Vapor phase etching with controllable metal etch selectivity

Abstract

A method for dry removal of material on a microelectronic workpiece is described. The method includes receiving a substrate having a working surface that exposes a metal layer and having at least one other material exposed to or beneath the metal layer; and differentially etching the metal layer relative to the other material by exposing the substrate to a controlled gas phase environment containing an anhydrous halogen compound.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to the following provisional application: U.S. Provisional Patent Application Serial No. 62 / 875,658, filed July 18, 2019, entitled “Gas Phase Etch with Controllable Etch Selectivity of Metals,” which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to an etching method, and more particularly to a dry non-plasma treatment system and method for chemical and thermal treatment of substrates. Background Technology

[0004] This disclosure relates to the fabrication of features in semiconductor devices, including fabrication through etching and deposition processes.

[0005] The fabrication of semiconductor devices is a multi-step process of forming structures (i.e., gates, contacts, interconnects, etc.) on a semiconductor substrate (wafer) or other substrates. These steps may include material growth, patterning, doping, deposition, etching, metallization, planarization, etc. Features formed on the substrate can include various transistors. Transistors can be planar or non-planar, and can have single or multiple gates.

[0006] Various etching processes benefit from the ability to etch one material relative to another, removing one material while the other largely remains on the substrate. For example, photoresist gets its name in part from the fact that it is a photosensitive material that resists etching by dry plasma etching processes. Photoresist materials are typically patterned into relief patterns, which are used as etching masks to allow the pattern to be transferred into one or more underlying materials.

[0007] Beyond the 10 nm technology node, the semiconductor device industry is moving towards gate-all-around (GAA) device architectures. A fundamental requirement for GAA implementation is the formation of silicon germanium (SiGe) and silicon (Si) nanowires (NW) or nanosheets (NS). The fabrication of these requires selective, isotropic, and precise metal etching processes when forming the metal contacts with the gate device. Summary of the Invention

[0008] The various materials used in semiconductor manufacturing exhibit varying degrees of etch resistance. In some manufacturing processes, high etch selectivity between two or more materials is desirable for different manufacturing steps. In other processes, a uniform etch rate is desired between two chemically different materials. Unfortunately, for a given pair of materials, the etching process may exhibit an undesirable etch rate ratio.

[0009] Metals, metalloids, amorphous silicon (a-Si), polycrystalline silicon (poly-Si), and single-crystal Si, along with silicon-germanium (Si-Ge, which is an alloy of silicon and germanium with different Si:Ge compositions), are widely used in various applications in the semiconductor industry. For sub-10 nm and above technology nodes, integrating Si-Ge as source-drain materials has shown potential to improve transistor electrical performance. The complex process flows for designing and manufacturing three-dimensional (3D) Si, Ge, and Si-Ge-based field-effect transistors (FETs) often present challenging requirements at different manufacturing stages. One challenge is the differential etching of metals relative to other materials present on the substrate, such as amorphous or crystalline silicon, silicon oxide, silicon nitride, silicon carbide, silicon-germanium alloys, hafnium oxide, or organic materials, or combinations thereof.

[0010] Embodiments of the present invention relate to a dry (e.g., vapor-phase), non-plasma (e.g., plasma-free) processing system and method for processing substrates, and more specifically to a dry non-plasma processing system and method for chemical and thermal treatment of substrates. Additional embodiments include differentiated, vapor-phase, non-plasma, isotropic etching of various materials. The techniques described herein provide dry isotropic and conformal etching of metals, including W, Ti, TiN, Ta, TaN, Ru, Co, or other transition metals, or combinations thereof.

[0011] According to one embodiment, an etching method is described. The method includes receiving a substrate having a working surface exposing a metal layer and having at least one other material exposed to or beneath the metal layer; and etching the metal layer differentially relative to the other material by exposing the substrate to a controlled gas phase environment containing anhydrous halogen compounds.

[0012] According to another embodiment, a method for etching is described. The method includes receiving a substrate having a working surface exposing a metal layer and having at least one other material exposed to or beneath the metal layer; and differentially removing at least a portion of the metal layer by: exposing the substrate surface to a chemical environment containing anhydrous halogen compounds at a first setpoint temperature to chemically alter a surface region of the metal layer, and then raising the temperature of the substrate to a second setpoint temperature to remove the chemically treated surface region of the metal layer.

[0013] Of course, for clarity, the order of discussion of the different steps described herein has been presented. Generally, these steps can be performed in any suitable order. Furthermore, although each different feature, technique, configuration, etc., in this disclosure may be discussed in different places, it is intended that each concept can be implemented independently of or in combination with each other. Therefore, the invention can be practiced and viewed in many different ways.

[0014] It should be noted that the Summary of this Exploration does not specify all embodiments and / or additional novel aspects of the invention disclosed herein or claimed. Rather, the Summary provides only a preliminary discussion of different embodiments and points of novelty compared to conventional techniques. For additional details and / or possible perspectives on the invention and embodiments, the reader should refer to the Detailed Description section of this Exploration and the accompanying drawings, as discussed further below. Attached Figure Description

[0015] In the attached diagram:

[0016] Figure 1A and 1B The device is depicted during the intermediate stages of manufacturing;

[0017] Figure 2 A flowchart illustrating an etching method according to an embodiment is provided;

[0018] Figure 3 A schematic illustration of a vapor phase etching system according to an embodiment is provided;

[0019] Figure 4 provides a schematic illustration of a heat treatment module according to an embodiment;

[0020] Figure 5 provides a schematic illustration of the chemical processing module according to an embodiment;

[0021] Figure 6 A schematic illustration of an etching system according to another embodiment is provided; and

[0022] Figure 7 A schematic diagram of a workpiece holder according to an embodiment is provided. Detailed Implementation

[0023] In the following description, specific details, such as the particular geometry of the machining system, the various components used therein, and the processes, are set forth for purposes of explanation and not limitation. However, it should be understood that the invention may be practiced in other embodiments that depart from these specific details.

[0024] Similarly, specific figures, materials, and configurations have been set forth for illustrative purposes in order to provide a thorough understanding of the invention. However, the invention may be practiced without specific details. Furthermore, it should be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.

[0025] The various operations will be described sequentially as a plurality of discrete operations in a manner most conducive to understanding the invention. However, the order of description should not be construed as meaning that these operations must be performed in that order. In particular, these operations need not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. In additional embodiments, various additional operations may be performed and / or the described operations may be omitted.

[0026] As used herein, the term “radiation-sensitive material” means and includes photosensitive materials, such as photoresists.

[0027] As used herein, the term "non-plasma" generally means that no plasma is formed in the space near the workpiece being processed (i.e., processing or handling the workpiece in a plasma-free environment). Although plasma products can be introduced into the environment near the workpiece from a remote location, the plasma is not actively generated by the electromagnetic field of the neighboring workpiece.

[0028] As used herein, “substrate” generally refers to the object being processed according to the invention. A substrate may include any material portion or structure of a device (particularly a semiconductor or other electronic device) and may be, for example, a base substrate structure (such as a semiconductor wafer) or a layer (such as a thin film) on or overlaid on a base substrate structure. A substrate may be a conventional silicon workpiece or other bulk workpiece comprising layers of semiconductor material. As used herein, the term “bulk substrate” refers to a silicon wafer and includes not only silicon wafers but also silicon-on-insulator (“SOI”) substrates (such as silicon-on-sapphire (“SOS”) and silicon-on-glass (“SOG”) substrates), silicon epitaxial layers on a base semiconductor substrate, and other semiconductor or optoelectronic materials (such as silicon-germanium, germanium, gallium arsenide, gallium nitride, and indium phosphide). Workpieces may be doped or undoped. Therefore, a substrate is not intended to be limited to any particular base structure, lower layer, or upper layer, whether patterned or unpatterned, but is contemplated to include any such layer or base structure, and any combination of layers and / or base structures. The following description may refer to specific types of workpieces, but is for illustrative purposes only and not for limiting purposes.

[0029] As mentioned above, advanced methods are needed to address these challenges and meet the requirements for erosive patterning at sub-30nm technology nodes. Furthermore, as also discussed, these methods present their own set of challenges, manifested in issues such as etch selectivity, rate, and contour control. The ability to successfully integrate patterning schemes with highly selective etching processes is crucial for robust pattern transfer.

[0030] As an example, once the circuit pattern is initially formed, the patterning material, whether it is a photosensitive material patterned using optical lithography, a mechanically imprinted patterned layer, or a directly self-assembled layer, acts as a protective layer that masks some areas of the semiconductor substrate, while other areas are exposed to allow the circuit pattern to be transferred to the underlying layer using dry etching processes such as plasma etching.

[0031] As previously mentioned, metals, metalloids, amorphous silicon (a-Si), polycrystalline silicon (poly-Si), and single-crystal Si, along with silicon-germanium (Si-Ge, which is an alloy of silicon and germanium with different Si:Ge compositions), are widely used in various applications in the semiconductor industry. For sub-10nm and below technology nodes, integrating Si-Ge as source-drain materials has shown potential to improve transistor electrical performance. Furthermore, W is a commonly used metal for metal contacts, using Ti or TiN, or combinations thereof, as metal pads. In various process steps, it is desirable to differentially remove at least a portion of the metal, including W, Ti, TiN, Ta, TaN, Ru, Co, or other transition metals, or combinations thereof.

[0032] Referring now to the accompanying drawings, in which the same reference numerals in all the views denote the same or corresponding parts. Figure 1A A cross-sectional view of the device is depicted during an intermediate stage of manufacturing. The device may include conductive contacts, such as metal contacts for transistors, like field-effect transistors (FETs) (e.g., pFETs or nFETs). As examples, the device may include planar (CMOS) FETs, finFETs, cFETs (complementary FETs), gate-all-around (GAA) FETs, nanowire FETs, or nanosheet FETs. Figure 1A A representative cross-section of the metal contact is provided. The device is formed on a substrate 100 and includes at least one film 101, such as silicon oxide (SiO2). x The exposed metal 102, such as W, Ru, or Co, and optionally, a metal liner 103, such as Ti or TiN. Using the process described herein, at least a portion of the metal layer 102 can be selectively removed relative to the underlying layers, such as film 101 and metal liner 103.

[0033] In another instance, Figure 1BA cross-sectional view of device 105 is depicted during an intermediate stage of manufacturing. Device 105 may include conductive contacts, such as metal contacts for a transistor, such as a GAA-FET. Device 105 may include a first set of nanosheet structures 110 and a second set of nanosheet structures 120. Multilayer materials may be conformally applied to the nanosheet structures, such as layer 111 (e.g., TiN) and at least one other material 112, 113, 114, such as a metal-containing layer 112 (e.g., TaN), a gate dielectric layer 113 (e.g., HfO), and an interface layer 114 (e.g., SiO2). Using the process described herein, at least a portion of the first metal-containing layer 111 may be selectively removed from the first set of nanosheet structures 110 relative to the underlying layer, such as at least one other material 112, 113, 114, while the second set of nanosheet structures 120 is masked by a mask layer 125.

[0034] refer to Figure 1A and Figure 1B An etching process can be performed to etch or remove exposed metal 102 (see [reference]). Figure 1A ) or the first metal-containing layer 111 (see Figure 1B Precise etching control is essential for manufacturing metal contacts with acceptable electrical properties and surface roughness conditions without damage or corrosion. Figure 1A The lower membrane 101 or the liner 103, or Figure 1B The second metal layer 112, the gate dielectric layer 113, and the interface layer 114 are essential.

[0035] like Figure 2 As shown, an etching method is provided according to an embodiment. This method involves... Figure 2 The flowchart in the image is presented as 200. Figure 2 As presented, flowchart 200 begins at 210 with a receiving substrate 100 having a working surface exposing metal 102 and having at least one other material 101 and / or 103 exposed to or beneath metal 102. Metal 102 may include W, Ti, TiN, Ta, TaN, Ru, Co, or other transition metals, or combinations thereof.

[0036] In one embodiment, the metal layer 102 contains W, and the other materials 101 and / or 103 comprise Ti or TiN. The other materials 101 and / or 103 may include organic materials, silicon-containing materials, germanium-containing materials, titanium-containing materials, or materials in the form of Si. x Ge 1-xThe materials 101 and / or 103 may be silicon, silicon oxide, silicon nitride, titanium, titanium nitride, or combinations thereof. In another embodiment, metal layer 111 contains TiN, and other materials 112, 113, and 114 comprise a multilayer structure of TaN, HfO, and SiO2. Other materials may further include a mask layer 125.

[0037] Substrate 100 may include a bulk silicon substrate, a single-crystal silicon (doped or undoped) substrate, a semiconductor-on-insulator (SOI) substrate, or any other semiconductor substrate containing, for example, Si, SiC, SiGe, SiGeC, Ge, GaAs, InAs, InP, and other III / V or II / VI compound semiconductors, or any combination thereof (Groups II, III, V, and VI refer to the classical or old IUPAC symbols in the periodic table; according to the revised or new IUPAC symbols, these groups will refer to Groups 2, 13, 15, and 16, respectively). Substrate 100 may have any size, such as a 200 mm substrate, a 300 mm substrate, a 450 mm substrate, or even larger. Device layers may include any film or device structure to which patterns can be transferred.

[0038] In 220, metal layers 102 and 111 are etched differentially relative to other materials 101, 103, 112, 113, and 114 by exposing the substrate to a controlled gaseous environment containing anhydrous halogen compounds such as diatomic halogens (e.g., F2), nitrogen-halogen compounds (e.g., NF3), or interhalogen compounds (e.g., ClF3). In some embodiments, the anhydrous halogen compounds do not contain nitrogen. Interhalogen compounds are compounds composed of two or more different halogen atoms. Interhalogen compounds may contain at least two elements selected from the group consisting of I, F, Cl, and Br. Interhalogen compounds may contain at least two elements selected from the group consisting of F, Cl, and Br. Interhalogen compounds may include tetraatomic interhalogen compounds. As an example, an interhalogen compound may include ClF3. The gaseous environment may include mixtures thereof and may further include rare gas elements, halides, N2, H2, or NH3, or combinations of two or more thereof. For example, the gaseous environment may include F2, NF3, ClF3, and mixtures thereof. Furthermore, the gas phase environment may further include effluents from a remote plasma or radical source. Alternatively, the gas phase environment may consist of ClF3.

[0039] When metals 102 and 111 are exposed to anhydrous halogenated chemicals, reaction byproducts can be observed. These byproducts have been shown to volatilize under reduced pressure at temperatures above 80°C. The ratio of etch gas to diluent gas can be carefully controlled and adjusted to achieve uniform and isotropic etching of metals 102 and 111, depending on the requirements of device fabrication. Furthermore, the gas pressure within the chamber allows for control of the etching rate to account for flow rate and any potential over-etching. Additionally, process parameters such as temperature and etchant concentration can be carefully tuned to achieve targeted etch selectivity.

[0040] As an example, vapor-phase etching can be accomplished by adsorbing ClF3 onto a surface at a suitable temperature (e.g., typically between about 35°C and 130°C, but this temperature can be as high as 300°C), which activates the surface and drives metal etching. The reaction rate for different materials is primarily controlled by two factors: (1) the rate of adsorption (e.g., ClF3) on the surface, and (2) the availability or concentration of the etching gas near the surface. The concentration of the etching gas can be controlled by adjusting the etching gas flow rate, including by adding diluents (e.g., N2, Ar, etc.), and the chamber pressure. Subsequently, reaction byproducts can be sublimated by increasing the temperature of the substrate under reduced pressure.

[0041] In one embodiment, tungsten (W) can be in a form more readily available than organic materials, silicon-containing materials, germanium-containing materials, and Si. x Ge 1-x (Where x < 0.5) silicon-germanium alloys can be etched at a higher rate. In another embodiment, this can be achieved relative to Ti, TiN, and Si forms. x Ge 1-x The silicon-germanium alloy (where x > 0.5) adjusts the etch selectivity for tungsten (W). For example, when etching W and the other materials are Ti and / or TiN, a relatively low temperature (i.e., close to 35°C) causes W to etch at a faster rate than Ti or TiN (etch selectivity 10:1, etch rate of W: etch rate of Ti or TiN), and a relatively high temperature (i.e., close to 130°C) causes W to etch at approximately the same rate as Ti or TiN (etch selectivity 1:1, etch rate of W: etch rate of Ti or TiN). In yet another embodiment, TiN can be etched at a higher rate than TaN, HfO, and SiO2.

[0042] Etching may further include raising the temperature of substrate 100 to 60°C or above when exposed to anhydrous halogens, such as interhalogen compounds. Alternatively, the temperature of the substrate may be raised to 70°C or higher, or 80°C or higher.

[0043] Etching may further include controlling the temperature of substrate 100 within a range from about -30°C to about 60°C when exposed to anhydrous halogens, such as interhalogen compounds.

[0044] As described above, etching may further include post-heat treatment of the substrate at a temperature of 80°C or above, for example, 100°C or above, 100°C to 400°C, 100°C to 300°C, or above 190°C, following exposure to anhydrous halogens (e.g., interhalogen compounds). Exposure of the substrate to a controlled gas phase environment containing anhydrous halogens (e.g., interhalogen compounds) and post-heat treatment of the substrate can be performed independently in a separate processing chamber. Alternatively, exposure of the substrate to a controlled gas phase environment containing halogen compounds and post-heat treatment of the substrate can be performed in the same processing chamber.

[0045] Other process steps can be performed before and / or after the etching step. For example, a cleaning step or a natural oxide penetration step can be performed before etching to clean the silicon-germanium alloy surface. The etching step may include NH3 and / or HF, but other chemicals may also be considered.

[0046] At least a portion of the metal layers 102, 111 are selectively removed from the substrate 100 or device 105. For example, the metal layers 102, 111 may be removed differentially relative to other materials. Etching can be performed by placing the substrate 100 or the substrate-containing device 105 in a tandem chamber etching system, such as... Figure 3 The system described in 5, or the system described in U.S. Patent No. 7,029,536 entitled "Processing system and method for treating a substrate" or U.S. Patent No. 8,303,716 entitled "High throughput processing system for chemical treatment and thermal treatment and method of operating"; or selective etching can be performed by placing the substrate 100 or the substrate-containing device 105 in a single-chamber etching system, such as Figure 6 and Figure 7The systems described herein are those described in U.S. Patent No. 7,718,032 entitled "Dry non-plasma treatment system and method of using," the entire contents of which are incorporated herein by reference.

[0047] According to one embodiment, differentiated etching is performed by exposing the surface of a substrate to a chemical environment containing anhydrous halogen compounds (such as interhalogen compounds) at a first setpoint temperature to chemically alter the surface region of the metal, and then raising the temperature of the substrate to a second setpoint temperature to remove the chemically treated surface region of the metal. As an example, the first setpoint temperature is at or above 35°C and at or below 300°C, for example, at or below 130°C, and the second setpoint temperature is at or above 80°C. Furthermore, this process sequence can be repeated cyclically to meet etching requirements.

[0048] During exposure, selected surfaces of the workpiece, including the exposed surfaces of metal layers 102 and 111, are chemically treated in a gas-phase chemical environment. The inventors have observed that these surface layer chemical changes occur in a self-limiting manner, i.e., the surface is exposed to the chemical environment for a predetermined duration, and the chemical change proceeds to a self-limiting depth. By selecting various process parameters, including the processing pressure of the chemical environment, the temperature of the workpiece, the temperature of the workpiece holder, the temperature of other chamber components, the composition of the chemical environment, and the absolute and relative flow rates of the gas phase components entering the chamber, specific materials can be locked in and a predetermined depth can be achieved. As the workpiece temperature increases, the chemically changed areas of the selected surfaces of metal layers 102 and 111 are volatilized and removed. During processing, these steps can be repeated as needed to etch a target amount of metal.

[0049] As described above, the temperature of the substrate holder or substrate can be selected to remove a material differentially or indiscriminately relative to another material. In one example, in order to differentially remove a layer made of metal relative to silicon oxide, silicon nitride, silicon carbide, amorphous carbon, silicon-germanium alloy, titanium, titanium nitride, and organic materials or other materials (including metals), the first temperature of the substrate holder or substrate can exceed 35°C, 60°C, 70°C, or 80°C, or range from 35°C to 300°C, or 35°C to 200°C, or 35°C to 130°C, or 80°C to 130°C.

[0050] In addition to interhalogen compounds, the chemical environment may also contain diatomic halogens, halides, HF, NF3, F2, NH3, N2, or H2, or combinations thereof. The chemical environment may further contain rare elements. In other embodiments, the chemical environment may contain excitation substances, radical substances, or metastable substances, or any combination thereof. For example, the dry non-plasma etching chamber includes a remote plasma generator or a remote radical generator arranged to supply the dry non-plasma etching chamber with excitation, radical, or metastable substances of halogens, F, N, or H. The processing pressure can range from 1 mTorr to 5 Torr, or 10 mTorr to 3 Torr, or 50 mTorr to 3 Torr, or 100 mTorr to 3 Torr, or greater than 100 mTorr.

[0051] Subsequently, the target, chemically altered surface layer is desorbed by raising the temperature from a first setpoint temperature to a second setpoint temperature, which can be performed in the same chamber or in a separate chamber. The second setpoint temperature can range from 80°C to 400°C, or from 80°C to 300°C, or preferably, from 80°C to 225°C, or preferably, from 80°C to 200°C, or more preferably, from 100°C to 200°C or higher.

[0052] Furthermore, the exposure and elevation steps can be performed alternately and sequentially. From one step to the next or from one cycle to the next, any one or more process parameters, including the processing pressure of the chemical environment, the temperature of the workpiece, the temperature of the workpiece holder, the temperature of other chamber components, the composition of the chemical environment, and the absolute and relative flow rates of the gas phase components entering the chamber, can be adjusted.

[0053] According to an embodiment, Figure 3 This is a schematic configuration diagram illustrating an example of a processing system equipped with an etching system performing an etching method according to an embodiment of this disclosure. The processing system 300 includes: a loading / unloading section 302 configured to load and unload a semiconductor substrate (hereinafter referred to as a "wafer") W as a target substrate, wherein a silicon-germanium alloy and another material coexist; two loading lock chambers (L / L) 303 arranged adjacent to the loading / unloading section 302; two heat treatment devices 304 (e.g., heat treatment chambers) arranged adjacent to the corresponding loading lock chambers 303 and configured to heat treat the wafer W; two etching devices 305 (e.g., chemical treatment chambers) according to an embodiment of the invention, arranged adjacent to the corresponding heat treatment devices 304 and configured to etch the wafer W; and a control section 306.

[0054] The loading / unloading section 302 includes a transfer chamber (L / M) 312 in which a first wafer transfer mechanism 311 for transferring wafers W is mounted. The first wafer transfer mechanism 311 includes two transfer arms 311a and 311b configured to hold the wafers W in a generally horizontal position. A stage is mounted on one longitudinal side of the transfer chamber 312. The stage is configured to connect one or more, for example, three, substrate carriers C capable of accommodating multiple wafers W. Furthermore, a substrate alignment device 314 configured to perform position alignment by rotating the wafers W and positioning reference points thereon is mounted adjacent to the transfer chamber 312.

[0055] In the loading / unloading section 302, the wafer W is held by one of the transport arms 311a and 311b and is moved linearly or vertically within a substantially horizontal plane by the operation of the first wafer transport mechanism 311, thereby being transported to the desired position. Furthermore, as the transport arms 311a and 311b move toward or away from the substrate carrier C, the orientation device 314, and the loading lock chamber 303, the wafer W is loaded or unloaded relative to the carrier C, the orientation device 314, and the loading lock chamber 303 supported on the support stage.

[0056] Each of the loading lock chambers 303 is connected to the transfer chamber 312, with a gate valve 316 inserted between each loading lock chamber 303 and the transfer chamber 312. A second wafer transfer mechanism 317 for transferring the wafer W is installed in each of the loading lock chambers 303. Each of the loading lock chambers 303 is configured such that it can be evacuated to a predetermined vacuum level.

[0057] The second wafer transport mechanism 317 has an articulated arm structure and includes a picker configured to hold the wafer W in a substantially horizontal position. In the second wafer transport mechanism 317, when the articulated arm is retracted, the picker is positioned within each of the loading lock chambers 303. As the articulated arm extends, the picker can reach the corresponding heat treatment unit 304, and as the articulated arm extends further, it can reach the corresponding etching unit 305. Therefore, the second wafer transport mechanism 317 can transport the wafer W between the loading lock chambers 303, the heat treatment unit 304, and the etching unit 305.

[0058] As shown in Figure 4, each of the heat treatment apparatus 304 includes a vacuum control chamber 420 and a stage 423 configured within the chamber 420 to hold a wafer W. A heater 424 is embedded in the stage 423. After undergoing an etching process, the wafer W is heated by the heater 424, thereby evaporating and removing etching residues present on the wafer W. The wafer W is mounted in the side wall of the chamber 420 adjacent to the loading lock chamber 303 via a loading / unloading gate 420a that transports it between the heat treatment apparatus 304 and a corresponding loading lock chamber 303. The loading / unloading gate 420a is opened and closed via a gate valve 422. Furthermore, the wafer W is mounted in the side wall of the chamber 420 adjacent to the etching device 305 via a loading / unloading gate 420b that transports it between the heat treatment apparatus 304 and a corresponding etching device 305. The loading / unloading gate 420b is opened and closed via a gate valve 454. A gas supply passage 425 is connected to the upper part of the side wall of the chamber 420. Gas supply passage 425 is connected to an inert gas, namely N2, from gas supply source 400. Exhaust passage 427 is connected to the bottom wall of chamber 420. Exhaust passage 427 is connected to vacuum pump 433. Flow regulating valve 431 is installed in gas supply passage 425. Pressure regulating valve 432 is installed in exhaust passage 427. By controlling flow regulating valve 431 and pressure regulating valve 432, the interior of chamber 420 is maintained in an inert or nitrogen atmosphere at a predetermined pressure. Heat treatment is performed under these conditions. Other inert gases, such as Ar, can be used instead of N2.

[0059] The control unit 306 includes a process controller 391 equipped with a microprocessor (computer), which controls the various components of the processing system 300. A user interface 392, including a keyboard allowing operators to perform command input operations to manage the processing system 300, and a display visualizing and showing the operating status of the processing system 300, is connected to the process controller 391. Also connected to the process controller 391 is a storage unit 393, which stores: control programs for implementing various types of processes executed in the processing system 300 under the control of the process controller, such as the supply of processing gases and the evacuation of chambers in each of the etching apparatus 305 described later; processing programs, which are control programs for allowing the various components of the processing system 300 to execute specific processes according to process conditions; and various types of databases. Programs are stored in a suitable storage medium (not shown) in the storage unit 393. If needed, any program can be retrieved from the storage unit 393 and executed by the process controller 391. In this way, the desired process is executed in the processing system 300 under the control of the process controller 391.

[0060] According to an embodiment, the etching apparatus 305 is configured to perform selective etching of the silicon-germanium alloy relative to other materials. The detailed configuration of the etching apparatus 305 will be described later.

[0061] In the processing system 300, wafers, including silicon-germanium alloys and other materials, are exposed on wafer W. Multiple wafers of this type W are loaded within a substrate carrier C and transported into the processing system 300.

[0062] In the processing system 300, one of the wafers W is transferred from the substrate carrier C carried in the loading / unloading section 302 to one of the loading lock chambers 303 via one of the transfer arms 311a and 311b of the first wafer transfer mechanism 311, while keeping the atmospheric side gate valve 316 open, and is delivered to the picker of the second wafer transfer mechanism 317 arranged in the loading lock chamber 303.

[0063] Subsequently, the atmospheric side gate valve 316 is closed, and the interior of the loading lock chamber 303 is evacuated. Then, the gate valve 354 is opened, and the pickup is extended into the corresponding etching device 305, so that the wafer W is transported to the etching device 305.

[0064] Afterward, the pickup returns to the loading lock chamber 303 and the gate valve 354 closes. Then, the etching process is performed in the etching apparatus 305 in the following manner.

[0065] After the etching process is completed, gate valves 322 and 354 are opened. The etched wafer W is transported to the heat treatment apparatus 304 via the pick-up device of the second wafer transport mechanism 317. While N2 gas is introduced into the chamber 420, the wafer W, which is supported on the support stage, is heated by a heater, thereby thermally removing etching residues and the like.

[0066] After heat treatment is completed in heat treatment apparatus 304, gate valve 322 is opened. The etched wafer W, carried on the carrier stage, is moved to loading lock chamber 303 by the pick-up device of second wafer transport mechanism 317. Then, the etched wafer W is returned to one of the carriers C by one of the transport arms 311a and 311b of first wafer transport mechanism 311. In this way, the process of one wafer is completed.

[0067] In the processing system 300, the heat treatment device 304 is not necessary. Without the heat treatment device installed in the processing system 300, the wafer W after the etching process can be moved to one of the loading lock chambers 303 by the picker of the second wafer transport mechanism 317, and then returned to one of the carriers C by one of the transport arms 311a and 311b of the first wafer transport mechanism 311.

[0068] Next, the etching apparatus 305 will be described in detail according to the embodiments.

[0069] Figure 5 is a cross-sectional view illustrating an etching apparatus according to an embodiment of the present invention. As shown in Figure 5, the etching apparatus 305 includes a chamber 540 having a sealed structure. A support stage 542 configured to support a wafer W in a substantially horizontal position is mounted within the chamber 540. The etching apparatus 305 further includes a gas supply mechanism 543 configured to supply etching gas to the chamber 540 and a evacuation mechanism 544 configured to evacuate the interior of the chamber 540.

[0070] The chamber 540 is composed of a chamber body 551 and a cover 552. The chamber body 551 includes a generally cylindrical sidewall portion 551a and a bottom portion 551b. The upper part of the chamber body 551 is open. This opening is closed by the cover 552. The sidewall portion 551a and the cover 552 are sealed by a sealing member (not shown), thereby ensuring the airtightness of the interior of the chamber 540. A gas introduction nozzle 561 is inserted through the top wall of the cover 552 to extend from above toward the interior of the chamber 540.

[0071] The wafer W is mounted in the sidewall portion 551a via a loading / unloading gate 553 that loads and unloads it between the chamber 540 of the etching apparatus 305 and the chamber 420 of the heat treatment apparatus 304. The loading / unloading gate 553 is opened and closed by a gate valve 554.

[0072] The stage 542 is generally circular in top view (but its shape can be arbitrary) and is fixed to the bottom 551b of the chamber 540. A temperature controller 555 configured to control the temperature of the stage 542 is installed within the stage 542. The temperature controller 555 includes a conduit through which a temperature control medium (e.g., water) circulates. The temperature of the stage 542 is controlled by heat exchange between the stage 542 and the temperature control medium flowing through the conduit, and thus, the temperature of the wafer W supported on the stage 542 is controlled.

[0073] The gas supply mechanism 543 may include multiple gas supplies 563, 564, 565, 566, for example, including gas supplies for interhalogen compounds. The gas supply mechanism 543 further includes multiple supply lines 567, 568, 569, 570, for example, for pneumatically coupling the gas supply to one or more gas lines 571 and gas nozzles 561.

[0074] The flow controller 572 is configured to perform flow path opening / closing operations and flow control for each type of gas supplied to chamber 540. A spray plate may be mounted on the upper part of chamber 540 to supply the excitation gas in a spray-like manner.

[0075] The evacuation mechanism 544 includes an exhaust pipe 582 connected to an exhaust port 581 formed in the bottom 551b of the chamber 540. The evacuation mechanism 544 further includes an automatic pressure control valve (APC) 583 mounted in the exhaust pipe 582 and configured to control the internal pressure of the chamber 540, and a vacuum pump 584 configured to evacuate the interior of the chamber 540.

[0076] Two capacitive pressure gauges 586a and 586b are installed in the side wall of chamber 540 as pressure gauges for measuring the internal pressure of chamber 540, with the gauges inserted into chamber 540. Capacitive pressure gauge 586a is used to measure high pressure, while capacitive pressure gauge 586b is used to measure low pressure. A temperature sensor (not shown) for detecting the temperature of wafer W is installed near wafer W, which is supported on stage 542.

[0077] Aluminum is used as the material for various components constituting the etching apparatus 305, such as chamber 540 and stage 542. The aluminum material constituting chamber 540 can be pure aluminum or aluminum with an anodized inner surface (such as the inner surface of chamber body 551). On the other hand, the surface of the aluminum material constituting stage 542 needs to be wear-resistant. Therefore, in some embodiments, an oxide film (e.g., an Al2O3 film) with high wear resistance can be applied to the surface of the aluminum material by anodizing.

[0078] According to another embodiment, the workpiece is placed in a single-chamber etching system (e.g., a dry non-plasma etching system, or a chemical and / or heat treatment chamber), such as Figure 6 The substrate holder in the system described herein. The single-chamber etching system is operated to perform the following: (1) exposing the surface of the workpiece to a chemical environment at a first setpoint temperature in the range of 50°C to 100°C, and preferably greater than or equal to 60°C, to chemically alter the surface region of the silicon-germanium alloy 102, and (2) then raising the temperature of the workpiece to a second setpoint temperature at or above 100°C to remove the chemically treated surface region of the target layer. The range of the first setpoint temperature may be from 50°C to 300°C, or 50°C to 200°C, or 50°C to 100°C, or 70°C to 90°C, and the range of the second setpoint temperature may be from 110°C to 400°C, or from 110°C to 300°C, or from 110°C to 225°C, or greater than or equal to 170°C.

[0079] A first setpoint temperature can be established by flowing a heat transfer fluid through the workpiece holder at a first fluid setpoint temperature. A second setpoint temperature can be established by flowing a heat transfer fluid through the workpiece holder at a second fluid setpoint temperature. In addition to flowing a heat transfer fluid through the workpiece holder at the second fluid setpoint temperature, the substrate holder can also be heated by electrically coupling at least one resistance heating element embedded within the workpiece holder. Alternatively, in addition to flowing a heat transfer fluid through the workpiece holder at the second fluid setpoint temperature, at least one other heat source separate from the workpiece holder can be used to heat the workpiece holder.

[0080] According to another embodiment, Figure 6 An etching system 600 for dry removal of material from a microelectronic substrate 625 is shown. System 600 includes a processing chamber 610 for processing the substrate 625 in a non-plasma, vacuum environment; a substrate holder 620 disposed within the processing chamber 610 and configured to support the substrate 625; a temperature control system 650 coupled to the substrate holder 620 and configured to control the temperature of the substrate holder 620 at two or more setpoint temperatures; a gas distribution system coupled to the processing chamber 610 and arranged to supply one or more processing gases into the processing chamber 610; and a controller 660 operatively coupled to the temperature control system 650 and configured to control the temperature of the substrate holder 620 within a range from 35°C to 250°C. For example, the temperature control system 650 may be configured to control the temperature of the substrate holder 620 within a first setpoint temperature range of 35°C to 130°C, and to regulate and control the temperature of the substrate holder 620 at or above a second setpoint temperature of 80°C. Alternatively, for example, the temperature control system 650 may be configured to control the temperature of the substrate holder 620 within a first setpoint temperature range of 10°C to 150°C, and to adjust and control the temperature of the substrate holder 620 at or above a second setpoint temperature of 80°C.

[0081] The processing chamber 610 may include a vacuum pump 640 to vent processing gases from the processing chamber 610. The processing chamber 610 may further include a remote plasma generator or a remote radical generator, which is arranged to supply excitation, radicals or metastable substances, or combinations thereof, to the processing chamber.

[0082] The gas distribution system may include a nozzle gas injection system having a gas distribution assembly and one or more gas distribution plates or conduits coupled to the gas distribution assembly and configured to form one or more gas distribution chambers or supply lines. Although not shown, the one or more gas distribution chambers may include one or more gas distribution baffles. The one or more gas distribution plates further include one or more gas distribution orifices to distribute processing gas from the one or more gas distribution chambers to the processing chamber 610. Furthermore, one or more gas supply lines may be coupled to the one or more gas distribution chambers, for example, via the gas distribution assembly, to supply processing gas comprising one or more gases. The processing gas may be introduced as a single flow or as separate, independent flows.

[0083] The gas distribution system may further include a branched gas distribution network designed to reduce or minimize the gas distribution volume. The branched network can eliminate or minimize the volume of gas chambers and shorten the gas distribution length from the gas valve to the processing chamber, while effectively distributing the processing gas across the diameter of the substrate 625. This allows for faster gas switching and more efficient modification of the chemical environment composition.

[0084] The volume of the processing chamber 610 (defining the chemical environment to which the substrate 625 is exposed) can be reduced or minimized to reduce or minimize the residence time or time required to evacuate, displace, and replace a chemical environment with another. The time required to displace the chemical environment in the processing chamber 610 can be estimated as the ratio of the processing chamber volume to the pumping rate delivered to the processing chamber volume by the vacuum pump 640.

[0085] The substrate holder 620 can provide several operational functions for thermal control and processing of the substrate 625. The substrate holder 620 includes one or more temperature control elements configured to regulate and / or raise the temperature of the substrate 625.

[0086] like Figure 7 As shown, the substrate holder 620 may include at least one fluid channel 622 to allow heat transfer fluid to flow through it and change the temperature of the substrate holder 620. The substrate holder 620 may further include at least one resistance heating element 624. Multi-zone channels and / or heating elements can be used to regulate and control the spatial uniformity of heating and cooling of the substrate 625. For example, at least one resistance heating element 624 may include a central zone heating element and an edge zone heating element. Furthermore, for example, at least one fluid channel 622 may include a central zone fluid channel and an edge zone fluid channel. At temperatures above 200°C to 250°C, other heating systems, including infrared (IR) heating, such as lamp heating, may be used.

[0087] A power source 658 is coupled to at least one resistance heating element 624 to supply current. The power source 658 may be a direct current (DC) power source or an alternating current (AC) power source. Furthermore, the at least one resistance heating element 624 may be connected in series or in parallel.

[0088] At least one heating element 624 may, for example, comprise a resistance heater element made of carbon, tungsten, nickel-chromium alloys, aluminum-iron alloys, aluminum nitride, etc. Examples of commercially available materials for manufacturing resistance heating elements include Kanthal, Nikrothal, and Akrothal, which are registered trademark names of metal alloys manufactured by Kanthal Corporation of Bethel, CT. The Kanthal series includes ferritic alloys (FeCrAl), and the Nikrothal series includes austenitic alloys (NiCr, NiCrFe). According to one example, each of the at least one resistance heating element 624 may include a heating element that is commercially available from Watlow Electric Manufacturing Company (Lackland Road 12001, St. Louis, Missouri 63146). Alternatively or additionally, a cooling element may be employed in any embodiment.

[0089] A heat transfer fluid distribution manifold 652 is arranged to pump and monitor the flow of heat transfer fluid through one or more fluid passages 622. The heat transfer fluid distribution manifold 652 can draw heat transfer fluid from a first heat transfer fluid supply tank 654 at a first heat transfer fluid temperature and / or a second heat transfer fluid supply tank 656 at a second heat transfer fluid temperature. The manifold 652 can mix the heat transfer fluid from the first and second fluid tanks 654, 656 to achieve an intermediate temperature. Furthermore, the heat transfer fluid distribution manifold 652 may include a pump, valve assembly, heater, cooler, and fluid temperature sensor to controllably supply, distribute, and mix the heat transfer fluid at a predetermined temperature.

[0090] In an alternative embodiment, the temperature control system 650 may include a hot wall adjacent to the substrate holder 620. The substrate holder 620 may further include a substrate holding system configured to hold the substrate to the substrate holder, and a back gas supply system configured to supply heat transfer gas to the back side of the substrate.

[0091] The heat transfer fluid may include a high-temperature fluid with a boiling point exceeding 200°C. For example, the heat transfer fluid may include Fluorinert. TM FC40 (with a temperature range of -57°C to 165°C), or Fluorinert TMThe FC70 (with a temperature range of -25°C to 215°C) is commercially available from 3M.

[0092] Temperature sensing devices such as thermocouples (e.g., K-type thermocouples, Pt sensors, etc.) or optical devices can be used to monitor the substrate holder 620. Furthermore, the substrate holder temperature control system 650 can utilize temperature measurements as feedback to the substrate holder 620 to control its temperature. For example, at least one of the following can be adjusted: fluid flow rate, fluid temperature, heat transfer gas type, heat transfer gas pressure, clamping force, resistance heater element current or voltage, thermoelectric device current or polarity, etc., to generate changes in the temperature of the substrate holder 620 and / or the substrate 625.

[0093] As described above, controller 660 is operatively coupled to temperature control system 650 and configured to control the temperature of various components in etching system 600, including substrate holder 620, within a temperature range of 10°C to 250°C, or 35°C to 250°C, or 50°C to 250°C. For example, under the command of controller 660, temperature control system 650 can be configured to control the temperature of substrate holder 620 at a first setpoint temperature in the range of 35°C to 100°C, and to regulate and control the temperature of substrate holder 620 at or above a second setpoint temperature of 100°C (see the processing procedure described above). Temperature control system 650 can obtain temperature information from one or more temperature sensors arranged to measure the temperature of substrate holder 620, substrate 625, chamber wall of processing chamber 610, or gas distribution system, etc., and use the temperature information to controllably regulate these temperatures.

[0094] As an example, when the temperature of the substrate holder 620 is changed from a first setpoint temperature in the range of 35°C to 100°C to a second setpoint temperature at or above 100°C, the fluid temperature of the heat transfer temperature can be rapidly adjusted by changing the proportion of heat transfer fluid drawn from the heat transfer fluid supply tanks 654, 656. Once within the predetermined range of the target second setpoint temperature, the setpoint temperature can be accurately controlled using at least one resistance heating element. The substrate holder 620 can be designed to have a relatively low thermal mass. For example, the thickness of the holder and the material composition of the holder can be designed to reduce or minimize the thermal mass of the holder. Furthermore, at least one fluid channel 622, including a fluid conduit for supplying heat transfer fluid to at least one fluid channel 622, can be designed to have a small volume for rapid changes in fluid temperature. For example, the length and diameter of the fluid channel and conduit can be designed to reduce or minimize the volume (i.e., reduce the time required to displace a fluid at one temperature and replace it with a fluid at another temperature).

[0095] Other chamber components of the processing chamber 610, including chamber walls, gas distribution systems, etc., may include heating and / or cooling elements to control their temperature. For example, the temperature of the chamber walls of the processing chamber 610 and the temperature of at least a portion of the gas distribution system may be controlled at a temperature up to 150°C, or in the range of 50°C to 150°C (preferably, 70°C to 110°C).

[0096] Although only certain embodiments of the invention have been described in detail above, those skilled in the art will readily understand that many modifications may be made to the embodiments without substantially departing from the novel teachings and advantages of the invention. Therefore, all such modifications are intended to be included within the scope of the invention.

Claims

1. An etching method, the method comprising: A receiving substrate having a working surface that exposes a metal layer and having at least one other material exposed to or beneath the metal layer; as well as The metal layer is etched non-plasma-etched in a way that is different from other materials by performing the following operations: The surface of the substrate is exposed to a controlled gaseous environment containing anhydrous halogen compounds at a first set point temperature to chemically alter the surface region of the metal layer. After exposing the surface of the substrate, the chemically altered surface region of the metal layer is removed at a second setpoint temperature higher than the first setpoint temperature. Specifically, changing the temperature at the first set point alters the etching selectivity between the metal layer and the at least one other material.

2. The method according to claim 1, wherein, The anhydrous halogen compound includes diatomic halogens, or interhalogen compounds, or combinations thereof.

3. The method according to claim 2, wherein, The interhalogenated compounds include tetraatomic interhalogenated compounds.

4. The method according to claim 1, wherein, The anhydrous halogen compound includes F2, or ClF3, or a combination thereof.

5. The method according to claim 1, wherein, This gaseous environment further includes nitrogen-containing gases.

6. The method according to claim 1, wherein, The gaseous environment further includes rare gas elements, HF, NF3, NH3, effluents from a remote plasma source, or a combination of two or more of them.

7. The method according to claim 1, wherein, These other materials include organic materials, silicon-containing materials, germanium-containing materials, or Si. x Ge 1-x Silicon-germanium alloys in the form of, or combinations of two or more thereof, and Where x is a real number greater than 0.

5.

8. The method according to claim 7, wherein, The silicon-containing material includes silicon, silicon oxide, silicon nitride, and combinations thereof, and wherein the germanium-containing material includes germanium, germanium oxide, germanium nitride, and combinations thereof.

9. The method according to claim 1, wherein, The metal layer contains W, Ti, TiN, Ta, TaN, Ru, Co, or other transition metals, or combinations thereof.

10. The method according to claim 1, wherein, The metal layer contains W, and the other materials include Ti or TiN.

11. The method according to claim 1, wherein, The differentiated etching further includes: When exposed to the anhydrous halogen compound, the temperature of the substrate is raised to 35°C or above and 130°C or below.

12. The method according to claim 1, wherein, The differentiated etching further includes: After exposing the substrate to the anhydrous halogen compound, the substrate is subjected to post-heat treatment at a temperature of 80°C or above.

13. The method according to claim 1, wherein, The differentiated etching further includes: After exposing the substrate to the anhydrous halogen compound, the substrate is subjected to post-heat treatment at a temperature of 170°C or above.

14. The method according to claim 12, wherein, The exposure of the substrate to the controlled gas phase environment containing the anhydrous halogen compound and the subsequent heat treatment of the substrate are performed independently in separate processing chambers.

15. The method according to claim 12, wherein, The substrate is exposed to the controlled gas phase environment containing the anhydrous halogen compound and the substrate is subjected to post-heat treatment in the same processing chamber.

16. An etching method, the method comprising: A receiving substrate having a working surface that exposes a metal layer and having at least one other material exposed to or beneath the metal layer; as well as The metal layer is removed differentially using non-plasma removal methods, specifically targeting at least a portion thereof: The surface of the substrate is exposed to a chemical environment containing anhydrous halogen compounds at a first set point temperature to chemically alter the surface region of the metal layer, and Then, the temperature of the substrate is raised to a second set point temperature to remove the chemically treated surface region of the metal layer. Specifically, changing the temperature at the first set point alters the etching selectivity between the metal layer and the at least one other material.

17. The method according to claim 16, wherein, The anhydrous halogen compound includes diatomic halogens, or interhalogen compounds, or combinations thereof.

18. The method according to claim 17, wherein, The interhalogenated compound includes ClF3.

19. The method of claim 16, wherein, The metal layer contains W, Ti, TiN, Ta, TaN, Ru, Co, or other transition metals, or combinations thereof.

20. The method of claim 16, wherein, The first setpoint temperature is at or above 35°C and at or below 130°C, and the second setpoint temperature is at or above 170°C.

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