Bottom-up molybdenum gap filling

Abstract

Embodiments of the present disclosure relate to a method for molybdenum gap filling. Additional embodiments provide a method for forming molybdenum gap fills that are void-free. Some embodiments of the present disclosure relate to higher aspect ratio features including DRAM memory cells.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a method for depositing a molybdenum film within a substrate feature. More particularly, embodiments of the present disclosure are directed to a method for providing bottom-up gap filling by a cyclic deposition etching process.

Background Art

[0002] The gap filling process is essential for several semiconductor manufacturing processes. The gap filling process can be used to fill a gap (or feature) with an insulating material or a conductor material. For example, shallow trench isolation, inter-metal dielectric layer, passivation layer, dummy gate are all generally realized by a gap filling process.

[0003] As the device geometry continues to shrink (e.g., critical dimensions <20 nm, <10 nm, and more), and the thermal history is reduced, void-free space filling becomes increasingly difficult due to the limitations of conventional deposition processes.

[0004] Most conventional deposition methods, especially chemical vapor deposition methods, deposit more material on the substrate surface than within the feature, particularly near the bottom of the feature.

[0005] As a result, the film on the substrate surface must be removed through an etching process after the gap filling deposition is completed. This additional processing step reduces throughput and increases manufacturing costs.

[0006] Other gap filling methods rely on atomic layer deposition to form the metal gap filling material. These methods generally create a conformal film on all substrate surfaces. Thus, these methods also require etching of the material deposited outside the feature, but often create gap filling with a seam in the middle because the film is formed from the sidewalls and meets in the middle.

[0007] Accordingly, there is a need for a gap filling method that enables a larger throughput and is deposited in a bottom-up manner to avoid defects in gap filling. SUMMARY OF THE INVENTION

[0008] One or more embodiments of the present disclosure are directed to a method of depositing a molybdenum gap fill. The method includes exposing a substrate surface having at least one feature formed therein to a first molybdenum precursor and a reducing agent to form a first gap fill within the at least one feature. The at least one feature has an opening and two sidewalls and extends by a depth from a top surface to a bottom surface. The substrate surface is exposed to a second molybdenum halide precursor to remove a portion of the first gap fill and the formation of the first gap fill is repeated.

[0009] Additional embodiments of the present disclosure are directed to a method of depositing a molybdenum gap fill. The method includes exposing a substrate surface having at least one feature formed therein to MoO2Cl2 and H2 to form a first gap fill within the at least one feature. The at least one feature has an opening and two sidewalls and extends by a depth from a top surface to a bottom surface. The feature has an aspect ratio of about 100:1 or more. The substrate surface is exposed to MoCl5 to remove a portion of the first gap fill and the formation and removal of the first gap fill are repeated until the at least one feature is completely filled.

[0010] To enable a more detailed understanding of the features enumerated above of the present disclosure, the present disclosure outlined above may be described in further detail with reference to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings merely illustrate general embodiments of the present disclosure, and thus, the present disclosure should not be considered as being limited in scope since it can admit other equally effective embodiments. The embodiments described herein are illustrative by way of example and are not limited to the figures of the accompanying drawings in which like reference numerals indicate similar elements.

Brief Description of the Drawings

[0011]

Figure 1

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Modes for Carrying Out the Invention

[0012] Before describing some exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of the configurations or process steps described in the following description. The present disclosure is capable of other embodiments and can be practiced or implemented in various ways.

[0013] As used herein, the term “about” means “approximately” or “nearly” and, in the context of the numerical values or ranges being described, means a variation of not more than ±15% of the numerical value. For example, values that differ by ±14%, ±10%, ±5%, ±2%, ±1%, ±0.5%, or ±0.1% would satisfy the definition of about.

[0014] As used in this specification and the claims, the terms "substrate" or "wafer" refer to the surface on which a process is performed, or a portion of the surface. It will be understood by those skilled in the art that references to a substrate may, in some cases, refer only to a portion of the substrate, unless otherwise explicitly indicated by the context. Additionally, references to depositing on a substrate may, in some cases, mean a bare substrate and a substrate on which one or more films or features have been deposited or formed.

[0015] "Substrate surface", as used herein, refers to any substrate or the surface of a material formed on a substrate on which film processing is performed during a manufacturing process. For example, substrate surfaces on which processing can be performed include, depending on the application, silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, and any other material such as metals, metal nitrides, alloys, and other conductor materials. Non-limiting examples of substrates include semiconductor wafers. The substrate may be exposed to a pretreatment process that performs polishing, etching, reduction, oxidation, hydroxylation, annealing, and / or firing of the substrate surface. In addition to direct film processing on the surface of the substrate itself, in the present disclosure, any of the disclosed film processing steps may also be performed on an underlying layer formed on the substrate, as will be disclosed in more detail below, and the term "substrate surface" is intended to include such underlying layer as indicated by the context. Thus, for example, when a film / layer or partial film / layer is deposited on a substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0016] The substrate surface may have one or more features formed therein, one or more layers formed thereon, and combinations thereof. The shape of the feature can have any suitable shape including, but not limited to, peaks, trenches, holes, and vias (circular or polygonal). As used herein, the term "feature" refers to any intentional surface irregularity. Suitable examples of features include, but are not limited to, trenches having a top, two sidewalls, and a bottom extending into the substrate, and vias having one or more sidewalls extending into the substrate to the bottom.

[0017] The term "on" indicates that the elements are in direct contact with each other. The term "directly on" indicates that the elements are in direct contact with each other without intervening elements.

[0018] As used in this specification and the appended claims, terms such as "precursor", "reagent", "reactive gas", etc. are used interchangeably to refer to any gas species capable of reacting with the substrate surface.

[0019] Embodiments of the present disclosure advantageously provide a method for depositing molybdenum gap fill in a bottom-up manner. Further embodiments advantageously provide a method for depositing gap fill with reduced defects (e.g., voids).

[0020] Embodiments of the present disclosure are described using drawings that illustrate processes and substrates in accordance with one or more embodiments of the present disclosure. The processes, schematics, and resulting substrates illustrated are merely examples of the disclosed processes, and those skilled in the art will recognize that the disclosed processes are not limited to the illustrated applications.

[0021] Referring to FIGS. 1 to 2C, the present disclosure relates to a method 100 for depositing molybdenum interstitial fill. FIG. 1 shows a process flow diagram of a deposition method 100 according to one or more embodiments of the present disclosure. FIGS. 2A to 2D show a substrate 200 being processed according to one or more embodiments of the present disclosure.

[0022] FIG. 2A shows a substrate 200 having a substrate surface 205. As described above, the substrate surface refers to the exposed surface of the substrate on which a layer may be formed. The substrate surface 205 has at least one feature 210 formed therein. Although only a single feature is shown in the drawing, those skilled in the art will recognize that multiple features will be affected in a similar manner by the disclosed method.

[0023] At least one feature 210 has an opening 212 having a width W. The opening 212 is formed in the upper surface 215 of the substrate 200. The feature 210 also has one or more sidewalls 214 and extends by a depth D from the upper surface 215 to the bottom 216. Although straight vertical sidewalls are shown in the drawing, the disclosed method may also be implemented for diagonal, irregular, or inwardly recessed sidewalls.

[0024] In some embodiments, the width W of the opening 212 is about 10 nm or more, about 15 nm or more, about 20 nm or more, about 25 nm or more, about 30 nm or more, or about 35 nm or more. In some embodiments, the width W is in the range of about 5 nm to about 15 nm, or in the range of about 10 nm to about 35 nm.

[0025] In some embodiments, the depth D of the feature 210 is about 50 nm or more, about 75 nm or more, about 100 nm or more, about 150 nm or more, about 200 nm or more, or about 250 nm or more. In some embodiments, the depth D is in the range of about 100 nm to about 200 nm, or in the range of about 200 nm to about 250 nm.

[0026] One skilled in the art will recognize that it becomes increasingly difficult to deposit intermetallic gap fillings within features of narrow width (also known as critical dimension (CD)) and / or increasing depth. The aspect ratio of at least one feature 210 is defined as the depth D of the feature 210 divided by the width W. In some embodiments, at least one feature has an aspect ratio (D:W) of about 20:1 or greater, about 50:1 or greater, or about 100:1 or greater.

[0027] As described above, in some embodiments, the substrate 200 includes a plurality of features 210. Some embodiments of the present disclosure advantageously provide molybdenum gap fillings for DRAM memory cell formation. In other words, in some embodiments, at least one feature forms a memory cell of a DRAM.

[0028] Referring to FIGS. 1 and 2B, method 100 begins at operation 110. At 110, a first gap filling 220 is formed within at least one feature 210 on the substrate surface 205. In some embodiments, as shown in FIG. 2B, the first gap filling 220 is deposited on the top surface 215 and the bottom surface 216. Although at least some of the gap filling material is considered to be formed on the sidewalls 214, for clarity, the sidewall deposition is not shown in the drawings.

[0029] At operation 110, the first gap filling 220 is formed by exposing the substrate surface to a first molybdenum precursor and a reducing agent. In some embodiments, the first molybdenum precursor and the reducing agent are exposed to the substrate simultaneously. In some embodiments, both the first molybdenum precursor and the reducing agent are continuously flowed into the processing space above the substrate. In some embodiments, the first molybdenum precursor is continuously flowed and the reducing agent is pulsed or flowed intermittently.

[0030] In some embodiments, the first molybdenum precursor comprises a molybdenum oxyhalide. In some embodiments, the first molybdenum precursor comprises or consists essentially of MoO2Cl2. The reducing agent may be any suitable reducing agent. In some embodiments, the reducing agent comprises or consists essentially of hydrogen gas (H2). When used in this context, a process gas "consisting essentially of" the indicated reactant, excludes any inert diluent or carrier gas and comprises, on a molar basis, more than about 95%, more than about 98%, more than about 99%, or more than about 99.5% of the indicated reactant.

[0031] In some embodiments, the first gap fill 220 has an upper thickness T on the top surface 215 T and a bottom thickness T on the bottom 216. B In some embodiments, the upper thickness T T is greater than the bottom thickness T. B In some embodiments, the upper thickness T T is at least 20 Å. In some embodiments, the bottom thickness T B is at least 10 Å. In some embodiments, the bottom thickness T B is in the range of about 10 Å to about 50 Å.

[0032] In some embodiments, operation 110 represents a chemical vapor deposition (CVD) process. In some embodiments, the temperature of the CVD process is in the range of about 450 °C to about 600 °C, or in the range of about 500 °C to about 600 °C. In some embodiments, the CVD process is performed without plasma.

[0033] Method 100 continues with operation 120 after the formation of the first gap fill 220. In some embodiments, if there is remaining reactive gas on the substrate surface 205, it is purged before proceeding to operation 120.

[0034] Referring to FIG. 2C, following operation 120, the substrate surface 205 is exposed to a second molybdenum halide precursor, and a portion of the first gap fill 220 is removed. In some embodiments, the thickness of the first gap fill 220 on the top surface 215 is significantly reduced compared to the thickness of the first gap fill on the bottom surface 216. In some embodiments, the first gap fill 220 is completely removed from the top surface 215. In some embodiments, the exposure to the second molybdenum halide removes the thickness of the first gap fill in the range of about 10 Å to about 50 Å.

[0035] Without being bound by theory, one possible explanation is that since the top surface is more exposed to the second molybdenum halide, the first gap fill on the top surface is etched more easily than the first gap fill at the bottom of the more protected features.

[0036] The second molybdenum halide can be any suitable compound that reacts with the first gap fill to etch / remove the first gap fill. The second molybdenum halide includes one or more halide ligands. In some embodiments, the second molybdenum halide includes one or more of MoCl5 or MoF6. In some embodiments, the second molybdenum halide consists essentially of MoCl5.

[0037] In some embodiments, the second molybdenum halide is delivered from a heated ampoule using a carrier gas. The carrier gas can be any suitably inert gas that does not react with or otherwise alter the first metal halide. In some embodiments, the carrier gas includes argon. In some embodiments, the ampoule is heated to a temperature in the range of about 90° C. to about 105° C.

[0038] If there is remaining reactive gas on the substrate surface 205 after a predetermined amount of the first gap fill has been removed or after a predetermined exposure period to the second molybdenum halide precursor, it is purged before proceeding to decision point 130.

[0039] At decision point 130, it is determined whether the first gap fill 220 has achieved a predetermined thickness. If it has been achieved, method 100 ends. If not, method 100 returns to operation 110 to form an additional first gap fill 220. The cycle of deposition (operation 110) and etching (operation 120) is repeated until the predetermined thickness of the first gap fill 220 is achieved.

[0040] Referring to FIG. 2D, in some embodiments, the cycle of deposition and etching is repeated until the entire depth D of at least one feature 210 is filled. In some embodiments, the number of deposition-etching cycles ranges from about 200 to about 400 cycles, or from about 250 to about 350 cycles.

[0041] The inventors have surprisingly found that by using cycles of deposition and etching rather than simply using a long deposition operation, a first gap fill 220 can be formed without closing the opening of at least one feature. Without being bound by theory, the etching operation 120 removes more material from the top surface 215 than from the bottom surface 216, so the inventors believe that features with a higher aspect ratio can be filled without "pinching off" the opening or forming voids within the feature. In some embodiments, method 100 forms a first gap fill with substantially no voids. In this regard, a "substantial" void is one with a width of 1 nm or more. In some embodiments, the first gap fill is formed within at least one feature 210 without any substantial seams. In this regard, a "substantial" seam is one with a width of 1 nm or less.

[0042] Furthermore, the disclosed method advantageously forms the first gap fill 220 in a "bottom-up" manner. The "bottom-up manner" means that method 100 accumulates little or no first gap fill 220 on the top surface 215 and / or sidewalls 214, and the formation of the first gap fill 220 is mainly performed on the bottom 216. Accordingly, the first gap fill 220 grows upward from the bottom 216 of at least one feature 210.

[0043] In some embodiments, the first gap fill 220 is deposited in a non-conformal manner. In some embodiments, the first gap fill 220 is etched in a non-conformal manner. The "non-conformal manner" means that the material is deposited or etched (formed or removed) in varying thicknesses across the substrate surface 205. For example, in some embodiments, the thickness of the first gap fill removed from the bottom 216 may be thinner than the thickness of the first gap fill 220 removed from the top surface 215.

[0044] In some embodiments, the processing conditions of method 100 may be controlled. In some embodiments, the processing environment is maintained at a predetermined pressure during method 100. In some embodiments, the pressure is maintained in the range of about 5 Torr to about 35 Torr, or in the range of about 25 Torr to about 50 Torr.

[0045] FIG. 3 is a schematic top view of an exemplary multi-chamber processing system 300 according to an embodiment of the present disclosure. The processing system 300 generally includes a factory interface 302, load lock chambers 304, 306, transfer chambers 308, 310 each having a transfer robot 312, 314, hold chambers 316, 318, and processing chambers 320, 322, 324, 326, 328, 330. As detailed herein, wafers within the processing system 300 can be processed in various chambers and transferred between them without exposing the wafers to the ambient environment outside the processing system 300 (e.g., an atmospheric environment such as an environment that may exist in a manufacturing factory). For example, wafers can be processed in various chambers in a low pressure (e.g., about 300 Torr or less) or vacuum environment and transferred between them without breaking the low pressure or vacuum environment during the various processes performed on the wafers within the processing system 300. Thus, the processing system 300 may provide an integrated solution for some processing of wafers.

[0046] Examples of processing systems that may be suitably modified in accordance with the teachings provided herein include integrated processing systems of Endura®, Producer®, or Centura®, or other suitable processing systems commercially available from Applied Materials, Inc., located in Santa Clara, California. It is contemplated that other processing systems, including those by other manufacturers, may be adapted to benefit from the aspects described herein.

[0047] In the example illustrated in FIG. 3, the factory interface 302 includes a docking station 340 and a factory interface robot 342 that facilitate the transfer of wafers. The docking station 340 is configured to receive one or more front-opening unified pods (FOUPs) 344. In some examples, each factory interface robot 342 generally includes a blade 348 disposed at one end of each factory interface robot 342, which is configured to transfer wafers from the factory interface 302 to the load lock chambers 304, 306.

[0048] The load lock chambers 304, 306 have respective ports 350, 352 coupled to the factory interface 302 and respective ports 354, 356 coupled to the transfer chamber 308. The transfer chamber 308 further has respective ports 358, 360 coupled to the hold chambers 316, 318 and respective ports 362, 364 coupled to the process chambers 320, 322. Similarly, the transfer chamber 310 has respective ports 366, 368 coupled to the hold chambers 316, 318 and respective ports 370, 372, 374, 376 coupled to the process chambers 324, 326, 328, 330. The ports 354, 356, 358, 360, 362, 364, 366, 368, 370, 372, 374, 376 can be slit valve openings having slit valves for passing wafers therethrough by transfer robots 312, 314 and for providing seals between respective chambers to prevent gas from passing between the respective chambers. Generally, any port is open for transferring a wafer therethrough. Otherwise, the port is closed.

[0049] The load lock chambers 304, 306, transfer chambers 308, 310, holding chambers 316, 318, and processing chambers 320, 322, 324, 326, 328, 330 may be fluidly coupled to a gas and pressure control system (not specifically shown). The gas and pressure control system can include one or more gas pumps (e.g., turbo pumps, cryo pumps, roughing pumps), a gas source, various valves, and conduits fluidly coupled to the various chambers. During operation, the factory interface robot 342 transfers a wafer from the FOUP 344 through port 350 or 352 to the load lock chamber 304 or 306. The gas and pressure control system then pumps down the load lock chamber 304 or 306. The gas and pressure control system further maintains an internal low pressure or vacuum environment (which may include an inert gas) in the transfer chambers 308, 310 and the holding chambers 316, 318. Thus, pumping down the load lock chamber 304 or 306 facilitates passing a wafer, for example, between the atmospheric environment of the factory interface 302 and the low pressure or vacuum environment of the transfer chamber 308.

[0050] With the wafer in the pumped-down load lock chamber 304 or 306, transfer robot 312 transfers the wafer from the load lock chamber 304 or 306 into the transfer chamber 308 through ports 354 or 356. Transfer robot 312 can then transfer the wafer, for processing, through respective ports 362, 364 into one or both of the processing chambers 320, 322 and / or, and / or between, and / or hold for further transfer through respective ports 358, 360 into one or both of the holding chambers 316, 318. Similarly, transfer robot 314 can access the wafer in holding chamber 316 or 318 through port 366 or 368 and transfer the wafer, for processing, through respective ports 370, 372, 374, 376 into one or both of the processing chambers 324, 326, 328, 330 and / or, and / or between, and / or hold for further transfer through respective ports 366, 368 into one or both of the holding chambers 316, 318 and / or, and / or between. Transfer and holding of the wafer within and between the various chambers can be within a low pressure or vacuum environment provided by the gas and pressure control system.

[0051] The processing chambers 320, 322, 324, 326, 328, 330 can be any suitable chambers for processing wafers. In some embodiments, the processing chamber 320 can be capable of performing an annealing process, the processing chamber 322 can be capable of performing a cleaning process, and the processing chambers 324, 326, 328, 330 can be capable of performing an epitaxial growth process. In some examples, the processing chamber 322 can be capable of performing a cleaning process, the processing chamber 320 can be capable of performing an etching process, and the processing chambers 324, 326, 328, 330 can be capable of performing their respective epitaxial growth processes. The processing chamber 322 may be a SiCoNi (trademark) Preclean chamber available from Applied Materials of Santa Clara, California. The processing chamber 320 may be a Selectra (trademark) Etch chamber available from Applied Materials of Santa Clara, California.

[0052] The system controller 390 is coupled to the processing system 300 to control the processing system 300 or its components. For example, the system controller 390 may control the operation of the processing system 300 using direct control of the chambers 304, 306, 308, 316, 318, 310, 320, 322, 324, 326, 328, 330 of the processing system 300 or by controlling the controllers associated with the chambers 304, 306, 308, 316, 318, 310, 320, 322, 324, 326, 328, 330. During operation, the system controller 390 enables data collection and feedback from each chamber to adjust the performance of the processing system 300.

[0053] The system controller 390 generally includes a central processing unit (CPU) 392, a memory 394, and a support circuit 396. The CPU 392 can be in any form of a general-purpose processor that can be used in industrial equipment. The memory 394, that is, the non-transitory computer-readable medium, is accessible by the CPU 392 and can be one or more of memories such as random access memory (RAM), read-only memory (ROM), floppy disks, hard disks, or any other form of digital storage, local or remote. The support circuit 396 is coupled to the CPU 392 and may include a cache, a clock circuit, an input / output subsystem, a power supply, etc. The various methods disclosed herein can generally be realized under the control of the CPU 392 by the CPU 392 executing computer instruction codes stored in the memory 394 (or in the memory of a specific process chamber), for example, as software routines. When the computer instruction codes are executed by the CPU 392, the CPU 392 controls the chamber to perform the process according to various methods.

[0054] Other processing systems can have other configurations. For example, a greater or fewer number of processing chambers may be coupled to the transfer device. In the illustrated example, the transfer device includes transfer chambers 308, 310 and holding chambers 316, 318. In other examples, a greater or fewer number of transfer chambers (e.g., one transfer chamber), and / or a greater or fewer number of holding chambers (e.g., no holding chambers) may be implemented in the processing system as the transfer device.

[0055] The process may generally be stored in the memory of system controller 390 as a software routine that, when executed by a processor, causes the process chamber to perform the processes of the present disclosure. The software routine may also be stored and / or executed by a second processor (not shown) that is located apart from the hardware controlled by the processor. Some or all of the methods of the present disclosure may also be implemented in hardware. Thus, the process may be implemented in software and executed using a computer system, or in hardware as, for example, an application specific integrated circuit or other type of hardware implementation, or as a combination of software and hardware. The software routine, when executed by a processor, converts a general purpose computer into a dedicated computer (controller) that controls the chamber operation so that the process is performed.

[0056] Embodiments of the present disclosure are directed to non-transitory computer-readable media. In one or more embodiments, the non-transitory computer-readable medium includes instructions that, when executed by a controller of a processing chamber, cause the processing chamber to perform the operations of any of the methods described herein (e.g., deposition method 100). In one or more embodiments, the controller causes the processing chamber to perform the operations of deposition method 100. In one or more embodiments, the controller causes the processing chamber to perform an operation (operation 110) of depositing a second metal material on a substrate surface having at least one feature therein. The at least one feature comprises at least one surface defining a via having a bottom surface and at least one sidewall. In one or more embodiments, the controller causes the processing chamber to perform an operation (operation 120) of exposing to a first metal halide and a reducing agent to form a first metal gap fill within the at least one feature.

[0057] Spatial relative terms such as "lower", "below", "bottom", "upper", "top", etc. may be used in this specification to simplify the description for explaining the relationship between one element or feature and another element or feature as shown in the drawings. It will be understood that spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the drawings. For example, if the device in the drawings is inverted, an element described as being "below" or "beneath" another element or feature will then be oriented "above" the other element or feature. Thus, the exemplary term "below" can encompass both upward and downward orientations. The device may be oriented in another way (rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this specification are to be interpreted accordingly.

[0058] The use of the terms "a", "an", and "the" and similar referents in the context of describing the materials and methods contemplated in this specification (in particular, in the context of the following claims) are to be construed to cover both the singular and the plural forms unless otherwise indicated herein or unless there is a clear contradiction by context. The recitation of a range of values herein is merely intended to serve as a convenient method of referring individually to each separate value falling within the range, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or unless there is a clear contradiction by context. The use of any examples, or exemplary language (e.g., "such as") provided herein is merely intended to better clarify the materials and methods and is not intended to impose a limitation on the scope unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.

[0059] Throughout this specification, references to "one embodiment", "a particular embodiment", "one or more embodiments", or "an embodiment" etc. mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases "in one or more embodiments", "in a particular embodiment", "in one embodiment", or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the present disclosure. In one or more embodiments, the particular features, structures, materials, or characteristics are combined in any suitable form.

[0060] Although the disclosure of this specification has been described with reference to particular embodiments, these embodiments should be understood to be merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatuses of the present disclosure without departing from the spirit and scope of the present disclosure. Accordingly, the present disclosure is intended to cover modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. Exposing a substrate surface on which at least one feature is formed to a first molybdenum precursor and a reducing agent to form a first gap fill within at least one feature, wherein the at least one feature has an opening and two sidewalls and extends by a depth from a top surface to a bottom surface, exposing the substrate surface; Exposing the substrate surface to a second molybdenum halide precursor to remove a portion of the first gap fill; Repeating the formation of the first gap fill; A method of depositing a molybdenum gap fill, comprising:

2. The method according to claim 1, wherein an aspect ratio of the at least one feature is about 50:1 or more.

3. The method according to claim 2, wherein the aspect ratio of the at least one feature is about 100:1 or more.

4. The method according to claim 1, wherein the at least one feature forms a memory cell of a DRAM.

5. The method according to claim 1, wherein the first gap fill is formed by a CVD process.

6. The method according to claim 5, wherein the CVD process is performed without plasma.

7. The method according to claim 1, wherein the first molybdenum precursor contains an oxyhalide.

8. wherein the first molybdenum precursor is basically MoO ２ Cl ２ and the method according to claim 7

9. The method according to claim 1, wherein the substrate is maintained at a temperature in a range of about 500 °C to about 600 °C during the formation of the first gap fill.

10. The method according to claim 1, wherein the first gap fill has a thickness in a range of about 10 Å to about 50 Å at the bottom of the at least one feature before being exposed to the second molybdenum halide.

11. The method according to claim 1, wherein the substrate surface is purged after the formation of the first gap fill and before the exposure to the second molybdenum halide.

12. wherein the second molybdenum halide is essentially MoCl ５ The method according to claim 1, comprising.

13. The method according to claim 1, wherein removing the portion of the first gap fill removes a thickness in a range of about 10 Å to about 50 Å.

14. The method according to claim 1, wherein the portion of the first gap fill is removed from near the upper part of the at least one feature, and the method forms the first gap fill in a bottom-up manner.

15. The method of claim 1, wherein the first gap fill includes voids, and removing a portion of the first gap fill removes the voids. **Claim 16** The method of claim 15, wherein the method forms a substantially void-free molybdenum gap fill. **Claim 17** The method of claim 1, wherein the substrate surface is purged after exposure to the second molybdenum halide and before repeating the formation of the first gap fill. **Claim 18** The method of claim 1, further comprising repeating the formation and removal of the first gap fill to fill the at least one feature. **Claim 19** The method of claim 18, wherein the forming and removing form deposition-etch cycles, and a number of cycles in the range of about 200 to about 400 are performed. **Claim 20** To form a first gap fill within at least one feature, expose the substrate surface within which the at least one feature is formed to MoO ２ Cl ２ and H ２ wherein the exposing comprises exposing the substrate surface such that the at least one feature has an opening and two sidewalls and extends a depth from a top surface to a bottom surface, and the feature has an aspect ratio of about 100:1 or greater. Exposing the surface of the substrate to MoCl ５ to remove a part of the first gap filling, Repeating the formation and removal of the first gap fill to completely fill the at least one feature A method of depositing a molybdenum gap fill, comprising:

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