Particle mitigation by purging

Abstract

Purging of flow paths to remove particle defects includes charging each flow path with inert gas and discharging to dislodge particles that may then be removed. Each flow path may be discharged to a divert or to a process chamber to reduce the number of particles that may then deposit on substrates during semiconductor fabrication operations.

Description

PARTICLE MITIGATION BY PURGINGRELATED APPLICATION(S)

[0000] 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.BACKGROUND

[0001] Particles and metal contamination on process wafers are a leading cause of product failure. Driven by ever smaller technology nodes, semiconductor device fabrication systems constantly advance. New process systems require new hardware components, increasingly complex assemblies, new manufacturing methods, and a close control on cleaning and handling techniques. The introduction of new parts can be a major source of particles on wafers. In addition, changes in existing process conditions can result in particle generation. Particles introduce device defects, which decrease yield and require cleaning procedures or part replacements to remove sources of particles.

[0002] The background description provided herein is for the purposes of generally presenting the context of the disclosure. 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 otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0003] Disclosed herein are methods and systems of filling purging flow paths fluidically connected with a process chamber. In one aspect of the embodiments herein, a system is provided the system including: a process chamber including a plurality of stations, wherein each station includes a showerhead, wherein the process chamber includes a plurality of flow paths, each flow path fluidically connected with at least one showerhead and each flow path fluidically connected with a vacuum pump; and a controller including memory and processors configured for (a) performing one or more cycles of: charging one or more flow paths to a first pressure with an inert gas; discharging the one or more flow paths towards the vacuum pump; charging the one or more flow paths to a second pressure with the inert gas; and discharging the one or more flow paths towards the at least one showerhead.

[0004] In some embodiments, each flow path includes a first valve that controls a flow of gas towards the vacuum pump and a second valve that controls the flow of gas towards the at least one showerhead. In some embodiments, each flow path includes a charge volume. In some embodiments, a first flow path of the plurality of flow paths is fluidically connected with a precursor species source, and wherein the controller is additionally configured for: (b) performing one or more cycles of: charging the first flow path to the first pressure with the inert gas; discharging the first flow path towards the vacuum pump; charging the first flow path to the second pressure with the inert gas; and discharging the first flow path towards the at least one showerhead, wherein (b) occurs before (a). In some embodiments, a precursor species flowed from the precursor species source is a halogenated metal precursor species. In some embodiments, the at least one showerhead includes a first showerhead and two or more second showerheads, the first showerhead being different from the second showerhead, and wherein a first flow path of the plurality of flow paths is fluidically connected with a first precursor species source and the first showerhead, and a second flow path of the plurality of flow paths is fluidically connected with a second precursor species source and the two or more second showerheads, and wherein the controller is additionally configured for: (b) performing one or more cycles of: charging the first flow path to the first pressure with the inert gas; discharging the first flow path towards the vacuum pump; charging the first flow path to the second pressure with the inert gas; and discharging the first flow path towards the first showerhead; and (c) performing one or more cycles of: charging the second flow path to the first pressure with the inert gas; discharging the second flow path towards the vacuum pump; charging the second flow path to the second pressure with the inert gas; and discharging the second flow path towards the two or more showerheads, wherein (b) and (c) occur before (a). In some embodiments, a third flow path of the plurality of flow paths is fluidically connected with an inert gas source, and wherein the controller is additionally configured for: (b) performing one or more cycles of: charging the third flow path to the second pressure with the inert gas; and discharging the third flow path towards the at least one showerhead, wherein (b) is performed after (a). In some embodiments, a fourth flow path of the plurality of flow paths is fluidically connected with an ampoule including a metal precursor, and wherein the controller is additionally configured for: (b) performing one or more cycles of: charging the fourth flow path to the second pressure with the inert gas; and discharging the fourth flow path towards the vacuum pump, wherein (b) is performed before (a).

[0005] In some embodiments, the process chamber further includes a piezo assembly connected to the fourth flow path, wherein before, during, or before and during (b) the piezo assembly vibrates a portion of the fourth flow path. In some embodiments, the first pressure is at least about1500 Torr. In some embodiments, the first pressure is at least about 2500 Torr. In some embodiments, the first pressure and the second pressure are the same pressure. In some embodiments, a first subset of flow paths of the plurality of flow paths are each fluidically connected to a precursor species source or a reactant source, and (a) is performed for each flow path of the first subset of flow paths. In some embodiments, (a) is not performed for a second subset of flow paths of the plurality of flow paths, the second subset of flow paths including different flow paths than the first subset of flow paths. In some embodiments, discharging is performed until the flow path reaches a third pressure. In some embodiments, the third pressure is less than about 10 Torr. In some embodiments, (a) is performed at least about 50 times for each flow path. In some embodiments, the process chamber includes a first flow path fluidically connected with a precursor gas source, a second flow path fluidically connected with a reactant source, and a third flow path fluidically connected with an inert gas source. In some embodiments, the first flow path includes a first valve that controls the flow of gases towards a first showerhead. In some embodiments, the second flow path includes a second valve that controls the flow of gases towards the first valve. In some embodiments, the third flow path includes a third valve that controls the flow of gases towards the second valve. In some embodiments, during discharging of the one or more flow paths towards the at least one showerhead an inert gas is flowing towards the showerhead by a different flow path. In some embodiments, the controller is additionally configured for: (b) performing one or more cycles of: charging one or more flow paths to a third pressure with the inert gas; discharging the one or more flow paths towards the vacuum pump; charging the one or more flow paths to a fourth pressure with the inert gas; and discharging the one or more flow paths towards the at least one showerhead, wherein the third pressure and the fourth pressure are both less than the first pressure and the second pressure. In some embodiments, the third pressure and the fourth pressure are between about 600 Torr and about 1500 Torr.

[0006] In another aspect of the embodiments herein, a method is provided the method including: providing a process chamber including a plurality of stations, wherein each station includes a showerhead, wherein the process chamber includes a plurality of flow paths, each flow path fluidically connected with at least one showerhead and each flow path fluidically connected with a vacuum pump; and performing one or more cycles of: charging one or more flow paths to a first pressure with an inert gas; discharging the one or more flow paths towards the vacuum pump; charging the one or more flow paths to a second pressure with the inert gas; and discharging the one or more flow paths towards the at least one showerhead.

[0007] These and other features of the disclosed embodiments will be described in detail below with reference to the associated drawings.BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 presents a defect map illustrating particle defects on a wafer.

[0009] Figure 2 presents a schematic diagram of a reactant delivery system according to various embodiments herein.

[0010] Figure 3 presents a flow diagram of operations for purging flow paths.

[0011] Figure 4 presents another flow diagram of purging a flow path.

[0012] Figures 5A-5F present schematic diagrams highlighting various flow paths.

[0013] Figures 6-9 are schematic diagrams of examples of process chambers for performing methods in accordance with disclosed embodiments.

[0014] Figures 10 and 11 present experimental data illustrating particle defects before and after performing embodiments disclosed herein.DETAILED DESCRIPTION

[0015] 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 these 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.Terminology

[0016] The term “flow control hardware” generally represents components configured to place one or more chemical sources in fluid connection with a processing chamber. Flow control hardware can comprise one or more mass flow controllers and / or valves, for example. Example chemical sources include dielectric film precursor sources, halogen-containing precursor sources, reactant gas sources, and inert gas sources.

[0017] The term “forming a gas mixture” generally represents either of or both of mixing a plurality of gases before introducing the plurality of gases into the processing chamber or mixing a plurality of gases in the processing chamber.

[0018] The term “inert gas” generally represents a gas phase material that does not react with other chemicals in a processing chamber during substrate processing. Example inert gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe), as well as nitrogen (N2) in some processes.

[0019] The term “plasma” generally represents a gas comprising ions, free radicals, and free electrons. The term “in-situ plasma” generally represents a plasma formed at a processing station in a processing chamber. The term “remote plasma” generally represents a plasma formed at a location away from a processing station in a processing chamber.

[0020] The term “plasma generator” generally represents a combination of components that can be used to form a plasma. Example components include a radiofrequency power source, an impedance matching network, and one or more electrodes.

[0021] The term “precursor” generally represents a chemical species that is reacted to form an elemental or compound film layer containing an element of the chemical species. A precursor may react with a reactant to form the film layer. In some embodiments of an atomic layer deposition (ALD) process, for example, a precursor may be adsorbed on the surface of a substrate. A reactant may react with the adsorbed precursor to convert it to the film layer. In some embodiments a precursor may be corrosive. Corrosive precursors may generate particles from valves or other parts within a fluid delivery system.

[0022] The term “processing chamber” or “process chamber” generally represents an enclosure in which chemical and / or physical processes are performed on substrates. The pressure, substrate temperature and atmospheric composition within a processing chamber can be controllable to perform the chemical and / or physical processes.

[0023] The term “processing tool” may generally represent a machine including a processing chamber and other hardware configured to enable processing to be carried out in the processing chamber.

[0024] The term “processing station” generally represents a location in a processing chamber at which a substrate is positioned during processing.

[0025] The term “reactant” generally represents a chemical species that reacts with a precursor adsorbed to a substrate surface to form a film layer in an ALD process. A reaction between a reactant and a precursor can be facilitated by thermal energy and / or a plasma in various processes.

[0026] The phrase “fluidically connected” may be used herein to describe connections between two or more components that place such components in fluidic communication with one another, much in the same manner that “electrically connected” may be used to describe an electrical connection between two or more components. The phrase “fluidically interposed” may be used, for example, to describe a particular ordering of components. For example, if component B is fluidically interposed between components A and C, then fluid flowing from component A to component C would flow through component B before reaching component C. Fluidicallyconnected may refer to direct and indirect connections between such components, including other components fluidically interposed between the components.

[0027] The implementations disclosed below describe deposition 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 and Context

[0028] ALD is a technique that deposits thin layers of material using sequential self-limiting reactions. ALD processes use surface-mediated deposition reactions to deposit films on a layer bylayer basis in cycles. As an example, an ALD cycle may include the following operations: (i) delivery / adsorption of a precursor, (ii) purging of precursor from the chamber, (iii) delivery of a second reactant and optionally ignite plasma, and (iv) purging of byproducts from the chamber. The reaction between the second reactant and the adsorbed precursor to form a film on the surface of a substrate affects the film composition and properties, such as non uniformity, stress, wet etch rate, dry etch rate, electrical properties (e.g., breakdown voltage and leakage current), etc. In ALD deposition of silicon oxide films, this reaction involves reacting oxygen plasma with carbon and nitrogen to form a gaseous species; oxidizing silicon to silicon oxide; eliminating trace carbon, nitrogen, and hydrogen impurities; and increasing bonding and densification of the film.

[0029] Unlike a chemical vapor deposition (CVD) technique, ALD processes use surface mediated deposition reactions to deposit films on a layer-by-layer basis. In one example of an ALD process, a substrate surface that includes a population of surface- active sites is exposed to a gas phase distribution of a first precursor, such as a silicon-containing precursor, in a dose provided toa chamber housing a substrate. Molecules of this first precursor are adsorbed onto the substrate surface, including chemisorbed species and / or physisorbed molecules of the first precursor. It should be understood that when a compound is adsorbed onto the substrate surface as described herein, the adsorbed layer may include the compound as well as derivatives of the compound. For example, an adsorbed layer of a silicon-containing precursor may include the silicon-containing precursor as well as derivatives of the silicon-containing precursor. After a first precursor dose, the chamber is then evacuated to remove most or all of first precursor remaining in gas phase so that mostly or only the adsorbed species remain. In some implementations, the chamber may not be fully evacuated. For example, the reactor may be evacuated such that the partial pressure of the first precursor in gas phase is sufficiently low to mitigate a reaction. A second reactant, such as an hydrogen-containing gas, is introduced to the chamber so that some of these molecules react with the first precursor adsorbed on the surface. In some processes, the second precursor reacts immediately with the adsorbed first precursor. In other embodiments, the second reactant reacts only after a source of activation is applied temporally. The chamber may then be evacuated again to remove unbound second reactant molecules. As described above, in some embodiments the chamber may not be completely evacuated. Additional ALD cycles may be used to build film thickness.

[0030] In some implementations, the ALD methods include plasma activation. As described herein, the ALD methods and apparatuses described herein may be conformal film deposition (CFD) methods, which are described generally in U.S. Patent Application No. 13 / 084,399 (now U.S. Patent No. 8,728,956), filed April 11, 2011, and titled “PLASMA ACTIVATED CONFORMAL FILM DEPOSITION,” and in U.S. Patent Application No. 13 / 084,305, filed April 11, 2011, and titled “SILICON NITRIDE FILMS AND METHODS,” which are herein incorporated by reference in their entireties.

[0031] The present disclosure relates to a purging protocol to mitigate particle defects on substrates. Defects come from defect sources, which are process operations and / or equipment component that produces particles or other conditions that lead to defects on a semiconductor substrate. For example, ALD cycles as described above may generate particle defects as valves are opened and closed to control flow of precursors and reactants. Examples of equipment components that may be defect sources include showerheads, rings, dielectric windows, process chamber walls, gas lines, elastomer coatings, wafer transport systems, and fluid delivery systems. In some cases, all process parts exposed to fabrication chemistry are potential defect sources. For example, precursors may be corrosive, generating particles from various components such as flow control hardware in a fluid delivery system. Corrosive precursors may include halogenated metalprecursors such as molybdenum dichloride dioxide (MOO2CI2). The resulting defects of any these sources may be particles, scumming, bridging, pinholes, and the like. Mechanical wear of components may also be a defect source.

[0032] A process chamber may have a plurality of flow paths that fluidically connect a showerhead to various reactant, precursor, and inert gas sources. These flow paths may become a source of particles, which may then deposit on a substrate and become defects. During fabrication operations particles may deposit within these flow paths and eventually flow towards a substrate, where they deposit as defects. Thus, it is desirable to purge the flow paths to remove such particles and reduce the number of particles that may deposit as defects. Figure 1 illustrates an example defect map 102.

[0033] Defects may be characterized by size. In some embodiments, one or more bins may be defined for particle defects based on the size of the particle, e.g., a bin for particles greater or less than about 25 nm. In some embodiments, particles greater than a certain size are more likely to cause a malfunctioning of a semiconductor device being fabricated than smaller particles. Thus, it may be desirable to minimize the number of larger particles.

[0034] Particle defects may be counted using a blank wafer and then performing a semiconductor fabrication operation. After performing the operation, the blank wafer will have a multitude of particle defects deposited thereon, which may then be counted to determine a normalized number of particle defects. Lower numbers are preferable.

[0035] Figure 2 illustrates a fluid delivery system 200 for a four-station process chamber (also referred to as a “quad-station process chamber”). Fluid delivery system 200 has a plurality of flow paths 250a-256 that are each fluidically connected with at least one source, as well as a showerhead and a divert. The sources may differ for each flow path, e.g., an inert gas source (220a- b), a hydrogen source (222a-b), an ammonia source (226), and a precursor “P” source (224a-b). While sources shown in the figures and described herein may refer to a specific reactant or gas, e.g., Argon, H2, or NH3, it should be understood that other inert gases and reactants may be used. For example, Ar source 220b may be a source for any inert gas. Similarly, FL source 222a and NH3 source 226 may instead be a source for other reactant gases, e.g., O2 or N2O. Precursor source 224a may also be a source for various precursors and is not limited to specific precursors disclosed herein. Sources of gases may include ampoules of gas that may be directly connected with flow paths of a process chamber. Sources of gases may also include fluidic connections to a main source line of a fabrication facility.

[0036] In some embodiments, a source may further comprise or be fluidically connected toanother source. For example, H2 source 222a-b and NH3 source 226 may be independently connected to an inert gas source (not shown). Furthermore, as shown in Figure 2, P source 224b may include an ampoule 212 that contains a metal precursor, an ampoule valve 216 that may control the flow of precursors, a piezo assembly 210, and a restricted flow orifice (RFO) 214 that restricts the flow of precursors. As some precursors may be highly toxic or otherwise dangerous, an RFO may be used to limit the flow of such precursors independently of a valve. P source 224b is also connected to Ar source 220d, which may flow inert gas to dilute the precursor gas. P source 224a may have similar or different components and flow paths (not shown).

[0037] In some embodiments, piezo assembly 210 may be part of P source 224b. A piezo assembly converts electrical charge into mechanical energy, namely vibrations. In some embodiments, a piezo assembly may be configured to vibrate the flow path at a frequency of between about 15-400 kHz. As discussed further below, P source 224b may be a significant defect source for particles, in part due to corrosive precursor species that are flowed from P source 224b and corrode components of the flow path such as valves or an RFO plate. As shown in Figure 3, piezo assembly 210 is connected to the flow path before and after RFO 214. In some embodiments, a piezo assembly may be connected to the flow path prior to and / or after an RFO plate. The RFO plate may be a significant source of particle defects from corrosion, and a piezo assembly may help dislodge such particles. These particles may deposit within flow paths and then flow through the showerhead to deposit as defects. Purging as discussed herein may dislodge these particles. In some embodiments, the piezo assembly may be used to vibrate a portion of the flow path near the piezo assembly, further dislodging particles to be removed by purging. While a piezo assembly is discussed herein, other parts or assemblies that may vibrate portions of the flow path at the frequency noted above may also be used. In some embodiments, a piezo assembly may not be present.

[0038] Each flow path may fluidically connect to a showerhead, and each showerhead may have gas distribution ports that flow gas into a process chamber (not shown). Each flow path may also fluidically connect with a divert via divert flow path 258. A divert is a waste product sink where gases may be flowed to instead of the showerhead. A divert may typically be fluidically connected to a vacuum pump such that the pressure at the divert is very low, e.g., less than 10 mTorr. In Figure 2 a single divert 204 is shown, however it should be understood that multiple diverts or flow paths to divert may exist in a process chamber. In some embodiments each flow path may have a connection to separate diverts. When a valve is opened to divert, process gas will flow towards divert 204 along a portion of divert flow path 258.

[0039] In some embodiments, each showerhead may have a set of flow paths that areindependent of flow paths to other showerheads, e.g., a flow path from a source to a showerhead will not overlap with flow paths from a source to other showerheads. In other embodiments, two or more showerheads may share a flow path from a single source and have overlapping flow paths. In Figure 2, showerhead 208a is fluidically connected with each of Ar source 220a via inert flow path 250a, NH3 source 226 via reactant flow path 256, H2 source 222a via reactant flow path 252a, and P source 224a via precursor flow path 254a. These sources are not fluidically connected to any other showerheads. Conversely, showerheads 208b-d have partially overlapping flow paths from Ar source 220b via inert flow path 250b, H source 222b via reactant flow path 252b, and P source 224b via precursor flow path 254b. A flow path to one of showerheads 208b-d from each source will at least partially overlap with another flow path to another of showerheads 208b-d from each source.

[0040] In some embodiments, multiple showerheads may have partially overlapping flow paths as similar or the same semiconductor fabrication operations may be performed at each showerhead. For example, showerheads 208b-d may each perform the same fabrication operations, and thus the same reactants, precursors, and / or inert gas flows may be provided to each showerhead. This may be more efficient and cost-effective than independent flow paths when performing similar or identical fabrication operations.

[0041] In some embodiments, one showerhead may perform a different fabrication operation and thus have independent flow paths. For example, showerhead 208a may be used to deposit a liner layer based on a different recipe than performed with showerheads 208b-d. The different recipe may require different reactants, such as NH3, than other recipes performed at showerheads 208b-d, and may also require different flow rates for precursors, reactants, and / or inert gases.

[0042] Each flow path may also be fluidically connected with or through various valves, pressure gauges, and charge volumes. In some embodiments, source valves may control introduction of gases into flow paths from a source. Inert gas source valve 270 may control introduction of inert gases from Ar source 220b. Reactant source valve 272 may control introduction of reactant gases from H2 source 222b. Precursor source valve 274 may control introduction of precursor gases from P source 224b.

[0043] In addition to source valves, there are also divert valves that control the flow of reactants to divert 204. Inert divert valve 280 may control the flow of gases from inert gas flow paths towards the divert. Reactant divert valve 282 may control the flow of gases from reactant gas flow paths towards the divert. Precursor divert valve 284 may control the flow of gases from precursor gas flow paths towards the divert.

[0044] In some embodiments, valves described herein may be two-way or three-way valves. A two-way valve may control the flow of gases from an inlet to an outlet. A three-way valve may be either a mixing valve or a diverting valve. A mixing valve may have two inlets of gases that are combined into a single outlet. A diverting valve may have one inlet and two outlets. Where a valve has multiple inlets or outlets, each inlet and outlet may be separately controlled such that the valve does not allow gas flows, allows gas flows through one inlet and one outlet, allows gas flows through one inlet and two outlets, or allows gas flows through two inlets and one outlet. While some valves are described as two-way valves, such as source valves 270-274 and divert valves 280-284, these valves may also be combined into three-way valves having an inlet from a source and outlets to a divert flow path or a flow path towards a showerhead.

[0045] Divert source valves 290, 292, 294, and 296 illustrate three-way valves that fluidically connect a gas source, a divert, and showerhead 208a. Inert divert source valve 290 may control the flow of gases from Ar source 220a towards the divert or showerhead 208a. Reactant divert source valve 292 may control the flow of gases from H2 source 222b towards the divert or showerhead 208a. Secondary reactant divert source valve 296 may control the flow of gases from NH3 source 226 towards the divert or showerhead 208a. Precursor divert source valve 294 may control the flow of gases from P source 224a towards the divert or showerhead 208a.

[0046] In some embodiments, each flow path may be fluidically connected with one or more corresponding charge volumes. A charge volume (CV) may be a canister that receives a process gas supplied by a gas source. In some embodiments, a CV may have a volume between about 0.1 liters and about 5 liters. The CV temporarily stores the process gas and supplies the process gas to a processing chamber in a controlled manner. As the process gas is supplied (i.e., discharged) from the CV to the processing chamber, an additional volume of the process gas may be supplied from a gas source to the CV to recharge the CV. As show in Figure 2, an Ar CV 260a is fluidically connected to flow path 250a. Similarly, Ar CV 260b-d are each fluidically connected to flow path 250b. H2 CV 262a is fluidically connected to flow path 252a. Similarly, H2 CV 262b-d are each fluidically connected to flow path 252b. P CV 264a is fluidically connected to flow path 254a. Similarly, P CV 264b-d are each fluidically connected to flow path 254b. NH3 CV 266 is fluidically connected to flow path 256.

[0047] In some embodiments, each flow path may be fluidically connected with one or more corresponding showerhead valves. Showerhead valves 230a-d may control the flow of inert gas. Showerhead valves 232a-d and 236 may control the flow of reactant gas. Showerhead valves 234a-d may control the flow of precursor gas. Each showerhead valve may be a three-way valve having two inlets and one outlet. The showerhead valve closest to the showerhead, e.g.,showerhead valves 234a-d, may have outlets that fluidically connect to gas distribution ports of the showerhead and flow gases into a process chamber. Each of showerhead valves 230a-d, 232a- d, and 236 may each have outlets that are fluidically connected to another showerhead valve as shown. Correspondingly, each of showerhead valves 232a-d, 234a-d, and 236 may have a first inlet that is fluidically connected to a charge volume and a second inlet that is fluidically connected to another showerhead valve. In some embodiments, gases from each source may be mixed as they flow through each showerhead valve. Thus, in embodiments where, e.g., an inert gas is flowed with a reactant, the inert gas and reactant gas may mix as they flow through showerhead valves 252a-d and showerhead valves 254a-d. It should be understood that in some embodiments gases may flow through showerhead valves that may also have another inlet for other process gases but are closed to such gases, e.g., showerhead valves 254a-d may be closed to precursor gases but open to reactant and inert gases.

[0048] Showerhead valves 230a-d may each be fluidically connected to a trickle purge source 206. Trickle inert source 206 is a source of inert gas that may be flowed to ensure a downstream flow of gas through each showerhead valve towards the corresponding showerhead. This may prevent or inhibit the undesirable backflow of gases through valves and other flow paths. In some embodiments, one or more trickle flow paths may be defined between trickle inert source 206 and each of showerheads 208a-d. Inert gas may be flowed along the trickle flow path during purging operations as described herein to inhibit backflow of gases.

[0049] In some embodiments, precursor showerhead valves 264a-d are fluidically closest to corresponding showerheads 208a-d as precursor species may be highly corrosive and thus generate particles that can lead to defects. By minimizing the flow path of precursor species and the number of valves precursor species flow through, corrosion of parts and generation of particles may be minimized.

[0050] Similarly, in some embodiments inert gas showerhead valves 230a-d may be fluidically upstream of all other valves. Inert gas may typically be used as a carrier or dilution gas to advect other process gases through flow paths towards the process chamber. Thus, in some embodiments an inert gas showerhead valve may be positioned upstream of reactant or precursor showerhead valves to facilitate mixing of the inert gas with the reactant or precursor gases.

[0051] In some embodiments, pressure gauges may be fluidically connected with each flow path to measure a pressure of each flow path. Pressure gauges 240a, 242a, 244a, and 246 may be respectively connected with flow paths 250a, 252a, 254a, and 256. Similarly, pressure gauges 240b, 242b, and 244b may be respectively connected with flow paths 250b, 252b, and 254b. In some embodiments, a pressure gauge may be used during purging of flow paths to measure thepressure in each flow path. When the pressure of each flow path to be purged reaches a predetermined pressure, the flow path may then be discharged. In some embodiments, the pressure gauges cannot measure the pressure above a first limit lower than the desired pressure for purging flow paths. In such embodiments, the rate of pressure increase within the range measurable by a pressure gauge may be determined and the pressure of the flow path extrapolated when the pressure exceeds the range measurable by the pressure gauge.

[0052] Figures 3 and 4 disclose flow charts for how flow paths may be purged. Flow paths to be purged are shown in Figures 5A-5F. Figures 5 A-5F illustrate flow paths using dashed lines. Figure 3 discloses an order of flow paths to be purged, while Figure 4 discloses how each flow path may be purged. Starting with Figure 3, one or more precursor flow paths may be purged to divert one or more times (302). In some embodiments, each flow path is sequentially purged, while in other embodiments two or more flow paths may be simultaneously purged. Figure 5A illustrates precursor flow paths using dashed lines. Depending on the configuration of the tool, there may be one, two, or more than two precursor flow paths. Figure 5A illustrates two precursor flow paths: a first precursor flow path 254a fluidically defined between inert source valve 270c and showerhead valve 234a, which may include P source 224a, source divert valve 294 (which is at least initially closed to divert), P CV 264a. A second precursor flow path 254b may be fluidically defined between inert source valve 270d and showerhead valves 234b-d, which may include P source 224b and P CV 264b-d.

[0053] Figure 4 describes a method of purging. A flow path is identified (402). One or more valves may be closed to isolate the flow path. In some embodiments, the flow path is closed except for an inlet for an inert gas source. In some embodiments this must be performed to prevent the flow of toxic or dangerous chemistry at high pressure, e.g., halogenated precursors may not be flowed above a pressure limit that is much lower than the pressure to be used for purging. In some embodiments, each source shown in Figure 2 and Figures 5A-5F may be additionally fluidically connected to an inert gas source. This is shown explicitly for Ar source 220c and 220d and is not shown for other sources.

[0054] The flow path is charged to a first pressure with inert gas (406). In some embodiments, the first pressure is at least about 1500 Torr, at least about 1800 Torr, at least about 2000 Torr, at least about 2500 Torr, at least about 2600 Torr, between about 2000 Torr and about 3000 Torr, between about 2000 Torr and about 4000 Torr, or between about 3000 Torr and about 4000 Torr. As noted above, in some embodiments a pressures gauge may have an upper limit on measurable pressures that is less than the first pressure. In such embodiments, the pressure of the flow path may be extrapolated based on the change in pressure during charging within the measurable rangeof the pressure gauge.

[0055] The flow path may then be discharged to a second pressure (408). The second pressure may be a pressure less than about 100 Torr, less than about 10 Torr, less than about 1 Torr, between about 0. 1 Torr and 1 Torr, or between about 1 Torr and 10 Torr. The flow path may be discharged to either the divert valve or the showerhead. The divert valve is preferable to discharge to first to reduce the number of particles that flow through the showerhead and into the process chamber. During discharge, the pressure difference between the flow path and the divert or showerhead may be substantially the pressure of the flow path, as the pressure of the divert or showerhead may be less than about 100 mTorr. This large pressure differential may result in a supersonic flow, which dislodges particles throughout the flow path and thus advects such particles (i.e., transports the particles by bulk motion of the inert gas), purging the flow path of particles.

[0056] In some embodiments, discharge of inert gas from the flow path may be a choked flow. Choked flow may occur if the pressure ratio between a high-pressure environment and a low- pressure environment is great enough. The velocity of fluid flow will not increase with a further decrease in pressure of the low-pressure environment, and the flow is considered choked. The minimum pressure ratio for choked flow depends on the particular gases used, though generally is around 2:1. Choked flow can be modeled using only the conditions of the high-pressure environment, including temperature, pressure, and gas density, which may be desirable when the parameters of the low pressure environment are unknown or changing. Specifically, when purging a flow path, choked flow is relevant as a factor to reduce the time required to sufficiently purge the flow path. While a higher pressure of the flow path may not increase the gas velocity, it may increase the duration of choked flow, improving the dislodging of particles.

[0057] In some embodiments, the pressure a flow path is charged to may change between cycles. In some embodiments, it can be time consuming to perform a single purge cycle; a single purge cycle may take minutes to complete. Considering the number of flow paths to purge, multiple purge cycles for each flow path may take several hours, which is undesirable as it decreases overall throughput. Most of this time per cycle is spent charging the flow path to a desired pressure. Thus, in some embodiments, the first pressure may be decreased for one or more cycles. The first pressure may be relatively high, as noted above, to dislodge particles that may stick to various portions of a flow path. Such particles may remain in the flow path after one or more purge cycles discharging from the first pressure. Such particles may then be evacuated with a discharge at a lower pressure.

[0058] In some embodiments, after charging and discharging a flow path from a first pressure, the flow path may be charged to and discharged from a third pressure that is lower than the firstpressure. In such embodiments, the flow path may be discharged to a fourth pressure that is the same as or different than the second pressure. The third pressure is lower than the first pressure, which may decrease the time spent charging the flow path and thus decrease the time per cycle when charging to the third pressure compared to charging to the first pressure. In some embodiments, the third pressure may be between about 600 Torr and about 1500 Torr, between about 90 Torr and about 1700 Torr, or between about 700 Torr and about 2000 Torr.

[0059] In some embodiments, the first pressure may change between operations of Figure 3. For example, operation 302 may be performed by discharging from a first charged pressure and operation 304 may be performed by discharging from a second charged pressure different from the first charged pressure. In some embodiments the same charged pressure may be used for all operations.

[0060] Discharge may be performed by opening the outlet on either a divert valve or a showerhead valve. For example, returning to Figure 5A, a discharge to divert may be performed by opening source divert valve 294 and divert valve 284. Conversely, a discharge to showerhead may be performed by opening showerhead valves 234a-d.

[0061] In some embodiments, the flowchart of Figure 4 may be repeated one or more times. In some embodiments, the process may be at least two times, at least 10 times, at least about 50 times, or at least 100 times. The number of cycles may depend on the defect particles measured, where a greater number of cycles may be performed based on determining a greater number of particles are present prior to purging.

[0062] Returning to Figure 3, precursor flow paths may be purged to divert one or more times in operation 302. Then, precursor flow paths may be purged to the showerhead one or more times. In some embodiments, the precursor flow path is the same for operations 302 and 304 except for changing the valve opened to discharge the flow path. As noted above, it is preferable to first purge a flow path to divert prior to purging to the showerhead as that reduces the number of particles flowing into the process chamber. The flow path may also be discharged to the showerhead as the showerhead may contain many particles than can then become defects on substrates; purging through the showerhead may thus dislodge an purge such particles, which may be evacuated from the process chamber through a divert or vacuum pump connected to a chamber body below the showerhead.

[0063] In some embodiments, operations 302 and 304 may be cycled m times. In some embodiments, m may be at least two times, at least 10 times, at least about 50 times, or at least 100 times. The number of cycles may depend on the defect particles measured, where a greaternumber of cycles may be performed based on determining a greater number of particles are present prior to purging.

[0064] In some embodiments, a precursor flow path may also include a flow path fluidically defined by ampoule 212, ampoule valve 216 and ampoule divert valve 218. In some embodiments, particles may build up behind RFO 214, however the flow through RFO 214 is restricted, limiting the ability to generate a large flow rate that lofts and advects particles. Thus, in some embodiments the flow path behind RFO 214 may be separately purged as the flow path may be charged and discharged at a high flow rate that is not limited by RFO 214. Figure 5E illustrates a flow path for P source 224b. A similar flow path may be purged for P source 224a (not shown).

[0065] In some embodiments, piezo assembly 210 may vibrate the flow path before or during purging of the precursor flow paths. As noted above, a large source of particles is the ampoule and associated components of the flow path that carry precursor species, particularly corrosive precursor species such as MoOiCh, molybdenum (V) chloride (M0CI5), and molybdenum oxytetrachloride (MoOCh). Purging as described herein may dislodge particles and advect them away from flow paths, reducing the number of particles that may deposit on wafers as defects during semiconductor fabrication operations. In some embodiments, piezo assembly 210 may be used to vibrate portions of the flow path before and / or during purging to further dislodge particles that may then be evacuated with the purge gas.

[0066] After purging the precursor flow path, a reactant flow path may be purged to divert one or more times (310). Purging the reactant flow path to divert may be performed according to Figure 4 as described above. Figure 5B illustrates reactant flow paths 252a and 252b for H2. Reactant flow path 252a may be fluidically defined between source divert valve 292 and showerhead valve 232a, which may include H2 CV 262a. Reactant flow path 252b may be fluidically defined between source valve 272 and showerhead valves 232b-d, which may include H2 CV 262b-d.

[0067] After purging each reactant flow path to divert, each reactant flow path is purged to the showerhead one or more times (312). Operations 310 and 312 may be cycled n.2 times. In some embodiments, n? may be at least two times, at least 10 times, at least about 50 times, or at least 100 times. The number of cycles may depend on the defect particles measured, where a greater number of cycles may be performed based on determining a greater number of particles are present prior to purging.

[0068] Operations 310 and 312 may then be repeated for each reactant flow path (313). For example, Figure 5C illustrates a flow path 256 for ammonia. Flow path 256 may be fluidically defined between source divert valve 296 and showerhead valve 236, which may include NH3 CV266.

[0069] In some embodiments, there are multiple flow paths for a single reactant. Figure 5F illustrates an alternate fluid delivery system 200b having two independent flow paths for H2, including additional H2 sources 222c and 222d and H2 CV 262e-h. Flow paths 252a and 252b are present in addition to flow paths 252c and 252d, which are also flow paths for flowing hydrogen. Each flow path may be independently purged according to the process described in Figures 3 and 4.

[0070] In some embodiments, discharging a flow path to a showerhead may require opening multiple showerhead valves. For example, as shown in Figure 5B, to discharge flow path 252b to showerheads 208b-d, showerhead valves 232b-d and showerhead valves 234b-d must be opened. When showerhead valves 234b-d are opened, they may be opened such that flow does not occur into flow path 254b. Back flow is generally undesirable, and thus three-way valves may be actuated to open an inlet when process gases are flowing into the inlet. One advantage of purging precursor flow paths prior to reactant flow paths is that the reactant flow path to the showerhead partially overlaps with the precursor flow path to the showerhead. Thus, purging the reactant flow path to the showerhead may also dislodge and advect particles between showerhead valves 234a-d and showerheads 208a-d. As noted above, precursors and precursor flow paths are typically a greater source of particles and defects, thus repeated purges of portions of a flow path that may have such particles is advantageous and may further reduce particles within flow paths compared to purging the precursor flow paths after the reactant flow paths.

[0071] After purging precursor and reactant flow paths, inert gas flow paths may be purged to the showerhead one or more times. As noted above, inert gas showerhead valves may be upstream of all other process gas showerhead valves to encourage dilution and mixing of process gases with inert gas. Furthermore, purging through upstream showerhead valves may encourage additional dislodging and advection of particles through the showerhead. Inert gas flow path 250a may be fluidically defined by source divert valve 290 and showerhead valve 230a, which may include Ar CV 260a. Inert gas flow path 250b may be fluidically defined by source valve 270b and showerhead valves 230b-d, which may contain Ar CV 260b-d.

[0072] Operations 302-314 may be cycled nj times. In some embodiments, ns may be at least two times, at least 10 times, at least about 50 times, or at least 100 times. The number of cycles may depend on the defect particles measured, where a greater number of cycles may be performed based on determining a greater number of particles are present prior to purging.

[0073] Figure 3 may optionally conclude with a chamber clean operation (316). A chamber cleanmay help remove any particles that flowed into the process chamber but were not evacuated from the process chamber during purging. In some embodiments, a chamber clean may be performed using NF3 or any other suitable cleaning chemistry. In some embodiments a chamber clean may be performed in the presence of a plasma.Example

[0074] Figures 10 and 11 present examples of particles before and after a purging protocol as described herein. In Figure 10, particle levels were measured by counting particles defects having a size greater than about 26 nm deposited on a test substrate before and after a purging protocol as described herein. As shown in Figure 10, each station exhibited a five-fold or greater decrease in particles. The purging protocol was 100 cycles of purging for each flow path as described in Figures 3 and 4.

[0075] Figure 11 presents another example of particle levels before and after a purging protocol as described herein. For the data shown in Figure 11 , 200 cycles of purging at a high pressure were performed, e.g. a pressure of about 1800 Torr, and then 10 cycles of purging at a lower pressure, e.g., about 1000 Torr, were performed. Similar to Figure 10, the number of particles decreases by nearly an order of magnitude following a purge protocol as described herein.Apparatus

[0076] Figure 6 schematically shows an embodiment of a process station 600 that may be used to deposit material using atomic layer deposition (ALD) and / or chemical vapor deposition (CVD), either of which may be plasma enhanced. For simplicity, the process station 600 is depicted as a standalone process station having a process chamber body 602 for maintaining a low-pressure environment. However, it will be appreciated that a plurality of process stations 600 may be included in a common process tool environment. Further, it will be appreciated that, in some embodiments, one or more hardware parameters of process station 600, including those discussed in detail below, may be adjusted programmatically by one or more computer controllers 650.

[0077] Process station 600 fluidly communicates with reactant delivery system 601 for delivering process gases to a distribution showerhead 606. In some embodiments, reactant delivery system 601 may be the same as fluid delivery system 200 disclosed above. In some embodiments, reactant delivery system 601 includes a mixing vessel 604 for blending and / or conditioning process gases for delivery to showerhead 606. One or more mixing vessel inlet valves 620 may control introduction of process gases to mixing vessel 604. Similarly, a showerhead inlet valve 605 may control introduction of process gasses to the showerhead 606. In some embodiments, an inhibitoror other gas may be directly delivered to the chamber body 602. One or more mixing vessel inlet valves 620 may control introduction of process gases to mixing vessel 604. These valves may be controlled depending on whether a process gas, inhibition gas, or carrier gas may be turned on during various operations. In some embodiments, an inhibition gas may be generated by using an inhibition liquid and vaporizing using a heated vaporizer.

[0078] As an example, the embodiment of Figure 6 includes a vaporization point 603 for vaporizing liquid reactant to be supplied to mixing vessel 604. In some embodiments, vaporization point 603 may be a heated vaporizer. The reactant vapor produced from such vaporizers may condense in downstream delivery piping. Exposure of incompatible gases to the condensed reactant may create small particles. These small particles may clog piping, impede valve operation, contaminate substrates, etc. Some approaches to addressing these issues involve sweeping and / or evacuating the delivery piping to remove residual reactant. However, sweeping the delivery piping may increase process station cycle time, degrading process station throughput. Thus, in some embodiments, delivery piping downstream of vaporization point 603 may be heat traced. In some examples, mixing vessel 604 may also be heat traced. In one non-limiting example, piping downstream of vaporization point 603 has an increasing temperature profile extending from approximately 100°C to approximately 150°C at mixing vessel 604.

[0079] In some embodiments, reactant liquid may be vaporized at a liquid injector. For example, a liquid injector may inject pulses of a liquid reactant into a carrier gas stream upstream of the mixing vessel. In one scenario, a liquid injector may vaporize reactant by flashing the liquid from a higher pressure to a lower pressure. In another scenario, a liquid injector may atomize the liquid into dispersed microdroplets that are subsequently vaporized in a heated delivery pipe. It will be appreciated that smaller droplets may vaporize faster than larger droplets, reducing a delay between liquid injection and complete vaporization. Faster vaporization may reduce a length of piping downstream from vaporization point 603. In one scenario, a liquid injector may be mounted directly to mixing vessel 604. In another scenario, a liquid injector may be mounted directly to showerhead 606.

[0080] In some embodiments, a liquid flow controller (LFC) upstream of vaporization point 603 may be provided for controlling a mass flow of liquid for vaporization and delivery to process station 600. For example, the liquid flow controller may include a thermal mass flow meter (MFM) located downstream of the LFC. A plunger valve of the LFC may then be adjusted responsive to feedback control signals provided by a proportional-integral-derivative (FID) controller in electrical communication with the MFM. However, it may take one second or more to stabilize liquid flow using feedback control. This may extend a time for dosing a liquid reactant. Thus, insome embodiments, the LFC may be dynamically switched between a feedback control mode and a direct control mode. In some embodiments, the LFC may be dynamically switched from a feedback control mode to a direct control mode by disabling a sense tube of the LFC and the PID controller.

[0081] Showerhead 606 distributes process gases toward substrate 612. In the embodiment shown in Figure 6, substrate 612 is located beneath showerhead 606, and is shown resting on a pedestal 608. It will be appreciated that showerhead 606 may have any suitable shape, and may have any suitable number and arrangement of ports for distributing processes gases to substrate 612.

[0082] In some embodiments, a microvolume 607 is located beneath showerhead 606. Performing an ALD and / or CVD process in a microvolume rather than in the entire volume of a process station may reduce reactant exposure and sweep times, may reduce times for altering process conditions (e.g., pressure, temperature, etc.), may limit an exposure of process station robotics to process gases, etc. Example microvolume sizes include, but are not limited to, volumes between 0.1 liter and 2 liters. This microvolume also impacts productivity throughput. While deposition rate per cycle drops, the cycle time also simultaneously reduces. In certain cases, the effect of the latter is dramatic enough to improve overall throughput of the module for a given target thickness of film.

[0083] In some embodiments, pedestal 608 may be raised or lowered to expose substrate 612 to micro volume 607 and / or to vary a volume of microvolume 607. For example, in a substrate transfer phase, pedestal 608 may be lowered to allow substrate 612 to be loaded onto pedestal 608. During a deposition process phase, pedestal 608 may be raised to position substrate 612 within micro volume 607. In some embodiments, micro volume 607 may completely enclose substrate 612 as well as a portion of pedestal 608 to create a region of high flow impedance during a deposition process.

[0084] Optionally, pedestal 608 may be lowered and / or raised during portions the deposition process to modulate process pressure, reactant concentration, etc., within microvolume 607. In one scenario where process chamber body 602 remains at a base pressure during the deposition process, lowering pedestal 608 may allow microvolume 607 to be evacuated. Example ratios of microvolume to process chamber volume include, but are not limited to, volume ratios between 1 :600 and 1 : 10. It will be appreciated that, in some embodiments, pedestal height may be adjusted programmatically by a suitable computer controller.

[0085] In another scenario, adjusting a height of pedestal 608 may allow a plasma density to be varied during plasma activation and / or treatment cycles included in the deposition process. At the conclusion of the deposition process phase, pedestal 608 may be lowered during another substrate transfer phase to allow removal of substrate 612 from pedestal 608.

[0086] While the example microvolume variations described herein refer to a height-adjustable pedestal, it will be appreciated that, in some embodiments, a position of showerhead 606 may be adjusted relative to pedestal 608 to vary a volume of microvolume 607. Further, it will be appreciated that a vertical position of pedestal 608 and / or showerhead 606 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 608 may include a rotational axis for rotating an orientation of substrate 612. It will be appreciated that, in some embodiments, one or more of these example adjustments may be performed programmatically by one or more suitable computer controllers.

[0087] Returning to the embodiment shown in Figure 6, showerhead 606 and pedestal 608 electrically communicate with RF power supply 614 and matching network 616 for powering a plasma. In some embodiments, the plasma energy may be controlled 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 614 and matching network 616 may be operated at any suitable power to form a plasma having a desired composition of radical species. Examples of suitable powers are included above. Likewise, RF power supply 614 may provide RF power of any suitable frequency. In some embodiments, RF power supply 614 may be configured to control high- and low-frequency RF power sources independently of one another. Example low-frequency RF frequencies may include, but are not limited to, frequencies between 50 kHz and 500 kHz. Example high-frequency RF frequencies may include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz. It will be appreciated that any suitable parameters may be modulated discretely or continuously to provide plasma energy for the surface reactions. In one non-limiting example, the plasma power may be intermittently pulsed to reduce ion bombardment with the substrate surface relative to continuously powered plasmas.

[0088] In some embodiments, the plasma may be monitored in-situ by one or more plasma monitors. In one scenario, plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, plasma density and / or process gas concentration may be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters may be programmatically adjusted based on measurements from such in-situ plasma monitors. For example, an OES sensor may be used in a feedback loop for providing programmatic control of plasma power. It will be appreciated that, in someembodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0089] In some embodiments, the plasma may be controlled via input / output control (IOC) sequencing instructions. In one example, the instructions for setting plasma conditions for a plasma process phase may be included in a corresponding plasma activation recipe phase of a deposition process recipe. In some cases, process recipe phases may be sequentially arranged, so that all instructions for a deposition process phase are executed concurrently with that process phase. In some embodiments, instructions for setting one or more plasma parameters may be included in a recipe phase preceding a plasma process phase. For example, a first recipe phase may include instructions for setting a flow rate of an inert and / or a reactant gas, instructions for setting a plasma generator to a power set point, and time delay instructions for the first recipe phase. A second, subsequent recipe phase may include instructions for enabling the plasma generator and time delay instructions for the second recipe phase. A third recipe phase may include instructions for disabling the plasma generator and time delay instructions for the third recipe phase. It will be appreciated that these recipe phases may be further subdivided and / or iterated in any suitable way within the scope of the present disclosure.

[0090] In some deposition processes, plasma strikes last on the order of a few seconds or more in duration. In certain implementations, much shorter plasma strikes may be used. These may be on the order of 10 ms to 1 second, typically, about 20 to 80 ms, with 50 ms being a specific example. Such very short RF plasma strikes require extremely quick stabilization of the plasma. To accomplish this, the plasma generator may be configured such that the impedance match is set preset to a particular voltage, while the frequency is allowed to float. Conventionally, high- frequency plasmas are generated at an RF frequency at about 13.56 MHz. In various embodiments disclosed herein, the frequency is allowed to float to a value that is different from this standard value. By permitting the frequency to float while fixing the impedance match to a predetermined voltage, the plasma can stabilize much more quickly, a result which may be important when using the very short plasma strikes associated with some types of deposition cycles.

[0091] In some embodiments, pedestal 608 may be temperature controlled via heater 610. Further, in some embodiments, pressure control for deposition process station 600 may be provided by butterfly valve 618. As shown in the embodiment of Figure 6, butterfly valve 618 throttles a vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of process station 600 may also be adjusted by varying a flow rate of one or more gases introduced to process station 600.

[0092] Figure 7 is a block diagram of a processing system suitable for conducting thin film deposition processes in accordance with certain embodiments. The system 700 includes a transfer module 703. The transfer module 703 provides a clean, pressurized environment to minimize risk of contamination of substrates being processed as they are moved between various reactor modules. Mounted on the transfer module 703 are two multi-station reactors 709 and 710, each capable of performing atomic layer deposition (ALD) and / or chemical vapor deposition (CVD) according to certain embodiments. Reactors 709 and 710 may include multiple stations 711, 713, 715, and 717 that may sequentially or non-sequentially perform operations in accordance with disclosed embodiments. The stations may include a heated pedestal or substrate support, one or more gas inlets or showerhead or dispersion plate.

[0093] Also mounted on the transfer module 703 may be one or more single or multi-station modules 707 capable of performing plasma or chemical (non-plasma) pre-cleans, or any other processes described in relation to the disclosed methods. The module 707 may in some cases be used for various treatments to, for example, prepare a substrate for a deposition process. The module 707 may also be designed / configured to perform various other processes such as etching or polishing. The system 700 also includes one or more wafer source modules 701, where wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 719 may first remove wafers from the source modules 701 to loadlocks 721. A wafer transfer device (generally a robot arm unit) in the transfer module 703 moves the wafers from loadlocks 721 to and among the modules mounted on the transfer module 703.

[0094] In various embodiments, a system controller 729 is employed to control process conditions during deposition. The controller 729 will typically include one or more memory devices and one or more processors. A processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc.

[0095] The controller 729 may control all of the activities of the deposition apparatus. The system controller 729 executes system control software, including sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other parameters of a particular process. Other computer programs stored on memory devices associated with the controller 729 may be employed in some embodiments.

[0096] Typically there will be a user interface associated with the controller 729. The user interface may include a display screen, graphical software displays of the apparatus and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0097] System control logic may be configured in any suitable way. In general, the logic can be designed or configured in hardware and / or software. The instructions for controlling the drive circuitry may be hard coded or provided as software. The instructions may be provided by “programming.” Such programming is understood to include logic of any form, including hard coded logic in digital signal processors, application-specific integrated circuits, and other devices which have specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general purpose processor. System control software may be coded in any suitable computer readable programming language.

[0098] The computer program code for controlling the inhibition species flow, RF power, hydrogen flow, oxygen flow, and silicon-containing precursor flow, and other processes in a process sequence can be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. Compiled object code or script is executed by the processor to perform the tasks identified in the program. Also as indicated, the program code may be hard coded.

[0099] The controller parameters relate to process conditions, such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters are provided to the user in the form of a recipe, and may be entered utilizing the user interface. Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 729. The signals for controlling the process are output on the analog and digital output connections of the deposition apparatus 700.

[0100] The system software may be designed or configured in many different ways. For example, various chamber component subroutines or control objects may be written to control operation of the chamber components necessary to carry out the deposition processes (and other processes, in some cases) in accordance with the disclosed embodiments. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0101] In some implementations, a controller, such as controller 650 or 729, is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system orsystems. The controller 729, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0102] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0103] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as describedabove, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0104] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0105] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0106] It may be appreciated that a plurality of process stations may be included in a multistation processing tool environment, such as shown in Figure 8, which depicts a schematic view of an embodiment of a multi-station processing tool. Processing apparatus 800 employs an integrated circuit fabrication chamber 863 that includes multiple fabrication process stations, each of which may be used to perform processing operations on a substrate held in a wafer holder, such as a pedestal, at a particular process station. In the embodiment of Figure 8, the integrated circuit fabrication chamber 863 is shown having four process stations 851, 852, 853, and 854. Other similar multi-station processing apparatuses may have more or fewer process stations depending on the implementation and, for example, a desired level of parallel wafer processing, size / space constraints, cost constraints, etc. Also shown in Figure 8 is substrate handler robot 875, which may operate under the control of system controller 890, configured to move substrates from a wafer cassette (not shown in Figure 8) from loading port 880 and into integrated circuit fabrication chamber 863, and onto one of process stations 851, 852, 853, and 854.

[0107] Figure 8 also depicts an embodiment of a system controller 890 employed to controlprocess conditions and hardware states of processing apparatus 800. System controller 890 may include one or more memory devices, one or more mass storage devices, and one or more processors, as described herein.

[0108] RF subsystem 895 may generate and convey RF power to integrated circuit fabrication chamber 863 via radio frequency input ports 867. In particular embodiments, integrated circuit fabrication chamber 863 may comprise input ports in addition to radio frequency input ports 867 (additional input ports not shown in Figure 8). Accordingly, integrated circuit fabrication chamber 863 may utilize 8 RF input ports. In particular embodiments, process stations 851-854 of integrated circuit fabrication chamber 863 may each utilize first and second input ports in which a first input port may convey a signal having a first frequency and in which a second input port may convey a signal having a second frequency. Use of dual frequencies may bring about enhanced plasma characteristics.

[0109] As described above, one or more process stations may be included in a multi-station processing tool. Figure 9 shows a schematic view of an embodiment of a multi-station processing tool 900 with an inbound load lock 902 and an outbound load lock 904, either or both of which may comprise a remote plasma source. A robot 906, at atmospheric pressure, is configured to move substrates or wafers from a cassette loaded through a pod 908 into inbound load lock 902 via an atmospheric port. A substrate is placed by the robot 906 on a pedestal 912 in the inbound load lock 902, the atmospheric port is closed, and the load lock is pumped down. Where the inbound load lock 902 comprises a remote plasma source, the substrate may be exposed to a remote plasma treatment in the load lock prior to being introduced into a processing chamber 914. Further, the substrate also may be heated in the inbound load lock 902 as well, for example, to remove moisture and adsorbed gases. Next, a chamber transport port 916 to processing chamber 914 is opened, and another robot 990 places the substrate into the reactor on a pedestal of a first station shown in the reactor for processing. While the embodiment depicted in Figure 9 includes load locks, it will be appreciated that, in some embodiments, direct entry of a substrate into a process station may be provided. In various embodiments, the soak gas is introduced to the station when the substrate is placed by the robot 906 on the pedestal 912.

[0110] The depicted processing chamber 914 comprises four process stations, numbered from 1 to 4 in the embodiment shown in Figure 9. Each station has a heated pedestal (shown at 918 for station 1), and gas line inlets. It will be appreciated that in some embodiments, each process station may have different or multiple purposes. For example, in some embodiments, a process station may be switchable between an inhibition plasma, passivation plasma, ALD and / or PEALD process mode. Additionally or alternatively, in some embodiments, processing chamber 914 may includeone or more matched pairs of ALD and plasma-enhanced ALD process stations. While the depicted processing chamber 914 includes four stations, it will be understood that a processing chamber according to the present disclosure may have any suitable number of stations. For example, in some embodiments, a processing chamber may have five or more stations, while in other embodiments a processing chamber may have three or fewer stations.

[0111] Figure 9 depicts an embodiment of a wafer handling system 990 for transferring substrates within processing chamber 914. In some embodiments, wafer handling system 990 may transfer substrates between various process stations and / or between a process station and a load lock. It will be appreciated that any suitable wafer handling system may be employed. Nonlimiting examples include wafer carousels and wafer handling robots. Figure 8 also depicts an embodiment of a system controller 950 employed to control process conditions and hardware states of process tool 900. System controller 950 may include one or more memory devices 956, one or more mass storage devices 954, and one or more processors 952. Processor 952 may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. In some embodiments, system controller 950 includes machine-readable instructions for performing operations such as those described herein.

[0112] In some embodiments, system controller 950 controls the activities of process tool 900. System controller 950 executes system control software 958 stored in mass storage device 954, loaded into memory device 956, and executed on processor 952. Alternatively, the control logic may be hard coded in the system controller 950. Applications Specific Integrated Circuits, Programmable Logic Devices (e.g., field-programmable gate arrays, or FPGAs) and the like may be used for these purposes. In the following discussion, wherever “software” or “code” is used, functionally comparable hard coded logic may be used in its place. System control software 958 may include instructions for controlling the timing, mixture of gases, amount of gas flow, chamber and / or station pressure, chamber and / or station temperature, substrate temperature, target power levels, RF power levels, substrate pedestal, chuck and / or susceptor position, and other parameters of a particular process performed by process tool 900. System control software 958 may be configured in any suitable way. For example, various process tool component subroutines or control objects may be written to control operation of the process tool components used to carry out various process tool processes. System control software 958 may be coded in any suitable computer readable programming language.Conclusion

[0113] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. Embodiments disclosed herein may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. Further, while the disclosed embodiments will be described in conjunction with specific embodiments, it will be understood that the specific embodiments are not intended to limit the disclosed embodiments. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein.

Claims

CLAIMSWhat is claimed is:

1. A system, comprising: a process chamber comprising a plurality of stations, wherein each station comprises a showerhead, wherein the process chamber comprises a plurality of flow paths, each flow path fluidically connected with at least one showerhead and each flow path fluidically connected with a vacuum pump; and a controller comprising memory and processors configured for (a) performing one or more cycles of: charging one or more flow paths to a first pressure with an inert gas; discharging the one or more flow paths towards the vacuum pump; charging the one or more flow paths to a second pressure with the inert gas; and discharging the one or more flow paths towards the at least one showerhead.

2. The system of claim 1, wherein each flow path comprises a first valve that controls a flow of gas towards the vacuum pump and a second valve that controls the flow of gas towards the at least one showerhead.

3. The system of claim 1, wherein each flow path comprises a charge volume.

4. The system of claim 1, wherein a first flow path of the plurality of flow paths is fluidically connected with a precursor species source, and wherein the controller is additionally configured for:(b) performing one or more cycles of: charging the first flow path to the first pressure with the inert gas; discharging the first flow path towards the vacuum pump; charging the first flow path to the second pressure with the inert gas; and discharging the first flow path towards the at least one showerhead, wherein (b) occurs before (a).

5. The system of claim 4, wherein a precursor species flowed from the precursor species source is a halogenated metal precursor species.

6. The system of claim 1, wherein the at least one showerhead comprises a first showerhead and two or more second showerheads, the first showerhead being different from the second showerhead, and wherein a first flow path of the plurality of flow paths is fluidically connected with a first precursor species source and the first showerhead, and a second flow path of the plurality of flow paths is fluidically connected with a second precursor species source and the two or more second showerheads, and wherein the controller is additionally configured for:(b) performing one or more cycles of: charging the first flow path to the first pressure with the inert gas; discharging the first flow path towards the vacuum pump; charging the first flow path to the second pressure with the inert gas; and discharging the first flow path towards the first showerhead; and(c) performing one or more cycles of: charging the second flow path to the first pressure with the inert gas; discharging the second flow path towards the vacuum pump; charging the second flow path to the second pressure with the inert gas; and discharging the second flow path towards the two or more showerheads, wherein (b) and (c) occur before (a).

7. The system of claim 1, wherein a third flow path of the plurality of flow paths is fluidically connected with an inert gas source, and wherein the controller is additionally configured for:(b) performing one or more cycles of: charging the third flow path to the second pressure with the inert gas; and discharging the third flow path towards the at least one showerhead, wherein (b) is performed after (a).

8. The system of claim 1, wherein a fourth flow path of the plurality of flow paths is fluidically connected with an ampoule comprising a metal precursor, and wherein the controller is additionally configured for:(b) performing one or more cycles of: charging the fourth flow path to the second pressure with the inert gas; and discharging the fourth flow path towards the vacuum pump, wherein (b) is performed before (a).

9. The system of claim 8, wherein the process chamber further comprises a piezo assembly connected to the fourth flow path, wherein before, during, or before and during (b) the piezo assembly vibrates a portion of the fourth flow path.

10. The system of claim 1, wherein the first pressure is at least about 1500 Torr.

11. The system of claim 1, wherein the first pressure is at least about 2500 Torr.

12. The system of claim 1, wherein the first pressure and the second pressure are the same pressure.

13. The system of claim 1 , wherein a first subset of flow paths of the plurality of flow paths are each fluidically connected to a precursor species source or a reactant source, and (a) is performed for each flow path of the first subset of flow paths.

14. The system of claim 13, wherein (a) is not performed for a second subset of flow paths of the plurality of flow paths, the second subset of flow paths comprising different flow paths than the first subset of flow paths.

15. The system of claim 1, wherein discharging is performed until the flow path reaches a third pressure.

16. The system of claim 15, wherein the third pressure is less than about 10 Torr.

17. The system of claim 1, wherein (a) is performed at least about 50 times for each flow path.

18. The system of claim 1, wherein the process chamber comprises a first flow path fluidically connected with a precursor gas source, a second flow path fluidically connected with a reactant source, and a third flow path fluidically connected with an inert gas source.

19. The system of claim 18, wherein the first flow path comprises a first valve that controls the flow of gases towards a first showerhead.

20. The system of claim 19, wherein the second flow path comprises a second valve that controls the flow of gases towards the first valve.

21. The system of claim 20, wherein the third flow path comprises a third valve that controls the flow of gases towards the second valve.

22. The system of claim 1, wherein during discharging of the one or more flow paths towards the at least one showerhead an inert gas is flowing towards the showerhead by a different flow path.

23. The system of claim 1, wherein the controller is additionally configured for:(b) performing one or more cycles of: charging one or more flow paths to a third pressure with the inert gas; discharging the one or more flow paths towards the vacuum pump; charging the one or more flow paths to a fourth pressure with the inert gas; and discharging the one or more flow paths towards the at least one showerhead, wherein the third pressure and the fourth pressure are both less than the first pressure and the second pressure.

24. The system of claim 23, wherein the third pressure and the fourth pressure are between about 600 Torr and about 1500 Torr.

25. A method, comprising: providing a process chamber comprising a plurality of stations, wherein each station comprises a showerhead, wherein the process chamber comprises a plurality of flow paths, each flow path fluidically connected with at least one showerhead and each flow path fluidically connected with a vacuum pump; and performing one or more cycles of: charging one or more flow paths to a first pressure with an inert gas; discharging the one or more flow paths towards the vacuum pump; charging the one or more flow paths to a second pressure with the inert gas; and discharging the one or more flow paths towards the at least one showerhead.

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