Method for forming semiconductor layer and material deposition system

Abstract

Systems and methods for forming a semiconductor layer including an oxide-based layer are disclosed in which a material deposition system has a rotation mechanism that rotates a substrate about a central axis of a substrate deposition plane of the substrate. A material source that supplies material to the substrate has i) an exit orifice having an exit orifice plane and ii) a predetermined spatial distribution of material jets starting from the exit orifice plane. The exit aperture is positioned at an orthogonal distance, a lateral distance, and a tilt angle relative to the central axis of the substrate. The system may be configured to i) find a minimum of the orthogonal distance and the lateral distance using a set tilt angle to achieve a desired layer deposition uniformity, or ii) find the tilt angle using a set orthogonal distance and a set lateral distance to achieve the desired layer deposition uniformity.

Description

[0001] This application is a divisional application of Chinese patent application No. 201980038891.0, whose application date is May 29, 2019 and whose invention name is “Method and material deposition system for forming a semiconductor layer”.

[0002] Related Applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 682,005, filed on June 7, 2018, and entitled “Material Deposition System and Methods”; the U.S. Provisional Patent Application is hereby incorporated by reference for all purposes. Technical Field

[0004] The present invention relates to a method and a material deposition system for forming a semiconductor layer. Background Art

[0005] In semiconductor manufacturing processes, thin film materials are deposited on a planar deposition surface using, for example, source materials in a reaction chamber. Molecular beam epitaxy (MBE) is one of several methods for depositing single-crystalline thin films in a reaction chamber. MBE is performed in high vacuum (HV) or ultra-high vacuum (UHV) (e.g., 10 –6 Up to 10 -9 The most important aspects of MBE are (1) flexibility in the choice of source material species; (2) abrupt changes in the interfaces between the deposited dissimilar films; (3) low impurity content of the deposited films; and (4) precise and uniform thickness of the deposited films. The last aspect is achieved by using a relatively slow deposition rate (typically less than 1,000 nm per hour) compared to other conventional deposition processes such as chemical vapor deposition (CVD), which typically exceed 10,000 nm per hour. The slow deposition rate (or growth rate) of MBE is advantageous for epitaxially growing thin films; however, MBE requires a proportionally higher reactor vacuum to match the low impurity content achieved by other deposition techniques such as CVD.

[0006] In a deposition process such as MBE, a high-quality film may have a thickness uniformity of about 99% or greater over the entire deposition plane. In other words, a high-quality film may have a thickness non-uniformity of about 1% or less over the entire deposition plane. In current MBE processes, uniformity over the entire deposition plane is critical because there is a direct correlation between the growth rate and the quality of the epitaxially grown film. That is, a slower deposition rate enables control of uniform atomic monolayer scale coverage over the entire deposition plane to achieve a two-dimensional (2D) "layer-by-layer" (LbL) growth mode. Thin film deposition using the LbL growth mode enables a complete 2D layer to be formed before subsequent layer growth, which is the most ideal method for epitaxial growth of single-crystal thin films and multilayer heterogeneous films. Typically, the LbL growth mode is achieved for technically relevant semiconductors (e.g., AlGaAs, AlGaN, SiGe, etc.) in accordance with at least the following criteria: (i) highly non-equilibrium temperature-pressure conditions; (ii) uniform arrival rate of the substance over the entire deposition plane; and (iii) highly uniform spatial temperature that can be imparted to the growth surface. Summary of the invention

[0007] In some embodiments, an optoelectronic device includes a substrate and a multi-region stack epitaxially deposited on the substrate. The multi-region stack includes a crystal polarity having an oxygen polar crystal structure or a metal polar crystal structure along a growth direction. The multi-region stack includes: a first region including a buffer layer; a second region including a crystal structure improvement layer; a third region including a first conductivity type; a fourth region including an intrinsic conductivity type layer; and a fifth region including a second conductivity type, the second conductivity type being opposite to the first conductivity type. At least one region of the multi-region stack is a layer including Mg (x) Zn (1-x) At least one region of the multi-region stack is a superlattice comprising at least two of: ZnO, MgO, and Mg (x) Zn (1-x) O.

[0008] In some embodiments, an optoelectronic device includes a substrate and a multi-region stack epitaxially deposited on the substrate. The multi-region stack includes a non-polar crystalline material structure along a growth direction. The multi-region stack includes: a first region including a buffer layer; a second region including a crystal structure improvement layer; a third region including a first conductivity type; a fourth region including an intrinsic conductivity type layer; and a fifth region including a second conductivity type, the second conductivity type being opposite to the first conductivity type. At least one region of the multi-region stack is a layer including Mg (x) Zn (1-x) At least one region of the multi-region stack is a superlattice comprising at least two of: ZnO, MgO, and Mg (x)Zn (1-x) O.

[0009] In some embodiments, a method of configuring a material deposition system includes providing a rotation mechanism that rotates a substrate about a central axis of a substrate deposition plane of the substrate. A material source is selected to supply material to the substrate, wherein the material source has i) an outlet orifice having an outlet orifice plane and ii) a predetermined material ejection spatial distribution starting from the outlet orifice plane. The predetermined material ejection spatial distribution has an axis of symmetry that intersects the substrate at a point offset from the central axis. The outlet orifice is positioned at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. The method also includes setting i) the inclination angle or ii) the orthogonal distance and the lateral distance for the outlet orifice of the material source. The desired accumulation of the material on the substrate is selected to achieve a desired layer deposition uniformity for a desired growth rate. The method i) uses the set inclination angle to determine a minimum of the orthogonal distance and the lateral distance to achieve the desired layer deposition uniformity or ii) uses the set orthogonal distance and the set lateral distance to determine the inclination angle to achieve the desired layer deposition uniformity. The substrate and the material source are contained within a vacuum environment.

[0010] In some embodiments, a method for forming a semiconductor layer includes: rotating a substrate about a central axis of a substrate deposition plane of the substrate; heating the substrate; and providing a material source that supplies material to the substrate. The material source has i) an outlet orifice having an outlet orifice plane and ii) a predetermined material ejection spatial distribution starting from the outlet orifice plane, the predetermined material ejection spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis. The outlet orifice is positioned at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. The method also includes containing the substrate and the material source in a vacuum environment and emitting the material from the material source to form a semiconductor layer on the substrate. The outlet orifice is positioned so that i) the orthogonal distance and the lateral distance are minimized for a set inclination angle to achieve a desired layer deposition uniformity for a desired layer growth rate of the semiconductor layer on the substrate, or ii) the inclination angle is determined for a set orthogonal distance and a set lateral distance to achieve the desired layer deposition uniformity for the desired layer growth rate of the semiconductor layer on the substrate.

[0011] In some embodiments, a material deposition system has: a rotation mechanism that rotates a substrate deposition plane of a substrate around a central axis of the substrate deposition plane; a heater configured to heat the substrate; a material source that supplies material to the substrate; and a positioning mechanism. The material source has i) an outlet hole having an outlet hole plane and ii) a predetermined material ejection spatial distribution starting from the outlet hole plane. The predetermined material ejection spatial distribution has an axis of symmetry that intersects the substrate at a point offset from the central axis, wherein the outlet hole is positioned at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. The positioning mechanism allows for dynamic adjustment of the orthogonal distance, the lateral distance, or the inclination angle.

[0012] In some embodiments, a method for forming an oxide-based semiconductor layer includes: rotating a substrate about a central axis of a substrate deposition plane of the substrate; heating the substrate; and placing a plurality of material sources facing the substrate. The plurality of material sources include a magnesium (Mg) source and a plasma source of nitrogen or oxygen. Each of the plurality of material sources has i) an outlet hole having an outlet hole plane and ii) a predetermined material ejection spatial distribution starting from the outlet hole plane, the material ejection spatial distribution having a symmetry axis that intersects the substrate at a point offset from the central axis. The outlet hole is positioned at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate. The method also includes emitting material from the plurality of material sources onto the substrate to form an oxide-based layer on the substrate. The exit aperture is positioned such that i) for a set tilt angle, the orthogonal distance and the lateral distance are minimized to achieve a desired layer deposition uniformity for a desired layer growth rate of the oxide-based layer on the substrate, or ii) the tilt angle is determined for a set orthogonal distance and a set lateral distance to achieve a desired layer deposition uniformity for the desired layer growth rate of the oxide-based layer on the substrate.

[0013] In some embodiments, a method for forming a semiconductor layer includes: rotating a substrate deposition plane of a substrate around a central axis of the substrate deposition plane; heating the substrate; and placing a plurality of material sources facing the substrate. The plurality of material sources include a magnesium (Mg) source, a zinc (Zn) source, and a plasma source of nitrogen or oxygen, wherein each of the plurality of material sources has i) an outlet hole having an outlet hole plane and ii) a predetermined material ejection spatial distribution starting from the outlet hole plane. The material ejection spatial distribution has an axis of symmetry that intersects the substrate at a point that deviates from the central axis. The outlet hole is positioned at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. Material is emitted onto the substrate from the plurality of material sources to form a p-type doped layer on the substrate. The exit hole is positioned such that i) for a set tilt angle, the orthogonal distance and the lateral distance are minimized to achieve a desired layer deposition uniformity for a desired layer growth rate of the p-type doped layer on the substrate, or ii) the tilt angle is determined for a set orthogonal distance and a set lateral distance to achieve a desired layer deposition uniformity for the desired layer growth rate of the p-type doped layer on the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is an isometric view of a conventional high vacuum reaction chamber.

[0015] Figure 2 is an isometric view of a material deposition system according to some embodiments.

[0016] Figure 3 is a graph of examples of beam flux profiles corresponding to certain cosine N factors for a material source, according to some embodiments.

[0017] Figures 4 to 7 is an example of a graph of configuration space for certain locations of a material source relative to a forming surface, wherein calculated film non-uniformities are plotted as a function of coordinates X and Z of the material source, according to some embodiments.

[0018] Figure 8 is a flow chart of an example of a method of configuring an off-axis source in a high vacuum reaction chamber to improve the balance between film quality and film growth rate, according to some embodiments.

[0019] Fig. 9 is a side view of an example of a plasma processing system for forming semiconductor layers, such as high-quality oxide-based films, according to some embodiments.

[0020] FIG. 10A to FIG. 10B is a cross-sectional view of an oxide-based LED device structure according to some embodiments.

[0021] Fig.11 According to some embodiments, FIG. 10A to FIG. 10B Flowchart of an example of a method for an LED device structure shown in FIG. DETAILED DESCRIPTION

[0022] The present disclosure relates generally to semiconductor manufacturing processes, and more particularly to a material deposition system having an off-axis material source in a high vacuum reaction chamber to improve the balance between film quality and film growth rate. A method for configuring a material deposition system by determining the location of a material source and also scaling the size of the entire reaction chamber according to the location of the material source is disclosed. The present disclosure also relates to high-quality oxide-based semiconductor structures, such as light emitting diodes (LEDs), and systems and methods for forming such structures.

[0023] The high quality films achievable using UHV deposition techniques have traditionally been achieved by greatly increasing process times compared to other established high-pressure CVD semiconductor manufacturing processes. Unfortunately, best-practice conventional UHV deposition methods (such as MBE) cannot adequately meet the high throughput processing required by silicon-based semiconductor manufacturers. In addition, current MBE processes are limited to growing highly uniform films on relatively small deposition surfaces (such as 6-inch diameter and smaller substrates). The silicon-based semiconductor industry has emphasized scaling up the manufacturing process to larger deposition surfaces (such as 8-inch, 12-inch, and even 18-inch deposition surfaces) to keep the deposition cost per unit area ($ / m2) sufficiently low. 2 Therefore, new methods are needed to scale up the MBE process to larger deposition surfaces and provide high film quality at high deposition rates.

[0024] In semiconductor device manufacturing, Group III nitride (III-N) semiconductors (e.g., aluminum nitride, gallium nitride, aluminum gallium nitride, indium nitride) are generally considered to belong to one of the most promising semiconductor families for making wide-bandgap semiconductors used in the manufacture of deep ultraviolet (DUV) optical devices such as LEDs and laser diodes (LDs). Unfortunately, several challenges inherent to conventional manufacturing equipment and methods limit the manufacture of high-quality Group III-N films.

[0025] For example, as described above, for substrates greater than 4 inches in diameter, it is difficult to control the growth temperature and precursor gas levels necessary for high-quality film deposition. Non-uniform temperature profiles across the film forming surface may produce low-quality or unusable devices. In addition, the formation of conventional III-N films is a relatively inefficient, low-yield, and expensive process with low utilization of expensive source materials. Finally, the device bandgap tuning capabilities of conventional III-N films are limited. This reduces the flexibility of semiconductor device design and application, particularly in the manufacture of DUV LEDs. As the semiconductor industry places increasing emphasis on producing high-quality films on larger substrates, improving production yields, and reducing manufacturing costs, new methods for device manufacturing are needed.

[0026] In the present disclosure, methods are provided for configuring biased material sources in a high vacuum reaction chamber in order to improve the balance between film quality and film growth rate. For example, embodiments are used to determine the position of a material source (e.g., a Knudsen gap cell, a gas injector source, a remote plasma source, an ion beam source, a sputtering source, a charged particle beam, a thermal evaporation source, or an ablation source) relative to a film forming surface in a high vacuum reaction chamber, which provides an improved balance between film quality and film growth rate compared to conventional techniques. More specifically, for a given material source having certain properties or characteristics and a given tilt angle setting of the material source, the method is used to determine the lateral distance and the orthogonal distance of the material source relative to the forming surface to improve the balance between film quality and film growth rate. In other embodiments, the lateral distance and the orthogonal distance of the material source can be set, and the tilt angle can be determined to obtain the desired film quality and film growth rate.

[0027] Also disclosed are systems and methods for forming high-quality oxide-based DUV LEDs. Oxide-based semiconductors are wide bandgap semiconductors classified as II-VI semiconductor groups. Typically, they have good transparency, high electron mobility, wide bandgap, and strong luminescence at room temperature. Oxide-based semiconductors are essentially n-type; traditionally, it is difficult to complete p-type doping of oxides. In an embodiment of the present invention, p-type doping of these semiconductors is achieved using a plasma of active atomic nitrogen (N*) or molecular nitrogen (N2*). The method disclosed herein utilizes a plasma reaction chamber and forms a film on a substrate made of a material such as calcium fluoride. In some embodiments, a buffer layer of magnesium zinc oxide (MgZnO) is formed on a substrate, and a MgO-MgZnO multilayer is formed on top of the buffer layer. Subsequently, n-type MgZnO is formed on top of the MgO-MgZnO multilayer, and a non-intentional doping (NID) layer of MgZnO or MgO is formed on top of the n-type MgZnO layer. A p-type MgZnO layer is then formed by a plasma of N* or N2* using p-type doping. Finally, metal contacts are formed on the device structure using conventional photolithography and metallization processes. In one example of operation, the n-type MgZnO layer generates electrons that move into the NID layer, where the charge carriers interact and recombine to emit light in the UV wavelength range of about 100 nm to about 280 nm from the LED device structure.

[0028] Methods and materials for forming high-quality oxide-based DUV LEDs exhibit advantages over conventional methods and materials. For example, it is difficult to control the growth temperature and precursor gas content necessary for high-quality film deposition of III-N films using conventional methods, especially for substrates with diameters greater than 4 inches. In addition, the formation of conventional III-N films is a relatively inefficient, low-yield, and expensive process with low utilization of expensive source materials. Finally, conventional III-N films have limited bandgap tuning capabilities. This limits the flexibility of semiconductor device design and application, particularly in the production of DUV LEDs. In contrast, the methods disclosed herein emphasize the production of high-quality films on larger substrates, greater device application flexibility, higher production yields, and reduced manufacturing costs.

[0029] MBE is just one example of a method for epitaxially growing multiple crystalline thin films in a high vacuum environment. Such films are composed of, for example, a composite semiconductor selected from the periodic table. For example, a IIIA-VA semiconductor may include a IIIA metal selected from at least one of Al, Ga, and In and a VA material selected from As, P, and N to form Al. x Ga 1-x As y P 1-y and Al x Ga1-x In another example, the II-VI semiconductor may include a Group II metal selected from Cd and Zn and a Group VI species selected from Te, S and Se to form a compound Zn x Cd 1-x Te. Other examples include IV-IV (e.g., Si x Ge y C z ) and metal oxides MO x Other examples of metal oxides are RE-oxides and RE-oxynitrides (wherein RE is selected from at least one species of the rare earth element family, i.e., a lanthanide metal species or an alkaline earth metal species) or mixed oxides of the form IIA-IB-VIA (e.g., Mg x Zn 1-x O), the oxides and oxynitrides or mixed oxides are also exemplary materials made using the MBE method disclosed herein. The method of the present invention can utilize other materials, such as amorphous oxynitrides and metal alloys, to produce films with high uniformity at enhanced growth rates. That is, the physical principles disclosed herein are independent of the surface chemistry specific to the adatoms and substrate.

[0030] In addition, the use of compound semiconductor materials in the deposition process provides the ability to fabricate multiple heteroepitaxial layers sequentially deposited on a deposition surface. This allows quantum engineering structures to be customized and optimized for specific electro-optical and electronic applications (e.g., LEDs, lasers, power transistors, and radio frequency devices).

[0031] Thus, in the methods and systems of the present invention, the material sources arranged relative to the formation surface to improve the balance between film quality and film growth rate are adapted to support a continuous, high throughput film formation process using an MBE system. The present disclosure provides improvements over existing systems and methods, which are conventionally characterized by at least one of the following: slow growth rate and low deposition uniformity caused by the physical arrangement of the material sources, which is determined by the manufacturer of the MBE system.

[0032] Conventional material deposition systems

[0033] Figure 1 1 is an isometric view of a portion of a high vacuum reaction chamber 10 known in the art, the high vacuum reaction chamber including a material source 18, the material source being arranged off-axis and at an angle relative to a film forming surface 26 of a substrate 22. The high vacuum reaction chamber 10 may be a reaction chamber of an MBE system 5. A vacuum environment 14 is maintained within the high vacuum reaction chamber 10 by a vacuum pump 16. For example, the vacuum environment 14 may be maintained at about 10 –12 To about 10 –7 About 10 –11 To about 10–9 Torr or about 10 –11 Support up to 10 –5 A well-prepared and substantially leak-free reactor has a base pressure and a growth pressure (ie, during deposition) that are directly related to the pumping speed of the reactor and the incident beam pressure produced by the source.

[0034] The material source 18 is arranged relative to the substrate 22 inside the high vacuum reaction chamber 10. The substrate 22 can be any base material on which a material film or material layer can be formed. The substrate 22 can rotate around the central rotation axis AX. The side of the substrate 22 facing the material source 18 provides a film forming surface 26. The substrate 22 has a radius R SUB .

[0035] Formation surface 26 is a target for material delivered from material source 18. That is, formation surface 26 is the side of substrate 22 on which a film may be formed, such as by epitaxy. Epitaxy refers to the deposition of a crystalline overlying layer on a crystalline substrate, wherein the overlying layer is aligned with the substrate. In other words, the overlying layer must have one or more preferred crystal orientations relative to the substrate to be referred to as epitaxial growth. The overlying layer is referred to as an epitaxial film or epitaxial layer, and is sometimes referred to as an epi layer.

[0036] Material source 18 may be any source of elements and pure substances from which a film may be formed on forming surface 26. For example, Figure 1 The material source 18 shown in the figure can be a Knudsen gap cell. A typical Knudsen gap cell includes a formed crucible (made of high purity pyrolytic boron nitride, fused quartz, tungsten or graphite), a plurality of resistive heating wires, a water cooling system, a heat shield to contain the heat within the crucible body, a crucible orifice and an orifice baffle, all of which are not shown but are well known to those skilled in the art. The material source 18 includes an outlet orifice 30. In the case of a Knudsen gap cell, the outlet orifice 30 is an opening in the end of the crucible that faces the forming surface 26. As the crucible heats, the material (e.g., liquid) inside the crucible is also heated, and atoms of the material are evaporated (e.g., evaporated from the surface of the liquid). By controlling the crucible temperature, the number of atoms evaporated per unit area per unit time can be well controlled. The evaporated atoms or species are transported from the exit orifice 30 under pressure, travel at a well-defined exit velocity and mean free path over the source-to-substrate distance (maintained by the high vacuum level in the reactor), and are directed toward the forming surface 26 where they collide and / or interact with the material of the forming surface 26. That is, a plume 34 of material (or species) exiting from the exit orifice 30 of the material source 18 is directed toward the forming surface 26. The plume 34 has an axis of symmetry SA.

[0037] Conventional, commercially available MBE deposition systems utilize multiple material sources that are spatially configured to achieve adequate material flux uniformity over a relatively small deposition plan area without primary consideration of simultaneously optimizing flux uniformity and growth rate. Figure 1 The central rotation axis AX of the substrate is schematically depicted. The material source 18 is positioned at a certain lateral distance X from the central rotation axis AX of the substrate 22, a certain orthogonal (perpendicular) distance Z from the plane of the formation surface 26, and a virtual flux plane (VFP) tilt angle α relative to the plane of the formation surface 26. Therefore, the material source 18 is an "off-axis" material source. The lateral distance X and the orthogonal distance Z are the coordinates of the material source 18 relative to the center of the substrate deposition plane 26.

[0038] In fact, by increasing the substrate-source distance R Src-Sub The non-optimal spatial placement of the material sources in conventional MBE systems is empirically compensated (i.e., by placing the sources farther away than would otherwise be required for optimal placement). This increased substrate-to-source distance directly results in a reduction in growth rate that is inversely proportional to the square of the substrate-to-source distance and reduces the utilization of the exhausted source material. Additionally, in conventional MBE systems, the plume of material from the material source is typically directed toward the center of the forming surface 26.

[0039] A conventional MBE system can be summarized and generalized as a reactor system with a configuration space specified by:

[0040] (i) an axis of symmetry SA of a material source plume arranged to target the absolute center of rotation of the deposition plane;

[0041] (ii) The distance R from the source to the substrate src-sub and a lateral distance X of the center of mass of the source VFP relative to a substrate rotation axis AX that is cylindrically or spherically symmetric relative to the center of the deposition plane;

[0042] (iii) Reactor size, scale the reactor size so that X ≤ R src-sub And β = tan –1 (X / R src-sub )≤45 o , where β is the angle between the vertical axis Z and the axis of symmetry SA; and

[0043] (iv) a virtual flux plane tilt angle, wherein the virtual flux plane tilt angle is limited to 0 ≤ α ≤ 45 o within the range.

[0044] Source placement is optimized for material deposition systems

[0045] Figure 21 is an isometric view of a portion of a material deposition system 50 according to some embodiments. The material deposition system 50 is a molecular beam epitaxy system having a high vacuum reaction chamber 100. The material deposition system 50 includes a material source 118 that is arranged off-axis and at an angle relative to a substrate deposition plane 126 of a substrate 122 and is also offset by an amount R 偏移 That is, the material source 118 has an axis of symmetry SA that is aligned with a point that is offset from the absolute center of the substrate 122 by an amount R 偏移 The material source 118 deposits the material on the area 122P of the substrate deposition plane 126. The vacuum environment 114 is maintained in the high vacuum reaction chamber 100 by the vacuum pump 116. For example, the vacuum environment 114 can be maintained at about 10 -12 To about 10 -7 Torr, and in another example about 10 -11 To about 10 -9 In another example, about 10 -11 Support to 10 –5 within the scope of support.

[0046] A material source 118 is arranged relative to a substrate 122 inside the high vacuum reaction chamber 100 to produce a deposited layer with high uniformity while maintaining a high yield. The substrate 122 can be any base material on which a material film or material layer can be formed. For example, the substrate 122 can be a wafer of silicon (e.g., single crystal), sapphire, MgO, or Ga2O3 with a clean atomic surface. The substrate 122 can rotate around a central rotation axis AX. The substrate deposition plane 126 is the side (e.g., front surface) of the substrate 122 on which a film can be formed, such as by epitaxy. The substrate 122 has a certain radius R SUB For example, an 8-inch substrate 122 has a 4-inch R SUB ; 12-inch substrate 122 has 6 inches (about 150mm) R SUB ; etc. Although Figure 1 The substrate 122 shown in the figure is circular, but the systems and methods of the present invention are not limited thereto. For example, the substrate 122 can be square or some other non-circular shape. In another embodiment, the material source 118 is arranged relative to a platen or the like on which one or more substrates are mounted.

[0047] Those skilled in the art will recognize that the high vacuum reaction chamber 100 may include other components (e.g., substrate heaters, material source apertures, sensing devices, additional vacuum pumping system components, etc.) that are not described herein. Figure 2 Shown in.

[0048] The material source 118 may be any source of elements and pure substances from which a film may be formed on the substrate deposition plane 126. In some embodiments, the material source may be a plasma source of nitrogen or oxygen. Examples of the material source 118 include: a gas precursor injector; a preheated gas injector; a Knudsen-type heat-driven crucible (i.e., a Knudsen gap cell) for containing sublimated solid materials or evaporated liquid materials; an electron beam evaporator that heats the source material; and a remote plasma activation source for a gas feedstock (i.e., a source in which the plasma zone is completely contained within the source and does not extend from the source to the substrate surface). In one example, when aluminum (Al) is the material to be epitaxially grown on the substrate deposition plane 126, the material source 118 may be a Knudsen gap cell containing substantially pure aluminum contained in a substantially non-interacting crucible.

[0049] The material source 118 includes an exit orifice 130 and a material level 132 of material in the material source 118. In the case of a Knudsen gap cell, the exit orifice 130 is an opening in the end of the crucible that faces the substrate deposition plane 126. A plume 134 of material (or substance) exiting from the exit orifice 130 of the material source 118 is directed toward the substrate deposition plane 126. In another embodiment, the material source 118 includes a plurality of outlets (exit orifices 130).

[0050] The position of the material source 118 relative to the substrate 122 is dynamically adjustable, so that the tilt angle, lateral distance and / or orthogonal distance of the material source 118 relative to the substrate 122 can be changed between production runs to achieve the desired layer deposition uniformity and the desired layer growth rate. The setting of the tilt angle, lateral distance and orthogonal distance will depend on the material ejection spatial distribution of the material source. Multiple material sources that emit different materials from each other can also be used simultaneously to affect positioning. In some embodiments, the tilt angle of the material source can be set first, and the set tilt angle can be used to determine the minimum value of the orthogonal distance and the lateral distance. In other embodiments, the orthogonal distance and the lateral distance can be set first, and the tilt angle can be determined to achieve the desired layer deposition uniformity for the desired growth rate. In some embodiments, the position of the material source 118 is movable, while the substrate 122 is fixed; or, instead of or in addition to the material source 118, the substrate 122 can also be movable. For example, the positioning mechanism can be connected to the material source, the substrate, or both the material source and the substrate. The positioning mechanism may be, for example, a bracket fixed along the slot, an arm or post with an adjustable length, a linear actuator, or a combination of the above.

[0051] The plume 134 of material (or matter) is a flux of substantially non-interacting particles having a spatial beam flux profile (BFP) that can be characterized by the angular distribution of matter emitted forward from the material source 118. The BFP can also be referred to as a predetermined material ejection spatial distribution of the material source. The beam flux profile is characterized by the relationship of the BFP angle θ to the symmetry axis SA of the plume 134. Therefore, the material source 118 can be approximated and characterized by having a certain cosine N factor. See Figure 3 Let's describe the cosine N factor in more detail.

[0052] Figure 3 Graph 200 is a graph of examples of beam flux distributions corresponding to certain cosine N factors of a material source. Graph 200 shows that the angular beam dispersion of certain beam flux distributions varies with the BFP angle θ. For example, graph 200 shows a BFP 210 that has a cosine N factor of 1, is substantially spherical, and is considered to be an isotropic point source. Figure 3 As shown in N BFPs with (θ)(N>1) are more directional. For example, graph 200 shows BFP 214, which has a cosine N factor of 6 and is an elongated and narrower beam flux distribution than BFP 210, rather than a spherical beam flux distribution. Graph 200 also shows examples of other BFPs with cosine N factors between 1 and 6 between BFP 210 and BFP 214. For example, the difference between a source with a cosine N factor of 1 and a source with a cosine N factor of 6 is that 80% of the forward projection beam is contained within ±36.4°, respectively. o and ±15.5 o Thus, by judiciously selecting the cosine-N-factor material source and the relative configuration position with respect to the rotating deposition plane, improved flux utilization can be achieved. For example, using a source with a cosine-N factor is more directional, thereby reducing the amount of wasted material.

[0053] The material source 118 may be any source characterized by a cosine N factor. This cosine N factor characterization is independent of the type of source, whether the material source 118 is a liquid source that evaporates a material, a sublimation source that sublimates a material, a gas source, or the like.

[0054] Conventional MBE systems utilize a material source having a cosine N factor of about 1 to about 2. Those skilled in the art widely believe that a substantially spherical plume is advantageous for high-throughput uniformity. Additionally, in conventional material sources, the effective cosine N factor can vary according to source material depletion. As the source material depletes, this results in a change in spatial flux non-uniformity across the deposition plane, and this problem is exacerbated if the material source is configured in a sub-optimal position relative to the deposition plane. Accordingly, in embodiments of the present invention, it is desirable to design a deposition reactor having an optimal source configuration that can tolerate variations in the effective cosine N factor.

[0055] Additionally, in conventional MBE systems, the material source is placed at a relatively long distance from the forming surface, and that distance typically far exceeds the optimal distance. Systems of the prior art typically employ an R that completely exceeds the diameter of the deposition plane src-sub (i.e., for α < 45 o , R src-sub >> 2R sub ). The typical BFP of a conventional material source is characterized by a cosine N factor of 1 < N ≤ 2, plus the long distance that the material constituting the source beam must travel, resulting in at least one of the following: (1) sub-optimal growth rate; (2) poor flux uniformity across the deposition plane; (3) a large amount of residual background impurity material, which can detrimentally affect the deposited film; and (4) poor flux utilization, as measured by the ratio of the total flux emitted from the source to the flux intersecting the deposition plane. That is, in conventional systems, the material from the material source tends to be emitted within a fairly large volume of the chamber rather than being directed towards the forming surface.

[0056] In the method and system of the present invention, the axis of symmetry SA of the plume 134 generated by the material source 118 points to a clearly defined portion at the periphery of the substrate deposition plane 126 of the substrate 122. Specifically, the axis of symmetry SA of the plume 134 is offset and points to a point spaced apart from the center of rotation of the substrate deposition plane 126. That is, the material source 118 has an axis of symmetry SA that intersects the substrate 122 at a point spaced apart by an amount R 偏移 from the axis of rotation AX.

[0057] Additionally, the lateral distance X and the orthogonal distance Z from the center axis of rotation AX of the substrate deposition plane of the substrate 122 representing the position of the material source 118 are scaled to R SUB . The relationship of the lateral distance X and the vertical distance Z to R SUB can be used to scale the dimensions of the high-vacuum reaction chamber 100. Bringing the material source 118 in the reaction chamber 100 closer to the substrate 122 allows for a smaller overall size of the reaction system (material deposition system 50), thereby reducing costs.

[0058] As Figure 2 As shown in detail A, the outlet hole 130 as the outlet of the material source 118 has an effective area A src . Effective area A src The radius R src Limit. With effective area A SRC The outlet orifice 130 may be characterized or designed as a plurality of independent cosine N element sources. For example, an integer m element source indexed by i = {1, ..., j, ..., m} (where m>1) is each characterized by a predetermined material jetting spatial profile (BFP) defined by cos Ni (θ i ) is given. The element source can be selected so that N i is constant for all values ​​of i, or at least two dissimilar sources of elements may be selected where Ni≠Nj.

[0059] In one example of determining placement of a material source in a material deposition system, a source having a radius R SUB = 1.5 can be used to represent a 300 mm diameter substrate 122. SRC =0.2 The composite source (ie, material source) of a circular area defined by is located in the positive z-direction half-space relative to the substrate deposition plane 126, and its center is located at And VFP tilt angle α=45 0 The source is stepped in three radial directions. To discretize, the discretization elements are angularly spaced, forming a composite source plane with 21 elements. Each source of the elements is modeled as a modified cosine emitter Each source element on the VFP emits a surface normal parallel to the VFP The flux is directed towards the substrate deposition plane 126. Then, the intersection of the directed flux segment with the general point P on the substrate deposition plane 126 and the Euclidean distance are calculated. The substrate 122 or substrate deposition plane 126 is similarly ΔR SUB = 0.1 and The radial and angular increments are discretized to provide a Cartesian coordinate P(x SUB ,y SUB 、z SUB ) with a sampling grid of 541 points.

[0060] The vacuum environment of the material deposition system is sufficient to ensure the mean free path length so that the ballistic particle state of the material ejected from the source hole is maintained greater than or equal to the Euclidean distance between the material source outlet hole and the point where the deposition plane intersects the symmetry axis of the material ejection spatial distribution. Provide a suitably high vacuum condition in which the residual background impurity species in the reaction chamber are significantly reduced. For a given vacuum degree, the cosine N factor of the material source also directly affects the amount of residual background impurity species in the reaction chamber. Assuming that the source material is composed of a sufficiently high purity material, the impurity concentration that can then be used to incorporate into the growing film (i.e., to form an additional undesirable impurity flux component of the desired material source flux) will depend primarily on the deposition rate and the vacuum maintained during deposition. That is, for a given base vacuum degree in the reactor before the source material flux is introduced, there is a quantifiable amount of time during which the well-prepared and clean deposition surface will accumulate undesirable impurity surface coverage. Therefore, it is desirable to simultaneously achieve small flux non-uniformity, high growth rate, and low background impurity concentration.

[0061] In the present disclosure, the material source 118 as an offset source improves both the flux non-uniformity across the substrate deposition plane 126 and reduces the source-to-substrate distance compared to conventional MBE systems. That is, an optimal position is determined for a given material source type that achieves reduced flux non-uniformity and increased growth rate for a given substrate deposition plane 126 area compared to conventional MBE systems.

[0062] In addition, embodiments of the present invention provide an optimal configuration space for material sources utilized in a high vacuum reactor, specifically for large area deposition planar applications. Additionally, reactors for large deposition areas can be further optimized according to the method by judiciously selecting material source properties, such as effective cosine N factor (N ≥ 2) and source VFP area.

[0063] In some embodiments, the cosine N factor of the material source 118 is in the range of 0 <N ≤ 10, such as in the range of 2 ≤ N ≤ 6. In addition, in an embodiment, the material source 118 is optimally positioned and close to the substrate deposition plane 126 compared to the non-optimal configuration of the prior art. As a result, the jet plume 134 of the deposition material is deposited on the substrate deposition plane 126 with higher efficiency than in conventional MBE systems. The significantly shortened travel distance of the source material increases the accumulation rate of the deposition material at the deposition surface inversely proportional to the square. This results in a significant reduction in the mean free path required for the deposition material ejected from the material source, thereby enabling a substantially collision-free state to be maintained at a higher operating pressure (i.e., at a lower vacuum). Another advantageous property of increasing the growth rate is the reduced impact of residual background impurity species within the deposited film.

[0064] "Source utilization" refers to the amount of material (i.e., in terms of volume) that is actually ejected from the material source 118 and intersects the substrate deposition plane 126. Conventional off-axis MBE reactor configurations can achieve a source utilization of up to about 25%. In contrast, since the embodiments of the present invention provide a plume 134 that is spatially configured to achieve an optimized target flux inhomogeneity, a maximized accumulation rate and thus a higher flux utilization are achieved. In addition, the embodiments of the present invention use a more directional material source (e.g., a cosine N factor of up to about 6) than in conventional MBE (e.g., a cosine N factor of about 1 to 2). Therefore, when optimally configured, the embodiments of the present invention further improve the source utilization. For example, the source utilization using the embodiments of the present invention can be from about 30% to about 50%. Therefore, the embodiments of the present invention result in a more efficient film formation process than conventional MBE, and achieve the best target flux inhomogeneity at the highest accumulation rate compared to conventional MBE.

[0065] In addition, embodiments of the present invention provide optimal high vacuum conditions for maintaining a sufficiently large mean free path of film-forming substances, which enables the formation of high-quality epitaxial films. The mean free path is the average distance covered by a moving particle (e.g., an atom, molecule, photon) between successive impacts (or collisions) that change its direction, energy, or other properties. More specifically, the embodiments provide high vacuum conditions for maintaining a mean free path of film-forming substances that is greater than the distance between the material source 118 and the substrate deposition plane 126. For example, in order to target a region that only includes a region that generates a flux Φ Al = 5 x 10 19 Atom·m –2 ·s –1 The example case of a material source beam of elemental Al atoms provides a mean free path L of Al atoms. MFP = 1 m, where the Al atoms are directed into a reactor that is uniformly and completely filled with inert molecular nitrogen (N2) at 300°K, with the maximum working chamber pressure limited to 10 –6 In practice, the longest unobstructed optical path length required for an atom to travel from the source to the deposition plane should be at most L MFP / 2. Another limitation is the effect of background impurity type and content specific to the type of film to be deposited. If the desired growth rate (i.e., the time τ for accumulating a monolayer of the desired material on the deposition plane) is ML ) is longer than the time τ required to accumulate an equivalent monolayer of impurity species imp (i.e., τ imp ≥λ·τ ML ) is at least λ ≥ 10 3 –10 4This places an upper limit on the acceptable residual impurity pressure in the reactor at about 10 –9 –10 –10 Entrust.

[0066] Therefore, the mean free path of the ejected species generated by the material source is assumed to be ballistic and collisionless before interacting with the deposition plane. In addition, the base pressure of the reactor is assumed to be free of contaminant species and to have no contribution to the flux profile generated at the deposition plane.

[0067] See again Figure 2 and Figure 3 , a method for configuring a material deposition system includes determining the position of a material source in order to improve the balance between film quality and film growth rate. More than one material source may be optimized, wherein the axis of symmetry of each material source points to a point offset from the rotation axis of the substrate. For example, an embodiment includes determining a minimum lateral distance X and a minimum orthogonal distance Z for a given material source and a tilt angle, wherein the material source has given parameters such as an outlet hole and a material jet spatial distribution (e.g., a given cosine N factor). In another example, an embodiment includes determining a tilt angle for a given material source and a given lateral distance X and an orthogonal distance Z, wherein the material source has given parameters such as an outlet hole and a material jet spatial distribution (e.g., a given cosine N factor). In some embodiments, the recommended material source position (and / or angle) may be tested, and one or more of the tilt angle α, the lateral distance, the orthogonal distance, the desired growth rate, and the outlet hole geometry may be dynamically modified after testing to meet the desired layer uniformity. In some implementations, if the desired layer uniformity is not met (e.g., deemed unattainable), the desired layer uniformity can be changed to a new value, and then new material source position parameters can be determined to meet the new value. In some implementations, the calculation of the relative position between the material source and the substrate can be performed for multiple material sources used together. That is, in some implementations, determining the position of a material source takes into account when a material source is used together with an additional material source. See Figure 8 The method of the present invention is described in more detail.

[0068] Optimization of material source placement

[0069] Figures 4 to 7 is an example of a graph of the configuration space for certain positions of the material source 118 relative to the substrate deposition plane 126, wherein the calculated film non-uniformity is plotted against the coordinates X and Z of the material source 118. SUB (indicating the area of ​​film formation), Figures 4 to 7The configuration space shown in the corresponding curve diagram is unique. The method is not limited to Figures 4 to 7 The configuration spaces shown in the graph of ; these configuration spaces are just examples. SUB For any combination of values ​​of , there exists a configuration space suitable for supporting a continuous, high-throughput film formation process using MBE. Table 1 shows the Figures 4 to 7 The configuration space corresponding to the curve graph shown in .

[0070] Table 1: Example configuration space

[0071]

[0072] exist Figure 4 , the curve 300 shows that when the cosine N factor = 2, the VFP tilt angle α = 45° and R SUB = 1.5. Note that the X coordinate, Z coordinate, and R SUB is dimensionless. Graph 300 shows a film non-uniformity region of >15%, a film non-uniformity region of 10%, a film non-uniformity region of 5%, a film non-uniformity region of 2%, a film non-uniformity region of 1%, a film non-uniformity region of 0.5%, and a film non-uniformity region of 0.3%, each of which is plotted based on the distance X and Z of the material source 118 relative to the substrate deposition plane 126. Curve 310 forms a boundary between the film non-uniformity regions of >15% and 10%. Curve 312 forms a boundary between the film non-uniformity regions of 10% and 5%. Curve 314 forms a boundary between the film non-uniformity regions of 5% and 2%. Curve 316 forms a boundary between the film non-uniformity regions of 2% and 1%. Curve 318 forms a boundary between the film non-uniformity regions of 1% and 0.5%. Curve 320 forms a boundary between the film non-uniformity regions of 0.5% and 0.3%. Note that there may be some islands 317 of 1% film non-uniformity in the 2% film non-uniformity region (i.e., near the apex of curve 316). Likewise, there may be some islands of 0.5% film non-uniformity in the 1% film non-uniformity region (i.e., near the apex of curve 318). Likewise, there may be some islands of 0.3% film non-uniformity in the 0.5% film non-uniformity region (i.e., near the apex of curve 320).

[0073] For a given inhomogeneity value, the fastest growth rate can be achieved by providing the shortest possible distance from the exit hole 130 of the material source 118 to the substrate deposition plane 126. Thus, the growth rate can be achieved by selecting the shortest possible X and Z distances (i.e., where R src-sub =(X 2 + Z 2 )1 / 2 The fastest growth rate is achieved at a point where the source has a minimum (X and Z) distance. Short X and Z distances are desirable because the shorter the distance from the source to the formation surface, the higher the growth rate, i.e., the higher the yield of the MBE system. By way of example and with reference to graph 300, if 2% non-uniformity is a goal of the film formation process and the highest possible growth rate is desired, then point A is selected near the vertex and just inside curve 314 to achieve the shortest possible distances X and Z, which in turn achieves the highest possible growth rate. In this example and corresponding to point A, a material source 118 having a VFP tilt angle α=45° (with a cosine N factor=2) is set to a distance X of about 2.4 and a distance Z of about 2 to achieve a non-uniformity of about 2%. In another example and corresponding to point B, a material source 118 having a VFP tilt angle α=45° (with a cosine N factor=2) is set to a distance X of about 3 and a distance Z of about 2.6 to achieve the highest possible growth rate at a non-uniformity of about 1%.

[0074] exist Figure 5 , the graph 400 shows that when the cosine N factor of the material source 118 = 3, the VFP tilt angle α = 45° and R SUB = 1.5. Note that the X coordinate, Z coordinate, and R SUB is dimensionless. Graph 400 shows a film non-uniformity region of >15%, a film non-uniformity region of 10%, a film non-uniformity region of 5%, a film non-uniformity region of 2%, a film non-uniformity region of 1%, and a film non-uniformity region of 0.5%, which is drawn according to coordinates X and Z of material source 118. Curve 410 forms a boundary between the film non-uniformity regions of >15% and 10%. Curve 412 forms a boundary between the film non-uniformity regions of 10% and 4%. Curve 414 forms a boundary between the film non-uniformity regions of 4% and 2%. Curve 416 forms a boundary between the film non-uniformity regions of 2% and 1%. Curve 418 forms a boundary between the film non-uniformity regions of 1% and 0.5%. Note that there may be some islands of 0.5% film non-uniformity in the 1% film non-uniformity region (i.e., near the vertex of curve 418).

[0075] In one example and corresponding to point A of graph 400, a material source 118 having a VFP tilt angle α=45° (where the cosine N factor=3) is positioned at a distance X of about 3.2 and a distance Z of about 2.6 to achieve a non-uniformity of about 1%. In another example and corresponding to point B of graph 400, a material source 118 having a VFP tilt angle α=45° (where the cosine N factor=3) is positioned at a distance X of about 4.2 and a distance Z of about 3.5 to achieve a non-uniformity of about 0.5%. Thus, for a non-uniformity of 1%, the X distance at which the material source 118 is located should be greater when the cosine factor is 3 (point A of graph 400) than when the cosine factor is 2 (point B of graph 300).

[0076] exist Figure 6 , the graph 500 shows that when the cosine N factor of the material source 118 is 6, the VFP tilt angle α is 45° and R SUB = 1.5. Note that the X coordinate, Z coordinate, and R SUB Is dimensionless. Graph 500 shows a film non-uniformity region of >15%, a film non-uniformity region of 10%, a film non-uniformity region of 5%, a film non-uniformity region of 2%, a film non-uniformity region of 1%, and a film non-uniformity region of 0.5%, which is drawn according to coordinates X and Z of material source 118. Curve 510 forms a boundary between the film non-uniformity region of >15% and 10%. Curve 512 forms a boundary between the film non-uniformity region of 10% and 5%. Curve 514 forms a boundary between the film non-uniformity region of 5% and 2%. Curve 516 forms a boundary between the film non-uniformity region of 2% and 1%. Curve 518 forms a boundary between the film non-uniformity region of 1% and 0.5%. Note that there may be some islands of 5% film non-uniformity in the 10% film non-uniformity region (i.e., near the vertex of curve 512). Likewise, there may be some islands of 2% film non-uniformity in the 5% film non-uniformity region (i.e., near the apex of curve 514). Likewise, there may be some islands of 1% film non-uniformity in the 2% film non-uniformity region (i.e., near the apex of curve 516). Likewise, there may be some islands of 0.5% film non-uniformity in the 1% film non-uniformity region (i.e., near the apex of curve 518).

[0077] In one example and corresponding to point A of graph 500, a material source 118 having a VFP tilt angle α=45° (where cosine N factor=6) is positioned at a distance X of about 3.6 and a distance Z of about 2.6 to achieve a non-uniformity of about 1%. In another example and corresponding to point B of graph 500, a material source 118 having a VFP tilt angle α=45° (where cosine N factor=6) is positioned at a distance X of about 3.7 and a distance Z of about 2.7 to also achieve a non-uniformity of about 1%, but at a growth rate slightly lower than the growth rate at point A. Thus, for a non-uniformity of 1%, the X distance at which the material source 118 is positioned when the cosine factor N=6 (points A or B of graph 500) should be greater than when the cosine factor is 3 (point A of graph 400), and greater than when the cosine factor is 2 (point B of graph 300).

[0078] exist Figure 7 6, the curve 600 shows that when the VFP tilt angle α = 30°, the cosine N factor of the material source 118 = 3 and R SUB = 1.5. Note that the X coordinate, Z coordinate, and R SUB Is dimensionless. Graph 600 shows a film non-uniformity region of >15%, a film non-uniformity region of 10%, a film non-uniformity region of 5%, a film non-uniformity region of 2%, a film non-uniformity region of 1%, and a film non-uniformity region of 0.5%, which is drawn according to coordinates X and Z of material source 118. Curve 610 forms a boundary between the film non-uniformity region of >15% and 10%. Curve 612 forms a boundary between the film non-uniformity region of 10% and 5%. Curve 614 forms a boundary between the film non-uniformity region of 5% and 2%. Curve 616 forms a boundary between the film non-uniformity region of 2% and 1%. Curve 618 forms a boundary between the film non-uniformity region of 1% and 0.5%. Note that some islands of 1% film non-uniformity may exist in the 2% film non-uniformity region (i.e., near the vertex of curve 616). Likewise, there may be some islands of 0.5% film non-uniformity in the 1% film non-uniformity region (ie, near the apex of curve 618).

[0079] In one example and corresponding to point A of graph 600, a material source 118 having a VFP tilt angle α = 30° (cosine N factor = 3) is set to a distance X of about 3 and a distance Z of about 3.3 to achieve a non-uniformity of about 1%. In another example and corresponding to point B of graph 600, a material source 118 having a VFP tilt angle α = 30° (cosine N factor = 3) is set to a distance X of about 3.05 and a distance Z of about 3.35 to also achieve a non-uniformity of about 1%, but at a growth rate slightly lower than the growth rate at point A. Comparing point A or B of graph 600 with point A of graph 400, it can be seen that for the same cosine factor N = 3, changing the tilt angle α from 30º to 45º affects the X and Z distances to achieve a non-uniformity target of 1%.

[0080] Figure 8 7 is a flow chart of an example of a method 700 for configuring an offset material source in a material deposition system to improve the balance between film quality and film growth rate. An embodiment of the method includes selecting values ​​for certain variables and mathematically modeling the material deposition process to optimize other variables. For example, for a given material source type and tilt angle, the lateral distance X and the orthogonal distance Z may be optimized, such as minimizing X and Z to achieve a desired layer deposition uniformity for a desired layer growth rate. In other example embodiments, the distances X and Z may be fixed, and the tilt angle may be determined to achieve a desired layer deposition uniformity for a desired growth rate. In other embodiments, the size of the substrate (R ) may be varied. SUB ) or cosine N source type to meet the desired deposition uniformity and growth rate.

[0081] Conventional MBE systems are characterized by the use of relatively slow growth rates as a means to achieve precise epi layer thickness, high uniformity flux, abrupt interfaces between heterogeneous epi layers, high uniformity films, high structural films, and crystalline films of high electronic quality. For example, the growth rate in a conventional MBE system can be from about 0.1 monolayer per second (ML / s) to about 10 ML / s. In addition, MBE systems typically require specialized but simple high vacuum preparation methods to achieve the low residual base pressure required for low levels of unintentional impurities in the deposited film. This upfront investment in reactor preparation to achieve a vacuum state suitable for high-quality epitaxy is a key difference when compared to high-pressure CVD reactors. In addition, material sources (such as solid-liquid interstitial sources) require the front-end atmosphere to be pre-loaded into the reactor, and once the reactor vacuum is obtained again, the material source will subsequently become inaccessible. Therefore, high-throughput film formation processes require high flux utilization efficiency to manage the cost per unit area ($ / m2) of the epi layer for a given lifetime of material source activity and total deposited film thickness. 2Another desirable property is the scalability of reactor size to increase the total deposition area for a given deposition cycle while maintaining low flux non-uniformity. This allows the cost per unit area (e.g., $ / m 2 ) and cost of ownership are further reduced. It should be appreciated that the increased deposition surface area may comprise a single large area substrate or multiple smaller substrates advantageously positioned across the deposition plane.

[0082] In conventional MBE systems, there is a direct correlation between the growth rate and the distance between the material source and the formation surface (hereinafter referred to as the distance from the source to the formation surface). More specifically, the shorter the distance from the source to the formation surface, the faster the potential growth rate. The longer the distance from the source to the formation surface, the slower the growth rate. Therefore, in order to obtain a highly uniform film, a conventional MBE system achieves a slow growth rate by placing the material source at a long distance from the formation surface and exceeding the optimal position as taught herein. Therefore, in order to achieve a high growth rate in a conventional MBE system, the distance from the source to the formation surface must be significantly reduced, but doing so generally compromises the uniformity of the film on the deposition plane and limits the maximum deposition surface area (i.e., limits the scalability of the process).

[0083] In contrast, according to some embodiments, method 700 provides a technique for achieving high growth rates in an MBE process while still achieving high quality films. In one example, method 700 provides a film having a thickness uniformity of about ≥ 95% (i.e., about ≤ 5% non-uniformity) on a deposition plane. In another example, method 700 provides a film having a uniformity of about ≥ 99% (i.e., about ≤ 1% non-uniformity). Method 700 may include the following steps.

[0084] At step 710, a rotation mechanism is provided. The rotation mechanism rotates the substrate about a central axis of a substrate deposition plane of the substrate. In some embodiments, the diameter of the substrate is equal to or greater than 6 inches (150 mm).

[0085] In step 714, a material source is selected, including the elemental substance of the material and the type of the material source. The material source and the substrate are contained in a vacuum environment. In one example of selecting a material source, if the film to be formed contains gallium, the selected substance is a gallium substance. In another example, if the film to be formed contains aluminum, the selected substance is an aluminum substance. Subsequently, the type of material source 118 (i.e., gas, liquid, and solid) is selected based on the selected substance. In one example, if the selected substance is gallium, a Knudsen gap permeation cell for liquid evaporation of gallium is selected. In some embodiments, the material source may be a cosine N source having a beam flux profile of, for example, about N = 1 to about N = 6, which is impossible to achieve using conventional MBE. Additional (i.e., multiple) material sources may be included, wherein the material source is used together with the additional material source; that is, for simultaneously depositing different materials onto the substrate. In some embodiments, the material source includes a nitrogen plasma source and an oxygen plasma material source that emit active nitrogen.

[0086] Each material source 118 has: an outlet hole 130 having an outlet hole plane; and a predetermined material ejection spatial distribution starting from the outlet hole plane. If more than one material source is to be used, a predetermined material ejection spatial distribution is obtained for each material source. In some embodiments, the outlet hole has an outlet hole geometry, and the method further comprises selecting the outlet hole geometry. The predetermined material ejection spatial distribution has an axis of symmetry that intersects the substrate at a point offset from the central axis, wherein the outlet hole is positioned at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate. For a cosine N factor material source, a predetermined (e.g., empirical) cosine N factor and material ejection spatial distribution may be obtained from a supplier of the selected material source 118. In one example, the cosine N factor of the selected material source 118 is greater than or equal to 2, such as about 3, or up to about 6.

[0087] At step 718, either i) a VFP tilt angle α is set when the selected material source 118 is installed, or ii) an orthogonal distance and a lateral distance of an exit hole of the material source are set. The VFP tilt angle α of the selected material source 118 may be about 30° to less than 90° in one example, about 30° to about 60° in another example, or about 45° in another example. In one example, the selected VFP tilt angle α is 45°. The plume 134 of the material source 118 is provided at a different tilt angle than in conventional MBE, in which the plume 134 of the material source 118 is provided substantially orthogonal to the substrate deposition plane 126.

[0088] At step 726, the desired accumulation of material on the substrate is selected to achieve a desired layer deposition uniformity for a desired growth rate. In some embodiments, the target (desired) uniformity (or non-uniformity) value may be expressed as a flux. In some embodiments, the flux or film uniformity may be expressed as a tolerance value. In one example, the selected target thickness uniformity on the substrate deposition plane 126 is 99% (or equivalently, 1% non-uniformity). In the present disclosure, the target value may also be referred to as the desired value. In determining the parameters for the desired layer uniformity and the desired growth rate, the deposition surface area (i.e., the area of ​​the substrate deposition plane 126) is taken into account. In one example, the substrate 122 is a 3 inch wafer (R SUB = 1.5). In another example, the substrate 122 is a 6-inch wafer (R SUB = 3). In yet another example, the substrate 122 is an 8-inch wafer (R SUB = 4). In yet another example, the substrate 122 is a 12-inch (300 mm) wafer (ie, R SUB = 6).

[0089] At step 730, if the tilt angle was set in step 718, the minimum values ​​of the orthogonal distance and the lateral distance for achieving the desired uniformity of layer deposition are determined. That is, the shortest distances X and Z for positioning the material source 118 are determined using the graph of the configuration space corresponding to the selections made in each of steps 714, 718, and 726. For example, Figure 5 The graph 400 shows the SUB = 1.5 corresponding to a cosine N factor = 3 (selected in step 714), a VFP tilt angle α = 45° (selected in step 718), and a target non-uniformity = 1% (selected in step 726). The growth rate of the film is increased by determining the shortest distances X and Z corresponding to the selected target uniformity. In some embodiments, the determined orthogonal distance and the determined lateral distance of the material source from the substrate deposition plane are equal to or less than the mean free path of the material emitted from the material source.

[0090] At step 730, if the orthogonal distance and the lateral distance were set in step 718, the tilt angle is determined using the set orthogonal distance and the set lateral distance to achieve the desired layer deposition uniformity.

[0091] In some embodiments, additional material sources may be used, and step 730 includes determining the tilt angle or orthogonal and lateral distances when all material sources are used together.

[0092] In some embodiments, the method of configuring the material deposition system is completed after step 730, for example, if the determined orthogonal and perpendicular distances can achieve the desired layer deposition uniformity and growth rate. In an example scenario, a point is selected within the 1% film non-uniformity region of the graph 400 that corresponds to the shortest or nearly shortest possible distances X and Z. In one example, point A near the vertex of curve 416 of the graph 400 is selected. Point A corresponds to a distance X of about 3.2 and a distance Z of about 2.6. Other points within the 1% film non-uniformity region of the graph 400 may result in longer distances X and Z, resulting in a slower growth rate. Therefore, by selecting point A near the vertex of curve 416 in the graph 400, the position of the material source 118 relative to the substrate deposition plane 126 is set using the shortest or nearly shortest possible distances X and Z. Since the closer the material source 118 is to the substrate deposition plane 126, the higher the growth rate will be, the growth rate is improved.

[0093] In other embodiments, the determined tilt angles or the determined minimum values ​​of the orthogonal distances and lateral distances may be tested to see if further optimization is needed. At step 734, the configuration of the material source 118 relative to the substrate deposition plane 126 determined in steps 714, 718, 726, and 730 is physically implemented and tested to determine whether the target film non-uniformity is achieved, combined with an appropriate growth rate to support a high throughput film formation process. For example and with reference to Figure 2 , the material source 118 having a certain cosine N factor (as determined in step 714) is positioned at the distances X and Z from the substrate deposition plane 126 determined in step 730 and at the VFP tilt angle α = 45° selected in step 718. The vacuum environment 114 of the high vacuum reaction chamber 100 is pumped down to a certain vacuum pressure (e.g., about 10 -11 To about 10 -7 The substrate 122 is rotated using a rotation mechanism of step 710, and the material source 118 is activated. Periodically, the thickness of the epitaxially grown film is measured at a plurality of sampling points along the substrate deposition plane 126. This measurement may be performed, for example, using a reflection high energy electron diffraction (RHEED) system directed toward the substrate deposition plane 126.

[0094] At decision step 738, based on the measurements made in step 734, it is determined whether the desired non-uniformity and growth rate that are suitably high to support a high throughput film formation process selected in step 726 have been achieved. If the target non-uniformity and growth rate are achieved, then the method 700 ends. Any configuration of the material source 118 relative to the substrate deposition plane 126 is a balance between film quality and film growth rate. Therefore, if the target non-uniformity and growth rate are not achieved, then the desired film quality or the desired film growth rate may be relaxed somewhat. In one example, if the target non-uniformity is not achieved, then the method 700 may proceed to step 742.

[0095] At step 742, if the test does not meet the desired layer deposition uniformity, at least one of the tilt angle, desired growth rate, lateral distance, and orthogonal distance is changed. For example, the desired growth rate may be reduced for the particular application (semiconductor product, manufacturing / cost target). The method 700 then returns to step 730, where another point is selected within the desired film non-uniformity region of a certain graph of the configuration space, where the new point corresponds to a slightly larger distance X or Z, or both, and, therefore, a slightly reduced growth rate. In another example, the lateral and / or orthogonal distances are adjusted, such as increasing their values ​​if a slower growth rate is acceptable. In another example, the tilt angle or exit hole geometry is changed, and another iteration of the method 700 is performed, where the orthogonal distance and lateral distance are re-determined using the spatial distribution of material ejection corresponding to the new tilt angle or exit hole geometry.

[0096] In some implementations, if the desired target is not achieved, the desired layer deposition uniformity of the film may be changed at step 746. For example, for a certain application, it may be acceptable to reduce the desired uniformity of the film or increase the non-uniformity of the film. The method 700 returns to step 726, where the uniformity value is reduced (i.e., the non-uniformity value is increased), and then another iteration of the method 700 begins.

[0097] In some embodiments, the rotating mechanism and the material source are housed in a reaction chamber, and method 700 may further include using the lateral distance and the orthogonal distance to determine the radius R of the substrate. SUB The step 750 of scaling the size of the reaction chamber based on the relationship of the material source. For example, once the minimum distance for positioning the material source is determined, the size of the reaction chamber can be reduced. Reducing the size of the reaction chamber can provide some benefits, such as reducing the manufacturing cost of the chamber and taking up less space in the manufacturing facility.

[0098] Method 700 may also include step 760 of emitting material to form a semiconductor layer. The substrate is heated while the material is emitted onto the substrate. Step 760 may include using an optimal positioning of the material source relative to the substrate, as determined in steps 710 to 738. The tilt angle, orthogonal distance, and lateral distance are dynamically adjustable so that the position can be adjusted depending on the material source used, which can vary between runs. The tilt angle, orthogonal distance, and lateral distance can be dynamically adjusted by adjusting the position of the substrate or by adjusting the position of the material source.

[0099] The VFP tilt angle may be selected a priori in step 718 with reference to the type of material source 118 selected. For example, if the material source 118 is a single, open orifice crucible of a liquid interstitial source, then for a given material volume capacity and the location of the melt surface relative to the exit orifice 130 (which is the exit orifice), the tilt angle of the material source is limited by the tilt relative to the vertical direction of the crucible (if placed in a gravitational field). In general, if the melt surface is sufficiently displaced from the exit orifice 130, then the VFP tilt angle may be selected a priori ... C A well-defined VFP is produced at the outlet plane defined by a single outlet hole 130 of a cylindrical crucible. In addition, the VFP at the outlet hole 130 can be determined by the hole diameter D O and hole depth L O Characterize so that D O / L O <1 and D O <D C Therefore, in fact, at 0 o < α < 70 o and more preferably at 30 o < α < 60 o , and usually around 40 o < α < 50 o Liquid sources are suitable. The standard configuration of this large volume material source is α = 45 o In contrast, the gas injector material source is not constrained by the internal details of the source and can be o ≤ α < 90 o Obviously, a gas injector material source type is capable of grazing incidence applications, where 70 o < α < 90 o .

[0100] In the operation of the high vacuum reaction chamber 100, where the position of the material source 118 has been improved relative to the substrate deposition plane 126 according to the method 700, in one example, the substrate deposition plane 126 (i.e., the substrate 122) is rotating. There is a speed at which the material is ejected from the material source 118, and therefore, there is a rate at which the material arrives at the substrate deposition plane 126. The arrival rate can be expressed, for example, in terms of the number of atoms or materials per unit area per unit time. When the high vacuum reaction chamber 100 is operating, the rotation speed of the substrate 122 can be, for example, about 1 rpm to about 1000 rpm. However, the minimum rotation speed of the substrate 122 is determined by the arrival rate of the material per unit area per unit time. That is, there is a correlation between the time it takes to rotate one circle around the substrate 122 and the arrival rate of the material. The material accumulation is averaged relative to one rotation of the substrate 122. For high growth rates suitable for supporting high-throughput systems, the rotation speed of the substrate 122 can be, for example, about tens of rpm to about hundreds of rpm. Although there is a lower limit on the base deposition plane rotation speed relative to the minimum material incident arrival rate, faster rotation speeds may generally be advantageous.

[0101] In summary, the method 700 configures the position of the material source 118 relative to the substrate deposition plane 126 to epitaxially grow high-quality films at a growth rate suitable for supporting a continuous, high-throughput film formation process, such as a continuous, high-throughput semiconductor manufacturing process. For film growth rates that are suitably high to support a high-throughput film formation process, the distance between the material source 118 and the substrate deposition plane 126 is suitably short, which is not possible using conventional MBE; for example, the method can increase the film growth rate by at least 1 angstrom per second compared to conventional MBE.

[0102] Oxide-based semiconductor structures

[0103] Oxide-based semiconductor devices can be produced using the above system, where the material sources are placed at positions and angles specifically designed to achieve high uniformity film layers at high throughput growth rates. P-type doping of various materials can also be achieved, including P-type doped Mg-based layers. For example, magnesium-based and zinc-based oxides can be formed, including Mg X Zn 1-X O-based oxide layers, where x > 0, p-type doped with Mg x Zn 1-xO layer, where 0 ≤ x < 0.45, or a MgZnON layer. In some embodiments, the oxide-based layer is a superlattice comprising sublayers of: a) MgO and ZnO, b) MgZnO and ZnO, or c) MgZnO and MgO. In some embodiments, the oxide-based layer is a p-type doped layer, and the material is emitted using at least one of: active nitrogen plasma, nitrogen oxide (N2O), ammonia (NH3), phosphorus, oxygen plasma, or defective Mg or Zn. In the present disclosure, DUV LEDs will be described; however, the same techniques can be used to manufacture other types of semiconductors.

[0104] Fig. 9 900 is a cross-sectional view of an example of a plasma processing system 900 that can be used to form high-quality oxide-based films on a substrate 901. The plasma processing system 900 includes: a reaction chamber 904; a heater 908; a nitrogen plasma source 912 that produces a nitrogen species 916; a Mg (magnesium) source 920 that produces a Mg species 924; a P (phosphorus) source 928 that produces a P species 932; an Al (aluminum) source 936 that produces an Al species 940; a Zn (zinc) source 944 that produces a Zn species 948; and an oxygen plasma source 952 that produces an oxygen species 956. The emission of the Mg species 924 is controlled by a baffle 960. The emission of the Zn species 948 is controlled by a baffle 964. The emission of the nitrogen plasma source 912, the P source 928, the Al source 936, and the oxygen plasma source 952 are each similarly controlled by baffles and are not shown in the figure for clarity. Fig. 9 900. The plasma processing system 900 also includes a vacuum pump 972 that is fluidly coupled to the reaction chamber 904. A positioning mechanism (not shown) may be coupled to each of the material sources 912, 920, 928, 936, 944, and 952 to adjust the position (lateral distance, orthogonal distance, and tilt angle) of the material source relative to the substrate 901 to meet desired layer deposition specifications. A positioning mechanism (not shown) may also be coupled to the substrate 901 to adjust and move the position of the substrate horizontally (in the direction of the plane of the substrate) or vertically (perpendicular to the plane of the substrate).

[0105] The plasma processing system 900 may also include an optical detector (not shown) and / or a reflection high energy electron diffraction (RHEED) system (not shown). The plasma processing system 900 includes a controller (not shown), which may be any computing device, such as a handheld computer, a tablet computer, a laptop computer, a desktop computer, a centralized server, a mobile computing device, etc.

[0106] The substrate 901 is placed in a reaction chamber 904, where a plasma treatment process is performed on the substrate to produce a defect-free oxide-based film on the substrate 901. The substrate 901 can be rotated about a central rotation axis AX. The substrate 901 can be held or manipulated using, for example, a wafer handling system (not shown). The substrate 901 has a certain radius R SUB For example, the radius R of the 6-inch substrate 901 is SUB The radius R of the substrate 901 is 3 inches and 8 inches SUB The radius R of the substrate 901 is 4 inches and 12 inches SUB 6 inches, and so on. The side of the substrate 901 facing the material source is a film-forming surface 906. The film-forming surface 906 is a surface of the substrate 901 to which the plasma treatment process is performed in preparation for the subsequent film-forming process. The substrate 901 may also have a backside coating (not shown) for absorbing heat from the heater 908.

[0107] Although the material source is located on the film-forming surface 906 side of the substrate 901, the heater 908 is located on the opposite side of the substrate 901. The heater 908 is used to heat the substrate 901, and in turn heats the film-forming surface 906 of the substrate 901 to a growth temperature T suitable for film growth. g , such as a growth temperature T of about 300°C to about 700°C g In one example, heater 908 is a radiant heater having a heating element made of rhenium.

[0108] The nitrogen plasma source 912 is, for example, an inductively coupled plasma (ICP) source that emits a plasma formed of N* or N2* (shown as nitrogen species 916). Reactive nitrogen is an allotrope of nitrogen and is formed by an electric discharge through a nitrogen flow. Unlike the inactive nitrogen used in conventional film formation, which has a very high bond energy that can only dissociate at temperatures up to 2,700 Kelvin (K), the active nitrogen can dissociate at relatively low temperatures (e.g., 700-800K). The nitrogen plasma source 912 includes an excitation device (not shown) and a pressure reducing orifice (not shown). In addition, one or more mass flow controllers (MFCs), shown as MFCs 976, are fluidly connected to the nitrogen plasma source 912 via a gas line 980. The MFC 976 controls the gas flow rate flowing out of a gas source (not shown) containing, for example, N2. In operation, N2 feed gas is supplied to nitrogen plasma source 912 via MFC 976 and then dissociated by energy provided by an excitation device (not shown) to produce nitrogen species 916. Nitrogen species 916 enter a deionizer / aperture (not shown), where substantially all of the nitrogen species 916 in an excited (i.e., ionized) state are neutralized before exiting the deionizer / aperture (not shown). In one example, the beam pressure of nitrogen species 916 is 10 -8 Tor, which is the beam pressure suitable for doping epitaxial films.

[0109] The Mg source 920 is, for example, a permeable cell that emits Mg species 924, which may be controlled using a baffle 960. In another example, the Mg source 920 generates the Mg species 924 as a precursor gas. Using a permeable cell and a precursor gas to generate the Mg species 924 reduces the complexity and processing costs associated with the plasma processing system 900. The Mg species 924 is emitted by sublimating solid magnesium in the Mg source 920. The flux of the Mg species 924 is represented as Φ(Mg). The flux is a measure of the number of atoms that strike the substrate surface per second and is expressed as beam pressure. In one example, Φ(Mg) is approximately 10 –7 Entrust.

[0110] The P source 928 is a permeable cell that emits a P substance 932, which can be controlled using a baffle (not shown). The P substance 932 can be elemental phosphorus or an allotrope of phosphorus, such as diphosphorus (P2) produced by sublimating gallium phosphide (GaP) or cracking tetraphosphorus (P4) using a conventional cracker. The P substance 932 acts as a p-type dopant during film formation and helps to form a highly uniform oxide-based film. The flux of the P substance 932 is represented by Φ(P). In one example, Φ(P) is about 10 –7 Entrust.

[0111] The Al source 936 is, for example, a permeable cell that emits an Al substance 940, which can be controlled using a baffle (not shown). In another example, the Al source 936 generates the Al substance 940 as a precursor gas. Using a permeable cell and a precursor gas to generate the Al substance 940 reduces the complexity and processing costs associated with the plasma processing system 900. The Al substance 940 is, for example, a single substance of aluminum (e.g., pure aluminum). The flux of the Al substance 940 is represented by Φ(Al). In one example, Φ(Al) is about 10 –7 In another embodiment, indium single substance or gallium single substance is used instead of aluminum substance.

[0112] The Zn source 944 is, for example, a permeable cell that emits Zn species 948, which can be controlled using a baffle 964. In another example, the Zn source 944 produces the Zn species 948 as a precursor gas. The use of a permeable cell and a precursor gas to produce the Zn species 948 reduces the complexity and processing costs associated with the plasma processing system 900. In the example where the Zn source 944 is a permeable cell, the Zn species 948 is formed by sublimating solid zinc within the Zn source 944. The flux of the zinc species 948 is represented by Φ(Zn). In one example, Φ(Zn) is approximately 10 –7 Entrust.

[0113] The oxygen plasma source 952 is, for example, an ICP source that emits a plasma formed by one or more gases selected from the group consisting of: reactive atomic oxygen (O*), molecular oxygen (O2*), oxygen nitrogen (ON), N*, and N2*. The resulting plasma is shown as oxygen species 956. In another example, the oxygen source 952 is a source of pure oxygen supplied to the reaction chamber 904. In the example where the oxygen plasma source 952 is a plasma source, the oxygen plasma source 952 includes an excitation device (not shown) and a deionizer / aperture (not shown). In addition, one or more mass flow controllers (MFCs) shown as MFC 984, MFC 988, and MFC 992 are fluidly coupled to the oxygen plasma source 952 via a gas line 996. MFC 984, MFC 988, and MFC 992 control the gas flow rate flowing out of a gas source (not shown) containing, for example, N2, O2, or N2O. In one operating example, N2 and O2 are combined in a fixed ratio and supplied to the oxygen plasma source 952, and then dissociated in their combined form by energy applied by an excitation device (not shown) to produce oxygen species 956. The oxygen species 956 enters a deionizer / aperture (not shown), where substantially all of the oxygen species 956 in an excited (i.e., ionized) state are neutralized before exiting the deionizer / aperture (not shown). In one example, 99% O2 is mixed with 1% N2 to produce a plasma of oxygen species 956, which then produces a p-type doped film on the film-forming surface 906. The oxygen species 956 improves the operating efficiency of the plasma processing system 900 by reducing the required processing temperature level and operating cost of the plasma processing system 900. In some embodiments, p-type doping of the oxide (i.e., forming a p-type oxide layer) is achieved exclusively by: i) replacing (i.e., substituting) some oxygen atoms in the semiconductor crystal structure (e.g., 1 in 1000) with nitrogen, ii) replacing (i.e., substituting) some Mg or Zn atoms in the crystal structure (e.g., 1 in 10) with Al or Ga, or (i) and (ii).

[0114] In one example, film deposition of oxide-based films in the plasma processing system 900 occurs at about 500°C to about 700°C, and in another example at about 600°C. With the oxygen plasma source 952 in place to enhance system efficiency, film growth in the plasma processing system 900 can occur at temperatures as low as 350°C. In contrast, conventional film deposition temperatures for group III-N materials range from about 900°C to about 1,200°C, and the growth temperature tolerance must be controlled within 5°C. The lower deposition temperatures supported by the plasma processing system 900 of embodiments of the present invention enable (1) reduced complexity and reduced cost processing equipment, (2) reduced processing energy usage, and (3) greater growth temperature tolerance compared to conventional systems. The lower growth temperature and greater growth temperature tolerance facilitate high quality film growth on larger substrates, thereby improving production yields.

[0115] A vacuum environment 968 is maintained within reaction chamber 904 by vacuum pump 972. Vacuum pump 972 may be a conventional variable speed vacuum pump that can evacuate reaction chamber 904 at a certain rate referred to as a pumping speed. A valve (not shown) may be associated with vacuum pump 972. A pressure sensor (not shown) may be provided to monitor the vacuum pressure within reaction chamber 904. Vacuum pump 972 is used to maintain a sufficient vacuum pressure within reaction chamber 904. The vacuum pressure within reaction chamber 904 during film formation is, for example, about 10 -11 To about 10 -5 Entrust.

[0116] In another embodiment of the plasma processing system 900, pure oxygen (O2) is supplied to the reaction chamber 904 through a heated tube (not shown) instead of the oxygen plasma source 952. The temperature of the oxygen entering the reaction chamber 904 is, for example, about 200° C. to about 300° C. In one example, the heated tube (not shown) is formed of sapphire.

[0117] The film-forming surface 906 of the substrate 901 is a target of materials delivered from the nitrogen plasma source 912, the Mg source 920, the P source 928, the Al source 936, the Zn source 944, and the oxygen plasma source 952. The shutter 960 is located in the path of the Mg species 924 emitted from the Mg source 920. When opened, the shutter 960 allows the Mg species 924 to hit the film-forming surface 906 of the substrate 901. When closed, the shutter 960 prevents the Mg species 924 from hitting the film-forming surface 906 of the substrate 901. The shutter 964 is located in the path of the Zn species 948 emitted from the Zn source 944. When opened, the shutter 964 allows the Zn species 948 to hit the film-forming surface 906 of the substrate 901. When closed, the shutter 964 prevents the Zn species 948 from hitting the film-forming surface 906 of the substrate 901. Other baffles (not shown) similarly control the impact of the nitrogen species 916 , the P species 932 , the Al species 940 , and the oxygen species 956 on the film-forming surface 906 of the substrate 901 .

[0118] When the reaction chamber 904 is at the desired film growth temperature T g When the substrate 901 is under vacuum pressure, the nitrogen plasma source 912, the Mg source 920, the P source 928, the Al source 936, the Zn source 944, and the oxygen plasma source 952 are turned on. The combined impact of the nitrogen species 916, the Mg species 924, the P species 932, the Al species 940, the Zn species 948, and the oxygen species 956 on the film-forming surface 906 of the substrate 901 forms an oxide-based layer on the film-forming surface 906.

[0119] Fig. 9 The Mg source 920 and the Zn source 944 are shown to be located at a certain lateral distance X from the central rotation axis AX of the substrate 901 and a certain vertical distance Z from the plane of the film forming surface 906. This positioning is shown for exemplary purposes. The lateral distance X and the vertical distance Z are the coordinates of the Mg source 920 and the Zn source 944 relative to the center of the film forming surface 906. In addition, the Mg source 920 and the Zn source 944 are located at a virtual flux plane (VFP) tilt angle α relative to the plane of the film forming surface 906. The nitrogen plasma source 912, the P source 928, the Al source 936, and the oxygen plasma source 952 are each similarly located at a lateral distance X from the central rotation axis AX of the substrate 901 and a vertical distance Z from the plane of the film forming surface 906. Therefore, the Mg source 920, the Zn source 944, the nitrogen plasma source 912, the P source 928, the Al source 936, and the oxygen plasma source 952 are "off-axis" material sources.

[0120] Fig. 10A1 is a cross-sectional view of an example of an LED device structure 1000, which is an example of an oxide-based structure to be manufactured according to some embodiments. The LED device structure 1000 can be used to form, for example, a DUV LED. The DUV LED can operate in the UVC wavelength range of about 100nm to about 280nm. The LED device structure 1000 can be used to form a single complete device, or can be used to form multiple devices as part of a large-scale, high-yield production process. The LED device structure 1000 includes a substrate 1004, on which a plurality of oxide-based layers are deposited. Specifically, the LED device structure 1000 includes a substrate 1004, on which a MgZnO buffer layer 1008, a MgO-MgZnO multilayer 1012, an n-type MgZnO layer 1016, a NID layer 1020, and a p-type MgZnO layer 1024 are sequentially deposited.

[0121] LED device structure 1000 is an example of a lateral PIN diode. NID layer 1020 serves as an intrinsic heterojunction between n-type MgZnO layer 1016 and p-type MgZnO layer 1024. A heterojunction is defined as an interface between two layers of different crystalline semiconductors with unequal band gaps.

[0122] In one example, substrate 1004 is formed of sapphire, calcium chloride, or magnesium oxide, which is substantially transparent to light (e.g., light 1028). In this example, substrate 1004 has a thickness of about 500 μm to about 1,000 μm; further, substrate 1004 has a diameter of about 4 inches to about 12 inches. In another example, substrate 1004 is formed of silicon carbide, silicon, or gallium nitride (GaN), which absorbs light and is therefore not transparent to light 1028.

[0123] The MgZnO buffer layer 1008 is formed of MgZnO and has a thickness of, for example, about 200 nm to about 1 μm. The MgZnO buffer layer 1008 serves to minimize threading dislocations and thus reduce defect density in a film formed over the MgZnO buffer layer 1008 .

[0124] The MgO-MgZnO multilayer 1012 is a superlattice layer formed by a plurality of alternating MgO sublayers 1013a and MgZnO sublayers 1013b, wherein two sublayers 1013a and 1013b are shown for simplicity, but more sublayers may be included. The MgO-MgZnO multilayer 1012 is used to further minimize threading dislocations and thus reduce the defect density in the film formed on the MgO-MgZnO multilayer 1012.

[0125] The n-type MgZnO layer 1016 is formed of MgZnO and is n-type doped with, for example, aluminum, gallium, or indium. For example, aluminum is a Group III metal and has the desirable property of being very easy to evaporate. The n-type MgZnO layer 1016 has a thickness of, for example, about 200 nm to about 1 μm.

[0126] The NID layer 1020 is a superlattice layer of alternating sublayers 1021a and 1021b, wherein for simplicity, sublayers 1021a and 1021b are each shown as two, but more sublayers may be included. Some sublayers may be formed by, for example, intrinsic MgZnO or MgO. In addition, the NID layer 1020 may include one or more quantum well structures formed by narrow bandgap materials. In one example, the NID layer 1020 is mainly formed by MgO (i.e., barrier material) for sublayer 1021a, and includes one or more narrow bandgap ZnO quantum well sublayers 1021b. The NID layer 1020 has a thickness of, for example, about 10nm to about 50nm. In another example, MgZnO or MgZnO-ZnO alloy is used to form the NID layer 1020 into a superlattice structure.

[0127] The p-type MgZnO layer 1024 is formed of, for example, nitrogen-doped MgZnO and has a minimum thickness of, for example, about 200 nm. The p-type doping of the p-type MgZnO layer 1024 is, for example, performed using N* or N2* plasma according to the following reference. Fig.11 The method described above is implemented. In another example, p-type doping of the p-type MgZnO layer 1024 is achieved using an independent nitrogen oxide (N2O) or ammonia (NH3) source. The p-type MgZnO layer 1024 provides the ability to tune the bandgap of the device across a wide wavelength range, while the bandgap tuning capabilities of conventional III-N family films are limited. For example, it is extremely difficult to use only AlN to make UVLEDs that operate at 190 nm (i.e., 6 eV) or below. In some cases, boron-AlN compounds can be used. However, this material requires a high content of nitrogen and a high deposition temperature, both of which may be extremely costly, technically unfeasible and / or commercially unfeasible. In addition, doping the boron-AlN compound into a conductive type is very problematic. In contrast, a p-type MgZnO film can be produced at an easily achievable deposition temperature, and the film can be doped into p-type conductivity by an easily achievable nitrogen content.

[0128] After forming the p-type MgZnO layer 1024, electrical contacts (e.g., anode and cathode; not shown) are formed using standard metallization and photolithography processes. The electrical contacts are formed of, for example, nickel (Ni), palladium (Pd), titanium (Ti), aluminum (Al), titanium nitride (TiN), or titanium aluminum (TiAl).

[0129] In one example, the epitaxial layers of the LED device structure 1000 are deposited so that charge carriers (ie, electrons and holes) move vertically and Fig. 10A Light (ie, photons), shown as light 1028 in FIG. 1 , is also emitted vertically. In another example, the epitaxial layers of the LED device structure 1000 are deposited such that the charge carriers move laterally, and light is also emitted laterally. Fig. 10A The term "lateral" in the context refers to a direction substantially along the plane of layer growth, while the term "vertical" refers to a direction substantially perpendicular or normal to the plane of layer growth.

[0130] In operation, the n-type MgZnO layer 1016 generates electrons that move vertically into the NID layer 1020. Continuing with the example, the p-type MgZnO layer 1024 emits holes that move vertically into the NID layer 1020. The charge carriers interact and recombine within the NID layer 1020 and are emitted from the LED device structure 1000 as light 1028. In an example where the LED device structure 1000 is a UVC LED, the NID layer 1020 is designed to emit light in a wavelength range of about 100 nm to about 280 nm. In an example where the light is substantially transparent to the substrate 1004, a certain percentage of the light emitted from the NID layer 1020 is emitted directly through the substrate 1004.

[0131] Fig. 10B 1 is a cross-sectional view of an optoelectronic device embodied as an LED device structure 1030, wherein a multi-region stack 1031 includes a crystal polarity having an oxygen polar crystal structure or a metal polar crystal structure along a growth direction 1032. The growth direction 1032 is Fig. 10B 1031. The LED device structure 1030 can be used to form, for example, a DUV LED. The DUV LED can operate in the UVC wavelength range of about 100 nm to about 280 nm. The LED device structure 1030 can be used to form a single complete device, or can be used to form multiple devices as part of a large-scale, high-throughput production process. The LED device structure 1030 has a substrate 1034 on which a crystalline polar multi-region stack 1031 having at least five regions is epitaxially deposited. The multi-region stack 1031 includes regions (i.e., layers) 1038, 1042, 1046, 1050, and 1054.

[0132] In one embodiment, substrate 1034 is formed of sapphire, calcium chloride, or magnesium oxide, through which light (e.g., light 1058) is substantially transparent. In this example, the thickness of substrate 1034 may be from about 500 μm to about 1,000 μm. The diameter of substrate 1034 may be from about 4 inches to about 12 inches. In another example, substrate 1034 is formed of silicon carbide, silicon, or gallium nitride (GaN), which absorbs light and therefore light 1058 is not transparent.

[0133] The first region 1038 of the multi-region stack 1031 is a buffer layer formed on the surface of the substrate 1034. The first region 1038 is used to improve the atomic surface quality of the substrate 1034 by minimizing threading dislocations, thereby reducing the defect density in the film formed above the first region 1038. The second region 1042 on the buffer layer 1038 serves as a crystal structure improvement layer. The second region 1042 further minimizes threading dislocations and thus reduces the defect density in the film formed above the second region 1042.

[0134] The third region 1046 on the second region 1042 has a first conductivity type, such as n-type or p-type conductivity. The fifth region 1054 has a second conductivity type, and the fourth region 1050 is an intrinsic conductivity type (NID) layer between the third region 1046 and the fifth region 1054. The second conductivity type is opposite to the first conductivity type. For example, if the third region 1046 is n-type, then the fifth region 1054 is p-type. Conversely, if the third region 1046 is p-type, then the fifth region 1054 is n-type.

[0135] The multi-region stack 1031 includes: at least one region (ie, layer), the at least one region is a Mg (x) Zn (1-x) O; and at least one region being a superlattice, wherein the superlattice comprises a material selected from the group consisting of ZnO, MgO and Mg (x) Zn (1-x) O. In one embodiment, the buffer layer (first region 1038) may be made of MgZnO, and its thickness may be, for example, about 200 nm to about 1 μm. In one embodiment, the second region 1042 is a superlattice layer formed of a plurality of alternating MgO sublayers 1043a and MgZnO sublayers 1043b, wherein two sublayers 1043a and 1043b are shown for clarity, but more sublayers may be included.

[0136] In some embodiments, at least one of the third region 1046 or the fifth region 1054 (n-type or p-type conductive layer) is formed by introducing at least one of silicon, germanium, nitrogen, aluminum, gallium, nickel, or phosphorus into the oxygen polarity or metal polarity crystal structure of the multi-region stack 1031. In some embodiments, Mg is used. (x) Zn(1-x) O-type bulk or bulk composition composition is graded to form at least one of the third region 1046 or the fifth region 1054. X is a spatially dependent value that varies along the growth direction. That is, the third region 1046 or the fifth region 1054 may include a plurality of regions along the oxygen polarity or metal polarity ( Fig. 10B The spatial correlation composition Mg of the growth direction 1032 is vertical (in the middle) (x) Zn (1-x) O. Examples of compositional classification are Fig. 10B The gradient shading in the third zone 1046 is represented.

[0137] In some embodiments, at least one of the third region 1046 or the fifth region 1054 (n-type or p-type conductivity layer) is formed using compositional grading of an effective alloy composition of a superlattice. (x) Zn (1-x) O and Mg (y) Zn (1-y) O layers form multiple bilayer pairs, where x≠y. The effective alloy composition of the superlattice varies spatially along the growth direction. That is, the spatially dependent effective alloy of the superlattice determined by x and y varies along the oxygen pole or metal pole growth direction 1032. An example of compositional grading of a superlattice is given by Fig. 10B The fifth region 1054 in FIG. 1 shows that the sublayers 1055a1 and 1055a2 may be Mg (x) Zn (1-x) O, and sublayers 1055b1 and 1055b2 may be Mg (y) Zn (1-y) O. Alternating Mg (x) Zn (1-x) O and Mg (y) Zn (1-y) The O sublayers form a bilayer. For sublayers 1055a1 and 1055a2, x varies along the growth direction 1032. Similarly, for sublayers 1055b1 and 1055b2, y varies along the growth direction 1032.

[0138] In other embodiments, Fig. 10BIt can also represent optoelectronic devices having a nonpolar crystal material structure, such as LEDs. In such embodiments, the multi-zone stack 1031 includes a nonpolar crystal material structure along the growth direction 1032. Similar to the polar crystal structures described above, the multi-zone stack 1031 for the nonpolar crystal structure includes zones (i.e., layers) 1038, 1042, 1046, 1050, and 1054. The first zone 1038 of the multi-zone stack 1031 is a buffer layer formed on the surface of the substrate 1034. The second zone 1042 on the buffer layer 1038 serves as a crystal structure improvement layer. The third zone 1046 on the second zone 1042 has a first conductivity type, such as n-type or p-type conductivity. The fourth zone 1050 is an intrinsic conductivity type (NID) layer. The fifth zone 1054 has a second conductivity type opposite to the first conductivity type. At least one zone of the multi-zone stack 1031 is a bulk or massive semiconductor material containing Mg (x) Zn (1-x) O. At least one zone of the multi-zone stack 1031 is a superlattice, where the superlattice contains at least two compositions selected from ZnO, MgO, and Mg (x) Zn (1-x) O.

[0139] In Fig. 10B some embodiments of the nonpolar crystal structure, at least one of the third zone 1046 or the fifth zone 1054 is formed by introducing at least one of silicon, germanium, nitrogen, aluminum, gallium, nickel, or phosphorus into the nonpolar crystal material structure. In some embodiments, compositional grading of a selective alloy composition of the superlattice is used to form at least one of the third zone 1046 or the fifth zone 1054 (n-type or p-type conductivity zone), where the superlattice has a plurality of bilayer pairs formed of Mg (x) M (1-x) O / Mg (y) M (1-y) O, where x≠y, and M is selected from Zn, Al, Ga, Ni, N, and P. The effective alloy composition of the superlattice varies along the growth direction (i.e., x and y are spatially correlated in the growth direction). For example, for the fifth zone 1054, the sublayers 1055a1 and 1055a2 can be Mg (x) M (1-x) O, while the sublayers 1055b1 and 1055b2 can be Mg (y) M (1-y) O. In some embodiments, the multi-zone stack 1031 consists of (i.e., all the components of the multi-zone stack 1031 are selected from) Mg (x) M (1-x) O compositions, where 0.55 <x≤1.0, and M is selected from Zn, Al, Ga, Ni, N, and P.

[0140] Fig.11 is used, for example Fig. 9 Flow chart of an example of a method 1100 for forming a high quality, oxide-based LED device structure using a plasma processing system 900. The method 1100 includes the following steps: Fig. 10A The following steps are described with reference to the device structure 1000, but the steps can also be applied to Fig. 10B device structures and other oxide devices.

[0141] Step 1110 includes rotating the substrate about the central axis of the substrate deposition plane of the substrate and heating the substrate. The substrate is loaded into the reaction chamber in preparation for producing high-quality oxide-based LEDs. The substrate is formed of, for example, calcium fluoride, MgO (111) and (001) surface orientations, Ga2O3 (-201) and (010) surface orientations, Al2O3 (c-plane and r-plane), Si (111), Si (001), a rare earth oxide buffer layer, or a MgZnO superlattice buffer layer. Using a vacuum pump, the vacuum pressure inside the reaction chamber is evacuated to about 10 –5 Torr or lower to evacuate the reaction chamber so that the substrate is contained in a vacuum environment. In addition, the heater is activated to provide a desired growth temperature T at the film formation surface of the substrate. g .

[0142] Step 1115 includes providing at least one material source that supplies material to the substrate. The material sources are contained within a vacuum environment of a reaction chamber. Each material source has: i) an outlet hole having an outlet hole plane; and ii) a predetermined material ejection spatial distribution starting from the outlet hole plane. The predetermined material ejection spatial distribution has a symmetry axis that intersects the substrate at a point offset from the central axis. The outlet holes are positioned at an orthogonal distance, a lateral distance, and an inclined angle relative to the central axis of the substrate. All material sources in the plasma reaction chamber are activated while the shutter remains closed. The material sources may include, for example, one or more of a nitrogen plasma source, a Mg source, a P source, an Al source, a Zn source, a nitrogen oxide (N2O) source, an ammonia (NH3) source, and an oxygen plasma source, the sources being activated while their associated shutters remain closed so that no material impinges on the film forming surface of the substrate.

[0143] Step 1120 includes emitting material from a material source to form a semiconductor layer, such as an oxide-based layer and a p-type doped layer, on a substrate. Step 1120 may include steps 1122, 1125, 1130, 1135, 1140, and 1145 for forming various layers of a semiconductor device. During the emitting step 1120, an exit aperture of at least one material source is positioned such that i) for a set tilt angle, an orthogonal distance and a lateral distance are minimized to achieve a desired layer deposition uniformity for a desired layer growth rate of the semiconductor layer on the substrate, or ii) for a set orthogonal distance and a set lateral distance, a tilt angle is determined to achieve a desired layer deposition uniformity for a desired layer growth rate of the semiconductor layer on the substrate.

[0144] Now we will use Fig. 10A The layers of the device structure 1000 are described Fig.11 ; however, other layers may be formed using the methods and systems disclosed herein. In step 1122, a MgZnO buffer layer (e.g., layer 1008) is formed to a desired thickness. That is, baffles associated with the oxygen plasma source, the Mg species (e.g., baffle 960), and the Zn species (e.g., baffle 964) are opened so that the oxygen species impinges on the film-forming surface of the substrate. In one example, the thickness of the formed MgZnO buffer layer is about 200 nm. During film growth, the vacuum pressure in the reaction chamber is maintained at about 10 –5 Torr or less to ensure ballistic transport of Mg species, Zn species, and oxygen species to the film-forming surface of the substrate.

[0145] At step 1125, the MgO-MgZnO multilayer (e.g., layer 1012) is formed to a desired thickness. That is, the shutters associated with the oxygen plasma source, the Mg species, and the Zn species are opened, whereby the oxygen species impinges upon the film-forming surface of the substrate to form the MgZnO component (sublayer) of the MgO-MgZnO multilayer. The shutter for the Zn species (e.g., shutter 964) is then closed to form the MgO component (sublayer) of the MgO-MgZnO multilayer. During the formation of a plurality of respective sublayers of the superlattice MgO-MgZnO multilayer, the Zn shutter is alternately opened and closed until the desired layer thickness is reached.

[0146] At step 1130, an n-type MgZnO layer (e.g., layer 1016) is formed to a desired thickness. That is, shutters associated with the oxygen plasma source, the Mg species, and the Zn species are opened, whereby the oxygen species impinges on the film-forming surface of the substrate to form the MgZnO component of the n-type MgZnO layer. At the same time, a shutter controlling the Al source is opened, and the Al species impinges on the film-forming surface of the substrate to serve as an n-type dopant in the n-type MgZnO layer.

[0147] At step 1135, the NID layer (e.g., layer 1020) is formed to a desired thickness. In an example where the NID layer contains one or more quantum well structures formed of narrow bandgap zinc oxide (ZnO) quantum well sublayers, the MgO barrier material is formed by opening a Mg shutter (e.g., shutter 260) and a shutter associated with an oxygen plasma source to allow Mg species and oxygen species to impinge on the film-forming surface of the substrate. The ZnO quantum well sublayer is formed by simultaneously closing the Mg shutter and opening a Zn shutter (e.g., shutter 264) to allow Zn species to impinge on the film-forming surface of the substrate. During the formation of the plurality of corresponding sublayers of the NID layer, the Mg and Zn shutters are alternately opened and closed until the desired layer thickness is reached. In one example, the thickness of the NID layer is about 25 nm.

[0148] At step 1140, a p-type MgZnO layer (e.g., layer 1024) is formed to a desired thickness. That is, shutters associated with the oxygen plasma source, the Mg species, and the Zn species are opened, whereby the oxygen species impinges on the film-forming surface of the substrate to form the MgZnO component of the p-type MgZnO layer. At the same time, shutters associated with the nitrogen plasma source are opened, whereby the nitrogen species impinges on the film-forming surface of the substrate. The nitrogen species is, for example, N* or N2* and serves as a p-type dopant in the p-type MgZnO layer. A beam flux monitor, such as a RHEED system, may be used to monitor the flux of the nitrogen species.

[0149] At step 1145, electrical contacts are formed on the LED device structure (e.g., device 1000) using conventional photolithography and metallization processes. The LED device structure is a vertical conductive LED, where charge carriers interact and recombine within the NID layer to produce light emitted from the LED device structure. In another example, method 1100 is used to form a lateral conductive LED, where light emission occurs in a lateral direction.

[0150] In summary, plasma processing systems and methods for forming high-quality oxide-based devices (e.g., DUV LEDs) exhibit advantages over conventional systems and methods for forming III-N films using epitaxial growth. Conventional semiconductor manufacturing equipment and epitaxial processes are unable to maintain the film growth temperature tolerances and precursor gas levels necessary for high-quality film deposition, particularly for substrates greater than 4 inches in diameter. This limitation can result in non-uniform temperature profiles across the film-forming surface, resulting in low-quality or unusable devices. Finally, the device bandgap tuning capabilities of conventional III-N films are limited. This limits the flexibility of semiconductor device design and application, particularly in the manufacture of DUV LEDs. In contrast, the inventive plasma processing systems and methods disclosed herein focus on producing high-quality films on larger substrates, greater device application flexibility, higher production yields, and reduced manufacturing costs.

[0151] The methods and systems of the present invention can generally be used to form structures having one or more MgZnO layers, thereby providing metal-rich and / or oxygen-rich compositions. These compositions are classified as non-stoichiometric materials and exhibit oxygen and / or metal vacancies that can be engineered to exhibit excess electrons or holes, depending on the crystallographic defects introduced into the crystal. In some embodiments, the structure is Mg y Zn 1-y O / Mg x Zn 1-x O superlattice or MgZn(O,N) oxynitride composition. For example, the semiconductor layer can be a superlattice including sublayers of: a) MgO and ZnO, b) MgZnO and ZnO, or c) MgZnO and MgO.

[0152] An example of a MgZnO structure grown according to an embodiment of the present invention comprises MgO as a layer and substrate; Mg x Zn 1-x O layer, x> 0.5 (rock salt); and MgO / Mg x Zn 1-x O, x> 0.55 (non-polar rock salt). In some embodiments, a wurtzite Mg x Zn 1-x Polar structures of O, x < 0.45, such as Mg x Zn 1-x O superlattice, where 0≤x <0.45; [Mg x Zn 1-x O, 0 ≤ x < 0.45] / [Mg y Zn 1-y O, 0 ≤ y < 0.45] superlattice, where x≠y; and bulk Mg x Zn 1-x O graded composition, 0≤ x <0.45. Bulk Mg x Zn 1-x The graded composition of O may include induced p-type or n-type doping. For example, some methods may induce p-type by grading from WBG to NBG for an O pole that is substantially oriented in the C plane or by grading from NBG to WBG for a metal pole that is substantially oriented in the C plane. In other examples, methods may induce n-type by grading from WBG to NBG for a metal pole that is substantially oriented in the C plane or by grading from NBG to WBG for an O pole that is substantially oriented in the C plane. In some embodiments, the method may induce n-type by using a grading method for bulk Mg x Zn 1-x The bulk standard described in O grades the superlattice unit cells to produce graded effective alloy compositions.

[0153] In addition to the polarization type doping described in the previous paragraph, impurity type doping may also be used. In some embodiments, both impurity type and polarization type doping may be used.

[0154] Other embodiments include forming devices using polar doping of MgZnO for compositions x < 0.45. Other embodiments include forming hybrid superlattices comprising MgO / ZnO or comprising [Mg x Zn 1-x O, 0 ≤ x≤ 1 ] / [Mg y Zn 1-y O, 0 ≤ y ≤ 1] superlattice, where x≠y. Other embodiments include forming a non-polar Mg x Zn 1-x O structure, where x > 0.55.

[0155] The structure can be grown on various substrates such as: MgO (111) and (001) surface orientations, Ga2O3 (-201) and (010) surface orientations, Al2O3 (c-plane and r-plane), Si (111) with wurtzite MgZnO x <0.45, Si (001) with MgZnO x> 0.55, rare earth oxide buffer layers and MgZnO superlattice buffer layers.

[0156] MgZnO superlattices and multiple quantum wells (MQWs) enable thicker layers with a quantized effect and are easier to grow than AlGaN or AlN / GaN superlattices.

[0157] Detailed reference has been made to the embodiments of the disclosed invention, one or more examples of which have been shown in the accompanying drawings. Each example has been provided by way of illustration of the present technology, rather than by way of limitation. In fact, although this specification has been described in detail with respect to specific embodiments of the present invention, it should be understood that those skilled in the art, after understanding the foregoing, can easily conceive of substitutions, modifications and equivalents to these embodiments. For example, a feature shown or described as part of one embodiment can be used together with another embodiment to produce yet another embodiment. Therefore, it is intended that this subject matter covers all such modifications and variations within the scope of the attached claims and their equivalents. Without departing from the scope of the present invention as more specifically set forth in the attached claims, those of ordinary skill in the art may practice these and other modifications and variations of the present invention. In addition, those of ordinary skill in the art will appreciate that the foregoing description is merely an example and is not intended to limit the present invention.

Claims

1. A method for forming a semiconductor layer, the method comprising: rotating a substrate about a central axis of a substrate deposition plane of the substrate; heating the substrate; providing a material source for supplying material to the substrate, wherein the material source has i) an outlet orifice having an outlet orifice plane and ii) a predetermined material ejection spatial distribution starting from the outlet orifice plane, the predetermined material ejection spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis, wherein the outlet orifice is positioned at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate; containing the substrate and the material source in a vacuum environment; as well as emitting the material from the material source to form a semiconductor layer on the substrate; wherein the exit hole is positioned such that i) for a set tilt angle, the orthogonal distance and the lateral distance are minimized to achieve a desired layer deposition uniformity for a desired layer growth rate of the semiconductor layer on the substrate, or ii) the tilt angle is determined for a set orthogonal distance and a set lateral distance to achieve the desired layer deposition uniformity for the desired layer growth rate of the semiconductor layer on the substrate.

2. The method of claim 1, wherein the material source is a cosine-N source and N ≥ 2.

3. The method of claim 1, wherein the substrate has a diameter equal to or greater than 6 inches (150 mm).

4. The method of claim 1, wherein: The material source is a nitrogen plasma source that emits active nitrogen; and The method also includes providing an oxygen plasma source.

5. The method of claim 4, wherein: The method further comprises providing a source of magnesium (Mg) and a source of zinc (Zn); and The semiconductor layer is Mg X Zn 1-X O layer, where x > 0.

6. The method of claim 5, wherein the semiconductor layer is a superlattice comprising sublayers of: a) MgO and ZnO, b) MgZnO and ZnO, or c) MgZnO and MgO.

7. The method of claim 1, wherein: The material source is a magnesium (Mg) source; The method further comprises providing a source of zinc (Zn); and The semiconductor layer is a MgZnON layer. The method of claim 1 , wherein the semiconductor layer is a p-type doped Mg-based layer.

9. A method for forming an oxide-based semiconductor layer, the method comprising: rotating a substrate about a central axis of a substrate deposition plane of the substrate; heating the substrate; placing a plurality of material sources facing the substrate, the plurality of material sources comprising a magnesium (Mg) source and a plasma source of nitrogen or oxygen, wherein each of the plurality of material sources has i) an exit hole having an exit hole plane and ii) a predetermined material ejection spatial distribution starting from the exit hole plane, the material ejection spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis, wherein the exit holes are positioned at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate; as well as emitting material from the plurality of material sources onto the substrate to form an oxide-based layer on the substrate; wherein the exit aperture is positioned such that i) for a set tilt angle, the orthogonal distance and the lateral distance are minimized to achieve a desired layer deposition uniformity for a desired layer growth rate of the oxide-based layer on the substrate, or ii) the tilt angle is determined for a set orthogonal distance and a set lateral distance to achieve the desired layer deposition uniformity for the desired layer growth rate of the oxide-based layer on the substrate.

10. The method of claim 9, wherein: The plurality of material sources also includes a zinc (Zn) source; and The oxide-based layer is Mg X Zn 1-X O, where x > 0.

11. The method of claim 9, wherein the oxide-based layer is a p-type doped Mg-based layer.

12. The method of claim 9, wherein: The oxide-based layer is a p-type doped layer; and The emission includes using one of: active nitrogen plasma, nitrogen oxide (N2O), ammonia (NH3), phosphorus, oxygen plasma, or defective Mg or Zn.

13. The method of claim 9, wherein the oxide-based layer is a layer comprising wurtzite Mg X Zn 1-X Polar structure of O, where 0 ≤ x < 0.

45.

14. The method of claim 13, wherein the polar structure is formed by the Mg X Zn 1-X O is either p-type or n-type induced by graded composition, where 0 ≤ x < 0.

45.

15. The method of claim 9, wherein the oxide-based layer is a superlattice of: a) Mg X Zn 1-X O, 0 ≤ x ≤ 1, and b) Mg Y Zn 1-Y O, 0 ≤ y ≤ 1, where x≠y.

16. The method of claim 9, wherein the oxide-based layer is a superlattice comprising sublayers of: a) MgO and ZnO, b) MgZnO and ZnO, or c) MgZnO and MgO.

17. The method of claim 9, wherein the oxide-based layer is MgZnON.

18. The method of claim 9, wherein the oxide-based layer is a non-polar Mg X Zn 1-X O structure, where x > 0.

55.

19. The method of claim 9, wherein the substrate has a diameter equal to or greater than 6 inches (150 mm).

20. A method for forming a p-type doped semiconductor layer, the method comprising: rotating a substrate deposition plane of a substrate about a central axis of the substrate deposition plane; heating the substrate; placing a plurality of material sources facing the substrate, the plurality of material sources comprising a magnesium (Mg) source, a zinc (Zn) source, and a plasma source of nitrogen or oxygen, wherein each of the plurality of material sources has i) an exit hole having an exit hole plane and ii) a predetermined material ejection spatial distribution starting from the exit hole plane, the material ejection spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis, wherein the exit holes are positioned at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate; as well as emitting materials from the plurality of material sources onto the substrate to form a p-type doped layer on the substrate; wherein the exit aperture is positioned such that i) for a set tilt angle, the orthogonal distance and the lateral distance are minimized to achieve a desired layer deposition uniformity for a desired layer growth rate of the p-type doped layer on the substrate, or ii) the tilt angle is determined for a set orthogonal distance and a set lateral distance to achieve the desired layer deposition uniformity for the desired layer growth rate of the p-type doped layer on the substrate.

21. The method of claim 20, wherein the plurality of material sources further comprises a phosphorus source to provide phosphorus as a p-type dopant.

22. The method of claim 20, wherein the p-type doped layer is an oxide layer, and the emitting material to form the p-type doped layer comprises i) replacing oxygen atoms with nitrogen or ii) replacing Mg or Zn atoms with Al or Ga.

23. The method of claim 20, wherein the p-type doped layer comprises MgZnO.

24. The method of claim 20, wherein the plurality of material sources further comprises nitrogen oxide (N2O) or ammonia (NH3) to achieve p-type doping of the p-type doping layer.

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