Method and system for forming device structures using selective deposition of gallium nitride

Abstract

The present invention discloses a method for forming a device structure, a structure formed by the method, and a system for performing the method. The method comprises the following steps: providing a substrate comprising a surface in a reaction chamber, the surface comprising a first portion and a second portion, the first portion comprising one or more of aluminum nitride and gallium nitride, the second portion comprising another material; and selectively depositing gallium nitride on the first portion relative to the second portion using a thermal cycle deposition method. Various embodiments of the present disclosure allow the formation of a device structure including a (e.g., patterned) gallium nitride layer using fewer steps and / or allow the formation of a device structure having relatively small gallium nitride features.

Description

Technical Field

[0001] The present disclosure generally relates to thin film deposition methods, structures formed using the methods, and systems for performing the methods. More specifically, the present disclosure relates to methods for selectively depositing gallium nitride to form device structures and related structures and systems. Background Art

[0002] Gallium nitride (GaN) is a direct bandgap material that exhibits relatively high electron mobility and a relatively wide bandgap compared to silicon. Therefore, the use of GaN in various devices has gained increasing attention, including optoelectronic devices such as photovoltaic devices; light-emitting devices such as lasers and light-emitting diodes; high-power, high-frequency transistors such as high electron mobility transistors (HEMTs), metal oxide semiconductor field effect transistors (MOSFETs), and metal semiconductor field effect transistors (MESFETs); resonators, etc.

[0003] Although gallium nitride has many desirable properties, gallium nitride substrates are relatively expensive compared to silicon substrates. Therefore, methods of forming devices including gallium nitride generally include the steps of depositing a gallium nitride layer on a silicon substrate and then patterning the gallium nitride layer using photolithography and etching techniques. Such processes allow gallium nitride devices to be monolithically integrated with silicon-based devices. While such processes work well for a variety of applications, the processes can be relatively time consuming and expensive and may not provide the precision desired for other applications. Therefore, improved methods for forming device structures including gallium nitride are desired. Summary of the invention

[0004] Various embodiments of the present disclosure are directed to methods of forming device structures that include selectively depositing gallium nitride on one material relative to another material. Although the manner in which various embodiments of the present disclosure address shortcomings of previous methods is discussed in more detail below, in general, various embodiments of the present disclosure allow for the formation of device structures that include (e.g., patterned) gallium nitride layers using fewer steps and / or allow for the formation of device structures that have relatively small gallium nitride features.

[0005] According to exemplary embodiments of the present disclosure, a method of forming a device structure includes providing a substrate including a surface in a reaction chamber, the surface including a first portion and a second portion, the first portion including one or more of aluminum nitride and gallium nitride (or other boron group (III) nitrides, such as BN, InN, or one or more transition metals), the second portion including another material; and selectively depositing gallium nitride on the first portion relative to the second portion using a thermal cycle deposition process (e.g., an atomic layer deposition process). According to various aspects of these embodiments, the second portion may include silicon. The silicon may be hydrogen terminated. According to further aspects, the second portion may include one or more of an oxide, a nitride, and an oxynitride. The second portion (e.g., an oxide, a nitride, or an oxynitride) may be hydroxyl terminated. The exemplary method may also include, prior to the step of selectively depositing gallium nitride, a step of exposing the first portion to a reducing agent and / or a nitriding agent, such as one or more of hydrogen, ammonia, and hydrazine and / or a radical species formed from a source gas including one or more of hydrogen, ammonia, and hydrazine. Exemplary methods may additionally or alternatively include forming features comprising one or more of aluminum nitride and gallium nitride (or other Group III nitrides or one or more transition metals).The surface of the feature may be etched, for example, to remove native oxide or other debris from the surface of the feature.

[0006] According to another embodiment of the present disclosure, a method of forming a device structure includes the following steps: providing a substrate comprising a surface, the surface comprising a first portion and a second portion, the first portion comprising aluminum nitride and one or more of gallium nitride or other Group III nitrides or one or more transition metals, and the second portion comprising silicon nitride; and selectively depositing gallium nitride on the first portion relative to the second portion using a thermal cycle deposition process (e.g., an atomic layer deposition process).

[0007] According to further exemplary embodiments of the present disclosure, a device structure is formed using a method as described herein.

[0008] And according to yet another embodiment of the present disclosure, a system for executing the method as described herein is provided.

[0009] For the purpose of summarizing the present invention and the advantages achieved over the prior art, certain objects and advantages of the present invention are described above. Of course, it should be understood that not all such objects or advantages may be achieved according to any particular embodiment of the present invention. Thus, for example, one skilled in the art will recognize that the present invention may be implemented or carried out in a manner that achieves or optimizes one advantage or a group of advantages as taught or suggested herein but does not necessarily achieve other objects or advantages as may be taught or suggested herein.

[0010] All of these embodiments are intended to fall within the scope of the invention disclosed herein. These and other embodiments will become apparent to those skilled in the art from the following detailed description of certain embodiments with reference to the accompanying drawings, the invention not being limited to any particular embodiment disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more complete understanding of illustrative embodiments of the present disclosure may be derived by referring to the detailed description and claims when considered in conjunction with the following illustrative drawings.

[0012] Figure 1 A method according to an exemplary embodiment of the present disclosure is described.

[0013] Figure 2 More details Figure 1 The steps of the method described in .

[0014] Figure 3 A device structure according to an exemplary embodiment of the present disclosure is described.

[0015] Figure 4 A system for executing a method according to an embodiment of the present disclosure is described.

[0016] It should be understood that the elements in the figures are illustrated only for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the illustrated embodiments of the present disclosure. DETAILED DESCRIPTION

[0017] The description of the exemplary embodiments provided below is merely illustrative and is intended for illustration purposes only; the following description is not intended to limit the scope of the present disclosure or the claims. Furthermore, the recitation of multiple embodiments having stated features is not intended to exclude other embodiments having additional features or other embodiments incorporating different combinations of the stated features. Furthermore, the illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized illustrations used to describe embodiments of the present disclosure.

[0018] The present disclosure generally relates to methods of forming structures and structures formed using the methods. The methods and structures described herein can be used to form a variety of devices, such as devices that include single crystal and / or polycrystalline gallium nitride layers.

[0019] As used herein, a layer comprising gallium nitride may comprise, consist essentially of, or consist of a gallium nitride material (with or without a dopant). Films composed of gallium nitride (with or without a dopant) may include acceptable amounts of impurities, such as carbon, which may originate from one or more precursors used to deposit the gallium nitride layer.

[0020] Similarly, a surface or portion comprising aluminum nitride may comprise, consist essentially of, or consist of an aluminum nitride material. Films composed of aluminum nitride may include acceptable amounts of impurities, such as carbon, which may originate from one or more precursors used to deposit the aluminum nitride layer.

[0021] As used herein, the term substrate may refer to any underlying material or materials onto which a material may be deposited. An exemplary substrate may be used to form a device, circuit, or structure. By way of example, a substrate may be or include a semiconductor material such as, but not limited to, silicon (Si), germanium (Ge), germanium tin (GeSn), silicon germanium (SiGe), silicon germanium tin (SiGeSn), silicon carbide (SiC), or a III-V semiconductor material such as gallium arsenide (GaAs), gallium phosphide (GaP), or gallium nitride (GaN). In some embodiments of the present disclosure, a substrate may include an engineered substrate in which a surface semiconductor layer is disposed above a body support with an intermediate buried oxide (BOX) disposed therebetween. The substrate may be patterned. A patterned substrate may include a substrate that may include a semiconductor device structure formed in or on a surface of the substrate; for example, a patterned substrate may include a partially fabricated semiconductor device structure, such as a transistor and / or a memory element. In some embodiments, a substrate may contain a single crystal surface and / or one or more subsurfaces, which may include a non-single crystal surface, such as a polycrystalline surface and / or an amorphous surface. A single crystal surface may include, for example, one or more of silicon (Si), silicon germanium (SiGe), germanium tin (GeSn), or germanium (Ge). A polycrystalline or amorphous surface may include a dielectric material, such as an oxide, oxynitride, or nitride, such as silicon oxide and silicon nitride.

[0022] As used herein, the term "cyclic deposition" may refer to sequentially introducing reactants into a reaction chamber to deposit a film on a substrate and includes deposition techniques such as atomic layer deposition and cyclic chemical vapor deposition.

[0023] As used herein, the term "cyclic chemical vapor deposition" may refer to any process that sequentially exposes a substrate to two or more volatile reactants that react and / or decompose on the substrate to produce a desired material.

[0024] As used herein, the term atomic layer deposition (ALD) may refer to a vapor deposition process in which a deposition cycle, such as a plurality of consecutive deposition cycles, is performed in a reaction chamber. Typically, during each cycle, a first precursor is chemically adsorbed to a deposition surface (e.g., a substrate surface or previously deposited underlying material, such as material from a previous ALD cycle), thereby forming a monolayer or sub-monolayer that is not susceptible to reaction with additional precursors (i.e., a self-limiting reaction). Thereafter, a reactant (e.g., another precursor or a reactive gas) may be subsequently introduced into the process chamber for converting the chemically adsorbed precursor to a desired material on the deposition surface. Typically, such a reactant is capable of further reacting with the precursor. Additionally, during each cycle, a purge step may also be utilized to remove excess precursor from the process chamber after converting the chemically adsorbed precursor and / or to remove excess reactant and / or reaction byproducts from the process chamber. As used herein, the term atomic layer deposition is also intended to include processes designated by related terms such as chemical vapor atomic layer deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE or organometallic MBE and chemical beam epitaxy when performed using alternating pulses of a precursor composition, a reactive gas, and a purge gas (e.g., an inert carrier gas).

[0025] As used herein, the terms layer, film, and thin film may refer to any continuous or non-continuous structure and material formed by the methods disclosed herein. For example, layers, films, and thin films may include 2D materials, nanolaminates, nanorods, nanotubes, or nanoparticles, or even partial or complete molecular layers, or partial or complete atomic layers, or clusters of atoms and / or molecules. Layers, films, and thin films may contain materials or layers with pinholes, but still be at least partially continuous.

[0026] As used herein, the term "incubation period" may refer to the number of cyclic deposition cycles in the initial stage of cyclic deposition during which no discernible deposition is observed.

[0027] A selective deposition process as described herein may involve a greater amount of material remaining on a first surface or portion relative to a second surface or portion. For example, a selective process may result in a greater amount of gallium nitride material remaining in a first region relative to any gallium nitride remaining in a second region. In some embodiments of the present disclosure, the selectivity of a process may be expressed as a ratio of the material remaining on the first surface to the combined amount of material formed on the first surface and the second surface. For example, if 10nm of gallium nitride material remains in the first region and 1nm of gallium nitride material remains in the second region, then the selective deposition process would be considered to be 91% selective. In some embodiments, the selectivity of the methods disclosed herein may be greater than 80%, greater than 90%, greater than 95%, greater than 99.5%, greater than 98%, greater than 99%, or even about 100%.

[0028] Turning now to the accompanying drawings, Figure 1 A method of forming a device structure 100 according to an exemplary embodiment of the present disclosure is described. The method of forming the device structure 100 includes the following steps: providing a substrate in a reaction chamber (step 102), and selectively forming a gallium nitride layer on a first portion of a substrate surface relative to a second portion of the substrate surface (step 104).

[0029] The substrate provided during step 102 may include a first portion and a second portion, the first portion including one or more of aluminum nitride and gallium nitride (or other boron group (Group III) nitrides, such as BN, InN, or one or more transition metals), and the second portion comprising other materials (i.e., another material), such as (e.g., hydrogen terminated) silicon or a metal or metalloid oxide, nitride, or oxynitride. The substrate may include patterned features of aluminum nitride, gallium nitride, and / or other materials. The patterned features may be formed, for example, by depositing layers of the respective materials and etching a portion of one or more layers. By way of example, the substrate provided during step 102 may include a first portion and a second portion, the first portion including patterned features of one or more of aluminum nitride and gallium nitride (e.g., formed by depositing layers of material, patterning the layers with, for example, a photoresist, and etching the layers to form patterned features), and the second portion including (e.g., patterned) other materials. The first and segment portions may be coplanar, the first portion may be raised relative to the second portion, or the second portion may be raised relative to the first portion. The first portion and the second portion may be formed using one or more reaction chambers.

[0030] During step 102, the reaction chamber may be brought to a desired deposition pressure and temperature for step 104. By way of example, once the substrate is loaded onto the reaction chamber, the temperature of the reaction chamber and / or the temperature of the susceptor within the reaction chamber may be about 350° C. to about 450° C., or about 375° C. to about 425° C., or about 380° C. to about 420° C. The pressure within the reaction chamber may be as high as about 25 mbar, or greater than about 10 -2 The pressure may be in the range of about 100 mbar to about 100 mbar, about 1 to about 100 mbar, about 1 mbar to about 25 mbar, or about 1 to about 10 mbar.

[0031] Next, in step 104, gallium nitride is selectively deposited on the first portion relative to the second portion using a cyclic deposition process, such as a cyclic CVD and / or ALD method. In order to maintain the selectivity of the deposition, the cyclic deposition process is ideally not plasma enhanced. In other words, the cyclic deposition process includes a thermal cyclic deposition process. In some cases, the deposition may not be a true ALD deposition, but rather includes at least some gas phase reactions between precursors - such as a cyclic deposition process. The gallium nitride can be single crystalline or polycrystalline. Although previous devices typically work with single crystalline GaN layers, it is expected that polycrystalline GaN layers may also work.

[0032] like Figure 2 As illustrated, step 104 may include the sub-step of providing a gallium precursor to the reaction chamber (step 202), the sub-step of purging / removing any unreacted gallium precursor and reaction byproducts from the reaction chamber (step 204), the sub-step of providing a nitrogen precursor to the reaction chamber (step 206), and the sub-step of purging / removing any unreacted nitrogen precursor and reaction byproducts from the reaction chamber (step 208). Sub-steps 202-208 may be simply referred to as steps. Step 104 may also include one or more optional sub-steps, such as an optional etching step 212 and / or an optional conditioning step 214.

[0033] Steps 202-208 (step 210) may be repeated until a film of desired thickness is formed. Additionally or alternatively, steps 202 and 204 may be repeated one or more times before continuing with step 206, and / or steps 206 and 208 may be repeated before continuing with step 202. In addition, although described starting with providing a gallium precursor step 202, step 104 may alternatively start with providing a nitrogen precursor step 206 and / or one or more of steps 212, 214.

[0034] Suitable precursors / reactants for depositing gallium nitride include gallium trichloride (GaCl3), gallium tribromide (GaBr3), gallium triiodide (GaI3), trimethylgallium (TMG) and triethylgallium (TEG) as gallium precursors and nitrogen (N2), ammonia (NH3) and hydrazine (N2H4) as nitrogen precursors, and / or remotely formed radicals from nitrogen (N2), ammonia (NH3) and hydrazine (N2H4) in such a way that the substrate is not exposed to any plasma or other form of energy for forming the radicals.

[0035] The flow rate of the precursors may vary depending on, for example, the reaction chamber configuration, substrate size, and / or the number of substrates being processed. By way of example, for an internal volume of about 32 cm 3For a reactor of 200, the flow rate of the gallium precursor during step 202 may be about 0.1 to about 100, or about 5 sccm, and the flow rate of the nitrogen precursor during step 206 may be about 1 to about 100, or about 4 sccm. For the same reactor volume, the flow rate of the purge gas, such as argon, during steps 204, 208 may be in the range of about 25 sccm to about 150 sccm. The partial pressure of the nitrogen precursor (e.g., NH3) may be, for example, about 10% to about 15% of the total reactor pressure.

[0036] In some embodiments of the present disclosure, step 202 includes exposing the substrate to a gallium precursor for a period of time between about 0.01 seconds and about 60 seconds, between about 0.05 seconds and about 10 seconds, or between about 0.1 seconds and about 5 seconds. In some embodiments of the present disclosure, step 206 includes exposing the substrate to a nitrogen precursor for a period of time between about 0.01 seconds and about 60 seconds, between about 10 seconds and about 50 seconds, or between about 20 seconds and about 40 seconds. The duration of step 204 can be in the range of about 1 to about 120, about 10 to about 90 seconds, or about 30 seconds. The duration of step 208 can be in the range of about 1 to about 120, about 10 to about 90 seconds, or about 60 seconds. The vacuum generated by the pumping system can help remove any excess precursor and any reaction byproducts.

[0037] Typically, in cyclic deposition—eg, ALD—on aluminum nitride or gallium nitride, particularly on aluminum nitride or gallium nitride features formed from etched layers of the respective materials, gallium nitride may not be selective with respect to the other materials.

[0038] However, silicon nitride has a relatively long incubation period.Thus, according to some aspects of these embodiments of the present disclosure, the second portion comprises silicon nitride.

[0039] Nitrogen terminated materials, such as NH x The incubation period of the (x=1-2) terminated aluminum nitride or gallium nitride may be relatively low compared to other materials (e.g., silicon, metal or silicon oxides, nitrides or oxynitrides). Unfortunately, the NH x The termination may be lost due to, for example, oxidation of the material, which may occur due to etching of the material and / or exposure to an oxidizing environment (e.g., air). According to exemplary aspects of the illustrated embodiments, the aluminum nitride and / or gallium nitride material (e.g., a feature comprising the material) is exposed to an environment to selectively provide NH on the aluminum nitride and / or gallium nitride, preferably on the aluminum nitride or gallium nitride relative to the second portion. x End-capping.

[0040] By way of example, NH, NH2 and / or hydrogen radical fluxes may be used to selectively modulate or provide NH on a first portion comprising one or more of aluminum nitride or gallium nitride or other materials as mentioned herein relative to a second portion. x Capping (step 214). The radical flux can be formed from the precursor gas using, for example, a remote plasma, a hot filament, or any other suitable method. The optional conditioning step 214 can be performed in the same reaction chamber used to perform step 104 and without a vacuum break between the conditioning step and the deposition step. In addition, the conditioning step 214 can be performed at the same (or different) temperature and / or the same (or different) pressure as the deposition step.

[0041] To further facilitate selective deposition, step 104 may include an optional etching step 212 to etch the surface of one or more of the aluminum nitride and gallium nitride prior to exposing the surface to the radical flux and / or other conditioning. Optional etching step 212 may be performed using, for example, sputtering of atomic hydrogen or argon ions.

[0042] Now turn to see Figure 3 , which illustrates a structure 300 formed according to an exemplary method described herein. The structure 300 includes a substrate 302, a first layer 304, a second layer 306, and a gallium nitride layer 308, the second layer 306 including one or more of aluminum nitride and gallium nitride (or other boron group (Group III) nitrides, such as BN, InN, or one or more transition metals). As illustrated, before forming the gallium nitride layer 308, the structure 300 includes a surface including a first portion 310 including one or more of aluminum nitride and gallium nitride (or other materials as described herein) and a second portion 312 including other materials, such as silicon, oxides, nitrides, or oxynitrides. By way of specific examples, the second portion 312 may include hafnium oxide, zirconium oxide, aluminum oxide, or other metal or metalloid oxides, nitrides, or oxynitrides. The gallium nitride layer 308 is selectively deposited onto the first surface 310 relative to the second surface 312 using one or more methods described herein. The gallium nitride layer 308 may be single crystalline or polycrystalline.

[0043] As described above, the first portion 310 can be formed by depositing a layer of, for example, aluminum nitride or gallium nitride, patterning the layer, and etching the layer to form the first portion 310. The aluminum nitride or gallium nitride layer for the first portion 310 can be formed using a cyclic deposition process, ALD, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), or physical deposition (PVD) technique. Suitable precursors for cyclic deposition processes, ALD, and CVD for depositing aluminum nitride include trimethylaluminum (TMA), triethylaluminum (TEA), and aluminum chloride (AlCl3), and any of the nitrogen precursors described herein. Suitable precursors for cyclic deposition, ALD, and CVD for depositing gallium nitride include TMG, TEG, GaCl3, and any of the nitrogen precursors described herein.

[0044] Figure 4 A system 400 configured for selectively forming gallium nitride on a surface of a substrate according to additional examples of the present disclosure is illustrated. The system 400 includes a reaction chamber 402, a first reactant / precursor source 404, a second reactant / precursor source 406, one or more purge gas sources 408, a vacuum source 410, and system operations and controls 412. Suitable systems for performing the methods described herein may be named Purchased from ASM International.

[0045] Reaction chamber 402 may include mechanisms for maintaining a substrate (not shown) at predetermined pressure, temperature, and ambient conditions and for selectively exposing the substrate to various gases. Exemplary pressures and temperatures are provided above.

[0046] Precursor source 404 may be coupled to reaction chamber 402 via conduit or other suitable component 404A, and may be further coupled to a manifold, a valve control system, a mass flow control system, or a mechanism for controlling the gaseous precursors from precursor source 404. Similarly, precursor source 406 may be coupled to reaction chamber 402 via conduit or other suitable component 406A, and may be further coupled to a manifold, a valve control system, a mass flow control system, or a mechanism for controlling the gaseous precursors from precursor source 406.

[0047] The precursor (not shown) supplied by precursor source 404 and / or precursor source 406 can be liquid or solid at room temperature and standard atmospheric pressure. Such precursors can be vaporized in a reactant source vacuum container, which can be maintained at or above the vaporization temperature in the precursor source chamber. In such embodiments, the vaporized precursor can be transported with a carrier gas (e.g., an inactive or noble gas) and then fed into reaction chamber 402 via conduit 404A or conduit 404B. In other embodiments, under standard conditions, the precursor can be a vapor. In such embodiments, the precursor does not need to be vaporized, and a carrier gas may not be required. For example, in one embodiment, the precursor can be stored in a gas cylinder.

[0048] Purge gas source 408 may also be coupled to reaction chamber 402 via conduit 408A and selectively supply various inert or noble gases to reaction chamber 402 to help remove precursor gases or exhaust gases from the reaction chamber. The various inert or noble gases that may be supplied may originate from solid, liquid, or stored gaseous forms.

[0049] The vacuum source may include a desiccant and / or a turbomolecular pump.

[0050] The system operation and control mechanism 412 may provide electronic circuits and mechanical components to selectively operate valves, manifolds, pumps, and other devices included in the reaction system 400. Such circuits and components operate to introduce precursors, purge gases from the respective precursor sources 404, 406, and the purge gas source 408. The system operation and control mechanism 412 also controls the timing of gas pulse sequences, the temperature of the substrate and the reaction chamber, and the pressure of the reaction chamber, as well as various other operations necessary to provide proper operation of the reaction system 400. The operation and control mechanism 412 may include control software and electrically or pneumatically controlled valves to control the flow of precursors, reactants, and purge gases into and out of the reaction chamber 402. The control system may include modules that perform certain tasks, such as software or hardware components, such as FPGAs or ASICs. The modules may be advantageously configured to reside on an addressable storage medium of the control system and may be advantageously configured to perform one or more processes.

[0051] Although exemplary embodiments of the present disclosure are described herein, it should be understood that the present disclosure is not limited thereto. Various modifications, changes and enhancements may be made to the devices, components and systems described herein without departing from the spirit and scope of the present disclosure.

[0052] Unless otherwise stated, the subject matter of the present disclosure includes all novel and nonobvious combinations and sub-combinations of the various systems, components and configurations, and other features, functions, acts, and / or properties disclosed herein, and any and all equivalents thereof.

Claims

1. A method for forming a device structure, the method comprising the following steps: providing a substrate comprising a surface within a reaction chamber, the surface comprising a first portion and a second portion, the first portion comprising one or more of aluminum nitride and gallium nitride, the second portion comprising another material; exposing the first portion to a flux of NH and / or NH2 and / or hydrogen radicals to provide NHx capping on the first portion; and Gallium nitride is selectively deposited on the first portion relative to the second portion using a thermal cycle deposition method. The method of claim 1 , wherein the second portion comprises silicon. The method of claim 2 , wherein the second portion comprises hydrogen terminated silicon. 4 . The method of claim 1 , wherein the second portion comprises one or more of an oxide, a nitride, and an oxynitride. The method of claim 1 , wherein the second portion comprises a hydroxyl-terminated oxide. 6 . The method of claim 1 , wherein the steps of selectively depositing gallium nitride and forming the first portion comprising one or more of aluminum nitride and gallium nitride are performed ex situ.

7. The method of claim 1, further comprising the step of exposing the first portion to a reducing agent prior to the step of selectively depositing gallium nitride.

8. The method of claim 7, wherein the step of exposing the first portion to a reducing agent and the step of selectively depositing gallium nitride are performed in the same reaction chamber without a vacuum break. 9 . The method of claim 7 , wherein the reducing agent comprises one or more of hydrogen, ammonia, and hydrazine or free radicals formed from a source gas comprising one or more of hydrogen, ammonia, and hydrazine.

10. The method of claim 1, wherein the one or more of aluminum nitride and gallium nitride is formed by depositing a layer comprising the one or more of aluminum nitride and gallium nitride using a method selected from the list consisting of chemical vapor deposition, cyclic deposition, atomic layer deposition, molecular beam epitaxy, and physical vapor deposition.

11. The method of claim 10, wherein the method of forming a device structure further comprises patterning the layer comprising the one or more of the aluminum nitride and gallium nitride to form features comprising the one or more of the aluminum nitride and gallium nitride.

12. The method of claim 11, further comprising the step of etching a surface of the feature.

13. The method of claim 11, further comprising the step of removing oxide from a surface of the feature.

14. The method of claim 1, wherein the first portion comprises aluminum nitride, wherein the aluminum nitride is deposited using chemical vapor deposition or atomic layer deposition, and wherein an aluminum precursor used to form the aluminum nitride is selected from the group consisting of TMA, TEA, and AlCl3.

15. The method of claim 1, wherein the first portion comprises gallium nitride, wherein the gallium nitride is deposited using chemical vapor deposition or atomic layer deposition, and wherein a gallium precursor used to form the gallium nitride is selected from the group consisting of: TMG, TEG, GaCl 3、 GaBr3 and GaI3.

16. The method according to any one of claims 14 and 15, further comprising the step of providing a nitrogen precursor, wherein the nitrogen precursor is selected from the group consisting of: ammonia (NH3) and hydrazine (N2H4), and / or a radical remotely formed from a precursor selected from the group consisting of: nitrogen (N2), ammonia (NH3) and hydrazine (N2H4).

17. The method of claim 1, wherein during said step of using a thermal cycle deposition method, a selectivity is greater than 80%.

18. The method of claim 1, wherein during the step of selectively depositing gallium nitride, the pressure within the reaction chamber is between 1 and 100 mbar.

19. The method of claim 1, wherein during the step of selectively depositing gallium nitride, the pressure within the reaction chamber is between 5 and 15 mbar.

20. The method of claim 1, wherein during the step of selectively depositing gallium nitride, the temperature within the reaction chamber is between 375°C and 425°C.

21. The method of claim 1, wherein during the step of selectively depositing gallium nitride, a selectivity is greater than 80%.

22. A structure formed by the method of forming a device structure according to any one of claims 1 to 21.

23. A system for performing the method of forming a device structure according to any one of claims 1 to 21.

24. A method of forming a device structure, the method comprising the steps of: Providing a substrate comprising a surface, the surface comprising a first portion and a second portion, the first portion comprising one or more of aluminum nitride and gallium nitride, the second portion comprising silicon nitride; exposing the first portion to a flux of NH and / or NH2 and / or hydrogen radicals to provide NHx capping on the first portion; and Gallium nitride is selectively deposited on the first portion relative to the second portion using a thermal cycle deposition method.

25. The method of claim 24, wherein during the step of selectively depositing gallium nitride, the pressure within the reaction chamber is between 1 and 100 mbar.

26. The method of claim 24, wherein during the step of selectively depositing gallium nitride, the pressure within the reaction chamber is between 5 and 15 mbar.

27. The method of claim 24, wherein during the step of selectively depositing gallium nitride, the temperature within the reaction chamber is between 375°C and 425°C.

28. The method of claim 24, wherein during the step of selectively depositing gallium nitride, a selectivity is greater than 80%.

29. A structure formed by the method of forming a device structure according to any one of claims 24 to 28.

30. A system for performing the method of forming a device structure according to any one of claims 24 to 28.

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