capsule; an elevator mechanism disposed below the movable source capsule, the elevator mechanism being configured to change the position of the movable source capsule; a smart material that can expand and contract with changes in temperature; a pyrometer configured to monitor a temperature adjacent the SiC seed.

2. the movable sauce capsule is donut-shaped, or The apparatus of claim 1 , wherein the crucible comprises graphite.

3. 1. A system comprising: a process chamber for growing a SiC crystal; a movable SiC source capsule disposed within the process chamber; a heater disposed around a side surface of the process chamber; a controller configured to control the position of the movable SiC source capsule.

4. The controller: a motive device configured to change the position of the movable SiC source capsule, the motive device including at least one of an elevator mechanism or a drive motor; a pyrometer configured to measure a temperature of the SiC crystal, the motive device being actuated in accordance with the temperature measurement; and and a processor programmed to engage the motive device in adjusting the position of the movable SiC source capsule relative to the SiC crystal during growth of the SiC crystal, and to engage the heater and the pyrometer in performing an annealing process after growing the SiC crystal.

5. 1. A method of forming silicon carbide, comprising: disposing a SiC precursor in a source capsule in a lower region of a crucible; disposing a SiC seed in a stationary seed module in an upper region of the crucible; heating the source capsule to sublimate the SiC precursor; forming a SiC crystal by condensing SiC on the surface of the SiC seed; moving the source capsule relative to the stationary seed module while forming the SiC crystal to maintain a convex profile of a growth interface of the SiC crystal; and measuring a temperature above the SiC seed using a pyrometer.

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