Atomic Layer Deposition Pulse Sequence Engineering for Enhanced Conformality of Low-Temperature Precursors

Abstract

The present disclosure relates to methods, systems, and apparatus for depositing films. In particular, the films are deposited using an atomic layer deposition process, where some steps of the ALD process are carried out at temperatures above the thermal decomposition temperature of the film precursors.

Description

[Background technology]

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

[0002] The fabrication of semiconductor devices can include the deposition of silicon nitride films. Silicon nitride thin films have unique physical, chemical, and mechanical properties that make them useful in a wide variety of applications. For example, silicon nitride films can be used as diffusion barriers, gate insulators, sidewall spacers, encapsulation layers, transistor strain membranes, and the like.

[0003] The background discussion provided herein is intended to provide a general overview of the contents of the present disclosure. Work by the currently named inventors within the scope of what is described in this background section, as well as aspects of the discussion that may not otherwise be considered prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure. Summary of the Invention

[0004] Disclosed herein are methods and systems for depositing a film. In one aspect of the embodiments herein, a method for depositing a film is provided, the method comprising: providing a substrate in a process chamber; and performing one or more cycles of an atomic layer deposition (ALD) process, each of the one or more cycles of the ALD process comprising: exposing the substrate to a precursor, the substrate being at a first temperature during at least a portion of (a), the first temperature being lower than a thermal decomposition temperature of the precursor; and exposing the substrate to one or more reactants, the substrate being at a second temperature higher than the thermal decomposition temperature during at least a portion of (b). In some embodiments, during (b), the process chamber is at a first pressure, and the method further comprises, prior to (a), (c) exposing the substrate to a purge gas, the process chamber being at a second pressure lower than the first pressure during (c). In some embodiments, during (c), the temperature of the substrate is reduced from the second temperature to the first temperature. In some embodiments, the first pressure is at least about 5 Torr and the second pressure is less than about 1 Torr. In some embodiments, the second pressure is less than about 0.1 Torr. In some embodiments, during (a), the process chamber is at a third pressure, the third pressure being less than the first pressure.

[0005] In some embodiments, the purge gas comprises an inert gas. In some embodiments, the purge gas comprises H2. In some embodiments, the duration of (c) is at least about 5 seconds. In some embodiments, the second temperature is at least about 600°C. In some embodiments, the pyrolysis temperature is between about 500°C and about 600°C. In some embodiments, (b) is performed in the presence of a plasma. In some embodiments, the power of the plasma is at least about 5000 W. In some embodiments, the precursor is a silicon-containing precursor. In some embodiments, the precursor is a carbon-containing precursor. In some embodiments, the one or more reactants include a nitrogen-containing reactant. In some embodiments, the one or more reactants include an oxygen-containing reactant. In some embodiments, the ALD process forms a conformal film. In some embodiments, the conformal film is a silicon nitride film. In some embodiments, the substrate includes features having an aspect ratio of at least about 30:1. In some embodiments, the process chamber includes a pedestal, and the temperature of the pedestal is about the second temperature during (a). These and other features of embodiments of the present disclosure are described in detail below with reference to the associated drawings. [Brief description of the drawings]

[0006] [Figure 1A] FIG. 1A shows examples of sidewall thicknesses according to embodiments described herein. [Figure 1B] FIG. 1B illustrates examples of sidewall thicknesses according to embodiments described herein.

[0007] [Diagram 2] FIG. 2 shows a flow chart of an exemplary embodiment of the present disclosure.

[0008] [Diagram 3] FIG. 3 shows pressure and temperature charts for an atomic layer deposition (ALD) process according to various embodiments herein.

[0009] [Figure 4A] FIG. 4A illustrates an example of determining pyrolysis temperature according to various embodiments herein. [Figure 4B] FIG. 4B illustrates an example of determining pyrolysis temperature according to various embodiments herein.

[0010] [Diagram 5] FIG. 5 is a schematic diagram of an example process chamber for carrying out methods according to embodiments of the present disclosure. [Figure 6] FIG. 6 is a schematic diagram of an example process chamber for carrying out methods according to embodiments of the present disclosure. [Figure 7] FIG. 7 is a schematic diagram of an example process chamber for carrying out methods according to embodiments of the present disclosure. [Figure 8] FIG. 8 is a schematic diagram of an example process chamber for carrying out methods according to embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Semiconductor manufacturing processes often involve the deposition of silicon nitride materials. In one example, silicon nitride may be used as a diffusion barrier, gate insulator, sidewall spacer, liner, transistor strain film, etch stop layer, and encapsulation layer in the manufacture of semiconductor devices. Conformal silicon nitride layers may also be used for other applications. For example, silicon nitride may be used during the manufacture of memory structures.

[0012] The present disclosure relates to a method for depositing a film at high temperature using an atomic layer deposition (ALD) process. Typically, an ALD cycle includes the operations of delivering and adsorbing at least one reactant to a substrate surface, and then reacting the adsorbed reactant with one or more reactants to form a layer of a film. As an example, a silicon nitride deposition cycle may include the operations of (i) delivering / adsorbing a silicon-containing precursor, (ii) purging the silicon precursor from the chamber, (iii) delivering a nitrogen-containing reactant or nitrogen-containing gas, and (iv) purging the nitrogen-containing reactant from the chamber.

[0013] Unlike chemical vapor deposition (CVD) techniques, ALD processes use surface-mediated deposition reactions to deposit films layer by layer. In one example of an ALD process, a substrate surface containing a total number of surface active sites is exposed to a gas-phase distribution of a first precursor, such as a silicon-containing precursor, in a dosage provided to a chamber configured to accommodate the substrate. Molecules of the first precursor are adsorbed on the substrate surface, including chemisorbed species and / or physisorbed molecules of the first precursor. It should be understood that when a compound is adsorbed on 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 a derivative of the silicon-containing precursor in addition to the silicon-containing precursor. This operation may be surface-mediated in that only a monolayer or partial layer of the first precursor saturates the substrate surface. After the dosage of the first precursor, the chamber is evacuated to remove most or all of the first precursor remaining in the gas phase, leaving most or only the adsorbed species. In some implementations, the chamber may not be fully evacuated. For example, the chamber may be evacuated so that the partial pressure of the first precursor in the gas phase is low enough to moderate the reaction. A reactant, such as a nitrogen-containing reactant, is introduced into the chamber and some of these molecules react with the first precursor adsorbed on the surface. In some processes, the reactant reacts immediately with the adsorbed first precursor. In some embodiments, a plasma is ignited when the reactant is introduced into the chamber. The chamber may then be evacuated again to remove unbound second reactant molecules. As mentioned above, in some embodiments, the chamber may not be fully evacuated. Additional ALD cycles may be used to increase the film thickness.

[0014] Generally, films deposited at higher temperatures (e.g., above 600° C.) result in better film quality. Films deposited at higher temperatures typically have fewer impurities, higher density, lower wet etch rates, lower leakage currents, and higher breakdown voltages than films deposited at lower temperatures. In some embodiments, films deposited at lower temperatures may be annealed at higher temperatures to improve film properties. However, in surface-mediated deposition processes such as atomic layer deposition (ALD), precursors may thermally decompose (subject to pyrolysis) at such higher temperatures. This is undesirable as it may add a chemical vapor deposition (CVD) component to the ALD process.

[0015] Thermal decomposition may occur with or without a catalyst, including in the presence of an inert gas, and the elevated temperature breaks the chemical bonds of the precursor. In the context of ALD, some precursors that would otherwise adsorb and saturate the substrate surface may decompose beyond the thermal decomposition temperature of the precursor. This thermal decomposition may prevent the saturation mechanism of ALD, since additional molecules of the precursor may adsorb to the decomposed precursor. In fact, when the thermal decomposition temperature of a silicon-containing precursor is exceeded, there may be a chemical vapor deposition component that causes the deposition of a silicon film in the initial step of the ALD cycle to deliver / adsorb the silicon-containing precursor. Thermal decomposition may break chemical bonds to groups that limit further adsorption of the precursor, thereby allowing further adsorption / decomposition of the precursor. For example, a silicon-containing precursor such as dichlorosilane (DCS) may undergo thermal decomposition to break silicon-chlorine bonds, which may allow the adsorption (and subsequent thermal decomposition) of additional DCS, resulting in the deposition of a silicon film with chlorine contaminants.

[0016] 1A illustrates a substrate feature onto which a film may be deposited. In some embodiments, the film may be deposited into a feature having a depth and a width, the aspect ratio of the depth to the width being about 30:1. The deposited film is characterized by its thickness deposited on the sidewalls, and a conformality measurement can be performed by comparing the deposited thickness at the top of the feature and the bottom of the feature.

[0017] FIG. 1B shows a film deposited using BTBAS (bis(t-butylamino)silane) as the silicon-containing precursor. Film 301 was deposited using a thermal ALD process at a temperature above the thermal decomposition temperature of BTBAS, which is about 550° C. Film 302 was deposited using a thermal ALD process at a temperature below the thermal decomposition temperature. As shown in FIG. 1B, film 302 is conformal, but film 301 has additional deposition near the top of the feature, reducing conformality from 100% to about 30%, which is undesirable. The excess deposition at the top of the feature in film 301 is due to the thermal decomposition of BTBAS, which results in a non-surface-mediated CVD component.

[0018] To address this CVD component, atomic layer deposition (ALD) processes may deliver precursors at lower temperatures than conversion processes that expose the substrate to reactants. Specifically, the temperature of the substrate may be lower than the thermal decomposition temperature of the precursor during the precursor delivery operation, and then the temperature of the substrate may be higher than the thermal decomposition temperature during a subsequent operation that reacts the precursor with the reactant. In some embodiments, the deposition layer is a silicon nitride film. However, the techniques described herein may be used with other precursors, such as carbon-containing precursors or silicon-containing precursors, that have a thermal decomposition temperature lower than the temperature of the processing operation.

[0019] In some embodiments, the ALD process may be performed in a process chamber having a pedestal on which the substrate rests during processing operations. The pedestal may include a heating element that is controllable to raise the temperature of the substrate during processing operations, for example, to 600° C. or higher. To reduce the temperature of the substrate, the temperature of the heating element may be reduced, but this type of cooling may be too slow to be acceptable in terms of throughput.

[0020] In order to cool the substrate within acceptable time constraints, in some embodiments, the process chamber pressure is reduced while flowing the purge gas. Reducing the process chamber pressure may immediately reduce the temperature of the substrate even if the pedestal is maintained at a higher temperature. Without being bound by theory, reducing the process chamber pressure may create a vacuum cooling effect on the wafer. Vacuum cooling of the wafer may be performed while flowing the purge gas. The temperature of the substrate may be adjusted prior to the precursor delivery step based on the process chamber pressure and the duration of flowing the purge gas at the reduced pressure. By cooling the wafer below the thermal decomposition temperature of the precursor, the subsequent precursor delivery step may saturate the surface of the substrate without thermal decomposition, resulting in a surface-mediated step without CVD components. The temperature of the wafer may then be increased before delivering the reactants. The purge gas may include any inert gas, such as N2, argon, helium, xenon, etc. In some embodiments, H2 may be flowed with the inert gas. Co-flowing hydrogen may increase the rate of temperature reduction.

[0021] FIG. 2 provides a flow chart of an ALD process according to various embodiments herein. FIG. 2 may be understood with reference to FIG. 3, which provides a timing diagram for pressure and temperature of various operations of an ALD cycle. The concept of an ALD "cycle" is relevant to the discussion of various embodiments herein. Typically, a cycle is a minimum set of operations used to perform one surface deposition reaction. A cycle results in the formation of at least a partial silicon nitride film layer on the substrate surface. Typically, an ALD cycle includes operations of delivering and adsorbing at least one reactant to the substrate surface, and then reacting the adsorbed reactant with one or more reactants to form a partial layer of the film. The cycle may include certain auxiliary operations, such as cleaning one of the reactants or by-products and / or processing the deposited partial film. Typically, a cycle includes one course of a unique sequence of operations. An ALD cycle may be repeated n times to increase the film thickness.

[0022] The film can be provided on any useful substrate. The substrate can be a silicon wafer, e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, including a wafer having one or more layers of material, such as a dielectric, conductive, or semiconductive material, deposited thereon. The substrate can include structures, such as high aspect ratio (HAR) structures, as described herein.

[0023] The substrate may have a "feature", such as a via or contact hole, which may be characterized by one or more of a narrow and / or reentrant opening, a constriction within the feature, and a high aspect ratio. The feature may be formed in one or more of the layers described above. An example of a feature is a hole or via in a semiconductor substrate or a layer on the substrate. In some embodiments, the feature may have an aspect ratio of at least about 2:1, at least about 4:1, at least about 6:1, at least about 10:1, or more. The feature may also have a dimension near the opening, for example, an opening diameter or line width between about 10 nm and 500 nm, for example, about 25 nm and about 300 nm. The method of the present disclosure may be performed on a substrate including a feature with an opening of less than about 150 nm. The via or trench of the feature may be referred to as an unfilled feature or feature. A feature may have a reentrant profile that narrows from the bottom, closed end, or interior of the feature towards the feature opening.

[0024] In any of the methods herein, an initial operation may include preparing a substrate in a process chamber. The process chamber may be set to a chamber pressure of between about 10 mTorr and about 30 Torr, or between about 1 and 3 Torr, or between about 0.5 and 22 Torr. The chamber pressure may be varied during operation of the ALD process, as described herein.

[0025] The substrate may be heated to a substrate temperature between about 25° C. and about 900° C., or between about 500° C. and about 700° C. As used herein, substrate temperature refers to the temperature of the substrate, and it will be understood that the temperature of the substrate may be different than the temperature set on the pedestal that holds the substrate, and that in some embodiments the substrate may be heated to a desired substrate temperature when placed in the process chamber on the pedestal prior to processing the substrate. The temperature of the pedestal may remain the same throughout operation as described herein, while the substrate temperature may be changed during operation of an ALD process as described herein.

[0026] Returning to FIG. 2, in operation 200, a substrate is provided in a process chamber. In some embodiments, the substrate may be heated to a temperature of a pedestal in the process chamber that supports the substrate. The temperature of the pedestal may be a first temperature, i.e., greater than about 550° C., greater than about 600° C., greater than about 650° C., greater than about 700° C., between about 550° C. and about 700° C., for example. In some embodiments, the first temperature is greater than a pyrolysis temperature of a precursor delivered to the substrate. In some embodiments, during operation 200, the pressure of the process chamber is at least about 1 Torr, at least about 5 Torr, or at least about 10 Torr.

[0027] In operation 210, the substrate is exposed to a purge gas at low pressure. In some embodiments, the low pressure may be any pressure lower than the pressure of the process chamber in operation 200. In some embodiments, the low pressure may be less than about 1 Torr, less than about 0.5 Torr, less than about 0.1 Torr, or less than about 10 mTorr. The duration of operation 210 may be based on the thermal decomposition temperature of the precursor. Typically, the longer the duration of the low pressure purge, the more the temperature of the substrate is reduced. In some embodiments, the duration of the low pressure purge may be at least about 1 second, at least about 5 seconds, at least about 10 seconds, at least about 20 seconds, at least about 30 seconds, or between about 1 second and about 30 seconds. In some embodiments, the duration of operation 210 is based on the time it takes for the substrate temperature to drop below the thermal decomposition temperature. At the end of operation 210, the substrate may be at a second temperature, the second temperature being lower than the first temperature. In some embodiments, the second temperature is lower than the thermal decomposition temperature of the delivered precursor. In some embodiments, during operation 210, the temperature of the substrate is reduced by at least about 50°C, at least about 70°C, at least about 100°C, at least about 150°C, or between about 50°C and about 150°C.

[0028] The purge gas may be flowed into the chamber housing the substrate at a flow rate between about 1000 sccm and about 40000 sccm (e.g., about 100 to 2000 sccm). In some embodiments, the purge gas may be selected based on its thermal conductivity or may be flowed with other gases having higher thermal conductivity. Gases with higher thermal conductivity increase the rate of cooling of the chamber by absorbing more heat energy during the purge operation. Hydrogen and helium gases are known to have higher thermal conductivity (about 0.182 and 0.151 W / mK at 300 K) compared to other inert gases such as argon or N2. In some embodiments, the purge gas may be flowed with H2. Flowing hydrogen with an inert gas may cause a more rapid drop in the substrate temperature during operation 210 compared to flowing only an inert gas, thereby increasing throughput by shortening the duration of operation 210 required to cool the substrate below the pyrolysis temperature of the precursor.

[0029] In operation 220, the substrate is exposed to a precursor. The precursor adsorbs on the surface of the substrate. The precursor may be a silicon-containing precursor, a carbon-containing precursor, or other precursor. The temperature of the substrate may be at a second temperature during at least a portion of operation 220. In some embodiments, the temperature of the substrate is about the second temperature throughout operation 220. In some embodiments, the temperature of the substrate is about the second temperature at the beginning of operation 220, and the temperature of the substrate increases during operation 220. In some embodiments, the substrate may be exposed to multiple precursors. In such embodiments, each precursor may have a different pyrolysis temperature, in which case the second temperature is based on the lowest pyrolysis temperature. In some embodiments, the second temperature may be between the pyrolysis temperatures of the multiple precursors.

[0030] In some embodiments, the precursors are flowed into a chamber containing a substrate at a flow rate between about 100 sccm and about 5000 sccm (e.g., about 100 to about 2000 sccm). The precursors can be flowed for any useful period of time (e.g., about 0.1 to 10 seconds) and at any useful pressure (e.g., about 1 to 25 Torr).

[0031] During operation 220, an inert gas may be flowed with the precursors. The inert gas may be nitrogen (N2), argon (Ar), or other gases listed herein. The inert gas may be provided to assist in pressure and / or temperature control of the process chamber, evaporation of liquid reactants, faster delivery of reactants, and / or as a purge gas to remove process gases from the process chamber and / or process chamber piping. In some embodiments, the inert gas is flowed into the chamber housing the substrate at a flow rate between about 100 sccm and about 5000 sccm (e.g., about 500 to about 2000 sccm). Flowing the inert gas with the precursors provides dilution of the precursors as well as stabilizing pressure during operation.

[0032] In some embodiments, operation 220 may be performed at a higher process chamber pressure than operation 210, such as the process chamber pressure during 200. In other embodiments, the process chamber pressure may be a third pressure between the pressurizations during operations 200 and 210. This third pressure may be based on maintaining the temperature of the substrate at a second temperature during operation 220 that is lower than the thermal decomposition temperature of the precursor. In some embodiments, the third pressure may be about 1 Torr, or between about 1 Torr and about 10 Torr.

[0033] In operation 230, the process chamber is optionally purged to remove precursor molecules that did not adsorb to the substrate surface. In some embodiments, the pressure in the process chamber is increased during operation 230 to facilitate increasing the temperature of the substrate for the subsequent conversion operation (240).

[0034] Purging the chamber includes flowing a purge gas or sweep gas, which may be a carrier gas used in other operations or may be a different gas. In some embodiments, purging may involve evacuating the chamber. Examples of purge gases include argon (Ar), nitrogen (N2), hydrogen (H2), helium (He), oxygen (O2), krypton (Kr), xenon (Xe), neon (Ne), and combinations thereof. In various embodiments, the purge gas is an inert gas. The purge gas may include one or more gases. In some embodiments, operation 230 may include one or more evacuation sub-stages to evacuate the process chamber. It will be understood that in some embodiments, operation 230 may be omitted. Operation 230 may have any suitable duration, such as between about 0 seconds and about 60 seconds, for example, about 0.01 seconds. In some embodiments, the duration of operation 230 may be reduced by increasing the flow rate of one or more purge gases. For example, the purge gas flow rate may be adjusted to modify the duration of operation 230 according to the thermodynamic properties of the various reactants and / or the geometric properties of the process chamber and / or process chamber piping. In one non-limiting example, the duration of the purge phase may be adjusted by adjusting the purge gas flow rate. This may reduce the deposition cycle time and increase substrate throughput. After purging, the precursor molecules remain adsorbed on the substrate surface.

[0035] The purge gas can be flowed into the process chamber containing the substrate at a flow rate of between about 1000 sccm and about 40000 sccm (e.g., about 100 to 2000 sccm) The purge gas can be flowed for any useful period of time (e.g., about 0.1 to 10 seconds) and at any useful pressure (e.g., about 0.5 to 25 Torr).

[0036] In operation 240, the substrate is exposed to a reactant gas, with or without a plasma, to react with the adsorbed precursors to form a film. In various embodiments, the reactant gas may include one or more reactants, including a nitrogen-containing reactant or an oxygen-containing reactant. The nitrogen-containing reactant or the oxygen-containing reactant may be flowed into a process chamber housing the substrate at a flow rate between about 1000 sccm and about 40000 sccm (e.g., about 2000 to 10000 sccm). The reactant may be flowed for any useful period of time (e.g., about 0.5 to 40 seconds) and any useful pressure (e.g., about 1 to 25 Torr). In some embodiments, the pressure of the process chamber during operation 240 is at least about 5 Torr or at least about 10 Torr. The pressure of the process chamber during operation 240 may be higher compared to operations 210 or 220 to maintain a higher temperature of the substrate during operation 240. In some embodiments, operation 240 may be a thermal conversion operation to react one or more reactants with the adsorbed precursors.

[0037] The reactant gas may be used with a push or carrier gas. The push or carrier gas may be an inert gas, such as those described herein. The push or carrier gas may be flowed into the chamber housing the substrate at a flow rate of between about 100 sccm and about 5000 sccm (e.g., about 500 to 2000 sccm). The push or carrier gas may be flowed for any useful period of time (e.g., about 0.5 to 40 seconds) and at any useful pressure (e.g., about 1 to 25 Torr).

[0038] In yet another embodiment, the reactant may further include flowing with a reducing gas. Non-limiting reducing gases may include hydrogen (H2). In one non-limiting example, operation 120 includes a nitrogen-containing reactant (e.g., NH3 or N2), a reducing gas (e.g., H2), and optionally an inert gas (e.g., N2). The reducing gas may be flowed into the chamber housing the substrate at a flow rate between about 0 sccm and about 10,000 sccm (e.g., about 0 to 5,000 sccm). The reducing gas may be flowed for any useful period of time (e.g., about 0.5 to 40 seconds) and at any useful pressure (e.g., about 1 to 25 Torr).

[0039] In some embodiments, operation 240 may include exposing the substrate to energetic species (e.g., radical species). In various embodiments, the radical species are generated from a source gas, the source gas including, for example, oxygen and / or nitrogen atoms. Still other embodiments may further include the source gas being co-flowed with a reducing gas. In some embodiments, the radical species is NH * Radical species or NR * A radical species, where R is H, aliphatic, aromatic, heteroaliphatic, or heteroaromatic. NH * The radical species can be generated in any useful manner, such as using NH3, N2 / NH3, or N2 / H2 plasma. During plasma generation, any useful process conditions can be varied, where conditions can include pressure, gas ratio mixture, and plasma power (e.g., higher power can provide higher radical flux).

[0040] Other radical species for depositing SiN films may include elemental nitrogen radicals, ammonia radicals, and amine radicals. Examples of amine radicals include, but are not limited to, methylamine, dimethylamine, and aniline radicals. In some embodiments, all or substantially all radicals may be in the ground state, e.g., at least about 90% or 95% of the radicals adjacent to the substrate are in the ground state. In some embodiments, the radical species may be generated by a remote plasma source, as described in more detail below.

[0041] In certain embodiments, radical species are formed using a plasma formed from a combination of N2 and NH3 or a combination of N2 and H2. As will be appreciated, the plasma can be formed with only a nitrogen-containing reactant or a combination of a nitrogen-containing reactant and a reducing gas (e.g., hydrogen or H2, etc.). Additionally, an inert gas can be employed with the nitrogen-containing reactant. The plasma can be delivered to a chamber housing the substrate at a flow rate between about 0 sccm and about 10,000 sccm (e.g., about 0 to 5,000 sccm). The reducing gas can be flowed for any useful period of time (e.g., about 0.5 to 40 seconds) and at any useful pressure (e.g., about 0.5 to 25 Torr).

[0042] In one embodiment, the plasma is formed in the presence of a first nitrogen-containing reactant (e.g., having a flow rate of about 20 to 500 sccm), an inert gas (e.g., having a flow rate of about 1000 to 40000 sccm), and a reducing gas (e.g., having a flow rate of about 0 to 200 sccm). In a particular embodiment, the plasma is formed in the presence of a first nitrogen-containing reactant including NH3 (e.g., having a flow rate of about 50 to 250 sccm), an inert gas including N2 (e.g., having a flow rate of about 5000 to 25000 sccm), and a reducing gas including H2 (e.g., having a flow rate of about 0 to 100 sccm).

[0043] The plasma power is between about 75 W and about 12000 W per 300 mm of wafer surface area. The plasma may be generated remotely (e.g., in a remote plasma generator) or directly in the chamber housing the substrate (i.e., in situ). In situ plasma has a power of about 0.2122 W / cm 2 to about 2.122 W / cm 2 A plasma may be ignited with a power per substrate area between 100 W and 200 W. For example, in a chamber processing four 300 mm wafers, the power may range from about 600 W to about 6000 W. Plasma for ALD processes may be generated by applying a radio frequency (RF) field to a gas using two capacitively coupled plates. The RF field ionizes the gas between the plates, igniting the plasma and creating free electrons in the plasma discharge region. These electrons may be accelerated by the RF field and collide with gas-phase reactant molecules. These collisions with the reactant molecules may form radical species that participate in the deposition process.

[0044] It will be appreciated that during operation 240, the RF field may be coupled through any suitable electrode. Non-limiting examples of electrodes include a process gas distribution showerhead and a substrate support pedestal. It will be appreciated that the plasma for the ALD process may be formed by one or more suitable methods other than capacitively coupling an RF field to a gas. In some embodiments, the plasma is a remote plasma, where a nitrogen-containing or oxygen-containing reactant or source gas is ignited in a remote plasma generator upstream of the station and then transferred to the station housing the substrate.

[0045] Operations 210-240 may be repeated a number of cycles sufficient to deposit a film, e.g., a silicon oxide or silicon nitride film, to a desired thickness. Any suitable number of deposition cycles may be included in an ALD process to deposit a desired film thickness. For example, about 20 to about 40 deposition cycles may be performed to deposit a silicon nitride film on a substrate using embodiments of the present disclosure.

[0046] FIG. 3 illustrates an exemplary timing diagram of temperature and pressure for various ALD cycles according to embodiments herein. Each of FIGS. 310-340 corresponds to a different set of ALD cycles. FIG. 310 illustrates a typical isobaric ALD process, where the dosing, purging, converting, and purging steps are performed at the same pressure. FIGS. 320-340 illustrate various low-pressure purge ALD processes corresponding to the flow chart of FIG. 2. In FIG. 310, dosing stage 310A refers to exposing a substrate to a precursor, as described herein. Converting stage 310C refers to exposing a substrate to a reactant, as described herein. Purge stages 310B and 310D refer to exposing a substrate to a purge gas without any precursor or reactant. In FIG. 310, both purge stages are performed at the same pressure. In some embodiments, the purge stage may be a low-pressure purge operation as described herein (particularly the purge operation before the dosing operation), although some of the purge operations may not be low-pressure purge operations.

[0047] The time / temperature diagram shows steps corresponding to steps 310A-D. In particular, the leftmost step labeled "PURGE (D)" corresponds to purge steps 310D-340D. Because ALD is a cyclic process, purge steps 310D-340D may be performed before dispense steps 310A-340A.

[0048] Fig. 310 illustrates an isobaric ALD process in which all operations are performed at the same process chamber pressure, e.g., 10 Torr. The substrate may correspondingly be maintained at the same temperature, e.g., 610°C, so that it may have a CVD component during the dosage phase, which is undesirable. The substrate temperature and process chamber pressure do not change during any phase of the ALD cycle.

[0049] 320-340 illustrate how the pressure of one or more stages of an ALD cycle can be reduced to reduce the temperature of the substrate during at least a portion of the dose stage. In FIG. 320, the purge stage 320D is performed at a low pressure, while the dose stage 320A, the purge stage 320B, and the conversion stage 320C are performed at higher pressures. In some embodiments, the purge stage 320D may be performed at a pressure of less than about 1 Torr, less than about 0.5 Torr, less than about 0.1 Torr, or less than about 10 mTorr. In some embodiments, the stages 320A-C may be performed at a pressure of at least about 1 Torr, at least about 5 Torr, or at least about 10 Torr. As shown in the temperature chart, during the purge stage 320D, the temperature of the substrate is reduced from about 610° C. to about 520° C. In the subsequent dose step 320A, as the process chamber pressure increases, the temperature of the substrate may increase, for example, until equilibration with the pedestal supporting the wafer occurs, bringing the wafer to approximately 610° C. The purge step 320B and conversion step 320C may be performed at this wafer temperature and process chamber pressure. This cycle may be repeated, with each pre-dose purge step at a lower pressure to reduce the temperature of the substrate for the subsequent dose steps.

[0050] FIG. 330 illustrates another example of ALD cycle stages according to embodiments herein. In FIG. 330, purge stage 330D may be the same as purge stage 320D. Also, dosing stage 330A may be performed at a lower pressure. Notably, the chamber pressure during dosing stage 330A may be higher than the chamber pressure during purge stage 330D. The chamber pressure during dosing stage 330A may be based on maintaining the temperature of the substrate rather than lowering or increasing the temperature of the substrate. As shown in the temperature diagram, the temperature of the substrate remains substantially the same during dosing stage 330A. In other embodiments, the temperature of the substrate may increase during dosing stage 330A, but at a slower rate than when the chamber pressure was not lowered, e.g., slower than during dosing stage 320A. The process chamber pressure during dosing stage 330A may be between the pressure of the process chamber during purge stage 320D and the pressure of the process chamber during stages 320B-C. In some embodiments, the pressure during stage 330A may be at least about 1 Torr, about 1 Torr, or between about 1 Torr and about 10 Torr.

[0051] Because the substrate temperature remains low during the dose phase 330A, the temperature of the substrate may be increased during a purge phase 330B prior to the conversion phase 330C. Because it is desirable to perform the conversion phase at a high substrate temperature, the purge phase 330B may be performed for a duration sufficient to allow the temperature of the wafer to be raised to a high temperature in thermal equilibrium with the pedestal, e.g., about 610°C.

[0052] FIG. 340 illustrates another example of ALD cycle steps according to embodiments herein. Steps 340A, 340B, and 340D may be performed under the same process chamber pressure as FIG. 330 (as shown, or alternatively at the same process conditions as FIG. 320). The conversion step 340C may be performed in the presence of a plasma to further increase the temperature of the substrate during conversion. The substrate temperature may be further increased, for example, to about 640° C. by igniting the plasma at a higher power, for example, at least about 2000 W, at least about 3000 W, at least about 5000 W, or at least about 6000 W. In some embodiments, the power to the electrodes feeding the plasma may then be reduced / removed during a purge step 340D, which may allow the substrate temperature to be reduced prior to a subsequent dosing step at a lower substrate temperature.

[0053] Notably, while the temperature of the substrate in each of Figures 320-340 changes, this temperature change is the result of changing the pressure of the process chamber rather than changing any of the heating elements (e.g., the pedestal) within the process chamber. Cooling the substrate by changing the pressure can be more effective and efficient than adjusting the power sent to the heating elements, resulting in an ALD process in which precursors may be adsorbed onto the surface of the substrate at a different substrate temperature than the subsequent conversion step in which the substrate is exposed to reactants at a temperature above the thermal decomposition temperature of the precursor.

[0054] The processes described herein may be used to deposit a variety of films, including silicon-containing films, carbon-containing films, metal films, or other dielectric films. In some embodiments, the films deposited according to the processes described herein may be silicon oxide films, silicon nitride films, or silicon oxynitride films. In particular, the processes described herein may be used to deposit films where the precursor adsorbed on the surface of the substrate has a pyrolysis temperature lower than the temperature of the conversion step in which the adsorbed precursor is exposed to a reactant. In one example, the method can provide a conformal SiN film, which is deposited on a high aspect ratio (HAR) structure. In one embodiment, the aspect ratio (depth to width) is about 30:1 or greater. After the ALD process, the resulting film can be a conformal film (e.g., with 100% step coverage).

[0055] In some embodiments, the methods herein increase the growth rate of the films deposited on the sidewalls. A lower temperature precursor exposure process can increase the growth rate compared to processes in which the substrate is exposed to the precursor at a higher temperature. Thus, in some embodiments, the low temperature dosing and high temperature conversion process described herein can increase the growth rate of the film and improve throughput.

[0056] To deposit a silicon-containing film, one or more silicon-containing precursors may be used. Silicon-containing precursors suitable for use in accordance with embodiments of the present disclosure include polysilanes (H3Si-(SiH2) n —SiH3), where n > 0. Examples of silanes include silane (SiH4), disilane (Si2H6), and organosilanes such as methylsilane, ethylsilane, isopropylsilane, t-butylsilane, dimethylsilane, diethylsilane, di-t-butylsilane, allylsilane, sec-butylsilane, thexylsilane, isoamylsilane, t-butyldisilane, and di-t-butyldisilane.

[0057] Halosilanes contain at least one halogen group and may or may not contain hydrogen and / or carbon groups. Examples of halosilanes include iodosilane, bromosilane, chlorosilane, and fluorosilane. Specific chlorosilanes include tetrachlorosilane, trichlorosilane, dichlorosilane, monochlorosilane, chloroallylsilane, chloromethylsilane, dichloromethylsilane, chlorodimethylsilane, chloroethylsilane, t-butylchlorosilane, di-t-butylchlorosilane, chloroisopropylsilane, chloro-sec-butylsilane, t-butyldimethylchlorosilane, thexyldimethylchlorosilane, and the like.

[0058] Aminosilanes contain at least one nitrogen atom bonded to a silicon atom, but may also contain hydrogen, oxygen, halogens, and carbon. Examples of aminosilanes include mono-, di-, tri-, and tetra-aminosilane (H3Si(NH2), H2Si(NH2)2, HSi(NH2)3, and Si(NH2)4, respectively), and substituted mono-, di-, tri-, and tetra-aminosilanes, such as t-butylaminosilane, methylaminosilane, tert-butylsilanamine, bis(tert-butylamino)silane (SiH2(NHC(CH3)3)2(BTBAS)), tert-butylsilylcarbamate, SiH(CH3)-(N(CH3)2), SiHCl(N(CH3)2), (Si(CH3)2NH), diisopropylaminosilane (DIPAS), di-sec-butylaminosilane (DSBAS), SiH2[N(CH2CH3)2]2(BDEAS), and the like. A further example of an aminosilane is trisilylamine (N(SiH3). In some embodiments, aminosilanes with two or more amine groups attached to a central Si atom may be used. These may result in less damage than aminosilanes with only a single amine group attached.

[0059] Further examples of silicon-containing precursors include trimethylsilane (3MS), ethylsilane, butasilane, pentasilane, octasilane, heptasilane, hexasilane, cyclobutasilane, cycloheptasilane, cyclohexasilane, cyclooctasilane, cyclopentasilane, 1,4-dioxa-2,3,5,6-tetrasilacyclohexane, diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane, Examples of suitable silanes include diphenyl ether (DMOS), methyldiethoxysilane (MDES), methyldimethoxysilane (MDMS), octamethoxydodecasiloxane (OMODDS), tert-butoxydisilane, tetramethylcyclotetrasiloxane (TMCTS), tetraoxymethylcyclotetrasiloxane (TOMCTS), triethoxysilane (TES), triethoxysiloxane (TRIES), and trimethoxysilane (TMS or TriMOS).

[0060] In some embodiments, the silicon-containing precursor may comprise a siloxane or an amino-group-containing siloxane. In some embodiments, the siloxane used herein is a compound represented by the formula: X(R 1 ) a Si-O-Si(R 2 ) b Y, where a and b are integers from 0 to 2, and X and Y are independently H or NR 3 R 4 wherein R1, R2, R3, and R4 are each hydrogen, unbranched alkyl, branched alkyl, saturated heterocyclic group, unsaturated heterocyclic group, or combinations thereof. In some embodiments, at least one of X or Y is NR 3 R 4When R3 and R4 are taken together with the atoms to which they are attached, they form a saturated heterocyclic compound. In some embodiments, the silicon-containing precursor is a pentamethylated amino group-containing siloxane or a dimethylated amino group-containing siloxane.Examples of amino group-containing siloxanes include 1-diethylamino-1,1,3,3,3,-pentamethyldisiloxane, 1-diisopropylamino-1,1,3,3,3,-pentamethyldisiloxane, 1-dipropylamino-1,1,3,3,3,-pentamethyldisiloxane, 1-di-n-butylamino-1,1,3,3,3,-pentamethyldisiloxane, 1-di-sec-butylamino-1,1,3,3,3,-pentamethyldisiloxane, 1-N-methylethylamino-1,1,3,3,3,-pentamethyldisiloxane, 1-N-methylpropylamino-1,1,3,3,3-pentamethyldisiloxane, 1N-methylbutylamino-1,1,3,3,3-pentamethyldisiloxane, 1-t-butylamino-1,1,3,3,3-pentamethyldisiloxane, 1-piperidino-1,1,3,3,3-pentamethyldisiloxane, 1-dimethylamino-1,1-dimethyldisiloxane, 1-diethylamino-1,1-dimethyldisiloxane, 1-diisopropylamino-1,1-dimethyldisiloxane, 1-dipropylamino 1-amino-1,1-dimethyldisiloxane, 1-di-n-butylamino-1,1-dimethyldisiloxane, 1-di-sec-butylamino-1,1-dimethyldisiloxane, 1-N-methylethylamino-1,1-dimethyldisiloxane, 1-N-methylpropylamino-1,1-dimethyldisiloxane, e1-N-methylbutylamino-1,1-dimethyldisiloxane, 1-piperidino-1,1-dimethyldisiloxane, 1-t-butylamino-1,1-dimethyldisiloxane, 1-dimethylamino-disiloxane, 1- Examples of suitable disiloxanes include diethylamino-disiloxane, 1-diisopropylamino-disiloxane, 1-dipropylamino-disiloxane, 1-di-n-butylamino-disiloxane, 1-di-sec-butylamino-disiloxane, 1-N-methylethylamino-disiloxane, 1-N-methylpropylamino-disiloxane, 1-N-methylbutylamino-disiloxane, 1-piperidino-disiloxane, 1-t-butylaminodisiloxane, and 1-dimethylamino-1,1,5,5,5,-pentamethyldisiloxane.

[0061] If the deposited film contains oxygen, an oxygen-containing reactant may be used. Examples of oxygen-containing reactants include oxygen (O2), ozone (O3), nitrous oxide (NO), nitric oxide (NO), nitrogen dioxide (NO2), dinitrogen trioxide (N2O3), dinitrogen tetroxide (N2O4), dinitrogen pentoxide (N2O5), carbon monoxide (CO), carbon dioxide (CO2), sulfur oxide (SO), sulfur dioxide (SO2), oxygen-containing hydrocarbons (C x H y O z ), water (HO), formaldehyde (CHO), carbonyl sulfide (COS), and mixtures thereof.

[0062] If the deposited film contains nitrogen, a nitrogen-containing reactant may be used. The nitrogen-containing reactant contains at least one nitrogen atom. For example, nitrogen (N2), ammonia (NH3), hydrazine (N2H4), amines (e.g., amines containing carbon), such as methylamine (CH5N), dimethylamine ((CH3)2NH), ethylamine (C2H5NH2), isopropylamine (C3H9N), t-butylamine (C4H 11 N), di-t-butylamine (CH 19 N), cyclopropylamine (C3H5NH2), sec-butylamine (C4H 11 N), cyclobutylamine (C4H7NH2), isoamylamine (C5H 13 N), 2-Methylbutan-2-amine (CH 13 N), trimethylamine (C3H9N), diisopropylamine (C6H 15 N), diethylisopropylamine (CH 17 N), di-t-butylhydrazine (CH 20N2) and aromatic-containing amines such as aniline, pyridine, and benzylamine. The amines may be primary, secondary, tertiary, or quaternary (e.g., tetraalkylammonium compounds). The nitrogen-containing reactants may contain heteroatoms other than nitrogen. For example, hydroxylamine, t-butyloxycarbonylamine, and Nt-butylhydroxylamine are nitrogen-containing reactants. Other examples include N-nitrogens such as nitrous oxide (N2O), nitric oxide (NO), nitrogen dioxide (NO2), dinitrogen trioxide (N2O3), dinitrogen tetroxide (N2O4), and / or dinitrogen pentoxide (N2O5). x O y Contains a compound.

[0063] If the protective coating contains carbon, a carbon-containing reactant may be used. Examples of carbon-containing reactants include hydrocarbons (C x H y ) Oxygen-containing hydrocarbons (C x H y O z ), carbonyl sulfide (COS), carbon disulfide (CS2), fluorocarbons (C x F y ), hydrofluorocarbons (C x H y F z ) and the like, but are not limited to these.

[0064] When the protective coating contains sulfur, a sulfur-containing reactant may be used. Examples of sulfur-containing reactants include, but are not limited to, hydrogen sulfide (H2S), carbonyl sulfide (COS), and the like.

[0065] A metal-containing reactant may be used when the protective coating includes a metal, examples of which include, but are not limited to, tungsten, tin, and molybdenum.

[0066] Exemplary tungsten-containing reactants include bis(butylcyclopentadienyl)tungsten(IV) diiodide (C 18 H 26I2W), bis(tert-butylimino)bis(tert-butylamino)tungsten ((C4H9NH)2W(C4H9N)2), bis(tert-butylimino)bis(dimethylamino)tungsten(VI) (((CH3)3CN)2W(N(CH3)2)2), bis(cyclopentadienyl)tungsten(IV) dichloride (C 10 H 10 ClW), bis(cyclopentadienyl)tungsten(IV) dianhydride (C 10 H 12 W), bis(isopropylcyclopentadienyl)tungsten(IV) dianhydride ((C5H4CH(CH3)2)2WH2), cyclopentadienyltungsten(II) tricarbonyl hydride (C8H6O3W), tetracarbonyl(1,5-cyclooctadiene)tungsten(0) (C 12 H 12 Examples of tungsten(IV) tricarbonyl ((NH3)3W(CO)3), tungsten hexacarbonyl (W(CO)6), and the like are, but are not limited to, these.

[0067] Exemplary tin-containing reactants include bis[bis(trimethylsilyl)amino]tin(II) ([[(CH3)3Si]2N]2Sn), hexaphenylditin(IV) ([(CH5)3Sn]2), tetraallyltin ((HC=CHCH2)4Sn), tetrakis(diethylamido)tin(IV) ([(CH5)2N]4Sn), tetrakis(dimethylamido)tin(IV) ([(CH3)2N]4Sn), tetramethyltin (Sn(CH3)4), tetravinyltin (Sn(CH=CH2)4), tin(II) acetylacetonate (C 10 H 14 O4Sn), trimethyl(phenylethynyl)tin (C6H5C≡CSn(CH3)3), trimethyl(phenyl)tin (C6H5Sn(CH3)3), and the like.

[0068] Exemplary molybdenum-containing reactants include (bicyclo[2.2.1]hepta-2,5-diene)tetracarbonylmolybdenum(0) (C 11H8MoO4), bis(cyclopentadienyl)molybdenum(IV) dichloride (C 10 H 10 Cl2Mo), cyclopentadienylmolybdenum(II) tricarbonyl (C 16 H 10 Mo2O6), molybdenum hexacarbonyl (Mo(CO)6), (propylcyclopentadienyl)molybdenum(I) tricarbonyl (C 22 H 22 Mo2O6), but are not limited to these.

[0069] Exemplary ruthenium-containing reactants include bis(cyclopentadienyl)ruthenium(II) (C 10 H 10 Ru), bis(ethylcyclopentadienyl)ruthenium(II) (C7H9RuC7H9), triruthenium dodecacarbonyl (Ru3(CO) 12 ) and the like, but are not limited to these.

[0070] Exemplary aluminum-containing reactants include, but are not limited to, aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate) (Al(OCC(CH3)3CHCOC(CH3)3)3), triisobutylaluminum ([(CH3)2CHCH2]3Al), trimethylaluminum ((CH3)3Al), tris(dimethylamido)aluminum(III) (Al(N(CH3)2)3), and the like.

[0071] Exemplary zirconium-containing reactants include bis(cyclopentadienyl)zirconium(IV) dianhydride (C 10 H 12 Zr), bis(methyl-η5-cyclopentadienyl)methoxymethylzirconium (Zr(CH3C5H4)2CH3OCH3), dimethylbis(pentamethylcyclopentadienyl)zirconium(IV) (C 22 H 36Zr), tetrakis(diethylamido)zirconium(IV) ([(C2H5)2N]4Zr), tetrakis(dimethylamido)zirconium(IV) ([(CH3)2N]4Zr), tetrakis(dimethylamido)zirconium(IV) ([(CH3)2N]4Zr), tetrakis(ethylmethylamido)zirconium(IV) (Zr(NCH3C2H5)4), zirconium(IV) dibutoxide (bis-2,4-pentanedionate) (C 18 H 32 O6Zr), zirconium(IV) 2-ethylhexanoate (Zr(CH 15 O2)4), zirconium tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) (Zr(OCC(CH3)3CHCOC(CH3)3)4), and the like.

[0072] 4A and 4B show an exemplary method for identifying the thermal decomposition temperature of a precursor. Other methods may be known to those skilled in the art. In FIG. 4A, the temperature of the substrate is held substantially constant, and the precursor / purge step is repeated without exposing the substrate to a reactant. Because the substrate is not exposed to a reactant, additional precursor exposure steps will not result in deposition because the surface is already saturated. Thus, as shown in FIG. 4A, at about 550° C., the deposition rate (DR) is close to zero because it is below the thermal decomposition temperature of the precursor, and further exposure of the precursor will not result in film growth. In comparison, there is a significant deposition rate at 600° C. or 650° C., indicating CVD components that are causing film growth in the absence of reactants. The thermal decomposition temperature of the precursor may be identified by performing repeated precursor / purge cycles at various temperatures.

[0073] FIG. 4B shows another method of identifying the pyrolysis temperature. FIG. 4B shows a time / deposition rate chart with lines 451, 452, and 453 each corresponding to a different temperature. Increasing the dose / exposure time of the substrate to the precursor should have the effect of reducing the impact on the deposition rate as the surface becomes saturated. Once the surface is sufficiently saturated with the precursor, adding exposure time should not increase the deposition rate. However, as can be seen from line 451, adding exposure time increases the deposition rate linearly, which indicates a CVD component. Specifically, the CVD component may be measured as the slope of the linear portion of line 451, i.e., between about 0.5 seconds and 3 seconds. By varying the temperature of the substrate, the pyrolysis temperature may be identified based on the temperature at which the slope of the line decreases, e.g., the negative second derivative.

[0074] Device 5 illustrates generally an embodiment of a process station 500 that may be used to deposit materials using atomic layer deposition (ALD) and / or chemical vapor deposition (CVD), either of which may be plasma-activated. For simplicity, the process station 500 is illustrated as a stand-alone process station having a process chamber body 502 for maintaining a low pressure environment. However, it will be understood that multiple process stations 500 may be included in a common process tool environment. Additionally, it will be understood that in some embodiments, one or more hardware parameters of the process station 500, including those detailed below, may be programmatically adjusted by one or more computer controllers.

[0075] The process station 500 is in fluid communication with a reactant delivery system 501 for delivering process gases to a distribution showerhead 506. The reactant delivery system 501 includes a mixing vessel 504 for mixing and / or conditioning process gases for delivery to the showerhead 506. One or more mixing vessel inlet valves 520 may control the introduction of process gases to the mixing vessel 504. Similarly, a showerhead inlet valve 505 may control the introduction of process gases to the showerhead 506. In some embodiments, inhibitors or other gases may be delivered directly to the chamber body 502. One or more mixing vessel inlet valves 720 may control the introduction of process gases to the mixing vessel 504. These valves may be controlled depending on whether the process gas, inhibitor gas, or carrier gas may be adjusted during various operations. In some embodiments, an inhibitor gas may be generated by using an inhibitor liquid and vaporizing it using a heated vaporizer.

[0076] As an example, the embodiment of FIG. 5 includes a vaporization point 503 for vaporizing liquid reactants provided to a mixing vessel 504. In some embodiments, the vaporization point 503 may be a heated vaporizer. Reactant vapor generated from such a vaporizer may condense in downstream delivery piping. Exposure of the condensed reactants to incompatible gases may generate small particles. These small particles may clog the piping, interfere with valve operation, contaminate the substrate, etc. Some methods for addressing such issues involve cleaning and / or evacuating the delivery piping to remove residual reactants. However, cleaning the delivery piping may increase the cycle time of the process station and reduce the throughput of the process station. Thus, in some embodiments, the delivery piping downstream of the vaporization point 503 may be heat traced. In some examples, the mixing vessel 504 may also be heat traced. In one non-limiting example, the piping downstream of the vaporization point 503 has a temperature profile that increases from about 100° C. to about 150° C. at the mixing vessel 504.

[0077] In some embodiments, the reactant liquid may be vaporized in a liquid injector. For example, the liquid injector may inject a pulse of liquid reactant into the carrier gas stream upstream of the mixing vessel. In one scenario, the liquid injector may vaporize the reactant by flushing the liquid from a higher pressure to a lower pressure. In another scenario, the liquid injector may atomize the liquid into dispersed microdroplets that are then vaporized in a heated delivery tubing. It will be appreciated that smaller droplets vaporize faster than larger droplets, reducing the delay between injection of the liquid and complete vaporization. Faster vaporization may reduce the length of tubing downstream from the vaporization point 503. In one scenario, the liquid injector may be attached directly to the mixing vessel 504. In another scenario, the liquid injector may be attached directly to the showerhead 506.

[0078] In some embodiments, a liquid flow controller (LFC) upstream of the vaporization point 503 may be provided to control the mass flow rate of liquid for vaporization and delivery to the process station 500. 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 in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, it may take more than a second to stabilize the liquid flow using feedback control. This may result in a long time to dose the liquid reactant. Therefore, in some 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 the feedback control mode to the direct control mode by disabling the sense tubes of the LFC and the PID controller.

[0079] The showerhead 506 distributes process gases towards the substrate 512. In the embodiment shown in Figure 5, the substrate 512 is shown positioned below the showerhead 506 and resting on a pedestal 508. It will be understood that the showerhead 506 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to the substrate 512.

[0080] In some embodiments, a micro-volume 507 is located under the showerhead 506. Performing ALD and / or CVD in the micro-volume rather than the entire volume of the process station allows for reduced reactant exposure and clean-up times, reduced time to change process conditions (e.g., pressure, temperature, etc.), limited exposure of the robotics of the process station to process gases, etc. Examples of micro-volume sizes include, but are not limited to, volumes between 0.1 liters and 2 liters. This micro-volume also impacts productivity throughput. While the deposition rate per cycle is reduced, cycle time is simultaneously reduced. In some cases, the latter effect is dramatic enough to increase the overall throughput of the module for a given target film thickness.

[0081] In some embodiments, the pedestal 508 may be raised or lowered to expose the substrate 512 to the micro-volume 507 and / or to change the volume of the micro-volume 507. For example, during a substrate transfer phase, the pedestal 508 may be lowered so that the substrate 512 can be placed on the pedestal 508. During a deposition process phase, the pedestal 508 may be raised to position the substrate 512 within the micro-volume 507. In some embodiments, during the deposition process, the micro-volume 507 may completely surround a portion of the pedestal 508 as well as the substrate 512, forming an area of ​​high flow impedance.

[0082] Optionally, the pedestal 508 may be lowered and / or raised during portions of the deposition process to adjust process pressure, reactant concentration, etc., within the micro-volume 507. In one scenario in which the process chamber body 502 remains at a base pressure during the deposition process, the pedestal 508 may be lowered to allow the micro-volume 507 to be evacuated. Example ratios of the micro-volume to the volume of the process chamber include, but are not limited to, volume ratios between 1:600 ​​and 1:10. It will be appreciated that in some embodiments, the height of the pedestal may be programmatically adjusted by a suitable computer controller.

[0083] In another scenario, the height of the pedestal 508 may be adjusted to allow for changes in plasma density during plasma activation and / or processing cycles involved in the deposition process. At the end of the deposition process stage, the pedestal 508 may be lowered during another substrate transfer stage to allow removal of the substrate 512 from the pedestal 508.

[0084] While the micro-volume variations described herein refer to a height adjustable pedestal, it will be understood that in some embodiments, the position of the showerhead 506 may be adjusted relative to the pedestal 508 to vary the volume of the micro-volume 507. Additionally, it will be understood that the vertical position of the pedestal 508 and / or the showerhead 506 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, the pedestal 508 may include a rotation axis for rotating the orientation of the substrate 512. It will be understood that in some embodiments, one or more of these example adjustments may be implemented programmatically by one or more suitable computer controllers.

[0085] The showerhead 506 and pedestal 508 are in electrical communication with an RF power source 514 and a matching network 516 to power the plasma. In some embodiments, the plasma energy may be controlled by controlling one or more of the process station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, the RF power source 514 and the matching network 516 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. Similarly, the RF power source 514 may provide RF power of any suitable frequency. In some embodiments, the RF power source 514 may be configured to control high frequency RF power and low frequency RF power independently of each other. Examples of low frequency RF frequencies include, but are not limited to, frequencies between 50 kHz and 500 kHz. Examples of high frequency RF frequencies include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz. It will be appreciated that any suitable parameter may be discretely or continuously adjusted to provide plasma energy for surface reactions. In one non-limiting example, the plasma power may be pulsed intermittently to reduce ion bombardment to the substrate surface compared to a continuously powered plasma.

[0086] In some embodiments, the plasma may be monitored in-situ by one or more plasma monitors. In one scenario, the plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, the 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, OES sensors may be used in a feedback loop to provide programmatic control of the plasma power. It will be appreciated that in some embodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0087] In some embodiments, the plasma may be controlled via input / output control (IOC) sequence instructions. In one example, instructions for setting plasma conditions for a plasma process stage may be included in a corresponding plasma activation recipe stage of a deposition process recipe. In some cases, the process recipe stages may be arranged in sequence such that all instructions for a deposition process stage are executed simultaneously with that process stage. In some embodiments, instructions for setting one or more plasma parameters may be included in a recipe stage preceding a plasma process stage. For example, a first recipe stage may include instructions for setting flow rates of an inert gas and / or a reactant gas, instructions for setting a power set point for a plasma generator, and a time delay instruction for the first recipe stage. A subsequent second recipe stage may include instructions for enabling the plasma generator, and a time delay instruction for the second recipe stage. A third recipe stage may include instructions for disabling the plasma generator, and a time delay instruction for the third recipe stage. It will be understood that these recipe stages may be further subdivided and / or repeated in any suitable manner within the scope of the present disclosure.

[0088] In some deposition processes, the plasma strikes last on the order of several seconds or more in duration. In certain implementations, 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 very fast stabilization of the plasma. To achieve this, the plasma generator may be configured to preset the impedance matcher to a specific voltage while allowing the frequency to vary. Conventionally, RF plasmas are generated at an RF frequency of about 13.56 MHz. In various embodiments disclosed herein, the frequency can be varied to values ​​different from this standard value. By allowing the frequency to vary while fixing the impedance matcher at a predetermined voltage, the plasma can be stabilized more quickly, which can be important when using very short plasma strikes associated with some types of deposition cycles.

[0089] In some embodiments, the pedestal 508 may be temperature controlled via a heater 510. In some embodiments, the heater 510 may be set to a single temperature during an ALD cycle as described herein, even though the substrate temperature changes during the ALD cycle as a result of pressure changes in the process chamber. Additionally, in some embodiments, pressure control of the process station 500 may be provided by a butterfly valve 518. As shown in the embodiment of FIG. 5, the butterfly valve 518 throttles the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of the process station 500 may be adjusted by varying the flow rate of one or more gases introduced to the process station 500.

[0090] FIG. 6 is a block diagram of a processing system suitable for performing a thin film deposition process according to certain embodiments. System 600 includes a transfer module 603. Transfer module 603 provides a clean, pressurized environment to minimize the risk of contamination of the substrate being processed as it moves between various reactor modules. Transfer module 603 is fitted with two multi-station reactors 609 and 610, each capable of performing atomic layer deposition (ALD) and / or chemical vapor deposition (CVD) according to certain embodiments. Reactors 609 and 610 may include multiple stations 611, 613, 615, and 617 that may perform operations sequentially or non-sequentially according to embodiments of the present disclosure. The stations may include a heated pedestal or substrate support, one or more gas inlets or showerheads or distribution plates.

[0091] The transfer module 603 may also be equipped with one or more single or multi-station modules 607 capable of performing plasma or chemical (non-plasma) pre-cleaning or any other process described in connection with the methods of the present disclosure. The modules 607 may be used for various processing, in some cases, to prepare the substrate for, for example, a deposition process. The modules 607 may also be designed / configured to perform various other processes, such as etching or polishing. The system 600 also includes one or more wafer source modules 601, where the wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 619 may first retrieve the wafers from the source modules 601 to the load lock 621. A wafer transfer device (typically a robot arm unit) in the transfer module 603 moves the wafers from the load lock 621 to between the modules mounted in the transfer module 603.

[0092] In various embodiments, a system controller 629 is employed to control process conditions during deposition. The controller 629 will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc.

[0093] The controller may control all activity of the deposition apparatus. The system controller 629 executes system control software that includes 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 in memory devices associated with the controller 629 may be employed in some embodiments.

[0094] Typically, there will be a user interface associated with the controller 629. The user interface may include a display screen, a graphical software display of equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0095] The system control logic may be configured in any suitable manner. In general, logic may be designed or configured in hardware and / or software. Instructions for controlling the drive circuitry may be hard-coded or provided as software. Instructions may be provided by "programming." Such programming is understood to include any form of logic, including logic hard-coded into digital signal processors, application specific integrated circuits, and other devices in which specific algorithms are implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general purpose processor. The system control software may be coded in any suitable computer readable programming language.

[0096] The computer program code for controlling the germanium-containing reducing agent pulses, hydrogen flow, tungsten-containing precursor pulses, and other processes in the process sequence can be written in any conventional computer readable programming language, such as assembly language, C, C++, Pascal, Fortran, etc. The compiled object code or script is executed by the processor to perform the tasks specified in the program. Also, as suggested, the program code may be hard coded.

[0097] 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 may be provided to a user in the form of a recipe and entered using a user interface. Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 629. Signals for controlling the process are output to analog and digital output connections of the deposition apparatus 600.

[0098] 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 the operation of the chamber components necessary to perform a deposition process (and possibly other processes) in accordance with embodiments of the present disclosure. Examples of programs or portions of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0099] In some implementations, the controller 629 is part of a system, which may be part of the examples described above. Such systems may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling the operation of the system before, during, and after processing of a semiconductor wafer or substrate. This electronics may be referred to as a "controller," which may control various parts or sub-parts of one or more systems. Depending on the processing requirements and / or type of system, the controller 629 may be programmed to control any of the processes disclosed herein, including delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, settings of radio frequency (RF) generators in some systems, settings of RF matching circuits, frequency settings, flow settings, fluid delivery settings, position and motion settings, transfer of wafers in and out of the tool, and transfer of wafers in and out of other transfer tools and / or load locks connected or coupled to the particular system.

[0100] Broadly speaking, a controller may be defined as electronic equipment having various integrated circuits, logic, memory, and / or software that, for example, receive instructions, issue instructions, control operations, enable cleaning operations, enable end-point measurements, and the like. 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 the program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various personalizations (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. The operational parameters may, in some embodiments, be part of a recipe defined by a process engineer to accomplish one or more processing processes during the manufacture of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0101] The controller may be part of or coupled to a computer that is integrated, coupled, or otherwise networked to the system, or a combination thereof, in some embodiments. For example, the controller may be all or part of a fab host computer system in the "cloud" or that allows remote access of wafer processing. The computer may allow remote access to the system to monitor the current progress of a manufacturing operation, review the history of past manufacturing operations, review trends or performance metrics from multiple manufacturing operations, modify parameters of a current process, set up processing steps following a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that allows for entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool to which the controller is configured to couple or control. Thus, as discussed above, the controller may be distributed, such as by including one or more separate controllers that are networked together and work toward a common purpose, such as the processes and controls described herein. An example of a controller distributed for such a purpose includes one or more integrated circuits on the chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer) combined to control the process on the chamber.

[0102] Without being limited thereto, exemplary 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 system associated with or that may be used in the fabrication and / or manufacturing of semiconductor wafers.

[0103] As described above, depending on the process step or steps being performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool parts, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, other controllers, or one or more of the tools used in material transport to transport containers of wafers in and out of tool locations and / or load ports within a semiconductor manufacturing factory.

[0104] It may be understood that multiple process stations may be included in a multi-station processing tool environment, such as that shown in FIG. 7, which depicts a schematic diagram of an embodiment of a multi-station processing tool. Processing apparatus 700 employs an integrated circuit fabrication chamber 763 that includes multiple fabrication process stations, each of which may be used to perform processing operations on a substrate held on a wafer holder, such as a pedestal, at a particular process station. In the embodiment of FIG. 7, integrated circuit fabrication chamber 763 is illustrated with four process stations 751, 752, 753, and 754. Other similar multi-station processing apparatus may have more or fewer process stations depending on the implementation and, for example, the desired level of parallel wafer processing, size / space constraints, cost constraints, etc. Also shown in FIG. 7 is a substrate handler robot 775, which may operate under the control of a system controller 790 and is configured to move substrates from a wafer cassette (not shown in FIG. 7) from a loading port 780 into integrated circuit fabrication chamber 763 and to one of process stations 751, 752, 753, and 754.

[0105] 7 also illustrates an embodiment of a system controller 790 employed to control process conditions and hardware states of the processing device 700. The system controller 790 may include one or more memory devices, one or more mass storage devices, and one or more processors, as described herein.

[0106] RF subsystem 795 may generate and transmit RF power to integrated circuit fabrication chamber 763 via radio frequency input port 767. In certain embodiments, integrated circuit fabrication chamber 763 may include input ports in addition to radio frequency input port 767 (additional input ports not shown in FIG. 7). Thus, integrated circuit fabrication chamber 763 may utilize eight RF input ports. In certain embodiments, process stations 751-754 of integrated circuit fabrication chamber 763 may each utilize a first and second input port, where the first input port may transmit a signal having a first frequency and the second input port may transmit a signal having a second frequency. By using dual frequencies, plasma characteristics may be enhanced.

[0107] As mentioned above, one or more process stations may be included in a multi-station processing tool. FIG. 8 shows a schematic diagram of an embodiment of a multi-station processing tool 800 having an inbound load lock 802 and an outbound load lock 804, one or both of which may constitute a remote plasma source. A robot 806 is configured to move a substrate or wafer from a cassette transported through a pod 808 into the inbound load lock 802 through an atmospheric port at atmospheric pressure. The substrate is placed on a pedestal 812 in the inbound load lock 802 by the robot 806, the atmospheric port is closed, and the load lock is pumped down. If the inbound load lock 802 includes a remote plasma source, the substrate may be exposed to remote plasma processing in the load lock prior to being introduced into the processing chamber 814. Additionally, the substrate may also be heated in the inbound load lock 802, for example, to remove moisture and adsorbed gases. A chamber transfer port 816 to the processing chamber 814 is then opened and another robot 890 places the substrate into the reactor on the pedestal of the first station shown in the reactor for processing. While the embodiment shown in Figure 9 includes a load lock, it will be understood that in some embodiments the substrate may be provided directly into the process station. In various embodiments, a soak gas is introduced into the station as the substrate is placed on the pedestal 812 by the robot 806.

[0108] The illustrated processing chamber 814 includes four processing stations, numbered 1 through 4 in the embodiment shown in FIG. 8. Each station has a heated pedestal (shown at 818 for station 1) and a gas line inlet. It will be understood that each processing station may have a different or multiple purposes in some embodiments. For example, in some embodiments, the processing stations may be switchable between ALD and PEALD process modes. Additionally or alternatively, in some embodiments, the processing chamber 814 may include one or more matched pairs of ALD and plasma-enhanced ALD process stations. Although the illustrated processing chamber 814 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, the processing chamber may have five or more stations, while in other embodiments, the processing chamber may have three or fewer stations.

[0109] FIG. 8 illustrates an embodiment of a wafer handling system 890 for transferring substrates within the processing chamber 814. In some embodiments, the wafer handling system 890 may transfer substrates between various process stations and / or between process stations and load locks. It will be understood that any suitable wafer handling system may be employed. Non-limiting examples include a wafer carousel and a wafer handling robot. FIG. 9 also illustrates an embodiment of a system controller 850 employed to control process conditions and hardware states of the process tool 800. The system controller 850 may include one or more memory devices 856, one or more mass storage devices 854, and one or more processors 852. The processor 852 may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. In some embodiments, the system controller 850 includes machine-readable instructions for performing the operations described herein.

[0110] In some embodiments, a system controller 850 controls the activities of the process tool 800. The system controller 850 executes system control software 858 stored on mass storage device 854, loaded into memory device 856, and executed on processor 852. Alternatively, control logic may be hard-coded into the system controller 850. For these purposes, application specific integrated circuits, programmable logic devices (e.g., field programmable gate arrays, or FPGAs), and the like may be used. In the following discussion, where "software" or "code" is used, functionally comparable hard-coded logic may be used instead. The system control software 858 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 the process tool 800. The system control software 858 may be configured in any suitable manner. For example, various process tool component subroutines or control objects may be written to control the operation of the process tool components used to perform the various process tool processes. The system control software 858 may be coded in any suitable computer readable programming language.

[0111] conclusion Although the foregoing embodiments have been described in some detail for clarity of understanding, it will be apparent that certain changes and modifications may be implemented within the scope of the appended claims. The embodiments disclosed herein may be practiced even without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the embodiments of the present disclosure. Furthermore, although the embodiments of the present disclosure are described in conjunction with specific embodiments, it will be understood that the specific embodiments are not intended to limit the embodiments of the present disclosure. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the present embodiments. Thus, the present embodiments are considered to be illustrative and not restrictive, and the present embodiments are not limited to the details set forth herein.

Claims

1. 1. A method of depositing a film, the method comprising: Providing a substrate in a process chamber; performing one or more cycles of an atomic layer deposition (ALD) process; Including, Each of the one or more cycles of the ALD process comprises: (a) exposing the substrate to a precursor, wherein during at least a portion of (a), the substrate is at a first temperature, the first temperature being less than a thermal decomposition temperature of the precursor; (b) exposing the substrate to one or more reactants, wherein during at least a portion of (b), the substrate is at a second temperature that is greater than the pyrolysis temperature; A method comprising:

2. 2. The method of claim 1 , During (b), the process chamber is at a first pressure, and the method further comprises, prior to (a), (c) exposing the substrate to a purge gas, wherein during (c), the process chamber is at a second pressure lower than the first pressure.

3. 3. The method of claim 2, A method according to claim 1, wherein during (c), the temperature of the substrate is reduced from the second temperature to the first temperature.

4. 3. The method of claim 2, The duration of (c) is at least about 5 seconds.

5. 3. The method of claim 2, The method, wherein the first pressure is at least about 5 Torr and the second pressure is less than about 1 Torr.

6. 6. The method of claim 5, The method, wherein the second pressure is less than about 0.1 Torr.

7. 3. The method of claim 2, The method of claim 1, wherein during (a), the process chamber is at a third pressure, the third pressure being less than the first pressure.

8. 3. The method of claim 2, The method, wherein the purge gas comprises an inert gas.

9. 3. The method of claim 2, The purge gas is H 2 A method comprising:

10. The method according to any one of claims 1 to 9, The method, wherein the second temperature is at least about 600°C.

11. The method according to any one of claims 1 to 9, The method, wherein the pyrolysis temperature is between about 500°C and about 600°C.

12. The method according to any one of claims 1 to 9, The method, wherein (b) is carried out in the presence of a plasma.

13. 13. The method of claim 12, The method, wherein the power of the plasma is at least about 5000 W.

14. The method according to any one of claims 1 to 9, The method, wherein the precursor is a silicon-containing precursor.

15. The method according to any one of claims 1 to 9, The method, wherein the precursor is a carbon-containing precursor.

16. The method according to any one of claims 1 to 9, The method, wherein the one or more reactants comprises a nitrogen-containing reactant.

17. The method according to any one of claims 1 to 9, The method, wherein the one or more reactants comprises an oxygen-containing reactant.

18. The method according to any one of claims 1 to 9, The method wherein the ALD process forms a conformal film.

19. 20. The method of claim 18, The method, wherein the conformal film is a silicon nitride film.

20. The method according to any one of claims 1 to 9, The method, wherein the substrate includes features having an aspect ratio of at least about 30:

1.

21. The method according to any one of claims 1 to 9, The method of claim 1, wherein the process chamber includes a pedestal, and the temperature of the pedestal is about the second temperature during (a).

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