Substrate processing method, substrate processing device, and method for manufacturing transistor of nanowire or nanosheet

Abstract

The present invention aims to appropriately shorten the processing steps in processing a substrate having alternately stacked silicon layers and silicon germanium layers. The present invention provides a substrate processing method, comprising selectively modifying the surface of the exposed surface of the silicon germanium layer using a plasma-formed processing gas containing fluorine and oxygen to form an oxide film.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method, a substrate processing apparatus, and a method for manufacturing a transistor of nanowires or nanosheets. Background Art

[0002] Patent Document 1 discloses a method for selectively etching a silicon germanium layer between a silicon germanium layer and a substrate where, for example, a silicon layer is exposed. The etching method described in Patent Document 1 simultaneously supplies a fluorine-containing gas and a chlorine trifluoride gas to the substrate in a vacuum atmosphere, thereby achieving a uniform etching rate and a consistent etching amount of the silicon germanium layer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-170380 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The technology according to the present disclosure can appropriately shorten the processing steps in processing a substrate in which silicon layers and silicon germanium layers are alternately stacked.

[0008] Solutions for solving problems

[0009] One embodiment of the present disclosure is a method for processing a substrate having alternately stacked silicon layers and silicon germanium layers. The substrate processing method uses a plasma-formed processing gas containing fluorine and oxygen to selectively modify the surface layer of the exposed surface of the silicon germanium layer to form an oxide film.

[0010] Effects of the Invention

[0011] According to the present disclosure, in processing a substrate in which silicon layers and silicon germanium layers are alternately stacked, the processing steps can be appropriately shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is an explanatory diagram schematically showing conventional wafer processing.

[0013] Figure 2 It is a longitudinal sectional view showing an example of the structure of a plasma processing apparatus.

[0014] Figure 3 This is an explanatory diagram schematically showing an example of the state of wafer processing according to this embodiment.

[0015] Figure 4 This is a graph comparing the oxidation amounts of a silicon layer and a silicon germanium layer in the plasma treatment according to this embodiment.

[0016] Figure 5This is a graph showing an example of temporal changes in the amount of oxidation and etching of a silicon germanium layer in the plasma processing according to the present embodiment.

[0017] Figure 6 This is an image showing an example of the result of the plasma treatment according to this embodiment.

[0018] Figure 7 It is a longitudinal sectional view showing another example of the structure of the plasma processing apparatus.

[0019] Figure 8 This is an explanatory diagram showing how the oxide film is modified. DETAILED DESCRIPTION

[0020] In semiconductor devices, films containing silicon are widely used in various applications. For example, silicon germanium (SiGe) films and silicon (Si) films are used for gate electrodes and seed layers. In addition, in the past, the manufacturing process of so-called GAA (Gate All Around) transistors of nanosheets or nanowires, such as Figure 1 As shown, the following steps are performed in sequence: (a) lamination of a SiGe film and a Si film on a substrate (wafer W); (b) selective etching of the SiGe film; (c) embedding of an interlayer insulating film (IS); and (d) etching of the excess interlayer spacers. It should be noted that the embedded interlayer insulating film in (c) serves as an insulating film between the metal gate electrode and the channel to be embedded in a subsequent step.

[0021] The technique disclosed in Patent Document 1 is a method for performing selective etching of (b) SiGe films. This selective etching of SiGe films requires uniform control of the etching amount of each stacked SiGe film. Furthermore, the etching method disclosed in Patent Document 1 achieves uniform etching of the SiGe films by simultaneously supplying a fluorine-containing gas and a chlorine trifluoride gas.

[0022] However, in such conventional manufacturing processes, each of the steps (a) to (d) requires high-precision processing, resulting in reduced yield and huge costs, and there is room for improvement.

[0023] Therefore, the present inventors conducted intensive research and discovered that during the radical oxidation process on wafer W, etching and oxidation of the SiGe film proceed simultaneously. This led to the discovery of the possibility of omitting steps (a) to (d) in the conventional manufacturing process. Furthermore, this finding is not disclosed in Patent Document 1.

[0024] The technology disclosed herein is based on the above-mentioned findings and is designed to appropriately shorten the processing steps when processing a substrate having alternately stacked silicon (Si) layers and silicon germanium (SiGe) layers. Below, a plasma processing apparatus, which is a substrate processing apparatus according to this embodiment, and a plasma processing method using the plasma processing apparatus are described with reference to the accompanying drawings. It should be noted that in this specification and the accompanying drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and repeated descriptions are omitted.

[0025] Plasma processing equipment

[0026] Figure 2 This is a longitudinal sectional view schematically showing the outline of the configuration of the plasma processing apparatus 1. In the following description, the exposed end surfaces of the alternately arranged SiGe layers and Si layers are sometimes referred to as "exposed surfaces" of the SiGe layers and Si layers.

[0027] It should be noted that, in the plasma processing apparatus 1, the SiGe layer is selectively modified among the Si and SiGe layers stacked on the wafer W. Specifically, attachments on the exposed surface of the SiGe layer are selectively removed, and the SiGe layer is oxidized, thereby forming an oxide film (SiO2 film) on the surface of the exposed surface of the SiGe layer on the wafer W, that is, from the exposed surface toward the depth.

[0028] like Figure 2 As shown, plasma processing apparatus 1 includes a sealed processing container 10 for accommodating wafers W. Processing container 10 is formed, for example, of aluminum or an aluminum alloy, and has an open top. The top of processing container 10 is closed by a lid 10a, which serves as a top portion. A loading / unloading port (not shown) for wafers W is provided on the side of processing container 10. This loading / unloading port is connected to the exterior of plasma processing apparatus 1. The loading / unloading port is configured to be openable and closed by a gate valve (not shown).

[0029] The interior of the processing container 10 is partitioned by a partition 11 into an upper plasma generation space P and a lower processing space S. That is, the plasma processing apparatus 1 according to this embodiment is configured as a remote plasma processing apparatus in which the plasma generation space P and the processing space S are separated.

[0030] The partition 11 includes at least two plate-like members 12 and 13 arranged so as to overlap from the plasma generation space P toward the processing space S. A spacer 14 is disposed between the plate-like members 12 and 13 to adjust the distance between them. Furthermore, the plate-like members 12 and 13 each have slits 12a and 13a formed therethrough in the overlapping direction. The slits 12a and 13a are arranged so as not to overlap when viewed from above, thereby allowing the partition 11 to function as a so-called ion trap, which prevents ions from penetrating into the processing space S when plasma is generated in the plasma generation space P. More specifically, the slit arrangement structure, i.e., the labyrinth structure, in which the slits 12a and 13a are arranged so as not to overlap, prevents the movement of anisotropically migrating ions while allowing isotropically migrating radicals to pass through.

[0031] It should be noted that the structure of the separator 11 is not limited to the illustrated example, and any structure may be employed.

[0032] The plasma generating space P includes a gas supply unit 20 for supplying a processing gas into the processing container 10 and a plasma generating unit 30 for converting the processing gas supplied into the processing container 10 into plasma.

[0033] The gas supply unit 20 is connected to a plurality of gas supply sources (not shown), which supply a process gas including a fluorine-containing gas (e.g., NF3 gas), an oxygen-containing gas (e.g., O2 gas), and a diluent gas (e.g., Ar gas) into the processing container 10. It should be noted that the types of the fluorine-containing gas, the oxygen-containing gas, and the diluent gas are not limited thereto and may be arbitrarily selected.

[0034] The gas supply unit 20 is provided with a flow rate regulator (not shown) for regulating the supply rate of the processing gas to the plasma generation space P. The flow rate regulator includes, for example, an on-off valve and a mass flow controller.

[0035] The plasma generation unit 30 is configured as an inductively coupled device using an RF antenna. The lid 10a of the processing chamber 10 is formed, for example, from a quartz plate and serves as a dielectric window. An RF antenna 31 for generating inductively coupled plasma in the plasma generation space P of the processing chamber 10 is formed above the lid 10a. The RF antenna 31 is connected to a high-frequency power supply 33 via a matching unit 32.

[0036] The matching device 32 includes a variable reactance matching circuit (not shown) for matching the impedance on the high-frequency power source 33 side with the impedance on the load (RF antenna 31 , plasma) side.

[0037] The high-frequency power source 33 outputs high-frequency power of a constant frequency (usually 13.56 MHz or higher) suitable for generating plasma by high-frequency discharge through inductive coupling at an arbitrary output value.

[0038] The processing space S includes a mounting table 40 on which the wafer W is mounted in the processing container 10 , and an exhaust unit 50 for exhausting the processing gas in the processing container 10 .

[0039] The mounting table 40 includes an upper table 41 for mounting the wafer W and a lower table 42 fixed to the bottom surface of the processing chamber 10 and supporting the upper table 41. A temperature control mechanism 43 for adjusting the temperature of the wafer W is provided inside the upper table 41.

[0040] The exhaust unit 50 is connected to an exhaust mechanism (not shown), such as a vacuum pump, outside the mounting table 40 via an exhaust pipe installed at the bottom of the processing container 10. Furthermore, an automatic pressure control valve (APC) is installed on the exhaust pipe. The exhaust mechanism and the APC control valve control the pressure within the processing container 10.

[0041] The plasma processing apparatus 1 described above is provided with a control device 60 as a control unit. The control device 60 is, for example, a computer equipped with a CPU, a memory, etc., and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of wafers W in the plasma processing apparatus 1. In addition, the program storage unit also stores a program for controlling the operation of the drive system such as the various processing devices and the conveying device described above, and for implementing the wafer processing described later in the plasma processing apparatus 1. It should be noted that the above-mentioned program is recorded in a computer-readable storage medium H and can be installed from the storage medium H into the control device 60.

[0042] Plasma treatment

[0043] The plasma processing apparatus 1 according to this embodiment is configured as described above. Next, a description will be given of plasma processing performed by the plasma processing apparatus 1. It should be noted that the aforementioned Si layer and SiGe layer are previously alternately stacked on the wafer W loaded into the plasma processing apparatus 1.

[0044] First, as described above, a wafer W formed by alternately stacking Si layers and SiGe layers is carried in by a wafer transfer mechanism (not shown) provided outside the plasma processing apparatus 1 and mounted on the mounting table 40 .

[0045] In the wafer W that is carried in, the Si layer and the SiGe layer formed on the wafer W are selectively modified. Specifically, the processing gas (NF3 gas, O2 gas and Ar gas in this embodiment) is supplied from the gas supply unit 20 to the plasma generation space P, and high-frequency power is supplied to the RF antenna 31 to generate a plasma containing oxygen and fluorine as an inductively coupled plasma. In other words, the generated plasma contains fluorine radicals (F * ) and oxygen free radicals (O * ).

[0046] Here, the flow rate of the processing gas supplied to the plasma generation space P is preferably O2:NF3 = 100-2500 sccm:1-20 sccm, and more preferably the volume ratio of NF3 gas to O2 gas is 0.1% to 1.0% by volume. Furthermore, the power of the high-frequency power in the plasma generation space P is preferably 100 W to 1000 W, and the pressure (vacuum level) of the plasma generation space P is preferably 6.67 Pa to 266.6 Pa (50 mTorr to 2000 mTorr). Furthermore, the temperature of the plasma generation space P is preferably 0°C to 120°C, and more preferably 15°C to 100°C.

[0047] The plasma generated in the plasma generating space P is supplied to the processing space S via the partition 11. Here, as described above, a labyrinth structure is formed in the partition 11, so that only the radicals generated in the plasma generating space P penetrate into the processing space S. Figure 3 As shown in (a), by allowing the radicals supplied to the processing space S to act on the exposed surface of the SiGe layer, Figure 3 As shown in (b), the SiGe layer is modified, and an oxide film Ox is formed on the surface of the exposed surface of the SiGe layer.

[0048] Here, Figure 4 This is a graph comparing the oxidation amounts of the Si layer and the SiGe layer in the plasma treatment according to this embodiment. Figure 5 FIG is a diagram showing the time-dependent changes in the etching amount and oxidation amount of the SiGe layer in the plasma treatment according to this embodiment. Figure 5 As shown in FIG, the “etching amount” of the SiGe layer refers to the distance from the outer edge of the wafer W (Si layer) to the outer edge of the SiGe layer. Figure 5 As shown, the "oxidation amount" of the SiGe layer refers to the radial thickness of the oxide film Ox formed on the exposed surface of the SiGe layer.

[0049] like Figure 4As shown in FIG. 1 , it can be seen that, in the plasma treatment according to this embodiment, the oxidation amount (oxidation rate) of the SiGe layer is approximately six times that of the Si layer. In other words, the plasma treatment according to this embodiment can appropriately and selectively modify (oxidize) the SiGe layer.

[0050] And if Figure 5 As shown, by stacking Si and SiGe and performing plasma treatment, the etching amount of the SiGe layer, that is, the radial dimension of the SiGe layer remaining on the wafer W, can be linearly controlled with respect to the treatment time. On the other hand, it can be seen that by stacking Si and SiGe and performing plasma treatment, the oxidation amount of the SiGe layer, that is, the radial thickness of the oxide film (SiO2 film) formed on the exposed surface of the SiGe layer, is independent of the treatment time and reaches saturation at approximately 10 nm. In other words, according to the plasma treatment involved in this embodiment, the etching amount of the SiGe layer can be appropriately controlled while maintaining the oxidation amount of the SiGe layer at a desired value. Therefore, the line width of the SiGe layer, that is, the channel width formed in the subsequent process, can be controlled to an arbitrary size.

[0051] The modification of the SiGe layer will be described in detail. When the radicals pass through the processing space S, first, the deposits attached to the exposed surface of the SiGe layer (for example, deposited by reactive ion etching (RIE) as a pre-processing) are removed by F. * Then, O * The exposed surface of the SiGe layer is oxidized to form an oxide film Ox (SiO2 film). During the oxidation of the SiGe layer, O2 replaces Ge and bonds to Si, whereby Ge gasifies (e.g., Ge2F4, GeOF2) and scatters, for example, by F * 、Ar * The SiGe layer is transported to and recovered in the exhaust unit 50. In this embodiment, the above series of deposit removal and SiGe layer oxidation are collectively referred to as "modification."

[0052] Here, the inventors studied the oxide film (SiO2 film) formed as described above and found that the oxide film has a low leakage current, ensures good insulation, and has good CV and IV characteristics as an insulating film. In other words, it was found that it can be used as an insulating oxide film. Furthermore, it was found that the EOT (equivalent oxide thickness) is slightly reduced and heat resistance can be ensured. In other words, by using the oxide film formed as an inner spacer, Figure 1The manufacturing process of the conventional GAA transistor shown in FIG. can reduce the number of steps to about 1 / 3. Specifically, Figure 1 As shown, the SiGe layer is selectively oxidized by only allowing the plasma-generated processing gas to act on the SiGe layer without performing selective etching of the SiGe layer, embedding and etching of the inner spacer, and the formed oxide film can be used as the inner spacer, thereby significantly reducing the number of steps.

[0053] It should be noted that if the time for supplying free radicals to the processing space S during a single plasma treatment is prolonged, there is a concern that the effect of the free radicals on the Si layer may be increased. In order to suppress the above-mentioned effect on the Si layer, the average treatment time per group of plasma treatment is preferably 30 seconds to 180 seconds, for example.

[0054] Here, the etching amount of the SiGe layer during the plasma treatment, that is, the radial dimension of the SiGe layer is as follows: Figure 5 Therefore, in order to suppress the effect of radicals on the Si layer and form an oxide film at a desired depth, it is desirable to repeat the aforementioned plasma treatment (30 seconds to 180 seconds) for multiple groups.

[0055] Furthermore, when the power during plasma treatment is increased, there is still a concern that radicals may affect the Si layer. To suppress the above-mentioned effect on the Si layer, the power of the plasma treatment is preferably 100W to 1000W as mentioned above.

[0056] Furthermore, in this embodiment, so-called remote plasma generation is performed, in which plasma is generated in a plasma generation space P that is different from the processing space S where plasma processing is performed, and the plasma generated in the plasma generation space P is transported to the processing space S. Fluorine ion plasma is easily deactivated during the transport process, so by using remote plasma in this manner, a process based mainly on free radicals can be performed in the processing space S. Furthermore, by using free radicals in this manner, damage to the Si layer, the SiGe layer, and the wafer W can be reduced.

[0057] Then, the wafer W after the plasma processing in the plasma processing apparatus 1 is unloaded from the plasma processing apparatus 1 by a wafer transfer mechanism (not shown) provided outside the plasma processing apparatus 1 , and a series of plasma processing is completed.

[0058] As described above, according to this embodiment, when forming inner spacers on a SiGe layer, the SiGe layer can be modified simply by supplying a plasma-formed processing gas under desired conditions in the plasma processing apparatus 1. This reduces the number of plasma processing steps. Furthermore, by reducing the number of steps, the cost of the plasma processing can be reduced, and the processing accuracy required to form the inner spacers can be improved.

[0059] Figure 6 The SEM image shows the result of SiGe layer modification in the plasma treatment according to the present embodiment. Figure 6 As shown in (a), only the Si layer and the SiGe layer formed on the wafer W are modified appropriately, such as Figure 6 As shown in (b), an oxide film Ox can be formed.

[0060] In addition, according to this embodiment, since F is supplied to the processing space S, * Since the deposits are removed at the same time, there is no need to perform pre-treatment (such as removal of the natural oxide film by HF treatment) before the plasma treatment of the SiGe layer as in the prior art.

[0061] Furthermore, according to this embodiment, since remote plasma processing is performed in a plasma processing apparatus, the generated plasma is suppressed from reaching the Si layer, the SiGe layer, and the wafer W, thereby suppressing damage to these layers. Specifically, the generated fluorine and oxygen-containing radicals reach the exposed surface of the wafer W in an inactivated state, thereby appropriately modifying the SiGe layer and suppressing damage to the Si layer and the wafer W.

[0062] Furthermore, according to this embodiment, since the remote plasma processing is performed at a power of 100 W to 1000 W and the partition 11 of the processing container 10 has a maze structure, it is possible to appropriately suppress the generated ions from reaching the Si layer, the SiGe layer, and the wafer W. In other words, the effects on the Si layer and the wafer W can be further appropriately suppressed.

[0063] It should be noted that, in the plasma process according to this embodiment, O 2 , NF 3 , and Ar are supplied as process gases, but Ar gas may be additionally supplied as Add gas.

[0064] It should be noted that, according to this embodiment, NF3 is selected as the fluorine-containing gas included in the processing gas, but any fluorine-containing gas may be used as long as F3 can be appropriately generated during plasma generation. *For example, SF6 gas or F2 gas can be selected. In addition, the diluent gas is not limited to Ar gas, and any gas containing at least one of H2 gas and rare gas can be selected.

[0065] Furthermore, the plasma source in the plasma generation space P is not limited to the inductively coupled plasma of the present embodiment; for example, any configuration such as microwave plasma may be employed. However, the present inventors conducted the same experiment using a parallel plate plasma processing apparatus. As shown in the present embodiment, the selective modification of the SiGe layer was not adequate, and the Si layer was also modified. Therefore, in a plasma processing apparatus, it is preferable to generate plasma using remote plasma generation.

[0066] It should be noted that, after the oxide film is formed by plasma treatment in this embodiment, the oxide may be removed (BT treatment) in a BT treatment apparatus (not shown).

[0067] It should be noted that, as described above, the wafer W having the oxide film Ox formed thereon as the inner spacer is sometimes subsequently subjected to a wet etching process in, for example, an etching process apparatus (not shown) provided outside the plasma processing apparatus 1. Therefore, the plasma processing apparatus 1 according to this embodiment may further perform a plasma treatment for improving the wet etching resistance of the inner spacer (oxide film Ox) formed in the above embodiment.

[0068] Specifically, for example, by using a second processing gas containing a nitrogen-containing gas (such as N2 gas, NH3 gas or NF3 gas, etc.) and further performing plasma treatment on the wafer W formed with the oxide film Ox, the wet etching resistance of the inner spacer (oxide film Ox) can be improved.

[0069] When the second process gas is used to perform plasma processing on the wafer W, N * Acting on the oxide film Ox, the oxide film Ox is nitrided, such as Figure 8 As shown in (a), a nitride film Nt is formed as a protective film on the surface of the inner spacer. During the nitridation of the SiO2 film serving as the oxide film Ox, N is bonded to Si instead of O2, causing the O2 to gasify and disperse. Furthermore, by forming a nitride film Nt (e.g., a SiN film) having wet etching resistance on at least the surface of the inner spacer, the nitride film Nt protects the oxide film Ox from the etching solution during the wet etching process. That is, the oxide film Ox remaining on the inner side of the nitride film Nt maintains its properties as an inner spacer, and the nitride film Nt improves its wet etching resistance.

[0070] It should be noted that the present inventors have studied the nitride film Nt formed in this way and found that the nitride film Nt can also exhibit characteristics as at least an inner spacer. Figure 8 In the diagram of (a), at least the surface of the oxide film Ox is nitrided, and the oxide film Ox and the nitride film Nt are stacked to form the oxide film Ox. However, for example, Figure 8 As shown in (b), the oxide film Ox can be replaced entirely with a nitride film Nt, and the nitride film Nt can be used as an inner spacer. However, compared with the nitride film Nt, the oxide film Ox has better properties as an insulating film (CV, IV characteristics). Figure 8 As shown in (a), the nitride film Nt is more preferably used as a protective film for the oxide film Ox serving as an inner spacer.

[0071] It should be noted that the film formed by plasma treatment for improving wet etching resistance is not limited to the above-mentioned nitride film Nt. For example, the oxide film Ox is carbonized by using a second process gas containing a carbon-containing gas, such as Figure 8 As shown in (c), a wet-etching-resistant carbon film Cb (e.g., a SiC film) can be formed on at least the surface of the inner spacer. Carbon-containing gases such as CH4 gas, CHF3 gas, CH2F2 gas, CH3F gas, CF4 gas, C4F6 gas, C4F8 gas, CO gas, CO2 gas, and COS gas can be used. Furthermore, when the carbon film Cb is formed in this manner, similar to the nitride film Nt described above, its resistance to wet etching performed in subsequent processing steps can be improved.

[0072] It should be noted that the inventors have studied the carbonized film Cb formed in this way and found that the carbonized film Cb has better properties (CV and IV characteristics) as an insulating film than the oxide film Ox and can further reduce the dielectric constant of the inner spacer. Figure 8 In the diagram of (c), at least the surface layer of the oxide film Ox is carbonized, and the oxide film Ox and the carbide film Cb are stacked to form the oxide film Ox. However, for example Figure 8 As shown in (d), the entire oxide film Ox can be replaced with a carbon film Cb, and the carbon film Cb can be used as an inner spacer. In this case, the wet etching resistance can be improved compared to the case of using the oxide film Ox as the inner spacer, and the insulation property of the inner spacer can be further improved.

[0073] It should be noted that, in this embodiment, the plasma generating space P and the processing space S in the plasma processing apparatus 1 can be provided in the same chamber, that is, integrally provided on the upper portion of the processing container 10, but the configuration of the plasma processing apparatus 1 is not limited thereto. Figure 7 As shown, the plasma generating space P may also be provided outside the processing container 10 .

[0074] The embodiments disclosed herein are by way of example only and should not be construed as limiting. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope of the appended claims and the spirit thereof.

[0075] It should be noted that the following structures also fall within the protection scope of this disclosure.

[0076] (1) A substrate processing method, which is a method for processing a substrate on which silicon layers and silicon germanium layers are alternately stacked.

[0077] The substrate processing method uses a plasma-formed processing gas containing fluorine and oxygen to selectively modify the surface layer of the exposed surface of the silicon germanium layer to form an oxide film.

[0078] According to the above (1), in the plasma treatment of a substrate having alternately stacked silicon layers and silicon germanium layers, plasma is generated from a processing gas containing fluorine and oxygen, and the silicon germanium layer can be appropriately modified (removal of attachments and oxidation of the silicon germanium layer) only by supplying the above-mentioned plasma-formed processing gas.

[0079] (2) The substrate processing method according to (1) above, wherein the processing gas includes O2 gas and fluorine-containing gas, and the volume ratio of the fluorine-containing gas to the O2 gas is greater than or equal to 0.1 volume % and less than or equal to 1.0 volume %.

[0080] (3) The substrate processing method according to (2) above, wherein the fluorine-containing gas is NF3 gas, F2 gas or SF6 gas.

[0081] (4) The substrate processing method according to any one of (1) to (3) above, wherein the processing gas further contains at least one of H 2 gas and a rare gas.

[0082] (5) The substrate processing method according to any one of (1) to (4) above, wherein remote plasma is used to convert the processing gas into plasma.

[0083] According to the above (5), by making the process gas remotely plasma generated, damage to the Si layer, SiGe layer, and wafer W can be appropriately suppressed, and the SiGe layer can be appropriately modified.

[0084] (6) The substrate processing method according to any one of (1) to (5), wherein the etching amount of the silicon germanium layer from the exposed surface is proportional to the plasma processing time of the substrate.

[0085] (7) The substrate processing method according to any one of (1) to (6), wherein the thickness of the oxide film formed is saturated at a desired value regardless of the plasma processing time of the substrate.

[0086] (8) The substrate processing method according to (6) or (7), wherein the plasma treatment of the substrate is repeated, and the time for one set of plasma treatment is 30 seconds to 180 seconds.

[0087] According to the above (8), by controlling the plasma treatment time within the desired time, damage to the Si layer can be further appropriately suppressed. In addition, by repeating the plasma treatment, the surface layer of the exposed surface of the SiGe layer can be appropriately modified, that is, the exposed surface can be modified to a desired depth.

[0088] (9) A substrate processing method according to any one of (1) to (8), wherein at least a surface layer of the oxide film is modified to form a nitride film using a second processing gas containing a nitrogen-containing gas that has been converted into plasma.

[0089] (10) A substrate processing method according to any one of (1) to (8), wherein at least a surface layer of the oxide film is modified to form a carbonized film using a second processing gas containing a carbon-containing gas that has been converted into plasma.

[0090] According to the above (9) or (10), by further modifying at least the surface layer of the oxide film formed on the exposed surface to form a nitride film or a carbide film, it is possible to improve resistance to wet etching treatment performed in the processing step after the inner spacer is formed.

[0091] (11) A substrate processing apparatus for processing a substrate having silicon layers and silicon germanium layers alternately stacked, the substrate processing apparatus comprising:

[0092] a processing unit that selectively modifies the surface layer of the exposed surface of the silicon germanium layer using a plasma-formed processing gas containing fluorine and oxygen to form an oxide film; and

[0093] A control unit controls the plasma processing in the processing unit.

[0094] (12) The substrate processing apparatus according to (11), wherein:

[0095] The aforementioned processing gas includes O2 gas and fluorine-containing gas,

[0096] The control unit controls the supply amount of the processing gas in the processing unit so that the volume ratio of the fluorine-containing gas to the O 2 gas is greater than or equal to 0.1 volume % and less than or equal to 1.0 volume %.

[0097] (13) The substrate processing apparatus according to (12), wherein the fluorine-containing gas is NF3 gas, F2 gas or SF6 gas.

[0098] (14) A substrate processing apparatus according to any one of (11) to (13), wherein the control unit controls the supply of the processing gas in the processing unit by further supplying at least one of H2 gas and rare gas.

[0099] (15) The substrate processing apparatus according to any one of (11) to (14), wherein remote plasma is used to convert the processing gas in the processing section into plasma.

[0100] (16) The substrate processing apparatus according to any one of (11) to (15), wherein the etching amount of the silicon germanium layer from the exposed surface during the plasma processing is proportional to the plasma processing time.

[0101] (17) The substrate processing apparatus according to any one of (11) to (16), wherein the thickness of the oxide film formed during the plasma processing is saturated at a desired value independent of the plasma processing time.

[0102] (18) The substrate processing apparatus according to (16) or (17), wherein the control unit repeatedly performs plasma processing on the substrate, and controls a plasma processing time of one group to be within a range of 30 seconds to 180 seconds.

[0103] (19) A substrate processing device according to any one of (11) to (18), wherein the control unit performs control as follows: the plasma processing in the processing unit is controlled by using a second processing gas containing a nitrogen-containing gas that has been plasmatized to modify at least the surface layer of the oxide film to form a nitride film.

[0104] (20) A substrate processing device according to any one of (11) to (18), wherein the control unit performs control as follows: the plasma processing in the processing unit is controlled by using a second processing gas containing a carbon-containing gas that has been plasmatized to modify at least the surface layer of the oxide film to form a carbonized film.

[0105] (21) A method for manufacturing a nanowire or nanosheet transistor, the method comprising using a substrate on which silicon layers and silicon germanium layers are alternately stacked.

[0106] The manufacturing method uses a plasma-formed processing gas containing fluorine and oxygen to selectively modify the surface layer of the exposed surface of the silicon germanium layer to form an insulating oxide film.

[0107] (22) A method for manufacturing a nanowire or nanosheet transistor according to (21) above, wherein a second processing gas containing a nitrogen-containing gas that has been plasmatized is used to modify at least the surface layer of the insulating oxide film to form a nitride film.

[0108] (23) A method for manufacturing a nanowire or nanosheet transistor according to the aforementioned (21), wherein a second processing gas containing a carbon-containing gas that has been plasmatized is used to modify at least the surface layer of the aforementioned insulating oxide film to form a carbonized film.

[0109] Description of Reference Numerals

[0110] 1 Plasma treatment device

[0111] 60 control device

[0112] S processing space

[0113] W wafer

Claims

1. A substrate processing method, comprising: processing a substrate having silicon layers and silicon germanium layers alternately stacked; The substrate processing method uses a plasma-formed processing gas containing fluorine and oxygen to selectively modify the surface layer of the exposed surface of the silicon germanium layer to form an oxide film. in, Using a second process gas containing a nitrogen-containing gas in a plasma state, at least a surface layer of the oxide film is modified to form a nitride film.

2. The substrate processing method according to claim 1, wherein: The processing gas includes O 2 gas and fluorine-containing gas, and a volume ratio of the fluorine-containing gas to the O 2 gas is greater than or equal to 0.1 volume % and less than or equal to 1.0 volume %.

3. The substrate processing method according to claim 2, wherein: The fluorine-containing gas is NF3 gas, F2 gas or SF6 gas.

4. The substrate processing method according to any one of claims 1 to 3, wherein: The processing gas further includes at least one of H2 gas or a rare gas.

5. The substrate processing method according to any one of claims 1 to 3, wherein: Remote plasma is used to plasmatize the process gas.

6. The substrate processing method according to any one of claims 1 to 3, wherein: The etching amount of the silicon germanium layer from the exposed surface is proportional to the plasma processing time of the substrate.

7. The substrate processing method according to any one of claims 1 to 3, wherein: The thickness of the oxide film is saturated at a desired value regardless of the plasma treatment time of the substrate.

8. The substrate processing method according to claim 6, wherein: The plasma treatment of the substrate is repeated, and the time of one plasma treatment is 30 seconds to 180 seconds.

9. A method for processing a substrate having silicon layers and silicon germanium layers alternately stacked. The substrate processing method uses a plasma-formed processing gas containing fluorine and oxygen to selectively modify the surface layer of the exposed surface of the silicon germanium layer to form an oxide film. in, Using a second process gas containing a carbon-containing gas in a plasma state, at least a surface layer of the oxide film is modified to form a carbonized film.

10. A substrate processing apparatus for processing a substrate having silicon layers and silicon germanium layers alternately stacked thereon, the substrate processing apparatus comprising: a processing unit that selectively modifies the surface layer of the exposed surface of the silicon germanium layer using a plasma-formed processing gas containing fluorine and oxygen to form an oxide film; and a control unit that controls the plasma processing in the processing unit, in, The control unit controls the plasma processing in the processing unit so that at least a surface layer of the oxide film is modified to form a nitride film using a second processing gas including a nitrogen-containing gas converted into plasma.

11. The substrate processing apparatus according to claim 10, wherein: The processing gas includes O2 gas and fluorine-containing gas, The control unit controls the supply amount of the processing gas in the processing unit so that the volume ratio of the fluorine-containing gas to the O 2 gas is greater than or equal to 0.1 volume % and less than or equal to 1.0 volume %.

12. The substrate processing apparatus according to claim 11, wherein: The fluorine-containing gas is NF3 gas, F2 gas or SF6 gas.

13. The substrate processing apparatus according to any one of claims 10 to 12, wherein: The control unit controls the supply of the processing gas in the processing unit so as to further supply at least one of H 2 gas and rare gas.

14. The substrate processing apparatus according to any one of claims 10 to 12, wherein: Remote plasma is used to convert the process gas into plasma in the process unit.

15. The substrate processing apparatus according to any one of claims 10 to 12, wherein: The amount of etching of the silicon germanium layer from the exposed surface during the plasma treatment is proportional to the plasma treatment time.

16. The substrate processing apparatus according to any one of claims 10 to 12, wherein: The thickness of the oxide film formed during the plasma treatment is saturated at a desired value regardless of the plasma treatment time.

17. The substrate processing apparatus according to claim 15, wherein: The control unit repeatedly performs the plasma treatment on the substrate and controls a plasma treatment time of one set to be within a range of 30 seconds to 180 seconds.

18. A substrate processing apparatus for processing a substrate having silicon layers and silicon germanium layers alternately stacked thereon, the substrate processing apparatus comprising: a processing unit that selectively modifies the surface layer of the exposed surface of the silicon germanium layer using a plasma-formed processing gas containing fluorine and oxygen to form an oxide film; and a control unit that controls the plasma processing in the processing unit, in, The control unit controls the plasma processing in the processing unit so that at least a surface layer of the oxide film is modified to form a carbonized film using a second processing gas including a carbon-containing gas converted into plasma.

19. A method for manufacturing a nanowire or nanosheet transistor, the method comprising using a substrate on which silicon layers and silicon germanium layers are alternately stacked. The manufacturing method uses a plasma-formed processing gas containing fluorine and oxygen to selectively modify the surface layer of the exposed surface of the silicon germanium layer to form an insulating oxide film. in, Using a second process gas containing a nitrogen-containing gas in a plasma state, at least a surface layer of the insulating oxide film is modified to form a nitride film.

20. A method for manufacturing a nanowire or nanosheet transistor, the method comprising using a substrate on which silicon layers and silicon germanium layers are alternately stacked. The manufacturing method uses a plasma-formed processing gas containing fluorine and oxygen to selectively modify the surface layer of the exposed surface of the silicon germanium layer to form an insulating oxide film. in, Using a second process gas containing a carbon-containing gas in a plasma state, at least a surface layer of the insulating oxide film is modified to form a carbonized film.

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