Patent Application
20240420969
During semiconductor processing operations, a substrate is typically supported on a pedestal within a processing chamber and process gases are flowed into the chamber in order to deposit one or more layers of material onto the substrate, or to remove one or more layers of material from a substrate. The commercial viability of a semiconductor processing operation depends in large part upon within-wafer uniformity and wafer-to-wafer repeatability of the process conditions. Apparatuses for controlling the gas flows are required to create desired processing conditions and the desired overall process and product.
Background and contextual descriptions contained herein are provided solely for the purpose of generally presenting the context of the disclosure. Much of this disclosure presents work of the inventors, and simply because such work is described in the background section or presented as context elsewhere herein does not mean that it is admitted to be prior art.
Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. The following, non-limiting implementations are considered part of the disclosure; other implementations will be evident from the entirety of this disclosure and the accompanying drawings as well.
The various implementations disclosed herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.
In this application, the terms “semiconductor wafer,” “wafer,” “substrate,” “wafer substrate,” and “partially fabricated integrated circuit” are used interchangeably. One of ordinary skill in the art would understand that the term “partially fabricated integrated circuit” can refer to a silicon wafer during any of many stages of integrated circuit fabrication thereon. A wafer or substrate used in the semiconductor device industry typically has a diameter of 200 mm, or 300 mm, or 450 mm. The following detailed description assumes the invention is implemented for use with such a wafer. However, the invention is not so limited. The work piece may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other work pieces that may take advantage of this invention include various articles such as printed circuit boards, magnetic recording media, magnetic recording sensors, mirrors, optical elements, micro-mechanical devices and the like.
For the purposes of this disclosure, the term “fluidically connected” is used with respect to volumes, plenums, holes, etc., that may be connected with one another in order to form a fluidic connection, similar to how the term “electrically connected” is used with respect to components that are connected together to form an electric connection. The term “fluidically interposed,” if used, may be used to refer to a component, volume, plenum, or hole that is fluidically connected with at least two other components, volumes, plenums, or holes such that fluid flowing from one of those other components, volumes, plenums, or holes to the other or another of those components, volumes, plenums, or holes would first flow through the “fluidically interposed” component before reaching that other or another of those components, volumes, plenums, or holes. For example, if a pump is fluidically interposed between a reservoir and an outlet, fluid that flowed from the reservoir to the outlet would first flow through the pump before reaching the outlet.
Some semiconductor processes are used to deposit one or more layers of a material onto a substrate. Example deposition processes include chemical vapor deposition (“CVD”), plasma-enhanced CVD (“PECVD”), atomic layer deposition (“ALD”), low pressure CVD, ultra-high CVD, physical vapor deposition (“PVD”), and conformal film deposition (“CFD”). Some CVD processes may deposit a film on a wafer surface by flowing one or more gas reactants into a reactor which form film precursors and by-products. The precursors are transported to the wafer surface where they are adsorbed by the wafer, diffused into the wafer, and deposited on the wafer by chemical reactions, including by the generation of a plasma in PECVD. Some other deposition processes involve multiple film deposition cycles, each producing a “discrete” film thickness. ALD is one such film deposition method, but any technique which puts down thin layers of film and used in a repeating sequential matter may be viewed as involving multiple cycles of deposition.
As device and features size continue to shrink in the semiconductor industry, and also as 3D devices structures become more prevalent in integrated circuit (IC) design, the capability of depositing thin conformal films (films of material having a uniform thickness relative to the shape of the underlying structure, even if non-planar) continues to gain importance. ALD is a film forming technique which is well-suited to the deposition of conformal films due to the fact that a single cycle of ALD only deposits a single thin layer of material, the thickness being limited by the amount of one or more film precursor reactants which may adsorb onto the substrate surface (i.e., forming an adsorption-limited layer) prior to the film-forming chemical reaction itself. Multiple “ALD cycles” may then be used to build up a film of the desired thickness, and since each layer is thin and conformal, the resulting film substantially conforms to the shape of the underlying devices structure. In certain embodiments, each ALD cycle includes the following steps: (1) Exposure of the substrate surface to a first precursor, i.e., a “dose phase,” (2) purge of the reaction chamber in which the substrate is located, i.e., a purge phase,” (3) activation of a reaction of the substrate surface, typically with a plasma and/or a second precursor, i.e., an “activation phase,” and (4) purge of the reaction chamber in which the substrate is located, i.e., another purge phase
The duration of each ALD cycle may typically be less than 25 seconds or less than 10 seconds or less than 5 seconds. The plasma exposure step (or steps) of the ALD cycle may be of a short duration, such as a duration of 1 second or less, for example. The plasma may be of other durations longer than that 1 second, such as 2 seconds, 5 seconds, or 10 seconds, for instance.
Some semiconductor fabrication processes involve patterning and etching of various materials, including conductors, semiconductors, and dielectrics. Some examples include conductors, such as metals or carbon; semiconductors, such as silicon or germanium; and dielectrics, such as silicon oxide, aluminum dioxide, zirconium dioxide, hafnium dioxide, silicon nitride, and titanium nitride. Atomic layer etching (“ALE”) processes remove thin layers of material using sequential self-limiting reactions. Generally, an ALE cycle is the minimum set of operations used to perform an etch process one time, such as etching a monolayer. The result of one ALE cycle is that at least some of a film layer on a substrate surface is etched. Typically, an ALE cycle includes a modification operation to form a reactive layer, followed by a removal operation to remove or etch only this reactive layer. The cycle may include certain ancillary operations such as removing one of the reactants or byproducts. Generally, a cycle contains one instance of a unique sequence of operations.
As an example, a conventional ALE cycle may include the following operations: (i) delivery of a reactant gas, (ii) purging of the reactant gas from the chamber, (iii) delivery of a removal gas and an optional plasma, and (iv) purging of the chamber. In some embodiments, etching may be performed nonconformally. The modification operation generally forms a thin, reactive surface layer with a thickness less than the un-modified material. In an example modification operation, a substrate may be chlorinated by introducing chlorine into the chamber. Chlorine is used as an example etchant species or etching gas, but it will be understood that a different etching gas may be introduced into the chamber. The etching gas may be selected depending on the type and chemistry of the substrate to be etched. A plasma may be ignited and chlorine reacts with the substrate for the etching process; the chlorine may react with the substrate or may be adsorbed onto the surface of the substrate. The species generated from a chlorine plasma can be generated directly by forming a plasma in the process chamber housing the substrate or they can be generated remotely in a process chamber that does not house the substrate, and can be supplied into the process chamber housing the substrate.
In order to perform these various processing operations, semiconductor processing tools, including those with one processing station in a processing chamber (“single-station tools”) and those with two or more processing stations in a single processing chamber (“multi-station tools”), have a process fluid delivery system that delivers numerous process fluids, such as process gases, liquids, fluids, and/or vapors (collectively referred to herein as “process gases” or “process gas”), to each processing station by flowing the each process gas from a common source through a manifold to a gas dispersion device, e.g., a showerhead, at the processing station. For multi-station tools, the process fluid delivery system delivers the numerous process fluids to each station by flowing each process gas from its common source through a gas manifold that has one or more junction points and multiple legs, or flowpaths, to the showerhead at each processing station. Although “showerhead” is used herein, such term encompasses any gas dispersion device, such as nozzles, ports, holes, or other structure that flows a gas or fluid into the processing chamber.
In order to flow multiple process gases to a single processing station, whether in a single-station or multi-station tool, that processing station may have a common junction manifold, hereinafter a “valve manifold,” where the inlets for the station come together, i.e., a common location where a leg of each of the multiple gas manifolds is physically and fluidically connected to the station. The valve manifold therefore includes multiple inputs that are each fluidically connected to one leg of each gas manifold. The valve manifold also includes a common outlet through which the gases flowed into the valve manifold flow into the gas dispersion device. In some implementations, the valve manifold may include a second outlet, e.g., a divert outlet, for diverting the process gases to a divert flow path and not to the processing chamber or processing station. The valve manifolds also include valves that control some of the gas flows into and through the valve manifold.
Some semiconductor processing tools flow a process gas, such as a precursor, and a purge gas through separate gas manifolds into the single, common valve manifold without providing a local flow control of the purge gas, e.g., without providing a valve on the valve manifold to control the flow of the purge gas into and/or through the valve manifold and to the showerhead. The present inventors discovered that this configuration can present various challenges and result in numerous disadvantages. For example, without flow control between the valve manifold and the purge gas manifold at the valve manifold, process gas can undesirably flow from the process gas manifold, into the valve manifold, and into the purge gas manifold. This backflow or backstream of the process gas into the purge gas manifold can cause numerous unwanted effects, such as deposition of a precursor in the purge gas manifold, damage to the purge gas manifold, and generation and flow of particles from the purge gas manifold onto the wafer. Some semiconductor processing tools prevent this backstream of process gas into the purge gas manifold by flowing the purge gas through the purge manifold at a low flowrate, sometimes referred to as a trickle purge, during one or more process steps, such as before, during, and/or after flowing the process gas. While this trickle purge may prevent some unwanted backflow of process gas into the purge gas manifold, the trickle purge can further cause unwanted effects, such as dilution of the process chemistry which can adversely affect process conditions. For instance, dilution of deposition process chemistry can undesirably slow growth rates or adversely affect deposited film properties.
Additionally, without local control of the purge gas at the valve manifold, the purge gas manifold may have an undesirably long leg and/or large dead leg volume. For example, some semiconductor processing tools flow the purge gas from its upstream source or upstream flow control point (e.g., a mass flow controller (MFC)) not locally positioned at or near the processing chamber, which results in a long leg (or long flowpath made up of multiple pipes, tubs, or other flow elements) having a large “dead leg” volume. Such configurations increase the purge gas flow control time which undesirably increases processing time. A dead leg generally refers to a volume of a gas or a portion of a fluid flow system where the gas or fluid can remain largely stagnant. These dead legs may be undesirable because, in some semiconductor processing, these dead legs may not be able to be properly cleaned which can lead to unwanted residue or buildup that can contaminate wafers. Further, some semiconductor processes use purge gases at a particular temperature, which may require temperature control, e.g., heating and maintaining the heat of, the purge gas. Having a purge gas manifold with a long leg and/or large dead leg volume makes this temperature control more challenging and for these processes, a purge gas at the incorrect temperature can cause undesirable effects.
A purge gas manifold with an undesirably long leg and large dead leg volume also can prevent charging the purge gas manifold and preforming a “burst purge.” It may be desirable to charge the purge gas manifold and thereby increase its pressure and concentration to more quickly and efficiently purge the gas dispersion device and processing station. However, this burst purge may not be feasible without local control of the purge gas manifold at the valve manifold. As described below, the present inventors determined that providing a valve manifold with local control of the purge gas manifold can result in numerous advantages including preventing unwanted backstream, enabling more precise purge gas flow, enabling a burst purge, and improving processing conditions by eliminating the trickle purge.
Aspects of this disclosure pertain to improving flow control of a purge gas at a processing station by using a valve manifold as provided herein. The valve manifold includes a process gas inlet, a purge gas inlet, an outlet to the showerhead, and a divert outlet to the divert flowpath, as well as three valve interfaces with multiple ports that enable valves to control the flow control of the various gases within and through the valve manifold. When valves are interfaced with the valve manifold, the valve manifold and valves are configured to control the flow of the purge gas to the showerhead, such preventing the purge gas from flowing through the valve manifold and to the showerhead while the process gas is flowing to the showerhead, allowing the purge gas to flow through the valve manifold to the showerhead while being fluidically separate from the process gas, as well as control the flow of the process gas to the showerhead, such as allowing the process gas to flow through the valve manifold and to the showerhead while keeping the purge gas and purge gas manifold fluidically separate from the process gas, preventing the process gas from flowing to the showerhead and to the purge gas manifold, and allowing the process gas to flow to the divert flowpath.
Also shown in
A second valve interface 118 is also shown within a dashed box and includes a first port 120, a second port 122, a third port 124, and a fourth port 126. The first port 120 is fluidically connected with the process gas inlet 102 via a third flowpath, not visible here, internal to the manifold body 110 and having no dead legs. The second port 122 of the second valve interface 118 is fluidically connected with the second port 116 of the first valve interface 112 via a second flowpath, not visible here, internal to the manifold body 110 and having no dead legs. The third port 124 configuration is discussed further below. The fourth port 126 of the second valve interface 118 is fluidically connected with the manifold outlet 106 via a fifth flowpath, not visible here, internal to the manifold body 110 and having no dead legs.
A third valve interface 128 is shown within a dashed box and includes a first port 130 and a second port 132. The first port 130 of the third valve interface 128 is fluidically connected with the third port 124 of the second valve interface 118 via a fourth flowpath, not visible here, internal to the manifold body 110 and having no dead legs. The second port 132 is fluidically connected with the divert outlet 108 via a sixth flowpath, not visible here, internal to the manifold body 110 and having no dead legs.
Some features of the manifold body may be positioned in various locations and orientations in order to, for example, enable the valve manifold to be positioned near the showerhead, reduce its internal volume, reduce its total volume, and/or enable maintenance to be performed on the valve manifold. In some embodiments, as illustrated in
In some embodiments, as shown in
These flowpaths are further illustrated in
The valve manifold described herein is used with a plurality of valves to control flow through and within the valve manifold.
The first valve 156 is configured to be switchable between an open state and a closed state, and when interfaced with the first valve interface 112, is also configured to control flow between the first port 114 and the second port 116 of the first valve interface 112. In some instances, the open state of the first valve 156 may include a fully open state in which flow is unrestricted or one or more partially open states in which a semi-restricted flow is allowed between the first port 114 and second port 116; the closed state of the first valve 156 may fully restricted flow between the first port 114 and second port 116 and therefore prevent any flow between these two ports. Similarly, the third valve 160 is configured to be switchable between an open state and a closed state, and when interfaced with the third valve interface 128, is configured to control flow between the first port 130 and the second port 132 of the third valve interface 128. In some instances, the open state of the third valve 160 may include a fully open state in which flow is unrestricted or one or more partially open states in which a semi-restricted flow is allowed between the first port 130 and second port 132; the closed state of the third valve 160 may fully restricted flow between the first port 130 and second port 132 and therefore prevent any flow between these two ports.
The second valve 156 is configured to be switchable between an open state and a closed state, and when interfaced with the second valve interface 118, is configured to control the flow of the ports of the second interface 118 as explained herein. For example, when in the open state, the second valve 156 may allow flow between the first port 120 and the fourth port 126 of the second valve interface 118 and not between the first port 120 and the third port 124 of the second valve interface 118. In the closed state, for instance, the second valve 156 may allow flow between the first port 120 and the third port 124 of the second valve interface 118 and not between the first port 120 and the fourth port 126 of the second valve interface 118. In some instances, the second port 122 of the second valve interface 118 may be fluidically connected to the fourth port 126 when the second valve 158 is in the open and closed configurations.
The valves and their configurations are able to control the flow in and within the valve manifold as described in more detail with respect to
In some implementations, once the purge gas reaches the second port 122 of the second valve interface 118, depending on the configuration of the second valve, not pictured, the purge gas may be able to flow to the manifold outlet 106. In some such implementations, as noted above, the second valve may fluidically connect the second port 122 of the second valve interface 118 with the fourth port 126 when the second valve 158 is in any configuration, such as in the open and closed configurations. This may fluidically connect the second port 122 of the second valve interface 118 with the fourth port 126 of the second valve interface 118, and thereby fluidically connect the second port 122 to the fifth flowpath 142 and the manifold outlet 106. Accordingly, in some such implementations, when the first valve is in the open state, the purge gas inlet 104 may be fluidically connected to the manifold outlet 106. This fluidic connection may be the purge gas inlet 104 being fluidically connected to the first flowpath 134, the first flowpath 134 being fluidically connected to the second flowpath 136 as provided by the first valve, and the second flowpath 136 being fluidically connected to the fifth flowpath 142 and the manifold outlet 106 as provided by the second valve. As noted above, the fluidic connection between the purge gas inlet 104 and the manifold outlet 106 is represented by the white arrows 162.
The second valve is also configured to provide various flow controls and fluidic connections. In some embodiments, the second valve may be configured such that when it is interfaced with the second valve interface 118, the second port 122 is fluidically connected to the fourth port 126 in any and all of the second valve states, such as the open state, partially open state, and the closed state. In
It will be understood that the second valve is configured to provide at least two fluidically separate, fluidically isolated, and fluidically independent flowpaths through the second valve. As illustrated in
Positioning the second valve in the closed state provides various advantages. For example, the purge gas can be flowed into and through valve manifold 100, out the manifold outlet 106 and into the processing station, independent of and fluidically separate from the process gas. Additionally, the process gas can flow into and through the valve manifold 100 can be further controlled, e.g., stopped or flowed to the divert outlet 108. For various processing operations, it is desirable to flow the process gas through the manifold outlet 106 and onto a wafer in the processing chamber at some specific times and phases during processing operations, and not onto the wafer at other times and phases of the processing operations. For example, some ALD processes may flow the process gas, e.g., a precursor, during the dose phase, but not during the purge phases or the activation phase. With the valve manifold and valves herein, by positioning the second valve in the closed state, the process gas is prevented from flowing through the fourth port 126, through the manifold outlet 106, and into the processing chamber.
The flow of the process gas through the valve manifold 100 is further controlled by the third valve when it is interfaced with the third valve interface 128. When the third valve is interfaced with the third valve interface 128, the third valve is configured to control gas flow between the first port 130 and the second port 132 of the third valve interface 128. In
In some implementations, the third valve is therefore configured to control the flow of the process gas to the divert outlet. This may include when the second valve is in the closed state and the first port 120 of the second valve interface 118 is fluidically connected to the third port 126 of the second valve interface. In some embodiments, when it is desired to stop the process gas flow to the processing chamber and showerhead therein, it may be advantageous to divert the process gas to the divert outlet, instead of stopping its flow. The valve manifold 100 and corresponding valves enable such operation by, as illustrated in
In some embodiments, additionally or alternatively, it may be advantageous to stop the flow of the process gas through the valve manifold by configuring the third valve in the closed state.
The flow of the process gas to the manifold outlet 106 and to the processing chamber will now be discussed. In some embodiments, the process gas may be flowed to the manifold valve outlet 106 by configuring the second valve in the open state.
In some embodiments, while the process gas is flowed through the valve manifold to the manifold outlet 106, e.g., by having the second valve in the open state, the first valve is in a closed state, as indicated by the “X” on the first port 114 and second port 116 of the first valve interface 112, thereby preventing the purge gas from flowing through the first port 114 and into the second port 116 and second flowpath 136. This is illustrated by the purge gas arrows 162 stopping at the first port 114. Because the second valve may provide the fluidic connection 166 between the fourth port 126 and the second port 122 of the second valve interface 118 when in the open configuration, the first valve being configured to the closed state when the second valve is in the open state prevents unwanted backflow of the process gas to the purge gas manifold that is fluidically connected to the purge gas inlet 104. By preventing the unwanted backflow of process gas into the purge gas manifold, a trickle purge, e.g., a constant flow of purge gas through the purge gas manifold while the process gas is flowed to the showerhead, is not needed. This provides numerous benefits, such as reducing or eliminating the unwanted dilution of the process gas which improves performance of the processing operations, such as improved deposition growth rate and reduced defects.
Configuring the first valve in the closed state while the process gas is flowing to the manifold outlet 106 further allows for the purge manifold to be charged, and in some instances pressurized, which provides numerous advantages, such as increasing the purge gas concentration and pressure inside the purge gas manifold to provide a burst purge through the manifold and into the showerhead. This burst purge can purge the showerhead faster by more efficiently (given its higher concentration) as compared to traditional purges. This can reduce the time required for a purge, and also perform a better purge.
This configuration of the apparatus 101 also creates a small purge gas leg and volume between the showerhead and the first valve, instead of the larger purge gas leg between the showerhead and the purge gas source. By having a smaller purge gas leg and volume, the purge gas flow control is faster and also reduces or eliminates the need for the complex temperature control of the purge gas manifold and its associated unwanted effects.
In some embodiments, while the second valve is in the open state, the third valve may be in a closed state, as indicated by the “X” on the first port 130 and second port 132 of the third valve interface 128, thereby preventing the process gas from flowing through the first port 130 and into the second port 132, sixth flowpath 144, and out through the divert outlet 108. In some embodiments, as an extra safety precaution, the second valve and the third valve may be interlocked such that when the second valve is in the open state, the third valve is in the closed state, and when the second valve is in the closed state, the third valve is in the open state.
Further examples of the valve operations and gas flows through the valve manifold of the apparatus will now be described.
Referring back to
The purge times of
In some embodiments, from at least times t1 through time t3, the process gas may be continuously flowing from the process gas source towards the processing station, but as described herein, it is directed to the showerhead and wafer for only a part of this time period and directed to the divert flowpath for another part of this time period. This configuration of the apparatuses provided herein enable this continuous process gas flow and such continuous gas flow presents numerous advantages, such as maintaining relatively constant and stable process gas flow conditions, e.g., flowrate and pressure, thereby reducing process gas variability, and also providing fast process gas control response time by having the process gas located at the valve manifold and close to the showerhead at the start of the dose period as opposed to waiting for the processing gas to flow from the gas source to the valve manifold.
In some other embodiments, the process gas may not continuously flow through the valve manifold and instead it may be stopped as illustrated in
Referring back to
After time t4 in
After time t5, another cycle may be performed from time t5 to time t6 in
The valve manifolds and apparatuses provided herein may be used various processing techniques and operations, such as ALD or ALE, to deposit or etch material.
Block 911 may correspond to a dose phase of an ALD cycle during which precursor is flowed to the showerhead and corresponding wafer, or to a modification phase of an ALE cycle during which a modifying gas is flowed to the showerhead and corresponding wafer. In some instances, as provided herein, the third valve may also be in the closed state during block 911.
In block 913, the purge gas is flowed to the showerhead and corresponding wafer by, as provided above, configuring the first valve in the open state and the second valve in the closed state. This enables the purge gas to flow through the second port 116 of the first valve interface 112, through the second flow path 136, through the second port 122 of the second valve interface 118, through the fourth port 126 of the second valve interface 118 and out the manifold outlet 106 to the showerhead and wafer. With the second valve in the closed state, the process gas can flow through the first port 120 of the second valve interface 118 to the third port 124 of the second valve interface 118 and with the third valve in the open state, the process gas can continue flowing through the first port 130 and second port 132 of the third valve interface 128 and out the divert outlet 108.
Block 913 may correspond with a purge phase of an ALD cycle or an ALE cycle. For ALD cycles, as illustrated in
For ALE, these processes remove thin layers of material using sequential self-limiting reactions. Generally, an ALE cycle is the minimum set of operations used to perform an etch process one time, such as etching a monolayer. The result of one ALE cycle is that at least some of a film layer on a substrate surface is etched. Typically, an ALE cycle includes a modification operation to form a reactive layer, followed by a removal operation to remove or etch only this reactive layer. The cycle may include certain ancillary operations such as removing one of the reactants or byproducts, as well as a cleaning operation to remove residues that have built up on surfaces of the processing chamber. Generally, a cycle contains one instance of a unique sequence of operations. As an example, an ALE cycle may include the following operations: (i) delivery of a first process gas that is a reactant gas, (ii) purging of the reactant gas from the chamber, (iii) delivery of a second process gas that is a removal gas and an optional plasma, and (iv) purging of the chamber. The modification operation (item (ii) above) generally forms a thin, reactive surface layer with a thickness less than the un-modified material, such as one, two, or three, atomic layers thick, for instance, or less than a whole atomic layer in one cycle.
The valve manifolds and apparatuses herein may be incorporated to semiconductor processing tools and chambers in order to control the flow of a process gas and a purge gas to a processing station in the processing chamber, including controlling such flows to multiple stations of a multi-station processing chamber and the station of a single-station chamber and these chambers may be used to perform various processing operations such as deposition or etching.
Process station 1200 fluidly communicates with gas delivery system 1201 for delivering process gases to a distribution showerhead 1206. Gas delivery system 1201 includes a mixing vessel 1204 for blending and/or conditioning process gases for delivery to showerhead 1206. One or more mixing vessel inlet valves 1220 may control introduction of process gases to mixing vessel 1204.
The gas delivery system 1201 also includes the apparatus 101 provided above that includes the valve manifold, first, second, and third valves, and other features described herein. The manifold outlet of this apparatus 101 is seen fluidically connected to the showerhead 1206, the process gas is seen fluidically connected to the process gas inlet, the purge gas is fluidically connected to the purge gas inlet, and the divert outlet is fluidically connected to the divert flowpath as described herein. The purge gas and process gas are configured to flow to the showerhead 1206, and be controlled, as described herein.
Some reactants, like BTBAS, may be stored in liquid form prior to vaporization at and subsequent delivery to the process station. For example, the embodiment of
In some embodiments, reactant liquid may be vaporized at a liquid injector. For example, a liquid injector may inject pulses of a liquid reactant into a carrier gas stream upstream of the mixing vessel. In one scenario, a liquid injector may vaporize reactant by flashing the liquid from a higher pressure to a lower pressure. In another scenario, a liquid injector may atomize the liquid into dispersed microdroplets that are subsequently vaporized in a heated delivery pipe. It will be appreciated that smaller droplets may vaporize faster than larger droplets, reducing a delay between liquid injection and complete vaporization. Faster vaporization may reduce a length of piping downstream from vaporization point 1203. In one scenario, a liquid injector may be mounted directly to mixing vessel 1204. In another scenario, a liquid injector may be mounted directly to showerhead 1206.
In some embodiments, a liquid flow controller upstream of vaporization point 1203 may be provided for controlling a mass flow of liquid for vaporization and delivery to process station 1200. For example, the liquid flow controller (LFC) may include a thermal mass flow meter (MFM) located downstream of the LFC. A plunger valve of the LFC may then be adjusted responsive to feedback control signals provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, it may take one second or more to stabilize liquid flow using feedback control. This may extend a time for dosing a liquid reactant. Thus, 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 a feedback control mode to a direct control mode by disabling a sense tube of the LFC and the PID controller.
Showerhead 1206 distributes process gases toward substrate 1212. In the embodiment shown in
In some embodiments, a microvolume 1207 is located beneath showerhead 1206. Performing an ALD and/or CVD process in a microvolume rather than in the entire volume of a process station may reduce reactant exposure and sweep times, may reduce times for altering process conditions (e.g., pressure, temperature, etc.), may limit an exposure of process station robotics to process gases, etc. Example microvolume sizes include, but are not limited to, volumes between 0.1 liter and 2 liters. This microvolume also impacts productivity throughput. While deposition rate per cycle drops, the cycle time also simultaneously reduces. In certain cases, the effect of the latter is dramatic enough to improve overall throughput of the module for a given target thickness of film.
In some embodiments, pedestal 1208 may be raised or lowered to expose substrate 1212 to microvolume 1207 and/or to vary a volume of microvolume 1207. For example, in a substrate transfer phase, pedestal 1208 may be lowered to allow substrate 1212 to be loaded onto pedestal 1208. During a deposition process phase, pedestal 1208 may be raised to position substrate 1212 within microvolume 1207. In some embodiments, microvolume 1207 may completely enclose substrate 1212 as well as a portion of pedestal 1208 to create a region of high flow impedance during a deposition process.
Optionally, pedestal 1208 may be lowered and/or raised during portions the deposition process to modulate process pressure, reactant concentration, etc., within microvolume 1207. In one scenario where process chamber body 1202 remains at a base pressure during the deposition process, lowering pedestal 1208 may allow microvolume 1207 to be more efficiently evacuated. Example ratios of microvolume to process chamber volume include, but are not limited to, volume ratios between 1:1200 and 1:10. It will be appreciated that, in some embodiments, pedestal height may be adjusted programmatically by a suitable computer controller.
In another scenario, adjusting a height of pedestal 1208 may allow a plasma density to be varied during plasma activation and/or treatment cycles included in the deposition process. At the conclusion of the deposition process phase, pedestal 1208 may be lowered during another substrate transfer phase to allow removal of substrate 1212 from pedestal 1208.
While the example microvolume variations described herein refer to a height-adjustable pedestal, it will be appreciated that, in some embodiments, a position of showerhead 1206 may be adjusted relative to pedestal 1208 to vary a volume of microvolume 1207. Further, it will be appreciated that a vertical position of pedestal 1208 and/or showerhead 1206 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 1208 may include a rotational axis for rotating an orientation of substrate 1212. It will be appreciated that, in some embodiments, one or more of these example adjustments may be performed programmatically by one or more suitable computer controllers.
Returning to the embodiment shown in
In some embodiments, the plasma may be monitored in-situ by one or more plasma monitors. In one scenario, plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, plasma density and/or process gas concentration may be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters may be programmatically adjusted based on measurements from such in-situ plasma monitors. For example, an OES sensor may be used in a feedback loop for providing programmatic control of plasma power. It will be appreciated that, in some embodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.
In some embodiments, the plasma may be controlled via input/output control (IOC) sequencing instructions. In one example, the instructions for setting plasma conditions for a plasma process phase may be included in a corresponding plasma activation recipe phase of a deposition process recipe. In some cases, process recipe phases may be sequentially arranged, so that all instructions for a deposition process phase are executed concurrently with that process phase. In some embodiments, instructions for setting one or more plasma parameters may be included in a recipe phase preceding a plasma process phase. For example, a first recipe phase may include instructions for setting a flow rate of an inert and/or a reactant gas, instructions for setting a plasma generator to a power set point, and time delay instructions for the first recipe phase. A second, subsequent recipe phase may include instructions for enabling the plasma generator and time delay instructions for the second recipe phase. A third recipe phase may include instructions for disabling the plasma generator and time delay instructions for the third recipe phase. It will be appreciated that these recipe phases may be further subdivided and/or iterated in any suitable way within the scope of the present disclosure.
In some deposition processes, plasma strikes last on the order of a few seconds or more in duration. In certain implementations, much shorter plasma strikes may be used. These may be on the order of 10 ms to 1 second, typically, about 20 to 80 ms, with 50 ms being a specific example. Such very short RF plasma strikes require extremely quick stabilization of the plasma. To accomplish this, the plasma generator may be configured such that the impedance match is set preset to a particular voltage, while the frequency is allowed to float. Conventionally, high-frequency plasmas are generated at an RF frequency at about 13.56 MHz. In various embodiments disclosed herein, the frequency is allowed to float to a value that is different from this standard value. By permitting the frequency to float while fixing the impedance match to a predetermined voltage, the plasma can stabilize much more quickly, a result which may be important when using the very short plasma strikes associated with some types of deposition cycles.
In some embodiments, pedestal 1208 may be temperature controlled via heater 1210. Further, in some embodiments, pressure control for deposition process station 1200 may be provided by butterfly valve 1218. As shown in the embodiment of
As described above, two or more process stations may be included in a multi-station substrate processing tool.
The substrate processing apparatus 1300 of
Although not shown in
As shown in
The RF power is generated at an RF power system 1322 and distributed to each of the stations 1331, 1332, 1333, or 1334; similarly a DC power source 1326 is distributed to each of the station. The RF power system may include one or more RF power sources, e.g., a high frequency (HFRF) and a low frequency (LFRF) source, impedance matching modules, and filters. In certain implementations, the power source may be limited to only the high frequency or low frequency source. The distribution system of the RF power system may be symmetric about the reactor and may have high impedance. This symmetry and impedance result in approximately equal amounts of power being delivered to each station.
In some implementations, the controller 1338 is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller 1338, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.
Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.
The controller, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.
Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.
As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.
The controllers provided herein are configured to perform any of the techniques or processes provided herein, including having program instructions for executing any and all of the example techniques described herein. For example, a controller may be configured to cause a process gas to flow from a process gas supply through a process gas manifold towards the valve manifold, cause the first valve of the valve manifold to be in a closed state, and cause the second valve of the valve manifold to be in an open state to allow the process gas to flow to the showerhead and corresponding wafer, as illustrated in
A chuck 1417 is positioned within the lower sub-chamber 1403 near the bottom inner surface. The chuck 1417 is configured to receive and hold a semiconductor wafer 1419 upon which the etching process is performed. The chuck 1417 can be an electrostatic chuck for supporting the wafer 1419 when present. In some embodiments, an edge ring (not shown) surrounds chuck 1417, and has an upper surface that is approximately planar with a top surface of a wafer 1419, when present over chuck 1417. The chuck 1417 also includes electrostatic electrodes for chucking and dechucking the wafer. A filter and DC clamp power supply (not shown) may be provided for this purpose. Other control systems for lifting the wafer 1419 off the chuck 1417 can also be provided. The chuck 1417 can be electrically charged using an RF power supply 1423. The RF power supply 1423 is connected to matching circuitry 1421 through a connection 1427. The matching circuitry 1421 is connected to the chuck 1417 through a connection 1425. In this manner, the RF power supply 1423 is connected to the chuck 1417.
A coil 1433 is positioned above window 1411. The coil 1433 is fabricated from an electrically conductive material and includes at least one complete turn. The exemplary coil 1433 shown in
Process gases may be supplied through a main injection port 1460 positioned in the upper chamber and/or through a side injection port 1470, sometimes referred to as an STG. A vacuum pump, e.g., a one or two stage mechanical dry pump and/or turbomolecular pump 1440, may be used to draw process gases out of the process chamber and to maintain a pressure within the process chamber 1400 by using a closed-loop-controlled flow restriction device, such as a throttle valve (not shown) or a pendulum valve (not shown), during operational plasma processing.
The apparatus 1400 may therefore include a gas delivery system that a process gas source, a purge gas source, a divert and the apparatus 101 provided above that includes the valve manifold, first, second, and third valves, and other features described herein. The manifold outlet of this apparatus 101 is seen fluidically connected to the main injection port 1460, the process gas is seen fluidically connected to the process gas inlet, the purge gas is fluidically connected to the purge gas inlet, and the divert outlet is fluidically connected to the divert flowpath as described herein. The purge gas and process gas are configured to flow to the main injection port 1460, and be controlled, as described herein.
During operation of the apparatus, one or more reactant gases may be supplied through injection ports 1460 and/or 1470. In certain embodiments, gas may be supplied only through the main injection port 1460, or only through the side injection port 1470. In some cases, the injection ports may be replaced by showerheads. The Faraday shield 1449 and/or optional grid 1450 may include internal channels and holes that allow delivery of process gases to the chamber. Either or both of Faraday shield 1449 and optional grid 1450 may serve as a showerhead for delivery of process gases.
Radio frequency power is supplied from the RF power supply 1441 to the coil 1433 to cause an RF current to flow through the coil 1433. The RF current flowing through the coil 1433 generates an electromagnetic field about the coil 1433. The electromagnetic field generates an inductive current within the upper sub-chamber 1402. The physical and chemical interactions of various generated ions and radicals with the wafer 1419 selectively etch features of the wafer.
If the plasma grid 1450 is used such that there is both an upper sub-chamber 1402 and a lower sub-chamber 1403, the inductive current acts on the gas present in the upper sub-chamber 1402 to generate an electron-ion plasma in the upper sub-chamber 1402. The optional internal plasma grid 1450, if present, may act to limit the number of hot electrons in the lower sub-chamber 1403. In some embodiments, the apparatus is designed and operated such that the plasma present in the lower sub-chamber 1403 is an ion-ion plasma. In other embodiments, the apparatus may be designed and operated such that the plasma present in the lower sub-chamber 1403 is an electron-ion plasma. Internal plasma grids and ion-ion plasma are further discussed in U.S. patent application Ser. No. 14/082,009, filed Nov. 15, 2013, and titled “INTERNAL PLASMA GRID FOR SEMICONDUCTOR FABRICATION,” and in U.S. Pat. No. 9,245,761, each of which is herein incorporated by reference in its entirety.
Volatile etching byproducts may be removed from the lower-sub chamber 1403 through port 1422. The chuck 1417 disclosed herein may operate at elevated temperatures ranging between about 30° C. and about 250° C. In some cases, the chuck 1417 may also operate at lower temperatures, for example when the chuck 1417 is actively chilled. In such cases the chuck 1417 may operate at substantially lower temperatures, as desired. The temperature will depend on the etching process operation and specific recipe. In some embodiments, the chamber 1401 may operate at pressures in the range of between about 1 mTorr and about 95 mTorr. In certain embodiments, the pressure may be higher.
Chamber 1401 may be coupled to facilities (not shown) when installed in a clean room or a fabrication facility. Facilities include plumbing that provide processing gases, vacuum, temperature control, and environmental particle control. These facilities are coupled to chamber 1401, when installed in the target fabrication facility. Additionally, chamber 1401 may be coupled to a transfer chamber that allows robotics to transfer semiconductor wafers into and out of chamber 1401 using typical automation.
In some embodiments, a system controller 1430 (which may include one or more physical or logical controllers) controls some or all of the operations of an etching chamber. The system controller 1430 may include one or more memory devices and one or more processors. The processor may include a central processing unit (CPU) or computer, analog and/or digital input/output connections, stepper motor controller boards, and other like components. Instructions for implementing appropriate control operations are executed on the processor. These instructions may be stored on the memory devices associated with the system controller 1430 or they may be provided over a network. In certain embodiments, the system controller 1430 executes system control software.
In some cases, the system controller 1430 controls gas concentration, wafer movement, and/or the power supplied to the coils 1433 and/or electrostatic chuck 1417. The system controller 1430 may control the gas concentration by, for example, opening and closing relevant valves to produce one or more inlet gas stream that provide the necessary reactant(s) at the proper concentration(s). The wafer movement may be controlled by, for example, directing a wafer positioning system to move as desired. The power supplied to the coils 1433 and/or chuck 1417 may be controlled to provide particular RF power levels. Similarly, if the internal grid 1450 is used, any RF power applied to the grid may be adjusted by the system controller 1430.
The system controller 1430 may control these and other aspects based on sensor output (e.g., when power, potential, pressure, etc. reach a certain threshold), the timing of an operation (e.g., opening valves at certain times in a process), or based on received instructions from the user.
The multi-station tool 1500 also includes a fluid delivery system 1501, similar to
In
Each station in
The apparatus 1500 also includes a controller 1538 with one or more memories 1544 and one or more processors 1544 as provided herein. This controller 1538 is configured to control the operation of the apparatus 1500, including causing process gas to flow from the process gas source 1516 to each apparatus 101A-D and corresponding processing station 1531-1534, causing purge gas to flow from the process gas source 1518 to each apparatus 101A-D and corresponding processing station 1531-1534, the operation of each valve on the apparatus 101A-D, as well as to perform any of the techniques provide herein.
It is to be understood that the use of ordinal indicators, e.g., (a), (b), (c), . . . , herein is for organizational purposes only, and is not intended to convey any particular sequence or importance to the items associated with each ordinal indicator. For example, “(a) obtain information regarding velocity and (b) obtain information regarding position” would be inclusive of obtaining information regarding position before obtaining information regarding velocity, obtaining information regarding velocity before obtaining information regarding position, and obtaining information regarding position simultaneously with obtaining information regarding velocity. There may nonetheless be instances in which some items associated with ordinal indicators may inherently require a particular sequence, e.g., “(a) obtain information regarding velocity, (b) determine a first acceleration based on the information regarding velocity, and (c) obtain information regarding position”; in this example, (a) would need to be performed (b) since (b) relies on information obtained in (a)-(c), however, could be performed before or after either of (a) or (b).
Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.
Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.
Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.
A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/078262 | 10/18/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63262736 | Oct 2021 | US |
