Substrate processing method and substrate processing device
Through remote plasma processing and etching technology, the oxide film is formed and removed, which solves the problem of difficulty in removing the dielectric constant low-space film on the silicon germanium layer substrate in the prior art, and achieves accurate etching and uniform removal of the substrate.
Patent Information
- Application Number
- CN202110234823.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2020-03-10
- Filing Date
- 2021-03-03
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2041-03-03
AI Technical Summary
The prior art is difficult to properly remove spacer films with low dielectric constants, especially materials such as SiOC films, in alternately laminated silicon and silicon germanium layer substrates, resulting in insufficient etching and potential damage to the substrate.
The remote plasma treatment device uses oxygen-containing gas to form an oxide film, and the etching treatment device uses fluorine-containing gas and ammonia gas to selectively etch and remove the oxide film, ensuring that the removal process of the spacer film is carried out under low temperature and low pressure conditions, and repeated Plasma oxidation and etching are processed to achieve the desired etching amount.
The proper removal of the spacer film with a low dielectric constant is achieved, damage to the substrate is avoided, and uniformity and control of the etching process are ensured, and the spacer film can be uniformly removed in the plane and in the height direction of the wafer W. Achieving the desired etch thickness.
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Figure CN113380618B_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a substrate processing method and a substrate processing device. Background Art
[0002] Patent Document 1 discloses a method for manufacturing a semiconductor device that etches a SiN film formed on the surface of a substrate so as to cover a transistor using a gas containing a halogen element. According to the method described in Patent Document 1, in the initial stage of supplying the gas containing a halogen element, a gas containing an alkaline gas is mixed and supplied. As a result, the SiNO film formed so as to cover the surface of the SiN film is changed into a film of a reaction product, and the SiN film is etched by the gas containing a halogen element.
[0003] Prior art literature
[0004] Patent Literature
[0005] Patent Document 1: International Publication No. 2012 / 063901 Summary of the invention
[0006] Problem that the invention aims to solve
[0007] The technology according to the present disclosure appropriately removes a spacer film as an insulating film in processing a substrate in which a silicon layer and a silicon germanium layer are alternately stacked.
[0008] Solutions for solving problems
[0009] One embodiment of the present disclosure is a method for processing a substrate on which silicon films and silicon germanium films are alternately stacked, wherein a low dielectric constant spacer film is formed at least on the sides of the silicon film and the silicon germanium film, and the substrate processing method includes the following steps: forming an oxide film on the surface of the spacer film by using an oxygen-containing gas that has been plasmatized using remote plasma; and etching and removing the formed oxide film.
[0010] Effects of the Invention
[0011] According to the present disclosure, a spacer film as an insulating film is appropriately removed in processing a substrate in which silicon layers and silicon germanium layers are alternately stacked. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 It is an explanatory diagram schematically showing a conventional wafer processing situation.
[0013] Figure 2 It is a flowchart showing main steps of wafer processing according to the present embodiment.
[0014] Figure 3 It is an explanatory diagram schematically showing a state of wafer processing according to the present embodiment.
[0015] Figure 4 It is a longitudinal cross-sectional view showing an example of the structure of a plasma processing apparatus.
[0016] Figure 5 It is a graph showing the relationship between the time of plasma oxidation treatment and the oxidation amount.
[0017] Figure 6 It is a longitudinal cross-sectional view showing an example of the structure of an etching processing apparatus.
[0018] Figure 7 It is an explanatory diagram showing an example of the result of wafer processing according to the present embodiment.
[0019] Description of Reference Numerals
[0020] IS: spacer film; Ox: oxide film; Si: silicon; SiGe: silicon germanium; W: wafer. DETAILED DESCRIPTION
[0021] In semiconductor devices, films containing silicon are widely used for various purposes. For example, silicon germanium (SiGe) films and silicon (Si) films are used in gate electrodes and channel materials. In addition, in the manufacturing process of GAA (Gate allaround) transistors such as nanosheets or nanowires, Figure 1 As shown, (a) stacking a SiGe film and a Si film on a substrate (wafer W), (b) selectively etching the SiGe film, (c) embedding a spacer film IS (Inner Spacer) as an insulating film, and (d) etching the redundant spacer film IS are performed in sequence. In addition, the insulating film embedded in (c) is configured as an insulating film for reducing the parasitic capacitance between the embedded metal gate and the source / drain in the subsequent process. In addition, the spacer film IS in (d) is etched to expose at least the side of the stacked Si film. In the subsequent process, a crystalline silicon film is epitaxially grown on the side of the exposed Si film (hereinafter referred to as the "exposed side").
[0022] The technology disclosed in the above-mentioned patent document 1 is a method for performing the (d) etching of the redundant spacer film IS. Specifically, a silicon nitride (SiN) film (spacer film IS) formed in a manner covering the transistor is etched using a gas containing a halogen element, thereby forming the SiN film to a desired thickness.
[0023] In addition, in recent years, as material candidates for the spacer IS of the next-generation transistor with a nanosheet structure, materials with a lower dielectric constant than the conventional SiN film, such as carbon-containing silicon oxide film (SiOC film), silicon carbon nitride film (SiON film), carbon nitride silicon oxide film (SiOCN film), and silicon boron carbon nitride film (SiBCN film) have attracted attention. However, these SiOC films, SiON films, SiOCN films, and SiBCN films are chemically stable, and the desired etching amount cannot be obtained by the existing etching methods (such as wet etching and dry etching). That is, when these materials are used as the spacer IS, the etching of the spacer IS in the aforementioned (d) cannot be properly performed, and it is difficult to perform isotropic etching in the channel without damage.
[0024] The technology disclosed herein is completed in view of the above situation, and in the processing of a substrate having a silicon layer and a silicon germanium layer alternately stacked, a spacer film with a low dielectric constant such as a SiOC film is particularly appropriately removed. Hereinafter, wafer processing as a substrate processing method involved in this embodiment is described with reference to the accompanying drawings. In addition, in this specification and the accompanying drawings, the same reference numerals are given to elements having substantially the same functional structure, thereby omitting repeated descriptions.
[0025] Figure 2 1 is a flowchart showing the main steps related to the removal of the spacer film IS (for example, SiOC film in the following description) as a wafer processing method involved in this embodiment. Figure 3 It is an explanatory diagram showing the main steps related to the removal of the spacer film IS.
[0026] like Figure 2 and Figure 3 As shown, during the removal of the spacer film IS according to the present embodiment, the following steps are performed: an oxide film Ox is formed on the surface of the spacer film IS formed so as to cover at least the side surfaces of the Si layer and the SiGe layer stacked on the wafer W. Figure 2 Step T1); and etching and removing the formed oxide film Ox ( Figure 2 Step T2). Repeat these steps T1 and T2 until Figure 3 As shown in (e) of FIG. 1 , the spacer film IS is etched away to expose at least the side surface of the Si film and form an exposed side surface ( Figure 2 Branch C1).
[0027] Next, Figure 2 and Figure 3 The detailed method of each step shown is described below.
[0028] <Step T1: Forming an oxide film on the spacer film>
[0029] exist Figure 2 In step T1 , the spacer film IS is oxidized using the plasma processing apparatus 1 as a plasma processing unit, and an oxide film Ox is formed in a depth direction from the surface layer, ie, the surface of the spacer film IS. Figure 4 1 is a longitudinal cross-sectional view schematically showing the structure of a plasma processing apparatus 1 for performing the plasma oxidation process.
[0030] like Figure 4 As shown, the plasma processing apparatus 1 includes a processing container 10 of a sealed structure for accommodating wafers W. The processing container 10 is formed of, for example, aluminum or an aluminum alloy, and the upper end of the processing container 10 is open and is closed by a cover 10a as a top. A loading and unloading port (not shown) for the wafers W is provided on the side of the processing container 10, and the plasma processing apparatus 1 is connected to the outside through the loading and unloading port. The loading and unloading port is configured to be freely opened and closed by a gate valve (not shown).
[0031] The interior of the processing container 10 is partitioned into an upper plasma generation space P and a lower processing space S by a partition plate 11. That is, the plasma processing apparatus 1 according to the present embodiment is configured as a remote plasma processing apparatus in which the plasma generation space P and the processing space S are separated.
[0032] The partition plate 11 has at least two plate-like members 12 and 13 which are arranged in an overlapping manner with a gap therebetween from the plasma generation space P toward the processing space S side. The plate-like members 12 and 13 respectively have slits 12a and 13a which are formed in a manner of penetrating the plate-like members 12 and 13 in the overlapping direction. Moreover, the slits 12a and 13a are arranged so as not to overlap when viewed from above, so that the partition plate 11 functions as a so-called ion trap for suppressing ions in the plasma from passing through the partition plate 11 and reaching the processing space S when plasma is generated in the plasma generation space P. More specifically, by arranging the labyrinth structure in which the slits 12a and 13a do not overlap, the movement of ions moving anisotropically is prevented, while the free radicals moving isotropically are allowed to pass through.
[0033] 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.
[0034] The gas supply unit 20 is connected to a plurality of gas supply sources (not shown), and the plurality of gas supply sources respectively supply oxygen-containing gases (e.g., O 2In addition, the types of oxygen-containing gas and dilution gas supplied to the gas supply unit 20 are not limited as long as the oxide film Ox can be formed on the surface layer of the spacer film IS.
[0035] The gas supply unit 20 is provided with a flow rate regulator (not shown) for regulating the amount of the processing gas supplied to the plasma generation space P. The flow rate regulator includes, for example, an on-off valve and a mass flow controller.
[0036] The plasma generating unit 30 is configured as an inductive coupling type device using an RF antenna. The cover 10a of the processing container 10 is formed of, for example, a quartz plate and is configured as a dielectric window. An RF antenna 31 for generating inductively coupled plasma in the plasma generating space P of the processing container 10 is formed above the cover 10a. The RF antenna 31 is connected to a high frequency power supply 33 via a matching device 32, the matching device 32 having a matching circuit for matching the impedance of the power supply side and the load side, and the high frequency power supply 33 outputs a high frequency power of a fixed frequency (usually 13.56 MHz or more) suitable for generating plasma at an arbitrary output value.
[0037] 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 a processing gas in the processing container 10 .
[0038] The mounting table 40 includes an upper table 41 on which the wafer W is mounted and a lower table 42 fixed to the bottom surface of the processing container 10 and supporting the upper table 41. A temperature adjustment mechanism 43 for adjusting the temperature of the wafer W is provided inside the upper table 41.
[0039] The exhaust unit 50 is connected to an exhaust mechanism (not shown) such as a vacuum pump via an exhaust pipe provided at the bottom of the processing container 10. In addition, an automatic pressure control valve (APC) is provided on the exhaust pipe. The pressure in the processing container 10 is controlled by the exhaust mechanism and the automatic pressure control valve.
[0040] 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 having 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 the wafer W performed in the plasma processing apparatus 1. In addition, the program storage unit also stores a program for controlling the operation of the drive system of the various processing devices, the conveying device, etc. described above to realize the wafer processing described later performed in the plasma processing apparatus 1. In addition, the above-mentioned program may be recorded in a computer-readable storage medium H and installed in the control device 60 from the storage medium H.
[0041] The plasma processing apparatus 1 according to the present embodiment is configured as described above. Next, a plasma oxidation process (formation of an oxide film Ox) performed using the plasma processing apparatus 1 is described. In addition, the aforementioned Si layer and SiGe layer are formed in advance in an alternating manner on the wafer W loaded into the plasma processing apparatus 1, and a spacer film IS is formed on at least the side surfaces of the Si layer and the SiGe layer.
[0042] First, if Figure 3 As shown in (a), a wafer W having a Si layer, a SiGe layer, and a spacer film IS formed thereon is placed on a mounting table 40. The spacer film IS formed on the side surfaces of the Si layer and the SiGe layer is oxidized, thereby Figure 3 As shown in FIG. 2 (b), an oxide film Ox is formed on the surface layer of the spacer film IS of the wafer W carried into the plasma processing apparatus 1 .
[0043] Specifically, after the wafer W is placed on the mounting table 40, an oxygen-containing gas (O) is supplied from the gas supply unit 20 to the plasma generation space P. 2 Gas (argon gas) and dilution gas (Ar gas) are mixed, and high frequency power is supplied to RF antenna 31 to generate plasma containing oxygen as inductively coupled plasma. In other words, the generated plasma contains oxygen radicals (O*). At this time, the pressure in the processing space S is controlled to be, for example, about 50mTorr to 1000mTorr, and the temperature of the wafer W on the mounting table 40 is controlled to be, for example, about 60°C to 150°C. In addition, the O supplied to the processing space S is controlled to be about 100°C to about 200°C. 2 The flow rates of the N2O2 gas and the Ar gas are controlled to be, for example, approximately 100 sccm to 1500 sccm and 10 sccm to 500 sccm, respectively.
[0044] The plasma generated in the plasma generation space P is supplied to the processing space S via the partition plate 11. Here, as described above, the partition plate 11 is formed with a labyrinth structure, so that only the radicals generated in the plasma generation space P pass through the partition plate 11 and reach the processing space S. Then, the radicals supplied to the processing space S act on the surface of the spacer film IS to oxidize the surface, thereby forming an oxide film Ox on the surface layer of the spacer film IS. More specifically, for example, in the case where the spacer film IS is formed of a SiOC film, the SiOC film is modified by the action of oxygen radicals (bonded with O to replace C), thereby forming SiO as the oxide film Ox. 2 membrane.
[0045] In addition, in the plasma oxidation process, as described above, only radicals that move isotropically penetrate into the processing space S, so that the oxide film Ox is isotropically formed. More specifically, the oxide film Ox is uniformly formed in the surface of the wafer W and uniformly in the height direction of the stacked Si film and SiGe film.
[0046] Here, the plasma oxidation process involved in this embodiment is a process in which the oxidation amount of the spacer film IS, that is, the thickness of the formed oxide film Ox is saturated during the plasma oxidation process. Figure 5 The thickness of the oxide film Ox formed by one plasma oxidation treatment is 2 nm or less (eg, about 1 nm to 1.5 nm).
[0047] <Step T2: Etching and Removal of Oxide Film Ox>
[0048] After the oxide film Ox is formed on the surface layer of the spacer film IS, the oxide film Ox formed in step T1 is then removed by etching using the etching apparatus 101 as an etching processing unit. Figure 6 1 is a longitudinal cross-sectional view schematically showing the structure of an etching processing apparatus 101 for performing the etching removal processing.
[0049] like Figure 6 As shown, the etching processing apparatus 101 is provided with a closed processing container 110 for accommodating a wafer W, and a processing space S is formed inside the processing container 110. A loading and unloading port (not shown) for the wafer W is provided on the side of the processing container 110, and the etching processing apparatus 101 is connected to the outside through the loading and unloading port. The loading and unloading port is configured to be opened and closed freely by a gate valve (not shown). In addition, the etching processing apparatus 101 is provided with a loading table 120 for placing the wafer W in the processing container 110, a supply unit 130 for supplying etching gas into the processing space S, and an exhaust unit 140 for exhausting the etching gas in the processing container 110.
[0050] The mounting table 120 is substantially circular in plan view and is fixed to the bottom of the processing container 110. A temperature adjustment mechanism 121 is provided inside the mounting table 120 for adjusting the temperature of the mounting table 120 and the wafer W held thereon.
[0051] The supply unit 130 includes a shower head 132 and a plurality of gas supply sources 131, and the plurality of gas supply sources 131 supply fluorine-containing gas (such as HF gas), ammonia (NH 2 O) and fluorine-containing gas (such as HF gas) as etching gas into the processing container 110. 3 ) gas, diluent gas (such as Ar gas) and inert gas (such as N 2The shower head 132 is disposed on the top of the processing container 110 and has a plurality of nozzles for spraying the processing gas into the processing space S. The gas supply source 131 is connected to the inside of the processing container 110 via a supply pipe connected to the shower head 132.
[0052] In addition, the supply unit 130 is provided with a flow rate regulator 133 for regulating the supply amount of the etching gas supplied into the processing container 110. The flow rate regulator 133 includes, for example, an on-off valve and a mass flow controller.
[0053] The exhaust unit 140 is connected to an exhaust mechanism (not shown) such as a vacuum pump via an exhaust pipe provided at the bottom of the processing container 110. In addition, an automatic pressure control valve (APC) is provided on the exhaust pipe. The pressure in the processing container 110 is controlled by the exhaust mechanism and the automatic pressure control valve.
[0054] The above etching processing apparatus 101 is provided with a control device 150 as a control unit. The control device 150 is, for example, a computer having 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 the wafer W performed in the etching processing apparatus 101. In addition, the program storage unit also stores a program for controlling the operation of the drive system of the various processing devices, the conveying device, etc. mentioned above to realize the wafer processing described later performed in the etching processing apparatus 101. In addition, the above program may be recorded in a computer-readable storage medium H and installed in the control device 150 from the storage medium H.
[0055] Furthermore, the control device 150 provided in the etching processing apparatus 101 may be a common control device with the control device 60 provided in the plasma processing apparatus 1 . That is, the etching processing apparatus 101 may be connected to the control device 60 provided in the plasma processing apparatus 1 instead of being connected to the control device 150 .
[0056] The etching apparatus 101 according to the present embodiment is configured as described above. Next, the etching removal process (removal of the oxide film Ox) performed by the etching apparatus 101 is described. In addition, the oxide film Ox is formed on the surface layer of the spacer film IS of the wafer W loaded into the etching apparatus 101 in the aforementioned step T1.
[0057] First, Figure 3 As shown in (b) of FIG. 1 , a wafer W having an oxide film Ox formed on the surface of the spacer film IS is placed on the placement table 120. The etching gas acts on the oxide film Ox formed on the wafer W carried into the etching processing apparatus 101, thereby Figure 3 The oxide film Ox is gas etched as shown in (c).
[0058] Specifically, after the wafer W is placed on the mounting table 120, a dilution gas (Ar gas) and an inert gas (N gas) are supplied into the sealed processing container 110. 2 At this time, the pressure in the processing container 110 is controlled to be lower than the atmospheric pressure (e.g., about 10 mTorr to 3000 mTorr), and the wafer W on the mounting table 120 is controlled to a desired temperature (e.g., 0°C to 120°C, preferably 0°C to 60°C).
[0059] When the pressure in the processing container 110 and the temperature of the wafer W reach the desired low pressure and low temperature state, fluorine-containing gas (HF gas) and NH 2 O are further supplied into the processing container 110. 3 At this time, for example, HF gas, NH 3 The flow rates of the HF gas and the Ar gas are controlled to be approximately 10 sccm to 500 sccm, 10 sccm to 500 sccm, and 10 sccm to 500 sccm, respectively. 3 Gas is used to start gas etching of the oxide film Ox formed on the surface layer of the spacer film IS.
[0060] Here, in this embodiment, as described above, the SiOC film used as the material of the spacer film IS is a chemically stable material and is different from the oxide film Ox (SiO 2 The etching rate (ER) of the spacer film is very small compared to the etching rate of the spacer film. That is, in the etching removal process involved in the present embodiment, the inside of the spacer film IS where the oxide film Ox is not formed in step T1 is hardly etched away, and only the oxide film Ox formed on the surface of the spacer film IS is selectively etched away. In other words, only the oxide film Ox can be selectively etched away while leaving the spacer film IS, so it is easy to control the etching of the spacer film IS.
[0061] In addition, if Figure 5 As shown in FIG. 1 , the thickness of the oxide film Ox formed by one plasma oxidation process is saturated at about 1 nm to 1.5 nm, for example. In addition, as described above, in the plasma oxidation process using oxygen radicals according to the present embodiment, the oxide film Ox is isotropically formed. Furthermore, in the etching removal process in step T2, the spacer film IS is etched by removing the oxide film Ox isotropically formed to a thickness of about 1 nm to 1.5 nm, so that the spacer film IS can be etched and removed isotropically.
[0062] In addition, in the present embodiment, the etching removal process of step T2 is also performed under low pressure and low temperature conditions. Here, when the etching removal process is performed under high temperature and high pressure conditions, the EA of the spacer film IS rises, and the oxide film Ox cannot be properly selectively etched and removed, and the spacer film IS may not be formed into a desired shape. In this regard, the etching removal process in the present embodiment is performed under low pressure and low temperature conditions, for example, under conditions where the temperature of the wafer W is 0°C to 120°C, preferably 0°C to 60°C, so that the oxide film Ox can be properly selectively etched and removed.
[0063] <Branch C1: Repetition of Plasma Oxidation Process and Etching Removal Process>
[0064] The plasma oxidation process (step T1) and etching removal process (step T2) of this embodiment are performed as described above. Here, as described above, in a series of wafer processes (plasma oxidation process and etching removal process) of this embodiment, only the oxide film Ox (spacer film IS) with a thickness of about 1nm to 1.5nm is removed, that is, the side surface of the Si layer cannot be exposed by only one wafer process. Therefore, in this embodiment, by repeating the cycle of this series of wafer processes (steps T1 and T2), Figure 5 As shown, the total etching amount (oxidation amount) is increased. In addition, the spacer film IS can be etched away to a desired thickness, specifically, a thickness that exposes at least the side surface of the Si layer and forms the exposed side surface.
[0065] In other words, the number of cycles of wafer processing repeated in the present embodiment is determined by the thickness of the spacer film IS formed so as to cover the Si layer and the SiGe layer.
[0066] Even when the wafer processing cycle is repeated as described above, the oxide film Ox having a thickness of 2 nm or less is isotropically formed in one plasma oxidation process, and the oxide film Ox formed in this way is selectively removed in one etching removal process. That is, the thickness of the spacer film IS removed by one etching can be controlled to a constant thickness, and the in-plane uniformity of the etching amount of the spacer film IS can be easily controlled.
[0067] Then, when a desired etching amount is obtained by repeating the wafer processing cycle in this manner, that is, when an exposed side surface is formed on the Si layer, the wafer processing according to the present embodiment is completed.
[0068] In addition, the wafer W with the exposed side surface formed with the Si layer is transferred to the next step, for example, a crystalline silicon thin film is epitaxially grown on the exposed side surface. Figure 3As shown in (e), the spacer film IS remains on the side surface of the SiGe film, so that the epitaxial growth of the crystalline silicon thin film on the side surface of the SiGe film can be suppressed.
[0069] <Effects of Wafer Processing According to the Embodiment>
[0070] According to the present embodiment, the surface layer of the spacer film IS (for example, SiOC film, SiON film or SiOCN film) formed of a material having a lower dielectric constant than that of a conventional SiN film and being chemically stable is oxidized by using an oxygen-containing gas plasmaized by remote plasma, thereby appropriately forming an oxide film Ox (SiO 2 membrane). In addition, by using a fluorine-containing gas (such as HF gas) and ammonia (NH 3 ) gas, the formed oxide film Ox can be properly etched and removed. That is, according to this embodiment, the spacer film IS as an insulating film can be properly removed.
[0071] In addition, according to the wafer processing involved in this embodiment, the chemically stable spacer film IS itself is not etched away as described above, and only the oxide film Ox formed as described above can be selectively etched away. That is, the etching of the spacer film IS can be properly controlled, and damage to the portion other than the oxide film Ox to be etched can be properly suppressed. In addition, at this time, the oxide film Ox is isotropically formed on the surface layer of the spacer film IS, so the spacer film IS can be etched away isotropically.
[0072] Furthermore, according to the present embodiment, only the spacer film IS with a thickness of less than 2 nm (for example, about 1 nm to 1.5 nm) is etched and removed by one cycle of wafer processing, and the desired etching amount is obtained by repeating the wafer processing. Figure 5 As shown in FIG. 1 , during the plasma oxidation process, the thickness of the spacer film IS to be etched away, that is, the thickness of the oxide film Ox to be formed is saturated. That is, the thickness of the spacer film IS to be removed at one time can be easily controlled, so the total etching amount of the spacer film IS in the wafer process can be appropriately controlled. That is, the total etching amount exceeding the desired amount can be appropriately suppressed.
[0073] Here, in Figure 7 2 shows an example of a processing result when a cycle of wafer processing according to the present embodiment is repeatedly performed. Figure 7 (a) shows the state of the spacer film IS before wafer processing. Figure 7 (b) shows the state of the spacer film IS after 10 cycles of wafer processing. Figure 7(c) shows the state of the spacer film IS after 10 cycles of wafer processing. Figure 7 The lower figure is an enlarged view of the main part in which the main part (Si layer, SiGe layer and spacer film IS) of the upper figure is enlarged and shown.
[0074] For example Figure 7 The spacer IS formed on the side of the Si layer and the SiGe layer as shown in (a) is subjected to 7 cycles of wafer processing, thereby Figure 7 As shown in (b), the thickness of the spacer film IS is reduced, that is, it is etched away. Furthermore, the processing cycle is further repeated to implement 10 cycles of wafer processing, thereby Figure 7 As shown in (c), an exposed side surface is formed on the Si layer. At this time, the spacer film IS remains on the side surface of the SiGe layer.
[0075] In addition, if Figure 7 (b) Figure 7 As shown in (c), it can be seen that the thickness of the spacer film IS remaining on the side of the Si layer and the SiGe layer is uniform in the surface of the wafer W, and is also uniform in the height direction of the stacked Si layer and SiGe layer. In other words, it can be seen that in the wafer processing involved in this embodiment, the spacer film IS is etched and removed uniformly in the surface direction and the height direction of the wafer W.
[0076] As described above, according to the plasma oxidation process and the etching removal process involved in this embodiment, the spacer film IS as the insulating film can be isotropically etched and removed. Figure 7 (b) Figure 7 As shown in (c), by controlling the number of repeated cycles of wafer processing, the total etching amount of the spacer film IS can be easily controlled, and etching removal can be performed while suppressing an etching amount exceeding a desired amount.
[0077] In addition, the plasma oxidation process and the etching removal process according to this embodiment may be performed in different chambers or in the same chamber.
[0078] In the above embodiment, the oxide film Ox is selectively removed by utilizing the etching rate difference between the oxide film Ox and the spacer film IS, thereby etching and removing the spacer film IS. However, the etching method of the spacer film IS is not limited thereto.
[0079] Specifically, for example, the oxide film Ox may be selectively removed by utilizing the difference in incubation time (time until etching removal starts) between the oxide film Ox and the spacer film IS, thereby performing etching removal processing on the spacer film IS. In this case, in the etching removal processing, the oxide film Ox is removed in the etching processing apparatus 101, and the etching gas is exhausted from the inside of the processing container 110 before the removal of the spacer film IS starts. Thus, the oxide film Ox can be selectively removed.
[0080] In addition, when the etching rate difference between the oxide film Ox and the spacer film IS is used as described above, the etching removal process is performed using an etching removal device under low pressure and low temperature conditions. This is because, under low temperature and low pressure conditions, the etching rate of the spacer film IS decreases, and the oxide film Ox can be selectively removed more appropriately. On the other hand, when the incubation time difference is used as described above, the etching removal process can be performed under high temperature and high pressure conditions (for example, a temperature condition of 80°C to 130°C). That is, under high temperature and high pressure conditions, the incubation time difference between the oxide film Ox and the spacer film IS becomes more obvious.
[0081] Here, when the etching removal process is performed by utilizing the etching rate difference under the conditions of low pressure and low temperature, as described above, the plasma oxidation process is performed by utilizing the plasma processing device 1 at a high temperature higher than the temperature condition of the etching removal process, for example, 60°C to 150°C. That is, when switching from the plasma oxidation process to the etching removal process, the wafer W needs to be cooled. On the other hand, when the etching removal process is performed by utilizing the incubation time difference under the conditions of high temperature and high pressure, the temperature condition of the etching removal process is substantially the same as the temperature condition of the plasma oxidation process. That is, when switching from the plasma oxidation process to the etching removal process, there is no need to control the temperature of the wafer W, so a series of wafer processes can be efficiently performed.
[0082] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the appended claims and the gist thereof.
[0083] In addition, the following structures also belong to the technical scope of the present disclosure.
[0084] (1) A substrate processing method is a method for processing a substrate on which silicon films and silicon germanium films are alternately stacked, wherein a low dielectric constant spacer film is formed at least on the sides of the silicon film and the silicon germanium film, and the substrate processing method includes the following steps: forming an oxide film on the surface of the spacer film by using an oxygen-containing gas that has been radicalized using remote plasma; and etching and removing the formed oxide film.
[0085] According to (1), an oxide film is formed on the surface of the low dielectric constant spacer film using a plasma-generated oxygen-containing gas, and the formed oxide film is etched and removed, thereby removing the spacer film. The low dielectric constant spacer film has chemical stability and is difficult to etch and remove using the existing etching method. However, by using the plasma-generated oxygen-containing gas in this way, the oxide film can be properly formed, thereby properly removing the spacer film formed as an oxide film.
[0086] Furthermore, the spacer film is oxidized by the plasma-generated oxygen-containing gas isotropically in the surface direction and the height direction of the substrate. That is, the spacer film can be etched away isotropically in the surface direction and the height direction of the wafer W.
[0087] (2) According to the substrate processing method described in (1), the spacer film is formed of any one of SiOC, SiON, SiOCN and SiBCN.
[0088] (3) According to the substrate processing method described in (1) or (2), the thickness of the formed oxide film is 2 nm or less from the surface of the spacer film.
[0089] (4) According to the substrate processing method described in any one of (1) to (3), the thickness of the oxide film to be formed is controlled by the processing time of the step of forming the oxide film.
[0090] (5) A substrate processing method according to any one of (1) to (4), using a gas containing at least HF gas and NH 3 The oxide film is etched and removed by etching with a processing gas.
[0091] (6) According to the substrate processing method described in (5), the step of etching and removing the oxide film is carried out under low temperature and low pressure conditions, and the temperature conditions for the etching and removal are 0°C to 120°C, preferably 0°C to 60°C.
[0092] (7) According to the substrate processing method described in any one of (1) to (6), a cycle including a step of forming the oxide film and a step of etching and removing the oxide film is repeated, thereby removing the spacer film and exposing at least the side surface of the silicon film.
[0093] According to (7), by repeatedly removing the spacer film, the desired etching amount can be properly obtained. In particular, as described in (3), the oxidation amount of the spacer film in one wafer processing (the etching amount of the spacer film) is saturated below 2nm, so the total etching amount of the spacer film can be easily controlled. In addition, since the oxidation amount (etching amount) of the spacer film is reduced to below 2nm in this way, the total etching amount of the spacer film can be more easily controlled.
[0094] (8) A substrate processing device processes a substrate on which silicon films and silicon germanium films are alternately stacked, wherein a low dielectric constant spacer film is formed at least on the sides of the silicon film and the silicon germanium film, and the substrate processing device comprises: a plasma processing unit, which uses an oxygen-containing gas that has been radicalized using a remote plasma to oxidize the surface of the spacer film to form an oxide film; an etching processing unit, which etches and removes the formed oxide film; and a control unit, which controls the operation of the plasma processing unit and the etching processing unit.
[0095] (9) According to the substrate processing apparatus described in (8), the spacer film is formed of any one of SiOC, SiON, SiOCN and SiBCN.
[0096] (10) According to the substrate processing apparatus described in (8) or (9), the control unit controls the operation of the plasma processing unit so that the thickness of the oxide film is formed to be less than 2 nm from the surface of the spacer film.
[0097] (11) In the substrate processing apparatus described in any one of (8) to (10), the control unit controls the thickness of the oxide film to be formed by a processing time of the plasma processing unit.
[0098] (12) According to any one of (8) to (11), the control unit controls the operation of the etching unit to utilize at least HF gas and NH 3 The oxide film is etched and removed by etching using the process gas of the gas.
[0099] (13) According to the substrate processing device described in (12), the control unit controls the operation of the etching processing unit to perform etching removal of the oxide film under low temperature and low pressure conditions, and the temperature conditions for the etching removal are 0°C to 120°C, preferably 0°C to 60°C.
[0100] (14) According to the substrate processing device described in any one of (8) to (13), the control unit controls the operation of the plasma processing unit and the etching processing unit to remove the spacer film by repeating the following cycle to expose at least the side of the silicon film, wherein the cycle includes the formation of the oxide film in the plasma processing unit and the removal of the oxide film in the etching processing unit.
Claims
1. A substrate processing method, which is a substrate processing method having silicon films and silicon germanium films alternately stacked, wherein a low dielectric constant spacer film is formed at least on the side surfaces of the silicon film and the silicon germanium film, and the substrate processing method comprises the following steps: forming an oxide film on the surface layer of the spacer film by using an oxygen-containing gas radicalized by remote plasma, wherein the oxide film is isotropically formed using only oxygen radicals that move isotropically; and The formed oxide film is removed by etching, wherein a cycle including a step of forming the oxide film and a step of etching and removing the oxide film is repeated, thereby removing the spacer film and exposing at least the side surface of the silicon film; The step of forming the oxide film is a process in which the oxidation amount of the spacer film, that is, the thickness of the formed oxide film, is saturated during the plasma oxidation process, and the thickness of the oxide film formed by the single step of forming the oxide film is 2 nm or less from the surface of the spacer film. The step of forming the oxide film is performed under a temperature condition higher than a temperature when the step of etching and removing the oxide film is performed.
2. The substrate processing method according to claim 1, characterized in that: The spacer film is formed of any one of SiOC, SiON, SiOCN and SiBCN.
3. The substrate processing method according to claim 1 or 2, characterized in that: The thickness of the oxide film to be formed is controlled by the processing time of the step of forming the oxide film.
4. The substrate processing method according to claim 1 or 2, characterized in that: The step of removing the oxide film by etching is performed by etching using a processing gas containing at least HF gas and NH 3 gas.
5. The substrate processing method according to claim 4, characterized in that: The step of etching and removing the oxide film is performed under low temperature and low pressure conditions. The temperature condition for performing the etching removal is 0°C to 120°C.
6. A substrate processing apparatus for processing a substrate on which a silicon film and a silicon germanium film are alternately stacked, wherein a low dielectric constant spacer film is formed at least on the side surfaces of the silicon film and the silicon germanium film, The substrate processing device comprises: a plasma processing unit for forming an oxide film on the surface of the spacer film using an oxygen-containing gas radicalized by remote plasma; an etching processing unit that removes the formed oxide film by etching; and A control unit controls the operations of the plasma processing unit and the etching processing unit to perform each step of the substrate processing method according to any one of claims 1 to 5.