Selective tungsten deposition within trench structures

Abstract

To provide methods for selectively depositing tungsten within trench structures.SOLUTION: An embodiment of the disclosure presents a method for reducing or eliminating the lateral growth of a selective tungsten layer. Another embodiment presents an integrated clean and deposition method for improving the selectivity of selectively deposited tungsten on trench structures. Additional embodiment provides a method for forming a more uniform and selective bottom-up gap fill for trench structures with improved film properties.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure generally relate to methods for selectively depositing tungsten in trench structures, and more particularly, to methods for integrating cleaning and deposition processes for improved film properties. [Background technology]

[0002] Integrated cleaning and selective tungsten deposition processes have been used in many semiconductor applications. These methods enable the creation of liner-free, seam-free via fills for contacts. However, trenches typically have a larger bottom area than vias. The large deposition area can make it difficult to grow a uniform film in a trench. Thus, the same methods often do not provide adequate deposition selectivity and film properties (e.g., roughness, thickness, uniformity) when applied to trench structures.

[0003] Therefore, there is a need for an improved method for selectively depositing tungsten in trench structures with excellent film properties. Summary of the Invention

[0004] One or more embodiments of the present disclosure are directed to a deposition method that includes recessing a line of metallic material to form a trench having a bottom surface and two sidewalls. The trench has a depth to a bottom surface that includes the metallic material and a width between two sidewalls that include a dielectric. A tungsten film is selectively deposited over the recessed metallic material and laterally bounded by the two sidewalls.

[0005] A further embodiment of the present disclosure is directed to a selective deposition method that includes exposing a trench having a bottom surface comprising a metallic material and two sidewalls comprising a dielectric to multiple chemical exposures to clean a surface of the metallic material and a surface of the dielectric, and selectively depositing a tungsten film on the cleaned surface of the metallic material.

[0006] Another embodiment of the present disclosure is directed to a deposition method that includes recessing a line of metallic material to form a trench having a bottom surface and two sidewalls. The trench has a depth to a bottom surface that includes the metallic material and a width between two sidewalls that include a dielectric. The trench is exposed to multiple chemical exposures to clean a surface of the metallic material and a surface of the dielectric. A tungsten film is selectively deposited on the cleaned surface of the metallic material.

[0007] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above will be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the present disclosure can admit of other equally effective embodiments, and therefore, that the accompanying drawings only illustrate typical embodiments of the present disclosure, and therefore should not be considered as limiting the scope of the present disclosure. [Brief description of the drawings]

[0008] [Figure 1] 1A-1D are cross-sectional views of a substrate during processing in accordance with one or more embodiments of the present disclosure. [Diagram 2] 1A-1D are cross-sectional views of a substrate during processing in accordance with one or more embodiments of the present disclosure. [Diagram 3] 1A-1D are cross-sectional views of a substrate during processing in accordance with one or more embodiments of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of a processing system in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Before describing certain example embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of structure or process steps set forth in the following description, as the present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0010] The term "substrate" as used herein and in the appended claims means a surface or a portion of a surface on which a process acts. Those skilled in the art will also understand that a reference to a substrate can refer only to a portion of the substrate, unless the context clearly indicates otherwise. In addition, a reference to deposition on a substrate can refer to both a bare substrate and a substrate on which one or more films or features have been deposited or formed.

[0011] As used herein, "substrate" refers to any substrate surface or material surface 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 materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, semiconductor wafers. Substrates can undergo pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure, and / or bake the substrate surface. In addition to film processing performed directly on the surface of the substrate itself, the present disclosure also provides that any of the disclosed film processing steps can also be performed on an underlying layer formed on the substrate, as disclosed in more detail below, and the term "substrate surface" includes such an underlying layer, as the context indicates. 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.

[0012] One or more embodiments of the present disclosure provide a method for advantageously eliminating lateral growth of selectively deposited tungsten. In some embodiments of the present disclosure, a line of metal material is recessed to form a trench, and tungsten is selectively deposited on the recessed metal line, bounded by the trench sidewalls.

[0013] 1, an exemplary method 100 for processing a substrate 400 is shown. The substrate 400 includes at least one line of a metal material 410 bounded by a dielectric material 420.

[0014] In some embodiments, metallic material 410 comprises one or more of copper, cobalt, tungsten, molybdenum, or ruthenium. In some embodiments, metallic material 410 consists essentially of cobalt. In some embodiments, metallic material 410 consists essentially of tungsten. In some embodiments, metallic material 410 consists essentially of ruthenium. In some embodiments, metallic material 410 consists essentially of molybdenum. In this regard, a metallic material that "consists essentially of" the recited elements is one that contains, on an atomic basis, 95% or more, 98% or more, 99% or more, or 99.5% or more of the recited elements.

[0015] In some embodiments, the dielectric 420 comprises silicon oxide, silicon nitride, or a combination thereof. In some embodiments, the dielectric consists essentially of silicon oxide. It should be noted that the above descriptors (e.g., silicon oxide) should not be construed as disclosing any particular stoichiometric ratio. Thus, one of ordinary skill in the art would understand "silicon oxide" or the like as a material consisting essentially of silicon and oxygen without disclosing any particular stoichiometric ratio.

[0016] At 110, the metal material 410 is recessed to form a trench 450 having a bottom surface 452 including recessed metal material 415 and two sidewalls 456, 458 including dielectric material 420. The trench 450 has a depth D to the bottom surface 452 and a width W between the two sidewalls 456, 458. In some embodiments, the depth D is in the range of 2 nm to 200 nm, 3 nm to 200 nm, 5 nm to 100 nm, 2 nm to 100 nm, or 50 nm to 100 nm. In some embodiments, the width W is in the range of 10 nm to 100 nm, 10 nm to 20 nm, 10 nm to 50 nm, or 50 nm to 100 nm. In some embodiments, the trench 450 has an aspect ratio (D / W) in the range of 1 to 20, 5 to 20, 10 to 20, or 15 to 20.

[0017] In some embodiments, the metallic material is recessed by a wet etching process. In some embodiments, the metallic material is recessed by a dry etching process.

[0018] Although not shown, trench 450 has a length L that is greater than its width W. In some embodiments, the ratio of length L to width W is 2 or greater, 5 or greater, 10 or greater, 20 or greater, 50 or greater, 100 or greater, or 500 or greater. In some embodiments, trench 450 has a length L that is bounded by vertical walls. In some embodiments, trench 450 has a length L that is bounded only by an edge of substrate 400.

[0019] Next, at 120, a tungsten film 430 is selectively deposited on the recessed metal material 415. In some embodiments, the tungsten film 430 is laterally bounded by two sidewalls 456, 458 of the trench 450. In this context, "latently bounded" means that the deposited material does not extend beyond the intersection between the top surface and the two sidewalls. In some embodiments, the tungsten film 430 extends above the trench 450. As shown in FIG. 1, in some embodiments, the tungsten film is completely inside the trench 450. In this context, material that is "completely inside" the trench does not extend above the trench and is laterally bounded by two sidewalls 456, 458 of the trench 450.

[0020] In some embodiments, selectively depositing the tungsten film includes exposing the trench 450 to a tungsten precursor and a reducing agent. In some embodiments, the tungsten precursor includes WF. In some embodiments, the reducing agent includes one or more of H, silane (SiH), or diborane (BH).

[0021] In some embodiments, the temperature of the substrate is maintained at a temperature less than or equal to 350° C. In some embodiments, the pressure of the process chamber is maintained at a pressure less than or equal to 30 Torr.

[0022] In some embodiments, each of the processes of method 100 is performed in the same processing chamber. In some embodiments, each of the processes of method 100 is performed in separate processing chambers. In some embodiments, the separate processing chambers are coupled as part of a processing system. In some embodiments, the processes of method 100 are performed without an intervening vacuum break.

[0023] 2, a method 200 is shown for processing an exemplary substrate 400. The substrate 400 comprises at least one trench 450 having a bottom surface 452 that includes a recessed metal material 415 and two sidewalls 456, 458 that include a dielectric 420.

[0024] The surface of the recessed metal material 415 and the surface of the dielectric 420 include contaminants, shown as O and X, respectively, in Figure 2. In some embodiments, the contaminants may include, but are not limited to, one or more of organic compounds, polymeric compounds, metal oxides, or metal nitrides. In some embodiments, the contaminants are generated on the surface of the recessed metal material 415 and the surface of the dielectric 420 by the process of recessing the metal material 415.

[0025] The materials of recessed metal material 415 and dielectric 420 are the same as those identified above with respect to method 100, however method 200 is not limited by the process steps of method 100. In other words, the recessed metal material 415 mentioned in describing method 200 may be formed by any suitable method.

[0026] At 210, trench 450 is exposed to multiple chemical exposures to clean the surfaces of recessed metal material 415 and dielectric 420. In some embodiments, at least one of the multiple chemical exposures includes a plasma exposure. In some embodiments, the plasma is an inductively coupled plasma (ICP). In some embodiments, the plasma is a capacitively coupled plasma (CCP). In some embodiments, the plasma is generated remotely. In some embodiments, the plasma is generated within the process chamber (direct plasma).

[0027] In some embodiments, at least one of the chemical exposures includes a thermal soak, which will be understood by those skilled in the art to include exposing the trench to a chemical agent without the use of plasma or other radicals.

[0028] In some embodiments, the multiple chemical exposures include exposure to one or more of Ar, H2, O2, or WF6. In some embodiments, the multiple chemical exposures include Ar and H2. In some embodiments, the multiple chemical exposures include Ar and O2. In some embodiments, the multiple chemical exposures include H2 and O2. In some embodiments, the multiple chemical exposures include WF6, H2, and WF6.

[0029] In some embodiments, the temperature of the substrate is controlled during the multiple chemical exposures, hi some embodiments, the temperature is maintained within the range of 20°C to 400°C, 20°C to 350°C, 20°C to 300°C, 20°C to 250°C, 20°C to 200°C, 20°C to 150°C, 20°C to 100°C, 100°C to 400°C, 200°C to 400°C, or 300°C to 400°C.

[0030] At 220, a tungsten film 430 is selectively deposited on the cleaned surface of the recessed metal material 415. In some embodiments, the tungsten film 430 is laterally bounded by two sidewalls 456, 458 of the trench 450. In this context, "latently bounded" means that the deposited material does not extend beyond the intersection between the top surface and the two sidewalls. In some embodiments, the tungsten film 430 extends above the trench 450. As shown in FIG. 2, in some embodiments, the tungsten film is completely inside the trench 450. In this context, material that is "completely inside" the trench does not extend above the trench and is laterally bounded by two sidewalls 456, 458 of the trench 450.

[0031] Methods and materials for selectively depositing tungsten film 430 are described above with respect to method 100.

[0032] Without being bound by theory, it is believed that multiple chemical exposures improve the quality of the deposited tungsten film 430. In some embodiments, tungsten films 430 deposited by the methods of the present disclosure exhibit one or more of increased selectivity, reduced surface roughness, and / or reduced grain size.

[0033] In some embodiments, the tungsten film 230 is selectively deposited with a selectivity that is at least 20 times greater, at least 50 times greater, at least 100 times greater, at least 200 times greater, at least 500 times greater, at least 1000 times greater, at least 2000 times greater, or at least 5000 times greater than a similar process performed without multiple chemical exposures.

[0034] In some embodiments, the tungsten film 230 has a roughness of 1 nm or less when the thickness of the tungsten film 230 is 10 nm. In some embodiments, the tungsten film 230 has a grain size of 10 nm or less.

[0035] In some embodiments, each of the processes of method 200 is performed in the same processing chamber. In some embodiments, each of the processes of method 200 is performed in separate processing chambers. In some embodiments, the separate processing chambers are coupled as part of a processing system. In some embodiments, the processes of method 200 are performed without an intervening vacuum break.

[0036] 3, a method 300 is shown for processing an exemplary substrate 400. The substrate 400 includes at least one line of metallic material 410 bounded by a dielectric material 420.

[0037] At 310, the metal material 410 is recessed to form a trench 450 having a bottom surface 452 comprising recessed metal material 415 and two sidewalls 456, 458 comprising dielectric 420. The method performed at 310 is similar to the method performed at 110.

[0038] In some embodiments, the process of recessing the metal material 410 creates contaminants on the surface of the recessed metal material 415 and / or the dielectric material 420. In Figure 3, the contaminants are designated O and X, respectively.

[0039] At 320, trench 450 is subjected to multiple chemical exposures to clean the surfaces of recessed metal material 415 and dielectric material 420. The method performed at 320 is similar to the method performed at 210.

[0040] At 330, a tungsten film 430 is selectively deposited on the cleaned surface of the recessed metal material 415. In some embodiments, the tungsten film 430 is laterally bounded by two sidewalls 456, 458 of the trench 450. In some embodiments, the tungsten film 430 extends above the trench 450. As shown in FIG. 2, in some embodiments, the tungsten film is completely inside the trench 450. In some embodiments, the tungsten film 430 fills the trench 450. In this regard, a film that "fills the trench" has a volume that occupies at least 95%, at least 98%, or at least 99% of the volume of the trench.

[0041] Methods and materials for selectively depositing tungsten film 430 are described above with respect to method 100. Properties of the deposited tungsten film 430 are described above with respect to method 200.

[0042] In some embodiments, each of the processes of method 300 is performed in the same processing chamber. In some embodiments, each of the processes of method 300 is performed in separate processing chambers. In some embodiments, the separate processing chambers are coupled as part of a processing system. In some embodiments, the processes of method 300 are performed without an intervening vacuum break.

[0043] With reference to FIG. 4, an additional embodiment of the present disclosure is directed to a processing system 900 for performing the methods described herein. FIG. 4 illustrates a system 900 that can be used to process substrates according to one or more embodiments of the present disclosure. The system 900 can be referred to as a cluster tool. The system 900 includes a central transfer station 910 having a robot 912 therein. Although the robot 912 is illustrated as a single blade robot, one skilled in the art will understand that other configurations of the robot 912 are within the scope of the present disclosure. The robot 912 is configured to move one or more substrates between multiple chambers coupled to the central transfer station 910.

[0044] At least one pre-clean / buffer chamber 920 is coupled to the central transfer station 910. The pre-clean / buffer chamber 920 may include one or more of a heater, a radical source, or a plasma source. The pre-clean / buffer chamber 920 may be used as a holding area for individual semiconductor substrates or as a holding area for a cassette of wafers for processing. The pre-clean / buffer chamber 920 may perform a pre-clean process or may pre-heat the substrate for processing, or may simply be a staging area for a process sequence. In some embodiments, there are two pre-clean / buffer chambers 920 coupled to the central transfer station 910.

[0045] 4, the pre-clean chamber 920 can function as a pass-through chamber between the factory interface 905 and the central transfer station 910. The factory interface 905 can include one or more robots 906 for moving substrates from a cassette to the pre-clean / buffer chamber 920. A robot 912 can then move the substrates from the pre-clean / buffer chamber 920 to other chambers in the system 900.

[0046] A first processing chamber 930 can be coupled to the central transfer station 910. The first processing chamber 930 can be configured as an etch chamber and can be in fluid communication with one or more reactive gas sources to provide one or more flows of reactive gas to the first processing chamber 930. Substrates can be moved to and from the processing chamber 930 by a robot 912 through an isolation valve 914.

[0047] Processing chambers 940 can also be coupled to the central transfer station 910. In some embodiments, the processing chambers 940 include cleaning chambers and are fluidly coupled to one or more reactive gas sources to provide a flow of reactive gas to the processing chambers 940 to perform a cleaning process. Substrates can be moved to and from the processing chambers 940 by a robot 912 through an isolation valve 914.

[0048] In some embodiments, a processing chamber 960 is coupled to the central transfer station 910. In some embodiments, the processing chamber 960 comprises a selective deposition chamber and is fluidly coupled to one or more reactive gas sources to provide a reactive gas flow to the processing chamber 960 to perform a deposition process. Substrates can be moved to and from the processing chamber 960 by a robot 912 through an isolation valve 914.

[0049] In some embodiments, each of the processing chambers 930, 940, and 960 is configured to perform a separate portion of a processing method. For example, processing chamber 930 can be configured to perform an etching process, processing chamber 940 can be configured to perform a cleaning process, and processing chamber 960 can be configured to perform a selective deposition process. Those skilled in the art will appreciate that the number and arrangement of individual processing chambers on a tool can vary, and the embodiment shown in FIG. 4 represents just one possible configuration.

[0050] In some embodiments, the processing system 900 includes one or more metrology stations. For example, the metrology station can be located within the pre-clean / buffer chamber 920, within the central transfer station 910, or within any of the individual processing chambers. The metrology station can be any location within the system 900 that allows for measuring the recess distance without exposing the substrate to an oxidizing environment.

[0051] At least one controller 950 is coupled to one or more of the central transfer station 910, the pre-clean / buffer chamber 920, the processing chambers 930, 940 or 960. In some embodiments, there are multiple controllers 950 connected to individual chambers or stations, with a primary control processor coupled to each of the separate processors for controlling the system 900. The controller 950 can be one of any form of general purpose computer processor, microcontroller, microprocessor, etc. that can be used in an industrial environment for controlling the various chambers and sub-processors.

[0052] At least one controller 950 may have a processor 952, a memory 954 coupled to the processor 952, input / output devices 956 coupled to the processor 952, and support circuitry 958 for communication between various electronic components. The memory 954 may include one or more of temporary memory (e.g., random access memory) and non-transitory memory (e.g., storage).

[0053] The processor's memory 954, or computer readable medium, may be one or more of a local or remote readily available memory, such as a random access memory (RAM), a read only memory (ROM), a floppy disk, a hard disk, or any other form of digital storage. The memory 954 may hold a set of instructions operable by the processor 952 to control parameters and components of the system 900. The support circuits 958 are coupled to the processor 952 for supporting the processor in a conventional manner. The circuits may include, for example, cache, power supplies, clock circuits, input / output circuits, subsystems, and the like.

[0054] The process can generally be stored in memory as a software routine that, when executed by a processor, causes the process chamber to perform the process of the present disclosure. The software routine can also be stored and / or executed by a second processor (not shown) that is remote from the hardware controlled by the processor. Some or all of the methods of the present disclosure can also be implemented in hardware. Thus, the process can be implemented as software and executed in hardware using a computer system, such as, for example, an application specific integrated circuit or other type of hardware implementation, or a combination of software and hardware. The software routine, when executed by a processor, turns a general-purpose computer into a special-purpose computer (controller) that controls the chamber operation so that the process is performed.

[0055] In some embodiments, the controller 950 has one or more configurations for executing individual processes or sub-processes to perform the method. The controller 950 can be connected to and configured to operate the intermediate components to perform the functions of the method. For example, the controller 950 can be connected to and configured to control one or more of gas valves, actuators, motors, slit valves, vacuum controls, etc.

[0056] The controller 950 in some embodiments has one or more configurations selected from: a configuration for robotically moving substrates between multiple processing chambers and a metrology station; a configuration for loading and / or unloading substrates from the system; a configuration for recessing a metal material; a configuration for cleaning the surface of the recessed metal material and the surface of a dielectric; and a configuration for selectively depositing tungsten.

[0057] References throughout this specification to "one embodiment," "a particular embodiment," "one or more embodiments," or "an embodiment" mean that a particular feature, structure, material, or characteristic described with respect to that embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of phrases such as "in one or more embodiments," "in a particular embodiment," "in one embodiment," or "in one embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment of the present disclosure. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0058] Although the present disclosure has been described herein with reference to specific embodiments, it will be understood by those skilled in the art that the described embodiments are 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 disclosed method and apparatus without departing from the spirit and scope of the present disclosure. That is, the present disclosure may include modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. recessing a line of metal material to form a trench having a bottom surface and two sidewalls, said trench having a depth to said bottom surface that includes said metal material and a width between said two sidewalls that includes a dielectric; selectively depositing a tungsten film on the recessed metal material, laterally bounded by said two sidewalls; The deposition method comprising:

2. The method of claim 1 , wherein the metallic material comprises one or more of copper, cobalt, tungsten, or ruthenium.

3. The method of claim 1 , wherein the dielectric comprises silicon oxide, silicon nitride, or a combination thereof.

4. The method of claim 1 , wherein the lines of metallic material are recessed by a wet etching process.

5. The method of claim 1 , wherein the lines of metallic material are recessed by a dry etching process.

6. The method of claim 1 , wherein the trench has a depth in the range of 3 nm to 200 nm.

7. The method of claim 6, wherein the trench has an aspect ratio in the range of 1:1 to 20:

1.

8. The step of selectively depositing a tungsten film includes forming the trench with WF 6 and H 2 The method of claim 1 , comprising exposing to a.

9. exposing a trench having a bottom surface comprising a metallic material and two sidewalls comprising a dielectric to multiple chemical exposures to clean a surface of the metallic material and a surface of the dielectric; selectively depositing a tungsten film onto the cleaned surface of the metallic material; A selective deposition method comprising:

10. The method of claim 9 , wherein the multiple chemical exposures include a plasma exposure.

11. The plurality of chemical exposures are 2 Plasma exposure and O 2 The method of claim 10 comprising plasma exposure.

12. The method of claim 9 , wherein the multiple chemical exposures include heat soaks.

13. The multiple chemical exposures include Ar, H 2 , O 2 or W.F. 6 10. The method of claim 9, comprising exposing the

14. 10. The method of claim 9, wherein the multiple chemical exposures are carried out at a temperature in the range of 20°C to 400°C.

15. 10. The method of claim 9, wherein the tungsten film is deposited with a selectivity that is at least 1000 times greater than a similar process performed without the multiple chemical exposures.

16. 10. The method of claim 9, wherein the tungsten film has a roughness of 1 nm or less.

17. 10. The method of claim 9, wherein the tungsten film has a grain size of 10 nm or less.

18. recessing a line of metal material to form a trench having a bottom surface and two sidewalls, the trench having a depth to the bottom surface that includes the metal material and a width between the two sidewalls that includes a dielectric; exposing the trench to multiple chemical exposures to clean the metallic material surface and the dielectric surface; selectively depositing a tungsten film onto the cleaned surface of the metallic material; The deposition method comprising:

19. 20. The method of claim 18, wherein the tungsten film is deposited completely inside the trench.

20. 20. The method of claim 18, wherein the tungsten film fills the trench.

Images