TW202517812A - Gapfill process using pulsed high-frequency radio-frequency (hfrf) plasma - Google Patents

Abstract

Methods for forming a metal carbide liner in features formed in a substrate surface are described. Each of the features extends a distance into the substrate from the substrate surface and have a bottom and at least one sidewall. The methods include depositing a metal carbide liner in the feature of the substrate surface with a plurality of high-frequency ratio-frequency (HFRF) pulses. Semiconductor devices with the metal carbide liner and methods for filling gaps using the metal carbide liner are also described.

Description

Gap filling process using pulsed high frequency radio frequency (HFRF) plasma

Cross-references to related applications

This case is a continuation-in-part of U.S. patent application No. 17/157,307 filed on January 25, 2021, the entire disclosure of which is incorporated herein by reference.

The present invention relates generally to methods for gap filling and more particularly to processes for gap filling using pulsed high frequency radio frequency (HFRF) plasma.

In microelectronic device fabrication, for many applications, narrow trenches with aspect ratios (AR) greater than 10:1 need to be filled without voids. One application is for shallow trench isolation (STI). For this application, the film needs to be of high quality throughout the trench (e.g., have a wet etch rate ratio of less than 2) and have very low leakage. One approach that has been successful in the past is flowable CVD. In this approach, oligomers are carefully formed in the gas phase, condense on the surface, and then "flow" into the trench. The as-deposited film quality is very poor and requires processing steps such as steam annealing and UV curing.

As feature sizes decrease and aspect ratios increase, post-curing of as-deposited flowable films becomes difficult, resulting in films with varying compositions throughout the filled trenches.

Amorphous silicon has been widely used as a sacrificial layer in semiconductor manufacturing processes because it can provide good etch selectivity relative to other films (e.g., silicon oxide, amorphous carbon, etc.). With the reduction of critical dimensions (CD) in semiconductor manufacturing, filling high aspect ratio gaps has become increasingly sensitive for advanced wafer manufacturing. The current metal replacement gate process involves either melt polysilicon or amorphous silicon virtual gate. Due to the nature of the process, a seam is formed in the middle of the Si virtual gate. This seam may open during post processing and cause structural failure.

Conventional plasma enhanced chemical vapor deposition (PECVD) of amorphous silicon (a-Si) forms a "mushroom-shaped" film at the top of narrow trenches. This is due to the inability of the plasma to penetrate into deep trenches. The result is that the narrow trench is pinched off from the top; a void or seam is formed at the bottom of the trench.

Conventional thermal CVD/furnace processes can grow a-Si via thermal decomposition of silicon precursors (e.g., silane, disilane). However, due to insufficient precursor supply or the presence of decomposition byproducts, the deposition rate at the top of the trench is higher than the deposition rate at the bottom of the trench. Narrow seams or voids can be observed in the trench.

Additionally, many semiconductor device applications include conformal pads. As device sizes shrink, conventional plasma enhanced chemical vapor deposition of metal carbides (e.g., tungsten carbide) forms a mushroom-shaped film on top of narrow trenches, where the film is very thin at the sidewalls. Since plasma cannot penetrate into deep trenches, films of this shape cannot be used as conformal pads.

Therefore, there is a need for methods for forming metal carbide conformal pads in semiconductor devices.

One or more embodiments of the present invention relate to a method of gap filling. A substrate surface of a substrate is exposed to a deposition process, the deposition process including a pulsed high frequency radio frequency (HFRF) plasma having a plurality of HFRF pulses to deposit a liner. The substrate surface has a plurality of features formed in the substrate surface. Each of the plurality of features extends a distance from the substrate surface into the substrate and has a bottom and at least one sidewall. The liner includes a metal carbide.

Another embodiment of the present invention relates to a method of forming a liner using HFRF. A metal carbide liner is formed on the sidewalls of a plurality of features formed in a substrate surface. Each feature extends a distance from the substrate surface into the substrate and has at least one sidewall. Forming the liner includes exposing the substrate to a chemical vapor deposition process having a plurality of liner HFRF pulses.

Further embodiments of the present invention relate to methods of forming a pad in a semiconductor device. A metal carbide pad is formed on the sidewalls of a plurality of features formed in a substrate surface. Each feature extends a distance from the substrate surface into the substrate and has at least one sidewall. Forming the metal carbide pad includes exposing the substrate to a chemical vapor deposition process using one or more of a tungsten-containing precursor, a molybdenum-containing precursor, or a nickel-containing precursor and a plurality of pad HFRF pulses to form a metal carbide pad having a tensile stress.

Before describing several exemplary embodiments of the present invention, it should be understood that the present invention is not limited to the details of the construction or process steps described in the following description. The present invention is capable of other embodiments and can be practiced or implemented in various ways.

As used herein, "substrate" refers to any substrate or material surface formed on a substrate on which film processing is performed during a manufacturing process. For example, depending on the application, substrate surfaces on which processing may 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 material such as metals, metal nitrides, metal alloys, and other conductive materials. Substrates include, but are not limited to, semiconductor wafers. The substrate may be exposed to pre-treatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, electron beam cure, and/or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in the present case, 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" is intended to include such underlying layers as the context indicates. Thus, for example, where a film/layer or portion of a film/layer has been deposited onto the substrate surface, the exposed surface of the newly deposited film/layer becomes the substrate surface.

One or more embodiments of the present invention provide a low temperature silicon gapfill process. By first depositing and then etching some of the silicon film around the trench structure, a substantially thicker amorphous silicon (a-Si) film volume is produced at the bottom of the trench compared to the sidewalls or top of the trench. Some embodiments provide a method for cyclic deposition and etching to form a defect-free silicon gapfill.

Embodiments of the present invention provide methods for depositing films (e.g., amorphous silicon) in high aspect ratio (AR) structures with small dimensions. Some embodiments advantageously provide methods involving cyclic deposition-etch-treat processes that can be performed in a cluster tool environment. Some embodiments advantageously provide high-quality amorphous silicon films without defective doping or alloying to fill high AR trenches with small dimensions.

FIG. 1 illustrates a partial cross-sectional view of a substrate 100 having a feature 110. For purposes of illustration, the figure illustrates a substrate having a single feature; however, one skilled in the art will appreciate that there may be more than one feature. The shape of feature 110 may be any suitable shape, including but not limited to a trench and a cylindrical through hole. As used in this regard, the term "feature" means any intentional surface irregularity. Suitable examples of features include but are not limited to a trench having a top, two sidewalls, and a bottom, a peak having a top and two sidewalls. Features may have any suitable aspect ratio (the ratio of the depth of the feature to the width of the feature). In some embodiments, the aspect ratio is greater than or equal to approximately 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, or 40:1.

Substrate 100 has a substrate surface 120. At least one feature 110 forms an opening in substrate surface 120. Feature 110 extends a depth D from substrate surface 120 to bottom surface 112. Feature 110 has a first sidewall 114 and a second sidewall 116 that define a width W of feature 110. The open area formed by the sidewalls and bottom is also referred to as a gap.

During a gap filling process, a seam is often formed in the fill material. The size and width of the seam may affect the overall operability of the gap filling component. The size and width of the seam may also be affected by process conditions and the deposited material. Thus, one or more embodiments advantageously provide a method for seamless (or void-free) gap filling. Some embodiments of the method advantageously disclose a cyclic deposition-treatment-etch process for gap filling. In some embodiments, the gap filling is flawless.

FIG. 2 and FIG. 3A-3D illustrate an exemplary gapfill method 200 according to one or more embodiments of the disclosure. In the embodiment shown in FIG. 2 , method 200 is performed on a substrate 100 having at least one feature 110. In some embodiments, feature 110 has an aspect ratio greater than or equal to 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, or 40:1. In some embodiments, method 200 includes depositing a film 220 and etching a film 240. In some embodiments, film deposition 220 and/or film etching 240 are performed in one or more processing chambers in a cluster tool environment. In some embodiments, film deposition 220 and/or film etching 240 includes a plurality of high frequency radio frequency (HFRF) pulses. In one or more embodiments, the plasma includes a pulsed HFRF plasma. In some embodiments, the pulsed HFRF plasma includes a plurality of HFRF pulses. In some embodiments, the pulsed HFRF plasma deposits a non-conformal film.

Some embodiments advantageously provide methods for using plasma to etch material (e.g., Si) faster on the sidewalls of a feature than at the bottom of the feature. Some embodiments advantageously use different etching rates on different surfaces and at different locations to produce bottom-up growth by a cyclic deposition-etching process.

In the embodiment shown in FIG. 3A , substrate 100 has features 110 formed on substrate 100 and two different surfaces: a first surface 350 and a second surface 360. First surface 350 and second surface 360 may be different materials. For example, one of the surfaces may be a metal and the other may be a dielectric. In some embodiments, first surface 350 and second surface 360 have the same chemical composition but different physical properties (e.g., crystallinity). When describing the following methods, reference to substrate 100 means first surface 350 and second surface 360 or a single surface in which features 110 are formed.

3A, feature 110 is formed by a first surface 350 and a second surface 360. The feature 110 shown is a trench, wherein the first surface 350 forms the bottom of the feature and the second surface 360 forms the sidewalls and top.

Some embodiments of the method 200 include an optional substrate pretreatment 210. In some embodiments, the substrate is exposed to one or more process conditions to pretreat or prepare the substrate surface for deposition. For example, in some embodiments, the pretreatment densifies the substrate surface or changes the surface termination. In some embodiments, the optional pretreatment 210 includes one or more of polishing, etching, reducing, oxidizing, hydroxylating, annealing, UV curing, electron beam curing, plasma treatment, and/or baking the substrate surface. In some embodiments, the plasma treatment includes NH ₃ plasma treatment.

In some embodiments, a pad is formed in the feature 110 in a pad formation process 215. The pad formation process 215 is an optional process that may be included in the method 200 or may be part of a separate method.

At deposition process 220, a film 370 is deposited on substrate 100. In one or more embodiments, depositing film 370 includes a plasma enhanced chemical vapor deposition (PECVD) process or a plasma enhanced atomic layer deposition (PEALD) process. In some embodiments, deposition process 220 includes a PECVD process. In some embodiments, deposition process 220 includes a PEALD process. In some embodiments, PECVD includes a gap-filling pulsed high frequency radio frequency (HFRF) plasma. In some embodiments, the gap-filling pulsed HFRF plasma includes a plurality of gap-filling HFRF pulses. The gap-filling pulsed HFRF plasma may also be referred to as a "first" HFRF plasma. The use of ordinal numbers such as "first", "second", etc. is used to identify different processes or components and is not intended to imply a specific order of operation or use.

As used herein, high frequency RF plasma includes high frequency on/off pulses of power. When on, the power is delivered at RF. Pulse frequency and RF refer to different aspects of the power used to generate plasma, which aspects can be controlled independently.

The film 370 can be any suitable film that can be selectively deposited on the first surface 350 relative to the second surface 360. In some embodiments, the film 370 includes silicon. In some embodiments, the film 370 consists essentially of silicon. As used in this manner, the term "consisting essentially of..." means that the film is greater than or equal to about 90%, 93%, 95%, 98%, or 99% silicon (or a specified substance) in terms of atoms. In some embodiments, the film 370 includes amorphous silicon. In some embodiments, the film 370 consists essentially only of amorphous silicon. The term "essentially only amorphous silicon" used in this manner means that the film 370 is greater than or equal to about 90%, 93%, 95%, 98%, or 99% amorphous silicon.

3A illustrates film 370 formed on the substrate surface (top 374), sidewalls 376, and bottom 372 of feature 110. Film 370 deposited on the substrate will have a film thickness _Ts on the sidewalls of the feature, a film thickness _Tt on the top of the feature (i.e., on the surface of the substrate), and a film thickness _Tb on the bottom of feature 110.

In some embodiments, the film 370 is formed non-conformally on at least one feature. As used herein, the term "non-conformal" or "non-conformally" refers to a layer that adheres to and covers an exposed surface non-uniformly, wherein the thickness variation is greater than 10% relative to the average thickness of the film. For example, a film with an average thickness of 100Å will have a thickness variation greater than 10Å. Such thickness variations include edges, corners, sides, and the bottom of grooves. In some embodiments, the variation is greater than or equal to 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. In some embodiments, the film deposited on the sidewalls of the trench is thinner than the film deposited at the bottom of the trench or on the surface in which the trench is formed. In some embodiments, the average thickness of the deposited film on the sidewalls is less than or equal to 90%, 80%, 70%, 60%, 50%, 40%, 30% or 20% of the average thickness on the bottom and/or top of the trench.

In some embodiments, before stopping the deposition, the film 370 is deposited to an average thickness in the range of 1 nm to 100 nm, 1 nm to 80 nm, 1 nm to 50 nm, 10 nm to 100 nm, 10 nm to 80 nm, 10 nm to 50 nm, 20 nm to 100 nm, 20 nm to 80 nm, or 20 nm to 50 nm. In some embodiments, the film 370 is deposited to an average thickness in the range of 5 nm to 100 nm, 5 nm to 80 nm, 5 nm to 40 nm, 5 nm to 30 nm, or 10 nm to 30 nm.

The process parameters used to deposit film 370 can affect the film thickness at the sidewalls of the feature, the top of the feature, and/or the bottom of the feature. For example, specific precursors and/or reactive species, plasma conditions, temperature, etc. In some embodiments, the thickness _Tt at the top of the feature is greater than the thickness _Ts at the sidewalls of the feature. In some embodiments, the thickness _Tb at the bottom of the feature is greater than the thickness _Ts at the sidewalls of the feature. In some embodiments, the thickness _Tt at the top of the feature is greater than the thickness _Tb at the bottom of the feature. In some embodiments, the thickness _Tb at the bottom of the feature is greater than the thickness _Tt at the top of the feature.

During the film deposition 220 process, the substrate is exposed to one or more process gases and/or conditions that form a film 370. In some embodiments, a process gas is flowed into a processing region of a processing chamber, and a pulsed HFRF plasma is formed from the process gas to deposit the film 370. The process gas of some embodiments includes a silicon precursor and a carrier gas, and the carrier gas is ignited into a plasma by HFRF power.

In one or more embodiments, the gap-filling pulsed HFRF plasma is a conductively coupled plasma (CCP) or an inductively coupled plasma (ICP). In some embodiments, the gap-filling pulsed HFRF plasma is a direct plasma or a remote plasma. In some embodiments, each of the plurality of gap-filling HFRF pulses is independently generated at a gap-filling power in the range of 0 W to 500 W, 50 W to 500 W, 50 W to 400 W, 50 W to 300 W, 50 W to 200 W, 50 W to 100 W, 100 W to 500 W, 100 W to 400 W, 100 W to 300 W, 100 W to 200 W, 200 W to 500 W, 200 W to 400 W, or 200 W to 300 W. In some embodiments, the minimum gap-filling plasma power is greater than 0 W. In some embodiments, all gap-filling pulses have the same power. In some embodiments, the power of each pulse in the gap-filling HFRF plasma varies.

In one or more embodiments, a plurality of gap-filling HFRF plasma pulses have a gap-filling duty cycle in a range of 1% to 50%, 1% to 45%, 1% to 40%, 1% to 35%, 1% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 10%, 5% to 50%, 5% to 45%, 5% to 40%, 5% to 35%, 5% to 30%, 5% to 25%, 5% to 20%, 5% to 15%, 5% to 10%, 10% to 50%, 10% to 45%, 10% to 40%, 10% to 35%, 10% to 30%, 10% to 25%, 10% to 20%, or 10% to 15%. In some embodiments, each of the plasma pulses during the gapfill deposition process has the same duty cycle. In some embodiments, the duty cycle varies during the gapfill deposition process.

In one or more embodiments, each of the plurality of gap-fill HFRF plasma pulses independently has a pulse width in the range of 5 milliseconds to 50 microseconds, 4 milliseconds to 50 microseconds, 3 milliseconds to 50 microseconds, 2 milliseconds to 50 microseconds, 1 millisecond to 50 microseconds, 800 microseconds to 50 microseconds, 500 microseconds to 50 microseconds, 200 microseconds to 50 microseconds, 5 milliseconds to 100 microseconds, 4 milliseconds to 100 microseconds, 3 milliseconds to 100 microseconds, 2 milliseconds to 100 microseconds, 1 millisecond to 100 microseconds, 800 microseconds to 100 microseconds, 500 microseconds to 100 microseconds, and 200 microseconds to 100 microseconds. In some embodiments, each of the pulse widths is the same during the deposition process. In some embodiments, the pulse width is varied during the deposition process.

In one or more embodiments, each of the plurality of gap-fill HFRF plasma pulses independently has a gap-fill pulse frequency in the range of 0.1 kHz to 20 kHz, 0.1 kHz to 15 kHz, 0.1 kHz to 10 kHz, 0.1 kHz to 5 kHz, 0.5 kHz to 20 kHz, 0.5 kHz to 15 kHz, 0.5 kHz to 10 kHz, 0.5 kHz to 5 kHz, 1 kHz to 20 kHz, 1 kHz to 15 kHz, 1 kHz to 10 kHz, 1 kHz to 5 kHz, 2 kHz to 20 kHz, 2 kHz to 15 kHz, 2 kHz to 10 kHz, or 2 kHz to 5 kHz. In some embodiments, the pulse frequency remains the same during the deposition process. In some embodiments, the pulse frequency is varied during the deposition process.

In one or more embodiments, the plurality of gap-filling HFRF pulses have a gap-filling RF frequency in the range of 5 MHz to 20 MHz, 5 MHz to 15 MHz, 5 MHz to 10 MHz, 10 MHz to 20 MHz, or 10 MHz to 15 MHz. In one or more embodiments, the plurality of gap-filling HFRF pulses have a first RF frequency of 13.56 MHz. In some embodiments, the RF frequency of the pulses is the same during the deposition process. In some embodiments, the RF frequency of the pulses varies during the deposition process. In one or more embodiments, each of the plurality of gap-filling HFRF pulses independently has a first RF frequency in the range of 5 MHz to 20 MHz, 5 MHz to 15 MHz, 5 MHz to 10 MHz, 10 MHz to 20 MHz, or 10 MHz to 15 MHz. In one or more embodiments, each of the plurality of gap-filling HFRF pulses independently has a first RF frequency of 13.56 MHz.

In one or more embodiments, each of the plurality of gapfill HFRF pulses has a gapfill duty cycle in the range of 1% to 50%, 1% to 45%, 1% to 40%, 1% to 35%, 1% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 10%, 5% to 50%, 5% to 45%, 5% to 40%, 5% to 35%, 5% to 30%, 5% to 25%, 5% to 20%, 5% to 15%, 5% to 10%, 10% to 50%, 10% to 45%, 10% to 40%, 10% to 35%, 10% to 30%, 10% to 25%, 10% to 20%, or 10% to 15%. In some embodiments, the duty cycle of the pulses is the same during the deposition process. In some embodiments, the duty cycle of the pulse is varied during the deposition process.

The deposition process 220 may occur at any suitable substrate temperature. In some embodiments, the substrate is maintained at 15°C to 250°C, 15°C to 225°C, 15°C to 200°C, 15°C to 175°C, 15°C to 150°C, 15°C to 125°C, 15°C to 100°C, 25°C to 250°C, 25°C to 225°C, 25°C to 200°C, 25°C to 175°C, 25°C to 150°C, 25°C to 125°C, 25°C to 100°C, 25°C to 250°C, 25°C to 225°C, 25°C to 200°C, 25°C to 175°C, 25°C to 150°C, 25°C to 125°C, 25°C to 1 C to 100°C, 50°C to 250°C, 50°C to 225°C, 50°C to 200°C, 50°C to 175°C, 50°C to 150°C, 50°C to 125°C, 50°C to 100°C, 75°C to 250°C, 75°C to 225°C, 75°C to 200°C, 75°C to 175°C, 75°C to 150°C, 75°C to 125°C, or 75°C to 100°C.

In one or more embodiments, the film deposition process 220 includes flowing one or more of a first carrier gas, a precursor, or a first reactant onto the substrate surface. In some embodiments, the carrier gas includes, but is not limited to, argon (Ar), helium He, H ₂ , or N _2. In some embodiments, the carrier gas includes helium (He) or consists essentially of helium (He). In some embodiments, the carrier gas includes argon (Ar). In one or more embodiments, the precursor includes, but is not limited to, silane, disilane, dichlorosilane (DCS), trisilane, or tetrasilane. In some embodiments, the precursor gas includes silane (SiH ₄ ). In _some embodiments _{, the precursor gas includes or consists essentially of disilane (Si 2 H 6} ). In some embodiments, the precursor gas is heated in a hot pot to increase the vapor pressure and delivered to the chamber using a carrier gas. In some embodiments, the first reactant gas includes _H2 .

In one or more embodiments, each of the gapfill carrier gas, the precursor gas, or the gapfill reactant gas is introduced at a flow rate of 40 sccm to 10000 sccm, 40 sccm to 5000 sccm, 40 sccm to 2000 sccm, 40 sccm to 1000 sccm, 40 sccm to 500 sccm, 40 sccm to 100 sccm, 100 sccm to 10000 sccm, 100 sccm to 5000 sccm, 100 sccm to 2000 sccm, 100 sccm to 1 Doses in the range of 100-2000 sccm, 100-500 sccm, 250-10000 sccm, 250-5000 sccm, 250-2000 sccm, 250-1000 sccm, 250-500 sccm, 500-10000 sccm, 500-5000 sccm, 500-2000 sccm, or 500-1000 sccm are independently flowed onto the substrate surface.

In some embodiments, as shown in FIG3A , the film 370 deposited during the deposition process 220 is a continuous film. As used herein, the term “continuous” refers to a layer that covers the entire exposed surface without gaps or bare spots that expose the material underlying the deposited layer. A continuous film may have gaps or bare spots that have a surface area of less than about 1% of the total surface area of the film.

After the deposition process 220, the method 200 reaches a decision point 230. At the decision point 230, the fill condition of the feature is evaluated. If the feature 110 or gap has been completely filled, the method 200 can be stopped and the substrate can be subjected to optional post-processing 260. If the feature or gap has not been filled, the method 200 moves to an etching process 240.

In one or more embodiments, the substrate 100 is subjected to a purge process and/or a vacuum process after the deposition process 220 but before the etching process 240. In some embodiments, a purge gas such as argon is introduced into the processing chamber between the deposition process 220 and the etching process 240 to purge the reaction zone or otherwise remove any residual reactive compounds or byproducts from the reaction zone. In some embodiments, the purge gas flows into the processing chamber continuously throughout the method 200. In some embodiments, a negative pressure is applied to the processing chamber between the deposition process 220 and the etching process 240 to remove any residual reactive compounds or byproducts from the reaction zone. In some embodiments, a negative pressure is continuously applied to the processing chamber throughout the method 200. In some embodiments, a purge process and/or a vacuum process is applied prior to the post-processing 260.

In one or more embodiments, the etching process 240 etches the non-conformal film. In some embodiments, the thickness _Ts of the film 370 on the sidewalls of the feature 110 etched by the etching process 240 is greater than the thickness _Tb from the bottom of the feature 110. In one or more embodiments, the thickness _Ts of the film 370 on the sidewalls of the feature 110 etched by the etching process is greater than the thickness _Tt from the top of the feature 110.

Without being bound by any particular theory of operation, it is believed that the directed plasma treatment preferentially modifies the top film 374 and the bottom film 372 relative to the sidewall film 376. The modified films appear to be more resistant to etching. This results in higher sidewall etching rates thereafter. FIG. 3B illustrates a feature 110 of a film that has been subjected to etching resulting in modification of the top film 384 and the bottom film 382 according to one or more embodiments of the present invention.

FIG. 3C illustrates an etch film according to one or more embodiments of the present invention. The etch film 370 removes substantially all of the sidewall film 376 from the feature 110, leaving some of the top film 384 and the bottom film 382. In some embodiments, removing substantially all of the sidewall film 376 means that at least about 95%, 98%, or 99% of the surface area of the sidewall has been etched. In some embodiments, removing substantially all of the sidewall film 376 includes nucleation delay for the subsequent deposition process 220.

In one or more embodiments, the etching process 240 includes exposing the substrate surface to one or more of an etching carrier gas or an etching reactant gas. In some embodiments, the second carrier gas includes one or more of argon (Ar), helium (He), or nitrogen ( _N2 ). In some embodiments, the second reactant gas includes one or more of _Cl2 , _H2 , _NF3 , or HCl. In some embodiments, the second reactant gas includes _H2 or consists essentially of _H2 . In some embodiments, each of the second carrier gas or the second reactant gas is introduced at a flow rate of 40 sccm to 10000 sccm, 40 sccm to 5000 sccm, 40 sccm to 2000 sccm, 40 sccm to 1000 sccm, 40 sccm to 500 sccm, 40 sccm to 100 sccm, 100 sccm to 10000 sccm, 100 sccm to 5000 sccm, 100 sccm to 2000 sccm, 100 sccm to 1000 sccm, 100 sccm to 500 sccm, 250 sccm to 10000 sccm, 250 sccm to 5000 sccm, 250 sccm to 2000 sccm, 250 sccm to 1000 sccm, 250 sccm to 500 sccm, 500 sccm to 10000 sccm, 500 sccm to 5000 sccm, 500 sccm to 2000 sccm, or 500 sccm to 1000 sccm, independently flowed onto the substrate surface.

In one or more embodiments, the etching process 240 includes maintaining the temperature of the substrate 100 at 15°C to 250°C, 15°C to 225°C, 15°C to 200°C, 15°C to 175°C, 15°C to 150°C, 15°C to 125°C, 15°C to 100°C, 25°C to 250°C, 25°C to 225°C, 25°C to 200°C, 25°C to 175°C, 25°C to 150°C, 25°C to 125°C, 25°C, 75°C to 250°C, 75°C to 225°C, 75°C to 200°C, 75°C to 175°C, 75°C to 150°C, 75°C to 125°C, 75°C to 100°C, 75°C to 250°C, 75°C to 225°C, 75°C to 200°C, 75°C to 175°C, 75°C to 150°C, 75°C to 125°C, or 75°C to 100°C. In some embodiments, the substrate is maintained at the same temperature during the deposition process 220 and the etching process 240. In some embodiments, the substrate is maintained at different (ΔT>10° C.) temperatures during the deposition process 220 and the etching process 240 .

In one or more embodiments, the etching process 240 includes maintaining the pressure of the substrate 100 in a range of 0.1 Torr to 12 Torr, 0.5 Torr to 12 Torr, 1 Torr to 12 Torr, 2 Torr to 12 Torr, 3 Torr to 12 Torr, 4 Torr to 12 Torr, 0.1 Torr to 10 Torr, 0.5 Torr to 10 Torr, 1 Torr to 10 Torr, 2 Torr to 10 Torr, 3 Torr to 10 Torr, 4 Torr to 10 Torr, 0.1 Torr to 8 Torr, 0.5 Torr to 8 Torr, 1 Torr to 8 Torr, 2 Torr to 8 Torr, 3 Torr to 8 Torr, 4 Torr to 8 Torr, 0.1 Torr to 5 Torr, 0.5 Torr to 5 Torr, 1 Torr to 5 Torr, 2 Torr to 5 Torr, 3 Torr to 5 Torr, or 4 Torr to 5 Torr.

In some embodiments, the etching process 240 includes an etching plasma. In some embodiments, the etching plasma is a conductively coupled plasma (CCP) or an inductively coupled plasma (ICP). In some embodiments, the etching plasma is a direct plasma or a remote plasma. In some embodiments, the etching plasma is operated at a power in the range of 0 W to 500 W, 50 W to 500 W, 50 W to 400 W, 50 W to 300 W, 50 W to 200 W, 50 W to 100 W, 100 W to 500 W, 100 W to 400 W, 100 W to 300 W, 100 W to 200 W, 200 W to 500 W, 200 W to 400 W, or 200 W to 300 W. In some embodiments, the minimum power of the plasma is greater than 0 W.

In some embodiments, the etching process occurs at a continuous power level. In some embodiments, the etching process occurs with a second HFRF plasma pulse. In some embodiments, each of the plurality of second HFRF plasma pulses is independently generated at an etching power in the range of 0 W to 500 W, 50 W to 500 W, 50 W to 400 W, 50 W to 300 W, 50 W to 200 W, 50 W to 100 W, 100 W to 500 W, 100 W to 400 W, 100 W to 300 W, 100 W to 200 W, 200 W to 500 W, 200 W to 400 W, or 200 W to 300 W. In some embodiments, the minimum second plasma power is greater than 0 W. In some embodiments, the power of the pulse is the same during the etching process. In some embodiments, the power of the pulse varies during the etching process.

In one or more embodiments, the plurality of second HFRF plasma pulses have a duty cycle in the range of 1% to 50%, 1% to 45%, 1% to 40%, 1% to 35%, 1% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 10%, 5% to 50%, 5% to 45%, 5% to 40%, 5% to 35%, 5% to 30%, 5% to 25%, 5% to 20%, 5% to 15%, 5% to 10%, 10% to 50%, 10% to 45%, 10% to 40%, 10% to 35%, 10% to 30%, 10% to 25%, 10% to 20%, or 10% to 15%. In some embodiments, the duty cycles of the pulses are the same during the etching process. In some embodiments, the duty cycle of the pulse is varied during the etching process.

In one or more embodiments, each of the plurality of second HFRF plasma pulses has a pulse width in the following range: 5 milliseconds to 50 microseconds, 4 milliseconds to 50 microseconds, 3 milliseconds to 50 microseconds, 2 milliseconds to 50 microseconds, 1 millisecond to 50 microseconds, 800 microseconds to 50 microseconds, 500 microseconds to 50 microseconds, 200 microseconds to 50 microseconds, 5 milliseconds to 100 microseconds, 4 milliseconds to 100 microseconds, 3 milliseconds to 100 microseconds, 2 milliseconds to 100 microseconds, 1 millisecond to 100 microseconds, 800 microseconds to 100 microseconds, 500 microseconds to 100 microseconds, and 200 microseconds to 100 microseconds. In some embodiments, the pulse widths of the pulses are the same during the etching process. In some embodiments, the pulse width of the pulse is varied during the etching process.

In one or more embodiments, each of the plurality of second HFRF plasma pulses independently has a pulse frequency in the range of 0.1 kHz to 20 kHz, 0.1 kHz to 15 kHz, 0.1 kHz to 10 kHz, 0.1 kHz to 5 kHz, 0.5 kHz to 20 kHz, 0.5 kHz to 15 kHz, 0.5 kHz to 10 kHz, 0.5 kHz to 5 kHz, 1 kHz to 20 kHz, 1 kHz to 15 kHz, 1 kHz to 10 kHz, 1 kHz to 5 kHz, 2 kHz to 20 kHz, 2 kHz to 15 kHz, 2 kHz to 10 kHz, or 2 kHz to 5 kHz. In some embodiments, the frequency of the pulses is the same during the etching process. In some embodiments, the frequency of the pulses is varied during the etching process.

In one or more embodiments, the plurality of second HFRF pulses have an etching RF frequency in the range of 5 MHz to 20 MHz, 5 MHz to 15 MHz, 5 MHz to 10 MHz, 10 MHz to 20 MHz, or 10 MHz to 15 MHz. In one or more embodiments, the plurality of second HFRF pulses have a second RF frequency of 13.56 MHz. In some embodiments, the RF frequency of the pulses is the same during the etching process. In some embodiments, the RF frequency of the pulses varies during the etching process. In one or more embodiments, each of the plurality of second HFRF pulses independently has an etching RF frequency in the range of 5 MHz to 20 MHz, 5 MHz to 15 MHz, 5 MHz to 10 MHz, 10 MHz to 20 MHz, or 10 MHz to 15 MHz. In one or more embodiments, each of the plurality of second HFRF pulses independently has a second RF frequency of 13.56 MHz.

In one or more embodiments, method 200 further includes repeating deposition process 220 and etching film 240 for gap filling. In some embodiments, each of repeating deposition process 220 and repeating etching film 240 includes HFRF plasma. In some embodiments, the gap filling is flawless. FIG. 3D illustrates feature 110 that has been filled after multiple cycles of the deposition-etching-process.

In one or more embodiments, one or more additional effects further cause the etch rate of the non-conformal film on the sidewalls of the feature to be different from the etch rate of the non-conformal film on the bottom of the feature. In some embodiments, the one or more additional effects include: a nucleation rate of a material (e.g., Si) to be deposited on the substrate surface, a property of the substrate surface that affects the nucleation rate of a material to be deposited on the substrate surface, or an etch rate of a material (e.g., Si) to be deposited on the substrate surface.

Some embodiments include an optional post-treatment 260 process. Post-treatment 260 can be used to modify the film 370 to improve some parameters of the film. In some embodiments, post-treatment 260 includes annealing the film 370. In some embodiments, post-treatment 260 can be performed by in-situ annealing in the same processing chamber used for deposition 220 and/or etching 240. Suitable annealing processes include, but are not limited to, rapid thermal processing (RTP) or rapid thermal annealing (RTA), spike annealing or UV curing, or electron beam curing and/or laser annealing. The annealing temperature can be in the range of about 500°C to 900°C. The composition of the environment during annealing can include one or more of _H2 , Ar, He, _N2 , _NH3 , _SiH4, etc. The pressure during annealing may be in the range of about 100 mTorr to about 1 atmosphere.

Some embodiments of the present disclosure relate to conformal PECVD pads of metal-doped carbon films deposited using a pulsed HFRF plasma process. As used in this manner, "metal-doped carbon" and "metal carbide" are used interchangeably to refer to films having metal and carbon atoms.

Some embodiments of the present invention relate to metal carbide (e.g., tungsten carbide) pads for dynamic random access memory (DRAM) devices. Some embodiments of the present invention relate to metal carbide pad memory or logic applications. Some embodiments of the present invention relate to methods for forming metal carbide hard molds.

Conventional plasma enhanced chemical vapor deposition of tungsten carbide forms a "mushroom shaped" film on top of narrow trenches and a very thin film at the sidewalls, resulting in a poorly conformal liner. Without being bound by any particular theory of operation, it is believed that the plasma does not adequately penetrate into deep trenches, resulting in poor conformality. The current state of the art for tungsten carbide deposition is by PECVD using a continuous HFRF plasma, but does not produce good conformality, with the thinnest/thickest film conformality being about 22% for trenches with a critical dimension (CD) of about 100 nm. The inventors surprisingly found that using pulsed HFRF, tungsten carbide conformality can be improved to 40% to 70% or more. In some embodiments, pulsed HFRF plasma increases conformality by a factor of 2 or more.

FIG4A illustrates another embodiment of the present disclosure in which a metal carbide pad is formed using a pulsed HFRF plasma. The metal carbide pad of some embodiments is formed during a pad formation process 215 as part of method 200. In some embodiments, the metal carbide pad is formed as part of a method different from that shown in method 200.

In the illustrated embodiment, electronic device 300 has a metal carbide film 470 formed on the substrate surface, sidewalls, and bottom of feature 110. Film 470 deposited on the substrate will have a film thickness _Ts on the sidewalls of the feature, a film thickness _Tt on the top of the feature (i.e., on the surface of the substrate), and a film thickness _Tb on the bottom of feature 110. Metal carbide film 470 has a bottom surface 472 at the bottom of feature 110, a sidewall surface 476 at the sidewalls of feature 110, and a top surface 474 on the top surface of feature 110.

In some embodiments, film 470 is conformally formed over at least one feature. As used herein, the term "conformal" or "conformally" refers to a metal carbide layer that adheres to and uniformly covers an exposed surface, wherein the thickness of the film on the sidewalls is greater than or equal to 40% of the thickness of the film on the top/bottom of the feature. In some embodiments, the metal carbide film has a conformality in the range of 40% to 75%. In some embodiments, the metal carbide film has a conformality greater than or equal to 40%, 45%, 50%, 55%, 60%, 65%, or 70%. Film 470 has greater conformality than films formed without pulsed plasma (i.e., continuous plasma), which typically have a conformality less than or equal to 25%.

In some embodiments, before stopping the deposition, the film 470 is deposited to an average thickness in the range of 1 nm to 100 nm, 1 nm to 80 nm, 1 nm to 50 nm, 10 nm to 100 nm, 10 nm to 80 nm, 10 nm to 50 nm, 20 nm to 100 nm, 20 nm to 80 nm, or 20 nm to 50 nm. In some embodiments, the film 470 is deposited to an average thickness in the range of 5 nm to 100 nm, 5 nm to 80 nm, 5 nm to 40 nm, 5 nm to 30 nm, or 10 nm to 30 nm.

The process parameters used to deposit film 470 can affect the film thickness at the sidewalls of the feature, the top of the feature, and/or the bottom of the feature. For example, specific precursors and/or reactive species, plasma conditions, temperature, etc. In some embodiments, the thickness _Tt at the top of the feature is greater than the thickness _Ts at the sidewalls of the feature. In some embodiments, the thickness _Tb at the bottom of the feature is greater than the thickness _Ts at the sidewalls of the feature. In some embodiments, the thickness _Tt at the top of the feature is greater than the thickness _Tb at the bottom of the feature. In some embodiments, the thickness _Tb at the bottom of the feature is greater than the thickness _Tt at the top of the feature.

During the film deposition process, the substrate is exposed to one or more process gases and/or conditions that form the film 470. In some embodiments, a process gas flows into a processing region of a processing chamber, and a pulsed HFRF plasma is formed by the process gas to deposit the film 470. The process gas of some embodiments includes a metal precursor and a carrier gas, and the carrier gas is ignited into a plasma by HFRF power. In some embodiments, the metal precursor includes a metal halide or consists essentially of a metal halide. The term "consisting essentially of..." used in this manner means that the active substance of the metal precursor is greater than or equal to 95%, 98%, 99% or 99.5% of the specified substance. In some embodiments, the metal halide includes fluorine atoms or consists essentially of a group of fluorine atoms. In some embodiments, the metal halide comprises or consists essentially of chlorine atoms.

In some embodiments, the metal precursor comprises one or more of tungsten (W), molybdenum (Mo), or nickel (Ni). _In some embodiments, the metal precursor comprises or consists essentially of tungsten hexafluoride (WF ₆ ). In some embodiments, the metal precursor comprises or consists essentially of molybdenum (V) fluoride (MoF ₅ ). In _some embodiments, the metal precursor comprises or consists essentially of nickel (II) fluoride (NiF ₂ ) _. In some embodiments, the metal precursor comprises or consists essentially of one or more of tungsten hexafluoride, molybdenum pentafluoride, or nickel difluoride.

In one or more embodiments, the linear pulsed HFRF plasma is a conductively coupled plasma (CCP) or an inductively coupled plasma (ICP). In some embodiments, the linear pulsed HFRF plasma is a direct plasma or a remote plasma. In some embodiments, each of the plurality of linear HFRF pulses is independently generated at a linear power in the range of 500W to 1500W, or in the range of 600W to 1400W, or in the range of 700W to 1300W, or in the range of 800W to 1200W. In some embodiments, the minimum pad plasma power is greater than 500W. In some embodiments, all linear pulses have the same power. In some embodiments, the power of each pulse in the liner HFRF plasma is varied.

In one or more embodiments, the plurality of pad HFRF plasma pulses have a pad duty cycle of up to and including 99%. In some embodiments, a plurality of liner HFRF plasma pulses have a liner duty cycle in a range of 1% to 95%, 1% to 90%, 1% to 85%, 1% to 80%, 1% to 75%, 1% to 70%, 1% to 65%, 1% to 60%, 1% to 55%, 5% to 95%, 5% to 90%, 5% to 85%, 5% to 80%, 5% to 75%, 5% to 70%, 5% to 65%, 5% to 60%, 5% to 55%, 10% to 95%, 10% to 45%, 10% to 40%, 10% to 35%, 10% to 30%, 10% to 25%, 10% to 20%, or 10% to 15%. In some embodiments, each of the plasma pulses during the pad deposition process has the same duty cycle. In some embodiments, the duty cycle changes during the pad deposition process.

In one or more embodiments, each of the plurality of linear HFRF plasma pulses independently has a pulse width in the range of 5 ms to 50 μsec, 4 ms to 50 μsec, 3 ms to 50 μsec, 2 ms to 50 μsec, 1 ms to 50 μsec, 800 μsec to 50 μsec, 500 μsec to 50 μsec, 200 μsec to 50 μsec, 5 ms to 100 μsec, 4 ms to 100 μsec, 3 ms to 100 μsec, 2 ms to 100 μsec, 1 ms to 100 μsec, 800 μsec to 100 μsec, 500 μsec to 100 μsec, and 200 μsec to 100 μsec. In some embodiments, each of the pulse widths is the same during a deposition process. In some embodiments, the pulse width is varied during the deposition process.

In one or more embodiments, each of the plurality of linear HFRF plasma pulses independently has a linear pulse frequency in the range of 0.1 kHz to 20 kHz, 0.1 kHz to 15 kHz, 0.1 kHz to 10 kHz, 0.1 kHz to 5 kHz, 0.5 kHz to 20 kHz, 0.5 kHz to 15 kHz, 0.5 kHz to 10 kHz, 0.5 kHz to 5 kHz, 1 kHz to 20 kHz, 1 kHz to 15 kHz, 1 kHz to 10 kHz, 1 kHz to 8 kHz, 1 kHz to 5 kHz, 2 kHz to 20 kHz, 2 kHz to 15 kHz, 2 kHz to 10 kHz, or 2 kHz to 5 kHz. In some embodiments, the pulse frequency remains the same during the deposition process. In some embodiments, the pulse frequency is varied during the deposition process.

As part of the method 200, the liner formation process 215 occurs before the deposition process 220 and can occur at any suitable substrate temperature. The substrate temperature during the liner formation process 215 can be the same or different than the substrate temperature during the deposition process 220 or the etching 240.

In some embodiments, during the pad formation process 215, the substrate is maintained at a pad temperature in the range of 200°C to 550°C, 250°C to 525°C, 300°C to 500°C, 325°C to 475°C, or 350°C to 450°C.

In some embodiments, the liner formation process 215 includes a plasma enhanced chemical vapor deposition (CVD) process. In one or more embodiments, the liner formation process 215 includes flowing one or more of a carrier gas, a liner precursor, or a liner reactant onto the substrate surface. In some embodiments, the carrier gas includes, but is not limited to, argon (Ar), helium He, H ₂ , or N ₂ .

In one or more embodiments, each of the liner carrier gas, liner precursor gas, or liner reactant gas is independently flowed onto the substrate surface at a dosage in the range of 10 sccm to 500 sccm, 15 sccm to 350 sccm, 20 sccm to 200 sccm, 25 sccm to 150 sccm, or 50 sccm to 125 sccm.

In some embodiments, the pad formation process 215 produces a metal carbide film 470 having a tensile stress. In some embodiments, the tensile stress of the metal carbide film 470 is greater than or equal to 1 GPa, 1.25 GPa, 1.5 GPa, 1.75 GPa, or 2.0 GPa. The inventors have surprisingly discovered that the metal carbide film 470 formed using a pulsed HFRF plasma produces a film having a tensile stress, while typical metal carbide films formed by different processes have stresses ranging from low tensile stress (e.g., <1 GPa) to compressive stress (e.g., negative GPa).

After the liner formation process 215, some embodiments of the method 200 enter a cycle of film deposition 220, followed by a decision point 230 and an optional etching process 240 to form a flawless gap fill. As shown in FIG. 4B, in some embodiments, whether according to the method 200 or by a different method, a gap fill film 480 is formed in the feature 110 on the metal carbide liner 470.

In some embodiments, metal carbide liner 470 is removed from the top surface of the substrate, leaving metal carbide liner 470 on the sidewalls of feature 110. In some embodiments, metal carbide liner 470 is removed from the top surface of the substrate and the bottom surface of feature 110, leaving the metal carbide liner substantially only on the sidewalls of the feature.

According to one or more embodiments, the substrate 100 is processed before and/or after forming the layer. Such processing can be performed in the same chamber or in one or more separate processing chambers. In some embodiments, the substrate 100 is moved from a first chamber to a separate second chamber for further processing. The substrate 100 can be moved directly from the first chamber to the separate processing chamber, or it can be moved from the first chamber to one or more transfer chambers and then to the separate processing chamber. Thus, the processing equipment can include multiple chambers connected to a transfer station. This type of device can be referred to as a "cluster tool" or "cluster system" or the like.

Typically, a cluster tool is a modular system that includes multiple chambers that perform various functions, including substrate centering and orientation, degassing, annealing, deposition 220, and/or etching 240. According to one or more embodiments, the cluster tool includes at least a first chamber and a central transfer chamber. The central transfer chamber can accommodate a robot that can shuttle substrates between and among the processing chambers and the load gate chamber. The transfer chamber is typically maintained under vacuum conditions and provides an intermediate stage for shuttling substrates from one chamber to another and/or to a load gate chamber positioned at the front end of the cluster tool. Two well-known cluster tools that may be suitable for use in the present case are Centura® and Endura®, both available from Applied Materials, Inc. of Santa Clara, California. The embodiments described herein may also be performed using other suitable systems. Other suitable systems include, but are not limited to, Producer®, Producer® XP Precision, or their equivalents. However, the exact arrangement and combination of chambers may be varied to perform specific steps of the methods described herein. Other processing chambers that may be used include, but are not limited to, cyclic layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, pre-cleaning, chemical cleaning, thermal treatment (such as RTP), plasma nitridation, degassing, orientation, hydroxylation, and other substrate processes. By performing the processes in chambers on a cluster tool, surface contamination of the substrate by atmospheric impurities can be avoided without oxidation occurring prior to deposition of subsequent films.

According to one or more embodiments, the substrate 100 is continuously under vacuum or "load gate" conditions and is not exposed to ambient air when moving from one chamber to the next. Thus, the transfer chamber is under vacuum that is "pumped" under vacuum pressure. An inert gas may be present in the processing chamber or the transfer chamber. In some embodiments, the inert gas is used as a purge gas to remove some or all of the reactants. According to one or more embodiments, the purge gas is injected at the outlet of the deposition chamber to prevent reactants from moving from the deposition chamber to the transfer chamber and/or additional processing chambers. Thus, the inert gas flow forms a curtain at the outlet of the chamber.

Substrates may be processed in a single substrate deposition chamber where a single substrate is loaded, processed, and unloaded prior to processing another substrate. Similar to a conveyor system, substrates may also be processed in a serial manner where multiple substrates are individually loaded into a first portion of the chamber, moved through the chamber, and unloaded from a second portion of the chamber. The shape of the chamber and associated conveyor system may form a straight path or a curved path. Additionally, the processing chamber may be a turntable where multiple substrates are moved about a central axis and exposed to deposition, etching, annealing, cleaning, etc. processes throughout the turntable path.

During processing, the substrate 100 may be heated or cooled. Such heating or cooling may be achieved by any suitable means, including but not limited to changing the temperature of the substrate support and flowing a heated or cooled gas to the substrate surface. In some embodiments, the substrate support includes a heater/cooler that can be controlled to conductively change the substrate temperature. In one or more embodiments, the gas (reactive gas or inert gas) is heated or cooled to locally change the substrate temperature. In some embodiments, the heater/cooler is positioned in a chamber adjacent to the substrate surface to convectively change the substrate temperature.

The substrate may also be stationary or rotated during processing. Rotating the substrate may be done continuously or in discrete steps. For example, the substrate may be rotated throughout the process, or the substrate may be rotated a small amount between exposures to different reactant gases or purge gases. Rotating the substrate during processing (continuously or in steps) can help produce a more uniform deposition or etch by minimizing the effects of local variability in, for example, gas flow geometry.

References throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment" 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 invention. Therefore, phrases such as "in one or more embodiments," "in certain embodiments," "in an embodiment," or "in an embodiment" appearing in various places throughout this specification do not necessarily refer to the same embodiment of the present invention. Furthermore, in one or more embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner.

Although the disclosure herein has been described with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the disclosure. It will be apparent to those skilled in the art that various modifications and variations may be made to the methods and apparatus of the disclosure without departing from the spirit and scope of the disclosure. Therefore, the disclosure is intended to include modifications and variations within the scope of the appended claims and their equivalents.

100: substrate 110: feature 112: bottom surface 114: first sidewall 116: second sidewall 120: substrate surface 200: method 210: substrate pretreatment 215: pad formation process 220: deposition process 230: decision point 240: etching process 260: post-processing 300: electronic device 350: first surface 360: second surface 370: film 372: bottom 374: top 376: sidewall 382: bottom film 384: top film 470: metal carbide film 472: bottom surface 474: top surface 476: Side wall surface 480: Gap filling film

In order to be able to understand the above-mentioned features of the present invention in detail, the present invention briefly summarized above can be described in more detail by reference to embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings only illustrate typical embodiments and therefore should not be considered to limit its scope, because the present invention may allow other equally effective embodiments.

FIG. 1 illustrates a cross-sectional view of a substrate feature according to one or more embodiments of the present disclosure; and

FIG. 2 illustrates a process flow according to one or more embodiments of the present invention.

3A-3D illustrate schematic cross-sectional representations of gapfill processes according to one or more embodiments of the present disclosure.

4A-4B illustrate schematic cross-sectional representations of a metal carbide pad formation process according to one or more embodiments of the present disclosure.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

300: Electronic devices

350: First surface

360: Second surface

470:Metal carbide film

480: Gap filling film

Claims (20)

A method of gap filling, the method comprising the following steps: Exposing a substrate having a substrate surface to a deposition process, the deposition process comprising a pulsed high frequency radio frequency (HFRF) plasma having a plurality of HFRF pulses for depositing a pad, the substrate surface having a plurality of features formed in the substrate surface, each of the plurality of features extending a distance from the substrate surface into the substrate and having a bottom and at least one sidewall, the pad comprising a metal carbide. The method of claim 1, wherein the pad has a tensile stress greater than or equal to 1.5 GPa. The method of claim 1, wherein each of the plurality of HFRF pulses independently has a pulse frequency in a range of 1 kHz to 8 kHz. The method of claim 1, wherein each of the plurality of HFRF pulses is independently generated at a power in a range of 500W to 1500W. The method of claim 1, wherein the plurality of HFRF pulses have a duty cycle of up to and including 99%. The method of claim 1, wherein each HFRF pulse has a pulse width in a range of 1 millisecond to 100 microseconds. The method of claim 1, wherein the deposition process comprises a plasma enhanced chemical vapor deposition (PECVD) process, wherein the PECVD comprises flowing a metal precursor onto the substrate surface at a dose in a range of 20 sccm to 200 sccm. The method of claim 1, further comprising the step of filling the feature with a second material to cover the pad. The method of claim 8, wherein the second material comprises amorphous silicon (a-Si). A method as claimed in claim 1, wherein the pad has a thickness that varies within a range of 25% to 75% relative to an average thickness of the pad. A method as claimed in claim 1, wherein the substrate is maintained at a pad temperature in the range of 300°C to 500°C. The method of claim 1, wherein the deposition process is performed at a pressure in a range of 1 Torr to 10 Torr. The method of claim 1, wherein the pad has a conformality in the range of 40% to 70%. The method of claim 1, wherein the metal carbide film comprises tungsten carbide. The method of claim 14, wherein the deposition process includes a metal precursor comprising tungsten hexafluoride (WF ₆ ). A method of forming a pad using HFRF, the method comprising the steps of: Forming a metal carbide pad on the sidewalls of a plurality of features formed in a substrate surface, each feature extending a certain distance from the substrate surface into a substrate and having at least one sidewall, the step of forming the pad comprising the steps of: exposing the substrate to a chemical vapor deposition process with a plurality of pad HFRF pulses. A method as in claim 16, wherein forming the metal carbide pad comprises exposing the substrate to a metal precursor comprising tungsten hexafluoride under the following conditions: a flow rate in the range of 20 sccm to 200 sccm, a temperature in the range of 300°C to 500°C, the plurality of pad HFRF pulses having a gapfill pulse frequency in the range of 1 kHz to 8 kHz, and a gapfill duty cycle up to and including 99% at a gapfill power in the range of 500 W to 1500 W. The method of claim 16, further comprising the step of filling the feature including the metal carbide pad with a second material by a gap-fill deposition process. The method of claim 18, wherein the gapfill deposition process comprises repeatedly depositing a non-conformal film in the feature and etching a portion of the non-conformal film, depositing the non-conformal film comprises a plurality of gapfill HFRF pulses, the plurality of gapfill HFRF pulses having a gapfill pulse frequency in a range of 1 kHz to 10 kHz at a gapfill RF frequency in a range of 5 MHz to 15 MHz and a power level in a range of 50 W to 500 W. The method further comprises: etching the non-conformal film by exposing the non-conformal film to an etching plasma, the etching plasma comprising a plurality of etching HFRF pulses having an etching pulse frequency in a range of 1 kHz to 10 kHz at an etching RF frequency in a range of 5 MHz to 15 MHz and a power in a range of 100 W to 300 W. An etching duty cycle in a range of 1% to 20% at an etching power in a range of W, wherein each of the etching HFRF pulses has an etching pulse width in a range of 1 millisecond to 100 microseconds. A method for forming a pad in a semiconductor device, the method comprising the following steps: Forming a metal carbide pad on the sidewalls of a plurality of features formed in a substrate surface, each feature extending a certain distance from the substrate surface into a substrate and having at least one sidewall, the step of forming the metal carbide pad comprising the following steps: exposing the substrate to a chemical vapor deposition process using one or more of a tungsten-containing precursor, a molybdenum-containing precursor, or a nickel-containing precursor and a plurality of pad HFRF pulses to form a metal carbide pad having a tensile stress.

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