JP2018532850A - Carrier-base bonding system - Google Patents

Abstract

  Systems and methods for generating three-dimensional nanostructures are disclosed. The system comprises a substrate that is bound to a carrier using a binder. The binder can be vaporizable or sublimable. The carrier can be glass or glassy material. In some embodiments, the carrier can be permeable with one or more pores that can be detached when the binder is converted to a gaseous state by heat, pressure, light, or other methods. . This substrate is bonded to the carrier using a binder. The substrate can then be processed to form a film. Examples of the processing include grinding, polishing, etching, patterning, and other processes. The processed membrane is then aligned and secured to the receiving substrate or pre-arranged membrane. Once properly attached, the binder is heated, depressurized or otherwise sublimated or vaporized, thereby detaching the processed film from the carrier.

Description

TECHNICAL FIELD This application includes US Provisional Patent Applications Nos. 62 / 238,930 and 62 / 238,764 filed Oct. 8, 2015, and US Patent Applications filed May 23, 2016. No. 15 / 161,646 is claimed, the disclosures of which are hereby incorporated by reference in their entirety.

Background Art Three-dimensional nanostructures are various such as photonic crystals with embedded elements, three-dimensional integrated semiconductor electronic components, three-dimensional semiconductor memories, tissue skeletons, refractive index distribution optical components, and heterogeneous single crystal lattice mismatched structures. Useful in applications.

  In some embodiments, these three-dimensional nanostructures are fabricated by stacking pre-patterned films in alignment with each other or on a receiving substrate. Typically, some of these films are patterned. This patterning may include introducing pores, channels, implanted chemical elements, electronic or optical elements or other regions of structure. Further, patterning includes dividing the film into a plurality of separated portions.

  Various techniques have been described for depositing patterned films. For example, each film can be placed on a frame. In such an example, the membrane can be bonded to the outer frame by using a cutting point. The patterning film on which the frame is mounted is aligned with the substrate or the film that has been previously deposited. After alignment, the cutting point can be cut, thereby separating the frame from the membrane.

  However, this technique may be acceptable for certain applications, but may not be suitable for membranes or separation membranes that have compressive stress.

  Therefore, it would be beneficial to have an improved carrier system for transporting and aligning the membrane to produce a three-dimensional nanostructure.

  Disclosed are systems and methods for generating three-dimensional nanostructures. The system comprises a substrate bonded to a carrier using a binder that can be either vaporizable or sublimable. The carrier can be glass or glassy material, silicon, another inorganic material, or itself a vaporizable or sublimable material. In other embodiments, the carrier may be sintered and may be an airgel or a capillary array. In some embodiments, the carrier may be permeable. For example, the carrier can have one or more pores that can escape when the binder is heated or otherwise converted to a gas. A substrate such as silicon, gallium arsenide, gallium nitride, graphene or other material is bonded to the carrier using a binder. The substrate can then be processed to form the desired film. Examples of the processing include grinding, dicing, polishing, patterning by lithography means, etching, metallization, and other patterning means. Thereafter, the substrate or processed membrane (hereinafter referred to as article) is aligned with the receiving substrate or pre-arranged membrane. After proper alignment, the binder is heated, depressurized or otherwise sublimated or vaporized, thereby peeling the substrate or processed film from the carrier. This process can be repeated multiple times to build a desired film stack.

  In one embodiment, a method for separating an article mounted on a carrier with a binder is disclosed. The method includes wicking the liquid state from the gap between the carrier and the article to transfer the binder from the solid state to the liquid state and release the article from the carrier. In certain embodiments, the carrier is permeable. In some embodiments, the binder transitions to a liquid state by at least one of decomposition or melting. In some embodiments, the liquid state of the binder is at least partially preserved within the permeable carrier. In some embodiments, the liquid state of the binder transitions to a gas and passes through the permeable carrier. In certain embodiments, the liquid state of the binder is transferred to a gas, and at least a portion of the gas is collected in at least one of its liquid or solid state in a permeable carrier.

  In another embodiment, a method for separating articles is disclosed. The method includes peeling the article from the binder by transferring the binder from the solid by increasing the temperature of the local or global atmosphere or decreasing the pressure. In certain embodiments, the binder is vaporizable or sublimable. In some embodiments, the binder comprises one or more cores to optimize at least one of solvent solubility, chemical resistance, cohesion, adhesion, melting point, heat capacity and vapor pressure. A molecule having one or more handles. In some embodiments, the binder is broken down into one or more sublimable or vaporizable species or structurally modified. In some embodiments, the binding agent conforms to one or more drugs that undergo photoinitiated splitting or have a high vapor pressure. In certain embodiments, the binder attaches the article to the carrier. In certain embodiments, the carrier is permeable. In certain embodiments, the permeable carrier comprises at least one of an airgel, a xerogel or other material made from a soluble gel. In certain embodiments, the permeable carrier comprises at least one of a capillary array, frit, or porous fiber material. In certain embodiments, the permeable carrier includes at least one embedded structure that is not porous. In some embodiments, the embedded structure adjusts the thermal, electromagnetic, fluid, or mechanical properties of the permeable carrier.

  In another embodiment, a method for processing a substrate to form a film is disclosed. The method mixes a first binder having a first melting point with a second binder having a second melting point higher than the first melting point to form a binder mixture; melting the binder mixture; The molten binder mixture is used to bond the carrier to the substrate; the first binder is vaporized, sublimated, or otherwise removed from the binder mixture, leaving the second binder; After the material is removed from the binder mixture, the substrate is processed to form a film; the processed binder mixture is sublimed or vaporized to remove the film from the carrier. In certain embodiments, the temperature at which bonding occurs is lower than the temperature at which the film is removed from the carrier.

  For a better understanding of the present invention, reference is made to the accompanying drawings, which are incorporated herein by reference.

FIG. 1A shows the carrier and substrate prior to deposition. FIG. 1B shows the substrate bonded to the carrier. FIG. 2A shows the film bonded to the carrier after grinding. FIG. 2B shows the film of FIG. 2A after patterning. FIG. 2C shows a top view of the membrane of FIG. 2B. FIG. 3A shows the membrane and carrier of FIG. 2B when aligned to a receiving substrate. FIG. 3B shows the nanostructure produced after the films are stacked. FIG. 4 shows a flowchart according to an embodiment. FIG. 5 shows a porous carrier according to one embodiment. FIG. 6 shows an enlarged view of a material that can be used as a carrier according to one embodiment. FIG. 7 compares the melting point and standard vapor pressure for various possible binders. FIG. 8 shows a flowchart illustrating the use of the binder mixture.

DETAILED DESCRIPTION A substrate can be fixed to a carrier with a binder and then processed to produce a film. A substrate or film (referred to as an article) can then be laminated on top of the receiving substrate or other pre-attached article to produce a three-dimensional nanostructure.

  Throughout this disclosure, reference is made to attachment of the substrate and removal of the membrane from the carrier. However, it should be noted that in certain embodiments, the substrate is not processed after being attached to the carrier. For example, the carrier can be used to support the substrate, such as during transfer. Thus, although this disclosure describes embodiments in which the substrate is processed prior to removal, in each of these embodiments, the article to be removed can be the original substrate or processed membrane. It is understood.

  FIG. 1A shows the carrier 10 and the substrate 20 before processing. The carrier 10 can be any semi-rigid amorphous or crystalline material or composite material. In some embodiments, the carrier 10 can be flexible glass or similar material. The dimensions of the carrier 10 can vary. For example, the length and width can be based on the size of the film to be produced. In one embodiment, the carrier 10 can have a diameter of 25 mm, although other dimensions are within the scope of the present invention. Also, the thickness of the carrier 10 can vary, and in some embodiments can be between 0.1 mm and 10 mm, although other thicknesses are possible.

In some embodiments, the carrier 10 can be permeable. In one embodiment, the permeability of the carrier 10 may be greater than 1 × 10 ⁻¹² millidalsea. The permeable carrier 10 can be of various configurations and materials. For example, in one embodiment, the carrier 10 contains one or more holes 12 that extend through the thickness of the carrier 10, as shown in FIG. These pores 12 can have a diameter in the range of nanometers to several hundreds of micrometers, although this diameter can vary. The porosity of the carrier 10 may exceed 20%. In some embodiments, the porosity is greater than 50%. The purpose of the holes 12 will be described in more detail below.

  In another embodiment, the carrier 10 is composed of a material that includes particles that contact each other only in limited locations, leaving an interparticle path large enough to allow gas to pass through the carrier. Therefore, it is porous. For example, FIG. 5 illustrates such a material, which in this embodiment is sintered glass. FIG. 5 shows an enlarged view of the material so that the interparticle path can be seen. Of course, other materials containing interparticle or intermolecular pathways may be used and the invention is not limited to this material or any other specific material.

  In another embodiment, the carrier 10 can be composed of one or more sublimable or vaporizable materials. In this embodiment, the carrier can be fixed directly to the substrate 20 without an intervening layer of binder. In one embodiment, the carrier material is melted to adhere the carrier material to the substrate. In one embodiment, the carrier material is vaporized and condensed on the substrate. By coating the substrate, the carrier surrounds part or all of the surface of the substrate that can be patterned with protruding and / or recessed structures. Articles that can be substrates or membranes have the advantage of supporting vaporizable or sublimable binders during subsequent processing steps because some of these binders form hard crystalline solids. .

  In another embodiment, the carrier 10 can be made from a permeable material that does not have holes or channels. For example, materials such as polydimethylsiloxane (PDMS) are permeable to gases. Of course, other materials may also have this property and the invention is not limited to a particular material.

  To achieve the above properties, the permeable carrier 10 can be made from a variety of materials such as paper, airgel or similar materials, capillary arrays, frit and porous polymers. Furthermore, solid materials can be made into permeable carriers by machining holes and / or surface channels that facilitate the transport of the binder. In general, paper comprises strands of fibers, typically cellulose or glass. Aerogels, xerogels and other materials made from the sol-gel process contain a small amount of residue from the gel matrix that remains after the liquid is removed. A capillary array includes one or more channels that pass through and through a solid, including when the channels occur along the material surface. The frit includes particles that are sintered together. Each of these materials is described in more detail below.

  The permeable carrier 10 can comprise an embedded structure that is not porous. These embedded structures can be used to adjust the thermal, electromagnetic, fluid, or mechanical properties of the carrier. One example is an embedded heating element that allows for selective heating of a region of the carrier. Another example includes breakpoints or embedded features to facilitate partitioning the laminate (which may comprise a combination of substrate, binder and carrier) into dies or other parts.

  As mentioned above, paper is a porous fiber material that is permeable to liquids and gases. These fibrous compositions make the paper more compatible than other carrier types, making the carrier ideal for some applications. The ability of paper to absorb fluid by capillary action may also be advantageous for some applications.

  Aerogels, xerogels and other materials made from sol-gel or sol-gel-like processes are porous materials formed by chemical mixing, catalysis and heating. Through the curing process, the gel solidifies and dries to form a porous material. Airgel carriers can be produced in several ways.

  One of the manufacturing processes is to form individual carriers. Aerogels can contain gradients in pore size and porosity. The gradient may be sharp from small holes near the surface of the material to large holes in the majority. This gradient modifies the capillary action and fluid flow properties of the airgel.

  The second manufacturing process will be described below. Instead of forming individual carriers, an airgel process can be used to create a generally cylindrical “boule” that gives a more uniform aspect ratio. Then, after curing, the airgel boule can be bouled into a wafer flake that can be further flatly polished into an airgel carrier using a wire saw or another slicing tool.

  A capillary array is a porous material that includes many adjacent channels that penetrate most of the material, typically formed by etching, ultrasonic drilling, powder blasting or laser direct patterning. In general, the holes have unequal inlet and outlet diameters, and the shape and size of the holes can vary along their length. The permeability of these materials can be calculated directly from Darcy's law or Poiseuille's law if the hole cross-section remains sufficiently uniform along the direction of flow.

  A frit is a porous material that typically includes a fine powder of glass, metal, organic or inorganic powder material held together by a bonding agent. The bonding agent is dissolved in a solvent. The dissolved bonding agent and powder are mixed to form a paste, and then cast into a mold. After casting, the solvent is dried or otherwise removed to produce a raw frit. The term “raw” is used to indicate that the material has not yet been heat treated. Thereafter, the raw frit is heat-treated or annealed to melt the bonding agent and bonded to the powder to form a porous material block. A frit that can keep its shape better than an airgel is often easier to form and mold than an airgel and is commercially available on a large scale.

  Finally, polymers and elastomers are another class of materials that can be used as permeable carriers. These materials are adjustable in terms of their permeability and stiffness, but are limited to their maximum temperature.

  Thus, the term “permeable carrier” refers to any material that allows a binder or liquid state to pass through. This permeability can be achieved in a variety of ways; some of these are described above. However, other permeable carriers are within the scope of the present invention.

  The substrate 20 can be any suitable material or composite material, and can be a semiconductor material. In some embodiments, the substrate can comprise an already patterned microstructure. In certain embodiments, the substrate 20 can be a silicon substrate. The dimension of the base material 20 before processing can be changed. In some embodiments, the substrate 20 is of a size that is convenient to handle and resistant to breakage. For example, in some embodiments, the diameter of the substrate 20 prior to processing can be about 1 cm. In some embodiments, the substrate 20 may be larger and may have a diameter of tens of centimeters. The thickness of the substrate before processing can be about 0.5 millimeters and can be thicker or thinner.

  Thereafter, the substrate 20 is fixed to the carrier 10 using a binder 15 as shown in FIG. 1B. The binder 15 can be an adhesive or a plurality of adhesive layers that are vaporizable or sublimable. The term “vaporizable” is used to refer to a material that can easily transition to a gaseous state. The term “sublimation” is used to refer to a material that can be directly transferred from a solid state to a gaseous state without first melting. In one embodiment, the liquid binder transitions to the gas phase when heated, depressurized or otherwise stimulated. In another embodiment, the solid binder, when heated, depressurized or otherwise stimulated, first melts into a liquid and then vaporizes into the gas phase. In another embodiment, the solid binder sublimes directly into the gas phase when heated, depressurized or otherwise stimulated.

  There are various types of binders 15 that can be used to separate the permeable carrier 10 from an article that can be a substrate 20 or a processed substrate (referred to as a membrane). In the first type, the binder molecules desorb the article from the permeable carrier 10 by direct sublimation or vaporization. In the second type, the binder molecule decomposes or is structurally modified to one or more volatile, sublimable or vaporizable species, which can then be partially or fully vaporized or sublimated. In a third type of material, the binder molecule undergoes photoinitiated splitting or conformational change to form one or more binders with high vapor pressure that are more easily sublimated or vaporized. Each type will be described in detail below.

  In the first type, the binding agent 15 can include a molecule having a “core” and a side group or “handle”. The “core” molecule has the most significant effect on the material aggregation, which is a bond between molecules, and the standard vapor pressure, which is the vapor pressure at 25 ° C. Side groups or “handles” have a significant effect on adhesion to the carrier and substrate. Some examples of core molecules are naphthalene or pentacene. On the other hand, some examples of handle molecules are hydroxyl groups or carboxyl groups. Of course, other “core” molecules and “handles” can be used as well.

  The choice of core molecules and side groups is an important feature of binder design that affects material / process compatibility. Different core molecules also have different melting points, solubility, chemical resistance and stability that make them robust against different processes. Vapor pressure, the stripping process, is somewhat affected by the choice of side groups; a larger core mass will lower the vapor pressure and increase the melting point. This is illustrated in FIG. 7, which compares the melting point and standard vapor pressure for several possible binders. Thus, the selection of the core and handle can optimize at least one of solubility, chemical resistance, cohesion, adhesion, melting point, heat capacity and vapor pressure.

  More broadly on how to modify the system to convert molecules from low vapor pressure, high molecular weight and high melting point materials to high vapor pressure, low molecular weight materials using the adaptability of the core molecule and side group system Can think. The following are two such mechanisms.

  The second type of binder includes those that decompose or are structurally modified to one or more volatile, sublimable or vaporizable species. For example, in the case of 1-pyrenecarboxylic acid, it is observed that the material sublimes in an almost vacuum at 206 ° C. and begins to smoke in an atmosphere of 235 ° C., and its theoretical vapor pressure is 0.56 Torr. Yes, this is less than one atmosphere. This material is believed to undergo heat-induced decarboxylation resulting in species of pyrene, 1-hydroxypyrene, carbon monoxide and carbon dioxide. The corresponding vapor pressures of pyrene and 1-hydroxypyrene are about 1E4 Torr and 9E3 Torr at 235 ° C., both greater than 1 atmosphere.

  A third type is one in which the binder molecule undergoes photoinitiated splitting or structural / conformational changes to form one or more high vapor pressure binders that sublime or vaporize under different thermodynamic conditions. It is done.

  For example, in the case of polymers, polymethylmethacrylate (PMMA) can be weakened using photolysis of ester bonds and preferentially removed from unexposed areas of the photoresist. Instead, molecules with photoswitchable side groups or bonds may be more likely to sublime upon or after light irradiation. This is different from using light to heat and vaporize materials; instead, in the present invention, the molecular structure of the binder is prior to vaporization or sublimation caused by the mechanisms described herein. Change.

  In another embodiment, two or more binders 15 can be mixed together. For example, a first binder having a first melting point and a second binder having a second melting point higher than the first melting point can be mixed together. The components in the mixture can be combined in a ratio that produces the lowest possible melting point or eutectic point, which can be lower than the melting point of the first binder. FIG. 8 shows how this mixture of first binder and second binder can be used for substrate processing. First, as shown in process 500, a first binder and a second binder are combined to form a binder mixture. The mixture is heated to its eutectic point where it becomes liquid. This eutectic point is below the first melting point, thereby reducing the heat-induced stress applied to the substrate 20 during the bonding process. Once the mixture has melted, it is used to bond the permeable carrier 10 to the substrate 20, as shown in process 510. Once the substrate 20 is bound to the permeable carrier 10, the first binder is vaporized, sublimated, removed or otherwise partially removed from the mixture by use of a solvent, as shown in process 520, thereby Leaving most of the second binder. That is, since the first binder has a lower vapor pressure than the second binder, it can be removed without removing the second binder. The substrate 20 may then be appropriately etched, thinned, handled, laminated, assembled, or otherwise processed, as shown in process 530, while bonded to the permeable carrier 10. As explained above, at this point, the permeable carrier 10 and the substrate 20 are mainly bonded by the second binder. Thereafter, as shown in process 540, the article, which can be the substrate 20 (if no processing has been performed) or a film, is peeled from the permeable carrier 10 by sublimating or vaporizing the residual mixture.

  One advantage of this approach is that there is less stress on the substrate because bonding occurs at lower temperatures. Removal of the first binder leaves a more robust second binder while the substrate is optionally undergoing additional processing. Although the eutectic point is a known parameter of the mixture, it can be used and then the melting point can be separated from the debonding point by preferentially removing one component of the mixture.

  In addition, this approach can be used to design mixtures with specific melting points. That is, the binder can be selected to achieve a melting point between the eutectic point of the constituent binder and the maximum melting point. In another embodiment, a mixture of two or more binders can be adjusted to have a specific melting point above the eutectic point. Some processes may have the advantage of low stress bonding at low temperatures while maintaining the high melting point of the mixture.

  Another feature of the binder mixture is that, when melted, the low melting point binder can act as a solvent for both the sublimable binder and / or the high melting point vaporizable binder. For example, it has been observed that pentacene that decomposes before melting readily dissolves in molten naphthalene.

  In addition, the binder mixture can be used to separate the article from the carrier leaving a small amount of vaporizable or sublimable residue to prevent van der Waals sticking action. This residue is later removed by vaporization, sublimation or other cleaning steps. For example, an article laminated on a receiving substrate can leave a residue that can be easily sublimated at higher or lower pressures than used during the separation process. This washing step can later be performed in a processing after the article, which can be a substrate or membrane, is fully bonded to the receiving substrate.

  Furthermore, although FIG. 8 shows a process using two binders, the present invention is not limited to this embodiment. Three or more binders may be combined, and further, binders from the different types described above may be combined together as part of the present invention.

  The binder 15 can be applied to the carrier 10 or article in many different ways, such as vaporization, spin coating and drop casting. In another embodiment, a soluble gel (sol-gel) can be cured on an article pre-coated with binder 15. Other techniques can also be used and are not limited by the present invention.

  Once the substrate 20 is secured to the carrier 10 using the binder 15, the binder 15 can be solidified. Thereafter, the base material 20 may be appropriately processed. The substrate 20 can be thinned to reduce its thickness. For example, as shown in FIG. 2A, the substrate 20 can be ground and polished to reduce its thickness. In another embodiment, the substrate 20 can be peeled away to separate the thin film layer from the substrate. In another embodiment, the substrate 20 may be etched to form a film with a desired thickness. When the thinning process is complete, the substrate 20 can have a thickness of about 300 nm, although other dimensions are possible. Once the substrate 20 is thinned, it can be referred to as a membrane 21. In other embodiments, the substrate 20 is not processed and remains unaffected throughout the process.

  In certain embodiments, the membrane 21 may be further processed if desired. For example, as shown in FIG. 2C, a pattern can be generated in the film 21 using lithography and etching processes. As shown in FIG. 2C, this patterning may be used to cause the membrane 21 to generate various types of structures, or the patterning may be used to separate the membrane 21 into a plurality of disjoint portions 22. Also good. For example, the substrate can be further processed to produce patterns or complex microstructures in or on the film. These fine structures include electronic elements, mechanical elements, and optical elements. The type of microstructure that can be generated is not limited by the present invention.

  Further, while the film 21 is patterned for its microstructure, the alignment mark 11 can be generated by patterning the carrier 10 and / or the film 21 as shown in FIGS. 2B and 2C. In this embodiment, the alignment mark 11 is generated to have a known spatial relationship with respect to the patterning of the film 21. These alignment marks 11 serve to align the patterned film 21 with respect to the receiving substrate, as will be described in more detail below.

  In another embodiment, the alignment mark 11 may already be present on the carrier 10 prior to article processing or film 21 patterning. In such an embodiment, the processing of the article or the patterning of the membrane 21 can be performed using the pre-existing alignment mark 11 as a guide. That is, the patterning is performed so as to be aligned with the alignment mark 11 existing in advance.

  The alignment mark 11 can be etched into the carrier 10 as shown in FIGS. 2B and 2C. However, in other embodiments, the alignment marks 11 can be arranged on the carrier 10 in other ways, for example as a relief pattern or a metal pattern. Further, the alignment mark 11 can be disposed on the disjoint portion 22 or etched into the disjoint portion 22.

  In some embodiments, the alignment mark 11 is generated so that the carrier 10 can be aligned with the receiving substrate in at least one direction.

  A three-dimensional structure is constructed on the receiving substrate. This receiving substrate can have alignment marks intended to align with alignment marks 11 on the carrier 10, as will be described below.

  FIG. 3A shows a receiving substrate 40 having a laminate 23 of articles already placed. The receiving substrate 40 also has alignment marks 41 that align with the carrier 10.

  Each article, which can be a substrate 20 or a membrane 21, is deposited on the receiving substrate 40 as follows. First, the base material 20 is fixed to the carrier 10 using the binder 15. Next, the substrate 20 is optionally thinned and processed to produce a pattern on or in the membrane 21. In another embodiment, the processing of the substrate 20 is not performed. As described above, the alignment mark 11 is arranged on the carrier 10 so as to have a constant and known spatial relationship with the pattern on the film 21. The alignment marks 11 may be generated during the film patterning process or may be pre-existing.

  Thereafter, as shown in FIG. 3A, the carrier 10 is moved and arranged near the receiving substrate 40. In one embodiment, the carrier 10 is placed above the receiving substrate 40 with the article, which can be the substrate 20 or the membrane 21, facing down. Next, the carrier 10 is aligned to the receiving substrate 40 using the alignment marks 11 and 41. As described above, in some embodiments, alignment marks 11 and 41 allow alignment in at least one direction. In this scenario, the carrier 10 can move in all six degrees of freedom, including three translation axes and two rotation axes. In other embodiments, alignment may be performed in fewer directions. For example, in one embodiment, the alignment marks 11, 41 allow alignment in at least one direction.

  The alignment can be performed in a number of ways. In some embodiments, the carrier 10 is aligned to the receiving substrate 40 using an optical alignment process known in the art. Of course, other alignment methods can be used.

  The carrier 10 is then moved to bring the article, which can be the substrate 20 or the membrane 21, into contact with the receiving substrate 40. If a stack 23 of one or more membranes 21 has already been placed on the receiving substrate 40, the new membrane 21 is lowered onto the existing stack 23 of the membrane (see FIG. 3A). Although FIG. 3A shows the membrane 21 being lowered toward the receiving substrate 40, other embodiments are possible. For example, the carrier 10 may be disposed below the receiving substrate 40 and lifted so as to adhere to the film 21 on the receiving substrate 40. Carrier 10 and receiving substrate can be positioned and aligned with respect to receiving substrate 40 such that membrane 21 can be peeled off carrier 10 and deposited on receiving substrate 40. Any arbitrary orientation of 40 is within the scope of the present invention.

  Optionally using surface-to-surface contact bonding, so-called van der Waals bonding, followed by additional thermal processing that improves the adhesion of the film 21 to the receiving substrate 41, eg thermal or laser annealing or quasi-covalent bond formation By doing so, the film 21 can be attached to the receiving substrate 40 or the laminated portion 23. In one embodiment, quasi-covalent bonds can be formed between the contact films 21 when the silicon films 21 are annealed by contacting each other above 300 ° C. for several minutes. In another embodiment, an adhesive may be used to secure the membrane 21 to the receiving substrate 40 or the laminate 23 of the membrane. In another embodiment, solder bumps can be used to connect vias or other metal conductors in adjacent films 21.

  Once the membrane 21 is properly positioned, the binder 15 is then removed from between the membrane 21 and the carrier 10. This can be done by heating the binder 15 such that the binder vaporizes or sublimes. Alternatively, the local atmosphere pressure may be reduced to promote the vaporization or sublimation process. In some embodiments, the binder 15 can be stimulated in other ways. For example, electromagnetic radiation such as light can be used to vaporize the binder 15 or promote sublimation. Any combination of mechanisms that change the binder 15 from solid to gas can be used to remove the binder 15. As shown in FIG. 3B, by removing the binder 15, the film 21 is separated from the carrier 10 and is overlaid on the receiving substrate 40. Also, although the above disclosure describes separation of the membrane 21, this process is equally applicable to the untreated substrate 20.

  The holes 12 (see FIG. 5) in the carrier 10 allow gas generated by vaporization or sublimation of the binder 15 to easily pass through the carrier 10. Without pores 12, formation of the gas phase of the binder 15 is impeded; any gas that forms may not be completely removed and become trapped between the carrier 10 and the film 21, This can have undesirable consequences.

  An example of a vaporizable binder is naphthalene, but other binders may be used.

  Vapors from the vaporizable binder 15 may condense, creating surface tension that impedes or makes it more difficult to separate the membrane 21 or substrate 20 from the carrier 10. The use of a sublimable binder eliminates the possibility of vapor condensation between the carrier 10 and the membrane 21 or substrate 20. This is because sublimation is a direct conversion from solid to gas.

  In some embodiments, sublimable binders can be used. The sublimable binder may be naphthalene, anthracene, tetracene or pentacene. In some embodiments, polyaromatic hydrocarbons having a sublimation point below the melting point can be used. Other binders can also be sublimable, but the invention is not limited to the above list.

  FIG. 4 shows a process flow illustrating the generation of a three-dimensional nanostructure. First, as shown in process 100, an arbitrarily processed substrate is attached to a carrier. The processed substrate is attached using a vaporizable or sublimable binder. As described above, the processed substrate may be a semiconductor such as silicon.

  After the processed substrate is attached to the carrier, the substrate is optionally thinned and / or processed as shown in process 110. In one embodiment, the substrate is ground and polished to reduce its thickness to the desired thickness. In another embodiment, the substrate may be peeled away and separated from the thin film layer from the substrate. In another embodiment, the substrate may be etched to form a film with a desired thickness. Other means of thinning the substrate to form a film are also within the scope of the present invention. In addition, the substrate can be further processed to produce patterns or complex microstructures in or on the membrane. Microstructure types include, but are not limited to, electronic, mechanical and optical elements. The type of processing performed to generate the pattern and microstructure on the substrate or film is not limited by the present invention. In certain embodiments, the substrate is not processed. In these embodiments, process 110 may be omitted.

  After the substrate has been thinned and / or processed in other ways, it can be referred to as a membrane. This film remains fixed to the carrier by the binder applied in process 100. As shown in process 120, the carrier having the processed film is then aligned to the receiving substrate. To do this, the carrier can be oriented so that the membrane is secured to the bottom surface of the carrier. As described above, in other embodiments, the receiving substrate is disposed on the carrier and the membrane is secured to the top surface of the carrier. Any orientation can be employed in which the membrane is fixed to the carrier and placed between the carrier and the receiving substrate.

  Thereafter, the carrier is moved closer to the receiving substrate. Alignment is achieved by moving at least one of the carrier and receiving substrate relative to the other. Both the carrier and the receiving substrate can include alignment marks to facilitate the alignment process. The alignment can be performed using a vision system or some other system.

  During alignment, the carrier is moved toward the receiving substrate as shown in process 130. Surface-to-surface contact bonding (often referred to as van der Waals bonding) can be used to attach the membrane fixed to the carrier to a pre-attached membrane of the receiving substrate or laminate. Permanent adhesives and other adhesion promoting materials can also be used during this attachment process. It is also possible to use an annealing process to form a covalent or quasi-covalent bond between the membrane and the receiving substrate or other processed membrane. In some embodiments, the annealing process is performed after each film is added to the stack of films. In other embodiments, the annealing process is performed after lamination is complete.

  Once bonding occurs between the article mounted on the carrier and the receiving substrate, or between the article mounted on the carrier and the article placed on the receiving substrate, the bonding is then performed as shown in process 140. The agent is transferred from solid to gas. This can be done by vaporization or sublimation. This can be done using pressure, temperature and / or electromagnetic radiation. The pressure can be global (which means that the carrier-binder-membrane system is enclosed in a vacuum chamber) or locally (at least part of the carrier-binder-membrane system is vacuumed). Meaning that it is mounted in the chamber). The temperature can likewise be varied locally or globally. The binder, which is now gaseous, can be allowed to escape into and / or through the pores of the carrier, or into and / or through channels within the article, facilitating separation of the article from the carrier. In other embodiments, the gas can escape from the carrier even if the carrier does not have holes. In other embodiments, the carrier itself may be vaporized or sublimated.

  In one embodiment, the carrier can then be used again to process other substrates into films and the processes 100-140 of FIG. 4 can be repeated. In another embodiment, the carrier itself is disposable and therefore discarded or vaporized. At the same time that the first article is attached directly to the receiving substrate, a subsequent article can be attached on or adjacent to the pre-mounted article, thereby building a three-dimensional structure. The annealing process described above can help bond adjacent articles together.

  In certain embodiments, the above disclosure provides a solid binder that, when heated, depressurized or otherwise stimulated, first melts, decomposes or dissolves into a liquid and then transitions to a gas by volatilizing into the gas phase. explain.

  In certain embodiments, it may be advantageous for the permeable carrier 10 and / or article to be able to absorb the liquid state binder 15 from the gap between the carrier 10 and the article when the binder 15 melts. is there. The 15 liquid state of the binder can be achieved by melting the binder, but the liquid formed by the decomposition of one or more binders and the dissolution of one or more binders in the molten state of another binder. Is also possible. One mechanism for removing the binder 15 from the gap between the article and the carrier 10 is to suck the liquid state binder 15 into the carrier 10. This is because the gap between the article and the carrier 10 is the characteristic length of the carrier hole so that the capillary force of the carrier 10 matches or exceeds the meniscus surface energy between the carrier 10 and the article. It is likely to occur when the scale is the same or larger than the dimensions. That is, when the binder 15 is transferred to a gas, the permeable carrier 10 or the article can absorb the binder 15 in the liquid state entirely or partially from the gap between the carrier 10 and the article. The liquid state binder 15 can then volatilize and pass through the carrier 10 and / or through the carrier, or through and / or through the article.

  Although liquids are known to be absorbed by permeable carriers, the optimal pore structure for desorption is not obvious. In one embodiment, the pore structure has a small characteristic length and a correspondingly high capillary force, but the flow rate is limited due to viscosity loss. In another embodiment, the length dimension of the pore structure is large and supports higher flow rates, but the capillary force may not be strong enough to completely absorb the binder. In another embodiment, the void volume of the carrier is collected such that the binder can be vaporized or sublimated on the article side and collected in the bulk or along the backside due to thermal or pressure gradients within the carrier 10. Large enough to act as a container. In another embodiment, the pore structure has a length dimension that provides higher porosity and capillary force, making it more suitable to desorb an article with a large patterned surface area. In another embodiment, the carrier swells when its pore structure absorbs the binder, allowing the carrier to warp from the article during the desorption process.

  When the liquid state binder 15 wets at least the carrier 10 or the article, at least the capillary force in the carrier 10 or article causes the liquid state binder 15 to move from the region between the article and the carrier 10 at least on the carrier 10. It can be made large enough to be drawn into the surface of the hole or article. With sufficient porosity (ratio of void volume to total volume), the carrier 10 or article can be used to preserve most or all of the liquid state binder 15. A typical opening area ratio of the capillary array is about 20%. In contrast, the porosity of the porous network can be 95% or more, or about 5 times or more. Thus, in the first example, the required absorption thickness of the carrier, i.e., the thickness of the carrier required to completely absorb a given layer thickness of the binder, is about 5 times thicker than in the second example. For applications that require a thick binder layer and a thin carrier, a highly porous carrier may be desirable. For applications that require a thin binder layer, the capillary array can be sufficient to collect the binder.

  In one embodiment, the carrier 10 can absorb the binder 15 by convection or diffusion. For example, polydimethylsiloxane (PDMS) can absorb naphthalene and is permeable to gases. It has been found that PDMS carriers bonded to a silicon substrate absorb the binder when vaporized, thereby causing the PDMS to expand and separate from the substrate. After the substrate is detached, the PDMS carrier is cooled and the binder becomes visible when solidified. Thus, in this embodiment, the carrier acts as a collection material for the vaporized binder. That is, the binder vaporizes in the carrier 10 but does not necessarily pass through the carrier 10. Furthermore, the carrier can act as a storage medium for some or all of the binder.

  It is known that liquids that permeate porous materials may be blocked by gas trapped in the pores. This phenomenon is known as vapor blockage. Liquid infiltration is defined as the ratio of the void volume of the porous material to the fluid volume within the porous material. Incomplete infiltration may occur due to vapor blockage because the formation of bubbles in the pores can block the flow. It is not obvious that a binder can be used to improve infiltration in the presence of vapor blockage. In one embodiment, bubbles having a meniscus are generated by sublimation, vaporization and / or decomposition of the binder 15 in the pores. As the bubble grows, the meniscus can come into contact with the pore walls and adhere in place to impede flow. Meniscus can be classified into upstream meniscus and downstream meniscus. As known as the Gibbs-Maragoni effect, the upstream meniscus is at a different temperature than the downstream meniscus, i.e., different surface energy, and there is a greater amount of condensation at the downstream meniscus than at the upstream meniscus. This transports the binder through the bubbles and prevents vapor blockage.

  The wetting properties of the carrier 10 can play a more important role in transporting the binder 15 to the carrier than transport that acts purely by Darcy's law describing the flow rate of fluid through the porous material. As a result of the different pore sizes within the airgel or xerogel, nanopores will absorb material more strongly than micropores. The airgel carrier may not support large flow rates through the material, but exhibits a capillary force significantly greater than the surface tension caused by the fluid flowing into the capillary array and can generally support greater porosity. Both pore structures can transport a vaporizable binder in the liquid state, but in some embodiments, the sol-gel can contain more binder and with greater force the binder. May be beneficial in terms of absorbing

  Thus, various carriers can be used to retain, collect, and store the condensed or solidified state of the binder 15. In these embodiments, the binder 15 melts, volatilizes, vaporizes, decomposes or sublimates partially or entirely as it is transported to the permeable carrier 10, thereby occupying the internal pores. This transport of the binder 15 to the carrier ensures that the substrate 20 is removed from the carrier 10 with low stress since there is little or no surface tension to hold the substrate 20 to the carrier 10. That is, since the liquid binder is absorbed from the base material 20, the base material 20 can be easily separated from the carrier 10.

  In certain embodiments, after the binder 15 has been transported into the pores of the permeable carrier 10, the binder 15 can volatilize, vaporize, sublime, or decompose and pass through the carrier 10. In other embodiments, the binder 15 can remain in the pores of the permeable carrier 10 for a longer period in the gas phase, liquid phase, or solid phase.

  Thus, a vaporizable binder can be used in the flowchart of FIG. 4, wherein process 140 includes an intermediate transition of the binder to the liquid state, where the liquid is transferred to the carrier.

  As described above, the binder can be vaporized by raising the temperature of the surrounding environment, lowering the pressure of the environment, or both locally or globally. This causes the binder to first vaporize on the outer surface exposed to the surrounding environment. As their outer surfaces vaporize, the process continues.

  The present invention should not be limited in scope by the specific embodiments described herein. Indeed, various other embodiments and modifications to the present invention in addition to those described herein will be apparent to those skilled in the art from the foregoing description and accompanying drawings. Accordingly, such other embodiments and modifications are intended to be included within the scope of the present invention. Further, although the present invention has been described herein in a specific implementation in a specific environment for a specific purpose, those skilled in the art will not be limited in their usefulness. It will be appreciated that the present invention can be advantageously implemented in any environment for any purpose. Accordingly, the claims should be construed in view of the full scope and spirit of the invention as described herein.

10 carrier 15 binder 20 substrate

Claims (20)

A method for separating an article attached to a carrier by a binder, comprising:
Transferring the binder from a solid state to a liquid state; and sucking the liquid state from a gap between the carrier and the article to release the article from the carrier.   The method of claim 1, wherein the carrier is permeable.   The method of claim 2, wherein the binder transitions to the liquid state by at least one of decomposition or melting.   The method of claim 2, wherein the liquid state binder is stored at least partially within the permeable carrier.   The method of claim 2, wherein the liquid state binder is transferred to a gas and passes through the permeable carrier.   The method of claim 2, wherein the liquid state binder is transferred to a gas and at least a portion of the gas is collected on the permeable carrier in at least one state, liquid or solid.   The method of claim 1, wherein the liquid state binder is transferred to a gas. A method for separating articles,
A method comprising peeling an article from said binder by transferring the binder from a solid by increasing the temperature of the local or global atmosphere or decreasing the pressure.   The method of claim 8, wherein the binder is vaporizable or sublimable.   The binder has one or more cores and one or more handles to optimize at least one of solvent solubility, chemical resistance, cohesion, adhesion, melting point, heat capacity and vapor pressure. 10. The method of claim 9, comprising a molecule.   10. A method according to claim 9, wherein the binder decomposes or is structurally modified into one or more sublimable or vaporizable species.   10. The method of claim 9, wherein the binding agent undergoes a photoinitiated split or is structurally changed to one or more agents having a high vapor pressure.   The method of claim 8, wherein the binder attaches the article to the carrier.   The method of claim 13, wherein the carrier is permeable.   15. The method of claim 14, wherein the permeable carrier comprises at least one of an airgel, xerogel, or other material made from a soluble gel.   The method of claim 14, wherein the permeable carrier comprises at least one of a capillary array, a frit, or a porous fiber material.   The method of claim 14, wherein the permeable carrier comprises an embedded structure that is not porous.   The method of claim 17, wherein the embedded structure adjusts the thermal, electromagnetic, fluid, or mechanical properties of the permeable carrier. A method of forming a film by processing a substrate,
Mixing a first binder having a first melting point with a second binder having a second melting point higher than the first melting point to form a binder mixture;
Melting the binder mixture;
Using the molten binder mixture to bond a carrier to the substrate;
Vaporizing, sublimating or otherwise removing the first binder from the binder mixture, leaving the second binder;
After the first binder is removed from the binder mixture, the substrate is processed to form a film; and after the processing, the binder mixture is sublimated or vaporized to remove the film from the carrier. A method comprising removing from.   20. The method of claim 19, wherein the temperature at which the bonding occurs is lower than the temperature at which any component of the mixture melts.

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