Photoresist with multiple patterning radiation-absorbing elements and / or vertical composition gradient

Abstract

To provide a method for depositing a photoresist material on a substrate.SOLUTION: A method includes, in a process station 300, providing a substrate 312 in a process chamber body 302, and providing a first reactant and a second reactant to a reaction chamber. The first reactant is an organo-metallic precursor having a formula of M1aR1bL1c. In the formula, M1 is a metal having a high patterning radiation-absorption cross-section, R1 is an organic group that survives the reaction between the first reactant and the second reactant and that is cleavable from M1 under exposure to patterning radiation, L1 is a ligand, ion, or other moiety that reacts with the second reactant, a≥1, b≥1 and c≥1, and at least one of the following conditions is satisfied: the photoresist material comprises two or more high-patterning radiation absorbing elements, and the photoresist material comprises a composition gradient along the thickness of the photoresist material.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] [Incorporated by reference] A PCT application is being filed contemporaneously herewith as a part of this application, and each application identified in that contemporaneously filed PCT application to which this application claims benefit or priority is hereby incorporated by reference in its entirety for all purposes.

[0002] The present disclosure relates generally to the field of semiconductor processing. In certain aspects, the present disclosure describes novel photoresist (PR) materials made via a reaction between one or more organometallic precursors and one or more counter-reactive agents. [Background technology]

[0003] As semiconductor fabrication continues to advance, feature sizes continue to shrink, requiring new processing methods. One area where advances are being made is in patterning, for example, using photoresist materials that are sensitive to lithographic radiation.

[0004] The background description provided herein is intended to provide a general overview of the contents of the present disclosure. Work by the currently named inventors within the scope of what is described in this Background section, as well as aspects of the description that may not otherwise be regarded as prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure. Summary of the Invention

[0005] Various embodiments herein relate to methods, materials, apparatus, and systems for depositing a photoresist material on a substrate. In one aspect of the disclosed embodiments, a method for depositing a photoresist material on a substrate is provided, the method including providing a substrate in a reaction chamber, providing a first reactant and a second reactant to the reaction chamber to initiate a reaction between the first reactant and the second reactant, thereby depositing a photoresist material on the substrate, the first reactant and the second reactant each being provided to the reaction chamber in a gas phase, the first reactant being M1 a R1 b L1 c where M1 is a metal having a high patterning radiation absorption cross section, R1 is an organic group that survives reaction between a first reactant and a second reactant and is cleavable from M1 upon exposure to patterning radiation, and L1 is a ligand, ion, or other moiety that reacts with the second reactant, a≧1, b≧1, and c≧1, and at least one of the following conditions is met: (a) the photoresist material comprises two or more elements that have a high patterning radiation absorption cross section, and / or (b) the photoresist material comprises a compositional gradient along the thickness of the photoresist material.

[0006] In various embodiments, the photoresist material may be an extreme ultraviolet (EUV) photoresist material, and M1 may have a high EUV absorption cross section. In some cases, the second reactant may include a hydroxyl moiety. In some cases, the second reactant may include a material selected from the group consisting of water, peroxide, di- or polyhydroxy alcohol, fluorinated di- or polyhydroxy alcohol, fluorinated glycol, and combinations thereof. In some cases, the second reactant may include a material capable of bridging metal atoms via sulfur bridges and / or tellurium bridges. In some embodiments, the second reactant may include a material selected from the group consisting of hydrogen sulfide, hydrogen disulfide, bis(trimethylsilyl)tellurium, and combinations thereof. In some embodiments, the second reactant may include hydrogen iodide. In various embodiments, the second reactant replaces one or more L1, thereby bridging two or more atoms of M1 via chemical bonds.

[0007] A number of different metals can be used for M1. In various embodiments, the EUV absorption cross section of M1 is greater than or equal to 1×10 7 cm 2 / mol or more. In these or other cases, M1 may include a metal selected from the group consisting of Sn, Sb, In, Bi, Te, and combinations thereof. Similarly, several different organic groups can be used for R1. In some cases, R1 may include an alkyl group or a halogen-substituted alkyl group. In some such cases, the alkyl group may include three or more carbon atoms. In these or other cases, R1 may include at least one beta hydrogen or beta fluorine. In some embodiments, R1 may be selected from the group consisting of i-propyl, n-propyl, t-butyl, i-butyl, n-butyl, sec-butyl, n-pentyl, i-pentyl, t-pentyl, sec-pentyl, and combinations thereof. Additionally, several different groups can be used for L1. In some embodiments, L1 may include a moiety selected from the group consisting of amine, alkoxy, carboxylate, halogen, and combinations thereof.

[0008] A variety of exemplary reactants are provided herein. In some cases, the first reactant is t-butyltris(dimethylamino)tin, i-butyltris(dimethylamino)tin, n-butyltris(dimethylamino)tin, sec-butyltris(dimethylamino)tin, i-propyl(tris)dimethylaminotin, n-propyltris(diethylamino)tin, t-butyltris(t-butoxy)tin, i-butyltris(t-butoxy)tin, n-butyltris(t-butoxy)tin, sec-butyltris(t-butoxy)tin, i-propyl(tris)dimethylaminotin, The photoconductive additive may comprise a material selected from the group consisting of tris(t-butoxy)tin, n-propyltris(t-butoxy)tin, t-butyltrichlorotin, i-butyltrichlorotin, n-butyltrichlorotin, sec-butyltrichlorotin, i-propyltrichlorotin, n-propyltrichlorotin, t-butyltribomostin, i-butyltribomostin, n-butyltribomostin, sec-butyltribomostin, i-propyltribromostin, n-propyltribromostin, and combinations thereof.

[0009] In some cases, the method may further include exposing the substrate to a plasma and replacing some M1-L1 bonds with M1-H bonds. In certain embodiments, the reaction between the first reactant and the second reactant may be a chemical vapor deposition reaction, an atomic layer deposition reaction, or a combination thereof. In some cases, the first reactant and the second reactant may be provided to the reaction chamber simultaneously. In other cases, the first reactant and the second reactant are not delivered to the reaction chamber simultaneously.

[0010] In some embodiments, the temperature of the substrate may be equal to or less than the temperatures of the first and second reactants as they are delivered to the reaction chamber. In these or other embodiments, initiating a reaction between the first and second reactants may include exposing the substrate to a plasma. In some embodiments, initiating a reaction between the first and second reactants may include exposing the substrate to thermal energy.

[0011] In some embodiments, the method may further include providing a third reactant to the reaction chamber to initiate a reaction between the second and third reactants or between the third and fourth reactants. In some such cases, each of the first and third reactants may include a metal selected from the group consisting of Sn, Sb, In, Bi, and Te, and the metal in the first reactant may be different from the metal in the second reactant.

[0012] In many cases, the photoresist material deposited on the substrate includes a compositional gradient along the thickness of the photoresist material. In some such cases, the photoresist material includes M2 in addition to M1, where M2 has a high EUV absorption cross section and is a different metal than M1, and the compositional gradient in the photoresist material provides different ratios of M1:M2 at different vertical locations within the photoresist material. In some embodiments, the compositional gradient in the photoresist material may provide different ratios of M1:R1 at different vertical locations within the photoresist material. In some such cases, the percentage of metal atoms bonded to R1 may vary at different vertical locations within the photoresist material. In some embodiments, the compositional gradient in the photoresist material may provide different concentrations of I or Te at different vertical locations within the photoresist material. In various embodiments, the compositional gradient may provide a higher density of high EUV absorbing elements at a bottom of the photoresist material compared to a top of the photoresist material, the bottom being deposited before the top.

[0013] In some embodiments, the method further includes providing a third reactant to the reaction chamber prior to providing the first reactant to the reaction chamber to initiate a reaction between the second reactant and the third reactant or between the third reactant and a fourth reactant, thereby depositing an initial portion of the photoresist material, the third reactant being represented by a compound of formula M2 a L2 cwhere M2 is a metal with a high EUV absorption cross section, L2 is a ligand, ion, or other moiety that reacts with the second or fourth reactant, and a > 1, and c > 1, such that an initial portion of the photoresist material does not incorporate R1. In these or other embodiments, the method may further include repeatedly exposing the substrate to a plasma to remove some of the R1 from the photoresist material, and the conditions used to generate the plasma are varied over time such that there is a gradient in the concentration of M1-R1 bonds in the photoresist material. In some such embodiments, the power used to generate the plasma may be reduced over time such that there is a relatively low concentration of M1-R1 bonds near the bottom of the photoresist material and a relatively high concentration of M1-R1 bonds near the top of the photoresist material. In various implementations, the photoresist material may include a vertical density gradient.

[0014] In some cases, the method may further include exposing a photoresist material to EUV and developing the photoresist material to form a pattern, where developing the photoresist material is performed by wet processing or dry processing. In various embodiments, the photoresist material may provide a depth-dependent EUV sensitivity.

[0015] In another aspect of the disclosed embodiments, a method of depositing a photoresist material on a substrate is provided, the method including providing a substrate in a reaction chamber; and providing a first reactant and a second reactant to the reaction chamber to initiate a reaction between the first reactant and the second reactant, thereby depositing a photoresist material on the substrate, wherein the first reactant and the second reactant are each provided to the reaction chamber in a gas phase, and wherein the photoresist material provides a plurality of patterning radiation absorbing species and / or a depth-dependent sensitivity to the patterning radiation.

[0016] In another aspect of the disclosed embodiments, a photoresist material is provided, the photoresist material being formed by any of the methods claimed or otherwise described herein.

[0017] In another aspect of the disclosed embodiments, an apparatus is provided for depositing a photoresist material on a substrate, the apparatus including a reaction chamber, an inlet for introducing a gas phase reactant, an outlet for removing material from the reaction chamber, a substrate support within the reaction chamber, and a controller having at least one processor configured to cause any of the methods claimed or otherwise described herein.

[0018] These and other aspects are further described below with reference to the drawings. [Brief description of the drawings]

[0019] [Figure 1A] FIG. 1A is a graph illustrating the composition of different representative films at different depths.

[0020] [Figure 1B] FIG. 1B is a graph illustrating the absorption of light at different film depths for different representative films.

[0021] [Figure 1C] FIG. 1C illustrates different resist films with different absorption and transmission properties. [Figure 1D] FIG. 1D illustrates different resist films having different absorption and transmission properties. [Figure 1E] FIG. 1E illustrates different resist films having different absorption and transmission properties.

[0022] [Figure 2A] FIG. 2A illustrates an embodiment in which the resist film is deposited in a compositional gradient, with bismuth and tin near the bottom of the resist and tin near the top of the resist.

[0023] [Figure 2B] FIG. 2B illustrates an embodiment in which the resist film is deposited in a compositional gradient, with tin and tellurium near the bottom of the resist and tin near the top of the resist.

[0024] [Diagram 3] FIG. 3 is a diagram illustrating a reaction chamber that can be used to deposit a resist film according to various embodiments.

[0025] [Figure 4] FIG. 4 is a diagram illustrating a multi-station reaction chamber that can be used to deposit a resist film according to various embodiments.

[0026] [Diagram 5] FIG. 5 illustrates a reaction chamber that can be used for various purposes, such as dry developing and / or etching a resist film, according to various embodiments.

[0027] [Figure 6] FIG. 6 is a diagram illustrating a semiconductor process cluster tool architecture with a vacuum integrated deposition and patterning module suitable for implementing various embodiments herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Reference will now be made in detail to certain embodiments of the present disclosure. Examples of certain embodiments are illustrated in the accompanying drawings. Although the present disclosure will be described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the present disclosure to such specific embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents that may be included within the spirit and scope of the present disclosure. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. The present disclosure may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail in order not to unnecessarily obscure the present disclosure.

[0029] Patterning of thin films in semiconductor processing is often a critical step in semiconductor fabrication. Patterning involves lithography. In traditional photolithography, such as 193 nm photolithography, a pattern is printed by emitting photons from a photon source onto a mask and printing the pattern onto a light-sensitive photoresist, thereby causing a chemical reaction in the photoresist that, after development, removes certain portions of the photoresist to form the pattern. The patterned and developed photoresist film can then be used as an etch mask to transfer the pattern into an underlying film composed of metal, oxide, etc.

[0030] Advanced technology nodes (defined by the International Technology Roadmap for Semiconductors) include the 22 nm, 16 nm, and beyond. For example, at the 16 nm node, the width of a via or line in a damascene structure is typically about 30 nm or less. The scaling of features on advanced semiconductor integrated circuits (ICs) and other devices is driving lithography to improve resolution.

[0031] Extreme ultraviolet (EUV) lithography can extend lithography techniques by moving to shorter imaging light source wavelengths than are achievable with traditional photolithography methods. EUV sources with wavelengths of approximately 10-20 nm, or 11-14 nm, for example 13.5 nm, are available for state-of-the-art lithography tools, also known as scanners. EUV radiation is strongly absorbed by a wide range of solid and fluid materials, including quartz and water vapor, and therefore operates in a vacuum.

[0032] Conventional organic chemically amplified resists (CARs) have several drawbacks when used in EUV lithography, especially the low absorption coefficient in the EUV region and the diffusion of photoactivated species. Thick CAR films are needed to overcome the low absorption coefficient, but with the risk of pattern collapse. Meanwhile, the diffusion of photoactivated species has a negative impact on pattern fidelity, such as linewidth roughness. In addition, poor etch selectivity also necessitates the use of additional underlayers for pattern transfer. Therefore, the lithographic performance of current CARs cannot match the spatial resolution performance of EUV scanners.

[0033] Direct photopatternable EUV resists may contain metals and / or metal oxides mixed within an organic component. These organometallic resists hold great promise in that they can enhance EUV photon absorption, generate secondary electrons, and / or provide enhanced etch selectivity relative to the underlying film stack or device layers.

[0034] Organometallic resists, such as those available from Inpria Corp of Corvallis, Oregon, enjoy a substantially higher absorption coefficient and can be made significantly thinner while providing excellent etch resistance. These films are described, for example, in U.S. Patent Publication Nos. US2017 / 0102612 and US2016 / 0116839, each of which is incorporated herein by reference at least for its disclosure of photopatternable metal oxide-containing films. However, as a spin-on formulation that results in a spatially homogeneous film, the Inpria film suffers from the aforementioned depth-dependent dose concerns, and once the material begins to absorb more than about 30% of the incident EUV photons, there is inevitably less reach to the bottom of the film to induce the chemical effects necessary to enable selective development. Additionally, stability in solution is also cited as a drawback of the Inpria formulation.

[0035] Currently, all commercially available EUV photoresists for high-resolution patterning applications are solution-based (wet) spin-on formulations. Dry deposition of organometallic resists has also been described, for example, in previous International Application No. PCT / US19 / 31618, entitled "METHODS FOR MAKING EUV PATTERNABLE HARD MASKS," filed May 9, 2019, the disclosure of which relating to the composition, deposition, and patterning of direct photopatternable organometallic metal oxide films to form EUV resist masks is incorporated herein by reference. In most or all of these organometallic resists, except for the metal centers (mainly Sn), all other elements have low EUV absorption cross sections. Introducing other highly EUV absorbing elements into the resist, either as metal centers or as part of counter reactants or as replacements for bulky organic groups, may further increase EUV absorption in the PR and thus further reduce the EUV dose required for patterning.

[0036] Additionally, Inpria spin-on films are believed to be homogeneous throughout the film thickness and have a consistent percentage of alkyl-bonded Sn atoms throughout the film. With our dry-deposited films, it is possible to adjust the composition during deposition and create films with vertical compositional gradients. To our knowledge, this has not been achieved with spin-on EUV PR formulations.

[0037] EUV photoresist (PR) materials according to the present disclosure can be formed using organometallic precursors having a metal center selected from among elements with high EUV absorption cross-sections, such as In, Sn, Sb, Bi, and Te. At least one of the precursors must also have one or more bulky organic groups that can withstand chemical reactions but are cleavable under EUV. Although the present disclosure is not limited by any particular theory or mechanism of operation, it is believed that the steric hindrance of the bulky organic groups prevents the formation of a dense network, resulting in a porous film with low density. The counter-reactant must be capable of replacing the original ligands of the metal center during the reaction and forming a cross-linked material. Additionally, the counter-reactant and / or the bulky organic groups can also include additional high EUV absorbing elements, such as I and Te.

[0038] Such PR films can be deposited using gas-phase deposition methods such as CVD and ALD. For some combinations of precursors and counter-reactants, the reaction can also be realized in the solution phase, generating small clusters of active EUV PR material, which can be coated onto a substrate via a spin-coating process. Upon EUV exposure, highly EUV-absorbing elements in the PR absorb the EUV light and generate a large number of secondary electrons. Within their mean free path (typically a few nm), these electrons can induce chemical reactions and break chemical bonds between metal centers and bulky organic groups. The changes that follow such bond scission, such as hydride / hydroxyl formation, crosslinking, changes in surface polarity, film shrinkage, and reduced solubility, create chemical contrasts that can be exploited for development, including both wet and dry development, as well as potential surface imaging / selective deposition strategies.

[0039] Another strategy that could further improve EUV sensitivity in PR films is to create films where the film composition is graded vertically, resulting in depth-dependent EUV sensitivity. Homogeneous PR with a high absorption coefficient would experience a decrease in light intensity throughout the film's depth, requiring a higher EUV dose to ensure the bottom is adequately exposed. By increasing the density of atoms with high EUV absorptance at the bottom of the film compared to the top of the film (i.e., by creating a gradient of increasing EUV absorption), it would be possible to more efficiently utilize the available EUV photons while distributing the absorption (and the effect of secondary electrons) more uniformly towards the more absorbing bottom of the film.

[0040] The strategy of engineering vertical compositional gradients in PR films is particularly applicable to dry deposition methods such as CVD and ALD and can be realized by adjusting the flow ratio between different reactants during deposition. Types of compositional gradients that can be engineered include ratios between different highly absorbing metals, percentages of metal atoms with EUV-cleavable bulky groups (or related, ratios between metal atoms and EUV-cleavable bulky groups), percentages of bulky groups or counter reactants that contain highly absorbing elements (such as Te, and I) (or related, ratios between metal atoms and additional highly absorbing elements such as Te and I), and combinations of the above.

[0041] Compositional gradients in EUV PR films can also provide additional benefits. For example, a high density of high EUV absorbing elements at the bottom of the film can effectively generate more secondary electrons and better expose the top of the film. In addition, such compositional gradients can also directly correlate with a higher proportion of EUV absorbing species that are not attached to bulky terminal substituents. For example, in the case of Sn-based resists, the incorporation of tin precursors with four leaving groups is possible, which promotes the formation of Sn-O-substrate bonds at the interface and improves adhesion.

[0042] Below are described some examples of how to make metal organic resists in accordance with the present disclosure, and some possible technical advantages that may be available.

[0043] Precursor Description In general, the methods described involve flowing an organometallic precursor that contains at least one alkyl group on each metal atom that can survive the vapor deposition reaction, while other ligands or ions coordinated to the metal can be displaced by a counter-reactant. Suitable organometallic precursors include those of the formula: M1 a R1 b L1 c (Formula 1) where M1 is an element with a high patterning radiation absorption cross section (e.g., 1×10 7 cm 2 / mol or more), and R1 is C n H 2n+1 and the like, preferably where n≧3; L1 is a ligand, ion, or other moiety that reacts with a counterreactant; a≧1, b≧1, and c≧1.

[0044] In various embodiments, the patterning radiation is EUV radiation and M1 is a metal with a high EUV radiation absorption cross section. If other types of patterning radiation are used, M1 may have a high absorption cross section with respect to the type of patterning radiation used to develop the photoresist material.

[0045] Additionally, suitable organometallic precursors that do not have alkyl groups, but instead have only ligands or ions that coordinate to the metal atom that can be displaced by a counter reactant, include the following: M2 a L2 c (Formula 2) where M2 is a metal with a high EUV absorption cross section, which may be the same or different from M1, and L2 is a ligand, ion, or other moiety that reacts with a counterreactant, where a > 1 and c > 1. The counterreactant preferably has the ability to displace a ligand or ion of a reactive moiety (e.g., L1 in Formula 1 above, and / or L2 in Formula 2) so as to link at least two metal atoms via a chemical bond.

[0046] In various embodiments, the patterning radiation is EUV radiation and M2 is a metal with a high EUV radiation absorption cross section. If other types of patterning radiation are used, M2 may have a high absorption cross section with respect to the type of patterning radiation used to develop the photoresist material.

[0047] Counter-reactants may include water, peroxides (e.g., hydrogen peroxide), formic acid, alcohols (e.g., di- or polyhydroxy alcohols, fluorinated di- or polyhydroxy alcohols, fluorinated glycols), oxygen, ozone, other sources of hydroxyl sites, and combinations thereof. In various embodiments, the counter-reactant reacts with the organometallic precursor by forming oxygen bridges between adjacent metal atoms. Other potential counter-reactants include hydrogen sulfide and hydrogen disulfide, which can bridge metal atoms through sulfur bridges, and bis(trimethylsilyl)tellurium, which can bridge metal atoms through tellurium bridges. Additionally, hydrogen iodide can be utilized to incorporate iodine into the film.

[0048] In various embodiments, R1 may be fluorinated, e.g., a group of formula C n F x H (2n+1) In various embodiments, R1 has at least one beta hydrogen or beta fluorine. For example, R1 may be selected from the group consisting of i-propyl, n-propyl, t-butyl, i-butyl, n-butyl, sec-butyl, n-pentyl, i-pentyl, t-pentyl, sec-pentyl, and mixtures thereof; Any of these may be fluorinated.

[0049] L1 or L2 can be any moiety that is readily displaced by a counter-reactive agent to generate the corresponding M-OH moiety, such as a moiety selected from the group consisting of amines (dialkylamino, monoalkylamino, etc.), alkoxy, carboxylate, halogen, and mixtures thereof.

[0050] The organometallic precursor can be any of a wide variety of candidate metal-organic precursors. For example, when M1 and / or M2 are tin, such precursors can be t-butyltris(dimethylamino)tin, i-butyltris(dimethylamino)tin, n-butyltris(dimethylamino)tin, sec-butyltris(dimethylamino)tin, i-propyl(tris)dimethylaminotin, n-propyltris(diethylamino)tin, and similar alkyl(tris)(t-butoxy)tin compounds (e.g., t-butyltris(t-butoxy)tin, i-butyltris(t-butoxy)tin, n-butyltris(t-butoxy)tin, sec-butyltris(t-butoxy)tin, i-propyl(tris)t-butoxytin, n-propyltris(t-butoxy)tin, and the like). butoxy) tin, as well as halogen-substituted forms of these materials. In some examples, the organometallic precursor may include t-butyl trichlorotin, i-butyl trichlorotin, n-butyl trichlorotin, sec-butyl trichlorotin, i-propyl trichlorotin, n-propyl trichlorotin, t-butyl tribomostin, i-butyl tribomostin, n-butyl tribomostin, sec-butyl tribomostin, i-propyl tribromostin, n-propyl tribromostin, and the like. In some embodiments, the organometallic precursor is partially fluorinated. In some embodiments, a less reactive / more controllable leaving group, such as t-butoxy, is advantageously used.

[0051] Further description of precursors and methods for their deposition as EUV photoresist films applicable to the present disclosure can be found in International Application No. PCT / US19 / 31618. In addition to the organometallic precursors and counter-reactants, the thin films may include optional materials to modify the chemical or physical properties of the film, such as modifying the film's sensitivity to EUV or enhancing etch resistance. Such optional materials can be introduced, for example, by doping during vapor phase formation prior to deposition on the substrate, after deposition of the film, or both. In some embodiments, a mild remote H2 plasma can be introduced to replace some M1-L and / or M2-L bonds (e.g., Sn-L bonds) with M1-H and / or M2-H bonds (e.g., Sn-H bonds), for example, to enhance the reactivity of the resist under EUV.

[0052] In various embodiments, the EUV patternable film is made and deposited on the substrate using vapor deposition equipment and processes among those known in the art. In such processes, polymerized organometallic materials are formed in the vapor phase or in situ on the surface of the substrate. Suitable processes include, for example, chemical vapor deposition (CVD), atomic layer deposition (ALD), and ALD with a CVD component, such as discontinuous ALD-like processes in which the metal precursor and counter-reactant are separated in either time or space. The reaction can be driven by thermal or plasma energy.

[0053] In general, the method involves mixing a vapor flow of an organometallic precursor with a vapor flow of a counter-reactant to form a polymerized organometallic material and depositing the organometallic material onto a surface of a semiconductor substrate. As will be appreciated by those skilled in the art, the mixing and deposition aspects of the process can be simultaneous in a substantially continuous process.

[0054] In an exemplary sequential CVD process, two or more gas streams in separate inlet paths for sources of organometallic precursor and counter-reactant are introduced into a deposition chamber of a CVD apparatus where they mix and react in the gas phase to form an aggregated polymeric material (e.g., via the formation of metal-oxygen-metal bonds). The streams can be introduced, for example, using separate inlets or a dual plenum showerhead. The apparatus is configured such that the flows of organometallic precursor and counter-reactant mix in the chamber, allowing the organometallic precursor and counter-reactant to react and form a polymerized organometallic material. Without limiting the mechanism, function, or utility of the present technology, it is believed that the products from such gas phase reactions are heavier in molecular weight because the metal atoms are cross-linked by the counter-reactant and then condensed or deposited on a substrate. In various embodiments, the steric hindrance of the bulky alkyl groups prevents the formation of a dense network, resulting in a low density porous film. In various cases, the low density film has a density of about 2-2.5 g / cm3.

[0055] CAV processes are typically carried out at reduced pressures, such as between 10 milliTorr and 10 Torr. In some embodiments, the process is carried out at 0.5 to 2 Torr. The temperature of the substrate is preferably equal to or lower than the temperature of the reactant stream. For example, the substrate temperature can be between 0° C. and 250° C., or between ambient temperature (e.g., 23° C.) and 150° C. In the various processes, deposition of polymerized metal-organic material onto the substrate occurs at a rate that is inversely proportional to the surface temperature.

[0056] In the remainder of this description, the organotin site will be used as the primary example of an EUV reactive site to which other Sn as well as non-Sn precursors can be added to modify the EUV absorption properties. Consistent with this disclosure, other organometallic species can be used.

[0057] A potential advantage of using dry deposition techniques is the ease of adjusting the composition of the film as it grows. In a CVD process, this can be accomplished by altering the relative flows of two or more metal-containing precursors during deposition. Deposition can be carried out at 30-200 °C at pressures between 0.01-100 Torr, more commonly about 0.1 Torr-10 Torr.

[0058] In ALD processes, this can be accomplished by changing the relative ratio of cycles of one precursor to another. For example, initially the process may be 5x[dose precursor A-purge-dose counter reactant-purge]+1x[dose precursor B-purge-dose counter reactant-purge] resulting in an A-heavy film, but later in the film growth the cycle may change to 1x[dose precursor A-purge-dose counter reactant-purge]+5x[dose precursor B-purge-dose counter reactant-purge] resulting in a B-heavy film. Deposition may be performed at 30-300°C at pressures of 0.01-10 Torr. ALD processes may have incomplete purges between precursor and counter reactant pulses, thus adding CVD components to the growth.

[0059] Dry deposition of gradient films by ALD / CVD method (non-plasma) One exemplary system for producing graded Sn-based resists with various alkyl groups involves using tetrakis(dimethylamino)tin and isopropyltris(dimethylamino)tin precursors and water as counter reactants. Tetrakis(dimethylamino)tin is introduced initially as a small to significant component, generating a relatively high density component of Sn not bonded to alkyl groups (essentially SnO2 and Sn-OH derivatives). The ratio of tetrakis(dimethylamino)tin:isopropyltris(dimethylamino)tin precursors decreases as the film grows. This results in a film with an increased amount of Sn-R bonds in the film toward the top surface of the film. (An example of increased absorption of a film obtained by this process is described below). This process can be carried out by either ALD or CVD methods.

[0060] Another example is the addition of different metals to the system to enhance absorption. For example, as shown in Figure 2A, a gradient film with bismuth and tin metal centers can be synthesized using isopropyltris(dimethylamino)tin and tris(dimethylamino)bismuth. The ratio of tris(dimethylamino)bismuth:isopropyltris(dimethylamino)tin in the precursor flow is decreased as the film is deposited. This results in the bottom of the film containing more bismuth metal centers than the top of the film. Like Sn, Bi atoms exhibit very high EUV cross sections, but unlike Sn, they appear to have a low tendency to condense into refractory binary metal oxides, even without bulky EUV-labile substituents. Thus, processes using tris(dimethylamino)bismuth may be substantially superior in some situations or applications to processes based on tetrakis(dimethylamino)tin due to their expected substantially lower adverse effects on both wet (aqueous and non-aqueous) and dry (e.g., HCl or HBr-based as described in U.S. Application No. 62 / 866,942, filed June 26, 2019, which is incorporated by reference herein for purposes of describing applicable dry development techniques) development strategies.

[0061] A related approach involving an absorption gradient involves the use of some tin-based resist films using two precursors, both with alkyl groups, but one containing one or more alkyl ligands than the other. For example, isopropyltris(dimethylamino)tin and diisopropyldi(dimethylamino)tin can be used. First, a flow of diisopropyldi(dimethylamino)tin is introduced during deposition of the film, and as the film is deposited, the ratio is increased relative to the flow of isopropyltris(dimethylamino)tin. This results in a film with a higher amount of Sn attached to the two alkyl groups on the surface compared to the bottom of the film.

[0062] Yet another strategy involves the introduction of alternative (or additional) co-reactants to the water to introduce elements with a much higher EUV absorption coefficient than oxygen. One example is the incorporation of tellurium, as shown in FIG. 2B. Bis(trimethyl)tellurium offers a viable option as a gas-phase co-reactant. In some embodiments, it can be combined with an alkyltin precursor, such as tris(t-butoxy)isopropyltin and water. In this way, thin films that absorb more than 80% of the EUV radiation can be obtained with little reduction in reactive Sn-alkyl sites near the bottom of the film. As shown in FIG. 2B, during the first part of the deposition, the co-reactants include both water and bis(trimethyl)tellurium. The initial film formed on the underlying substrate has a significant amount of both tin and tellurium. As the deposition proceeds, the ratio of bis(trimethyl)tellurium:tris(t-butoxy)isopropyltin decreases, thereby forming a film with relatively less tellurium and relatively more tin compared to the first part of the film. In various embodiments, the film may transition to a tellurium-free composition near the top surface of the film to help minimize, for example, contamination and handling issues.

[0063] A similar strategy (also using tris(t-butoxy)isopropyltin and water as the base chemical) can be used to gradient introduce iodine using low concentrations of HI (or an appropriate alkyl iodide) together with water to achieve gradient doping of iodine near the interface.

[0064] Although this section refers to non-plasma methods for dry deposition of gradient films, it is understood that either strategy can be applied to plasma-based deposition methods as well.

[0065] Dry deposition of gradient films by ALD / CVD (plasma): Another method of creating a graded film involves using a plasma to remove some of the alkyl groups that were attached to the metal center during the initial deposition of the film. For example, Sn-alkyl bonds are easily broken in the presence of a plasma by electron or ion bombardment from VUV or a plasma. Ideally, a plasma is used that simply removes the alkyl groups but does not etch the film. For example, O2, Ar, He, or CO2 plasmas can be used. As the film is deposited, the efficiency of the plasma to remove the alkyl groups decreases (i.e., the power of the plasma is reduced) and is eventually turned off. This results in a graded film with more M-alkyl bonds at the surface of the film than at the bottom of the film.

[0066] Patterning exposure Following deposition and optional post-application bake, the gradient film is exposed. EUV, 193 nm, or electron beam can be used to expose the film. In many embodiments, EUV is used. It should also be understood that the present disclosure relates to lithographic patterning techniques and materials exemplified by EUV lithography, but is also applicable to other next generation lithography techniques. In addition to EUV, which includes the standard 13.5 nm EUV wavelength currently in use and being developed, the most relevant radiation source for such lithography is DUV (deep-UV), which generally refers to the use of 248 nm or 193 nm excimer laser sources, X-rays (formally including EUV in the lower energy range of the X-ray range), and e-beams that can cover a wide energy range. The particular method may depend on the particular materials and applications used in the semiconductor substrate and the final semiconductor device. Thus, the methods described in this application are merely exemplary of methods and materials that may be used in the present technology.

[0067] A possible advantage of gradient films is higher EUV absorption. An example is a graded Sn-based film with a higher density of Sn-alkyl bonds at the surface than at the bottom. Based on the density, EUV cross-sections of the constituent elements, and stoichiometry, it can be easily calculated that SnO2 has a higher linear absorption coefficient than the CVD organotin oxide films described herein and in International Application No. PCT / US19 / 3161, i.e., SnO2 absorbs more EUV photons for a given volume than the CVD organotin oxide films. The absorption of EUV photons can be calculated by the Beer-Lambert law. Figure 1A illustrates the composition versus film depth for various representative films. Figure 1B illustrates the absorption versus film depth for these same representative films, with the estimate being based on the Beer-Lambert law.

[0068] It may be advantageous to capture more of the incident EUV light that strikes the wafer to create contrast between exposed and unexposed areas. A sufficient thickness of resist must be used so that the pattern can then be transferred to subsequent layers. In general, if the resist is compositionally homogeneous, about 70% transmission of light to the bottom of the resist should occur. However, more absorption and less transmission may be appropriate if the resist has a graded composition, as the graded composition can counteract non-uniformities in absorption behavior that sometimes occur with homogeneous resist compositions.

[0069] For the exemplary Sn case, it may be advantageous to incorporate areas with higher absorption near the bottom of the film, especially near the underlying substrate. These regions will absorb more EUV light and generate more secondary electrons that can expose adjacent regions (e.g., the radius of the CVD organotin oxide films described herein is about 1 nm). One possible method is to include regions with fewer Sn-alkyl bonds, effectively more SnO2-like material, toward the bottom of the film and more Sn-alkyl bonds toward the top of the film.

[0070] Some examples of different composition gradients are shown in FIG. 1A and the corresponding absorption is shown in FIG. 1B. Additionally, FIGS. 1C-1E illustrate different EUV photoresists and the resulting absorption / transmission they provide. In these figures, an EUV photoresist 121 is positioned on an underlying substrate 120. EUV radiation 122 illuminates the EUV photoresist 121, and different amounts of the EUV radiation 122 are absorbed by the EUV photoresist 121, resulting in different amounts of EUV radiation being transmitted through the EUV photoresist 121 onto the underlying substrate 120. The photoresist 121 in FIG. 1C is a homogenous organotin oxide photoresist with a relatively low EUV absorption of 30%, a transmittance of 70%. The photoresist 121 in FIG. 1D is a homogenous film with a relatively high EUV absorption of 90%, a transmittance of 10% (this photoresist is generally ineffective for patterning applications because the EUV absorption and resulting chemistry are weighted toward the top of the photoresist). The photoresist 121 of FIG. 1E is a graded tin-based EUV photoresist with a compositional gradient that provides an overall 60% EUV absorption at 40% transmission. The increasing EUV absorption gradient provided by the compositional gradient of FIG. 1E results in a more uniform absorption throughout the thickness of the photoresist 121. As can be readily seen, the inclusion of regions with higher SnO2-like properties increases EUV absorption within the film. All of the examples given have increasing Sn-alkyl content towards the surface of the film, although the concept of having laminate layers with alternating heavy Sn-alkyl and light Sn-alkyl regions is also envisioned.

[0071] Development Strategy Following exposure and optional baking, the film is developed. The film can be either wet or dry developed. The film and chemistry selected can be designed such that the unexposed film can be selectively removed over the exposed film.

[0072] Dry development processes suitable for organotin oxide-based EUV photoresist compositions have been demonstrated, applicable to both commercially available spin-coatable formulations (e.g., from Inpria Corp) and formulations applied using the dry vacuum deposition techniques referenced above. Negative tone dry development has been achieved by selectively dry developing (removing) non-EUV exposed areas exposed to a flow containing hydrogen halide or hydrogen and halides (including HCl and / or HBr not bombarded with plasma), or a flow of H2 and Cl2 and / or Br2, with a remote plasma or UV radiation generated from the plasma to generate radicals. An example process for dry development includes an organotin oxide-containing EUV sensitive photoresist film (e.g., 10-40 nm thick, sometimes 10-20 nm thick, e.g., 15 nm thick), which is subjected to an EUV exposure dose, followed by a post-exposure bake, and then dry developed. Process conditions for dry development are, for example, as follows: reactant flow 100-500 sccm (e.g., 500 sccm HBr or HCl), temperature -10-120 °C (e.g., -10 °C), pressure 20-500 mT (e.g., 300 mT), no plasma, about 10-500 seconds, sometimes about 10 seconds to 1 minute, depending on the photoresist film and composition and properties. If the hydrogen halide reactant flow is hydrogen gas and halide gas, remote plasma / UV radiation is used to generate radicals from H2 and Cl2 and / or Br2, and the hydrogen radicals and halide radicals are flowed into the reaction chamber and contacted with the patterned EUV photoresist on the substrate layer of the wafer. Suitable plasma power can be in the range of 100-500 W without bias. These conditions are suitable for some processing reactors, e.g., Kiyo etch tools available from Lam Research Corporation, Fremont, Calif., but it should be understood that a wider range of process conditions may be used depending on the capabilities of the processing reactor.

[0073] Another potential advantage of gradient films is evident in development. As previously explained, when EUV light passes through the resist, some of the light is absorbed. This means that the bottom of the resist is exposed to less light than the top of the resist. By using gradient films, it may be possible to more uniformly distribute the number of EUV photons absorbed throughout the thickness of the resist while maintaining sufficient EUV-induced reactivity necessary for selective development. For example, in the case of isopropyltris(dimethylamino)tin and tetrakis(dimethylamino)tin, deposition regions with a relatively high ratio of tetrakis(dimethylamino)tin:isopropyltris(dimethylamino)tin may have a lower percentage of Sn-alkyl bonds and more Sn-O-Sn bonds compared to deposition regions with a relatively low ratio of tetrakis(dimethylamino)tin:isopropyltris(dimethylamino)tin. Thus, if more tetrakis(dimethylamino)tin amount is first shed during deposition (and then reduced during deposition), the bottom of the film may be crosslinked more effectively than the top of the film.

[0074] conclusion The introduction of high EUV absorbing elements allows the photoresist material to absorb more EUV photons and emit more secondary electrons compared to traditional metal oxide photoresists such as Inpria, lowering the dose requirements and therefore the cost of EUV lithography. Such films can potentially be deposited using both wet spin-coat and dry CVD / ALD techniques.

[0075] Graded films may offer the advantage of reducing the EUV dose required for film exposure over homogeneous films. Dry deposition of these films offers more opportunities to tailor the composition of the resist throughout the film thickness over spin-coated films.

[0076] Device FIG. 3 illustrates a schematic diagram of one embodiment of a process station 300 having a process chamber body 302 for maintaining a low pressure environment suitable for carrying out the dry deposition and development embodiments described herein. Multiple process stations 300 may be included in a common low pressure process tool environment. For example, FIG. 4 illustrates one embodiment of a multi-station processing tool 400, such as a VECTOR® processing tool available from Lam Research Corporation of Fremont, Calif. In some embodiments, one or more hardware parameters of the process stations 300 (including those described in detail below) may be programmatically adjusted by one or more computer controllers 350.

[0077] The process stations can be configured as modules within a cluster tool. Figure 6 illustrates a semiconductor process cluster tool architecture with a vacuum integrated deposition and patterning module suitable for implementing the embodiments described herein. Such a cluster process tool architecture can include resist deposition, resist exposure (EUV scanner), resist dry development, and etching modules, as described above and further below with reference to Figures 5 and 6.

[0078] In some embodiments, certain processing functions, such as dry developing and etching, can be performed sequentially in the same module. Thus, embodiments of the present disclosure are directed to methods and apparatus for receiving a wafer including a photo-patterned EUV resist thin film layer disposed on a layer or layer stack to be etched, following photo-patterning in an EUV scanner, into a dry developing / etching chamber to dry develop the photo-patterned EUV resist thin film layer, and then etching the underlying layer using the patterned EUV resist as a mask, as described herein.

[0079] Returning to FIG. 3, the process station 300 is in fluid communication with a reactant delivery system 301a for delivering process gases to a distribution showerhead 306. The reactant delivery system 301a optionally includes a mixing vessel 304 for blending and / or conditioning the process gases delivered to the showerhead 306. One or more mixing vessel inlet valves 320 can control the introduction of process gases to the mixing vessel 304. In various embodiments, the mixing vessel 304 may be omitted and the reactant delivery system 301a may be configured to deliver each of the reactants separately to the process station 300 so that they do not mix before reaching the process station 300. If plasma exposure is used, the plasma may also be delivered to the showerhead 306 or generated at the process station 300. As noted above, in at least some embodiments, non-plasma thermal exposure is preferred.

[0080] 3 includes an optional vaporization point 303 for vaporizing the liquid reactant provided to the mixing vessel 304. In some embodiments, a liquid flow controller (LFC) can be provided upstream of the vaporization point 303 to control the mass flow rate of the liquid that is vaporized and delivered to the process station 300. For example, the LFC can include a thermal mass flow meter (MFM) located downstream of the LFC. A plunger valve of the LFC can then be adjusted in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM.

[0081] The showerhead 306 distributes process gases toward the substrate 312. In the embodiment illustrated in Figure 3, the substrate 312 is shown positioned below the showerhead 306 and resting on a pedestal 308. The showerhead 306 can have any suitable shape and can have any suitable number and arrangement of ports for distributing process gases to the substrate 312.

[0082] In some embodiments, the pedestal 308 can be raised or lowered to expose the substrate 312 to the volume between the substrate 312 and the showerhead 306. It will be appreciated that in some embodiments, the height of the pedestal can be programmatically adjusted by a suitable computer controller 350.

[0083] In some embodiments, the pedestal 308 may be temperature controlled via heater 310. In some embodiments, the pedestal 308 may be heated to a temperature above 0° C. to 300° C. or higher, such as 50-120° C., such as about 65-80° C., during non-plasma thermal exposure of the photo-patterned resist to a hydrogen halide dry developing chemistry, such as HBr or HCl, as described in the disclosed embodiments.

[0084] Additionally, in some embodiments, pressure control for the process station 300 may be provided by a butterfly valve 318. As shown in the embodiment of Figure 3, the butterfly valve 318 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control for the process station 300 may also be adjusted by varying the flow rate of one or more gases introduced to the process station 300.

[0085] In some embodiments, the position of the showerhead 306 can be adjusted relative to the pedestal 308 to change the volume between the substrate 312 and the showerhead 306. Further, it will be understood that the vertical position of the pedestal 308 and / or the showerhead 306 may be altered by any suitable mechanism within the scope of the present disclosure. In some embodiments, the pedestal 308 may include a rotational axis for rotating the orientation of the substrate 312. It will be understood that in some embodiments, one or more of these exemplary adjustments can be implemented programmatically by one or more suitable computer controllers 350.

[0086] Where a plasma may be used, for example in mild plasma-based dry development embodiments and / or etching operations performed in the same chamber, the showerhead 306 and pedestal 308 are in electrical communication with a radio frequency (RF) power source 314 and matching network 316 to power the plasma. In some embodiments, the plasma energy can be controlled by controlling one or more of the process station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, the RF power source 314 and matching network 316 can be operated at any suitable power to form a plasma having a desired composition of radical species. An example of a suitable power is up to about 500W.

[0087] In some embodiments, instructions for the controller 350 may be provided via input / output control (IOC) sequence instructions. In one example, instructions for setting conditions for a process step may be included in a corresponding recipe step of a process recipe. In some cases, a process recipe step may be arranged in sequence such that all instructions for a process step are executed simultaneously with that process step. In some embodiments, instructions for setting one or more reactor parameters may be included in a recipe step. For example, a recipe step may include instructions for setting a flow rate of a dry development chemical reactant gas, such as HBr or HCl, and a time delay instruction for the recipe step. In some embodiments, the controller 350 may include any of the features described below with respect to the system controller 450 of FIG. 4.

[0088] As mentioned above, one or more process stations may be included in a multi-station processing tool. FIG. 4 shows a schematic diagram of an embodiment of a multi-station processing tool 400 with an inbound load lock 402 and an outbound load lock 404, either or both of which may include a remote plasma source. A robot 406 is configured to move a wafer from a cassette loaded via a pod 408 at atmospheric pressure to the inbound load lock 402 via an atmospheric pressure port 410. The wafer is placed by the robot 406 on a pedestal 412 of the inbound load lock 402, the atmospheric pressure port 410 is closed, and the load lock is pumped down. If the inbound load lock 402 includes a remote plasma source, the wafer may be subjected to a remote plasma treatment to treat the silicon nitride surface in the load lock before being introduced to the processing chamber 414. Additionally, the wafer may also be heated in the inbound load lock 402 to remove, for example, moisture and absorbed gases. The chamber transfer port 416 to the processing chamber 414 is then opened and another robot (not shown) moves the wafer into the reactor and places it on the pedestal of the first station shown in the reactor for processing. Although the embodiment shown in Figure 4 includes a load lock, it will be understood that in some embodiments the wafer may enter the process station directly.

[0089] The illustrated processing chamber 414 includes four process stations, numbered 1 through 4 in the embodiment shown in FIG. 4. Each station has a heated pedestal (shown at 418 for station 1) and a gas line inlet. It will be understood that in some embodiments, each process station may have a different purpose or multiple purposes. For example, in some embodiments, the process stations may be switchable between a dry development mode and an etch process mode. Additionally or alternatively, in some embodiments, the processing chamber 414 may include one or more matched pairs of dry development and etch process stations. Also, in some embodiments, to deposit an EUV resist film having a vertically graded composition, the multi-station processing tool may be configured to deposit a series (e.g., four) of consecutive homogeneous stepped absorbing layers, thereby increasing the density of atoms with high EUV absorption at the bottom of the film compared to the top of the film. Although the illustrated processing chamber 414 includes four stations, it will be understood that a processing chamber according to the present disclosure may have any suitable number of stations. For example, in some embodiments, a processing chamber may have five or more stations, while in other embodiments, a processing chamber may have three or fewer stations.

[0090] FIG. 4 illustrates one embodiment of a wafer handling system 490 for transporting wafers within the processing chamber 414. In some embodiments, the wafer handling system 490 can transport wafers between various process stations and / or between process stations and load locks. It will be understood that any suitable wafer handling system may be used. Non-limiting examples include a wafer carousel and a wafer handling robot. FIG. 4 also illustrates one embodiment of a system controller 450 used to control the process conditions and hardware states of the process tool 400. The system controller 450 can include one or more memory devices 456, one or more mass storage devices 454, and one or more processors 452. The processor 452 can include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc.

[0091] In some embodiments, the system controller 450 controls all of the activity of the process tool 400. The system controller 450 executes system control software 458 that is stored in the mass storage device 454, loaded into the memory device 456, and executed by the processor 452. Alternatively, the control logic may be hard-coded into the controller 450. For these purposes, application specific integrated circuits, programmable logic devices (e.g., field programmable gate arrays, or FPGAs), and the like may be used. In the following description, wherever "software" or "code" is used, functionally equivalent hard-coded logic may be used instead. The system control software 458 may include instructions for controlling the timing, mixture of gases, gas flow rates, chamber and / or station pressures, chamber and / or station temperatures, wafer temperatures, target power levels, RF power levels, substrate pedestal, chuck and / or susceptor positions, and other parameters of a particular process performed by the process tool 400. The system control software 458 may be configured in any suitable manner. For example, various process tool component subroutines or control objects may be written to control the operation of the process tool components used to perform the various process tool processes. The system control software 458 may be coded in any suitable computer readable programming language.

[0092] In some embodiments, the system control software 458 may include input / output control (IOC) sequence instructions for controlling the various parameters described above. In some embodiments, other computer software and / or programs stored on the mass storage device 454 and / or memory device 456 associated with the system controller 450 may be used. Examples of programs or sections of programs for this purpose include a substrate positioning program, a process gas control program, a pressure control program, a heater control program, and a plasma control program.

[0093] The substrate positioning program may include program code for process tool components used to load the substrate onto the pedestal 418 and control the spacing between the substrate and other parts of the process tool 400 .

[0094] The process gas control program may include code for controlling hydrogen halide gas composition (e.g., HBr or HCl gas as described herein) and flow rates to stabilize the pressure of the process station, and optionally, code for flowing gas to one or more process stations prior to deposition. The pressure control program may include code for controlling the pressure of the process station, for example, by adjusting a throttle valve in the exhaust system of the process station, gas flow to the process station, etc.

[0095] The heater control program may include code for controlling the current to a heating unit used to heat the substrate, or the heater control program may control the delivery of a heat transfer gas (such as helium) to the substrate.

[0096] The plasma control program may include code for setting RF power levels applied to process electrodes of one or more process stations according to embodiments herein.

[0097] The pressure control program can include code for maintaining pressure in a reaction chamber according to embodiments herein.

[0098] In some embodiments, there may be a user interface associated with the system controller 450. The user interface may include a display screen, a graphical software display of equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0099] In some embodiments, the parameters adjusted by the system controller 450 may relate to process conditions. Non-limiting examples include process gas composition and flow rates, temperature, pressure, plasma conditions (such as RF bias power levels), etc. These parameters may be provided to a user in the form of a recipe and may be entered using a user interface.

[0100] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 450 from various process tool sensors. Signals for controlling the process can be output at analog and digital output connections of the process tool 400. Non-limiting examples of process tool sensors that can be monitored include mass flow controllers, pressure sensors (such as pressure gauges), thermocouples, etc. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain process conditions.

[0101] The system controller 450 can provide program instructions for carrying out the deposition processes described above. The program instructions can control various process parameters such as DC power levels, RF bias power levels, pressure, temperature, etc. The instructions can control parameters for operating dry development and / or etching processes according to various embodiments described herein.

[0102] System controller 450 typically includes one or more memory devices and one or more processors configured to execute instructions such that the apparatus performs methods according to the disclosed embodiments. Machine-readable media containing instructions for controlling process operations according to the disclosed embodiments may be coupled to system controller 450.

[0103] In some implementations, the system controller 450 is part of a system, such as may be part of the examples described above. Such systems may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling system operations before, during, and after processing of a semiconductor wafer or substrate. Such electronics may be referred to as a "controller" and may control various components or subparts of one or more systems. The system controller 450 may be programmed to control any of the processes disclosed herein depending on the processing conditions and / or type of system. Such processes may include delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow settings, fluid delivery settings, position and motion settings, wafer loading and unloading from the tool, and wafer loading and unloading from other transport tools and / or load locks connected or interfaced with the particular system.

[0104] Broadly, the system controller 450 may be defined as electronic equipment having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, i.e., microcontrollers that execute program instructions (e.g., software). The program instructions may be instructions communicated to the system controller 450 in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. The operational parameters may, in some embodiments, be part of a recipe defined by a process engineer to accomplish one or more processing steps in the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0105] The system controller 450 may, in some embodiments, be part of, or coupled to, a computer that is integrated or coupled with the system or otherwise networked to the system, or a combination thereof. For example, the system controller 450 may be in the "cloud" or all or part of a fab host computer system. This allows for remote access of wafer processing. The computer may allow remote access to the system to monitor the current progress of a fabrication operation, review the history of past fabrication operations, review trends or performance criteria from multiple fabrication operations, modify parameters of a current process, set processing steps following a current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network. Such a network may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the system controller 450 receives instructions in the form of data. Such data identifies parameters for each processing step performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool that the system controller 450 is configured to interface with or control. Thus, as described above, the system controller 450 may be distributed, for example, by including one or more individual controllers that are networked together and cooperate toward a common purpose (such as the processes and controls described herein).An example of a distributed controller for such purposes would include one or more integrated circuits on the chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer) and coupled to control the process in the chamber.

[0106] Exemplary systems may include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a tracking chamber or module, an EUV lithography chamber (scanner) or module, a dry development chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0107] As described above, depending on the process step or steps being performed by the tool, the system controller 450 may communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used for material transport to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0108] In a particular embodiment, an inductively coupled plasma (ICP) reactor that may be suitable for etching operations suitable for practicing some embodiments is now described. Although an ICP reactor is described herein, it should be understood that in some embodiments, a capacitively coupled plasma reactor may also be used.

[0109] 5 illustrates generally a cross-sectional view of an inductively coupled plasma apparatus 500 suitable for carrying out certain embodiments or aspects of the embodiments such as dry development and / or etching, an example of which is the Kiyo® reactor manufactured by Lam Research Corporation of Fremont, Calif. In other embodiments, other tools or tool types having the functionality to carry out the dry development and / or etching processes described herein may be used for carrying out the processes.

[0110] The inductively coupled plasma apparatus 500 includes an overall process chamber 524 structurally defined by a chamber wall 501 and a window 511. The chamber wall 501 can be fabricated from stainless steel or aluminum. The window 511 can be fabricated from quartz or other dielectric materials. An optional internal plasma grid 550 divides the overall process chamber into an upper subchamber 502 and a lower subchamber 503. In most embodiments, the plasma grid 550 can be removed, thereby utilizing the chamber space consisting of the subchambers 502 and 503. A chuck 517 is positioned within the lower subchamber 503 near the bottom inner surface. The chuck 517 is configured to receive and hold a semiconductor wafer 519 on which the etching and deposition processes are performed. The chuck 517, if present, can be an electrostatic chuck for supporting the wafer 519. In some embodiments, an edge ring (not shown) surrounds the chuck 517 and, if present on the chuck 517, has an upper surface that is approximately planar with an upper surface of the wafer 519. The chuck 517 also includes an electrostatic electrode for chucking and dechucking the wafer 519. For this purpose, a filter and DC clamp power supply (not shown) may be provided. Other control systems for lifting the wafer 519 from the chuck 517 may also be provided. The chuck 517 may be charged using an RF power supply 523. The RF power supply 523 is connected to a matching circuit 521 through a connection 527. The matching circuit 521 is connected to the chuck 517 through a connection 525. In this manner, the RF power supply 523 is connected to the chuck 517. In various embodiments, the bias power of the electrostatic chuck may be set to about 50V or may be set to a different bias power depending on the process to be performed according to the disclosed embodiments. For example, the bias power may be about 20Vb to about 100V, or about 30V to about 150V.

[0111] The elements for plasma generation include a coil 533 positioned over the window 511. In some embodiments, a coil is not used in the disclosed embodiments. The coil 533 is fabricated from a conductive material and includes at least one complete turn. The example coil 533 shown in FIG. 5 includes three turns. A cross section of the coil 533 is symbolically shown with the coil having an "X" rotating into the page while the coil having a "●" rotating out of the page. The elements for plasma generation also include an RF power source 541 configured to provide RF power to the coil 533. Generally, the RF power source 541 is connected to a matching circuit 539 through a connection 545. The matching circuit 539 is connected to the coil 533 through a connection 543. In this manner, the RF power source 541 is connected to the coil 533. An optional Faraday shield 549a is positioned between the coil 533 and the window 511. The Faraday shield 549a may be maintained in a spaced apart relationship relative to the coil 533. In some embodiments, the Faraday shield 549a is disposed directly above the window 511. In some embodiments, the Faraday shield 549b is between the window 511 and the chuck 517. In some embodiments, the Faraday shield 549b is not maintained in a spaced apart relationship to the coil 533. For example, the Faraday shield 549b can be directly below the window 511 without a gap. The coil 533, the Faraday shield 549a, and the window 511 are each configured to be substantially parallel to one another. The Faraday shield 549a can prevent metals or other species from depositing on the window 511 of the process chamber 524.

[0112] Process gases may be flowed into the process chamber through one or more main gas inlets 560 positioned in the upper subchamber 502 and / or through one or more side gas inlets 570. Similarly, although not explicitly shown, similar gas inlets may be used to supply process gases to the capacitively coupled plasma processing chamber. A vacuum pump, e.g., a one or two stage mechanical dry pump and / or turbomolecular pump 540, may be used to draw process gases from the process chamber 524 and maintain pressure within the process chamber 524. For example, the vacuum pump may be used to evacuate the lower subchamber 503 during an ALD purge operation. A valve controlled conduit may be used to fluidly connect the vacuum pump to the process chamber 524 to selectively control application of the vacuum environment provided by the vacuum pump. This may be done using a closed loop controlled flow restriction device, such as a throttle valve (not shown) or a pendulum valve (not shown), during plasma processing operations. Similarly, a vacuum pump and a valve controlled fluid connection to the capacitively coupled plasma processing chamber may also be used.

[0113] During operation of the apparatus 500, one or more process gases may be supplied through the gas inlets 560 and / or 570. In certain embodiments, the process gases may be supplied only through the main gas inlet 560 or only through the side gas inlet 570. In some cases, the gas inlets shown in the figure may be replaced with more complex gas inlets, such as one or more showerheads. The Faraday shield 549a and / or the optional grid 550 may include internal channels and holes that allow delivery of process gases to the process chamber 524. Either or both of the Faraday shield 549a and the optional grid 550 may function as showerheads for delivering process gases. In some embodiments, a liquid vaporization and delivery system may be located upstream of the process chamber 524 such that once the liquid reactants or precursors are vaporized, the vaporized reactants or precursors are introduced into the process chamber 524 via the gas inlets 560 and / or 570.

[0114] Radio frequency power is supplied from RF power supply 541 to coil 533, causing an RF current to flow through coil 533. The RF current flowing through coil 533 generates an electromagnetic field around coil 533. The electromagnetic field generates an induced current in the upper subchamber 502. Physical and chemical interactions of the various generated ions and radicals with the wafer 519 etch features on the wafer 519 and selectively deposit layers on the wafer 519.

[0115] When a plasma grid 550 is used such that both an upper subchamber 502 and a lower subchamber 503 are present, induced currents act on the gas present in the upper subchamber 502 to generate an electron-ion plasma in the upper subchamber 502. The optional internal plasma grid 550 limits the amount of hot electrons in the lower subchamber 503. In some embodiments, the apparatus 500 is designed and operated such that the plasma present in the lower subchamber 503 is an ion-ion plasma.

[0116] Both the upper electron-ion plasma and the lower ion-ion plasma may contain positive and negative ions, but the ion-ion plasma has a greater ratio of negative ions to positive ions. Volatile etch and / or deposition byproducts may be removed from the lower subchamber 503 through port 522. The chuck 517 disclosed herein can operate at elevated temperatures ranging from about 10° C. to about 250° C. The temperature will vary depending on the process operation and the particular recipe.

[0117] The apparatus 500 may be coupled to equipment (not shown) when installed in a clean room or fabrication facility. The equipment includes plumbing to provide process gases, vacuum, temperature control, and environmental particle control. These equipment will be coupled to the apparatus 500 when installed in the intended fabrication facility. Additionally, the apparatus 500 may be coupled to a transfer chamber that allows a robot to move semiconductor wafers in and out of the apparatus 500 using typical automated operations.

[0118] In some embodiments, a system controller 530 (which may include one or more physical or logical controllers) controls some or all of the operations of the process chamber 524. The system controller 530 may include one or more memory devices and one or more processors. In some embodiments, the apparatus 500 includes a switching system for controlling flow rates and durations when the disclosed embodiments are implemented. In some embodiments, the apparatus 500 may have a switching time of up to about 500 ms, or up to about 750 ms. The switching time may vary depending on the flow chemistry, the selected recipe, the reactor architecture, and other factors.

[0119] In some implementations, the system controller 530 is part of a system, such a system may be part of the examples described above. Such a system may include semiconductor processing equipment including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestal, gas flow system, etc.). These systems may be integrated with electronics for controlling system operations before, during, and after processing of a semiconductor wafer or substrate. Such electronics may be integrated into the system controller 530 and may control various components or subparts of one or more systems. The system controller may be programmed to control any of the processes disclosed herein depending on the processing parameters and / or type of system. Such processes may include delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and motion settings, wafer loading and unloading from the tool, and wafer loading and unloading from other transport tools and / or load locks connected or interlocked with the particular system.

[0120] Broadly, the system controller 530 may be defined as electronic equipment having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, i.e., microcontrollers that execute program instructions (e.g., software). The program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. The operational parameters may, in some embodiments, be part of a recipe defined by a process engineer to accomplish one or more processing steps in the fabrication or removal of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0121] The system controller 530 may, in some embodiments, be part of, or coupled to, a computer that is integrated or coupled with the system or otherwise networked to the system, or a combination thereof. For example, the controller may be in the "cloud" or all or part of a fab host computer system. This allows for remote access of wafer processing. The computer may allow remote access to the system to monitor the current progress of a fabrication operation, review the history of past fabrication operations, review trends or performance criteria from multiple fabrication operations, modify parameters of a current process, set processing steps following a current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the system over a network. Such a network may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the system controller 530 receives instructions in the form of data. Such data identifies parameters for each processing step performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the system controller 530 may be distributed, for example, by including one or more individual controllers that are networked together and cooperate toward a common purpose (such as the processes and controls described herein).An example of a distributed controller for such purposes would include one or more integrated circuits on the chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer) and coupled to control the process in the chamber.

[0122] Exemplary systems may include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an ALD chamber or module, an ALE chamber or module, an ion implantation chamber or module, a tracking chamber or module, an EUV lithography chamber (scanner) or module, a dry development chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0123] As described above, depending on the process step or steps being performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used for material transport to and from tool locations and / or load ports within a semiconductor manufacturing factory.

[0124] EUVL patterning can be performed using any suitable tool, often referred to as a scanner, such as the TWINSCAN NXE:3300B® platform supplied by ASML, Veldhoven, The Netherlands. The EUVL patterning tool can be a standalone device into which the substrate enters and exits for deposition and etching as described herein. Or, as described below, the EUVL patterning tool can be a module on a larger multi-component tool. FIG. 6 illustrates a semiconductor process cluster tool architecture with a vacuum integrated deposition, EUV patterning, and dry develop / etch module in conjunction with a vacuum transfer module suitable for carrying out the processes described herein. The processes can be carried out without such vacuum integrated equipment, although such equipment may be advantageous in some embodiments.

[0125] FIG. 6 illustrates a semiconductor process cluster tool architecture with a vacuum integrated deposition and patterning module in conjunction with a vacuum transfer module suitable for carrying out the processes described herein. The arrangement of transfer modules to "transfer" wafers between multiple containment and processing modules is sometimes referred to as a "cluster tool architecture" system. The deposition and patterning modules are vacuum integrated according to the requirements of the particular process. Other modules, such as for etching, may also be included in the cluster.

[0126] A vacuum transport module (VTM) 638 interfaces with four processing modules 620a-620d that may be individually optimized to perform various fabrication processes. By way of example, processing modules 620a-620d may be implemented to perform deposition, evaporation, ELD, dry develop, etch, strip, and / or other semiconductor processes. For example, module 620a may be an ALD reactor that may be operated to perform the non-plasma thermal atomic layer deposition described herein, such as a Vector tool available from Lam Research Corporation of Fremont, Calif., and module 620b may be a PECVD tool, such as a Lam Vector™. It should be understood that the figures are not necessarily to scale.

[0127] Airlocks 642 and 646, also known as loadlocks or transfer modules, interface with the VTM 638 and the patterning module 640. For example, as mentioned above, a suitable patterning module may be a TWINSCAN NXE:3300B™ platform supplied by ASML, Veldhoven, The Netherlands. This tool architecture allows workpieces such as semiconductor substrates or wafers to be transferred under vacuum and made non-reactive prior to exposure. The integration of the deposition module with the lithography tool is facilitated by the fact that EUVL also requires significantly lower pressures, given the strong optical absorption of incident photons by ambient gases such as H2O, O2, etc.

[0128] As mentioned above, this integrated architecture is only one possible embodiment of a tool for the implementation of the described process. The process can also be implemented using a more conventional standalone EUVL scanner and deposition reactor, such as a Lam Vector tool, either standalone or integrated into a cluster architecture, using other tools such as etch, strip, etc. as modules (e.g., Lam Kiyo or Gamma tools), as described, for example, with reference to FIG. 6 (but without the integrated patterning module).

[0129] Airlock 642 may be an "out" load lock, referring to the transfer of substrates from the VTM 638 that serves deposition module 620a to the patterning module 640, and airlock 646 may be an "in" load lock, referring to the transfer of substrates from the patterning module 640 to the VTM 638. In load lock 646 may also provide an interface to the outside of the tool for access and removal of substrates. Each process module has a facet that interfaces the module to the VTM 638. For example, deposition process module 620a has facet 636. Within each facet, sensors, for example sensors 1-18 shown, are used to detect the passage of wafer 626 as it moves between the respective stations. Patterning module 640 and airlocks 642 and 646 may similarly include additional facets and sensors not shown.

[0130] A main VTM robot 622 transfers wafers 626 between modules including airlocks 642 and 646. In one embodiment, the robot 622 has one arm, and in another embodiment, the robot 622 has two arms, each arm having an end effector 624 that picks up a wafer such as wafer 626 for transfer. A front-end robot 644 is used to transfer wafers 626 from the outgoing airlock 642 to the patterning module 640 and from the patterning module 640 to the incoming airlock 646. The front-end robot 644 may also transfer wafers 626 between the incoming load lock and the exterior of the tool for substrate access and removal. The incoming airlock module 646 has the ability to interface between atmosphere and vacuum environments, allowing the wafers 626 to move between the two pressure environments without damage.

[0131] It should be noted that EUVL tools typically operate at a higher vacuum than deposition tools. In this case, it may be desirable to increase the vacuum environment of the substrate during transfer from deposition to the EUVL tool so that the substrate can be degassed before entering the patterning tool. The unloading airlock 642 may provide this function by holding the transferred wafer at a low pressure below the pressure of the patterning module 640 for a period of time while the off-gassing is exhausted so that the optics of the patterning tool 640 are not contaminated by the outgassing of the substrate. A suitable pressure for the unloading degassing airlock is 1E-8 Torr or less.

[0132] In some embodiments, a system controller 650 (which may include one or more physical or logical controllers) controls some or all of the operations of the cluster tool and / or its separate modules. It should be noted that the controller may be intrinsic to the cluster architecture, be located outside the cluster architecture on the manufacturing floor, or be connected to the cluster architecture via a network at a remote location. The system controller 650 may include one or more memory devices and one or more processors. The processor may include a central processing unit (CPU) or computer, analog and / or digital input / output connections, stepper motor controller boards, and other similar components. Instructions for implementing appropriate control operations are executed on the processor. These instructions may be stored in a memory device associated with the controller or provided over a network. In certain embodiments, the system controller executes system control software.

[0133] The system control software may include instructions for controlling the timing of application and / or magnitude of any aspect of tool or module operation. The system control software may be configured in any suitable manner. For example, various process tool component subroutines or control objects may be written to control the operation of process tool components necessary to perform various process tool processes. The system control software may be coded in any suitable computer readable programming language. In some embodiments, the system control software includes input / output control (IOC) sequence instructions for controlling the various parameters described above. For example, each stage of a semiconductor fabrication process may include one or more instructions for execution by the system controller. Instructions for setting process conditions for condensation, deposition, evaporation, patterning, and / or etching stages may be included in the corresponding recipe stages, for example.

[0134] In various embodiments, an apparatus for forming a negative pattern mask is provided. The apparatus can include a process chamber for patterning, deposition, and etching, and a controller including instructions for forming a negative pattern mask. The instructions can include code for patterning features in a chemically amplified resist (CAR) on a semiconductor substrate by EUV exposure to expose a surface of the substrate in the process chamber, dry developing the photo-patterned resist, and etching an underlying layer or layer stack using the patterned resist as a mask.

[0135] It should be noted that the computer that controls the movement of the wafers can be intrinsic to the cluster architecture, can be located outside the cluster architecture on the manufacturing floor, or can be connected to the cluster architecture via a network at a remote location. A controller such as that described above with respect to any of Figures 3, 4, or 5 can be implemented using the tools of Figure 6.

[0136] conclusion A process and apparatus for dry development of metal and / or metal oxide photoresists, for example for forming patterning masks in the context of EUV patterning, is disclosed.

[0137] It is understood that the examples and embodiments described herein are for illustrative purposes only, and various modifications or changes will be suggested to those skilled in the art in light thereof. Various details have been omitted for clarity, but various design alternatives may be implemented. Thus, the examples should be considered as illustrative rather than restrictive, and the disclosure should not be limited to the details provided herein, but may be modified within the scope of the disclosure.

[0138] The following exemplary claims are provided to further describe certain embodiments of the present disclosure, but the present disclosure is not necessarily limited to these embodiments.

Claims

1. A method for depositing a metal oxide-containing photoresist material, comprising: flowing a first organometallic precursor and a second organometallic precursor into a reaction chamber containing a counter-reactant, the first organometallic precursor comprising a metal having a high EUV absorption cross section, a first organic group having a metal-carbon bond that is resistant to a vapor deposition reaction with the counter-reactant, and a first ligand that reacts with the counter-reactant, and the second organometallic precursor does not comprise an organic group having a metal-carbon bond and comprises a second ligand that reacts with the counter-reactant; varying a ratio of the first organometallic precursor to the second organometallic precursor during deposition such that the metal oxide-containing photoresist material comprises a vertical compositional gradient along a thickness of the metal oxide-containing photoresist material; A method comprising:

2. A method according to claim 1, comprising: The method wherein the ratio is altered such that the bottom of the metal oxide-containing photoresist material is more cross-linked than the top of the metal oxide-containing photoresist material.

3. The method according to claim 1, The method, wherein the first organometallic precursor and the second organometallic precursor each comprise tin (Sn).

4. The method of claim 1, comprising: The method of claim 1, wherein the first organic group is an alkyl.

5. The method of claim 1, comprising: The method of claim 1, wherein the first ligand comprises an amine.

6. The method of claim 1, comprising: The method of claim 1, wherein the ratio of the second organometallic precursor to the first organometallic precursor decreases as the metal oxide-containing photoresist material grows.

7. The method of claim 1, comprising: The method of claim 1, wherein the first organometallic precursor is isopropyltris(dimethylamino)tin.

8. The method of claim 1, comprising: The method of claim 1, wherein the second organometallic precursor is tetrakis(dimethylamino)tin.

9. A method for depositing a metal oxide-containing photoresist material, comprising: flowing a first organometallic precursor and a second organometallic precursor into a reaction chamber containing a counter-reactant, the first organometallic precursor comprising a metal having a high EUV absorption cross section, a first organic group having a metal-carbon bond that is resistant to a vapor phase deposition reaction with the counter-reactant, and a first ligand that reacts with the counter-reactant, and the second organometallic precursor comprising a second organic group having a metal-carbon bond that is resistant to a vapor phase deposition reaction with the counter-reactant, and a second ligand that reacts with the counter-reactant; varying a ratio of the first organometallic precursor to the second organometallic precursor during deposition such that the metal oxide-containing photoresist material comprises a vertical compositional gradient along a thickness of the metal oxide-containing photoresist material; A method comprising:

10. The method of claim 9, comprising: The method, wherein the first organometallic precursor and the second organometallic precursor each comprise tin (Sn).

11. The method of claim 9, comprising: The method of claim 1, wherein the ratio of the second organometallic precursor to the first organometallic precursor decreases as the metal oxide-containing photoresist material grows.

12. The method of claim 9, comprising: The method, wherein at least one of the first organometallic precursor and the second organometallic precursor comprises an amine.

13. The method of claim 9, comprising: The method wherein the ratio is altered such that the bottom of the metal oxide-containing photoresist material is more cross-linked than the top of the metal oxide-containing photoresist material.

14. The method of claim 9, comprising: The method of claim 1, wherein the first organometallic precursor is isopropyltris(dimethylamino)tin.

15. The method of claim 9, comprising: The method of claim 1, wherein the second organometallic precursor is tetrakis(dimethylamino)tin.

16. A metal oxide-containing photoresist film, comprising: a vertical composition gradient along the thickness of the film; the vertical compositional gradient comprises a first composition and a second composition; the first composition comprises a metal having a high EUV absorption cross section and bridged with a metal-oxide bond and a first organic group having a metal-carbon bond; the second composition has a metal with a high EUV absorption cross section and includes the metal bridged with more metal-oxygen bonds than the first composition, and the vertical composition gradient is such that the ratio of the second composition to the first composition is higher at the bottom of the film than at the top. film.

17. The membrane of claim 16, The metal is tin (Sn).

18. The membrane of claim 16, A membrane, wherein the first organic group in the first composition is isopropyl, and the second composition does not have an organic group with a metal-carbon bond.

19. The membrane of claim 16, The membrane, wherein the first organic group in the first composition is isopropyl and the second composition further comprises an organic group having a metal-carbon bond, the organic group being t-butyl.

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