PLANAR SURFACES

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 62/511,036, filed on May 25, 2017, the content of which is relied upon and incorporated herein by reference in its entirety.

Field

[0002] The present disclosure relates generally to methods and apparatuses for adhesion force measurement between planar surfaces and more particularly to adhesion force measurement between planar surfaces under variable loading conditions.

Background

[0003] Flat surfaces in intimate contact with one another often adhere due to several types of material interactions. Depending on the material system involved as well as geometric and/or configurational factors, the force required to separate the two surfaces can vary from miniscule to very significant. This can pose significant challenges in flat panel display manufacturing processes, where dimensionally-large, highly flat and thin glass substrates routinely come into contact with equally large, flat surfaces, such as metal surfaces, which typically serve as vacuum chucks or susceptors in vacuum processing equipment. In certain circumstances, removing these surfaces from each other can require forces in excess of the glass surface strength resulting in failure. In addition, factors such as surface materials, surface roughness, and atmospheric conditions (e.g., humidity, etc.) can affect adhesion forces between planar surfaces. While there are surface engineering methods that can mitigate these effects, in order to study adhesion forces accurately, there is a continuing need for improved measurement techniques involving robust simulation of actual process conditions.

SUMMARY

[0004] Embodiments disclosed herein include an apparatus for measuring adhesion force between planar surfaces. The apparatus includes a substrate contacting component that includes a planar surface that includes at least one opening or channel indented into the planar surface. The at least one opening or channel is in fluid communication with a vacuum source. The apparatus also includes a force measurement gauge. The apparatus and a substrate having a planar surface are configured to move relative to each other from at least a first position, wherein the planar surface of the substrate contacting component and the planar surface of the substrate are not in contact, to at second position, wherein the planar surface of the substrate contacting component and the planar surface of the substrate contact each other. While in the second position, at least a partial vacuum is generated in the at least one opening or channel. In addition, the apparatus and the substrate are configured to move relative to each other from the second position to a third position, wherein the planar surface of the substrate contacting component and the planar surface of the substrate are not in contact. The apparatus is also configured to enable determination of an adhesion force between the planar surface of the substrate contacting component and the planar surface of the substrate as a result of movement between the second position and the third position.

[0005] Embodiments disclosed herein also include a method for measuring adhesion force between planar surfaces. The method includes moving an apparatus and a substrate having a planar surface relative to each other from at least a first position to a second position. The apparatus includes a force measurement gauge and a substrate contacting component that includes a planar surface that includes at least one opening or channel indented into the planar surface. The at least one opening or channel is in fluid communication with a vacuum source. The planar surface of the substrate contacting component and the planar surface of the substrate are not in contact in the first position. The method also includes, when in the second position, generating at least a partial vacuum in the at least one opening or channel. In addition, the method includes moving the apparatus and the substrate to a third position , wherein the planar surface of the substrate contacting component and the planar surface of the substrate are not in contact. The method also includes determining an adhesion force between the planar surface of the substrate contacting component and the planar surface of the substrate as a result of movement between the second position and the third position.

[0006] Additional features and advantages of the embodiments disclosed herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the disclosed embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings. [0007] It is to be understood that both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and character of the claimed embodiments. The accompanying drawings are included to provide further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description serve to explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic perspective view of an example adhesion force measurement apparatus according to embodiments disclosed herein;

[0009] FIG. 2 is a side cutaway view of the apparatus of FIG. 1;

[0010] FIG. 3A is a bottom perspective view of a planar surface of a substrate contacting component of the apparatus of FIG. 1, wherein a plurality of parallel channels are indented into the planar surface;

[0011] FIG. 3B is a bottom perspective view of an alternate planar surface of a substrate contacting component, wherein a channel indented into the planar surface includes a section that is perpendicular to at least one other section of the channel;

[0012] FIGS. 4A to 4C are side perspective views of a substrate contacting component and a substrate moving relative to each other between first, second, and third, positions;

[0013] FIG. 5 is a chart showing total load as a function of time as an adhesion force measurement apparatus and a substrate are moved relative to each other between, first, second, and third positions;

[0014] FIG. 6 is a chart showing an exploded view of total load as a function of time as an adhesion force measurement apparatus and a substrate are moved relative to each other between first and second positions;

[0015] FIG. 7 is a chart showing an exploded view of total load as a function of time as an adhesion force measurement apparatus and a substrate are moved relative to each other between second and third positions; and

[0016] FIGS. 8A and 8B are, respectively, side and bottom perspective views of a substrate contacting component that includes a detachable subcomponent comprising a plurality of through holes and a planar surface having a layer of material positioned thereon. DETAILED DESCRIPTION

[0017] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0018] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, for example by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0019] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0020] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0021] As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components, unless the context clearly indicates otherwise. [0022] As used herein, the term "vacuum source" refers to a source capable of generating at least a partial vacuum in an apparatus, system, or component that is in fluid communication with the vacuum source.

[0023] FIG. 1 shows a schematic perspective view of an example adhesion force measurement apparatus 100 according to embodiments disclosed herein and FIG. 2 shows a side cutaway view of the apparatus 100 shown in FIG. 1. Apparatus 100 includes a substrate contacting component 106 having a planar surface 102. Substrate contacting component 106 is rigidly coupled with stabilizing component 116 via connecting pins 118. Stabilizing component 1 16 is, in turn, coupled with bracket 124 via threaded engagement members 120 and 122.

[0024] FIG. 3A shows a bottom perspective view the planar surface 102 of the substrate contacting component 106 of apparatus 100 shown in FIGS. 1 and 2. In the embodiment illustrated in FIG. 3 A, a plurality of parallel channels 104 are indented into the planar surface 102.

[0025] FIG. 3B shows a bottom perspective view of an alternate planar surface 102' of a substrate contacting component 106', wherein a channel 104' having a section that is perpendicular to at least one other section of the channel 104' is indented into the planar surface 102' . The channel 104' also includes a section that is parallel to at least other section of the channel 104' . Channel 104' can also be characterized as including a larger rectangular section surrounding a smaller rectangular section wherein the rectangular sections are connected by four intersecting connecting sections.

[0026] In certain exemplary embodiments, planar surface 102, 102' comprises a metal, such as at least one of aluminum, steel, and brass. Planar surface may also comprise non-metallic materials, such as ceramics or plastics.

[0027] In certain exemplary embodiments, planar surface 102, 102' can have an area of from about 5,000 square millimeters to about 500,000 square millimeters.

[0028] In certain exemplary embodiments, channels 104, 104' may be formed in the planar surface 102, 102' by one or more methods such as, for example, mechanical cutting (e.g., machining), laser cutting, or molding the planar surface 102, 102' to include the channels 104, 104' . The depth of the channels 104, 104', while not limited can range from about 0.5 millimeters to about 1 millimeter. The width of the channels 104, 104', while not limited, can range from about 0.5 millimeters to about 1 millimeter. The length of the channels 104, 104', while not limited, can range from about 10 millimeters to about 120 millimeters. [0029] As shown in FIGS. 1 and 2, apparatus 100 further includes a vacuum line 108 and vacuum chamber 110 that enable channels 104, 104' to be in fluid communication with a vacuum source (not shown). Vacuum source can be operated so as to vary a partial vacuum generated in channels 104, 104' when planar surface 102, 102' contacts an object, such as a substrate, having a planar surface.

[0030] Apparatus, 100 further includes a force measurement gauge 112 that can be in electrical communication with, for example, a data processing unit (not shown) via lead line 114. In certain exemplary embodiments, force measurement gauge 112 can comprise a load cell. The load cell can, for example, be an integrated uni-directional load cell that is calibrated in both tension and compression modes, as known to persons of ordinary skill in the art. Exemplary commercially available load cells include those available from FUTEK Advanced Sensor Technology, Inc., OMEGA Engineering, and Transducer Techniques.

[0031] FIGS. 4A-4C show side perspective views of substrate contacting component 106 of apparatus 100 and a substrate 200 moving relative to each other between first, second, and third, positions, respectively. Specifically, FIG. 4A shows a side perspective view of relative movement of substrate contacting component 106 of apparatus 100 and substrate 200 comprising planar surface 202 from a first position to a second position. As shown in FIG. 4A, planar surface 102 of substrate contacting component 106 and planar surface 202 of substrate 200 are not in contact with each other but are moving relatively closer to each other, as shown by arrows A and B.

[0032] In FIG. 4B, apparatus 100, including substrate contacting component 106, and substrate 200 are shown in a second position, wherein planar surface 102 of substrate contacting component 106 and planar surface 202 of substrate 200 contact each other. While in this second position, at least a partial vacuum can be generated in at least one channel (e.g., 104, 104' as shown in FIGS. 3 A and 3B) through operation of vacuum source through vacuum line 108 and vacuum chamber 110.

[0033] FIG. 4C shows a side perspective view of relative movement of substrate contacting component 106 of apparatus 100 and substrate 200 comprising planar surface 202 from a second position to a third position. As shown in FIG. 4C, planar surface 102 of substrate contacting component 106 and planar surface 202 of substrate 200 are not in contact with each other and are moving relatively farther from each other, as shown by arrows A and B.

[0034] As shown in FIGS. 4A-4C surface area of planar surface 202 of substrate 200 is shown as being larger than the surface area of planar surface 102 of substrate contacting component 106. However, embodiments disclosed herein include those in which planar surface 202 of substrate 200 and planar surface 102 of substrate contacting component 106 are different relative sizes than are shown in FIGS. 4A-4C, such as where planar surface 202 of substrate 200 and planar surface 102 of substrate contacting component 106 have approximately the same area or where planar surface 102 of substrate contacting component 106 has a larger surface area than planar surface 202 of substrate 200. Accordingly, apparatus 100 can be used to determine adhesion forces of substrates having varying surface areas.

[0035] Relative movement between apparatus 100 and substrate 200 can occur via movement of one or both of apparatus 100 and substrate 200. For example, in certain exemplary embodiments, apparatus 100 may move toward and away from substrate 200 while substrate 200 remains stationary. Alternatively, in certain exemplary embodiments, substrate 200 may move toward and away from apparatus 100 while apparatus 100 remains stationary. In addition, in certain exemplary embodiments, apparatus 100 and substrate 200 may both move toward and away from each other.

[0036] For example, embodiments disclosed herein include those in which apparatus 100 is integrated into a larger platform or system, such as, for example, a system that examines additional characteristics of substrates, including, for example, a system that is used to measure electrostatic charge on substrates, as described in U.S. application serial no.

62/262,638, the entire disclosure of which is incorporated herein by reference. Such system may be humidity controlled according to methods known by persons having ordinary skill in the art.

[0037] In such embodiments, substrate 200 may be mounted on a mounting platform and optionally secured to the platform using any suitable fastening mechanism, such as clamps, vacuum chucking, and other similar components or methods, or combinations thereof. The mounting platform may, in turn, be included in an assembly platform that can be used to, among other things, position the mounting platform and the apparatus 100 relative to each other.

[0038] For example, in some embodiments, apparatus 100 may be removably secured via bracket 124 to a multi-axis actuator, which can be positioned proximate (e.g., above) the mounting platform and actuated to provide three-dimensional motion relative to the mounting platform, such as through the combination of a motor, such as a servo motor, and a positioning sensor. The multi-axis actuator can further include programming for carrying out desired motions or sequences. The motor can be used to power the movement of the multi- axis actuator based on programming selected for a given substrate . [0039] Substrate 200 can be chosen from, for example, glass substrates, plastic substrates, metal substrates, ceramic substrates, including substrates comprising at least two of glass, plastic, metal, and ceramics. In certain exemplary embodiments, substrate 200 comprises glass, such as a glass sheet or panel. In certain exemplary embodiments, substrate 200 comprises glass, such as a glass sheet or panel that is coated with at least one coating material, such as a at least one coating material selected from inorganic coatings, organic coatings, and polymeric coatings, to name a few.

[0040] The thickness of substrate 200, while not limited, may, for example, range from about 0.05 millimeters to about 5 millimeters. The surface area of substrate 200, while not limited, may, for example, range from about 5,000 square millimeters to about 500,000 square millimeters.

[0041] As apparatus 100 and substrate 200 are moved relative to each other between first, second, and third positions, the total load or force exerted by apparatus 100 onto substrate 200 can be measured by force measurement gauge 112 and sent to a data processing unit via lead line 114. FIG. 5 is a chart showing total load as a function of time as apparatus 100 and substrate 200 are moved relative to each other between, first, second, and third positions, such as is shown in FIGS. 4A-4C. FIG. 6 is a chart showing an exploded view of total load as a function of time as apparatus 100 and substrate 200 are moved relative to each other between first and second positions. FIG. 7 is a chart showing an exploded view of total load as a function of time as apparatus 100 and substrate 200 are moved relative to each other between second and third positions.

[0042] Specifically, FIGS. 5-7 show an average total load as a function of time for five experimental runs. As shown in FIGS. 5-7, apparatus 100 included substrate contacting component 106' including a planar surface 102' having channel 104' as illustrated in FIG. 3B. Substrate contacting component 106' was made of stainless steel and the surface area of substrate contacting component 106' was about 10,907 square millimeters, the depth of channel 104' was about 0.76 millimeters and the width of channel 104' was about 0.76 millimeters. Substrate 200 was made of Eagle XG ^® glass, available from Corning

Incorporated, having a thickness of about 0.5 millimeters and a surface area of about 9,123 square millimeters.

[0043] As shown in FIGS. 5-7, apparatus 100 and substrate 200 were moved relatively closer to each other until a time of about 53.3 seconds at which point, apparatus 100 and substrate 200 were in second position, wherein planar surface 102' of substrate contacting component 106' of apparatus 100 and planar surface 202 of substrate 200 contacted each other. While in the second position, a partial vacuum of about 25 mPa negative pressure was generated in channel 104'. Upon contact, total load exerted by apparatus 100 onto substrate 200 quickly increased from about 0 to about 1.5 pounds.

[0044] As shown in FIGS. 5-7, planar surface 102' of substrate contacting component 106' of apparatus 100 and planar surface 202 of substrate 200 were held in contact for a time of about 63.2 seconds, after which, at a time of about 116.5 seconds, apparatus 100 and substrate 200 were moved to a third position , wherein planar surface 102' of substrate contacting component 106' and planar surface 202 of substrate 200 were not in contact.

[0045] As shown in FIG. 7, the adhesion force between planar surface 102' of substrate contacting component 106' and planar surface 202 of substrate 200 is represented as a negative load at the moment apparatus 100 and substrate 200 began being moved from the second position. In the embodiment of FIG. 7, the adhesion force is about 0.25 pounds. The adhesion force can be broadly summarized as the sum of various forces that result in adherence between surfaces, in this case the adhesion between metal surface of substrate contacting component 106' and glass surface of substrate 200. Such forces can, for example, include electrostatic forces due to non-covalently bonded charge interactions, molecular attractive forces independent of charge state, and capillary forces due to liquid mediated contact or adhesion (such as, for example, resulting from humidity).

[0046] FIGS. 8A and 8B show, respectively, side and bottom perspective views of a substrate contacting component 106 that includes a detachable subcomponent 126 comprising a plurality of openings (through holes 130) and a planar surface 102" having a layer of material 128 positioned thereon. The detachable subcomponent 126 can be, for example, repeatedly attached and detached to the main body of substrate contacting component 106 through attachment mechanisms known to persons having ordinary skill in the art (e.g., screws, clamps, interference fit, etc.). While FIG. 8B shows eight through holes 130, embodiments disclosed herein include detachable subcomponents having any number of openings, such as through holes 130.

[0047] Openings, such as through holes 130, can be in fluid communication with a vacuum source. For example, in certain exemplary embodiments, through holes 130 can be formed or machined through the detachable subcomponent 126 at predetermined positions such that they are in fluid communication with channels (e.g., 104, 104') of main body of substrate contacting component 106, 106', which are, in turn, in fluid communication with a vacuum source. Alternatively, main body of substrate contacting component may comprise a plurality of openings, such as through holes, which are configured to enable fluid communication between vacuum source and plurality of openings of detachable subcomponent 126.

[0048] Such fluid communication can be further enabled though use of a thin o-ring or gasket between the main body of substrate contacting component and detachable subcomponent 126. In addition, the planar surface 102" of the detachable subcomponent 126 may comprise at least one channel in fluid communication with a vacuum source, such as the channel patterns illustrated in FIGS. 3 A and 3B.

[0049] The detachable subcomponent 126 and/or its planar surface 102" can comprise one or more of any number of materials. For example, embodiments disclosed herein include a plurality of detachable subcomponents that can each be interchangeably attached and detached to the main body of the substrate contacting component. Members of the plurality of detachable subcomponents can each comprise planar surfaces comprising materials that differ from planar surface materials of other members of the plurality of detachable subcomponents. Changing such materials can, for example, further enable study of the adhesion forces between glass and different materials. In certain exemplary embodiments, the planar surface 102" of the detachable subcomponent 126 comprises at least one material selected from silicon and glass.

[0050] Members of the plurality of detachable subcomponents can each comprise planar surfaces comprising the same materials that differ in certain surface properties of other members of the plurality of detachable subcomponents. For example, members of the plurality of detachable subcomponents can each comprise planar surfaces comprising the same materials that differ in surface roughness as compared of other members of the plurality of detachable subcomponents.

[0051] As shown in FIG. 8B, a layer of material 128 is positioned on at least a portion of the planar surface 102" of the detachable subcomponent 126. The layer of material 128 may be adhered (e.g., glued) coated, or otherwise deposited or positioned onto the planar surface 102" through any method known to persons having ordinary skill in the art. For example, as discussed above, embodiments disclosed herein include a plurality of detachable

subcomponents that can each be interchangeably attached and detached to the main body of the substrate contacting component. Members of the plurality of detachable subcomponents can each comprise planar surfaces comprising layers of material positioned thereon that differ from layers of material positioned on planar surfaces of other members of the plurality of detachable subcomponents. In certain exemplary embodiments, the layer of material 128 comprises at least one material selected from metals and polymers. Exemplary metals include, but are not limited to, chromium, aluminum, gold, nickel, copper, platinum, and titanium, as well as alloys and multilayers of the same. The thickness of the layer of material 128, while not specifically limited, may, for example, range from about 1 nanometer to about 1 millimeter, such as from about 10 nanometers to about 1 micron, and further such as from about 20 nanometers to about 200 nanometers.

[0052] A number of processes can be used to generate openings, such as through holes 130, in detachable subcomponent 126. For example, in embodiments where the detachable subcomponent 126 comprises silicon, a thin coating of silicon nitride can be deposited on its surfaces and following this deposition, at least one of these surfaces can be coated with an ultraviolet (UV) patternable photoresist material that is exposed through a photomask. After the photoresist is developed, the silicon-nitride in the photoresist can be etched away using, for example, plasma dry etching. The photoresist can then be removed and the detachable subcomponent 126 can be inserted in a heated alkaline solution (e.g., 20-30wt% KOH in water heated to 70-90°C). The solution can etch the silicon in an anisotropic fashion until a through opening is formed.

[0053] In embodiments where the detachable subcomponent 126 comprises glass, a pattem of pilot holes can be defined using laser exposure. The subsurface damage introduced by the laser can lead to much faster etching in, for example, an acidic solution, such as an aqueous HF solution, resulting in the formation of through glass vias.

[0054] Regardless of the material of the detachable subcomponent 126, the planar surface of the subcomponent can, if desired, be roughened through various chemical or mechanical methodologies as known to persons having ordinary skill in the art. For example, when the detachable subcomponent 126 comprises glass, the planar surface of the detachable subcomponent 126 can be roughened using fine grit sandblasting. After such surface roughening, the detachable subcomponent 126 may be washed, for example with a detergent solution, after which a coating may be applied to at least one surface of the detachable subcomponent 126.

[0055] In conjunction with apparatus 100 including a force measurement gauge 112, apparatus may also include an electrometer or electrostatic volt meter that can be in electrical communication with, for example, a data processing unit (not shown) via lead line 1 14. The electrometer may, for example, record charge transfer between planar surface 102, 102 ' of substrate contacting component 106, 106' and substrate 200 when substrate 200 is in the second position and as a result of movement between the second position and the third position. Similarly, the electrostatic volt meter can record voltage generated on the surface of the substrate 200 as a result of movement between the second position and the third position.

[0056] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiment of the present disclosure without departing from the spirit and scope of the disclosure. Thus it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.