Silicon nitride chemical vapor deposition using remote plasma

Abstract

Disclosed examples relate to low damage deposition of silicon nitride films using chemical vapor deposition (CVD). One example presents a method (300) for forming a silicon nitride film on a substrate in a processing chamber by chemical vapor deposition. The method includes introducing (302) a nitrogen-containing precursor into a remote plasma formed in a remote plasma chamber of the processing tool. The method further includes forming (308) a free radical nitrogen species in the remote plasma. The method further includes flowing (312) an oxygen-free silicon-containing precursor into the processing chamber of the processing tool. The method further includes introducing (316) a free radical nitrogen species from the remote plasma chamber into the processing chamber while flowing the oxygen-free silicon-containing precursor. The method further includes reacting the oxygen-free silicon-containing precursor with a radical nitrogen species to form a silicon nitride film on the substrate.

Description

Background Art

[0001] Semiconductor manufacturing processes can involve many steps such as material deposition, patterning, and removal to form integrated circuits on a substrate. For example, silicon nitride can be deposited and patterned to form many different structures in an integrated circuit. Atomic layer deposition (ALD) can be used to form highly conformal silicon nitride films. ALD forms a film in the form of one or more individual film layers by sequentially adsorbing precursors onto a substrate and then reacting the adsorbed precursors to form a film layer. Summary of the Invention

[0002] This Summary of the Invention is provided to introduce a selection of concepts in a simplified form that will be further described in the Detailed Description below. This Summary of the Invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Additionally, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0003] The disclosed examples relate to low-damage chemical vapor deposition (CVD) of silicon nitride films using remote plasmas. One example presents a method of forming a silicon nitride film on a substrate in a processing chamber by chemical vapor deposition. The method includes: introducing a nitrogen-containing precursor into a remote plasma formed in a remote plasma chamber of a processing tool. The method further includes: forming radical nitrogen species in the remote plasma. The method further includes: flowing an oxygen-free silicon-containing precursor into the processing chamber of the processing tool. The method further includes: introducing the radical nitrogen species from the remote plasma chamber into the processing chamber while flowing the oxygen-free silicon-containing precursor. The method further includes: reacting the oxygen-free silicon-containing precursor with the radical nitrogen species to form the silicon nitride film on the substrate.

[0004] In some such examples, forming the silicon nitride film includes: forming a conformal silicon nitride film.

[0005] In some such examples, flowing the oxygen-free silicon-containing precursor additionally or alternatively includes: flowing a silane-based precursor.

[0006] In some such examples, forming the silicon nitride film additionally or alternatively includes: forming the silicon nitride film on one or more of an amorphous silicon mandrel or an amorphous carbon mandrel.

[0007] In some such examples, forming the silicon nitride film additionally or alternatively includes: forming the silicon nitride film in one or more gaps on the substrate.

[0008] In some such examples, the method additionally or alternatively includes: performing atomic layer deposition to deposit additional silicon nitride onto the silicon nitride film.

[0009] In some such examples, forming the radical nitrogen species additionally or alternatively includes: using radio frequency power in the range of 300 to 2000 watts to form the remote plasma.

[0010] In some such examples, the method additionally or alternatively includes: controlling the pressure of the processing chamber in the range of 2 torr to 8 torr when forming the silicon nitride film.

[0011] In some such examples, introducing the nitrogen-containing precursor into the remote plasma additionally or alternatively includes: introducing one or more of nitrogen, nitrogen / hydrogen, ammonia, hydrazine, or amine into the remote plasma.

[0012] Another example presents a method of forming a silicon nitride film on a substrate in a processing chamber of a chemical vapor deposition (CVD) tool. The method includes: introducing a nitrogen-containing precursor into a remote plasma formed in a remote plasma chamber of the CVD tool. The method further includes: forming radical nitrogen species in the remote plasma. The method further includes: introducing a silicon-containing precursor without oxygen into the processing chamber of the CVD tool. The method further includes: introducing the radical nitrogen species from the remote plasma chamber into the processing chamber. The method further includes: reacting the silicon-containing precursor without oxygen with the radical nitrogen species to form the silicon nitride film on the substrate. The method further includes: performing atomic layer deposition to form one or more additional silicon nitride layers on the silicon nitride film.

[0013] In some such examples, forming the silicon nitride film on the substrate includes: forming the silicon nitride film on one or more mandrels.

[0014] In some such examples, the one or more mandrels include amorphous silicon.

[0015] In some such examples, the one or more mandrels additionally or alternatively include amorphous carbon.

[0016] In some such examples, forming the silicon nitride film on the substrate additionally or alternatively includes: forming the silicon nitride film in one or more gaps on the substrate.

[0017] In some such examples, introducing the silicon-containing precursor without oxygen into the processing chamber additionally or alternatively includes: introducing a silane-based precursor into the processing chamber.

[0018] In some such examples, introducing the nitrogen precursor into the remote plasma additionally or alternatively includes: introducing one or more of nitrogen, nitrogen / hydrogen, ammonia, hydrazine, or an amine into the remote plasma.

[0019] Another example presents a chemical vapor deposition (CVD) tool. The CVD tool includes a processing chamber and a remote plasma chamber. The CVD tool also includes a radio frequency power source configured to form a plasma in the remote plasma chamber. The CVD tool also includes a nitrogen precursor source including a nitrogen-containing precursor. The CVD tool also includes a silicon-containing precursor source without oxygen including a silicon-containing precursor without oxygen. The CVD tool also includes flow control hardware configured to introduce the nitrogen-containing precursor into the remote plasma chamber and introduce the silicon-containing precursor without oxygen into the processing chamber. The CVD tool also includes a controller configured to operate the flow control hardware to introduce the nitrogen-containing precursor into the remote plasma chamber. The controller is also configured to operate the radio frequency power source to form a plasma from the nitrogen-containing precursor, the plasma including radical nitrogen species. The controller is also configured to operate the flow control hardware to flow the silicon-containing precursor without oxygen into the processing chamber. The controller is also configured to operate the flow control hardware to introduce the radical nitrogen species from the remote plasma chamber into the processing chamber to react with the silicon-containing precursor without oxygen and form a silicon nitride film on a substrate.

[0020] In some such examples, the nitrogen precursor source includes one or more of nitrogen, nitrogen / hydrogen, ammonia, hydrazine, or an amine.

[0021] In some such examples, the CVD tool additionally or alternatively includes a hydrogen-containing precursor source including hydrogen gas, and the controller is configured to operate the radio frequency power source to form the plasma from the nitrogen-containing precursor and the hydrogen gas.

[0022] In some such examples, the CVD tool additionally or alternatively includes an exhaust system, and the controller is configured to operate the exhaust system and the flow control hardware to generate a pressure in the range of 2 Torr to 8 Torr in the processing chamber when forming the silicon nitride film on the substrate. Description of the Drawings

[0023] Figure 1A-1C Schematically shows the structure formed in an exemplary atomic layer deposition (ALD) of a silicon nitride film on an amorphous silicon mandrel and a subsequent etching step that results in material loss.

[0024] Figure 2A-2B Schematically shows the expansion of an exemplary amorphous carbon mandrel resulting from the ALD deposition of a silicon nitride film.

[0025] Figure 3A flowchart is shown that depicts an exemplary method for performing chemical vapor deposition (CVD) of a silicon nitride film using radical nitrogen species formed in a remote plasma.

[0026] Figure 4A-4C A structure formed by exemplary CVD deposition of a silicon nitride film on a substrate including a mandrel is schematically shown.

[0027] Figure 5A-5C A structure formed by exemplary CVD deposition of a silicon nitride film in a gap on a substrate is schematically shown.

[0028] Figure 6 A schematic diagram of an exemplary CVD tool configured to deposit a silicon nitride film using radical nitrogen species generated in a remote plasma is shown.

[0029] Figure 7 A block diagram of an exemplary computing system is shown. DETAILED DESCRIPTION

[0030] The term "alkylamine" generally can denote a compound containing nitrogen having 1 to 3 alkyl substituents and 0 to 2 hydrogen (H) substituents. Alkylamines include primary, secondary, tertiary, and cyclic amines. Examples of alkylamines include methylamine, dimethylamine, trimethylamine, and piperidine.

[0031] The term "aspect ratio" generally can denote the ratio between the depth of a feature and the average width of that feature.

[0032] The term "atomic layer deposition" (ALD) generally can denote a process in which a film is formed on a substrate in one or more individual layers by sequentially adsorbing precursors to the substrate and reacting the adsorbed precursors to form a film layer. Examples of ALD processes include plasma-enhanced ALD (PEALD) and thermal ALD (TALD). PEALD utilizes a plasma of reaction gases to facilitate the chemical conversion of precursors adsorbed on the substrate to a film on the substrate. TALD utilizes heat to facilitate the chemical conversion of precursors adsorbed on the substrate to a film on the substrate. The terms "grow" and "deposit" and their variants can also be used to refer to film formation.

[0033] The term "ALD cycle" generally can denote a series of processes used to form a single layer of film on a substrate in an ALD process.

[0034] The term "chemical vapor deposition" (CVD) generally refers to a process in which a continuous flow of one or more precursor gases is directed onto a substrate surface under conditions configured to cause the chemical conversion of the precursor gases into a film, thereby forming a solid film on the substrate. The term "plasma-enhanced chemical vapor deposition" (PECVD) generally refers to a CVD process in which a plasma is used to facilitate the chemical conversion of one or more precursor gases into a solid film on the substrate.

[0035] The term "CVD tool" generally refers to a machine that includes a processing chamber and other hardware configured to perform CVD.

[0036] The term "conformal film" generally refers to a film with a thickness variation of 10% or less. The thickness of the conformal film at a first location can be 90% to 110% of the thickness of the film at a second location.

[0037] The term "gap" generally refers to a recess formed in the substrate surface.

[0038] The term "mandrel" generally refers to a raised structure in a patterning process that has sidewalls defining the position of a spacer. As an example, a mandrel can be formed from any polysilicon, amorphous silicon, and amorphous carbon.

[0039] The term "nitrogen-containing precursor" generally refers to any material that can be introduced into a plasma to form radical nitrogen species, which can react with one or more other precursors to form a silicon nitride film. Examples of suitable nitrogen-containing precursors can include nitrogen (N 2 ), ammonia (NH 3 ), hydrazine (N 2 H 4 ), and amines, such as diamines and alkylamines. Examples of nitrogen-containing precursors can also include mixtures of gases. Examples of gas mixtures include nitrogen / hydrogen and ammonia / hydrogen.

[0040] The term "oxygen-free silicon-containing precursor" generally refers to any molecule that does not contain oxygen and can be introduced into a processing chamber in the gas phase to react with radical nitrogen species to form a silicon-containing nitride film on a substrate. An exemplary silicon-containing nitride is silicon nitride (Si 3 N 4 ). Exemplary oxygen-free silicon-containing precursors for forming a silicon-containing nitride film can include materials having the following general structure: where R 1 , R 2 and R 3 can be the same or different substituents and can include silanes, amines, halides, hydrogen, or organic groups, such as alkylamines, alkyls, alkenyls, alkynyls, and aromatic groups.

[0041] More specific exemplary oxygen-free silicon-containing precursors include silane-based precursors (silanes and polysilanes ((H 3 Si-(SiH 2 ) n -SiH 3 ), where n≥0). Exemplary oxygen-free silicon-containing precursors also include trisilylamine (TSA). In a further example, the oxygen-free silicon-containing precursor can be an aminosilane, such as bis(diethylamino)silane, di(isopropylamino)silane, bis(tert-butylamino)silane (BTBAS), (di-sec-butylamino)silane, and tris(dimethylamino)silane (3DMAS). The aminosilane precursor can have the following general structure: H x -Si-(NR) y , where x = 1-3, x + y = 4, and R is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aromatic group, or a hydride group.

[0042] The term "patterning process" generally can denote a process for creating a topography on a substrate.

[0043] The term "plasma" generally can denote a gas containing cations and free electrons. Plasma can be used to generate reactive chemicals from precursor molecules introduced into the plasma. The term "in-situ plasma" generally can denote a plasma to which the substrate is directly exposed during processing. The term "remote plasma" generally can denote a plasma located distant from the substrate being processed.

[0044] The term "processing chamber" generally denotes a housing in which chemical and / or physical processing is performed on a substrate. The pressure, temperature, and gas composition within the processing chamber are controllable to perform chemical and / or physical processing.

[0045] The term "purge" and its variants generally can denote a process for removing unwanted substances from the processing chamber.

[0046] The term "radical" generally can denote a chemical species having an unpaired electron.

[0047] The term "radical nitrogen species" generally can denote a nitrogen atom or molecule having an unpaired electron. Examples include N, NH, NH 2 and NH 3 radicals.

[0048] The term "radio frequency (RF) power source" generally can denote a power source that is configured to provide RF power to an electrode to form a capacitively coupled plasma, or to a coil to form an inductively coupled plasma.

[0049] The term "remote plasma generator" generally can refer to one or more components of a processing tool that are configured to form a remote plasma. The remote plasma generator includes an RF power source and a remote plasma chamber in which the remote plasma is formed.

[0050] The term "silane-based precursor" generally can refer to silane and polysilanes ((H 3 Si-(SiH 2 ) n -SiH 3 ), where n ≥ 0). Exemplary polysilanes include disilane, trisilane, and tetrasilane.

[0051] The term "spacer" generally can refer to a structure formed in a patterning process that defines the spacing between a plurality of features to be formed in subsequent processing steps.

[0052] The term "substrate" generally can refer to any object on which a film can be deposited.

[0053] The term "substrate support" generally can refer to any structure for supporting a substrate in a processing chamber. Examples include a pedestal, an electrostatic chuck pedestal, and a showerhead pedestal for backside deposition processing.

[0054] As described above, silicon nitride is used to form many structures in integrated circuits. A conformal film of silicon nitride can be deposited by plasma-enhanced ALD (PEALD). In a silicon nitride PEALD cycle, a silicon-containing precursor gas is introduced into the processing chamber. The silicon-containing precursor gas is adsorbed onto the substrate in the processing chamber. The excess film precursor is swept out of the processing chamber. Then, a nitrogen-containing precursor is introduced into the processing chamber. Next, radio frequency power is applied to an electrode in the processing chamber to form a plasma. The plasma forms reactive species, such as radical nitrogen species. The radical nitrogen species react with the adsorbed silicon-containing precursor to form a silicon nitride layer. One or more PEALD cycles can be used to grow a highly conformal film of a target thickness.

[0055] However, silicon nitride deposition by PEALD may not be suitable for some applications. For example, some substrates are susceptible to plasma damage. Examples of such substrates include amorphous silicon, amorphous carbon, and chalcogenides. The film precursors for silicon nitride PEALD can include halosilanes, such as dichlorosilane or diiodosilane. The radical halogen species formed from halosilanes in the plasma may etch some substrate materials. In addition, the PEALD process may employ a relatively high-power in-situ plasma containing nitrogen and hydrogen. Such conditions may cause nitridation of the substrate.

[0056] The nitridation of the substrate may result in unwanted material loss during subsequent etching steps. This is depicted in Figure 1A-1C . Figure 1AThe substrate 100 is shown, which includes silicon mandrels 102A, 102B. The silicon mandrels 102A, 102B contain amorphous silicon (α-Si). Figure 1B The silicon nitride film 104 deposited on the silicon mandrels 102A, 102B by PEALD is shown. Since the ALD process uses direct plasma to promote the growth of the silicon nitride film 104, the reactive species formed in the direct plasma impinge on the silicon mandrels 102A, 102B. This causes the nitridation of α-Si. Nitride layers 106A, 106B are formed on the silicon mandrels 102A, 102B respectively by nitridation.

[0057] Figure 1C The substrate 100 after the etching process for removing the silicon nitride film 104 is shown. The etching process also removes at least some of the nitride layers 106A, 106B. This results in material loss from the sidewalls 110, 111 of the silicon mandrel 102A and the sidewalls 112, 113 of the silicon mandrel 102B. Due to the material loss, the silicon mandrels 102A, 102B shown in Figure 1C are thinner than those shown in Figure 1A . The material loss of the mandrels may affect pattern transfer.

[0058] The use of direct plasma during the deposition of silicon nitride by PEALD may also cause the swelling of carbon substrate features. This is depicted in Figure 2A-2B . Figure 2A The substrate 200 is shown, which includes carbon mandrels 202A, 202B. The carbon mandrels 202A, 202B contain amorphous carbon. Figure 2B The silicon nitride layers 206A, 206B deposited on the carbon mandrels 202A, 202B respectively are shown. The silicon nitride layers 206A, 206B are deposited using PEALD. Due to the use of direct plasma and high power during PEALD, the high-energy species in the plasma impinge on the carbon mandrels 202A, 202B and react with the carbon. This causes the mandrels to swell. Therefore, the carbon mandrels 202A, 202B in Figure 2B may not be suitable for patterning applications.

[0059] In the case of using halogen-containing precursors, the high-energy species in the direct plasma may also cause the halogenation and etching of chalcogenide substrate materials. Advanced memory architectures (e.g., magnetoresistive random access memory (MRAM) and phase change random access memory (PRAM)) may utilize chalcogenides such as selenium and tellurium. However, such materials may be sensitive to water vapor, oxygen, other gases, and / or plasma. For example, the plasma species used in the deposition of silicon nitride by PEALD may react with the chalcogenide to form H 2 Te or H 2Se. Because H 2 Te and H 2 Se has a relatively low boiling point, so H 2 Te or H 2 Se generation may cause etching.

[0060] Accordingly, examples of forming a silicon nitride film by CVD using radical nitrogen species formed in a remote plasma are disclosed. As described in more detail below, the disclosed examples can provide a suitably conformal film growth to serve as a protective layer before performing conformal atomic layer deposition of silicon nitride. Additionally, in cases where a relatively thin silicon nitride film is desired, the disclosed examples can be used in place of a PEALD silicon nitride deposition process. Briefly, a nitrogen-containing precursor is introduced into a remote plasma formed in a remote plasma chamber. Radical nitrogen species are formed in the remote plasma. The radical nitrogen species are introduced into a processing chamber including a substrate. An oxygen-free silicon-containing precursor is introduced into the processing chamber. The radical nitrogen species react with the oxygen-free silicon-containing precursor to form a silicon nitride film on the substrate. By using the radical species formed in the remote plasma to activate the oxygen-free silicon-containing precursor, the disclosed examples can help avoid damage from direct plasma, such as nitridation, swelling, halogenation, and etching. In some examples, using a relatively high pressure and / or a relatively low power as compared to other CVD processes can provide a suitably low impact energy to the substrate surface. Additionally, performing CVD deposition using an oxygen-free and / or halogen-free silicon-containing precursor can help avoid oxidation and / or etching of the substrate material.

[0061] Silicon nitride film deposition by CVD according to the present disclosure can be performed using precursors that are relatively inexpensive as compared to other methods (e.g., PEALD). For example, silane-based precursors such as silane and polysilane can be used. These materials may be less expensive than other silicon-containing film precursors (e.g., trisilylamine (TSA)). Accordingly, the disclosed examples can provide cost savings as compared to forming a nitride film by PEALD. The disclosed examples can also help avoid the substrate damage problems resulting from nitridation, swelling, halogenation, and / or etching described above.

[0062] As described above, the silicon nitride film deposited by CVD according to the present disclosure can be used as a standalone film to replace a PEALD silicon nitride film. This is because the disclosed CVD deposition method forms a fairly conformal silicon nitride film. Some such conformal, CVD-deposited silicon nitride films can include or a smaller thickness. Other conformal, CVD-deposited silicon nitride films according to the present disclosure can include a thickness greater than of.

[0063] In other examples, a silicon nitride film deposited by CVD according to the present disclosure can be used as an interface layer. For example, a silicon nitride film deposited by CVD according to the present disclosure can be used to form a protective silicon nitride film on a substrate surface vulnerable to PEALD damage. Subsequently, PEALD can be performed to deposit an additional silicon nitride layer onto the silicon nitride film. Thus, the silicon nitride film deposited by CVD can serve as an interface layer between the substrate material and the ALD silicon nitride layer. The conformal nature of the CVD-deposited silicon nitride interface layer allows for a similar conformal nature throughout the silicon nitride, as if depositing the silicon nitride film using only PEALD. Additionally, depositing the silicon nitride film according to the examples disclosed herein first can avoid substrate damage.

[0064] Figure 3 A flowchart showing an exemplary method 300 for forming a silicon nitride film on a substrate is presented. At 302, method 300 includes introducing a nitrogen-containing precursor into a remote plasma formed in a remote plasma chamber. The nitrogen-containing precursor can include any suitable gas that can form radical nitrogen species in the plasma. Examples include nitrogen (N 2 ), ammonia (NH 3 ), hydrazine (N 2 H 4 ), and amines, such as diamines and alkylamines. In some examples, introducing the nitrogen-containing precursor at 302 includes introducing a mixture of nitrogen and hydrogen. In such examples, at 304, method 300 can include introducing one or more of nitrogen, nitrogen / hydrogen, ammonia, hydrazine, or an amine into the remote plasma. Hydrogen can also be mixed with ammonia, hydrazine, and other nitrogen-containing precursors. In some examples, an inert gas can be flowed into the remote plasma. Exemplary inert gases include helium (He) and argon (Ar).

[0065] At 308, method 300 includes forming radical nitrogen species in the remote plasma. Examples of radical nitrogen species include N radicals, NH radicals, NH 2 radicals, and NH 3 radicals. In some examples, the radical nitrogen species can be formed by generating an inductively coupled plasma. In other examples, the radical nitrogen species can be formed by generating a capacitively coupled plasma. In further examples, a microwave plasma can be used. Any suitable radio frequency (RF) power can be used to form the plasma. In some examples, at 310, method 300 includes using an RF power in the range of 300 to 2000 watts (W) to form the remote plasma. In other examples, an RF power outside of this range can be used.

[0066] Continuing, method 300 further includes, at 312, flowing an oxygen-free silicon-containing precursor into the processing chamber. Examples of oxygen-free silicon-containing precursors can include materials having the following general structure: where R 1 , R 2 and R 3 can be the same or different substituents and can include silanes, amines, hydrogen, or organic groups such as alkylamines, alkyls, alkenyls, alkynyls, and aromatic groups.

[0067] More specific examples of oxygen-free silicon-containing precursors include silane-based precursors (silanes and polysilanes ((H 3 Si-(SiH 2 )n-SiH 3 ), where n≥0), as shown at 314. Exemplary oxygen-free silicon-containing precursors also include trisilylamine (TSA). In further examples, the oxygen-free silicon-containing precursor can include aminosilanes such as bis(diethylamino)silane, di(isopropylamino)silane, bis(tert-butylamino)silane (BTBAS), (di-sec-butylamino)silane, or tris(dimethylamino)silane (3DMAS). The aminosilane precursor can have the following general structure: H x -Si-(NR) y , where x = 1-3, x + y = 4, and R is a substituted or unsubstituted alkyl, a substituted or unsubstituted alkenyl, a substituted or unsubstituted alkynyl, a substituted or unsubstituted aromatic group, or a hydride group.

[0068] The use of silane-based precursors can provide cost savings compared to examples using more expensive precursors (e.g., trisilylamine or halosilanes). However, in other examples, trisilylamine and / or halosilane precursors can be used.

[0069] In some examples, the oxygen-free silicon-containing precursor is also halogen-free. Using an oxygen-free and halogen-free silicon-containing precursor can help avoid etching. When less concern about halide etching is required, halogen-containing precursors can be used.

[0070] In some examples, an inert gas as a carrier gas flows into the processing chamber together with the oxygen-free silicon-containing precursor. Examples include nitrogen, helium, and argon.

[0071] Method 300 further includes, at 316, introducing a radical nitrogen species from a remote plasma chamber into the processing chamber while flowing the oxygen-free silicon-containing precursor. This allows the radical nitrogen species to react with the oxygen-free silicon-containing precursor, thereby forming a silicon nitride film on the substrate.

[0072] In some examples, the substrate may include one or more mandrels. In such examples, at 318, a silicon nitride film is formed on one or more mandrels. In some examples, at 320, the mandrel includes an amorphous silicon mandrel. In some examples, at 322, the mandrel includes an amorphous carbon mandrel. In some examples, the silicon nitride film may be deposited over the mandrel to form a protective interface layer.

[0073] Since method 300 uses a remote plasma rather than a direct plasma, the method may help avoid damage, deformation, and / or nitridation of substrate features caused by the plasma. The deposition of silicon nitride on the mandrel is discussed in more detail below with reference to FIG. 5.

[0074] In other examples, method 300 may be used to form a silicon nitride film on any other suitable substrate feature. For example, at 324, a silicon nitride film may be formed in a gap on the substrate. In some such examples, the gap may include a relatively high aspect ratio, such as an aspect ratio in the range of 10:1 to 30:1.

[0075] Method 300 may utilize any suitable processing conditions to form the silicon nitride film. In some examples, the substrate is heated during the formation of the silicon nitride film. In some such examples, the substrate may be heated to a temperature in the range of 25°C to 400°C. In other examples, the substrate may be heated to a temperature above this range.

[0076] In addition, any suitable pressure may be used during the silicon nitride deposition. In some examples, at 326, method 300 includes controlling the pressure of the processing chamber in the range of 2 Torr to 8 Torr when forming the silicon nitride film. Such a pressure may help avoid damage to the substrate by reactive species formed in the remote plasma compared to a lower pressure. For example, using a relatively higher pressure compared to a relatively lower pressure may reduce the mean free path of radical nitrogen species. A shorter mean free path may reduce the impact rate of radical nitrogen species impinging on the substrate surface. A lower impact rate may help avoid plasma damage.

[0077] Additionally, any suitable RF power may be used to form the remote plasma. Examples include RF power in the range of 300 W to 2000 W. Using a relatively lower RF power compared to a relatively higher power may reduce the impact energy of radical nitrogen species on the substrate surface. A lower impact energy may help avoid plasma damage.

[0078] In some examples, processing conditions can be controlled to achieve a desired degree of conformality of the silicon nitride film. For example, using a relatively high pressure and a relatively low RF power can help obtain a relatively more conformal silicon nitride film. Thus, at 328, in some examples, method 300 includes forming a conformal silicon nitride film. The conformality of the film can refer to the film thickness at the top of the feature compared to the film thickness at another location of the feature (e.g., the bottom or the middle sidewall). In some examples, the thickness of the silicon nitride film near the bottom of the feature is in the range of 90% to 110% of the thickness of the silicon nitride film at the top of the feature. In the example of forming a silicon nitride film in one or more gaps at 324, conformal deposition can help fill the gaps without forming voids. In other examples, a less conformal silicon nitride film can be formed. A relatively high RF power and / or a relatively low pressure can be used to form a less conformal film.

[0079] In some examples, the silicon nitride film formed at 316 can be a separate film. In some examples, the separate film can have a thickness in the range of to . In other examples, the film can have a thickness outside of this range.

[0080] In other examples, the silicon nitride film formed at 316 can be an interface film. In such an example, at 330, method 300 further includes performing PEALD to deposit additional silicon nitride onto the silicon nitride film. As described above, without an interface layer, PEALD of silicon nitride can cause damage to the substrate. However, the silicon nitride film formed at 316 can protect the substrate from plasma damage during PEALD (as shown at 330).

[0081] In some examples, the silicon nitride film can be formed as part of a patterning application. For example, a silicon nitride film can be deposited over a mandrel to protect the mandrel during subsequent processing steps. Then, removing the protective silicon nitride film allows the mandrel to be used for patterning. In other examples, a silicon nitride film can be deposited to form spacers on the sidewalls of the mandrel.

[0082] Figure 4A-4C An exemplary silicon nitride film formed on a mandrel using CVD is schematically shown. First, Figure 4A a substrate 400 is depicted, which includes mandrels 402A, 402B. Mandrels 402A, 402B can include any suitable material, such as carbon or α-Si. Then, Figure 4BShows a silicon nitride film 404 deposited over mandrels 402A, 402B. Method 300 is an example of a method for forming silicon nitride film 404. The silicon nitride film 404 can include any suitable thickness. Examples include thicknesses in the range of to . In some examples, the silicon nitride film 404 can be deposited relatively conformally by using a relatively high pressure and / or a relatively low RF power.

[0083] By introducing radical nitrogen species from a remote plasma to react with a silicon-containing precursor without oxygen, damage to the mandrels 402A, 402B by the plasma can be avoided. This can help prevent material loss and / or swelling. Compared to Figure 1B , the deposition of the silicon nitride film 404 can be carried out while avoiding the nitridation of the mandrels 402A, 402B. Compared to Figure 2B , the silicon nitride film 404 can be deposited while avoiding the swelling of the mandrels 402A, 402B. Thus, in an example where the silicon nitride film 404 is removed by etching, the shapes of the mandrels 402A, 402B can be retained. This can help with patterning applications.

[0084] Figure 4C Shows an example of conformally depositing additional silicon nitride using ALD. An additional silicon nitride 406 is deposited over the silicon nitride film 404. The deposition of the additional silicon nitride 406 can be performed using any suitable ALD process, such as PEALD or thermal ALD (TALD). In a PEALD cycle, a silicon-containing precursor is introduced into the processing chamber and adsorbed onto the substrate 400. The silicon-containing precursor can include any suitable precursor that can react to form a silicon nitride film. Examples include silane-based precursors, TSA, alkylsilanes, and halosilanes. The excess silicon-containing precursor is swept out of the processing chamber. Then, a nitrogen-containing precursor is introduced. Exemplary nitrogen-containing precursors include nitrogen (N 2 ), nitrogen / hydrogen, ammonia (NH 3 ), hydrazine (N 2 H 4 ), and amines, such as diamines and alkylamines. A plasma is excited in the processing chamber to form radical nitrogen species that react with the adsorbed silicon-containing precursor to form the additional silicon nitride 406. In a TALD cycle, thermal energy can be used to facilitate the reaction. One or more ALD cycles can be performed to form a conformally deposited silicon nitride film of a target thickness.

[0085] FIG. 5 schematically shows an exemplary structure formed during a CVD process for depositing silicon nitride in a gap on a substrate 500. The substrate 500 can represent an intermediate structure in the fabrication of a trench isolation region, a memory structure, or one or more logic gates. As Figure 5AAs shown, substrate 500 includes gaps 510, 511, 512, 513, 514. The gaps can include any suitable aspect ratio. In some examples, gaps 510, 511, 512, 513, 514 can have one or more aspect ratios in the range of 10:1 to 30:1. In other examples, the gaps can have one or more aspect ratios outside of this range.

[0086] Then, Figure 5B A silicon nitride film 520 formed on substrate 500 (including in gaps 510, 511, 512, 513, 514) is shown. The silicon nitride film 520 is deposited using CVD by reacting a silicon-containing precursor without oxygen with a radical nitrogen species formed in a remote plasma. As described above, conformally depositing a film in a gap using CVD can be challenging. During CVD, the film growth rate at the top of the gap can be different from the film growth rate at the bottom of the gap. However, the disclosed examples allow for the growth of a suitably conformal silicon nitride film using CVD. For example, method 300 can be used to deposit the silicon nitride film 520 under conditions favorable for conformal film growth. As described above, a relatively high pressure and a relatively low RF power can be favorable for a conformal silicon nitride film. Thus, the thickness 522 of the silicon nitride film 520 at the top of gap 514 can be similar to the thickness 524 at the bottom of gap 514. In some examples, thickness 524 is in the range of 90% to 120% of thickness 522. Additionally, in some examples, thickness 524 is in the range of 100% to 110% of thickness 522. In some examples, a relatively low RF power can assist in achieving a ratio of thickness 524:thickness 522 that is closer to 1:1 compared to examples using a relatively high RF power. The conformal deposition of the silicon nitride film 520 can assist in avoiding the formation of reentrant features. Reentrant features narrow along a direction extending from the bottom of the gap towards the top of the gap relative to the substrate surface. Such reentrant features can be closed during subsequent conformal ALD processing.

[0087] In some examples, the silicon nitride film 520 can include separate films. In other examples, the silicon nitride film 520 can serve as an interface layer. Figure 5CShows additional silicon nitride 530 deposited over silicon nitride film 520. In this figure, silicon nitride film 520 is the interface layer. In the depicted example, the layer of silicon nitride 530 fills gaps 510, 511, 512, 513, 514. The layer of silicon nitride 530 can be deposited using ALD (e.g., PEALD or TALD). As described above, in the absence of an interface layer, PEALD of silicon nitride can cause damage to the substrate. However, silicon nitride film 520 can protect substrate 500 from plasma damage during PEALD. Additionally, the conformal nature of silicon nitride film 520 can allow for the deposition of additional silicon nitride by ALD to fill gaps 510, 511, 512, 513, 514 without forming voids (cavities) in the substrate. A void is a cavity formed in the substrate. Thus, the examples disclosed herein can help fill gaps (including high aspect ratio gaps) on a substrate while avoiding substrate damage.

[0088] Figure 6 Shows an exemplary CVD tool 600 that can be used to deposit a silicon nitride film on a substrate using remote plasma. CVD tool 600 includes a processing chamber 602 and a substrate support 604 within the processing chamber. Substrate support 604 is configured to support substrate 606 disposed within processing chamber 602. In some examples, substrate support 604 includes a substrate heater 608. Substrate support 604 can include a pedestal, an electrostatic chuck pedestal, a showerhead pedestal, or any other suitable structure.

[0089] CVD tool 600 also includes a process gas inlet 610. Process gas inlet 610 is configured to introduce radical species from remote plasma chamber 612 into processing chamber 602. In some examples, process gas inlet 610 can be configured to filter ions and / or radiation generated in remote plasma chamber 612. In some examples, process gas inlet 610 includes a showerhead.

[0090] CVD tool 600 also includes flow control hardware 614, 616. Flow control hardware 614 is connected to a nitrogen-containing precursor source 620, an optional hydrogen source 622, and an inert gas source 623. Flow control hardware 616 is connected to a silicon-containing precursor source 624 without oxygen and an inert gas source 623.

[0091] Nitrogen-containing precursor source 620 can include any suitable nitrogen-containing precursor without oxygen. Examples include nitrogen, ammonia, hydrazine, and amines such as diamines and alkylamines. Optional hydrogen source 622 includes hydrogen gas. In other examples, the hydrogen source can be omitted. In some such examples, the nitrogen-containing precursor source can include a molecule containing nitrogen (e.g., N 2 or NH 3 ) mixed with hydrogen (H 2 ).

[0092] The oxygen - free silicon - containing precursor source 624 includes any suitable oxygen - free silicon - containing precursor. Examples include silane - based precursors, TSA, and aminosilanes, as described above. Using silane - based precursors can help reduce costs compared to other precursors (e.g., TSA). However, in some examples, TSA can be used. In some examples, the oxygen - free silicon - containing precursor can be halogen - free. The inert gas source 623 can include any suitable inert gas and can include two or more different inert gases that can flow separately. Examples include helium, nitrogen, and argon.

[0093] The flow control hardware 614 is configured to control the flow of the nitrogen - containing precursor from the nitrogen - containing precursor source 620 into the remote plasma chamber 612. The flow control hardware 614 is also configured to control the flow of hydrogen from the optional hydrogen source 622 into the remote plasma chamber 612. The flow control hardware 614 is also configured to control the flow of an inert gas (e.g., He, Ar) from the inert gas source 623 into the remote plasma chamber 612. Similarly, the flow control hardware 616 is configured to control the flow of the oxygen - free silicon - containing precursor into the processing chamber 602. The flow control hardware 616 is also configured to control the flow of an inert gas (e.g., He, N 2 、Ar) into the processing chamber 602. In some examples, the inert gas flowing through the flow control hardware 616 is different from the inert gas flowing through the flow control hardware 614. The flow control hardware 614, 616 can include one or more mass flow controllers and / or valves to control the flow rate of the gas.

[0094] The remote plasma chamber 612 is configured to generate a remote plasma from the nitrogen - containing precursor to generate radical nitrogen species. In some examples, the remote plasma chamber 612 can be configured to generate an inductively coupled plasma. In other examples, the remote plasma chamber 612 can be configured to generate a capacitively coupled plasma. In additional examples, microwave plasma can be used. The radical nitrogen species can flow into the processing chamber 602 through the process gas inlet 610. The radical nitrogen species can promote the reaction with the oxygen - free silicon - containing precursor to form a silicon nitride film on the substrate 606. By forming the radical nitrogen species in the remote plasma chamber, the CVD tool 600 can help avoid damage to the substrate 606 by the plasma.

[0095] The CVD tool 600 also includes an exhaust system 632. The exhaust system 632 is configured to receive the gas flowing out of the processing chamber 602. In some examples, the exhaust system 632 is configured to actively remove the gas from the processing chamber 602 and / or apply a partial vacuum. The exhaust system 632 can include any suitable hardware, including one or more pumps.

[0096] The CVD tool 600 also includes an RF power source 634 that is electrically connected to a plasma generation circuit in the remote plasma chamber 612. Examples of plasma generation circuits include capacitor plates for generating capacitively coupled plasma or coils for generating inductively coupled plasma. The CVD tool 600 may also include a matching network 636 for impedance matching of the RF power source 634. The RF power source 634 may be configured to provide a suitable frequency and power to form a plasma in the remote plasma chamber 612. Examples of suitable frequencies include frequencies in the range from 0.3 MHz to 10 GHz. Examples of suitable power include power in the range from 300 W to 2000 W. In some examples, the radio frequency power source 634 is configured to operate at multiple different frequencies and / or powers. In other examples, microwave plasma may be used.

[0097] The controller 650 is operably coupled to the substrate heater 608, the flow control hardware 614, 616, the remote plasma chamber 612, the exhaust system 632, and the RF power source 634. The controller 650 may also be operably coupled to any other suitable components of the CVD tool 600. The controller 650 is configured to control various functions of the CVD tool 600 to deposit a silicon nitride film on a substrate. For example, the controller 650 is configured to operate the substrate heater 608 to heat the substrate. The controller 650 is also configured to operate the flow control hardware 614 to cause a nitrogen-containing precursor to flow into the remote plasma chamber 612 at a selected flow rate. In some examples, the controller 650 is also configured to control the flow control hardware 614 to cause hydrogen to flow into the remote plasma chamber 612. In some examples, the controller 650 is also configured to control the flow control hardware 614 to cause an inert gas to flow into the remote plasma chamber 612. Additionally, the controller 650 is configured to operate the RF power source 634 to form a remote plasma that is used to introduce radical nitrogen species into the processing chamber 602.

[0098] The controller 650 is also configured to operate the flow control hardware 616 to introduce a silicon-containing precursor without oxygen into the processing chamber 602. The controller 650 is also configured to operate the flow control hardware 616 to cause an inert gas to flow into the processing chamber 602 together with the silicon-containing precursor without oxygen. Thus, the controller 650 may cause the silicon-containing precursor without oxygen and the radical nitrogen species to be introduced into the processing chamber 602. The radical nitrogen species react with the silicon-containing precursor without oxygen to form a silicon nitride film on the substrate 606 in the processing chamber 602.

[0099] The controller 650 is also configured to operate the exhaust system 632 to remove gases from the processing chamber 602. The controller 650 is also configured to operate the flow control hardware 614, 616, and the exhaust system 632 to maintain a selected pressure within the processing chamber 602. In some examples, the controller 650 is configured to maintain the pressure in the range of 2 Torr to 8 Torr when flowing an oxygen-free silicon-containing precursor into the processing chamber 602.

[0100] The controller 650 is also configured to control processing conditions (e.g., pressure, RF power, gas flow) to control conformality, thickness, and other film characteristics. The controller 650 is also configured to control any other functions of the CVD tool 600.

[0101] The controller 650 may include any suitable computing system. Figure 7 A non-limiting implementation of the computing system 700 is schematically shown, which may execute one or more of the above methods and processes. The computing system 700 is shown in a simplified form. The computing system 700 may take the following forms: one or more personal computers, workstations, computers integrated with substrate processing tools, and / or network-accessible server computers.

[0102] The computing system 700 includes a logic machine 702 and a storage machine 704. The computing system 700 may optionally include a display subsystem 706, an input subsystem 708, a communication subsystem 710, and / or Figure 7 other components not shown in. The controller 650 is an example of the computing system 700.

[0103] The logic machine 702 includes one or more physical devices configured to execute instructions. For example, the logic machine may be configured to execute instructions as part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform tasks, implement data types, transform the state of one or more components, achieve technical effects, or otherwise achieve desired results.

[0104] The logic machine may include one or more processors configured to execute software instructions. Additionally or alternatively, the logic machine may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. The processors of the logic machine may be single-core or multi-core, and the instructions executed thereon may be configured for sequential, parallel, and / or distributed processing. Optionally, the various components of the logic machine may be distributed in two or more separate devices, which may be remotely located and / or configured for coordinated processing. Various aspects of the logic machine may be virtualized and executed by remotely accessible networked computing devices configured in a cloud computing configuration.

[0105] The storage machine 704 includes one or more physical devices configured to hold instructions 712 that can be executed by the logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of the storage machine 704 can be transformed—for example, to hold different data.

[0106] The storage machine 704 can include removable and / or built-in devices. The storage machine 704 can include optical memory (e.g., CD, DVD, HD-DVD, Blu-ray Disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and / or magnetic memory (e.g., hard disk drive, floppy disk drive, tape drive, MRAM, etc.). The storage machine 704 can include volatile, non-volatile, dynamic, static, read / write, read-only, random access, sequential access, location-addressable, file-addressable, and / or content-addressable devices.

[0107] It should be understood that the storage machine 704 includes one or more physical devices. Optionally, however, aspects of the instructions described herein can be propagated via a communication medium (e.g., electromagnetic signal, optical signal, etc.) that is not held by a physical device for a limited duration.

[0108] Aspects of the logic machine 702 and the storage machine 704 can be integrated together into one or more hardware logic components. For example, such hardware logic components can include field-programmable gate arrays (FPGAs), program- and application-specific integrated circuits (PASIC / ASICs), program- and application-specific standard products (PSSP / ASSPs), systems-on-a-chip (SOCs), and complex programmable logic devices (CPLDs).

[0109] When included, the display subsystem 706 can be used to present a visual representation of data held by the storage machine 704. The visual representation can take the form of a graphical user interface (GUI). Since the methods and processes described herein change the data held by the storage machine and thus the state of the storage machine, the state of the display subsystem 706 can likewise be transformed to visually represent the underlying data change. The display subsystem 706 can include one or more display devices using almost any type of technology. Such display devices can be combined with the logic machine 702 and / or the storage machine 704 in a shared enclosure, or such display devices can be peripheral display devices.

[0110] When included, input subsystem 708 may include or interface with one or more user input devices such as a keyboard, mouse, or touch screen. In some embodiments, the input subsystem may include or interface with selected natural user input (NUI) components. Such components may be integrated or peripheral, and the conversion and / or processing of input actions may be processed on-board or off-board. Exemplary NUI components may include microphones for voice and / or sound recognition, and infrared, color, stereo, and / or depth cameras for machine vision and / or gesture recognition.

[0111] When included, communication subsystem 710 may be configured to communicatively couple computing system 700 with one or more other computing devices. Communication subsystem 710 may include wired and / or wireless communication devices compatible with one or more different communication protocols. By way of non-limiting example, the communication subsystem may be configured to communicate using a wireless telephone network, or a wired or wireless local or wide area network. In some embodiments, the communication subsystem may allow computing system 700 to send and / or receive messages to and from other devices over a network such as the Internet.

[0112] It should be understood that the configurations and / or methods described herein are exemplary in nature, and these specific embodiments or examples should not be considered limiting as many variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Accordingly, the various acts shown and / or described may be performed in the shown and / or described order, in other orders, in parallel, or omitted. Likewise, the order of the above-described processing may be changed.

[0113] The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various processes, systems, and configurations, as well as other features, functions, acts, and / or properties disclosed herein, and any and all equivalents thereof.

Claims

1. A method (300) for forming a silicon nitride film on a substrate in a processing chamber by chemical vapor deposition, the method comprises: introducing (302) a nitrogen-containing precursor into a remote plasma formed in a remote plasma chamber (612) of a processing tool (600); forming (308) a radical nitrogen species in the remote plasma; flowing (312) a silicon-containing precursor without oxygen into the processing chamber of the processing tool; when flowing the silicon-containing precursor without oxygen, introducing (316) the radical nitrogen species from the remote plasma chamber into the processing chamber; and reacting (316) the silicon-containing precursor without oxygen with the radical nitrogen species to form the silicon nitride film on the substrate.

2. The method according to claim 1, wherein forming the silicon nitride film comprises: forming a conformal silicon nitride film.

3. The method according to claim 1, wherein flowing the silicon-containing precursor without oxygen comprises: flowing a silane-based precursor.

4. The method according to claim 1, wherein forming the silicon nitride film comprises: forming the silicon nitride film on one or more of an amorphous silicon mandrel or an amorphous carbon mandrel.

5. The method according to claim 1, wherein forming the silicon nitride film comprises: forming the silicon nitride film in one or more gaps on the substrate.

6. The method according to claim 1, further comprises: performing atomic layer deposition to deposit additional silicon nitride onto the silicon nitride film.

7. The method according to claim 1, wherein forming the nitrogen radical species comprises: using radio frequency power in the range of 300 watts to 2000 watts to form the remote plasma.

8. The method according to claim 1, further comprises: when forming the silicon nitride film, controlling the pressure of the processing chamber in the range of 2 Torr to 8 Torr.

9. The method according to claim 1, wherein introducing the nitrogen-containing precursor into the remote plasma comprises: introducing one or more of nitrogen, nitrogen / hydrogen, ammonia, hydrazine or amine into the remote plasma.

10. A method (600) for forming a silicon nitride film on a substrate in a processing chamber of a chemical vapor deposition (CVD) tool, the method comprises: introducing (302) a nitrogen-containing precursor into a remote plasma formed in the remote plasma chamber (612) of the CVD tool; forming (308) a radical nitrogen species in the remote plasma; introducing (312) a silicon-containing precursor without oxygen into the processing chamber of the CVD tool; introducing (316) the radical nitrogen species from the remote plasma chamber into the processing chamber; reacting (316) the silicon-containing precursor without oxygen with the radical nitrogen species to form the silicon nitride film on the substrate; and performing (330) atomic layer deposition to form one or more additional silicon nitride layers on the silicon nitride film.

11. The method according to claim 10, wherein forming the silicon nitride film on the substrate comprises: forming the silicon nitride film on one or more mandrels.

12. The method according to claim 11, wherein the one or more mandrels comprise amorphous silicon.

13. The method according to claim 11, wherein the one or more mandrels comprise amorphous carbon.

14. The method according to claim 10, wherein forming the silicon nitride film on the substrate comprises: forming the silicon nitride film in one or more gaps on the substrate.

15. The method according to claim 10, wherein introducing the oxygen-free silicon-containing precursor into the processing chamber comprises: introducing a silane-based precursor into the processing chamber.

16. The method according to claim 10, wherein introducing the nitrogen-containing precursor into the remote plasma comprises: introducing one or more of nitrogen, nitrogen / hydrogen, ammonia, hydrazine, or amine into the remote plasma.

17. A chemical vapor deposition (CVD) tool (600), which comprises: a processing chamber (602); a remote plasma chamber (612); a radio frequency power source (634) configured to form a plasma in the remote plasma chamber; a nitrogen precursor source (620) comprising a nitrogen-containing precursor; an oxygen-free silicon-containing precursor source (624) comprising an oxygen-free silicon-containing precursor; flow control hardware (614, 616) configured to introduce the nitrogen-containing precursor into the remote plasma chamber and introduce the oxygen-free silicon-containing precursor into the processing chamber; and a controller (650, 700) configured to: operate the flow control hardware to introduce (302) the nitrogen-containing precursor into the remote plasma chamber, operate the radio frequency power source to form (308) a plasma from the nitrogen-containing precursor, the plasma comprising free radical nitrogen species, operate the flow control hardware to flow (312) the oxygen-free silicon-containing precursor to the processing chamber, and operate the flow control hardware to introduce (316) the free radical nitrogen species from the remote plasma chamber into the processing chamber to react with the oxygen-free silicon-containing precursor and form a silicon nitride film on a substrate.

18. The CVD tool according to claim 17, wherein the nitrogen-containing precursor source comprises one or more of nitrogen, nitrogen / hydrogen, ammonia, hydrazine, or amine.

19. The CVD tool according to claim 17, further comprising a hydrogen-containing precursor source comprising hydrogen gas, wherein the controller is configured to operate the radio frequency power source to form the plasma from the nitrogen-containing precursor and the hydrogen gas.

20. The CVD tool according to claim 17, further comprising an exhaust system, wherein the controller is configured to operate the exhaust system and the flow control hardware to generate a pressure in the range of 2 Torr to 8 Torr in the processing chamber when forming the silicon nitride film on the substrate.

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