Plasma molding for diamond growth

Abstract

A system for growing diamond. The system includes a chemical vapor deposition reactor having a microwave chamber. The system further includes a single crystal seed configured to be positioned within the chamber. The system also includes a precursor gas. A microwave source is configured to energize the precursor gas to generate a plasma plume. An electromagnetic wave source of the system is configured to generate an inductive external field to adjust the position of the plasma plume within the chamber and / or to adjust the shape of the plasma plume.

Description

[Technical Field]

[0001] Priority This patent application claims priority from U.S. Provisional Patent Application No. 62 / 980,673, filed on February 24, 2020, entitled "PLASMA SHAPING FOR DIAMOND GROWTH", with John Ciraldo and Jonathan Levine-Miles listed as inventors, the disclosure of which is incorporated herein by reference in its entirety.

[0002] Field of the Invention Exemplary embodiments of the present invention generally relate to the formation of diamond on a substrate, and more specifically, exemplary embodiments of the present invention relate to plasma shaping for targeted diamond growth.

[0003] Background of the Invention Diamond is used in a variety of applications. For example, it may be used in the manufacture of integrated circuits or as a lens in laser systems. Diamond may also simply be used as a gemstone. However, there are many technical challenges in the manufacture of diamond.

[0004] Chemical vapor deposition (CVD) is a process of depositing a film of a material from the gas phase by decomposing chemical substances on the surface of a substrate. Most frequently, this process is thermally driven, but methods utilizing light and plasma are also used. Film deposition is controlled by chemical reactions.

[0005] Summary of Various Embodiments According to one embodiment of the present invention, a system grows a diamond. The system includes a chemical vapor deposition reactor having a microwave chamber. The system further includes a single crystal seed configured to be positioned within the chamber. The system also includes a precursor gas. A microwave source is configured to energize the precursor gas to generate a plasma plume. An electromagnetic source in the system is configured to generate a steering field for adjusting the position of the plasma plume within the chamber and / or for adjusting the shape of the plasma plume.

[0006] A microwave source emits microwave radiation. The microwave source may generate a first electric field that energizes a gas. The charged gas may include methane and hydrogen. The first electric field and the induced field may be at least partially superimposed. The electromagnetic source may include, among other things, a magnetic coil, a charged ring, and / or an electrically biased mechanical support.

[0007] The system may further include a mechanical support on which a single crystal seed is positioned. The system may further include multiple single crystal seeds formed from diamond. In addition, the system may include a deposition feedback system. The deposition feedback system is configured to determine the temperature of one or more seeds, measure the dimensions of one or more grown diamonds, and / or determine the shape of a plasma plume. As a result of the deposition feedback, the external field intensity and / or other properties of one or more electromagnetic sources may be adjusted.

[0008] According to another embodiment, the method generates a plasma plume in a chamber. The chamber is configured such that the plasma plume is unstable or metastable. Thus, the plasma plume moves between a first position and a second position. The method biases the plasma plume toward the first position.

[0009] The method may also involve providing a single crystal seed within a chamber. The chamber may be cylindrical. Carbon from the plasma plume is deposited onto the single crystal seed through a series of reactions to form diamond. In exemplary embodiments, the single crystal seed is positioned on a mechanical support. In some chambers, the first position is above the single crystal seed, and the second position is at the top of the chamber. However, other positions of the plasma plume are also possible.

[0010] The method may generate an electric field to bias the plasma plume. Additionally or alternatively, the method may generate a magnetic field to bias the plasma plume. Some embodiments generate a second magnetic field or a second electric field to modify the shape of the biased plasma plume.

[0011] In yet another embodiment, the method controls diamond growth. The method provides a single crystal seed in the growth environment. Energy is supplied to a carbon-containing gas to generate a plasma plume. The method creates an induced external field to adjust the deposition properties of the plasma plume.

[0012] The inductive external field is configured to alter the shape of the plasma plume. In an exemplary embodiment, the method alters the shape of the plasma plume boundary facing the seed to have a larger radius of curvature. Additionally or alternatively, the method may increase the deposition area by altering the shape of the plasma plume more broadly. The inductive external field may be generated by using one or more magnetic fields, electric fields, and / or electromagnetic fields.

[0013] According to one embodiment of the present invention, the position and / or shape of a plasma plume is used to grow a diamond. The method provides a single-crystal seed in a growth environment. The single-crystal seed is formed from diamond. The method generates a plasma plume by energizing a carbon-containing gas to deposit free carbon atoms onto the single-crystal seed. The method also creates an induced external field to modulate the carbon atom deposition properties of the plasma plume.

[0014] In some embodiments, the growth environment is located within a chemical vapor deposition chamber. Furthermore, the gas may contain methane. The carbon atom deposition properties of the plasma plume may be regulated by changing the shape of the plasma plume and / or by changing the density of at least a portion of the plasma plume.

[0015] The induced field may alter the shape and / or density of the plasma plume. For example, the induced field may alter the shape of the portion of the plasma plume facing the seed to have a larger radius of curvature (i.e., to be more planar). Additionally or alternatively, the induced field may increase the deposition area by broadening the shape of the plasma plume.

[0016] The inductive external field may be created by one or more magnetic fields, electric fields, and / or electromagnetic fields. For example, the inductive external field may be created by one or more permanent magnets. The magnets may be positioned adjacent to the deposition region. The inductive external field may be created using one or more electromagnetic coils. The electromagnetic coils may surround the deposition region and / or chamber. The inductive external field may also be created via an electrically (voltage) biased ring or plate. In some embodiments, the electromagnetic coils are positioned adjacent to the seed and / or outside the chamber to generate an inductively coupled plasma.

[0017] Those skilled in the art will gain a more complete understanding of the advantages of various embodiments of the present invention from the following “Description of Exemplary Embodiments,” which will be discussed with reference to the drawings summarized below. [Brief explanation of the drawing]

[0018] [Figure 1] This figure schematically shows the diamond growth environment at the start of the diamond growth process according to an exemplary embodiment of the present invention. [Figure 2] This figure schematically illustrates diamond growth in a diamond growth environment according to an exemplary embodiment of the present invention. [Figure 3A] This figure schematically illustrates the control of a plasma plume using different types of electric, magnetic, and / or electromagnetic fields according to exemplary embodiments of the present invention. [Figure 3B] This figure schematically illustrates the control of a plasma plume using different types of electric, magnetic, and / or electromagnetic fields according to exemplary embodiments of the present invention. [Figure 3C] This figure schematically illustrates the control of a plasma plume using different types of electric, magnetic, and / or electromagnetic fields according to exemplary embodiments of the present invention. [Figure 3D] This figure schematically illustrates the control of a plasma plume using different types of electric, magnetic, and / or electromagnetic fields according to exemplary embodiments of the present invention. [Figure 3E] This figure schematically illustrates the control of a plasma plume using different types of electric, magnetic, and / or electromagnetic fields according to exemplary embodiments of the present invention. [Figure 3F] This figure schematically illustrates the control of a plasma plume using different types of electric, magnetic, and / or electromagnetic fields according to exemplary embodiments of the present invention. [Figure 3G] This figure schematically illustrates the control of a plasma plume using different types of electric, magnetic, and / or electromagnetic fields according to exemplary embodiments of the present invention. [Figure 4]1 is a diagram illustrating a process for growing diamond in accordance with an exemplary embodiment of the present invention.

[0019] Description of Exemplary Embodiments Exemplary embodiments adjust the position and / or shape of a plasma plume to improve diamond deposition using chemical vapor deposition. In particular, the exemplary embodiments employ microwave plasma chemical vapor deposition. The plasma plume has a shape largely defined by the distribution of ions within the plume. Generally, the plume has a predictable shape and position within a CVD chamber. Exemplary embodiments advantageously adjust the position and / or shape of the plume using magnetic and / or electric fields.

[0020] Figure 1 schematically illustrates a diamond growth environment 10 in accordance with an exemplary embodiment of the present invention. In the illustrated embodiment, the growth environment 10 is inside a chamber 15 used for chemical vapor deposition (CVD). Generally, plasma 16 (also referred to as plasma plume 16) is generated by ionizing a gas 32 (for example, energizing methane with microwaves 30). The gas 32 may be injected into the chamber 15 and may include various concentrations of hydrogen, methane, argon, nitrogen, and / or oxygen, among others.

[0021] Inside the chamber 15, there are one or more diamond seeds 12 disposed (for example, directly) on a refractory metal support 11. The refractory metal support 11 may itself be positioned on a temperature-controlled growth stage 13. Alternatively, the diamond seeds 12 may be positioned directly on the growth stage 13.

[0022] During the CVD growth process, the chamber 15 is filled with precursors of gas 32 formed within the high-temperature plasma 16. As previously described, the plasma 16 may be formed by energizing a charged gas 32 such as methane (CH₄) (e.g., using microwaves 30). Without wishing to be bound by any particular theory, the inventors believe that energizing the plasma 16 causes the atoms of the gas 32 to dissociate, allowing free carbon atoms to attach to the seed 12 crystal through a series of reactions. Accordingly, growth of diamond 14 (or other crystals 14) occurs at the growth interface 26.

[0023] Figure 2 schematically illustrates growth of diamond 14 in a diamond growth environment 10 in accordance with an exemplary embodiment of the present invention. The position and / or orientation of the diamond growth interface 26 relative to the plasma plume 16 affects growth of the diamond 14 via CVD. For example, in Figure 1 the diamond growth interface 26 is the exposed surface of the diamond seed 12. However, in Figure 2 the diamond growth interface 26 includes a surface defined by growth of new diamond 14.

[0024] The plasma plume 16 provides both free radicals and thermal energy for the deposition process. Accordingly, the position of the plume 16 relative to the diamond growth interface 26 (e.g., the diamond seed 12) is important to the growth mechanism. It should be understood that although the plume 16 does not have a clearly defined boundary and thus does not have an exact shape, for simplicity of discussion it is typical to treat the plasma 16 as having a shape. For example, the shape of the plasma plume 16 can be visualized as a region of intense light emission.

[0025] In a typical RF or microwave plasma reactor, the plume 16 tends to become rounded near the growth interface 26, which can make it difficult to maintain uniform growth conditions when growing multiple diamonds 14 simultaneously (for example, as shown in Figure 2). Individual diamonds 14 are typically aligned along a single plane (e.g., defined by the seed 12), but the shape of the plasma 16 (e.g., the portion of the plume 16 closest to the growth interface 26) is inherently non-planar. For example, diamond seed 12A is further from the "boundary" of the plasma plume 16 than diamond seed 12B. Here, the boundary 34 can be said to include part or all of the portion of the plasma plume 16 facing the growth interface 26. These differences in the distance of the plume 16 from the boundary 34 result in differences in temperature and growth conditions for the various seeds 12 (e.g., seed 12B directed towards the center compared to seed 12A directed towards the edge). Therefore, as shown in Figure 2, the growth of diamonds 14 may be non-uniform in seed 12A compared to seed 12B.

[0026] The non-planar shape of the plasma plume 16 results in uneven growth conditions, including a large thermal gradient across the growing diamond 14. These uneven growth conditions are caused by variations in growth conditions resulting from the thermal gradient across the growing diamond 14 (i.e., from the plasma 16 itself), as well as from the fact that different parts of the growth interface 26 are at different distances from the plasma plume 16 (e.g., boundary 34).

[0027] Exemplary embodiments may modify the shape of the growing plasma 16, including by optimizing the procedure and / or by injecting an inert gas species, both of which can alter the dynamics within the plasma plume 16. As discussed below, these techniques can modify the shape of the plume 16. The inventors have found that active means can be used to modify the shape or position of the plasma 16 in situ without requiring significant modifications to process conditions such as pressure, temperature, or gas chemistry.

[0028] Modifications to the plume 16 may include, for example, making the plume 16 denser in the target region, modifying the boundary 34 of the plume 16 to correspond to the shape of the growth interface 26 (e.g., normalizing the distance between the boundary 34 and the growth interface 26), and / or making the boundary 34 substantially more planar. These various modifications can improve the growth rate and ultimately improve the growth rate and final quality of the diamond 14 material. As another example, the plume 16 can be widened to increase the deposition area. Thus, the quantity and quality of the grown diamond 14 can be improved.

[0029] Figures 3A–3C schematically illustrate various techniques for re-forming and / or repositioning the plasma plume 16 according to exemplary embodiments of the present invention. Specifically, the inventors have found that the plasma plume 16 can be reshaped (also called induced) using an electric field and / or a magnetic field. These techniques enable the plasma 16 to be actively reshaped by an external field into a plasma 16A (e.g., including a re-formed boundary 34A) without optionally modifying process conditions including pressure and gas chemistry.

[0030] By reshaping the plasma plume 16, the growth environment 10 can be made more homogenized, reducing growth variability and instability. In addition, the plasma 16 can be made denser in the region of interest, improving the growth rate and ultimately improving the growth rate and final quality of the grown diamond 14 material. In some embodiments, the plume 16 may be widened so that the reshaped boundary 16A can be considered substantially planar (for example, the plasma plume 16A has a large radius of curvature facing the diamond growth interface 26). In some embodiments, the plasma 16 may be said to have a radius of curvature at the boundary 34. In exemplary embodiments, the plume 16A can be reshaped to increase the radius of curvature, thereby reducing the curvature of the boundary 34A and making it more planar.

[0031] In exemplary embodiments, the plasma plume 16 is advantageously modified so that crystals 14A grown near the edges of the growth interface 26 experience substantially the same growth conditions as crystals 14C grown near the center. Without modification of the plume 16, crystals 14A near the edges will exhibit different chemical properties and temperatures than crystals 14C near the center. Generally, the larger the substantially larger the boundary 34, the more seeds 12 can be positioned within the chamber 15 to achieve homogeneous growth simultaneously. For example, some embodiments may have a plume 16 that provides substantially homogeneous growth conditions for a 3x3 arrangement of seeds 12 (e.g., to grow 9 crystals 14). Some embodiments may adjust the shape of the plume 16 so that a 4x4 arrangement of seeds 12 can grow homogeneously (i.e., 16 crystals 14). Thus, exemplary embodiments advantageously enable the growth of nearly twice, or more than twice, the number of homogeneous crystals 14 for an otherwise identical growth environment 10. Furthermore, the plume 16 can be planarized (i.e., made substantially more planar at the boundary 34 or a portion thereof) so that the seed crystal 12 can have homogeneous growth conditions in a 5x5 arrangement. Some embodiments enable homogeneous growth of seed 12 arrangements larger than 5x5 (e.g., up to 10x10).

[0032] To provide homogeneous growth conditions, the shape of the boundary 34 of the plume 16 substantially corresponds to the shape of the growth interface 26. While a precise correspondence of shapes is desirable, those skilled in the art will understand that even slight improvements in the correspondence between the shape of the plume 16 (e.g., boundary 34) and the shape of the growth interface 26 can provide the various advantages described herein.

[0033] Generally, the seed 12 is positioned on a substantially planar support 11 and / or stage 13. Exemplary embodiments may modify the shape of the plume 16 to be substantially planar (i.e., corresponding to the shape of the growth interface 26, which is also substantially planar). It should be understood that the growth interface 26 may have discontinuities (e.g., between the seeds 12) or slight angular miscuts on the seed 12 and / or diamond 14, but the growth interface 26 is still considered substantially planar. It is unlikely that the shape of the plume 16 will precisely correspond to the shape of the growth interface 26. However, while a precise correspondence between the shape of the plume 16 and the growth interface 26 is theoretically ideal, the inventors have found that simply adjusting the shape of the plume 16 to more closely correspond to the shape of the growth interface 26 provides the various advantages described herein. In other words, adjusting the shape of the plume 16 to homogenize the growth conditions of the diamond 14 at the growth interface 26 provides various advantages.

[0034] To control the shape of the plume 16 (e.g., ion displacement), exemplary embodiments may use a magnetic field and / or an electric field. The inventors have found that both types of external fields can adjust the shape of the plume 16. This is because the plasma plume 16 is similar to a conductive gas that is highly responsive to an electric field. Since the ions in the plasma 16 are in motion, the shape of the plume 16 is also responsive to a magnetic field. Therefore, exemplary embodiments may use a magnetic field and / or an electric field to induce charged particles, thereby adjusting the shape of the plume 16. In various embodiments, magnetic and / or electrical biases may be applied to the seed 12 and / or the plume 16. Furthermore, different parts of the plume 16 may be charged (e.g., the outer edge of the plume 16 may be guided downward without the center of the plume 16 being guided downward).

[0035] As shown in Figure 3A, if the inductive external field is inherently magnetic, it may include one or more electromagnetic sources, such as a permanent magnet 20 (e.g., a rare-earth magnet 20), positioned adjacent to the deposition region (e.g., adjacent to the growth interface 26). Alternatively, as shown in Figure 3B, the external field may be generated by one or more electromagnetic sources, such as an electromagnetic coil 22. The magnetic coil 22 may be positioned, for example, outside the chamber 15 to generate the inductively coupled plasma 16A (e.g., wrapped around the chamber 15). Alternatively or additionally, the magnetic coil 22 may be embedded in the wall of the chamber 15.

[0036] Figure 3C schematically shows an electromagnetic coil 22 surrounding the chamber 15 according to an exemplary embodiment of the present invention. As described above, the electrically and / or magnetically induced external field provides better uniformity of the plasma 16. However, the exemplary embodiment may also provide better process stability in certain types of reactors. For example, in some reactors, the plasma 16 may have a tendency to move (e.g., between two stable positions).

[0037] Figure 3D schematically shows two different positions 161 and 162 of the plasma plume 16 within the chamber 15 according to an exemplary embodiment of the present invention. To facilitate the explanation of the relative positions 161 and 162 of the plasma 16 within the chamber 15, the wall 62 of the chamber 15 is shown. In addition, a quartz window 60 is shown through which a microwave source 64 emits microwave radiation 30. In addition, a gas injector 66 configured to introduce gas 32 into the chamber 15 is shown. The wall 62, window 60, microwave source 64, and gas injector 66 are not shown in other figures, but those skilled in the art should understand that all of these components may be present in other figures. However, these components are omitted from various drawings. Furthermore, it should be understood that the shape, arrangement, and position of the wall 62, window 60, microwave radiation source 64, and gas injector 66 are merely illustrative and not intended to limit various embodiments.

[0038] In a preferred embodiment, the chamber 15 is a standing wave chamber 15 having high reflectivity to microwaves. Therefore, the waves bounce within the chamber with relatively low loss. Thus, the exemplary embodiment does not have electrodes (compared to plasma-enhanced CVD with RF electrodes). Generally, the shape of the plasma in a system with RF electrodes is defined by the electrodes. In contrast, the shape of the plasma 16 in the microwave chamber 15 is defined by standing waves. Furthermore, in the microwave chamber 15, there is generally no bias on the stage where the sample (e.g., substrate) is positioned.

[0039] The inventors have found that microwave fields advantageously promote diamond growth. Diamonds 14 grow in RF fields, but the growth rate can be an order of magnitude lower. Adversely, the plasma plume 16 in a microwave field is undesirably small and spherical. In contrast, RF fields typically produce plasma plumes that are advantageously large and relatively flat. Thus, exemplary embodiments advantageously use a second external field (e.g., electric, magnetic, and / or electromagnetic) to adjust the size and / or shape of the plasma 16, thereby improving the growth quality and / or the number of grown diamonds 14.

[0040] To initiate the diamond growth process 14, energy is supplied to the gas 32 in the chamber 15 (for example, by emitting microwave radiation 30 from a microwave source 64 through a quartz window 60) to collide with the plasma 16. Since microwave radiation 30 is an electromagnetic wave, it generates a first electric field configured to convert the gas 32 into plasma 16. Subsequently, as is known to those skilled in the art, microwave radiation 30 continues to be emitted during the growth process to maintain the plasma 16. After colliding with the plasma 16, the plasma 16 generally settles in position 161. However, position 161 of the plasma 16 may be unstable or metastable, and the plasma 16 may move to a second position 162 (for example, the top of the chamber 15 surrounded by the quartz window 60). In exemplary embodiments, the first position 161 may be more desirable for the growth of the diamond 14 than the second position 162.

[0041] Therefore, when energy is applied to the plasma 16, it can have one or more stable and / or unstable stationary positions (depending, for example, on the design of the chamber 15). If both positions are unstable or metastable, the plasma 16 can move between a first position 161 and a second position 162 over time. The locations of the first position 161 and the second position 162 are functions of the shape of the chamber 15. Thus, some chambers 15 may be designed to have a single stable position 161 where the plasma plume 16 rests, while other chambers 15 may have two or more positions 161, 162 between which the plasma plume 16 moves. For example, some chambers 16 may have symmetrical positions (e.g., the first position 161 is above the platform 11, and the second position 162 is above the first position 161 at the top of the chamber 15). In particular, the inventors have found that cylindrical chambers 15 tend to have a second position 162 at the top of the chamber (for example, surrounded by a quartz window 60 through which microwave radiation 30 enters the chamber 15).

[0042] In a given time, there exists a certain probability that the plume 16 is at a first position 161 and a certain probability that the plume 16 is at a second position 162. Furthermore, there may also be a decreasing probability that the plume 16 is at any other position. Exemplary embodiments can use the induced external field described herein to bias the plasma plume 16 toward a single stable position, thereby favorably increasing the probability that the plasma plume 16 is at a desired position 161.

[0043] In exemplary embodiments, a second electric field or a first magnetic field (referred to as a positioning external field) may be activated before, during, and / or after impact with the plasma 16. The positioning external field electrically and / or magnetically biases the plasma 16 to a specific position 161 or 162. Advantageously, this allows for control of the position of the plasma 16, which can be ignited at different positions 161 or 162. Furthermore, even if the plasma starts at a desired position 161, it is possible for the plasma 16 to move to a second unstable or metastable position 162 after impact. Those skilled in the art will understand that the plasma 16 may grow diamond 14 at a desirable position 161, but destroy a portion of the chamber 15 at an undesirable position 162.

[0044] Advantageously, exemplary embodiments use a positioning external field (e.g., generated by an electric bias from the ring 24 or a magnetic bias from the coil 22) to position the plasma plume 16 to the first diamond 14 growth position 161. Thus, some embodiments provide a superposition of electric and / or magnetic fields (e.g., a first electric field for igniting the plasma and a first magnetic field for positioning the plasma).

[0045] As described above, the size and shape of the chamber 15 affect the stable position of the plume 16. However, a discussion of the influence of the size and shape of the chamber 15 on the stability and migration tendency of the plume 16 is outside the scope of this discussion. Generally, RF engineers design the chamber 15 to be a resonant cavity. Two well-known chamber designs commonly employed in CVD include the clamshell chamber 15 and the cylindrical chamber 15. We have found that the clamshell chamber 15 tends to have a single stable position 161, while the cylindrical chamber 15 tends to move the plume 16 between at least two positions 161 and 162.

[0046] Figure 3E schematically shows the configuration of the chamber 15 in Figure 3C, in which the plume 16 is biased to a first position 161. As shown in Figure 3E, the plasma 16 may be inductively coupled by positioning an electromagnetic coil 22 around the chamber 15. The coil 22 generates a laminar, positioning external field parallel to the coil 22 within itself. As is known to those skilled in the art, the electric field generated within the coil 22 is uniform and oriented in a single direction. Thus, the coil 22 biases the plume 16 either upward or downward, depending on the direction of the current. Thus, the coil 22 can be used to bias the plume 16 to its first position 161, in addition to changing the shape of the plume 16.

[0047] Furthermore, in exemplary embodiments, the metal stage 11 creates boundary conditions for the plasma 16 by generating a repulsive force when the metal stage 11 is charged. Thus, as the plasma 16 advances toward the stage, the electromagnetic force pushes the plasma 16 away. Consequently, the center of the plasma 16 may be repelled by the stage 11, while the edges of the plasma 16 may be pushed down.

[0048] Figure 3F schematically shows an alternative arrangement for biasing the plume 16 to a first position 161 according to an exemplary embodiment. The ring 24 may be positioned around the outside of the growth region and / or growth interface 26 of the diamond 14. The ring 24 may be electrically biased. In Figure 3E, the ring 24 is shown at a height lower than the deposition surface. However, in some embodiments, the ring may be at the same height as the deposition surface. The entire ring 24 may be biased. Alternatively, the exemplary embodiment may generate local bias points, for example, under each of many individual seeds, to compensate for physical variations such as height differences between individual seeds.

[0049] By biasing the ring 24, the end 16B of the plume 16 can be pulled downward without guiding the center 16C downward. In an exemplary embodiment, the ring 24 is positioned around the growth such that it is closer to the outer end 16B of the plume than to the center 16C. Various dimensions and positions of the ring 24 may be used. Those skilled in the art will know that the outer field strength is 1 / r 2 We know that it is proportional to . Therefore, at the position described here, the outer end 16B (which is closer to the ring 24) experiences a greater inductive force relative to the center 16C of the plume 16. Thus, the plasma 16 is induced to be flat at the end 16B (as shown, for example, in the induced plasma 16A), while having little effect on the center 16C of the plasma 16.

[0050] Figure 3G shows yet another embodiment for biasing the plume 16 to a desired position and / or shape, according to an exemplary embodiment of the present invention. In Figure 3G, the stage 11 itself is electrically biased (for example, by applying a voltage to the stage 11). Similar to the embodiments discussed earlier, the inductive force generated by the bias plate is used to guide the plasma to the desired shape and / or position.

[0051] In some embodiments, the stage can be biased at a target location. For example, biasing can occur at the position of each seed 12. Thus, the seeds 12 can be spaced apart from each other around the stage 11, and each seed 12 can be biased independently. Such a bias configuration provides greater specificity for inducing plasma 16 (e.g., where the plasma 16 should go and where it should not go). This can be particularly advantageous in situations where the seeds 12 do not always grow at the same rate. Thus, if one seed 12 appears to be growing at a faster rate than another seed 12, the seed 12 with reduced growth can attract more plasma 16 towards it. Alternatively, the seed 12 experiencing faster growth can stop or reduce the amount of plasma 16 being induced towards it. Furthermore, one or more seeds may be biased to push the plasma 16 further away, while other seeds 12 may attract the plasma 16. In this way, it is possible to create highly specific plasma 16 that can be reshaped based on the needs of the growth process.

[0052] Some embodiments may include a temperature sensor configured to detect the temperature at each seed 12. For example, each seed 12 may be on a separate pad which may have a unique voltage applied thereto. Each pad may also have a separate temperature sensor. However, due to process conditions, the pads may not have sensors. Instead, exemplary embodiments may measure the temperature optically, for example, by using a pyrometer or an IR camera. Generally, the closer the plasma 16 is to a particular part of the growth interface 26, the higher the temperature at that location. Therefore, temperature feedback can be used to automatically adjust the amount of plasma 16 induced at a particular location. For example, if one seed 12 is hotter than another seed, the temperature of the hotter seed 12 can trigger a microcontroller to change the bias voltage, reducing the induction of plasma toward that seed 12. Here, a simple example for one seed has been described, but it will be clear that this temperature feedback may be used simultaneously for multiple seeds.

[0053] Additionally or alternatively, the induced external field can be adjusted using optical feedback. For example, a camera can image the plasma 16 and communicate with a controller that maps the shape of the plume 16 as a function of light intensity. The height of different parts of the plasma plume 16 can be adjusted using the light intensity.

[0054] The feedback is discussed with reference to Figure 3F, but it will be apparent to those skilled in the art that the feedback mechanisms discussed herein can be employed in conjunction with any of the various electromagnetic bias configurations disclosed herein and their variations.

[0055] Figure 4 shows a process 400 for growing one or more diamonds according to one embodiment of the present invention. It should be noted that this method is substantially simplified from longer processes that may ordinarily be used. Thus, the method of Figure 4 may have many other steps that a person skilled in the art might use. Furthermore, some of the steps are optional (e.g., step 410) and / or may be performed in a different order than shown (e.g., step 406 may be started before step 404), or simultaneously. Thus, a person skilled in the art can modify the process as appropriate.

[0056] Furthermore, as mentioned above and below, many of the materials and structures mentioned are only a few of the many different materials and structures that can be used. Those skilled in the art can select appropriate materials and structures depending on the application and other constraints. Therefore, discussions regarding specific materials and structures are not intended to limit all embodiments.

[0057] Process 400 may be carried out inside a furnace, reactor, or other apparatus (not shown) having a chamber 15 in which environmental conditions such as predetermined pressure, temperature, and ambient gas are carefully controlled. For example, Process 400 may be carried out using the CVD method.

[0058] The process begins in step 402, in which the diamond seed 12 is positioned in the growth environment 10 (for example, in a vacuum-sealed CVD chamber 15 as shown in Figure 1). Specifically, the diamond seed 12 may be positioned on a refractory metal support 11, which itself may be on a temperature-controlled growth stage 13. Although the exemplary embodiment refers to the growth of diamond 14, the seed 12 may, among other things, be formed from magnesium oxide, iridium, silicon, yttrium-stabilized zirconium, titanium, silicon carbide, diamond, or a combination thereof. Those skilled in the art may further select other materials for the seed 12. Preferably, the seed 12 has a single-crystal / monocrystalline structure. In the exemplary embodiment in which the seed 12 is formed from diamond, the growth surface of the seed 12 may have a (100) crystal orientation with miscuts / orientations in the range of about ±5 degrees.

[0059] In various embodiments, one or more diamond seeds 12 may be positioned within the chamber 15. Furthermore, although the diamond seeds 12 are shown to be aligned on a planar surface, in some embodiments, the diamond seeds 12 may be positioned in a different manner (for example, to match the expected "shape" of the plume 16).

[0060] Next, the process proceeds to step 404, which generates (or collides with) the plasma 16. As previously described, the growth environment 10 includes a gas 32, such as methane (CH4), which is energized (e.g., by microwaves) by 30 and becomes the plasma 16. The gas 32 may be injected into the chamber 15. In some embodiments, the gas 32 may include hydrogen, methane, argon, nitrogen, and / or oxygen. The plasma 16 provides a source of carbon to be deposited onto the seed 12 (e.g., the diamond seed 12). In this way, the diamond 14 growth process is initiated.

[0061] Next, the process proceeds to step 406, which creates an inductive external field configured to reshape the plume 16 in order to guide the deposition of material (e.g., carbon-containing ions) from the plume 16 and / or to bias the plume 16 toward a certain position. For this purpose, exemplary embodiments may include a magnet 20 (e.g., as shown in Figure 3A) or an electromagnetic coil 22 (e.g., as shown in Figure 3B). Figure 3B shows that the coil 22 wraps around and / or surrounds the deposition area, but it should be understood that this is for illustrative purposes only and is not intended to limit the various embodiments. In fact, in some embodiments, the coil 22 wraps around and / or surrounds the deposition area. In some other embodiments, for example, the coil 22 may wrap around the entire chamber 15 (e.g., the coil 22 may be positioned along the outer circumference of the chamber 15).

[0062] If the induced external field is electrical, the result is a superposition of two external fields, i.e., alternating microwave fields coupled with an RF or DC field. The external field may be generated adjacent to the deposition region via an electrically biased ring or plate 24 having a given voltage. Alternatively, the bias may be applied to a ring 24 that encompasses the deposition region and is positioned at or below the height of the deposition surface (e.g., platen). It may also be desirable to generate local bias points, for example, under each of many individual seeds, to compensate for physical variations such as height differences between individual seeds. Although this is an automated process, such as that performed by PID control, it may be even more advantageous to control the external field strength locally or through the formation of the external field. Thus, the external field strength can be tuned via independent variables such as growth rate or temperature.

[0063] As explained earlier, the shape of the plasma plume 16 can be altered using an induced external field (see, for example, the re-attached plasma 16A in Figures 3A-3B). For example, the plasma plume 16 may be widened to better reach more seeds 12. Additionally or alternatively, the shape of the plasma plume 16 may be adjusted to provide more homogeneous growth characteristics. Additionally or alternatively, the position of the plasma plume 16 can be altered using an induced external field.

[0064] Next, the process proceeds to step 408, which involves the deposition of diamond 14. Although shown to occur after step 406, it should be understood that the deposition process of diamond 14 may also occur when the plasma plume 16 is generated. However, the density and location of the deposited diamond 14 may change when an induced external field is created. In some embodiments, such as when a permanent magnet is used, the external field may always be present even when the reactor is not in use. Thus, the "deposition profile" of the plume 16 is altered.

[0065] In step 409, the process receives growth feedback for the diamond 14. The feedback may be related to the temperature of one or more seeds 12. The feedback may also come from a visual monitoring / inspection system (e.g., a camera) that views the plasma plume 16 from the side and determines the distance of the plume 16 to a particular seed 12. Additionally or alternatively, an optical and / or laser measuring system may measure the height of the grown diamond 14. The various types of feedback described herein are illustrative and are not intended to limit the various embodiments of the invention.

[0066] The process may return to step 406, in which the induced outfield is adjusted based on the feedback received in step 409. For example, if a particular seed 12 has a higher temperature than other seeds 12, the system may reduce the inductive force that pulls the plasma plume 16 toward that seed 12. As another example, if a particular diamond 14 is not growing as fast as other diamonds 14, the shorter height of the diamond 14 can be used as feedback to pull the plasma plume closer to that diamond (e.g., by either pulling the plume 16 closer to the diamond 14 and / or spreading the plume). Those skilled in the art can imagine a variety of ways in which feedback may be used to adjust the induced outfield. In an exemplary embodiment, the induced outfield is adjusted so that the growth rates of the various grown diamonds 14 become more uniform.

[0067] The process ends in step 410, which further processes the diamond 14. For example, the process may polish or anneal one or both sides of the resulting diamond 14, depending on its final application. For example, one side of the diamond 14 may be polished and / or the grown diamond 14 may be doped for some downstream application. Other post-processing may involve cutting the grown bulk diamond 14 into wafers of a predetermined size or shape.

[0068] While the above discussion refers to CVD processes, it should be understood that the exemplary embodiments can also work with physical vapor deposition (PVD) processes. For example, pulsed laser deposition (PLD) is a PVD technique in which a high-power pulsed laser beam is focused in a vacuum chamber and directed onto a target of material to be deposited. This material evaporates from the target in a plasma plume, depositing the material as a thin film onto a substrate (such as a silicon wafer facing the target). Therefore, the exemplary embodiments can be applied to various deposition types that generate a plasma plume.

[0069] The embodiments of the present invention described above are intended to be illustrative only, and numerous variations and modifications will be apparent to those skilled in the art. Such variations and modifications are intended to be within the scope of various embodiments.

Claims

1. It is a system for growing diamonds. A chemical vapor deposition reactor including a standing wave cylindrical microwave chamber, A single crystal seed configured to be positioned within the microwave chamber, Precursor gas and A microwave source configured to supply energy to the precursor gas to generate a plasma plume in the standing wave cylindrical microwave chamber, An electromagnetic wave source configured to generate an electrical inductive external field for adjusting the position of the plasma plume within the microwave chamber, Includes, The plasma plume can be repositioned between a first position and a second position within the standing wave cylindrical microwave chamber using the electrical inductive external field. system.

2. The system according to claim 1, wherein the microwave source generates a first electric field that energizes the precursor gas, and the first electric field and the induced external field are at least partially superimposed.

3. The system according to claim 1, further comprising a mechanical support on which the single crystal seed is positioned.

4. The system according to claim 1, further comprising a plurality of single-crystal seeds formed from diamond.

5. The system according to claim 1, wherein the charged precursor gas comprises methane and hydrogen.

6. The system according to claim 1, wherein the microwave source emits microwave radiation.

7. The system according to claim 1, wherein the electromagnetic wave source includes a magnetic coil and / or a charged ring.

8. The system according to claim 3, wherein the electromagnetic wave source includes an electrically biased mechanical support.

9. The system according to claim 1, further comprising a vapor deposition feedback system.

10. The system according to claim 9, wherein the deposition feedback system determines the temperature of one or more seeds, measures the dimensions of one or more grown diamonds, and / or determines the shape of a plasma plume.

11. A method for growing diamonds, The method involves using a microwave source to impart energy to a precursor gas in a standing wave cylindrical microwave chamber to generate a plasma plume, wherein the standing wave cylindrical microwave chamber is such that the plasma plume is unstable or metastable such that it moves between a first position and a second position within the standing wave cylindrical microwave chamber where the plasma plume is generated. To generate a first electric field for biasing the plasma plume, Using the first electric field, the plasma plume is biased toward the first position, To generate a second electric field for modifying the shape of the biased plasma plume, Using the second electric field, the shape of the biased plasma plume is modified, Methods that include...

12. To provide a single crystal seed in the chamber, The process involves depositing carbon from the plasma plume onto the single crystal seed to form a diamond. The method according to claim 11, further comprising:

13. The method according to claim 12, wherein the single crystal seed is located on a mechanical support.

14. The method according to claim 13, wherein the first position is located on the single crystal seed and the second position is located at the top of the chamber.

15. The method according to claim 11, wherein the chamber is a cylindrical chamber.

16. A method for controlling diamond growth, To provide single crystal seeds for growth in a standing wave cylindrical microwave chamber, Using a microwave source, energy is imparted to a carbon-containing gas to generate a plasma plume, Creating an electrically induced external field, Using the aforementioned electrical induction external field, the plasma plume is repositioned from the first position to the second position. Methods that include...

17. The method according to claim 16, wherein the growth environment is located inside a chemical vapor deposition chamber.

18. The method according to claim 16, wherein the gas is methane.

19. The method according to claim 16, further comprising changing the shape of the boundary of the plasma plume facing the single crystal seed to have a larger radius of curvature.

20. The method according to claim 16, further comprising increasing the deposition area by broadly changing the shape of the plasma plume.

21. The method according to claim 16, wherein the induced external field is created using one or more magnetic fields, electric fields, and / or electromagnetic fields.

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