Methods and apparatuses using tunable reactive gas source

Abstract

Photon-activated species such as reactive radicals are generated using a tunable light source in a semiconductor processing apparatus. Reactant gases in a ground state are flowed into an optical cavity of the semiconductor processing apparatus. The reactant gases are exposed to radiation from the tunable light source to dissociate the reactant gases, form reactive radicals, and / or energize reactive radicals from a ground state to excited state. The light source may be tuned to: (1) a specified intensity and / or (2) specified wavelength or range of wavelengths to control the energies or energy distribution of the photon-activated species. The photon-activated species generated by the tunable light source may be applied to etch materials on a semiconductor substrate, treat a surface of the semiconductor substrate, clean the surface of the semiconductor substrate, deposit one or more materials on the semiconductor substrate, or clean internal surfaces of a processing chamber.

Description

METHODS AND APPARATUSES USING TUNABEE REACTIVE GAS SOURCEINCORPORATION BY REFERENCE

[0001] A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in its entirety and for all purposes.FIELD

[0002] The present disclosure relates to semiconductor processing apparatuses and tools used in semiconductor manufacturing operations.BACKGROUND

[0003] As the semiconductor device industry has continued to advance, semiconductor processing apparatuses and tools using reactive gases to process semiconductor substrates have become increasingly crucial. Reactive gases can be applied in a wide variety of semiconductor processing applications. Reactive gases may be used to deposit materials on a substrate surface. Reactive gases may be used to etch materials such as silicon oxide, silicon, silicon nitride, metal or metal oxide, silicon-germanium, and many other materials. Many semiconductor fabrication operations involve selectively etching one or more materials in a semiconductor substrate. Reactive gases may be used to clean internal surfaces of a semiconductor processing chamber. Reactive gases may be used to treat or clean substrate surfaces. Reactive gases may be used to deposit materials on substrate surfaces. In some cases, the reactivity of reactive gases may be increased by forming plasma of the reactive gases.

[0004] Plasma has long been employed for processing substrates. Plasma processes are commonly used in the fabrication of semiconductor devices. High-energy ions and radicals from the plasma may be used to react with materials on a substrate surface. Alternatively, high-energy ions and radicals from the plasma may be used to clean internal surfaces of a semiconductor processing chamber. However, such high-energy ions and radicals generated by plasma sources result in a high concentration of energetic species with broad energy distributions. This can cause substrate damage, material selectivity issues, and incompatibility with applications requiring isotropic etching.

[0005] The background description provided herein is for the purpose of generally presenting the context of the present technology. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwisequalify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.SUMMARY

[0006] Provided herein is semiconductor processing apparatus. The semiconductor processing apparatus includes a processing chamber, a substrate support configured to support a semiconductor substrate in the processing chamber, a gas distributor in fluid communication with the processing chamber, a gas source in fluid communication with the gas distributor, wherein the gas source is configured to supply one or more reactant gases to the gas distributor, and a light source configured to emit radiation to produce photon-activated species of at least one of the reactant gases.

[0007] In some implementations, the light source is tuned to emit radiation having: (1) a selected intensity and, (2) a selected wavelength or range of wavelengths to obtain a desired energy distribution of the photon-activated species. In some implementations, the light source is tuned according to the selected wavelength or range of wavelengths to achieve a target etch rate and selectivity of one or more materials to be etched on the semiconductor substrate. In some implementations, the light source is tuned according to the selected intensity to achieve a target etch rate and selectivity of one or more materials to be etched on the semiconductor substrate. In some implementations, the one or more reactant gases comprise a mixture of reactant gases, where the light source is tuned according to the selected wavelength or range of wavelengths to selectively produce photon-activated species of one of the reactant gases in the mixture relative to a remainder of the reactant gases in the mixture. In some implementations, the semiconductor processing apparatus further includes an optical cavity optically coupled to the light source to receive the radiation from the light source, where the at least one of the reactant gases is converted into the photon-activated species in the optical cavity. In some implementations, the optical cavity includes a gas cell through which the one or more reactant gases flow through and an optical cell that surrounds the gas cell or sits above the gas cell, where the light source is positioned on one or more surfaces of the optical cell to emit the radiation through the gas cell. In some implementations, the optical cell has a geometry different than the gas cell. In some implementations, the optical cell has a cylindrical, rectangular, or octagonal geometry. In some implementations, the optical cell includes one or more mirrors or a reflective material to reflect the emitted radiation from the light source. In some implementations, the gas cell includes one or more mirrors or a reflective material to reflect the emitted radiation from the light source. In some implementations, a material of the gas cell is transparent or substantially transparent to the emitted radiation from the light source. In some implementations, the optical cell includes a window thatsits above the gas cell, where the light source is disposed on the window and includes a plurality of light-emitting diodes (LEDs) that emit the radiation into the gas cell. In some implementations, the optical cell includes a ring that surrounds the gas cell, where the light source is disposed on the ring and includes a plurality of LEDs that emit the radiation into the gas cell. In some implementations, the optical cavity includes one or more mirrors or reflective surfaces. In some implementations, the optical cavity is free of any mirrors or reflective surfaces. In some implementations, the light source includes a laser. In some implementations, the light source includes a flash lamp. In some implementations, the light source includes a plurality of LEDs. In some implementations, the plurality of LEDs includes a first LED configured to emit radiation at a first wavelength and a second LED configured to emit radiation at a second wavelength different than the first wavelength. In some implementations, the light source is further configured to expose the semiconductor substrate to the emitted radiation to promote or hinder surface reactions on the semiconductor substrate. In some implementations, the light source includes a plurality of LEDs positioned above the gas distributor, where the gas distributor is transparent or substantially transparent to the emitted radiation. In some implementations, the optical cavity is positioned between the gas distributor and the gas source so that photon activation occurs prior to the gas distributor. In some implementations, the optical cavity is positioned in the gas distributor so that photon activation occurs in the gas distributor. In some implementations, the optical cavity is positioned in the processing chamber so that photon activation occurs in the processing chamber. In some implementations, the one or more reactant gases include a halogen gas, a hydrogen halide, an oxidant gas, nitrogen trifluoride, nitrous oxide, nitric oxide, nitrogen dioxide, methane, fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof. In some implementations, the photon-activated species of the at least one of the reactant gases includes molecular radicals in a ground or excited state, atomic radicals in a ground or excited state, and / or energized reactant gases in an excited vibrational state.

[0008] Also provided herein is a semiconductor processing apparatus. The semiconductor processing apparatus includes a processing chamber, a substrate support configured to support a semiconductor substrate in the semiconductor processing chamber, a gas distributor in fluid communication with the semiconductor processing chamber, a gas source in fluid communication with the gas distributor, where the gas source is configured to supply one or more reactant gases in a ground state to the gas distributor, a light source configured to emit radiation and tuned to: (1) a selected intensity and (2) a selected wavelength or range of wavelengths, and an optical cavity positioned between the gas source and the gas distributor, where the optical cavity is configuredto receive radiation from the light source and convert the one or more reactant gases into photon- activated species in the optical cavity.

[0009] Also provided herein is a semiconductor processing apparatus. The semiconductor processing apparatus includes a semiconductor processing chamber, a substrate support configured to support a semiconductor substrate in the semiconductor processing chamber, a gas distributor in fluid communication with the semiconductor processing chamber, a gas source in fluid communication with the gas distributor, where the gas source is configured to supply one or more reactant gases in a ground state to the gas distributor, and a light source configured to emit radiation and tuned to: (1) a selected intensity and (2) a selected wavelength or range of wavelengths, where the gas distributor serves as an optical cavity configured to receive radiation from the light source and convert the one or more reactant gases into photon-activated species in the gas distributor.

[0010] Also provided herein is a semiconductor processing apparatus. The semiconductor processing apparatus includes a processing chamber, a substrate support configured to support a semiconductor substrate in the processing chamber, a gas distributor in fluid communication with the processing chamber, a gas source in fluid communication with the gas distributor, where the gas source is configured to supply one or more reactant gases in a ground state to the gas distributor, and a light source configured to emit radiation and tuned to: (1) a selected intensity and (2) a selected wavelength or range of wavelengths, where the processing chamber serves as an optical cavity configured to receive radiation from the light source and convert the one or more reactant gases into photon-activated species in the processing chamber.

[0011] Also provided herein is a method of generating photon-activated species for use in a processing chamber. The method includes flowing one or more reactant gases towards a gas distributor for distributing the one or more reactant gases into the processing chamber, emitting radiation from a light source at: (1) a selected intensity and (2) a selected wavelength or range of wavelengths, and producing photon-activated species of at least one of the reactant gases in an optical cavity by exposing the one or more reactant gases to the emitted radiation from the light source.

[0012] In some implementations, the method further includes etching one or more materials on a semiconductor substrate in the processing chamber by exposing the semiconductor substrate to the photon-activated species. In some implementations, the one or more materials are etched at an etch rate and selectivity based at least in part on one or both of: (1) the selected intensity and (2) the selected wavelength or range of wavelengths. In some implementations, etching the one or more materials includes etching silicon oxide relative to silicon and / or silicon nitride, where the photon-activated species includes radicals of an oxygen-containing gas and / or hydrogen-containing gas. In some implementations, etching the one or more materials includes etching silicon relative to silicon oxide and / or silicon nitride, where the photon-activated species includes radicals of a halogen gas and / or methane gas. In some implementations, etching the one or more materials includes etching silicon relative to silicon-germanium, silicon oxide, silicon nitride, or combinations thereof, where the photon-activated species includes radicals of a nitrogencontaining gas mixed with a fluorine-containing gas and / or hydrogen-containing gas. In some implementations, etching the one or more materials includes etching silicon nitride relative to silicon oxide, silicon, silicon-germanium, or combinations thereof, where the photon-activated species includes radicals of a fluorine-containing gas and / or nitrogen-containing gas. In some implementations, etching the one or more materials includes etching a metal or metal oxide, where the photon-activated species includes radicals of a fluorine-containing gas. In some implementations, the method further includes treating a surface of the semiconductor substrate by exposing the semiconductor substrate to the photon-activated species to desorb etch byproducts from the surface of the semiconductor substrate. In some implementations, etching the one or more materials includes etching silicon-germanium relative to silicon, where the photon-activated species includes radicals of a fluorine-containing species and / or chlorine-containing species. In some implementations, a concentration of the photon-activated species for etching the one or more materials is tunable by controlling: (1) the selected intensity of the emitted radiation and (2) the selected wavelength of the emitted radiation. In some implementations, the method further includes treating a surface of a semiconductor substrate in the processing chamber by exposing the semiconductor substrate to the photon-activated species. In some implementations, the method further includes cleaning internal surfaces of the processing chamber by exposing the internal surfaces to the photon-activated species. In some implementations, the optical cavity is upstream of the gas distributor, integrated with the gas distributor, or integrated with the processing chamber. In some implementations, the optical cavity includes one or more mirrors or a reflective material configured to reflect the radiation emitted from the light source in the optical cavity. In some implementations, the light source includes a plurality of LEDs, where the plurality of LEDs emit at the same wavelength or a combination of different wavelengths. In some implementations, the photon-activated species are produced independent of any plasma. In some implementations, the photon-activated species includes molecular radicals in a ground or excited state, atomic radicals in a ground or excited state, and / or energized reactant gases in an excited vibrational state. In some implementations, the one or more reactant gases comprise a halogen gas, a hydrogen halide, an oxidant gas, nitrogen trifluoride, nitrous oxide, nitric oxide, nitrogen dioxide, methane,fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof.BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 shows a schematic illustration of an example plasma processing apparatus that generates plasma comprising high-energy ions and radicals according to some implementations.

[0014] Figure 2 shows a schematic illustration of an example plasma processing apparatus that generates plasma comprising high-energy ions and radicals according to some other implementations.

[0015] Figure 3A shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species and an optical cavity between a gas distributor and gas source according to some implementations.

[0016] Figure 3B shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species and an optical cavity between a gas distributor and gas source according to some other implementations.

[0017] Figure 3C shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a gas distributor according to some implementations.

[0018] Figure 3D shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a gas distributor according to some other implementations.

[0019] Figure 3E shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a processing chamber according to some implementations.

[0020] Figure 3F shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a processing chamber according to some other implementations.

[0021] Figure 4 shows a graph illustrating light absorption of halogen gases as a function of wavelength associated with radiation emitted from a light source according to some implementations.

[0022] Figure 5 shows a schematic illustration of an example optical cavity that includes an optical cell with a light source and a gas cell through which one or more reactant gases pass through according to some implementations.

[0023] Figure 6A shows a schematic illustration of an example optical cavity that includes a rectangular optical cell and a cylindrical gas cell according to some implementations.

[0024] Figure 6B shows a schematic illustration of an example optical cavity that includes a cylindrical optical cell and a cylindrical gas cell according to some implementations.

[0025] Figure 6C shows a schematic illustration of an example optical cavity that includes an octagonal optical cell and a cylindrical gas cell according to some implementations.

[0026] Figure 6D shows a schematic illustration of an example optical cavity that includes a circular window that sits above a gas cell according to some implementations.

[0027] Figure 6E shows a schematic illustration of an example optical cavity that includes an annular window that surrounds a gas cell according to some implementations.

[0028] Figure 7A shows a schematic illustration of an example semiconductor processing apparatus including a light source positioned above a gas distributor, where the light source may be configured to generate photon-activated species in an optical cavity, according to some implementations.

[0029] Figure 7B shows a schematic illustration of an example semiconductor processing apparatus including a light source positioned above a gas distributor, where the light source may be configured to illuminate a semiconductor substrate in a processing chamber, according to some implementations.

[0030] Figure 8 shows a plan view of a schematic illustration of an example light source including a plurality of light-emitting diodes (LEDs) for emitting radiation at different wavelengths according to some implementations.

[0031] Figure 9A shows a flow diagram of an example method for generating photon-activated species for use in a processing chamber according to some implementations.

[0032] Figure 9B shows a flow diagram of an example method for generating and using photon- activated species in a processing chamber according to some implementations.

[0033] Figure 10 shows a schematic diagram of an example process tool for performing the disclosed implementations.DETAILED DESCRIPTION

[0034] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all the specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0035] The implementations disclosed below may describe processing of a material on a substrate such as a wafer, substrate, or other work piece. The work piece may be of various shapes, sizes, and materials. In this application, the terms “semiconductor wafer,” “wafer,” “substrate,” “wafer substrate,” and “partially fabricated integrated circuit” are used interchangeably. One of ordinary skill in the art would understand that the term “partially fabricated integrated circuit” can refer to a silicon wafer during any of many stages of integrated circuit fabrication thereon. A wafer or substrate used in the semiconductor device industry typically has a diameter of 200 mm, or 300 mm, or 450 mm. Unless otherwise stated, the processing details recited herein (e.g., flow rates, power levels, etc.) are relevant for processing 300 mm diameter substrates, or for treating chambers that are configured to process 300 mm diameter substrates and can be scaled as appropriate for substrates or chambers of other sizes. In addition to semiconductor wafers, other work pieces that may be used implementations disclosed herein include various articles such as printed circuit boards and the like. The processes and apparatuses can be used in the fabrication of semiconductor devices, displays, LEDs, photovoltaic panels and the like.Introduction

[0036] Plasma has long been employed for processing substrates and semiconductor devices. Plasma generation may employ capacitively-coupled plasma technology, inductively-coupled plasma technology, electron-cyclotron technology, or microwave technology. Plasma is generated by supplying a plasma-generation chamber with reactant gases and applying a strong radiofrequency (RF) electromagnetic field. Electrons are accelerated by the oscillating electric field, and the electrons collide with the reactant gas molecules to ionize the reactant gas molecules and strip them of their electrons, thereby creating a plasma of ions and more electrons. The plasma generally includes ions, electrons, neutral species or radicals in their excited states and ground states. Thus, the plasma may include charged species and uncharged species having both high kinetic energies and high chemical potentials. In some cases, high-energy ions and radicals from the plasma may be delivered to a substrate surface to etch one or more materials deposited on the substrate. In some cases, high-energy ions and radicals from the plasma may be delivered to a substrate surface to treat the substrate surface or remove contaminants. In some cases, high-energy ions and radicals from the plasma may be delivered to internal surfaces of a semiconductor processing chamber to clean the internal surfaces.

[0037] Figure 1 shows a schematic illustration of an example plasma processing apparatus that generates plasma comprising high-energy ions and radicals according to some implementations. The plasma processing apparatus 100 has a single processing chamber 110 with a substrate holder118 (e.g., a pedestal or electrostatic chuck) in an interior volume which may be maintained under vacuum or other desired chamber pressure by vacuum pump 130. A gas delivery system 102 and a showerhead 104 are fluidly coupled to the processing chamber 110 for the delivery of film precursors, carrier and / or purge and / or process gases, secondary reactants, etc. Equipment for generating a plasma within the processing chamber 110 is also shown in Figure 1.

[0038] The plasma processing apparatus 100 fluidly communicates with the gas delivery system 102 for delivering process gases. The gas delivery system 102 may include a mixing vessel 106 for blending and / or conditioning process gases for delivery to the showerhead 104. One or more mixing vessel inlet valves 108 A and 108B may control introduction of process gases to the mixing vessel 106.

[0039] Showerhead 104 distributes process gases and / or reactants (e.g., etch gases) toward the substrate 114, the flow of which is controlled by one or more valves upstream from the showerhead (e.g., valves 108A, 108B, and 116). The substrate 114 is located beneath the showerhead 104 and is shown resting on a substrate holder 118. A chamber space 120 is located beneath the showerhead 104. In some implementations, the substrate holder 118 may be raised or lowered to expose the substrate 114 to chamber space 120 and / or to vary a volume of the chamber space 120. The showerhead 104 and the substrate holder 118 are electrically connected to RF power supply 122 and matching network 124 for powering a plasma. In some implementations, the plasma energy may be controlled (e.g., via a system controller having appropriate machine-readable instructions and / or control logic) by controlling one or more of a process station pressure, a gas concentration, an RF source power, an RF source frequency, and a plasma power pulse timing. For example, RF power supply 122 and matching network 124 may be operated at any suitable power to form a plasma in the chamber space 120. The plasma may be a capacitively-coupled plasma that comprises high-energy ions and radicals. The plasma formed in the chamber space 120 may be used to etch one or more materials from the substrate 114, treat the substrate 114, deposit a film on the substrate 114, or clean internal surfaces of the processing chamber 110. The plasma processing apparatus 100 also includes a DC power supply 126 that is configured to provide a direct current to the substrate holder 118 in order to generate and provide an electrostatic clamping force to the substrate holder 118 and the substrate 114. The substrate holder 118 may also have one or more temperature control elements 128 that are configured to heat and / or cool the substrate 114.

[0040] Figure 2 shows a schematic illustration of an example plasma processing apparatus that generates plasma comprising high-energy ions and radicals according to some other implementations. The plasma processing apparatus 200 includes a remote plasma source 250 anda processing chamber 225 separate from the remote plasma source 250. The remote plasma source 250 is configured to generate a remote plasma 260. The remote plasma 260 may be an inductively- coupled plasma comprising high-energy ions and radicals. The high-energy ions and radicals of the remote plasma 260 may be introduced through a showerhead 254. A substrate 220 may be supported on a substrate support 210.

[0041] Process gases 202 may be supplied to the remote plasma source 250 via a gas distributor 252. One or more valves may control introduction of the process gases 202 into the remote plasma source 250. The remote plasma source 250 may be a container of any suitable shape, such as dome-shaped, conical-shaped, or cylindrical-shaped. Coils 256 may surround at least a portion of the container of the remote plasma source 250. The coils 256 may be in electrical communication with an RF power source for generating the remote plasma 260 in the remote plasma source 250. The remote plasma 260 may be ignited by energizing the coils 256 to form activated species 204, which may include high-energy ions and radicals. The activated species 204 pass through the showerhead 254 towards the substrate 220. The activated species 204 of the remote plasma 260 may be used to etch one or more materials from the substrate 220, treat the substrate 220, deposit a film on the substrate 220, or clean internal surfaces of the processing chamber 225.

[0042] In some implementations, an in situ plasma 230 may be generated between the showerhead 254 and the substrate support 210, where the in situ plasma may be a capacitively- coupled plasma. A gas or gas mixture 206 may be introduced into the processing chamber 225. An electric field may be generated between the showerhead 254 and the substrate support 210, and ionization of the gas or gas mixture 206 may ignite the in situ plasma 230 to form activated species including high-energy ions and radicals. In some implementations, the in situ plasma 230 may be used to etch one or more materials from the substrate 220, treat the substrate 220, deposit a film on the substrate 220, or clean internal surface of the processing chamber 225.

[0043] The plasma processing apparatus 200 may further include a controller 240. The controller 240 may be programmed to control various processes performed by the plasma processing apparatus 200, including delivery of gases, temperature settings, pressure settings, vacuum settings, power settings, RF generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, substrate transfers in and out of a tool and / or load locks, etc.Photon Activation in Semiconductor Processing Apparatus

[0044] Embodiments of the present disclosure use photons or photon-activated species in a semiconductor processing apparatus instead of plasma or plasma-activated species. Someembodiments of the present disclosure relate to a reactive gas source for generation of photon- activated species. Rather than generating highly energized ions and radicals by plasma ignition, the present disclosure generates photon-activated species so that the energies of the photon- activated species can be tuned, selected, or controlled. By exposing reactant gases to radiation emitted from a light source, such as a laser, lamp, or an array of LEDs, the reactant gases may be energized to form reactive radicals and / or energized molecules in an excited vibrational state. The light source can be tuned according to a specified wavelength and / or intensity to control the energy or energy distribution of the photon-activated species of the reactant gases. In a mixture of gases, a specific wavelength may be selected to photo-activate a targeted gas species while leaving all other gas species in an un-activated ground state. In some implementations, photon-activated species may include reactive radicals in an excited state, reactive radicals in the ground state, and / or energized reactant gases in an excited vibrational state. The photon-activated species may be employed to etch one or more materials on a semiconductor substrate, treat a surface of the semiconductor substrate, or clean internal surfaces of a processing chamber. In some embodiments, the photo-activated species may be used to perform other processing steps such as oxidation, nitridation, atomic layer etch, surface clean, deposition, etc.

[0045] In some embodiments of the present disclosure, a semiconductor processing apparatus is configured to generate photon-activated species. The semiconductor processing apparatus may include a processing chamber and a gas distributor (e.g., showerhead) for delivery of reactant gases into the processing chamber. A light source may be optically coupled to the processing chamber, the gas distributor, or an optical cavity upstream of the gas distributor. Reactant gases in the ground state may be exposed to the light source in the processing chamber, the gas distributor, or the optical cavity to produce photon- activated species of the reactant gases. For instance, the light source may include a plurality of LEDs configured to emit radiation from above a showerhead to produce the photon-activated species in an optical cavity above the showerhead. In some cases, the plurality of LEDs may be configured to emit radiation through the showerhead to expose the semiconductor substrate directly to the radiation. In some implementations, exposing the semiconductor substrate directly to the radiation may promote or hinder surface reactions. In some implementations, the photon-activated species generated in the processing chamber, gas distributor, or optical cavity may be employed to etch one or more materials on the semiconductor substrate, treat a surface of the semiconductor substrate, or clean internal surfaces of the processing chamber. In some cases, the photon-activated species generated in the processing chamber, gas distributor, or optical cavity may be employed to deposit materials on the semiconductor substrate, clean the surface of the semiconductor substrate, perform oxidation, perform nitridation, orperform atomic layer etc.

[0046] Figures 3 A-3F show schematic illustrations of various configurations for implementing a light source in a semiconductor processing apparatus for generation of photon-activated species. The light source may be tunable. In Figures 3A-3F, the semiconductor processing apparatus 300 includes a processing chamber 310 and a substrate support 320 configured to support a substrate 322 in the processing chamber 310. In some implementations, the substrate support 320 is a pedestal or electrostatic chuck. The semiconductor processing apparatus 300 further includes a gas distributor 330 in fluid communication with the processing chamber 310. The gas distributor 330 is configured to distribute process gases and reactants into the processing chamber 310. In some implementations, the gas distributor 330 may be configured to distribute the process gases and reactants towards the substrate 322. In some implementations, the gas distributor 330 is a showerhead.

[0047] The semiconductor processing apparatus 300 may further include a gas source 340. The gas source 340 is upstream of the gas distributor 330 and provides one or more reactant gases. The one or more reactant gases may include molecular gases in a ground state. The ground state represents an energy state that is an unexcited energy state. Atoms or molecules can exist in either its ground state or excited state. The atoms or molecules can be excited in a number of different ways, such as excitation by plasma, excitation by photons, etc. After excitation to an excited state, the atom or molecule eventually relaxes to a lower energy state or ground state. Here, the one or more reactant gases provided by the gas source 340 have not undergone excitation by plasma or excitation by photons.

[0048] In some implementations, the one or more reactant gases include a halogen gas, a hydrogen halide, an oxidant gas, nitrogen trifluoride, nitrous oxide, nitric oxide, nitrogen dioxide, methane, fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof. Example halogen gases include fluorine (F2), chlorine (Ch), bromine (E ), and iodine (I2). Example hydrogen halides include hydrogen fluoride (HF), hydrogen chloride (HC1), hydrogen bromide (HBr), and hydrogen iodide (HI). Example oxidant gases include oxygen (O2), nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O), nitrous acid (HONO), water (H2O), hydrogen peroxide (H2O2), and ozone (O3). In some implementations, the one or more reactant gases include a fluorine-based species such as nitrogen trifluoride (NF3), carbon tetrafluoride (CF4), sulfur hexafluoride (SFe), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), silicon tetrafluoride (SiF4), hexafluorobutadiene (C4F6), hexafluoroethane (C2F6), tetrafluoroethylene (C2F4), germanium tetrafluoride (GeF4), or xenon difluoride (XeF2). In some implementations, the one or more reactant gases include a carbon-containing species such as carbonyl sulfide (COS), carbon monoxide (CO), carbon dioxide (CO2), or methane (CH4). In some implementations, the one or more reactant gases include a hydrogencontaining species such as ammonia (NH3), hydrogen (H2), or silane (SiEE). In some implementations, the one or more reactant gases include an amine species.

[0049] Typically, in a plasma, the reactant gases form high-energy ions and excited radicals. A radical is an atom or molecule that contains one or more unpaired valence electrons. Plasma is generally characterized by the presence of a significant fraction of charged particles in any combination of ions or electrons. Uncharged particles (e.g., radicals) are also present. Furthermore, both the charged species and the uncharged species in the plasma may have high thermal kinetic energy. The plasma may be characterized by particles with high thermal kinetic energy and high concentration of energetic species (ions and radicals). The high concentration of energetic species in the plasma may be characterized by a broad energy distribution. Without being limited by any theory, the varying amounts of charged and uncharged species in the plasma, the thermal kinetic energies of particles in the plasma, and the varying levels of excitation of particles may contribute to the broad energy distribution. More specifically, energies between reactive species in the plasma may differ by several electron-volts or tens of electron-volts (eV). In some cases, the energy distribution of reactive species in the plasma may be on the order of tens of eV.

[0050] Rather than activating and exciting the reactant gases by plasma, activation and excitation of the reactant gases may occur by photons. Electromagnetic radiation, such as ultraviolet (UV), visible, or infrared (IR) radiation, may be emitted by a light source. The energy of the photon is inversely proportional to the wavelength of the emitted radiation. The light source may emit radiation having one or more wavelengths within a narrow light source spectral line width. This narrow light source spectral line width provides a narrow energy distribution of photons, which can result in a tight energy distribution of reactive radicals. Excitation of reactant gases by photon energy can avoid ionization and avoid transmitting kinetic energy to the reactant gases. Instead, excitation of reactant gases by photon energy can produce excited radicals with a tight energy distribution. Additionally or alternatively, excitation of reactant gases by photon energy can produce reactant gases in an excited vibrational state.

[0051] Molecules in their ground state can be excited to an excited energy state by exposure to photon energy. Additionally or alternatively, molecules at their ground state can break apart and form radicals in a ground state or excited state by exposure to photon energy. The reactive radicals generated from the light source may be in molecular or atomic form.

[0052] The semiconductor processing apparatus 300 may further include a light source 350configured to emit electromagnetic radiation such as UV radiation, IR radiation, or visible light. In some implementations, UV radiation may have a wavelength between about 100 nm and about 400 nm, visible light may have a wavelength between about 400 nm and about 1000 nm, and IR radiation may have a wavelength greater than about 1000 nm. The light source 350 may be configured to emit radiation tuned to: (1) a selected wavelength or range of wavelengths and / or (2) a selected intensity. The one or more reactant gases provided by the gas source 340 may be exposed to the radiation emitted from the light source 350. Exposing the one or more reactant gases to the radiation emitted from the light source 350 produces photon-activated species of the one or more reactant gases. Specifically, the photon-activated species may include reactive radicals in a ground or excited state of the one or more reactant gases or energized reactant gases in an excited vibrational state. In some implementations, the light source 350 may be configured to emit radiation to directly illuminate the substrate 322.

[0053] In some implementations, the light source 350 may include any suitable laser or lamp, which may include but is not limited to mercury lamps, deuterium lamps, pulsed xenon lamps, excimer lamps, and excimer lasers. Such lamps / lasers may be tuned to provide an emission spectrum to excite and / or break down the one or more reactant gases. For example, the light source 350 may be a UV lamp or laser. UV light sources may produce UV radiation with wavelengths between about 100 nm and about 400 nm, where the UV radiation may have sufficient energy to break apart molecular species of the one or more reactant gases and / or form radicals in the excited state. However, it will be understood that the light source 350 may operate at other ranges of wavelengths, including visible light wavelengths and IR wavelengths. In some implementations, the light source 350 using a laser or lamp is tunable within a range of wavelengths, such as a range of wavelengths between about 193 nm and about 10 pm. The spectral line width is defined as the range of wavelengths over which a light source emits light. The spectral line width of the laser or lamp can be on the order of about 1 nm.

[0054] In some implementations, the light source 350 may include any suitable LED or an array of LEDs. An LED is a semiconductor light source that emits light having a wavelength based on an energy band gap of the semiconductor. The LED may emit IR light, visible light, or UV light. Example semiconductor materials for LEDs include but are not limited to gallium arsenide (GaAs), gallium phosphide (GaP), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), aluminum gallium phosphide (AlGaP), aluminum gallium indium phosphide (AlGalnP), aluminum gallium indium nitride (AlGalnN), aluminum gallium arsenide (AlGaAs), silicon carbide (SiC), silicon (Si), zinc selenide (ZnSe), aluminum nitride (AIN), and boron nitride (BN). In some implementations, the light source 350 using an LED or array of LEDsis tunable within a range of wavelengths, such as a range of wavelengths between about 193 nm and about 10 gm. The spectral line width of the LED or array of LEDs can be on the order of about 10 nm.

[0055] In some implementations, the light source 350 may be configured to emit a discrete wavelength. Lasers and LEDs may be capable of emitting radiation at a discrete wavelength. In some other implementations, the light source 350 may be configured to emit a broadband range of wavelengths. “Broadband” may refer to a light source having a wide spectral bandwidth (e.g., greater than about 50 nm). Whereas lasers and some types of LEDs are largely monochromatic light sources, broadband light sources such as an arc discharge lamp may are largely polychromatic light sources. Some other types of LEDs are also broadband light sources, e.g., white light LEDs. An array of LEDs comprising of LEDs emitting at different wavelengths may also be used.

[0056] In some implementations, the light source 350 may operate in a continuous mode or pulsing mode. In some implementations, the light source 350 may be positioned relative to the surface of the substrate 322 to expose the surface of the substrate 322 to its emitted radiation. In some implementations, the light source 350 may be positioned relative to the surface of the substrate 322 to avoid exposure to its emitted radiation. For instance, the light source 350 may emit radiation inside an optical cavity separate from the processing chamber 310 or emit radiation inside the processing chamber 310 at an angle that avoids striking the surface of the substrate 322.

[0057] Figure 4 shows a graph illustrating light absorption of halogen gases as a function of wavelength associated with radiation emitted from a light source according to some implementations. The light source (e.g., light source 350) may be configured to emit a discrete wavelength or a range of wavelengths that optimize light absorption by the halogen gases. The selected wavelength(s) ensures photon activation and excitation by the halogen gas to form photon-activated species. Such photon-activated species include halogen-based radicals in the excited state. By way of an example, the selected wavelength to optimize absorption by fluorine gas may be between about 200 nm and about 380 nm, or between about 220 nm and about 365 nm. By using radiation tuned to a selected wavelength or wavelengths, this can allow optimized absorption of certain gases such as a fluorine gas relative to other gases in a gas mixture.

[0058] In some implementations, the light source (e.g., light source 350) may be configured to a selected intensity. Put another way, the intensity of the emitted radiation from the light source may be tunable. In some implementations, the light source may be configured to emit radiation having an intensity between about 0.001 W / cm2and about 100 W / cm2or between about 0.01 W / cm2and about 10 W / cm2.

[0059] Photon-activated species, including reactive radicals in the ground state or excited state,are generated by illumination from the light source (e.g., light source 350). The photon-activated species may be highly reactive radicals with a narrow energy distribution. Because the spectral line width of radiation from the light source may be narrow, e.g., within 1 nm or 10 nm, the energy distribution of the photon-activated species is also narrow. In some implementations, the energy distribution of the photon-activated species generated by illumination from the light source is about 10 meV or less. In some implementations, the energy distribution of the photon-activated species generated by illumination from the light source is about 100 meV or less. This allows the energy of the highly reactive radicals to be more tightly controlled and targeted. Unlike excitation by plasma that produces activated species with a broad energy distribution, excitation by photons produces activated species with a narrower energy distribution for more targeted applications.

[0060] Returning to Figures 3 A-3F, the photon-activated species may be applied to a variety of semiconductor processing applications. For instance, the photon-activated species may be applied to etch one or more materials on the substrate 322, treat a surface of the substrate 322, or clean internal surfaces (e.g., chamber walls) of the processing chamber 310. In addition, the photon- activated species may be applied to perform oxidation, nitridation, atomic layer etch, substrate surface clean, and deposition.

[0061] In some implementations, the photon-activated species are used to etch one or more materials on the substrate 322 in the processing chamber 310. One or more reactant gases for etching may include halogens such as F2, Ch, Br2, and I2, oxidants such as O2, NO, NO2, N2O, HONO, O3, H2O2, and H2O, hydrogen halides such as HF, HC1, HBr, and HI, and other etchant chemistries such as NF3, CH4, CHF3, SFe, NH3, SiF4, and H2. Any of the aforementioned reactant gases, or their combinations, may form highly reactive radicals in a ground or excited state. By way of an example, the one or more reactant gases for etching may include F2. When exposed to appropriate radiation from the light source 350, molecular fluorine gas (F2) may dissociate and form reactive radicals of fluorine (F*). The radicals of fluorine may be in a ground state or excited state to etch one or more materials on the substrate 322, such as silicon, silicon oxide, silicon nitride, or silicon germanium.

[0062] Material etch rate and selectivity may be controlled in a variety of different ways. Typically, material etch rate and selectivity may be controlled by changing etchant chemistries or changing a ratio of etchant chemistry combinations (e.g., ratio of NF3 to H2). In some implementations of the present disclosure, material etch rate and selectivity may be controlled by tuning light source energy (e.g., wavelength) from the light source 350. By tuning the light source energy, this can change the ratio of radicals in different excited states. For instance, higher energies can cause more radicals to be excited to higher energy states, and lower energies cancause fewer radicals to be excited to higher energy states or even cause more radicals to be in lower energy states (e.g., ground state). A higher concentration of radicals in higher energy states can increase an etch rate of one or more materials. In one example, the selected wavelength of the light source 350 may cause more fluorine radicals (F*) in a certain energy state, thereby changing the etch rate and selectivity of materials such as silicon, silicon oxide, silicon nitride, or silicon germanium on the substrate 322. In some implementations of the present disclosure, material etch rate and selectivity may be controlled by tuning the light source intensity from the light source 350. By tuning the light source intensity, this can change the ratio of radical atoms in the excited state to radical atoms or molecules in the ground state. For example, higher intensity can cause a higher concentration of reactant gases to be dissociated and form radical atoms in an excited state, whereas lower intensity can cause a lower concentration of reactant gases to be dissociated or can even produce more radical atoms in a lower energy state (e.g., ground state) than a higher energy state. In one example, the selected intensity of the light source 350 or other characteristic of the light source 350 may modulate the ratio of F2 to F* species or modulate the ratio of F* (excited state) to F* (ground state), thereby changing the etch rate and selectivity of materials such as silicon, silicon oxide, silicon nitride, or silicon germanium. In another example, the selected wavelength of the light source 350 may cause at least one reactant gas to be dissociated and / or excited to a higher energy state from amongst a mixture of reactant gases. That way, certain reactant gases may form photon-activated species depending on the selected wavelength while other reactant gases are not activated by the radiation from the light source 350. By controlling the light source wavelength and / or the light source intensity, etch rate and selectivity can be tuned. This affords greater control in performing selective etch across one or more materials on the substrate 322.

[0063] In some implementations, the photon-activated species are used to treat a surface of the substrate 322. The one or more reactant gases may form highly reactive radicals used to treat the surface of the substrate 322 without damage or with minimal damage to underlying films on the substrate 322. In contrast to plasma-generated species that comprise high-energy ions and radicals, photon-generated species that comprise reactive radicals in a ground state or excited state have less energy (e.g., less kinetic energy) to minimize damage to the substrate 322. In some implementations, the reactive radicals or reactant gases in an excited vibrational state generated by light exposure can serve to remove surface contamination. The reactive radicals or reactant gases in an excited vibrational state can serve to remove various contaminants containing carbon (C), hydrocarbon (CH), fluorocarbon (CF), hydrofluorocarbon (CHF), etc. In some implementations, the reactive radicals or reactant gases in an excited vibrational state generatedby light exposure can serve to remove damaged materials or layers. The reactive radicals or reactant gases in an excited vibrational state can serve to remove, for example, damaged silicon (Si), silicon oxide (SiCh), silicon oxycarbonitride (SiOCN), or silicon nitride (SisN^.

[0064] In some implementations, the photon-activated species are used to clean internal surfaces of the processing chamber 310. The one or more reactant gases may form highly reactive radicals or reactant gases in an excited vibrational state used to remove materials deposited on internal surfaces of the processing chamber 310. Internal surfaces may include but are not limited to internal chamber walls, ceiling, floor, showerhead, substrate support, lift pins, gas lines, nozzles, etc. Without cleaning the processing chamber 310, wafers are vulnerable to particle contamination and drift in processing results, and the processing chamber 310 is subject to degradation and erosion. In some cases, cleaning the internal surfaces of the processing chamber 310 may proceed without a substrate in the processing chamber 310, such as in a waferless automated clean (WAC). In contrast to plasma-generated species that have high kinetic energies, photon-activated species have low kinetic energies and are more easily distributed throughout the processing chamber 310. As such, the reactive radicals or reactant gases in an excited vibrational state generated by light exposure can serve to remove materials deposited on chamber surfaces such as chamber-deposited materials containing silicon, carbon, hydrocarbon, fluorocarbon, hydrofluorocarbon, metal, etc.

[0065] Though not shown in Figures 3A-3F, the semiconductor processing apparatus 300 may further include a controller configured with instructions for performing various operations. The controller may control various activities of the semiconductor processing apparatus 300. The controller executes system control software, including sets of instructions for controlling the timing of gas flow, mixture of gases, concentration of gases, chamber pressure, chamber temperature, substrate temperature, pedestal position, light source wavelength(s), light source intensity, light source mode of operation, timing of light exposure, selection of light source from among a plurality of light sources, and other parameters. Other computer programs stored on memory devices associated with the controller may be employed in some other embodiments.

[0066] The semiconductor processing apparatus 300 shown in Figures 3A-3F may be a standalone apparatus for generating photon-activated species using a light source. Alternatively, the semiconductor processing apparatus 300 may be implemented with both a plasma source for generation of plasma-activated species and a light source for generation of photon-activated species. By incorporating the light source and the plasma source in the semiconductor processing apparatus 300, the plasma source and the light source may co-exist in the semiconductor processing apparatus 300 and may be used for various processing operations. The plasma source may be used for processing that involves high-energy ions and radicals and the light source maybe used for processing that involves reactive radicals at lower energies. By way of an example, the plasma source may be used for anisotropic etching of materials on a substrate, and the light source may be used for subsequent treatment of damaged layers following the anisotropic etch. By integrating the plasma source and the light source in a single tool, such processes may be performed without a vacuum break in between operations. In some implementations, any of the configurations shown in Figures 3A-3F may be incorporated with plasma-based apparatuses in Figures 1 and 2.

[0067] Figure 3A shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species and an optical cavity between a gas distributor and gas source according to some implementations. In Figure 3A, an optical cavity 360 is positioned between the gas source 340 and the gas distributor 330. The optical cavity 360 is fluidly coupled to the gas source 340 to receive the one or more reactant gases. The one or more reactant gases are in the ground state. The optical cavity 360 is fluidly coupled to the gas distributor 330 to deliver photon-activated species to the gas distributor 330. The light source 350 is optically coupled to the optical cavity 360. The light source 350 is optically coupled to permit transmission of light into the optical cavity 360. For instance, the light source 350 may transmit light through a window 362 into the optical cavity 360.

[0068] An interior of the optical cavity 360 may include one or more mirrors or may be coated with a reflective material 364. As used herein, the term “optical cavity” may refer to a space where photons are present. In other words, the “optical cavity” is a space that is configured to receive radiation from a light source. The interior of the optical cavity may or may not include reflective surfaces. The mirror(s) or reflective material 364 may exhibit high reflectivity in the appropriate spectrum (e.g., UV spectrum, visible light spectrum, IR spectrum). Radiation emitted from the light source 350 may repeatedly reflect in the interior of the optical cavity 360 to increase the likelihood of the one or more reactant gases being exposed to the radiation. Having the reflective coatings or mirrors reduce residence times and increase optical path lengths. This enhances overall absorption of radiation so that a higher concentration of photon-activated species is generated. As a result, this ensures that a substantial amount of the one or more reactant gases supplied to the optical cavity 360 are converted to photon-activated species. While the photon-activated species includes reactive radicals in the excited state, it will be understood that the photon-activated species may also include reactive radicals in the ground state and / or energized reactant gases in an excited vibrational state.

[0069] In Figure 3A, the photon-activated species are generated in the optical cavity 360 that is remote from the processing chamber 310. In such a configuration, the semiconductor processingapparatus 300 may be more easily serviceable and maintained with a separate optical cavity 360. The photon-activated species may include reactive radicals in the excited state that flow from the optical cavity 360 through the gas distributor 330 and into the processing chamber 310. The photon-activated species may have relatively long lifetimes. Once formed, the photon-activated species may have lifetimes of about 1 second or more, about 5 seconds or more, or about 10 seconds or more. The lifetime of a reactive radical in the excited state may correspond to the length of time before the reactive radical in the excited state transitions to a ground state or recombines. Photon-activated species may include dissociated atoms / molecules that may eventually recombine. Fluorine-activated species, for example, may have a lifetime in excess of 10 seconds. The photon-activated species may remain in the active state for a sufficient time before recombination or before transitioning to a ground state. That way, a substantial fraction of the photon-activated species may be in the active state to etch one or more materials on the substrate 322, treat a surface of the substrate 322, or clean internal surfaces of the processing chamber 310 before recombination or before transitioning to a ground state.

[0070] Figure 3B shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species and an optical cavity between a gas distributor and gas source according to some other implementations. In Figure 3B, an optical cavity 360 is positioned between the gas source 340 and the gas distributor 330. The optical cavity 360 is fluidly coupled to the gas source 340 to receive the one or more reactant gases. The one or more reactant gases are in the ground state. The optical cavity 360 is fluidly coupled to the gas distributor 330 to deliver photon-activated species to the gas distributor 330. The light source 350 is optically coupled to the optical cavity 360. The light source 350 is optically coupled to permit transmission of light into the optical cavity 360. For example, the light source 350 may transmit light through a window 362 into the optical cavity 360.

[0071] The light source 350 may include an LED or an array of LEDs. The LED or array of LEDs may emit radiation at a discrete wavelength or discrete wavelengths, though it is possible that the LED(s) may emit radiation at a broadband range of discrete or continuous wavelengths. In Figure 3B, the array of LEDs may be arranged along a periphery of the optical cavity 360 to increase the likelihood of the one or more reactant gases being exposed to the radiation. In some cases, the LEDs may be positioned on top surfaces and / or side surfaces of the optical cavity 360. The density and arrangement of LEDs may be optimized to ensure that a substantial amount of the one or more reactant gases supplied to the optical cavity 360 are converted to photon-activated species. In some implementations, the optical cavity 360 may include one or more mirrors or may be coated with a reflective material (not shown). In some implementations, the light source 350is not limited to an LED or an array of LEDs, but may include one or more lasers or one or more broadband light sources such as an arc discharge lamp.

[0072] In Figure 3B, the photon-activated species are generated in the optical cavity 360 that is remote from the processing chamber 310. In such a configuration, the semiconductor processing apparatus 300 may be more easily serviceable and maintained with a separate optical cavity 360. The photon-activated species may include reactive radicals in the excited state that flow from the optical cavity 360 through the gas distributor 330 and into the processing chamber 310. A substantial fraction of the photon-activated species may be in the active state to etch one or more materials on the substrate 322, treat a surface of the substrate 322, or clean internal surfaces of the processing chamber 310 before recombination or before transitioning to a ground state.

[0073] Figure 3C shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a gas distributor according to some implementations. In Figure 3C, the gas distributor 330 simultaneously serves as the optical cavity for generation of photon-activated species and for delivery of the photon- activated species into the processing chamber 310. No separate optical cavity is needed in the semiconductor processing apparatus 300 as the gas distributor 330 functions as the optical cavity. The gas source 340 is fluidly coupled to the gas distributor 330, where the gas distributor 330 receives the one or more reactant gases. The one or more reactant gases are in the ground state. The light source 350 is optically coupled to the gas distributor 330. The light source 350 is optically coupled to permit transmission of light into the gas distributor 330. For instance, the light source 350 may transmit light through a window 332 into the gas distributor 330.

[0074] An interior of the gas distributor 330 may include one or more mirrors or may be coated with a reflective material 334. The mirror(s) or reflective material 334 may exhibit high reflectivity in the appropriate spectrum (e.g., UV spectrum, visible light spectrum, IR spectrum). Radiation emitted from the light source 350 may repeatedly reflect in the interior of the gas distributor 330 to increase the likelihood of the one or more reactant gases being exposed to the radiation. The reflective coatings or mirrors reduce residence times and increase optical path length, which ensures that a substantial amount of the one or more reactant gases supplied to the gas distributor 330 are converted to photon-activated species.

[0075] In Figure 3C, the photon-activated species are generated in the gas distributor 330 that is fluidly coupled to the processing chamber 310. In such a configuration, the photon-activated species may be more uniformly distributed from the gas distributor 330 to the processing chamber 310. The photon-activated species may include reactive radicals in the excited state that flow from the gas distributor 330 and into the processing chamber 310. A substantial fraction of the photon-activated species may be in the active state to etch one or more materials on the substrate 322, treat a surface of the substrate 322, or clean internal surfaces of the processing chamber 310 before recombination or before transitioning to a ground state.

[0076] Figure 3D shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a gas distributor according to some other implementations. In Figure 3D, the gas distributor 330 simultaneously serves as the optical cavity for generation of photon-activated species and for delivery of the photon-activated species into the processing chamber 310. No separate optical cavity is needed in the semiconductor processing apparatus 300 as the gas distributor 330 functions as the optical cavity. The gas source 340 is fluidly coupled to the gas distributor 330, where the gas distributor 330 receives the one or more reactant gases. The one or more reactant gases are in the ground state. The light source 350 is optically coupled to the gas distributor 330. The light source 350 is optically coupled to permit transmission of light into the gas distributor 330. For example, the light source 350 may transmit light through a window 332 into the gas distributor 330.

[0077] The light source 350 may include an LED or an array of LEDs. The LED or array of LEDs may emit radiation at a discrete wavelength or discrete wavelengths, though it is possible that the LED(s) may emit radiation at a broadband range of discrete or continuous wavelengths. The array of LEDs may be arranged along a periphery of the gas distributor 330 to increase the likelihood of the one or more reactant gases being exposed to the radiation. In some cases, the LEDs may be positioned on side surfaces of the gas distributor 330. The density and arrangement of LEDs may be optimized to ensure that a substantial amount of the one or more reactant gases supplied to the gas distributor 330 are converted to photon-activated species. In some implementations, the gas distributor 330 may include one or more mirrors or may be coated with a reflective material (not shown). In some implementations, the light source 350 is not limited to an LED or an array of LEDs, but may include one or more lasers or one or more broadband light sources such as an arc discharge lamp.

[0078] In Figure 3D, the photon-activated species are generated in the gas distributor 330 that is fluidly coupled to the processing chamber 310. In such a configuration, the photon-activated species may be more uniformly distributed from the gas distributor 330 to the processing chamber 310. The photon-activated species may include reactive radicals in the excited state that flow from the gas distributor 330 and into the processing chamber 310. A substantial fraction of the photon- activated species may be in the active state to etch one or more materials on the substrate 322, treat a surface of the substrate 322, or clean internal surfaces of the processing chamber 310 before recombination or before transitioning to a ground state.

[0079] Figure 3E shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a processing chamber according to some implementations. In Figure 3E, the processing chamber 310 simultaneously serves as the optical cavity for generation of photon-activated species and for processing the substrate 322 or cleaning internal surfaces of the processing chamber 310. No separate optical cavity is needed in the semiconductor processing apparatus 300 as the processing chamber 310 functions as the optical cavity. The gas source 340 is fluidly coupled to the gas distributor 330, where the gas distributor 330 receives the one or more reactant gases. The one or more reactant gases are in the ground state. The light source 350 is optically coupled to the processing chamber 310. The light source 350 is optically coupled to permit transmission of light into the processing chamber 310. For instance, the light source 350 may transmit light through a window 312 into the processing chamber 310.

[0080] An interior of the processing chamber 310 may include one or more mirrors or may be coated with a reflective material 314. The mirror(s) or reflective material 314 may exhibit high reflectivity in the appropriate spectrum (e.g., UV spectrum, visible light spectrum, IR spectrum). Radiation emitted from the light source 350 may repeatedly reflect in the interior of the processing chamber 310 to increase the likelihood of the one or more reactant gases being exposed to the radiation. The reflective coatings or mirrors reduce residence times and increase optical path length, which ensures that a substantial amount of the one or more reactant gases supplied to the processing chamber 310 are converted to photon-activated species.

[0081] In Figure 3E, the photon-activated species are generated directly in the processing chamber 310. In such a configuration, the photon-activated species are generated closest to the substrate 322 and / or internal surfaces of the processing chamber 310 for maximum efficiency. By generating the photon- activated species directly in the processing chamber 310, the likelihood of recombination or transitioning of reactive radicals from the excited state to ground state is minimized. Accordingly, a substantial fraction of the photon-activated species may be in the active state to etch one or more materials on the substrate 322, treat a surface of the substrate 322, or clean internal surfaces of the processing chamber 310 before recombination or before transitioning to a ground state.

[0082] Figure 3F shows a schematic illustration of an example semiconductor processing apparatus including a light source for generating photon-activated species in a processing chamber according to some other implementations. In Figure 3F, the processing chamber 310 simultaneously serves as the optical cavity for generation of photon-activated species and for processing the substrate 322 or cleaning internal surfaces of the processing chamber 310. Noseparate optical cavity is needed in the semiconductor processing apparatus 300 as the processing chamber 310 functions as the optical cavity. The gas source 340 is fluidly coupled to the gas distributor 330, where the gas distributor 330 receives the one or more reactant gases. The one or more reactant gases are in the ground state. The light source 350 is optically coupled to the processing chamber 310. The light source 350 is optically coupled to permit transmission of light into the processing chamber 310. For example, the light source 350 may transmit light through a window 312 into the processing chamber 310.

[0083] The light source 350 may include an LED or an array of LEDs. The LED or array of LEDs may emit radiation at a discrete wavelength or discrete wavelengths, though it is possible that the LED(s) may emit radiation at a broadband range of discrete or continuous wavelengths. The array of LEDs may be arranged along a periphery of the processing chamber 310 to increase the likelihood of the one or more reactant gases being exposed to the radiation. In some cases, the LEDs may be positioned on side surfaces or chamber walls of the processing chamber 310. The density and arrangement of LEDs may be optimized to ensure that a substantial amount of the one or more reactant gases supplied to the processing chamber 310 are converted to photon-activated species. In some implementations, the processing chamber 310 may include one or more mirrors or may be coated with a reflective material (not shown). In some implementations, the light source 350 is not limited to an LED or an array of LEDs, but may include one or more lasers or one or more broadband light sources such as an arc discharge lamp.

[0084] In Figure 3F, the photon-activated species are generated directly in the processing chamber 310. In such a configuration, the photon-activated species are generated closest to the substrate 322 and / or internal surfaces of the processing chamber 310 for maximum efficiency. By generating the photon- activated species directly in the processing chamber 310, the likelihood of recombination or transitioning of reactive radicals in the excited state to ground state is minimized. As such, a substantial fraction of the photon-activated species may be in the active state to etch one or more materials on the substrate 322, treat a surface of the substrate 322, or clean internal surfaces of the processing chamber 310 before recombination or before transitioning to a ground state.

[0085] Figure 5 shows a schematic illustration of an example optical cavity that includes an optical cell with a light source and a gas cell through which one or more reactant gases pass through according to some implementations. The optical cavity 500 may be implemented in a semiconductor processing apparatus, such as any one of the semiconductor processing apparatuses described in Figures 3A-3F and 7A-7B. The optical cavity 500 represents a space or volumeadapted for generation of photon-activated species and through which radiation from a light source is received.

[0086] The optical cavity 500 includes an optical cell 510 and a gas cell 520. The optical cell 510 can represent a structural component that includes one or more light sources 512. In some cases, the optical cell 510 can further include window(s) and / or transparent material(s) so that radiation emitted from the one or more light sources 512 can be transmitted. In some cases, the optical cell 510 can further include mirror(s) and / or reflective material (s) so that radiation emitted from the one or more light sources 512 can be reflected. Reflective walls or surfaces can trap photons within the optical cavity 500 to increase photo-absorption. This allows reactant gases to encounter photons as many times as possible within the optical cavity 500.

[0087] The gas cell 520 can represent a structural component through which reactant gas(es) pass through. In some implementations, the gas cell 520 can be fluidly coupled to a processing chamber. The optical cell 510 can be positioned relative to the gas cell 520 so that radiation from the one or more light sources 512 can be absorbed by the reactant gas(es) in the gas cell 520. The gas cell 520 may have a gas inlet 522 configured to receive the reactant gas(es) and a gas outlet 524 configured to discharge the reactant gas(es). The reactant gas(es) that exit the gas cell 520 at the outlet 524 may be photo-activated. In some implementations, the gas cell 520 may be made of a transparent or substantially transparent material to the radiation from the one or more light sources 512. For example, walls of the gas cell 520 can comprise silicon dioxide (e.g., quartz) or aluminum oxide (e.g., sapphire).

[0088] In some implementations, the optical cell 510 has a geometry that is the same as the gas cell 520. In some implementations, the optical cell 510 has a geometry that is different than the gas cell 520. The optical cell 510 may have a different geometry than the gas cell 520 for ease of manufacturability. The optical cell 510 may have a cylindrical, rectangular, octagonal, or other polygonal geometry. The gas cell 520 may have a cylindrical, rectangular, octagonal, or other polygonal geometry. As shown in Figure 5, the optical cell 510 has a rectangular geometry and the gas cell 520 has a cylindrical geometry.

[0089] The one or more light sources 512 may be disposed, placed, attached, mounted, or positioned on one or more surfaces of the optical cell 510. The one or more light sources 512 may direct radiation into the gas cell 520 so that reactant gases interact with photons of the radiation inside the gas cell 520. In Figure 5, the one or more light source 512 may include an array of LEDs. In some implementations, the array of LEDs may include first LEDs that emit radiation at a first wavelength, second LEDs that emit radiation at a second wavelength, and so forth. As such,the array of LEDs may be configured to emit radiation at different wavelengths. In one example, the array of LEDs may include multiple banks of LED arrays, where each bank can include several LEDs arranged in an array. By way of the example illustrated in Figure 5, the one or more light sources 512 can include a 5x3 array of LED banks, each LED bank comprising 10 LEDs, so that the one or more light sources 512 includes 150 LEDs on a surface of the optical cell 510.

[0090] Mirrors or other reflective materials may be disposed, placed, attached, mounted, or positioned in the optical cavity 500. The mirrors or other reflective materials may be inside and / or outside the gas cell 520. In some implementations, mirrors or other reflective materials located outside the gas cell 520. For example, the mirrors or other reflective materials may be located on one or more surfaces of the optical cell 510. In such designs, the mirrors or other reflective materials may avoid exposure to the reactant gases (e.g., corrosive gases) that can degrade the reflectivity of the mirrors or other reflective materials. However, this may result in higher optical loss compared to mirrors or other reflective materials being located inside the gas cell 520. Higher optical loss can result from having the emitted radiation from the one or more light sources 512 and the reflected radiation from the mirrors or other reflective materials encounter more interfaces in passing through the gas cell 520. To facilitate the reflected radiation passing through the gas cell 520, the gas cell 520 may be composed of transparent materials that contribute to more interfaces encountered by the radiation, resulting in higher optical loss.

[0091] Figures 6A-6E illustrate various designs of an optical cavity that includes a separate gas cell from an optical cell. The designs in Figures 6A-6E are illustrative only and it will be understood that various modifications or changes can be made for alternative designs. Therefore, the present examples are considered illustrative and not restrictive.

[0092] Figure 6A shows a schematic illustration of an example optical cavity that includes a rectangular optical cell and a cylindrical gas cell according to some implementations. The rectangular optical cell 602 surrounds the cylindrical gas cell 604. The rectangular optical cell 602 may include a plurality of LEDs 606 located on one or more surfaces of the rectangular optical cell 602 and positioned around the cylindrical gas cell 604. The plurality of LEDs 606 may be configured to illuminate the cylindrical gas cell 604. In some cases, the plurality of LEDs 606 can be arranged as strings or arrays of LEDs on multiple surfaces of the rectangular optical cell 602. Reactant gases that flow through the cylindrical gas cell 604 may be activated by the radiation emitted from the plurality of LEDs 606. In some implementations, reflective mirrors (not shown) can be arranged outside the cylindrical gas cell 604 and around the cylindrical gas cell 604. For example, the reflective mirrors may be located on one or more surfaces of the rectangular optical cell 602. In some cases, the rectangular optical cell 602 can be a cube with reflective surfaces.The cylindrical gas cell 604 may be formed of a transparent or substantially transparent material such as quartz. The reflective mirrors can cause multiple reflections and thus increase the effective path length to increase the LED optical power used to activate the reactant gases in the cylindrical gas cell 604.

[0093] Figure 6B shows a schematic illustration of an example optical cavity that includes a cylindrical optical cell and a cylindrical gas cell according to some implementations. The cylindrical optical cell 612 surrounds the cylindrical gas cell 614. The cylindrical optical cell 612 may include a plurality of LEDs 616 located at one of the ends of the cylinder of the cylindrical optical cell 612. Additionally or alternatively, the plurality of LEDs 616 may be located along the curved surfaces of the cylinder of the cylindrical optical cell 612. Reactant gases that flow through the cylindrical gas cell 614 may be activated by the radiation emitted from the plurality of LEDs 616. In some implementations, reflective mirrors (not shown) can be arranged outside the cylindrical gas cell 614 and around the cylindrical gas cell 614. For instance, the reflective mirrors may be located on the curved surfaces of the cylindrical optical cell 612 or at one of the ends of the cylinder of the cylindrical optical cell 612. The cylindrical gas cell 614 may be formed of a transparent or substantially transparent material such as quartz. The reflective mirrors can cause multiple reflections and thus increase the effective path length to increase the LED optical power used to activate reactant gases in the cylindrical gas cell 614.

[0094] Figure 6C shows a schematic illustration of an example optical cavity that includes an octagonal optical cell and a cylindrical gas cell according to some implementations. The octagonal optical cell 622 surrounds the cylindrical gas cell 624. The octagonal optical cell 622 may include a plurality of LEDs 626 located on one or more sides of the octagonal optical cell 622 and positioned around the cylindrical gas cell 624. The plurality of LEDs 626 may be configured to illuminate the cylindrical gas cell 624. In some cases, the plurality of LEDs 626 can be arranged as strings or arrays of LEDs on one or more surfaces of the octagonal optical cell 622. Reactant gases that flow through the cylindrical gas cell 624 may be activated by the radiation emitted from the plurality of LEDs 626. In some implementations, reflective mirrors (not shown) can be arranged outside the cylindrical gas cell 624 and around the cylindrical gas cell 624. For example, the reflective mirrors may be located on one or more sides of the octagonal optical cell 622 and may even be formed on all sides of the octagonal optical cell 622. The cylindrical gas cell 624 may be formed of a transparent or substantially transparent material such as quartz. The reflective mirrors can cause multiple reflections and thus increase the effective path length to increase the LED optical power used to activate the reactant gases in the cylindrical gas cell 624.

[0095] Figure 6D shows a schematic illustration of an example optical cavity that includes a circular window that sits above a gas cell according to some implementations. The circular window 632 is located above the gas cell 634. The circular window 632 includes a plurality of LEDs 636 located on a major surface of the circular window 632. The plurality of LEDs 636 may include several boards or banks of LEDs positioned across the major surface of the circular window 632. For instance, the boards of LEDs may be arranged in concentric circles, where each of the boards of LEDs may include multiple LEDs. In one example, the plurality of LEDs 636 can include 18 boards of 12 LEDs each. The plurality of LEDs 636 illuminate the gas cell 634 that sits below the circular window 632. Reactant gases that flow through the gas cell 634 may be activated by the radiation emitted from the plurality of LEDs 636. In some implementations, reflective mirrors (not shown) may be located inside the gas cell 634 or outside the gas cell 634. However, in some other implementations, reflective mirrors are not employed. The plurality of LEDs 636 may emit radiation into the gas cell 634 without the assistance of reflective mirrors or surfaces to activate the reactant gases in the gas cell 634. Accordingly, the radiation from the plurality of LEDs 636 may pass through the gas cell 634 only once. In some cases, the gas cell 634 may constitute a space between the circular window 632 and a showerhead 638. The circular window 632 may be positioned above the showerhead 638 and photon-activated species of the reactant gases may pass through the showerhead 638 and into a processing chamber.

[0096] Figure 6E shows a schematic illustration of an example optical cavity that includes an annular window that surrounds a gas cell according to some implementations. Rather than a circular window that sits above the gas cell 644, the annular window 642 is positioned around and along a periphery of the gas cell 644. The annular window 642 may be shaped as a ring. The annular window 642 may include a plurality of LEDs 646 arranged around the annular window 642. The annular window 642 may be formed of a transparent or substantially transparent material such as quartz or sapphire. The plurality of LEDs 646 arranged around the annular window 642 may illuminate the gas cell 644. Reactant gases that flow through the gas cell 644 may be activated by the radiation emitted from the plurality of LEDs 646. The radial arrangement of the LEDs 646 around a ring (i.e., annular window 642) allows for increased path length for improved light absorption by the reactant gases. In some implementations, reflective mirrors (not shown) may be located inside the gas cell 644 or outside the gas cell 644. In some implementations, reflective mirrors are not employed. The embodiment in Figure 6E may be similar to the embodiment in Figure 6D except that the window comprising the plurality of LEDs 646 is placed around the gas cell 644 rather than above the gas cell 644. The gas cell 644 may be formed of a transparent orsubstantially transparent material such as quartz or sapphire to facilitate transmission of the radiation from the plurality of LEDs 646 through the gas cell 644.

[0097] Any of the aforementioned optical cavities in Figures 6A-6E may be incorporated into a semiconductor processing apparatus, such as semiconductor processing apparatuses described in Figures 1, 2, 3A-3F, and 7A-7B, where the optical cavities may include certain designs of an optical cell optically coupled to a gas cell. The semiconductor processing apparatus may include a processing chamber, a gas distributor fluidly coupled to the processing chamber, and a substrate support in the processing chamber that is configured to support a semiconductor substrate. Reactant gases may flow through the gas cell of the optical cavity, where at least one of the reactant gases is converted to photon-activated species by illumination. One or more light sources (e.g., LEDs) on an optical cell may illuminate the gas cell to generate the photon-activated species. As discussed above, the optical cavity may be located upstream of the gas distributor, integrated in the gas distributor, or integrated in the processing chamber. Figures 7A-7B illustrate an example semiconductor processing apparatus that includes a processing chamber, a gas distributor, and an optical cavity located above or upstream the gas distributor. Figure 7A shows the semiconductor processing apparatus being utilized for generating photon-activated species in the optical cavity. Figure 7B shows the semiconductor processing apparatus being utilized for direct illumination of the semiconductor substrate in the processing chamber.

[0098] Figure 7A shows a schematic illustration of an example semiconductor processing apparatus including a light source positioned above a gas distributor, where the light source may be configured to generate photon-activated species in an optical cavity, according to some implementations. The semiconductor processing apparatus 700 includes a processing chamber 710 and a substrate support 720 configured to support a semiconductor substrate 722 in the processing chamber 710. The substrate support 720 may be a pedestal or electrostatic chuck. The semiconductor processing apparatus 700 further includes a gas distributor 730 such as a showerhead in fluid communication with the processing chamber 710. The gas distributor 730 may be configured to distribute process gases and reactants into the processing chamber 710. In some implementations, the gas distributor 730 may be a plate with a plurality of through-holes by which the process gases and reactants flow through. In some implementations, the gas distributor 730 may include a transparent or substantially transparent material such as quartz or sapphire to permit electromagnetic radiation to pass through the gas distributor 730 and into the processing chamber 710.

[0099] The semiconductor processing apparatus 700 may further include a gas source 740. The gas source 740 may be located upstream of the gas distributor 730 and may provide one or morereactant gases to an optical cavity 760. The one or more reactant gases may include atomic or molecular gases in a ground state. In some implementations, the one or more reactant gases include a halogen gas, a hydrogen halide, an oxidant gas, nitrogen trifluoride, nitrous oxide, nitric oxide, nitrogen dioxide, methane, fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof. The gas source 740 may be in fluid communication with the optical cavity 760. The one or more reactant gases flow from the gas source 740 through the optical cavity 760 to the gas distributor 730.

[0100] The semiconductor processing apparatus 700 may further include a light source 750. The light source 750 may be optically coupled with the optical cavity 760. The light source 750 may be configured to emit radiation into the optical cavity 760 to energize and / or excite the one or more reactant gases in the ground state to produce photon-activated species of at least one of the reactant gases. The light source 750 may be tunable. Specifically, the light source 750 may be tuned to a selected wavelength or wavelengths to cause at least one of the reactant gases to be dissociated, energized to an excited vibrational state, activated to form a reactant radical, and / or excited from a ground state to an excited state reactant radical. In some implementations, the selected wavelength or wavelengths may be tuned in the UV spectrum (100-400 nm). In some implementations, the selected wavelength or wavelengths may be tuned in the visible light spectrum (400-1000 nm). In some implementations, the selected wavelength or wavelengths may be tuned in the IR spectrum (greater than 1000 nm). In the IR spectrum, for example, the reactant gases may be energized to an excited vibrational state without undergoing dissociation. Additionally or alternatively, the light source 750 may be tuned to a selected intensity. The selected intensity may be tuned to control an energy distribution of the photon-activated species of the one or more reactant gases. For instance, the intensity can control a ratio of reactant radicals in the excited state to reactant radicals in the ground state.

[0101] In some implementations, the light source 750 can include a laser. In some implementations, the light source 750 can include a flash lamp. In some implementations, the light source 750 can include a plurality of LEDs. Similar to the design in Figure 6D, the light source 750 may include a plurality of LEDs positioned above the optical cavity 760. In some implementations, the light source 750 is positioned on a window 770 such as a circular window. The window 770 may include a transparent or substantially transparent material such as quartz or sapphire. The plurality of LEDs emit radiation through the window 770 into the optical cavity 760 towards the gas distributor 730. The one or more reactant gases interact with the radiation in the optical cavity 760 to convert at least one of the reactant gases into photon-activated species in the optical cavity 760.

[0102] In some implementations, the optical cavity 760 can include one or more reflective mirrors or reflective surfaces. Radiation emitted from the light source 750 may reflect in the interior of the optical cavity 760 to increase the likelihood of the one or more reactant gases being exposed to the radiation. This can increase the optical path length and effective LED power for photon activation of the one or more reactant gases. In some other implementations, the optical cavity 760 is free of any reflective mirrors or reflective surfaces. This may provide ease of manufacturability. This also avoids any mirrors or reflective surfaces being exposed to corrosive gases. Radiation emitted from the light source 750 may pass only once through the optical cavity 760.

[0103] The photon-activated species generated in the optical cavity 760 may flow through the gas distributor 730 and into the processing chamber 710. While the photon-activated species includes reactive radicals in the excited state, it will be understood that the photon-activated species may also include reactive radicals in the ground state and / or energized reactant gases in an excited vibrational state. Without the assistance of plasma, the one or more reactant gases are activated by photons and employed to clean internal surfaces of the processing chamber 710 or process the semiconductor substrate 722 in the processing chamber 710. In the processing chamber 710, the photon-activated species serve to etch one or more materials on the semiconductor substrate 722, treat a surface of the semiconductor substrate 722, clean the surface of the semiconductor substrate 722, deposit one or more materials on the semiconductor substrate 722, perform oxidation on the semiconductor substrate 722, perform nitridation on the semiconductor substrate 722, perform atomic layer etch on the semiconductor substrate 722, or clean internal surfaces of the processing chamber 710. The light source 750 may be tuned to certain wavelength(s) and / or intensity to control the energy distribution of the photon-activated species of the one or more reactant gases to influence the reach vity / selectivity of reactions that take place on the semiconductor substrate 722 or the internal surfaces of the processing chamber 710.

[0104] Figure 7B shows a schematic illustration of an example semiconductor processing apparatus including a light source positioned above a gas distributor, where the light source may be configured to illuminate a semiconductor substrate in a processing chamber, according to some implementations. In some implementations, the light source 750 is configured to directly expose the semiconductor substrate 722 to radiation of the selected wavelength(s) and / or intensity. Direct illumination or exposure to the radiation may promote or hinder surface reactions on the semiconductor substrate 722. In some implementations, the radiation emitted from the light source 750 may pass through the gas distributor 730 to expose the semiconductor substrate 722 to theradiation in the processing chamber 710. Instead of activating reactant gases, the light source 750 may be configured to emit radiation at a selected wavelength(s) and / or intensity to treat the semiconductor substrate 722. In some implementations, the gas distributor 730 includes a transparent or substantially transparent material such as quartz, sapphire, or other inert material to facilitate optical transmission of the radiation into the processing chamber 710.

[0105] In some implementations, the light source 750 is tuned to a selected wavelength(s) and / or intensity to promote or hinder surface reactions on the semiconductor substrate 722. For example, the light source 750 may be tuned to a selected wavelength(s) and / or intensity that avoids generation of reactive radicals by dissociation. In fact, the selected wavelength(s) and / or intensity may cause vibrational excitation in chemical species on the surface of the semiconductor substrate 722. Such vibrational excitation may occur with IR exposure rather than electronic excitation that may occur with UV exposure. The vibrational excitation may provide additional energy to the surface of the semiconductor substrate 722 to promote or hinder surface reactions.

[0106] In some implementations, the light source 750 is tuned to a selected wavelength(s) and / or intensity to promote desorption of byproducts formed on the surface of the semiconductor substrate 722. By way of an example, etch of one or more materials on the semiconductor substrate 722 may be performed using photon-activated species generated in the optical cavity 760 and flowed into the processing chamber 710. During and after the etch process, undesirable etch byproducts may form on the surface of the semiconductor substrate 722. High temperatures are often needed for thermal desorption of the etch byproducts. However, the light source 750 may be used to directly illuminate the semiconductor substrate 722 and tuned to the selected wavelength(s) and / or intensity to promote desorption of the etch byproducts. This can lower the temperature required to perform thermal desorption of the etch byproducts.

[0107] Figure 8 shows a plan view of a schematic illustration of an example light source including a plurality of LEDs for emitting radiation at different wavelengths according to some implementations. Vibrational or electronic excitation of different gas chemistries occur at different wavelengths. Depending on the chemistry of the reactant gas, the wavelength of the light source 800 can be tuned to activate the reactant gas. In some implementations, the light source 800 can emit radiation at a first wavelength to activate a first reactant gas, and subsequently emit radiation at a second wavelength to activate a second reactant gas. The light source 800 can be tuned to emit radiation at two or more different wavelengths.

[0108] As shown in Figure 8, the light source 800 can include a board with multiple LEDs 810, 820, 830, and 840. The light source 800 can include a plurality of first LEDs 810 configured to emit radiation at a first wavelength, a plurality of second LEDs 820 configured to emit radiationat a second wavelength, a plurality of third LEDs 830 configured to emit radiation at a third wavelength, and a plurality of fourth LEDs 840 configured to emit radiation at a fourth wavelength. The light source 800 can be configured to emit different discrete wavelengths. Certain wavelengths may be selected based upon the chemistry of the reactant gas being used for semiconductor processing. In a case involving a gas mixture, the light source 800 can be configured to a selected wavelength so that only some of the reactant gases in the gas mixture are converted to photon-activated species. In a case involving a sequential introduction of reactant gases, the light source 800 can be configured to a first wavelength to photon activate a first reactant gas and the light source 800 can be configured to a second wavelength thereafter to photon activate a second reactant gas. In some cases, multiple wavelengths can be turned on according to process needs. For example, wavelengths of the light source 800 can be in the UV, visible, or IR spectrum.

[0109] In some implementations, the different LEDs 810, 820, 830, and 840 configured to emit radiation at different wavelengths are integrated as a single light source on a board. In some implementations, the light source 800 can include a power connector 850 for supplying power to the LEDs 810, 820, 830, and 840. In some implementations, the light source 800 can further include a thermistor 860 to maintain the LEDs 810, 820, 830, and 840 at a desired temperature range and limit the effects of overheating. In some implementations, the light source 800 can further include a transient voltage suppression diode 870 that is used to protection against electrostatic discharge (ESD).Use of Photon- Activated Species in Semiconductor Processing

[0110] Plasma-activated species including high-energy ions and radicals can easily damage substrate layers and materials. Plasma may be characterized by a broad energy distribution that is less suitable for targeted applications. In contrast, photon-activated species include reactive radicals in a ground energy state or excited energy state. Photon-activated species may additionally or alternatively include molecular gas(es) in an excited vibrational energy state. Photon-activated species generally do not comprise high-energy species that easily damage substrate layers and materials. Photon-activated species can be characterized by a narrow energy distribution for more targeted applications. The photon-activated species may be utilized to etch one or more materials of a semiconductor substrate or treat a surface of a semiconductor substrate, [oni] Photon-activated species may be used to control an amount of reactive species in advanced oxide applications. In some implementations, ozone may be used as an oxidant in formation of an oxide material such as silicon oxide (SiOx). Oxide materials may include thermal oxide and / or flowable oxide. It may be desirable to etch such oxide materials with a flat etch front,with minimal to no isolated / dense feature loading, with little to no seam blowout, and with approximately 1 : 1 flowable oxide to thermal oxide selectivity. Oxidants such as ozone easily decompose and it is often difficult to control the amount of decomposition that takes place. By introduction of a tunable light source, it is possible to control an amount of O2 radicals relative to O radicals. Oxygen-based radicals may be produced as photon-activated species. A ratio of O2 radicals to O radicals can be tuned, or a ratio of O2 radicals to molecular O2 can be tuned. The selected wavelength and / or intensity of the radiation emitted from the tunable light source can control ozone decomposition. This can be useful in controlling the oxidation of oxide materials such as silicon oxide. In some implementations, photon-activated species of hydrogen may be used in etching an oxide material such as silicon oxide relative to other materials such as silicon and silicon nitride. Hydrogen-based radicals such as H2 radicals or H radicals may be produced as photon-activated species. A ratio of H2 radicals to H radicals or H radicals to molecular H2 may can be tuned. The selected wavelength and / or intensity of the radiation emitted from the tunable light source can control hydrogen-based radical generation. This can be useful in controlling the etching of silicon oxide relative to silicon and silicon nitride. In some cases, ozone and hydrogen (O3 / H2) can be introduced as a gas mixture for the oxidation of silicon and etching of silicon oxide, where the decomposition of O3 and H radical generation can be tuned by photon activation. In some cases, nitrous acid (HNO2) can be used for etching silicon oxide relative to silicon and silicon nitride. Etching silicon oxide may generate various etch byproducts. Examples of etch byproducts include salt byproducts such as ammonium hexafluorosilicate ((NH^SiFe). Desorption of etch byproducts may be assisted by wafer illumination using the tunable light source. The tunable light source can directly expose the semiconductor substrate to radiation that enhances desorption of byproducts and reduces a temperature necessary to achieve desorption.

[0112] In some implementations, halogen-based species are used as an etchant for silicon. Silicon-on-insulator (SOI), polysilicon (poly-Si), and amorphous silicon (a-Si) are examples of silicon materials that may be etched using an etchant comprising a halogen-based species. Etching of silicon may occur relative to other materials such as silicon oxide (e.g., thermal oxide) and silicon nitride. Etching of silicon can be useful in a variety of applications including dummy poly removal (DPR). Dummy poly removal can be utilized in manufacturing gate structures. It may be desirable to etch silicon at a high etch rate, with good selectivity, and in a manner that avoids pitting. In some implementations, etchants for silicon may involve a halogen gas such as fluorine (F2) or chlorine (Ch). Using a tunable light source, it is possible to control an amount of F2 radicals or F radicals, or Ch radicals or Cl radicals. The tunable light source can emit radiation at a selected wavelength and / or intensity for targeted bond dissociation so that a ratio of F2 / F radicals tomolecular F2 may be tuned, or a ratio of Ch / Cl radicals to molecular CI2 may be tuned. This provides tunability with respect to etching of silicon materials. In some implementations, etchants for silicon may involve a mixture of gases. The mixture of gases may include one or more halogenbased species (e.g., F2, CI2) combined with one or more of a nitrogen-containing species, an oxygen-containing species, and / or a carbon-containing species. An example of a carbon- containing species is methane, and an example of a nitrogen-containing species is nitric oxide, where an example gas mixture can include NO / F2 / CI2 / CH4. In a gas mixture, the tunable light source can selectively target a certain reactant gas for dissociation for generation of reactive radicals. In some cases, the tunable light source can target dissociation of F2 to generate fluorine radicals. In some other cases, the tunable light source can target dissociation of CF to generate alkyl radicals. Whereas plasma energizes and activates all species in a gas mixture, the tunable light source can be configured to energize and activate only certain species in a gas mixture. This can afford greater control of etching and selectivity for etching materials such as silicon.

[0113] In some implementations, selective etching of target materials may involve gas mixtures with an additive. One such additive may include an amine. An amine can refer to a chemical formula NRXR2, where each of R1and R2is, independently, selected from hydrogen, aliphatic, heteroaliphatic, haloaliphatic, haloheteroaliphatic, aromatic, as defined herein, or any combination thereof, or R1and R2, taken together with the nitrogen atom to which each are attached, form a heterocyclyl group. In some implementations, the amine is pyridine. The etch selectivity of the gas mixture can be tuned by the amount of additive in the gas mixture. For example, very high selectivity of silicon oxide with respect to silicon nitride can be achieved by controlling a ratio of halogen source: additive (e.g., HF:pyridine), or very high selectivity of silicon oxide with respect to silicon and silicon germanium (SiGe) can be achieved by controlling a ratio of halogen source: additive (e.g., HF :pyridine). In some implementations, very high selectivity of silicon with respect to silicon nitride, field oxide, and silicon germanium can be achieved by controlling relative amounts of F2 / HF / additive. Usually, an additive such as pyridine reacts violently with F2 and HF in the gas phase. The tunable light source can target activation of the additive to limit its reactivity with F2 and HF in the gas phase. Particularly, the tunable light source can target activation of the additive such as pyridine at a location adjacent to the surface of a semiconductor substrate. That way, once the additive gets close enough to the substrate surface, activation of the additive can occur. The additive can be relatively inert until that point. This can provide targeted activation in terms of timing and location to afford greater control of etching and selectivity of materials. One application of such targeted additive (e.g., amine) activation near a substrate surface is in backside power delivery networks (BSPDN).

[0114] In some implementations, selective etching of target materials may involve gas mixtures with one or more fluorine-containing gases. Fluorine-containing gases may be used to etch silicon such as silicon-on-insulator, polysilicon, and amorphous silicon relative to other materials such as silicon germanium, thermal oxide, and silicon nitride. It may be desirable to etch silicon relative to some of the aforementioned materials at a high etch rate and with high selectivity. The etch rate and selectivity may be controlled by controlling an amount of the fluorine-containing gases in the gas mixture. In one example, relative amounts of germanium tetrafluoride and fluorine (GeF4 / F2) can be tuned to shift an equilibrium to etch silicon relative to silicon germanium. In another example, an amount of fluorine relative to ammonia and methane (F2 / NH3 / CH4) can be tuned to control the selectivity of silicon relative to other materials. Using a tunable light source, targeted bond dissociation may occur so that reactive radicals are generated of a certain species such as a fluorine-containing gas while activation / dissociation of the other gases in the gas mixture are avoided. Thus, not only are relative amounts of fluorine-containing gases in a gas mixture controlled, but relative amounts of fluorine-containing radicals in the gas mixture are controlled. This can also be applied in the context of backside power delivery networks and other semiconductor processing applications.

[0115] In some implementations, one or more fluorine-containing gases may be used in selective silicon nitride etching. Silicon nitride can be etched using a fluorine-containing gas such as F2, which may be combined with an oxidant gas such as NOX(e.g., NO2, NO, N2O) or hydrogencontaining gas such as CH4, H2, etc. Historically, plasma of a gas mixture of F2 / NO has been employed for selective etching of silicon nitride. By way of an example, silicon nitride may be etched relative to other materials such as silicon oxide (e.g., thermal oxide), silicon, and silicon germanium. It may be desirable to achieve an etch that is highly selective and controllable with low roughness. A tunable light source can generate photon-activated species of the fluorine- containing gas(es) used in selective silicon nitride etching. The fluorine radicals can bond and create FNO species or FNO2 species. Additionally or alternatively, the tunable light source can generate photon-activated species of the oxidant gas used in selective silicon nitride etching. The emitted radiation from the tunable light source can pull apart NOX, for example, to generate nitrogen radicals and oxygen radicals. Depending on the wavelength of the emitted radiation, certain reactive radicals can be generated in a gas mixture of F2 / NO to control the selectivity and / or etch rate of silicon nitride etching.

[0116] In some implementations, halogen-based gases may be used in metal or metal oxide etching. Metal or metal oxide etching are typically etched using atomic layer etching (ALE) processes. Atomic layer etching processes are effective in terms of selectivity but can be veryslow in terms of etch rate. Plasma-based etchants can be very fast in terms of etch rate but very poor in terms of selectivity. It may be desirable to increase an etch per cycle while maintaining high selectivity. A tunable light source can be employed to tune an amount of halogen-based radicals that are generated in an etchant for selectively etching metal or metal oxide. In one example, hafnium oxide can be etched using a mixture of hydrogen fluoride and boron trichloride (HF / BCI3), or a mixture of fluorine and boron trichloride (F2 / BCI3). In another example, molybdenum oxide can be etched using a mixture of hydrogen fluoride and ozone (HF / O3), or a mixture of fluorine and ozone (F2 / O3). Any of the hydrogen fluoride, the boron trichloride, and the ozone may be targeted by the tunable light source for generation of reactive radicals to selectively etch the metal oxide. Hafnium oxide can be selectively etched relative to other materials such as silicon, silicon nitride, silicon oxide, and titanium nitride. Molybdenum oxide can be selectively etched relative to other materials such as silicon, silicon nitride, and silicon oxide. The tunable light source can generate photon-activated species for etching metal or metal oxide that achieves high etch rate and high selectivity. In some cases, the tunable light source can also be employed to directly illuminate the semiconductor substrate to promote or hinder surface reactions. For instance, the tunable light source can directly expose the semiconductor substrate to radiation to enhance desorption of etch byproducts. Fluorinated byproducts may be generated during metal or metal oxide etching. These fluorinated byproducts may be desorbed from the semiconductor substrate surface at high temperatures (e.g., equal to or greater than about 300°C). However, with the assistance of direct illumination by the tunable light source, desorption of etch byproducts may occur at lower temperatures (e.g., less than about 275°C).

[0117] In some implementations, selective etching of silicon germanium relative to other materials such as silicon may be accomplished in gate-all-around (GAA) device fabrication. Silicon germanium may be used as a sacrificial material when forming channels of a GAA device. Many techniques have been developed for selective removal of silicon germanium. Existing plasma-driven techniques rely on fluorine radicals generated from fluorine-containing gases such as nitrogen trifluoride (NF3), carbon tetrafluoride (CF4), sulfur hexafluoride (SFe), silicon tetrafluoride (SiF4), fluorine (F2), or combinations thereof. Thermally-driven techniques often rely on fluorine (F2), which can provide improved selectivity, but can result in a non-uniform etch rate that can lead to formation of a non-ideal etch front within the silicon germanium material. Different portions of the silicon germanium in a layer may have different compositions, where the compositions may vary with respect to the concentration of Si and Ge, as well as other elements that may be present in the layer. These differences in compositions can result in a non-uniform etch front. It may be desirable to etch silicon germanium relative to silicon with a relatively flatetch front with minimal silicon loss. Plasma-driven processes utilize a high concentration of fluorine radicals that can achieve a relatively flat etch front. However, the plasma-driven processes utilizing a high concentration of fluorine radicals can also result in high silicon loss. On the other hand, the thermally-driven processes that utilize molecular F2 can minimize silicon loss but can lead to a non-uniform etch front. By using a tunable light source, it is possible to control a ratio of fluorine radicals relative to molecular F2 in a gas mixture comprising a fluorine-containing gas. In other words, an amount of fluorine radicals relative to molecular F2 can be carefully controlled using the tunable light source configured to emit radiation at a selected wavelength and / or intensity. This enables hitting a sweet spot to control the SiGe:SiGe selectivity as well as the Si:SiGe selectivity while minimizing silicon loss. That way, the photon-activated species of fluorine-containing gas can be tuned in a manner to achieve a flat etch front with minimal silicon loss. The gas mixture for selective silicon germanium etching relative to silicon can include one or more fluorine-containing gases. In some examples, the gas mixture includes fluorine combined with nitrogen dioxide (F2 / NO2). In some examples, the gas mixture includes fluorine combined with nitric oxide (F2 / NO). In some examples, the gas mixture includes sulfur hexafluoride (SFe). In some examples, the gas mixture includes fluorine combined with silicon tetrafluoride (F2 / SiF4). In some examples, the gas mixture includes only fluorine (F2). In some examples, the gas mixture includes fluorine combined with chlorine (F2 / CI2). In some examples, the gas mixture includes fluorine combined with fluoromethane (F2 / CH3F). In some examples, the gas mixture includes fluorine combined with nitrogen (F2 / N2). In some examples, the gas mixture includes fluorine combined with oxygen (F2 / O2). In some other examples, the gas mixture may include a chlorine- containing gas such as molecular chlorine (CI2). The tunable light source can control an amount of reactive radicals generated in the gas mixture to optimize selectivity during etching and achieve a flat etch front.

[0118] Using photon-activated species generated from a tunable light source can control a concentration or ratio of reactive species (e.g., reactive radicals) in a gas mixture, provide targeted bond dissociation, control decomposition of reactive species, provide targeted activation of certain reactive species near a wafer surface, enhance desorption of etch byproducts, improve material selectivity during etching, and many other advantages that are typically not available in plasmabased processes or thermal-based processes. Generation of the photon-activated species from the tunable light source may be achieved using any one of the semiconductor processing apparatuses in the present disclosure, though it will be understood that the generation of the photon-activated species from the tunable light source is not limited to only the semiconductor processing apparatuses in the present disclosure. Other configurations or modifications of the semiconductorprocessing apparatuses may be used as would be designed by those with ordinary skill in the art.Methods of Generating Photon- Activated Species

[0119] Figure 9A shows a flow diagram of an example method for generating photon-activated species for use in a processing chamber according to some implementations. The operations of a process 900 may be performed in different orders and / or with different, fewer, or additional operations. One or more operations of the process 900 may be performed using an apparatus described in any one of Figures 1, 2, 3A-3F, 5, 6A-6E, and 7A-7B. In some implementations, the operations of the process 900 may be implemented, at least in part, according to software stored in one or more non-transitory computer readable media.

[0120] At block 910 of the process 900, one or more reactant gases are flowed towards a gas distributor for distributing the one or more reactant gases into a processing chamber. The one or more reactant gases are in a ground state. In other words, the one or more reactant gases are in an unexcited energy state. The one or more reactant gases may include a halogen gas, a hydrogen halide, an oxidant gas, a nitrogen trifluoride, nitrous oxide, nitric oxide, nitrogen dioxide, methane, fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof. In some implementations, the one or more reactant gases include a halogen gas such as fluorine, chlorine, bromine, or iodine. In some implementations, the one or more reactant gases include a hydrogen halide such as hydrogen fluoride, hydrogen chloride, hydrogen bromide, or hydrogen iodide. In some implementations, the one or more reactant gases include an oxidant gas such as oxygen, nitric oxide, nitrogen dioxide, nitrous oxide, nitrous acid, water, hydrogen peroxide, or ozone.

[0121] The processing chamber may be part of a semiconductor processing apparatus for processing one or more substrates. The gas distributor may be fluidly coupled to the semiconductor processing chamber. The gas distributor may be configured to receive the one or more reactant gases from a gas source. The gas source may be positioned upstream of the gas distributor. The gas distributor may be a showerhead with one or more holes for delivering process gases into the processing chamber. The semiconductor processing apparatus may include a substrate support configured to support a semiconductor substrate. The substrate support may be a pedestal or electrostatic chuck. In some implementations, the semiconductor substrate may include one or more materials disposed on the substrate surface. Such materials may include an oxide material such as silicon oxide, a silicon material such as silicon-on-insulator, polysilicon, and amorphous silicon, a silicon nitride material, a metal or metal oxide material, or a silicongermanium material. In some implementations, the processing chamber may include one or more materials deposited on internal surfaces of the processing chamber.

[0122] The semiconductor processing apparatus may include an optical cavity. The optical cavity may refer to a hardware component or structure of the semiconductor processing apparatus that is configured to receive radiation from a light source. In some implementations, the optical cavity is positioned between the gas distributor and the gas source. In some implementations, the optical cavity is integrated with the gas distributor. In some implementations, the optical cavity is integrated with the processing chamber. In some implementations, the optical cavity includes a window that is transmissive to radiation emitted from the light source. Thus, the light source is optically coupled to the optical cavity. In some implementations, the optical cavity includes one or more mirrors and / or reflective material configured to reflect the radiation emitted from the light source.

[0123] In some implementations, the optical cavity includes an optical cell and a gas cell. The optical cell may include the light source and the gas cell may permit the flow of the one or more reactant gases therethrough. The optical cell and the gas cell may have different geometries from one another. In some examples, each of the optical cell and the gas cell has a cylindrical, rectangular, or octagonal geometry.

[0124] At block 920 of the process 900, radiation is emitted from a light source at a selected intensity and selected wavelength or range of selected wavelengths. The light source may be a tunable light source. The light source may be tunable according to its wavelength or range of wavelengths, intensity, and mode of operation. The tunability of the light source influences the energy distribution of the photon-activated species. In some implementations, the light source includes a laser, lamp, or LED. For example, the light source may include a plurality of LEDs. In some instances, the light source may include a broadband light source such as an arc discharge lamp. The light source may be configured to emit a discrete wavelength, a range of wavelengths, or a broadband of wavelengths.

[0125] The light source may be tunable according to its wavelength or range of wavelengths. In some implementations, the light source is configured to emit radiation such as UV radiation, IR radiation, or visible light. In some implementations, the light source is configured to emit radiation having a wavelength or range of wavelengths between about 100 nm and about 10 pm. The wavelength or range of wavelengths may be selected to obtain a desired energy distribution of radicals in their ground or excited states. With the desired energy distribution, the light source may be tuned according to selected wavelength(s) to obtain a target etch rate and selectivity of oneor more materials to be etched on the semiconductor substrate. Some examples of targeted materials to be etched on the semiconductor substrate are described above.

[0126] Additionally or alternatively, the light source may be tunable according to its intensity. In some implementations, the light source intensity may be between about 0.001 W / cm2and about 100 W / cm2or between about 0.01 W / cm2and about 10 W / cm2. The light source intensity may be selected to obtain a desired energy distribution of radicals in their ground or excited states. With the desired energy distribution, the light source may be tuned according to the selected light source intensity to obtain a target etch rate and selectivity of one or more materials to be etched on the semiconductor substrate.

[0127] Additionally or alternatively, the light source may be tunable according to its mode of operation. In some cases, the light source is configured to operate in a continuous mode or pulsing mode. In some cases, the light source may be positioned to expose or not expose the surface of the semiconductor substrate with radiation.

[0128] At block 930 of the process 900, photon-activated species of the one or more reactant gases are produced in an optical cavity by exposing the one or more reactant gases to the emitted radiation from the light source. The light source is optically coupled to the optical cavity. The light source may direct the emitted radiation into the optical cavity through an opening or window. The optical cavity may be integrated with the gas distributor, integrated with the processing chamber, or installed as a separate hardware component between the gas distributor and the gas source. The one or more reactant gases flow into the optical cavity in the ground state and exit the optical cavity as photon- activated species.

[0129] The photon-activated species are produced independent of any plasma. The one or more reactant gases may flow into the optical cavity in the ground state. After exposure to the radiation from the light source, molecular species of the one or more reactant gases may break apart and / or become excited, thereby forming the photon-activated species. In some implementations, one or more reactant gases may be energized to an excited vibrational state. The photon-activated species may include reactive radicals in the ground state or excited state. The photon-activated species may exclude ions or ionized species. In some implementations, reactive radicals in one or more energy states may be produced of a halogen gas, a hydrogen halide, an oxidant gas, a nitrogen trifluoride, nitrous oxide, nitric oxide, nitrogen dioxide, methane, fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof. By way of an example, if the reactant gas comprises F2, then the reactive radicals may comprise F2* or F* after exposure to radiation from the light source. Since the energyand / or intensity of the light source may be tuned, the energies and energy distribution of the reactive radicals in the ground or excited state may be tuned. Moreover, a ratio of reactive radicals (e.g, F2* and F*) to molecular fluorine may be tuned. This enables more precise control over substrate processing applications or chamber processing applications. Examples of substrate processing applications or chamber processing applications are discussed above and also illustrated in Figure 9B.

[0130] Figure 9B shows a flow diagram of an example method for generating and using photon- activated species in a processing chamber according to some implementations. The operations of a process 950 may be performed in different orders and / or with different, fewer, or additional operations. One or more operations of the process 950 may be performed using an apparatus described in any one of Figures 1, 2, 3A-3F, 5, 6A-6E, and 7A-7B. In some implementations, the operations of the process 950 may be implemented, at least in part, according to software stored in one or more non-transitory computer readable media.

[0131] Blocks 910, 920, and 930 of the process 950 in Figure 9B are identical to blocks 910, 920, and 930 of the process 900 in Figure 9A. For the sake of brevity, the description associated with blocks 910, 920, and 930 are not repeated here. Once photon-activated species are generated in the optical cavity at block 930, the photon-activated species may be leveraged to perform various processing steps such as etch, surface treatment, or chamber cleaning.

[0132] At block 940 of the process 950, one or more materials on the semiconductor substrate are etched, a surface of the semiconductor substrate is treated, a surface of the semiconductor substrate is cleaned, one or more materials are deposited on the semiconductor substrate, oxidation is performed on the semiconductor substrate, nitridation is performed on the semiconductor substrate, atomic layer etch is performed on the semiconductor substrate, or internal surfaces of the semiconductor processing chamber are cleaned. It will be understood that the photon-activated species may be used in a variety of contexts related to semiconductor processing.

[0133] In some implementations, the process 950 further includes etching one or more materials on the semiconductor substrate. One or more reactant gases for etching may include halogens such as F2, CI2, Br2, and I2, oxidants such as O2, NO, NO2, N2O, H2O2, and H2O, hydrogen halides such as HF, HC1, HBr, and HI, and other etchant chemistries such as HONO, GeF4, NF3, CH4, CHF3, SiF4, SFe, BCI3, and H2. Combinations of any of the aforementioned species may be employed in a gas mixture for etching. Material etch rate and selectivity may be controlled by tuning light source energy according to a selected wavelength or range of wavelengths. This can change the ratio of radicals in different excited states. Material etch rate and selectivity may be controlled bytuning light source intensity according to a selected intensity. This can change the ratio of radical atoms in the excited state to radical atoms or molecules in the ground state.

[0134] In some implementations of the process 950, etching the one or more materials comprises etching silicon oxide relative to silicon and / or silicon nitride, where the photon-activated species comprises radicals of an oxygen-containing gas and / or hydrogen-containing gas. In some implementations of the process 950, etching the one or more materials comprises etching silicon relative to silicon oxide and / or silicon nitride, where the photon-activated species comprises radicals of a halogen gas and / or methane gas. In some implementations of the process 950, etching the one or more materials comprises etching silicon relative to silicon-germanium, silicon oxide, silicon nitride, or combinations thereof, where the photon-activated species comprises radicals of a nitrogen-containing gas mixed with a fluorine-containing gas and / or hydrogen-containing gas. In some implementations of the process 950, etching the one or more materials comprises etching silicon nitride relative to silicon oxide, silicon, silicon-germanium, or combinations thereof, where the photon-activated species comprises radicals of a fluorine-containing gas and / or nitrogencontaining gas. In some implementations of the process 950, etching the one or more materials comprises etching a metal or metal oxide, where the photon-activated species comprises radicals of a fluorine-containing gas. In some implementations of the process 950, etching the one or more materials comprises etching silicon-germanium relative to silicon, where the photon-activated species comprises radicals of a fluorine-containing species and / or chlorine-containing species.

[0135] In some implementations, the process 950 further includes treating a surface of the semiconductor substrate. Treatment of the surface of the semiconductor substrate may involve removal of contaminants or removal of damaged layers. In some cases, high-energy ions from plasma may easily damage substrate layers and materials. This can include, for example, damaged Si, SiC>2, SiOCN, or SisN4. In some cases, carbon or polymer-based contaminants may form on the surface of the semiconductor substrate. This can include, for example, C, CH, CF, CHF, etc. The photon-activated species may treat the surface of the semiconductor substrate without damage to the semiconductor substrate or underlying films. In some implementations, the process 950 may include treatment of the surface of the semiconductor substrate by direct exposure to radiation from the light source. Such direct exposure may enhance desorption of byproducts on the surface of the semiconductor substrate.

[0136] In some implementations, the process 950 further includes cleaning internal surfaces of the semiconductor processing chamber. Unwanted materials may deposit on chamber walls, ceiling, floor, showerhead, substrate support, lift pins, gas lines, nozzles, etc. Such unwantedmaterials may include, for example, Si, C, CH, CF, CHF, metal, etc. Without using plasma, the unwanted materials may be removed by exposure to the photon-activated species. In some cases, the unwanted materials may be removed by exposure to radiation from the light source.

[0137] Figure 10 shows a schematic diagram of an example process tool for performing the disclosed implementations. The process tool may include an arrangement of transfer modules and processing modules that may be referred to as a “cluster tool architecture” system. The various modules may interface with a vacuum transfer module (VTM) 1038. Airlock 1030, also known as a loadlock or transfer module, is shown in VTM 1038 with four processing modules 1020a, 1020b, 1020c, and 1020d. The processing modules 1020a, 1020b, 1020c, and 1020d may be optimized to perform various fabrication processes. By way of example, processing modules 1020a, 1020b, 1020c, and 1020d may be implemented to perform substrate etching, deposition, substrate treatment, ion implantation, substrate cleaning, sputtering, and / or other semiconductor processes. One or more of the substrate processing modules (any of 1020a, 1020b, 1020c, and 1020d) may be implemented for performing substrate etching, substrate treatment, or chamber cleaning as disclosed herein using photon-activated species. Airlock 1030 and the process module 1020 may be referred to as “stations.” Each station has a facet 1036 that interfaces the station to the VTM 1038. Inside each facet, sensors 1-18 are used to detect the passing of the substrate 1026 when moved between respective stations.

[0138] Robot 1022 transfers the substrate 1026 between stations. In one embodiment, robot 1022 has one arm, and in another embodiment, robot 1022 has two arms, where each arm has an end effector 1024 to pick up substrates such as substrate 1026 for transport. Front-end robot 1032, in atmospheric transfer module (ATM) 1040, is used to transfer substrates 1026 from cassette or Front Opening Unified Pod (FOUP) 1034 in Load Port Module (LPM 1042 to airlock 1030. Module center 1028 inside process module 1020 is one location for placing the substrate 1026. Aligner 1044 in ATM 1040 is used to align substrates.

[0139] In an example processing method, a substrate is placed in one of the FOUPs 1034 in the LPM 1042. Front-end robot 1032 transfer the substrate from the FOUP 1034 to an aligner 1044, which allows the substrate 1026 to be properly centered before it is etched or processed. After being aligned, the substrate 1026 is moved by the front-end robot 1032 into an airlock 1030. Because airlock modules have the ability to match the environment between an ATM and a VTM, the substrate 1026 is able to move between two pressure environments without being damaged. From the airlock module 1030, the substrate 1026 is moved by robot 1022 through VTM 1038 and into one of the processing modules 1020a, 1020b, 1020c, and 1020d. In order to achieve thissubstrate movement, the robot 1022 uses end effectors 1024 on each of its arms. Once the substrate 1026 has been processed, it is moved by robot 1022 from the process modules 1020a, 1020b, 1020c, or 1020d to an airlock module 1030. From here, the substrate 1026 may be moved by the front-end robot 1032 to one of the FOUPs 1034 or to the aligner 1044.

[0140] The computer controlling the wafer movement can be local to the cluster architecture, or can be located external to the cluster architecture in the manufacturing floor, or in a remote location and connected to the cluster architecture via a network. A controller as described above with respect to Figures 1 and 2 may be implemented with the tool in Figure 10. CONCLUSION

[0141] It is understood that the examples and implementations described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art. Although various details have been omitted for clarity’s sake, various design alternatives may be implemented. Therefore, the present examples are to be considered as illustrative and not restrictive, and the disclosure is not to be limited to the details given herein, but may be modified within the scope of the disclosure.

Claims

CLAIMS1. A semiconductor processing apparatus comprising: a processing chamber; a substrate support configured to support a semiconductor substrate in the processing chamber; a gas distributor in fluid communication with the processing chamber; a gas source in fluid communication with the gas distributor, wherein the gas source is configured to supply one or more reactant gases to the gas distributor; and a light source configured to emit radiation to produce photon-activated species of at least one of the reactant gases.

2. The semiconductor processing apparatus of claim 1, wherein the light source is tuned to emit radiation having: (1) a selected intensity and, (2) a selected wavelength or range of wavelengths to obtain a desired energy distribution of the photon-activated species.

3. The semiconductor processing apparatus of claim 2, wherein the light source is tuned according to the selected wavelength or range of wavelengths to achieve a target etch rate and selectivity of one or more materials to be etched on the semiconductor substrate.

4. The semiconductor processing apparatus of claim 2, wherein the light source is tuned according to the selected intensity to achieve a target etch rate and selectivity of one or more materials to be etched on the semiconductor substrate.

5. The semiconductor processing apparatus of claim 2, wherein the one or more reactant gases comprise a mixture of reactant gases, wherein the light source is tuned according to the selected wavelength or range of wavelengths to selectively produce photon-activated species of one of the reactant gases in the mixture relative to a remainder of the reactant gases in the mixture.

6. The semiconductor processing apparatus of claim 1, further comprising: an optical cavity optically coupled to the light source to receive the radiation from the light source, wherein the at least one of the reactant gases is converted into the photon-activated species in the optical cavity.

7. The semiconductor processing apparatus of claim 6, wherein the optical cavity comprises a gas cell through which the one or more reactant gases flow through and an optical cell that surrounds the gas cell or sits above the gas cell, wherein the light source is positioned on one or more surfaces of the optical cell to emit the radiation through the gas cell.

8. The semiconductor processing apparatus of claim 7, wherein the optical cell has a geometry different than the gas cell.

9. The semiconductor processing apparatus of claim 7, wherein the optical cell has a cylindrical, rectangular, or octagonal geometry.

10. The semiconductor processing apparatus of claim 7, wherein the optical cell comprises one or more mirrors or a reflective material to reflect the emitted radiation from the light source.

11. The semiconductor processing apparatus of claim 7, wherein the gas cell comprises one or more mirrors or a reflective material to reflect the emitted radiation from the light source.

12. The semiconductor processing apparatus of claim 7, wherein a material of the gas cell is transparent or substantially transparent to the emitted radiation from the light source.

13. The semiconductor processing apparatus of claim 7, wherein the optical cell comprises a window that sits above the gas cell, wherein the light source is disposed on the window and comprises a plurality of light-emitting diodes (LEDs) that emit the radiation into the gas cell.

14. The semiconductor processing apparatus of claim 7, wherein the optical cell comprises a ring that surrounds the gas cell, wherein the light source is disposed on the ring and comprises a plurality of LEDs that emit the radiation into the gas cell.

15. The semiconductor processing apparatus of claim 6, wherein the optical cavity comprises one or more mirrors or reflective surfaces.

16. The semiconductor processing apparatus of claim 6, wherein the optical cavity is free of any mirrors or reflective surfaces.

17. The semiconductor processing apparatus of claim 1, wherein the light source comprises a laser.

18. The semiconductor processing apparatus of claim 1, wherein the light source comprises a flash lamp.

19. The semiconductor processing apparatus of claim 1, wherein the light source comprises a plurality of LEDs.

20. The semiconductor processing apparatus of claim 19, wherein the plurality of LEDs comprises a first LED configured to emit radiation at a first wavelength and a second LED configured to emit radiation at a second wavelength different than the first wavelength.

21. The semiconductor processing apparatus of claim 1, wherein the light source is further configured to expose the semiconductor substrate to the emitted radiation to promote or hinder surface reactions on the semiconductor substrate.

22. The semiconductor processing apparatus of claim 21, wherein the light source comprises a plurality of LEDs positioned above the gas distributor, wherein the gas distributor is transparent or substantially transparent to the emitted radiation.

23. The semiconductor processing apparatus of claim 1, wherein the optical cavity is positioned between the gas distributor and the gas source so that photon activation occurs prior to the gas distributor.

24. The semiconductor processing apparatus of claim 1, wherein the optical cavity is positioned in the gas distributor so that photon activation occurs in the gas distributor.

25. The semiconductor processing apparatus of claim 1, wherein the optical cavity is positioned in the processing chamber so that photon activation occurs in the processing chamber.

26. The semiconductor processing apparatus of claim 1, wherein the one or more reactant gases comprise a halogen gas, a hydrogen halide, an oxidant gas, nitrogen trifluoride, nitrousoxide, nitric oxide, nitrogen dioxide, methane, fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof.

27. The semiconductor processing apparatus of claim 1, wherein the photon- activated species of the at least one of the reactant gases comprises molecular radicals in a ground or excited state, atomic radicals in a ground or excited state, and / or energized reactant gases in an excited vibrational state.

28. A semiconductor processing apparatus comprising: a processing chamber; a substrate support configured to support a semiconductor substrate in the semiconductor processing chamber; a gas distributor in fluid communication with the semiconductor processing chamber; a gas source in fluid communication with the gas distributor, wherein the gas source is configured to supply one or more reactant gases in a ground state to the gas distributor; a light source configured to emit radiation and tuned to: (1) a selected intensity and (2) a selected wavelength or range of wavelengths; and an optical cavity positioned between the gas source and the gas distributor, wherein the optical cavity is configured to receive radiation from the light source and convert the one or more reactant gases into photon-activated species in the optical cavity.

29. A semiconductor processing apparatus comprising: a semiconductor processing chamber; a substrate support configured to support a semiconductor substrate in the semiconductor processing chamber; a gas distributor in fluid communication with the semiconductor processing chamber; a gas source in fluid communication with the gas distributor, wherein the gas source is configured to supply one or more reactant gases in a ground state to the gas distributor; and a light source configured to emit radiation and tuned to: (1) a selected intensity and (2) a selected wavelength or range of wavelengths, wherein the gas distributor serves as an optical cavity configured to receive radiation from the light source and convert the one or more reactant gases into photon-activated species in the gas distributor.

30. A semiconductor processing apparatus comprising: a processing chamber; a substrate support configured to support a semiconductor substrate in the processing chamber; a gas distributor in fluid communication with the processing chamber; a gas source in fluid communication with the gas distributor, wherein the gas source is configured to supply one or more reactant gases in a ground state to the gas distributor; and a light source configured to emit radiation and tuned to: (1) a selected intensity and (2) a selected wavelength or range of wavelengths, wherein the processing chamber serves as an optical cavity configured to receive radiation from the light source and convert the one or more reactant gases into photon-activated species in the processing chamber.

31. A method of generating photon-activated species for use in a processing chamber, the method comprising: flowing one or more reactant gases towards a gas distributor for distributing the one or more reactant gases into the processing chamber; emitting radiation from a light source at: (1) a selected intensity and (2) a selected wavelength or range of wavelengths; and producing photon-activated species of at least one of the reactant gases in an optical cavity by exposing the one or more reactant gases to the emitted radiation from the light source.

32. The method of claim 31, further comprising: etching one or more materials on a semiconductor substrate in the processing chamber by exposing the semiconductor substrate to the photon-activated species.

33. The method of claim 32, wherein the one or more materials are etched at an etch rate and selectivity based at least in part on one or both of: (1) the selected intensity and (2) the selected wavelength or range of wavelengths.

34. The method of claim 32, wherein etching the one or more materials comprises etching silicon oxide relative to silicon and / or silicon nitride, wherein the photon-activated species comprises radicals of an oxygen-containing gas and / or hydrogen-containing gas.

35. The method of claim 32, wherein etching the one or more materials comprises etching silicon relative to silicon oxide and / or silicon nitride, wherein the photon-activated species comprises radicals of a halogen gas and / or methane gas.

36. The method of claim 32, wherein etching the one or more materials comprises etching silicon relative to silicon-germanium, silicon oxide, silicon nitride, or combinations thereof, wherein the photon-activated species comprises radicals of a nitrogen-containing gas mixed with a fluorine-containing gas and / or hydrogen-containing gas.

37. The method of claim 32, wherein etching the one or more materials comprises etching silicon nitride relative to silicon oxide, silicon, silicon-germanium, or combinations thereof, wherein the photon-activated species comprises radicals of a fluorine-containing gas and / or nitrogen-containing gas.

38. The method of claim 32, wherein etching the one or more materials comprises etching a metal or metal oxide, wherein the photon-activated species comprises radicals of a fluorine- containing gas.

39. The method of claim 32, further comprising: treating a surface of the semiconductor substrate by exposing the semiconductor substrate to the photon-activated species to desorb etch byproducts from the surface of the semiconductor substrate.

40. The method of claim 32, wherein etching the one or more materials comprises etching silicon-germanium relative to silicon, wherein the photon-activated species comprises radicals of a fluorine-containing species and / or chlorine-containing species.

41. The method of claim 32, wherein a concentration of the photon-activated species for etching the one or more materials is tunable by controlling: (1) the selected intensity of the emitted radiation and (2) the selected wavelength of the emitted radiation.

42. The method of claim 31, further comprising: treating a surface of a semiconductor substrate in the processing chamber by exposing the semiconductor substrate to the photon-activated species.

43. The method of claim 31, further comprising: cleaning internal surfaces of the processing chamber by exposing the internal surfaces to the photon-activated species.

44. The method of claim 31, wherein the optical cavity is upstream of the gas distributor, integrated with the gas distributor, or integrated with the processing chamber.

45. The method of claim 31, wherein the optical cavity comprises one or more mirrors or a reflective material configured to reflect the radiation emitted from the light source in the optical cavity.

46. The method of claim 31, wherein the light source comprises a plurality of LEDs, wherein the plurality of LEDs emit at the same wavelength or a combination of different wavelengths.

47. The method of claim 31, wherein the photon-activated species are produced independent of any plasma.

48. The method of claim 31, wherein the photon-activated species comprises molecular radicals in a ground or excited state, atomic radicals in a ground or excited state, and / or energized reactant gases in an excited vibrational state.

49. The method of claim 31, wherein the one or more reactant gases comprise a halogen gas, a hydrogen halide, an oxidant gas, nitrogen trifluoride, nitrous oxide, nitric oxide, nitrogen dioxide, methane, fluoromethane, trifluoromethane, ammonia, hydrogen gas, sulfur hexafluoride, silicon tetrafluoride, or combinations thereof.

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