EUV dose reducing layers, related structures, and methods and systems for their manufacture

Abstract

To provide EUV dose reducing layers, related structures, and methods and systems for their manufacture.SOLUTION: Methods and related systems and structures for reducing EUV dose requirements during lithography steps, are provided. Presently disclosed methods can comprise forming a dose reducing layer that comprises a doped semiconductor. The doped semiconductor can comprise at least one of an elemental semiconductor and a compound semiconductor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates generally to structures, methods, and systems used in the formation of semiconductor devices. More specifically, the present disclosure relates to the field of extreme ultraviolet lithography. [Background technology]

[0002] Semiconductor device patterning is often designed around the characteristics of expensive lithography equipment. Reducing the time required per wafer during a lithography step can greatly improve the throughput and cost of device manufacturing, and this time can be expressed in terms of lithography exposure dose.

[0003] Exposure dose is equal to the energy over a unit space, or in other words, the photon flux (the number of photons per unit space per unit time) multiplied by the photon energy and exposure time. In the emerging field of EUV lithography, which improves resolution through reduced wavelength, the energy per photon is greatly increased. To reduce the exposure dose, either the photon flux or the exposure time needs to be reduced, both of which reduce the total number of photons hitting the lithographic resist to a very small amount. Furthermore, high energy EUV photons are more difficult to absorb by most materials, exaggerating the problem of low photon counts. With such a small number of photons absorbed by the resist, it is difficult to obtain good quality lithographic structures due to photon shot noise effects, especially when small feature sizes are pursued. Therefore, the key to actually reducing the exposure dose is to increase the useful effect of each photon.

[0004] The usefulness of each photon can be improved through two methods: by increasing the absorption of each photon, and by increasing the number of electrons generated per photon. Absorption is often improved by simply inserting an EUV absorbing material into the lithographic structure. This absorption produces photoelectrons that can drive reactions in the resist, but one electron per photon conversion still produces high shot noise. This problem is solved if the high energy photoelectrons are converted into multiple secondary electrons (SEs) through multiple possible paths.

[0005] There are two main known solutions for integrating EUV absorbing and SE generating materials into the lithography stack.

[0006] One solution is to add materials directly to the resist, such as by adding sensitizers to chemically amplified resists (CARs) or by using highly absorbing metal oxide resists (MORs). However, these new resists have drawbacks. The resists become complex structures where SE generation is difficult to control, and too high absorption in the resist can prevent further photons from traveling to the bottom of the resist when needed. Excessively long electron paths in the resist are also undesirable, as this impairs resolution and causes roughness. If the absorption is balanced so that photons are absorbed at the bottom of the resist, SEs are still often lost to the substrate.

[0007] A second solution, complementary to the above solutions, is to deposit EUV absorbing and SE generating materials in the underlayers. These layers can be directly designed to generate many electrons and help to supply SEs to the bottom of the resist. However, many of the materials are heavy metals that have a self-limiting effect because electrons from deeper levels cannot easily travel to the resist. Furthermore, many of the randomly moving electrons are still lost to the substrate. Even if materials with longer electron paths are placed below these materials, the electrons are still blocked by the upper layers and lost to the substrate. Many highly absorbing materials are known and can be deposited, but a more precisely designed architecture is needed to control how the electrons are generated and whether they are terminated as required, all while being incorporated into a low-cost and very thin sacrificial patterning stack. Summary of the Invention [Means for solving the problem]

[0008] Structures that can be used or employed in lithographic patterning stacks during semiconductor wafer processing are disclosed, as are methods and systems for producing such structures.

[0009] Advantageously, embodiments according to the present disclosure may allow for the generation of as many secondary electrons as possible.

[0010] Thus, described herein is a structure comprising a substrate, an exposure dose reduction layer overlying the substrate, and an extreme ultraviolet (EUV) resist overlying the exposure dose reduction layer, the exposure dose reduction layer comprising a doped semiconductor, the doped semiconductor comprising a base component and a dopant.

[0011] In some embodiments, the doped semiconductor has a band gap of at least 2.0 eV.

[0012] In some embodiments, the EUV resist is selected from a metal-organic framework resist, a metal oxide resist, and a chemically amplified resist.

[0013] Further described herein is a method comprising providing a substrate to a reaction chamber, forming an exposure dose reducing layer on the substrate, optionally forming an adhesive layer on the substrate, and forming an EUV resist on the substrate, wherein the EUV resist is disposed to absorb EUV radiation and generate secondary electrons, and wherein the exposure dose reducing layer comprises a main component and a dopant.

[0014] In some embodiments, the method further includes exposing the EUV resist to EUV radiation through a mask.

[0015] In some embodiments, the base component comprises an elemental semiconductor.

[0016] In some embodiments, the elemental semiconductor comprises tellurium.

[0017] In some embodiments, the base component comprises a compound semiconductor.

[0018] In some embodiments, the compound semiconductor comprises indium(III) oxide.

[0019] In some embodiments, the dopant comprises a vacancy.

[0020] In some embodiments, the vacancies comprise oxygen vacancies.

[0021] In some embodiments, the dopant comprises iodine.

[0022] Further described herein is a method of forming a layer, the method including providing a substrate to a reaction chamber by a substrate handler and performing a cyclic deposition process, the cyclic deposition process including a plurality of cycles including a main component precursor pulse and a dopant reactant pulse, the main component precursor pulse including contacting the substrate with the main component precursor, the reactant pulse including contacting the substrate with the dopant reactant, the main component precursor including tellurium, and the dopant reactant including iodine.

[0023] In some embodiments, the primary component precursor comprises diisopropyl telluride.

[0024] In some embodiments, the dopant reactant comprises an iodoalkane.

[0025] In some embodiments, the iodoalkane comprises 1,2-diiodoethane.

[0026] In some embodiments, the cyclic deposition process is a thermal cyclic deposition process.

[0027] In some embodiments, at least one of the precursor and the reactant comprises an activated species, and the activated species is generated in a plasma.

[0028] This Summary is provided to introduce selected concepts in a simplified form. These concepts are described in more detail in the Detailed Description of Example Embodiments of the Disclosure below. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 shows an embodiment of a structure 100 as described herein. [Diagram 2]FIG. 2 shows an embodiment of a system 200 as described herein. [Diagram 3] FIG. 3 illustrates an embodiment of the method as described herein. [Figure 4] FIG. 4 illustrates an embodiment of a system as described herein. [Diagram 5] FIG. 5 illustrates an embodiment of a system as described herein. [Figure 6] FIG. 6 illustrates an embodiment of a system as described herein. [Figure 7] FIG. 7 illustrates an embodiment of a system as described herein. [Figure 8] FIG. 8 illustrates an embodiment of the method as described herein. [Figure 9] FIG. 9 shows an embodiment of a system as described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been 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.

[0031] Although certain specific embodiments and examples are disclosed below, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments and / or uses of the invention, and obvious modifications and equivalents thereof, and therefore it is not intended that the scope of the disclosed invention should be limited by the specific disclosed embodiments described below.

[0032] As used herein, the term "substrate" may refer to any underlying material or materials, including any underlying material or materials, that may be modified or upon which a device, circuit, or film may be formed. A "substrate" may be continuous or non-continuous, rigid or flexible, solid or porous, and combinations thereof. The substrate may be in any form, such as a powder, a plate, or a workpiece. Substrates in the form of plates may include wafers of various shapes and sizes. Substrates may be made of semiconductor materials, including, for example, silicon, silicon germanium, silicon oxide, gallium arsenide, gallium nitride, and silicon carbide.

[0033] For example, the substrate in the form of a powder may have applications for pharmaceutical manufacturing. The porous substrate may include a polymer. Examples of workpieces may include medical devices (e.g., stents and syringes), jewelry, tooling devices, components for battery manufacturing (e.g., anodes, cathodes, or separators), or components of photovoltaic cells, etc.

[0034] The continuous substrate may extend beyond the boundaries of the process chamber in which the deposition process occurs. In some processes, the continuous substrate may move through the process chamber, such that the process continues until the end of the substrate is reached. The continuous substrate may be fed from a continuous substrate feed system to enable the production and output of the continuous substrate in any suitable form.

[0035] Non-limiting examples of continuous substrates may include sheets, nonwoven films, rolls, foils, webs, flexible materials, bundles of continuous filaments or fibers (e.g., ceramic or polymeric fibers). Continuous substrates may also include carriers or sheets onto which the non-continuous substrates are placed.

[0036] In this disclosure, "gas" can include materials that are gaseous at ambient temperature and pressure (NTP), vaporized solids, and / or vaporized liquids, and can be comprised of a single gas or a mixture of gases in some circumstances. Gases other than process gases, i.e., gases introduced without passing through a gas distribution assembly, other gas distribution device, or the like, can be used, for example, to seal the reaction space and can include a seal gas. Precursors and reactants can be gases. Exemplary seal gases include noble gases, nitrogen, and the like. In some cases, the term "precursor" can refer to a compound that participates in a chemical reaction to produce another compound, and specifically a compound that constitutes the membrane matrix or backbone of the membrane, and the term "reactant" can be used interchangeably with the term precursor.

[0037] As used herein, the terms "film" and / or "layer" can refer to any continuous or non-continuous structure and material, such as materials deposited by the methods disclosed herein. For example, the film and / or layer can include two-dimensional materials, three-dimensional materials, nanoparticles, partial or complete molecular layers, or partial or complete atomic layers, or clusters of atoms and / or molecules. The film or layer can include or at least partially consist of a plurality of dispersed atoms on the surface of a substrate, and / or can be embedded or become embedded within the substrate and / or within a device fabricated on the substrate. The film or layer can comprise a material or layer with pinholes and / or isolated islands. The film or layer can be at least partially continuous. The film or layer can be patterned, e.g., subdivided, and can be included within multiple semiconductor devices. The film or layer can be selectively grown on some parts of the substrate and not on other parts.

[0038] As used herein, the term "deposition process" can refer to the introduction of precursors (and / or reactants) into a reaction chamber to deposit a layer over a substrate. A "cyclic deposition process" is an example of a "deposition process."

[0039] The term "cyclic deposition process" or "cyclical deposition process" can refer to the sequential introduction of precursors (and / or reactants) into a reaction chamber to deposit layers on a substrate, and includes processing techniques such as atomic layer deposition (ALD), cyclic chemical vapor deposition (cyclic CVD), and hybrid cyclic deposition processes that include ALD and cyclical CVD components.

[0040] The term "atomic layer deposition" can refer to a deposition process in which deposition cycles, typically multiple successive deposition cycles, are performed in a process chamber. As used herein, the term atomic layer deposition, when performed with alternating pulses of precursor / reactive gases and purge (e.g., inert carrier) gas, may include processes designated by related terms such as chemical vapor atomic layer deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE, metalorganic MBE, and chemical beam epitaxy. The pulse may include exposing the substrate to a precursor or reactant. This may be done, for example, by introducing the precursor or reactant into a reaction chamber in which the substrate is present. Additionally or alternatively, exposing the substrate to the precursor may include moving the substrate to a location in the substrate processing system where the reactant or precursor is present.

[0041] Generally, for an ALD process, during each cycle, a precursor is introduced into the reaction chamber and chemisorbed onto the deposition surface (e.g., a substrate surface, which may include previously deposited material or other materials from a previous ALD cycle) and forms a monolayer or quasi-monolayer of material that does not readily react with additional precursors (i.e., self-limiting reaction). A reactant (e.g., another precursor or reactant gas) may then be introduced into the process chamber for use in converting the chemisorbed precursor to a desired material on the deposition surface. The reactant may be capable of further reaction with the precursor. Purging steps may be utilized during one or more cycles (e.g., during each step of each cycle) to remove any excess precursor from the process chamber and / or to remove any excess reactants and / or reaction by-products from the reaction chamber.

[0042] As used herein, the term "purging" may refer to a procedure in which an inert gas or a substantially inert gas is provided to the reaction chamber between two pulses of gases that react with each other. For example, a purge, e.g., a purge using a noble gas, may be provided between the precursor pulse and the reactant pulse, thus avoiding or at least minimizing gas phase interactions between the precursor and the reactant. Of course, purging can be accomplished temporally, spatially, or both. For example, in the case of temporal purging, the purging step can be used in a time sequence, e.g., providing a first precursor to the reaction chamber, providing a purge gas to the reaction chamber, and providing a second precursor to the reaction chamber, without moving the substrate on which the layer is deposited. For example, in the case of spatial purging, the purging step can take the following form: moving the substrate from a first location where the first precursor is continuously supplied, through a purge gas curtain, to a second location where the second precursor is continuously supplied.

[0043] As used herein, "precursor" includes a gas or material that can be gaseous and can be represented by a chemical formula that includes elements that may be incorporated during a deposition process as described herein.

[0044] The term "oxygen reactant" can refer to a gas or material that can be gaseous and can be represented by a chemical formula that includes oxygen. In some cases, the chemical formula includes oxygen and hydrogen.

[0045] The illustrations presented herein are not meant to be actual representations of any particular materials, structures, or devices, but merely idealized representations used to describe embodiments of the present disclosure.

[0046] The particular implementations shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of aspects and implementations in any way. Indeed, for the sake of brevity, conventional manufacturing, association, preparation, and other functional aspects of the system may not be described in detail. Furthermore, the connecting lines shown in the various figures are intended to represent example functional relationships and / or physical couplings between the various elements. Many alternative or additional functional relationships or physical connections may be present in an actual system and / or may not be present in some embodiments.

[0047] It should be understood that the configurations and / or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be construed in a limiting sense, as numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various illustrated operations may be performed in the order illustrated, in other orders, or omitted in some cases.

[0048] The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various processes, systems, and configurations, and other features, functions, operations and / or properties disclosed herein, as well as all equivalents thereof.

[0049] In some embodiments, and with reference to Figure 1, a structure 100 is described herein. The structure 100 can include a substrate 110, an exposure dose reduction layer 120 overlying the substrate, and an extreme ultraviolet (EUV) resist 130 overlying the exposure dose reduction layer 120. The exposure dose reduction layer 120 can include a doped semiconductor. The doped semiconductor can include a base component and a dopant.

[0050] The EUV resist can be constructed and arranged to absorb EUV radiation and generate secondary electrons. The EUV resist layer can include any suitable resist, such as a molecular, metal oxide, or chemically amplified resist. Of course, the resist can be formed using any suitable deposition technique, including chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), and plasma-enhanced atomic layer deposition (PEALD).

[0051] Dopants in doped semiconductors can increase the electrical conductivity of the doped semiconductor relative to undoped variants. Some level of electrical conductivity can advantageously allow for the replenishment of electrons lost in secondary electron emission processes that can improve secondary electron generation within the dose reduction layer, which in turn can help lower the EUV exposure dose required for full resist exposure.

[0052] In some embodiments, incorporating a dopant into the exposure reduction layer can reduce the electron affinity of the exposure reduction layer relative to an undoped version, which can increase the electron escape probability, which can result in the generation of more secondary electrons.

[0053] In some embodiments, the dopants can have a relatively high capture cross section for EUV radiation, which can reduce the exposure dose requirements of the lithographic stack.

[0054] In some embodiments, the doped semiconductor has a bandgap of at least 2.0 eV. In some embodiments, the doped semiconductor has a bandgap of at least 2.5 eV, at least 3.0 eV, or at least 4.0 eV, where eV stands for "electron volts."

[0055] In some embodiments, the doped semiconductor has a band gap of at most 6.0 eV, at most 5.0 eV, or at most 4.0 eV.

[0056] In some embodiments, the doped semiconductor has a band gap of at least 2.0 eV and up to 4.0 eV.

[0057] Materials with relatively wide bandgaps, such as semiconductors with relatively wide bandgaps, can suppress, prevent, or limit the energy loss of low energy secondary electrons through electron-electron collisions, thereby resulting in large escape depths for the secondary electrons and large secondary electron yields. Nevertheless, excessively high bandgaps can make it difficult to make the doped material conductive by adding dopant elements, which can be a practical limit on the maximum bandgap that is practical.

[0058] In some embodiments, the doped semiconductor comprises a compound semiconductor, in other words, the main component of the doped semiconductor may comprise a compound semiconductor.

[0059] Suitable compound semiconductors include semiconductor oxides.

[0060] In some embodiments, the doped semiconductor includes indium oxide, such as indium(III) oxide, i.e., In2O3. In other words, the main component of the doped semiconductor can include In2O3. In some embodiments, when the main component of the doped semiconductor includes In2O3, the dopant can include iodine.

[0061] In some embodiments, the doped semiconductor comprises tin oxide, such as tin(IV) oxide, i.e., SnO2. In other words, the main component of the doped semiconductor can comprise SnO2. In some embodiments, when the main component of the doped semiconductor comprises tin oxide, the dopant can comprise iodine.

[0062] In some embodiments, the doped semiconductor includes antimony oxide. In other words, the main component of the doped semiconductor can include antimony oxide. In some embodiments, when the main component of the doped semiconductor includes antimony, the dopant can include iodine. In some embodiments, the doped semiconductor can include antimony oxide, such as iodine-doped antimony oxide. The antimony can be in the +III or +V oxidation state. In some embodiments, the antimony oxide can be an oxide, e.g., a non-stoichiometric oxide, e.g., in the form SbO, where x is a real number of at least 3 and at most 5. x In some embodiments, x is 3. In some embodiments, x is 4. In some embodiments, x is 5.

[0063] In some embodiments, the doped semiconductor comprises tellurium oxide. In other words, the main component of the doped semiconductor can comprise tellurium oxide. In some embodiments, when the main component of the doped semiconductor comprises tellurium oxide, the dopant can comprise iodine.

[0064] In some embodiments, for example, when the doped semiconductor comprises a semiconducting oxide such as indium oxide, tin oxide, antimony oxide, or tellurium oxide, the dopant may comprise oxygen vacancies.

[0065] Suitable compound semiconductors include semiconducting halides, such as semiconducting iodides or semiconducting bromides. In some embodiments, the main component of the doped semiconductor comprises tin iodide. In such embodiments, the dopant may comprise a chalcogenide, such as tellurium.

[0066] In some embodiments, the doped semiconductor comprises an elemental semiconductor. A suitable elemental semiconductor includes tellurium, i.e. Te. In other words, the main component of the doped semiconductor can include tellurium.

[0067] In some embodiments, for example, when the base component of the doped semiconductor includes tellurium, the dopant may include a halogen, such as iodine.

[0068] Advantageously, the dopant may have a relatively high capture cross section for EUV radiation. For example, the dopant may have a capture cross section of 2×10 6 cm 2 / mol. For example, the dopants can include one or more of lead (Pb), cesium (Cs), bismuth (Bi), indium (In), aluminum (Al), magnesium (Mg), titanium (Ti), yttrium (Y), lanthanum (La), strontium (Sr), terbium (Tb), antimony (Sb), tellurium (Te), germanium (Ge), hafnium (Hf), and ytterbium (Yb).

[0069] In some embodiments, the dopant comprises a halogen.Suitable halogens include bromine and iodine.For example, halogens such as iodine and bromine can be employed to dope stoichiometric or non-stoichiometric semiconductors such as semiconductor oxides.For example, the bromine-doped semiconductor or iodine-doped semiconductor can be selected from the list consisting of silicon oxycarbide, silicon oxide, tellurium oxide, tin oxide, indium oxide, and germanium oxide.

[0070] In some embodiments, the dopant comprises an alkali metal. Suitable alkali metals include cesium.

[0071] In some embodiments, the dopant comprises a chalcogenide. Suitable chalcogenides include selenium.

[0072] Exposure dose reduction layers according to the present disclosure can be formed by any suitable method, for example, by atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0073] The method of forming the layer is further described herein. Advantageously, the layer can be employed as an exposure dose reducing layer as described herein. In some embodiments, the method as described herein can include providing the substrate to a reaction chamber. This can be done by a substrate handler, such as, for example, a segmented robot arm, a linear actuator, a rotary actuator, a conveyor belt, an air cushion, or the like.

[0074] Methods according to embodiments of the present disclosure may further include performing a cyclic deposition process. The cyclic deposition process may include a plurality of cycles. A plurality of cycles may include a main component precursor pulse and a dopant reactant pulse. The main component precursor pulse may include contacting the substrate with the main component precursor. The dopant reactant pulse may include contacting the substrate with the dopant reactant.

[0075] In some embodiments, the layer, e.g., the exposure dose reduction layer, may comprise a doped elemental semiconductor. Suitable elemental semiconductors include diamond, diamond-like carbon, tin, indium, selenium, germanium, antimony, and tellurium.

[0076] In some embodiments, the main component precursor comprises a carbon precursor and the dopant reactant comprises a boron reactant.Therefore, a layer, such as a reduced exposure layer, containing boron-doped diamond or boron-doped diamond-like carbon can be produced, which can have excellent secondary electron yield.Nitrogen is a deep donor in diamond, and N-doped diamond samples are insulators at room temperature.It has been shown that the secondary electron yield (SEY) from N-doped diamond is very low.In contrast, boron is a shallow acceptor in diamond, and therefore boron-doped diamond samples are advantageously conductive and have a higher SEY.

[0077] In some embodiments, the cyclical deposition process includes a main component precursor pulse, a main component reactant pulse employing an oxygen reactant, and a dopant reactant pulse. The main component reactant pulse employing an oxygen reactant may be referred to as an oxygen reactant pulse. The main component precursor pulse may include contacting the substrate with the precursor. The reactant pulse may include contacting the substrate with the dopant reactant. The oxygen reactant pulse includes contacting the substrate with the oxygen reactant.

[0078] In some embodiments, the oxygen reactant comprises an oxygen-containing gas, such as N2O, NO, NO2, NO3, N2O4, N2O5, H2O, H2O2, O2, or O3.

[0079] In some embodiments, the oxygen reactant comprises an active species. Suitable active species include ions and radicals. The active species can be generated using plasma. In some embodiments, the plasma contacts the substrate. Suitable plasma can be generated using plasma gas containing O2, so-called O2 plasma, which can suitably generate oxygen atoms and oxygen radicals, which can be used individually or in combination as oxygen reactant.

[0080] When using a relatively strong oxygen reactant such as O3 or O2 plasma, an oxide semiconductor with a small or negligible amount of oxygen vacancies may result, with a resistive film as a result. For example, doped In2O3 can be made using a main component precursor containing indium, i.e., an indium precursor, a dopant reactant, and a main component reactant containing oxygen, i.e., an oxygen reactant. When O3 is used as the oxygen reactant, the process produces a more perfect In2O3 stoichiometry with fewer oxygen vacancies compared to that produced using water as the oxygen reactant, resulting in increased resistivity and less secondary electron emission. Incorporating dopants into such high resistivity films can advantageously increase the electrical conductivity and therefore the electron emission. In some embodiments, the indium oxide can be doped with one or more dopants selected from cesium, iodine, and tellurium.

[0081] In some embodiments, the main component precursor comprises a tellurium precursor comprising tellurium. In some embodiments, the tellurium precursor is selected from Te(OEt)4, Te(SiMe3)2, Te(SiEt3)2, TeCl4, and TeRR', where R and R' are independently any C1-C6 alkyl or alkenyl. It is understood that Et represents ethyl and Me represents methyl. In some embodiments, the tellurium precursor is selected from Te(vinyl)4, Te(allyl)4, Te(iPr)2, Te chloride, Te ethoxide, Te[NH(Si(CH3)3)]2.

[0082] In some embodiments, the main component precursor comprises a tin precursor comprising tin. In some embodiments, the tin precursor is selected from tin alkenyls such as Sn(vinyl)4 and Sn(allyl)4, tin alkyls such as SnMe4, and tin alkylamines such as tetrakis(dimethylamido)tin(IV). In some embodiments, the tin precursor is selected from tin halides such as SnCl4, tin alkyls such as SnHBu3, dimethylamino-2-methyl-2-propoxy-tin(II) (Sn(dmamp)2), bis(diisopropylacetamidinato)tin(II) (Sn(iPr2AMD)2), bis(N,N'-diisopropylformamidinato)tin(II) (Sn(iPr2FMD)2), tin alkylamines such as Sn(NEtMe)4, tin alkoxides such as Sn(OtBu)4, tin halides such as SnI4, tin alkyls such as SnEt4, and tin β-diketonates such as tin(II) acetylacetonate (Sn(acac)2). It should be understood that Me represents methyl, Bu represents butyl, and tBu represents tert-butyl.

[0083] In some embodiments, the main component precursor comprises an antimony precursor comprising antimony. In some embodiments, the antimony precursor may comprise one or more of antimony halides such as SbCl3 and SbCl5, antimony alkylsilyls such as Sb(SiMe3)3 and Sb(SiEt3)3, antimony alkylamines such as Sb(NMe2)3, antimony alkyls such as SbEt3 and SbR3, where R is C1-C6 alkyl, and antimony alkoxides such as SbOEt3. It is understood that Me represents methyl, Et represents ethyl, and OEt represents ethoxide.

[0084] In some embodiments, the dopant reactant comprises a halogen. Exemplary halogens include fluorine, chlorine, bromine, and iodine.

[0085] In some embodiments, the dopant reactant comprises iodine. Suitable iodine-containing reactants include iodoalkanes, such as 1,2-diiodoethane, CH3I, and CH2I2. In some embodiments, the dopant reactant can comprise a metal iodide, such as a post-transition metal iodide, such as SnI4. In some embodiments, the dopant reactant comprises elemental iodine, I2. In some embodiments, the dopant reactant comprises an iodine-substituted saturated or unsaturated cyclic hydrocarbon, such as an iodine-substituted saturated cyclic hydrocarbon, such as cyclopentyl iodide or cyclohexyl iodide. In some embodiments, the dopant reactant is selected from the list of C1-C10 iodoalkyl, C2-C10 iodoalkenyl, and C6-C10 iodoaryl, which can comprise at least 1 to 4 iodine atoms. In some embodiments, the dopant reactant is selected from the list consisting of diiodomethane, 1,2-diiodoethane, 1-iodobutane, 1-iodohexane, iodobenzene, iodotoluene, allyl iodide, and vinyl iodide.

[0086] In some embodiments, the dopant reactant comprises bromine. Suitable bromine-containing reactants include bromoalkanes, such as 1,2-dibromoethane, CH3Br, and CH2Br2. In some embodiments, the dopant reactant can comprise a metal bromide, such as a post-transition metal bromide, such as SnBr4. In some embodiments, the dopant reactant comprises elemental bromine, Br2.

[0087] In some embodiments, the dopant reactant comprises an iodinated hydrocarbyl, such as an iodinated C1-C10 linear or branched alkyl, or an iodinated C6-C10 substituted aryl, where the alkyl or aryl can contain from 1 to 4 iodine atoms, which can be on the same atom, adjacent atoms, or non-adjacent atoms. In some embodiments, the dopant reactant comprises a compound selected from the list consisting of phenyl iodide, 1-iodohexane, and 1-iodo-butane.

[0088] In some embodiments, the dopant reactant comprises a brominated hydrocarbyl, such as a brominated C1-C10 linear or branched alkyl, or a brominated C6-C10 substituted aryl, where the alkyl or aryl can contain from 1 to 4 bromine atoms, which can be on the same atom, adjacent atoms, or non-adjacent atoms. In some embodiments, the dopant reactant comprises a compound selected from the list consisting of phenyl bromide, 1-bromohexane, and 1-bromo-butane.

[0089] In some embodiments, the dopant reactant is selected from the list consisting of HBr, HI, N-bromosuccinimide, N-iodosuccinimide, TiBr4, and TiI4.

[0090] In some embodiments, the dopant reactant comprises cesium, i.e., comprises a cesium reactant. Suitable cesium reactants include alkylsilylamides such as cesium bis(trimethylsilyl)amide, Cs[Y(β-diketonato)4]-type precursors such as Cs[Y(ptac)4], and cesium halides such as CsI. It will be appreciated that the β-diketonato ligand can be of the general formula CF3COCHCOR, where R is tert-butyl for ptac, R is CF3 for hfac, R is methyl for tfac, and R is phenyl for btfac. Suitable cesium alkoxides include branched or linear alkoxides such as C3-C7 alkoxides such as Cs(OtBu), where OtBu represents tert-butoxide.

[0091] In some embodiments, the dopant reactant comprises a selenium reactant that includes selenium. Suitable selenium reactants include selenium halides such as SeO2, SeCl4, selenium alkyl silyls such as H2Se, Se(SiMe3)2 and Se(SiEt3)2, and selenium alkyls such as Se2Et2 and SeEt2, where Me is methyl and Et is ethyl.

[0092] In some embodiments, the main reactant comprises oxygen. In other words, the main reactant may comprise an oxygen reactant. Suitable oxygen reactants may be selected from the list including O3, O2, H2O, H2O2, N2O, NO, NO2, and NO3.

[0093] In some embodiments, the cyclic deposition process is a thermal cyclic deposition process. A thermal process can include activating a chemical reaction by thermal energy. A thermal process can be contrasted with a plasma process, which can employ a plasma to generate activated species, such as ions or radicals, that can activate a chemical reaction at a relatively lower temperature.

[0094] The thermal cyclic deposition process may be performed in an embodiment of system 200 according to an exemplary embodiment of the present disclosure. System 200 may be used to perform methods as described herein and / or to form structures or device portions as described herein.

[0095] In the illustrated embodiment, the system 200 includes one or more reaction chambers 202 , a first precursor gas source 204 , a reactant gas source 206 , a purge gas source 208 , an exhaust 210 , and a controller 212 .

[0096] The reaction chamber 202 can include any suitable reaction chamber, such as an ALD or CVD reaction chamber.

[0097] The first precursor gas source 204 can include a container and one or more precursors as described herein, alone or mixed with one or more carrier gases (e.g., noble gases). The second precursor gas source 206 can include a container and one or more reactants as described herein, alone or mixed with one or more carrier gases.

[0098] The purge gas source 208 can include one or more noble gases as described herein. Although illustrated with four gas sources 204-208, the system 200 can include any suitable number of gas sources. The gas sources 204-208 can be coupled to the reaction chamber 202 via lines 214-218, each of which can include flow controllers, valves, heaters, and the like.

[0099] The exhaust 210 may include one or more vacuum pumps.

[0100] The controller 212 includes electronic circuitry and software for selectively operating the valves, manifolds, heaters, pumps, and other components included within the system 200. These circuitry and components operate to introduce precursor and purge gases from their respective sources 204-208. The controller 212 can control the timing of gas pulse sequences, the temperature of the substrate and / or reaction chamber, the pressure within the reaction chamber, and various other operations to provide proper operation of the system 200. The controller 212 can include control software that electrically or pneumatically controls valves to control the flow of precursors, reactants, and purge gases into and out of the reaction chamber 202. The controller 212 can include software or hardware components, such as modules, e.g., FPGAs or ASICs, that perform certain tasks. The modules can be advantageously configured to reside on an addressable storage medium of the control system and can be configured to execute one or more processes.

[0101] Other configurations of the system 200 are possible, including different numbers and types of precursor and reactant sources, and purge gas sources. Additionally, it will be appreciated that there are numerous arrangements of valves, conduits, precursor sources, and purge gas sources that may be used to achieve the goal of selectively feeding gases into the reaction chamber 202. Additionally, as a schematic representation of the system, many components have been omitted for simplicity of illustration, and such components may include, for example, various valves, manifolds, purifiers, heaters, vessels, vents, and / or bypasses.

[0102] During operation of the reactor system 200, a substrate (not shown), such as a semiconductor wafer, is transferred, for example, from a substrate handling system to the reaction chamber 202. Once the substrate is transferred to the reaction chamber 202, one or more gases, such as precursors, reactants, carrier gases, and / or purge gases from gas sources 204-208, are introduced into the reaction chamber 202.

[0103] Embodiments of the reactor system 200 can be employed to perform cyclic deposition processes, such as atomic layer deposition processes, as described herein.

[0104] A schematic representation of an embodiment of a cyclical deposition process, such as an atomic layer deposition process, is shown in Figure 3. The process further includes positioning 311 a substrate on a substrate support. The process further includes a plurality of deposition cycles 319. From the plurality of deposition cycles can include a main component precursor pulse 312, an optional main component precursor post purge 313, an optional main component reactant pulse 314, an optional main component reactant post purge 315, a dopant reactant pulse 316, and a dopant reactant post purge 317. After a predetermined number of deposition cycles 319 have been performed, the process can end 318.

[0105] The main component precursor pulse 312 can include exposing the substrate to a main component precursor as described herein. The main component precursor post purge 313 can include exposing the substrate to a purge gas as described herein. The main component reactant pulse 314 can include exposing the substrate to a main component reactant as described herein. The main component reactant post purge 315 can include exposing the substrate to a purge gas as described herein. The dopant reactant pulse 316 can include exposing the substrate to a dopant reactant as described herein. The dopant reactant post purge 317 can include exposing the substrate to a purge gas as described herein.

[0106] In some embodiments, at least one of the precursors and reactants comprises an activated species, hi some embodiments, the activated species is generated in a plasma.

[0107] In some embodiments, the exposure dose reduction layer comprises iodine-doped tin oxide. Such an exposure dose reduction layer can be advantageously produced using a plasma-enhanced cyclic deposition process, for example by plasma-enhanced atomic layer deposition. An exemplary embodiment of a plasma-enhanced cyclic deposition process can include multiple deposition cycles. The deposition cycle can include, in a given order, a precursor pulse, a first plasma pulse, a reactant pulse, and a second plasma pulse. The precursor pulse can include exposing the substrate to a tin precursor. The first plasma pulse can include exposing the substrate to an oxygen plasma, i.e., a plasma generated using a plasma gas containing oxygen and optionally a noble gas such as He or Ar. The reactant pulse can include exposing the substrate to a halogen-containing reactant, for example an iodine-containing reactant. The second plasma pulse can include exposing the substrate to a noble gas plasma, such as an argon plasma.

[0108] In some embodiments, an exposure dose reduction layer comprising a halogen-doped tin oxide, e.g., iodine-doped tin oxide, can be produced by first forming a tin oxide layer and then exposing the tin oxide layer to a halogen-containing reactant, e.g., an iodine-containing reactant. For example, the tin oxide layer can be formed using thermal or plasma-enhanced atomic layer deposition.

[0109] For example, an exposure dose reduction layer can be produced using an embodiment of the process described in FIG. 3. In some embodiments, producing such an exposure dose reduction layer can include generating a plasma during one or more steps of the embodiment of FIG. 3. For example, the main component precursor pulse 312 can include generating activated species using a plasma. For example, the main component precursor post purge 313 can include generating activated species using a plasma. For example, the main component reactant pulse 314 can include generating activated species using a plasma and exposing the substrate to these activated species. For example, the main component reactant post purge 315 can include generating activated species using a plasma and exposing the substrate to these activated species. For example, the dopant reactant pulse 316 can include generating activated species using a plasma and exposing the substrate to these activated species. For example, the dopant reactant post purge 317 can include generating activated species using a plasma and exposing the substrate to these activated species. The activated species can include at least one of ions and radicals.

[0110] In some embodiments, the exposure dose reduction layer can be fabricated using an embodiment of the process described in Figure 8. The process of Figure 8 further includes step 811 of positioning a substrate on a substrate support. The process then includes performing a plurality of supercycles 817. One from the plurality of supercycles 817 includes a dopant reactant pulse 814 and one or more, for example, a plurality of subcycles 816. Each subcycle includes a main component precursor pulse 812 and a main component reactant pulse 813. After a predetermined amount of supercycles have been performed, a layer having a suitable thickness is deposited and the process ends 815. Optionally, one or more of the aforementioned pulses can be separated by a purge step.

[0111] The main component precursor pulse 812 can include exposing the substrate to a main component precursor as described herein. The main component reactant pulse 813 can include exposing the substrate to a main component reactant as described herein. The dopant reactant pulse 814 can include exposing the substrate to a dopant reactant as described herein. In some embodiments, the dopant reactant includes a dopant precursor, and the dopant reactant pulse can be generated thermally, i.e., without exposing the substrate to activated species generated in a plasma. In some embodiments, the dopant reactant pulse can include exposing the substrate to one or more activated species, such as ions and radicals, generated in a plasma.

[0112] In an exemplary embodiment, and in a process according to the embodiment of the process of FIG. 8, the main component precursor can include indium, the main component reactant can include oxygen, and the dopant reactant can include active species such as at least one of radicals or ions. Suitable radicals include hydrogen radicals. Suitable ions include oxygen ions. Advantageously, at least one of hydrogen radicals and oxygen radicals can be generated in a hydrogen plasma. Suitable hydrogen plasma can include a hydrogen source such as H2, and a noble gas such as He, Ne, Ar, Xe, or Kr. Advantageously, an indium oxide layer containing oxygen vacancies can therefore be obtained. The oxygen vacancies can act as dopants.

[0113] In some embodiments, the methods as described herein can include exposing the substrate to a plasma, such as a hydrogen plasma. A "hydrogen plasma" can refer to a plasma in which the plasma gas includes hydrogen together with one or more noble gases, such as, for example, He, Ne, Ar, Kr, or Xe.

[0114] In some embodiments, when the doped semiconductor base comprises a compound semiconductor, such as a semiconducting oxide, such as In2O3, a hydrogen plasma post-deposition treatment may be applied.

[0115] Advantageously, the hydrogen plasma post-treatment can abstract one or more constituent elements from the doped semiconductor, e.g., oxygen from the semiconductor oxide, which can result in the creation of oxygen vacancies, which can act as electron donating sites, i.e., n-type dopants, thereby enhancing electrical conductivity in the semiconductor oxide, which in turn can enhance the secondary electron yield from the exposure reduction layer.

[0116] Layers formed by methods according to the present disclosure may be formed in any suitable apparatus, including in a reactor such as that shown in Figure 4. Similarly, structures provided herein or parts thereof may be fabricated in any suitable apparatus, including in a reactor such as that shown in Figure 4. Figure 4 is a schematic diagram of a plasma-enhanced atomic layer deposition (PEALD) apparatus, along with programmed controls for carrying out the sequences described below, that may be desirably used in some embodiments of the present invention. In this diagram, a pair of conductive plate electrodes 402, 404 are provided parallel and facing each other within the interior 411 (reaction zone) of a reaction chamber 403, and a plasma is excited between the electrodes by applying RF power (e.g., at 13.56 MHz and / or 27 MHz) from a power source 425 to one side and electrically grounding the other side 412.

[0117] A temperature regulator may be provided on the lower stage 402, i.e., the lower electrode. The substrate 401 is placed thereon, and its temperature is kept constant at a given temperature. The upper electrode 404 may also function as a shower plate, and may introduce reactant gases, and / or dilution gases, if any, as well as precursor gases into the reaction chamber 403 through gas lines 421 and 422, respectively, and through the shower plate 404. In addition, a circular duct 413 with an exhaust line 417 is provided in the reaction chamber 403, through which the gas in the interior 411 of the reaction chamber 403 is exhausted. In addition, a transfer chamber 405 is disposed below the reaction chamber 403, and the transfer chamber 405 is provided with a gas seal line 424 for introducing a seal gas into the interior 411 of the reaction chamber 403 through the interior 416 of the transfer chamber 405, and a separation plate 414 for separating the reaction zone and the transfer zone is provided. The gate valve through which the wafer may be transferred into or out of the transfer chamber 405 is omitted from this view. The transfer chamber is also provided with an exhaust line 406. In some embodiments, forming the exposure reducing layer and forming the EUV resist are performed in one and the same reaction chamber. In some embodiments, they can be formed in separate reaction chambers included in one cluster system in which the substrate can be transferred from one reaction chamber to another without breaking vacuum or while maintaining the substrate in an inert gas environment, such as a noble gas environment.

[0118] FIG. 5 shows a schematic representation of an embodiment of a subsystem 500 as described herein. It can be used, for example, to form at least one of an exposure dose reduction layer and an EUV resist. The subsystem 500 includes a reaction chamber 510 in which a plasma 520 is generated. Specifically, the plasma 520 is generated between a showerhead injector 530 and a substrate support 540. This is a direct plasma configuration employing capacitively coupled plasma. In the configuration shown, the subsystem 500 includes two alternating current (AC) power sources: a high frequency power source 521 and a low frequency power source 522. In the configuration shown, the high frequency power source 521 provides radio frequency (RF) power to the showerhead injector, and the low frequency power source 522 provides an AC current signal to the substrate support 540. The radio frequency power can be provided at frequencies of, for example, 13.56 MHz or higher, for example, at frequencies of at least 100 kHz up to 50 MHz, or at frequencies of at least 50 MHz up to 100 MHz, or at frequencies of at least 100 MHz up to 200 MHz, or at frequencies of at least 200 MHz up to 500 MHz, or at frequencies of at least 500 MHz up to 1000 MHz, or at frequencies of at least 1000 MHz up to 2000 MHz. The low frequency alternating current signal can be provided at frequencies of 2 MHz or lower, for example, at frequencies of at least 100 kHz up to 200 kHz, or at frequencies of at least 200 kHz up to 500 kHz, or at frequencies of at least 500 kHz up to 1000 kHz, or at frequencies of at least 1000 kHz up to 2000 kHz. Process gases, including precursors, reactants, or both, are provided to the conical gas distributor 550 through gas line 560. The process gases then pass through holes 531 in the showerhead injector 530 into the reaction chamber 510 .

[0119] While high frequency power source 521 is shown as being electrically connected to the showerhead injector and low frequency power source 522 is shown as being electrically connected to the substrate support 540, other configurations are possible as well. For example, in some embodiments (not shown), both high frequency and low frequency power sources can be electrically connected to the showerhead injector, or both high frequency and low frequency power sources can be electrically connected to the substrate support, or the high frequency power source can be electrically connected to the substrate support and the low frequency power source can be electrically connected to the showerhead injector.

[0120] FIG. 6 shows a schematic representation of another embodiment of a subsystem 600 as described herein, which can be used, for example, to form at least one of an exposure dose reducing layer and an EUV resist. The configuration of FIG. 6 can be described as an indirect plasma system. The subsystem 600 includes a reaction chamber 610 separated from a plasma generation space 625 in which a plasma 620 is generated. Specifically, the reaction chamber 610 is separated from the plasma generation space 625 by a showerhead injector, and the plasma 620 is generated between the showerhead injector 630 and a plasma generation space ceiling 626.

[0121] In the configuration shown, the subsystem 600 includes three alternating current (AC) power sources, a high frequency power source 621 and two low frequency power sources 622, 623: a first low frequency power source 622 and a second low frequency power source 623. In the configuration shown, the high frequency power source 621 provides radio frequency (RF) power to the plasma generation space ceiling, the first low frequency power source 622 provides an alternating current signal to the showerhead injector 630, and the second low frequency power source 623 provides an alternating current signal to the substrate support 640. The substrate 641 is provided on the substrate support 640. The radio frequency power can be provided at a frequency of, for example, 13.56 MHz or higher. The low frequency AC signals of the first low frequency power source 622 and the second low frequency power source 623 can be provided at a frequency of, for example, 2 MHz or lower.

[0122] Process gases, including precursors, reactants, or both, are provided to the plasma generation space 625 through gas lines 660 that pass through the plasma generation space ceiling 626. Active species, such as ions and radicals, generated by the plasma 625 from the process gases pass through holes 631 in a showerhead injector 630 into the reaction chamber 610.

[0123] FIG. 7 shows a schematic representation of another embodiment of a subsystem 700 as described herein. It can be used, for example, to form at least one of a secondary electron reflecting layer, a secondary electron generating layer, an adhesive layer, and an EUV resist. The configuration of FIG. 7 can be described as a remote plasma system. The subsystem 700 includes a reaction chamber 710 operatively connected to a remote plasma source 725 in which a plasma 720 is generated. Any type of plasma source can be used as the remote plasma source 725, for example, an inductively coupled plasma, a capacitively coupled plasma, or a microwave plasma.

[0124] Specifically, activated species are provided from the plasma source 725 to the reaction chamber 710 via activated species duct 760, to the cone distributor 750, and through holes 731 in the shower plate injector 730 to the reaction chamber 710. Therefore, activated species can be provided to the reaction chamber in a uniform manner.

[0125] In the configuration shown, the subsystem 700 includes three alternating current (AC) power sources, a high frequency power source 721 and two low frequency power sources 722, 723: a first low frequency power source 722 and a second low frequency power source 723. In the configuration shown, the high frequency power source 721 provides radio frequency (RF) power to the plasma generation space ceiling, the first low frequency power source 722 provides an alternating current signal to the showerhead injector 730, and the second low frequency power source 723 provides an alternating current signal to the substrate support 740. The substrate 741 is provided on the substrate support 740. The radio frequency power can be provided at a frequency of, for example, 13.56 MHz or higher. The low frequency AC signals of the first low frequency power source 722 and the second low frequency power source 723 can be provided at a frequency of, for example, 2 MHz or lower.

[0126] In some embodiments (not shown), an additional radio frequency power source can be electrically connected to the substrate support, and thus a direct plasma can be generated within the reaction chamber.

[0127] Process gases, including precursors, reactants, or both, are provided to the plasma source 725 by gas line 760. Active species, such as ions and radicals, generated by the plasma 725 from the process gases are guided to the reaction chamber 710.

[0128] With reference to FIG. 9, an embodiment of a system 900 that can be employed to form a structure comprising an exposure dose reduction layer and an EUV resist is further described herein. The structure can be formed on a substrate that is held in a vacuum or inert gas environment during and between the formation of the exposure dose reduction layer and the EUV resist. The system 900 comprises an exposure dose reduction layer reaction chamber 910 constructed and arranged to form an exposure dose reduction layer on the substrate. The system 900 further comprises an EUV resist reaction chamber 920 constructed and arranged to form an EUV resist on the exposure dose reduction layer. The system further comprises a wafer handling robot 930 constructed and arranged to move the substrate from the exposure dose reduction layer reaction chamber 910 to the EUV resist reaction chamber 920. Advantageously, this can be done without breaking vacuum or while the substrate is held in an inert, i.e. non-reactive gas environment, such as a noble gas environment.

[0129] In an exemplary embodiment, reference is made to FIG. 1, which shows an embodiment of a structure 100 in which the exposure dose reduction layer 120 comprises iodine doped tellurium. The exposure dose reduction layer comprises carbon, which advantageously allows the surface free energy of the exposure dose reduction layer to be adjusted to a desired value. The exposure dose reduction layer is formed by a plasma enhanced cyclic deposition process. The cyclic deposition process comprises a plurality of cycles, from which, in a given order, a tellurium precursor pulse, an argon plasma step, an iodine reactant pulse, and an iodine reactant post purge. The tellurium precursor pulse comprises exposing the substrate to a tellurium precursor. The argon plasma step comprises exposing the substrate to an argon plasma. The iodine reactant pulse comprises exposing the substrate to a reactant. The iodine reactant post purge comprises exposing the substrate to a purge gas, such as a noble gas, such as argon. It is noted that the substrate was not exposed to a plasma between the subsequent iodine reactant pulse and the tellurium precursor pulse. In other words, the iodine reactant post purge was performed thermally. Diisopropyl telluride was used as the tellurium precursor. 1,2-diiodoethane was used as the iodine precursor. Other iodoalkanes, such as diiodomethane, may alternatively be used as the iodine precursor. The results were characterized by iodine to tellurium ratios of 17 to 39 atomic percent and had advantageously low roughness. Advantageously, a 13 percent dose reduction was obtained. [Explanation of symbols]

[0130] 100 Structure 110 Base material 120 Exposure reduction layer 130 Extreme Ultraviolet (EUV) Resist 200 Systems 202 Reaction chamber 204 First precursor gas source 206 Reactant Gas Source 208 Purge gas source 210 Exhaust 212 Controller 214~218 Line 319 Multiple Deposition Cycles 816 Multiple Subcycles 817 Multiple Supercycles

Claims

1. A structure comprising: a substrate, an exposure reducing layer on said substrate; an extreme ultraviolet (EUV) resist on said exposure dose reducing layer, A structure wherein the exposure dose reducing layer comprises a doped semiconductor, the doped semiconductor comprising a base component and a dopant.

2. 10. The structure of claim 1, wherein the doped semiconductor has a band gap of at least 2.0 eV.

3. 3. The structure of claim 1 or 2, wherein the EUV resist is selected from metal-organic framework resists, metal oxide resists, and chemically amplified resists.

4. The structure of claim 1 or 2, wherein the primary component comprises an elemental semiconductor.

5. The structure of claim 4 wherein the elemental semiconductor comprises tellurium.

6. The structure of claim 1 or 2, wherein the main component comprises a compound semiconductor.

7. The structure of claim 6 , wherein the compound semiconductor comprises indium (III) oxide.

8. The structure of claim 6 , wherein the dopants comprise vacancies.

9. The structure of claim 8 , wherein the vacancies comprise oxygen vacancies.

10. The structure of claim 1 or 2, wherein the dopant comprises iodine.

11. 1. A method comprising: - providing a substrate into a reaction chamber; forming an exposure reducing layer on said substrate; - optionally forming an adhesive layer on said substrate; forming an EUV resist on the substrate, Where: - said EUV resist is arranged to absorb EUV radiation and generate secondary electrons; The method, wherein the exposure dose reducing layer comprises a main component and a dopant.

12. 12. The method of claim 11, further comprising exposing the EUV resist to EUV radiation through a mask.

13. The method of claim 11 or 12, wherein the main component comprises an elemental semiconductor.

14. The method of claim 13 , wherein the elemental semiconductor comprises tellurium.

15. The method of claim 11 or 12, wherein the main component comprises a compound semiconductor.

16. The method of claim 15 , wherein the compound semiconductor comprises indium (III) oxide.

17. The method of claim 15 , wherein the dopant comprises a vacancy.

18. The method of claim 17 , wherein the vacancies comprise oxygen vacancies.

19. The method of claim 11 or 12, wherein the dopant comprises iodine.

20. 1. A method of forming a layer, comprising: - providing a substrate to a reaction chamber by a substrate handler; performing a cyclic deposition process, the cyclic deposition process comprising a plurality of cycles, a cycle from the plurality of cycles comprising a main component precursor pulse and a dopant reactant pulse; - the main component precursor pulse comprises contacting the substrate with a main component precursor, - the reactant pulse comprises contacting the substrate with a dopant reactant; The method wherein the primary component precursor comprises tellurium and the dopant reactant comprises iodine.

21. The method of claim 20 , wherein the primary component precursor comprises a tellurium alkyl.

22. 22. The method of claim 21 , wherein the tellurium alkyl comprises diisopropyl telluride.

23. The method of claim 21 , wherein the dopant reactant comprises an iodoalkane.

24. 24. The method of claim 23, wherein the iodoalkane comprises 1,2-diiodoethane.

25. The method of claim 20 , wherein the deposition process is a thermal cyclic deposition process.

26. The method of any one of claims 20 to 25, wherein at least one of the precursors and the reactants comprises an activated species, the activated species being generated in a plasma.

Images