Surface modification for selective isotropic etching

Abstract

A surface of a substrate is modified, wherein the substrate comprises at least two different layers or films of different materials. The modified layer is then selectively converted into a protective layer on one of the layers while etching the other layer.

Description

[0001] Cross-references to related patents and applications

[0002] This application claims priority to and the benefit of the filing date of U.S. non-provisional patent application No. 17 / 945,897, filed on September 15, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to processing of substrates and related apparatus, particularly where plasma etching or vapor phase etching is used as part of the process. Background Art

[0004] Etching of semiconductor materials often requires selectively etching one material relative to (or in relation to) another material when the two materials are arranged in the same environment, such as a plasma or vapor phase chemical etching environment. Selective etching can be particularly challenging because during certain portions of the manufacturing process, it may be necessary to selectively etch a first material relative to a second material, while in different portions of the process, different etch selectivities may be required, including selectively etching the second material relative to the first material, or selectively etching another material relative to the first and / or second material. In addition, selective etching can be problematic in complicating the overall process due to challenges with increasingly smaller device and layer sizes, requirements for etching accuracy, and the need to avoid damage. Summary of the invention

[0005] The present invention provides an advantageous method and related apparatus for selective etching, wherein an initial treatment process is provided, and thereafter, the treatment is advantageous for various selectivities of different materials and different material combinations. In an example, a first and a second film or layer is provided on a substrate, wherein the first film and the second film are formed of different materials, each containing silicon. The treatment is provided on both films to provide a modified surface on both films. In an example, the treatment is performed in a non-plasma environment and is followed by a thermal treatment. After the thermal treatment, in a subsequent etching process, the modified surface is selectively converted into a protective layer or an etch stop layer on the surface of one of these materials, while etching another material (in a plasma etching chemistry or a gas phase etching chemistry), thereby providing selective etching. The initial treatment and / or the etching process can be changed to produce various selectivity combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figures 1A-1C Treatment or surface modification and etching methods are shown;

[0007] Figure 2 are examples of devices that may be used with the present invention;

[0008] Figure 3is a flow chart or algorithm illustrating an example of a process; and

[0009] Figure 4A and 4B Additional processing is shown. DETAILED DESCRIPTION

[0010] Aspects and advantages of the present invention will be apparent from the description herein. It should be understood that, in practicing the present invention, certain aspects or advantages may be utilized without using other aspects or advantages. Therefore, variations and / or subsets of the features or advantages of the examples described herein may be used to practice the present invention.

[0011] Examples of shrinking processes are described, however, it should be understood that the present invention can also be used in other applications where selective etching of two different materials is desired. For example, aspects of the method of the present invention can be used for various n-type and p-type field effect transistor (nfet and pfet) operations, SiGe and Si nanosheet manufacturing, channel release or channel trimming, penetration process steps, or removal of oxide layers. The methods described herein can improve the functionality of the surface for subsequent processing, such as to improve selectivity or impart selectivity, and to avoid or reduce damage. In addition, the methods described herein can make the surface hydrophobic so that subsequent steps can be more effectively etched with gases containing hydrogen, oxygen and fluorine, such as aerosolized H2O and fluorine-containing gases, such as silicon oxide. In addition, although examples of materials are described herein, it should be understood that alternative materials can also be used. In addition, in some examples, elements or materials are described as not present. This should be understood to mean that such elements or materials are not intentionally introduced, however, trace amounts may be present depending on the purity of the materials used and / or as a result of degassing or releasing elements from other materials during processing.

[0012] The disclosed examples can provide selective isotropic etching of different materials and different material combinations relative to each other.

[0013] In the example, an initial surface treatment is provided for each of at least two layers or two films (a first film and a second film). Preferably, the treatment is a non-plasma gas phase treatment. As used herein, unless otherwise specified, gas phase is used to mean non-plasma processing, however, the gas phase may contain, for example, aerosolized components such as aerosolized water, and / or vapor phase components may also be used. After the initial treatment, a modified surface is generated and provided on the surfaces of these films, for example, on the side surfaces of two films. The modified surface is then selectively converted into a protective surface or protective layer on one of the films, while etching the other film, thereby providing selective etching of the unprotected film relative to the protected film. By changing which material is selectively converted or not protected, different etching selectivities of different materials can be provided. In addition, in some examples, different etching selectivities can be provided for different materials while utilizing the same or substantially the same pretreatment or surface modification steps. A series of additional selectivity combinations can be provided by changes to the pretreatment and / or subsequent etching processes.

[0014] Although the films are formed of different materials, in an example, each of the films will be a silicon-containing film, wherein at least two films of different materials are provided. For example, the first film may contain epitaxial silicon, polysilicon, silicon oxide (of different qualities or types), or silicon germanium (SiGe). The second film may be selected from the same group, but will be different from the first film. The two different films may also include two different silicon oxide films. One of the films may also be a silicon nitride film.

[0015] refer to Figures 1A-1C , an example of an embodiment will be described. Figure 1A In the initial structure of the present invention, the substrate will include a semiconductor base 100, which may include, for example, a wafer or a substrate base, and an additional layer on the substrate base, which is below the material being processed as described herein. The material being processed in this example will include at least a first film 104 and a second film 102 provided in an alternating manner. In addition, there may be a mask 108, wherein the mask is formed, for example, by SiN, an inorganic material, or a low-k material. Although two films are shown with 102 and 104, it should be understood that other films may also be present. In the example, at least one of the films 102 and 104 is vertically above another in the film, and multiple films may be provided in an alternating arrangement. In addition, the film will be formed of different materials, wherein each of the films or layers 102 and 104 is a silicon-containing film. For example, the first film 104 may be formed of epitaxial silicon, polycrystalline silicon, silicon oxide, or silicon germanium (SiGe). The second film 102 may also be formed, for example, by epitaxial silicon, polycrystalline silicon, silicon oxide, or SiGe, wherein the second film is formed of a material different from the first film. In another example, one of the films may be a silicon nitride film.

[0016] In an initial processing step, a modified surface 116 is formed on the side surfaces of the first and second films, such as Figure 1B As shown. In a preferred example, the modified surface is formed in a gas phase non-plasma environment in which a gas containing hydrogen, fluorine and oxygen is introduced. For example, the processing gas may include HF, aerosolized H2O and a carrier gas such as argon and / or nitrogen. In an example, as a result of the treatment, the modified surface will contain hydrogen, silicon, and fluorine. In addition, if one of the films contains Ge (e.g., SiGe), the modified surface will typically also contain Ge in the region of the layer or film, so that the modified surface contains hydrogen, silicon, fluorine and germanium.

[0017] According to an example, the first film may comprise epitaxial silicon and the second film may comprise silicon germanium (SiGe), and the treatment will provide a modified surface 116 on the side surfaces of both layers, wherein the modified surface comprises H, Si, F and Ge on the side surface of the SiGe layer, and the modified surface on the side surface of the epitaxial silicon layer will comprise H, Si and F. As described earlier, the treatment environment will include an introduced gas, which may comprise hydrogen, fluorine and oxygen, and a carrier gas such as nitrogen and / or argon. The duration of the gas phase treatment may vary, but is preferably at least 10 seconds. The gas phase treatment may be carried out at a temperature in the range of -20°C to 200°C and at a pressure in the range of 10 mTorr to 4 Torr. For example, in the case where one of the films is epitaxial silicon and the other film is SiGe, the temperature may preferably be in the range of 0°C to 35°C, with a pressure in the range of 1 Torr to 4 Torr. Examples of gas flow rates may be 200 sccm to 1000 sccm of aerosolized H2O; 300 sccm to 1000 sccm of HF, and 100 sccm to 450 sccm of N 2。 Another fluorine-containing gas or a halogen-containing gas may also or alternatively be used, and an alternative carrier gas, such as argon, may also be used. In addition, although aerosolized H2O is provided in preferred examples, water may be provided in different forms, such as in vapor form. Alternative gases may also be used to provide a gas containing hydrogen and oxygen. Aerosolized H2O is currently preferred. In some examples herein, the gas present during processing will contain at least hydrogen, oxygen, and fluorine, and typically also a carrier gas such as argon and / or nitrogen.

[0018] After treatment to form the modified surface, an optional but preferred heat treatment is then also performed, primarily to remove residual water or water vapor. The heat treatment is preferably performed in an inert atmosphere (e.g., including nitrogen and / or argon, but without reactive gases, such as halogen-free gases). For example, the heat treatment can be performed at a temperature in the range of 100°C to 350°C, such as 100°C to 300°C, and preferably 100°C to 250°C, and a pressure in the range of 1 torr to 3 torr. Preferably, during the heat treatment, the gas flow comprising hydrogen, fluorine (or another halogen) and oxygen is interrupted.

[0019] After forming the modified surface 116 and the heat treatment, the modified surface is selectively converted to a protective surface, as shown at 116a. In the example shown, the modified surface 116 is converted to a protective surface or protective layer 116a adjacent to the first film 104, and the second film 102 is selectively etched relative to the first film to provide an indentation in the second film 102, so that the second film has an outer dimension that is smaller than the outer dimension of the first film. However, the selective conversion of the modified film to the protective film and the selective etching can be interchanged, for example, where the modified surface is converted to a protective surface or protective layer on the side surface of the second film 102, and the first film 104 is selectively etched to cause the first film to be indented relative to the second film.

[0020] With respect to the modified surface 116 on the film or layer to be etched later, the modified surface 116 can be removed or partially removed during the heat treatment step (before plasma etching or vapor etching) so that only the portion of the film 116 that remains during the plasma etching process or vapor etching is the portion of the layer 116 (or modified surface 116) that will then become the protective surface or protective layer 116a. Alternatively, if there are portions of the modified surface 116 adjacent to the film or layer to be etched after the heat treatment, then they are removed in the plasma or vapor etching process and the retracted film or layer is then etched. Due to the nature of the surface modification, in the area of ​​the layer to be etched, it will sublime (or partially sublime) in the heat treatment or will be removed in the etching.

[0021] As an example, where the film being indented (etched) comprises SiGe and the film being protected comprises epitaxial silicon, the etching gas chemistry may comprise fluorine (F) and a carrier gas such as argon in a vapor phase etch. In an example, the gas chemistry does not comprise nitrogen, and preferably will not comprise both nitrogen and hydrogen, because such gases may form nitrides on the surface of the SiGe layer or film, which may inhibit etching. Conversely, if the SiGe layer is to be protected, and the epitaxial silicon layer is to be etched, the plasma etching gas chemistry may comprise F, N, and H, and the modified surface may be converted to a germanium nitride surface that will protect the SiGe layer or film, and the epitaxial silicon may be etched selectively to the SiGe film.

[0022] In the example where the standby surface 116a or protective layer 116a protects the SiGe layer and Si is to be etched, an initial portion of the plasma process (e.g., lasting 5 to 25 seconds, preferably 8 to 20 seconds, more preferably 10 to 15 seconds) can be performed, wherein no fluorine (or another halogen) is introduced, while N and H are introduced, thereby converting the modified surface 116 to a protective surface or protective layer 116a, and thereafter, in a second portion of the plasma process, fluorine (or another halogen) can be introduced while continuing to introduce nitrogen and hydrogen, and etching the silicon-containing layer (in this example, epitaxial silicon). The first portion of the process (or first plasma) can be continuous with the second portion (or second plasma), except that a halogen (e.g., fluorine) is introduced in the second portion. The protective surface or protective layer 116a contains germanium nitride, which protects the SiGe layer during etching of the epitaxial silicon layer. The flow of the hydrogen or halogen containing gas may be periodically interrupted for a period of time as etching proceeds, while the flow of other gases (e.g., nitrogen and hydrogen) may continue to provide a protective coating for the newly exposed surfaces (as the recess forms, exposing the surfaces on the top and bottom of the protected film facing the recess, e.g., Figure 1C For example, after a first plasma without halogen, followed by processing with a plasma containing halogen (wherein the second portion lasts, for example, 5 to 30 seconds, preferably 8 to 25 seconds), the flow of halogen and / or plasma generation power can be interrupted for a period of time (e.g., for 8 to 20 seconds, preferably 10 to 15 seconds) while continuing the flow of hydrogen and nitrogen, and then resuming processing with the introduced halogen (fluorine) and applied plasma generation power.

[0023] A single-step etch (without periodic interruption of the fluorine- or halogen-containing gas) may also be used. In addition, where a two-step etch is used, the first and second steps may be alternated a predetermined number of times, or a number of times based on one or more sensed parameters (e.g., measured or detected etch amount, total etch time). In addition, in the case of a one-step or two-step etch, the initial modification may also be repeated periodically.

[0024] In the above examples, the same pretreatment (vapor phase) can be advantageously used to selectively etch epitaxial silicon relative to SiGe (e.g., using H, F, and N plasma etching chemistries), and conversely, to selectively etch SiGe relative to epitaxial silicon (e.g., using F and Ar etching chemistries, e.g., in a non-plasma vapor phase etch), where the etch selectivity of both is improved due to the pretreatment.

[0025] This may be advantageous in cases where the substrate may have different features or devices in different regions of the substrate. For example, a substrate may have a first region comprising a first device or a first group of devices in which an epitaxial silicon or other silicon layer forms a channel and then a germanium layer or SiGe is retracted and later released (removed); and a second region comprising a second device or a second group of devices in which a germanium or SiGe layer forms a channel and a silicon layer such as epitaxial silicon is retracted and later released. In the case of an example of the present invention, the same surface modification can be used for two devices and two regions of the substrate. Thereafter, different etching steps can be used for different devices or regions, and the unetched devices are covered, for example, with an organic material such as OPL. Advantageously, the selectivity of the two etches is improved by a pre-etching treatment.

[0026] Although the disclosed methods may be applied when one or both layers contain metal, according to some examples, one or both of the films or layers 102, 104 do not contain metal, and preferably, the treatment gas and / or etching process gas do not contain metal.

[0027] In another example, the first film and the second film can be different silicon oxides, for example, the first film can be a thermal oxide or TEOS, and the second layer can be an ALD oxide (atomic layer deposition silicon oxide). These can be etched relative to each other using the same pre-etch process as described herein. During etching (after pre-etch modification as discussed earlier herein), a fluorine-containing gas is introduced in the range of 500 sccm to 1500 sccm, wherein the etching gas also contains aerosolized H2O in the range of 100 sccm to 1000 sccm, preferably 200 sccm to 1000 sccm, and a carrier gas (nitrogen and / or argon, for example, 50 to 500 sccm, preferably in the range of 100 sccm to 450 sccm). This will provide selective etching of the ALD oxide selective to the thermal oxide (relative to the thermal oxide) in the vapor phase etch.

[0028] According to another example, the second layer or film may include silicon oxide, and the first film may include silicon nitride or a low-k dielectric. For example, the low-k dielectric (before treatment) may include one or more of silicon, oxygen, carbon, and hydrogen (e.g., SiCOH). The pretreatment may be as described earlier for temperature and pressure. In an example, a fluorine-containing gas may be introduced in a range of 500 sccm to 1500 sccm, an aerosolized H2O may be introduced in a range of 100 sccm to 500 sccm, and a carrier gas may be introduced in a range of 800 sccm to 2000 sccm. The heat treatment may then be performed as discussed earlier. The etching process may include a fluorine-containing gas (e.g., 10 sccm to 300 sccm), a catalyst-containing gas such as NH3 (e.g., 20 sccm to 300 sccm), and a carrier gas such as argon (50 sccm to 500 sccm) in a vapor phase etch, wherein the pressure is preferably in the range of 20 mTorr to 800 mTorr and the temperature is preferably in the range of 20°C to 140°C.

[0029] In another example, the first film can be a thermal oxide or TEOS, and the second film can be SiN. In this example, SiN can be etched relative to thermal oxide, wherein the pretreatment preferably includes 300 sccm to 800 sccm of a fluorine-containing gas, 100 sccm to 500 sccm of aerosolized H2O, and 20 sccm to 500 sccm of a carrier gas (e.g., nitrogen and / or argon), and the temperature and pressure as in the previous example. The thermal treatment can be as previously described. The main etch can be a plasma etch, for example, with an RF power of 400 watts to 800 watts, preferably with a remote plasma, wherein the process gas includes hydrogen (10 sccm to 100 sccm), oxygen (100 sccm to 600 sccm), and a fluorine-containing gas (10 sccm to 75 sccm), a pressure of 50 mTorr to 500 mTorr, and a temperature in the range of 10°C to 90°C to provide a highly selective etch of SiN relative to thermal oxide, wherein improved selectivity is provided by the pre-etch treatment.

[0030] Table 1 further summarizes Examples 1-11 using the method of the present invention. In Table 1, Film 2 is the layer or film that is selectively etched. In other words, Film 2 is etched preferentially (or at a higher etching rate) relative to Film 1. For example, in Figures 1A to 1C In the examples, film 2 corresponds to layer 102, and film 1 corresponds to layer 104. Table 1 identifies the process conditions for the modification and also the subsequent etching. As indicated, according to these examples, the modification is gas phase (as indicated in brackets), and the etching can be gas phase or plasma etching (also indicated in brackets). Table 1 lists the gas flow rates of the gases used in the examples, and also lists examples of other (alternative or additional) gases.

[0031] Table 1

[0032]

[0033]

[0034]

[0035]

[0036]

[0037] Figure 2 An example of a processing chamber is shown in which one or more processing operations disclosed herein can be utilized. For plasma or gas phase processing, a gas supply GS204 is provided, which may include one or more supply lines and a reservoir or source to accommodate and provide a source of processing gas. In order to form a plasma, at least one power supply 202 is preferably provided, which may be, for example, a radio frequency (RF) power supply to power an electrode 218, and the electrode may form a plasma with a process gas introduced from a gas supply or gas source GS204. For example, the process gas may be introduced through an electrode 218 arranged in a showerhead, however, alternatively or in addition, the process gas may be introduced at other locations. It should be understood that the number of electrodes may vary, and an alternating plasma generation source may also be utilized, for example, where an induction power supply or a microwave power supply is used to generate plasma. In addition, for gas phase etching, no electrode and plasma generation power is required.

[0038] In the example shown, the plasma can be formed as a remote plasma, for example, where a first plasma is generated as indicated by P1, and when the plasma generated in the first chamber or chamber portion 210 is transferred to the second chamber or second chamber portion 212, ions are removed, for example, by a grid or grid device 230 for removing ions, so that the radicals in the plasma P2 are mainly used for plasma processing of the substrate 222 present on the substrate support 220. However, it should also be understood that the plasma can be generated in the same chamber or chamber portion in which the substrate is present. Therefore, although it may be preferred to use a remote plasma in some examples to process the substrate using radicals, it is optional and the element (e.g., grid or grid device) 230 can be eliminated if desired. In addition, for gas phase etching, the structure 230 is also unnecessary. The substrate 222 is mounted on the substrate support 220, which can electrostatically attract the substrate 222. In the case of using a remote plasma or performing gas phase etching, the support 220 (and the region 220) does not need to be supplied with plasma generation power. However, it is also possible to apply bias power and / or plasma generation power to an electrode of the substrate holder 220 or the substrate holder 200 , wherein plasma is generated in a region where the substrate is positioned.

[0039] A controller 200 is provided for controlling various operations and processes as described herein. The controller 200 may include, for example, a processor or computer, and a memory that may include a non-transitory computer readable memory. It should be understood that the controller may include a centralized controller, and multiple controllers or sub-controllers that may control different chambers or chamber components. In addition, the controller may store recipe data and data about substrates or wafers to control substrate transfer operations, and / or update or modify processes based on feedback or measurement data of previously processed substrates (or data unique to a specific substrate being processed or to be processed).

[0040] A vacuum pump VP 224 is provided to exhaust process gases and, in conjunction with the incoming gas flow, may also vary the pressure within one or more chambers. Temperature control TC is indicated at 206 and may include various temperature, heating or cooling means for heating and / or cooling the process chamber and / or substrate support 220. For example, electrical heating may be provided in the substrate support 220 and / or fluid heating or cooling (or heat exchange) may also be provided in the substrate support 220. Similarly, heating and / or cooling means may be provided in the chamber walls or chamber wall portions 214, 216, including electrical and / or fluid cooling or heat exchange elements.

[0041] refer to Figure 3, provides an overview of the process as disclosed herein, which may be provided as an algorithm, for example, for use in a process controlled by a controller 200 of a process apparatus. Figure 3 An overview of the process is shown, but further details of the process under the control of the controller may be provided as disclosed herein.

[0042] As indicated by S10, a substrate having a first layer and a second layer, for example, in an alternating stacking arrangement, is initially provided. The layers will be formed of different materials, preferably, wherein each of these materials contains silicon. For example, as discussed earlier, a layer may contain a material selected from the group consisting of: epitaxial silicon, polysilicon, SiGe, or silicon oxide, and another layer may be formed of a different material selected from the group consisting of: epitaxial silicon, polysilicon, SiGe, or silicon oxide. One of the films may also contain silicon oxide and the other may contain different silicon oxides. According to an example, one of the layers or films may contain a silicon nitride layer or film. According to another example, the substrate may also include different devices (e.g., different stacking arrangements of materials) in different regions, for example, in a first region, there are one or more first devices each having a first layer (or film) and a second layer (or film), and in a second region, one or more second devices having a third layer or film and a fourth layer or film are provided. These devices may have different layers requiring different selectivities, for example, where the first layer is etched relative to the second layer (selectively to the second layer) in the first device, and the third layer is etched relative to the fourth layer in the second device, and where the required selectivity is different for different devices. For example, one of the devices may require selective etching of SiGe relative to Si, while the other device requires selective etching of Si relative to SiGe. In the case of the method herein, the same initial treatment may be provided for the first device and the second device, wherein the first layer, the second layer, the third layer, and the fourth layer are exposed to the treatment. Thereafter, a different etching process may be used for the first device compared to the second device, for example, plasma etching for the first device and gas phase non-plasma etching for the second device to obtain the desired etching selectivity. According to the advantages of the method of the present invention, the selectivity of the two etchings is improved by a pre-etching treatment according to the method disclosed herein. During the etching of one device (or multiple devices), the other may be covered with, for example, a carbon-containing layer such as OPL.

[0043] As indicated by S12, the gas phase treatment is initially performed so as to provide a modified surface on the surface of each of the first layer and the second layer, for example, on the side surfaces of the first layer and the second layer, such as Figures 1A to 1C116 as shown in the figure. Then, as indicated by S14, a heat treatment is performed to remove residues or residual water vapor. In some examples, the heat treatment can also remove portions of the modified surface 116, while other portions of the modified surface 116 are not removed by sublimation and later become a protective surface or protective layer (116a). In the case where the heat treatment does not remove portions of the modified surface 116 adjacent to the layer to be etched, these portions are removed in a plasma or vapor phase etching process S16. In the plasma process, the portions of the layer that are not etched (or protected) are converted into a protective layer 116a, while the etched layer (102) is etched, for example, with a fluorine or halogen-containing gas in an etching process.

[0044] After etching, a heat treatment at a temperature higher than that during etching, for example in the range of 100° C. to 250° C., is preferred, in particular for vapor phase etching.

[0045] Figure 4A and 4B For example, as described earlier Figures 1A to 1C Additional processing may occur after forming the indentation as shown in FIG.

[0046] Figure 4A and 4B The arrangement includes, for example, a Ge (or SiGe) containing layer 104, wherein the Si containing layer 102 is between the layers 104, and wherein the Si containing layer has been retracted as described earlier. Region 108 can be a mask, such as a hard mask, and region 107 can initially include a dummy gate, which is later removed and a gate metal is deposited. After the retraction process discussed earlier, a spacer layer 110 is deposited to provide an inner spacer layer 110. Layer 110 can be formed, for example, of a spacer material such as SiN or a low-k dielectric. The inner spacer layer 110 is then partially removed so that the spacer 103 remains in the previously formed retraction or retraction portion as discussed earlier. Layer 102 can then be removed (channel release) so that the channel 104 remains formed by the Ge or SiGe containing layer, and the area previously occupied by the dummy gate 107 and the Si containing layer 102 can then be filled with gate metal. Furthermore, when the inner spacer layer 110 is removed or etched to leave the spacer 103, the spacer 103 should be retracted relative to the outer surface of the Ge or SiGe containing layer or channel 104 so that the outer surface of the spacer 103s has an outer dimension that is smaller than the outer surface or outer dimension 104s of the layer 104.

[0047] Although the present invention has been discussed earlier with respect to etching to form a recess, the present invention may also be used, for example, for channel release to remove layer 102 ( Figure 4A and 4B) while protecting layer 104 (e.g., SiGe layer). As another alternative, the present invention can be applied to etch spacer material 103 selectively to or relative to layer 104 (while protecting layer 104) so ​​that the remaining portion of the inner spacer layer 110 is etched and the retracted outer surface 103s of the spacer is retracted relative to the outer surface 104s of the Ge-containing layer (or SiGe).

[0048] It should be understood that other applications including features of the examples disclosed herein may be utilized. For example, the method may be applied to liner removal, mask removal or mask trimming, channel trimming, or other processing operations where selective etching is desired.

[0049] Although the present disclosure describes specific process / method steps as occurring in a particular order, the present disclosure contemplates process steps occurring in any suitable order. Although the present disclosure has been described with reference to the illustrative embodiments, this description is not intended to be interpreted in a restrictive sense. Various modifications and combinations of the illustrative embodiments and other embodiments of the present disclosure will be apparent to those skilled in the art with reference to the description. Therefore, the appended claims are intended to cover any such modifications or embodiments.

Claims

1. A method for selective etching, the method comprising: providing a substrate having a film stack thereon, the film stack comprising a first film and a second film, wherein one of the first film or the second film is vertically above the other of the first film or the second film; The first film is formed of a material different from that of the second film, and the first film and the second film each include one of epitaxial silicon, polysilicon, silicon oxide, silicon germanium, or silicon nitride, and the first film and the second film each include a side surface; treating the side surfaces of the first film and the second film to form a first modified surface on the first film and a second modified surface on the second film, wherein the treatment is a gas-phase non-plasma treatment with a gas containing hydrogen, fluorine, and oxygen; After the treatment, an etching process is performed, which converts the first modified surface into a protective surface and selectively etches the second film relative to the first film to remove a portion of the second film.

2. The method of claim 1, wherein: The etching process is a plasma process that etches the second film to form a recessed portion in the second film so that an outer dimension of the second film is smaller than an outer dimension of the first film.

3. The method of claim 1, wherein: The gases in this process include HF, aerosolized H2O and a carrier gas.

4. The method of claim 3, wherein: The treatment is carried out at a temperature ranging from -20°C to 200°C and at a pressure ranging from 10 mTorr to 4 Torr.

5. The method of claim 4, wherein: The treatment is carried out at a temperature ranging from 0°C to 35°C.

6. The method of claim 5, further comprising, after the treating and before the etching, performing a heat treatment at a temperature in the range of 100°C to 350°C.

7. The method of claim 1, wherein: The etching process is a non-plasma vapor phase etching.

8. The method of claim 1, wherein: the film stack including the first film and the second film forming one of a first plurality of devices in a first region of the substrate, the substrate further including a second plurality of devices in a second region of the substrate, and wherein both the first plurality of devices and the second plurality of devices are exposed to the process; wherein the etching process is a plasma etch performed on the first plurality of devices but not on the second plurality of devices; as well as Wherein after the processing, the second plurality of devices are exposed to a gas phase non-plasma etch.

9. A method of selective etching, the method comprising: providing a substrate having thereon a first film and a second film, one of the first film and the second film being vertically above the other of the first film and the second film, wherein the first film is formed of a material different from that of the second film, and the first film and the second film each contain silicon, and the first film and the second film each have a side surface; treating the substrate to form a first modified surface on a side surface of the first film and a second modified surface on a side surface of the second film; An etching process is performed that converts the first modified surface into a protective layer, removes the second modified surface, and etches the second film so that the second film is retracted relative to the first film.

10. The method of claim 9, wherein: The first film is formed of a first material selected from the group consisting of epitaxial silicon, polysilicon, silicon germanium, silicon nitride, and silicon oxide; and The second film is formed of a second material that is different from the first material and is selected from the group consisting of: epitaxial silicon, polysilicon, silicon germanium, silicon nitride, and silicon oxide.

11. The method of claim 9, wherein: The treatment is performed in a non-plasma environment at a temperature ranging from -20°C to 200°C and at a temperature ranging from 10 mTorr to 4 Torr.

12. The method of claim 9, wherein: The process is performed in a non-plasma environment using a process gas containing halogen, oxygen and hydrogen.

13. The method of claim 9, wherein: The treatment is performed in a non-plasma environment with a treatment gas comprising aerosolized H2O, HF and a carrier gas.

14. The method of claim 9, further comprising increasing the temperature of the substrate to perform heat treatment after the treating and before the etching process, the heat treatment being performed at a temperature ranging from 100°C to 300°C and in an environment in which halogen is not introduced.

15. The method of claim 14, wherein: During this etching process, halogen and carrier gas are introduced and nitrogen is not introduced.

16. The method of claim 14, wherein: During this etching process, halogens, nitrogen and hydrogen are introduced.

17. The method of claim 9, wherein: The treatment is carried out at a gas flow rate of HF in the range of 300 sccm to 1000 sccm and aerosolized H2O in the range of 200 sccm to 1000 sccm, and a carrier gas containing argon and / or nitrogen is also introduced.

18. The method of claim 9, wherein: The substrate includes a first plurality of devices and a second plurality of devices, and the first plurality of devices and the second plurality of devices are each exposed to the process, and after the process, the first plurality of devices are exposed to a gas phase non-plasma etch and the second plurality of devices are exposed to a plasma etch.

19. A method of selective etching, the method comprising: Providing a substrate, the substrate comprising a first plurality of devices in a first region and a second plurality of devices in a second region, the first plurality of devices comprising a first layer and a second layer, the first layer being formed of a material different from that of the second layer, the second plurality of devices comprising a third layer and a fourth layer, the third layer being formed of a material different from that of the fourth layer; treating the first plurality of devices and the second plurality of devices with a non-plasma gas phase chemistry comprising hydrogen, halogen, and oxygen; After the processing, exposing the first plurality of devices to a plasma etching process to selectively etch the first layer relative to the second layer; as well as After the processing, the second plurality of devices are exposed to a gas phase non-plasma etch to selectively etch the third layer relative to the fourth layer.

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