Underlayer with bonded dopants for lithography

Abstract

Examples disclosed relate to the use of extreme ultraviolet light (EUV) to absorb photoelectron-emitting dopants that are bonded to atoms in a hydrogen-donating light-sensitive underlayer for a photoresist. One example provides a method of forming a hydrogen-donating photosensitive underlayer on a substrate. The method includes exposing the substrate to a dopant precursor and a hydrocarbon precursor, the dopant precursor including an extreme ultraviolet light (EUV) absorbing photoelectron emitting dopant bonded within a carbon-containing polymerizable molecule. The method further includes exposing the substrate to a free radical species formed from a plasma. The method further includes forming a hydrogen-donating photosensitive underlayer on the substrate from the dopant precursor and the hydrocarbon precursor by reaction of the dopant precursor and the hydrocarbon precursor with the free radical species.

Description

Background Art

[0001] In photolithography, photoresists are used to transfer light patterns to substrates and form patterned coatings. First, a layer of light-sensitive photoresist material is applied to the substrate. Then, using a patterned mask, the unshielded areas of the photoresist are exposed to light. Exposure can enhance negative photoresists or degrade positive photoresists. Next, a developer is used to remove the shielded areas of the negative photoresist, or the degraded areas of the positive photoresist. The remaining photoresist material forms a patterned coating on the substrate. For example, the patterned coating can be used to selectively protect the coated areas of the substrate from subsequent deposition or etching processes. Summary of the invention

[0002] This summary is provided to introduce a selection of concepts in a simplified form, which will be further described in the following detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that address any or all of the disadvantages mentioned in any part of this disclosure.

[0003] Disclosed examples involve the use of extreme ultraviolet (EUV) absorbing photoelectron emitting dopants that bond to atoms in a hydrogen donating photosensitive underlayer for a photoresist.

[0004] One example provides a method of forming a photosensitive underlayer on a substrate. The method includes: exposing the substrate to a dopant precursor and a hydrocarbon precursor, the dopant precursor including an extreme ultraviolet (EUV) absorbing photoelectron emitting dopant bonded in a carbon-containing polymerizable molecule. The method also includes: exposing the substrate to a free radical species. The method also includes: forming a hydrogen-donating photosensitive underlayer on the substrate from the dopant precursor and the hydrocarbon precursor through a reaction of the dopant precursor and the hydrocarbon precursor with the free radical species.

[0005] In some such examples, exposing the substrate to the radical species includes introducing the radical species from a remote plasma into a processing chamber including the substrate through an ion shielded and radiation shielded inlet.

[0006] In some such examples, the dopant precursor is additionally or alternatively introduced into the ion shielding and radiation shielding structure downstream of the ion shielding and radiation shielding inlet.

[0007] In some such examples, additionally or alternatively, the carbon-containing polymerizable molecule includes one or more of a carbon-carbon double bond, a carbon-carbon triple bond, or a cyclic group.

[0008] In some such examples, the method also includes, additionally or alternatively, mixing the hydrocarbon precursor with a hydrogen-containing gas prior to exposing the substrate to the hydrocarbon precursor.

[0009] In some such examples, the dopant precursor additionally or alternatively includes an iodine-containing dopant precursor.

[0010] In some such examples, the iodine-containing dopant precursor additionally or alternatively includes one or more of iodoacetylene or 3-iodopropylene.

[0011] In some such examples, the dopant precursor additionally or alternatively includes a tin-containing dopant precursor.

[0012] In some such examples, the tin-containing dopant precursor additionally or alternatively includes one or more of dimethyltin(II), diethyltin(II), tetravinyltin(IV), or dimethyl(divinyl)tin(IV).

[0013] In some such examples, additionally or alternatively, a ratio of the hydrocarbon precursor gas flow rate in standard cubic centimeters per minute (sccm) to the dopant precursor gas flow rate in sccm is in a range of 2:1 to 100:1.

[0014] In some such examples, the method also includes, additionally or alternatively, controlling a substrate heater to heat to a temperature in a range of 100°C to 300°C.

[0015] Another example provides a patterned stack disposed on a substrate. The patterned stack includes a photoresist layer. The patterned stack also includes a hydrogen-donating photosensitive bottom layer disposed between the photoresist layer and the substrate. The hydrogen-donating photosensitive bottom layer includes an extreme ultraviolet (EUV) absorbing photoelectron emitting dopant, and the extreme ultraviolet absorbing photoelectron emitting dopant is bonded to atoms in the hydrogen-donating photosensitive bottom layer.

[0016] In some such examples, the hydrogen donating photosensitive underlayer includes silicon carbide.

[0017] In some such examples, additionally or alternatively, the hydrogen donating photosensitive underlayer comprises a polymer.

[0018] In some such examples, the EUV absorbing photoelectron emitting dopant additionally or alternatively includes one or more of In, Sn, Sb, Te, or I.

[0019] In some such examples, the photoresist layer additionally or alternatively includes extreme ultraviolet (EUV) photoresist.

[0020] In some such examples, the EUV photoresist additionally or alternatively includes a tin-based metal oxide photoresist.

[0021] Another example provides a processing tool. The processing tool includes a processing chamber. The processing tool also includes a plasma generator. The processing tool also includes an RF power supply configured to provide RF power to the plasma generator. The processing tool also includes flow control hardware configured to control the flow of gas into the processing chamber and into the plasma generator. The processing tool also includes a logic subsystem; and a storage subsystem, which includes instructions, the instructions can be executed by the logic subsystem to: control the flow control hardware to introduce a dopant precursor and a hydrocarbon precursor into the processing chamber, the dopant precursor including an extreme ultraviolet (EUV) absorbing photoelectron emitting dopant, and the extreme ultraviolet (EUV) absorbing photoelectron emitting dopant is bonded to a carbon-containing polymerizable molecule. The instructions are also executable to control the flow control hardware to introduce an inert gas into the plasma generator. The instructions are also executable to control the RF power supply to form a plasma in the plasma generator. The instructions are also executable to control the flow control hardware to introduce a radical species precursor into the plasma generator.

[0022] In some such examples, the processing tool further includes a dopant precursor gas source, wherein the dopant precursor gas source includes one or more of an iodine-containing dopant precursor or a tin-containing dopant precursor.

[0023] In some such examples, the processing tool also includes, additionally or alternatively, an ion shield and a radiation shield inlet connecting the plasma generator and the processing chamber.

[0024] In some such examples, the instructions are additionally or alternatively executable to control the flow control hardware to flow the hydrocarbon precursor and to flow the dopant precursor with a gas flow ratio in a range of 2 sccm:1 sccm to 10 sccm:1 sccm.

[0025] In some such examples, the processing tool additionally or alternatively includes a substrate heater, and the instructions are further executable to control the substrate heater to heat to a temperature in a range of 100°C to 300°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A-1B The formation of a dopant hydride in a hydrogen donating photosensitive underlayer including a bulk EUV absorbing photoelectron emitting dopant is schematically shown.

[0027] Figure 2A-2C Schematic illustration of chemical changes occurring in a patterned stack at various processing stages in an exemplary extreme ultraviolet (EUV) lithography process.

[0028] Figures 3A-3D Schematic representation of chemical reactions that may occur in an exemplary tin-based metal oxide EUV photoresist layer in an exemplary EUV lithography process.

[0029] Figure 4 The migration of labile hydrogen in a hydrogen donating photosensitive underlayer including a bonded EUV absorbing photoelectron emitting dopant is schematically shown.

[0030] Figure 5 An exemplary processing tool that can be used to form a hydrogen donating photosensitive underlayer including EUV absorbing photoelectron emitting dopants bonded to carbon atoms is schematically shown.

[0031] Figure 6 An exemplary reaction of a dopant precursor with a hydrocarbon precursor to form a hydrogen donating photosensitive underlayer including a bonded EUV absorbing photoelectron emitting dopant is schematically shown.

[0032] Figure 7 Another exemplary reaction of a dopant precursor with a hydrocarbon precursor to form a hydrogen donating photosensitive underlayer including a bonded EUV absorbing photoelectron emitting dopant is schematically shown.

[0033] Figure 8 A flow chart is shown depicting an exemplary method for forming a patterned stack.

[0034] Fig. 9 A block diagram of an exemplary computer system is shown. DETAILED DESCRIPTION

[0035] The term "aliphatic" may generally refer to an organic compound lacking an aromatic group. The term "aliphatic ligand" may generally refer to a ligand derived from an aliphatic in which a hydrogen atom is removed to allow the ligand to bond to a dopant atom.

[0036] The term "alkane" generally refers to hydrocarbons having the general chemical formula C n H 2n+2 Compounds of the general chemical formula C n H 2n+1, which is generated by removing one hydrogen from an alkane. Exemplary alkyl groups include methyl, ethyl, propyl, and butyl. Exemplary alkyl groups that may be suitable for use as aliphatic ligands disclosed herein may include alkyl groups where n=1 to 12.

[0037] The term "alkene" may generally refer to a hydrocarbon compound that includes at least one carbon-carbon double bond. An alkene that includes one carbon-carbon double bond has a general chemical formula of C n H 2n Exemplary olefins include ethylene, propylene, and butene. Olefins may have more than one carbon-carbon double bond, such as dienes, propadiene, and polyenes. The term "alkenyl" may generally refer to a group comprising the general chemical formula C n H 2n-1 A functional group derived from an olefin by removing one hydrogen. Exemplary alkenyl groups include vinyl, allyl, propenyl, and butenyl. Exemplary alkenyl groups that may be suitable for use as unsaturated aliphatic ligands in the dopant precursors disclosed herein may include alkenyl groups where n=2 to 12.

[0038] The term "alkyne" may generally refer to a hydrocarbon compound that includes at least one carbon-carbon triple bond. Alkynes that include one carbon-carbon triple bond have the general chemical formula C n H 2n-2 Alkynes may have more than one carbon-carbon triple bond, such as a diyne, which has two carbon-carbon triple bonds. The term "alkynyl" may generally refer to a group including a group of the general formula C n H 2n-3 A functional group derived from the removal of one hydrogen from an alkyne. Exemplary alkynyl groups include ethynyl, propynyl, and butynyl. Exemplary alkynyl groups that may be suitable for use as unsaturated aliphatic ligands in the dopant precursors disclosed herein may include alkynyl groups where n=2 to 12.

[0039] The term "aromatic" refers to a planar cyclic compound that includes resonant pi bonds. The term "aromatic" includes homocyclic compounds, in which all atoms in the ring structure are carbon, and heterocyclic compounds, in which one or more atoms in the ring structure are elements other than carbon (e.g., nitrogen).

[0040] The term "carbon-containing polymerizable molecule" may generally refer to aliphatic and aromatic molecules that are capable of bonding to an extreme ultraviolet (EUV) absorbing photoelectron emitting dopant and are capable of polymerizing with the hydrocarbon precursors disclosed herein. Examples of carbon-containing polymerizable molecules include molecules having carbon-carbon double bonds, molecules having carbon-carbon triple bonds, molecules having cyclic groups, and molecules having aromatic groups.

[0041] The term "chemical vapor deposition" may generally refer to a process in which a substrate is exposed to one or more vapor-phase precursors that react to form a deposited film on the substrate surface.

[0042] The term "cyclic hydrocarbon" may generally refer to saturated and unsaturated hydrocarbon molecules including closed ring structures. Cyclic hydrocarbons may be aliphatic or aromatic. Examples of cyclic hydrocarbons include cyclopropane and cyclobutene. The term "cycloalkyl" may generally refer to a functional group resulting from the removal of one hydrogen from a cycloalkane. Exemplary cycloalkyl groups that may be suitable for use as carbon-containing polymerizable ligands in the dopant precursors disclosed herein include cyclopropyl, cyclobutyl, and cyclohexyl. The term "cycloalkenyl" may generally refer to a functional group resulting from the removal of one hydrogen from a cycloalkene. Exemplary cycloalkenyl groups that may be suitable for use as aliphatic ligands in the dopant precursors disclosed herein include cyclobutenyl and cyclohexenyl. The term "cyclic group" may generally refer to a functional group including a cyclic hydrocarbon.

[0043] The term "dopant precursor" may generally refer to any suitable compound including an EUV absorbing photoelectron emitting dopant bonded within a carbon-containing polymerizable molecule that can react with a hydrocarbon precursor to form a hydrogen-donating photosensitive underlayer. Exemplary EUV absorbing photoelectron emitting dopants suitable for use in the hydrogen-donating photosensitive underlayer include indium (In), tin (Sn), antimony (Sb), tellurium (Te), and iodine (I). The dopant precursor may have the general chemical formula ZR n , n≥1, wherein Z is any suitable EUV absorbing element that emits EUV photoelectrons, and wherein R generally represents a ligand, one or more of which include a carbon-containing molecule. Each R may independently be, for example, hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkenyl, or substituted cycloalkenyl. Suitable alkyl ligands include methyl, ethyl, propyl, and tert-butyl. Suitable substituted alkyls include iodoethyl and aminopropyl. Suitable cycloalkyl ligands include cyclopropyl and cyclobutyl groups. Suitable substituted cycloalkyl ligands include aminocyclohexyl. Suitable alkenyl ligands include vinyl (ethenyl), allyl, propenyl, and 3-butenyl. Suitable substituted alkenyl ligands include aminovinyl. Suitable alkynyl ligands include ethynyl and propynyl. Suitable substituted alkynyl ligands include chloropropynyl. Suitable cycloalkenyl ligands include cyclobutenyl and cyclohexenyl.

[0044] Exemplary dopant precursors that may be suitable for forming a hydrogen-donating photosensitive underlayer include organic antimony compounds (e.g., Sb(V) compounds having the general chemical formula R5Sb and Sb(III) compounds having the general chemical formula R3Sb), organic tin compounds (e.g., Sn(IV) compounds having the general chemical formula R4Sn), organic tellurium compounds (e.g., telluride compounds having the general chemical formula R2Te or (RTe)2, Te(IV) compounds having the general chemical formula R4Te, and tellurium oxides having the general chemical formula R2TeO), and organic iodine compounds having the general chemical formula RI. Exemplary dopant precursors include tin-containing dopant precursors (e.g., tetravinyltin(IV), tetraethynyltin(IV), diethyltin(II), dimethyltin(II), and dimethyl(divinyl)tin(IV)), antimony-containing dopant precursors (e.g., trivinylantimony), tellurium-containing dopant precursors (e.g., divinyltellurium oxide), and iodine-containing dopant precursors (e.g., iodoacetylene, 3-iodopropylene, and 3-iodopropyne).

[0045] The term "extreme-ultraviolet (EUV) absorbing photoelectron-emissive dopant" may generally refer to any atom that absorbs radiation having a wavelength in the range of 124 nanometers (nm) to 10 nm and emits photoelectrons in response. Exemplary EUV absorbing photoelectron-emissive dopants that may be suitable for use in the bottom layer include indium (In), antimony (Sb), tin (Sn), tellurium (Te), and iodine (I).

[0046] The term "EUV photolithography process" may generally refer to a photolithography process in which a photoresist sensitive to EUV light is exposed to EUV light. The term "EUV photoresist" may generally refer to a photoresist material sensitive to EUV light. EUV refers to light having a wavelength between about 124 nm and about 10 nm and a photon energy between 10 eV and 124 eV.

[0047] The term "functional group" may generally refer to an atom or a group of atoms in a molecule.

[0048] The term "inlet" may generally refer to any structure used to inject gas-phase chemicals or plasma into a process chamber of a processing tool. In various examples, an inlet may include a nozzle or a showerhead.

[0049] The term "hydrocarbon precursor" may generally refer to any carbon-containing precursor that can be polymerized to form a hydrogen-donating photosensitive bottom layer on a substrate. Exemplary hydrocarbon precursors include unsaturated aliphatic compounds and cyclic aliphatic compounds. For example, in the case where a carbon polymer matrix is ​​to be deposited, exemplary unsaturated aliphatic compounds include acetylene, propylene, ethylene, and propylene. For example, in the case where silicon carbide or polycarbosilane is to be deposited, a silicon-containing precursor may be used in addition to a carbon-containing precursor. In some examples, the hydrocarbon precursor may include a gas mixture and may also be mixed with a hydrogen-containing gas.

[0050] The term "hydrogen-contributing photosensitive underlayer" may generally refer to a material that generates labile hydrogen when exposed to light of a suitable wavelength, which can migrate to an overlying layer (e.g., a photoresist layer). Suitable materials for use as a hydrogen-contributing photosensitive underlayer include carbon-based polymers and silicon carbide-based layers.

[0051] The term "ion-shielding and radiation-shielding inlet" may generally refer to an inlet configured to allow a flow of radical species to pass therethrough while filtering at least some ions and electromagnetic radiation from the plasma. In some examples, the ion-shielding and radiation-shielding inlet may include an ion-shielding and radiation-shielding showerhead. The term "showerhead" may generally refer to an inlet including a plurality of holes configured to introduce a process gas into a region of a substrate.

[0052] The term "labile hydrogen" may generally refer to hydrogen molecules, hydrogen atoms or hydrogen ions entrapped in the hydrogen-donating photosensitive underlayer of the photoresist layer. Labile hydrogen may also refer to hydrogen atoms, ions and / or radicals generated in the hydrogen-donating photosensitive underlayer of the photoresist layer by EUV light exposure and that may migrate to the photoresist layer.

[0053] The term "ligand" may generally refer to a functional group that combines with a central metal atom to form a coordination complex.

[0054] The term "loose EUV-absorbing photoelectron-emissive dopant" may generally refer to EUV-absorbing photoelectron-emissive dopant species in the hydrogen-donating photosensitive underlayer that are not atomically bonded. Loose EUV-absorbing photoelectron-emissive dopant may include elemental, ionic and / or radical species.

[0055] The term "patterning stack" may generally refer to a hydrogen donating photosensitive underlayer disposed on a substrate and a photoresist layer disposed on the hydrogen donating photosensitive underlayer.

[0056] The term "photoresist" may generally refer to a light-sensitive material that can be used to transfer a pattern to a substrate through radiation-induced changes in the material's properties.

[0057] The term "photosensitive underlayer" may generally refer to a material that undergoes a chemical change when exposed to photons of electromagnetic energy of a suitable wavelength.

[0058] The term "plasma" may generally refer to an ionized gas including positive ions and free electrons. Plasma may be generated using any suitable method, and may include radio frequency (RF) plasma, microwave plasma, and electron beam generated plasma. Plasma may be used to generate free radical species. For example, a hydrogen-containing gas (e.g., H2, NH3, N2H4) may be introduced into a plasma to generate hydrogen radicals, which are hydrogen atoms with unpaired electrons.

[0059] The term "processing chamber" may generally refer to an enclosure in which a chemical and / or physical process is performed on a substrate. Exemplary chemical and / or physical processes include chemical vapor deposition (CVD), atomic layer deposition (ALD), and etching processes.

[0060] The term "processing tool" may generally refer to a machine that includes a processing chamber and other hardware configured to enable processing to be performed on one or more substrates in the processing chamber.

[0061] The term "radical species" may generally refer to a chemical species having unpaired valence shell electrons.

[0062] The term "remote plasma" may generally refer to a plasma used to generate chemical species used to process a substrate located outside of the plasma.

[0063] The term "silicon-containing precursor" may generally refer to any silicon-containing material that may be introduced with a hydrocarbon precursor to deposit silicon carbide or polycarbosilane. Exemplary silicon-containing precursors for forming silicon carbide or polycarbosilane may include materials having the following general structure: Wherein R1, R2 and R3 may be the same or different substituents and may include silane, siloxy, amine, halide, hydrogen, or an organic group, such as an alkylamine, alkoxy, alkyl, alkenyl, alkynyl and aromatic group.

[0064] Exemplary silicon-containing precursors include polysilane (H3Si-(SiH2) n -SiH3), where n≥1, such as silane, disilane, trisilane, tetrasilane and trisilylamine.

[0065] In some examples, the silicon-containing precursor is an alkoxysilane. Alkoxysilanes that can be used include the following: H x -Si-(OR) y , wherein x=1 to 3, x+y=4, and each R is a substituted or unsubstituted alkyl, alkenyl, alkynyl or aromatic group; and H x (RO) y ,-Si-Si-(OR) y H x , is a substituted or unsubstituted alkyl, alkenyl, alkynyl or aromatic group.

[0066] Examples of silicon-containing precursors include tetraethylorthosilicate (TEOS), tetramethoxysilane (TMOS), monosilane, trimethylsilane (3MS), disilane, butasilane, pentasilane, octasilane, heptsilane, hexasilane, cyclotetrasilane, cycloheptasilane, cyclohexasilane, cyclooctylsilane, cyclopentasilane, 1,4-dioxane-2,3,5,6-tetrasilcyclohexane, diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyldiethoxysilane (MDES), methyldimethoxysilane (MDMS), tert-butoxydisilane, triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0067] In some examples, the silicon-containing precursor may be a siloxane. Exemplary siloxanes include octamethylcyclotetrasiloxane (OMCTS), octamethoxydodecylsiloxane (OMODDS), tetramethylcyclotetrasiloxane (TMCTS), triethoxysiloxane (TRIES), and tetraoxymethylcyclotetrasiloxane (TOMCTS).

[0068] As mentioned above, in some examples, the silicon-containing precursor may be an aminosilane, such as bis-diethylaminosilane, diisopropylaminosilane, bis-(tert-butylamino)silane (BTBAS), di-sec-butylaminosilane, or tris-(dimethylamino)silane (3DMAS). Aminosilane precursors include the following: x -Si-(NR)y , wherein x=1 to 3, x+y=4, and each R is a substituted or unsubstituted alkyl, alkenyl, alkynyl or aromatic group or a hydride group.

[0069] In some examples, a halogen-containing silane may be used such that the silane includes at least one hydrogen atom. Such a silane may have the chemical formula SiX a H y , where y ≥ 1. For example, in some examples, dichlorosilane (H2SiCl2) may be used.

[0070] The term "substrate" may generally refer to any structure on which a patterned stack may be formed. Exemplary substrates include semiconductor wafers.

[0071] As described above, photolithography can be used to form a patterned coating on a substrate. In an exemplary process, a photoresist material is applied to a substrate. For example, a wet photoresist can be applied using a spin coating method. A dry photoresist can be applied using a vapor deposition method. Next, the photoresist material is exposed to a light pattern formed by a patterned mask. This exposes some areas of the photoresist to light while shielding other areas from exposure. The exposed areas undergo a chemical reaction that results in a structural difference between the exposed areas relative to the unexposed areas. The structural difference between the exposed and unexposed areas is then used to partially remove the coating. The remaining coating forms a pattern on the substrate.

[0072] Semiconductor device manufacturing employs photolithography in many different steps of integrated circuit fabrication. The minimum feature size that can be resolved in photolithography can be approximated using the Rayleigh equation shown below. In this equation, CD is the critical dimension (the width of a feature formed by exposure in the photoresist), a parameter that is dependent on the processing conditions, λ is the wavelength of the light used, and NA is the numerical aperture of the projection optics. Thus, the critical dimension of the feature size is proportional to the wavelength of the light used. Therefore, by using lithography techniques with shorter wavelengths of light, smaller feature sizes can be achieved.

[0073] Extreme ultraviolet (EUV) lithography is a promising technology for patterning integrated circuits with line and space spacings of less than 36 nanometers (nm). EUV refers to light with a wavelength between about 124 nm and about 10 nm and a photon energy between 10 eV and 124 eV. In some examples, for example, a laser-driven tin (Sn) plasma light source can be used to generate EUV light. Such a light source can produce light with a peak of about 13.5 nm and a relatively narrow bandwidth. After absorbing EUV light, the EUV-sensitive photoresist generates photoelectrons, which drive chemical reactions in the exposed areas of the photoresist. Suitable EUV-sensitive photoresists with λ=13.5 nm may include metal-containing photoresists, such as metal oxide photoresists, metal oxide nanoparticle photoresists, and organic metal photoresists (e.g., photoresists including Zn, Zr, Sn, Sb, Te and / or Hf).

[0074] However, EUV photoresists may have high sensitivity. In addition, the optical devices used in EUV lithography absorb a portion of the incident light. Therefore, only a relatively small portion of the EUV light generated can reach the photoresist. Due to the intensity and high sensitivity of the incident EUV light, a relatively long exposure time may be required to produce features in the photoresist. Longer exposure times may be associated with lower yields. In addition, longer exposure times may also cause substrate heating. This may cause substrate degassing and / or damage. In addition, the transition region of the photoresist (the region between the fully exposed region and the fully shielded region) may receive a relatively low dose (energy per unit area) of EUV light. This may result in poorly defined features in the transition region.

[0075] One method of reducing the exposure time of EUV photoresists is to utilize a hydrogen-donating photosensitive underlayer located between the substrate and the EUV photoresist layer. When exposed to EUV light and / or post-exposure baking, the hydrogen-donating photosensitive underlayer generates unstable hydrogen. Unstable hydrogen can migrate to the EUV photoresist layer. Unstable hydrogen can promote water elimination reactions, resulting in crosslinking of metal oxide photoresists. For example, in tin-based metal oxide EUV photoresists, unstable hydrogen can inhibit the hydroxyl groups from recombining with tin atoms, which allows tin to form Sn-O-Sn bonds, which crosslink the tin metal oxide polymer chains. Therefore, unstable hydrogen can allow crosslinking to occur at shorter EUV light exposure times.

[0076] To further reduce exposure time, EUV absorbing photoelectron emitting dopants can be incorporated into the hydrogen-donating photosensitive bottom layer. EUV absorbing photoelectron emitting dopants can emit EUV photoelectrons when absorbing EUV light. This can provide additional electrons to drive chemical reactions in the photoresist. In addition, the photoelectrons generated by the EUV absorbing photoelectron emitting dopants can also drive the generation of additional unstable hydrogen. Each of these mechanisms can help reduce the photoresist exposure time.

[0077] However, some EUV absorbing photoelectron emitting elements (e.g., Sn, etc.) may easily form hydrides. For example, loose EUV absorbing photoelectron emitting dopants that are not bonded to atoms may form hydrides from unstable hydrogen. Figure 1A-1B More specifically, Figure 1A A hydrogen-donating photosensitive underlayer 102 is shown disposed on a substrate 103. An EUV photoresist layer 104 is disposed on the hydrogen-donating photosensitive underlayer 102. The loose EUV absorbing photoelectron emitting dopant, shown as Sn atom 306, is not bonded to atoms in the hydrogen-donating photosensitive underlayer. Therefore, the Sn atom 306 may capture one or more unstable hydrogen atoms, as shown at 308. This may form tin hydrides, such as Figure 1B Therefore, the loose EUV photoelectron emitting dopant may adversely affect the function of the hydrogen donating photosensitive underlayer by trapping unstable hydrogen.

[0078] Therefore, an example of using a hydrogen-donating photosensitive bottom layer is disclosed, which includes a bonded EUV absorbing photoelectron emitting dopant. In one example, a patterned stack formed on a substrate includes a photoresist layer and a hydrogen-donating photosensitive bottom layer, which includes an EUV absorbing photoelectron emitting dopant bonded to atoms in the hydrogen-donating photosensitive bottom layer. The hydrogen-donating photosensitive bottom layer is disposed between the substrate and the photoresist layer. At least some of the EUV light that is not absorbed by the photoresist layer can be absorbed by the EUV absorbing photoelectron emitting dopant in the hydrogen-donating photosensitive bottom layer. In response, the EUV absorbing photoelectron emitting dopant can generate photoelectrons that help drive a cross-linking reaction in the photoresist. The photoelectrons can also generate additional unstable hydrogen, which promotes the cross-linking reaction in the photoresist. The bonding of the EUV absorbing photoelectron emitting dopant to atoms in the hydrogen-donating photosensitive bottom layer can reduce the risk of forming dopant hydrides from unstable hydrogen in the hydrogen-donating photosensitive bottom layer. Avoiding the generation of dopant hydrides can allow more unstable hydrogen and photoelectrons to reach the photoresist layer. Thus, the disclosed examples can help improve yield by reducing photoresist exposure time.The disclosed examples can also help form well-defined features in transition regions.

[0079] The hydrogen-donating photosensitive bottom layer according to the present disclosure can be formed using a dopant precursor and a hydrocarbon precursor. The dopant precursor includes an EUV absorbing photoelectron emitting dopant bonded to a carbon-containing polymerizable molecule. The dopant precursor can react with the hydrocarbon precursor in a polymerization reaction. The polymerization reaction can be promoted by free radical species formed by plasma. However, plasma ions and / or plasma energy may cause the risk of breaking the carbon-dopant bond of the dopant precursor. Therefore, in some examples, a remote plasma can be used to form free radical species. In such examples, ion shielding and radiation shielding entrances can be used to introduce free radical species into the processing chamber. Ion shielding and radiation shielding entrances can help reduce the risk of high-energy ions and electromagnetic radiation from the plasma damaging the dopant precursor.

[0080] Figure 2A-2C The patterned stack 200 is shown at various stages in the EUV lithography process. Figures 3A-3D The corresponding exemplary chemical reactions for exemplary tin-based metal oxide photoresists are shown. Figure 2A , the patterned stack 200 includes a photoresist layer 202 and a hydrogen donating photosensitive underlayer 204 disposed on a substrate 206. The substrate 206 represents any suitable structure on which the photoresist layer 202 and the hydrogen donating photosensitive underlayer 204 may be formed. The hydrogen donating photosensitive underlayer 204 includes an EUV absorbing photoelectron emitting dopant bonded to carbon atoms, as schematically shown at 208.

[0081] The photoresist layer 202 may include any suitable EUV sensitive photoresist, including wet photoresists and dry photoresists. A wet photoresist may include a photoresist applied in a liquid phase. A dry photoresist may include a photoresist applied by depositing a reactive precursor in a gas phase. In some examples, the photoresist layer 202 may include a tin-based metal oxide photoresist that can form a Sn-O-Sn crosslink, as explained in more detail below. The hydrogen-donating photosensitive bottom layer 204 may include any suitable material for providing unstable hydrogen to the photoresist layer 202. For example, in various examples, the hydrogen-donating photosensitive bottom layer 204 may include a carbon-based polymer or a silicon carbide-containing material. Therefore, in some examples, the EUV absorbing photoelectron emitting dopant may be bonded to any suitable atom (e.g., N, C, Si) within the hydrogen-donating photosensitive bottom layer.

[0082] The EUV absorbing photoelectron emitting dopant may include any suitable atom having a relatively high absorption profile for EUV light. Suitable EUV absorption profiles include those equal to or greater than 1×10 7 cm 2 Exemplary EUV absorbing photoelectron emitting dopants suitable for use in the hydrogen donating photosensitive underlayer include In, Sn, Sb, Te, and I.

[0083] continue Figure 2A , region 202A of the photoresist layer 202 is exposed to EUV light 210. Region 202B is shielded by a patterned mask (not shown) to prevent exposure. Exposing region 202A of the photoresist layer 202 and hydrogen-donating photosensitive bottom layer 204 to EUV light causes the hydrogen-donating photosensitive bottom layer to donate unstable hydrogen to the photoresist layer 202. Then, referring to Figure 2B , the unstable hydrogen reacts with the photoresist to form a chemically modified photoresist region 202C. Figure 3A-3B An exemplary reaction of a tin oxide-based photoresist with labile hydrogen is described.

[0084] In addition, exposure of EUV absorbing photoelectron emitting dopant 208 causes photoelectron emission. Some photoelectrons can generate additional unstable hydrogen through electron collision-induced dissociation (e.g., through bond rupture), as shown at 222. In addition, some photoelectron emitting dopants can generate photoelectrons that migrate to photoresist layer 202, as shown at 224. Such photoelectrons can increase the photon dose of EUV light exposure. Through either or both of these mechanisms, photoelectrons generated by EUV absorbing photoelectron emitting dopants can help reduce the exposure time for forming chemically adjusted photoresist region 202C.

[0085] Next, the photoresist layer 202 including the chemically adjusted photoresist region 202C is subjected to a post-exposure bake (PEB). The PEB process drives unstable hydrogen into the photoresist layer 202. This results in a water elimination reaction and cross-linking of the photoresist molecules in the chemically adjusted photoresist region 202C. Figure 2C , which results in the formation of cross-linked photoresist regions 202D. A subsequent development process may be used to remove regions 202B of the photoresist film. Thus, the development process forms a patterned photoresist film including cross-linked photoresist regions 202D.

[0086] Figure 2A-2C The EUV lithography process shown can be performed using various photoresist chemistries. Figures 3A-3D show Figure 2A-2C The process is performed on the exemplary tin-based metal oxide EUV photoresist layer 300. First, Figure 3AThe molecular structure of an exemplary tin-based metal oxide EUV photoresist layer 300 is shown. The tin-based metal oxide EUV photoresist layer 300 includes a tin metal oxide polymer chain 302 (which is depicted as a Sn-O-Sn polymer chain) having a functional group (R) 304 bonded to a Sn atom. The functional group 304 may include any suitable functional group that can undergo a β-hydride elimination reaction. For example, the functional group 304A includes an ethyl group that can undergo a β-hydride elimination to form ethylene. Figure 3A Also shown is an interface 306 between the tin-based metal oxide EUV photoresist layer 300 and a hydrogen-donating photosensitive underlayer 308, which includes a carbon polymer-based structure. The hydrogen-donating photosensitive underlayer 308 includes one or more EUV-absorbing photoelectron-emitting dopant atoms 310 bonded to carbon atoms of the carbon polymer-based structure. The hydrogen-donating photosensitive underlayer 308 also includes entrained hydrogen, which includes molecular hydrogen (H2) 312A, radical hydrogen (H·) 312B, and hydrogen ions (H + )312C. In addition, the structure of carbon-based polymers includes H atoms bonded to carbon, such as H 314.

[0087] Next reference Figure 3B ,exist Figure 3A When the structure is exposed, unstable hydrogen 316 is generated in the hydrogen-donating photosensitive bottom layer 308. The unstable hydrogen may include entrained hydrogen, such as H2 312A, H 312B, and H + 312C. In addition, photoelectrons generated by EUV absorbing photoelectron emitting dopant atoms 310 can generate additional unstable hydrogen. For example, as shown at 316, photoelectrons generated by EUV absorbing photoelectron emitting dopant atoms 310 can generate unstable hydrogen 314A from hydrogen 314 of the backbone 318 of the carbon-based polymer structure.

[0088] Photoelectrons generated by EUV absorbing photoelectron emitting dopant atoms 310 may also migrate to the tin-based metal oxide EUV photoresist layer 300, as shown by photoelectrons 320. Upon exposure to EUV light 210 and photoelectrons (e.g., photoelectrons 320) from the hydrogen donating photosensitive bottom layer 308, the bond between Sn and the functional group 304 is cleaved. Figure 3B As shown, functional group 304 is replaced with H. For example, ethyl group 304A undergoes a β-hydride elimination to form ethylene 304B and donates H, as shown at 322. Figure 3B Chemically tuned tin oxide-based EUV photoresists can represent Figure 2B The chemically modified photoresist region 202C.

[0089] In some examples, the R functional groups 304 may be relatively bulky. Therefore, replacing the R functional groups with hydrogen may allow the tin metal oxy polymer chains to be more tightly bound together. This may promote crosslinking by water elimination.

[0090] like Figure 3B As shown, water molecules may be eliminated from adjacent hydroxyl groups 324 of the tin metal oxypolymer chains to crosslink adjacent chains. Figure 3C The result of water elimination 325 in the cross-linked structure 326 is shown. Figure 3C As shown, heat 328 is applied to help remove water from the cross-linked structure 326. Heat 328 can also help promote the migration of labile hydrogen into the photoresist layer, as shown at 330. In the depicted example, the labile hydrogen can inhibit the hydroxyl groups from recombining with the tin atoms (e.g., by changing the balance between Sn-O-Sn links and -OH terminated Sn), which in combination with the evaporation of water drives the tin to form Sn-O-Sn bonds. Figure 3D As shown, the crosslinked structure 326 includes Sn-O-Sn bonds 332 between the tin metal oxide polymer chains. The crosslinked structure 326 is Figure 2C An example of a cross-linked photoresist region 202D.

[0091] like Figure 2A-2C and Figures 3A-3D As shown, the use of EUV absorbing photoelectron emitting dopants in the hydrogen donating photosensitive underlayer can help reduce the exposure time of the EUV photoresist. Figure 1A-1B As mentioned, the use of bulky EUV absorbing photoelectron emitting dopants may result in the formation of dopant hydrides from labile hydrogen.

[0092] Compared to Figure 1A-1B , Figure 4 A substrate 401 is shown on which a hydrogen-donating photosensitive underlayer 402 is disposed. The hydrogen-donating photosensitive underlayer 402 includes dopants (e.g., Sn atoms 404) bonded to carbon atoms. As described above, unstable hydrogen atoms 406 may include H2, H, or H2 entrained in the hydrogen-donating photosensitive underlayer. + , or may be generated by carbon-based polymer chains in the hydrogen-donating photosensitive bottom layer. Unstable hydrogen atoms 406 may migrate into the photoresist layer 408 without being captured by Sn atoms in the hydrogen-donating photosensitive bottom layer 402. Figure 1A-1B The examples depicted in FIGS. 4 and 5 use Sn, but any other suitable EUV absorbing photoelectron emitting dopant may be used, including In, Sb, Te, and / or I.

[0093] The hydrogen-donating photosensitive bottom layer including EUV-absorbing photoelectron-emitting dopants bonded to atoms can be formed in any suitable manner. In some examples, the hydrogen-donating photosensitive bottom layer can be formed by chemical vapor deposition. In an exemplary method, a hydrocarbon precursor and a dopant precursor as described above can be introduced into a processing chamber including a substrate to form the hydrogen-donating photosensitive bottom layer by polymerization. In some examples, the substrate can be heated.

[0094] In addition, in some examples, polymerization may be free radical assisted. Any suitable free radical source may be used. In some such examples, a plasma may be used to form free radical species that initiate polymerization. However, ions and radiation from the plasma may be energetic enough to disrupt ligand-dopant bonds in the dopant precursor. Therefore, in some examples, the injection of the dopant precursor into the processing chamber may be separated from the injection of the free radical species by using a remote plasma and ion shielding and radiation shielding inlets to introduce the free radical species generated in the plasma into the processing chamber.

[0095] Figure 5 A schematic diagram of an exemplary processing tool 500 is shown that employs ion shielding and radiation shielding inlets to form a hydrogen-supply photosensitive bottom layer that includes EUV absorbing photoelectron emitting dopants. The processing tool 500 includes a processing chamber 502 and a substrate support 504 within the processing chamber. The substrate support 504 is configured to support a substrate 506 disposed within the processing chamber 502. In some examples, the substrate support 504 includes a substrate heater 508. The substrate support 504 may include a susceptor, a chuck, and / or any other suitable structure.

[0096] The processing tool 500 also includes an ion shield and radiation shield inlet 510. The ion shield and radiation shield inlet 510 is configured to introduce precursor gases and radical species into the processing chamber 502 while filtering ions and radiation generated in the remote plasma generator 530, as described in more detail below. In some examples, the ion shield and radiation shield inlet 510 includes a showerhead.

[0097] The processing tool 500 also includes flow control hardware 514A-514B. The flow control hardware 514A is connected to a dopant precursor source 516, a hydrocarbon precursor source 518, and a hydrogen source 520. Figure 5In the depicted example, a hydrogen source 520 can be used as a free radical precursor. In some examples, any suitable hydrogen-containing gas (e.g., H2, NH3, or N2H4) can be used as a free radical precursor. Flow control hardware 514B is connected to an inert gas source 522. Flow control hardware 514B is configured to control the flow of hydrogen-containing gas from the hydrogen source 520 and / or inert gas from the inert gas source 522 into the remote plasma generator 530. The hydrocarbon precursor source 518 can include any suitable hydrocarbon that can be polymerized to form a hydrogen-supplying photosensitive underlayer. Exemplary hydrocarbon precursors are described in more detail above.

[0098] The dopant precursor source 516 may include any suitable dopant precursor that, when reacted with the hydrocarbon precursor, forms a hydrogen-donating photosensitive bottom layer that includes an EUV absorbing photoelectron emitting dopant bonded to an atom (e.g., a carbon atom of the hydrocarbon precursor). As described above, the dopant precursor may include a dopant atom bonded to a carbon-containing polymerizable molecule. Exemplary dopant precursors include tin-containing dopant precursors, such as tetravinyltin (IV), tetraethynyltin (IV), diethyltin (II), dimethyltin (II), and dimethyl (divinyl) tin (IV). In some examples, exemplary dopant precursors also include iodine-containing precursors, such as iodoacetylene, 3-iodopropylene, and 3-iodopropyne. Further examples include precursors comprising In, Sb, and Te bonded to a carbon-containing polymerizable molecule. Exemplary carbon-containing polymerizable molecules include vinyl, ethynyl, allyl, propenyl, butenyl, and cyclopropyl ligands, as well as others discussed above.

[0099] The dopant precursor and the hydrocarbon precursor are configured to react to form a hydrogen-donating photosensitive underlayer on the substrate by polymerization. As described above, the hydrogen-donating photosensitive underlayer includes a bonded EUV absorbing photoelectron emitting dopant. In addition, hydrogen gas from a hydrogen source 520 may be introduced.

[0100] Figure 6-7 An exemplary polymerization reaction for forming a hydrogen-donating photosensitive underlayer comprising a bonded EUV-absorbing photoelectron-emitting dopant is shown. First, Figure 6An exemplary polymerization reaction 600 between a dopant precursor 602 and a hydrocarbon precursor 604 is shown. The dopant precursor 602 includes tetravinyltin (IV). The hydrocarbon precursor 604 includes propylene. The dopant precursor 602 and the hydrocarbon precursor 604 react to form a tin-containing polymeric hydrocarbon 606. The polymerization reaction 600 can be promoted by a free radical species 608. The free radical species 608 can be any suitable free radical species. Examples include free radicals generated by hydrogen (H2), deuterium (D2), ammonia (NH3) and / or hydrazine (N2H4) in a plasma. The free radical species 608 can be formed by a plasma, such as by a remote plasma. The tin-containing polymeric hydrocarbon 606 includes Sn-C bonds, such as bond 610. Therefore, when used as a hydrogen-donating photosensitive underlayer, the tin atoms in the tin-containing polymeric hydrocarbon 606 can help generate EUV photoelectrons without trapping unstable hydrogen.

[0101] Next, Figure 7 An example of a polymerization reaction 700 between a dopant precursor 702 (including 3-iodopropylene) and a hydrocarbon precursor 704 (including propylene) is shown. The dopant precursor 702 and the hydrocarbon precursor 704 react to form an iodine-containing polymerized hydrocarbon 706. Free radical species 708 can promote the reaction. Examples of free radical species include free radicals formed from one or more of hydrogen, deuterium, ammonia, or hydrazine in the plasma. As shown by bond 710, the polymerized hydrocarbon 706 includes an iodine-carbon (IC) bond. Therefore, when used as a hydrogen-donating photosensitive underlayer, the iodine (I) atoms in the polymerized hydrocarbon 706 can help generate EUV photoelectrons without capturing unstable hydrogen. In other examples, any suitable dopant precursor and any suitable hydrocarbon precursor can be used.

[0102] return Figure 5 , flow control hardware 514A may be controllable to flow gases from dopant precursor source 516, hydrocarbon precursor source 518, and hydrogen source 520 into process chamber 502 to deposit a hydrogen-supply photosensitive bottom layer. Prior to introducing radical species into process chamber 502, ions and / or radiation from remote plasma generator 530 are filtered by ion shield and radiation shield inlet 510. Figure 5 In the example of , the chemicals are introduced from one side of the processing chamber 502. Therefore, the precursor gas is introduced from downstream of the ion shielding and radiation shielding inlet 510. The introduction of the dopant precursor from downstream of the ion shielding and radiation shielding inlet 510 can help filter ions and / or high-energy radiation to prevent the breaking of the bond between the EUV absorbing photoelectron emitting dopant and the carbon-containing polymerizable ligand in the dopant precursor. Hydrogen is introduced into the chamber from the hydrogen source 520 downstream of the ion shielding and radiation shielding inlet 510 to introduce the entrained hydrogen into the hydrogen supply photosensitive bottom layer. In some examples, the entrained hydrogen can be introduced into the hydrogen supply photosensitive layer via the flow control hardware 514B and the remote plasma generator 530. In such an example, the connection of the hydrogen source 520 to the flow control hardware 514A can be omitted.

[0103] Remote plasma generator 530 is configured to generate remote plasma from an inert gas and a radical precursor to generate radical species. In some examples, remote plasma generator 530 may be configured to generate an inductively coupled plasma (ICP). In other examples, remote plasma generator 530 may be configured to generate a capacitively coupled plasma (CCP). In further examples, microwave plasma may be used. Radical species may flow into the processing chamber through ion shielding and radiation shielding inlet 510. Suitable inert gases include He, Ne, Ar, Kr, and N2. Suitable radical precursors include hydrogen, deuterium, ammonia, and hydrazine. Flow control hardware 514A-514B schematically represent any suitable components that are related to causing gases to flow into the processing chamber 502.

[0104] The flow control hardware 514A-514B may include one or more mass flow controllers and / or valves to control the flow rates of the gases. In some examples, the flow control hardware is controllable to adjust the flow ratio between the two gases. For example, the flow control hardware may be controllable to flow the hydrocarbon precursor and the dopant precursor at a gas flow ratio in the range of 2:1 to 100:1 measured in standard cubic centimeters (sccm).

[0105] In some examples, liquid precursors may be used for dopant precursor source 516 and / or hydrocarbon precursor source 518. In such examples, the liquid precursors may be introduced as a flow over vapor (FOV) along with a carrier gas. In such examples, flow control hardware 514A may be configured to introduce the liquid precursors into the process chamber using the FOV.

[0106] The processing tool 500 also includes an exhaust system 532. The exhaust system 532 is configured to receive gases flowing from the processing chamber 502. In some examples, the exhaust system 532 is configured to actively remove gases and / or apply a partial vacuum from the processing chamber 502. The exhaust system 532 can include any suitable hardware, including one or more pumps.

[0107] As described above, remote plasma generator 530 is configured to form free radical species using plasma. Free radical species can promote the reaction between dopant precursors and hydrocarbon precursors. For example, by reacting with unsaturated carbon-carbon bonds and / or opening cyclic functional groups, free radicals can initiate polymerization. Plasma can be formed by the gas supplied by inert gas source 522. In the depicted example, hydrogen from hydrogen source 520 serves as a free radical precursor. In other examples, free radical precursors other than hydrogen can be used. As described above, suitable free radical precursors include hydrogen, deuterium, ammonia and hydrazine. Inert gas source 522 can include any suitable inert gas, such as He, N2, Ne, Ar or Kr. In some more specific examples, H / He plasma is used.

[0108] The processing tool 500 also includes a radio frequency (RF) power source 534 electrically connected to the remote plasma generator 530. The processing tool 500 may also include a matching network 536 for impedance matching of the RF power source 534. The RF power source 534 can be configured for any suitable frequency and power. Examples of suitable frequencies include frequencies in the range of 0.3 MHz to 10 GHz. Examples of suitable powers include powers in the range of 10 W to 10 kW. In some examples, the RF power source 534 is configured to operate at a plurality of different frequencies and / or powers.

[0109] The controller 550 is operatively coupled to the substrate heater 508, the flow control hardware 514A-514B, the remote plasma generator 530, the exhaust system 532, and the RF power supply 534. The controller 550 may also be operatively coupled to any other suitable components of the processing tool 500. The controller 550 is configured to control various functions of the processing tool 500 to deposit a hydrogen photosensitive underlayer including a bonded EUV absorbing photoelectron emitting dopant on the substrate 506. For example, the controller 550 is configured to operate the substrate heater 508 to heat the substrate. The controller 550 is also configured to operate the flow control hardware 514A to flow a selected gas or gas mixture into the processing chamber 502 at a selected flow rate. The controller 550 is also configured to operate the exhaust system 532 to remove gases from the processing chamber 502. The controller 550 is also configured to operate the flow control hardware 514A-514B and the exhaust system 532 to maintain a selected pressure within the processing chamber 502. In addition, the controller 550 is configured to operate the remote plasma generator 530 and / or the RF power supply 534 to form a plasma including an inert gas and / or hydrogen gas, as well as control any other functions of the processing tool 500. The controller 550 may include any suitable computer system, examples of which are described below with reference to Fig. 9 Give a description.

[0110] For example, the controller 550 may operate the flow control hardware 514A to introduce a dopant precursor and a hydrocarbon precursor into the process chamber 502, thereby exposing the substrate 506 to the precursor gas. The controller 550 may also operate the flow control hardware to introduce an inert gas and / or a radical precursor into the remote plasma generator 530. The controller 550 may also operate the remote plasma generator 530 and / or the RF power source 534 to form a plasma and introduce radical species into the process chamber 502. Thus, the controller 550 may control the introduction of the precursor gas and the radical species into the process chamber 502, so that the radical species reacts with one or more of the dopant precursor and the hydrocarbon precursor to form a hydrogen-donating photosensitive bottom layer on the substrate 506.

[0111] In some examples, alternatively or additionally, the introduction of the dopant precursor can be temporally separated from the introduction of the radical species.For example, the flow control hardware and the remote plasma generator can be configured to alternately expose the substrate to the precursor gas and to the radical species.

[0112] Figure 8 A flow chart is shown depicting an exemplary method 800 for forming a hydrogen-donating photosensitive underlayer on a substrate. Processing tool 500 is an exemplary tool for performing method 800. Method 800 includes exposing a substrate to a dopant precursor and a hydrocarbon precursor at 802. The dopant precursor includes an EUV absorbing photoelectron emitting dopant bonded within a carbon-containing polymerizable molecule. In some examples, at 804, the method includes introducing the dopant precursor downstream of an ion shielding and radiation shielding structure of an inlet. In examples where plasma is used to form free radical species, 804 can help prevent bond breakage between the EUV absorbing photoelectron emitting dopant and the carbon-containing polymerizable ligand in the example.

[0113] In some examples, the carbon-containing polymerizable molecule includes one or more of a carbon-carbon double bond, a carbon-carbon triple bond, or a cyclic group, as shown at 806. For example, the carbon-containing polymerizable molecule may include vinyl, ethynyl, allyl, propenyl, butenyl, and / or cyclopropyl ligands. As shown at 808, in some examples, the dopant precursor includes one or more of iodoacetylene or 3-iodopropene. As shown at 810, in some examples, the dopant precursor includes one or more of dimethyltin (II), diethyltin (II), tetravinyltin (IV), or dimethyl (divinyl) tin (IV).

[0114] At 812, in some examples, method 800 includes mixing the hydrocarbon precursor with hydrogen before exposing the substrate to the hydrocarbon precursor. In some examples, at 814, the method includes flowing a ratio of a hydrocarbon precursor gas flow in sccm to a dopant precursor gas flow in sccm in a range of 2:1 to 100:1.

[0115] Continuing, method 800 also includes exposing the substrate to radical species formed by the plasma at 816. In some examples, the method includes introducing the radical species into the processing chamber including the substrate through the ion shielding and radiation shielding inlet at 818. In such examples, the dopant precursor may be introduced from the ion shielding and radiation shielding structure downstream of the ion shielding and radiation shielding inlet, as shown at 804.

[0116] Continuing, at 820, method 800 also includes forming a hydrogen-donating photosensitive bottom layer on the substrate from the dopant precursor and the hydrocarbon precursor by reacting one or more of the dopant precursor and the hydrocarbon precursor with the radical species. In some examples, at 822, the method also includes controlling a substrate heater to heat to a temperature in a range of 100° C. to 300° C.

[0117] Thus, the disclosed examples may provide a hydrogen-donating photosensitive underlayer comprising a bonded EUV absorbing photoelectron emitting dopant. When used in a patterned stack, the EUV absorbing photoelectron emitting dopant may absorb at least some of the EUV light absorbed by the uncovered photoresist layer. The EUV absorbing photoelectron emitting dopant may generate photoelectrons that help drive crosslinking reactions in the photoresist and / or may generate additional unstable hydrogen that promotes crosslinking reactions in the photoresist. Because the EUV absorbing photoelectron emitting dopant is bonded to atoms in the hydrogen-donating photosensitive underlayer, such an underlayer may reduce the risk of dopant hydrides being formed from unstable hydrogen in the hydrogen-donating photosensitive underlayer. Thus, the disclosed examples may help improve yields by reducing EUV photoresist exposure time and / or dose. For example, the disclosed examples may achieve a dose ratio size of ≤50 mJ / cm for EUV photoresist. 2 . The disclosed examples may also facilitate the formation of well-defined features in transition regions. For example, the disclosed examples may be used to form features including a pitch of ≤36 nm. In some examples, features may be formed that include a line width roughness of ≤3 nm measured using after development inspection (ADI). In some examples, features may be formed that include a local critical dimension uniformity of ≤4 nm measured using ADI. In addition, the disclosed examples may provide approximately 20% improvement in complex patterning (fidelity) compared to other examples that omit the use of EUV absorbing photoelectron emitting dopants that bond to atoms in the hydrogen-donating photoresist bottom layer. Although disclosed in the context of EUV photoresists, the disclosed examples may also be used with any other suitable photoresists, including photoresists that absorb in spectra other than EUV wavelengths.

[0118] In some embodiments, the methods and processes described herein may be combined with a computing system of one or more computing devices. Specifically, such methods and processes may be implemented as a computer application or service, an application programming interface (API), a library, and / or other computer program products.

[0119] Fig. 9A non-limiting embodiment of a computing system 900 is schematically shown that can perform one or more of the above methods and processes. The computing system 900 is shown in simplified form. The computing system 900 can take the form of one or more personal computers, workstations, computers integrated with wafer processing tools, and / or network accessible server computers.

[0120] The computing system 900 includes a logic machine 902 and a storage machine 904. The computing system 900 may optionally include a display subsystem 906, an input subsystem 908, a communication subsystem 910, and / or Fig. 9 Controller 550 is an example of computing system 900.

[0121] The logic machine 902 includes one or more physical devices configured to execute instructions. For example, the logic machine can be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions can be implemented to perform tasks, implement data types, transform the state of one or more components, achieve technical effects, or otherwise achieve desired results.

[0122] The logic machine may include one or more processors configured to execute software instructions. Additionally or alternatively, the logic machine may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. The processors of the logic machine may be single-core or multi-core, and the instructions executed thereon may be configured for sequential, parallel and / or distributed processing. The various components of the logic machine may optionally be distributed in two or more separate devices that may be remotely located and / or configured for coordinated processing. Various aspects of the logic machine may be virtualized and executed by a remotely accessible networked computing device configured in a cloud computing configuration.

[0123] The storage machine 904 includes one or more physical devices configured to store instructions 912 that can be executed by a logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of the storage machine 904 can be transformed—for example, to store different data.

[0124] The storage machine 904 may include removable and / or built-in devices. The storage machine 904 may include optical storage (e.g., CD, DVD, HD-DVD, Blu-ray disc, etc.), semiconductor storage (e.g., RAM, EPROM, EEPROM, etc.), and / or magnetic storage (e.g., hard disk drive, floppy disk drive, tape drive, MRAM, etc.). The storage machine 904 may include volatile, non-volatile, dynamic, static, read / write, read-only, random access, sequential access, location addressable, file addressable, and / or content addressable devices.

[0125] It should be understood that storage 904 includes one or more physical devices. However, alternatively, aspects of the instructions described herein may be propagated via a communication medium (eg, electromagnetic signals, optical signals, etc.) that is not held for a finite duration by a physical device.

[0126] Aspects of the logic machine 902 and the storage machine 904 may be integrated together into one or more hardware logic components. For example, such hardware logic components may include field programmable gate arrays (FPGAs), program and application specific integrated circuits (PASIC / ASIC), program and application specific standard products (PSSP / ASSP), systems on chips (SOCs), and complex programmable logic devices (CPLDs).

[0127] When included, display subsystem 906 can be used to present a visual representation of the data stored by storage machine 904. This visual representation can take the form of a graphical user interface (GUI). Since the methods and processes described herein change the data held by the storage machine, and therefore change the state of the storage machine, the state of display subsystem 906 can also be converted to visually represent the change of the underlying data. Display subsystem 906 can include one or more display devices using almost any type of technology. Such display device can be combined with logic machine 902 and / or storage machine 904 in a shared cabinet (a shared enclosure), or such display device can be a peripheral display device.

[0128] When included, the input subsystem 908 may include or may interact with one or more user input devices (e.g., a keyboard, mouse, or touch screen). In some embodiments, the input subsystem may include or interact with selected natural user input (NUI) components. Such components may be integrated or peripheral, and the conversion and / or processing of input actions may be handled on-board or off-board. Exemplary NUI components may include microphones for voice and / or sound recognition, and infrared, color, stereo, and / or depth cameras for machine vision and / or gesture recognition.

[0129] When included, the communication subsystem 910 can be configured to communicatively couple the computing system 900 with one or more other computing devices. The communication subsystem 910 can include wired and / or wireless communication devices compatible with one or more different communication protocols. As a non-limiting example, the communication subsystem can be configured to communicate using a wireless telephone network, or a wired or wireless local area network or wide area network. In some embodiments, the communication subsystem can allow the computing system 900 to send messages to other devices and / or receive messages from other devices through a network such as the Internet.

[0130] It should be understood that the configuration and / or method described herein is exemplary in nature, and these specific one or more embodiments should not be considered as restrictive, because many variations are possible. The specific routine or method described herein can represent one or more of any number of processing strategies. Therefore, the various actions shown and / or described can be performed in the order shown and / or described, in other orders, in parallel or omitted. Similarly, the order of the above-mentioned process can be changed.

[0131] The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems and configurations, and other features, functions, acts, and / or properties disclosed herein, as well as any and all equivalents thereof.

Claims

1. A method for forming a light-sensitive bottom layer on a substrate, the method comprising: exposing the substrate to a dopant precursor and a hydrocarbon precursor, the dopant precursor comprising an extreme ultraviolet (EUV) absorbing photoelectron emitting dopant bonded within a carbon-containing polymerizable molecule; exposing the substrate to free radical species; as well as Through the reaction of the dopant precursor and the hydrocarbon precursor with the radical species, a hydrogen-donating photosensitive underlayer is formed on the substrate from the dopant precursor and the hydrocarbon precursor.

2. The method of claim 1 , wherein exposing the substrate to the free radical species comprises: The radical species are introduced from a remote plasma into a processing chamber including the substrate through an ion shielded and radiation shielded inlet.

3. The method of claim 2, wherein the dopant precursor is introduced into an ion shielding and radiation shielding structure downstream of the ion shielding and radiation shielding inlet.

4. The method of claim 1, wherein the carbon-containing polymerizable molecule comprises one or more of a carbon-carbon double bond, a carbon-carbon triple bond, or a cyclic group.

5. The method of claim 1, further comprising mixing the hydrocarbon precursor with a hydrogen-containing gas prior to exposing the substrate to the hydrocarbon precursor. The method of claim 1 , wherein the dopant precursor comprises an iodine-containing dopant precursor.

7. The method of claim 6, wherein the iodine-containing dopant precursor comprises one or more of iodoacetylene or 3-iodopropylene.

8. The method of claim 1, wherein the dopant precursor comprises a tin-containing dopant precursor.

9. The method of claim 8, wherein the tin-containing dopant precursor comprises one or more of dimethyltin(II), diethyltin(II), tetravinyltin(IV), or dimethyl(divinyl)tin(IV).

10. The method of claim 1, wherein a ratio of a hydrocarbon precursor gas flow rate in standard cubic centimeters per minute (sccm) to a dopant precursor gas flow rate in sccm is in a range of 2:1 to 100:

1.

11. The method of claim 1, further comprising controlling a substrate heater to heat to a temperature in a range of 100°C to 300°C.

12. A patterned stack disposed on a substrate, the patterned stack comprising: a photoresist layer; as well as The hydrogen-donating photosensitive underlayer is disposed between the photoresist layer and the substrate, and includes an extreme ultraviolet (EUV) absorbing photoelectron emitting dopant, wherein the EUV absorbing photoelectron emitting dopant is bonded to atoms in the hydrogen-donating photosensitive underlayer.

13. The patterned stack of claim 12, wherein the hydrogen-donating photosensitive underlayer comprises silicon carbide.

14. The patterned stack of claim 12, wherein the hydrogen donating photosensitive underlayer comprises a carbon-based polymer.

15. The patterned stack of claim 12, wherein the EUV light absorbing photoelectron emitting dopant comprises one or more of In, Sn, Sb, Te, or I.

16. The patterned stack of claim 12, wherein the photoresist layer comprises extreme ultraviolet (EUV) photoresist.

17. The patterned stack of claim 16, wherein the EUV photoresist comprises a tin-based metal oxide photoresist.

18. A processing tool comprising: Processing room; Plasma generator; a radio frequency power supply configured to provide radio frequency power to the plasma generator; flow control hardware configured to control the flow of gases into the processing chamber and into the plasma generator; Logical subsystem; as well as a storage subsystem comprising instructions executable by the logic subsystem to: controlling the flow control hardware to introduce a dopant precursor and a hydrocarbon precursor into the process chamber, the dopant precursor comprising an extreme ultraviolet (EUV) absorbing photoelectron emitting dopant bonded within a carbon-containing polymerizable molecule, controlling the flow control hardware to introduce an inert gas into the plasma generator; controlling the radio frequency power source to form plasma in the plasma generator; as well as The flow control hardware is controlled to introduce a radical species precursor into the plasma generator.

19. The processing tool of claim 18, further comprising a dopant precursor gas source, wherein the dopant precursor gas source comprises one or more of an iodine-containing dopant or a tin-containing dopant.

20. The processing tool of claim 18, further comprising an ion shield and radiation shield inlet connecting the plasma generator and the processing chamber.

21. The processing tool of claim 18, wherein the instructions are executable to control the flow control hardware to flow the hydrocarbon precursor and to flow the dopant precursor with a gas flow ratio in a range of 2 sccm:1 sccm to 10 sccm:1 sccm.

22. The processing tool of claim 18, further comprising a substrate heater, and wherein the instructions are further executable to control the substrate heater to heat to a temperature in the range of 100°C to 300°C.

Images