A method for performing atomic layer etching (ALE) on a substrate

Abstract

The present invention relates to a method for performing atomic layer etching (ALE) on a substrate, which comprises the following operations: performing a surface modification operation on the surface of the substrate, the surface modification operation being configured to convert at least one monolayer of the substrate surface into a modified layer; performing a removal operation on the substrate surface, the removal operation being configured to remove the modified layer from the substrate surface, wherein removing the modified layer comprises exposing the substrate surface to a metal complex so that the ligand exchange reaction occurs between the metal complex and the converted substance of the modified layer; after the removal operation, performing plasma treatment on the substrate surface, the plasma treatment being configured to remove residues formed from the exposure of the substrate surface to the metal complex, wherein the residues are volatilized by the plasma treatment; repeating the aforementioned operations until a predetermined thickness has been etched from the substrate surface.

Description

[0001] This application is a divisional application of the application with application number 201710117229.7, application date March 1, 2017, and invention name “Atomic layer etching of AL2O3 using a combination of plasma and vapor treatment”. Technical Field

[0002] Implementations of the present disclosure relate to atomic layer etching (ALE), and more particularly to ALE of aluminum oxide using a combination of plasma and vapor treatments. Background Art

[0003] Conventional techniques for etching materials on semiconductor substrates by fine-tuning control of uniformity and etching rate are limited. For example, reactive ion etching is commonly used to etch materials on semiconductor substrates during semiconductor processing, and the etching rate of the material etched using reactive ion etching is controlled by adjusting the radio frequency plasma power and chemical selection. However, a wafer plasma sheath is formed on the top of the substrate, so ions from the plasma are usually accelerated onto the wafer surface to etch the substrate. This results in an anisotropic directional etching process that does not etch the vertical and horizontal surfaces of the material at the same rate. In addition, the material undergoing the conventional etching process may also be non-uniform. The use of conventional techniques generally involves specific reactor design and / or modification of feed gas delivery and exhaust, as well as careful monitoring of the temperature distribution of both the chamber or reactor wall and the electrostatic chuck, which can be part of a wafer holder capable of holding the wafer during processing to achieve high etching rate uniformity control, and it can result in lower efficiency and higher cost of substrate processing. Summary of the invention

[0004] According to some implementation schemes, a method for performing atomic layer etching (ALE) on a substrate is provided, comprising: (a) performing a surface modification operation on the surface of the substrate, the surface modification operation being configured to convert at least one monolayer of the substrate surface into a modified layer; (b) performing a removal operation on the substrate surface, the removal operation being configured to remove the modified layer from the substrate surface, wherein the removal of the modified layer is performed by a ligand exchange reaction configured to volatilize the modified layer; (c) after the removal operation, performing a plasma treatment on the substrate surface, the plasma treatment being configured to remove residues generated by the removal operation from the substrate surface, wherein the residues are volatilized by the plasma treatment; and (d) repeating operations (a) to (c) until a predetermined thickness has been etched away from the substrate surface.

[0005] In some implementations, performing the surface modification operation includes exposing the substrate surface to a fluorine-containing plasma, wherein the exposure to the fluorine-containing plasma is configured to convert the at least one monolayer of the substrate surface to a fluoride.

[0006] In some implementations, the surface of the substrate comprises a metal, a metal oxide, a metal nitride, a metal phosphide, a metal sulfide, or a metal arsenide; wherein the exposure to the fluorine-containing plasma forms a metal fluoride.

[0007] In some implementations, exposing the surface of the substrate to the fluorine-containing plasma includes introducing a fluorine-containing gas into a chamber within which the substrate is disposed, and igniting a plasma.

[0008] In some implementations, the exposing to the fluorine-containing plasma is performed at a chamber pressure of about 10 mTorr to 500 mTorr for a duration of less than about 15 seconds.

[0009] In some implementations, performing the removal operation includes exposing the substrate surface to tin(II) acetylacetonate (Sn(acac)2) vapor, wherein the exposure to the Sn(acac)2 vapor is configured to exchange acac ligands with fluorine atoms in the modified layer.

[0010] In some implementations, exposing the surface of the substrate to the Sn(acac)2 includes introducing the Sn(acac)2 as a vapor into a chamber within which the substrate is disposed.

[0011] In some implementations, the exposure to the Sn(acac)2 is performed for a duration of about 1 second to 30 seconds.

[0012] In some implementations, performing the plasma treatment includes exposing the substrate surface to a hydrogen plasma, wherein the exposure to the hydrogen plasma is configured to volatilize tin, tin fluoride, or tin oxide residues on the surface of the substrate.

[0013] In some implementations, exposing the surface of the substrate to the hydrogen plasma includes introducing hydrogen gas into a chamber within which the substrate is disposed, and igniting a plasma.

[0014] In some implementations, the duration of the exposure to the hydrogen plasma is about 1 to 30 seconds, typically about 5 seconds.

[0015] In some implementations, operation (a) is performed in a first chamber; and operation (b) is performed in a second chamber.

[0016] In some implementations, operation (d) is performed in the first chamber.

[0017] In some implementations, operation (d) is performed in a third chamber.

[0018] According to some implementation schemes, a method for performing atomic layer etching (ALE) on a substrate is provided, comprising: (a) performing a surface modification operation on the surface of the substrate, the surface modification operation being configured to convert at least one monolayer of the substrate surface into a modified layer; (b) performing a removal operation on the substrate surface, the removal operation being configured to remove the modified layer from the substrate surface, wherein the removal of the modified layer is performed by a ligand exchange reaction configured to volatilize the modified layer; (c) repeating operations (a) and (b) for a predetermined number of cycles; (d) after operation (c), performing plasma treatment on the substrate surface, the plasma treatment being configured to remove residues generated by the removal operation from the substrate surface, wherein the residues are volatilized by the plasma treatment; and (e) repeating operations (a) to (d) until a predetermined thickness is etched away from the substrate surface.

[0019] In some implementations, performing the surface modification operation includes exposing the substrate surface to a fluorine-containing plasma, wherein the exposure to the fluorine-containing plasma is configured to convert the at least one monolayer on the substrate surface into a fluoride; wherein performing the removal operation includes exposing the substrate surface to tin(II) acetylacetonate (Sn(acac)2) vapor, wherein the exposure to the Sn(acac)2 vapor is configured to exchange fluorine atoms in the modified layer with acac ligands; wherein performing the plasma treatment includes exposing the substrate surface to a hydrogen plasma, wherein the exposure to the hydrogen plasma is configured to volatilize tin, tin fluoride, or tin oxide residues on the surface of the substrate.

[0020] In some implementations, the surface of the substrate comprises a metal, a metal oxide, a metal nitride, a metal phosphide, a metal sulfide, or a metal arsenide; wherein the exposure to the fluorine-containing plasma forms a metal fluoride.

[0021] In some implementations, the exposure to the fluorine-containing plasma is performed for a duration of less than about 15 seconds at a chamber pressure of about 10 mTorr to 500 mTorr; wherein the exposure to the Sn(acac)2 is performed for a duration of about 1 to 30 seconds, typically about 1 second; and wherein the exposure to the hydrogen plasma is performed for a duration of about 1 to 30 seconds, typically about 5 seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figures 1A-1F An ALE process sequence is conceptually illustrated according to an embodiment of the present disclosure.

[0023] Figure 2 An implementation according to the present disclosure shows a method for ALE cycling.

[0024] Figure 3 A process flow chart of a method for performing ALE is shown according to an implementation of the present disclosure.

[0025] Figure 4 Implementations according to the present disclosure conceptually illustrate an apparatus having multiple chambers for performing ALE operations.

[0026] Figure 5 according to Figure 3 An embodiment of FIG. 1 shows a method, but wherein the fluorine exposure and Sn(acac) 2 exposure are repeated according to an implementation of the present disclosure until n cycles have been reached.

[0027] Figure 6 A cluster tool 600 is shown in accordance with an implementation of the present disclosure.

[0028] Figure 7 An exemplary chamber for performing ALE is shown in accordance with implementations of the present disclosure.

[0029] Figure 8 According to an implementation scheme of the present disclosure, a control module for controlling the above system is shown. DETAILED DESCRIPTION

[0030] In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments presented. The disclosed embodiments may be practiced without some or all of these specific details. In other cases, well-known processing operations are not described in detail so as not to unnecessarily obscure the disclosed embodiments. Although the disclosed embodiments will be described in conjunction with specific embodiments, it should be understood that they are not intended to limit the disclosed embodiments.

[0031] Provided herein is a method for isotropic atomic layer etching (ALE) of metal oxides, such as aluminum oxide (Al2O3), by a ligand exchange mechanism involving a fluorine-containing plasma and a tin-containing etchant. The method described herein involves modifying the surface of the material to be etched using a fluorine-containing plasma and exposing the modified surface to tin (II) acetylacetonate (Sn(acac)2) vapor to remove the material in a self-limiting manner. The ligand exchange reaction is maintained in a vapor deposition chamber with Sn(acac)2 vapor in the absence of a plasma.

[0032] Atomic layer etching (ALE) is a method for atomic-level control of etching performance. ALE is a cyclic process. ALE is a technique for removing thin layers of material using sequential self-limiting reactions. In general, ALE can be performed using any suitable technique. Examples of atomic layer etching techniques are described in U.S. Patent No. 8,883,028, issued on November 11, 2014; and U.S. Patent No. 8,808,561, issued on August 19, 2014, which are incorporated herein by reference for the purpose of describing exemplary atomic layer etching and etching techniques. In various embodiments, ALE can be performed with plasma, or can be performed with thermal methods.

[0033] ALE can be accomplished by a surface modification operation (i.e., chemical adsorption by reactive chemicals on the substrate surface) followed by a removal operation. Such an operation can be repeated for a specific number of cycles. During ALE, reactive chemicals and removal chemicals are delivered to the substrate separately.

[0034] Figures 1A-1F An ALE process sequence according to an implementation of the present disclosure is conceptually illustrated.

[0035] Figure 1A A portion of a substrate surface 100 is shown in an unmodified state. The outermost layer 102 of molecules / atoms of the substrate surface 100 is exposed for the ALE process. Figure 1B As shown, a surface conversion / modification operation is performed to convert the surface layer of the substrate to a functionalized state. For example, the surface layer is modified by exposure to a surface conversion reactant 104, which can be adsorbed or chemisorbed on the surface. In various implementations, the surface conversion reactant can include molecules or low-energy free radicals that react with the surface layer atoms to achieve the surface conversion step. The resulting surface layer is shown in Figure 1C , which consists of a functionalized outermost layer 106 of molecules to enable subsequent ALE steps. Since the reaction is self-limiting, only (or substantially only) the outermost layer of the substrate surface will undergo transformation. In some implementations, the surface modification requires conversion of the surface species to halides. In some implementations, after the self-limiting surface transformation, the chamber is swept to remove any reaction byproducts or excess surface transformation reactants.

[0036] After the surface conversion operation, then Figure 1DIn the illustrated implementation, the modified surface 106 of the substrate is exposed to a ligand-containing reactant 108, thereby effecting a ligand exchange reaction, wherein the ligand-containing reactant adsorbs on the substrate surface and transfers its ligand to the converted surface species 106 formed during an earlier surface modification / conversion operation. The ligands bond to the modified surface layer of molecules / atoms, thereby forming a ligand-containing reactant 108. Figure 1E The reaction product shown consists of a ligand-substituted surface substance 110, which can be released.

[0037] like Figure 1F As shown, desorption drives the removal of the outermost layer of surface material 110 (reaction products after the ligand exchange operation) from the substrate surface. In some implementations, release can be achieved by applying thermal energy, which can be applied simultaneously with exposure to the ligand-containing reactant or in a separate step.

[0038] The concept of an "ALE cycle" is relevant to the discussion of various embodiments herein. In general, an ALE cycle is a minimum set of operations for performing an etching process once (e.g., etching a single layer). The result of one cycle is that at least some of the film layer on the surface of the substrate is etched away. In general, an ALE cycle includes a modification operation to form a reaction layer, followed by a removal operation to remove or etch away only the modified layer. The modification can be performed using a chemical adsorption mechanism, a deposition mechanism, a top layer conversion mechanism, or an extraction mechanism. The cycle may include certain auxiliary operations, such as sweeping one of the reactants or byproducts. In general, a cycle contains an instance of a unique sequence of operations. For example, Figure 2 A method for an ALE cycle is shown, which includes the following operations: (i) delivering a reactant gas (operation 201), (ii) optionally purging a reactant gas from a chamber (operation 203), (iii) delivering a removal gas and optionally a plasma (operation 205), and (iv) optionally purging the chamber (operation 207). Further description and examples of ALE are described in U.S. Patent Application No. 14 / 696,254, filed on April 24, 2015, entitled "INTEGRATING ATOMIC SCALE PROCESSES: ALD (ATOMIC LAYER DEPOSITION) AND ALE (ATOMIC LAYER ETCH)," which is incorporated herein by reference for the purpose of describing atomic layer etching processes.

[0039] exist Figure 3 A process flow diagram of a method performed according to the disclosed embodiments is provided in During operations 301-307, an inert gas such as argon may flow continuously in the background as a carrier gas.

[0040] In operation 301, a substrate including a material to be etched is exposed to a fluorine-containing plasma to modify a surface of the substrate.

[0041] The fluorine-containing plasma can be generated by introducing a fluorine-containing gas and igniting the plasma. For example, in some embodiments, the fluorine-containing gas can be carbon tetrafluoride (CF4), nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), fluorine (F2), or any fluorine-containing gas. In various embodiments, CF4 can be introduced with O2 to produce a large amount of fluoride ions in the plasma to etch the substrate. In some embodiments, about 35% of the total gas flow rate to the chamber for generating the fluorine-containing plasma is O2 gas. In some embodiments, other fluorine-containing gases including carbon can be used when introduced with another gas to suppress carbides. For example, other fluorine-containing gases can have the formula C x H y F z , where x can be any integer greater than or equal to 1, y can be any integer greater than or equal to 0, and z can be any integer greater than or equal to 1. Examples include fluoroform (CHF3) and difluoromethane (CH2F2). In some embodiments, the fluorine-containing gas can be produced by gasifying a fluorine-containing liquid.

[0042] In some embodiments, the substrate is not patterned. In various embodiments, the substrate may be patterned. The substrate may include a transistor structure that may include an additional gate layer such as a blocking oxide or an etch stop layer. For example, the substrate may include an aluminum oxide layer above the fin of a FinFET transistor. In some embodiments, the substrate may include a 3D NAND structure in which a metal oxide etch stop layer is formed at the bottom of a trench in the structure such that the metal oxide etch stop layer is the material to be etched. In various embodiments, features on the substrate may have an aspect ratio between about 1.5:1 and about 5:1.

[0043] The plasma in operation 301 may be generated in situ or may be a remote plasma. In many embodiments, the plasma is generated in situ to produce an inductively coupled plasma.

[0044] In various embodiments, the substrate includes a metal oxide, metal nitride, metal phosphide, metal sulfide, metal arsenide, or metal layer to be etched. Examples include aluminum oxide (Al2O3) and hafnium oxide. Note that in many embodiments, the disclosed embodiments may not be used to etch silicon-containing materials (e.g., silicon oxide, silicon nitride, silicon carbide, silicon, etc.), which helps achieve etch selectivity, particularly when etching materials such as sacrificial gate oxide layers above fins on FinFET transistor structures. It should be understood that while the disclosed embodiments can be used to etch a variety of materials, Figure 1A-1FIt will be described with reference to etching aluminum oxide.

[0045] In various embodiments, operation 301 may be performed without applying a bias so as to enable the substrate surface to be modified isotropically. Note that while the disclosed embodiments may be used to perform isotropic etching, the disclosed embodiments may also be used to perform an anisotropic etching process by applying a bias during operation 301. The etching described herein with reference to FIG. Figure 1A-1F Examples described.

[0046] Without being bound by a particular theory, during operation 301, a metal oxide surface (e.g., an aluminum oxide surface) can be isotropically fluorinated by a fluorine-containing plasma to modify the surface of the aluminum oxide to form aluminum fluoride (e.g., AlF3). One or more monolayers of the aluminum oxide surface can be modified to form aluminum fluoride. The modification operation can be limited by the diffusion depth. The substrate can be exposed to the fluorine-containing plasma at a chamber pressure between about 10 mTorr and about 100 mTorr, such as about 20 mTorr, for a duration of less than about 15 seconds, but more than 0 seconds.

[0047] Note that in some embodiments, the chamber housing the substrate may not be purged after performing operation 301. In some embodiments, the substrate may be purged.

[0048] In operation 303, the substrate is exposed to tin(II) acetylacetonate (Sn(acac)2) vapor. In various embodiments, Sn(acac)2 can be vaporized in an external vaporizer before delivering the vapor to the substrate.

[0049] Without being bound by a particular theory, it is believed that when the modified AlF3 surface is exposed to Sn(acac)2 vapor, a ligand exchange reaction occurs, causing one acac ligand on Sn(acac)2 to replace one fluorine atom on the AlF3 molecule, thereby forming AlF2(acac). Additional Sn(acac)2 and / or Sn(acac) can then react with AlF2(acac) twice more to replace the second and third fluorine atoms with (acac), thereby obtaining Al(acac)3 that is volatile and can therefore be etched away from the substrate. Since the ligand exchange reaction is theoretically derived to have a faster etching rate in the top monolayer of AlF3 (e.g., the first monolayer exposed to Sn(acac)2 vapor), the reaction is self-limiting, and some tin, tin fluoride, tin oxide, and Sn(acac)2 will begin to accumulate on the surface of the material to be etched, thereby blocking further etching of any modified AlF3 bottom layer.

[0050] In various embodiments, operations 301 and 303 can be performed in the same chamber. In operation 303, the plasma is turned off, and the fluorine-containing gas flow can be turned off before the vapor flow is turned on. Without purging the chamber prior to operation 303, the presence of the fluorine-containing gas without the plasma does not affect the etching mechanism. Instead, the separate fluorine-containing gas can be selected so that it does not react as a gas with the material to be etched, and does not react with the vapor used in operation 303.

[0051] In some embodiments, operations 301 and 303 can be performed in separate chambers of the same apparatus. Figure 4 An apparatus having multiple chambers for performing ALE operations is conceptually illustrated according to an embodiment of the present disclosure. In various embodiments, a substrate can be shuttled or moved between a first chamber 401 for exposure to a fluorine-containing plasma in operation 301 and a second chamber 403 for exposure to Sn(acac)2 vapor. In some embodiments, the second chamber 403 is a vapor deposition chamber. In some embodiments, the second chamber 403 is a modification chamber that does not include a plasma source. Note that the movement or shuttle motion of the substrate between chambers can be performed without breaking the vacuum.

[0052] In an alternative embodiment, the substrate may be exposed to another gas phase chemical that is selective for the metal fluoride but does not react with the metal oxide. The chemical may include one or more ligands that, when reacting with the metal fluoride, produce a volatile compound including the metal bonded to the ligand.

[0053] Operation 303 may be performed for a duration of about 1 second, wherein the temperature of the wafer holder or susceptor holding the wafer is set to a temperature of about 200° C. In various embodiments, the chamber pressure at the end of the exposure to Sn(acac) 2 vapor may be about 20 mTorr.

[0054] In operation 305, the substrate may be exposed to plasma treatment. Without being bound by a particular theory, it is believed that operation 305 is performed to volatilize the tin, tin fluoride, or tin oxide accumulation on the substrate surface that may have accumulated in performing operation 303. Exposing the substrate to hydrogen will form hydrated tin that is volatile at the selected substrate temperature, which can then be pumped away from the processing chamber. The substrate may be exposed to plasma treatment for a duration of more than 0 seconds and less than 5 seconds. The duration of plasma exposure may depend on the amount of tin on the surface. For example, in some embodiments, the amount of tin can be determined by evaluating the tin line in the emission spectrum. In some embodiments, the plasma may be turned off when the tin line in the emission spectrum disappears. In some embodiments, the substrate is exposed to plasma for about 5 seconds. In some embodiments, the substrate is exposed to plasma for a duration longer than about 5 seconds. In various embodiments, plasma treatment may include introducing hydrogen and igniting plasma. Operation 305 may be performed in the same chamber as the chambers of operations 301 and 303. Note that although operation 305 can be performed by exposing the substrate to a hydrogen plasma, in some embodiments, a different chemistry can be used to remove tin or tin oxide accumulation on the surface of the material to be etched. For example, in some embodiments, an ammonia (NH3) plasma can be used.

[0055] In some embodiments, operation 305 can be performed in separate chambers. For example, in some embodiments, the substrate can be moved to or shuttled to a first station / chamber 401 where operation 301 is performed, or can be moved to or shuttled to a third station / chamber 405 to perform operation 305. Note that the movement or shuttle of the substrate between chambers can be performed without breaking vacuum.

[0056] In operation 307, it is determined whether the amount etched is sufficient to achieve the desired amount to be etched. If the desired remaining thickness has not been reached, operations 301-305 can be optionally repeated. Note that in some embodiments, operation 305 can be performed only in every n cycles of performing operations 301 and 303, where n is an integer greater than or equal to 1. If n is 1, operation 305 is performed in each cycle. In various embodiments, operation 305 is performed in each cycle. In another example, if n is 2, operation 305 can be performed in every 2 cycles of performing operations 301 and 303, so that the following operations can be performed to etch the substrate: (1) exposure to fluorine-containing plasma, (2) exposure to Sn(acac)2 vapor, (3) exposure to fluorine-containing plasma, (4) exposure to Sn(acac)2 vapor, (5) exposure to hydrogen plasma, and (6) repeating (1)-(5).

[0057] Figure 5 according to Figure 3The embodiment of FIG. 5 shows a method, but in which the fluorine exposure (operation 501) and the Sn(acac)2 exposure (operation 503) are repeated until n cycles have been reached (operation 505). Then, a hydrogen plasma exposure is performed (operation 507). The entire sequence is repeated until the desired etching amount is reached (operation 509).

[0058] The disclosed embodiments result in a highly controlled etching process with high uniformity. The disclosed embodiments can be used to perform isotropic etching of a variety of materials and can also be modified to perform isotropic etching of a variety of materials by applying a voltage of approximately 20V. b and about 80V b Between (e.g. about 50V b ) to perform anisotropic etching.

[0059] Various embodiments described herein can be performed in a plasma etch chamber, such as the Kiyo available from Lam Research Corporation (Fremont, CA). In various embodiments, the substrate can be shuttled between the etch chamber and the vapor chamber without breaking vacuum.

[0060] The disclosed embodiments may be performed in any suitable chamber or apparatus, such as in or Flex, both available from Lam Research Corporation (Fremont, CA). In some embodiments, the disclosed embodiments may be implemented in a cluster tool, which may include one or more stations. Figure 6 A cluster tool 600 is shown according to an implementation of the present disclosure. In various embodiments, one station 601 may include a module for etching, while another station 603 includes a module for exposure to vapor (eg, a vapor chamber). In some embodiments, a third station 605 includes a module for exposure to plasma.

[0061] In some embodiments, an inductively coupled plasma (ICP) reactor may be used. Such an ICP reactor has also been described in U.S. Patent Application Publication No. 2014 / 0170853, filed on December 10, 2013, entitled “IMAGE REVERSAL WITH AHM GAP FILL FORMULTIPLE PATTERNING,” which is incorporated herein by reference for describing a suitable ICP reactor for implementing the techniques described herein. Although an ICP reactor is described herein, it should be understood that in some embodiments, a capacitively coupled plasma reactor may also be used. References Figure 7, an exemplary etching chamber or apparatus may include a chamber 701 having: a showerhead or nozzle 703 for distributing a fluorine-containing gas (705), hydrogen (707), or Sn(acac)2 vapor (709) or other chemical into the chamber 701; a chamber wall 711; a chuck 713 for holding a substrate or wafer 715 to be processed, which may include an electrostatic electrode for clamping and releasing the wafer and may be powered using an RF power supply 717; an RF power supply 719 configured to power a coil 721 to generate a plasma; and a gas flow inlet for inputting a gas as described herein. In various embodiments, the chamber wall 711 may be fluorine-resistant. For example, the chamber wall 711 may be coated with a silicon-containing material (e.g., silicon or silicon oxide) or a carbon-containing material (e.g., diamond) or a combination thereof, so that the fluorine-containing gas and / or plasma may not etch the chamber wall 711. Modifying chemical gases for chemical adsorption (e.g., fluorine-containing gases for generating fluorine-containing plasmas) and / or vapor exposure (e.g., Sn(acac)2) can flow into chamber 701. In some embodiments, hydrogen gas 707 can flow into the chamber to generate a hydrogen plasma for removing tin or tin oxide residues. In some embodiments, the chamber walls are heated to support wall cleaning efficiency using hydrogen plasma. In some embodiments, the device may include more than one chamber, each of which can be used to etch, deposit, or process a substrate. The chamber or device may include a system controller 723 for controlling some or all operations of the chamber or device, such as adjusting chamber pressure, inert gas flow, plasma power, plasma frequency, reactant gas flow (e.g., fluorine-containing gas, Sn(acac)2 vapor, etc.); bias power, temperature, vacuum settings; and other process conditions.

[0062] Figure 8 A control module 800 for controlling the above-mentioned system is shown according to an implementation scheme of the present disclosure. For example, the control module 800 may include a processor, a memory, and one or more interfaces. The control module 800 may be used to control a device in a system based in part on a sensed value. For example only, the controller 800 may control one or more of a valve 802, a filter heater 804, a pump 806, and other devices 808 based on sensed values ​​and other control parameters. For example only, the control module 800 receives sensed values ​​from a pressure gauge 810, a flow meter 812, a temperature sensor 814, and / or other sensors 816. The control module 800 may also be used to control process conditions during reactant delivery and plasma treatment. The control module 800 will typically include one or more memory devices and one or more processors.

[0063] The control module 800 can control the activities of the reactant delivery system and the plasma treatment device. The control module 800 executes a computer program, which includes other parameters for controlling process timing, delivery system temperature, pressure difference across the filter, valve position, gas mixture, chamber pressure, chamber temperature, wafer temperature, RF power level, wafer ESC or susceptor position and specific process. The control module 800 can also monitor the pressure difference and automatically switch the vapor reactant delivery from one or more paths to one or more other paths. Other computer programs stored on the memory device associated with the control module 800 can be adopted in some embodiments.

[0064] Typically, there will be a user interface associated with the control module 800. The user interface may include a display 818 (e.g., a display screen and / or graphical software display of device and / or process conditions), and a user input device 820 (e.g., a pointing device, keyboard, touch screen, microphone, etc.).

[0065] Computer programs for controlling the delivery of reactants, plasma treatment, and other processes in a process sequence can be written in any conventional computer-readable programming language (e.g., assembly language, C, C++, Pascal, Fortran, or others). The compiled object code or script is executed by a processor to perform the tasks identified in the program.

[0066] Control module parameters relate to process conditions such as, for example, filter pressure differential, process gas composition and flow rate, temperature, pressure, plasma conditions (eg, RF power level and low frequency RF frequency), cooling gas pressure, and chamber wall temperature.

[0067] The system software can be designed or configured in many different ways. For example, various chamber component subroutines or control objects can be written to control the operation of the chamber components required to perform the deposition process of the present invention. Examples of programs or program segments for this purpose include substrate positioning code, process gas control code, pressure control code, heater control code, and plasma control code.

[0068] Although the foregoing embodiments have been described in considerable detail for the purpose of clarity of understanding, it will be apparent that certain changes and modifications may be implemented within the scope of the disclosed embodiments. It should be noted that there are many alternative ways of implementing the processes, systems, and devices of the present embodiments. Therefore, the embodiments of the present invention are to be considered illustrative rather than restrictive, and the embodiments are not to be limited to the details given herein.

Claims

1. A method for performing atomic layer etching (ALE) on a substrate, comprising: (a) performing a surface modification operation on the surface of the substrate, the surface modification operation being configured to convert at least one monolayer of the substrate surface into a modified layer; (b) performing a removal operation on the substrate surface, the removal operation being configured to remove the modified layer from the substrate surface, wherein removing the modified layer comprises exposing the substrate surface to a metal complex so that a ligand exchange reaction occurs between the metal complex and a converted substance of the modified layer; (c) performing a plasma treatment on the substrate surface after the removing operation, the plasma treatment being configured to remove residues formed from the substrate surface exposed to the metal complex, wherein the residues include metal elements in the metal complex and are volatilized by the plasma treatment; (d) Repeating operations (a) to (c) until a predetermined thickness has been etched from the substrate surface. 2 . The method of claim 1 , wherein the surface of the substrate comprises a metal, a metal oxide, a metal nitride, a metal phosphide, a metal sulfide, or a metal arsenide.

3. The method of claim 1, wherein performing the surface modification operation comprises exposing the substrate surface to a halogen-containing plasma, wherein the exposure to the halogen-containing plasma is configured to convert the at least one monolayer of the substrate surface to a halide. 4 . The method of claim 3 , wherein exposing the surface of the substrate to the halogen-containing plasma comprises introducing a halogen-containing gas into a chamber within which the substrate is disposed, and igniting a plasma. 5 . The method of claim 3 , wherein exposing the surface of the substrate to the halogen-containing plasma comprises receiving the halogen-containing plasma from a remote plasma source.

6. The method of claim 1, wherein performing the removal operation comprises exposing the substrate surface to tin(II) acetylacetonate (Sn(acac)2) vapor, wherein the exposure to the tin(II) acetylacetonate vapor is configured to exchange acac ligands with atoms in the modified layer.

7. The method of claim 1, wherein performing the plasma treatment comprises exposing the substrate surface to a hydrogen plasma.

8. The method of claim 1, wherein exposing the surface of the substrate to the plasma comprises introducing hydrogen gas into a chamber within which the substrate is disposed, and igniting a plasma.

9. The method of claim 7, wherein exposing the substrate surface to the hydrogen plasma comprises receiving the hydrogen plasma from a remote plasma source.

10. The method according to claim 1, wherein operation (a) is performed in the first chamber; Wherein operation (b) is performed in the second chamber.

11. A method for performing atomic layer etching (ALE) on a substrate, comprising: (a) performing a surface modification operation on the surface of the substrate, the surface modification operation being configured to convert at least one monolayer of the substrate surface into a modified layer; (b) performing a removal operation on the substrate surface, the removal operation being configured to remove the modified layer from the substrate surface, wherein removing the modified layer comprises exposing the substrate surface to a metal complex so that a ligand exchange reaction occurs between the metal complex and a converted substance of the modified layer; (c) repeating operations (a) and (b) for a predetermined number of cycles; (d) after the operation (c), performing a plasma treatment on the surface of the substrate, the plasma treatment being configured to remove residues formed from the surface of the substrate exposed to the metal complex, wherein the residues include metal elements in the metal complex and are volatilized by the plasma treatment; (e) Repeating operations (a) to (d) until a predetermined thickness has been etched from the substrate surface.

12. The method of claim 11, wherein the surface of the substrate comprises a metal, a metal oxide, a metal nitride, a metal phosphide, a metal sulfide, or a metal arsenide.

13. The method of claim 11, wherein performing the surface modification operation comprises exposing the substrate surface to a halogen-containing plasma, wherein the exposure to the halogen-containing plasma is configured to convert the at least one monolayer of the substrate surface to a halide.

14. The method of claim 13, wherein exposing the surface of the substrate to the halogen-containing plasma comprises introducing a halogen-containing gas into a chamber within which the substrate is disposed, and igniting a plasma.

15. The method of claim 13, wherein exposing the surface of the substrate to the halogen-containing plasma comprises receiving the halogen-containing plasma from a remote plasma source.

16. The method of claim 11, wherein performing the removal operation comprises exposing the substrate surface to tin(II) acetylacetonate (Sn(acac)2) vapor, wherein the exposure to the tin(II) acetylacetonate vapor is configured to exchange acac ligands with atoms in the modified layer.

17. The method of claim 11, wherein performing the plasma treatment comprises exposing the substrate surface to a hydrogen plasma.

18. The method of claim 11, wherein exposing the surface of the substrate to the plasma comprises introducing hydrogen gas into a chamber within which the substrate is disposed, and igniting a plasma.

19. The method of claim 17, wherein exposing the substrate surface to the hydrogen plasma comprises receiving the hydrogen plasma from a remote plasma source.

20. The method according to claim 11, wherein operation (a) is performed in the first chamber; Wherein operation (b) is performed in the second chamber.

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