PATENT DOCUMENT

Publication Number: US-11719865-B2
Application Number: US-202117176992-A
Country: US
Kind Code: B2

Title: Visible-light-reflecting coatings for electronic devices

Abstract:
An electronic device may include conductive structures having a visible-light-reflecting coating. The coating may include a seed layer, transition layers, a neutral-color base layer, and an uppermost layer that forms a single-layer interference film. The neutral-color base layer may be opaque to visible light. The interference film may include silicon and may have an absorption coefficient between 0 and 1. The interference film may include, for example, CrSiCN or CrSiC. The composition of the interference film, the thickness of the interference film, and/or the composition of the base layer may be selected to provide the coating with a desired color in the visible spectrum (e.g., at blue or purple wavelengths). The color may be relatively stable even if the thickness of the coating varies across its area.

Claims:
What is claimed is: 
     
       1. Apparatus comprising:
 a conductive substrate; and 
 a coating on the conductive substrate and having a color, the coating comprising:
 adhesion and transition layers, 
 a CrSiN layer on the adhesion and transition layers, the CrSiN layer being opaque to light of the color, and 
 an uppermost layer on the CrSiN layer, the uppermost layer comprising a CrSiC film. 
 
 
     
     
       2. The apparatus of  claim 1 , wherein the CrSiC film forms a single-layer interference filter. 
     
     
       3. The apparatus of  claim 1 , wherein the CrSiC film has a thickness between 0.01 and 0.1 microns. 
     
     
       4. The apparatus of  claim 3 , wherein an atomic percentage of Cr atoms in the CrSiC film is greater than 25% and less than 35% and wherein an atomic percentage of Si atoms in the CrSiC film is greater than 50% and less than 60%. 
     
     
       5. The apparatus of  claim 4 , wherein an atomic percentage of Cr atoms in the CrSiN layer is greater than 55% and less than 65% and wherein an atomic percentage of Si atoms in the CrSiN layer is greater than 20% and less than 30%. 
     
     
       6. The apparatus of  claim 5 , wherein the CrSiC film has a thickness between 0.04 and 0.06 microns. 
     
     
       7. The apparatus of  claim 6 , wherein the coating has an L* value between 45 and 55 in a CIELAB color space, an a* value between −5 and 0 in the CIELAB color space, and a b* value between −14 and −10 in the CIELAB color space. 
     
     
       8. The apparatus of  claim 3 , wherein an atomic percentage of Cr atoms in the CrSiC film is greater than 50% and less than 60% and wherein an atomic percentage of Si atoms in the CrSiC film is greater than 30% and less than 40%. 
     
     
       9. The apparatus of  claim 8 , wherein an atomic percentage of Cr atoms in the CrSiN layer is greater than 60% and less than 70% and wherein an atomic percentage of Si atoms in the CrSiN layer is greater than 10% and less than 25%. 
     
     
       10. The apparatus of  claim 9 , wherein the CrSiC film has a thickness between 0.01 and 0.04 microns. 
     
     
       11. The apparatus of  claim 10 , wherein the coating has an L* value between 35 and 40 in a CIELAB color space, an a* value between 0 and 5 in the CIELAB color space, and a b* value between −10 and −5 in the CIELAB color space. 
     
     
       12. The apparatus defined in  claim 1 ,
 wherein the adhesion and transition layers comprise a seed layer on the conductive substrate and a transition layer on the seed layer, wherein the seed layer comprises a material selected from the group consisting of: Cr, CrSi, and Ti, and wherein the transition layer comprises a material selected from the group consisting of: CrSiN, CrSiCN, CrN, and CrCN. 
 
     
     
       13. The apparatus defined in  claim 1 , wherein the conductive substrate comprises a conductive substrate selected from the group consisting of: a conductive electronic device housing wall and a three-dimensional conductive structure for an electronic device. 
     
     
       14. Apparatus comprising:
 a conductive substrate; and 
 a coating on the conductive substrate and having a color, the coating comprising:
 adhesion and transition layers, 
 a CrSiN layer on the adhesion and transition layers, the CrSiN layer being opaque to light of the color, and 
 an uppermost layer on the CrSiN layer, the uppermost layer comprising a CrSiCN film, wherein the CrSiCN film has a thickness between 0.01 and 0.1 microns. 
 
 
     
     
       15. The apparatus of  claim 14 , wherein the CrSiCN film forms a single-layer interference filter. 
     
     
       16. The apparatus of  claim 15 , wherein an atomic percentage of Cr atoms in the CrSiCN film is greater than 30%, wherein an atomic percentage of Si atoms in the CrSiCN film is greater than 20%, and wherein an atomic percentage of C atoms in the CrSiCN film is greater than 30%. 
     
     
       17. The apparatus of  claim 16 , wherein the atomic percentage of Cr atoms in the CrSiCN film is less than 36% and wherein the atomic percentage of Si atoms in the CrSiCN film is less than 30%. 
     
     
       18. The apparatus of  claim 17 , wherein an atomic percentage of Cr atoms in the CrSiN layer is greater than 30% and less than 40% and wherein an atomic percentage of Si atoms in the CrSiN layer is greater than 10% and less than 20%. 
     
     
       19. The apparatus of  claim 18 , wherein the thickness is between 0.05 and 0.07 microns. 
     
     
       20. The apparatus of  claim 19 , wherein the coating has an L* value between 45 and 50 in a CIELAB color space, an a* value between −5 and −2 in the CIELAB color space, and a b* value between −12 and −8 in the CIELAB color space. 
     
     
       21. Apparatus comprising:
 a conductive substrate; and 
 a coating on the conductive substrate and having a color, the coating comprising:
 a Cr seed layer, 
 a CrN transition layer on the Cr seed layer, and 
 an uppermost layer on the CrN transition layer, wherein the uppermost layer comprises TiSiN. 
 
 
     
     
       22. The apparatus of  claim 21 , wherein the uppermost layer has a thickness between 0.3 and 0.5 microns and wherein an atomic percentage of Ti atoms in the uppermost layer is greater than 50% and less than 60%. 
     
     
       23. The apparatus of  claim 22 , wherein the coating has an L* value between 70 and 80 in a CIELAB color space, an a* value between 0 and 5 in the CIELAB color space, and a b* value between 10 and 15 in the CIELAB color space. 
     
     
       24. Apparatus comprising:
 a conductive substrate; and 
 a coating on the conductive substrate and having a color, the coating comprising:
 adhesion and transition layers, 
 a CrSiCN layer on the adhesion and transition layers, the CrSiCN layer being opaque to light of the color, and 
 an uppermost layer on the CrSiCN layer, the uppermost layer comprising a CrSiCN film.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 62/988,346, filed Mar. 11, 2020, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to coatings for electronic device structures and, more particularly, to visible-light-reflecting coatings for conductive electronic device structures. 
     BACKGROUND 
     Electronic devices such as cellular telephones, computers, watches, and other devices contain conductive structures such as conductive housing structures. The conductive structures are provided with a coating that reflects particular wavelengths of light so that the conductive components exhibit a desired visible color. 
     It can be difficult to provide coatings with a relatively uniform thickness, particularly on conductive structures with non-planar shapes. If care is not taken, thickness variations in the coating can undesirably distort the color and visual appearance of the coating across its area. 
     SUMMARY 
     An electronic device may include conductive structures such as conductive housing structures. The conductive structures may have three-dimensional surfaces or other non-planar shapes. A visible-light-reflecting coating may be formed on the conductive structures. The coating may include a seed layer on the conductive structures, one or more transition layers on the seed layer, a neutral-color base layer on the transition layers, and a single-layer interference film on the neutral-color base layer. The single-layer interference film may be the uppermost layer of the coating. The neutral-color base layer may be opaque to visible light. 
     The single-layer interference film may include silicon and may have an absorption coefficient between 0 and 1. The single-layer interference film may include, for example, CrSiCN or CrSiC. The neutral-color base layer may include, for example, CrSiN. The composition and thickness of the single-layer interference film may be selected to provide the coating with a desired color (e.g., blue or purple in scenarios where CrSiC is used or blue in scenarios where CrSiCN is used). Light reflected by the interfaces of the single-layer interference film may constructively and destructively interfere to exhibit a relatively uniform reflected intensity across a wavelength in the visible spectrum (e.g., at blue or purple wavelengths). This may configure the coating to exhibit a relatively uniform (stable) color near the middle of the visible spectrum even if the thickness of the coating varies across its area. In another suitable arrangement, the single-layer interference film and the neutral-color base layer may be replaced by a TiSiN color layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of an illustrative electronic device of the type that may be provided with conductive structures and visible-light-reflecting coatings in accordance with some embodiments. 
         FIG.  2    is cross-sectional side view of an illustrative electronic device having conductive structures that may be provided with visible-light-reflecting coatings in accordance with some embodiments. 
         FIG.  3    is a cross-sectional side view of an illustrative visible-light-reflecting coating having a coloring layer that is highly sensitive to thickness variations in accordance with some embodiments. 
         FIG.  4    is a cross-sectional side view of an illustrative coating that reflects visible light with a relatively uniform reflected intensity regardless of thickness variations in accordance with some embodiments. 
         FIG.  5    is a cross-sectional side view of an illustrative coating of the type shown in  FIG.  4   , having a single-layer interference film formed from chromium silicon carbonitride in accordance with some embodiments. 
         FIG.  6    is a plot of the atomic percentage of different elements in an illustrative single-layer interference film for a coating of the type shown in  FIG.  5    in accordance with some embodiments. 
         FIG.  7    is a plot of the atomic percentage of different elements in an illustrative neutral-color base layer for a coating of the type shown in  FIG.  5    in accordance with some embodiments. 
         FIG.  8    is a cross-sectional side view of an illustrative coating of the type shown in  FIG.  4   , having a single-layer interference film formed from chromium silicon carbide in accordance with some embodiments. 
         FIG.  9    is a plot of the atomic percentage of different elements in an illustrative single-layer interference film for a coating of the type shown in  FIG.  8    in accordance with some embodiments. 
         FIG.  10    is a plot of the atomic percentage of different elements in an illustrative neutral-color base layer for a coating of the type shown in  FIG.  8    in accordance with some embodiments. 
         FIG.  11    is a cross-sectional side view of an illustrative coating having a color layer formed from titanium silicon nitride in accordance with some embodiments. 
         FIG.  12    is a plot of the atomic percentage of different elements in an illustrative color layer for a coating of the type shown in  FIG.  11    in accordance with some embodiments. 
         FIG.  13    is a plot of the atomic percentage of different elements in an illustrative transition layer for a coating of the type shown in  FIG.  11    in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices and other items may be provided with conductive structures. Coatings may be formed on the conductive structures to reflect particular wavelengths of visible light so that the conductive structures exhibit a desired color. A visible-light-reflecting coating may be deposited on a conductive substrate. The visible-light reflecting coating may include transition and adhesion layers on the substrate, a neutral-color base layer on the transition and adhesion layers, and an upper-most single-layer interference film on the neutral-color base layer. In other suitable arrangements, the coating may include a non-neutral (colored) base layer instead of a neutral-color base layer and/or a multi-layer thin-film interference filter on the base layer instead of a single-layer interference film. 
     The single-layer interference film may have a thickness and a composition that configures the coating to reflect light of a particular color within a desired range of the visible light spectrum (e.g., a blue or purple color). The single-layer interference film may include chromium silicon carbonitride or chromium silicon carbide, for example. The composition and thickness of the single-layer interference film may be selected to provide the coating with a non-zero absorption coefficient at some wavelengths to help tune the reflected color of the coating. 
     The single-layer interference film and the neutral-color base layer may be relatively color-insensitive to variations in thickness of the coating. For example, even if the coating exhibits different thicknesses across its area (e.g., due to limitations in the deposition equipment used to deposit the coating and/or in scenarios where the substrate has a three-dimensional shape), the reflected intensity of the coating may be relatively uniform (e.g., without significant local minima or maxima) across the wavelength band that gives the color of the coating. This may allow the coating and thus the underlying substrate to exhibit a uniform color and aesthetic appearance, even if the substrate is three dimensional and even if the deposition equipment used to deposit the coating is incapable of providing the coating with a precise thickness across its area. The neutral-color base layer and the single-layer interference film may be replaced by a color layer if desired. In these arrangements, the color layer may include titanium silicon nitride, as an example. 
     An illustrative electronic device of the type that may be provided with conductive structures and visible-light-reflecting coatings is shown in  FIG.  1   . Electronic device  10  of  FIG.  1    may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device (e.g., a watch with a wrist strap), a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head (e.g., a head mounted device), or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a wireless base station, a home entertainment system, a wireless speaker device, a wireless access point, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG.  1   , device  10  is a portable device having a substantially rectangular lateral outline such as a cellular telephone or tablet computer. Other configurations may be used for device  10  if desired. The example of  FIG.  1    is merely illustrative. 
     In the example of  FIG.  1   , device  10  includes a display such as display  14 . Display  14  may be mounted in a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). Housing  12  may have metal sidewalls or sidewalls formed from other materials. Examples of metal materials that may be used for forming housing  12  include stainless steel, aluminum, silver, gold, titanium, metal alloys, or any other desired conductive material. 
     Display  14  may be formed at (e.g., mounted on) the front side (face) of device  10 . Housing  12  may have a rear housing wall on the rear side (face) of device  10  that opposes the front face of device  10 . Conductive housing sidewalls in housing  12  may surround the periphery of device  10 . The rear housing wall of housing  12  may be formed from conductive materials and/or dielectric materials. 
     The rear housing wall of housing  12  and/or display  14  may extend across some or all of the length (e.g., parallel to the X-axis of  FIG.  1   ) and width (e.g., parallel to the Y-axis) of device  10 . Conductive sidewalls of housing  12  may extend across some or all of the height of device  10  (e.g., parallel to Z-axis). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode (OLED) display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer. The display cover layer may be formed from a transparent material such as glass, plastic, sapphire or other crystalline dielectric materials, ceramic, or other clear materials. The display cover layer may extend across substantially all of the length and width of device  10 , for example. 
     Device  10  may include one or more buttons. The buttons may be formed from a conductive button member that is located within (e.g., protruding through) openings in housing  12  or openings in display  14  (as examples). Buttons may be rotary buttons, sliding buttons, buttons that are actuated by pressing on a movable button member, etc. 
     A cross-sectional side view of device  10  in an illustrative configuration in which display  14  has a display cover layer is shown in  FIG.  2   . As shown in  FIG.  2   , display  14  may have one or more display layers that form pixel array  18 . During operation, pixel array  18  forms images for a user in an active area of display  14 . Display  14  may also have inactive areas (e.g., areas along the border of pixel array  18 ) that are free of pixels and that do not produce images. Display cover layer  16  of  FIG.  2    overlaps pixel array  18  in the active area and overlaps electrical components in device  10 . 
     Display cover layer  16  may be formed from a transparent material such as glass, plastic, ceramic, or crystalline materials such as sapphire. Illustrative configurations in which a display cover layer and other transparent members in device  10  (e.g., windows for cameras and other light-based devices that are formed in openings in housing  12 ) are formed from a hard transparent crystalline material such as sapphire (sometimes referred to as corundum or crystalline aluminum oxide) may sometimes be described herein as an example. Sapphire makes a satisfactory material for display cover layers and windows due to its hardness (9 Mohs). In general, however, these transparent members may be formed from any suitable material. 
     Display cover layer  16  for display  14  may be planar or curved and may have a rectangular outline, a circular outline, or outlines of other shapes. If desired, openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button, a speaker port, or other component. Openings may be formed in housing  12  to form communications or data ports (e.g., an audio jack port, a digital data port, a port for a subscriber identity module (SIM) card, etc.), to form openings for buttons, or to form audio ports (e.g., openings for speakers and/or microphones). 
     Device  10  may, if desired, be coupled to a strap such as strap  28  (e.g., in scenarios where device  10  is a wristwatch device). Strap  28  may be used to hold device  10  against a user&#39;s wrist (as an example). Strap  28  may sometimes be referred to herein as wrist strap  28 . In the example of  FIG.  2   , wrist strap  28  is connected to attachment structures  30  in housing  12  at opposing sides of device  10 . Attachment structures  30  may include lugs, pins, springs, clips, brackets, and/or other attachment mechanisms that configure housing  12  to receive wrist strap  28 . Configurations that do not include straps may also be used for device  10 . 
     If desired, light-based components such as light-based components  24  may be mounted in alignment with an opening  20  in housing  12 . Opening  20  may be circular, may be rectangular, may have an oval shape, may have a triangular shape, may have other shapes with straight and/or curved edges, or may have other suitable shapes (outlines when viewed from above). Window member  26  may be mounted in window opening  20  of housing  12  so that window member  26  overlaps component  18 . A gasket, bezel, adhesive, screws, or other fastening mechanisms may be used in attaching window member  26  to housing  12 . Surface  22  of window member  26  may lie flush with exterior surface  23  of housing  12 , may be recessed below exterior surface  23 , or may, as shown in  FIG.  3   , be proud of exterior surface  23  (e.g., surface  22  may lie in a plane that protrudes away from surface  23  in the −Z direction). In other words, window member  26  may be mounted to a protruding portion of housing  12 . Surface  23  may, for example, form the rear face of housing  12 . 
     Conductive structures in device  10  may be provided with a visible-light-reflecting coating that reflects certain wavelengths of light so that the conductive structures exhibit a desired aesthetic appearance (e.g., a desired color, reflectivity, etc.). The conductive structures in device  10  may include, for example, conductive portions of housing  12  (e.g., conductive sidewalls for device  10 , a conductive rear wall for device  10 , a protruding portion of housing  12  used to mount window member  26 , etc.), attachment structures  30 , conductive portions of wrist strap  28 , a conductive mesh, conductive components  32 , and/or any other desired conductive structures on device  10 . Conductive components  32  may include internal components (e.g., internal housing members, a conductive frame, a conductive chassis, a conductive support plate, conductive brackets, conductive clips, conductive springs, input-output components or devices, etc.), components that lie both at the interior and exterior of device  10  (e.g., a conductive SIM card tray or SIM card port, a data port, a microphone port, a speaker port, a conductive button member, etc.), or components that are mounted at the exterior of device  10  (e.g., conductive portions of strap  28  such as a clasp for strap  28 ), and/or any other desired conductive structures on device  10 . 
       FIG.  3    is a cross-sectional diagram of a visible-light-reflecting coating that may be provided on conductive structures in device  10  (e.g., portions of housing  12  of  FIGS.  1  and  2   , conductive components  32  of  FIG.  2   , etc.). As shown in  FIG.  3   , visible-light-reflecting coating  36  may be formed on substrate  34 . Substrate  34  may be a conductive structure in device  10  such as a conductive portion of housing  12  ( FIGS.  1  and  2   ) or a conductive component  32  ( FIG.  2   ). Substrate  34  may be thicker than coating  36 . The thickness of substrate  34  may be 0.1 mm to 5 mm, more than 0.3 mm, more than 0.5 mm, between 5 mm and 20 mm, less than 5 mm, less than 2 mm, less than 1.5 mm, or less than 1 mm (as examples). Substrate  34  may include stainless steel, aluminum, titanium, or other metals or alloys. 
     Coating  36  may include adhesion and transition layers  40  on substrate  34  and one or more uppermost (top) coloring layer(s)  38  on adhesion and transition layers  40 . The composition of coloring layer(s)  38  may configure coating  36  to absorb and reflect light at selected wavelengths to impart coating  36  and thus substrate  34  with a desired color and reflectivity. 
     Coloring layer(s)  38  may, for example, include an intrinsically-colored layer that preferentially absorbs light at particularly wavelengths to reveal the color of the reflected wavelengths to an observer. As an example, coloring layer(s)  38  may include metal nitride, carbide, or carbonitride that provide coating  36  with an intrinsic color (e.g., a titanium silicon nitride color layer). These types of intrinsically-colored layers may exhibit a limited range of possible colors, thereby limiting the aesthetic characteristics of device  10 . 
     In another suitable arrangement, coloring layer(s)  38  may include a thin film interference filter having multiple alternating layers of high and low refractive index materials. Light may reflect off of the interfaces between the layers of the thin film interference filter and the reflected light may constructively and destructively interfere at certain wavelengths to produce reflected light of a particular color and reflectivity for an observer. As an example, the thin film interference filter may include layers of silicon nitride, titanium nitride, zirconium oxide, tantalum oxide, niobium oxide, silicon oxide, aluminum oxide, etc. 
     In practice, it can be difficult to deposit coloring layer(s)  38  as a thin film interference filter with a relatively uniform thickness  42  across the entire layer. Providing coloring layer(s)  38  with a uniform thickness  42  is particularly difficult when substrate  34  has a three-dimensional geometry instead of a planar geometry (e.g., when the coating is deposited on a three-dimensional conductive structure such as an edge or curved portion of housing  12  of  FIGS.  1  and  2   , attachment structures  30  of  FIG.  2   , a three-dimensional conductive component  32  of  FIG.  2    such as a conductive button member, a conductive portion of strap  28 , an audio port for device  10 , a data port for device  10 , a SIM card tray for device  10 , etc.). 
     The reflected color exhibited by these types of thin film interference filters may be highly sensitive to thickness variations across the coating. In general, the thickness  42  of coloring layer(s)  38  may determine the reflective characteristics and thus the perceived visible color of coating  36 . Small variations in thickness  42  across the lateral area of coloring layer(s)  38  can change the local reflectivity of the coating as a function of wavelength, providing the coating and thus substrate  34  with an unattractive, non-uniform color that varies across its area. Coating  36  may be particularly sensitive to these variations when it is desired to provide coating  36  and substrate  34  with a color near the middle of the visible light spectrum. 
     Manufacturing limitations associated with the deposition of coating  36  may cause the coating to exhibit different thicknesses across its area, particularly when substrate  34  is a three-dimensional substrate rather than a planar substrate. This may impart coating  36  with the desired color (e.g., a blue color, a purple color, or other desired colors) in some regions of the coating while imparting coating  36  with other undesired colors (e.g., red-shifted or blue-shifted colors) in other regions. This may cause substrate  34  and thus device  10  to exhibit an unattractive aesthetic appearance. It may therefore be desirable to be able to provide substrate  34  with a coating that imparts the substrate with a desired color (e.g., with a blue color, a purple color, or other desired colors), while also exhibiting a reflective response that is relatively insensitive to thickness variations associated with the process for depositing the coating on the substrate. 
       FIG.  4    is a cross-sectional side view of an illustrative visible-light-reflecting coating that may impart substrate  34  with a desired color while also exhibiting a reflective response that is relatively insensitive to thickness variations. As shown in  FIG.  4   , a coating such as coating  68  may be layered on substrate  34 . 
     The layers of coating  68  may be deposited on substrate  34  using any suitable deposition techniques. Examples of techniques that may be used for depositing the layers in coating  68  include physical vapor deposition (e.g., evaporation and/or sputtering), cathodic arc deposition, chemical vapor deposition, ion plating, laser ablation, etc. For example, coating  68  may be deposited on substrate  34  in a deposition system having deposition equipment (e.g., a cathode). Substrate  34  may be moved (e.g., rotated) within the deposition system while the deposition equipment (e.g., the cathode) deposits the layers of coating  68 . If desired, substrate  34  may be moved/rotated dynamically with respect to speed and/or orientation relative to the deposition equipment (e.g., the cathode) during deposition. This may help provide coating  68  with as uniform a thickness as possible across its area, even in scenarios where substrate  34  has a three-dimensional shape. 
     As shown in  FIG.  4   , coating  68  may include a seed layer such as seed layer  70  and one or more transition layers such as transition layer(s)  72 . Seed layer  70  may couple substrate  34  to the remaining transition layer(s)  72 . Seed layer  70  may include chromium (Cr), chromium silicon (CrSi), titanium (Ti), other metals, metal alloys, and/or other materials. Transition layers  72  may include one or more chromium silicon nitride (CrSiN) layers, chromium silicon carbonitride (CrSiCN) layers, chromium silicon carbide (CrSiC) layers, chromium nitride (CrN) layers, chromium carbonitride (CrCN) layers, and/or any other desired transition layers. 
     Seed layer  70  and transition layer(s)  72  may sometimes be referred to collectively herein as adhesion and transition layers  84 . Adhesion and transition layers  84  may have a thickness  82 . Thickness  82  may, for example, be greater than or equal to 0.1 microns, 0.5 microns, 1 micron, 2 microns, 3 microns, or any other desired thickness (e.g., thickness  82  may be between 0.1 and 4 microns, between 0.5 and 3 microns, etc.). 
     Coating  68  may include a base layer such as neutral-color base layer  74  on adhesion and transition layers  84  (e.g., transition and adhesion layers  74  may couple neutral-color base layer  74  to substrate  34 ). Neutral-color base layer  74  may exhibit a relatively neutral color (e.g., a relatively uniform reflectivity across the visible spectrum) and may be optically opaque. 
     For example, neutral-color base layer  74  may exhibit a lightness value (e.g., an L* value in a CIE L*a*b* (CIELAB or Lab) color space) that is between 65 and 75, between 48 and 82, between 60 and 72, between 65 and 71, between 40 and 76, or other neutral lightness values (e.g., where an L* value of 100 corresponds to white and an L* value of 0 corresponds to black). At the same time, neutral-color base layer  74  may exhibit an |a*| value (e.g., in the L*a*b* color space, where a* is a function of the difference between red and green channels and “| |” is the absolute value operator) that is less than approximately 2 (e.g., an a* value that is −1, 0, 1, 1.5, −1.5, 1.9, 0.5, etc.). Similarly, neutral-color base layer  74  may exhibit a |b*| value (e.g., in the L*a*b* color space, where b* is a function of the difference between blue and green channels) that is less than approximately 2 (e.g., an b* value that is −1, 0, 1, 1.5, −1.5, 1.9, 0.5, etc.). 
     Neutral-color base layer  74  may have thickness  80  and index of refraction n 2 . As an example, neutral-color base layer  74  may be formed from chromium silicon carbonitride (CrSiCN), chromium nitride (CrN), chromium silicon nitride (CrSiN), carbide, carbonitride, other metal nitrides, or other materials. The relative number of chromium, silicon, carbon, and nitrogen atoms in neutral-color base layer  74  (e.g., in scenarios where layer  74  is formed from CrSiCN) may, for example, be selected to provide neutral-color base layer  74  with the desired neutral color profile and the desired index of refraction n 2 . Thickness  80  may be, for example, greater than or equal to 0.1 microns, 0.2 microns, 0.3 microns, 0.4 microns, 0.5 microns, 0.6 microns, 0.7 microns, 0.8 microns, between 0.4 and 0.8 microns, between 0.5 and 0.75 microns, between 0.65 and 0.75 microns, etc. 
     Coating  68  may include an uppermost (top) layer that is formed from a single-layer interference film such as single-layer interference film  76 . Single-layer interference film  76  may include a single layer (film) deposited on neutral-color base layer  74 . Single-layer interference film  76  may have a thickness  78  and an index of refraction n 1  that is different from the index of refraction n 2  of neutral-color base layer  74  and the index of refraction no of air. Index of refraction n 1  may, for example, be greater than no and less than n 2 . If desired, the materials in single-layer interference film  76  may also be configured to absorb some wavelengths of light, such that single-layer interference film  76  has an absorption coefficient k that is less than 1 and greater than 0. 
     Single-layer interference film  76  may form a thin film interference filter for coating  68 . For example, incoming light  44  may reflect off of the exterior surface (interface) of single-layer interference film  76  as reflected light  44 ″. Incoming light  44  may also be refracted and transmitted through single-layer interference film  76 . Because neutral-color base layer  74  exhibits an index of refraction n 2  that is different from the index of refraction n 1  of single-layer interference film  76 , light  44  may also be reflected off of the surface (interface) between single-layer interference film  76  and neutral-color base layer  74  as reflected light  44 ′. Reflected light  44 ′ may be transmitted through single-layer interference film  76  and may constructively and destructively interfere at different wavelengths with reflected light  44 ″. 
     By controlling the thickness  78  of single-layer interference film  76  as well as the optical characteristics of single-layer interference film  76  (e.g., absorption coefficient k and index of refraction n 1 ), reflected light  44 ″ and  44 ′ may destructively and/or constructively interfere at a selected set of wavelengths such that the combination of reflected light  44 ″ and  44 ′ are perceived by an observer with a desired color. As an example, thickness  78  may be between approximately 20 nm and 100 nm (e.g., between 30 nm and 70 nm, between 20 nm and 80 nm, between 35 nm and 75 nm, between 0.05 and 0.07 microns, etc.) to provide the combination of reflected light  44 ″ and  44 ′ with a desired color (e.g., a blue or purple color). Thickness  78  may, for example, be less than thickness  80 . Thickness  80  may be less than, equal to, or greater than thickness  82 . Coating  68  may have a total thickness H. Total thickness H may be, for example, between 1.2 and 1.8 microns, between 1.3 and 1.7 microns, between 1.4 and 1.6 microns, between 1.1 and 1.9 microns, or other thicknesses. 
     The composition of single-layer interference film  76  may also be selected to provide single-layer interference film  76  with a desired index of refraction n 1  and absorption coefficient k that contribute to the observed color response of coating  68  (e.g., to provide single-layer interference film  76  with a non-zero absorption coefficient at some wavelengths that helps to tune the observed color of the combination of reflected light  44 ″ and  44 ′). As examples, single-layer interference film  76  may include metal carbonitrides or carbon-oxynitrides or other materials. 
     Single-layer interference film  76  may, for example, include chromium silicon carbonitride (CrSiCN), as shown in the cross-sectional side view of  FIG.  5   . As shown in  FIG.  5   , single-layer interference film  76  may be a CrSiCN layer. Neutral-color base layer  74  may be a CrSiN layer or a layer formed using other suitable materials. Neutral-color base layer  74  may have thickness  80 . Single-layer interference film  76  may have thickness  78 . The composition of neutral-color base layer  74 , the composition of single-layer interference film  76 , thickness  80 , and/or thickness  78  may be selected to provide coating  68  with a desired visual (observed) color such as a blue color (or any other desired colors). In scenarios where coating  68  is configured to produce a blue color, the composition of single-layer interference film  76  and thickness  78  may have the greatest impact on the reflective color response of coating  68 . 
     As examples, thickness  82  may be between 0.2 and 1.5 microns, between 0.5 and 1.25 microns, between 1.0 and 2.0 microns, between 1.1 and 1.3 microns, between 1.05 and 1.25 microns, between 0.75 and 1.5 microns, greater than 1.0 micron, less than 2.0 microns, etc. Thickness  80  may be between 0.1 and 0.5 microns, between 0.15 and 0.45 microns, between 0.3 and 0.4 microns, between 0.2 and 0.3 microns, between 0.25 and 0.5 microns, between 0.27 and 0.33 microns, between 0.24 and 0.49 microns, greater than 0.2 microns, less than 0.5 microns, less than 1.0 micron, greater than 0.1 micron, or other desired thicknesses. Thickness  78  may be between 0.01 and 0.1 microns, between 0.05 and 0.07 microns, between 0.01 and 0.2 microns, between 0.05 and 0.15 microns, between 0.03 and 0.22 microns, greater than 0.01 microns, greater than 0.05 microns, less than 0.08 microns, less than 0.1 microns, less than 0.2 microns, or other desired thicknesses. 
       FIG.  6    is a plot of illustrative atomic percentages for the different elements in single-layer interference film  76  in examples where single-layer interference film  76  is a CrSiCN layer (e.g., in the configuration of coating  68  as shown in  FIG.  5   , such as a configuration in which coating  68  is configured to exhibit a blue color). As shown in  FIG.  6   , the composition of single-layer interference film  76  may be selected such that the atomic percentage of chromium (Cr) atoms in single-layer interference film  76  lies within region  90  (e.g., a region extending between upper limit A 1  and lower limit A 2 ). The atomic percentage of silicon (Si) atoms in single-layer interference film  76  lies within region  92  (e.g., a region extending between upper limit A 3  and lower limit A 4 ). The atomic percentage of nitrogen (N) atoms in single-layer interference film  76  lies within region  94  (e.g., a region extending between upper limit A 5  and lower limit A 6 ). The atomic percentage of carbon (C) atoms in single-layer interference film  76  lies within region  96  (e.g., a region extending between upper limit A 7  and lower limit A 8 ). 
     In the example of  FIG.  6   , atomic percentage A 1  is greater than atomic percentage A 5 , which is greater than atomic percentage A 3 , which is greater than atomic percentage A 7 , and atomic percentage A 6  is greater than atomic percentage A 2 , which is greater than atomic percentage A 4 , which is greater than atomic percentage A 8 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  90 ,  92 ,  94 , and  96  may have other relative positions along the vertical axis of  FIG.  6    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit A 1  of region  90  (e.g., the upper limit on the atomic percentage of Cr atoms in single-layer interference film  76 ) may be between 30% and 40%, between 34% and 36%, between 31% and 39%, between 33% and 41%, between 35% and 45%, greater than 35%, greater than 30%, or other values. The lower limit A 2  of region  90  (e.g., the lower limit on the atomic percentage of Cr atoms in single-layer interference film  76 ) may be between 30% and 40%, between 20% and 35%, between 25% and 35%, between 30% and 32%, less than 35%, less than 30%, less than 40%, or other values less than upper limit A 1 . 
     The upper limit A 3  of region  92  (e.g., the upper limit on the atomic percentage of Si atoms in film  76 ) may be between 20% and 40%, between 25% and 30%, between 26% and 28%, between 21% and 34%, greater than 25%, greater than 20%, greater than 22%, less than 30%, less than 40%, or other values. The lower limit A 4  of region  92  (e.g., the lower limit on the atomic percentage of Si atoms in film  76 ) may be between 20% and 30%, between 22% and 24%, between 21% and 31%, between 15% and 25%, less than 30%, less than 35%, less than 40%, greater than 20%, greater than 15%, or other values less than upper limit A 3 . 
     The upper limit A 5  of region  94  (e.g., the upper limit on the atomic percentage of N atoms in film  76 ) may be between 30% and 40%, between 35% and 45%, between 36% and 38%, between 31% and 39%, greater than 30%, greater than 35%, greater than 27%, less than 37%, less than 40%, less than 45%, or other values. The lower limit A 6  of region  94  (e.g., the lower limit on the atomic percentage of N atoms in film  76 ) may be between 30% and 40%, between 31% and 45%, between 32% and 34%, greater than 30%, greater than 25%, less than 36%, less than 45%, less than 52%, or other values less than upper limit A 5 . 
     The limits of region  96  may be defined by the balance of atomic percentage remaining in film  76 . For example, the upper limit A 7  of region  96  (e.g., the upper limit on the atomic percentage of C atoms in film  76 ) may be between 10% and 20%, between 12% and 14%, between 5% and 15%, greater than 10%, greater than 5%, greater than 1%, less than 15%, less than 10%, less than 5%, less than 2%, less than 1%, or other values. The lower limit A 8  of region  92  (e.g., the lower limit on the atomic percentage of C atoms in film  76 ) may be between 1% and 2%, between 0.5% and 1.5%, between 0.2% and 1.2%, between 1% and 10%, between 3% and 15%, less than 5%, less than 2%, less than 1%, greater than 0.2%, greater than 0.5%, or other values less than upper limit A 7 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  90 ,  92 ,  94 , and  96  may have other heights, relative positions, and/or relative sizes). 
       FIG.  7    is a plot of illustrative atomic percentages for the different elements in neutral-color base layer  74  in examples where neutral-color base layer  74  is a CrSiN layer (e.g., in the configuration of coating  68  as shown in  FIG.  5   , such as a configuration in which coating  68  is configured to produce a blue color with a CrSiCN single-layer interference film  76 ). As shown in  FIG.  7   , the composition of neutral-color base layer  74  may be selected such that the atomic percentage of Cr atoms in layer  74  lies within region  98  (e.g., a region extending between upper limit B 1  and lower limit B 2 ). The atomic percentage of Si atoms in layer  74  lies within region  100  (e.g., a region extending between upper limit B 3  and lower limit B 4 ). The atomic percentage of N atoms in layer  74  lies within region  102  (e.g., a region extending between upper limit B 5  and lower limit B 6 ). 
     In the example of  FIG.  7   , atomic percentage B 5  is greater than atomic percentage B 1 , which is greater than atomic percentage B 3 , and atomic percentage B 6  is greater than atomic percentage B 2 , which is greater than atomic percentage B 4 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  98 ,  100 , and  102  may have other relative positions along the vertical axis of  FIG.  7    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit B 1  of region  98  (e.g., the upper limit on the atomic percentage of Cr atoms in layer  74 ) may be between 30% and 40%, between 35% and 40%, between 37% and 39%, between 33% and 41%, between 35% and 45%, greater than 35%, greater than 30%, less than 40%, less than 45%, or other values. The lower limit B 2  of region  98  (e.g., the lower limit on the atomic percentage of Cr atoms in layer  74 ) may be between 30% and 40%, between 20% and 35%, between 30% and 35%, between 33% and 35%, less than 35%, less than 30%, less than 40%, or other values less than upper limit B 1 . 
     The upper limit B 3  of region  100  (e.g., the upper limit on the atomic percentage of Si atoms in layer  74 ) may be between 10% and 20%, between 5% and 15%, between 13% and 15%, greater than 10%, greater than 12%, greater than 5%, less than 15%, less than 20%, or other values. The lower limit B 4  of region  100  (e.g., the lower limit on the atomic percentage of Si atoms in layer  74 ) may be between 10% and 20%, between 5% and 20%, between 6% and 14%, between 11% and 13%, less than 14%, less than 15%, less than 20%, less than 10%, greater than 10%, greater than 5%, or other values less than upper limit B 3 . 
     The limits of region  102  may be defined by the balance of atomic percentage remaining in layer  74 . For example, the upper limit B 5  of region  102  (e.g., the upper limit on the atomic percentage of N atoms in layer  74 ) may be between 30% and 60%, between 50% and 59%, between 53% and 55%, greater than 50%, greater than 45%, greater than 40%, less than 60%, less than 70%, less than 55%, less than 52%, less than 50%, or other values. The lower limit B 6  of region  102  (e.g., the lower limit on the atomic percentage of N atoms in layer  74 ) may be between 40% and 50%, between 45% and 51%, between 47% and 49%, between 31% and 60%, less than 50%, less than 52%, less than 45%, greater than 45%, greater than 40%, greater than 50%, or other values less than upper limit B 5 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  98 ,  100 ,  102  may have other heights, relative positions, and/or relative sizes). 
     When configured in this way, coating  68  of  FIG.  5    may exhibit a desired color such as a blue color. As an example, coating  68  of  FIG.  5    may have an L* value between 40 and 60, between 45 and 50, between 46 and 49, between 30 and 60, between 40 and 50, between 35 and 55, between 42 and 49, or other L* values in the CIELAB color space. Coating  68  of  FIG.  5    may, for example, have an a* value between −10 and 0, between −5 and 0, between −4 and −3, between −2 and −5, between −1 and −6, or other a* values in the CIELAB color space. Coating  68  of  FIG.  5    may, for example, have a b* value between −5 and −15, between −8 and −12, between −10 and −11, between −9 and −14, or other b* values in the CIELAB color space. 
     If desired, CrSiN layer  74  of  FIG.  5    may be replaced with a CrSiCN layer (e.g., neutral color base layer  74  may include CrSiCN). In these arrangements, upper limit A 1  may be between 30-40%, between 33-37%, greater than 31%, less than 36%, or other values. Lower limit A 2  may be 30-35%, 25-33%, greater than 30%, less than 35%, or other values less than upper limit A 1 . Upper limit A 5  may be between 35-40%, greater than 35%, less than 40%, or other values. Lower limit A 6  may be between 30-35%, less than 35%, greater than 30%, or other values less than upper limit A 5 . In this example, coating  68  may have an L* value between 40 and 50, between 45 and 50, between 46 and 52, greater than 45, greater than 40, less than 50, less than 55, or other L* values. Coating  68  may have an a* value between −5 and 0, between −4 and −3, between −5 and 5, less than 0, less than −3, greater than −4, greater than −5, or other a* values. Coating  68  may have a b* value between −10 and −15, between −5 and −15, less than −10, greater than −15, greater than −11, or other b* values. 
     If desired, single-layer interference film  76  may, for example, include chromium silicon carbide (CrSiC), as shown in the cross-sectional side view of  FIG.  8   . As shown in  FIG.  8   , single-layer interference film  76  may be a CrSiC layer. Neutral-color base layer  74  may be a CrSiN layer or a layer formed using other suitable materials. The composition of neutral-color base layer  74 , the composition of single-layer interference film  76 , thickness  80 , and/or thickness  78  of coating  68  of  FIG.  8    may have a first configuration selected to provide coating  68  with a first visual (observed) color such as a blue color (or any other desired colors). 
     As examples, thickness  82  may be between 0.2 and 1.5 microns, between 0.5 and 1.25 microns, between 0.5 and 1.5 microns, between 0.6 and 0.8 microns, between 0.55 and 0.75 microns, between 0.25 and 1.0 microns, greater than 0.5 micron, less than 1.5 microns, etc. Thickness  80  may be between 0.5 and 1.5 microns, between 0.9 and 1.1 microns, between 0.3 and 1.4 microns, between 0.2 and 2.3 microns, between 0.25 and 1.5 microns, between 0.97 and 1.13 microns, greater than 0.5 microns, less than 1.5 microns, less than 1.2 microns, greater than 0.8 microns, or other desired thicknesses. Thickness  78  may be between 0.01 and 0.1 microns, between 0.04 and 0.06 microns, between 0.01 and 0.2 microns, between 0.04 and 0.14 microns, between 0.03 and 0.22 microns, greater than 0.01 microns, greater than 0.03 microns, less than 0.07 microns, less than 0.1 microns, less than 0.2 microns, or other desired thicknesses. 
       FIG.  9    is a plot of illustrative atomic percentages for the different elements in single-layer interference film  76  in examples where single-layer interference film  76  is a CrSiC layer that reflects light of the first color (e.g., in the first configuration of coating  68  as shown in  FIG.  8   , where coating  68  is configured to exhibit a blue color). As shown in  FIG.  9   , the composition of single-layer interference film  76  may be selected such that the atomic percentage of Cr atoms in single-layer interference film  76  lies within region  110  (e.g., a region extending between upper limit C 1  and lower limit C 2 ). The atomic percentage of Si atoms in single-layer interference film  76  lies within region  112  (e.g., a region extending between upper limit C 3  and lower limit C 4 ). The atomic percentage of C atoms in single-layer interference film  76  lies within region  114  (e.g., a region extending between upper limit C 5  and lower limit C 6 ). 
     In the example of  FIG.  9   , atomic percentage C 3  is greater than atomic percentage C 1 , which is greater than atomic percentage C 5 , and atomic percentage C 4  is greater than atomic percentage C 2 , which is greater than atomic percentage C 6 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  110 ,  112 , and  114  may have other relative positions along the vertical axis of  FIG.  9    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit C 1  of region  110  (e.g., the upper limit on the atomic percentage of Cr atoms in single-layer interference film  76 ) may be between 30% and 40%, between 28% and 36%, between 31% and 33%, between 20% and 50%, between 27% and 38%, greater than 30%, greater than 25%, less than 40%, less than 35%, or other values. The lower limit C 2  of region  110  (e.g., the lower limit on the atomic percentage of Cr atoms in single-layer interference film  76 ) may be between 20% and 40%, between 20% and 30%, between 27% and 29%, between 25% and 35%, less than 35%, less than 30%, less than 40%, or other values less than upper limit C 1 . 
     The upper limit C 3  of region  112  (e.g., the upper limit on the atomic percentage of Si atoms in film  76 ) may be between 50% and 60%, between 45% and 65%, between 50% and 70%, between 57% and 59%, greater than 55%, greater than 50%, greater than 40%, less than 60%, less than 70%, or other values. The lower limit C 4  of region  112  (e.g., the lower limit on the atomic percentage of Si atoms in film  76 ) may be between 50% and 60%, between 45% and 55%, between 51% and 53%, between 41% and 57%, less than 60%, less than 55%, less than 70%, greater than 45%, greater than 50%, or other values less than upper limit C 3 . 
     The upper limit C 5  of region  114  (e.g., the upper limit on the atomic percentage of C atoms in film  76 ) may be between 10% and 20%, between 13% and 15%, between 8% and 18%, between 5% and 15%, greater than 10%, greater than 5%, greater than 13%, less than 15%, less than 20%, less than 35%, or other values. The lower limit C 6  of region  114  (e.g., the lower limit on the atomic percentage of C atoms in film  76 ) may be between 10% and 20%, between 10% and 15%, between 7% and 13%, between 11% and 13%, greater than 10%, greater than 5%, less than 15%, less than 20%, less than 25%, or other values less than upper limit C 5 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  110 ,  112 , and  114  may have other heights, relative positions, and/or relative sizes). 
       FIG.  10    is a plot of illustrative atomic percentages for the different elements in neutral-color base layer  74  in examples where neutral-color base layer  74  is a CrSiN layer (e.g., in the first configuration of coating  68  as shown in  FIG.  8   , where coating  68  is configured to exhibit a blue color with a CrSiC single-layer interference film  76 ). As shown in  FIG.  10   , the composition of neutral-color base layer  74  may be selected such that the atomic percentage of Cr atoms in layer  74  lies within region  122  (e.g., a region extending between upper limit D 1  and lower limit D 2 ). The atomic percentage of Si atoms in layer  74  lies within region  124  (e.g., a region extending between upper limit D 3  and lower limit D 4 ). The atomic percentage of N atoms in layer  74  lies within region  126  (e.g., a region extending between upper limit D 5  and lower limit D 6 ). 
     In the example of  FIG.  10   , atomic percentage D 1  is greater than atomic percentage D 3 , which is greater than atomic percentage D 5 , and atomic percentage D 2  is greater than atomic percentage D 4 , which is greater than atomic percentage D 6 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  122 ,  124 , and  126  may have other relative positions along the vertical axis of  FIG.  10    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit D 1  of region  122  (e.g., the upper limit on the atomic percentage of Cr atoms in layer  74 ) may be between 60% and 70%, between 55% and 65%, between 61% and 63%, between 50% and 70%, between 51% and 67%, greater than 60%, greater than 50%, less than 70%, less than 75%, or other values. The lower limit D 2  of region  122  (e.g., the lower limit on the atomic percentage of Cr atoms in layer  74 ) may be between 50% and 60%, between 55% and 57%, between 55% and 65%, between 49% and 57%, less than 60%, less than 70%, less than 75%, or other values less than upper limit D 1 . 
     The upper limit D 3  of region  124  (e.g., the upper limit on the atomic percentage of Si atoms in layer  74 ) may be between 20% and 30%, between 24% and 26%, between 17% and 28%, greater than 20%, greater than 22%, greater than 15%, less than 30%, less than 35%, or other values. The lower limit D 4  of region  124  (e.g., the lower limit on the atomic percentage of Si atoms in layer  74 ) may be between 20% and 30%, between 20% and 22%, between 16% and 24%, between 11% and 33%, less than 24%, less than 25%, less than 30%, less than 40%, greater than 10%, greater than 20%, or other values less than upper limit D 3 . 
     The limits of region  126  may be defined by the balance of atomic percentage remaining in layer  74 . For example, the upper limit D 5  of region  126  (e.g., the upper limit on the atomic percentage of N atoms in layer  74 ) may be between 20% and 30%, between 22% and 24%, between 15% and 25%, greater than 20%, greater than 15%, greater than 10%, less than 25%, less than 30%, less than 35%, less than 32%, less than 40%, or other values. The lower limit D 6  of region  126  (e.g., the lower limit on the atomic percentage of N atoms in layer  74 ) may be between 10% and 20%, between 12% and 14%, between 8% and 17%, between 5% and 25%, less than 15%, less than 20%, less than 25%, greater than 10%, greater than 5%, greater than 8%, or other values less than upper limit D 5 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  122 ,  124 ,  126  may have other heights, relative positions, and/or relative sizes). 
     In another suitable arrangement, the composition of neutral-color base layer  74 , the composition of single-layer interference film  76 , thickness  80 , and/or thickness  78  in the arrangement of  FIG.  8    may have a second configuration selected to provide coating  68  with a second visual (observed) color such as a purple color. 
     As examples, thickness  82  may be the same as in scenarios where coating  68  of  FIG.  8    is configured to exhibit the first color (e.g., a blue color). Similarly, thickness  82  may be the same as in scenarios where coating  68  of  FIG.  8    is configured to exhibit the first color (e.g., a blue color). However, thickness  78  may be between 0.03 and 0.04 microns, between 0.034 and 0.036 microns, between 0.01 and 0.04 microns, between 0.02 and 0.039 microns, between 0.025 and 0.075 microns, between 0.2 and 1.0 microns, greater than 0.03 microns, greater than 0.02 microns, less than 0.04 microns, or other desired thicknesses. 
     Returning to  FIG.  9   , when coating  68  of  FIG.  8    is configured to exhibit the second (e.g., purple) color, the composition of single-layer interference film  76  may be selected such that the atomic percentage of Cr atoms in single-layer interference film  76  lies within region  116  (e.g., a region extending between upper limit C 7  and lower limit C 8 ), the atomic percentage of Si atoms in single-layer interference film  76  lies within region  118  (e.g., a region extending between upper limit C 9  and lower limit C 10 ), and the atomic percentage of C atoms in single-layer interference film  76  lies within region  120  (e.g., a region extending between upper limit C 11  and lower limit C 12 ). 
     In the example of  FIG.  9   , atomic percentage C 7  is greater than atomic percentage C 9 , which is greater than atomic percentage C 11 , and atomic percentage C 8  is greater than atomic percentage C 10 , which is greater than atomic percentage C 12 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  116 ,  118 , and  120  may have other relative positions along the vertical axis of  FIG.  9    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit C 7  of region  116  (e.g., the upper limit on the atomic percentage of Cr atoms in single-layer interference film  76 ) may be between 50% and 60%, between 56% and 58%, between 53% and 59%, between 45% and 65%, between 51% and 58%, greater than 55%, greater than 50%, less than 60%, less than 65%, or other values. The lower limit C 8  of region  116  (e.g., the lower limit on the atomic percentage of Cr atoms in single-layer interference film  76 ) may be between 50% and 60%, between 45% and 55%, between 41% and 62%, between 45% and 52%, less than 55%, less than 60%, less than 65%, or other values less than upper limit C 7 . 
     The upper limit C 9  of region  118  (e.g., the upper limit on the atomic percentage of Si atoms in film  76 ) may be between 30% and 40%, between 35% and 37%, between 25% and 40%, between 31% and 39%, greater than 35%, greater than 30%, greater than 25%, less than 40%, less than 50%, or other values. The lower limit C 10  of region  118  (e.g., the lower limit on the atomic percentage of Si atoms in film  76 ) may be between 30% and 40%, between 31% and 33%, between 26% and 33%, between 21% and 37%, less than 35%, less than 40%, less than 50%, greater than 30%, greater than 25%, or other values less than upper limit C 9 . 
     The upper limit C 11  of region  120  (e.g., the upper limit on the atomic percentage of C atoms in film  76 ) may be between 1% and 10%, between 2% and 15%, between 3% and 18%, between 5% and 10%, between 8% and 10%, greater than 5%, greater than 2%, greater than 6%, less than 10%, less than 15%, less than 30%, or other values. The lower limit C 12  of region  120  (e.g., the lower limit on the atomic percentage of C atoms in film  76 ) may be between 1% and 10%, between 1% and 8%, between 6% and 8%, between 2% and 13%, greater than 5%, greater than 1%, less than 10%, less than 8%, less than 15%, or other values less than upper limit C 11 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  116 ,  118 , and  120  may have other heights, relative positions, and/or relative sizes). Region  116  may have any desired position and size relative to region  110 , region  112  may have any desired position and size relative to region  118 , and region  114  may have any desired position and size relative to region  120 . 
     As shown in  FIG.  10   , when coating  68  of  FIG.  8    is configured to exhibit the second (e.g., purple) color, the composition of neutral-color base layer  74  may be selected such that the atomic percentage of Cr atoms in layer  74  lies within region  128  (e.g., a region extending between upper limit D 7  and lower limit D 8 ), the atomic percentage of Si atoms in layer  74  lies within region  130  (e.g., a region extending between upper limit D 9  and lower limit D 10 ), and the atomic percentage of N atoms in layer  74  lies within region  132  (e.g., a region extending between upper limit D 11  and lower limit D 12 ). 
     In the example of  FIG.  10   , atomic percentage D 7  is greater than atomic percentage D 9 , which is greater than atomic percentage D 11 , and atomic percentage D 8  is greater than atomic percentage D 10 , which is greater than atomic percentage D 12 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  128 ,  130 , and  132  may have other relative positions along the vertical axis of  FIG.  10    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit D 7  of region  128  (e.g., the upper limit on the atomic percentage of Cr atoms in layer  74 ) may be between 65% and 75%, between 69% and 71%, between 60% and 80%, between 45% and 75%, greater than 65%, greater than 55%, less than 70%, less than 75%, or other values. The lower limit D 8  of region  128  (e.g., the lower limit on the atomic percentage of Cr atoms in layer  74 ) may be between 60% and 70%, between 60% and 65%, between 61% and 63%, between 51% and 71%, less than 65%, less than 70%, less than 75%, greater than 55%, greater than 60%, or other values less than upper limit D 7 . 
     The upper limit D 9  of region  130  (e.g., the upper limit on the atomic percentage of Si atoms in layer  74 ) may be between 20% and 30%, between 21% and 23%, between 17% and 28%, greater than 20%, greater than 22%, greater than 15%, less than 30%, less than 25%, or other values. The lower limit D 10  of region  130  (e.g., the lower limit on the atomic percentage of Si atoms in layer  74 ) may be between 10% and 20%, between 10% and 25%, between 17% and 19%, between 11% and 33%, less than 20%, less than 25%, less than 30%, less than 40%, greater than 10%, greater than 15%, or other values less than upper limit D 9 . 
     The limits of region  132  may be defined by the balance of atomic percentage remaining in layer  74 . For example, the upper limit D 11  of region  132  (e.g., the upper limit on the atomic percentage of N atoms in layer  74 ) may be between 15% and 25%, between 18% and 24%, between 19% and 21%, greater than 15%, greater than 10%, greater than 5%, less than 25%, less than 30%, less than 35%, less than 32%, less than 40%, or other values. The lower limit D 12  of region  132  (e.g., the lower limit on the atomic percentage of N atoms in layer  74 ) may be between 1% and 10%, between 5% and 15%, between 7% and 9%, less than 10%, less than 15%, less than 25%, greater than 5%, greater than 2%, or other values less than upper limit D 11 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  128 ,  130 ,  132  may have other heights, relative positions, and/or relative sizes). Region  128  may have any desired position and size relative to region  122 , region  124  may have any desired position and size relative to region  130 , and region  126  may have any desired position and size relative to region  132 . Neutral-color base layer  74  may be formed using other elements in any of these configurations if desired. 
     When configured to exhibit the first color (e.g., the blue color), coating  68  of  FIG.  8    may, for example, have an L* value between 40 and 60, between 45 and 55, between 50 and 60, between 50 and 51, between 49 and 52, between 48 and 53, between 50 and 52, or other L* values in the CIELAB color space. Coating  68  of  FIG.  8    may, for example, have an a* value between −10 and 0, between −5 and 0, between −4 and −2, between −1 and −5, between −1 and −4, between −2.5 and −3.5, or other a* values in the CIELAB color space. Coating  68  of  FIG.  8    may, for example, have a b* value between −5 and −15, between −10 and −14, between −12 and −13, between −11 and −14, or other b* values in the CIELAB color space. 
     When configured to exhibit the second color (e.g., the purple color), coating  68  of  FIG.  8    may, for example, have an L* value between 30 and 40, between 35 and 45, between 35 and 40, between 36 and 39, between 35 and 38, or other L* values in the CIELAB color space. Coating  68  of  FIG.  8    may, for example, have an a* value between 0 and 10, between 0 and 5, between 2 and 4, between 1 and 4, between 2 and 3, between 2.5 and 3.5, or other a* values in the CIELAB color space. Coating  68  of  FIG.  8    may, for example, have a b* value between −5 and −15, between −5 and −10, between −7 and −8, between −6 and −9, or other b* values in the CIELAB color space. 
     The example of  FIGS.  4 - 10    in which coating  68  includes a single-layer interference film  76  is merely illustrative. In another suitable arrangement, single-layer interference film  76  of  FIGS.  4 - 10    may be replaced by a multi-layer thin film interference filter (e.g., a filter having multiple stacked films of alternating refractive indices, etc.) that provides coating  68  with a desired visible color. 
     If desired, neutral-color base layer  74  and single-layer interference film  76  may be replaced by a color layer, as shown in the cross-sectional side view of  FIG.  11   . As shown in  FIG.  11   , coating  68  may include adhesion and transition layers  84  and color layer  140  on adhesion and transition layers  84 . Color layer  140  may be an intrinsically-colored layer that preferentially absorbs light at particularly wavelengths to reveal the color of the reflected wavelengths to an observer. Adhesion and transition layers  84  may include seed layer  70  (e.g., a Cr seed layer) and transition layer  72  (e.g., a CrN transition layer). Color layer  140  may be a titanium silicon nitride (TiSiN) layer, as one example. Seed layer  70  has thickness  146  whereas transition layer  72  has thickness  144 . Color layer  140  has thickness  142 . 
     As examples, thickness  142  may be between 0.2 and 0.6 microns, between 0.3 and 0.5 microns, between 0.1 and 1.0 microns, between 0.1 and 0.5 microns, between 0.35 and 0.75 microns, greater than 0.3 microns, greater than 0.1 microns, less than 0.5 microns, less than 0.8 microns, etc. Thickness  144  may be between 0.5 and 1.5 microns, between 0.7 and 1.1 microns, between 0.3 and 1.4 microns, between 0.2 and 2.3 microns, between 0.25 and 1.5 microns, between 0.57 and 1.13 microns, greater than 0.5 microns, greater than 0.7 microns, less than 1.5 microns, less than 1.2 microns, greater than 0.8 microns, or other desired thicknesses. Thickness  146  may be between 0.1 and 0.3 microns, between 0.05 and 0.36 microns, greater than 0.1 microns, greater than 0.05 microns, less than 0.27 microns, less than 0.3 microns, or other desired thicknesses. 
       FIG.  12    is a plot of illustrative atomic percentages for the different elements in color layer  140 . As shown in  FIG.  12   , the composition of color layer  140  may be selected such that the atomic percentage of titanium (Ti) atoms in color layer  140  lies within region  150  (e.g., a region extending between upper limit E 1  and lower limit E 2 ). The atomic percentage of Cr atoms in color layer  140  lies within region  152  (e.g., a region extending between upper limit E 3  and lower limit E 4 ). The atomic percentage of N atoms in color layer  140  lies within region  154  (e.g., a region extending between upper limit E 5  and lower limit E 6 ). 
     In the example of  FIG.  12   , atomic percentage E 1  is greater than atomic percentage E 5 , which is greater than atomic percentage E 3 , and atomic percentage E 2  is greater than atomic percentage E 6 , which is greater than atomic percentage E 4 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  150 ,  152 , and  154  may have other relative positions along the vertical axis of  FIG.  12    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit E 1  of region  150  (e.g., the upper limit on the atomic percentage of Ti atoms in color layer  140 ) may be between 50% and 60%, between 45% and 65%, between 54% and 56%, between 52% and 60%, greater than 50%, greater than 45%, less than 60%, less than 75%, or other values. The lower limit E 2  of region  150  (e.g., the lower limit on the atomic percentage of Ti atoms in color layer  140 ) may be between 50% and 60%, between 45% and 55%, between 50% and 52%, between 41% and 59%, less than 55%, less than 60%, less than 52%, or other values less than upper limit E 1 . 
     The upper limit E 3  of region  152  (e.g., the upper limit on the atomic percentage of Cr atoms in color layer  140 ) may be between 10% and 20%, between 12% and 16%, between 13% and 15%, between 5% and 25%, greater than 10%, greater than 12%, greater than 5%, less than 15%, less than 20%, or other values. The lower limit E 4  of region  152  (e.g., the lower limit on the atomic percentage of Cr atoms in color layer  140 ) may be between 5% and 15%, between 9% and 11%, between 6% and 13%, less than 12%, less than 15%, less than 20%, greater than 5%, greater than 8%, or other values less than upper limit E 3 . 
     The upper limit E 5  of region  154  (e.g., the upper limit on the atomic percentage of N atoms in color layer  140 ) may be between 30% and 40%, between 35% and 45%, between 38% and 40%, between 25% and 45%, greater than 35%, greater than 30%, greater than 25%, less than 40%, less than 45%, less than 50%, or other values. The lower limit E 6  of region  154  (e.g., the lower limit on the atomic percentage of N atoms in color layer  140 ) may be between 30% and 40%, between 30% and 32%, between 27% and 33%, between 21% and 43%, greater than 30%, greater than 25%, less than 35%, less than 40%, less than 45%, or other values less than upper limit E 5 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  150 ,  152 , and  154  may have other heights, relative positions, and/or relative sizes). 
       FIG.  13    is a plot of illustrative atomic percentages for the different elements in the CrN transition layer  72  of  FIG.  11   . As shown in  FIG.  13   , the composition of transition layer  72  may be selected such that the atomic percentage of Cr atoms in layer  72  lies within region  156  (e.g., a region extending between upper limit F 1  and lower limit F 2 ). The atomic percentage of N atoms in layer  72  lies within region  158  (e.g., a region extending between upper limit F 3  and lower limit F 4 ). In the example of  FIG.  13   , atomic percentage F 1  is greater than atomic percentage F 3  and atomic percentage F 2  is greater than atomic percentage F 4 . This is merely illustrative and, in general, these percentages may have other relative magnitudes. Regions  156  and  158  may have other relative positions along the vertical axis of  FIG.  13    and may have other relative sizes (e.g., where the size of each region is determined by the difference between its corresponding upper and lower limits). 
     As an example, the upper limit F 1  of region  156  (e.g., the upper limit on the atomic percentage of Cr atoms in layer  72 ) may be between 90% and 99%, between 85% and 99%, between 92% and 98%, greater than 90%, greater than 85%, less than 96%, less than 99%, or other values. The lower limit F 2  of region  156  (e.g., the lower limit on the atomic percentage of Cr atoms in layer  72 ) may be between 90% and 99%, between 90% and 95%, between 92% and 94%, less than 95%, less than 90%, or other values less than upper limit F 1 . 
     The upper limit F 3  of region  158  (e.g., the upper limit on the atomic percentage of N atoms in layer  74 ) may be between 1% and 10%, between 5% and 10%, between 6% and 8%, greater than 5%, greater than 3%, less than 10%, less than 15%, or other values. The lower limit F 4  of region  158  (e.g., the lower limit on the atomic percentage of N atoms in layer  72 ) may be between 1% and 10%, between 4% and 6%, between 2% and 7%, between 1% and 8%, less than 10%, less than 15%, greater than 3%, greater than 1%, or other values less than upper limit F 3 . These examples are merely illustrative and, in general, other atomic percentages of these elements may be used (e.g., regions  156  and  158  may have other heights, relative positions, and/or relative sizes). 
     When configured in this way, coating  68  of  FIG.  11    may exhibit a desired color. As an example, coating  68  of  FIG.  11    may have an L* value between 70 and 80, between 75 and 80, between 60 and 85, between 76 and 78, between 55 and 85, or other L* values in the CIELAB color space. Coating  68  of  FIG.  11    may, for example, have an a* value between 0 and 10, between 0 and 5, between 0 and 1, between 0.5 and 1, between 0 and 3, or other a* values in the CIELAB color space. Coating  68  of  FIG.  11    may, for example, have a b* value between 10 and 15, between 13 and 15, between 11 and 16, between 5 and 15, or other b* values in the CIELAB color space. In another implementation, color layer  140  may be a titanium chromium nitride (TiCrN) layer and/or may be an intrinsically colored layer rather than a single-layer thin film interference filter. 
     The examples of  FIGS.  4 - 13    are merely illustrative. In another suitable arrangement, single-layer interference film  76  may be a CrSiN layer (film) whereas neutral-color base layer  74  is also a CrSiN layer (film) (e.g., with different atomic composition ratios between layers  76  and  74 ). In another suitable arrangement, single-layer interference film  76  may be a CrSiN layer whereas neutral-color base layer  74  is a CrSiC layer. In another suitable arrangement, single-layer interference film  76  may be a CrSiC layer whereas neutral-color base layer  74  is also a CrSiC layer (e.g., with different atomic composition ratios between layers  76  and  74 ). In another suitable arrangement, single-layer interference film  76  may be a CrSiCN layer whereas neutral-color base layer  74  is a CrSiC layer. In another suitable arrangement, single-layer interference film  76  may be a CrSiN layer whereas neutral-color base layer  74  is a CrSiCN layer. In another suitable arrangement, single-layer interference film  76  may be a CrSiC layer whereas neutral-color base layer  74  is a CrSiCN layer. In yet another suitable arrangement, single-layer interference film  76  may be a CrSiCN layer whereas neutral-color base layer  74  is also a CrSiCN layer (e.g., with different atomic composition ratios between layers  76  and  74 ). These examples are also merely illustrative. If desired, the Cr atoms in any of these layers may be replaced by Ti or zirconium (Zr) atoms. For example, in another suitable arrangement, single-layer interference film  76  may be a TiSiN layer (film) or a ZrSiN layer whereas neutral-color base layer  74  is also a TiSiN layer (film) or a ZrSiN (e.g., with different atomic composition ratios between layers  76  and  74 ). In another suitable arrangement, single-layer interference film  76  may be a TiSiN layer or a ZrSiN layer whereas neutral-color base layer  74  is a TiSiC or a ZrSiC layer. In another suitable arrangement, single-layer interference film  76  may be a TiSiC layer or a ZrSiC layer whereas neutral-color base layer  74  is also a TiSiC layer or a ZrSiC (e.g., with different atomic composition ratios between layers  76  and  74 ). In another suitable arrangement, single-layer interference film  76  may be a TiSiCN layer or a ZrSiCN layer whereas neutral-color base layer  74  is a TiSiC layer or a ZrSiC layer. In another suitable arrangement, single-layer interference film  76  may be a TiSiN layer or a ZrSiN layer whereas neutral-color base layer  74  is a TiSiCN layer or a ZrSiCN layer. In another suitable arrangement, single-layer interference film  76  may be a TiSiC layer or a ZrSiC layer whereas neutral-color base layer  74  is a TiSiCN layer or a ZrSiCN layer. In yet another suitable arrangement, single-layer interference film  76  may be a TiSiCN layer or a ZrSiCN layer whereas neutral-color base layer  74  is also a TiSiCN layer or a ZrSiCN layer (e.g., with different atomic composition ratios between layers  76  and  74 ). Any combination of these arrangements for layers  74  and  76  may be used if desired. 
     Coating  68  may exhibit minimal variation in reflected color even as the overall thickness H varies (e.g., due manufacturing tolerances associated with the deposition of coating  68  on substrate  34 ). In other words, even if the deposition equipment used to deposit coating  68  on substrate  34  exhibits a variation in thickness H of up to 10% across the area of the coating on substrate  34 , the color reflected by coating  68  may change by an amount dE that is less than a threshold value over the range of wavelengths that provide the coating with the desired color. In this way, even if coating  68  has different thicknesses across substrate  34  (e.g., in scenarios where substrate  34  is a three-dimensional substrate and/or where the deposition equipment used to deposit the coating is incapable of providing the coating with a precise thickness), coating  68  may still provide substrate  34  with a desired visible color across the entire area of the substrate. This may allow substrate  34  to exhibit an attractive uniform color that maximizes the aesthetic appearance of substrate  34 . 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20210216
Publication Date: 20230808
Grant Date: 20230808
Priority Date: 20200311
Inventors: TRYON, BRIAN S.
BAO, LIJIE
MELCHER, MARTIN
POSTAK, Sonja R.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B5/0833", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/286", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/0808", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/286", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/0833", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/286", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/0015", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/0635", "inventive": true, "first": false, "tree": "[]"}, {"code": "C23C14/0641", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0283", "inventive": false, "first": false, "tree": "[]"}, {"code": "C23C14/024", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/286", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 74874620