WO2013119737A2 - Processing flexible glass with a carrier - Google Patents

Abstract

A method of removing a desired part of a thin sheet (20) from a thin sheet bonded to a carrier (10) by a bonded area (40) that surrounds a non-bonded area (50), wherein the method includes forming a perimeter vent (60) defining a perimeter of the desired part (56), wherein the perimeter vent is disposed within the non-bonded area and has a depth.. 50% of the thickness (22) of the thin sheet. Prior to removing the desired part, a device may be processed onto the thin sheet. In some processes, the carrier is diced so it may be processed in smaller sizes, yet maintains a hermetically sealed edge. After dicing, an additional part of the device may be processed onto the thin sheet, and the desired part is removed by removing a desired part of the thin sheet from the carrier.

Description

PROCESING FLEXIBLE GLASS WITH A CARRIER

BACKGROUND

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S

Provisional Application Serial No. 61/596727 filed on February 8, 2012 the content of which is relied upon and incorporated herein by reference in its entirety.

[0002] Field of the invention.

[0003] The present invention relates to apparatuses and methods for processing thin sheets on carriers, and more specifically, to thin sheets of flexible glass on carriers.

[0004] Technical Background.

[0005] Today flexible plastic substrates are manufactured using a plastic base material laminated with one or more polymer films. These laminated substrate stacks are commonly used in flexible packaging associated with PV, OLED, LCDs and patterned Thin Film Transistor (TFT) electronics because of their low cost.

[0006] Flexible glass substrates offer several technical advantages over flexible plastic technology. One technical advantage is the ability of the glass to serve as a moisture or gas barrier, a primary degradation mechanism in outdoor electronics. A second advantage is in its potential to reduce overall package size (thickness) and weight through the reduction or elimination of one or more package substrate layers.

[0007] As the demand for thinner/flexible substrates (< 0.3mm thick) is driven into the electronic display industry, manufacturers are faced with a number of challenges for processing these thinner/flexible substrates.

[0008] One option is to process thicker sheets of glass then etch or polish the panel to thinner overall net thickness. This enables the use of existing panel fabrication infrastructure, but adds finishing costs to the end of the process.

[0009] A second approach is to re-engineer the existing panel process for thinner substrates.

Glass loss in the process is a major interruption, and significant capital would be required for minimizing handling loss in either a sheet to sheet or roll to roll process.

[0010] A third approach is to utilize Roll to Roll processing technologies for the thin flexible substrates. [0011] A fourth approach would be to use a carrier process where the thin substrate glass is bonded to a thicker glass carrier using adhesive.

[0012] What is desired is a carrier approach that utilizes the existing capital infrastructure of the manufacturers, enables processing of thin glass, i.e., glass having a thickness < 0.3 mm thick, without contamination or loss of bond strength between the thin glass and carrier at higher processing temperatures, and wherein the thin glass de-bonds easily from the carrier at the end of the process.

SUMMARY

[0013] The present concept involves bonding a thin sheet, for example, a flexible glass sheet, to a carrier (for example, another glass sheet) initially by van der Waals forces, then increasing the bond strength in certain areas while retaining the ability to remove the thin sheet after processing the thin sheet/carrier to form devices (for example, electronic or display devices, components of electronic or display devices, OLED materials, photo-voltaic (PV) structures, or thin film transistors), thereon. At least a portion of the thin glass is bonded to a carrier such that there is prevented device process fluids from entering between the thin sheet and carrier, whereby there is reduced the chance of contaminating downstream processes, i.e., the bonded seal between the thin sheet and carrier is hermetic, and in some preferred embodiments, this seal encompasses the outside of the article thereby preventing liquid or gas intrusion into or out of any area of the sealed article.

[0014] One commercial advantage to the present approach is that manufacturers will be able to utilize their existing capital investment in processing equipment while gaining the advantages of the thin glass sheets for PV, OLED, LCDs and patterned Thin Film Transistor (TFT) electronics, for example. Additionally, the present approach enables process flexibility, including: that for cleaning and surface preparation of the thin glass sheet and carrier to facilitate bonding; that for strengthening the bond between the thin sheet and carrier at the bonded area; that for maintaining releasability of the thin sheet from the carrier at the non-bonded (or reduced/low- strength bond) area; and that for cutting the thin sheets to facilitate extraction from the carrier. Strictly speaking, the non-bonded area may include some bonding between the thin sheet and carrier, but that bonding is of sufficient weakness to allow the thin sheet easily to be removed from the carrier without damage to the thin sheet; throughout this disclosure, such areas are called non- bonding areas for the sake of convenience only. In essence, the non-bonding areas have a bond strength significantly less than the bond strength in the bonded areas.

[0015] In certain device processes, temperatures approaching 600°C or greater and/or vacuum environments may be used. These conditions limit the materials that may be used, and place high demands on the carrier/thin sheet. The inventors have found that the ability of the article (including a thin sheet bonded to a carrier) to survive such conditions can be increased by minimizing the amount of gas trapped between the thin sheet and carrier. The trapped gas can be minimized in a number of ways, for example, by: annealing the carrier/thin glass sheet after it has undergone a process of release layer deposition whereby the annealing minimizes subsequent off-gassing after the thin sheet and carrier have been bonded to one another— this annealing can be accomplished either before or after the carrier/thin glass sheet are placed in contact with each other; initially bonding the thin sheet and carrier to one another in a vacuum environment;

providing a path for gas to escape from between the thin sheet and carrier, by the use of vent strips and/or trenches, for example; appropriately selecting cleaning/etching solutions; and controlling the surface roughness of the carrier and/or thin sheet. Each of the foregoing ways of minimizing trapped gas may be used alone, or in conjunction with any one or more other ways of minimizing trapped air and/or other gasses.

[0016] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the invention as exemplified in the written description and the appended drawings and as defined in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework to understanding the nature and character of the invention as it is claimed.

[0017] The accompanying drawings are included to provide a further understanding of principles of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain, by way of example, principles and operation of the invention. It is to be understood that various features of the invention disclosed in this specification and in the drawings can be used in any and all combinations. For example, the various features of the invention may be combined according to the aspects set forth below.

[0018] According to a first aspect, there is provided a method of bonding a thin sheet to a carrier comprising:

a) providing a thin sheet and a carrier;

b) bonding the thin sheet to the carrier;

c) processing at least one of the thin sheet and the carrier so as to minimize gas trapped between the thin sheet and carrier after bonding.

[0019] According to a second aspect, there is provided the method of the first aspect, wherein step (c) is performed before step (b), and comprises depositing a release layer on at least one of the thin sheet and the carrier, and annealing the at least one of the thin sheet and the carrier at a temperature higher than that expected in subsequent processing of a device onto the thin sheet.

[0020] According to a third aspect there is provided the method of the first aspect, further comprising a step (d) of providing a surface treatment to at least one of the thin sheet and the carrier so as to form a non-bonded area, and wherein step (c) comprises providing at least one of the thin sheet and the carrier with a trench extending from an outer peripheral edge of the at least one of the thin sheet and the carrier to the non-bonded area.

[0021] According to a fourth aspect there is provided the method of the third aspect, wherein step (b) is performed in a vacuum environment, and step (c) further comprises sealing the trench after the thin sheet and carrier have been bonded but before they are removed from the vacuum environment.

[0022] According to a fifth aspect there is provided the method of the fourth aspect, wherein the sealing comprises one or more of: filling the trench with frit and heating the frit; filling the trench with a heat-curable resin and then heating the resin.

[0023] According to a sixth aspect there is provided the method of the first aspect, further comprising a step (d) of providing a surface treatment to at least one of the thin sheet and the carrier so as to form a non-bonded area during step (b), and wherein step (c) comprises cleaning the at least one of the thin sheet and the carrier with a fluid that minimizes, upon rinsing, residue that will out-gas at subsequent processing temperatures. [0024] According to a seventh aspect there is provided the method of the first aspect, wherein step (c) is performed simultaneously with step (b), and includes bonding the thin sheet to the carrier in a vacuum environment, and flowing water vapor into the vacuum environment.

[0025] According to an eighth aspect there is provided the method of the first aspect, wherein step (b) produces a bonded area between the thin sheet and carrier, and further comprising a step (d) of increasing the strength of the bond between the thin sheet and the carrier by applying heat or pressure to the bonded area.

[0026] According to a ninth aspect there is provided the method of the eighth aspect, wherein step (d) comprises heating the thin sheet and carrier at a temperature of 400 to 625 °C.

[0027] According to a tenth aspect there is provided an article comprising:

a carrier;

a thin sheet ;

a bonded area, having an outer perimeter, holding the thin sheet to the carrier;

a non-bonded area disposed so as to be surrounded by the bonded area, wherein at least one of the thin sheet and the carrier includes a trench extending from the non-bonded area to the outer perimeter of the bonded area.

[0028] According to an eleventh aspect there is provided the article of the tenth aspect, wherein the trench is filled with a sealing material.

[0029] According to a twelfth aspect there is provided the article of the eleventh aspect, wherein the sealing material is selected from: frit; sintered frit; a heat curable resin; a heat cured resin; a UV curable resin; a UV cured resin; polyimide; material melted from one of the thin sheet and the carrier.

[0030] According to a thirteenth aspect, there is provided a method of removing a desired part of a thin sheet from a thin sheet bonded to a carrier by a bonded area that surrounds a non-bonded area, the thin sheet having a thickness, comprising:

forming a perimeter vent defining a perimeter of the desired part, wherein the perimeter vent is disposed within the non-bonded area and has a depth > 50% of the thickness of the thin sheet. [0031] According to a fourteenth aspect there is provided the method of the thirteenth aspect, further comprising forming two release vents, that are neither parallel nor collinear with one another, in the non-bonded area.

[0032] According to a fifteenth aspect there is provided the method of the thirteenth aspect, further comprising:

forming two release vents that are either parallel or collinear with one another, wherein each of the release vents extends in the bonded and non-bonded areas, and

propagating the release vents through both the thin sheet and the carrier so as to remove a portion of the thin sheet and carrier that allows the desired part to be slid off of the carrier.

[0033] According to a sixteenth aspect there is provided the method of the fourteenth or fifteenth aspects, wherein the release vents come within 500 microns of the perimeter vent but do not contact the perimeter vent.

[0034] According to a seventeenth aspect there is provided the method of any one of aspects thirteen to sixteen, further comprising using a laser to form at least one of the vents.

[0035] According to an eighteenth aspect, there if provided a method of forming a thin-sheet- based device comprising:

attaching a thin sheet to a carrier by a bonded area surrounding a non-bonded area; processing the thin sheet so as to form a device on the non-bonded area; and removing a desired part of the thin sheet according to the method of any one of aspects

13 to 17.

[0036] According to a nineteenth aspect, there is provided a cutting apparatus comprising:

a head having a plurality of orifices;

a laser source optically coupled to a first orifice of the plurality of orifices so as to deliver a laser beam through the first orifice; and

a cooling fluid source in fluid communication with at least a second orifice and at least a third orifice of the plurality of orifices, wherein a first line extending from the first orifice to the second orifice is disposed at a first angle to a second line extending from the first orifice to the third orifice. [0037] According to a twentieth aspect, there is provided the cutting apparatus of the nineteenth aspect, wherein the first angle is 90 degrees, wherein cooling fluid source is also in fluid communication with a fourth orifice of the plurality of orifices and a fifth orifice of the plurality of orifices, and further wherein a third line extending from the first orifice to the fourth orifice is substantially collinear with the first line, and a fourth line extending from the first orifice to the fifth orifice is substantially collinear with the second line.

[0038] According to a twenty first aspect, there is provided the cutting apparatus of the cutting apparatus of a nineteenth aspect, wherein the first angle is something other than 90 degrees or a multiple thereof.

[0039] According to a twenty second aspect, there is provided a cutting apparatus comprising:

a head having a plurality of orifices;

a laser source optically coupled to a first orifice of the plurality of orifices so as to deliver a laser beam through the first orifice; and

a cooling fluid source in fluid communication with at least a second orifice of the plurality of orifices,

wherein the head is rotatable.

[0040] According to a twenty third aspect, there is provided the cutting apparatus of any one of aspects nineteen to twenty-two wherein the cooling fluid source is a source of compressed air.

[0041] According to a twenty fourth aspect, there is provided the cutting apparatus of any one of aspects nineteen to twenty-three wherein the orifices have a diameter of < 1 mm.

[0042] According to a twenty fifth aspect, there is provided a method of cutting, comprising;

providing a cutting apparatus according to any one of aspects nineteen to twenty-one, twenty-three, twenty-four;

delivering a laser beam through the first orifice, and cooling fluid through the second orifice while moving the head in a first direction along the first line;

turning off the delivery of cooling fluid through the second orifice;

delivering fluid through the third orifice while moving the head in a second direction along the second line;

turning off the delivery of cooling fluid through the third orifice.

[0043] According to a twenty sixth aspect, there is provided a method of cutting, comprising; providing a cutting apparatus according to the twenty-second aspect;

delivering a laser beam through the first orifice, and cooling fluid through the second orifice while moving the head in a first direction;

rotating the head and moving the head in a second direction at a non-zero angle to the first direction.

[0044] According to a twenty seventh aspect, there is provided an article comprising:

a carrier;

a thin sheet;

a bonded area, formed around a perimeter of the thin sheet, holding the thin sheet to the carrier;

a release layer disposed so as to be surrounded by the bonded area, wherein the release layer is made of a material that will not bond to the thin sheet at a first predetermined

temperature, but will bond to the thin sheet at a second predetermined temperature, wherein the second predetermined temperature is higher than the first predetermined temperature.

[0045] According to a twenty eighth aspect, there is provided the article of the twenty- seventh aspect, wherein the release layer comprises a silicon film on the surface of the carrier and having a thickness of 100 to 500 nm thick, wherein the surface of the silicon film facing away from the carrier has had its surface dehydrogenated.

[0046] According to a twenty ninth aspect, there is provided the article of the twenty-eighth aspect, wherein the release layer further comprises a metal film on the surface of the thin sheet facing the carrier, wherein the metal film has a thickness of 100 to 500 nm.

[0047] According to a thirtieth aspect, there is provided the article of the twenty-ninth aspect, wherein the metal is chosen from the group that will form a silicide with the silicon at temperatures > 600°C, and so that it will have a surface roughness due to grain size in sputtering of Ra > 2 nm.

[0048] According to a thirty first aspect, there is provided the article of the twenty-ninth aspect or the thirtieth aspect, wherein the metal is chosen from aluminum, molybdenum, and tungsten.

[0049] According to a thirty second aspect, there is provided the article of any one of aspects twenty-seven to thirty-one, wherein the thin sheet is glass having a thickness < 300 microns. [0050] According to a thirty third aspect, there is provided the article of any one of aspects twenty-seven to thirty-two, wherein the carrier is glass having a thickness > 50 microns.

[0051] According to a thirty fourth aspect, there is provided the article of any one of aspects twenty-seven to thirty-three, wherein the combined thickness of the thin sheet and the carrier is 125 to 700 microns.

[0052] According to a thirty fifth aspect, there is provided a process of producing a plurality of desired parts from an article according to any one of aspects twenty-seven to thirty-four, comprising:

locally heating the release layer to a temperature > the second predetermined temperature to form a plurality of bonded contour lines.

[0053] According to a thirty sixth aspect, there is provided the process of the thirty- fifth aspect, further comprising forming devices on the thin sheet using processes that do not subject the release layer to a temperature greater than the first predetermined temperature.

[0054] According to a thirty seventh aspect, there is provided the process of the thirty- fifth aspect, further comprising removing the desired parts according to the method of any one of extraction aspects thirteen to seventeen.

[0055] According to a thirty eighth aspect, there is provided a method of making a device on a thin sheet comprising:

processing at least part of the device onto a thin sheet of an article, wherein the article comprises the thin sheet that has a thickness < 300 microns and that is bonded to a carrier having a thickness > 100 microns, and further wherein the bonding includes a plurality of first areas having one bonding strength, and a second area having a second bonding strength significantly higher than the first bonding strength;

dicing at least the carrier of the article so as to produce a first article portion and a second article portion, wherein the first article portion includes one of the plurality of first areas and at least a portion of the second area;

processing an additional part of the device onto the first article portion.

[0056] According to a thirty ninth aspect, there is provided the method of the thirty-eighth aspect, wherein the dicing is performed along a line that is within the second area. [0057] According to a fortieth aspect, there is provided the method of the thirty-eighth or thirty- ninth aspect, wherein the dicing is performed so that the first article portion includes at least a part of the second area around its perimeter.

[0058] According to a forty first aspect, there is provided the method of any one of aspects thirty-eight to forty, further comprising removing at least a part of the thin sheet from the first article portion according to any one of aspects thirteen to seventeen.

[0059] According to a forty second aspect, in any one of the first through eighteenth, or the twenty seventh through forty first, aspects, the thin sheet is a glass sheet, and the carrier is a glass sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] FIG. 1 is a schematic top view of an article having a thin sheet bonded to a carrier.

[0061] FIG. 2 is a schematic end view of the article in FIG. 1 as seen in the direction of arrow 3.

[0062] FIG. 3 is a flow diagram of steps for processing a thin sheet with a carrier.

[0063] FIG. 4 is a schematic flow diagram of steps for cleaning sheets.

[0064] FIG. 5 is a schematic top view of an article having a thin sheet bonded to a carrier according to one embodiment.

[0065] FIG. 6 is a partial cross section of an article having a thin sheet bonded to a carrier according to another embodiment.

[0066] FIG. 7 is a schematic top view of an article having a thin sheet bonded to a carrier according to another embodiment.

[0067] FIG. 8 is a schematic top view of an article having a desired part removed from a carrier.

[0068] FIG. 9 is a schematic view similar to that in FIG. 8, but including a cross-section.

[0069] FIG. 10 is a cross-sectional view of an article having vents formed therein.

[0070] FIG. 11 is a schematic top view of an article having vents formed therein.

[0071] FIG. 12 is a cross sectional view of a desired part 56 being removed from the article.

[0072] FIG. 13 is a top view of an article having a thin sheet bonded to a carrier according to another embodiment.

[0073] FIG. 14 is a cross sectional view of the article in FIG. 13 as taken along line 14-14.

[0074] FIG. 15 is a top view of the article in FIG. 13 having bonding contours.

[0075] FIG. 16 is a schematic view of a laser and coolant delivery head. [0076] FIG. 17 is a schematic view of another embodiment of a laser and coolant delivery head.

[0077] FIG. 18 is a graph showing the solubility of various compositional elements of a glass in ammonium bifluoride.

[0078] FIG. 19 is a graph showing dissolved aluminum in etching solutions having various compositional elements.

[0079] FIG. 20 is a graph showing the concentration of calcium dissolved in etching solutions having various compositional elements.

DETAILED DESCRIPTION

[0080] In the following detailed description, for purposes of explanation and not limitation, example embodiments disclosing specific details are set forth to provide a thorough

understanding of various principles of the present invention. However, it will be apparent to one having ordinary skill in the art, having had the benefit of the present disclosure, that the present invention may be practiced in other embodiments that depart from the specific details disclosed herein. Moreover, descriptions of well-known devices, methods and materials may be omitted so as not to obscure the description of various principles of the present invention. Finally, wherever applicable, like reference numerals refer to like elements.

[0081] 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, 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.

[0082] 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.

[0083] 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. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order 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 or operational flow; plain meaning derived from grammatical organization or punctuation; the number or type of embodiments described in the specification.

[0084] 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.

[0085] General Description

[0086] With reference to FIGS. 1 and 2, a carrier 10, having a thickness 12, is bonded to a thin sheet 20 so that the thin sheet 20, i.e., one having a thickness 22 of 300 microns or less

(including but not limited to thicknesses of, for example, 10-50 microns, 50-100 microns, 100- 150 microns and 150-300 microns), can be utilized in existing device processing infrastructure. When carrier 10 and thin sheet 20 are bonded to one another, their combined thickness 24 is the same as a thicker sheet for which the device processing equipment was designed. For example, if the processing equipment was designed for a 700 micron sheet, and the thin sheet had a thickness 22 of 300 microns, then thickness 12 would be selected as 400 microns.

[0087] Carrier 10 may be of any suitable material including glass, or glass-ceramic, for example. If made of glass, carrier 10 may be of any suitable composition including alumino-silicate, boro- silicate, alumino-boro-silicate, soda-lime-silicate, and may be either alkali containing or alkali- free depending upon its ultimate application. Thickness 12 may be from about 0.3 to 3 mm, for example 0.3, 0.4, 0.5, 0.6, 0.65, 0.7, 1.0, 2.0, or 3 mm, and will depend upon the thickness 22, as noted above. Additionally, the carrier may be made of one layer, as shown, or multiple layers (including multiple thin sheets) that are bonded together.

[0088] The thin sheet 20 may be of any suitable material including glass, or glass-ceramic, for example. When made of glass, thin sheet 20 may be of any suitable composition, including alumino-silicate, boro-silicate, alumino-boro-silicate, soda-lime-silicate, and may be either alkali containing or alkali free depending upon its ultimate application. The thickness 22 of the thin sheet 20 is 300 microns or less, as noted above.

[0089] The thin sheet 20 is bonded to the carrier by an area 40, wherein there is direct contact between the surface of the thin sheet 20 and the surface of the carrier 10. There is no bond, or a less strong bond (as noted above), between the carrier 10 and thin glass sheet 20 in the area 50, hereinafter called the non-bonded area for the sake of convenience of reference only, even though there may be some form of weak bonding. The non-bonded area 50 has a perimeter 52, outside of which the bonded area 40 is disposed.

[0090] The present concept involves bonding a flexible sheet 20 to carrier 10 initially by van der Waals forces, then increasing the bond strength in certain areas while retaining the ability to remove the thin sheet after processing the thin sheet/carrier article to form devices. The present concepts further involve: cleaning and surface preparation of the thin sheet 20 and carrier 10 to facilitate bonding; initially bonding the thin sheet 20 to the carrier 10; strengthening the initial bond between the thin sheet 20 and carrier 10 at the bonded area 40; providing for releasability of the thin sheet 20 from the carrier 10 at the non-bonded area 50; and extracting desired parts 56 of the thin sheet 20.

[0091] General Process flow

[0092] FIG. 3 shows a general process flow for the present concept. The carrier flow process 102 includes selecting a suitable carrier in terms of size, thickness, and material. The carrier is then cleaned at process 104. At 106, the carrier is treated so as to achieve areas that will have different bond strength with the thin sheet. The carrier may then be cleaned again as at process 104a, which may be the same or different than the process 104. Alternatively, depending upon what process was used to achieve the areas of different bond strength with the thin sheet, the carrier may be cleaned with a different cleaning process, or not at all. The carrier is then ready for bonding to the thin sheet at initial bonding process 108. At process flow 122, the thin sheet is selected in terms of its size, thickness, and material. The thin sheet may be of about the same size as, slightly larger, or slightly smaller than, the carrier. After selection, the thin sheet is cleaned at 124. The cleaning process 124 may be the same as that used in 104, or may be different. The object of the cleaning processes is to reduce the amount of particles or other impurities that are on the bonding faces of the carrier and thin sheet. At 108, the bonding faces of the thin sheet and carrier are contacted with one another. At 110 there are performed processes for strengthening the bond between the carrier and thin sheet. At 112, the carrier/thin sheet article undergoes processing to form devices on the thin sheet. At 114, optionally, the carrier and thin sheet may be diced into smaller parts with the thin sheet still bonded to the carrier. The dicing at 114, when present, may occur after the processing 112, before the processing 112, or between two different steps of processing 112. Then at 116, at least a part of the thin sheet is removed from the carrier.

[0093] Carrier and Thin Sheet Selection - Example 1

[0094] A carrier was selected having: a thickness of 0.7 mm; a circular wafer of diameter of 200 mm; composition of Corning Incorporated's Eagle XG® glass. A thin sheet was selected having: a thickness of 100 microns; a size smaller than the carrier; and composition of Corning Incorporated's Eagle XG® glass.

[0095] Glass Cleaning - 104, 104a, 124

[0096] The cleaning process is primarily used to remove particles that may prevent bonding between the thin sheet and carrier. However, the cleaning process may also be used to roughen the surface of the carrier and, thereby, assist in forming the non-bonded described below in connection with the treatment to achieve different bonding strengths 106. The cleaning process may occur prior to treatment 106 on the carrier (and/or thin sheet, should the thin sheet also or alternatively be subjected to a treatment 106) as at 104, after such treatment 106 as at 104a, or both before and after the treatment 106. The cleaning process may also occur on the thin sheet prior to initial bonding, even if the thin sheet does not undergo a surface treatment as at 106.

[0097] The cleaning process 104 generally includes up to four steps: a first step of general removal or organics; a second step of additional cleaning; a third step of rinsing; and a fourth step of drying.

[0098] The first step for general removal of organics may include cleaning with one or more of the following: a DI water having dissolved ozone; 02 plasma; sulfuric-peroxide mixture; and/or UV-Ozone.

[0099] The second step of additional cleaning may include standard clean-1 (SCI). The SCI may also be known in the art as an "RCA clean". This process may include an ammonia solution which, as discussed below with respect to treatment 106, may perform both cleaning and surface roughening with certain materials. Instead of an SCI, a JTB100, or Baker clean 100 (available from J.T. Baker Corp.), may be used, which does not include an ammonia solution and, thus, does not perform surface roughening along with cleaning for certain materials, also as discussed below in connection with treatment 106. [00100] The rinse may be performed in DI water by a quick-dump-rinse (QDR), for example, by flowing water over the sheet (carrier or thin sheet, as appropriate).

[00101] The fourth step is a drying step, and may include a Marangoni Style drying, including Isopropyl alcohol.

[00102] The cleaning processes 104a and 124, which occur just prior to initial bonding at 108 may, in some instances, include cleaning to remove organic materials as the last step prior to initial bonding. Thus, the process steps as described above in connection with 104 would be ordered so that the step 2 follows step 1. This would be preferred if there is any significant delay between cleaning steps 1 and 2, whereby organics— from the environment in which the carrier and/or thin sheet are stored— may collect thereon. However, if there is no significant time between steps 1 and 2, or the carrier/thin sheet are stored in an environment containing a low amount of organic particles, as in a clean room, for example, then steps 1 and 2 may occur in that order, whereby cleaning of organics just prior to initial bonding at 108 is not necessary. In all other respects, the cleaning processes 104a, 124 remain the same as discussed above in connection with 104.

[00103] Cleaning Example - 1

[00104] Each the carrier and the thin sheet, from Carrier and Thin Sheet Selection - Example 1, were put through a four step process, wherein the basic recipe is a dissolved ozone cleaning step 410 in tank 403, an SCI step 420 in tank 402, a rinse step 430 in tank 403, and a dry step 440 in tank 404. All mixtures are made by volume unless otherwise stated. NH40H used herein is 14.5 Molar (28 wt/wt NH3 in water). H202 used herein is 30wt% H202 in water. DI or DIH20 refers to Deionized water and these terms are used interchangeably herein.

[00105] FIG. 4 is a tank arrangement of the machine used, including relative position of each tank, the process occurring in that particular tank, the process flow through the machine, and the particular parameters used. In this process, Tank 401, etching (including HF / HC1 etching) was not used. The following steps were performed in the respectively noted tanks 402 to 404.

[00106] In the first step 410, the glass is placed into tank 403 containing dissolved ozone (DI03). The particulars are as follows:

DI water with dissolved ozone

Ozone Concentration: 30 ppm Time: 10 minutes

Temperature: Ambient (approximately 22°C)

Water High Flow: 44 Lpm

[00107] In the second step 420, the sample is placed into tank 402 containing an SCI solution. The particulars are as follows:

1 part NH40H : 2 parts H202 : 40 parts DI water

Temperature: 65°C

Time: 5 minutes

Megasonic: 350w, 850 kHz

[00108] In the third step 430, the sample is placed in tank 403 for a Quick Dump Rinse (QDR). The particulars are as follows:

Time: 10 minutes

Rinse: DI water high flow cascade at 44 Lpm

Temperature: Ambient (approximately 22°C)

[00109] In the fourth step 440, there is performed drying in an IPA Vapor. The particulars are as follows:

Time: 10 min (includes pre cascade rinse and N2/IPA low flow dry, in the Marangoni style)

Time: 2 min final 150°C N2 high flow dry

[00110] Cleaning Example - 2

[00111] The carrier from Release Layer Application - Example 1, below, was taken and put through the same cleaning process as outlined in Cleaning Example -1, above.

[00112] Treatment For Achieving Different Bonding Strength Areas- 106

[00113] Throughout this description, for sake of simplicity in explanation, the treatments for achieving different bonding-strength areas will be described as being performed on the carrier.

However, it should be noted that, alternatively, such treatments may be performed on the thin sheet, or on both the carrier and thin sheet.

[00114] One manner of forming a non-bonded area is to deposit materials on the carrier to which the thin sheet is not disposed to sticking when subject to temperatures expected during device processing. The deposited material thus forms a release layer between the surfaces of the carrier and the thin sheet. It is desirable for the deposited material to be cleanable (so as to survive the cleaning processes described herein that are used to facilitate achieving a good bond in the bonding area), removable from the carrier as by etching, and yet that are easily able to form a roughened surface (e.g., preferably are in a crystalline form as they exist on the carrier) to facilitate debonding of the thin sheet from the carrier. Suitable materials for the release layer include zinc oxide (ZnO), 0.2-4.0% aluminum doped zinc oxide (AZO), 0.2-4.0%) gallium doped zinc oxide (GZO) , tin oxide (Sn02), aluminum oxide (A1203) gallium oxide (Ga203), bismuth oxide (Bi203), F-Sn02, F-Si02, TiON, and TiCN, for example. Standard deposition techniques may be used to put the materials on the carrier.

[00115] The release layer may operate on the principle of increasing the roughness of the interface between the thin sheet and carrier, whereby a non-bonding area is formed.

Accordingly, the release layer may include a surface roughness > 2 nm Ra (average surface roughness) to facilitate prevention of a strong bond in the non-bonded area. Yet, as the surface roughness increases, the amount of gas trapped between the thin sheet and carrier also increases, which leads to processing problems as discussed herein. Accordingly, there is likely an upper limit to the amount of surface roughness that may be practically used. This upper limit will likely depend upon the processing techniques used for initial bonding, and venting of the non- bonded area as by the use of vent strips or trenches as discussed herein.

[00116] The roughness of the surface may be adjusted by an acid etch step to increase surface roughness. The acid etching may be performed as a stand-alone step, or may be combined with the cleaning step by an appropriate selection of cleaning solutions relative to the material of the release layer. It is advantageous, from a process standpoint, however, to perform surface roughening and cleaning at the same time.

[00117] For example, with AZO films, etching may be performed as a stand-alone step by etching with a acid (for example a solution of HC1 having a pH of 2, at room temperature), followed by alkaline cleaning (for example with tetramethyl ammonia hydroxide (TMAH)). The alkaline cleaning may be performed in a standard JTB 100 cleaning with H202, having TMAH in a carboxylate buffer. In one example, using the JTB 100 with 30% H202, TMAH in carboxylate buffer, the surface roughness was reduced from 2 nm to 1.1 nm. Additionally this cleaning solution is readily rinsed from the AZO film, which beneficially leads to low out- gassing when the carrier is bonded to the thin sheet, and/or when the article is taken through device processing. Accordingly, this manner of surface roughening and cleaning may be preferred in some instances, as where fewer measures of preventing gas entrapment between the carrier and thin sheet are used.

[00118] To perform cleaning and roughening in one step, with AZO films, for example, an SCI process (40: 1 :2 DI:NH40H:H202) cleaning can be used to increase the surface roughness from 2.0 to 37 nm Ra. Combined cleaning and roughening may be preferred, in some instances (where process simplification is desired), when further measures of preventing gas entrapment between the carrier and thin sheet are used.

[00119] Alternatively, the release layer may operate on the principle of forming no OH bonding with the thin glass sheet, and need not have a particular roughness to provide a non-bonded area; materials in this category may include, for example, tin oxide, Ti02, Silica (Si02), refractory materials, SiN (silicon nitride), SiC, diamond like carbon, graphitic carbon, graphene, titanium nitride, Alumina, Titania (Ti02), SiON (siliconoxynitride), F-Sn02, F-Si02, and/or those materials having a melting point < 1000°C, and/or a strain point > about 1000°C.

[00120] The release layer thickness should be chosen so that it does not cause a gap between the bonding surfaces of the carrier and the thin sheet to such an extent that the thin sheet is unduly stressed when the bonding surfaces are in contact. Undue stress in the thin sheet may lead to damage of the thin sheet during attempted bonding to the carrier, and/or during subsequent device processing. That is, for example, assuming that the thin sheet has a planar surface (i.e., a surface facing the carrier and having no recesses or protrusions in the area of the release layer, the release layer should not stand proud above the bonding surface of the carrier more than 1 micron, for example, the gap between the bonding surfaces of the thin sheet and carrier should be < 1 micron, <500 nm, <200 nm, < 100 nm, < 50nm, < 25 nm, < 15 nm, < 10 nm, or <5 nm, for example. On the other hand, the release layer needs to have sufficient thickness so as to prevent the surfaces of the thin sheet and carrier from bonding. Accordingly, in the event that the thin sheet and carrier have completely planar surfaces facing one another, the release layer should have a thickness of > 0.2 nm. In other instances, release layers having thicknesses from 10-500 nm are acceptable. In other instances, release layers having thicknesses from 100 to 400 nm are acceptable; these have been tested and found to allow sufficient bonding in the bonding area, yet also provide a non-bonded area. In some instances, the release layer may be partially disposed in a recess within the carrier and/or thin sheet.

[00121] The release layer may be patterned over less than the entire contact area between the thin sheet 20 and carrier 10 so as to allow selected portions to form non-bonded areas 50 between the thin sheet and carrier. See, for example, FIG. 5. The non-bonded areas 50 have a perimeter 52. That is, the release layer would be patterned to allow the release material and/or surface treatment to be applied to the areas 50 but not the area 40. The remainder of the thin sheet 20 and carrier 10, i.e., bonded area 40, are bonded together. Thus, any number of desired parts 56 may be separated from any number of other desired parts 56 by cutting along dashed lines 5, or various subsets thereof, and yet all the desired parts 56 are still bonded to the carrier 10. It may be desirable to divide the article 2 into smaller sub-units for further processing. In such an instance, this arrangement of bonded area 40 and non-bonding areas 50 is advantageous in that the thin sheet 20 and carrier 10 sections are still bonded around their peripheries so that process fluids will not enter between them, which may contaminate subsequent processes, or may separate the thin sheet 20 from the carrier 10.

[00122] Although shown as having one thin sheet bonded to one carrier, in FIG. 5, a plurality of thin sheets 20 may be bonded to one carrier 10, wherein any one thin sheet 20 may be bonded to the carrier 10 with any suitable number of non-bonding areas 50 surrounded by the bonded area 40. In this case, at the time of separating the desired parts 56 from other desired parts 56, the carrier 10 may be separated between the bonding areas 40 of different thin sheets 20.

[00123] A second manner of forming a non-bonded area is through the use of different materials having different bond strengths between the thin sheet and the carrier. For example, SiNx may be used in the non-bonded area, whereas Si02 may be used in the bonded area. In order to form these two different material areas, the following process may be used. A film of SiNx may be deposited on the entire surface of the carrier by PECVD. A film of Si02 may then be deposited on top of the SiNx by PECVD in a pattern so that it is disposed the areas were bonding is desired.

[00124] A third manner of forming a non-bonded area is to use an 02 plasma to increase the bonding strength of a material that would otherwise form weak bonds with the thin sheet. For example, SiNx (silicon nitride) could be deposited over the entire carrier surface. A shadow mask could be used to block the non-bonding areas, and then an 02 plasma applied to the unmasked areas. The Si x treated by the 02 plasma will form a sufficiently strong bond to hold a glass thin sheet to the carrier, whereas the untreated SiNx will form a non-bonded area.

[00125] A fourth manner of forming a non-bonded area is through the use of surface roughening of the carrier, the thin sheet, or both. The surface roughness in the non-bonding area is increased relative to that in the bonding area so that a thin sheet to carrier bond is not formed upon heating as during device processing or strengthening of the bond in the bonded area.

Surface roughening may be used together with the techniques of the first, second, or third manners, of forming a non-bonded area. For example, the surface of the carrier is textured or roughened in at least the non-bonding area. For example, the carrier surface could be treated with an acid solution that increases the roughness of the carrier surface. For example, the acid in the solution could be H2S04, NaF/H3P04 mixture, HC1, or FTN03. Other manners of surface roughening include sand blasting, and reactive ion etching (RIE), for example.

[00126] According to one embodiment of the fourth manner, the roughened surface can be provided by printing a glass etch cream on the desired one of the thin sheet and the carrier.

[00127] More specifically, Reactive Ion Etching (RIE) and solution etching processes such as Gateway require a masking process to create bonding and non-bonding regions.

Photolithography is expensive but precise. Additive methods such as thin film deposition may also be used to create the non-bonding area. Films deposited by Chemical Vapor Deposition (CVD) such as Fluorine-doped Tin Oxide (FTO), Silicon Carbide (SiC), and Silicon Nitride (SiNx) require expensive photolithographic patterning and wet or dry etching to pattern the non- bonding area. Films deposited by Physical Vapor Deposition (PVD) such as Alumina-doped Zinc Oxide (AZO) and Indium Tin Oxide (ITO) may be shadow masked to pattern and create the non-bonding area in one process step. However, all these thin film methods require considerable capital investment for vacuum deposition equipment, lithography, and etch capabilities.

[00128] A less capital intensive and lower cost route to combine formation of the non-bonding area and patterning into one step is to print a glass etch cream which can etch and roughen the glass substrate. Glass etch creams use fluoride salts as etchants with inert materials to mask etch or "frost" soda lime glass. A patterned non-bonded area on the carrier can be easily formed at low cost by screen printing etch cream. The etch cream approach to surface roughening gives the ability to etch defined patterns to form non-bonded regions, and can induce roughness over that defined region while leaving the remaining glass surface pristine. Further, the etch cream approach to surface roughening is versatile in that the viscosity of the cream can be adjusted to facilitate screen printing, and in that the composition of the cream can be tailored to produce desired etch roughness for different glass compositions.

[00129] Display glass compositions, as may be used for the thin sheet and/or carrier, are made to possess high strain points, great chemical durability, and high stiffness. These properties make the etch rate of display glass in etch cream considerably lower than that for soda-lime glass. In addition, multicomponent glasses such as display glass may not etch uniformly. The solubility of multicomponent glasses can be estimated from equilibrium solubility theory. Coming's Eagle XG™ glass (available from Corning Incorporated, Corning, NY) is a calcium aluminum borosilicate. The solubility of Eagle XG™ was estimated— using ChemEQL

(fattp://www.eawagxh/research_e^^^ — for various concentrated etch compositions assuming contact with an infinite solid comprised of end members allowing precipitation. Figure 18 shows the solubility as a function of pH for calcium (line 1801, triangle data points), aluminum (line 1802, x data points), boron (line 1803, square data points), and silicon (line 1804, diamond data points) in ammonium bifluoride. The solubility of calcium is far lower than the other component oxides above pH 5. Since cream etch is typically near neutral pH to improve safety and handling, one would expect selective etching of a calcium aluminum borosilicate glass leaving calcium oxide and salts precipitated on the etch surface. Figure 19 shows the impact of various etch cream composition components on the solubility of aluminum. Substituting sodium bifluoride (line 1902, triangle data points) for ammonium bifluoride (line 1901, square data points), and the partial substitution of ammonium chloride (line 1903, x data points) for ammonium bifluoride, provides almost no change in the solubility of aluminum. Simply substituting another monovalent cation for ammonia has little impact (compare lines 1901 and 1902). Chlorine additions (line 1903) slightly suppress the dissolved aluminum concentration. However, the addition of sulfuric acid and barium sulphate (as used in Armour Etch Cream, line 1904, diamond data points) shows a decrease in the solubility of aluminum (compare with line 1901 for ammonium bifloride). Further, as seen from FIGS. 19 and 20, along with the decrease in total dissolved aluminum (line 1904) the addition of barium sulfate and sulfuric acid (line 2004, diamond data points) is seen to significantly increase the total dissolved calcium, as compared with the case for ammonium bifloride (line 2001, square data points). Thus, barium sulfate and sulfuric acid containing acid etch creams significantly reduce the preferential etching of calcium aluminum borosilicate glass as compared with etching with just ammonium bifluoride. Sulfate is a good choice because most sulfates are highly soluble except barium and strontium, so barium sulfate can be added as a mask material. In addition, it should be noted that calcium solubility increases strongly as pH decreases, so preferential etching (wherein calcium is etched less) can be reduced (so that calcium is etched more, and thus more evenly with the remaining composition components of the glass) by simple pH adjustment with sulfuric acid.

[00130] Glass etch cream has been demonstrated to create a non-bonding region. A carrier (0.63 mm Eagle XG) was bonded to a thin glass (0.1 mm Eagle XG) by creating non-bonding areas by roughening the carrier surface, and creating bonded areas where the pristine glass surfaces are allowed to van der Waals bond before a 500°C anneal created a strong covalent bond. In this example, a photoresist mask was patterned by lithography, and a commercial etch cream (Armour Etch Cream) was used (with a 10 minute etch time) to create a non-bonding region. A calcium aluminum borosilicate glass was etched with an etch cream under the conditions used to create the example above, and was found to increase the surface roughness from 0.34 nm to 0.42 nm. With the typical bonding process a thin piece of 0.1 mm glass was bonded leaving a non-bonded center region and strongly bonded edges. This bonded carrier has passed vacuum cycling to 70 mTorr, thermal processes to 600°C, and wet processes typical of an LTPS process.

[00131] The etch cream can be applied in a defined pattern through a variety of printing processes such as screen printing, ink jet printing, or transfer printing which apply the etchant paste to regions of the carrier to produce the non-bonded area. Screen printing is a stencil method of printing where the etch creams would be forced through the open areas of the stencil onto the carrier via a fill blade or squeegee during the squeegee stroke. The etch cream is applied for a pre-determined time to achieve the desired roughness. Roughness can be varied by changing the etch cream application time, temperature, or composition. For instance, application time at room temperature can be from 2 to 20 minutes. Following cream etching, the carrier is cleaned, typically with a heated alkaline aqueous solution with or without mechanical agitation such as brush washing, ultrasonic or megasonic agitation. After rinsing, the substrate is additionally cleaned in a Standard Clean 1 (SCI) solution consisting of DI water, a base such as ammonium hydroxide or tetramethylammonium hydroxide, and hydrogen peroxide. The carrier and thin glass part are then brought into contact to form a Van der Waals bond, and heat treated above 450°C (for example, 500°C) to create a covalent bond between the thin glass and carrier.

[00132] According to a second embodiment of the fourth manner, there can be used

atmospheric pressure reactive ion etching (AP-RIE). AP-RIE can be utilized to roughen glass carrier regions by using a Shadow Mask method or a Polymer Photoresist method. These thin film methods require considerable capital investment. Should a manufacturer already possess the processing equipment, the manufacturer can utilize the existing capital investment in processing equipment while gaining the manufacturing advantages of the thin glass sheets for PV, OLED, LCDs and other applications.

[00133] AP-RIE is a technology used in micro -fabrication. This process uses chemically reactive plasma to remove material from substrates. In this process, plasma is generated using low pressure (typically, vacuum) by an electromagnetic field. High-energy ions from the plasma attack the substrate surface and create the surface roughness. The AP-RIE is delivered using a plasma gun or jet directed on the areas defined for roughening, i.e., where non-bonding regions are desired. The plasma attaches the exposed areas using both methods. Suitable reactive gases to use for this purpose are NF3, CF4, C2F6, SF6, or generally any fluorine gas. The shadow mask method, and the polymer photoresist methods for carrying out AP-RIE will now be described. In the description of these methods, the carrier is described as the one being etched to form roughened areas for non-bonding regions. However, depending upon the ultimate application of the thin sheet, the thin sheet may also, or instead, be the one etched to form a suitable surface roughness for non-bonding regions.

[00134] Shadow Mask Method

[00135] The shadow mask method is lower cost than the polymer photoresist method, at least in part because there are fewer process steps, and less equipment is required. The mask material may be several types of materials that are not easily etched such as metal, plastic, polymer, or ceramic. However, the shadow mask method may be less accurate than the photoresist method and, therefore, not as suitable for some applications. More specifically, the exposed edge produced by the shadow mask method is not as clearly defined as the edge produced by the polymer photoresist method.

[00136] The procedure for carrying out the shadow mask method is as follows. A mask is placed over the glass carrier. AP-RIE plasma is then used to etch the exposed glass carrier areas. The mask is then removed from the glass carrier. And finally, the glass carrier is cleaned to remove particles that may prevent bonding between the thin glass sheet and carrier in the bonding areas, which are adjacent to the thusly produced non-bonding areas.

[00137] Polymer Photoresist Method

[00138] The polymer photoresist method is higher cost than Shadow Mask method, at least in part because there is more capital investment involved, and there are more process steps.

However, this method is more accurate than shadow mask method and, thus, may be better suited to some applications. The exposed edge produced by the polymer photoresist method is more clearly defined than that produced by the shadow mask method. The procedure for carrying out the polymer photoresist method is as follows. A polymer photoresist is deposited onto the glass carrier so as to block the desired bonding areas. A photolithography (expose and develop photoresist) is performed to define a pattern of desired bonding areas wherein the surface of the carrier will be roughened. An AP-RIE plasma etch is performed on the exposed areas of the glass carrier. Exposure can occur from the front or the back of the glass. In either case, the polymer protects the region that will be the bonding area.

[00139] The polymer is then removed with polymer resist remover such as oxygen ash or sulfuric hydrogen peroxide (SPM) mixture. Finally, the glass carrier is cleaned to remove particles that may prevent bonding between the thin glass sheet and carrier in the desired bonding areas.

[00140] Cleaning Methods suitable for using after the AP-RIE methods described above may include a detergent wash, or an RCA type cleaning (as is known in the art). These traditional methods of cleaning may be employed after etching is complete. The cleaning process is primarily used to remove particles that may prevent bonding between the thin sheet and carrier in the desired bonding areas. The cleaning process generally includes removal of organics, additional cleaning, rinsing and drying. [00141] The detergent washing method removes particles and light residuals with detergent, for example, KG wash, Parker 225, or Parker 225X, in ultrasonics. Submicron particles can be removed by detergent, for example, KG wash, Parker 225, or Parker 225X, in megasonics. Rinsing may include DI water rinse in ultrasonics or megasonics at room temperature to 80° C. Also, rinsing may include rinsing with IP A. After rinsing, the carrier glass is dried. A shadow masked carrier may be dried with an air knife using compressed air. A polymer photoresist formed carrier may be dried with Nitrogen. In either case, the drying may be performed in a Marangoni dryer.

[00142] The RCA cleaning method includes three cleaning steps, rinsing, and drying. A first cleaning step may be performed with SPM to remove heavy organics. A second cleaning step can include a Standard Clean 1(SC1), wherein there is used a solution of Ammonia Hydroxide, Hydrogen Peroxide and DI water diluted as needed with or without ultrasonics or megasonics. This cleaning step removes small particles and sub-micro particles. After this second cleaning step, rinsing can be performed in DI water with or without ultrasonics or megasonics.

Optionally, during this second cleaning step, washing with a brush may be performed. A nylon, PVA, or PVDF, material can be used for the brush. If brush washing is used, then another rinse may be performed thereafter with DI water in ultrasonics or megasonics at room temperature to 80°C. The third cleaning step includes a Standard Clean 2 (SC2), which is used to remove metallic contaminates. The SC2 includes HCL:H202:DI or HCL:DI solution with ultrasonics or megasonics a at room temperature to 80°C for whatever amount of time is needed. After the third cleaning step, the sample is rinsed in DI water with or without ultrasonics or megasonics. Finally, the sample is dried with an air knife using compressed air. Alternatively, the sample may be dried with a Marangoni dryer using nitrogen

[00143] A fifth manner of forming a non-bonded area involves the use of a photolithography process. A material that forms weak bonds with the thin sheet is deposited on the carrier; for example, this material could by SiNx. The SiNx is patterned, for example, by a

photolithography process whereby the SiNx in the bonding areas is removed, thereby allowing the thin sheet to contact and bond with the surface of the carrier.

[00144] Any of the above methods of forming a non-bonded area may be used in conjunction with an edge bond 80. See FIG. 6. The edge bond 80 may be formed by laser fusing of the thin sheet 20 to the carrier 10, or by frit or polyimide (or other adhesive able to withstand the temperatures expected during device processing) applied between the edge of the thin sheet 20 and the surface of the carrier 10, for example. As shown, the edge of the thin sheet 20 is recessed from the edge of the carrier 10 to assist in preventing damage to the thin sheet 20 from processing equipment or otherwise. The edge bond 80 may extend down the edge, as over area 81, of the carrier to reduce the chance that processing fluids will enter between the thin sheet 20 and carrierlO, which would increase the risk of the thin sheet 20 coming off of the carrier 10. The edge bond 80 may be useful in the case that the thin sheet 20 is bowed, or otherwise does not completely conform to the surface profile of carrier 10 at the edge; this may be the case when vent strips 70 are used. In any event, the use of the edge bond 80 assists in increasing the reliability of the article. Although FIG. 6 shows a release layer 30 between the thin sheet and carrier, this approach may be used with any other manner of forming a non-bonded area.

Further, the edge bond 80 may provide the entire bonding between the thin sheet 20 and carrier 10, or may supplement other bonding areas between the thin sheet 20 and carrier 10, for example the bonding areas formed as described herein.

[00145] Release Layer Application -Example 1

[00146] The carrier from Cleaning Example 1 was taken and AZO was sputtered onto the carrier in the non-bonding areas. That is, a mask was used to block the sputtered AZO from coating the carrier in the bonding areas. The AZO was deposited in by RF sputtering from a 0.5wt% AZO target at lOmT pressure, 1% 02 in Ar gas flow and 2.5W/cm2 RF power density (at target).

[00147] AZO was chosen because it is easily reactively sputtered from a low-cost metallic target to form crystalline AZO which may easily be roughened, cleaned, and removed

(patterned). The grain structure of the crystalline AZO may provide suitable surface roughness. Additionally, AZO is readily roughened or removed by either acidic or basic solutions.

Specifically, post deposition roughening may be accomplished by either an acid etch followed by alkaline cleaning, or an alkaline etch which also cleans and removes organics. Etching was performed at room temperature with an HC1 solution having a pH of 2, whereby the surface roughness was increased from 2.9 nm Ra to 9.0 nm Ra with an etch time of 5 seconds.

[00148] Initial Bonding Process 108 [00149] In order to prepare for initial bonding the sheet (thin sheet and/or carrier) having the release layer thereon, there may be used a pre-heating step. One object of the pre-heating step is to drive off any volatiles remaining after cleaning and/or formation of the release layer. The preheating step advantageously heats the sheet at a temperature near or above the temperature expected during subsequent device processing of the bonded carrier/thin sheet article. If the temperature used during pre-heating is less than the expected device processing temperature, then additional volatiles may be driven off during the device processing causing gasses to build in the non-bonded area that could, in certain instances, cause release of the thin sheet from the carrier, or breakage of the thin sheet. Even if there is no separation or breakage of the thin sheet, such gasses may cause a bulge in the thin sheet that would make it unsuitable for processing in equipment or methods requiring a certain sheet flatness, for example.

[00150] Heating steps may be used to minimize or prevent absorbed water from forming on the bonding surfaces immediately prior to bonding, which greatly improves performance under vacuum and high temperature and permits a strong bond to be formed between the carrier and thin glass.

[00151] Trapped gasses such as air, water, or volatiles, induced during the bonding process can expand during customer processing due to the elevated temperatures (150°C - 600°C) or vacuum environment which can cause thin glass to separate, break or bulge in a manner that degrades or interferes with the customer process or process equipment. However, a hydroxyl terminated surface is desired for bonding the glass surfaces to achieve the bond between the thin glass and carrier. There is a delicate balance between removing the physisorbed and chemisorbed water from the non-bonding (roughened) regions without removing the silanol terminated groups desired for the bonding regions to maintain a bond between the thin glass and carrier.

[00152] This balance can be achieved by the following bonding surface preparation. The carrier and thin glass are cleaned first in a conventional cleaning line with alkaline detergent and ultrasonic agitation, and DI water rinse. This is followed by 02 plasma cleaning, and 10 minutes in a 75°C dilute SCI bath ( 40: 1 :2 DI:NH40H:H202 or 40: 1 :2 DI:JTB100:H2O2). Depending on the nature of the non-bonding surface, the carrier and thin glass are subject to either a 150°C 1 minute hotplate bake to remove physisorbed water, or a 450°C lhour vacuum anneal to remove chemisorbed wafer. Soon after removing free water the thin glass and carrier are brought into contact to pre-bond by Van der Waals forces, and heated treated at T > 450°C to create a covalent bond.

[00153] After the SCI cleaning process, one would expect the glass surface to be saturated with hydroxyl (~4.6 OH/nm2, which should form 2.3 H20/nm² after condensation), covered with a monolayer of tightly bound hydrogen bonded water (-15 H20/nm2), and more loosely bound free water (~2.5 monolayers). The free water is lost in vacuum at as low as 25°C. Heating to 190°C in vacuum is reported to remove the monolayer of hydrogen bonded water. Additional heating to 400°C and above removes all but the isolated single silanol groups, but this reduces the degree of surface hydro xylation. Temperatures of in excess of 1000°C would be needed to remove all the hydroxyl groups, but such is not necessary to obtain suitable performance of the thin sheet on carrier according to the present disclosure.

[00154] Creation of the non-bonding area by additive processes such as Alumina-doped Zinc Oxide (AZO) deposition, or subtractive processes such as reactive ion etching, or etch cream create increased surface roughness, and may cause chemical changes which can increase the amount of water and other gases absorbed on the surfaces. In particular, the cleaning of AZO with SCI containing NH₄OH and H₂0₂ causes a reaction forming Zn(OH)₂. This reaction greatly increases surface roughness and creates a white hazy surface. Upon heating Zn(OH)₂ starts to decompose forming ZnO and water at only 125°C. Zinc hydroxide also absorbs carbon dioxide from the air to form zinc carbonate which is stable to 300°C.

[00155] The impact of this free water, hydrogen bound water, and silanol species on the vacuum compatibility of a thin glass on carrier consisting of a strongly bound periphery and a non-bonding center can be described by estimating the quantity of water in each species, and calculating the pressure exerted as it expands by ideal gas law under various PVD, CVD, and dopant activation steps typical of LTPS processes.

[00156] (Table 1)

[00157] Vaporization of the condensed water should create pressure differentials of 104 to 106 Torr. This pressure differential will cause bowing and defection of the thin glass away from the carrier. This deflection increased the volume between the carrier and thin sheet, reducing the pressure differential. The applied pressure and resulting thin glass deflection put the thin glass into tension. If the tensile force is too great, the probability of thin glass failure will become unacceptable for a manufacturing process. Minimizing the risk of failure due to vaporization of surface water can be done by minimizing the water prior to bonding.

[00158] The impact of degassing, by heating, the carrier and thin glass parts immediately after cleaning and prior to bonding upon the vacuum compatibility of bonded thin glass carriers is illustrated in Tables 2 and 3.

[00159] Table 2

[00160] Table 3

[00161] These samples included AZO coated carriers cleaned with SCI solution containing either ΝΗ₄ΟΗ or JT Baker 100. As described above, the zinc oxide reacts with the SCI solution containing NH₄OH and H₂0₂ forming Zn(OH)₂. The vacuum compatibility of the bonded carries was evaluated by pumping in the loadlock of a conventional CVD tool. This system has a soft pump valve to slow the initial vacuum surge, and the dry pump reaches an ultimate pressure of < 70 mTorr. With no degassing between cleaning and bonding, all parts fail with the thin glass breaking near atmospheric pressure. Table 2 shows the impact of a 150°C 1 minute hot plate degass shifts the failure point of AZO samples cleaned in Baker 100 to near 1 Torr, while samples cleaned with NH₄OH continue to fail near atmospheric pressure. From the studies of hydration of silica surfaces cited above, one would expect the majority of the hydrogen bonded water to be removed by a 150°C lminute hot plate degas. However, decomposition of Zn(OH)₂ and Zn(CO)₃ may not be complete. A comparison of the samples 2-1 to 2-7 shows that the 150°C lminute hot plate degas helped, but alone was not sufficient. Further, a comparison of samples 2-1, 2-2, 2-3, and 2-4, cleaned with JTB 100 to samples 2-5, 2-6, and 2-7, cleaned with NH40H, shows that there is little difference between these two cleaning solutions. Table 3 shows the impact of a 450°C lhour vacuum anneal on the vacuum survivability of the carriers. All bonded carriers which did not have flaws in the bonded area (visible prior to testing) passed vacuum testing regardless of the chemistry utilized in cleaning. A comparison of the samples of Table 3 with those of Table 2 shows that a higher temperature, and longer heating time, were more effective at improving the ability of the thin sheet and carrier to survive vacuum conditions. When used in combination, these two heating steps were found to be very effective.

Specifically, by degassing patterned AZO coated carriers with a 450°C lhour vacuum anneal (as per the protocol of the Table 3 samples), and degassing the thin glass (that is to be bonded to the carrier) by heating at 150°C for 1 minute on a hotplate (as per the protocol of the Table 2 samples), 32/32 samples fabricated passed vacuum testing. Although the thin glass sheets could have been subject to the protocol of the Table 3 samples, the lower temperature and shorter time of the Table 2 protocol may be more economical in certain situations.

[00162] After any heating steps, the thin sheet and carrier are then brought into contact with one another. One manner of doing so is to float the thin sheet on top of the carrier, and then cause point contact between them. A bond (e.g., a van der Waal type bond) is made at the point of contact and spreads across the interface between the thin sheet and carrier. It is advantageous to avoid trapping gas bubbles (air or other gas that is in the initial bonding environment) between the thin sheet and the carrier, because such trapped gas may expand during subsequent device processing (due to processing temperatures or vacuum environment) and, in certain instances, cause release of the thin sheet from the carrier, or breakage of the thin sheet. Again, as with volatiles described above, even if there is no separation or breakage of the thin sheet, such trapped gas may cause a bulge in the thin sheet that would make it unsuitable for processing in equipment or methods requiring a certain sheet flatness, for example.

[00163] One manner of avoiding gas bubbles is to bend the thin sheet and/or carrier while making the point of contact, and then allow the bend to relax until the thin sheet and carrier are straightened. If gas bubbles are trapped between the thin sheet and the carrier, it is advantageous to remove them by applying directional pressure to the bubbles until they escape, for example, from an edge of the article or through a venting passage. At this stage, after the initial bond has been made, the article may be handled without fear of trapping particles between the thin sheet and carrier. Thus, for example, the article may then be handled outside of a clean room to facilitate processing.

[00164] Another manner of avoiding gas bubbles is to do the initial bonding in a vacuum environment, which assists in removing the gas from between the thin sheet and carrier. Yet, it is desirable to have a thin film of water, even a mono-layer, on the surfaces to be bonded. These two competing interests, of removing gas, volatiles, and water vapor, from the non-bonding area to limit trapped gas, yet having water on the bonding areas, can be accommodated by flowing water vapor through the vacuum environment. A suitable temperature, relative humidity, and flow rate may be chosen to accommodate these competing interests.

[00165] If a sufficient amount of the volatiles were not removed from the sheet having the release layer thereon before initially bonding the thin sheet to the carrier, then further de-gassing may be done after the initial bonding. At this point, the article may be heated at a temperature sufficient to cause further volatilization. However, if the bonded area forms a complete seal around the non-bonded area (as is desired to prevent device process fluids from entering between the thin sheet and carrier, whereby they may contaminate downstream processes, i.e., the seal is hermetic), then the out-gassing of the volatiles will cause the thin sheet to bulge. This bulge may be removed by applying sufficient directional pressure to force the trapped gasses out from between the thin sheet and carrier, as at the edge for example, or via a vent passage as described below. Other vent locations may be provided as described below. The article may be allowed to cool to room temperature at this stage if desired. [00166] Initial Bonding - Example 1

[00167] The carrier from Cleaning Example - 2 was taken and placed on a hot plate that was at 250°C, and held there for 5 minutes, and then allowed to return to room temperature. The thin sheet from Cleaning Example - 1 was floated on top of that carrier. The thin sheet, was forced into point contact with the carrier at a location interior of the edge of the thin sheet and within the bonding area. A bond was formed between the thin sheet and carrier, and that bond was observed to propagate through the bonded area. The article was then placed on a hot plate and heated at a temperature between 350°C and 400 °C. A bulge in the non-bonded area was observed, and was subsequently squeezed out from between the thin sheet and carrier.

[00168] Venting the Non-Bonded Area

[00169] Steps may be taken to reduce the amount of bulging of, and/or other undesired effects on, the thin sheet 20 when gas trapped in the non-bonded area 50 expands as when the article 2 is subjected to an increased temperature environment, as during bond strengthening. One manner of reducing these undesired effects is to provide vent strips 70 extending from the non-bonded area 50, through the bonded area 40 to the edge of the thin sheet 20. See FIG. 7. The vent strips 70 may be formed in the same, or a different, manner as is the non-bonded area.

Advantageously, the vent strips 70 are formed as a release layer of the same material as is the non-bonded area 50. The number and location of the vent strips 70 will depend upon the size and shape of the non-bonded area. The vent strips 70 permit escape of gas trapped between the thin sheet 20 and the carrier 10 during any process where the article 2 is heated, for example, during the bond strengthening process, or when the article 2 is in a vacuum environment. The vent strips 70 have a width 71, and produce a non-bonding effect between the thin sheet 20 and carrier 10 over a width 73 greater than width 71. Any suitable number of vent strips 71 may be used, depending upon the size and thickness of the non-bonded area 50.

[00170] The vent strips 70 may also be used to improve the performance of the article 2 during initial bonding, or in device processing, when the article 2 is in a vacuum environment. For example, initial bonding may occur in a vacuum environment to reduce the amount of gas trapped between the thin sheet 20 and carrier 10, and/or to assist in the initial bonding process. That is, when the initial bonding process takes place in a vacuum environment, the vent strips 70 allow the escape of gas from between the thin sheet 20 and carrier 10 as the initial bonding takes place. At the end of the initial bonding process, while the article is still under vacuum environment, the vents are sealed so that gas and moisture do not re-enter between the thin sheet 20 and carrier 10. Alternatively, for example, after the thin sheet 20 has been bonded (by either initial bonding and/or bond strengthening) to the carrier 10, the article 2 may be placed in a vacuum environment, and the vent strips 70 sealed where they intersect with the edge of the thin sheet 20, for example. In this manner there can be reduced the amount of gas trapped between the thin sheet 20 and carrier 10, thereby minimizing the undesired effects thereof during device processing in a vacuum or elevated temperature environment. The seal then prevents air and moisture from re-entering through the vent strips 70.

[00171] One manner of sealing the vent strips 70 is to place the article 2 in an atomic layer deposition (ALD) chamber, evacuate the chamber, and then deposit a thin coating across the end of the vent strip 70 at the edge of the thin sheet 20. ALD involves monolayer pulses of reactants which can diffuse and penetrate into narrow features (such as the ends of vent strips 70) and absorb before being reacting with a second pulse of another precursor. For example, in ALD deposition of A1203, an monolayer of aluminum precursor such as trimethylaluminum is reacted with a monolayer of water to form A1203.

[00172] Vent strips - Example 1

[00173] The carrier from Release Layer Application - Example 1 was additionally patterned with four vents of 100 micron width each. The carrier was then processed according to Initial Bonding Example - 1 and Increasing Bond Strength Example - 1. After bond strengthening, the width 73 extended about a half of a mm on either side of the width 71. The sample survived initial vacuum testing at 100 mtorr

[00174] Vent strips - Example 2

[00175] The carrier from Release Layer Application - Example 1 was additionally patterned with eight vents of 100 micron width each. The carrier was then processed according to Initial Bonding Example - 1 and Increasing Bond Strength Example - 1. After bond strengthening, the width 73 extended about a half of a mm on either side of the width 71. The sample survived initial vacuum testing at 100 mtorr.

[00176] Vent strips - Example 3 [00177] The carrier from Release Layer Application - Example 1 was additionally patterned with four vents of 1 mm width each. The carrier was then processed according to Initial Bonding Example - 1 and Increasing Bond Strength Example - 1. After bond strengthening, the width 73 extended about a half of a mm on either side of the width 71. The sample survived initial vacuum testing at 100 mtorr.

[00178] Vent strips - Example 4

[00179] The carrier from Release Layer Application - Example 1 was additionally patterned with four vents of 10 mm width each. The carrier was then processed according to Initial Bonding Example - 1 and Increasing Bond Strength Example - 1. After bond strengthening, the width 73 extended about a half of a mm on either side of the width 71. The sample survived initial vacuum testing at 100 mtorr.

[00180] Vent strips - Example 5

[00181] The carrier from Release Layer Application - Example 1 was additionally patterned with four vents of 25 mm width each. The carrier was then processed according to Initial Bonding Example - 1 and Increasing Bond Strength Example - 1. After bond strengthening, the width 73 extended about a half of a mm on either side of the width 71. The sample survived initial vacuum testing at 100 mtorr.

[00182] As an alternative, or in addition, to the vent strips 70, trenches may be made in the carrier 10 itself. That is, instead of forming a strip of non-bonding area through the bonding area to the edge of the article 2 (or to the edge of the thin sheet 20, as appropriate), a recessed path (or trench) in the carrier 10 may perform the same function. Alternatively, instead of a trench in the carrier 10, the trench may be formed in the thin sheet 20, or in both the thin sheet 20 and carrier 10. The locations of the trenches may be similar to that of the vent strips 70 as shown in FIG. 7. In any case, the trench allows a vacuum environment to remove gas and/or moisture from between the thin sheet 20 and carrier 10 during initial bonding, bond strengthening, and/or at any point prior to device processing. While still in the vacuum environment, the trench may be sealed with injection and curing of a polymer, for example, polyimide, a heat-curable polymer, or a UV-curable polymer. Alternatively the trench may be sealed by heating frit placed into the trench, or by direct heating of the material around the trench to melt and/or fuse the trench closed, as may be accomplished by laser heating. Such trenches may be disposed in the same configuration and number as with the vent strips 70. However, because the trench may be made with a larger cross section than that of the vent strips 70, fewer trenches may be used.

Additionally, in order to use fewer trenches, the trench may extend into the non-bonding area 50, and in some embodiments even to the center thereof. The number of trenches and/or vacuum strips may depend upon the size of the non-bonded area 50.

[00183] Strengthening the Bond Between the Thin Sheet and Carrier at Desired Areas - 110

[00184] The bonds formed between the carrier and the thin sheet at 108 may be strengthened by various processes so that the article 2 may stand up to the rigors of device processing (high temperatures, for example, temperatures over 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C, vacuum environments, and/or high pressure fluid sprays, for example), without the thin sheet coming off of the carrier.

[00185] On manner of strengthening the bond between the thin sheet and carrier is to perform anodic bonding. One manner of anodic bonding is described in US 2012/0001293, which discusses the deposition of barrier layers and the use of Anodic Bonding for the attachment of these layers to the substrate also may be used to bond thin glass sheets onto carrier substrates.

[00186] Another manner of strengthening the bond between the thin sheet and carrier is through the use of temperature and pressure, wherein the article (including the thin sheet and the carrier) is heated and subjected to application of pressure. The application of pressure may be performed by plates in contact with the carrier and thin sheet, or in a pressure chamber applying fluid pressure to the article, for example. The plates themselves may be used as heat sources, or the plates may be disposed within a heated environment. The amount of pressure used may vary depending upon temperature, for example, less pressure may be needed as temperature is increased.

[00187] When pressure plates are used, a spacer plate, or shim, may be used between the thin sheet and the plate applying pressure thereto. The spacer plate is shaped so as to contact the thin sheet in the bonded area, and to contact as much of the bonded area as possible. One advantage to using a spacer is that it may allow the thin sheet to bulge an amount equal to the thickness of the spacer plate during the application of heat and pressure during bond strengthening. The bulge may be of an amount acceptable during device processing, yet may cause trouble or damage to the thin sheet during bond strengthening. Such a bulge may occur if there were a limited amount of volatiles and/or gas bubbles remaining between the thin sheet and carrier in the non-bonded area. Alternatively, the pressure application plate may be shaped to as to have recesses or concavities, or otherwise in a manner so that it does not directly contact the thin sheet in the non-bonded area. In this manner, the thin sheet is allowed to have an acceptable bulge during bond strengthening. If the thin sheet were not allowed to bulge, in certain circumstances (as with a sufficient amount of remaining volatiles and/or air pockets, for example) the pressure build up at the non-bonded area may disrupt the bond strengthening occurring in the bonding area.

[00188] With respect to heating the article to increase bond strength, heating at a temperature of about 400°C to about 625 °C has produced acceptable bond strength. In general, as the temperature increases, the bond strength increases. A practical upper temperature limit is defined by the strain point of the materials involved, i.e., the material of the carrier and/or the material of the thin sheet. With respect to applying pressure to the article to increase bond strength, similarly to temperature, as the pressure increases, the bond strength increases as well. As a practical matter, from a manufacturability standpoint, it would be desirable to be able to produce an acceptable bond strength at as low a pressure and temperature as possible.

[00189] When heating the initially bonded area with a laser, in an environment having atmospheric pressure, it may be possible to achieve an acceptable glass-to-glass bond between the thin sheet and the carrier when the release layer is thin enough.

[00190] The techniques of glass to glass bonding as discussed in Patent US 6,814,833 B2, R Sabia, Corning Incorporated, Corning, NY. "Direct Bonding of Articles Containing Silicon", may be used to bond thin glass sheets to carriers according to the concepts of the present disclosure.

[00191] Increasing Bonding Strength Example -1

[00192] The article resulting from Initial Bonding Example -1 was taken at room temperature and placed between the plates of a heating press, using a graphene sheet (patterned so that the graphene material matched the pattern of the bonded area, whereas cut-out portions in the sheet matched the pattern of the non-bonded area) as a shim between the thin sheet and the plate of the heating press. The plates were brought together to contact the article, but not apply any significant pressure. The plates were heated at a temperature of 300°C, with no significant pressure on the article. The plates were ramped up from room temperature to 300°C, and held for 5 minutes. The plates were then ramped from 300°C to 625°C at a rate of 40°C/minute and at the same time, the pressure on the article was ramped up to 20 psi. This state was held for 5 minutes, then the heaters were turned off and the pressure released. The plates were allowed to cool to 250°C, at which point the article was removed from the press and allowed to cool to room temperature. Upon inspection, the article was found to have such a bond at the bonded area that the thin sheet and carrier behaved as a monolith, whereas the thin sheet and carrier were very much separate entities at the non-bonded area.

[00193] Increasing Bonding Strength Example - 2 (comparative)

[00194] The process as described in Increasing Bonding Strength Example 1 was carried out, except that maximum temperature was 180°C and the pressure used was 100 psi. These conditions did not produce a bond of acceptable strength for high temperature, low pressure device processing conditions.

[00195] Extracting Desired Parts of the Thin Sheet from the Carrier - 116

[00196] One of the major challenges of flexible glass on carrier concepts is the ability to extract the desired part of the thin sheet from the carrier. With reference to FIGS. 1, 2, and 8-12, this section outlines a novel approach of using a score wheel 90 to perform free-shape scoring and to remove the desired parts 56 of the thin sheet 20 from the carrier 10. It also describes a method of using a laser beam 94 (for example a C02 laser beam) to perform free-shape full body cutting of the thin sheet 20 together with mechanical scoring to create a series of release vents 61, 63, 65, 67, and/or 69 and to remove the desired parts 56 of the thin sheet 20 from the carrier 10.

[00197] This method avoids the need for debonding of the entire thin sheet 20 from the carrier 10; reducing the probability of breakage of the thin sheet 20. Instead, efficiency can be achieved by cutting and extracting only the desired part 56 which can either be TFT, CF, Touch or other thin films. Furthermore, since the mechanical and laser cutting do not cut beyond the thickness 22 of the thin sheet 20, they allow re-use of the carrier (after cleaning of the unwanted portions of thin sheet therefrom) and reducing the overall manufacturing cost.

[00198] Next, with reference to FIGS. 1 and 2, it will be described how to remove a desired part 56 of the thin sheet 20, i.e., that part having the devices or other desired structure formed thereon, from the carrier 10. [00199] In order to remove the desired part 56 from the carrier 10, a number of cuts are made in the thin sheet 20. The cuts may be scribe or vent lines, as when made by a mechanical device, for example, a score wheel 90. Alternatively, a laser 94— a carbon dioxide laser, for example— may be used to produce a vent or a full body cut through the full thickness 22. The vents have a depth 62. In order to easily and reliably remove the desired parts 56, the depth 62 is selected to be > 50% of the thickness 22. If the vent depth 62 is less than 50% of the thickness 22, then the thin sheet 20 and carrier 10, due to their bond to one another, will not flex enough to propagate the vent through the entire thickness 22 forming a cut that will release the desired part 56. In a full-body laser cut, the vent depth 62 will be 100% of the thickness 22. For the sake of simplicity in explanation and reference, the vents will be described below as vents made through less than the entire thickness 22. Further, although all of the vents are shown as being of the same depth 62, such need not be the case; instead, the vents may have different depths from one another.

[00200] The vents include a perimeter vent 60, y-direction release vents 61, 63, and x-direction release vents 65, 67, 69. The perimeter vent 60 follows the perimeter 57 of the desired part 56, and is made within the perimeter 52 of the non-bonded area 50. The release vents are shown as having various configurations relative to the bonded area 40 and the non-bonded area 50, as well as relative to the perimeter vent 60, which may be the case, or they may have a similar configuration. For example, y-direction vents 61 are shown as extending within both the bonded area 40 and non-bonded area 50, i.e., they cross the perimeter 52, but do not extend to the perimeter of the thin sheet 20. The vents 61 are spaced a distance 66 from the perimeter of the thin sheet 20. Distance 66 may be chosen as any suitable value, including zero. In the event that distance 66 is zero, then the vents will have the configuration of vents 63. Similarly to vents 61, x-direction vents 65 extend within both the bonded area 40 and non-bonded area 50, and are spaced from the perimeter of the thin sheet 20. Vents 67 are entirely within the non-bonded area 50, and do not reach the perimeter 52. Similarly, vents 69 are entirely within the non-bonded area 50, but do extend to the perimeter 52. In one arrangement, as shown with vents 65, the vents are positioned so as to be collinear with the straight portions of the perimeter vent 60. In another arrangement, as shown with vents 63, 67, 69, the vents are perpendicular to the straight portions of the perimeter vent 60. In another arrangement, as shown with vents 61, the vents may be aligned with a curved portion of the perimeter vent 60.

[00201] Common to all the vents 61, 63, 65, 67, 69, is that they do not extend so as to touch the perimeter vent 60. It is desirable to keep the perimeter 57 of the desired part 56 of as high a quality as possible. That is, the strength of the part 56 will depend at least in part upon the edge strength at perimeter 57. Accordingly, it is desired to avoid damage to the perimeter 57. A score wheel or laser that over shoots its target, when making the vents 61, 63, 65, 67, 69, may cause damage to perimeter 57 thereby weakening the desired part 56. On the other hand, a vent that is propagated through the thin sheet 20 towards perimeter 57 will stop at perimeter vent 60 without causing damage to perimeter 57. Also, the vents are disposed so as to come within a distance 64 of the perimeter vent 60. The distance 64 is chosen to be < 500 microns, for example, < 400, <300, <200, <100, <50, <25, <10, or < 5, microns. If the distance 64 is greater than 500 microns, there is the unwelcome possibility that when propagated, the vent will not meet with perimeter vent 60 at a desired location.

[00202] Any suitable number of vents 61, 63, 65, 67, 69, may be used. That is, any suitable total number of vents, or any suitable number of each vent type may be used. The inventors have, however, found that using vents disposed at angles to one another facilitates removal of the desired part 56. That is, it is advantageous to use both x-direction and y-direction vents together as opposed to using only the x-direction type or only the y-direction type.

[00203] After all the vents 60, 61, 63, 65, 67, 69, are formed, the carrier 10 and thin sheet 20 are flexed to propagate the vents 60, 61, 63, 65, 67, 69, through the thickness 22, and the vents 61, 63, 65, 67, 69, in their respective x or y directions so as to meet perimeter vent 60. Next, as shown in FIG. 12, the desired part 56 may be removed by peeling, for example, by attaching suction cups 91 and pulling the desired part 56 off of carrier 10. In order to facilitate removal, air or liquid may be forced between desired part 56 and carrier 10 as the desired part 56 is being pulled. Because the perimeter 57 of the desired part 56 is entirely within the non-bonded area 50, the thin sheet 20 is easily removed, without damage, from the carrier 10.

[00204] A second embodiment, for extracting desired part 56, will be explained in connection with FIGS. 1, 2, 8, and 9. In this embodiment, mainly the differences from the first embodiment will be described, with the understanding that the remaining elements are similar to those described in connection with the first embodiment, and wherein like reference numerals denote like elements throughout the embodiments.

[00205] In this embodiment, perimeter vent 60 and the desired vents 61, 63, 65, 67, 69, are formed as in the first embodiment. The carrier 10 and thin sheet 20 are also flexed to propagate the vents 60, 61, 63, 65, 67, 69. Additionally, as seen in FIG. 9, a presser or breaking bar 92 may then be used to apply pressure to the thin sheet 20 and carrier lOas they are supported by a soft elastic base plate 98. the pressure is applied to the right of the perimeter 57 (perimeter vent 60), and generally along a line parallel to that through vent 61 and vent 63, so as to propagate the vents 61 and 63 not only through the thin sheet 20, but also through the carrier 10 as shown by the dashed line extending through the thickness of carrier 10 in FIG. 9. That is, the bond at the interface 41 between the thin sheet 20 and the carrier 10 is so strong that these elements act as a monolith in the bonded area 40. Accordingly, because the vents 61 , 63 extend on the surface of thin sheet 20 over the interface 41, when they are propagated, the vents 61 and 63 can be made to propagate through the carrier 10 in addition to through the thin sheet 20. The vent propagation through the carrier 10 is not very well controlled, especially outside of the bonded area 40, but it does not need to be. Although there may be a jagged edge on the carrier 10 outside of the bonded area 40, and/or on the thin sheet 20 outside of perimeter 57 (perimeter vent 60), the main thing is to remove a portion of thin sheet 20 so as to allow the desired part 56 to be slid off of the carrier 10, for example in the direction of arrow 58 as shown in FIG. 8. That is, although any existing van der Waals forces may be relatively strong when pulling on thin sheet 20 to lift it off of the carrier, these forces are weak in shear. Thus, removing a portion of the thin sheet 20 together with a portion of carrier 10 thereby allowing the desired part 56 to be slid off of carrier 10 greatly facilitates removal of the desired part 56. Of course, a presser or breaking bar extending in the x direction may be used to propagate vents 65 and 69 through the carrier 10 to allow the desired part 56 to be slid in the y direction off of the carrier 10.

[00206] Although the scribe lines are shown as being made on the thin sheet 20, such need not be the case for scribe lines made in the bonded area 40. That is, at the bonded area 40 the thin sheet 20 and the carrier 10 act as a monolith, whereby a scribe in either will propagate through to the other when the article is bent. Accordingly, a scribe in the bonded area may be formed either on the thin sheet side, or the carrier side, of the article. [00207] Extraction of the parts using mechanical scoring includes the following steps:

[00208] 1.Scoring of the thin sheet along the required contour, i.e., forming a perimeter vent 60, within the non-bonded area 50 with a score wheel 90. The score wheel type, score pressure and scoring speed are selected to produce a vent with depth 62 (D), which is equal or larger that half of the thickness 22 (T) of the thin sheet, i.e., (D> 0.5T). Multiple contours can be scored prior to extraction. The scored contours can have rounded corners or can have angled corners.

[00209] 2.Creation of the pattern of the release cuts or vents 61, 63, 65, 67, and/or 69, for example, which enable an extraction of the desired parts 56. If the desired parts 56 to be extracted have a rectangular shape (or rectangular with rounded corners) the release vents should be created in directions perpendicular to each side of the part (see FIGS. 1 and 8) at each corner of the desired part 56. If the desired parts 56 are "large", one or more additional release vents 67 can be made between the corners. The release cuts (vents) should be extended close to the perimeter vent 60 that follows the contour 57 of the desired part 56 (preferably within less than 0.5mm), but they should not cross or "touch" the contour to avoid damaging of the part edges.

[00210] 3. After scoring of the contour of the part, i.e., forming the perimeter vent 60, and after the creation of the release vents (one or more types selected from those shown at 61, 63, 65, 67, 69) the flexible glass should be slightly flexed (bent) around the perimeter 57 of the desired part 56 together with the carrier 10 in order to extend the vents through the thickness 22 of the thin sheet 20 to achieve full separation of the desired part 56.

[00211] 4. The extraction is done by peeling the desired part 56 off of the inner part of the carrier 10 using suction force at an angle close to normal to the surface (e.g., 60-90 degrees with respect to the surface of the thin sheet 20) to overcome any van der Waals forces at the non- bonded area 50 without breaking the desired part. See FIG. 12.

[00212] Another method of extraction is illustrated by FIGS 8 and 9. This method includes a bend and break of the carrier 10 along one side of the desired part 56 using the release vents 61, 63 over the bonded area 40 as initiation of the break. The carrier should be placed on the relatively soft flexible material 98. The vent starts at the release vent 61 or 63 above the bonded area 40, and the crack propagates beneath the thin sheet 20 through the carrier 10 along the breaking bar 92 by bending stress generated by the breaking bar 92. After the carrier 10 and the portion of the thin sheet 20 extending to the right of vents 61, 63, as shown in FIG. 8 are broken away from the right side (as directions are shown in FIG. 8) of the desired part 56, then the desired part 56 can be slide off the carrier in the direction of arrow 58.

[00213] Instead of, or in addition to, mechanical scoring, laser cutting may be used. For example, a aC02 laser may advantageously be used as follows with reference to FIG. 10.

[00214] When a C02 laser beam 94 is used to make the perimeter vent 60 for cut the perimeter 57 of the desired parts 56, creation of the release vents and extraction (either via peeling or sliding) may be done using the same techniques and patterns described above. Unlike the mechanical scoring, however, the C02 laser enables full body cut of the thin sheet 20. The C02 laser cutting does not require flexing of the carrier 10 and of the thin sheet 20 to extend the vent through its thickness 22, so laser cutting may advantageously be used with thicker carriers 10. Laser cutting of at least the perimeter vent 60 also produces higher quality part edges with higher strength, which allows a more reliable peeling procedure and a higher yield of the extracted desired parts 56. For the C02 laser cutting the laser beam 94 is focused into a circular beam shape of small diameter on the surface of the thin sheet 20, and moves along the required trajectory followed by a coolant nozzle 96. Initiation of the laser separation may be performed by the same score wheel 90, which creates the release vents. The coolant nozzle 96 may be an air nozzle, for example, which delivers a compressed air stream onto the surface of the thin sheet through a small diameter orifice. Use of water or of air-liquid mist is preferred, since it increases an attraction force between the thin sheet 20 and the carrier 10.

[00215] One design of the nozzle 96, as shown in FIGS. 11 and 16, includes a head 200 having 4 small diameter orifices 201, 202, 203, 204, to emit cooling fluid for cutting rectangular parts. Preferably the orifice diameter is <lmm. Each orifice 201, 202, 203, 204 is used for one direction of the cut. When the laser beam 94, emitted through aperture 205, approaches the corner of the perimeter vent 60 (for example, a 90 degree turn), a control system (not shown) gradually turns one orifice off and turns on another one for making a cut in a direction perpendicular, for example, to the first cut. Alternatively, the head 200 need not be moved in perpendicular directions. That is, the orifices 201, 202, 203, and 204, are shown as being placed 90 degrees from one another around the perimeter of the head 200, but such need not be the case.

[00216] Although the above-described arrangement of four cooling orifices 201-204 is advantageous for cutting generally rectangular parts, different arrangements are possible. For example, as shown in FIG. 16, the first orifice 201 may be in the position shown, but then a second orifice 212 may be in a position located 120° clockwise therefrom, and a third orifice 213 may be in a position located another 90° clockwise from the second orifice 212. In this manner, the orifices may be used to cut a triangular pattern, for example, by moving the head 200 in a first direction collinear with the laser orifice 205 and the first cooling orifice 201, then upwards (as directions are shown in FIG. 16) along a line collinear with that extending between the laser orifice 205 and the second orifice 212, and then downwards (as directions are shown in FIG. 16) along a line collinear with that extending between the laser orifice 205 and the third orifice 213. Of course, any desired number of cooling orifices may be used to accommodate variously shaped perimeter vents 60.

[00217] Another design of the nozzle, as shown in FIG. 17, includes a head 200 having one cooling orifice 201, and a rotation mechanism (not shown but which may turn the head 200 in the direction of arrow 215), which allows the cooling orifice 201 to follow the laser beam (emitted from orifice 205) while the head 200 is moved through the corner of the perimeter vent 60. As is seen from FIGS. 10, 11, 16, and 17, the laser and cooling nozzles may be separate, or may be delivered through the same head.

[00218] Another advantage of the C02 laser is that the laser beam creates local heating of the flexible glass and of the carrier, which may reduce attraction forces between the glasses. The laser heating also may induce local buckling of the flexible glass making the extraction process easier.

[00219] Thin Sheet / Carrier Product and Process of Using

[00220] Above, there was described the situation wherein one desired part 56 was formed from a thin sheet 20 bonded to a carrier 10. However, any desired number of desired parts 56 may be made from a thin sheet 20 bonded to a carrier 10, depending upon the size of the thin sheet 20 and the size of the desired parts 56. For example, the thin sheet may be of a Gen 2 size or larger, for example, Gen 3, Gen 4, Gen 5, Gen 8 or larger (e.g., sheet sizes from 100 mm x 100 mm to 3 meters x 3 meters or greater). In order to allow a user to determine an arrangement of desired parts 56— in terms of size, number, and shape, of the desired parts 56, for example— that he would like to produce from one thin sheet 20 as bonded to a carrier 10, the thin sheet 20 may be supplied as shown in FIGS. 13 and 14. More specifically, there is provided an article 2 having a thin sheet 20 and a carrier 10. The thin sheet 20 is bonded to the carrier 10 in a bonded area 40 that surrounds a non-bonded area 50.

[00221] The bonded area 40 is disposed at the perimeter of the thin sheet 20. It is advantageous that the bonded area 40 seal any gap between the thin sheet 20 and carrier 10 at the perimeter of the article 2 so that process fluids are not trapped because otherwise trapped process fluids may contaminate a subsequent process through which the article 2 is conveyed.

[00222] The non-bonded area 50 may be produced by any of the above-described methods or materials. Particularly suitable, however, is coating the carrier with a release layer made of a material that maintains its non-bonding nature with thin sheet 20 at temperatures expected during device processing, but that may be bonded to the thin sheet 20 at higher temperatures. For example, the release layer 30 may be made of an inorganic material, for example, an oxide film. For example, materials may be selected from one or more of the following ITO (indium tin oxide), SiO, Si02, F-Si02, Sn02, F-Sn02, ΒΪ203, AZO, GAO, Ga203, A1203, MgO, Y203, La203, Pr6011, Pr203, Sc203, W03, Hf02, In203, Zr02, Nd203, Ta205, Ce02, Nb205, TiO, Ti02, Ti305, F-Ti02, Ti (titanium nitride), TiON (titaniumoxynitride), NiO, ZnO, or combinations thereof. Suitable metals include, for example, aluminum, molybdenum, and tungsten. Such materials, when heated to a temperature of about 450 to 600°C will not bond with the thin glass sheet 20. However, when heated to (a predetermined temperature > 625°C), or, alternatively to a temperature within 100 degrees of the strain point of the thin glass sheet, or in some embodiments within 50 degrees of the strain point of the thin glass sheet, for example, will bond to the thin glass sheet 20. In certain instances, sputtered metals may be used, for example, Ti, Si, Sn, Au, Ag, Al, Cr, Cu, Mg. Thus, the non-bonded area 50 will maintain its ability to release portions of the thin sheet 20 even after the article 2 has been processed in temperatures up to about 450 to 600°C. On the other hand, portions of the release layer 30 may be selectively bonded to the thin glass sheet 20 by heating to the predetermined temperature. Such local heating may be accomplished via a laser, other rastered heat source, heating wires, or induction heaters, for example. Other suitable materials for the non-bonding area include, more generally, metal oxides, metal oxynitrides, or metal nitrides, wherein the metal component may include In, Si, Sn, Bi, Zn, Ga, Al, Mg, Ca, Y, La, Pr, Sc, W, Hf, Zr, Nd, Ta, Ce, Nb, Ti, Mo, or combinations thereof. [00223] One specific manner of achieving this functionality— of allowing various shapes of bonding areas 40 to be formed after the thin sheet 20 has been bonded to the carrier 10 around the perimeter of the thin sheet 20— will now be described. This specific manner includes forming a release layer 30 by depositing a silicon film about 100-500nm thick on the carrier 10 (made of glass, for example Corning Incorporated's Eagle code glass) by sputtering or PECVD followed by thermal dehydrogenation of the silicon film surface, and sputtering a metal film 100- 500nm thick on the back surface of the thin sheet 20. The metal is chosen such that it will form a silicide with the silicon at high temperatures (e.g. > 600°C), and such that it will have sufficient surface roughness (e.g., Ra > 2 nm) due to grain size in sputtering to create non-bonding region. Localized heating by laser illumination through the carrier 10 will react the silicon and the metal to form a refractory silicide and create a bonded region 40. Suitable metals include (and are not limited to) aluminum, molybdenum, and tungsten.

[00224] To make the desired number of desired parts 56 on one article 2, there are made the desired number of non-bonded areas 50 surrounded by bonded contour lines 42. See FIG. 15. The bonded contour lines 42 may be selectively formed by selectively tracing a laser in the desired shape to locally heat the release layer 30 to the predetermined temperature where it will stick and hermetically seal to the thin sheet 20. Then, the article 2 is processed so as to form devices within the areas defined by the contour lines 42. After device processing, the desired parts 56 may be separated from the carrier 10 by any of the above-described manners. If it is desired to slide the desired parts 56 off of the carrier, the article 2 may first be diced into any smaller number of pieces, by dicing between appropriate ones of adjacent contour lines 42, e.g., along any pattern or sub-set of dashed lines 5. Alternatively, the article 2 may be diced along lines made so as to intersect with the perimeter vent defining the perimeter 57 of the desired part 56. In this manner, similar to that described above in connection with FIGS. 8 and 9, fewer steps are required to slide the desired parts 56 from the carrier. Further processing of devices on thin sheet 20 may occur after the article 2 has been diced.

[00225] Conclusion

[00226] Testing of an article (in this case a thin glass on carrier) for hermeticity can be achieved by a number of methods including visual or spectroscopic measurement of liquid or gas intrusion into or out of any area of the sealed article. [00227] It should be emphasized that the above-described embodiments of the present invention, particularly any "preferred" embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of various principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention without departing substantially from the spirit and various principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the following claims.

Claims

What is claimed is:

1. A method of removing a desired part of a thin sheet from a thin sheet bonded to a carrier by a bonded area that surrounds a non-bonded area, the thin sheet having a thickness, comprising: forming a perimeter vent defining a perimeter of the desired part, wherein the perimeter vent is disposed within the non-bonded area and has a depth > 50% of the thickness of the thin sheet.

2. The method of claim 1, further comprising forming two release vents, that are neither parallel nor collinear with one another, in the non-bonded area.

3. The method of claim 1, further comprising:

forming two release vents that are either parallel or collinear with one another, wherein each of the release vents extends in the bonded and non-bonded areas, and

propagating the release vents through both the thin sheet and the carrier so as to remove a portion of the thin sheet and carrier that allows the desired part to be slid off of the carrier.

4. The method of claim 2 or 3, wherein the release vents come within 500 microns of the perimeter vent but do not contact the perimeter vent.

5. The method of any one of claims 1 to 4, further comprising using a laser to form at least one of the vents.

6. A method of forming a thin-sheet-based device comprising:

attaching a thin sheet to a carrier by a bonded area surrounding a non-bonded area;

processing the thin sheet so as to form a device on the non-bonded area; and

removing a desired part of the thin sheet according to the method of any one of claims 1 to 5.

7. An article comprising:

a carrier;

a thin sheet;

a bonded area, formed around a perimeter of the thin sheet, holding the thin sheet to the carrier;

a release layer disposed so as to be surrounded by the bonded area, wherein the release layer is made of a material that will not bond to the thin sheet at a first predetermined temperature, but will bond to the thin sheet at a second predetermined temperature, wherein the second predetermined temperature is higher than the first predetermined temperature.

8. The article of claim 7, wherein the release layer comprises a silicon film on the surface of the carrier and having a thickness of 100 to 500 nm thick, wherein the surface of the silicon film facing away from the carrier has had its surface dehydrogenated.

9. The article of claim 8, wherein the release layer further comprises a metal film on the surface of the thin sheet facing the carrier, wherein the metal film has a thickness of 100 to 500 nm.

10. The article of claim 9, wherein the metal is chosen from the group that will form a silicide with the silicon at temperatures > 600°C, and so that it will have a surface roughness due to grain size in sputtering of Ra > 2 nm.

11. The article of claim 9 or 10, wherein the metal is chosen from aluminum, molybdenum, and tungsten.

12. The article of any one of claims 7-11, wherein the thin sheet is glass having a thickness < 300 microns.

13. The article of any one of claims 7-12, wherein the carrier is glass having a thickness > 50 microns.

14. The article of any one of claims 7-13, wherein the combined thickness of the thin sheet and the carrier is 125 to 700 microns.

15. A process of producing a plurality of desired parts from an article according to any one of claims 7-14, comprising:

locally heating the release layer to a temperature > the second predetermined temperature to form a plurality of bonded contour lines.

16. The process of claim 15, further comprising forming devices on the thin sheet using processes that do not subject the release layer to a temperature greater than the first

predetermined temperature.

17. The process of claim 15, further comprising removing the desired parts according to the method of any one of claims 1-5.

18. A method of making a device on a thin sheet comprising:

processing at least part of the device onto a thin sheet of an article, wherein the article comprises the thin sheet that has a thickness < 300 microns and that is bonded to a carrier having a thickness > 100 microns, and further wherein the bonding includes a plurality of first areas having one bonding strength, and a second area having a second bonding strength significantly higher than the first bonding strength;

dicing at least the carrier of the article so as to produce a first article portion and a second article portion, wherein the first article portion includes one of the plurality of first areas and at least a portion of the second area;

processing an additional part of the device onto the first article portion.

19. The method of claim 18, wherein the dicing is performed along a line that is within the second area.

20. The method of claim 18 or claim 19, wherein the dicing is performed so that the first article portion includes at least a part of the second area around its perimeter.

21. The method of any one of claims 18-20, further comprising removing at least a part of the thin sheet from the first article portion according to any one of claims 1-6.

22. A cutting apparatus comprising:

a head having a plurality of orifices;

a laser source optically coupled to a first orifice of the plurality of orifices so as to deliver a laser beam through the first orifice; and

a cooling fluid source in fluid communication with at least a second orifice and at least a third orifice of the plurality of orifices, wherein a first line extending from the first orifice to the second orifice is disposed at a first angle to a second line extending from the first orifice to the third orifice.

23. The cutting apparatus of claim 22, wherein the first angle is 90 degrees, wherein cooling fluid source is also in fluid communication with a fourth orifice of the plurality of orifices and a fifth orifice of the plurality of orifices, and further wherein a third line extending from the first orifice to the fourth orifice is substantially collinear with the first line, and a fourth line extending from the first orifice to the fifth orifice is substantially collinear with the second line.

24. The cutting apparatus of claim 23, wherein the first angle is something other than 90 degrees or a multiple thereof.

25. A cutting apparatus comprising:

a head having a plurality of orifices; a laser source optically coupled to a first orifice of the plurality of orifices so as to deliver a laser beam through the first orifice; and

a cooling fluid source in fluid communication with at least a second orifice of the plurality of orifices,

wherein the head is rotatable.

26. The cutting apparatus of any one of claims 22-25, wherein the cooling fluid source is a source of compressed air.

27. The cutting apparatus of any one of claims 22-26, wherein the orifices have a diameter of < 1 mm.

28. A method of cutting, comprising;

providing a cutting apparatus according to any one of claims 22-24, 26, 27;

delivering a laser beam through the first orifice, and cooling fluid through the second orifice while moving the head in a first direction along the first line;

turning off the delivery of cooling fluid through the second orifice;

delivering fluid through the third orifice while moving the head in a second direction along the second line;

turning off the delivery of cooling fluid through the third orifice.

29. A method of cutting, comprising;

providing a cutting apparatus according to claim 25;

delivering a laser beam through the first orifice, and cooling fluid through the second orifice while moving the head in a first direction;

rotating the head and moving the head in a second direction at a non-zero angle to the first direction.