Temperature-controlled showerhead assembly for cyclic deposition.

Abstract

A temperature-controlled showerhead assembly is configured to deliver multiple gases to a cyclic deposition chamber. The showerhead assembly includes a showerhead body having a cavity formed through a central region thereof, the cavity configured to diffuse or mix gases before the gases are introduced into the deposition chamber. The showerhead assembly further includes a network of cooling channels configured to conduct heat away from the showerhead body. The showerhead assembly further includes a network of heating elements configured to supply heat to the showerhead body, the network of heating elements being positioned closer to a top surface of the showerhead body than the cooling channels.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] All applications for which a foreign or domestic priority claim is identified in the Application Data Sheet filed with this application are hereby incorporated by reference pursuant to 37 CFR 1.57.

[0002] This application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 371,564, entitled "TEMPERATURE-CONTROLLED SHOWERHEAD ASSEMBLY FOR CYCLIC VAPOR DEPOSITION," filed August 16, 2022, the contents of which are expressly incorporated herein by reference in their entirety. [Technical Field]

[0003] Field The disclosed technology relates generally to thin film deposition systems, and more particularly to showerhead assemblies for cyclic evaporation systems. [Background technology]

[0004] As semiconductor devices continue to scale in lateral dimensions, there is a corresponding scaling of the vertical dimensions of the semiconductor device, including the scaling of the thickness of functional thin films such as electrodes and dielectrics. Semiconductor fabrication involves a variety of thin films that are deposited and patterned throughout a process flow. The thin films used in semiconductor fabrication can be formed using a variety of techniques, including wet and dry deposition methods. Wet deposition methods include, for example, aerosol / spray deposition, sol-gel processes, and spin coating. Dry deposition methods include physical vapor-based techniques such as physical vapor deposition (PVD) and evaporation. Dry deposition methods further include precursor and / or chemical reaction-based techniques, such as cyclic deposition, for example, chemical vapor deposition (CVD) and atomic layer deposition (ALD). Summary of the Invention

[0005] In one aspect, a temperature-controlled showerhead assembly configured to deliver multiple gases to a cyclic deposition chamber includes a showerhead body having a cavity formed through a central region thereof, the cavity configured to diffuse or mix the gases before the gases are introduced into the deposition chamber. The showerhead assembly further includes a network of cooling channels configured to transfer heat from the showerhead body. The showerhead assembly further includes a network of heating elements configured to supply heat to the showerhead body, the network of heating elements being positioned closer to a top surface of the showerhead body than the cooling channels.

[0006] In another aspect, a temperature-controlled showerhead assembly configured to deliver multiple gases to a cyclic deposition chamber includes a showerhead body having a substantially flat outer surface facing away from a susceptor disposed below the showerhead body and a tapered inner surface facing the susceptor such that the thickness of the showerhead body increases from a central region toward an edge portion. The showerhead assembly further includes a cavity formed through the showerhead body in the central region, the cavity configured to diffuse or mix gases before introducing them into the deposition chamber. The showerhead assembly further includes a network of cooling channels and a network of heating elements formed at different vertical heights.

[0007] In another aspect, a temperature-controlled showerhead assembly configured to deliver multiple gases to a cyclic deposition chamber includes a showerhead body having a cavity formed through a central region thereof, the cavity configured to diffuse or mix the gases before the gases are introduced into the deposition chamber. The showerhead assembly further includes a network of cooling channels formed above the showerhead body and configured to conduct heat away from the showerhead. The showerhead assembly further includes a network of heating elements configured to supply heat to the showerhead. The showerhead assembly further includes a thermal insulation film vertically interposed between the cooling channels and the network of heating elements. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B illustrate schematic diagrams of a thin film deposition system including a deposition chamber configured to provide multiple gases using a temperature-controlled showerhead assembly according to some embodiments.

[0009] [Figure 2] 1 shows a perspective view of an upper exterior portion of a thin film deposition system including multiple processing stations, each configured for a temperature-controlled showerhead assembly, according to some embodiments.

[0010] [Figure 3A] 1 illustrates a cross-sectional view of a temperature controlled showerhead assembly according to some embodiments.

[0011] [Figure 3B] 1 shows a cross-sectional view of a temperature controlled showerhead assembly according to some alternative embodiments.

[0012] [Figure 4] FIG. 3C is a cross-sectional view of a portion of the showerhead assembly shown in FIG. 3B, including an expanded view of the diffusion / mixing cavity.

[0013] [Figure 5] 3C shows a perspective view of the showerhead body of the showerhead assembly shown in FIG. 3B.

[0014] [Figure 6] 1 shows a diagram of a diffusion / mixing cavity according to some embodiments.

[0015] [Figure 7] 7 shows the results of a computational fluid dynamics analysis performed to explain the diffusion and mixing effects within the diffusion / mixing cavity shown in FIG. 6.

[0016] [Figure 8] FIG. 3C is a cross-sectional view of a portion of the showerhead assembly shown in FIG. 3B, including an enlarged view of an edge portion of the deposition chamber.

[0017] [Figure 9] 1 illustrates an exploded view of a showerhead assembly according to some embodiments.

[0018] [Figure 10] 3C shows the substrate-facing surface of the showerhead body of the showerhead assembly shown in FIG. 3B, indicating the location of the temperature sensor.

[0019] [Figure 11] 1 shows a schematic cross-sectional view of a showerhead assembly, illustrating the cooling channels, heater, and insulating layer interposed therebetween.

[0020] [Figure 12] 10 shows a graph of experimental temperature measurements from a showerhead body according to some embodiments.

[0021] [Figure 13] 1 shows an example of the order of precursor supply.

[0022] [Figure 14] 1 is a cross-sectional view of an exemplary portion of a semiconductor structure illustrating high aspect ratio features and step coverage of thin films. DETAILED DESCRIPTION OF THE INVENTION

[0023] Cyclic deposition processes, such as atomic layer deposition (ALD) processes, can provide relatively conformal thin films with high uniformity and thickness accuracy over relatively high aspect ratio (e.g., 2:1) structures on a substrate (e.g., wafer). In the context of this disclosure, uniformity refers to the consistency (e.g., consistency of thickness, resistivity, step coverage) of thin films within the same substrate. Thin films deposited using sequential deposition processes, such as chemical vapor deposition (CVD), are generally less conformal and uniform than ALD, but can offer higher productivity and lower costs. To name a few, ALD and CVD can be used to fabricate elemental metals, metal compounds (e.g., titanium nitride (TiN), tantalum nitride (TaN), etc.), semiconductors (e.g., silicon (Si), III-V, etc.), dielectrics (e.g., silicon dioxide (SiO2), aluminum nitride (AlN), hafnium oxide (HfO2), zirconium oxide (ZrO2), etc.), rare earth oxides, conductive oxides (e.g., iridium oxide (IrO2), etc.), ferroelectrics (e.g., lead titanate (PbTiO3), lanthanum nickel oxide (LaNiO3), etc.), superconductors (e.g., yttrium barium copper oxide (Yba2Cu3O 7-x A wide variety of films can be deposited, including SiO 2 films, SiO 2 films, and chalcogenides (e.g., germanium-antimony-tellurium (GeSbTe)).

[0024] Some cyclic deposition processes, such as atomic layer deposition (ALD), involve alternately exposing a substrate to multiple precursors to form a thin film. Different precursors can alternately at least partially saturate the substrate surface and react with each other to form a thin film in a layer-by-layer manner. Various types of ALD exist, including time-based ALD and spatial ALD. In time-based ALD, precursors are injected sequentially and react with active sites on the substrate surface one at a time. Sequential precursor exposures may be separated by purge steps to prevent mixing and reaction of the sequential precursors in the gas phase. Thus, the reaction is confined to the surface and self-terminates, resulting in uniform deposition. Furthermore, many ALD processes can enable the deposition of high-quality materials at temperatures significantly lower than CVD, even near room temperature. ALD growth can occur within a specific temperature range, below which precursor molecules may not be sufficiently activated or desorb too slowly, and above which precursors may decompose at the surface, or even before reaching the surface, or desorb too quickly during the purge step. Therefore, temperature control of the deposition chamber is important for high-quality thin film deposition using ALD processes.

[0025] Because of its layer-by-layer growth capability, ALD can enable precise control of thickness and composition, and therefore various properties such as conductivity, conformality, uniformity, barrier properties, and mechanical strength. Even for ALD, which is already known to produce thin films with extremely high uniformity compared to other techniques, there is an increasing need to improve within-wafer uniformity, particularly due to thickness scaling, often associated with feature size scaling in semiconductor devices. While ALD films generally have excellent uniformity, there can be several reasons for reduced uniformity in deposition. For example, uniformity can be reduced due to precursor pulse overlap, non-uniform precursor distribution resulting from insufficient mixing and / or diffusion, thermal autolysis of precursors, and non-uniform substrate temperature, to name a few.

[0026] As mentioned above, non-uniform precursor distribution can be caused by insufficient diffusion or mixing with the carrier gas. For example, in an ALD reactor (e.g., a deposition chamber formed in a processing station), precursors are introduced into the deposition or reaction chamber from individual source delivery lines, which may converge into a common supply line before being introduced into the atomic layer deposition (ALD) chamber (e.g., simply the deposition chamber). Without being bound by any theory, in some cases, carrier gas may flow through all precursor delivery lines, resulting in the carrier gas from one precursor delivery line acting as a diffusion barrier for precursors flowing from another precursor delivery line. While each precursor is believed to mix properly with the carrier gas within its individual source delivery line, the precursors may not be able to spread properly beyond the intersection of the common chamber supply line, which is typically located a short distance upstream from the substrate.

[0027] To mitigate these concerns, some processing stations use a means for distributing precursor / reactant and purge gases within the chamber space. One such means includes a showerhead, which is used to effectively distribute and mix gases, including precursors. Variations in the design of this hardware can range from flat to tapered designs. Gas distribution can be provided in one of several ways, including (1) across the entire surface of the showerhead through multiple holes fed by one or more plenums, (2) from the center of the showerhead, or (3) from one end to the other (also known as crossflow).

[0028] To reduce the aforementioned non-uniformity problems caused by insufficient gas mixing or diffusion, some deposition chambers, such as those with flat showerheads and distributed holes, have a larger showerhead-to-substrate spacing to increase mixing and diffusion and reduce the impact of gas impingement on the substrate. However, increasing the showerhead-to-substrate spacing comes at the expense of longer ALD cycle times due to increased space for gas filling and purging. In time-based ALD, the longer time required to fill and purge the chamber increases the leading and trailing edges of the precursor pulses, which can exacerbate non-uniformity resulting from precursor pulse overlap. In spatial deposition chambers with flat showerheads, the spacing can be smaller, but leading and trailing edge effects can still typically exist. Furthermore, in addition to spatial optimization of the chamber, including the spacing between the showerhead and the substrate, spatial and temporal temperature variations at the showerhead can adversely affect various deposition characteristics, such as increasing thickness non-uniformity. The inventors of the present invention have discovered that, due to the stringent requirements of today's semiconductor manufacturing specifications, such temperature variations at the showerhead can cause temperature variations at substrate height, which in turn leads to within-wafer thin film non-uniformity of various parameters, such as thickness, resistivity, and step coverage, to name a few.

[0029] Thus, there is a need for precursor delivery systems designed to improve the productivity (e.g., shorter ALD cycle times) and uniformity of thin films deposited in ALD systems. To address these and other sources of non-uniformity, various embodiments disclosed herein relate to temperature-controlled showerhead assemblies.

[0030] Various hardware design considerations for a cyclic deposition system, such as an ALD deposition system, are interdependent. Design optimization of one parameter can result in the deterioration of another. For example, it may be desirable to reduce the space between the showerhead and the substrate that must be filled during exposure to a precursor so that a shorter time is required for the precursor to saturate the substrate surface. However, the present inventors have discovered that reducing the showerhead-to-substrate distance can significantly increase heat transfer between the substrate and the showerhead, potentially adversely affecting various properties of the resulting thin film. In particular, the present inventors have discovered that the design of a showerhead for an ALD processing station can significantly affect the uniformity of the thickness, composition, and physical properties of thin films deposited in the deposition chamber. Specifically, the present inventors have discovered that controlling the spatial temperature profile of the showerhead and maintaining a relatively constant temperature therein can be important for reducing non-uniformity in thin films deposited by ALD processes. Furthermore, the present inventors have discovered that proper precursor diffusion and / or mixing with a purge gas prior to contact with the substrate can be important for the uniformity of the deposited thin film.

[0031] To address the aforementioned needs, among others, a cyclic deposition system according to some embodiments includes a deposition chamber configured to deposit a thin film by alternatingly exposing a substrate (e.g., a wafer, a semiconductor device) to multiple gases, including precursors, where the thin film deposition chamber is configured to introduce one or more of the gases into the thin film deposition chamber using a temperature-controlled showerhead assembly. The showerhead assembly according to various embodiments includes a showerhead body having a gas diffusion / mixing cavity formed therethrough in a central region (e.g., an upper central region) of the showerhead body, the gas diffusion / mixing cavity configured to receive gases from an external source and diffuse and / or mix the precursors before being introduced into the ALD deposition chamber. The showerhead assembly further includes a heater (e.g., a network of heating elements) configured to supply heat to the showerhead. The showerhead assembly further includes a network of cooling channels configured to flow a coolant through the showerhead to carry heat away from the showerhead. The heating elements and cooling channels are controlled to maintain the showerhead within a temperature range set for the thin film being deposited.

[0032] In various embodiments, the heating element is embedded in the showerhead body, for example, located on the top surface of the showerhead body.

[0033] In various embodiments, the cooling channels may be formed in a component located adjacent to the showerhead body, for example, in a component immediately above the showerhead.

[0034] In various embodiments, the showerhead body has a substantially flat outer surface portion located away from a susceptor that supports a substrate for thin film deposition. The showerhead body further has a tapered inner surface portion facing the susceptor. The inner surface portion is connected to the outer surface portion, and the taper moves the inner surface portion further away from the susceptor as it approaches the center of the susceptor.

[0035] In various embodiments, the gas diffusion / mixing cavity is a conical gas diffusion and / or mixing cavity.

[0036] In various embodiments, the heater (e.g., a network of heating elements) and the network of cooling channels are formed at different vertical heights and configured such that during deposition the inner surface of the showerhead body is maintained at a temperature at least 20° C. higher than the temperature of the coolant flowing through the cooling channels.

[0037] In various embodiments, the showerhead assembly further comprises a thermal insulating film interposed between the cooling channels and the network of heating elements and configured to limit heat transfer therebetween.

[0038] The temperature-controlled showerhead assembly allows, among other things, improved temperature control of the showerhead, and thus the substrate temperature, as well as spatial uniformity of the precursors delivered to the substrate surface, thereby improving the properties of the resulting thin film, such as improved thickness and composition uniformity. When the thin film being deposited is a conductor, such as TiN, the system also allows for improved resistivity uniformity. Furthermore, the system also improves thin film step coverage in high aspect ratio structures on the substrate.

[0039] In the following discussion, some embodiments may be described using specific precursors for specific films as examples. For example, thin film deposition and methods of depositing such thin films according to various embodiments may be described using specific exemplary precursors including titanium tetrachloride (TiCl), ammonia (NH), and dichlorosilane (SiClH) for depositing TiN and / or titanium silicon nitride (TiSiN). However, the embodiments are not so limited, and it will be understood that aspects of the invention are applicable to any suitable combination of precursors for depositing any suitable thin film that can be formed using a cyclic deposition process, such as an ALD process.

[0040] Cyclic Thin Film Deposition System 1 schematically illustrates a thin film deposition system 100 including a deposition chamber 103 configured to provide precursors using a temperature-controlled showerhead assembly 112 according to some embodiments. The thin film deposition system 100 includes a thin film processing station 102 having a deposition chamber 103 formed therein. A precursor delivery system 106 is configured to deliver multiple precursors into the deposition chamber 103. The illustrated deposition chamber 103 is configured to form a thin film under process conditions on a substrate 117 disposed on a support (e.g., a susceptor) 116 connected to support posts 115. The deposition chamber 103 further includes an injector block 108 connected to an upper central portion of the deposition chamber 103, the injector block 108 configured to centrally eject multiple precursors into the deposition chamber 103 via a temperature-controlled showerhead assembly 112 that forms a boundary of the deposition chamber 103. The injector block 108 can direct gases, such as precursor and purge gases, into the gas diffusion cavity prior to introduction into the deposition chamber 103 for contact with the substrate 117. The temperature-controlled showerhead assembly 112 is configured to uniformly distribute the precursors onto the substrate 117 held on the susceptor 116 so that uniform film deposition occurs. The deposition chamber 103 can be equipped with a pressure monitoring sensor (P) and / or a temperature monitoring sensor (T).

[0041] The precursor delivery system 106 is configured to deliver multiple precursors from precursor sources (120, 124) and one or more purge gases, such as an inert gas, from purge gas sources (128-1, 128-2, 134-1, 134-2) to the deposition chamber 103. Each of the precursors and purge gases is connected to the deposition chamber 103 by a respective gas delivery line. The gas delivery lines further include mass flow controllers (MFCs) 132 and precursor valves in their respective paths for introducing the respective precursors and purge gases into the thin film deposition chamber 103. More conveniently, at least some of the valves may be ultra-rapid atomic layer deposition (ALD) valves.

[0042] 1, the plurality of precursors includes a first precursor and a second precursor. The first precursor is stored in at least one first precursor source 120, and the second precursor is stored in at least one second precursor source 124. The precursor delivery system 106 is configured to deliver the first and second precursors from the first and second precursor sources 120, 124 to the deposition chamber 103 via first and second precursor delivery lines 110, 114, respectively. A rapid purge (RP) gas can be stored in at least two shared RP gas sources 128-1, 128-2. The precursor delivery system 106 is configured to deliver the rapid purge (RP) gas from the RP gas sources 128-1, 128-2 to the deposition chamber 103 via RP gas delivery lines 118-1, 118-2, respectively. Continuous purge (CP) gas can be stored in at least two CP gas sources 134-1, 134-2. The precursor delivery system 106 is configured to deliver CP gas from the CP gas sources 134-1, 134-2 to the deposition chamber 103 via CP gas delivery lines 113-1, 113-2, respectively.

[0043] The first and second precursors are configured to be delivered from first and second precursor sources 120, 124, respectively, by independently operating first and second precursor ALD valves 140, 144 connected in parallel before the processing station 102. Additionally, the RP gas is configured to be delivered from RP purge gas sources 128-1, 128-2 by independently operating two respective purge gas ALD valves 148-1, 148-2 connected in parallel before the processing station 102. The ALD valves 140, 144, 148-1, and 148-2 and respective delivery lines connected to the processing station 102 can be configured to supply the respective gases to the injector block 108 via a multi-valve block assembly, which can be attached to a lid portion of the processing station 102. In the illustrated configuration, ALD valves 140, 144, 148-1, and 148-2 are the final valves before their respective gases enter deposition chamber 103 of processing station 102.

[0044] By way of example only, the first and second precursors can include TiCl4 and NH3, respectively, delivered from respective TiCl4 and NH3 sources through respective precursor delivery lines to the deposition chamber 103 to form a thin film (e.g., a TiN thin film). Additionally, the precursor delivery system 106 can be configured to deliver argon (Ar) as a purge gas from an Ar source through a purge gas delivery line to the processing chamber 103. The purge gas can be delivered as a continuous purge (CP) gas and / or as a rapid purge (RP) gas, which can be delivered through a dedicated purge gas ALD valve as shown in FIG. 1. The CP gas can be introduced with one of the precursors and mixed in a vertical cavity formed through a showerhead block of the showerhead assembly 112 before being introduced into the main deposition chamber 103. The illustrated precursor delivery system 106 can be configured to deliver Ar as an RP gas from purge gas sources 128-1, 128-2 to the processing chamber 103 via respective purge gas delivery lines and purge gas ALD valves 148-1, 148-2. CP gases can be delivered to the deposition chamber 103 without the purge gas ALD valves. Such CP gases can function as carrier gases and be introduced into the injector block 108 simultaneously with the precursors.

[0045] According to various embodiments, the thin film deposition system 100 may be configured for non-plasma-assisted thermal ALD deposition. While plasma-assisted processes, such as plasma-enhanced atomic layer deposition (PE-ALD) processes, can be effective in forming conformal films on surfaces with features having relatively low aspect ratios, such processes may be ineffective for depositing films within vias and cavities in substrates with features having relatively high aspect ratios. Without being limited by theory, one possible reason for this is that, in some circumstances, the plasma may not be able to reach the deeper portions of high-aspect-ratio vias. In these circumstances, different portions of the via may be exposed to different amounts of plasma, leading to undesirable structural effects resulting from non-uniform deposition, such as thicker films deposited near the opening of the via compared to thinner films deposited deeper (e.g., sometimes referred to as cusping or keyhole formation). For these reasons, thermally cyclic deposition, such as thermal ALD deposition, may be more advantageous because such thermal processes are less dependent on the plasma's ability to reach different portions of the surface being deposited.

[0046] FIG. 2 shows a perspective view of a thin film deposition system 200 including multiple processing stations (e.g., four processing stations). Each of the multiple processing stations is configured to form a thin film on a substrate disposed in the deposition chamber from multiple precursors delivered to the deposition chamber under specific process conditions, such as process temperature and process pressure. In some embodiments, the multiple processing stations share the same processing conditions when the same thin film is formed at each station. In the illustrated embodiment, there are four processing stations 202-1, 202-2, 202-3, and 202-4 with corresponding showerhead assemblies. Processing stations 202-1, 202-2, 202-3, and 202-4 may be, for example, single-substrate processing stations each configured to deposit one or more precursors through respective precursor delivery lines. While the illustrated deposition system 200 is a multi-station processing system, it will be understood that the embodiments disclosed herein are not limited thereto and may be implemented in any suitable single-wafer or multi-wafer processing chamber.

[0047] As described with respect to FIG. 1 , deposition system 200 may include multiple gas (e.g., precursor, purge gas) delivery lines configured to deliver precursor and purge gases to multiple processing stations. In FIG. 2 , each delivery line may originate from a supply and connect to an MFC and manifold 236, where the precursor or purge gas delivery line may branch to deliver the corresponding gas to different processing stations 202-1, 202-2, 202-3, and 202-4. Before reaching the respective processing station, each branched delivery line may be connected to an ALD valve, and the delivery line may be precisely turned on and off to deliver the corresponding precursor or purge gas to the connected processing station. Note that ALD valves may not be required for the CP gas line, as it may deliver sequentially to the connected processing stations. This CP gas acts as a carrier gas when delivered along with the precursor. According to FIG. 1, each of the processing stations 202-1, 202-2, 202-3, 202-4 shown in FIG. 2 includes a showerhead assembly 112 having an injection block 108 that cyclically delivers multiple precursor and purge gases into the deposition chamber 103 and onto a substrate 117 disposed on a susceptor 116.

[0048] The exemplary embodiment deposition system 200 shown in FIG. 2 can significantly benefit from various combinations of the embodiments disclosed herein, including high conductance line sections and ALD valves, which can significantly shorten exposure to each precursor without sacrificing desirable film properties such as conformality, step coverage, and station-to-station consistency.

[0049] shower head assembly FIG. 3A shows a cross-sectional view of a temperature-controlled showerhead assembly 300A according to some embodiments. The showerhead assembly 300A includes a central-delivery showerhead body 308, which may be formed of a highly thermally conductive material, such as a metallic material such as aluminum. The showerhead body 308 has a gas diffusion / mixing cavity 312 formed in / through an upper central region to receive delivered precursor and purge gases into the diffusion / mixing cavity 312. Gas diffusion and / or mixing effects are described elsewhere herein. A deposition chamber 340 is located below the showerhead body 308, into which precursor and purge gases are introduced for thin film deposition on a substrate. An optional perforated plate 314 may be disposed between the upper diffusion / mixing cavity 312 and the lower deposition chamber 340 to restrict and more uniformly distribute gas flow from the diffusion / mixing cavity 312 to the deposition chamber 340 while fluidly connecting the upper diffusion / mixing cavity 312 and the lower deposition chamber 340. The showerhead assembly 300 may further include a network of cooling channels 316 formed above the showerhead body 308. The cooling channels 316 may be arranged in any suitable pattern, such as multiple concentric radial rings or a serpentine pattern, over the top surface of the showerhead body 308. The network of cooling channels 316 may be connected to a heat exchanger (not shown) and configured to allow a coolant to flow therethrough to carry heat away from the showerhead body 308. The showerhead assembly 300A may further include a temperature sensor 331 for measuring the temperature of the showerhead body 308.

[0050] FIG. 3B shows a cross-sectional view of another embodiment of a temperature-controlled showerhead assembly 300B. The showerhead assembly 300B incorporates various design improvements over the showerhead assembly 300A described above with respect to FIG. 3A, among other design parameters. The showerhead assembly 300B includes various features similar to those of the showerhead assembly 300A, detailed descriptions of which may not be repeated herein for the sake of brevity. For example, a showerhead body 308 made of a thermally conductive material (e.g., metal) forms an upper gas diffusion / mixing cavity 312 and a lower deposition chamber 340, with a perforated plate 314 positioned therebetween. The perforated plate 314 can be positioned to fluidly connect the diffusion / mixing cavity 312 to the deposition chamber 340 while restricting and more uniformly distributing gas from the diffusion / mixing cavity 312 to the deposition chamber 340. The showerhead body 308 is configured to receive and distribute precursor and purge gases through a gas diffusion / mixing cavity 312 into a thin film deposition chamber 340 .

[0051] Further, the showerhead assembly 300B has multiple cooling channels formed above the showerhead body 308. Additionally, the showerhead assembly 300B shown in FIG. 3B has a heater 330 disposed between the showerhead body 308 and the cooling channels 316. The heater 330 may be mounted in contact with the showerhead body 308. The heater 330 may be a single component or multiple heating elements (e.g., a network of heating elements) arranged in a pattern (e.g., a ring or serpentine pattern). An insulating layer 318 may be disposed between the cooling channels 316 and the heater 330 to limit heat transfer from the heater 330 to the cooling channels 316. The cooling channels 316, the insulating layer 318, and the heater 330 may be configured to control the temperature of the showerhead body 308, as further described elsewhere herein.

[0052] As shown in FIGS. 3A and 3B , a housing 304 encases the showerhead body 308 and fills the space between the showerhead body 308 and a lid portion 348, which forms the top cover of the showerhead assembly 300. As seen in FIG. 3B , a network of cooling channels may be formed in the portion of the housing 304 above the showerhead body 308. The housing 304 forms the peripheral wall of the deposition chamber 340. As shown in FIG. 3B , a susceptor 354 for holding a substrate is disposed below the deposition chamber 340 and connected to lower support posts 352. The upper surface of the susceptor 354 is configured to hold a substrate (e.g., a wafer) 356 for thin film deposition. The peripheral wall of the housing 304 is connected to a structure surrounding the susceptor 354 and support posts 352. The connection between the peripheral wall 304 and the structure surrounding the susceptor 354 can form an airtight seal so that the deposition chamber 340 is fluidly isolated from the external environment.

[0053] The inventors of the present invention have discovered that several factors related to the structure of the showerhead body 308 are important for determining the precursor flow pattern within the deposition chamber 340 and the quality (e.g., uniformity) of the thin film deposition. FIG. 4 is a partial cross-sectional view taken from the cross-sectional view of FIG. 3B to show the diffusion / mixing cavity 312 located at the top center of the showerhead body 308. As shown in FIG. 4, the diffusion / mixing cavity 312 may be cone-shaped with steeply tapered sidewalls 311, and the widest base diameter of the cone may be less than its height. The bottom diameter of the diffusion / mixing cavity 312 may be 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, or a value within a range defined by any of these values. The angle between the tapered sidewall 311 of the diffusion / mixing cavity 312 and a vertical line 313 perpendicular to the top surface of the susceptor 354 is the first cone angle α. According to some embodiments, the cone angle α may be less than 12°, 10°, 8°, 6°, or a value within a range defined by any of these values, such as less than 4.5°. The present inventors have found that a steeply tapered sidewall 311 can be important for advanced semiconductor applications, as further described elsewhere herein.

[0054] 4, the showerhead body 308 further includes an injector block 320 disposed above the diffusion / mixing cavity 312. The diffusion / mixing cavity 312 is connected to inlet channels 324a and 324b and configured to receive inlet precursor and purge gases.

[0055] The present inventors have found that the arrangement of the gas inlet channels defined within the injector block can be an important aspect for uniform distribution of precursor and purge gas. In particular, the present inventors have found that when the inlet gas channels are arranged to extend vertically, the resulting distribution of gas incident on a substrate (e.g., substrate 356 shown in FIG. 3B ) can be undesirably concentrated around a line-of-sight location, such as the center of the substrate. Without being bound by any theory, this phenomenon may be due to the fact that the velocity profile of the jet flow from a vertically arranged inlet channel is typically parabolic, with higher velocities in the central region and lower velocities at the sides of the jet. In this way, the flow is primarily downward, impinging on the central portion of the substrate, and lateral flow and diffusion can be limited. If the precursor is locally concentrated in the inlet channel without a carrier gas, limited diffusion and mixing can result in a non-uniform distribution of the precursor-containing fluid when it reaches the substrate. To address this concern, in the exemplary design shown, inlet gas channels 324a and 324b of injector block 320 extend at an oblique angle substantially off-vertical, as seen in FIG.

[0056] 5 is a perspective view of one embodiment of the showerhead body 308, with the outer wall of the diffusion / mixing cavity 312 rising from the top surface of the showerhead body. Two inlet tubes 324 and 326, with inlet channels 324a and 324b, respectively, formed therein, may be connected to the top of the diffusion / mixing cavity 312. As can be seen, the inlet tubes 324 and 326 are inclined with respect to a vertical axis perpendicular to the top surface of the showerhead body 308.

[0057] In FIG. 6 , a diffusion / mixing cavity 312 and connected inlet channels 324 a and 326 b are constructed for computational fluid dynamics (CFD) simulation purposes. The diffusion / mixing cavity 312 is bounded at its lower end by a perforated plate 314. CFD simulation results for the configuration shown in FIG. 6 are shown in FIG. 7 , illustrating the streamlines of a fluid (e.g., precursor or purge gas) entering the upper end through inlet channels 324 a and 326 b. As clearly seen in the simulated streamline trajectories, the skewed or inclined inlet channels 324 a and 326 b cause the gaseous fluid to enter the mixing cavity 312 obliquely from the top and collide with the sidewall at least once. This collision can result in the formation of vortices and turbulence in the fluid, thus promoting mixing and diffusion and resulting in more uniform precursor delivery in the gaseous fluid as it enters the deposition chamber below.

[0058] 3A, 3B, and 6, downstream of the diffusion / mixing cavity 312 is a perforated plate 314 formed with a plurality of perforations. The perforations may be the same size or different sizes. The perforations restrict flow and allow precursor and purge gases to pass more uniformly through each perforation, thereby more evenly distributing the gases in the deposition chamber 340 downstream of the perforated plate 314.

[0059] FIG. 8 is a cross-sectional view of a portion taken from FIG. 3B , showing further detail of an edge portion of the deposition chamber 340. As can be seen, the deposition chamber 340 is bounded at the top by the tapered lower surface of the showerhead body 308 and at the bottom by the upper surface of the susceptor 354. The lower surface of the showerhead body 308 has a shallow taper, forming a second cone angle β between the tapered lower surface and a plane parallel to the upper surface of the susceptor 354 (or substrate 356). The present inventors have discovered that a showerhead body 308 with a tapered lower surface allows for a significant reduction in the volume of the deposition chamber 340, relative to a showerhead body 308 with a flat surface facing the substrate 356. In addition, the present inventors have discovered that the tapered volume of the deposition chamber 340 allows for a more uniform flow of gas to be incident on the substrate surface. According to various embodiments, the second cone angle β can be less than 12°, 10°, 8°, 6°, 4°, or a value within a range defined by any of these values, such as less than 9.0°. One skilled in the art will appreciate that the smaller the second cone angle β, the smaller the volume of the deposition chamber 340. The reduced volume results in faster cycle times, in part due to less time required to purge unreacted precursor gas between precursor pulses.

[0060] Another factor to consider is the wafer-to-showerhead body gap S, shown in FIG. 8 , which is the gap between the bottom of the showerhead body 308 and the top surface of a substrate (e.g., wafer) 356 disposed on the susceptor 354. According to some embodiments, the gap S is less than 0.3 inches, 0.25 inches, 0.2 inches, 0.15 inches, 0.10 inches, or a value within a range defined by any of these values, e.g., less than 0.15 inches. The inventors of the present invention have found that, relative to a gap S of 0.25 inches, a gap S of 0.15 inches or 0.10 inches can reduce the volume of the space in the deposition chamber 340 between the showerhead and the substrate by 36% and 45%, respectively. A smaller gap S can also help improve the uniformity of thin film deposition on the substrate 356. Precursors may be configured to be ejected from the gap S surrounding the substrate 356. A smaller gap S can create more fluid resistance, ensuring that the precursor flows more uniformly in all radial directions toward the periphery. It is important that the gap S has a significantly narrower tolerance, especially when the gap S is small.

[0061] Showerhead Assembly Temperature Control As described above, to improve the temperature control and response of the showerhead assembly, some embodiments of the showerhead assembly include a network of cooling channels and a network of heating elements. The inventors of the present invention discovered that temperature control and response are particularly effective when the cooling channels and the heating elements are formed at different vertical heights. In particular, the inventors of the present invention discovered that it is advantageous to position the network of heating elements closer to the top surface of the showerhead body than the cooling channels. Furthermore, in some embodiments, the showerhead assembly further includes a thermal insulating film interposed vertically between the cooling channels and the network of heating elements. This arrangement, among other things, allows for improved control of vertical temperature differences in the showerhead body and faster time response thereof.

[0062] CFD simulations were performed to optimize the design parameters and features of the deposition chamber 340, such as the design factors described above with respect to FIGS. 3A-8. The design parameters / features include the first cone angle α, the second cone angle β, and the gap S. CFD simulations were performed to optimize the precursor concentration uniformity and flow velocity distribution on the substrate, particularly for the first cone angle α, under certain assumptions, and revealed that a first cone angle of less than 10° was substantially better than a first cone angle of 11°. For the second cone angle β, the simulation results indicated that the precursor concentration was most uniform when the second cone angle was approximately 5.5°, while the velocity distribution was best when the second cone angle was approximately 6.5°. For the wafer-to-showerhead body gap S, the simulation results indicated that a gap S of approximately 0.158 inches showed substantial improvements in concentration and velocity distribution compared to a gap S of 0.258 inches. CFD simulations were also performed to compare different implementations of the injector block. The table below shows a comparison of exemplary CFD simulation results for reducing the volume of the deposition chamber. [Table 1]

[0063] Shower head temperature control In addition to the structural factors discussed above with respect to FIGS. 3A-8 related to the uniformity of gas delivery onto the substrate and the volume of the deposition chamber 308, the present inventors have discovered that controlling the temperature of the showerhead body 308 can be important for controlling the uniformity of the deposited thin film, both in thickness and in physical properties, including chemical composition and resistivity.

[0064] Referring again to FIG. 3B , a heater can be embedded in the susceptor 354 to heat the substrate 356 within the deposition chamber 340. Heat from the substrate 356 can be transferred to the underside of the showerhead body 308, for example, by radiation and, to a lesser extent, convection. At the top of the deposition chamber 340, the temperature of the showerhead body 308 can be controlled by a combination of a heater 330 integrated into the upper portion of the showerhead body 308, multiple cooling channels 316 disposed above the showerhead body 308, and an insulating layer 318 interposed between the cooling channels 316 and the heater 330. In this manner, the temperature within the deposition chamber 340 can be controlled for optimal thin film deposition. FIG. 9 is an exploded perspective view of the showerhead assembly 300B, further illustrating the relationship between the heater 330, the insulating layer 318, and the showerhead body 308. The cooling channels 316 are embedded in the upper portion of the exploded view and are not visible at this viewing angle.

[0065] Turning to FIG. 10 , showerhead assembly 300B further includes temperature sensors 334, 336, and 338 positioned at different locations having different distances from the center when viewed from the top. In contrast to temperature sensor 331 shown in FIG. 3A , which is embedded in the upper part of housing 304 of showerhead assembly 300A, temperature sensors 334, 336, and 338 are embedded in showerhead body 308 of showerhead assembly 300B. As mentioned above, showerhead body 308 may be made of a highly conductive material, such as aluminum. Therefore, the temperature distribution within showerhead body 308 may be within a narrow range. The inventors of the present invention have discovered that embedding temperature sensors 334, 336, and 338 within a solid showerhead body 308 formed of a highly conductive material can optimize the response time of temperature sensing. Furthermore, the present inventors have discovered that for fast response time closed-loop temperature control, the temperature sensors 334, 336, 338 may be recessed within 0.5 inches, 0.3 inches, 0.1 inches, or a distance within a range defined by any of these values ​​from the underside of the showerhead body 308 facing the substrate 356, up to about 0.1 inches from the tapered underside facing the substrate 356. In the cross-sectional view of the portion of FIG. 8, the locations of two such temperature sensors are indicated by the numerals 334 and 336.

[0066] As discussed above, it may be desirable to control the temperature of the deposition chamber 340 (e.g., its underside) within a specific temperature range for depositing a particular thin film. In particular, controlling the temperature of the showerhead body 308 within a temperature range can be important for several reasons in maintaining temperature control during the deposition of a thin film on a substrate. For example, if the showerhead temperature is too low, unwanted deposition can occur on its surface. Such deposition can cause, among other things, changes in the showerhead's surface emissivity and particle generation. On the other hand, if the temperature is too high, secondary heating of the substrate due to radiation can occur. Analysis has been performed to guide the design of a temperature control system and heat transfer solution for the showerhead body 308.

[0067] FIG. 11 shows a partial cross-sectional view illustrating certain heat transfer components connected to the showerhead body 308 ( FIGS. 3A and 3B ), including a network of cooling channels 316. As described above, the network of cooling channels 316 formed in the upper portion of the housing 304 above the showerhead body 308 is configured to transfer heat away from the showerhead body 308. The cooling channels 316 are configured to carry a constant-temperature coolant that is circulated by a heat exchanger (not shown) so that the upper surface of the showerhead body 308 adjacent the cooling channels 316 is maintained at a relatively constant temperature. For example, the coolant can be maintained at a temperature of approximately 100° C., 120° C., 140° C., 160° C., 180° C., 200° C., 220° C., or within a range defined by any of these values. The temperature of the coolant is determined by the thin film to be deposited and the process configured to deposit the thin film in the deposition chamber 340.

[0068] In FIG. 11, the temperature of the underside of the housing 304 in contact with the showerhead body 308 is T liner For analytical purposes, the temperature T liner can be considered to be constant. As an example, the thermal contact resistance between the housing 304 and the top surface of the showerhead body 308, e.g., R contact , and the thermal resistance of the showerhead body 308, e.g., R Al , using known or estimated values, the temperature shown, e.g., T sh The heat transfer rate from the lower surface of the showerhead body 308 to the lower surface of the housing 304 can be calculated to maintain a temperature difference (e.g., ΔT) of more than 100° C. between the wafer-facing lower surface of the showerhead body 308 and the lower surface of the housing 304 (ΔT=T sh -T linerIt has been found that the magnitude of the heat transfer rate required to maintain the deposition chamber 340 exceeds 30,000 W, an order of magnitude greater than the typical power supplied for heating power supplied to semiconductor processing chambers. Conveniently in the industry, the power source for the deposition chamber 340 can be as large as 750 W. Applying 750 W to the equation that yielded the 30,000 W heat transfer rate above and employing the same assumptions, calculations reveal that the expected temperature difference ΔT is only about 4 degrees. This temperature difference across the showerhead body thickness from a 750 W heat transfer rate is too small to support effective temperature control of the showerhead body 308 for the purpose of maintaining the temperature of the deposition chamber 340.

[0069] The calculations performed above demonstrate the need for thermal engineering in the vertical stacking direction of the showerhead assembly 300A shown in FIG. 3A to improve the efficiency of closed-loop temperature control of the showerhead body 308. The inventors of the present invention have discovered that this need arises, in part, due to the high thermal conductivity of aluminum materials. As described below, the inventors of the present invention have further discovered that introducing a vertical series thermal resistance in accordance with some embodiments can improve thermal performance. As shown in FIGS. 3B, 9, and 11, an insulating layer 318 is interposed between the housing 304 and the showerhead body 308 to introduce additional series thermal resistance.

[0070] The present inventors have discovered that controlled thermal isolation between the housing 304 and the showerhead body 308 can be important in maintaining a substantial temperature difference ΔT, e.g., 10°C, 20°C, 30°C, 40°C, 50°C, or a temperature difference within a range defined by any of these values, and maintaining a narrow temperature range at the underside of the showerhead body 308 during deposition operations. For effective thermal isolation, in addition to physical separation, the present inventors have discovered that inserting an appropriate insulating layer (e.g., insulating layer 318) can be effective. The insulating layer 318 functions to slow down heat transfer by creating a substantial temperature across its thickness.

[0071] The basic heat transfer analysis model used above, which includes a set of thermal resistances, is used in the analysis. contact ) and the thermal resistance (R Al ), an additional thermal resistance resulting from the insulating layer 318 was added to the heat transfer model. This configuration allows the underside of the showerhead body 318 to be maintained at a suitable temperature, for example, at least 20° C. higher than the temperature of the coolant circulating through the cooling channels 316. The inventors of the present invention have found that the insulating layer 330 can be a suitable polymer film with a thermal resistance similar to polyetheretherketone (PEEK). Using a layer of PEEK for the insulating layer 318, a ΔT of 40° C. can be maintained between the underside of the showerhead body 308 and the underside of the housing 304, with the majority of the 40° C. spanning the PEEK insulating layer 318.

[0072] 3B, as part of a solution for maintaining the showerhead body 308 within a desired temperature range for depositing various types of thin films, a heater 330 can be coupled to the top of the showerhead body 308 to provide thermal energy for heating the showerhead body 308. The heater 330 can be a network of heating elements arranged to cover a large area on the top of the showerhead body 308. The heater 330 can be configured to provide 250 W, 500 W, 750 W, 1000 W, 1250 W, 1500 W, 1750 W, 2000 W of power, or a power within a range defined by any of these values. 3B , assuming that the heater 330 is configured to provide a maximum power of 750 W and that the underside of the showerhead body 308 can receive, e.g., up to 500 W, e.g., via radiation, from the deposition chamber 340 and substrate 356 below, calculations using the heat transfer model described above reveal that a thickness of 0.029 inches (0.7 mm) of the insulating layer 318 (e.g., a layer of PEEK) can maintain an adequate ΔT, e.g., 40° C., between the underside of the showerhead body 308 and the underside of the housing 304. It may be desirable to use a smaller power source to maintain ΔT at 40° C. In some embodiments, if the maximum radiation from the substrate 356 and deposition chamber 340 remains at 500 W, a power source of up to 250 W can maintain a temperature T sh Assuming that the insulating layer 318 is to be used for closed-loop control of the temperature, calculations have revealed that a thickness of 0.055 inches (1.4 mm) for the insulating layer 318 may be effective. Either a thickness of 0.029 inches or a thickness of 0.055 inches is a small thickness.

[0073] Using the heater 330, the network of cooling channels 316, the insulating layer 318 interposed therebetween, and the temperature sensors 334, 336, and 338, the showerhead assembly 300 can be configured with a closed-loop temperature control system for maintaining the underside of the showerhead body 308 within a relatively small temperature range during thin film deposition operations in the deposition chamber 340. The heater 330 and the network of cooling channels 316 configured in this manner, positioned at different vertical heights, and in thermal communication with each other and the showerhead body 308, are controlled together. Thus, the temperature of the underside of the showerhead body 308 facing the substrate 356 is maintained at least 20° C. higher than the temperature of the underside of the housing 304 or the coolant circulating through the cooling channels 316 during operation. In some embodiments, the temperature of the underside of the showerhead body 308 can be maintained at least 40° C. higher than the temperature of the coolant circulating through the cooling channels 316. Depending on the temperature of the coolant flowing within the coolant channels 306, the underside of the showerhead body 308 can be maintained at an average temperature of 120°C, 140°C, 160°C, 180°C, 200°C, 240°C, or a temperature within a range defined by any of these values, for example, a temperature within a range of 160°C to 230°C, during deposition of a thin film onto the substrate 356, which can be at temperatures greater than 300°C, 350°C, 400°C, 450°C, 500°C, 600°C, 650°C, or a temperature within a range defined by any of these values.

[0074] FIG. 12 shows temperature measurements of the underside of the showerhead body 308. It can be seen that the temperature within the showerhead body can be maintained within a relatively narrow range. For example, the lowest curve, corresponding to a chamber pressure of 5 Torr, is maintained between about 220°C and about 270°C for a wafer temperature of 620°C. Another observation is the effect of pressure within the deposition chamber 340 on the temperature measurements. For example, at TC6, the temperature drops from over 280°C when the pressure is 1 Torr to about 230°C when the pressure is increased to 5 Torr.

[0075] FIG. 13 shows, by way of example only, an exemplary precursor delivery sequence for delivering one or more precursors using a temperature-controlled showerhead assembly (e.g., showerhead assembly 300B) according to some embodiments. First and second precursor inlets of an injector block are connected to first and second precursor delivery lines, arranged, for example, as described above with respect to FIG. 1. Thus, two precursor delivery sequences are respectively illustrated by two charts in FIG. 13. In each chart, the vertical axis is flow rate (Q) and the horizontal axis is time (t). The ALD cycles in the two charts include a first subcycle for exposing substrate 356 to a first precursor (e.g., TiCl) and a second subcycle for exposing substrate 356 to a second precursor (e.g., NH). Each of the precursor ALD valves can be a three-way valve, and in some embodiments, a continuous purge (CP) gas, such as an inert gas, can be flowed through the ALD valve while substrate 356 is exposed to the first precursor and / or the second precursor. In the illustrated exemplary chart, the CP gas used is N2. When simultaneously introduced into the deposition chamber 340, the CP gas and precursors are mixed in the diffusion / mixing cavity 312 before being introduced into the deposition chamber 340, as described above. In the illustrated embodiment of FIG. 13, each of the first and second subcycles further includes a rapid purge (RP) with an inert gas after exposure to one or both of the first and second precursors, respectively. In FIG. 13, the rapid purge gas is N2, which is the same as the continuous purge gas used. The rapid purge can be performed using a purge ALD valve, as described above. As shown in FIG. 13, the rapid purge has a higher flow rate than the continuous purge.

[0076] The deposition system 100 according to the above-described embodiments is particularly advantageous for forming thin films on substrates containing high-aspect ratio structures with opening widths smaller than 1 micron, 500 nm, 200 nm, 100 nm, 50 nm, 20 nm, or a value within a range defined by any of these values, aspect ratios greater than 5, 10, 20, 50, 100, 200, or a value within a range defined by any of these values, and an areal density such that the surface area is greater than the surface area of ​​the flat substrate described above. Substrates having such topography can be conformally coated with a thin film comprising TiN, TiSiN, and / or TiAlN, or another suitable thin film, according to embodiments, with a step coverage as defined above of greater than 50%, 60%, 70%, 80%, 90%, 95%, or greater than a value within a range defined by any of these values.

[0077] High uniformity is one measure of conformality in the context of high aspect ratio structures, referred to herein as step coverage. A high aspect ratio structure may be, for example, a via, a hole, a trench, a cavity, a protrusion, or a similar structure. As an illustrative example, FIG. 14 schematically shows a semiconductor structure 500 having an exemplary high aspect ratio structure 516 formed therein to illustrate some exemplary metrics for defining and / or measuring the conformality of a thin film formed on the high aspect ratio structure. The illustrated high aspect ratio structure 516 is coated with a thin film 512, such as, for example, a TiN layer deposited according to some embodiments, the thin film having different thicknesses in different portions. As described herein, a high aspect ratio structure has an aspect ratio, e.g., a ratio defined as the depth or height (H) divided by the width (W) in the open area of ​​the high aspect ratio structure 516, greater than 1. In the illustrated example, the high aspect ratio structure 516 is a via formed through a dielectric layer 508, such as an intermetal dielectric (ILD) layer disposed on a semiconductor substrate 504, with the bottom surface of the high aspect ratio structure 516 exposing the underlying semiconductor 504. The thin film 512 can cover different surfaces of the high aspect ratio structure 516 with different thicknesses. As described herein, one metric for defining or measuring the conformality of a thin film formed with a high aspect ratio is called step coverage. Step coverage may be defined as the ratio between the thickness of the thin film in the lower or bottom region of the high aspect ratio structure and the thickness of the thin film in the upper or top region of the high aspect ratio structure. The upper or top region may be a region at a relatively small depth within the high aspect ratio structure, such as 0-10% or 0-25% of H, measured from the top of the opening. The lower or bottom region may be a region at a greater depth in the high aspect ratio structure, such as 90-100% or 75-100% of H measured from the top of the opening. In some high aspect ratio structures, step coverage can be defined or measured by the ratio of the thickness of the thin film 512A formed on the bottom surface to the thickness of the thin film 512C formed on the upper or top sidewall surfaces of the high aspect ratio structure.However, it will be appreciated that some high aspect ratio structures may not have a well-defined bottom surface or a bottom surface with a small radius of curvature, and in these structures, step coverage may be more consistently defined or measured by the ratio of the thickness of the thin film 512B formed on the lower or lower sidewall surface to the thickness of the thin film 512C formed on the upper or upper sidewall surface of the high aspect ratio structure.

[0078] The deposition system 100 according to some embodiments provides substantial improvements in step coverage in high-aspect ratio structures, due at least in part to the relatively constant temperature uniformity of the showerhead body 308 and the effective diffusion and / or mixing of precursors and purge gases. Using the temperature-controlled showerhead assembly 300B according to some embodiments, high-aspect ratio structures having aspect ratios greater than 1, 2, 5, 10, 20, 50, 100, 200, or values ​​within a range defined by any of these values, can be conformally coated with thin films, such as TiN films according to some embodiments, at step coverages defined herein of greater than 70%, 80%, 90%, 95%, or values ​​within a range defined by any of these values. The step coverage values ​​thus obtained represent an improvement of 5%, 10%, 15%, 20%, or values ​​within a range defined by any of these values, over corresponding step coverage values ​​obtained using a showerhead assembly for an equivalent thin film deposition system without appropriate temperature control. Additional Example I: 1. A temperature-controlled showerhead assembly configured to deliver multiple precursors to an atomic layer deposition (ALD) chamber, comprising: a showerhead comprising a solid body portion and a gas diffusion cavity formed through a central region of the body portion, the showerhead being configured to diffuse precursors within the gas diffusion cavity prior to introduction into the ALD chamber; a network of cooling channels formed above the showerhead and configured to conduct heat away from the showerhead; a network of heating elements in contact with the solid body portion and configured to supply heat to the showerhead; A shower head assembly comprising: 2. A temperature-controlled showerhead assembly configured to deliver multiple precursors to an atomic layer deposition (ALD) chamber, comprising: a solid body portion having a substantially flat outer surface facing away from the susceptor and a tapered inner surface facing the susceptor such that the thickness increases from a central region toward an edge portion; a conical gas diffusion chamber formed through a central region of the body portion and configured to diffuse precursors prior to their introduction into the ALD chamber; A shower head comprising: a network of cooling channels and a network of heating elements formed at different vertical heights and configured to maintain an inner surface of the solid body portion at a temperature at least 20° C. higher than the temperature of the cooling fluid filling the cooling channels during deposition; A shower head assembly comprising: 3. A temperature-controlled showerhead assembly configured to deliver multiple precursors to an atomic layer deposition (ALD) chamber, comprising: a showerhead comprising a solid body portion and a gas diffusion cavity formed through a central region of the body portion, the showerhead configured to diffuse precursors within the gas diffusion cavity prior to introduction into the thin film deposition chamber; a network of cooling channels formed above the showerhead and configured to conduct heat away from the showerhead; a network of heating elements configured to supply heat to the showerhead; a thermal insulating film interposed between the cooling channel and the heating element in a vertical direction and configured to limit heat transfer therebetween; A shower head assembly comprising: 4. The showerhead assembly of example 2 or 3, wherein the heating element contacts a solid portion of the showerhead. 5. The showerhead assembly of example 1 or 3, wherein the solid body portion has a substantially flat outer surface facing away from the susceptor and a tapered inner surface facing the susceptor such that the thickness of the solid body portion increases toward an edge portion. 6. The showerhead assembly of example 1 or 3, wherein the gas diffusion cavity is a conical gas diffusion cavity. 7. The showerhead assembly of example 1 or 3, wherein the network of cooling channels and the network of heating elements are formed at different vertical heights and are configured such that during deposition, the inner surface of the solid body portion is maintained at a temperature at least 20° C. higher than the temperature of the coolant filling the cooling channels. 8. The showerhead assembly of example 1 or 2, wherein the cooling channel and the heating element are thermally insulated from each other by a thermal insulating film interposed between them in the vertical direction. 9. The showerhead assembly of any one of the preceding examples, wherein the showerhead further comprises a plurality of thermocouples embedded in the solid body portion and positioned within 0.5 inches of the inner surface facing the susceptor. 10. The showerhead assembly of any one of the preceding examples, wherein the outer surface of the showerhead is radially sloped to have a neck angle of less than 10 degrees relative to the horizontal. 11. The showerhead assembly of any one of the preceding embodiments, wherein the gas diffusion cavity is a conical diffusion cavity having sidewalls with a cone angle of less than 10 degrees with respect to the vertical. 12. The showerhead assembly of any one of the previous examples, wherein the distance between the lowermost surface of the solid body portion facing the susceptor and the susceptor is less than 0.3 inches. 13. The showerhead assembly of any one of the preceding examples, wherein the gas diffusion cavity is a conical diffusion cavity having a diameter less than 30% of the diameter of the showerhead. 14. The showerhead assembly of any one of the preceding examples, wherein the showerhead assembly further comprises an injector block disposed above the showerhead, the injector having a plurality of injector channels formed therein configured to direct precursors in an oblique direction into the gas diffusion cavity. 15. The showerhead assembly of example 14, wherein the oblique direction is such that precursors exiting the injector channels are directed toward the sidewall of the gas diffusion cavity. 16. The showerhead assembly of example 14, further comprising a mixing chamber formed within the gas diffusion cavity, the plurality of injector channels configured to direct precursors into the mixing chamber prior to introduction into the ALD chamber. 17. The showerhead assembly of example 16, wherein the mixing chamber comprises a plurality of injectors configured to inject precursors into the ALD chamber. 18. The showerhead assembly of any one of the preceding embodiments, wherein the cooling channels and the heating elements do not overlap vertically. 19. The showerhead assembly of any one of the preceding embodiments, wherein a thermal insulating film comprising a polymer film is interposed between the cooling channels and the heating elements in the vertical direction. 20. The showerhead assembly of example 19, wherein the polymer film comprises polyetheretherketone (PEEK). 21. The showerhead assembly of example 19, wherein the polymer film has a thickness between 0.020 and 0.040 inches. 22. The showerhead assembly of any one of the preceding embodiments, wherein the cooling channels are filled with a coolant that is maintained at a substantially constant temperature by a heat exchanger. 23. The showerhead assembly of any one of the preceding examples, wherein the heating element comprises a resistive heating element. 24. The showerhead assembly of any one of the preceding examples, wherein the network of cooling channels and the network of heating elements are configured such that the inner surface of the solid body portion facing the susceptor is maintained at a temperature of 150-240°C during deposition. 25. The showerhead assembly of example 24, wherein the cooling channels are filled with a coolant that is maintained at a substantially constant temperature between 120 and 220°C. 26. The showerhead assembly of example 24, wherein the heating element is configured to dissipate between 500 W and 2000 W. 27. The showerhead assembly of example 24, wherein the ALD chamber comprises a susceptor configured to heat the substrate to between 300°C and 700°C. 28. The showerhead assembly of any one of the preceding embodiments, wherein the heating element does not contact the solid body portion. 29. The showerhead assembly of any one of the preceding embodiments, wherein the heating element does not contact the cooling channel. Additional Example II: 1. A temperature-controlled showerhead assembly configured to deliver multiple gases to a cyclic deposition chamber, comprising: a showerhead body having a cavity formed through a central region thereof, the cavity configured to diffuse or mix gases before the gases are introduced into the deposition chamber; a network of cooling channels configured to conduct heat away from the showerhead body; a network of heating elements configured to supply heat to the showerhead body, the network of heating elements being positioned closer to a top surface of the showerhead body than the cooling channels; A shower head assembly comprising: 2. The showerhead assembly of Example 1, wherein the networks of cooling channels and heating elements are arranged at different vertical heights. 3. The showerhead assembly of example 2, wherein the network of cooling channels and heating elements are thermally insulated from one another by an insulating layer interposed therebetween. 4. The showerhead assembly of example 3, wherein the network of cooling channels and heating elements laterally surrounds the cavity. 5. The showerhead assembly of example 4, wherein the cavity has a vertically elongated truncated conical shape, the width of the truncated conical shape increasing in a direction toward a susceptor disposed below the showerhead assembly. 6. The showerhead assembly of example 1, further comprising an injector block disposed above the showerhead body, the injector block having a plurality of channels formed therein for flowing different gases such that the different gases are directed in different directions into the cavity. 7. The showerhead assembly of example 6, wherein the cavity is configured to mix two different gases prior to their introduction into the deposition chamber. 8. The showerhead assembly of example 7, wherein one of the two different gases is an inert gas and the other of the two different gases is a reactant. 9. A temperature-controlled showerhead assembly configured to deliver multiple gases to a cyclic deposition chamber, comprising: a showerhead body having a substantially flat outer surface facing away from the susceptor and a tapered inner surface facing the susceptor such that the thickness increases from a central region toward an edge portion; a chamber formed through the showerhead body at a central region and configured to diffuse or mix gases prior to introducing the gases into the deposition chamber; A network of cooling channels and a network of heating elements formed at different vertical heights A shower head assembly comprising: 10. The showerhead assembly of example 9, wherein the network of cooling channels and the network of heating elements are configured such that, during deposition, the interior surface of the showerhead body is maintained at a temperature at least 20° C. above the temperature of the coolant filling the cooling channels. 11. The showerhead assembly of example 9, wherein the network of cooling channels and heating elements are thermally insulated from one another by a thermal insulating film interposed between them in the vertical direction. 12. The showerhead assembly of example 9, wherein the showerhead assembly further comprises a plurality of thermocouples positioned within 0.5 inches of the inner surface of the showerhead body facing the susceptor. 13. The showerhead assembly of example 9, wherein the outer surface of the showerhead body is radially sloped to have a neck angle of less than 10 degrees with respect to the horizontal. 14. The showerhead assembly of example 9, wherein the cavity is a conical cavity having sidewalls with a cone angle of less than 10 degrees relative to the vertical. 15. The showerhead assembly of example 9, wherein the distance between the bottom surface of the showerhead body facing the susceptor and the top surface of the susceptor is less than 0.3 inches. 16. A temperature-controlled showerhead assembly configured to deliver multiple gases to a cyclic deposition chamber, comprising: a showerhead body having a cavity formed through a central region thereof, the cavity configured to diffuse or mix gases before the gases are introduced into the deposition chamber; a network of cooling channels formed above the showerhead body and configured to conduct heat away from the showerhead; a network of heating elements configured to supply heat to the showerhead; a thermal insulating film interposed between the cooling channels and the network of heating elements in the vertical direction; A shower head assembly comprising: 17. The showerhead assembly of example 16, wherein the lateral footprint occupied by the network of cooling channels falls within the lateral footprint occupied by the network of heating elements. 18. The showerhead assembly of example 16, wherein the thermally insulating film comprises a polymer film. 19. The showerhead assembly of example 18, wherein the polymer film comprises polyetheretherketone (PEEK). 20. The showerhead assembly of example 19, wherein the polymer film has a thickness between 0.020 and 0.040 inches.

[0079] While the invention has been described herein with reference to specific embodiments, these embodiments do not serve to limit the invention, but are set forth for purposes of illustration. It will be apparent to those skilled in the art that modifications and improvements can be made without departing from the spirit and scope of the invention.

[0080] Such simple modifications and improvements of the various embodiments disclosed herein are within the scope of the disclosed technology, the specific scope of which is further defined by the appended claims.

[0081] In the above, it will be understood that any feature of one embodiment can be combined with or substituted for any other feature of another embodiment.

[0082] Unless the context clearly dictates otherwise, throughout the specification and claims, words such as "comprise," "comprising," "include," "including," and the like, shall be construed in an inclusive sense, i.e., "including, but not limited to," and not in an exclusive or exhaustive sense. The term "coupled," as generally used herein, refers to two or more elements that may be directly connected or that may be connected by one or more intermediate elements. Similarly, the term "connected," as generally used herein, refers to two or more elements that may be directly connected or that may be connected by one or more intermediate elements. Furthermore, the words "herein," "above," "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural may also include the plural or singular, respectively. The word "or" in connection with a list of two or more items covers all of the following interpretations of that word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0083] Furthermore, conditional language used herein, such as, among others, "can," "could," "might," "may," "e.g.," "for example," "such as," and the like, is generally intended to convey that certain embodiments include certain features, elements, and / or conditions, while other embodiments do not, unless otherwise specified or understood otherwise in the context of use. Thus, such conditional language is generally not intended to imply that features, elements, and / or conditions are in any way required by one or more embodiments, or whether these features, elements, and / or conditions are included in or performed in any particular embodiment.

[0084] While specific embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel apparatus, methods, and systems described herein may be embodied in a variety of other forms, and various omissions, substitutions, and changes may be made in the methods and systems described herein without departing from the spirit of the present disclosure. For example, while features are presented in a given configuration, alternative embodiments may perform similar functions with different component and / or sensor topology, and some features may be deleted, moved, added, subdivided, combined, and / or modified. Each of these features may be implemented in a variety of different ways. Any suitable combination of elements and operations of the various embodiments described above may be combined to provide further embodiments. The various features and processes described above may be implemented independently of one another or combined in various ways. All possible combinations and subcombinations of features of the present disclosure are intended to be within the scope of the present disclosure.

Claims

1. 1. A temperature-controlled showerhead assembly configured to deliver a plurality of gases to a cyclic deposition chamber, comprising: a showerhead body having a cavity formed through a central region, the cavity configured to diffuse or mix the gases before the gases are introduced into the deposition chamber; a network of cooling channels configured to conduct heat away from the showerhead body; a network of heating elements configured to supply heat to the showerhead body, the network of heating elements being positioned closer to a top surface of the showerhead body than the cooling channels; A shower head assembly comprising:

2. 10. The showerhead assembly of claim 1, wherein the network of cooling channels and the network of heating elements are disposed at different vertical heights.

3. 3. The showerhead assembly of claim 2, wherein the network of cooling channels and the network of heating elements are thermally insulated from one another by an insulating layer interposed therebetween.

4. 4. The showerhead assembly of claim 3, wherein the network of cooling channels and heating elements laterally surrounds the cavity.

5. 5. The showerhead assembly of claim 4, wherein the cavity has a vertically elongated frustum shape, the width of the frustum shape increasing in a direction toward a susceptor disposed below the showerhead assembly.

6. 10. The showerhead assembly of claim 1, further comprising an injector block disposed above the showerhead body, the injector block having a plurality of channels formed therein for flowing different gases such that the different gases are directed in different directions into the cavity.

7. 7. The showerhead assembly of claim 6, wherein the cavity is configured to mix two different gases prior to introduction into the deposition chamber.

8. 8. The showerhead assembly of claim 7, wherein one of the two different gases is an inert gas and the other of the two different gases is a reactant.

9. 1. A temperature-controlled showerhead assembly configured to deliver a plurality of gases to a cyclic deposition chamber, comprising: a showerhead body having a substantially flat outer surface facing away from the susceptor and a tapered inner surface facing the susceptor such that the thickness increases from a central region toward an edge portion; a chamber formed through the showerhead body in the central region and configured to diffuse or mix the gases prior to introducing the gases into the deposition chamber; A network of cooling channels and a network of heating elements formed at different vertical heights A shower head assembly comprising:

10. 10. The showerhead assembly of claim 9, wherein the network of cooling channels and the network of heating elements are configured such that, during deposition, the inner surface of the showerhead body is maintained at a temperature at least 20° C. above a temperature of a coolant filling the cooling channels.

11. 10. The showerhead assembly of claim 9, wherein the cooling channels and the network of heating elements are thermally insulated from one another by a thermal insulating film interposed between them in a vertical direction.

12. 10. The showerhead assembly of claim 9, further comprising a plurality of thermocouples positioned within 0.5 inches of the inner surface of the showerhead body that faces a susceptor.

13. 10. The showerhead assembly of claim 9, wherein the outer surface of the showerhead body is radially sloped to have a neck angle of less than 10 degrees with respect to horizontal.

14. 10. The showerhead assembly of claim 9, wherein the cavity is a conical cavity having sidewalls at a cone angle of less than 10 degrees with respect to vertical.

15. 10. The showerhead assembly of claim 9, wherein the distance between a bottom surface of the showerhead body facing a susceptor and a top surface of the susceptor is less than 0.3 inches.

16. 1. A temperature-controlled showerhead assembly configured to deliver a plurality of gases to a cyclic deposition chamber, comprising: a showerhead body having a cavity formed through a central region, the cavity configured to diffuse or mix the gases before the gases are introduced into the deposition chamber; a network of cooling channels formed above the showerhead body and configured to conduct heat away from the showerhead; a network of heating elements configured to supply heat to the showerhead; a thermal insulating film interposed between the cooling channels and the network of heating elements in the vertical direction; A shower head assembly comprising:

17. 17. The showerhead assembly of claim 16, wherein a lateral footprint occupied by the network of cooling channels falls within a lateral footprint occupied by the network of heating elements.

18. 17. The showerhead assembly of claim 16, wherein the thermally insulating film comprises a polymer film.

19. 20. The showerhead assembly of claim 18, wherein the polymer film comprises polyetheretherketone (PEEK).

20. 20. The showerhead assembly of claim 19, wherein the polymer film has a thickness between 0.020 and 0.040 inches.

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