DIAMOND-LIKE CARBON COATINGS AND METHODS OF MAKING THE SAME

In accordance with some embodiments of the present disclosure, a diamond-like carbon coating is provided. The diamond-like carbon coating may include a substrate and a diamond-like carbon film formed on the substrate. The diamond-like carbon film may include a plurality of layers of diamond-like carbon. A first layer of diamond-like carbon in the diamond-like carbon film is softer than a second layer of diamond-like carbon in the diamond-like carbon film. In some embodiments, the diamond-like carbon coating may further include a barrier layer and/or a UV protection layer formed between the substrate and the diamond-like carbon film. In some embodiments, the diamond-like carbon coating may further include a hydrophobic layer formed on the diamond-like carbon film. The diamond-like carbon coating is optically transparent.

TECHNICAL FIELD

The implementations of the disclosure relate generally to forming coatings on substrates and, more specifically, to diamond-like carbon coatings and methods of making the same.

BACKGROUND

Diamond-like carbon (DLC) may refer to amorphous carbon materials that may display certain typical properties of diamond. DLC may include sp2and sp3bonds of carbon atoms. DLC may be applied as coatings to other materials to achieve desirable optical or mechanical properties, such as high hardness, high wear resistance, or desired durability. However, existing DLC coatings may have limited applications due to conflicts among the optical and mechanical properties. For example, existing DLC coatings of high hardness typically present high compressive stress and are not suitable for high wear resistance applications due to their limited film thicknesses. As another example, optical durability applications typically require films of a certain thickness (e.g., a thickness of 1-10 micrometers). However, existing DLC coatings of such thickness may be brown or black and are thus not suitable for such optical durability applications. As a further example, existing DLC coatings with high hardness may be electrically insulated.

SUMMARY

In accordance with some embodiments of the present disclosure, a substrate and a diamond-like carbon film formed on the substrate. The diamond-like carbon film includes a plurality of layers of diamond-like carbon that includes a first layer of diamond-like carbon and a second layer of diamond-like carbon. The first layer of diamond-like carbon is softer than the second layer of diamond-like carbon.

The diamond-like carbon coating is optically transparent.

In some embodiments, the diamond-like carbon coating further includes a barrier layer formed on the substrate. The barrier layer is positioned between the substrate and the diamond-like carbon film. In some embodiments, the barrier layer includes at least one of SiO2or Al2O3. In some embodiments, the barrier layer is optically transparent.

In some embodiments, the barrier layer includes a first layer of SiOxCyand a second layer of SiOxCy, and wherein the first layer of SiOxCyis softer than the second layer of SiOxCy.

In some embodiments, the diamond-like carbon coating further includes an ultraviolet (UV) protection layer formed on the substrate. In some embodiments, the UV protection layer is electrically conductive.

In some embodiments, the UV protection layer is positioned between the substrate layer and the diamond-like carbon film.

In some embodiments, the UV protection layer is positioned between the barrier layer and the diamond-like carbon film.

In some embodiments, the UV protection layer comprises a crystalline layer of at least of one of ZnO, Al-doped ZnO, or TiO2.

In some embodiments, the UV protection layer includes a transition layer positioned between the UV blocking layer and the diamond-like carbon film.

In some embodiments, the diamond-like carbon coating further includes a hydrophobic layer formed on the diamond-like carbon film.

In accordance with one or more aspects of the present disclosure, methods for fabricating a diamond-like carbon coating are provided. The methods include forming, on a substrate, a diamond-like carbon film on the substrate. Forming the diamond-like carbon film includes forming a plurality of layers of diamond-like carbon, wherein the plurality of layers of diamond-like carbon materials comprises a first layer of diamond-like carbon materials and a second layer of diamond-like carbon materials, wherein the first layer of diamond-like carbon materials is softer than the second layer of diamond-like carbon materials, and wherein the diamond-like carbon coating is optically transparent.

In some embodiments, forming the plurality of layers of diamond-like carbon includes depositing an initial layer of DLC; etching the initial layer of DLC to produce an etched initial layer of DLC; and depositing a subsequent layer of DLC on the etched initial layer of DLC.

In some embodiments, the methods further include forming a barrier layer on the substrate, wherein forming the barrier layer includes depositing a layer of at least one of SiO2, Al2O3, or SiOxCy.

In some embodiments, forming the barrier layer includes forming a first layer of SiOxCyand a second layer of SiOxCy, and wherein the first layer of SiOxCyis softer than the second layer of SiOxCy.

In some embodiments, the methods further include forming an ultraviolet (UV) protection layer on the substrate, wherein the UV protection layer is electrically conductive.

In some embodiments, forming the UV protection layer includes forming a crystalline layer of at least of one of ZnO, Al-doped ZnO, or TiO2.

In some embodiments, forming the UV protection layer includes forming a transition layer positioned on the UV blocking layer.

In some embodiments, the methods further include growing the diamond-like carbon coating to a thickness greater than 100 nm.

In some embodiments, the methods further include growing the diamond-like carbon coating to a thickness of the diamond-like carbon coating is greater than 1 micrometer.

In some embodiments, the methods further include forming a hydrophobic layer formed on the diamond-like carbon film.

DETAILED DESCRIPTION

Aspects of the disclosure provide for diamond-like carbon coatings and mechanisms for making the diamond-like carbon coatings. As referred to herein, diamond-like carbon (DLC) materials may refer to amorphous carbon materials that may display certain typical properties of diamond. DLC materials may include sp2and sp3bonds of carbon atoms.

The DLC coatings fabricated in accordance with the present disclosure may present multiple desired optical properties and/or mechanical properties, such as electrical conductivity, ultraviolet (UV) protection capacity, optical transparency, mechanical durability, anti-smudge capability, etc. In some embodiments, the hardness of a DLC coating fabricated in accordance with the present disclosure may be about 7H-9H measured using a pencil hardness test. In some embodiments, the hardness of a DLC coating fabricated in accordance with the present disclosure may be about 10-20 GPa measured using a nano-indentation test method. In some embodiments, a thickness of the DLC coating may be between about 2 nm and about 2000 nm.

The DLC coatings may have any suitable thickness without compromising their optical and/or mechanical properties. The DLC coatings may be used to implement various applications, such as display overcoats, screen protectors for mobile phones or other computing devices, eyeglasses, window coatings with defroster capability, decorative glass, building glass, etc.

In some embodiments, a DLC coating may include a substrate and a DLC film. The DLC film may include multiple DLC layers of varying hardness. For example, the DLC film may include one or more soft DLC layers and one or more hard DLC layers alternatively stacked on each other. The soft DLC layer(s) may neutralize mechanical stress and prevent delamination. The DLC film may be optically transparent. In some embodiments, the DLC film with an optical transmission rate of about or greater than90% for visible light may be regarded as being optically transparent.

In some embodiments, the DLC coating may further include a hydrophobic layer formed on the DLC film. The hydrophobic layer may be and/or include, for example, an anti-smudge coating formed on a surface of the DLC film.

In some embodiments, a barrier layer may be formed between the substrate and the DLC film. The barrier layer may serve as a moisture barrier for the DLC coating and/or enhance adherence between the substrate and layers formed on the substrate (e.g., the DLC film). In some embodiments, the barrier layer may include one or more layers of SiO2, A12O3, SiOxCy, etc.

In some embodiments, a UV protection layer may be formed between the substrate and the DLC film. The UV protection layer may include one or more layers of one or more suitable materials that may prevent the substrate from UV damage, such as ZnO, Al-doped ZnO, TiO2, etc. The UV protection layer may be optically transparent and electrically conductive. In one implementation, the UV protection layer may be formed on the barrier layer. In another implementation, the DLC coating does not include the barrier layer. In such implementation, the UV protection layer may be formed directly on the substrate.

As will be discussed in greater detail below, one or more components of the DLC coating may be omitted or modified to implement various applications and/or to achieve DLC coatings of various desired optical and mechanical properties. A DLC film is typically a hard compressive film. The desirable properties of DLC may be realized due to numerous types of mismatch between substrates and DLC at the bottom, such as stress mismatch, thermal expansion mismatch, chemical bonding mismatch. The desirable DLC properties may be utilized by multi-layers stress cancellation and hardness gradient. For example, hydrophobicity or lipophobicity may be achieved by making the surface of the DLC coating completely passivated and thus nonstick.

An existing screen protector typically includes a tempered glass of a certain thickness to achieve desired hardness (e.g.,9H in the pencil scale). Such tempered glass screen protector may easily crack if the surface or a top portion of the tempered glass cracks, resulting in damages to the screen below the tempered glass. A DLC coating in accordance with the present disclosure may be fabricated on a flexible substrate (e.g., a plastic substrate) while presenting high hardness. As such, any hard impact on the surface of the DLC coating will not crack through the DLC coating. The DLC coating may be used as a durable screen protector.

FIGS. 1A, 1B, 2A, 2B, 2C, 2D, 3A, 3B, and 3Cillustrate structures associated with processes for fabricating diamond-like carbon (DLC) coatings in accordance with some embodiments of the present disclosure.

Turning toFIG. 1A, a substrate110may be provided. Substrate110may include any suitable material that can provide a desirable original pattern, color, and/or layout of circuitry to be seen through for the DLC coating to be fabricated. For example, substrate110may include one or more plastic materials, glass, wood, textiles, semiconductor materials (e.g., silicon), smart windows, displays (e.g., OLED displays), etc.

A DLC film150may be formed on substrate110to form a DLC coating100A. DLC film150may be optically transparent (e.g., with an optical transmission rate of about or greater than 96% for visible light). In some embodiments, DLC film150may present an optical transmission rate of about 90%-99% for visible light. In some embodiments, a DLC film with an optical transmission rate of about or greater than 90% for visible light may be regarded as being optically transparent. DLC film150may include a multi-layer DLC structure including a plurality of DLC layers. Each of the DLC layers may include a layer of one or more amorphous carbon materials with sp2and sp3bonds of carbon atoms. The DLC layers may have various hardness. For example, DLC film150may include one or more soft DLC layers151a-151zand one or more hard DLC layers153a-153zalternatively stacked on each other. As such, soft DLC layers151a-151zand hard DLC layers153a-153zform a plurality of pairs of a soft DLC layer and a hard DLC layer, wherein the hard DLC layer has higher hardness than the soft DLC layer. More particularly, for example, DLC film150may include a pair of a soft DLC layer151aand a hard DLC layer153a. Soft DLC layer151amay be softer than hard DLC layer153a. In some embodiments, hard DLC layer153amay be formed on soft DLC layer151aso that soft DLC layer151may neutralize film stress and/or prevent delamination in the multi-layer structure. DLC film150may further include a soft DLC layer151zand a hard DLC layer153z. Soft DLC layer151zmay be softer than hard DLC layer153z. Soft DLC layer151amay or may not be softer than one or more other soft DLC layers in DLC film150(e.g., soft DLC layer151z). In one implementation, soft DCL layer151aand soft DLC layer151zmay have the same hardness. In another implementation, soft DCL layer151aand soft DLC layer151zhave different hardness values. While a certain number of pairs of soft DLC layers and hard DLC layers are illustrated inFIG. 1A, this is merely illustrative. DLC film150may include any suitable number of pairs of soft DLC layers and hard DLC layers. For example, DLC film150may include a pair of a soft DLC layer and a hard DLC layer in some embodiments.

In some embodiments, a thickness of DLC film150may be about a few micrometers. As an example, a heavy-duty application of DLC film150may have a thickness of about 5 μm. In some embodiments, a thickness of DLC film150may be about a few nanometers (e.g., 15 nm-100 nm). As an example, a thickness of a display screen protection incorporating DLC film150may be about 20 nm. In some embodiments, a thickness of DLC film150may be about a few hundred nanometers to a few micrometers.

Existing DLC coatings with certain thicknesses (e.g., a thickness greater than 100 nm) are not transparent due to SP2bond between carbon and carbon. More particularly, the electrically conductive electron in Pi bond may absorb photons. According to one or more aspects of the present disclosure, one or more DLC layers may be etched using etching gases including fluorine, hydrogen, are/or chlorine to bleach off the brown color (e.g., by either etching off graphitic carbon or passivating Pi bond by supplying F and/or H colors). A transparent DLC coating may be formed by depositing the DLC layer(s) and performing the etching process iteratively.

Turning toFIG. 1B, a hydrophobic layer160may be formed on DLC film150to form a DLC coating100B. Hydrophobic layer160may include a fluorinated overcoat. In some embodiments, hydrophobic layer160may be and/or include one or more anti-smudge coatings with high water contact angle (e.g., 90-120 degrees). A thickness of hydrophobic layer160may be about 1 nm to 300 nm in some embodiments. As an example, a thickness of hydrophobic layer160of a display screen protector incorporating a DLC coating disclosed herein may be about or greater than 10 nm. In some embodiments, a thickness of the hydrophobic layer may be between about 50 nm and about 100 nm.

In some embodiments, DLC coatings100A and/or100B may be used as screen protectors on a display (e.g., a display of a mobile phone or any other computing device). In such embodiments, substrate110may be and/or include plastic materials, glass, laminated articles, etc. In some embodiments, a thickness of DLC coating100A and/or DLC coating100B may be between about 15 nm and 100 nm. In some embodiments, a thickness of DLC coating100A and/or DLC coating100B may be between about a few hundred nanometers and a few micrometers.

In some embodiments, one or more barrier layers may be deposited between substrate110and DLC film150. The barrier layers may protect substrate111and/or the DLC coating from moisture, ultraviolet (UV) radiation, etc. For example, as shown inFIG. 2A, a barrier layer120may be formed on substrate110. Barrier layer120is optical transparent in some embodiments. A thickness of barrier layer120may be between about a few nanometers and a few micrometers. In some embodiments, a thickness of the barrier layer may be about 20 nm. Barrier layer120may prevent moisture from penetrating through substrate110and reaching layers formed on substrate110. Barrier layer120may also improve adhesion between one or more layers formed on substrate110(e.g., DLC film150) and substrate110. Barrier layer120may include any suitable material that may implement a moisture barrier and/or an adhesion layer, such as SiO2, Al2O3, SiOxCy, the like, or a combination of the above.

In some embodiments, barrier layer120may include SiO2and A1203deposited on substrate110alternatively. For example, barrier layer120may include a plurality of layers of SiO2and Al2O3alternatively stacked on each other (not shown), such as a first layer of SiO2, a first layer of Al2O3formed on the first layer of SiO2, a second layer of SiO2formed on the first layer of Al2O3, a second layer of Al2O3formed on the second layer of SiO2, etc.

In some embodiments, barrier layer120may include one or more layers of SiOxCy. For example, as will be discussed in greater detail in conjunction withFIGS. 9A-9E, the barrier layer may include a plurality of SiOxCylayers of varying hardness, such as a plurality of soft SiOxCylayers and hard SiOxCylayers stacked alternatively on each other. In some embodiments, barrier layer120may further include a plastic sheet positioned between two SiOxCylayers.

In some embodiments, as shown inFIG. 2B, DLC film150may be formed on barrier layer120to form a DLC coating200A. As such, barrier layer120is positioned between substrate110and DLC film150.

The formation of barrier layer120on substrate110may enhance the hardness of the DLC coating. For example, substrate110may have a first hardness value, while the DLC coating200A including substrate110and barrier layer120may have a second hardness value that is greater than the first hardness value. In one implementation, substrate110may include polycarbonate (PC) and may have a hardness of about or lower than1H in pencil hardness scale. In another implementation, substrate110may include laminated PC and may have a hardness of about or lower than 3H in pencil hardness scale. Barrier layer120including SiOxCyand/or Si3N4may be deposited on substrate110to enhance the hardness of the DLC coating (e.g., to a hardness of about or higher than 3H in pencil hardness scale). In some embodiments, the thickness of barrier layer120may be between about 5 μm and 8 μm. The formation of DLC film150on barrier layer120may further enhance the hardness of the DLC coating (e.g., up to 7H-9H in the pencil hardness scale).

In some embodiments, as shown inFIG. 2C, an ultraviolet (UV) protection layer130may be formed on substrate110and/or barrier layer120to prevent substrate110from being exposed to UV and/or to keep the original color features of the components of the DLC coating. In some embodiments, UV protection layer130may block about or at least 90% UV radiation. In some embodiments, a thickness of UV protection layer130may be about 200 nm. UV protection layer130may be optically transparent and electrically conductive.

UV protection layer130may include one or more layers of suitable materials that may block UV radiation. For example, UV protection layer130may include a UV blocking layer135comprising one or more crystalline layers of one or more materials that may prevent one or more portions of UV radiation to which the DLC coating is exposed from perpetrating into the DLC coating. Examples of the materials include Al-doped ZnO, ZnO, TiO2, etc. In some embodiments, UV blocking layer135may include one or more layers of ZnO and TiO2. In some embodiments, UV blocking layer135may include layers of ZnO and TiO2alternatively stacked on each other (not shown), such as a first layer of ZnO, a first layer of TiO2formed on the first layer of ZnO, a second layer of ZnO formed on the first layer of TiO2, a second layer of TiO2formed on the second layer of ZnO, etc.

In some embodiments, one or more portions of UV blocking layer135may be electrically conductive. For example, UV blocking layer135may include one or more layers of Al-doped ZnO of a suitable thickness (e.g., about 100 nm to 500 nm) to connect a power source (e.g., a DC power source) to the DLC coating. As such, UV protection layer130may provide both UV blocking and electrical conductivity functionalities.

In some embodiments, UV protection layer130may further include a transition layer140formed on UV blocking layer135. Transition layer140may serve as a transition from the crystalline layers in UV blocking layer135to DLC film150that includes amorphous materials. Transition layer140may further enhance adhesion of DLC film150on UV protection layer130and/or UV blocking layer135. Transition layer140may include SiO2, Al2O3, the like, or a combination of the above. In some embodiments, transition layer140may include layers of SiO2and A12O3alternatively stacked on each other (not shown), such as a first layer of SiO2, a first layer of Al2O3formed on the first layer of SiO2, a second layer of SiO2formed on the first layer of Al2O3, a second layer of Al2O3formed on the second layer of SiO2, etc. The ZnO film may include perpendicular ZnO rods, while DLC is amorphous. The transitional layer may change the growth orientation and help DLC adhere better on layer below. Chemically, carbon adhere well onto silicon or SiOxCy. A thickness of transition layer140may be about a few nanometers to a few micrometers (e.g., a thickness of about or greater than 2 nm).

In some embodiments, as shown inFIG. 2D, DLC film150may be formed on UV protection layer130to form a DLC coating200B. As such, DLC coating200B includes substrate110, barrier layer120, UV protection layer130, and DLC film150. As shown, UV protection layer130is positioned between substrate110and DLC film150. DLC coating200B may be optically transparent and electrically conductive.

In some embodiments, DLC coatings100A,100B,200A, and/or200B may be used as screen protectors on a display (e.g., a display of a mobile phone or any other computing device). In such embodiments, substrate110may be and/or include plastic materials, glass, laminated articles, etc. In some embodiments, a thickness of each of DLC coatings100A,100B,200A, and/or200B may be between a few hundred nanometers and a few micrometers. In some embodiments, a thickness of each of DLC coatings100A,100B,200A, and/or200B may be between about 15 nm and about 100 nm.

In some embodiments, as shown inFIG. 3A, hydrophobic layer160may be formed on DLC coating200B to form a DLC coating300A. DLC coating300A may include substrate110, barrier layer120, UV protection layer130, DLC film150, and hydrophobic layer160.

In some embodiments, barrier layer120may be omitted from DLC coating300A. For example, as illustrated inFIG. 3B, DLC coating300B may include substrate110, UV protection layer130, DLC film150, and hydrophobic layer160. Each layer and/or component of DLC coatings300A and300B may be optically transparent. As such, DLC coatings300A and/or300B may be optically transparent.

As described above, one or more portions of UV blocking layer135may be electrically conductive. For example, UV blocking layer135may include one or more layers of Al-doped ZnO of a suitable thickness to connect a power source (e.g., a DC power source). Each of DLC coatings300A and300B may be electrically conductive and may be used in applications requiring electrical conductivity, such as window coatings with both UV blocking and defroster functions.

In some embodiments, UV protection layer130may be omitted from DLC coating300A. For example, as illustrated inFIG. 3C, DLC coating300C may include substrate110, barrier layer120, DLC film150, and hydrophobic layer160. Each layer and/or component of DLC coating300C may be optically transparent. As such, DLC coating300C may be optically transparent.

FIG. 4is a flow diagram illustrating an example400of a method for fabricating a DLC coating according to some embodiments of the disclosure. Method400may be performed to fabricate DLC coatings100A and/or100B ofFIGS. 1A-1Bin some embodiments.

Method400may start at block410, where a substrate may be provided. The substrate may include, for example, one or more plastic materials, glass, wood, textiles, semiconductor materials (e.g., silicon). The substrate may be and/or include substrate110as described in connectionFIG. 1Aabove. In some embodiments, providing the substrate may involve loading the substrate into a static machine (e.g., a PECVD system), a system800aor800bofFIGS. 8A-8B, or any other suitable system that may be used to fabricate a DLC coating.

At block420, a DLC film may be formed on the substrate. The DLC film may be optically transparent. In some embodiments, the DLC film may be and/or include the DLC film150as described in connection withFIGS. 1A-1Babove. Forming the DLC film may include forming a multi-layer DLC structure comprising a plurality of DLC layers of varing hardness, such as a first layer of DLC and a second layer DLC formed on the first layer of DLC. The first layer of DLC may be softer than the second layer DLC. In some embodiments, forming the DLC film may further include forming a third layer of DLC. The third layer of DLC may be softer than the second layer of DLC. In some embodiments, forming the DLC film may further include forming a fourth layer of DLC. The third layer of DLC may be softer than the fourth layer of DLC.

Each of the DLC layers may be formed by alternatively performing a deposition process and an etching process in an iterative manner until a desired thickness is achieved. For example, a DLC layer of the multi-layer DLC structure may be formed by depositing an initial DLC layer of using any suitable deposition technique and/or combination of deposition techniques, such as plasma-assisted chemical vapor deposition, ion beam deposition, sputter deposition, radio-frequency (RF) plasma deposition, cathodic arc, etc. The initial DLC layer may be thinner than the DLC layer to be formed. An etching process may then be carried out on a surface of the initial DLC layer to produce an etched initial DLC layer. Performing the etching process on the initial DLC layer may etch weak cc-bonds and break hydrogen bonds, resulting in a widening optical band gap and increasing conductivity activation energy. The deposition process may be repeated after the etching process. For example, DLC may be deposited on the etched initial DLC layer to form a subsequent DLC layer on the initial DLC layer. The subsequent DLC layer may then be etched to produce an etched subsequent DLC layer. The deposition process and the etching process may be performed alternatively as described above until the DLC layer is grown to the desired thickness to obtain optically transparent DLC layers. The hardness of each DLC layer in the DLC film may be achieved by tuning processing conditions in the deposition process and/or the etching process.

In some embodiments, the deposition process may include depositing DLC using inductively coupled plasma (ICP) sources. In some embodiments, the deposition process may be carried out using a radio frequency (RF) ICP source. The power value of the RF generator may be set to about 6 W/cm2. During the deposition process, a reactant stream may be supplied to a processing chamber in which the substrate is located. In some embodiments, the reactant stream may include a hydrocarbon precursor gas, such as ethane (C2H4). In some embodiments, the reactant stream may be a gas mixture of C2H4, argon (Ar), and/or helium (He). The flow rate of C2H4may be about 25 sccm. In some embodiments, the deposition rate may be about65Å/sec. The processing pressure may be, for example, 3.5 mTorr.

The etching process may be performed using the ICP source used in the deposition process. During the etching process, an etching gas mixture comprising CF4, CCI4, CHF3, Ar, and/or H2may be supplied to the processing chamber. The processing pressure may be between about 10 mTorr and about 100 mTorr. In some embodiments, a bias of about 50V may be applied to the substrate during the etching process. The etching process may be carried out for a suitable duration, such as 5-60 seconds. The duration of the etching process may be adapted according to different transmission targets.

In some embodiments, prior to the formation of the DLC film, the substrate may be cleaned using ion implantation methods to promote adhesion between the DLC film and the substrate.

In some embodiments, the surface of the substrate may be treated using a gas mixture comprising Ar, O2, etc. prior to the formation of the DLC film.

In some embodiments, at block430, a hydrophobic layer may be formed on the DLC film. The hydrophobic layer may include a fluorinated overcoat. In some embodiments, the hydrophobic layer may be formed by forming one or more coatings comprising fluoropolymer on the DLC film. For example, the DLC coating produced by performing operations depicted in blocks410and420(e.g., DCL coating100A ofFIG. 1A) may be immersed in a solution containing fluoropolymer (e.g., fluoropolymer dissolved in an ether, such as tetrahydrofuran). A desirable thickness of the hydrophobic layer may be achieved by controlling the concentration of fluoropolymer in the solution and/or the duration of the immersion of the DLC coating in the solution containing fluoropolymer. In some embodiments, block430may be omitted to produce a DCL coating including a multi-layer DLC structure (e.g., the DCL coating100A ofFIG. 1A).

In some embodiments, forming the hydrophobic layer may involve depositing one or more fluoropolymer films by PECVD using octafluorocyclobutane (c-C4F8) or any other suitable precursor gas. In some embodiments, Ar or He may be used as performance enhancement gas in the PECVD process. The power density may be from about 0.1 w/cm2to about 8 w/cm2in some embodiments.

In some embodiments, forming the hydrophobic layer may involve depositing one or more fluoropolymer films by PECVD using a mixture comprising hexafluoroethane (C2F6) and H2.

In some embodiments, forming the hydrophobic layer may involve forming amorphous fluoropolymer films (e.g., Teflon AF1600, AF2400, etc.). The amorphous fluoropolymer films may be formed using a direct liquid injection (DLI) assisted deposition method, a chemical vapor deposition method, etc. In some embodiments, the hydrophobic layer may be UV cured (e.g., processed using UV irradiation).

In some embodiments, the DLC coatings described herein may be fabricated using a pass-by machine, such as system800A and/or800B as described in connection withFIG. 8. In some embodiments, the DLC coatings described herein may be fabricated using a static machine including a chemical vapor deposition system (e.g., a PECVD reactor or any other suitable reactor), such as PECVD system1100ofFIG. 11.

FIGS. 5A and 5Bare flow diagrams illustrating examples500A and500B of methods for fabricating a DLC coating according to some embodiments of the disclosure. Method500A may be performed to fabricate a DLC coating300C ofFIG. 3Cin some embodiments. Method500B may be performed to fabricate a DLC coating900c ofFIG. 9Cin some embodiments.

Method500A may begin at block510, where a substrate is provided. The substrate may be and/or include substrate110as described in connectionFIG. 1Aabove.

At block520, a barrier layer may be formed on the substrate. The barrier layer may prevent moisture from penetrating through the substrate and reaching layers formed on the substrate. The barrier layer may also improve adhesion between layers on the substrate and the substrate. The barrier layer may be and/or include barrier layer120as described in connection withFIGS. 2A, 2B, 9A, and/or9B.

In some embodiments, forming the barrier layer may involve forming one or more layers of SiOxCy. In some embodiments, forming the barrier layer may involve forming multiple layers of SiOxCywith varying hardness, such as one or more alternate soft SiOxCylayers and hard SiOxCylayers as described in connection withFIGS. 9A-9E. In some embodiments, a first hard SiOxCylayer may be formed on a first soft SiOxCylayer. The hardness of the first hard SiOxCylayer layer may be higher than that of the first soft SiOxCylayer. A second soft SiOxCylayer may be formed on the first hard SiOxCylayer. Any suitable number of soft SiOxCylayers and hard SiOxCylayers may be formed to fabricate the barrier layer.

The quality (e.g., the hardness) of the barrier layer may be controlled by adjusting the source power to dissociate the organosilicon precursors and/or the gas ratio of O2to the organosilicon precursor(s) (also referred to herein as the “O2/precursor flow ratio”). For example, forming a SiOxCylayer using a relatively higher O2/precursor flow ratio in the PECVD process may deposit more SiO2and may thus form a relatively harder film. Forming a SiOxCylayer using a relatively lower O2/precursor flow ratio in the PECVD process may result in the formation of a film containing methyl and end up having SiOxCy. The values of x and y and the hardness of the film may be controlled by adjusting the volume of O2and/or the O2/precursor flow ratio in the PECVD process. For example, using a relatively higher O2/precursor flow ratio in the PECVD process may deposit SiOxCywith a relatively greater value of x and a relatively lower value of y. Using a relatively lower O2/precursor flow ratio in the PECVD process may deposit SiOxCywith a relatively greater value of y and a relatively lower value of x.

In some embodiments, forming the barrier layer may involve forming one or more layers of SiO2and/or one or more layers of Al2O3. In some embodiments, a plurality of layers of SiO2and Al2O3may be formed alternatively (e.g., a first layer of SiO2, a first layer of Al2O3formed on the first layer of SiO2, a second layer of SiO2formed on the first layer of Al2O3, a second layer of Al2O3formed on the second layer of SiO2, etc.).

In some embodiments, the barrier layer may be formed utilizing one or more chemical vapor deposition techniques, such as Plasma Enhanced Chemical Vapor Deposition (PECVD) techniques. In some embodiments, the barrier layer may be formed using a suitable plasma source (e.g., a capacitive coupled plasma (CCP) source, an inductively coupled plasma (ICP) source, an RF ICP, hollow cathode, etc.) with precursors comprising organosilicon compounds (e.g., hexamethyldisiloxane (HMDSO), octamethylcyclotetrasiloxane (OMCTS)) in plasma gas comprising O2, Ar, He, etc. In some embodiments, the barrier layer may be formed using a dual-frequency CCP source comprising multi-frequency radio frequency sources (e.g., system1000as described in connection withFIG. 10).

In some embodiments, the barrier layer may be formed using one or more suitable sputtering methods. For example, forming the barrier layer may involve radio frequency (RF) magnetron sputtering of SiO2and/or Al2O3to form one or more layers of SiO2and/or one or more layers of Al2O3. As a more particular example, SiO2may be deposited using an RF magnetron sputtering method in a gas mixture of oxygen and argon at a suitable processing pressure (e.g., 2 mTorr). In some embodiments, the gas mixture may further include He and/or H2. A gas volume ratio of oxygen to argon may be 1/9 in some embodiments. An RF power of about 1500 W may be used to sputtering SiO2in some embodiments. The barrier layer may be deposited at a deposition rate lower than 3 Å/sec in some embodiments. In some embodiments, SiO2may be deposit using a sputtering target including boron-doped Si. The target can be sputtered using direct current (DC) power supplies or any other suitable power supply. The barrier layer may be deposited at a deposition rate higher than 10 Å/sec.

In some embodiments, the surface of the substrate may be treated using a gas mixture including one or more of Ar, O2, etc. prior to the formation of the barrier layer.

At block530, a DLC film may be formed on the barrier layer. Forming the DLC film may include forming a multi-layer DLC structure comprising a plurality of DLC layers of various hardness, such as the DLC film150ofFIGS. 1A-3B. In some embodiments, the DLC film may be formed by performing one or more operations as described in connection with block420ofFIG. 4above. In some embodiments, forming the DLC film may include depositing DLC using an ICP source from a gas mixture comprising SiH4and C2H4.

In some embodiments, at block540, a hydrophobic layer may be formed on the DLC film. The hydrophobic layer may include a fluorinated overcoat. In some embodiments, the hydrophobic layer may be formed by forming one or more coatings comprising fluoropolymer on the DLC film. In some embodiments, the hydrophobic layer may be formed by performing one or more operations as described in connection with block430ofFIG. 4. In some embodiments, block540may be omitted to produce a DLC coating200A ofFIG. 2B.

Method500B may begin at block550, where a substrate is provided. The substrate may be and/or include substrate110as described in connectionFIG. 1Aabove.

At block560, a barrier layer may be formed on the substrate. The barrier layer may be formed by performing one or more operations as described in connection with block520above.

At block570, a hydrophobic layer may be formed on the barrier layer. The hydrophobic layer may be formed by performing one or more operations as described in connection with block430above.

FIG. 6is a flow diagram illustrating an example600of a method for fabricating a DLC coating according to some embodiments of the disclosure. Method600may be performed to fabricate a DLC coating300A ofFIG. 3Ain some embodiments.

Method600may begin at block610, where a substrate is provided. The substrate may be and/or include substrate110as described in connectionFIG. 1Aabove.

At block620, a barrier layer may be formed on the substrate. The barrier layer may be and/or include the barrier layer120as described in connection withFIGS. 2A-2D. The barrier layer may be formed by performing one or more operations as described in connection with block520ofFIG. 5.

At block630, a UV protection layer may be formed on the barrier layer. The UV protection layer may prevent the substrate from UV radiation and/or to keep color features of the components of the DLC coating to be formed. The UV protection layer may be optically transparent and electrically conductive. The UV protection layer may be and/or include the UV protection layer130ofFIGS. 2C-3Dabove. Forming the UV protection layer may include forming a UV blocking layer as depicted in block631and forming a transition layer as depicted in block633.

At block631, a UV blocking layer may be formed on the barrier layer. Forming the UV blocking layer may involve forming one or more crystalline layers of Al-doped ZnO, ZnO, TiO2, etc. In some embodiments, forming the UV blocking layer may involve forming a plurality of layers of ZnO and TiO2alternatively stacked on each other (e.g., a first layer of ZnO, a first layer of TiO2formed on the first layer of ZnO, a second layer of ZnO formed on the first layer of TiO2, a second layer of TiO2formed on the second layer of ZnO, etc.). For example, forming the UV blocking layer may include forming one or more crystalline layers of ZnO using a suitable RF magnetron sputtering method. The crystalline layers of ZnO may include one or more layers of ZnO oriented along the (002) crystalline direction. As another example, forming the UV blocking layer may include forming one or more crystalline layers of Al-doped ZnO using a suitable DC magnetron sputtering method. Each of the layers of Al-doped ZnO may be a transparent conductive oxide (TCO) layer having suitable electrical conductivity.

At block633, a transition layer may be formed on the UV blocking layer. The transition layer may include SiO2, Al2O3, the like, or a combination of the above. In some embodiments, transition layer140may include layers of SiO2and Al2O3alternatively stacked on each other. Forming the transition layer may involve forming one or more layers of SiO2and/or one or more layers of Al2O3. In some embodiments, a plurality of layers of SiO2and Al2O3may be alternatively formed on each other (e.g., a first layer of SiO2, a first layer of Al2O3formed on the first layer of SiO2, a second layer of SiO2formed on the first layer of Al2O3, a second layer of Al2O3formed on the second layer of SiO2, etc.). The layers of SiO2and/or Al2O3may be formed using one or more suitable sputtering methods, such as the sputtering methods described in connection with block520ofFIG. 5.

At block640, a DLC film may be formed on the UV protection layer. The DLC film may be formed, for example, by performing one or more operations described in connection with block420ofFIG. 4.

At block650, a hydrophobic layer may be formed on the DLC film. The hydrophobic film may be formed, for example, by performing one or more operations described in connection with block430ofFIG. 4.

In some embodiments, block650may be omitted to produce DLC coating200B ofFIG. 2D.

FIG. 7is a flow diagram illustrating an example700of a method for fabricating a DLC coating according to some embodiments of the disclosure. Method700may be performed to fabricate a DLC coating300B ofFIG. 3Bin some embodiments.

Method700may begin at block710, where a substrate is provided. The substrate may be and/or include substrate110as described in connectionFIG. 1Aabove.

At block720, a UV protection layer may be formed on the substrate. The UV protection layer may prevent the substrate from being exposed to UV and to keep color features of the components of the DLC coating to be formed. The UV protection layer may be and/or include the UV protection layer130ofFIGS. 2C-3Dabove. The UV protection layer may be formed by performing one or more operations described in connection with block630ofFIG. 6. For example, forming the UV protection layer may include forming a UV blocking layer as depicted in block721and forming a transition layer as depicted in block723.

At block730, a DLC film may be formed on the UV protection layer. The DLC film may be formed, for example, by performing one or more operations described in connection with block420ofFIG. 4.

At block740, a hydrophobic layer may be formed on the DLC film. The hydrophobic film may be formed, for example, by performing one or more operations described in connection with block430ofFIG. 4. In some embodiments, block740may be omitted.

For simplicity of explanation, the methods of this disclosure are depicted and described as a series of acts. However, acts in accordance with this disclosure can occur in various orders and/or concurrently, and with other acts not presented and described herein. Furthermore, not all illustrated acts may be required to implement the methods in accordance with the disclosed subject matter. In addition, those skilled in the art will understand and appreciate that the methods could alternatively be represented as a series of interrelated states via a state diagram or events.

FIGS. 8A and 8Bare schematic diagrams depicting examples800a and800b of systems that may be used to fabricate DLC coatings in accordance with some embodiments of the present disclosure.

As illustrated, system800a may include a conveyor805a and one or more processing stations810,820,830,840,850, and860for fabricating various components of a DLC coating in accordance one or more aspects of the present disclosure. System800bmay include a conveyor805band one or more processing stations810,820,830,840,850, and860for fabricating various components of a DLC coating in accordance one or more aspects of the present disclosure.

A substrate (e.g., rigid plastic or glass) may be uploaded onto the conveyor810aor810bin the processing station810. The conveyor805aor805bmay move the substrate to one or more of the processing stations820,830,840,850and860for processing. Each of the processing stations820,830,840,850, and860may include a reactor in which one or more portions of a DLC coating may be formed. The size of the reactor may be designed based on the size of the substrate that is to be used to form the DLC coating. The conveyor805amay be suitable for transporting a rigid substrate (e.g., a substrate of rigid plastic materials, a glass substrate, etc.) for fabricating DLC coatings. The conveyor805bmay include one or more pulleys and/or any other suitable mechanisms for conveying a soft substrate (e.g., a substrate of soft plastic materials, a thin glass sheet, etc.) for fabricating DLC coatings.

In the processing station820, a barrier layer may be formed on the substrate (e.g., by performing one or more operations described in connection with520ofFIG. 5and/or block620ofFIG. 6). In processing station830, a UV blocking layer may be formed on the substrate and/or the barrier layer (e.g., by performing one or more operations described in connection with631ofFIG. 6and/or block721ofFIG. 7). In processing station840, a transition layer may be formed (e.g., by performing one or more operations described in connection with633ofFIG. 6and/or block723ofFIG. 7). In processing station850, a DLC film may be formed (e.g., by performing one or more operations described in connection with block420ofFIG. 4, block530ofFIG. 5, and/or block640ofFIG. 6and/or block730ofFIG. 7). In processing station860, a hydrophobic layer may be formed (e.g., by performing one or more operations described in connection with block430ofFIG. 4, block650ofFIG. 6, and/or block740ofFIG. 7).

In some embodiments, one or more of processing stations820,830,840, and/or860may be omitted to implement various embodiments of the present disclosure. For example, a system for performing method400ofFIG. 4may include conveyor810aand/or810b,processing station850, and processing station860. As another example, a system for performing method500ofFIG. 5may include conveyor810aand/or810b,processing station820and850. As a further example, a system for performing method600ofFIG. 6may include conveyor810aand/or810b,processing station820, processing station830, processing station840, processing station850, and processing station860. As a further example, a system for performing method600ofFIG. 6may include conveyor810aand/or810b,processing station830, processing station840, processing station850, and processing station860.

In some embodiments, system800aand/or800bmay further include a processing station870from which the DLC coating may be unloaded.

FIGS. 9A, 9B, and 9Cdepict example DLC coatings according to some embodiments of the present disclosure.FIGS. 9D and 9Edepict examples of a barrier layer according to some embodiments of the present disclosure.

As illustrated inFIG. 9A, DLC coating900amay include a substrate110, a barrier layer120, a DLC film150, and a hydrophobic layer160. Barrier layer120may include a plurality of layers of SiOxCywith varying hardness, such as soft SiOxCylayers121a, . . . ,121zand hard SiOxCylayers123a, . . ,123zthat are formed alternatively. More particularly, for example, a first hard SiOxCylayer123amay be formed on a first soft SiOxCylayer121a.Soft SiOxCylayer may be softer than hard SiOxCylayer123a. A second soft SiOxCylayer (e.g., SiOxCylayer121z) may be formed on the first hard SiOxCylayer123a. The second soft SiOxCylayer may be softer than the first hard SiOxCylayer123a. The first soft SiOxCylayer and the second soft SiOxCylayer may or may not have the same hardness. In some embodiments, the first SiOxCylayer and the second SiOxCylayer have the same hardness. A second hard SiOxCylayer (e.g., SiOxCylayer123z) may be formed on the second soft SiOxCylayer. The hardness of the second hard SiOxCylayer may be higher than that of the second soft SiOxCylayer.

In some embodiments, a thickness of a soft SiOxCylayer121a-n may be about 20 nm-200 nm. In some embodiments, a thickness of a hard SiOxCylayer123a-nmay be about 100 nm-5000 nm. In some embodiments, a thickness of the DLC film150is between about 15 nm and about 100 nm.

The soft SiOxCylayers and the hard SiOxCylayers alternatively stacked on each other may enhance adhesion between the DLC film and the other component of the DLC coating and the substrate. Residual stress may make the substrate (e.g., a plastic sheet) bend towards its non-coated side. The SiOxCylayer(s) may enhance the mechanical strength of the substrate and may support the DLC film and/or other component of the DLC coating.

A DLC film150may be formed on the barrier layer120. A hydrophobic layer160may be formed on the DLC film150. In some embodiments, package cardboards (not shown) may sandwich the DLC coating.

In some embodiments, the hydrophobic layer160may be omitted. For example, as illustrated inFIG. 9B, DLC coating900bmay include substrate110, barrier layer120, and DLC film150.

In some embodiments, hydrophobic layer160may be formed directedly on barrier layer120. For example, as illustrated inFIG. 9C, DLC coating900cmay include substrate110, barrier layer120, and hydrophobic layer160.

In some embodiments, barrier layer120may further include one or more plastic sheets positioned between multiple layers121a-zand/or123a-z.For example, as illustrated inFIG. 9D, barrier layer900dmay include a plastic sheet125positioned between a hard SiOxCylayer121zand a soft SiOxCylayer123b.In one implementation, the plastic sheet125is in direct contact with soft SiOxCylayer123b.In another implementation, the plastic sheet125is not in direct contact with soft SiOxCylayer123b.For example, one or more layers of SiOxCyand/or any other suitable material for implementing the functionality of the barrier layer120may be positioned between plastic sheet125and SiOxCylayer123b.As illustrated inFIG. 9E, the plastic sheet125may be positioned between the substrate110and the barrier layer120in some embodiments. DLC film500and/or hydrophobic layer160may be formed on the barrier layer illustrated inFIGS. 9D-9E.

FIG. 10is a schematic diagram illustrating an example1000of a dual-frequency capacitively coupled plasma (CCP) system for fabricating DLC coatings in accordance with some embodiments of the present disclosure. System1000may include a first power source1001and a second power source1003. The first power source1001may provide first power of a first frequency to a first electrode1011(e.g., the upper electrode) to control plasma density and deposition rate. The second power source1003may provide second power of a second frequency to a second electrode1013(e.g., the bottom electrode) holding the wafer to control ion bombardment energy/densification and thin film hardness. The first frequency may be higher than the second frequency. As an example, the first frequency may be tens of MHz (e.g., a frequency of about or higher than 13.56 MHz). The second frequency may be hundreds of KHz to a few MHz (e.g., a frequency between about 100 KHz and 2 MHz). The difference between the first frequency and the second frequency may enable interference-free and independent energy control.

FIG. 11is a schematic diagram illustrating an example1100of a plasma-enhanced chemical vapor deposition (PECVD) system for fabricating DLC coatings in accordance with some embodiments of the present disclosure. System1100may be used to deposit one or more portions of a DLC coating as described herein.

As shown, system1100may include a reactor1101, a plasma source1103, electrodes1105aand1105b,pump1107, one or more input ports1109, and/or any other suitable component.

Plasma source1103may include an ICP source, hollow cathode source, etc. Plasma source1103may be covered by a shield that may protect the plasma source. Plasma gas may be discharged between parallel electrodes1105aand1105b.The plasma gas may include, for example, a gas mixture of one or more of Ar, O2, He, etc. to form one or more components of a DLC coating. Suitable precursors may be used to form one or more DLC coatings on a substrate1109as described herein. For example, a precursor mixture including one or more of HMDSO, OMCTS, C2H4, C—C4F8, O2, etc. may be used to form a barrier layer as described herein. The plasma gas and/or the precursors may be provided to reactor1101via one or more input ports1109. Reaction byproducts produced during the fabrication of the DLC coating may be pumped away by the pump1107.

The terms “approximately,” “about,” and “substantially” may be used to mean within ±20% of a target dimension in some embodiments, within ±10% of a target dimension in some embodiments, within ±5% of a target dimension in some embodiments, and yet within ±2% in some embodiments. The terms “approximately” and “about” may include the target dimension. Numeric ranges are inclusive of the numbers defining the range.

In the foregoing description, numerous details are set forth. It will be apparent, however, that the disclosure may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the disclosure.

The terms “first,” “second,” “third,” “fourth,” etc. as used herein are meant as labels to distinguish among different elements and may not necessarily have an ordinal meaning according to their numerical designation.

The words “example” or “exemplary” are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the words “example” or “exemplary” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Reference throughout this specification to “an implementation” or “one implementation” means that a particular feature, structure, or characteristic described in connection with the implementation is included in at least one implementation. Thus, the appearances of the phrase “an implementation” or “one implementation” in various places throughout this specification are not necessarily all referring to the same implementation.

As used herein, when an element or layer is referred to as being “on” another element or layer, the element or layer may be directly on the other element or layer, or intervening elements or layers may be present. In contrast, when an element or layer is referred to as being “directly on” another element or layer, there are no intervening elements or layers present.