Conditioning treatment for ALD productivity

Deposition methods and apparatus for conditioning a process kit to increase process kit lifetime are described. A nitride film formed on a process kit is exposed to conditioning process comprising nitrogen and hydrogen radicals to condition the nitride film to decrease particulate contamination from the process kit.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to apparatus and methods for conditioning process chamber components. In particular, embodiments of the disclosure related to methods and apparatus for nitride deposition with improved productivity.

BACKGROUND

Atomic Layer Deposition (ALD) process chambers used for depositing some types of nitride films need frequent cleanings and maintenance. There is a low mean wafer between cleaning (MWBC) due to the properties of the deposition material on the process kit (e.g., consumable parts used in a deposition chamber). The process kit includes, but is not limited to, elements of the deposition chamber that are removable parts that touch reactive chemicals during processing. For example, chamber showerheads, pumping liners, pump shields, etc.

During processing, ALD tantalum nitride (TaN) is deposited on the wafer as well as the process kit. The wafer temperature and process kit temperatures are different, with the wafer temperature being greater than the process kit. Due at least in part to the temperature differences, the TaN deposited on the process kit is different from the film deposited on the wafer. The TaN on the process kit is low density and has high levels of impurities. The TaN formed is powdery and causes particle issues. There are no known in-situ cleaning processes capable of cleaning ALD TaN from the process kit, necessitating long equipment downtimes for cleanings and maintenance.

Additionally, plasma based processes are prone to increased particulate contamination due to plasma-induced stress accumulation on the chamber body. The particle lifetime of a process kit in a plasma process is about 20% of the particle lifetime of a process kit in a thermal process chamber.

Accordingly, there is a need for methods and apparatus to extend the mean wafer between cleaning (MWBC) for nitride deposition processes.

SUMMARY

One or more embodiments of the disclosure are directed to deposition methods comprising exposing a process kit of a process chamber having a nitride film thereon to a conditioning process comprising nitrogen and hydrogen radicals to form a conditioned nitride film. A nitride layer is deposited on a plurality of wafers within the process chamber.

Additional embodiments of the disclosure are directed to deposition methods comprising processing a plurality of wafers within a process chamber to deposit tantalum nitride (TaN) on the wafers and a nitride film on a process kit within the process chamber. The nitride film has a density less than 9 g/cm3. The process kit is conditioned after processing the plurality of wafers using a conditioning process. The conditioning process comprises exposing the process kit to nitrogen and hydrogen radicals to increase the density of the nitride film to greater than 9 g/cm3and generate a nitride film with compressive stress.

Further embodiments of the disclosure are directed to non-transitory computer readable medium including instructions, that, when executed by a controller of a processing chamber, causes the processing chamber to perform operations of: exposing a substrate to a deposition process condition to deposit a nitride film; and exposing a process kit of the process chamber to a conditioning process.

DETAILED DESCRIPTION

Embodiments of the disclosure are directed to methods of using a conditioning treatment to improve film properties of a film formed on the process kit. Some embodiments of the disclosure provide a conditioning treatment on one or more of the chamber showerhead, pumping liner, chamber isolator or edge ring. Some embodiments of the disclosure advantageously provide methods of improving adhesion of a film on the process kit during deposition. One or more embodiments advantageously provide methods of reducing particle contamination from a film formed on the process kit. Some embodiments advantageously provide methods of extending the mean-wafer-between-clean (MWBC) for a nitride deposition process.

Some embodiments of the disclosure condition the chamber body using a mixed ammonia, hydrogen and argon plasma treatment to densify the film deposited on the process kit by changing the film composition. In some embodiments, the film deposited on the process kit is treated to increase the density of the film. In some embodiments, the treatment process causes the film material to have a more neutral film-stress. Some embodiments improve the film properties of the material deposited on the process kit so that adhesion to the process kit is improved over time. In some embodiments, adhesion is improved by lowering particle formation in the chamber over time due to delamination, cracking from stressed films and/or showerhead peeling. In some embodiments, the process particle performance is improved to increase the particle lifetime of the process kit. In some embodiments, particle performance is defined by particle adders >32 nm. In some embodiments, particle performance is in the range of less than 5 particle adders (particles that the process adds onto the wafer) greater than 32 nm in size. In some embodiments, the particles are measured using a surface inspection system using, for example, light-scattering. In some embodiments, the particles are measured using a scanning electron microscope (SEM) to determine the particle size based on image analysis. In some embodiments, a particle map and bin sizes are determined by optically measuring the surface topography aberrations that indicate defects on a wafer surface. At smaller particle sizes, the measured particle could be a wafer defect and not a particle added by the process and SEM can be used to view the top of the wafers before or after receiving the defect map from another technique. In some embodiments, SEM images are taken at locations on the defect map at one or more magnifications and be reviewed for the existence of particles, the correct bin size, particle morphology, and/or particle composition.

In some embodiments, an ammonia (NH3)/hydrogen (H2)/argon (Ar) plasma treatment at various powers, process gas flow ratios and/or treatment times improves film density and/or particle performance. Nitridification of an ALD nitride film (e.g., TaN) deposited on the process kit turns the tensile, low density, loose film into a higher density and more stress-neutral film. Unless otherwise specified, the skilled artisan will recognize that the use of terms like “tantalum nitride” or formulae like “TaN” identify the elemental components of the stated material and do not imply any particular stoichiometric relationship of components. For example, TaN, unless otherwise specified, refers to a film having tantalum and nitrogen atoms. In an example using specific stoichiometric values, the low density, tensile film comprising TaN is modified into a higher density, more stress-neutral Ta3N5.

The films deposited on the process kit during deposition typically have high impurities and forms a powdery material that can cause particle issues, decreasing the MWBC for the chamber in production. Some embodiments of the disclosure modify the film properties deposited on the process kit periodically during kit life to help keep the film adhered to the process kit, make the film denser and/or more stress-neutral so that defects are less likely to occur causing particle issues.

FIG.1shows a process chamber100, andFIG.2shows a process method200in according with some embodiments of the disclosure. The process chamber100shown inFIG.1includes a chamber body110, a showerhead120(or other gas distribution plate), a confinement ring125(which may be omitted), a pedestal130(or other substrate support), and a wafer140. The process kit150inFIG.1comprises the pedestal130and confinement ring125. The process kit150, having a nitride film160thereon, is exposed to a conditioning process210to form a conditioned nitride film165. The conditioning process of some embodiments comprises nitrogen radicals and hydrogen radicals. The method200further comprises deposition process220in which a nitride layer170is deposited on a plurality of wafers140within the process chamber100. The plurality of wafers140of some embodiments are processed individually. In some embodiments, deposition occurs on more than one wafer at a time.

During deposition process220, in which the nitride layer170is formed on the wafer140surface, some material deposits on the process kit150(e.g., showerhead120and/or confinement ring125) as nitride film160. The nitride film160that forms on the process kit150has different properties than the nitride layer170formed on the wafer140. Without being bound by any particular theory of operation, the differences in properties between the nitride film160and nitride layer170are due to, inter alia, temperature differentials between the wafer140and the process kit150.

FIG.3Aillustrates an expanded view of region155before the conditioning process210, andFIG.3Billustrates the view ofFIG.3Aafter the conditioning process210. InFIG.3Athe nitride film160formed on the process kit150has a relatively low density and is under tensile stress. In some embodiments, the conditioning process210increases the density of the nitride film160to form the conditioned nitride film165, as shown inFIG.3B. The conditioned nitride film165may also be referred to as a densified nitride film.

In some embodiments, the nitride film160is formed on the process kit150during a nitride deposition process to form a nitride layer on one or more wafer. In some embodiments, the nitride layer is deposited by one or more of chemical vapor deposition (CVD) or atomic layer deposition. In some embodiments, the nitride layer and nitride film are deposited by atomic layer deposition. In some embodiments, the nitride layer is deposited on a plurality of wafers at the same time or sequentially.

In some embodiments, the nitride film160deposited on the process kit150comprises one or more of tantalum nitride (TaN), titanium nitride (TiN), manganese nitride (MnN), tungsten nitride (WN), ruthenium tantalum nitride (RuTaN) or niobium nitride (NbN). In some embodiments, the nitride film160deposited on the process kit150comprises or consists essentially of tantalum nitride (TaN). As used in this manner, the term “consists essentially of” means that the composition of the film is greater than or equal to 90%, 92.5%, 95%, 98%, 99% or 99% of the sum of the stated elements, on an atomic basis. In some embodiments, the nitride film160deposited on the process kit150comprises or consists essentially of titanium nitride. In some embodiments, the nitride film160deposited on the process kit150comprises or consists essentially of niobium nitride.

In some embodiments, the nitride film160comprises tantalum nitride with a relatively low density under tensile stress. As used in this manner, the term “relatively low density” means that the density of the tantalum nitride film, prior to the conditioning process, is less than or equal to 8 g/cm3, 7.5 g/cm3, 7 g/cm3, 6.5 g/cm3, 6 g/cm3, 5.5 g/cm3or 5 g/cm3.

In some embodiments, the tantalum nitride film formed on the process kit has a density, prior to the conditioning process, in the range of 5 g/cm3to 6.5 g/cm3. In some embodiments, the nitride film160formed on the process kit prior to the conditioning process, comprises tantalum nitride with tensile stress. In some embodiments, ellipsometry is used to measure the differential stress in the deposited film with a known thickness (measured by XRF). ALD TaN films prior to treatment are very tensile, ranging from 100 MPa to 1500 MPa in tensile stress. In some embodiments, after treatment the ALD Ta3N5film is more stress neutral/compressive. In some embodiments, the stress of the treated film is in the range of 0 to −500 MPa. In some embodiments, ellipsometry is used to measure the radius of curvature of the wafer before and after film deposition. The curvature delta is used to calculate the film stress with the known film thickness.

The conditioning process210changes the nitride film160into the conditioned nitride film165. The conditioned nitride film165of some embodiments has a density greater than or equal to 9 g/cm3, 9.5 g/cm3or 10 g/cm3. In some embodiments, the conditioned nitride film165comprises tantalum nitride with a density in the range of 9 g/cm3to 10.5 g/cm3, or 9.5 g/cm3to 10 g/cm3.

In some embodiments, the conditioned nitride film has a compressive stress. In some embodiments, the compressive stress is in the range of about 0 to about −500 MPa, as measured by ellipsometry.

The conditioning process of some embodiments comprises nitrogen radicals and hydrogen radicals. In some embodiments, the nitrogen radicals and hydrogen radicals are formed by passing a conditioning gas across a hot wire. In some embodiments, the nitrogen radicals and hydrogen radicals are formed within a plasma generated from a conditioning gas. In some embodiments, the plasma is a direct plasma. In some embodiments, the plasma is a remote plasma.

The conditioning gas of some embodiments comprises one or more of ammonia (NH3), hydrazine (N2H4), nitrogen (N2), hydrogen (H2) or argon (Ar). The conditioning gas of some embodiments comprises one or more of ammonia (NH3), hydrazine (N2H4), nitrogen (N2), hydrogen (H2) or argon (Ar), with the proviso that each of nitrogen (N2), hydrogen (H2) or argon (Ar) are used with at least one additional gaseous species to provide nitrogen and hydrogen radicals. In some embodiments, the conditioning gas comprises an ammonia hydrogen compound (azane). In some embodiments, the conditioning gas comprises one or more of diazane (hydrazine), triazane (N3H5), diazene (N2H2) or triazene (N3H3). In some embodiments, the conditioning gas comprises at least one species having both nitrogen atoms and hydrogen atoms. In some embodiments, the conditioning gas comprises or consists essentially of ammonia (NH3). As used in this manner, the term “consists essentially of” means that the active species within the conditioning gas are greater than or equal to 95%, 98%, 99% or 99.5% of the stated species on a molecular basis, or sum of the states specie, without counting inert or diluent species. In some embodiments, the conditioning gas comprises or consists essentially of hydrazine (N2H4). In some embodiments, the conditioning gas comprises or consists essentially of ammonia and hydrogen (H2). In some embodiments, the conditioning gas comprises or consists essentially of hydrogen (H2) and nitrogen (N2).

In some embodiments, the conditioning gas comprises ammonia (NH3), hydrogen (H2) and argon (Ar). In some embodiments, the conditioning gas consists essentially of ammonia (NH3), hydrogen (H2) and argon (Ar). The ratio of ammonia:hydrogen:argon (NH3:H2:Ar) of some embodiments, is in the range of 0.9-1.1 NH3: 0.9-1.1 H2: 0.9-1.1 Ar. In some embodiments, the ratio of ammonia:hydrogen:argon (NH3:H2:Ar) is about 1:1:1. In some embodiments, the ratio of ammonia:hydrogen:argon (NH3:H2:Ar) is in the range of 1-20 NH3:1-20 H2:1 Ar, or in the range of 1-10:1-10:1, or in the range of 10:10:0.1-10 Ar. In some embodiments, the amount of ammonia (NH3) and hydrogen (H2) is within ±10% relative and the argon (Ar) is a diluent of any appropriate amount to provide enough reactive species in the process chamber.

In some embodiments, the conditioning gas comprises a plasma with a frequency in the range of about 2 MHz to 100 MHz, 13.56 MHz to 60 MHz, 13.56 MHz to 40 MHz. In some embodiments, the conditioning gas comprises a plasma with a pressure in the range of about 0.5 torr to about 25 torr (about 67 pascals to about 3333 pascals), or in the range of about 1 torr to 15 torr (about 133 pascals to about 2000 pascals, or in the range of about 1.5 torr to about 10 torr (about 200 pascals to about 1333 pascals). In some embodiments, the conditioning gas comprises a plasma and the conditioning process is performed for less than or equal to five minutes.

Referring toFIG.2, after the conditioning process210, a nitride layer is deposited 220 on one or more wafers (substrates). The number of wafers deposited on before re-conditioning the process kit150depends on, for example, the conditioning process parameters used, the deposition parameters and nitride layer composition. The number of wafers between re-conditioning using the conditioning process210of some embodiments is in the range of 5 to 50 wafers. In some embodiments, following method200increases the lifetime of the process kit150by at least 5× relative to a process kit without the conditioning process210being performed. In some embodiments, the lifetime of the process kit is defined as the number of wafers that can be processed between cleaning or preventative maintenance. For any given process, a typical reference lifetime is in the range of <1 K to 10K.

Some embodiments of the method begin with a seasoning process205to season the process kit150. The seasoning process205of some embodiments uses the deposition process220followed by the conditioning process210to prepare the process kit150for use. In some embodiments, the process kit150is subjected to the seasoning process205prior to installation in a deposition chamber. In some embodiments, the seasoning process205comprises a form of the deposition process followed by a form of the conditioning process. In some embodiments, the seasoning process comprises a form of the deposition process and the method200moves to the conditioning process210as a next procedure to condition and complete the seasoning process. In some embodiments in which the seasoning process includes a form of the conditioning process, after the seasoning process205, the method200proceeds to the deposition process220, following optional path222.

With reference toFIG.1, additional embodiments of the disclosure are directed to process chambers100for executing the methods described herein.FIG.1illustrates a chamber100that can be used to process a substrate according to one or more embodiment of the disclosure. The process chamber100comprises at least one controller190configured to control various components of the chamber100. In some embodiments, there is more than processor connected to the process chamber100with a primary control processor coupled to each of the separate processors to control the chamber100. The controller190may be one of any form of general-purpose computer processor, microcontroller, microprocessor, etc., that can be used in an industrial setting for controlling various chambers and sub-processors.

In some embodiments, the controller190has a processor192(also referred to as a CPU), a memory194coupled to the processor192, input/output devices196coupled to the processor192, and support circuits198to communication between the different electronic components. In some embodiments, the memory194includes one or more of transitory memory (e.g., random access memory) or non-transitory memory (e.g., storage).

The memory194, or computer-readable medium, of the processor may be one or more of readily available memory such as random access memory (RAM), read-only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The memory194can retain an instruction set that is operable by the processor192to control parameters and components of the system. The support circuits198are coupled to the processor192for supporting the processor in a conventional manner. Circuits may include, for example, cache, power supplies, clock circuits, input/output circuitry, subsystems, and the like.

Processes may generally be stored in the memory as a software routine that, when executed by the processor, causes the process chamber to perform processes of the present disclosure. The software routine may also be stored and/or executed by a second processor (not shown) that is remotely located from the hardware being controlled by the processor. Some or all of the method of the present disclosure may also be performed in hardware. As such, the process may be implemented in software and executed using a computer system, in hardware as, e.g., 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 the processor, transforms the general purpose computer into a specific purpose computer (controller) that controls the chamber operation such that the processes are performed.

In some embodiments, the controller190has one or more configurations to execute individual processes or sub-processes to perform the method. In some embodiments, the controller190is connected to and configured to operate intermediate components to perform the functions of the methods. For example, the controller190of some embodiments is connected to and configured to control one or more of gas valves, actuators, motors, slit valves, vacuum control, etc.

The controller190of some embodiments has one or more configurations selected from: a configuration to expose a substrate to a deposition process condition to deposit a nitride film; a configuration to expose a process kit of the process chamber to a conditioning process. A non-transitory computer readable medium including instructions, that, when executed by a controller of a processing chamber, causes the processing chamber to perform operations of: exposing a substrate to a deposition process condition to deposit a nitride film; and exposing a process kit of the process chamber to a conditioning process.