Methods and material deposition systems for forming semiconductor layers

Abstract

To provide methods, material deposition systems, and devices for forming semiconductor layers.SOLUTION: A material deposition system 50 has: a rotation mechanism that rotates a substrate 122 around a center axis AX of a substrate deposition plane 126 of the substrate in a vacuum chamber 100; and a material source 118 that supplies a material to the substrate. The material source has: an exit aperture 130 with an exit aperture plane; and a predetermined material ejection spatial distribution from the exit aperture plane. The exit aperture is positioned at an orthogonal distance Z, a lateral distance X, and a tilt angle α relative to the center axis of the substrate so as to achieve a desired layer deposition uniformity at a desired layer growth rate of the semiconductor layer on the substrate either: by means that an orthogonal distance and a lateral distance are minimized for a set tilt angle; or by means that the tilt angle is determined for a set orthogonal distance and a set lateral distance.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 62 / 682,005, entitled "Material Deposition System and Method," filed June 7, 2018, which is incorporated herein by reference for all purposes. [Background technology]

[0002] In semiconductor manufacturing processes, thin film materials are deposited onto planar deposition surfaces, for example, using 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. Molecular beam epitaxy is performed in high vacuum (HV) or ultra-high vacuum (UHV) (e.g., 10 -6 ~10 -9 MBE is performed at a pressure of 1000 Pa (1000 Pa). The most important features of MBE are (1) flexibility in the selection of source material species, (2) abrupt interfaces between deposited dissimilar films, (3) low impurity levels in the deposited films, and (4) precise and uniform thickness of the deposited films. The last feature is achieved by using deposition rates that are relatively slow (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. MBE's slow deposition (or growth) rates are advantageously used to epitaxially grow thin films. However, MBE requires a proportionally higher reactor vacuum to match the low impurity levels achieved by other deposition techniques (e.g., CVD).

[0003] In deposition processes such as MBE, high-quality films can have thickness uniformity of approximately 99% or greater across the deposition surface. Stated differently, high-quality films can have thickness non-uniformity of approximately 1% or less across the deposition surface. Because a direct correlation exists between growth rate and the quality of epitaxially grown films, uniformity across the deposition surface is important in current MBE processes. That is, slow deposition rates enable the control of uniform atomic monolayer-scale coverage across the deposition surface, enabling the two-dimensional (2D) "layer-by-layer" (LbL) growth mode. Thin film deposition using the LbL growth mode allows the formation of a complete 2D layer prior to the growth of subsequent layers, which is the most desirable method for the epitaxial growth of single-crystalline thin films and multilayer heterogeneous films. Typically, the LbL growth mode is realized for technologically relevant semiconductors (e.g., AlGaAs, AlGaN, SiGe, etc.) under at least the following criteria: (i) highly non-equilibrium temperature-pressure conditions, (ii) uniform arrival of species across the deposition surface, and (iii) highly uniform spatial temperature that can be imparted to the growth surface. Summary of the Invention

[0004] 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 improving 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 includes Mg (x) Zn (1-x) At least one region of the multi-region stack is a bulk semiconductor material containing ZnO, MgO, and Mg (x) Zn (1-x) O.

[0005] In some embodiments, an optoelectronic device includes a substrate and a multi-region stack epitaxially deposited on the substrate, the multi-region stack including a non-polar crystalline material structure along a growth direction, the multi-region stack including a first region including a buffer layer, a second region including a crystalline structure improving layer, and a second region including a crystalline structure improving layer. The multi-region stack includes 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 includes Mg (x) Zn (1-x) At least one region of the multi-region stack is a bulk semiconductor material containing ZnO, MgO, and Mg (x) Zn (1-x) O.

[0006] In some embodiments, a method for configuring a material deposition system includes providing a rotation mechanism for rotating a substrate about a central axis of a substrate deposition surface of the substrate. A material source for supplying material to the substrate is selected, the material source having i) an outlet opening having an outlet opening face, and ii) a predetermined spatial distribution of material emission from the outlet opening face. The predetermined spatial distribution of material emission has an axis of symmetry that intersects the substrate at a point offset from the central axis. The outlet opening 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 either i) the inclination angle or ii) the orthogonal and lateral distances of the outlet opening of the material source. A desired deposition of material on the substrate is selected to achieve a desired layer deposition uniformity at a desired growth rate. The method determines either i) minimum values ​​of the orthogonal and lateral distances to achieve the desired layer deposition uniformity using the set inclination angle, or ii) the inclination angle to achieve the desired layer deposition uniformity using the set orthogonal and lateral distances. The substrate and material source are contained within a vacuum environment.

[0007] In some embodiments, a method for forming a semiconductor layer includes rotating a substrate about a central axis of a substrate deposition surface of the substrate, heating the substrate, and providing a material source for supplying material to the substrate. The material source has i) an outlet opening having an outlet opening surface, and ii) a predetermined spatial distribution of material emission from the outlet opening surface, the predetermined spatial distribution of material emission having an axis of symmetry that intersects the substrate at a point offset from the central axis. The outlet opening is disposed at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. The method includes housing the substrate and the material source in a vacuum environment and discharging material from the material source to form a semiconductor layer on the substrate. The outlet opening is disposed to: i) minimize the orthogonal and lateral distances relative to the inclination angle to achieve a desired layer deposition uniformity at a desired layer growth rate of the semiconductor layer on the substrate; or ii) determine an inclination angle relative to the orthogonal and lateral distances to achieve a desired layer deposition uniformity at a desired layer growth rate of the semiconductor layer on the substrate.

[0008] In some embodiments, a material deposition system includes a rotation mechanism for rotating a substrate deposition surface of a substrate about a central axis of the substrate deposition surface, a heater configured to heat the substrate, a material supply source for supplying material to the substrate, and a position adjustment mechanism. The material supply source has i) an outlet opening having an outlet opening surface, and ii) a predetermined material emission spatial distribution from the outlet opening surface. The predetermined material emission spatial distribution has an axis of symmetry that intersects the substrate at a point offset from the central axis, and the outlet opening is disposed at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. The position adjustment mechanism can dynamically adjust the orthogonal distance, the lateral distance, or the inclination angle.

[0009] In some embodiments, a method for forming an oxide-based semiconductor layer includes rotating a substrate about a central axis of a substrate deposition surface of the substrate, heating the substrate, and disposing a plurality of material sources facing the substrate. The plurality of material sources includes a magnesium (Mg) source and a nitrogen or oxygen plasma source. Each of the plurality of material sources has i) an exit opening having an exit opening face, and ii) a predetermined material emission spatial distribution from the exit opening face, the material emission spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis. The exit openings are disposed at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate. The method includes discharging materials from the plurality of material sources onto the substrate to form an oxide-based layer on the substrate. The exit opening is positioned to: i) minimize the orthogonal and lateral distances relative to the set tilt angle to achieve a desired layer deposition uniformity at a desired layer growth rate of the oxide-based layer on the substrate; or ii) determine the tilt angle relative to the set orthogonal and lateral distances to achieve a desired layer deposition uniformity at a desired layer growth rate of the oxide-based layer on the substrate.

[0010] In some embodiments, a method for forming a semiconductor layer includes rotating a substrate deposition surface of a substrate around a central axis of the substrate deposition surface, heating the substrate, and disposing a plurality of material sources facing the substrate. The plurality of material sources includes a magnesium (Mg) source, a zinc (Zn) source, and a nitrogen or oxygen plasma source, each of the plurality of material sources having i) an exit opening having an exit opening surface, and ii) a predetermined material emission spatial distribution from the exit opening surface. The material emission spatial distribution has an axis of symmetry that intersects the substrate at a point offset from the central axis. The exit opening is disposed at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate. Materials from the plurality of material sources are emitted onto the substrate to form a p-type doped layer on the substrate. The exit opening is positioned to: i) minimize the perpendicular and lateral distances relative to the set tilt angle to achieve a desired layer deposition uniformity at a desired layer growth rate of the p-type doped layer on the substrate; or ii) determine the tilt angle relative to the set perpendicular and lateral distances to achieve a desired layer deposition uniformity at a desired layer growth rate of the p-type doped layer on the substrate. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an isometric view of a conventional high vacuum reaction chamber. [Figure 2] FIG. 1 illustrates an isometric view of a material deposition system, according to some embodiments. [Figure 3] 10 is a plot of an example of a beam flux profile corresponding to a particular cosine N factor of a material source, according to some embodiments. [Figure 4] 1 is an example of a plot of configuration space for a particular location of a material source relative to a build surface, where calculated film non-uniformity is plotted as a function of the X and Z coordinates of the material source, according to some embodiments. [Figure 5] 1 is an example of a plot of configuration space for a particular location of a material source relative to a build surface, where calculated film non-uniformity is plotted as a function of the X and Z coordinates of the material source, according to some embodiments. [Figure 6]1 is an example of a plot of configuration space for a particular location of a material source relative to a build surface, where calculated film non-uniformity is plotted as a function of the X and Z coordinates of the material source, according to some embodiments. [Figure 7] 1 is an example of a plot of configuration space for a particular location of a material source relative to a build surface, where calculated film non-uniformity is plotted as a function of the X and Z coordinates of the material source, according to some embodiments. [Figure 8] 1 is a flow diagram of an example of a method for 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. [Figure 9] 1 is a side view of an example of a plasma processing system used to form semiconductor layers, such as high-quality oxide-based films, according to some embodiments. [Figure 10A] 1 is a cross-sectional view of an oxide-based LED device structure according to some embodiments. [Figure 10B] 1 is a cross-sectional view of an oxide-based LED device structure according to some embodiments. [Figure 11] 10A-10B is a flow diagram of an example method for forming the LED device structure shown in FIGS. 10A-10B, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure relates generally to semiconductor manufacturing processes, and more particularly to the relationship between film quality and film growth rate. The present disclosure relates to a material deposition system having an off-axis material source within a high-vacuum reaction chamber for improved balance. Methods for configuring the material deposition system by determining the location of the material source and scaling the overall reaction chamber size accordingly are also 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.

[0013] The high film quality that can be achieved using UHV deposition techniques has traditionally come at the expense of significantly increased processing times compared to other mature high-pressure CVD semiconductor manufacturing processes. Unfortunately, traditional UHV deposition methods, such as best-case MBE, cannot adequately accommodate the high-throughput processing demands of silicon-based semiconductor manufacturers. In addition, current MBE processes are limited to growing highly uniform films on relatively small deposition surfaces, such as substrates with a diameter of 6 inches or less. In the silicon-based semiconductor industry, deposition costs per unit area ($ / m 2 This highlights the importance of scaling the manufacturing process to larger deposition surfaces, such as 8-inch, 12-inch, and even 18-inch deposition surfaces, to keep the deposition rate (T) sufficiently low. Therefore, new approaches are required to scale MBE processes to larger deposition surfaces and provide high film quality at high deposition rates.

[0014] In semiconductor device fabrication, III-nitride (III-N) semiconductors (e.g., aluminum nitride, gallium nitride, aluminum-gallium nitride, and indium nitride) are widely recognized as one of the most promising semiconductor groups for producing wide-bandgap semiconductors used in the fabrication of deep ultraviolet (DUV) optical devices such as LEDs and laser diodes (LDs). Unfortunately, several challenges inherent in conventional fabrication equipment and methods limit the production of high-quality III-N films.

[0015] For example, controlling the growth temperature and precursor gas levels required for high-quality film deposition is difficult on substrates larger than 4 inches in diameter, as discussed above. Non-uniform temperature profiles across the film formation surface can result in poor-quality or unusable devices. Furthermore, conventional III-N film formation is a relatively inefficient, low-throughput, and expensive process that inefficiently utilizes high-cost source materials. Finally, conventional III-N films have limited device bandgap tuning capabilities, which reduces flexibility in semiconductor device design and utilization, particularly in the manufacture of deep-UV LEDs. As the semiconductor industry places increasing emphasis on producing high-quality films on larger substrates, increasing manufacturing throughput, and reducing manufacturing costs, new approaches to device fabrication are needed.

[0016] The present disclosure provides a method for setting offset material sources within a high-vacuum reaction chamber with respect to improving the balance between film quality and film growth rate. For example, several embodiments are used to determine the position of a material source (e.g., a Knudsen evaporation cell, gas injection source, remote plasma source, ion beam source, sputtering source, charged particle beam, thermal evaporation source, or ablation source) relative to a film formation surface within a high-vacuum reaction chamber, providing an improved balance between film quality and film growth rate compared to conventional techniques. More specifically, the method is used to determine the lateral and orthogonal distances of the material source relative to the formation surface for a given material source having specific properties or characteristics and for a given tilt angle setting of the material source to improve the balance between film quality and film growth rate. In other embodiments, the lateral and orthogonal distances of the material source can be set, and the tilt angle can be determined to achieve a desired film quality and film growth rate.

[0017] Systems and methods for forming high quality oxide-based DUV LEDs are also disclosed.Oxide-based semiconductors are wide bandgap semiconductors that belong to the II-VI semiconductor family. Generally, they exhibit excellent transparency, high electron mobility, wide band gaps, and strong light emission at room temperature. Oxide-based semiconductors are inherently n-type, and p-type doping of oxides is difficult to achieve using conventional methods. In this embodiment, p-type doping of these semiconductors is achieved using a plasma of activated atomic nitrogen (N*) or molecular nitrogen (N2*). The methods disclosed herein utilize a plasma reaction chamber to form films on substrates made of materials such as calcium fluoride. In some embodiments, a magnesium zinc oxide (MgZnO) buffer layer is formed on the substrate, and an MgO-MgZnO multilayer is formed on the buffer layer. Then, n-type MgZnO is formed on the MgO-MgZnO multilayer, and an unintentionally doped (NID) layer of MgZnO or MgO is formed on the n-type MgZnO layer. A p-type MgZnO layer is then formed using p-type doping from the N* or N2* plasma. Finally, metal contacts are formed on the device structure using conventional lithography and metallization processes. In one example of operation, the n-type MgZnO layer generates electrons that migrate to the NID layer, where the charge carriers interact and recombine to emit light from the LED device structure in the UV wavelength range of about 100 nm to about 280 nm.

[0018] The methods and materials used to form high-quality oxide-based DUV LEDs offer advantages over conventional methods and materials. For example, controlling the growth temperature and precursor gas levels required for high-quality film deposition of III-N films using conventional methods is difficult, especially on substrates larger than 4 inches in diameter. Furthermore, conventional III-N film formation is a relatively inefficient, low-throughput, and expensive process that utilizes high-cost source materials inefficiently. Finally, conventional III-N films have limited bandgap tuning capabilities, which limits the flexibility of semiconductor device design and utilization, especially in the fabrication of DUV LEDs. In contrast, the methods disclosed herein emphasize the fabrication of high-quality films on larger substrates, greater flexibility in device utilization, increased manufacturing throughput, and reduced manufacturing costs.

[0019] MBE is just one example of a process in which thin crystalline films are epitaxially grown in a high vacuum environment. Such films may be composed of compound semiconductors selected from the periodic table of elements. For example, IIIA-VA semiconductors may contain a group IIIA metal selected from at least one of Al, Ga, and In, and a group VA species selected from As, P, and N, resulting in a stoichiometric Al x Ga 1-x As y P 1-y and Al x Ga 1-x In another example, the II-VI semiconductor can include a group II metal selected from Cd and Zn and a group VI species selected from Te, S, and Se to form the compound Zn x CD 1-x Te can be formed. Further examples include IV-IV (e.g., Si x Ge y C z ) and metal oxide MO x Other examples of metal oxides include RE-oxides and RE-oxynitrides (RE is at least one species from the group of rare earth elements, i.e., selected from the lanthanide series or alkaline earth metal species) or IIA-IB-VIA (e.g., Mg x Zn 1-x O), which are also exemplary materials produced using the MBE methods disclosed herein. The methods of the present invention can also utilize other materials, such as amorphous oxynitrides and metal alloys, to form highly uniform films at improved growth rates. That is, the physical principles disclosed herein are independent of the inherent surface chemistry of the adatom and the substrate.

[0020] Furthermore, the use of compound semiconductor materials in the deposition process offers the ability to fabricate multiple different epilayers deposited sequentially on the deposition surface, allowing quantum engineered structures to be tailored and optimized for specific electro-optical and electronic applications (e.g., LEDs, lasers, power transistors, and radio frequency devices).

[0021] Therefore, in the method and system of the present invention, a balance between film quality and film growth rate is achieved. Material sources positioned relative to the formation surface to improve performance are suitable for supporting continuous, high-throughput film formation processes using MBE systems. The present disclosure provides improvements over existing systems and methods that have traditionally been characterized by slow growth rates and / or poor deposition uniformity due to the physical placement of material sources fixed by the MBE system manufacturer. Traditional Material Deposition Systems 1 is an isometric view of a portion of a high-vacuum reaction chamber 10 known in the art, which includes a material source 18 positioned off-axis and at an angle relative to a film formation 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 a pressure of about 10 -12 torr ~ approx. 10 -7 torr, about 10 -11 torr ~ approx. 10 -9 torr, or about 10 -11 torr~10 -5 A well-prepared, substantially leak-free reactor has a base pressure and growth pressure (i.e., during deposition) that is directly related to the pumping rate of the reactor and the incident beam pressure produced by the source.

[0022] The material source 18 is positioned relative to a substrate 22 inside the high-vacuum reaction chamber 10. The substrate 22 may be any base material upon which a film or layer of material may be formed. The substrate 22 is rotatable about a central axis of rotation AX. The side of the substrate 22 facing the material source 18 provides a film formation surface 26. The substrate 22 has a radius R SUB It has.

[0023] The formation surface 26 is the target for material delivered from the material source 18. That is, the formation surface 26 is the side of the substrate 22 on which a film may be formed, such as by epitaxy. Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate, where the overlayer is inscribed on the substrate. In other words, to be called epitaxial growth, there must be one or more preferred crystalline orientations of the overlayer with respect to the substrate. The overlayer is sometimes called an epitaxial film or epilayer, or sometimes called an epilayer.

[0024] The material source 18 may be any elemental source or pure species capable of forming a film on the forming surface 26. For example, the material source 18 shown in FIG. 1 may be a Knudsen evaporation cell. A typical Knudsen evaporation cell includes a shaped crucible (made of high-purity pyrolytic boron nitride, fused quartz, tungsten, or graphite), multiple resistive heating filaments, a water cooling system, a heat shield to contain heat within the crucible body, a crucible orifice, and an orifice shutter. None of these are shown, but are well known to those skilled in the art. The material source 18 includes an exit opening 30. In a Knudsen evaporation cell, the exit opening 30 is an opening at the end of the crucible facing the forming surface 26. As a result of heating the crucible, the material (e.g., liquid) within the crucible also heats, causing material atoms to evaporate (e.g., from the liquid surface). The number of atoms evaporated per unit area per unit time can be well controlled by controlling the temperature of the crucible. The evaporated atoms or species are conveyed under pressure from exit orifice 30, traveling with a well-defined exit velocity and mean free path over the distance from the source to the substrate (maintained by the high vacuum level within the reactor), and directed toward forming surface 26 where they collide and / or interact with material at forming surface 26. That is, a plume 34 of material (or species) exits exit orifice 30 of material source 18 and is directed toward forming surface 26. Plume 34 has an axis of symmetry SA.

[0025] Conventional commercial MBE deposition systems utilize spatially configured material sources for adequate material flux uniformity over a relatively small deposition surface area without first considering simultaneous optimization of both flux uniformity and growth rate. Figure 1 shows a schematic representation of a substrate's central axis of rotation AX. Material source 18 is positioned at a specific lateral distance X from the central axis of rotation AX of substrate 22, a specific orthogonal (perpendicular) distance Z from the plane of formation surface 26, and a specific vertical distance Z relative to the plane of formation surface 26. The material source 18 is positioned at a virtual flux plane (VFP) tilt angle α. Therefore, the material source 18 is an "off-axis" material source. The lateral distance X and orthogonal distance Z are coordinates of the material source 18 relative to the center of the substrate deposition surface 26.

[0026] In practice, the non-optimal spatial arrangement of the material source in conventional MBE systems is due to the substrate-to-source distance R Src-Sub (i.e., by placing the source significantly farther than required for optimal placement). This increased substrate-to-source distance directly results in a decrease in growth rate that is inversely proportional to the square of the substrate-to-source distance, and a decrease in utilization of the emitted source material. Additionally, in conventional MBE systems, the plume of species from the material source is typically directed toward the center of the formation surface 26.

[0027] A conventional MBE system can be generalized and summarized as a reactor system with a configuration space defined by: (i) the axis of symmetry SA of the material source plume, positioned to target the absolute center of rotation of the deposition surface; (ii) R from the source to the substrate src-sub , and the lateral distance X of the source VFP center of gravity relative to the substrate rotation axis AX, which is configured with cylindrical or spherical symmetry about the center of the deposition surface. (iii) X≦R src-sub and β = tan -1 (X / R src-sub )≦45° (β is the angle between the vertical axis Z and the axis of symmetry SA), and (iv) The virtual flux plane inclination angle is limited to the range 0≦α≦45°. Material deposition system with optimized source placement 2 is an isometric view of a portion of a material deposition system 50, according to some embodiments. The material deposition system 50, which is a molecular beam epitaxy system, includes a high-vacuum reaction chamber 100. The material deposition system 50 is configured to deposit a material 122 off-axis, at an angle relative to the substrate deposition surface 126 of the substrate 122, and at an amount R offset That is, the material supply 118 is not at an absolute center, but is offset by an amount R offset The substrate 122 has an axis of symmetry SA directed toward a point offset from the absolute center of the substrate 122 by a distance of 1000 . The material source 118 deposits material onto the substrate deposition surface 126 at an area 122P. A vacuum environment 114 is maintained within the high vacuum reaction chamber 110 by a vacuum pump 116. For example, the vacuum environment 114 may be maintained at a pressure of approximately 100 . -12 torr ~ approx. 10 -7 torr, in another example, about 10 -11 torr ~ approx. 10 -9 torr, or in yet another example, about 10 -11 torr~10 -5 torr range.

[0028] The material source 118 is positioned relative to the substrate 122 within the high-vacuum reaction chamber 100 to produce a deposition layer with high uniformity while maintaining high throughput. The substrate 122 may be any base material upon which a film or layer of material can be formed. For example, the substrate 122 may be a silicon (e.g., single crystal), sapphire, MgO, or Ga2O3 wafer with a clean atomic surface. The substrate 122 is rotatable about a central axis of rotation AX. The substrate deposition surface 126 is the surface of the substrate 122, e.g., the front surface, on which a film may be formed, such as by epitaxy. The substrate 122 is rotatable about a particular radius R SUB For example, an 8-inch substrate 122 has a 4-inch R SUB The 12-inch substrate 122 has an R of 6 inches (approximately 150 mm). SUB1 is circular, the systems and methods of the present invention are not limited thereto. For example, the substrate 122 may be square or have other non-circular shapes. In another embodiment, the material source 118 is positioned relative to a platen or the like on which one or more substrates are mounted.

[0029] Those skilled in the art will appreciate that the high vacuum reaction chamber 100 may include other components not shown in FIG. 2 (e.g., substrate heaters, material source openings, sensing devices, additional vacuum pumping system components, etc.). ) may be included.

[0030] The material source 118 may be a source of any element or pure species capable of forming a film on the substrate deposition surface 126. In some embodiments, the material source may be a nitrogen or oxygen plasma source. Examples of material source 118 include gaseous precursor injectors, preheated gas injectors, Knudsen-type thermally driven crucibles for containing sublimated solid material or evaporated liquid material (i.e., Knudsen evaporation cells), electron beam evaporator heating of the source material, and remote plasma activation sources for gaseous precursors (i.e., sources in which the plasma region is contained entirely within the source and does not extend from the source toward the substrate surface). In one example, if aluminum (Al) is the material to be epitaxially grown on the substrate deposition surface 126, the material source 118 may be a Knudsen evaporation cell containing substantially pure aluminum contained in a substantially non-interacting crucible.

[0031] The material source 118 includes an exit opening 130 and a material level 132 of material within the material source 118. In the case of a Knudsen evaporation cell, the exit opening 130 is an opening in the end of the crucible facing the substrate deposition surface 126. A plume 134 of material (or species) exiting the exit opening 130 of the material source 118 is directed toward the substrate deposition surface 126. In another embodiment, the material source 118 includes multiple exits (exit openings 130).

[0032] The position of the material source 118 relative to the substrate 122 can be dynamically adjusted 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 fabrication runs to achieve desired layer deposition uniformity and a desired layer growth rate. The tilt angle, lateral distance, and orthogonal distance settings depend on the spatial distribution of material emission from the material source. Positioning adjustments can also be affected by simultaneously using multiple material sources that emit different materials. In some embodiments, the tilt angle of the material source can be set first, and the minimum orthogonal and lateral distances can be determined using the set tilt angle. In other embodiments, the orthogonal and lateral distances can be set first, and the tilt angle can be determined to achieve desired layer deposition uniformity at a desired growth rate. In some embodiments, the position of the material source 118 can be moved while the substrate 122 is fixed, or the substrate 122 can be moved instead of or in addition to the material source 118. For example, the positioning mechanism may be coupled 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 a slot, an arm or post with an adjustable length, a linear actuator, or a combination thereof.

[0033] The plume 134 of material (or species) is a flux of substantially non-interacting particles that has a spatial beam flux profile (BFP) that can be characterized by the angular distribution of species emitted in a forward direction from the material source 118. The BFP is sometimes referred to as the predetermined material emission spatial distribution of the material source. The beam flux profile is characterized by the relationship of the BFP angle θ to the axis of symmetry SA of the plume 134. Thus, the material source 118 can be approximated by and is characterized by having a particular cosine N factor. The cosine N factor is described in more detail with reference to FIG. 3.

[0034] 3 is a plot 200 of an example beam flux profile corresponding to a particular cosine N factor of a material source. Plot 200 shows the angular beam dispersion of a particular beam flux profile as a function of BFP angle θ. For example, plot 200 shows a BFP 210 that has a cosine N factor of 1, which is considered to be a substantially spherical, isotropic point source. For cos N > 1, N The BFP with (θ) is shown in Figure 3. For example, plot 200 shows BFP 214, which has a cosine N factor of 6 and a beam flux profile that is not spherical but is more elongated and narrower than BFP 210. Plot 200 also shows examples of other BFPs between BFP 210 and BFP 214, each with a cosine N factor between 1 and 6. For example, sources with a cosine N factor of 1 and a cosine N factor of 6 differ in that 80% of the forward projected beam falls within the angular ranges of ±36.4° and ±15.5°, respectively. Therefore, improved flux utilization can be achieved by judicious selection of the cosine N factor material source and its relative configuration with respect to the rotating deposition surface. For example, using a source with a cosine N factor results in more directionality and therefore less wasted material.

[0035] 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, such as whether material source 118 is a liquid source that evaporates material, a sublimation source that is a subliming material, or a gas source.

[0036] Conventional MBE systems utilize a material source having a cosine N coefficient in the range of about 1 to about 2. It is widely considered by those skilled in the art that a substantially spherical plume is advantageous for high flux uniformity. Further, in conventional material sources, the effective cosine N coefficient can vary in response to the depletion of the source material. This results in a change in the non-uniformity of the spatial flux across the entire deposition surface as the source material is depleted, and this problem worsens if the material source is configured at a non-optimal position with respect to the deposition surface. Therefore, in the present embodiment, it is desirable to design a deposition reactor having an optimal source configuration that can withstand variations in the effective cosine N coefficient.

[0037] Further, in conventional MBE systems, the material source is disposed at a relatively long distance from the formation surface, typically far exceeding the optimal distance. Prior art systems typically use an R scr-sub that far exceeds the diameter of the deposition surface (i.e., α < 45° and R scr-sub >> 2R sub ). A typical BFP of a conventional material source characterized by a cosine N coefficient of 1 < N ≦ 2, in combination with the long distances that the species constituting the source beam have to travel, results in at least one of: (1) a non-optimal growth rate, (2) insufficient uniformity of the flux across the entire deposition surface, (3) a large amount of residual background impurity species that can adversely affect the deposited film, and (4) insufficient flux utilization, measured by the ratio of the total flux emitted from the source to the flux across the deposition surface. That is, the species from the material source in a conventional system tend to be emitted throughout a significant volume of the chamber, in contrast to being directed towards the formation surface.

[0038] In the present method and system, the symmetry axis SA of the plume 134 generated by the material source 118 is directed towards a well-defined portion around the substrate deposition surface 126 of the substrate 122. Specifically, the symmetry axis SA of the plume 134 is shifted and directed towards a point away from the center of rotation of the substrate deposition surface 126. That is, the material source 118 is at a distance R from the axis of rotation AX offset122. The substrate 122 has an axis of symmetry SA that intersects the substrate 122 at a point spaced apart by .mu.m.

[0039] Furthermore, the lateral distance X and the orthogonal distance Z representing the location of the material supply source 118 from the rotation center axis AX of the substrate deposition surface of the substrate 122 are R SUB is scaled to R SUB The relationship of the lateral distance X and vertical distance Z to the substrate 122 can be used to scale the size of the high vacuum reaction chamber 100. By allowing the material source 118 in the reaction chamber 100 to be closer to the substrate 122, the overall size of the reaction system (material deposition system 50) can be made smaller, resulting in reduced costs.

[0040] The outlet opening 130 of the material supply 118 is shown in detail A of FIG. Effective area A src Effective area A src is the radius R src It can be defined as: effective area A SRC can be characterized or designed as multiple independent cosine N element sources. For example, the integer m (m>1) of the element sources subscripted i={1,...,j,...,m} can be characterized or designed as multiple independent cosine N element sources. Ni (θ i ) are characterized by a predetermined material release spatial distribution (BFP). The elemental sources are N i can be chosen to be constant for all values ​​of i, or at least two different element sources can be chosen to be N i ≠N j You can select it with.

[0041] One example of determining the placement of a material source in a material deposition system is to define a radius R SUB A circular substrate deposition surface 126 with radius R = 1.5 can be used to represent a 300 mm diameter substrate 122. SRCThe compound source (i.e., material source) of the circular area defined by S = 0.2 is located in the half-space in the positive z direction relative to the substrate deposition surface 126 and is centered at S (S 0x , S 0y , S 0z ) and the VFP tilt angle α = 45°. ρSRC The discretization is performed in three radial steps with Δθ = 0.1. SRC = 36°, forming a compound source plane with 21 elements. Each elemental source is a modified cosine emitter.

[0042]

number

[0043] Each source element on the VFP is modeled as

[0044]

number

[0045] The flux is emitted directed towards the substrate deposition surface 126 parallel to the surface 126. The intersection of the directed flux segment with a general point P on the substrate deposition surface 126 is then determined by the Euclidean distance norm

[0046]

number

[0047] The substrate 122 or the substrate deposition surface 126 is similarly calculated with ΔR SUB =0.1 and Δθ SUB = 10° radial and angular increments, so that the Cartesian coordinates P(x SUB , y SUB , z SUB ) is obtained.

[0048] The vacuum environment of the material deposition system is sufficient for the mean free path length to maintain the ballistic particle morphology of the material emitted from the source orifice at or greater than the Euclidean distance between the material source exit orifice and the point on the deposition surface that intersects the axis of symmetry of the material emission spatial distribution. Suitable high vacuum conditions are provided that significantly reduce residual background impurity species in the reaction chamber. The cosine N factor of the material source also directly affects the amount of residual background impurity species in the reaction chamber at a given vacuum level. Assuming the source material is composed of sufficiently high-purity material, the impurity concentration that is subsequently available for incorporation into the growing film (i.e., forming additional undesired impurity flux components in the desired material source flux) depends primarily on the deposition rate and vacuum level maintained during deposition. That is, for a given base vacuum level in the reactor prior to the introduction of the source material flux, there is a quantifiable amount of time during which a well-prepared, clean deposition surface will deposit an undesired impurity surface coating. Therefore, it is desirable to simultaneously achieve small flux nonuniformity, high growth rate, and low background impurity concentration.

[0049] In the present disclosure, the offset source material source 118 provides both improved flux non-uniformity across the substrate deposition surface 126 and a reduced source-to-substrate distance compared to conventional MBE systems. That is, an optimal location is determined for a given material source type that achieves reduced flux non-uniformity and increased growth rate for a given substrate deposition surface 126 area compared to conventional MBE systems.

[0050] Furthermore, this embodiment provides an optimal configuration space for the material source(s) utilized in a high vacuum reactor specifically due to the practicality of large area deposition surfaces. Additionally, large deposition area reactors can be further optimized according to this method by appropriate selection of material source characteristics, such as effective cosine N factor, N≧2, and source VFP area.

[0051] In some embodiments, the material source 118 has a cosine N coefficient in the range of 0 < N ≤ 10, such as in the range of 2 ≤ N ≤ 6. Further, in a plurality of embodiments, the material source 118 is arranged optimally and close to the substrate deposition surface 126 as compared to a non-optimal configuration of the prior art. As a result, the emitted plume 134 of the deposition species is deposited on the substrate deposition surface 126 with higher efficiency than in the case of a conventional MBE system. When the travel distance of the source material species is significantly short, the deposition rate of the deposition species on the deposition surface increases inversely proportionally. Thereby, the mean free path required for the deposition species emitted from the material source is significantly reduced, and thus, a region substantially free of collisions can be maintained at a higher operating pressure (i.e., a lower vacuum level). A further advantageous characteristic of the improved growth rate is that the influence of residual background impurity species in the deposited film is reduced.

[0052] "Source utilization rate" refers to the amount (i.e., in volume units) of material physically emitted from the material source 118 across the substrate deposition surface 126. The configuration of a conventional off-axis MBE reactor can achieve a source utilization rate of at most 25%. In contrast, the present embodiment provides a spatially configured plume 134 due to the optimized non-uniformity of the target flux, thereby achieving a maximized deposition rate and thus a higher flux utilization rate. Further, the present embodiment uses a more directive material source (e.g., a cosine N coefficient of up to about 6) than conventional MBE (e.g., a cosine N coefficient of about 1 to 2). Therefore, when optimally configured, the present embodiment further increases the source utilization rate. For example, the source utilization rate using the present embodiment can be from about 30% to about 50%. Thus, the present embodiment provides a film formation process that is more efficient than conventional MBE and achieves an optimal non-uniformity of the target flux with the fastest deposition rate compared to conventional MBE.

[0053] Furthermore, the present embodiments provide optimal high-vacuum conditions for maintaining a sufficiently large mean free path of the film-forming species, thereby enabling the formation of high-quality epitaxial films. The mean free path is the average distance traveled by a moving particle (e.g., atom, molecule, photon) between successive impacts (or collisions), which alters its direction, energy, or other properties. More specifically, some embodiments provide high-vacuum conditions for maintaining a mean free path of the film-forming species that is greater than the distance of the material source 118 from the substrate deposition surface 126. For example, 300 Φ directed into a reactor completely and uniformly filled with inert molecular nitrogen (N2) at 100°K. Al =5×10 19 atoms m -2 ·s -1 For the example of a material source beam consisting of only single Al atoms, which produces a flux of L MFP To obtain a mean free path of Al atoms of 1 m, the maximum working chamber pressure is 10 -6 In practice, the longest unobstructed optical path length required for atoms to travel from the source to the deposition surface is at most L MFP / 2. An additional limitation is the effect of the type and amount of background impurities specific to the type of film being deposited. This embodiment focuses on the growth rate (i.e., the time τ ML ) is the time τ required to deposit an equivalent monolayer of the impurity species. imp than at least a factor λ ≥ 10 3 ~10 4 If it is desired to be twice as fast (i.e. τ imp ≧λ τ ML ) can obtain high-quality films. This reduces the upper limit of the allowable residual impurity pressure in the reactor to 10 -9 ~10 -10 It is blown to about torr.

[0054] Therefore, the mean free path of emitted species generated by the material source is assumed to be ballistic and collision-free until interaction with the deposition surface. Furthermore, the reactor base pressure is assumed to be free of impurity species and do not contribute to the flux profile generated at the deposition surface.

[0055] Referring again to FIGS. 2 and 3 , a method for configuring a material deposition system includes determining material source positions for the purpose of improving the balance between film quality and film growth rate. Two or more material sources can be optimized, with the axis of symmetry of each material source oriented offset from the substrate's rotation axis. For example, some embodiments include determining a minimum lateral distance X and a minimum orthogonal distance Z and a tilt angle for a given material source, the material source having predetermined parameters (e.g., a predetermined cosine N coefficient) such as an outlet opening and a spatial distribution of material output. In another example, some embodiments include determining a tilt angle and a predetermined lateral distance X and an orthogonal distance Z for a given material source, the material source having predetermined parameters (e.g., a predetermined cosine N coefficient) such as an outlet opening and a spatial distribution of material output. In some embodiments, proposed material source positions (and / or angles) can be tested, and one or more of the tilt angle α, lateral distance, orthogonal distance, desired growth rate, and outlet opening shape can be dynamically modified after testing to meet desired layer uniformity. In some embodiments, 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 are determined to meet the new value. In some embodiments, 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 embodiments, the determination of the material source position takes into account when the material source and additional material sources are used together. The method of the present invention is described in more detail with reference to FIG. 8. Optimization of material supply allocation 4-7 are example plots of configuration space for a particular location of the material source 118 relative to the substrate deposition surface 126, with the calculated film non-uniformity plotted as a function of the X and Z coordinates of the material source 118. The configuration space shown in each plot of FIGS. 4-7 corresponds to a particular VFP tilt angle α, a particular cosine N coefficient of the material source 118, and a particular R SUB (representing the region of film formation). The method is not limited to only the configuration space shown in the plots of Figures 4-7, which are merely exemplary. The VFP tilt angle α, cosine N factor, and R are suitable for supporting continuous high-throughput film formation processes using MBE. SUB There exists a configuration space for any combination of values. Table 1 shows the configuration space corresponding to the plots shown in Figures 4-7.

[0056] [Table 1]

[0057] In FIG. 4, plot 300 shows the results for the cases where the cosine N factor is 2, the VFP tilt angle α is 45°, and R SUB 3 shows the configuration space of the location of the material source 118 when the X coordinate, Z coordinate, and R SUBNote that is dimensionless. Plot 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 plotted as a function of the distance X and Z of the material source 118 relative to the substrate deposition surface 126. Curve 310 forms the boundary between the film non-uniformity region of >15% and the film non-uniformity region of 10%. Curve 312 forms the boundary between the film non-uniformity region of 10% and the film non-uniformity region of 5%. Curve 314 forms the boundary between the film non-uniformity region of 5% and the film non-uniformity region of 2%. Curve 316 forms the boundary between the film non-uniformity region of 2% and the film non-uniformity region of 1%. Curve 318 forms the boundary between the film non-uniformity region of 1% and the film non-uniformity region of 0.5%. Curve 320 forms the boundary between the film non-uniformity region of 0.5% and the film non-uniformity region of 0.3%. Note that a particular island 317 of 1% film non-uniformity may exist in the 2% film non-uniformity region (i.e., near the apex of curve 316). Similarly, a particular island of 0.5% film non-uniformity may exist in the 1% film non-uniformity region (i.e., near the apex of curve 318). Similarly, a particular island of 0.3% film non-uniformity may exist in the 0.5% film non-uniformity region (i.e., near the apex of curve 320).

[0058] For a given non-uniformity value, the fastest growth rate can be achieved by providing the shortest possible distance from the exit opening 130 of the material source 118 to the substrate deposition surface 126. Therefore, a point within a given non-uniformity region that provides the shortest possible X and Z distance (i.e., R src-sub =(X 2 +Z 2 ) 1 / 2The fastest growth rate can be achieved by selecting the X and Z distances (where X is minimized). Shorter source-to-formation surface distances result in faster growth rates, i.e., higher throughput for the MBE system. Referring to plot 300 as an example, if a 2% non-uniformity is the goal for the film formation process and the fastest possible growth rate is desired, point A, which is near the apex and just inside curve 314, is selected to obtain the shortest possible X and Z distances, and thus the fastest possible growth rate. In this example, corresponding to point A, material source 118 (with a cosine N factor = 2) with a VFP tilt angle α = 45° 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, corresponding to point B, material source 118 (with a cosine N factor = 2) with a VFP tilt angle α = 45° is set to a distance X of about 3 and a distance Z of about 2.6 to obtain the fastest possible growth rate with a non-uniformity of about 1%.

[0059] In FIG. 5, plot 400 shows the material source 118 with a cosine N factor of 3, a VFP tilt angle α of 45°, and R SUB 4 shows the configuration space of the location of the material source 118 when the X coordinate, Z coordinate, and R SUB Note that is dimensionless. Plot 400 shows a film non-uniformity area of ​​>15%, a film non-uniformity area of ​​10%, a film non-uniformity area of ​​5%, a film non-uniformity area of ​​2%, a film non-uniformity area of ​​1%, and a film non-uniformity area of ​​0.5%, plotted as a function of the X and Z coordinates of the material source 118. Curve 410 Curve 412 forms the boundary between the >15% and 10% membrane non-uniformity regions. Curve 414 forms the boundary between the 10% and 4% membrane non-uniformity regions. Curve 416 forms the boundary between the 2% and 1% membrane non-uniformity regions. Curve 418 forms the boundary between the 1% and 0.5% membrane non-uniformity regions. Note that certain islands of 0.5% membrane non-uniformity may exist in the 1% membrane non-uniformity region (i.e., near the apex of curve 418).

[0060] In one example, corresponding to point A on plot 400, a material source 118 (with a cosine N factor = 3) with a VFP tilt angle α = 45° is set 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, corresponding to point B on plot 400, a material source 118 (with a cosine N factor = 3) with a VFP tilt angle α = 45° is set 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 material source 118 needs to be positioned at a greater X distance for a cosine factor of 3 (point A on plot 400) than for a cosine factor of 2 (point B on plot 300).

[0061] In FIG. 6, plot 500 shows the material source with cosine N factor=6, VFP tilt angle α=45°, and R SUB 5 shows the configuration space of the location of the material source 118 when the X coordinate, Z coordinate, and R SUB Note that is dimensionless. Plot 500 shows a >15% film non-uniformity region, a 10% film non-uniformity region, a 5% film non-uniformity region, a 2% film non-uniformity region, a 1% film non-uniformity region, and a 0.5% film non-uniformity region plotted as a function of the X and Z coordinates of the material source 118. Curve 510 forms the boundary between the >15% and 10% film non-uniformity regions. Curve 512 forms the boundary between the 10% and 5% film non-uniformity regions. Curve 514 forms the boundary between the 5% and 2% film non-uniformity regions. Curve 516 forms the boundary between the 2% and 1% film non-uniformity regions. Curve 518 forms the boundary between the 1% and 0.5% film non-uniformity regions. Note that certain islands of 5% film non-uniformity may exist in the 10% film non-uniformity region (i.e., near the apex of curve 512). Similarly, a particular island of 2% membrane non-uniformity may exist in a region of 5% membrane non-uniformity (i.e., near the apex of curve 514). Similarly, a particular island of 1% membrane non-uniformity may exist in a region of 2% membrane non-uniformity (i.e., near the apex of curve 516). Similarly, certain islands of 0.5% membrane non-uniformity may exist in the 1% membrane non-uniformity region (ie, near the apex of curve 518).

[0062] In one example, corresponding to point A on plot 500, a material source 118 (with a cosine N factor = 6) with a VFP tilt angle α = 45° is set 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, corresponding to point B on plot 500, a material source 118 (with a cosine N factor = 6) with a VFP tilt angle α = 45° is set at a distance X of about 3.7 and a distance Z of about 2.7 to achieve a non-uniformity of about 1%, but at a slightly slower growth rate than point A. Thus, for a non-uniformity of 1%, the material source 118 needs to be positioned at a greater X distance for a cosine factor of 6 (points A or B on plot 500) than for a cosine factor of 3 (point A on plot 400) than for a cosine factor of 2 (point B on plot 300).

[0063] Referring to FIG. 7, plot 600 shows the VFP tilt angle α=30°, material source 118 cosine N factor=3, and R SUB 6 shows the configuration space of the location of the material source 118 when the X coordinate, Z coordinate, and R SUB Note that is dimensionless. Plot 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%, plotted as a function of the X and Z coordinates of the material source 118. Curve 610 forms the boundary between the film non-uniformity region of >15% and 10%. Curve 612 forms the boundary between the film non-uniformity region of 10% and 0.5%. Curve 614 forms the boundary between the 5% and 2% membrane non-uniformity regions. Curve 616 forms the boundary between the 2% and 1% membrane non-uniformity regions. Curve 618 forms the boundary between the 1% and 0.5% membrane non-uniformity regions. Note that certain islands of 1% membrane non-uniformity may exist in the 2% membrane non-uniformity region (i.e., near the apex of curve 616). Similarly, certain islands of 0.5% membrane non-uniformity may exist in the 1% membrane non-uniformity region (i.e., near the apex of curve 618).

[0064] In one example, corresponding to point A on plot 600, a material source 118 (with a cosine N factor = 3) with a VFP tilt angle α = 30° 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, corresponding to point B on plot 600, a material source 118 (with a cosine N factor = 3) with a VFP tilt angle α = 30° is set to a distance X of about 3.05 and a distance Z of about 3.35 to achieve a similar non-uniformity of about 1% but at a slightly slower growth rate than point A. Comparing points A or B on plot 600 with point A on plot 400 shows that, for the same cosine factor = 3, changing the tilt angle α from 30° to 45° affects the X and Z distances to achieve the goal of 1% non-uniformity.

[0065] FIG. 8 is a flow diagram of an example method 700 for configuring staggered material sources in a material deposition system to improve the balance between film quality and film growth rate. Method embodiments include mathematically modeling a material deposition process to select values ​​for certain variables and optimize other variables. For example, for a given material source type and tilt angle, the lateral distance X and the orthogonal distance Z can be optimized, such as minimizing X and Z to achieve a desired layer deposition uniformity at a desired layer growth rate. In other exemplary embodiments, the distances X and Z may be fixed, and the tilt angle can be determined to achieve a desired layer deposition uniformity at a desired growth rate. In yet other embodiments, the distances X and Z may be varied relative to the substrate (R) to achieve a desired deposition uniformity and growth rate. SUB ) or the type of the Cosine N source can be changed.

[0066] Conventional MBE systems are characterized by the use of relatively slow growth rates as a means to achieve precise epilayer thicknesses, highly uniform fluxes, abrupt interfaces between dissimilar epilayers, highly uniform films, highly structured films, and crystalline films with high electronic quality. For example, growth rates in conventional MBE systems can be from about 0.1 monolayers per second (ML / s) to about 10 ML / s. Furthermore, MBE systems typically require specialized yet simple high-vacuum preparation methods to achieve the low residual base pressure required to minimize the incorporation of unintended impurities into the deposited film. This upfront investment in reactor preparation to achieve suitable vacuum conditions for high-quality epitaxy is a key differentiator compared to high-pressure CVD reactors. Furthermore, material sources (such as solid-liquid evaporation sources) require a front-end atmospheric pre-pressure to the reactor, which subsequently becomes inaccessible once the reactor is re-evacuated. Therefore, for high-throughput film formation processes, the epilayer cost per unit area ($ / m) for a given lifetime of material source capability and total deposited film thickness is crucial. 2 High flux utilization efficiency is required to manage the flux uniformity. A further desirable property is reactor size scalability to increase the total deposition area for a given deposition cycle while maintaining low flux non-uniformity. This allows for lower cost per area (e.g., $ / m 2 ) and cost of ownership can be further reduced. It is understood that the increased deposition surface area can include a single large area substrate or multiple smaller substrates advantageously positioned across the deposition surface.

[0067] In conventional MBE systems, there is a direct correlation between the growth rate and the distance between the material source and the formation surface (hereafter referred to as the source-to-formation surface distance). More specifically, the shorter the source-to-formation surface distance, the higher the potential growth rate. The longer the distance to the growth surface, the slower the growth rate. Therefore, to obtain highly uniform films, conventional MBE systems accommodate slow growth rates by placing the material source at a greater distance from the growth surface than the optimal location taught herein. As a result, achieving high growth rates in conventional MBE systems requires significantly shorter source-to-surface distances, which typically compromises film uniformity across the deposition surface and limits the maximum deposition surface area (i.e., limits process scalability).

[0068] In contrast, method 700, according to some embodiments, provides a technique for meeting high growth rates in MBE processes while achieving high quality films. In one example, method 700 provides a film having a thickness uniformity of about ≧95% across the deposition surface (i.e., about ≦5% non-uniformity). 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:

[0069] In step 710, a rotation mechanism is provided. The rotation mechanism rotates the substrate about a central axis of the substrate deposition surface of the substrate. In some embodiments, the substrate has a diameter of 6 inches (150 mm) or greater.

[0070] In step 714, a material source is selected, such as the elemental species of the material and the type of material source. The material source and the substrate are contained within a vacuum environment. In one example of selecting a material source, if the film to be formed includes gallium, the selected species is a gallium species. In another example, if the film to be formed includes aluminum, the selected species is an aluminum species. The type of material source 118 (i.e., gas, liquid, or solid) is then selected based on the selected species. In one example, if the selected species is gallium, a Knudsen evaporation cell for liquid evaporation of gallium is selected. In some embodiments, the material source may be a cosine-N source, for example, with a beam flux profile ranging from about N=1 to about N=6, which is not otherwise possible using conventional MBE. Additional (i.e., multiple) material sources may be included when the material source and additional material source are used together, i.e., to simultaneously deposit different materials on the substrate. In some embodiments, the material source includes a nitrogen plasma source emitting activated nitrogen and an oxygen plasma material source.

[0071] Each material supply source 118 has an outlet opening 130 with an outlet opening surface and a predetermined material emission spatial distribution from the outlet opening surface. When two or more material supply sources are used, a predetermined material emission spatial distribution is obtained for each material supply source. In some embodiments, the outlet opening has an outlet opening shape, and the method further includes selecting the outlet opening shape. The predetermined material emission spatial distribution has an axis of symmetry that intersects the substrate at a point offset from the central axis, and the outlet openings are disposed at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. For cosine N coefficient material sources, a predetermined (e.g., empirical) cosine N coefficient and material emission spatial distribution can be obtained from the supplier of the selected material supply source 118. In one example, the cosine N coefficient of the selected material supply source 118 is 2 or greater, such as about 3 or up to about 6.

[0072] In step 718, either i) a VFP tilt angle α for positioning the selected material source 118 is set, or ii) the orthogonal and lateral distances of the material source exit opening are set. The VFP tilt angle α of the selected material source 118 can be, in one example, from about 30° to less than 90°, in another example, from about 30° to about 60°, and in yet another example, about 45°. In one example, the selected VFP tilt angle α is 45°. Unlike conventional MBE, in which the plume 134 of the material source 118 is delivered substantially perpendicular to the substrate deposition surface 126, the plume 134 of the material source 118 is delivered at an oblique angle.

[0073] In step 726, a desired deposition of material on the substrate is selected to achieve a desired layer deposition uniformity at a desired growth rate. In some embodiments, the target (desired) uniformity (or non-uniformity) value can be expressed as a flux. In some embodiments, the flux or film uniformity can be expressed as a tolerance. In one example, the selected targeted thickness uniformity across the substrate deposition surface 126 is 99% (i.e., corresponding to 1% non-uniformity). In this disclosure, the target value is sometimes referred to as the desired value. The deposition surface area (i.e., the area of ​​the substrate deposition surface 126) is considered in determining the parameters for the desired layer uniformity and desired growth rate. In one example, the substrate 122 is a 3-inch wafer (R SUB In another example, the substrate 122 is a 6-inch wafer (R SUB In yet another example, the substrate 122 is an 8-inch wafer (R SUB In yet another example, the substrate 122 may be a 12-inch (300 mm) wafer (i.e., R SUB =6).

[0074] In step 730, the minimum orthogonal and lateral distances to achieve the desired layer deposition uniformity are determined when the tilt angle is set in step 718. That is, the minimum distances X and Z for positioning the material source 118 are determined using plots of the configuration space corresponding to the selections made in steps 714, 718, and 726, respectively. For example, plot 400 of FIG. 5 shows the minimum orthogonal and lateral distances R SUB 7 shows the configuration space corresponding to a cosine N factor of 3 (selected in step 714), a VFP tilt angle α of 45° (selected in step 718), and a target non-uniformity of 1% (selected in step 726), with α=1.5. The film growth rate is improved by determining the shortest distances X and Z that correspond 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 surface are less than or equal to the mean free path of material emitted from the material source.

[0075] In step 730, if the orthogonal distance and lateral distance were set in step 718, the tilt angle is determined to achieve the desired layer deposition uniformity using the set orthogonal distance and set lateral distance.

[0076] In some embodiments, additional material sources may be used, and step 730 includes determining either the tilt angle or the orthogonal and lateral distances when all material sources are used together.

[0077] In some embodiments, the method of configuring a material deposition system is complete after step 730, for example, if the determined orthogonal and perpendicular distances achieve the desired layer deposition uniformity and growth rate. In an exemplary situation, a point within the 1% film non-uniformity region of plot 400 corresponding to the shortest or nearly shortest possible distances X and Z is selected. In one example, point A near the apex of curve 416 of plot 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 plot 400 may result in longer distances X and Z, thereby resulting in slower growth rates. Therefore, by selecting point A in plot 400 near the apex of curve 416, the shortest or nearly shortest possible distances X and Z are utilized to position the material source 118 relative to the substrate deposition surface 126. This improves the growth rate because the closer the material source 118 is to the substrate deposition surface 126, the faster the growth rate.

[0078] In further embodiments, the determined tilt angles or the determined minimum values ​​of the orthogonal and lateral distances can be tested to see if further optimization is required. In step 734, the configuration of the material source 118 relative to the substrate deposition surface 126 determined in steps 714, 718, 726, and 730 is physically implemented and tested to achieve the targeted growth rate combined with an appropriate growth rate to support a high throughput film formation process. 2, a material source 118 having a particular cosine N coefficient (determined in step 714) is positioned at a distance X and Z from the substrate deposition surface 126 determined in step 730, and a VFP tilt angle α=45° selected in step 718. The vacuum environment 114 of the high-vacuum reaction chamber 100 is pumped to a particular vacuum pressure (e.g., about 10 -11 torr ~ approx. 10 -7torr), the rotation mechanism of step 710 is used to rotate the substrate 122, and the material source 118 is activated. Periodically, the thickness of the epitaxially grown film is measured at multiple sample points along the substrate deposition surface 126. This measurement can be performed, for example, using a reflection high-energy electron diffraction (RHEED) system directed at the substrate deposition surface 126.

[0079] In decision step 738, it is determined based on the measurements made in step 734 whether both the desired non-uniformity selected in step 726 and an appropriately high growth rate to support a high-throughput film formation process have been achieved. If both the target non-uniformity and growth rate have been achieved, method 700 ends. Any configuration of material source 118 relative to substrate deposition surface 126 is a balance between film quality and film growth rate. Thus, if the target non-uniformity and growth rate are not achieved, either the desired film quality or the desired film growth rate may be slightly relaxed. In one example, if the target non-uniformity is not achieved, method 700 can proceed to step 742.

[0080] In 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 can be lowered for that specific application (semiconductor product, manufacturing / cost goals). Method 700 then returns to step 730, where another point is selected within the desired film non-uniformity region of the particular plot in configuration space, where the new point corresponds to a slightly larger distance X or Z, or both, and thus a slightly reduced growth rate. In another example, the lateral and / or orthogonal distances are adjusted, such as by increasing the value if a slower growth rate is acceptable. In a further example, the tilt angle or outlet opening shape is changed, and another iteration of method 700 is performed, where the orthogonal and lateral distances are again determined using the material emission spatial distribution corresponding to the new tilt angle or outlet opening shape.

[0081] In some embodiments, the deposition uniformity of the desired layer of the film can be modified in step 746 if the desired goal is not being achieved. For example, it may be acceptable to decrease the desired uniformity of the film or increase the non-uniformity of the film for a particular application. Method 700 returns to step 726 with the uniformity value decreased (i.e., the non-uniformity value increased), after which another iteration of method 700 begins.

[0082] In some embodiments, the rotation mechanism and material source are housed within a reaction chamber, and the method 700 includes adjusting the radius R of the substrate to scale the size of the reaction chamber. SUB Step 750 may also be included, using the relationship of lateral and orthogonal distances to the material source. For example, after the minimum distances for placing the material sources are determined, the size of the reaction chamber may be reduced. Reducing the size of the reaction chamber may provide benefits such as reducing the cost of manufacturing the chamber and occupying less space in the manufacturing facility.

[0083] Method 700 may also include a step 760 of discharging material to form a semiconductor layer. The substrate is heated while the material is being discharged onto the substrate. Step 760 may include using the optimal placement of the material source relative to the substrate determined in steps 710 through 738. The tilt angle, orthogonal distance, and lateral distance are dynamically adjustable to allow for adjustment of the placement depending on the material source(s) used, which may vary from run to run. The tilt angle, orthogonal distance, and lateral distance may be adjusted by adjusting the position of the substrate. The material supply may be dynamically adjustable by adjusting the temperature or placement of the material source.

[0084] The VFP tilt angle can be selected in step 718 with prior reference to the type of material source 118 selected. For example, if the material source 118 is a liquid evaporation source single open-ended orifice crucible, the tilt angle is limited by the tilt of the crucible relative to the vertical (if placed in a gravitational field) for a given material volume capacity and melt surface position relative to the exit orifice, the exit opening 130. Typically, if the melt surface is sufficiently offset from the exit opening 130, a well-defined VFP will be obtained by adjusting the body diameter D C The VFP at the exit orifice 130 is defined by the exit plane defined by the single exit orifice 130 of the cylindrical crucible. O / L O <1 and D O <D C The opening diameter D O and opening depth L O Therefore, in practice, liquid sources are suitable for angles of 0°<α<70°, more preferably 30°<α<60°, and typically 40°<α<50°. The standard configuration for this type of bulk material source is α=45°. In contrast, gas injector material sources are not constrained by the internal details of the source and can be used for angles of 0°≦α<90°. Clearly, gas injector material source types are available for oblique incidence angles of 70°<α<90°.

[0085] In operation of the high-vacuum reaction chamber 100 in which the position of the material source 118 relative to the substrate deposition surface 126 is improved in accordance with method 700, in one example, the substrate deposition surface 126 (i.e., the substrate 122) rotates. There is a rate at which species are released from the material source 118, and therefore there is an arrival rate of the species to the substrate deposition surface 126. The arrival rate can be expressed, for example, as the number of atoms or species per unit area per unit time. When the high-vacuum reaction chamber 100 is operating, the rotation speed of the substrate 122 may be, for example, from about 1 rpm to about 1000 rpm. However, the minimum rotation speed of the substrate 122 is determined by the arrival rate of the species per unit area per unit time. That is, there is a correlation between the time required to complete one rotation around the substrate 122 and the arrival rate of the species. The deposition of material is averaged over one rotation of the substrate 122. For fast growth rates suitable for supporting high-throughput systems, the rotation speed of the substrate 122 can be, for example, on the order of about tens of rpm to about hundreds of rpm. There is a lower limit to the fundamental depositional surface rotation rate for the minimum incident arrival rate of species, but faster rotation rates will usually be advantageous.

[0086] In summary, the method 700 configures the position of the material source 118 relative to the substrate deposition surface 126 to epitaxially grow high-quality films at growth rates suitable for supporting continuous, high-throughput film formation processes, such as continuous, high-throughput semiconductor manufacturing processes. The distance of the material source 118 from the substrate deposition surface 126 is appropriately short for a high film growth rate suitable for supporting high-throughput film formation processes not otherwise possible using conventional MBE. For example, the method can provide a film growth rate improvement of at least 1 Angstrom / second over conventional MBE. Structure of oxide-based semiconductors The above-described system, with material sources positioned at specially designed positions and angles to obtain highly uniform film layers at high throughput growth rates, can be used to fabricate oxide-based semiconductor devices. P-type doping of various materials, such as p-type doped Mg-based layers, can also be performed. For example, Mg x Zn 1-xOxide-based layers of O(x>0), p-type doped Mg x Zn 1-x Magnesium- and zinc-based oxides, such as MgO layers (0≦x<0.45), or MgZnO layers, can be formed. In some embodiments, the oxide-based layer is a superlattice including 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 released using at least one of active nitrogen plasma, nitrous oxide (NO), ammonia (NH), phosphorus, oxygen plasma, or defective Mg or Zn. This disclosure is intended to describe DUV LEDs. However, other types of semiconductors can be manufactured using the same techniques.

[0087] 9 is a side view of an example of a plasma processing system 900 that can be used to form a high-quality oxide-based film on a substrate 901. The plasma processing system 900 includes a reaction chamber 904, a heater 908, a nitrogen plasma source 912 that generates nitrogen species 916, a magnesium (Mg) source 920 that generates Mg species 924, a phosphorus (P) source 928 that generates P species 932, an aluminum (Al) source 936 that generates Al species 940, a zinc (Zn) source 944 that generates Zn species 948, and an oxygen plasma source 952 that generates oxygen species 956. The emission of the Mg species 924 is controlled by a shutter 960. The emission of the Zn species 948 is controlled by a shutter 964. The emissions 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 shutters, which are not shown in FIG. 9 for clarity. The plasma processing system 900 also includes a vacuum pump 972 fluidly coupled to the reaction chamber 904. Positioning adjustment mechanisms (not shown) can be coupled to each of the material sources 912, 920, 928, 936, 944, and 952 to adjust the position (lateral distance, perpendicular distance, and tilt angle) of the material sources relative to the substrate 901 to meet the desired layer deposition specifications. Positioning adjustment mechanisms (not shown) can also be coupled to the substrate 901 to adjust and translate the position of the substrate horizontally (in the plane of the substrate) or vertically (orthogonal to the plane of the substrate).

[0088] Plasma processing system 900 may also include an optical detector (not shown) and / or a reflection high-energy electron diffraction (RHEED) system (not shown). Plasma processing system 900 includes a controller (not shown), which may be any computing device, such as a portable computer, a tablet computer, a laptop computer, a desktop computer, a centralized server, a mobile computing device, etc.

[0089] The substrate 901 is placed in a reaction chamber 904, where it undergoes a plasma treatment process to form a defect-free oxide-based film on the substrate 901. The substrate 901 is rotatable about a central axis of rotation AX. The substrate 901 can be held or manipulated using, for example, a wafer handling system (not shown). The substrate 901 is positioned at a particular radius R SUB For example, a 6 inch substrate 901 has a radius R of 3 inches. SUB and the 8-inch substrate 901 has a 4-inch radius R SUB and the 12 inch substrate 901 has a 6 inch radius R SUB The side of the substrate 901 facing the material source is the film formation surface 906. The film formation surface 906 is the surface of the substrate 901 that will undergo a plasma treatment process in preparation for the subsequent film formation process. The substrate 901 may also have a backside coating (not shown) to absorb heat from the heater 908.

[0090] The material supply source is disposed on the film formation surface 906 side of the substrate 901, while the heater 908 is disposed on the opposite side of the substrate 901. The heater 908 heats the substrate 901, and then heats the film formation surface 906 of the substrate 901 to a growth temperature T of about 300° C. to about 700° C. g The growth temperature T is suitable for film growth such as g In one example, heater 908 is a radiant heater with a rhenium heating element.

[0091] The nitrogen plasma source 912 is, for example, an inductively coupled plasma (ICP) source that emits a plasma formed from N* or N2*, shown as nitrogen species 916. Activated nitrogen is an allotrope of nitrogen and is formed by passing an electrical discharge through a nitrogen stream. Unlike the inactive nitrogen used in conventional film formation, which has a very high binding energy and can only dissociate at temperatures as high as 2,700 Kelvin (K), activated nitrogen can dissociate at relatively low temperatures (e.g., 700-800 K). The nitrogen plasma source 912 includes an excitation device (not shown) and a vacuum aperture plate (not shown). Additionally, one or more mass flow controllers (MFCs), shown as MFC 976, are fluidly connected to the nitrogen plasma source 912 via gas line 980. The MFC 976 controls the gas flow rate from a gas source (not shown) containing, for example, N. In operation, N feed gas is supplied to the nitrogen plasma source 912 via the MFC 976 and then dissociated by energy imparted by an excitation device (not shown) to produce nitrogen species 916. The nitrogen species 916 enter a deionizer / orifice (not shown) where substantially all of the nitrogen species 916 in an excited (i.e., ionized) state are neutralized before exiting the deionizer / orifice (not shown). In one example, the beam pressure of the nitrogen species 916 is 10 -8 Torr, which is a suitable beam pressure for doping epitaxial films.

[0092] The Mg source 920 is, for example, an evaporation cell that emits Mg species 924 that can be controlled using a shutter 960. In another example, the Mg source 920 generates the Mg species 924 as a precursor gas. Utilizing an evaporation cell and 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 sublimation of 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 per second that strike the substrate surface and is expressed as a beam pressure. In one example, Φ(Mg) is about 10 -7 It's Torr.

[0093] The P source 928 is an evaporation cell that emits P species 932, which can be controlled using a shutter (not shown). The P species 932 can be elemental phosphorus or a phosphorus allotrope, such as diphosphorus (P2), produced by sublimating gallium phosphide (GaP) or by cracking tetraphosphorus (P4) using a conventional cracker. The P species 932 acts as a p-type dopant during film formation and contributes to the formation of a highly uniform oxide-based film. The flux of the P species 932 is represented as Φ(P). In one example, Φ(P) is approximately 10 -7 It's Torr.

[0094] The Al source 936 is, for example, an evaporation cell that emits Al species 940 that can be controlled using a shutter (not shown). In another example, the Al source 936 generates the Al species 940 as a precursor gas. Utilizing an evaporation cell and a precursor gas to generate the Al species 940 reduces the complexity and processing costs associated with the plasma processing system 900. The Al species 940 is, for example, a single aluminum species (e.g., pure aluminum). The flux of the Al species 940 is represented as Φ(Al). In one example, Φ(Al) is about 10 -7 Torr. In another embodiment, instead of the aluminum species, a single indium or gallium species is used.

[0095] The Zn source 944 is an evaporation cell that emits Zn species 948, which can be controlled using, for example, a shutter 964. In another example, the Zn source 944 generates the Zn species 948 as a precursor gas. Utilizing an evaporation cell and a precursor gas to generate 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 an evaporation cell, the Zn species 948 are formed by sublimation of solid zinc within the Zn source 944. The flux of the Zn species 948 is represented as Φ(Zn). In one example, Φ(Zn) is about 10 -7 It's Torr.

[0096] The oxygen plasma source 952 is, for example, an ICP source that emits a plasma formed from one or more gases selected from the group consisting of activated 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 that is supplied to the reaction chamber 904. In examples where the oxygen plasma source 952 is a plasma source, the oxygen plasma source 952 includes an excitation device (not shown) and a deionization device / orifice (not shown). Additionally, one or more mass flow controllers (MFCs), shown as MFC 984, MFC 988, and MFC 992, supply the oxygen plasma source 952 with oxygen via gas line 996. The MFCs 984, 988, and 992 are fluidly connected to each other. The MFCs 984, 988, and 992 control the flow rates of gases from gas sources (not shown) containing, for example, N, O, or N2O. In one example of operation, N and O are mixed in a fixed ratio and fed to the oxygen plasma source 952, where they are subsequently dissociated in their mixed form by energy applied by an excitation device (not shown) to generate oxygen species 956. The oxygen species 956 enter a deionizer / opening (not shown), where substantially all of the oxygen species 956 in an excited (i.e., ionized) state are neutralized before exiting the deionizer / opening (not shown). In one example, 99% O is mixed with 1% N to generate a plasma of oxygen species 965, which then produces a p-type doped film on the film formation surface 906. The oxygen species 956 improves the operational efficiency of the plasma processing system 900 by reducing the required processing temperature level and operating costs of the plasma processing system 900. In some embodiments, p-type doping of the oxide (i.e., formation of a p-type oxide layer) is achieved independently by i) substituting (i.e., replacing) some oxygen atoms (e.g., 1 in 1000 oxygen atoms) in the semiconductor crystal structure with nitrogen, ii) substituting (i.e., replacing) some Mg or Zn atoms (e.g., 1 in 10 Mg or Zn atoms) in the crystal structure with Al or Ga, or by both (i) and (ii).

[0097] Film deposition of oxide-based films in the plasma processing system 900 occurs at temperatures between about 500°C and about 700°C in one example, and at about 600°C in another example. With an 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 III-N materials range from about 900°C to about 1,200°C, and growth temperature tolerances must be controlled to within 5°C. The lower deposition temperatures supported by the plasma processing system 900 of the present embodiment enable (1) less complex and lower-cost processing equipment, (2) lower process energy usage, and (3) greater growth temperature tolerance than conventional systems. The lower growth temperatures and greater growth temperature tolerances facilitate high-quality film growth on larger substrates, thereby facilitating higher manufacturing throughput.

[0098] The vacuum environment 968 is maintained within the reaction chamber 904 by a vacuum pump 972. The vacuum pump 972 may be a conventional variable speed vacuum pump capable of evacuating the reaction chamber 904 at a specific speed known as the pumping speed. A valve (not shown) may be associated with the vacuum pump 972. A pressure sensor (not shown) may be provided to monitor the vacuum pressure within the reaction chamber 904. The vacuum pump 972 is used to maintain an appropriate vacuum pressure within the reaction chamber 904. The vacuum pressure within the reaction chamber 904 during film formation may be, for example, about 10 -11 torr ~ approx. 10 -5 It's torr.

[0099] In another embodiment of the plasma processing system 900, pure oxygen (O) is supplied to the reaction chamber 904 via heated piping (not shown) rather than via the oxygen plasma source 952. The temperature of the oxygen entering the reaction chamber 904 is, for example, between about 200°C and about 300°C. In one example, the heated piping (not shown) is formed from sapphire.

[0100] The film formation surface 906 of the substrate 901 is a target for materials supplied 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. A shutter 960 is disposed in the path of Mg species 924 emitted from the Mg source 920. When open, the shutter 960 allows the Mg species 924 to impinge on the film formation surface 906 of the substrate 901. When closed, the shutter 960 prevents the Mg species 924 from impinging on the film formation surface 906 of the substrate 901. A shutter 964 is disposed in the path of Zn species 948 emitted from the Zn source 944. When open, the shutter 964 allows the Zn species 948 to impinge on the film formation surface 906 of the substrate 901. When closed, the shutter 964 prevents the Zn species 948 from impinging on the film formation surface 906 of the substrate 901. Other shutters (not shown) similarly control the impingement of nitrogen species 916, P species 932, Al species 940, and oxygen species 956 onto the film formation surface 906 of the substrate 901.

[0101] The reaction chamber 904 is heated to a desired film growth temperature T g and vacuum pressure, nitrogen plasma source 912, Mg source 920, P source 928, Al source 936, Zn source 944, and oxygen plasma source 952 are activated. The combined bombardment of nitrogen species 916, Mg species 924, P species 932, Al species 940, Zn species 948, and oxygen species 956 onto film formation surface 906 of substrate 901 forms an oxide-based layer on film formation surface 906.

[0102] 9 shows that the Mg source 920 and the Zn source 944 are positioned at a fixed lateral distance X from the central axis of rotation AX of the substrate 901 and a fixed vertical distance Z from the plane of the film-forming surface 906. This positioning is shown for illustrative purposes. The lateral distance X and 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. Furthermore, the Mg source 920 and the Zn source 944 are positioned at an inclination angle α of a virtual flux plane (VFP) 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 similarly positioned at a lateral distance X from the central axis of rotation AX of the substrate 901 and a vertical distance Z from the plane of the film-forming surface 906. Thus, the Mg source 920, Zn source 944, nitrogen plasma source 912, P source 928, Al source 936, and oxygen plasma source 952 are "off-axis" material sources.

[0103] FIG. 10A is a cross-sectional view of an example LED device structure 1000, which is an example of an oxide-based structure fabricated in accordance with some embodiments. The LED device structure 1000 is useful, for example, for forming deep UV LEDs. Deep UV LEDs can operate in the UVC wavelength range of about 100 nm to about 280 nm. The LED device structure 1000 may be used to form a single complete device or may be used to form multiple devices as part of a high-volume, high-throughput manufacturing process. The LED device structure 1000 includes a substrate 1004 upon which multiple oxide-based layers are deposited. Specifically, the LED device structure 1000 includes a substrate 1004 having deposited thereon, in order, an MgZnO buffer layer 1008, an MgO-MgZnO multilayer 1012, an n-type MgZnO layer 1016, an NID layer 1020, and a p-type MgZnO layer 1024.

[0104] LED device structure 1000 is an example of a lateral PIN diode. NID layer 1020 functions as an intrinsic heterojunction between n-type MgZnO layer 1016 and p-type MgZnO layer 1024. A heterojunction is defined as the interface between two layers of dissimilar crystalline semiconductors characterized by unequal bandgaps.

[0105] In one example, substrate 1004 is formed from 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, and a diameter of substrate 1004 of about 4 inches to about 12 inches. In another example, substrate 1004 is formed from silicon carbide, silicon, or gallium nitride (GaN), which absorbs light and therefore does not transmit light 1028.

[0106] The MgZnO buffer layer 1008 is formed from MgZnO and has a thickness of, for example, about 200 nm to about 1 μm. The MgZnO buffer layer 1008 functions to minimize threading dislocations, thereby reducing the defect density of the film formed on the MgZnO buffer layer 1008.

[0107] The MgO-MgZnO multilayer 1012 is a superlattice layer formed of a plurality of alternating MgO sublayers 1013a and MZnO sublayers 1013b. For simplicity, each sublayer 1013a and Although two of the sublayers 1013b are shown, more may be included. The MgO-MgZnO multilayer 1012 serves to further minimize threading dislocations, thereby reducing the defect density of films formed on the MgO-MgZnO multilayer 1012.

[0108] The n-type MgZnO layer 1016 is formed from MgZnO and is n-type doped with, for example, aluminum, gallium, or indium. Aluminum, for example, is a group III metal that has the desirable property of being highly evaporable. The n-type MgZnO layer 1016 has a thickness of, for example, about 200 nm to about 1 μm.

[0109] The NID layer 1020 is a superlattice layer of alternating sublayers 1021a and 1021b. For simplicity, two of each sublayer 1021a and 1021b are shown, but more sublayers may be included. Some sublayers may be formed, for example, from intrinsic MgZnO or MgO. Additionally, the NID layer 1020 may include one or more quantum well structures formed from narrow bandgap materials. In one example, the NID layer 1020 is formed primarily from MgO (i.e., a 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 10 nm to about 50 nm. In another example, the NID layer 1020 is formed as a superlattice structure using MgZnO or an MgZnO-ZnO alloy.

[0110] The p-type MgZnO layer 1024 is formed, for example, from 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 achieved using a plasma of N* or N2*, for example, according to the method described below with reference to FIG. 11. In another example, the p-type doping of the p-type MgZnO layer 1024 is achieved using an independent source of nitrous oxide (NO) or ammonia (NH3). The p-type MgZnO layer 1024 provides the ability to tune the device's bandgap over a wide wavelength range, whereas conventional III-N films have limited bandgap tuning capabilities. For example, it is very difficult to form a UV LED operating below 190 nm (i.e., 6 eV) using only AlN. In some cases, boron-AlN compounds are used. However, this material requires high levels of nitrogen and high deposition temperatures, both of which can be very costly, technically impractical, and / or commercially unviable. Furthermore, doping boron-AlN compounds to a p-type conductivity is very problematic. In contrast, p-type MgZnO films can be fabricated at readily achievable deposition temperatures and can be doped to a p-type conductivity with readily achievable levels of nitrogen.

[0111] Following the formation of the p-type MgZnO layer 1024, electrical contacts (e.g., anode and cathode, not shown) are formed using standard metallization and lithography processes. The electrical contacts may be formed, for example, from nickel (Ni), palladium (Pd), titanium (Ti), aluminum (Al), titanium nitride (TiN), or titanium aluminum (TiAl).

[0112] In one example, the epitaxial layers of LED device structure 1000 are deposited such that charge carriers (i.e., electrons and holes) move vertically and light (i.e., photons), shown as light 1028 in Figure 10A, is also emitted vertically. In another example, the epitaxial layers of LED device structure 1000 are deposited such that charge carriers move laterally and light is also emitted laterally. In Figure 10A, "lateral" refers to a direction substantially along the plane of layer growth, while "vertical" refers to a direction substantially perpendicular or or to the plane of layer growth.

[0113] In operation, n-type MgZnO layer 1016 generates electrons that move vertically into NID layer 1020. Continuing the example, p-type MgZnO layer 1024 moves vertically into 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 examples where the LED device structure 1000 is a UVC LED, the NID layer 1020 is designed to emit light in the wavelength range of about 100 nm to about 280 nm. In examples where the substrate 1004 is substantially transparent to light, a percentage of the light emitted from the NID layer 1020 is emitted directly through the substrate 1004.

[0114] FIG. 10B is a cross-sectional view of an optoelectronic device embodied as an LED device structure 1030, in which a multi-region stack 1031 includes a crystal polarity having either an oxygen-polar or metal-polar crystal structure along a growth direction 1032. In FIG. 10B, the growth direction 1032 is perpendicular to the horizontal plane of the layers of the multi-region stack 1031. The LED device structure 1030 is useful, for example, for forming deep UV LEDs. Deep UV LEDs can operate in the UVC wavelength range of about 100 nm to about 280 nm. The LED device structure 1030 may be used to form a single completed device or may be used to form multiple devices as part of a high-volume, high-throughput manufacturing process. The LED device structure 1030 includes a substrate 1034 upon which at least five crystal polarity multi-region stacks 1031 are epitaxially deposited. Multi-region stack 1031 includes regions (ie, layers) 1038, 1042, 1046, 1050, and 1054.

[0115] In one embodiment, substrate 1034 is formed from sapphire, calcium chloride, or magnesium oxide, which is substantially transparent to light (e.g., light 1058). In this example, substrate 1034 may have a thickness of about 500 μm to about 1,000 μm. Substrate 1034 may have a diameter of about 4 inches to about 12 inches. In another example, substrate 1034 is formed from silicon carbide, silicon, or gallium nitride (GaN), which absorbs light and therefore does not transmit light 1058.

[0116] A 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 functions to improve the atomic surface quality of the substrate 1034 by minimizing threading dislocations, thereby reducing the defect density of films formed on the first region 1038. A second region 1042 on the buffer layer 1038 functions as a crystal structure improvement layer. The second region 1042 further minimizes threading dislocations, thereby reducing the defect density of films formed on the second region 1042.

[0117] 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 (NID) layer between the third region 1046 and the fifth region 1054. The second conductivity type is the opposite of 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.

[0118] The multi-region laminate 1031 is made of Mg (x) Zn (1-x) and at least one region (i.e., layer) that is a bulk semiconductor material containing ZnO, MgO, and Mg. (x) Zn (1-x) In one embodiment, the buffer layer (first region 1038) can be made of MgZnO, for example, having a thickness of about 200 nm to about 1 μm. In one embodiment, the second region 1042 is a superlattice layer formed of multiple alternating MgO sublayers 1043 a and 1043 b, where two of each sublayer 1043 a and 1043 b are shown for clarity, but more sublayers may be included.

[0119] In some embodiments, the third region 1046 or the fifth region 1054 (n-type or At least one of the third region 1046 or the fifth region 1054 is formed by introducing at least one of silicon, germanium, nitrogen, aluminum, gallium, nickel, or phosphorus into the oxygen-polar or metal-polar crystalline structure of the multi-region stack 1031. In some embodiments, at least one of the third region 1046 or the fifth region 1054 is formed by introducing at least one of Mg (x) Zn (1-x)The third region 1046 or fifth region 1054 is formed using a compositional gradient of bulk or bulk-like composition in the form of O. X is a spatially dependent value that varies along the growth direction. That is, the third region 1046 or fifth region 1054 is formed using a compositional gradient of Mg that varies along the growth direction 1032 of oxygen polarity or metal polarity (vertical in FIG. 10B). (x) Zn (1-x) The composition gradient can consist of a spatially dependent composition of O. An example of a composition gradient is represented by the graded shading of the third region 1046 in Figure 10B.

[0120] 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 a compositional gradient of the effective alloy composition of the superlattice. (x) Zn (1-x) O and Mg (y) Zn (1-y) The superlattice has multiple bilayer pairs formed from alternating layers of O (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 growth direction 1032 of oxygen polarity or metal polarity. An example of a composition gradient of the superlattice is represented by the fifth region 1054 of FIG. 10B, in which sublayers 1055a1 and 1055a2 are composed of Mg (x) Zn (1-x) O, and sublayers 1055b1 and 1055b2 may be Mg (y) Zn (1-y) Mg (x) Zn (1-x) O and Mg (y) Zn (1-y) The alternating sublayers of O form a bilayer. In sublayers 1055a1 and 1055a2, x varies along the growth direction 1032. Similarly, in sublayers 1055b1 and 1055b2, y varies along the growth direction 1032.

[0121] In another embodiment, FIG. 10B can also represent an optoelectronic device such as an LED having a nonpolar crystal material structure. In such an embodiment, the multi-region laminate 1031 includes a nonpolar crystal material structure along the growth direction 1032. Similar to the polar crystal structure described above, the multi-region laminate 1031 of the nonpolar crystal structure includes regions (i.e., layers) 1038, 1042, 1046, 1050, and 1054. The first region 1038 of the multi-region laminate 1031 is a buffer layer formed on the surface of the substrate 1034. The second region 1042 on the buffer layer 1038 functions as a crystal structure improvement layer. The third region 1046 on the second region 1042 has a first conductivity type such as n-type or p-type conductivity. The fourth region 1050 is an intrinsic conductivity type (NID) layer. The fifth region 1054 has a second conductivity type opposite to the first conductivity type. At least one region of the multi-region laminate 1031 is a bulk or bulk-like semiconductor material containing Mg (x) Zn (1-x) O. At least one region of the multi-region laminate 1031 is a superlattice, and the superlattice includes at least two compositions selected from ZnO, MgO, and Mg (x) Zn (1-x) O.

[0122] In some embodiments of the nonpolar crystal structure of FIG. 10B, at least one of the third region 1046 or the fifth region 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, at least one of the third region 1046 or the fifth region 1054 (n-type or p-type conductive region) is formed using a composition gradient of a selective alloy composition of a superlattice, and this superlattice is 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) and has a plurality of bilayer pairs. The effective alloy composition of the superlattice changes along the growth direction (i.e., x and y are spatially dependent on the growth direction). For example, in the fifth region 1054, the sub-layers 1055a1 and 1055a2 are Mg(x) M (1-x) On the other hand, the sublayers 1055b1 and 1055b2 can be Mg (y) M (1-y) O. In some embodiments, the multi-region laminate 1031 is Mg ( x) M (1-x) O composition (0.55 < x ≤ 1.0, where M is selected from Zn, Al, Ga, Ni, N, and P) (that is, all compositions of the multi-region laminate 1031 are selected from these).

[0123] FIG. 11 is, for example, a flowchart of an example of a method 1100 for forming a high-quality oxide-based LED device structure using the plasma processing system 900 of FIG. 9. The method 1100 includes the following steps described using the device structure 1000 of FIG. 10A, which can also be applied to the device structures of FIG. 10B and other oxide devices.

[0124] Step 1110 includes rotating the substrate about the central axis of the substrate deposition surface of the substrate and heating the substrate. As preparation for manufacturing a high-quality oxide-based LED, the substrate is loaded into the reaction chamber. The substrate is formed from, for example, calcium fluoride, MgO (111) and (00l) 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 in the reaction chamber is pumped down to about 10 -5 Torr or less, and the chamber is evacuated so that the substrate is contained in a vacuum environment. Further, a heater is activated to bring the film formation surface of the substrate to the desired growth temperature T g .

[0125] Step 1115 includes providing at least one material source for supplying material to the substrate. The material sources are contained within the vacuum environment of the reaction chamber. Each material source has i) an exit opening having an exit opening surface, and ii) a predetermined spatial distribution of material emission from the exit opening surface. The predetermined spatial distribution of material emission has an axis of symmetry that intersects the substrate at a point offset from the central axis. The exit opening is disposed at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate. All material sources within the plasma reaction chamber are activated with their associated shutters 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 nitrous oxide (NO) source, an ammonia (NH) source, and an oxygen plasma source, activated with their associated shutters closed to prevent species from impinging on the film formation surface of the substrate.

[0126] Step 1120 includes discharging 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 individual layers of a semiconductor device. During the discharging of step 1120, the outlet opening of at least one material source is positioned such that i) an orthogonal distance and a lateral distance are minimized with respect to a set tilt angle to achieve a desired layer deposition uniformity at a desired layer growth rate of the semiconductor layer on the substrate, or ii) a tilt angle is determined with respect to a set orthogonal distance and a set lateral distance to achieve a desired layer deposition uniformity at a desired layer growth rate of the semiconductor layer on the substrate.

[0127] While the layers of device structure 1000 of FIG. 10A are used below to illustrate the process of FIG. 11, other layers can also be formed using the methods and systems disclosed herein. In step 1122, an MgZnO buffer layer (e.g., 1008) is formed to a desired thickness. That is, shutters associated with the oxygen plasma source, Mg species (e.g., shutter 960), and Zn species (e.g., shutter 964) are opened, allowing oxygen species to impinge on the substrate's deposition surface. In one example, the MgZnO buffer layer formed has a thickness of approximately 200 nm. During film growth, the vacuum pressure in the reaction chamber is maintained at approximately 100 s by a vacuum pump to ensure ballistic transport of the Mg, Zn, and oxygen species to the substrate's deposition surface. -5 Torr.

[0128] In step 1125, an MgO-MgZnO multilayer (e.g., layer 1012) is formed to a desired thickness. That is, shutters associated with the oxygen plasma source, the Mg species, and the Zn species are opened, causing oxygen species to impinge on the substrate's deposition surface and form the MgZnO component (sublayer) of the MgO-MgZnO multilayer. The Zn species shutter (e.g., shutter 964) is then closed to form the MgO component (sublayer) of the MgO-MgZnO multilayer. The Zn shutter is alternately opened and closed during the formation of each of the multiple sublayers of the superlattice MgO-MgZnO multilayer until the desired layer thickness is achieved.

[0129] In 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, Mg species, and Zn species are opened, allowing oxygen species to impinge on the deposition surface of the substrate to form the MgZnO component of the n-type MgZnO layer. Simultaneously, a shutter controlling the Al source is opened, allowing Al species to impinge on the deposition surface of the substrate to act as n-type dopants in the n-type MgZnO layer.

[0130] In step 1135, an NID layer (e.g., layer 1020) is formed to a desired thickness. In an example where the NID layer includes one or more quantum well structures formed from narrow bandgap zinc oxide (ZnO) quantum well sublayers, the MgO barrier material is formed by opening an Mg shutter (e.g., shutter 260) and a shutter associated with an oxygen plasma source to allow Mg and oxygen species to impinge on the deposition 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 deposition surface of the substrate. The Mg shutter and the Zn shutter are alternately opened and closed during the formation of each of the multiple sublayers of the NID layer until the desired layer thickness is achieved. In one example, the NID layer has a thickness of approximately 25 nm.

[0131] In 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, Mg species, and Zn species are opened, allowing oxygen species to bombard the substrate's deposition surface and form the MgZnO component of the p-type MgZnO layer. Simultaneously, a shutter associated with the nitrogen plasma source is opened, allowing nitrogen species to bombard the substrate's deposition surface. The nitrogen species, e.g., N* or N2*, functions 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.

[0132] In step 1145, electrical contacts are formed on the LED device structure (e.g., device 1000) using conventional lithography and metallization processes. The LED device structure is a vertical conduction LED, in which charge carriers interact and recombine in the NID layer to generate light that is emitted from the LED device structure. In another example, method 1100 is used to form a lateral conduction type LED, in which light emission occurs laterally.

[0133] In summary, plasma processing systems and methods for forming high-quality oxide-based devices (e.g., DUV LEDs) offer 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 required for high-quality film deposition, especially for substrates larger than 4 inches in diameter. This constraint can result in non-uniform temperature profiles across the film formation surface, thereby producing low-quality or unusable devices. Finally, conventional III-N films have limited device bandgap tuning capabilities, limiting flexibility in semiconductor device design and utilization, particularly in the fabrication of DUV LEDs. In contrast, the inventive plasma processing systems and methods disclosed herein emphasize the production of high-quality films on larger substrates, greater flexibility in device utilization, increased manufacturing throughput, and reduced manufacturing costs.

[0134] 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 are classified as non-stoichiometric materials, exhibiting 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 structures are Mg y Zn 1-y O / Mg x Zn 1-x The semiconductor layer may be a superlattice including sublayers of a) MgO and ZnO, b) MgZnO and ZnO, or c) MgZnO and MgO.

[0135] Examples of MgZnO structures grown according to this embodiment include MgO as layers and substrates, Mg x Zn 1-x O(x>0.5) layer (rock salt) and MgO / Mg x Zn 1-xIn some embodiments, Mg x Zn 1-x O(0≦x<0.45) superlattice, [Mg x Zn 1-x O, 0≦x<0.45] / [Mg y Zn 1-y O, 0≦y<0.45] (x≠y) superlattice, and bulk Mg x Zn 1-x Wurtzite-type MgO (0≦x<0.45) and other gradient compositions x Zn 1-x Polar structures containing O (x<0.45) can be produced. Bulk Mg x Zn 1-x The O gradient composition can include induced p-type or n-type doping. For example, some methods can induce p-type by grading from WBG to NBG for O polarity on a substantially C-plane orientation, or by grading from NBG to WBG for metallic polarity on a substantially C-plane orientation. In another example, methods can induce n-type by grading from WBG to NBG for metallic polarity on a substantially C-plane orientation, or by grading from NBG to WBG for O polarity on a substantially C-plane orientation. In some embodiments, the graded effective alloy composition can be a grading of bulk Mg x Zn 1-x It can be formed by grading the superlattice unit cell using the bulk criteria described for O.

[0136] In addition to the polarization-type doping described in the previous paragraph, impurity-type doping may also be used, and in some embodiments, both impurity and polarization types of doping may be used.

[0137] Another embodiment includes forming devices using polarization doping of MgZnO with composition x<0.45. Yet another embodiment includes forming devices using polarization doping of MgO / ZnO or [Mg x Zn 1-x O, 0 ≤ x ≤ 1] / [Mg y Zn 1-y0, 0≦y≦1 (x≠y). x Zn 1-x O structure (x>0.55).

[0138] The structures can be grown on a variety of substrates, including MgO (111) and (001) surface orientations, GaO (-201) and (010) surface orientations, AlO (c- and r-planes), Si(111) for use with wurtzite MgZnO (x<0.45), Si(001) for use with MgZnO (x>0.55), rare earth oxide buffer layers, and MgZnO superlattice buffer layers.

[0139] MgZnO superlattices and multiple quantum wells (MQWs) allow for thicker layers for quantization effects and are easier to grow than AlGaN or AlN / GaN superlattices.

[0140] Reference has been made in detail to embodiments of the disclosed invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided as an explanation of the inventive technology, not as a limitation of the inventive technology. Indeed, while the specification has described in detail specific embodiments of the invention, those skilled in the art will, upon understanding the foregoing, be able to make alterations, modifications, and variations of these embodiments. It will be understood that equivalents and variations thereof are readily conceivable. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Accordingly, it is intended that the present subject matter encompass all such modifications and variations that come within the scope of the appended claims and their equivalents. These and other modifications and variations of the present invention can be practiced by those skilled in the art without departing from the scope of the present invention, which is more particularly set forth in the appended claims. Moreover, those skilled in the art will appreciate that the foregoing description is illustrative only and is not intended to limit the invention.

Claims

1. a substrate, and a multi-region stack epitaxially deposited on the substrate; An optoelectronic device comprising: The multi-domain stack comprises a crystal polarity having an oxygen-polar crystal structure or a metal-polar crystal structure along a growth direction, and the multi-domain stack is a first region including a buffer layer; a second region including a crystal structure improving layer; a third region comprising the 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; Including, At least one region of the multi-region stack comprises Mg （ｘ） Zn （１－ｘ） a bulk semiconductor material containing O, At least one region of the multi-region stack is made of ZnO, MgO, and Mg （ｘ） Zn （１－ｘ） O, The optoelectronic device.

2. 2. The device of claim 1, wherein at least one of the third region or the fifth region is formed by introducing at least one of silicon, germanium, nitrogen, aluminum, gallium, nickel, or phosphorus into the oxygen-polar crystal structure or the metal-polar crystal structure.

3. At least one of the third region or the fifth region is Mg （ｘ） Zn （１－ｘ） 10. The device of claim 1, formed using a compositional gradient of bulk composition in the form of O, where x is spatially dependent and varies along the growth direction.

4. At least one of the third region or the fifth region includes the superlattice, and the superlattice is Mg （ｘ） Zn （１－ｘ） O and Mg （ｙ） Zn （１－ｙ） O, where x≠y; the superlattice is formed using a compositional gradient of the effective alloy composition of the superlattice; the effective alloy composition of the superlattice varies spatially along the growth direction; The device of claim 1 .

5. a substrate, and a multi-region stack epitaxially deposited on the substrate; An optoelectronic device comprising: The multi-region stack comprises a non-polar crystalline material structure along a growth direction, the multi-region stack comprising: a first region including a buffer layer; a second region including a crystal structure improving layer; a third region comprising the 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; Including, At least one region of the multi-region stack comprises Mg （ｘ） Zn （１－ｘ） a bulk semiconductor material containing O, At least one region of the multi-region stack is made of ZnO, MgO, and Mg （ｘ） Zn （１－ｘ） O, The optoelectronic device.

6. 6. The device of claim 5, wherein at least one of the third region or the fifth region is formed by introducing at least one of silicon, germanium, nitrogen, aluminum, gallium, nickel, or phosphorus into the non-polar crystalline material structure.

7. At least one of the third region or the fifth region includes the superlattice, and the superlattice is Mg （ｘ） M （１－ｘ） O and Mg （ｙ） M （１－ｙ） and O, where x≠y and M is selected from Zn, Al, Ga, Ni, N, and P; the superlattice is formed using a compositional gradient of the effective alloy composition of the superlattice; the effective alloy composition of the superlattice varies along the growth direction; The device of claim 5.

8. The multi-region laminate is made of Mg. （ｘ） M （１－ｘ） 6. The device of claim 5, wherein the element is of the formula: 0, 0, 0 composition, 0.55<x≦1.0, and M is selected from Zn, Al, Ga, Ni, N, and P.

9. rotating the substrate about a central axis of a substrate deposition surface of the substrate; heating the substrate; providing a material supply source for supplying material to the substrate, the material supply source having i) an outlet opening having an outlet opening face, and ii) a predetermined material emission spatial distribution from the outlet opening face, the predetermined material emission spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis, the outlet opening being disposed 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; and releasing the material from the material source to form a semiconductor layer on the substrate; A method for forming a semiconductor layer, comprising: The method, wherein the outlet opening is positioned to: i) achieve a desired layer deposition uniformity at a desired layer growth rate of the semiconductor layer on the substrate by minimizing the perpendicular distance and the lateral distance with respect to a set tilt angle; or ii) achieve a desired layer deposition uniformity at the desired layer growth rate of the semiconductor layer on the substrate by determining the tilt angle with respect to a set perpendicular distance and a set lateral distance.

10. 10. The method of claim 9, wherein the material source is a cosine N source, where N > 2.

11. 10. The method of claim 9, wherein the substrate has a diameter of 6 inches (150 mm) or greater.

12. the material supply source is a nitrogen plasma source that emits active nitrogen; The method of claim 9 , wherein the method further comprises providing an oxygen plasma source.

13. providing a source of magnesium (Mg) and a source of zinc (Zn); The semiconductor layer is Mg Ｘ Zn １－ｘ O layer, x>0; The method of claim 12.

14. 14. The method of claim 13, wherein the semiconductor layer is a superlattice comprising sublayers of a) MgO and ZnO, b) MgZnO and ZnO, or c) MgZnO and MgO.

15. the material source is a magnesium (Mg) source; The method further comprises providing a zinc (Zn) source; The semiconductor layer is an MgZnON layer.

10. The method of claim 9.

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

17. rotating the substrate about a central axis of a substrate deposition surface of the substrate; heating the substrate; disposing a plurality of material supply sources facing the substrate, the material supply sources including a magnesium (Mg) source and a nitrogen or oxygen plasma source, each of the plurality of material supply sources having i) an exit opening having an exit opening face, and ii) a predetermined material emission spatial distribution from the exit opening face, the material emission spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis, the exit openings disposed at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate; discharging materials from the plurality of material sources onto the substrate to form an oxide-based layer on the substrate; 1. A method for forming an oxide-based semiconductor layer, comprising: The method, wherein the outlet opening is positioned to: i) achieve a desired layer deposition uniformity at a desired layer growth rate of the oxide-based layer on the substrate by minimizing the perpendicular distance and the lateral distance with respect to a set tilt angle; or ii) achieve a desired layer deposition uniformity at the desired layer growth rate of the oxide-based layer on the substrate by determining the tilt angle with respect to a set perpendicular distance and a set lateral distance.

18. the plurality of material sources further comprises a zinc (Zn) source; The oxide-based layer is Mg Ｘ Zn １－ｘ O and x>0; 18. The method of claim 17.

19. 18. The method of claim 17, wherein the oxide-based layer is a p-type doped Mg-based layer.

20. the oxide-based layer is a p-type doped layer; The emission may be activated nitrogen plasma, nitrous oxide (N ２ O), ammonia (NH ３ 20. The method of claim 17, comprising using one of: phosphorus, oxygen plasma, or defective Mg or Zn.

21. The oxide-based layer is formed of wurtzite Mg ｘ Zn １－ｘ 18. The method of claim 17, wherein the polar structure comprises O, and 0≦x<0.

45.

22. The polar structure is Mg ｘ Zn １－ｘ 22. The method of claim 21, wherein the p-type or n-type is induced by a gradient composition of O, and 0≦x<0.

45.

23. The oxide-based layer comprises: a) Mg Ｘ Zn １－ｘ O, 0≦x≦1 and b) x ≠ y Mg Ｙ Zn １－Ｙ 18. The method of claim 17, wherein the superlattice is 0, 0≦y≦1.

24. 18. The method of claim 17, wherein the oxide-based layer is a superlattice comprising sublayers of a) MgO and ZnO, b) MgZnO and ZnO, or c) MgZnO and MgO.

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

26. The oxide-based layer is a non-polar Mg Ｘ Zn １－ｘ 18. The method of claim 17, wherein the aryl group is in the O structure and x>0.

55.

27. 18. The method of claim 17, wherein the substrate has a diameter of 6 inches (150 mm) or greater.

28. rotating a substrate deposition surface of a substrate about a central axis of the substrate deposition surface; heating the substrate; disposing a plurality of material supply sources facing the substrate, the material supply sources including a magnesium (Mg) source, a zinc (Zn) source, and a nitrogen or oxygen plasma source, each of the plurality of material supply sources having i) an exit opening having an exit opening surface, and ii) a predetermined material emission spatial distribution from the exit opening surface, the material emission spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis, the exit openings being disposed at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate; discharging materials from the plurality of material sources onto the substrate to form a p-type doped layer on the substrate; 1. A method for forming a p-type doped semiconductor layer, comprising: the exit opening is positioned to: i) minimize the orthogonal distance and the lateral distance with respect to a set tilt angle to achieve a desired layer deposition uniformity at a desired layer growth rate of the p-type doped layer on the substrate; or ii) determine the tilt angle with respect to a set orthogonal distance and a set lateral distance to achieve a desired layer deposition uniformity at the desired layer growth rate of the p-type doped layer on the substrate.

29. 30. The method of claim 28, wherein the plurality of material sources further comprises a phosphorus source for providing phosphorus as a p-type dopant.

30. 29. The method of claim 28, wherein the p-type doped layer is an oxide layer, and releasing the 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.

31. 30. The method of claim 28, wherein the p-type doped layer comprises MgZnO.

32. The plurality of material sources include nitrous oxide (N) for achieving p-type doping of the p-type doped layer. ２ O) or ammonia (NH ３ 29. The method of claim 28, further comprising:

33. providing a rotation mechanism for rotating the substrate about a central axis of a substrate deposition surface of the substrate; selecting a material source for supplying material to the substrate, the material source having i) an outlet opening having an outlet opening face, and ii) a predetermined material emission spatial distribution from the outlet opening face, the predetermined material emission spatial distribution having an axis of symmetry that intersects the substrate at a point offset from the central axis, and the outlet opening being disposed at an orthogonal distance, a lateral distance, and an inclination angle relative to the central axis of the substrate; setting either i) the tilt angle, or ii) the orthogonal and lateral distances of the outlet openings of the material supply; selecting a desired deposition of the material on the substrate to achieve a desired layer deposition uniformity at a desired growth rate; i) the minimum values ​​of the orthogonal distance and the lateral distance to achieve the desired layer deposition uniformity using the set tilt angle, or ii) the set orthogonal distance and the and determining the tilt angle to achieve the desired layer deposition uniformity using the set lateral distance.

1. A method of configuring a material deposition system, comprising: The method, wherein the substrate and material source are contained within a vacuum environment.

34. i) physically testing the determined minimum values ​​of the orthogonal distance and the lateral distance or ii) the determined tilt angle; and if the test does not satisfy the desired layer deposition uniformity, modifying at least one of the tilt angle, the desired growth rate, the lateral distance, and the orthogonal distance; 34. The method of claim 33, further comprising:

35. 34. The method of claim 33, wherein the tilt angle, the orthogonal distance, and the lateral distance are dynamically adjustable.

36. 36. The method of claim 35, wherein the tilt angle, the orthogonal distance, and the lateral distance are dynamically adjustable by adjusting the position of the substrate.

37. 34. The method of claim 33, wherein the exit opening has an exit opening shape, the method further comprising selecting the exit opening shape.

38. The rotation mechanism and the material supply source are housed in a reaction chamber, and the substrate has a radius R ＳＵＢ 34. The method of claim 33, wherein the relationship of the lateral distance and the orthogonal distance to is used to scale the size of the reaction chamber.

39. 34. The method of claim 33, wherein the material source is a cosine N source, where N > 2.

40. 34. The method of claim 33, wherein the substrate has a diameter of 6 inches (150 mm) or greater.

41. further comprising a source of additional material; 34. The method of claim 33, wherein the determining step considers when the material source and the additional material source are used together.

42. the material supply source is a nitrogen plasma source that emits active nitrogen; 34. The method of claim 33, wherein the method further comprises providing an oxygen plasma material source.

43. 34. The method of claim 33, wherein the determined orthogonal distance and the determined lateral distance from the substrate deposition surface to the material source are less than or equal to a mean free path of the material released from the material source.

44. a rotation mechanism for rotating the substrate deposition surface of the substrate around a central axis of the substrate deposition surface; a heater configured to heat the substrate; a material supply source for supplying material to the substrate, the material supply source having i) an outlet opening having an outlet opening surface, and ii) a predetermined spatial distribution of material emission from the outlet opening surface, the predetermined spatial distribution of material emission having an axis of symmetry that intersects the substrate at a point offset from the central axis, the outlet opening being disposed at an orthogonal distance, a lateral distance, and an oblique angle relative to the central axis of the substrate; a position adjustment mechanism capable of dynamically adjusting the orthogonal distance, the lateral distance, or the tilt angle; 1. A material deposition system comprising:

45. 45. The system of claim 44, wherein the exit openings are positioned to minimize the orthogonal distance and the lateral distance to achieve a desired layer deposition uniformity at a desired layer growth rate.

46. a reaction chamber containing the rotation mechanism and the material supply source; The size of the reaction chamber is the radius R of the substrate. ＳＵＢ 45. The method of claim 44, wherein the lateral distance and the orthogonal distance are scaled based on a relationship of the lateral distance and the orthogonal distance to

47. 45. The system of claim 44, wherein the position adjustment mechanism is coupled to the material supply source.

48. 45. The system of claim 44, wherein the position adjustment mechanism is coupled to the rotation mechanism.

49. 45. The system of claim 44, wherein the material source is a cosine N source, where N > 2.

50. 45. The system of claim 44, wherein the substrate has a diameter of 6 inches (150 mm) or greater.

51. the material supply source is a nitrogen plasma source that emits active nitrogen; 45. The system of claim 44, wherein the system further comprises an oxygen plasma source.

52. 45. The system of claim 44, further comprising an additional material source comprising a source of one or more of Mg, P, Al, or Zn.

53. 45. The system of claim 44, wherein the substrate and the material source are contained in a vacuum environment.

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