Circulating film deposition using reducing agent gas

Abstract

A method for depositing a film on a substrate disposed in a processing chamber includes repeating a cycle. The cycle includes a precursor step and a reactant step, and may include a purge step. A reductant step is performed during at least a portion of the cycle. The precursor step includes exposing the substrate to a precursor gas to form an intermediate film at the substrate from the precursor gas. The precursor gas may be a metal halide gas, such as a titanium tetrachloride gas. The reactant step includes exposing the substrate to a reactant gas to chemically react with the intermediate membrane to form a membrane. The reactant gas may be a hydrogen nitride gas having at least two nitrogen atoms, such as a hydrazine gas. The reductant step includes exposing the substrate to a reductant gas, such as a hydrogen-containing gas, such as hydrogen.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 351,592, filed on June 13, 2022, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present invention relates generally to systems and methods for film deposition and, in particular embodiments, to systems and methods for cyclic film deposition processes using a reducing agent gas. Background Art

[0004] Typically, microelectronic devices such as integrated circuits (ICs) are manufactured by sequentially depositing and patterning layers of dielectric, conductive, and semiconductor materials on a substrate to form a network of electronic components and interconnecting elements (e.g., transistors, resistors, capacitors, metal lines, contacts, and vias) integrated into a monolithic structure. As device size decreases and device density increases, there is an increasing demand for thinner films deposited with greater precision.

[0005] A method for depositing precision thin films is atomic layer deposition (ALD). The ALD process deposits films on a substrate by growing the film layer by layer using a cyclic process of reaction steps. During each reaction step, a precursor in a gaseous state is introduced. The precursor is chemically reacted with the surface until all thermodynamically favorable reaction sites are gone. In this way, each reaction step of the ALD process is self-limiting. Purge steps are also included between these reaction steps so that only one precursor is present at a time.

[0006] ALD processes can be used to deposit a wide variety of materials, including both pure materials and composite materials. For example, ALD processes can be used to form films of pure metals such as aluminum (Al), titanium (Ti), chromium (Cr), cobalt (Co), etc. ALD processes have also been used to combine many pure material elements such as fluorine (F), nitrogen (N), oxygen (O), and sulfur (S) to form composite materials.

[0007] The thermal balance of various substrates may be relatively low, requiring film deposition at lower temperatures to avoid damage to existing layers of the substrate. However, the film properties of films deposited at lower temperatures may not be desirable. For example, conventional TiN atomic layer deposition (ALD) using alternating exposure of TiCl4 and NH3 shows significant degradation of deposition rate and resistivity at substrate temperatures below 350°C. Therefore, new methods are needed to overcome these problems. Summary of the invention

[0008] According to an embodiment of the present invention, a method for depositing a metal nitride film on a substrate disposed in a process chamber comprises repeating a cycle including a precursor step of exposing the substrate to a metal halide gas to form an intermediate film at the substrate from the metal halide gas, and a reactant step of exposing the substrate to a nitride gas to chemically react with the intermediate film to form the metal nitride film. The nitride gas has a chemical formula N m H n , where m>1. The method further comprises a reducing agent step of exposing the substrate to hydrogen (H2) during at least a portion of each cycle.

[0009] According to another embodiment of the present invention, a method for depositing a film on a substrate disposed in a process chamber includes repeating a cycle including a precursor step of exposing the substrate to a precursor gas containing a metal to form an intermediate film containing the metal at the substrate, a precursor purge step of purging the process chamber after the precursor step, a reactant step of exposing the substrate to a reactant gas containing hydrogen and another material to chemically react with the intermediate film to form a deposited film, and a reactant purge step of purging the process chamber after the reactant step. The deposited film contains the metal and the other material. The method further includes a reducing agent step of exposing the substrate to hydrogen (H2) during at least a portion of each cycle and maintaining the substrate at a temperature of about 300°C or less for the duration of each cycle.

[0010] According to yet another embodiment of the present invention, a method for depositing a titanium nitride film on a substrate disposed in a process chamber includes repeating a cycle including a precursor step of exposing the substrate to titanium tetrachloride gas (TiCl4) to form an intermediate film comprising titanium and chlorine at the substrate, a precursor purge step of purging the process chamber after the precursor step, a reactant step of exposing the substrate to hydrazine gas (N2H4) to chemically react with the intermediate film to form the titanium nitride film, and a reactant purge step of purging the process chamber after the reactant step. The method further includes a reducing agent step of exposing the substrate to hydrogen (H2) during at least a portion of each cycle and maintaining the substrate at a temperature of about 300°C or less for the duration of each cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of the present invention and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0012] Figure 1 An exemplary method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed during at least a portion of the cycle, is presented in accordance with an embodiment of the present invention;

[0013] Figure 2 An exemplary method for depositing a titanium nitride film using a cycle including a precursor step, a precursor purge step, a reactant step, and a reactant purge step, wherein a reducing agent step is performed during at least a portion of the cycle, according to an embodiment of the present invention is presented;

[0014] Figure 3 An exemplary method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed at least during the reactant step of the cycle, according to an embodiment of the present invention is presented;

[0015] Figure 4 An exemplary method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed at least during the precursor step of the cycle, according to an embodiment of the present invention is presented;

[0016] Figure 5 An exemplary method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed at least during a reactant purge step of the cycle, according to an embodiment of the present invention is presented;

[0017] Figure 6 shows example graphs of film resistivity as a function of process temperature and gas type in accordance with embodiments of the present invention;

[0018] Figure 7 An example system for depositing a film on a substrate disposed in a processing chamber according to an embodiment of the present invention is presented, wherein the system includes a precursor gas source, a reactant gas source, and a reductant gas source;

[0019] Figure 8 shows a qualitative example graph of film resistivity as a function of reactant gas exposure time in accordance with an embodiment of the present invention;

[0020] Fig. 9 shows a qualitative example graph of membrane resistivity as a function of reductant gas flow rate in accordance with an embodiment of the present invention;

[0021] Fig.10 An example method for depositing a nitride film according to an embodiment of the present invention is presented;

[0022] Fig.11 An example method for depositing a film according to an embodiment of the present invention is presented; and

[0023] Fig.12 An example method for depositing a titanium nitride film according to an embodiment of the present invention is presented.

[0024] Unless otherwise indicated, corresponding numbers and symbols in different figures generally refer to corresponding parts. These figures are drawn to clearly show the relevant aspects of the embodiments, and these figures are not necessarily drawn to scale. The edges of features drawn in the figures do not necessarily indicate the end of the range of the features. DETAILED DESCRIPTION

[0025] The manufacture and use of various embodiments are discussed in detail below. However, it should be understood that the various embodiments described herein can be applied to a wide variety of specific situations. The specific embodiments discussed are merely illustrative of specific ways to manufacture and use the various embodiments and should not be construed as limiting the scope. Unless otherwise specified, the expressions "about" and "substantially" indicate within 10% and preferably within 5% of a given value, or, as in the case of substantially zero, less than 10% and preferably less than 5% of a comparable amount.

[0026] Film quality during microelectronic device manufacturing is an important factor in producing high-quality devices at high yields. Without achieving a specific film quality, some applications of the material may not be feasible. In addition, the properties of the deposited film may vary depending on the process conditions during film deposition. This may allow control of some film properties. However, process parameters are often subject to more considerations than just film quality. There may also be trade-offs in film properties between different process parameter groups. Therefore, it may be difficult to achieve a target film quality or set of film properties.

[0027] Temperature is an example of a process parameter that is subject to additional consideration. For example, structures on a substrate may be sensitive to high temperatures. However, conventional methods of film deposition using cyclic processes (e.g., ALD) have degraded film properties when deposited at lower temperatures (e.g., when plasma enhanced ALD (PE-ALD) is not feasible and only thermal ALD can be used). In particular, the quality of the film may decrease proportionally with the deposition temperature. An example is the resistivity of the film, for some applications, a low resistivity may be desired. At higher deposition temperatures, the resistivity may be desirably lower, while lower temperature deposition results in an undesirably higher resistivity.

[0028] In a specific example, titanium nitride (TiN) can be deposited using a cyclic film deposition process. A conventional method for depositing titanium nitride TiN films includes repeated alternating exposures of titanium tetrachloride (TiCl4) and ammonia (NH3) with a purge step between these exposures. Another known method for TiN film deposition includes repeated alternating exposures of TiCl4 and hydrazine (N2H4) with a purge step between these exposures. However, these known methods do not have the desired properties when deposited at lower temperatures (e.g., at temperatures of about 300°C or less). For example, such conventional TiN films have a resistivity greater than 350 μΩ·cm.

[0029] In various embodiments, the present invention improves the film quality for a cyclic film deposition process by including a reducing agent gas during at least a portion of each cycle. In various embodiments, a method for depositing a film on a substrate in a processing chamber includes repeating a cycle including a precursor step and a reactant step. During the precursor step, the substrate is exposed to a precursor gas (e.g., containing a metal) to form an intermediate film at the substrate. The intermediate film includes a material (e.g., a metal) from the precursor gas. During the reactant step, the substrate is exposed to a reactant gas (e.g., containing hydrogen) to chemically react with the intermediate film and form a deposited film.

[0030] The method for depositing a film also includes a reducing agent step, during which the substrate is exposed to a reducing agent gas during at least a portion of each cycle. For example, the reducing agent step can be performed simultaneously with the precursor step, with the reactant step, or with both steps. In addition, the cycle can also include a purge step. For example, a precursor purge step can be performed after the precursor step and / or a reactant purge step can be performed after the reactant step. One (or more) purge gases can be used during the purge step. For example, a carrier gas can be provided to the processing chamber without supplying precursor gas / reactant gas during the purge step.

[0031] In various embodiments, the method for depositing the film is performed at a lower temperature. For example, during the duration of each cycle, the substrate can be maintained at a lower temperature, such as at about 300° C. or lower. The method for depositing the film can be an ALD process, and in one embodiment a thermal ALD process.

[0032] The deposited film can be any number of suitable films. In some embodiments, the deposited film is a nitride film, and in one embodiment is TiN. The precursor gas can contain a metal, and in some embodiments is a metal halide gas. In one embodiment, the precursor gas is titanium tetrachloride (TiCl4), but other precursor gases are possible. In various embodiments, the reactant gas contains hydrogen, and in some embodiments is a gas having the formula N m H n A nitrogen hydride gas wherein m>1. One such nitrogen hydride gas is hydrazine (N2H4), but other nitrogen hydride gases are possible. The reducing agent gas can interact with species in the process chamber and / or at the substrate to improve film quality or change film properties during cycling. In one embodiment, the reducing agent gas is hydrogen (H2). Other reducing agent gases may also be suitable, and their selection may depend on the composition of the deposited film, the precursor gas, and / or the reactant gas.

[0033] Various embodiments can advantageously improve (e.g., reduce) the film resistivity of films deposited at lower temperatures. The ability to control the composition, timing, and flow rate of the reducing agent gas can also provide the advantage of improved control over the cyclic deposition process. The ability to deposit higher quality films at lower temperatures can advantageously allow these films to be used in more applications, such as, for example, back-end of line (BEOL) applications. The embodiments described herein can also provide the benefit of enabling purely thermal deposition of films that would otherwise require plasma enhancement to achieve the desired film properties.

[0034] The embodiments provided below describe various systems and methods for film deposition, and in particular, systems and methods for cyclic film deposition processes using a reducing agent gas. The embodiments are described in the following description. Figure 1 Used to describe an example method for depositing a film on a substrate. Figure 2 A more detailed example method of depositing the film is described. Figures 3 to 5 Three additional example methods for depositing films are described. Figure 6 Example graphs of film resistivity as a function of process temperature and gas type are shown and described. Figure 7 An example system for depositing a film on a substrate is described. Figure 8 and Fig. 9 Two additional qualitative example graphs of film resistivity as a function of process parameters are shown and described. Figures 10 to 12 Three additional example methods of depositing films are described.

[0035] Figure 1 An example method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed during at least a portion of the cycle, is presented in accordance with an embodiment of the present invention.

[0036] refer to Figure 1 , a method 100 for depositing a film on a substrate includes a cycle 102 that is repeated to form a film. For example, as shown, the cycle 102 is repeated at least once, but can be repeated as many times as needed (as shown by arrow return path 109) to deposit a film of a desired thickness on the substrate. In various embodiments, the method 100 is a layer-by-layer deposition process during which discrete processing steps are used to build up the layers of the film. In various embodiments, the method 100 is an ALD process and in one embodiment is a thermal ALD process. In one embodiment, the method 100 is a PE-ALD process. In other embodiments, the method 100 is a molecular layer deposition (MLD) process.

[0037] Each layer can be very thin, such as an atomic layer (e.g., ALD) or a molecular layer (e.g., MLD). These processing steps can be self-limiting or pseudo-self-limiting, which can promote defined endpoints for the formation of each layer and improve control over both film composition and film thickness.

[0038] Cycle 102 includes a precursor step 104 of exposing the substrate to a precursor gas 10. The substrate is exposed to the precursor gas 10 for a predetermined duration, and the precursor gas 10 is provided at a predetermined flow rate to form an intermediate film at the substrate. For example, when the precursor step 104 is performed as the first step of the method 100, the precursor gas 10 forms the intermediate film from a precursor gas 10 containing a component of the precursor gas 10. The duration of the precursor step 104 may be referred to as a precursor exposure time.

[0039] Cycle 102 further includes a reactant step 106 of exposing the substrate (i.e., including any intermediate films) to a reactant gas 12 for a predetermined duration and flow rate. The reactant gas 12 chemically reacts with the intermediate film to form a deposited film comprising components of the reactant gas 12. As with precursor step 104, the duration of reactant step 106 may be referred to as a reactant exposure time.

[0040] The precursor gas 10 can be selected so that it can form a film that reacts with the reactant gas 12 to form the desired deposited film. In some embodiments, the precursor gas 10 contains a metal, and in some embodiments, the precursor gas 10 is a metal halide. For example, the precursor gas 10 can contain one or more of any suitable metals such as titanium (Ti), tantalum (Ta), aluminum (Al), platinum (Pt), zinc (Zn), hafnium (Hf), indium (In), germanium (Ge), silicon (Si), ruthenium (Ru), etc. The precursor gas 10 can also contain one or more of any suitable halogens such as fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0041] In one embodiment, the precursor gas 10 is titanium tetrachloride (TiCl4). In another embodiment, the precursor gas 10 is titanium tetrabromide (TiBr4). In yet another embodiment, the precursor gas 10 is tantalum pentachloride (TaCl5). Of course, the precursor gas 10 can be other suitable compounds and can contain additional or alternative elements not listed here, as can be apparent to one of ordinary skill in the art.

[0042] The reactant gas 12 can be selected so that it can form a desired deposited film on the substrate by reacting with the precursor gas 10. In one embodiment, the reactant gas 12 includes hydrogen (H). In various embodiments, the reactant gas 12 includes nitrogen (N) (for example, when depositing a nitride such as TiN), and in some embodiments, the reactant gas 12 is a nitrogen hydride gas. For example, in some embodiments, the reactant gas 12 is a gas having the chemical formula N m H n In various embodiments, the reactant gas 12 may be an azane, and the reactant gas 12 is an acyclic azane, wherein in the aforementioned formula, n=m+2. In one embodiment, the reactant gas 12 is hydrazine (N2H4). In another embodiment, the reactant gas 12 is triazane (N3H5).

[0043] The reactant gas 12 may include oxygen (O) (e.g., when depositing an oxide such as aluminum oxide (Al2O3)). For example, in one embodiment, the reactant gas 12 is water vapor (H2O). In another embodiment, the reactant gas 12 is hydrogen peroxide (H2O2). Of course, the reactant gas 12 may also be other compounds and may include additional or alternative elements not listed, as may be apparent to one of ordinary skill in the art.

[0044] The cycles 102 also include a reducing agent step 108 of exposing the substrate to an additional gas, i.e., a reducing agent gas 14, such as, for example, hydrogen (H2), during at least a portion of each cycle 102. The reducing agent gas 14 can help improve the formation of the deposited film by removing excess species (e.g., halogens, such as, for example, Cl) from the substrate, film, and / or process chamber, or by enhancing a desired chemical reaction between the intermediate film and the reactant gas 12 or between the deposited film and the precursor gas 10. The reducing agent gas 14 can also react with species in the process to form byproducts that are more easily removed from the process chamber (e.g., during a purge step (when included), discussed in more detail below).

[0045] Although shown here as H2 gas, in other applications, the reductant gas 14 may be a different gas. In the case where the chemical reaction between the intermediate film formed from the precursor gas 10 and the reactant gas 12 involves hydrogen, the reductant gas 14 may be a compound containing one or more hydrogen atoms. Some examples may be NH3, N2H4, N3H5, etc. However, it should be noted that the reductant gas 14 is different from the reactant gas 12 (although there may be overlap in the gases that may be used for each in a given application).

[0046] Precursor gas 10 and / or reactant gas 12 can be provided to substrate together with carrier gas 16. Carrier gas 16 can enhance the delivery of reactive gases such as precursor gas 10 and reactant gas 12 to substrate (for example, when the flow rate of reactive gas is slightly low). Carrier gas 16 can be selected so that it does not react with other gases, film or substrate. For example, carrier gas 16 can be a rare gas or other inert gas. In one embodiment, carrier gas 16 is argon (Ar). In another embodiment, carrier gas 16 is nitrogen (N2). In yet another embodiment, carrier gas 16 is xenon (Xe).

[0047] In addition to the precursor step 104 and the reactant step 106, the cycle 102 may also include one or both of a precursor purge step 105 and a reactant purge step 107. For example, during the precursor purge step 105, instead of providing the precursor gas 10, one or more other gases (i.e., purge gas 17) may be provided to the process chamber to remove the precursor gas 10 and byproducts in preparation for the subsequent reactant step 106. Similarly, during the reactant purge step 107, instead of providing the reactant gas 12, a purge gas 17 (not necessarily the same purge gas as in the precursor purge step 105 (when included), but may be the same) may be provided to the process chamber to remove the reactant gas 12 and byproducts in preparation for the precursor step 104 of the cycle 102.

[0048] The purge gas 17 may be any suitable gas (e.g., one that does not react with the film or substrate but may react with excess material in the process chamber and form byproducts). Figure 1 As shown in , the purge gas 17 can be or include the carrier gas 16. Another gas can also be used instead of the carrier gas 16 or included with the carrier gas, such as the reductant gas 14. In some cases, when the carrier gas 16 is included in the precursor step 104 and / or the reactant step 106 and used during the purge step, the flow rate of the carrier gas 16 can be increased during the purge step, as shown qualitatively. However, in other cases, the flow rate of the carrier gas 16 can remain constant. In this regard, the flow rate of any gas can be changed or adjusted between steps and between cycles as part of a recipe or fine-tuned based on the metrology of the process chamber and the film.

[0049] The reductant gas 14 (e.g., H2 gas) may be provided during any (or all) steps of the cycle 102. In one example, the reductant gas 14 is provided only during the precursor step 104 (e.g., with the TiCl4 gas). In another example, the reductant gas 14 is provided only during the reactant step 106 (e.g., with the N2H4 gas). In yet another example, the reductant gas 14 is provided during both the precursor step 104 and the reactant step 106. In another example, the reductant gas 14 is provided throughout the cycle 102 (as shown, although the flow rate of the reductant gas 14 may vary between steps).

[0050] Because the reducing agent gas 14 can advantageously improve the film quality, the method 100 can be performed at a lower temperature than conventional methods while still obtaining the desired film properties. According to some embodiments, the substrate can be maintained at a temperature of about 300°C or lower, such as between about 250°C and about 300°C. For example, the substrate can be maintained at a temperature range of about 20°C, which is less than about 300°C, such as between about 280°C and about 300°C or between about 260°C and about 280°C, maintained at a temperature range of about 30°C, such as between about 270°C and about 290°C or between about 260°C and about 290°C, and so on. In one embodiment, the substrate temperature is maintained at about 280°C. However, the exact temperature may depend on the details of the specific application, as will be apparent to one of ordinary skill in the art.

[0051] Figure 2 An example method for depositing a titanium nitride film using a cycle including a precursor step, a precursor purge step, a reactant step, and a reactant purge step, wherein a reducing agent step is performed during at least a portion of the cycle, is presented in accordance with an embodiment of the present invention. Figure 2 The method may be other methods described herein (e.g., Figure 1 The specific implementation of the method). Similar marked elements can be as described previously.

[0052] refer to Figure 2 , a method 200 for depositing a titanium nitride film includes a cycle 202, which includes a precursor step 204, a precursor purge step 205, a reactant step 206, and a reactant purge step 207. It should be noted that for the sake of brevity and clarity, a convention is used here and below, where the element [x02] (where 'x' is a figure number) attached to the pattern can be a related implementation of the cycle in various embodiments. For example, unless otherwise specified, cycle 202 can be similar to cycle 102. Similar conventions have been used for other elements, as clearly stated by using similar terms in conjunction with the above-mentioned numbering system.

[0053] Precursor step 204 includes providing TiCl4 gas (precursor gas) to substrate 20. Other gases may also be provided together with the TiCl4 gas. For example, a carrier gas (such as argon (shown here), N2 gas, etc.) may be included during precursor step 204. A reducing agent gas (e.g., H2 gas, as shown) may also be included. The TiCl4 gas reacts with substrate 20 and forms an intermediate film containing Ti on the surface of substrate 20. In the specific interaction of TiCl4 with substrate 20 shown here, each Ti atom is bonded to substrate 20 and retains two Cl atoms, while the remaining two Cl atoms are removed (e.g., removed by an exhaust port of the processing chamber). When H2 gas is included in precursor step 204, hydrogen chloride gas (HCl) may be formed and discharged as a byproduct 13 (e.g., HCl or N2 as shown).

[0054] After the precursor step 204, TiCl4 (precursor gas) is not provided to the process chamber, and one or more gases (i.e., purge gases) are provided during the precursor purge step 205. For example, as shown, a low-reactivity gas (e.g., an inert gas such as Ar) can be included in the purge gas. The low-reactivity gas can be the same gas as the gas used as a carrier gas in the precursor step 204. Additionally or alternatively, another gas, such as H2 gas, can be provided, which can beneficially enhance the purge of undesirable species during the precursor purge step 205.

[0055] After the precursor purge step 205, the reactant step 206 includes providing N2H4 gas (hydrazine) into the process chamber to expose the intermediate film 22 to the N2H4 gas. The N2H4 gas chemically reacts with the intermediate film 22 and replaces the chlorine bonded to the titanium with nitrogen to form TiN (titanium nitride) at the substrate 20. After the reactant step 206 is performed for a sufficiently long duration (i.e., the time during which the N2H4 gas is exposed to the intermediate film 22), the first layer of the deposited film 24 (here, the TiN film) is formed.

[0056] As with the precursor step 204, a reactant purge step 207 is performed after the reactant step 206, during which no N2H4 gas is provided, but a purge gas containing one or more gases is provided. Similar to the precursor purge step 205, the purge gas may include an inert gas (e.g., Ar, N2, Xe, etc.) and / or another gas, such as H2 gas, other reducing agent gases, other carrier gases, etc.

[0057] The reactant purge step 207 can advantageously improve the quality of the film entering the next step of the cycle 202, such as by removing excess chlorine. For example, as shown, chlorine can bond with some of the nitrogen in the TiN pairs of the film. The H2 gas of the reactant purge step 207 (and other steps (when included)) can react with or enhance the removal of chlorine in the film to improve the quality of the deposited film 24, such as by reducing the resistivity of the film.

[0058] Including H2 gas during one or more steps of cycle 202 can allow the method 200 for depositing a TiN film to be effective at lower processing temperatures. For example, during cycle 202, the substrate 20 can be maintained at a temperature of about 300°C or less. In various embodiments, the substrate 20 is maintained within a desired temperature range of less than about 300°C. In one embodiment, the substrate 20 is maintained at a temperature of about 280°C.

[0059] Figure 3 An example method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed at least during the reactant step of the cycle, is presented according to an embodiment of the present invention. Figure 3 The method may be other methods described herein (e.g., Figure 1 The specific implementation of the method). Similar marked elements can be as described previously.

[0060] refer to Figure 3 , the method 300 for depositing a film includes a cycle 302, which includes a precursor step 304, a precursor purge step 305, a reactant step 306, and a reactant purge step 307. A reductant step 308 is also included, during which a reductant gas 14 is provided during the reactant step 306. As discussed above, the reductant gas 14 can be, for example, H2 gas.

[0061] As shown, the reductant gas 14 of the reductant step 308 may also be provided during the reactant purge step 307. As previously discussed, the flow rate of the reductant gas 14 may be substantially constant between steps, but it is not required that the flow rate of the reductant gas 14 remain constant during each step of the cycle 302. For example, the flow rate of the reductant gas 14 may be increased during the reactant purge step 307 relative to the reactant step 306 (or other steps performed simultaneously with the reductant step 308), as shown. Of course, the opposite may also be true in some applications (the flow rate during the reactant step 306 is higher relative to the reactant purge step 307).

[0062] Figure 4 An example method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed at least during the precursor step of the cycle, is presented according to an embodiment of the present invention. Figure 4 The method may be other methods described herein (e.g., Figure 1 The specific implementation of the method). Similar marked elements can be as described previously.

[0063] refer to Figure 4 , a method 400 for depositing a film includes a cycle 402, which includes a precursor step 404, a precursor purge step 405, a reactant step 406, and a reactant purge step 407. A reductant step 408 is also included, during which a reductant gas 14 can be provided during the precursor step 404 and / or the reactant purge step 407. Therefore, in contrast to the previous method, the reductant step 408 can be performed simultaneously with the precursor step 404, with the reactant purge step 407, or with both the precursor step 404 and the reactant purge step 407.

[0064] As already discussed, the carrier gas 16 may be provided during one or more steps of the cycle 402. For example, the carrier gas 16 may be included to help deliver reactive gases (i.e., precursor gas 10 and / or reactant gas 12 to the film / substrate) and / or be included in the purge gas 17 during one or more purge steps. As with the other gases, the flow rate of the carrier gas 16 may also be varied step-by-step or cycle-by-cycle. For illustrative purposes, the carrier gas 16 is shown here as being substantially constant between the precursor step 404 and the precursor purge step 405, but increasing during the reactant step 406, and then increasing again during the reactant purge step 407. Of course, this is just one example, and other examples are possible, as would be apparent to one of ordinary skill in the art.

[0065] Figure 5 An example method for depositing a film using a cycle including a precursor step and a reactant step, wherein a reducing agent step is performed at least during the reactant purge step of the cycle, is presented according to an embodiment of the present invention. Figure 5 The method may be other methods described herein (e.g., Figure 1 The specific implementation of the method). Similar marked elements can be as described previously.

[0066] refer to Figure 5 , a method 500 for depositing a film includes a cycle 502, which includes a precursor step 504, a precursor purge step 505, a reactant step 506, and a reactant purge step 507. A reductant step 508 is also included, during which a reductant gas 14 is provided during the reactant step 506 and the reactant purge step 507. The reductant step 508 can also be optionally performed simultaneously with the precursor purge step 505, as shown. Figure 1Similar alternatives are possible as suggested in the description of , where reductant step 508 is performed simultaneously with precursor step 504 and precursor purge step 505 , and optionally simultaneously with reactant purge step 507 .

[0067] Figure 6 An example graph of film resistivity as a function of process temperature and gas type is shown in accordance with an embodiment of the present invention. Figure 6 , Figure 600 shows the resistivity of five TiN films deposited using different reactants and conditions. The gaseous exposures were all performed without plasma excitation. The first TiN film (left) was deposited using alternating exposures of TiCl4 and NH3 at a substrate temperature of about 430°C and had a measured resistivity of about 340μΩ·cm. The second TiN film was deposited using alternating exposures of TiCl4 and NH3 at a substrate temperature of about 330°C and had a measured resistivity of greater than about 1,000μΩ·cm. The third TiN film was deposited using alternating exposures of TiCl4 and NH3 at a substrate temperature of about 280°C and had a measured resistivity of greater than about 10,000μΩ·cm. The fourth TiN film was deposited using alternating exposures of TiCl4 and N2H4 (without H2 gas) at a substrate temperature of about 280°C and had a measured resistivity of about 600μΩ·cm. The fifth TiN film (right) was deposited using alternating exposures of TiCl4 and N2H4 (with H2 gas during TiCl4 flow, N2H4 flow, and purge flow) at a substrate temperature of about 280°C and had a measured resistivity of about 350 μΩ·cm.

[0068] Figure 7 An example system for depositing a film on a substrate disposed in a processing chamber according to an embodiment of the present invention is presented, where the system includes a precursor gas source, a reactant gas source, and a reductant gas source. Figure 7 The system can be used to perform the methods described herein (e.g., Figures 1 to 5 and Figures 10 to 12 Similar labeled elements may be as previously described.

[0069] refer to Figure 7 , a system 700 for depositing a film 24 on a substrate 20 disposed in a process chamber 30 includes a substrate holder 32 that supports the substrate 20 within the process chamber 30. For example, the system 700 can be an ALD tool, an MLD tool, etc. In various embodiments, the system 700 is an ALD tool and in one embodiment is a thermal ALD tool (i.e., not configured to generate or contain a plasma). Of course, in some applications, the system 700 can be a PE-ALD.

[0070] The controller 40 is coupled to various sensors and valves in the system 700. The sensors are configured to monitor various parameters and can be configured to automatically adjust one or more variables and / or process conditions of the system 700 or the methods described herein to achieve a desired film composition and uniformity with desired film properties (i.e., film quality). Some examples of adjustable parameters include gas mixture ratios, gas timing and flow rates, exposure time, temperature (at the substrate 20, various regions of the substrate holder 32, and / or in the process chamber 30), substrate rotation, etc.

[0071] Sensors may be coupled to the process chamber 30 and positioned therein and / or about it. Various types of sensors may be included in the system 700 (e.g., depending on the details of a given application). For example, optical sensors (e.g., cameras, lasers, light, reflectometers, spectrometers, ellipsometers, etc.), capacitive sensors, ultrasonic sensors, gas sensors, or other sensors may monitor the condition of the deposited film 24, the substrate 20, and / or the system 700.

[0072] In one specific example, one or more optical sensors can be used to measure the thickness and refractive index of the deposited film in real time. In another specific example, a spectrometer can be used to measure the film thickness of one or more layers provided on the substrate 20. In one embodiment, a residual gas analyzer (RGA) can be used to detect precursor (i.e., precursor gas and / or reactant gas) breakdown for real-time chemical reaction completion detection. This information can be advantageously used to adjust the flow rate of the reducing agent gas (e.g., H2 gas) during one or more steps of the cycle in order to achieve the desired film quality.

[0073] The controller 40 is configured to control the timing and flow rates of the various source gases. To achieve this, the controller 40 is coupled to one or more valves along the fluid path between the process chamber 30 and the precursor gas source 50, the reactant gas source 52, the reductant gas source 54, and (optionally) the carrier gas source 56. The controller 40 may also be coupled to one or more optional film monitors 42, optional temperature monitors 44 (e.g., one or more disposed in the process chamber 30 and / or in the substrate holder 32), optional heaters 34, exhaust ports 36, and optional motors 38 (e.g., to rotate the substrate 20 and improve film uniformity). For example, the controller 40 may be configured to control the optional heater 34 so as to maintain the temperature of the substrate 20 at or below a desired temperature (e.g., about 300° C. or less) using the optional temperature monitor 44.

[0074] The controller 40 may be configured to analyze data collected by one or more sensors and provide feedback to control various process parameters and components of the processing chamber 30. The controller 40 may use or analyze sensor data to determine when to end one or more steps of the method described herein. For example, the controller 40 may receive data from a residual gas analyzer to detect the end point of the film deposition process. In another example, the controller 40 may utilize ellipsometry to detect the average film thickness of the film deposited on the substrate 20 during rotation, and provide an indication of the change in film thickness during the process. In another example, the controller 40 may utilize ellipsometry to detect the refractive index of the film deposited on the substrate during rotation, and provide an indication of the change in film composition during the ALD process. In some embodiments, the controller 40 may automatically end the deposition process when the desired film thickness is achieved.

[0075] The sensor data and controller 40 can also be used to achieve desired throughput targets. For example, adding a reducing agent gas during a deposition process can advantageously improve film quality. The controller 40 can be configured to optimize the process to increase throughput by increasing the flow rate of the reducing agent gas, thereby allowing exposure time or purge time to be reduced and throughput to be increased relative to conventional methods.

[0076] The controller 40 can be implemented in a variety of ways. In one example, the controller 40 can be a computer (e.g., a general-purpose computer). In another example, the controller 40 can include one or more programmable integrated circuits programmed to provide the functions described herein. For example, one or more processors (e.g., microprocessors, microcontrollers, central processing units, etc.), programmable logic devices (e.g., complex programmable logic devices (CPLDs)), field programmable gate arrays (FPGAs), etc.) and / or other programmable integrated circuits can be programmed with software or other programming instructions to implement the functions described herein for the controller 40.

[0077] In various embodiments, the software or other programming instructions may be stored in one or more non-transitory computer-readable media (e.g., memory storage devices, flash memory, dynamic random access memory (DRAM), reprogrammable storage devices, hard drives, floppy disks, DVDs, CD-ROMs, etc.), and when executed by a programmable integrated circuit, the software or other programming instructions cause the programmable integrated circuit to perform the processes, functions, and / or capabilities described herein. Other variations may also be implemented as may be apparent to one of ordinary skill in the art.

[0078] Figure 8 Qualitative example graphs of film resistivity as a function of reactant gas exposure time according to embodiments of the present invention are presented. Figure 8, graph 800 shows film resistivity (e.g., for a TiN film deposited using alternating exposures of TiCl4 and N2H4) as a function of exposure time for a reactant gas flow (e.g., N2H4) at a lower flow rate (e.g., 500 sccm (standard cubic centimeters per minute)) and a higher flow rate (e.g., 2000 sccm). A reducing agent gas is provided during some or all steps of each cycle, such as providing H2 gas during the TiCl4 flow, the N2H4 flow, and / or the purge flow. The substrate temperature can be maintained at a lower temperature, such as about 280°C. Graph 800 shows that increasing the reactant exposure time (e.g., from about 0.5 s to about 2.5 s) reduces the resistivity (e.g., from about 550 μΩ·cm to about 350 μΩ·cm, or about 60% in the context of a specific example).

[0079] Of course, graph 800 is intended to be qualitative in nature. Specific values ​​are given as examples and will vary depending on various factors specific to a given application. For example, the precursors, reactants, reducing agents, and / or carrier gases may be different. Flow rates may be higher or lower and may be adjusted to achieve a particular result. Similarly, exposure times may be longer or shorter. Beneficial results (such as here film resistivity) may improve at different rates relative to changes in exposure time.

[0080] Fig. 9 A qualitative example graph of membrane resistivity as a function of reductant gas flow rate is shown according to an embodiment of the present invention. Fig. 9 , graph 900 shows film resistivity (e.g., for a TiN film deposited using alternating exposures of TiCl4 and N2H4) as a function of reducing agent gas flow rate (e.g., H2 gas during TiCl4 flow, N2H4 flow, and / or purge flow). The substrate temperature can be maintained at a relatively low temperature (e.g., about 280°C). Graph 900 shows that increasing the flow rate of the reducing agent gas (e.g., from about 0 sccm to about 1000 sccm) reduces the resistivity of the film (e.g., from about 400 μΩ·cm to about 350 μΩ·cm, or about 10% in the context of a specific example).

[0081] As previously mentioned, graph 900 is also intended to be qualitative in nature. Specific values ​​are given as examples and will vary depending on various factors specific to a given application. For example, the precursor, reactant, reductant, and / or carrier gas may be different. The flow rate may be higher or lower and may be adjusted to achieve a particular result. Beneficial results (such as here film resistivity) may be improved at different rates relative to changes in reductant gas flow.

[0082] Fig.10 An example method for depositing a nitride film according to an embodiment of the present invention is presented. Fig.10 The method can be combined with other methods and performed using the systems and devices described herein. For example, Fig.10 The method can be used with Figures 1 to 5 , Figure 7 , Fig. 9 and Figure 11 to Figure 12 Although shown in a logical order, Fig.10 The arrangement and numbering of the steps are not intended to be limiting. As will be apparent to one skilled in the art, Fig.10 The method steps may be performed in any suitable order or concurrently with each other.

[0083] refer to Fig.10 , a method 1000 for depositing a metal nitride film on a substrate disposed in a process chamber includes repeating 1009 a cycle 1002. The cycle 1002 includes a precursor step 1004 of exposing the substrate to a metal halide gas to form an intermediate film at the substrate from the metal halide gas and a reactant step 1006 of exposing the substrate to a nitrogen hydride gas to chemically react with the intermediate film to form a metal nitride film. The nitrogen hydride gas has a chemical formula N m H n , where m>1. The method 1000 further includes exposing the substrate to a reducing agent step 1008 of hydrogen (H 2 ) during at least a portion of each cycle 1002 .

[0084] Fig.11 An example method for depositing a film according to an embodiment of the present invention is presented. Fig.11 The method can be combined with other methods and performed using the systems and devices described herein. For example, Fig.11 The method can be used with Figures 1 to 5 , Figure 7 , Figures 9 and 10 and Fig.12 Although shown in a logical order, Fig.11 The arrangement and numbering of the steps are not intended to be limiting. As will be apparent to one skilled in the art, Fig.11 The method steps may be performed in any suitable order or concurrently with each other.

[0085] refer to Fig.11, a method 1100 for depositing a film on a substrate disposed in a process chamber includes repeating 1109 a cycle 1102. The cycle 1102 includes a precursor step 1104 of exposing the substrate to a precursor gas containing a metal to form an intermediate film containing the metal at the substrate, a precursor purge step 1105 of purging the process chamber after the precursor step, a reactant step 1106 of exposing the substrate to a reactant gas containing hydrogen and another material to chemically react with the intermediate film to form a deposited film, and a reactant purge step 1107 of purging the process chamber after the reactant step. The deposited film contains the metal and the additional material.

[0086] The method 1100 further includes exposing the substrate to a reducing agent step 1108 of hydrogen (H 2 ) during at least a portion of each cycle 1102 and maintaining the temperature in step 1119 at a temperature of about 300° C. or less for the duration of each cycle 1102 .

[0087] Fig.12 An example method for depositing a titanium nitride film according to an embodiment of the present invention is presented. Fig.12 The method can be combined with other methods and performed using the systems and devices described herein. For example, Fig.12 The method can be used with Figures 1 to 5 , Figure 7 and Figures 9 to 11 Although shown in a logical order, Fig.12 The arrangement and numbering of the steps are not intended to be limiting. As will be apparent to one skilled in the art, Fig.12 The method steps may be performed in any suitable order or concurrently with each other.

[0088] refer to Fig.12 , a method 1200 for depositing a titanium nitride film on a substrate disposed in a process chamber includes repeating 1209 a cycle 1202. The cycle 1202 includes a precursor step 1204 of exposing the substrate to titanium tetrachloride gas (TiCl4) to form an intermediate film comprising titanium and chlorine at the substrate, a precursor purge step 1205 of purging the process chamber after the precursor step, a reactant step 1206 of exposing the substrate to hydrazine gas (N2H4) to chemically react with the intermediate film to form a titanium nitride film, and a reactant purge step 1207 of purging the process chamber after the reactant step.

[0089] The method 1200 further includes exposing the substrate to a reducing agent step 1208 of hydrogen (H 2 ) during at least a portion of each cycle 1202 and maintaining the temperature in step 1219 at a temperature of about 300° C. or less for the duration of each cycle 1202 .

[0090] This summarizes example embodiments of the present invention. Other embodiments may also be understood from the entire specification and the claims presented herein.

[0091] Example 1. A method for depositing a metal nitride film on a substrate disposed in a process chamber, the method comprising: repeating a cycle including a precursor step of exposing the substrate to a metal halide gas to form an intermediate film at the substrate from the metal halide gas, and a reactant step of exposing the substrate to a nitrogen hydride gas to chemically react with the intermediate film to form the metal nitride film, the nitrogen hydride gas having a chemical formula N m H n , where m>1; and a reducing agent step of exposing the substrate to hydrogen (H2) during at least a portion of each cycle.

[0092] Example 2. The method of Example 1, wherein the reducing agent step is performed only during the precursor step of the cycle.

[0093] Example 3. The method of one of Examples 1 and 2, wherein the cycle further comprises a precursor purge step of purging the process chamber using a purge gas after the precursor step.

[0094] Example 4. The method of any one of Examples 1 to 3, wherein the cycle further comprises a reactant purge step of purging the process chamber using a purge gas after the reactant step.

[0095] Example 5. The method as described in one of Examples 3 and 4, wherein the reducing agent step is performed only during at least one of the precursor step and the reactant purge step.

[0096] Example 6. The method of Example 5, wherein the reducing agent step is performed only during the reactant purge step.

[0097] Example 7. The method of one of Examples 3 and 4, wherein the purge gas is argon (Ar).

[0098] Example 8. The method of one of Examples 3 and 4, wherein the purge gas is nitrogen (N2).

[0099] Example 9. The method of any one of Examples 1 to 8, further comprising: flowing a carrier gas into the processing chamber during at least a portion of the cycle.

[0100] Example 10. The method of Example 9, wherein the carrier gas is argon (Ar).

[0101] Example 11. The method of Example 9, wherein the carrier gas is nitrogen (N2).

[0102] Example 12. The method of any one of Examples 1 to 11, wherein the metal halide gas contains titanium.

[0103] Example 13. The method of any one of Examples 1 to 12, wherein the metal halide gas comprises tantalum.

[0104] Example 14. The method of any one of Examples 1 to 13, wherein the metal halide gas comprises chlorine.

[0105] Example 15. The method of Example 14, wherein the metal halide gas is titanium tetrachloride (TiCl4).

[0106] Example 16. The method of any one of Examples 1 to 14, wherein the metal halide gas contains bromine.

[0107] Example 17. The method of any one of Examples 1 to 16, wherein the nitrogen hydrogen compound gas is a non-cyclic azane, wherein n=m+2.

[0108] Example 18. The method of Example 17, wherein the nitrogen hydrogen compound gas is hydrazine (N2H4).

[0109] Example 19. The method of Example 17, wherein the nitrogen hydrogen compound gas is triazine (N3H5).

[0110] Example 20. The method of any one of Examples 1 to 19, further comprising: maintaining the substrate at a temperature of about 300° C. or less for the duration of each cycle.

[0111] Example 21. A method for depositing a film on a substrate arranged in a processing chamber, the method comprising: repeating a cycle, the cycle comprising a precursor step of exposing the substrate to a precursor gas containing a metal to form an intermediate film containing the metal at the substrate, a precursor purge step of purging the processing chamber after the precursor step, a reactant step of exposing the substrate to a reactant gas containing hydrogen and another material to chemically react with the intermediate film to form a deposited film, wherein the deposited film contains the metal and the other material, and a reactant purge step of purging the processing chamber after the reactant step; a reducing agent step of exposing the substrate to hydrogen (H2) during at least a portion of each cycle; and maintaining the substrate at a temperature of about 300°C or less for the duration of each cycle.

[0112] Example 22. The method of Example 21, wherein the precursor gas comprises titanium.

[0113] Example 23. The method of one of Examples 21 and 22, wherein the precursor gas contains aluminum.

[0114] Example 24. The method of any one of Examples 21 to 23, wherein the reactant gas is hydrazine (N2H4).

[0115] Example 25. The method of any one of Examples 21 to 23, wherein the reactant gas is water vapor.

[0116] Example 26. The method of any one of Examples 21 to 23, wherein the reactant gas is hydrogen peroxide (H2O2).

[0117] Example 27. A method for depositing a titanium nitride film on a substrate arranged in a processing chamber, the method comprising: repeating a cycle, the cycle including a precursor step of exposing the substrate to titanium tetrachloride gas (TiCl4) to form an intermediate film comprising titanium and chlorine at the substrate, a precursor purge step of purging the processing chamber after the precursor step, a reactant step of exposing the substrate to hydrazine gas (N2H4) to chemically react with the intermediate film to form the titanium nitride film, and a reactant purge step of purging the processing chamber after the reactant step; a reducing agent step of exposing the substrate to hydrogen (H2) during at least a portion of each cycle; and maintaining the substrate at a temperature of about 300°C or less for the duration of each cycle.

[0118] Example 28. The method of Example 27, wherein the reducing agent step is performed only during at least one of the precursor step and the reactant purge step.

[0119] Example 29. The method of Example 28, wherein the reducing agent step is performed only during the precursor step.

[0120] Example 30. The method of any one of Examples 27 to 29, wherein the temperature is about 280°C.

[0121] Example 31. The method of any one of Examples 27 to 30, wherein the titanium nitride film has a resistivity of about 350 μΩ·cm or less.

[0122] Although the present invention has been described with reference to illustrative embodiments, this description is not intended to be interpreted in a limiting sense. Various modifications and combinations of the illustrative embodiments and other embodiments of the present invention will be apparent to those skilled in the art with reference to the description. Therefore, the appended claims are intended to cover any such modifications or embodiments.

Claims

1. A method for depositing a metal nitride film on a substrate disposed in a processing chamber, the method comprising: Repeat the cycle, which includes exposing the substrate to a metal halide gas to form a precursor step of an intermediate film at the substrate from the metal halide gas, and The substrate is exposed to a nitrogen hydride gas having a chemical formula N to react with the intermediate film to form the metal nitride film. m H n , where m>1; as well as The substrate is exposed to a reducing agent step of hydrogen (H2) during at least a portion of each cycle.

2. The method of claim 1, wherein: The reductant step is performed only during the precursor step of the cycle.

3. The method of claim 1, wherein: The cycle further comprises at least one of the following steps a precursor purge step of purging the process chamber using a purge gas after the precursor step, and The reactant step is followed by a reactant purge step in which the process chamber is purged using a purge gas.

4. The method of claim 3, wherein: The reducing agent step is performed only during at least one of the precursor step and the reactant purge step.

5. The method of claim 4, wherein: The reducing agent step is performed only during the reactant purge step.

6. The method of claim 1, wherein: The metal halide gas contains titanium.

7. The method of claim 1, wherein: The metal halide gas contains tantalum.

8. The method of claim 1, wherein: The metal halide gas contains chlorine.

9. The method of claim 8, wherein: The metal halide gas is titanium tetrachloride (TiCl4).

10. The method of claim 1, wherein: The metal halide gas contains bromine.

11. The method of claim 1, wherein: The nitrogen hydrogen compound gas is hydrazine (N2H4).

12. The method of claim 1, wherein: The nitrogen hydrogen compound gas is triazine (N3H5).

13. A method for depositing a film on a substrate disposed in a processing chamber, the method comprising: Repeat the cycle, which includes a precursor step of exposing the substrate to a precursor gas comprising a metal to form an intermediate film comprising the metal at the substrate, a precursor purge step to purge the process chamber after the precursor step, exposing the substrate to a reactant gas comprising hydrogen and another material to chemically react with the intermediate film to form a deposited film, wherein the deposited film comprises the metal and the other material, and a reactant purge step of purging the process chamber after the reactant step; exposing the substrate to a reducing agent step of hydrogen (H2) during at least a portion of each cycle; as well as The substrate is maintained at a temperature of about 300° C. or less for the duration of each cycle.

14. The method of claim 13, wherein: The precursor gas includes titanium.

15. The method of claim 13, wherein: The precursor gas contains aluminum.

16. The method of claim 13, wherein: The reactant gas is hydrazine (N2H4).

17. The method of claim 13, wherein: The reactant gas is water vapor.

18. A method for depositing a titanium nitride film on a substrate disposed in a processing chamber, the method comprising: Repeat the cycle, which includes a precursor step of exposing the substrate to titanium tetrachloride gas (TiCl 4 ) to form an intermediate film comprising titanium and chlorine at the substrate, a precursor purge step to purge the process chamber after the precursor step, exposing the substrate to hydrazine gas (N2H4) to chemically react with the intermediate film to form the titanium nitride film, and a reactant purge step of purging the process chamber after the reactant step; exposing the substrate to a reducing agent step of hydrogen (H2) during at least a portion of each cycle; as well as The substrate is maintained at a temperature of about 300° C. or less for the duration of each cycle.

19. The method of claim 18, wherein: The reducing agent step is performed only during at least one of the precursor step and the reactant purge step.

20. The method of claim 19, wherein: The reducing agent step is performed only during the precursor step.

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