WO2003078304A2

WO2003078304A2 - Surface relief structures for joining and adhesion

Info

Publication number: WO2003078304A2
Application number: PCT/US2003/008117
Authority: WO
Inventors: Renyuan Gao; Anthony F. Garito; Donald Bitting; Joseph Chang; Kazuya Takayama
Original assignee: Photon-X, Inc.
Priority date: 2002-03-15
Filing date: 2003-03-17
Publication date: 2003-09-25
Also published as: WO2003078304A3; AU2003220334A1; AU2003220334A8

Abstract

A solid substrate comprising a first major surface and a second major surface juxtaposed from and parallel or substantially parallel to the first major surface, wherein the substrate has a plurality of surface relief structures located on the substrate between the first major surface and second major surface, and further wherein the substrate has at least one channel extending through the substrate between the first and second major surfaces.

Description

SURFACE RELIEF STRUCTURES FOR JOINING AND ADHESrON CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional Patent Application Serial No. 60/364,865 filed March 15, 2002, which is herein incorporated by reference.

FIELD OF THE INVENTION

[001] The present invention relates to surface relief structures for joining and adhering to solid materials.

BACKGROUND OF THE INVENTION

[002] Methods for joining two solid materials are well known. For example, dovetails and snap-on features are routinely used in mechanical parts made from various materials, such as plastics, to join two or more pieces together. These joining features are made by a variety of techniques such as injection molding. However, such features are macroscopic in dimensions and are not applicable on smaller scales.

[003] Solid substrates are also well known in electronics and optics fields as a base for fabricating a plurality of generally small components in micrometer and nanometer sized areas. Such solid substrates can be comprised of an array of materials, both inorganic and organic, that include, for example, silicon, glasses, crystals, metals, compound semiconductors, ceramics, and polymers. Devices utilizing these solid substrates often require joining or adhesion of multiple materials on micrometer and nanometer levels. Thus, it is desirable to have micrometer or nanometer sized features that serve as joints and adhesive interfaces.

SUMMARY OF THE INVENTION

[004] The present invention describes a device and associated fabrication methods for realizing surface relief structures on solid substrates to serve in joining and SUMMARY OF THE INVENTION

[004] The present invention describes a device and associated fabrication methods for realizing surface relief structures on solid substrates to serve in joining and adhering multiple materials to a solid substrate on micrometer and nanometer length scales. The present invention, more specifically, relates to a solid substrate comprising a first major surface and a second major surface juxtaposed from and parallel or substantially parallel to the first major surface, wherein the substrate has a plurality of surface relief structures located on the substrate between the first and second major surfaces, and further wherein the substrate has at least one channel extending through the substrate between the first and second major surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

[005] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate the presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention. In the drawings:

[006] Fig. 1 is a perspective view of a substrate according to a first embodiment of the current invention.

[007] Fig. 1 A is an end view of a single solid substrate according to a first embodiment of the current invention. [008] Fig. 2 is an end view of a superstrate adhered to the underlying substrate according to a first embodiment of the current invention. The surface relief pedestal structures serve as the adhesion and joint interface.

[009] Fig. 3 shows the scanning electron micrographs (SEMs) of exemplary surface relief pedestal structures on a solid substrate.

[010] Fig. 4 shows the photo-lithographic mask pattern of exemplary surface relief pedestal structures.

. [011] Fig. 5 shows the perspective view of a second embodiment of the current invention.

[012] Fig. 5A shows the end view of a second embodiment of the current invention.

[013] Fig. 5B is an end view of a superstrate adhered, or joined to the underlying substrate according to a second embodiment of the current invention. The surface relief pedestal structures serve as the adhesion and joint interface.

[014] Fig. 6 shows the perspective view and top view of a third embodiment of the current invention.

[015] Fig. 6A shows the perspective view and top view of a third embodiment of the current invention.

[016] Fig. 6B is an end view of a superstrate adhered, or joined to the underlying substrate according to a third embodiment of the current invention. The surface relief pedestal structures serve as the adhesion and joint interface. [017] Fig. 7 is an end view of a superstrate adhered to the underlying substrate according to a fourth embodiment of the current invention. The surface relief pedestal structures serve as the adhesion and joint interface.

DETAILED DESCRIPTION OF THE INVENTION

[018] In the following description, reference is made to the accompanying drawings that form a part thereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention can be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments can be utilized and that changes can be made without departing from the scope of the present invention.

[019] The presently claimed invention thus relates, in one embodiment, to a solid substrate comprising a first major surface and a second major surface juxtaposed from and parallel or substantially parallel to the first major surface, wherein the substrate has a plurality of surface relief structures located on the substrate between the first major surface and second major surface, and further wherein the substrate has at least one channel extending through the substrate between the first and second major surfaces. The solid substrate 10 is illustrated in one embodiment in Fig. 1. In the drawings, like numerals indicate like elements throughout.

[020] The solid substrate 10 can be formed, in one embodiment, from inorganic materials, organic materials, and mixtures or blends of both types of materials. Suitable organic materials include polymeric materials which include, but are not limited to, thermoplastic materials, thermoset materials, and mixtures or blends thereof. Suitable thermoplastic materials include, but are not limited to, polycarbonate, polyacrylate, polymethyl methacrylate, cellulosic thermoplastic elastomer, poly(ethylene butyl acrylate), poly(ethylene vinyl alcohol), ethylene tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polyetherimide, polyethersulfone, polyetheretherketone, polyperfluoroalkoxyethylene, nylon, polybenzimidazole, polyester, polyethylene, polynorbornene, polyimide, polystyrene, polysulfone, polyvinyl chloride, polyvinylidene fluoride, an ABS polymer such as polyacrylonitrile butadiene styrene, acetal copolymer, poly[2,2-bistrifluoromethyl-4,5-difluoro-1 ,3-dioxole-co- tetrafluoroethylene], poly[2,3-(perfluoroalkenyl) perfluorotetrahydrofuran], poly[2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole-co-tetrafluoroethylene], poly[2,2-bisperfluoroalkyl-4,5-difluoro-1,3-dioxole-co-tetrafluoroethylene], poly(pentafluorostyrene), fluorinated polyimide, fluorinated polymethylmethacrylate, polyfluoroacrylates, polyfluorostyrene, fluorinated polycarbonates, fluorinated poly (N-vinylcarbazole), fluorinated acrylonitrile- styrene copolymer, fluorinated Nation®, fluorinated poly(phenylenevinylene), perfluoro-polycyclic polymers, polymers of fluorinated cyclic olefins, copolymers of fluorinated cyclic olefins, and mixtures or blends of any of the foregoing.. Suitable thermoset materials include, but are not limited to, diallyl phthalate, epoxy, furan, phenolic, thermoset polyester, polyurethane, and vinyl ester polymer. [021] The substrate 10 can be manufactured from any of the above-listed homopolymers, and corresponding copolymers, terpolymers, or combinations, or blends of the above-listed polymers together with polymer composites.

[022] Suitable inorganic materials useful in forming the solid substrate 10 include, but are not limited to, silicon, glass, crystal, metals, compound semiconductors, ceramics, and mixtures thereof.

[023] Non-limiting examples of semiconductor materials include, for example, Si, Ge, SiGe, GaP, GaAs, GaN, InP, InAs, InSb, PbSe, PbTe, InGaAs, and mixtures thereof, including other stoichiometries and compositions. Other non-limiting examples of semiconductor materials include, for example, semiconductor materials doped with an appropriate ion.

[024] In another non-limiting embodiment of the present invention, the substrate 10 can comprise glass, ceramic, crystal, and alloy compounds and complexes, such as, for example, oxides, phosphates, halophosphates, phosphinates, arsenates, sulfates, borates, borides, carbides, aluminates, gallates, silicates, germanates, vanadates, niobates, tantalites, tungstates, molybdates, alkalihalogenates, halogenides, nitrides, selenides, sulfides, sulfoselenides, tetrafluoroborates, hexafluorophosphates, phosphonates, and oxysulfides.

[025] In yet another non-limiting embodiment, the substrate 10 can comprise Piezoelectric ceramic materials, such as, for example, Barium Titanate, Lead Zirconate Titanate, Lead Titanate, Magnesium Niobate, Lead Metaniobate, Lead Zirconate Titanate, and Lead Nickel Niobate. [026] In another non-limiting embodiment, the substrate 10 can comprise metals, such as, for example, aluminum, magnesium, iron, copper, tin, titanium, zinc, tungsten, gold, silver, platinum, and metal alloys comprised of the above list of metals, together with other ions and compounds.

[027] In still another non-limiting embodiment, the substrate 10 can comprise transition metal elements, rare-earth metal elements, the actinide element uranium, group VA elements, and group IVA elements in the form of, for example, ions, alloys, compounds, composites, complexes, chromophores, dyes and polymers. Examples of such materials include, but are not limited to, Ce³⁺, Pr³⁺, Nd³⁺, Pm³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb³⁺, V²⁺, V³⁺, Cι*\ Cr³⁺, Cr⁴⁺, Mn⁵⁺, Co²⁺, Fe²⁺, Ni²⁺, Ti³⁺, U³⁺, and Bi³⁺.

[028] In another non-limiting embodiment, the substrate can comprise composite materials that include polymer nanocomposites. Such composite materials may include nanoparticles distributed within a host matrix material. Nanoparticles are particles of a material that have a size measured on a nanometer scale. Nanoparticles may be larger than a cluster (which in certain embodiments might only comprise a few hundred atoms), but with a relatively large surface area-to-bulk volume ratio. Historically, most nanoparticles have a size ranging from about 10nm to about 500 nm, but in the present invention, the nanoparticles may have a size, for example, ranging from about 1 nm to about 1x10³ nm, such as from about 10 nm to about 500 nm. Nanoparticles can be made from a wide array of materials, such as, for example, transition metals, rare-earth metals, group VA elements, polymers, dyes, semiconductors, alkaline earth metals, alkali metals, group MIA elements, and group IVA elements.

[029] Further, nanoparticles themselves may be considered a nanoparticle composite, which may comprise a wide array of materials, single elements, mixtures of elements, stoichiometric and non-stoichiometric compounds. The materials may be crystalline, amorphous, or mixtures or combinations of such structures.

[030] The host matrix material may comprise a random glassy matrix, such as, for example, a semi-crystalline or amorphous organic polymer. Non- limiting examples of organic polymers include hydrocarbon polymers and halogenated polymers.

DETAILED DESCRIPTION OF THE DRAWINGS

[031] The substrate 10 has a first major surface 12, and a second major surface 14 juxtaposed from and generally parallel to the first major surface. See Figure 1. In certain embodiments, a plurality of surface relief structures are shown extending through the substrate 10 between at least the first (12) and second (14) major surfaces of the present invention. In one embodiment, a plurality of surface relief structures extend across the substrate between a first end 16 and a second end 18 and between a third end 20 and a fourth end 22. One of ordinary skill in the art will understand that the channels created by the plurality of surface relief structures need not necessarily extend entirely throughout the substrate surface. [032] In one non-limiting embodiment depicted in Figure 1A, the surface relief structures of Figure 1 are comprised of a plurality of pedestals having a characteristic shape determined by the ratio of the top and bottom cross-

sectional areas σi and σ₂, respectively, and the distance of that separates σi and

σ₂. The shape of each pedestal is determined by the following relationships:

σi ≥ o"2

σ₂ ≥ σ-ι/5

and

d²<100σ₂

[033] In one non-limiting embodiment, described in Figure 1 B, the surface relief pedestal structure of the solid substrate X acts as an adhering and joining interface to a second surface relief structure of the solid superstrate Y, wherein the surface relief structure of the superstrate can be uniformly interposed with the individual pedestals of the underlining substrate, such as, for example, in a dovetail pattern.

[034] The surface relief features of the substrate and the superstrate can be fabricated by a wide variety of methods, such as, for example, wet etching, dry etching, injection molding, stamping, embossing, printing, extrusion, and other related techniques.

[035] Figure 3 depicts an exemplary embodiment of the surface relief structure on a solid substrate according to the current invention that is fabricated by the dry etching method, plasma etching, or reactive ion etching (RIE). The solid substrate shown in the figure is comprised of a polymer. [036] Figure 4 depicts an exemplary embodiment of the photolithographic mask pattern that may be utilized in the fabrication of the surface relief structure on the substrate.

[037] Figure 5 depicts a non-limiting embodiment of the surface relief structure on a solid substrate according to the present invention. The substrate 10 has a first major surface 12 and a second major surface b juxtaposed from and generally parallel to the first major surface 12. In certain embodiments, a plurality of surface relief structures are shown extending through the substrate 10 between the first (12) and second (14) major surfaces of the present invention. In one embodiment, a plurality of surface relief structures extend across the substrate between a first end 16 and a second end 18, and between a third end 20 and a fourth end 22. One of the ordinary skill in the art will understand that the channels created by the plurality of surface relief structures do not necessarily extend entirely throughout the substrate surface.

[038] In one non-limiting embodiment depicted in figure 5A, the surface relief structures of Figure 5 are comprised of a plurality of pedestals having a characteristic shape. The characteristic feature is determined by the ratio of the

top and bottom cross-sectional areas σi and σ₂, respectively, and the distance d

that separates σi and σ₂. The shape of each pedestal is determined by the following relationships:

0"1 ≥ σ₂

σ₂ ≥ σ-ι/5 and d²<100σ₂

[039] In one non-limiting embodiment, described in Figure 5B, the surface relief pedestal structure of the solid substrate X acts as an adhering and joining interface to a second surface relief structure of the solid superstrate Y, wherein the surface relief structure of the superstrate can be uniformly interposed with the individual pedestals of the underlining substrate, such as, for example, in a lock-and-key pattern.

[040] Figure 6 depicts a non-limiting embodiment of the surface relief structure on a solid substrate according to the current invention. The substrate 10 has a first major surface 12 and a second major surface 14 juxtaposed from and generally parallel to the first major surface. In certain embodiments, a plurality of surface relief structures are shown extending through the substrate 10 between the first (12) and second (14) major surfaces of the present invention. A non- limiting example involves a plurality of surface relief structures extending through the substrate between the first 12 and second 14 major surfaces of the present invention.

[041] In one embodiment, a plurality of surface relief structures extend across the substrate between a first end 16 and a second end 18, and between a third end 20 and a fourth end 22. One of ordinary skill in the art will understand that the channels created by the plurality of surface relief structures need not necessarily extend entirely throughout the substrate surface.

[042] In one non-limiting embodiment depicted in figure 6A, the surface relief structures of figure 6 are comprised of a plurality of pedestals having a characteristic shape. The characteristic feature is determined by the ratio of the

top and bottom cross-sectional areas σi and σ₂, respectively, and the distance of

that separates σi and σ₂. The shape of each pedestal is determined by the

following relationships:

σi > σ₂

σ₂ ≥ σ-ι/5 and

d²<100σ₂

[043] In one non-limiting embodiment described in figure 6B, the surface relief pedestal structure of the solid substrate X acts as an adhering and joining interface to a second surface relief structure of the solid superstrate Y, wherein the surface relief structure of the superstrate is uniformly interposed with the individual pedestals of the underlining substrate, such as in a lock-and-key pattern.

[044] In one non-limiting embodiment, the at least one pedestal can have generally circular, square, rectangular, and oval cross-sections. However, those skilled in the art will recognize that other geometric shapes can be used as well. Also, while a plurality of pedestals are shown, those skilled in the art will also recognize that only one channel need be used.

[045] In another non-limiting embodiment, the at least one channel formed between at least two rows each comprising a plurality of surface relief structures can be open to ambient air or filled with a filler material. Non-limiting examples of such filler material include, but are not limited to, fluids, polymers, metals, glass, insulators, and mixtures thereof. The filler material may be added to the at least one channel, for example, by injecting the desired material into the channel.

[046] The substrate 10 itself can be manufactured by any known method and each channel can be formed after manufacture of the substrate by, for example, drilling, laser etching, reactive ion etching, or any other method known to those skilled in the art.

[047] The substrate 10 can, for example, be injection molded, such as with at least one spacer inserted into the cavity formed by the mold. The material of the substrate can then be injected into the mold, and the material forms around the spacer. The substrate may then be released from the mold and the spacer may be removed, forming the at least one channel located where the spacer was inserted.

[048] A fourth embodiment of a substrate 200 is shown in Fig. 7. In this embodiment, the substrate 200 can have a first portion 210 and a second portion 220. The first portion 210 has a first major interior surface 212 and a first major exterior surface 214. A plurality of channels 230 are formed in the first portion 210 such that each channel 230 is in fluid communication with the first major interior surface.

[049] The second portion 220 has a second major interior surface 222 and a second major exterior surface 224. The first major interior surface 212 is fixedly connected to the second major interior surface 222, such that each channel is generally enclosed between the first and second major interior surfaces. In a non-limiting embodiment, the first major interior surface 212 is fixedly connected to the second major interior surface 222 with an adhesive, such as, for example, epoxy, although those skilled in the art will recognize that other methods of connection may be used, such as, for example, solvent bonding or ultrasonic bonding.

[050] A non-limiting method of manufacturing the substrate can involve selecting a first portion and forming channels in the first major interior surface, such as, for example, by reactive ion etching, molding, stamping or other process known to those skilled in the art. After the channels are formed, the second portion is aligned with and disposed on the first portion, as shown in Fig. 7.

[051] The channels can then be filled with a filler. Useful fillers include, but are not limited to, gases, liquids, polymers, metals, and mixtures thereof.

[052] Potential uses of the embodiments described above include uses that will be recognized by those skilled in the art, such as, for example, adjusting the coefficient of thermal expansion (CTE) of the substrate, heat dissipation, thermal insulation, light propagation, and illumination.

[053] A non-limiting example of a potential use for any of the aforementioned substrates described above is as a substrate for planar optical waveguides, as disclosed in U.S. Patent Application Serial No. 09/877,871 , filed June 8, 2001 (Attorney Docket No. PHX-0016), U.S. Patent Application Serial No. 09/971 ,157, filed October 4, 2001 (Attorney Docket No. PHX-0016C1), U.S. Patent Application Serial No. 10/045,317, filed November 7, 2001 (Attorney Docket No. PHX-0038), and U.S. Patent Application Serial No. 10/243,833, filed September 16, 2002 (Attorney Docket No. PHX-0048), all of which are owned by the assignee of the current invention and all of which are incorporated herein by reference in their entireties.

[054] It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

What is claimed is:

1. A solid substrate comprising: a first major surface; and a second major surface juxtaposed from and parallel or substantially parallel to the first major surface; wherein the substrate has a plurality of surface relief structures located on the substrate between the first major surface and second major surface, and further wherein the substrate has at least one channel extending through the substrate between the first and second major surfaces.

2. The solid substrate according to claim 1 , wherein the substrate is selected from organic and inorganic materials.

3. The solid substrate according to claim 2, wherein the substrate comprises at least one inorganic material selected from silicon, glasses, crystals, metals, compound semiconductors, ceramics, and mixtures thereof.

4. The solid substrate according to claim 2, wherein the substrate comprises at least one organic material selected from thermoplastic materials, thermoset materials, and mixtures thereof.

5. The solid substrate according to claim 3, wherein the composite materials further comprise at least one polymer nanocomposite.

6. The solid substrate according to claim 1 , wherein the at least one channel is at least partially filled with at least one filler material.

7. The solid substrate according to claim 6, wherein the at least one filler material is selected from fluids, polymers, metals, glass, insulators, and mixtures thereof.

8. The solid substrate according to claim 1 , further comprising an optical waveguide disposed on the first major surface.

9. The planar substrate according to claim 8, wherein the optical waveguide comprises at least one polymer.

10. The planar substrate according to claim 1 , wherein the substrate comprises a first substrate portion fixedly connected to a second substrate portion.

11. The planar substrate according to claim 1 , wherein the substrate comprises a first substrate portion having a first interior surface, wherein the at least one channel is in fluid communication with the first interior surface, and a second substrate portion having a second interior surface, wherein the first and second interior faces are generally in contact with each other.

12. A polymer substrate comprising: a first generally planar portion having a first major interior surface, wherein the first generally planar portion includes at least one channel extending therein that is in fluid communication with the first major interior surface; and a second generally planar portion having a second major interior surface, wherein the first and second major interior surfaces are fixedly connected to each other.

13. A method of manufacturing a polymer substrate comprising: providing a first substrate portion having a first major interior surface; providing a second substrate portion having a second major interior surface; generating at least one channel in the first major interior surface; and fixedly connecting the first major interior surface and the second major interior surface.

14. The method according to claim 13, further comprising at least partially filling the at least one channel with a filler material.

15. The method according to claim 13, wherein generating the at least one channel comprises etching the at least one channel.