WO2017049253A1

WO2017049253A1 - Methods for depositing conformal bcn films

Info

Publication number: WO2017049253A1
Application number: PCT/US2016/052386
Authority: WO
Inventors: Rui CHENG; Abhijit Basu Mallick
Original assignee: Applied Materials, Inc.
Priority date: 2015-09-18
Filing date: 2016-09-17
Publication date: 2017-03-23
Also published as: KR102615728B1; CN108028179A; CN117165927A; KR20180043393A

Abstract

Methods for forming a borocarbide film on a substrate surface by exposing the substrate surface to a borane precursor. The borocarbide film optionally comprising nitrogen and/or hydrogen. The borocarbide film can be deposited onto a surface that comprises substantially no boron. The borane precursor can include compound having the general formula NHR₂BH₃, where each R is independently selected from the group consisting of hydrogen, C1-C10 alkyl groups, C1-C10 alkenyl groups and aryl groups.

Description

METHODS FOR DEPOSITING CONFORMAL BCN FILMS

FIELD

[0001] Embodiments of the disclosure generally relate to methods of forming borocarbide films. More particularly, embodiments of the disclosure relate to methods of forming borocarbide, borocarbonitride and/or boronitride films.

BACKGROUND

[0002] As a result of strong covalent bonding, the elements: boron, carbon and nitrogen can form B-C-N materials with many useful properties. For example, materials can be formed with high hardness, high temperature stability, increased reactive ion etching (RIE) selectivity and/or increased solvent etchant resistivity. Efforts have been focused on diamond-like carbon (DLC), boron carbide and boron nitride films. There have also been investigations focused on ternary compounds such as BCN.

[0003] The conventional processes use high temperature chemical vapor deposition (CVD) at temperatures greater than about 550^QC or plasma enhanced CVD. However, high temperature limits the application of such films and plasma processing reduces the conformality of the film due to the distribution of the plasma.

[0004] Therefore, there is a need in the art for methods of forming films at low temperatures with good conformality and etch selectivity. SUMMARY

[0005] One or more embodiments of the disclosure are directed to processing methods comprising exposing a substrate surface comprising substantially no boron to a borane precursor in a processing chamber at a temperature in the range of about 300^QC to about 550^QC to form a borocarbide film.

[0006] Additional embodiments of the disclosure are directed to processing methods comprising positioning a substrate having a surface in a processing chamber. The surface of the substrate is exposed to a borane precursor at a temperature in the range of about 300^QC to about 550^QC to form a borocarbide film. The borane precursor comprises a compound with the general formula NHR₂BH₃, where each R is independently selected from the group consisting of hydrogen, C1 - C10 alkyl groups, C1 -C10 alkenyl groups and aryl groups with the proviso that at least one of the R groups comprises a carbon atom.

[0007] Further embodiments of the disclosure are directed to processing methods comprising positioning a substrate having a surface comprising substantially no boron in a processing chamber. The surface has at least one feature thereon. The surface of the substrate is exposed to a borane precursor and an optional co-reactant at a temperature in the range of about 300^QC to about 550^QC to form a conformal hardmask comprising a borocarbide film on the at least one feature. The borane precursor comprises NH(CH₃)₂BH₃. The co-reactant is selected from the group consisting of hydrogen, B₂H₆, CH₄, C₂H₂, C₃H₆, NH₃ and combinations thereof.

DETAILED DESCRIPTION

[0008] As used in this specification and the appended claims, the term "substrate" and "wafer" are used interchangeably, both referring to a surface, or portion of a surface, upon which a process acts. It will also be understood by those skilled in the art that reference to a substrate can also refer to only a portion of the substrate, unless the context clearly indicates otherwise.

[0009] Reference throughout this specification to "one embodiment," "certain embodiments," "various embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment may be included in at least one embodiment of the disclosure. Furthermore, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. In addition, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0010] As used in this specification and the appended claims, the terms "substrate" and "wafer" are used interchangeably, both referring to a thin piece of material having a surface, or portion of a surface, upon which a process acts. It will also be understood by those skilled in the art that reference to a substrate can also refer to only a portion of the substrate, unless the context clearly indicates otherwise. Additionally, reference to depositing on a substrate can mean both a bare substrate and a substrate with one or more films or features deposited or formed thereon.

[0011] A "substrate surface" as used herein, refers to an exposed face of any substrate or material surface formed on a substrate upon which film processing is performed during a fabrication process. For example, a substrate surface on which processing can be performed include materials such as silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon doped silicon oxides, silicon nitride, silicon carbide, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal carbides, metal alloys, and other conductive materials, depending on the application. Substrates include, without limitation, semiconductor and insulating wafers, which may or may not have been further processed to produce electronic and/or optoelectronic devices. Substrates may be exposed to a pretreatment process to clean, polish, etch, reduce, oxidize, hydroxylate, anneal and/or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, in the embodiments of the present disclosure any of the film processing steps disclosed may also be performed on an underlayer formed on the substrate as disclosed in more detail below, and the term "substrate surface" is predetermined to include such underlayer(s) as the context indicates, for example vias passing through thin semiconducting and/or insulating layers on an SOI wafer.

[0012] Substrates for use with the embodiments of the disclosure can be any suitable substrate. In some embodiments, the substrate is a rigid, discrete, generally planar substrate. As used in this specification and the appended claims, the term "discrete" when referring to a substrate means that the substrate has a fixed dimension. The substrate of one or more embodiments is a semiconductor substrate, such as a 200 mm or 300 mm diameter silicon substrate. In some embodiments, the substrate is one or more of silicon, silicon germanium, gallium arsenide, gallium nitride, germanium, gallium phosphide, indium phosphide, sapphire and silicon carbide. [0013] Some embodiments of the disclosure advantageously provide methods of forming a borocarbide film on a substrate surface without a boron containing underlayer. In some embodiments, the substrate surface comprises substantially no boron. As used in this regard, the term "substantially no boron" means that there is less than about 1 % on an atomic basis of boron atoms on to the surface to a depth of about 10 A. In some embodiments, the substrate surface consists essentially of silicon, carbon and oxygen atoms. As used in this regard, the term "consists essentially of silicon carbon and oxygen atoms" means that the substrate surface, to a depth of about 10 A, comprises greater than or equal to about 99% silicon, carbon and oxygen atoms, in total. In some embodiments, the substrate surface consists essentially of silicon, carbon, hydrogen and oxygen atoms. As used in this regard, the term "consists essentially of silicon, carbon, hydrogen and oxygen atoms" means that the substrate surface, to a depth of about 10 A, comprises greater than or equal to about 99% silicon, carbon, hydrogen and oxygen atoms, in total.

[0014] Embodiments of the disclosure are directed to processes to deposit borocarbide, borocarbonitride and similar films. Some embodiments of the disclosure provide films that are formed at relatively low temperatures, allowing preservation of the thermal budget during device formation. Some embodiments of the disclosure provide films with excellent conformality greater than or equal to about 98%.

[0015] Some embodiments of the disclosure are directed to processing methods in which a substrate surface is exposed to a borane precursor at low temperature to form a borocarbide film. As used in this specification and the appended claims, the term "borocarbide" refers to a film comprising boron and carbon. In some embodiments, the borocarbide film consists essentially of boron and carbon, meaning that boron and carbon make up at least about 80 atomic % of the film. The borocarbide film can comprise nitrogen and/or hydrogen. In some embodiments, the borocarbide film consists essentially of boron, carbon and optionally, hydrogen atoms.

[0016] In some embodiments, the borocarbide film is a borocarbonitride film. As used in this specification and the appended claims, the term "borocarbonitride" refers to a film comprising boron, carbon and nitrogen. In some embodiments, the borocarbonitride film consists essentially of boron, carbon and nitrogen, meaning that boron, carbon and nitrogen make up at least about 80 atomic % of the film. In some embodiments, the borocarbonitride film consists essentially of boron, carbon, nitrogen, and optionally, hydrogen atoms.

[0017] In some embodiments, the borocarbide film comprises hydrogen in addition to boron, carbon and, optionally, nitrogen. The hydrogen content of the film can be up to about 20 atomic %, 15 atomic %, 10 atomic %, 5 atomic % or 2 atomic %.

[0018] The borane precursor can comprise any suitable borane compounds that can decompose at a temperature less than about 550^QC. In some embodiments, the borane precursor comprises a compound with the general formula NHR₂BH₃. In some embodiments, each R group is independently selected from the group consisting of hydrogen, C1 -C10 alkyl groups, C1 -C1 0 alkenyl groups and aryl groups. In one or more embodiments, at least one of the R groups comprises a carbon atom. In some embodiments, the borane precursor comprises NH(CH₃)₂BH₃. In one or more embodiments, the borane precursor comprises a compound of the general formula NHR₂BH₃, where each R group is independently selected from the group consisting of C1 -C10 alkyl groups, C1 -C10 akenyl groups and aryl groups so that there is one hydrogen atom bonded to the nitrogen atom. In some embodiments, the borane precursor has a general formula of NH₂RBH₃, where R is selected from the group consisting of C1 -C10 alkyl, C1 -C10 alkenyl and aryl groups so that there are two hydrogen atoms bonded to the nitrogen atom.

[0019] In some embodiments, the temperature at which the borocarbide film is formed in the range of about 300^QC to about 550^QC to form a borocarbide film. In one or more embodiments, the temperature at which the borocarbide film forms is less than or equal to about 550^QC, or less than or equal to about 525^QC, or less than or equal to about 500^QC, or less than or equal to about 475^QC, or less than or equal to about 450^QC, or less than or equal to about 425^QC, or less than or equal to about 400^QC.

[0020] In use, a substrate is positioned within a processing chamber and the borane precursor is flowed into the processing chamber to react with the substrate surface. In some embodiments, the borane precursor is flowed into the processing chamber with or without a carrier gas. As used in this regard, a carrier gas is a gas that does not react with either the borane precursor or the substrate surface.

[0021] The borocarbide film of some embodiments forms by thermal decomposition of the borane precursor. In one or more embodiments, the temperature of the substrate surface is elevated and a relatively cool borane precursor is flowed into the processing chamber. The borane precursor decomposes on the relatively hot substrate surface to form the borocarbide film. In one or more embodiments, the thermal decomposition occurs without a catalyst or plasma enhancement.

[0022] In some embodiments, the borane precursor is flowed into the processing chamber with a co-reactant. The co-reactant is selected from the group consisting of hydrogen, B₂H₆, CH₄, C₂H₂, C₃H₆, NH₃ and combinations thereof. In some embodiments, the co-reactant increases the atomic percentage of one or more of boron, carbon, nitrogen or hydrogen in the borocarbide film. The co-reactant can be mixed with the borane precursor before flowing into the processing chamber or mixed with the borane precursor within the processing chamber.

[0023] In some embodiments, the borane precursor is exposed to a plasma in processing chamber to form the borocarbide film. The plasma can be a direct plasma which is ignited within the processing chamber immediately adjacent the substrate surface or can be a remote plasma which is ignited outside of the processing chamber and flowed into the processing region adjacent the substrate surface. In some embodiments, the plasma comprises one or more of hydrogen, nitrogen, helium or argon. In some embodiments, the borocarbide film is formed conformally on the substrate surface without a plasma.

[0024] The borocarbide film formed by one or more embodiments of the disclosure are substantially uniform in composition throughout the thickness of the film. As used in this regard, the term substantially uniform means that the atomic composition of the film near the top of the film is about the same as the atomic composition of the film near the bottom of the film and in between. Those skilled in the art will understand that the interface between the substrate surface and the borocarbide film and the interface beween the borocarbide film and any component on top of the film may have slightly different compositions than the bulk portion of the film due to, for example, atomic migration.

[0025] In some embodiments, the substrate surface comprises at least one feature thereon. A "feature" as used in this specification and the appended claims, refers to any non-flat portions of a substrate. For example, a feature can be a trench or a peak. Features generally include at least one "vertical" surface and either a top or bottom "horizontal" surface. A vertical surface is one that extends at an angle to the substrate surface in the range of about 70^Q to about 1 10^Q, with a surface normal measured at 90^Q. A horizontal surface is one that extends at an angle to the normal of the substrate in the range of about 0^Q to about 20^Q.

[0026] In one or more embodiments, the borocarbide film forms conformally on at least one feature. As used herein, the term "conformal", or "conformally", refers to a layer that adheres to and uniformly covers exposed surfaces with a thickness having a variation of less than 1 % relative to the average thickness of the film. For example, a 1 ,000 A thick film would have less than 1 0 A variations in thickness. This thickness and variation includes edges, corners, sides, and the bottom of recesses. For example, a conformal layer deposited by ALD in various embodiments of the disclosure would provide coverage over the deposited region of essentially uniform thickness on complex surfaces.

[0027] As used herein, the term "continuous" refers to a layer that covers an entire exposed surface without gaps or bare spots that reveal material underlying the deposited layer. A continuous layer may have gaps or bare spots with a surface area less than about 1 % of the total surface area of the film.

[0028] The borocarbide film of some embodiments is substantially transparent to light at a predetermined wavelength. As used in this specification and the appended claims, the term "substantially transparent" means that the film absorbs less than about 1 0% or 5% of light at the predetermined wavelength. The predetermined wavelength can be any suitable wavelength of light that is used to interact with any film formed beneath the borocarbide film.

[0029] In some embodiments, the borocarbide film is formed as a hardmask and is resistant to etching. As used in this specification and the appended claims, the term "resistant to etching" means that the film has an SiO or a-Si dry etch selectivity by reactive ion etch (RIE) of greater than 100 or a wet etch rate in dilute HF of less than about 2 A/min.

[0030] In some embodiments, the method further comprises irradiating the substrate surface through the borocarbide film using light of a wavelength to which the borocarbide film is substantially transparent. In one or more embodiments, the method further comprises removing the hardmask after irradiating the substrate surface beneath the borocarbide film.

[0031] Examples

[0032] Borocarbonitride (B-C-N) films were deposited by thermal CVD process using dimethylamine borane [NH(CH₃)₂BH₃] (DMAB). The DMAB was heated in a hot can to increase the vapor pressure and was delivered to a processing chamber using ultrahigh purity (UHP) Ar carrier gas. The hot can temperature ranged from room temperature to about 150^QC. The Ar carrier gas flow ranged from 100 seem to 20000 seem. To control the elemental composition of the B-C-N film, NH₃, H₂, C₃H₆ co- reactant gases were delivered to the CVD chamber. The chamber temperature ranged from 300^QC to 550^QC. The processing chamber pressure ranged from 100 mTorr to 100 Torr. The B-C-N film was deposited on a silicon wafer.

[0033] The film properties of the B-C-N film were characterized by ellipsometer, XPS and/or RBS/HFS. The Rl/633nm of the film was 2.2 and K/633nm was 0.0087. The composition analysis shows that the boron concentration ranged from 35% to 60% on an atomic basis. The carbon concentration ranged from 8% to 37% on an atomic basis. The nitrogen concentration ranged from 9% to 42% on an atomic basis. FTIR spectrum of the borocarbonitride film showed B-B, B-C, B-N, B-H bonds were in the film.

[0034] Without being bound by any particular theory of operation, it is believed that the DMAB decomposes on the substrate wafer first and generates BH₃ and DMA. The BH₃ reacts with Si and forms Si-B bonds. The remaining B-H bonds react with B, C, and N-species and form B-B, B-C and C-N bonds. Table 1 lists the etching ratio for a layer below the hardmask, normalized to the etch rate of the hard mask. Table 1 .

Film Relative Etch Rate

Carbon Hard Mask 1 .00

SiO 1 .91

SiN 2.31

a-Si 2.80

SiB 3.1 5

[0035] It can be seen from Table 1 that the relative etch rate of the silicon boride film is greater than the relative etch rates of amorphous silicon, silicon oxide or silicon nitride films.

[0036] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:

1 . A processing method comprising exposing a substrate surface to a borane precursor in a processing chamber at a temperature in the range of about 300^QC to about 550^QC to form a borocarbide film, wherein the substrate surface comprises substantially no boron.

2. A processing method comprising:

positioning a substrate having a surface in a processing chamber;

exposing the surface of the substrate to a borane precursor at a temperature in the range of about 300^QC to about 550^QC to form a borocarbide film, the borane precursor comprising a compound with the general formula NHR₂BH₃, where each R is independently selected from the group consisting of hydrogen, C1 -C1 0 alkyl groups, C1 -C10 alkenyl groups and aryl groups with the proviso that at least one of the R groups comprises a carbon atom.

3. The processing method of claim 1 , wherein the borane precursor comprises a compound with the general formula NHR₂BH₃, where each R is independently selected from the group consisting of hydrogen, C1 -C10 alkyl groups, C1 -C10 alkenyl groups and aryl groups.

4. The processing method of claim 3, wherein at least one of the R groups comprises a carbon atom.

5. The processing method of any of claims 1 to 4, wherein the borocarbide film consists essentially of boron, carbon and optionally, hydrogen atoms.

6. The processing method of any of claims 1 to 4, wherein the borane precursor comprises NH(CH₃)₂BH₃.

7. The processing method of claim 6, wherein the borocarbide film consists essentially of boron, carbon, nitrogen and optionally, hydrogen atoms.

8. The processing method of any of claims 1 to 4, wherein the borane precursor is co-flowed into the processing chamber with a co-reactant, the co-reactant selected from the group consisting of hydrogen, B₂H₆, CH₄, C₂H₂, C₃H₆, NH₃ and combinations thereof.

9. The processing method of claim 8, wherein the co-reactant increases an atomic percentage of one or more of hydrogen, carbon or nitrogen in the borocarbide film.

10. The processing method of any of claims 1 to 4, wherein the borane precursor is exposed to a plasma in processing chamber to form the borocarbide film, the plasma comprises one or more of hydrogen, nitrogen, helium or argon.

1 1 . The processing method of any of claims 1 to 4, wherein the substrate surface comprises silicon.

12. The processing method of any of claims 1 to 4, wherein the substrate surface comprises at least one feature thereon and the borocarbide film forms conformally on the at least one feature.

13. The processing method of any of claims 1 to 4, wherein the borocarbide film is substantially transparent to light at a predetermined wavelength.

14. The processing method of claim 13, wherein the borocarbide film is formed as a hardmask and is resistant to etching and the method further comprises irradiating the substrate surface through the borocarbide film using light of the predetermined wavelength, and removing the hardmask.

15. A processing method comprising:

positioning a substrate having a surface in a processing chamber, the surface having at least one feature thereon and comprises substantially no boron;

exposing the surface of the substrate to a borane precursor and an optional co-reactant at a temperature in the range of about 300^QC to about 550^QC to form a conformal hardmask comprising a borocarbide film on the at least one feature, the borane precursor comprising NH(CH₃)₂BH_3! the co- reactant selected from the group consisting of hydrogen, B₂H₆, CH₄, C₂H₂, C₃H₆, NH₃ and combinations thereof.