Substrate processing involving material modification and removal

Abstract

Etching and surface modification are performed in a plasma where ions are removed and radicals from the plasma form a modified surface on the layer of the substrate, and gas phase chemicals react with the modified surface to form a reactive modified surface which is then removed.

Description

[Technical Field]

[0001] Cross-references to related patents and applications This application claims priority to and the benefit of the filing date of U.S. patent application Ser. No. 17 / 886,289, filed Aug. 11, 2022, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a substrate processing method and a substrate processing apparatus. [Background technology]

[0003] Etching semiconductor materials can be particularly challenging due to the need to selectively etch certain materials relative to other materials and the extreme precision required in performing the etch. For example, certain materials that need to be etched or trimmed are already very thin, e.g., 5 nm or less, and must be etched in the presence of other materials that should not be etched. Existing etching methods can also be undesirable in that they can cause damage to one or more of the materials and / or can cause undesirable material modifications or undesirable residues after the etching process. Summary of the Invention [Means for solving the problem]

[0004] Examples disclosed herein can provide selective etching of thin layers of material, where the etching is selective to other materials and avoids damage to the material being etched or other materials.

[0005] In one example, the plasma is initially used for an etching and modification step, which removes a portion of the material being etched and modifies the remaining surface after etching to provide a modified material or surface. This is followed by a post-treatment to remove the modified surface. The etching / modification step and post-treatment can be performed repeatedly until the desired amount of etching is achieved, or a single iteration of the steps can be used. In one example, the post-treatment includes reacting the modified surface to form a reactive modified surface, and then increasing the temperature to remove the reactive modified surface.

[0006] BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the process and apparatus embodiments of the present specification may be better understood with reference to the drawings, as follows: [Brief explanation of the drawings]

[0007] [Figure 1A] An example of an etching process will be described. [Figure 1B] An example of an etching process will be described. [Figure 1C] An example of an etching process will be described. [Figure 1D] An example of an etching process will be described. [Figure 2] An example of an apparatus that can be used for the processing of the present invention is shown below. [Figure 3] An example of equipment that can be used for post-processing is shown below. [Figure 4] 1 is a flowchart of an example of a process or control algorithm. [Figure 5A] 1 shows processing after selectively coating portions of a substrate. [Figure 5B] 1 shows processing after selectively coating portions of a substrate. [Figure 6A] The composition of the etched material before, during, and after processing is shown. [Figure 6B] The composition of the etched material before, during, and after processing is shown. DETAILED DESCRIPTION OF THE INVENTION

[0008] Examples and advantages achieved by the processes and apparatus will become apparent from the detailed description herein, taken in conjunction with the drawings. It should be understood that in practicing the invention, some processes or apparatus may utilize certain aspects of the examples herein and not other aspects. Similarly, while advantages are described herein for practicing certain examples, some examples may achieve different or additional advantages, or only some of the advantages described herein. Thus, the present invention may be practiced using variations and / or some of the features of the examples disclosed herein.

[0009] 1A-D show by way of example only one example of a device to which the method and apparatus of the present invention can be applied and are not to be construed as limiting.

[0010] 1A-D, a substrate, e.g., a semiconductor substrate, is provided that includes a base 100. The base represented by 100 may include, for example, the base of a semiconductor wafer, and additional layers may also be present above the base 100 and below the features described herein, to which the methods and apparatus of the present invention are also applicable.

[0011] In the illustrated example, the structure includes alternating layers 102 and 104. The example materials and architecture in this example are provided for completeness, but it should be understood that the methods herein can be utilized with other materials or features / architectures. For example, layer 102 can include Si, Ge, or SiGe. Layer 104 can include Si, Ge, or SiGe, but is different from layer 102. For example, layer 102 can be a Si layer that includes no Ge or a lower amount of Ge than layer 104. Layer 104 can include, for example, Ge without Si, or SiGe with a higher amount of Ge than layer 102.

[0012] Furthermore, the positions of layers 102 and 104 may be reversed from those shown. For example, layer 102 is recessed relative to layer 104, but alternatively, layer 104 may be recessed relative to layer 102. Additionally, a substrate may have different features or devices in different regions of the substrate. For example, a substrate may have a first region in which channels are formed with a higher Ge content layer (with a lower Ge content or no Ge content layer between the channels that is recessed for spacers and then removed) and a second region in which channels are formed with a higher Si content (with a higher Ge content layer between the channels that is recessed for spacers and then removed). While two alternating layers 102 and 104 are provided, it should be understood that it is also possible to include three or more layers of different materials. In the example of FIG. 1A, one of layers 102 has already been etched relative to layer 104, making it recessed relative to layer 104. As an example, layer 104 may provide a channel structure, and layer 102 may be subsequently removed to provide channel release (removal of material between the channels).

[0013] Element 106 represents a gate spacer and may be formed, for example, of SiN or a low-k material. Element 108 may be a mask, such as a hard mask, and may be formed, for example, of SiO2 or SiN. Regarding the materials of elements 106 and 108, they may overlap in available material families or groups, although in some instances the materials 106, 108 are different from each other.

[0014] The inner spacer 110 is shown at 110. The spacer material of the inner spacer 110 is formed as a layer over the feature or other layers, filling the recessed portion 103 of the layer 102 in the region between the layers 104. For example, the spacer material of the layer can include SiN or a low-k dielectric material. The low-k dielectric of the spacer layer includes one or more of Si, N, C, O, and / or H. For example, although this should not be construed as limiting, the dielectric can be SiCN. The dielectric can also be doped with boron to provide a SiBCN dielectric, for example. In a preferred example, the layer 110 does not include metal, and the materials used in the modification and etching do not add metal to the layer 100. Additionally, it is preferred that the layer directly below and in contact with the layer 110 (or exposed during processing, e.g., layer 600 described with reference to FIGS. 5A-B ) have at least one of a lower oxygen content or a higher carbon content compared to the modified surface 110a of the layer being etched.

[0015] The spacer material of inner spacers 110 will be a different material than that of gate spacers 106 and mask 108. Region 107 will be provided with a dummy gate, formed for example of amorphous silicon (a-Si). Region 107 provides an area onto which gate metal will be subsequently deposited. Similarly, gate metal can be deposited in the areas occupied by layer 102 in the illustrated embodiment after channel release (removal of layer 102) and gate metal deposition in these areas.

[0016] Spacer layer 110 is often very thin or small before the processing described herein, for example 5 nm thick, and becomes smaller or thinner with processing.

[0017] In the example of FIGS. 1A-D, the goal is to remove a portion of the spacer material in the region of layer 102 that is recessed and adjacent to or between layers 104, leaving a spacer shown at 103 (FIG. 1D). Preferably, the outer surface 103s of spacer 103 does not extend beyond the outer dimensions of surface 104s of layer 104. More preferably, as shown in FIG. 1D, outer surface 103s is preferably slightly recessed from surface 104s of the adjacent layer 104, such that the outer dimensions of spacer 104 are smaller than or recessed from the outer dimensions of layer 104 at surface 104s. In fact, recessing of surface 103s relative to surface 104s may be a requirement for subsequent processing and development of the device. While recesses are shown on both sides (left and right in FIG. 1D), it should be understood that the device may have additional recesses, for example, on all four sides (front and back of the illustrated drawing) when considering the device in three dimensions. 1A is already thin (e.g., 5 nm or less), the etching must be very precise. Additionally, the etching or removal of layer 110 should be selective with respect to the layers below it, so that the partial removal of layer 110 to leave spacers 103 does not damage the underlying layers. Portions of other layers may be exposed during the completion of the etching of layer 110 to leave spacers 103.

[0018] 1A to 1D, an etching and modification step is performed as shown in FIG. 1B. In the etching and modification step, the spacer material of the inner spacer layer 110 is etched and modified in one step, resulting in the removal of a portion of the layer 110 and the modification of the remaining surface, or modified surface 110a, of the material 110 compared to the material before the etching / modification step. Thus, after the etching and modification step, a portion of the material 110 is removed, leaving a modified surface 110a, which has an increased amount of oxygen and an increased amount of fluorine compared to the material of the inner spacer layer 110 before the etching and modification step.

[0019] The etching and modification steps can include a plasma process in which plasma ions are removed, thereby performing etching and modification using plasma radicals. The plasma gas contains at least fluorine and oxygen, preferably hydrogen, and may also contain a carrier gas, typically an inert gas. Examples of gases used in forming the plasma include NF3, H2, O2, Ar, NO, and N2, and the gas contains at least one fluorine-containing gas and at least one oxygen-containing gas. In a preferred example, a remote plasma is first formed with the plasma gas, and ions are removed from the plasma during transport, for example, from the chamber (or chamber portion) where the plasma is generated to the chamber or chamber portion where the substrate resides. Plasma etching and modification can occur at temperatures, for example, between -20°C and 100°C, preferably between 0°C and 85°C, and more preferably between 15°C and 85°C. A preferred temperature range can also be between 0°C and 50°C for better control (smaller etching steps). For more aggressive etching modifications, etching and modification can be performed at temperatures ranging from 50°C to 100°C, preferably from 50°C to 85°C. For less aggressive etching and modification, lower temperatures ranging from 0°C to 50°C are preferred. In a preferred example for better control, the depth of the etching modification and subsequent thickness removal is 1 nm or less per iteration (etch modification and subsequent post-treatment, described below). Pressures can range from 10 mTorr to 1000 mTorr, preferably from 25 mTorr to 500 mTorr. More aggressive etching modifications performed at higher temperatures and higher concentrations of oxygen and / or fluorine result in a thicker modified surface, and the final structure of FIG. 1D can be achieved with a single etching and modification step and a single post-treatment step (described below). For better control, thinner modified surfaces can be formed at lower temperatures, and the etching modification step can be followed by a post-treatment step, followed by one or more additional iterations of the etching modification step and post-treatment step. Lower pressures allow for longer etching modification times and better control of the extent or thickness of the modified surface.As another variation, when repeated cycles are used, one or more early cycles can utilize higher temperatures (e.g., above 50°C, e.g., 50°C to 85°C), while one or more other cycles can utilize etch modification at lower temperatures (e.g., below 50°C, e.g., 0°C to 50°C). Preferably, when controlled removal is desired, each iteration of etch modification and post-treatment (reaction of the modified surface followed by thermal treatment) removes less than 1 nm of the target material being etched. During the etching and modification step, a portion of layer 110 is removed, and the remaining surface 110a is modified to have increased amounts of oxygen and fluorine. It is also within the scope of embodiments herein to provide a modified surface 110a with increased oxygen and fluorine content without removing material from layer 110 during modification. In most instances, a portion of layer 110 is also removed during the etching and modification process or process step.

[0020] In one example, when forming the plasma, the volumetric flow rate of the fluorine-containing gas can be, for example, 5%-25% of the total gas flow rate, and the fluorine-containing gas can be, for example, NF3. The oxygen can be, for example, 20%-55% of the total volumetric flow rate, and the hydrogen can be, for example, less than 25%, for example, 5%-25%. The remaining gases in one example are nitrogen and argon. For a more aggressive etching and modification step, the volumetric flow rate of NF3 can be 20%-25% and the volumetric flow rate of oxygen can be 45%-55%. However, as described below, if other materials are exposed during processing (besides the material being removed), additional modification may be used, such as maintaining oxygen at 1%-5% if an OPL (organic planarization layer) is present.

[0021] After the etching and modification steps, a post-treatment is performed. In one example, the post-treatment includes two steps, or substeps, including a gas-phase chemical treatment or reaction in which the modified surface 110a reacts with a gas-phase chemical gas, preferably not in a plasma state, resulting in the formation of a reactive modified surface from the modified surface 110a. The substrate is then subjected to a thermal treatment to raise the temperature of the substrate and remove the reactive modified surface. As can be seen in FIG. 1C, after the post-treatment, the modified surface 110a has been removed, and the amount of material in layer 110, as shown in FIG. 1C, has been reduced compared to FIG. 1B and compared to FIG. 1A. In the illustrated configuration, additional removal of layer 110 (one or more additional iterations of etching and modification followed by post-treatment) is required to achieve the final desired result shown in FIG. 1D. However, as previously mentioned, a single run of each of the etching and modification steps and post-processing can be used to achieve the final architecture of FIG. 1D, particularly if more aggressive etching and modification steps are utilized at higher temperatures (and / or with higher fluorine and / or oxygen amounts).

[0022] The reaction of the modified surface is with a different gas chemistry than that used to form the plasma for etching modification, and can be with gases including HF and NH3, and possibly Ar and N2. The temperature can be, for example, 15°C to 120°C, although lower temperatures are preferred because the gases reacting with the modified surface are more likely to adhere to or bond with the modified surface at lower temperatures. For example, the temperature can be in the range of 15°C to 85°C, preferably below 50°C, for example, 30°C to 50°C. The pressure can be 10 mTorr to 3000 mTorr, for example, 25 to 2000 mTorr.

[0023] After reacting the modified surface to form the reactive modified surface, the temperature of the substrate or substrate environment is raised (higher than the temperature during the reaction) for a thermal treatment step, e.g., 70°C to 300°C, preferably 100°C to 250°C, e.g., 150°C to 250°C. When an OPL is present (e.g., as shown in Figures 5A-B and described below), a lower temperature, e.g., 70°C to 150°C, is preferred. Preferably, the thermal treatment is performed in an inert environment, e.g., containing N and Ar, preferably without halogens, oxygen, or other reactive gases. Thus, HF and NH3 are introduced during the reaction of the modified surface in the initial post-treatment, but are not introduced into the environment in which the substrate is placed during the thermal treatment. The pressure can be 1000 mTorr to 10,000 mTorr, preferably 1000 mTorr to 5000 mTorr, e.g., 1000 mTorr to 3000 mTorr (e.g., 2000 mTorr), typically higher than the pressure during the modification and reaction of the modified portion. The heat treatment is preferably for at least 60 seconds, more preferably for more than 120 seconds. The heat treatment can be carried out in the same chamber as the reaction of the modified surface, or alternatively, the substrate can be transferred to a separate chamber for the heat treatment.

[0024] Referring to FIG. 2 , an example of an apparatus that can be used to perform etch modification is shown. The apparatus is controlled by a controller 200, which controls the apparatus to perform the processes disclosed herein, including controlling power from a power supply 202, supplying gas from a gas supply GS 204, and controlling temperature via a temperature control system TC 206, which can include one or more heaters. Heaters can be provided in a first chamber (or chamber portion) 210 and, optionally, in a second chamber (or chamber portion) 212 in which a substrate is processed. Heaters can include heaters associated with one or more of the chamber walls 214, 216 and / or electrodes 218 associated with the chamber or chamber portion 210, and / or heating can also be provided with respect to a substrate holder or substrate support 220 on which a substrate 222 being processed rests. The substrate support 220 or other components can also have components for cooling, as needed, using, for example, liquid or gas cooling or a heat exchanger. Plasma process gases are evacuated using a vacuum pump VP, indicated at 224. A combination of gas flow into the system and gas evacuation by a vacuum pump can also be used to control the pressure within the device.

[0025] Controller 200 may include, for example, one or more processors or computers and may also include memory for storing, for example, process commands, recipes, recipe data, substrate data, or other control data. Control information may also be provided to controller 200 from another device or memory separate from controller 200. Control and recipe data is preferably stored on a non-transitory computer-readable medium. While one controller is identified or represented in 200, it should also be understood that the controller may include one or more sub-controllers or separate controllers operating independently or under command from controller 200 to control various power, gas supply, and temperature control equipment and functions for carrying out processes as described herein.

[0026] The gas source 204 includes a source of at least one oxygen-containing gas and at least one fluorine-containing gas, preferably hydrogen. The gas source 204 controllably supplies process gases at amounts of prescribed concentrations. Typically, a carrier gas, such as argon, is also provided. By way of example, the gas source 204 may be NF 3、 A supply of one or more gases selected from H2, O2, Ar, NO, or N2 is provided, wherein the supplied gas comprises at least fluorine and oxygen. While preferred gases and materials are described herein, it should be understood that other combinations are possible. Additionally, as used herein, reference to a gas or element not being used or present means that the gas or element is not intentionally added or introduced, but that trace amounts of the material may be present depending on the purity of the materials used.

[0027] While electrodes are shown schematically at 218, other types of plasma generation can be utilized, such as one or more electrode arrangements with one or more radio frequency or inductive elements on or off the chamber to provide inductive power, or microwave components to generate the plasma with microwave energy. In one example, a power in the range of 300-1000 watts is provided to generate the plasma. Gases from gas source 204 can be supplied through electrode 218 (e.g., in a showerhead configuration) and / or through other gas inlets, and the gases can be mixed upstream of the chamber or within chamber 210.

[0028] Thus, a first plasma, represented generally at P1, is formed within chamber or chamber portion 210. Additionally, in the illustrated example, a separator, such as a mesh or grid, provides filter or separator 230, which, when powered, filters or removes ions (preventing ions from passing therethrough), such that plasma passing from chamber 210 to chamber (or chamber portion) 212 passes through separator or filter 230 but not ions. As a result, a second plasma, represented generally at P2, is ion-free (or at least contains fewer ions than plasma P1). In a preferred embodiment, plasma P2 is ion-free but contains at least oxygen and fluorine radicals, which react to etch the surface and form a modified surface on the layer of the substrate being etched and modified. The configuration of FIG. 2 can be considered as including separate chambers or as one chamber containing separate chamber portions. Additionally, while plasma P1 and plasma P2 are represented generally, it should be understood that this is because the second plasma differs from one another in that ions have been removed. However, rather than being illustrated as separate and distinct plasmas P1 and P2, the first and second plasmas P1 and P2 may be illustrated as extending continuously from the first chamber portion to the second chamber portion, but the second plasma to which the substrate is exposed in the second chamber portion is a different plasma, i.e., the second plasma, in that it has been stripped of ions.

[0029] The pressure and temperature are controlled within the ranges as previously described.

[0030] After the radical etching / modification, a post-treatment is performed. While it is possible to perform the processing steps in a single chamber, in a presently preferred example, the post-etch / modification treatment is performed in a separate chamber 301, as shown in FIG. 3. Chamber 301 is controlled by controller 300, which may include one or more processors or computers configured to control the operations and processes performed in chamber 301. As noted with respect to controller 200, controller 300 may store instructions or process commands (e.g., using a memory including a non-transitory computer-readable medium) or may receive instructions or data from another memory or controller. Also as previously mentioned, controller 300 may be a single controller or may include distributed controllers or sub-controllers for controlling the various components and operations discussed herein.

[0031] Gas source GS2, shown at 304, controllably supplies process gases from one or more gas sources (which are part of gas source GS2) at designated concentrations, and the temperature can be controlled by various temperature control means, as represented at TC2 306, which can include temperature control of the substrate holder 320 and / or the chamber walls and / or radiation or other forms of temperature control. A substrate 322 is placed on substrate holder 320 and may be held by electrostatic attraction, for example, by an electrostatic chuck. A vacuum pump VP2 at 324 is provided for evacuating the gases. In a presently preferred example, the gases from gas source 304 are not excited into a plasma, but are provided in the vapor phase so that processing is performed with vapor-phase chemistry.

[0032] The gas-phase chemicals include gases that react with the modified surface to form a reactive modified surface that can be removed by thermal treatment. The thermal treatment can be performed in the same chamber as the gas-phase reaction, or in a separate chamber after the gas-phase (non-plasma) reaction. The gas-phase reaction of the modified surface can be, for example, a reaction with a gas containing HF, NH3, N2, and Ar, and can be performed, for example, at pressures ranging from 25 mTorr to 2000 mTorr and temperatures ranging from 15°C to 200°C, preferably below 100°C, and within the temperature ranges discussed previously herein. The subsequent thermal treatment or sublimation can be performed, for example, at pressures ranging from 1000 mTorr to 2000 mTorr and temperatures ranging from 70°C to 200°C, while supplying N2 and Ar to the chamber, preferably without an etchant gas (e.g., without introducing a halogen gas during the thermal treatment). The thermal treatment is performed in a non-plasma environment without introducing HF and NH3, which were introduced during the reaction of the modified surface.

[0033] FIG. 4 is a flowchart or algorithm according to an example of a process disclosed herein, which may be utilized or implemented by one or more of the controllers described above. As shown, in step S10, a substrate is provided, which may include a SiN layer or low-k dielectric material, e.g., for layer 110. In step S12, a plasma containing at least O and F is formed, and ions are removed from the plasma, as shown in S14. In S16, etching and modification are performed using radicals from the plasma to provide a modified surface of the SiN or low-k material. Typically, this step removes a portion of the material, and the remaining surface is modified to include increased amounts of oxygen and fluorine. However, this step could also be performed as a modification step without necessarily removing material. Step S16 is performed with the ion-removed plasma, so that the radicals from the plasma modify and etch.

[0034] In step S18, the modified surface is then treated or reacted with gas phase chemistry (without or without plasma) to form a reactive modified surface. This can be, for example, using gas chemistry of HF, NH, N, and Ar. The reactive modified surface is then removed using a thermal treatment without plasma, for example, in an environment of Ar and N, as shown in S20.

[0035] 5A and 5B illustrate other applications or examples that can utilize the processes disclosed herein. In certain manufacturing processes or process flows, it is important to selectively cover certain features while other features are processed. For example, as shown in FIG. 5A , certain features, such as a gate architecture feature or device generally represented at 500, are covered with a film, e.g., an organic film 600 such as an OPL, while other features, generally represented at 700, are not covered with organic film 600, allowing feature 700 to be further processed separately from feature 500. Feature 500 is covered by liner 502, which in turn protects the feature during deposition or other processing of film 600. Thus, a substrate can include a first set of features or devices in a first region and a second set of features or devices in a second region. In the example of FIGS. 5A and 5B , the process can be utilized to remove liner 702 in order to process feature or device 700 separately from feature 500. The liner 702 can be, for example, SiN or a low-k material (e.g., SiOCN, containing one or more of Si, N, C, O, or H), and the liner can be removed according to the processes disclosed herein. Removal of the liner 702 employs the same general processing as disclosed herein, but preferably uses a lower oxygen content, such as 1-5% oxygen by volume flow, for the etching and modification steps (steps S12-S16 described above) to avoid damage to the organic or OPL 600. The fluorine-containing gas for the etching modification, as disclosed, can be in the 5%-25% range previously disclosed herein, preferably toward the higher portions of those ranges (e.g., 15-25% or 20-25% NF3). Additionally, the etching and modification steps are preferably performed at lower temperatures, such as below 100°C, preferably below 50°C, e.g., 35°C-50°C.After etching and modification, the liner 702 is reacted in a gas phase chemical step (no plasma) to form a reactively modified surface, after which the temperature is increased to remove the liner 702 and provide exposed features or devices, as shown in FIG. 5B, which can then be processed separately from the features or devices covered by the organic film or layer 600. The thermal treatment temperature can be, for example, in the range of 100° C. to 250° C. Lower temperatures may be desirable (e.g., 70° C. to 150° C. or 100-150° C.) to avoid damage or degradation of the organic material or OPL.

[0036] Figures 6A and 6B illustrate the advantage of this method in that the composition of the processed material is substantially the same compared to before processing. In other words, after the etching modification and subsequent post-processing, the material properties in terms of composition percentage are substantially the same. Therefore, material can be removed in one or more iterations to leave a desired amount of material or material in a desired location (e.g., material remaining as a spacer in a recess), and despite the processing to remove the material, the remaining material retains its integrity in terms of the composition of the material used. Figures 6A and 6B also demonstrate the highly controllable nature of this process, in that significantly different amounts of modification or modification thicknesses can be obtained (as indicated by the different amounts of oxygen and fluorine in the different etching modifications). The amount of modified material corresponds to the material or thickness removed in the post-processing (PST, which includes gas-phase reaction and thermal treatment). Because typically all of the modified surface or modified material is removed during PST, controlling the etching modification allows for a high degree of control over the overall process in terms of the amount of material or material thickness removed in a given iteration of the process steps. Thus, very fine etching (e.g., to provide spacer surfaces 103s that are slightly recessed relative to adjacent layer surfaces 104s) can be more easily achieved. Furthermore, despite the process variability for etch modification, the etched material returns to a state remarkably similar to its as-received state after PST for each of the processes compared to one another.

[0037] FIG. 6A shows the beneficial results for the first dielectric material, SiCN, while FIG. 6B shows the beneficial results for another low-k material, SiBCN, with similar beneficial results, corresponding to a material doped with boron to provide SiBCN. Three different etch modification steps were used for each, varying the degree of aggressiveness of the etch and surface modification steps. As discussed above, more aggressive etch and modification (each iteration) can provide a thicker modified surface and therefore remove a greater amount of material per iteration (each iteration includes an etch modification step and a post-processing step in which the modified surface reacts to form a reactive modified surface, which is then removed with a thermal treatment). More aggressive etch modifications involve higher temperatures and may include more O and / or F compared to less aggressive modifications. In FIGS. 6A-B, Etch Mod2 is more aggressive than Etch Mod1, and Etch Mod3 is more aggressive than Etch Mod2.

[0038] The bar graphs on the left side of each figure show the as-received composition, with region 1 representing the silicon content, region 2 representing the oxygen content, region 3 representing the nitrogen content, and region 4 representing the carbon content. Region 5 represents the fluorine content, and region 6 represents the boron content. In bars where the content is not shown or is negligible, these are not identified numerically. For the remaining materials, atomic weight percentages are identified by atomic weight to two decimal places. The graphs also show that the etching and modification steps are substantially limited to the region of the modified surface that is removed during post-processing steps, thus maintaining the integrity of the material.

[0039] As shown in Figure 6A, after the etch modification and post-treatment (PST), the amounts of Si, N, and C are all within a difference of less than 5% compared to the as-received composition. Additionally, for the boron-doped low-k material (Figure 6B), the changes (for Si, N, and C) are also less than 5%. The change in atomic weight percentages of Si, N, and C can actually be less than 2%, or even less than 1%, in terms of atomic weight, of the overall composition of the post-PST material compared to the as-received material. However, the amounts of O and F change significantly for different etch modifications (before PST), demonstrating the controllability of the process.

[0040] Etch Modification 1 was performed at 20°C, Etch Modification 2 at 50°C, and Etch Modification 3 at 70°C. As can be seen, the fluorine (region 5) and oxygen (region 2) content increased significantly as a result of the etch modification, with the amount of increase varying significantly depending on the aggressiveness of the treatment, with the increase being more pronounced for the more aggressive Etch Modification 3 compared to Etch Modification 2, which shows a larger increase compared to Etch Modification 1. Nevertheless, after the etch modification and post-treatment, as represented by Etch Mod 1 PST, Etch Mod 2 PST, and Etch Mod 3 PST, respectively, the materials essentially returned to their as-received composition after post-treatment, although there are differences between the post-Etch Mod and pre-Etch Mod PST. Thus, Figures 6A and 6B demonstrate the ability of the modifications resulting from the etch modification step to vary the amount or thickness of the modification, providing the ability to vary the amount of material removed for a given iteration of etch modification and post-treatment PST. However, the material compositions after modification and post-treatment are remarkably similar to each other and to the as-received composition, so that the integrity of the material is substantially unaffected.

[0041] The disclosed methods and apparatus can be used in a variety of applications including nFETs, pFETs, nanosheets, GAAs, FinFETs, CFETs, and other devices or device features.

[0042] It is to be understood that modifications and variations not inconsistent with the teachings herein may be incorporated. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise or with variations on the embodiments disclosed herein.

Claims

1. To provide a substrate including a spacer layer formed of a spacer material, Etching and surface modification step, comprising etching the surface of the spacer material to remove a portion of the spacer material, modifying the remaining surface of the spacer material to provide a modified surface having increased oxygen and fluorine content compared to the spacer material before the etching and modification step, and performing the etching and surface modification step, which includes exposing the spacer material to a plasma containing at least fluorine and oxygen. After the etching and surface modification steps, in order to remove the modified surface of the spacer material, a vapor-phase chemical etching is performed that is not in the plasma. Includes, The gas-phase chemical etching comprises a first step and a second step, wherein the first step uses HF and NH3, the second step uses Ar and / or N and does not use HF or NH3, and the second step is performed at a higher temperature than the first step. Substrate processing method.

2. The etching and surface modification steps described above are: To form the first plasma, Removing ions from the first plasma to form a second plasma that is ion-free or contains fewer ions than the first plasma, The spacer material is exposed to the second plasma, thereby causing the radicals of the second plasma to etch the spacer material and modify the remaining surface to provide the modified surface. The method according to claim 1, including the method described in claim 1.

3. The method according to claim 2, wherein the gas-phase chemical etching comprises reacting the modified surface with a gas-phase chemical at 100°C or below to form a reaction-modified surface.

4. The method according to claim 3, wherein the reaction of the modified surface is carried out at a temperature of 0°C to 85°C in order to form the reaction modified surface.

5. The method according to claim 4, further comprising, after reacting the modified surface at 0°C to 85°C, raising the temperature of the substrate to a range of 100°C to 250°C and performing heat treatment to remove the reaction-modified surface.

6. The method according to claim 3, wherein the gas used for etching and surface modification is different from the gas used during the reaction of the modified surface.

7. The spacer material contains one or more of Si, N, C, O, or H, and the spacer material does not contain metal. The method according to claim 2, wherein the second plasma comprises oxygen radicals and fluorine radicals.

8. The method according to claim 7, wherein the substrate comprises a plurality of layers adjacent to the spacer layer and covered by the spacer layer prior to the etching and surface modification steps, each of the plurality of layers having at least one of a lower oxygen content or a higher carbon content compared to the modified surface of the spacer layer.

9. The plurality of layers comprises a laminate of alternating first and second layers, each first layer having a higher Ge content than each second layer, and each second layer having a higher Si content than each first layer. Prior to the etching and surface modification steps, one of the first layer and the second layer is recessed with respect to the other of the first and second layers, so that a recess is provided in one of the first and second layers. Prior to the etching and surface modification steps, the spacer material is filled into the recess and covers both sides of the first and second layers. After the etching and surface modification, and the gas-phase chemical etching, the spacer material remains in the recess to form a spacer, the outer dimensions of the spacer are recessed from the other outer dimensions of the first and second layers, and the other outer surface of the first and second layers is exposed. The method according to claim 8.

10. The substrate includes a plurality of adjacent layers adjacent to the spacer layer and covered by the spacer layer prior to the etching and surface modification steps, each of the plurality of adjacent layers having at least one of a lower oxygen content or a higher carbon content compared to the modified surface. The plurality of adjacent layers comprise a laminate of alternating first and second layers, each first layer having a higher Ge content than each second layer, and each second layer having a higher Si content than each first layer. Prior to the etching and surface modification steps, one of the first and second layers is recessed relative to the other of the first and second layers, so that a recess is provided in one of the first and second layers. Prior to the etching and surface modification steps, the spacer material is filled into the recess and covers both sides of the first and second layers. After the etching and surface modification steps and one or more iterations of the gas-phase chemical etching, the spacer material of the spacer layer remains in the recess to form a spacer, the outer dimensions of the spacer are recessed from the other outer dimensions of the first and second layers, and the other outer surfaces of the first and second layers are exposed. The method according to claim 5.

11. The formation of the first plasma is carried out with a volume flow rate of 5% to 25% NF3, 25% to 55% oxygen, 25% or less hydrogen, and the remaining argon or nitrogen gas. The above reaction involves HF and NH ３ That was the reaction, The heat treatment is carried out in an environment consisting of argon and / or nitrogen. The method according to claim 5.

12. The etching and surface modification are carried out by forming a plasma with NF3 and oxygen, removing ions from the plasma, and then exposing the spacer material to the plasma after the ions have been removed. The method according to claim 1.

13. The etching and surface modification are performed at temperatures ranging from 15°C to 85°C. The first step is performed at a temperature in the range of 0°C to 50°C. The second step is performed at a temperature in the range of 70°C to 300°C. The method according to claim 12.

14. A method for processing circuit boards, To provide a substrate having a layer thereon, wherein the layer is formed of a material containing at least one of Si, N, C, O, or H. Forming a first plasma containing at least oxygen and fluorine, The process involves removing ions from the first plasma to form a second plasma containing oxygen radicals and fluorine radicals, The modification involves modifying the surface of the layer with the second plasma to form a modified surface, wherein the modified surface has increased levels of fluorine and oxygen compared to the material of the layer before modification. To remove the modified surface, gas-phase chemical etching is performed, wherein the gas-phase chemical etching is performed in a non-plasma environment, and the gas-phase chemical etching is performed in a non-plasma environment. The modified surface is reacted with a gas-phase chemical substance at a temperature of less than 100°C to form a reaction-modified surface. The temperature of the substrate is raised to over 100°C and heat-treated to remove the reaction-modified surface, Methods that include...

15. The gas composition of the environment in which the substrate is placed is different from that for the reaction, with respect to the reforming process. The gas composition for the reaction is different from that for the heat treatment. The temperature during the aforementioned modification process is in the range of 0°C to 85°C. The temperature during the reaction is in the range of 0°C to 85°C. The temperature during the heat treatment is in the range of 100°C to 250°C. The method according to claim 14.

16. The layer does not contain metal, the gas introduced during the formation of the first plasma does not contain metal, and the gas introduced during the reaction does not contain metal. The gases introduced during the reaction are HF and NH ３ including, The method according to claim 15.

17. The heat treatment is performed for 60 seconds or more, and during the heat treatment, the pressure is maintained in the range of 1000 milliliters to 5000 milliliters. During the formation of the first plasma, the gas is supplied at a volumetric flow rate of 5% to 25% NF3, 25% to 55% oxygen, and less than 25% hydrogen, and the pressure is 10 milliliters to 1000 milliliters. During the heat treatment for 60 seconds or more, HF and NH ３ It is not supplied to the environment in which the circuit board is placed. The method according to claim 16.

18. The substrate comprises a first region and a second region, the first region providing a first device covered by the layer, the layer being exposed before modification, the second region providing a second device, the second device being covered by the layer, the layer being covered by an organic layer, After the modification and after the gas-phase chemical etching including the reaction and heat treatment, the layer in the first region is removed, the layer in the second region is not removed, and the organic layer in the second region remains covering the layer in the second region. While the first plasma is being formed, an oxygen-containing gas is supplied at a volume flow rate of 1% to 5% of the total gas flow, and a fluorine-containing gas is supplied at a volume flow rate of 5% to 25% of the total gas flow. The heat treatment is performed at a temperature in the range of 70°C to 150°C. The method according to claim 14.

19. The substrate includes a first set of a first plurality of features and a second set of a second plurality of features, wherein the second set of the second plurality of features is covered by an organic layer, and the first set of the first plurality of features is not covered by the organic layer. The layer is a liner formed on the first set of the first plurality of features, which is removed by modification and gas-phase chemical etching. The method further includes removing the organic layer after removing the liner. The method according to claim 14.

20. The substrate includes a plurality of adjacent layers adjacent to the layer before modification and covered by the layer, each of the plurality of adjacent layers having at least one of a lower oxygen content or a higher carbon content compared to the modified surface. The plurality of adjacent layers comprise a laminate of alternating first and second layers, each first layer having a higher Ge content than each second layer, and each second layer having a higher Si content than each first layer. One of the first and second layers is recessed relative to the other of the first and second layers, so that a recess is provided in one of the first and second layers. Prior to the modification, the layer fills the recess and covers both sides of the first and second layers. After the heat treatment, the material of the layer remains in the recess to form a spacer, the outer dimensions of the spacer are recessed from the other outer dimensions of the first and second layers, and the other outer surfaces of the first and second layers are exposed. The method according to claim 14.

21. To provide a substrate including a spacer layer formed of a spacer material, Etching and surface modification step, comprising etching the surface of the spacer material to remove a portion of the spacer material, modifying the remaining surface of the spacer material to provide a modified surface having increased oxygen and fluorine content compared to the spacer material before the etching and modification step, and performing the etching and surface modification step, which includes exposing the spacer material to a plasma containing at least fluorine and oxygen. After the etching and surface modification steps, the spacer material is subjected to vapor-phase chemical etching, which is not in the plasma, in order to remove the modified surface, wherein the vapor-phase chemical etching includes reacting the modified surface at a temperature of 0°C to 85°C to form a reaction modified surface. After the modified surface is subjected to the reaction at 0°C to 85°C, the temperature of the substrate is raised to a range of 100°C to 250°C, heat treatment is performed, and the reaction-modified surface is removed. including, Substrate processing method.

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