Functional nanoparticles

The application claims the benefit under 35 U.S.C. §119(e)(1) of U.S. Provisional Application No. 61/236,957, filed on Aug. 26, 2009, which is hereby incorporated by reference in its entirety.

Nano-fabrication includes the fabrication of very small structures that have features on the order of 100 nanometers or smaller. Although well known within the integrated circuit industry, nano-fabrication techniques may be applied in the bio-domain, solar cells industry, battery industry and/or other industries. See, for example, U.S. Patent Publication No. 2007/0031505, U.S. Pat. No. 6,918,946, U.S. Patent Publication No. 2008/0121279, Kelly, J. and DeSimone, J., Shape - specific monodisperse nano - molding of protein particles , J. Am. Chem. Soc. 2008, vol. 130, pgs. 5437-5439, and Canelas, D., Herlihy, K, and DeSimone, J., Top - down particles fabrication: control of size and shape for diagnostic imaging and drug delivery , WIREs Nanomedicine and Nanobiotechnology, 2009, vol. 1, pgs. 391-404.

Imprint lithography techniques include formation of a relief pattern in a formable layer positioned on a substrate. The substrate may be coupled to a motion stage to obtain a desired positioning to facilitate the patterning process. The patterning process may use a template spaced apart from the substrate and the formable liquid applied between the template and the substrate. The formable liquid is solidified to form features on the substrate conforming to the shape of the template that contacts the formable liquid. After solidification, the template is separated from the features and the substrate is subjected to additional processing to form functional nanoparticles (e.g., drug delivery devices, batteries, and the like).

So that the present invention may be understood in more detail, a description of embodiments of the invention is provided with reference to the embodiments illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of the invention, and are therefore not to be considered limiting of the scope.

FIG. 1 illustrates a simplified side view of a lithographic system in accordance with embodiments of the present invention.

FIG. 2 illustrates a simplified side view of the substrate shown in FIG. 1 having a patterned layer positioned thereon.

FIG. 3 illustrates a simplified side view of the substrate shown in FIG. 2 having multiple protrusions formed thereon.

FIG. 4 illustrates a simplified side view of a pillar formed by release of the protrusions of FIG. 3 .

FIGS. 5A-5F illustrate simplified side views of formation of pillars in accordance within an embodiment of the present invention.

FIGS. 6A-6C illustrate perspective views of exemplary pillars.

FIG. 7 illustrates a flow chart of an exemplary method 100 of forming pillars 52 a using imprint lithography.

FIGS. 8A-8E illustrate simplified side views of formation of pillars in accordance with an embodiment of the present invention.

Referring to the figures, and particularly to FIGS. 1 and 2 , illustrated therein is a lithographic system 10 used to form functional nano and/or micro particles on substrate 12 . Substrate 12 may be coupled to substrate chuck 14 . As illustrated, substrate chuck 14 is a vacuum chuck. Substrate chuck 14 however, may be any chuck including, but not limited to, vacuum, pin-type, groove-type, electrostatic, electromagnetic, and/or the like. Exemplary chucks are described in U.S. Pat. No. 6,873,087, U.S. Ser. Nos. 11/108,208, 11/047,428, 11/047,499, and 11/690,480, all of which are hereby incorporated by reference herein in their entirety.

Substrate 12 and substrate chuck 14 may be further supported by stage 16 . Stage 16 may provide rotational and/or translational motion in relation to the x, y and z axes. Stage 16 , substrate 12 , and substrate chuck 14 may also be positioned on a base (not shown).

Spaced-apart from substrate 12 is template 18 . Template 18 may include mesa 20 extending therefrom towards substrate 12 , with mesa 20 having a patterning surface 22 thereon. Further, mesa 20 may be referred to as mold 20 . Alternatively, template 18 may be formed without mesa 20 .

Template 18 and/or mold 20 may be formed from such materials including, but not limited to, fused-silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, hardened sapphire, and/or the like. As illustrated, patterning surface 22 comprises features defined by a plurality of spaced-apart recesses 24 and/or protrusions 26 , though embodiments of the present invention are not limited to such a configuration. For example, patterning surface 22 may be substantially flat. Generally, patterning surface 22 may be defined as any original pattern that forms the basis of a pattern to be formed on substrate 12 . Additionally, template 18 may be treated with an anti-adhesion agent (e.g., Relmat, FTOS). Exemplary anti-adhesion agents include, but are not limited to those described in U.S. Ser. No. 09/976,681, which is hereby incorporated by reference in its entirety.

Template 18 may be coupled to chuck 28 . Chuck 28 may be configured as, but not limited to, vacuum, pin-type, groove-type, electrostatic, electromagnetic, and/or other similar chuck types. Exemplary chucks are further described in U.S. Pat. No. 6,873,087, which is hereby incorporated by reference herein in its entirety. Further, chuck 28 may be coupled to imprint head 30 such that chuck 28 and/or imprint head 30 may be configured to facilitate movement of template 18 . Additionally, chuck 28 may be configured to adjust and/or vary the structure of template 18 prior to imprinting, during imprinting, and/or subsequent to imprinting (e.g. during separation).

System 10 may further comprise fluid dispense system 32 . Fluid dispense system 32 may be used to deposit functional material 34 a on substrate 12 . Functional material 34 a may have use within the bio-domain, solar cell industry, battery industry, and other industries requiring a functional nano-particle. For example, functional material 34 a may include, but is not limited to, biomaterials (e.g., PEG), solar cell material (e.g., N-type material, P-type material), polymerizable materials, and/or the like.

Functional material 34 a may be positioned on substrate 12 using techniques such as drop dispense, spin-coating, dip coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), thin film deposition, thick film deposition, and/or the like. It should be noted that the positioning of functional material 34 on substrate 12 may be configured to limit the amount of waste. For example, use of drop dispense in positioning of functional material 34 on substrate 12 , as compared to spin-coating and the like, may limit the amount of non-useable fluid during formation of functional nanoparticles.

Substrate 12 may include the use of a removable layer 50 . Removable layer 50 may facilitate separation of solidified functional material 34 a from substrate 12 as described herein. Examples of materials for use in removable layer 50 may include, but are not limited to PVA or PMMA.

Referring to FIGS. 1 and 2 , system 10 may further comprise solidification source 38 (e.g., energy source) coupled to direct a medium 40 (e.g., energy) along path 42 to solidify functional material 34 a . Imprint head 30 and stage 16 may be configured to position template 18 and/or substrate 12 in superposition with path 42 . System 10 may be regulated by processor 54 in communication with stage 16 , imprint head 30 , fluid dispense system 32 and/or source 38 , and may operate on a computer readable program stored in memory 56 .

Either imprint head 30 , stage 16 , or both may vary a distance between mold 20 and substrate 12 to define a desired volume therebetween that is filled by functional material 34 a . For example, imprint head 30 may apply a force to template 18 such that mold 20 contacts functional material 34 a . After the desired volume is filled with functional material 34 a , source 38 may produce medium 40 , e.g. UV radiation, causing functional material 34 a to solidify and/or cross-link conforming to a shape of surface 44 of substrate 12 and patterning surface 22 , defining patterned layer 46 on substrate 12 . Patterned layer 46 may comprise a residual layer 48 and/or features (e.g., protrusions 47 and recessions 49 ). Protrusions 47 may have a thickness t 1 and residual layer 48 may have a thickness t 2 .

Referring to FIGS. 2 and 3 , after solidification, patterned layer 46 may be subjected to further processing to clean patterned layer 46 and/or further separate protrusions 47 to form pillars 52 . For example, patterned layer 46 may be subjected to an oxygen plasma etching. Etching may remove at portion of residual layer 48 as illustrated in FIG. 3 .

Referring to FIGS. 3 and 4 , release of protrusions 47 from substrate 12 may form pillars 52 . For example, substrate 12 may be subjected a solution that may include, but is not limited to, water (e.g., de-ionized water), organic solvents (e.g., diluted HF), mild basic components, and/or the like. The solution may release protrusions 47 from substrate 12 to form pillars 52 having a thickness t 3 .

Etching of protrusions 47 subsequent to solidification of functional material 34 a may distort the configuration of protrusion 47 such that thickness t 2 of protrusion 47 is substantially different from thickness t 3 of the resulting pillar 52 . The amount of degradation of shape may limit the accuracy and/or precision of dimensionality when forming pillars 52 . Such distortion may be detrimental depending on the design consideration for the pillar 52 . For example, when pillars 52 are functional nanoparticles used as drug delivery devices, geo-targeting of destinations for pillar 52 within a body (e.g., human, animal, and/or the like) may be misdirected by alterations and/or distortion in shape.

Separation of template 18 from patterned layer 46 may also cause separation defects in pillars 52 . Although release layers (e.g., FOTS, Relmat, and the like) may be provided on substrate 12 , template 18 or both, the surface area of patterned layer 46 coupled to substrate 12 may be less than the surface area of patterned layer 46 coupled to template 18 prior to separation. Materiality of release layers and/or functional material 34 in combination with the dynamics of the surface area may provide separation defects in pillars 52 .

FIGS. 5A-5E illustrate schematic side views of formation of pillars 52 a minimizing degradation and separation distortion. By minimizing degradation and separation distortion, accuracy and/or precision of pillar formation may be controlled forming functional nanoparticles (i.e., pillars 52 a ).

Pillars 52 a are formed of functional material 34 a . Functional material 34 a includes material used in industries including, but not limited to, the bio-domain, solar cell industry, battery industry, and the like. Functional material 34 a may have use within the bio-domain, solar cell industry, battery industry, and other industries requiring a functional nano-particle. For example, functional material 34 a may include, but is not limited to, biomaterials (e.g., PEG), solar cell material (e.g., N-type material, P-type material), polymerizable materials, and/or the like.

FIGS. 5A-5E account for use of (1) properties of functional material 34 a ; and (2) imprint lithography materials (e.g., sacrificial material 34 a , BT20, release properties of template 18 a and 18 b , and/or the like) by using sacrificial material 34 b and imprint lithography techniques to form recesses recesses 49 a and 47 a that may be filled with functional material 34 a . Without accounting for both properties of functional material 34 a and properties of imprint lithography materials, degradation and separation distortion increases.

Generally, pillars 52 a may be formed using one or more imprint lithography processes. For example, sacrificial material 34 a may form protrusions 47 a and recessions 49 a using a first template 18 a through the processes and systems described in relation to FIGS. 1 and 2 . For example, sacrificial material 34 a (e.g., monomer mixture) may be solidified on a multi-layer substrate 70 to form patterned layer 46 a having a first set of protrusions 47 a and recessions 49 a . The pattern formed by protrusions 47 a and recessions 49 a may be used to form a second set of protrusions 47 b and recessions 49 b in removable layer 50 a . Functional material 34 a (e.g., biomaterial) may then be deposited in recessions 49 b in removable layer 50 a to form pillars 52 a . Alternatively, functional material 34 a may be deposited on removable layer 50 a and patterned by a second template 18 b using the processes and systems as described in relation to FIGS. 1 and 2 to form pillars 52 in removable layer 50 a . Pillars 52 a may then be released from multi-layer substrate 70 .

Referring to FIG. 5A , sacrificial material 34 b may be deposited on multi-layer substrate 70 . Sacrificial material 34 b may be formed of materials including, but not limited to, a polymerizable fluid comprising a monomer mixture as described in U.S. Pat. No. 7,157,036 and U.S. Patent Publication No. 2005/0187339, both of which are hereby incorporated by reference herein in their entirety.

Multi-layer substrate 70 may include a base layer 12 a , a removable layer 50 a , a protection layer 60 and an adhesion layer 62 . Base layer 12 a may be similar to substrate 12 described in relation to FIG. 1 . Base layer 12 a may be formed of materials including, but not limited to, fused-silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, hardened sapphire, and/or the like.

Removable layer 50 a may be positioned adjacent to base layer 12 a . Removable layer 50 a may be similar to removable layer 50 described in relation to FIG. 3 . For example, removable layer 50 a may release pillars 52 a when subjected a solution including, but not limited to, water (e.g., de-ionized water), organic solvents (e.g., diluted HF), mild basic components, and/or the like.

Protection layer 60 may be positioned adjacent to removable layer 50 a . Materiality of protection layer 60 may minimize damage and/or distortion of removable layer 50 a during imprinting and/or etching. For example, protection layer 60 may be formed of materials such as PECVD silicon oxide and the like.

Adhesion layer 62 (e.g., BT20) may be positioned adjacent to protection layer 60 . During processing of patterned layer 46 a , adhesion layer 62 may minimize separation distortion by adhering patterned layer 46 a to multi-layer substrate 70 during separation of template 18 from patterned layer 46 a.

Referring to FIG. 5B , features (e.g., 47 a and 49 a ) of patterned layer 46 a may be formed on multi-layer substrate 70 using first template 18 a as described in relation to the system 10 and processes described in FIGS. 1 and 2 . It should be noted that patterned layer 46 a may be formed by other nano-lithography techniques including, but not limited to, optical lithography, x-ray lithography, extreme ultraviolet lithography, scanning probe lithography, atomic force microscopic nanolithography, magneto lithography, and/or the like.

Referring to FIGS. 5C-5D , subsequent to formation of patterned layer 46 a on multi-layer substrate 70 , features (e.g., 47 a and 49 a ) may aid in forming features (e.g., 47 b and 49 b ) in removable layer 50 a . For example, features (e.g., 47 a and 49 b ) may be etched in multi-layer substrate 70 forming features (e.g., 47 b and 49 b ) in removable layer 50 a . Exemplary techniques include, but are not limited to, techniques described in U.S. Ser. Nos. 10/396,615 and 10/423,642, both of which are hereby incorporated by reference in their entirety.

In an optional step, portions of removable layer 50 a or entire removable layer 50 a may be exposed to UV ozone and/or O 2 plasma. Exposure to UV ozone and/or O 2 plasma may alter wetting characteristics of portions of removable layer 50 a for a given material. Alterations of wetting characteristics may increase depth and/or aspect ratio, and/or reduce filling time and filling defect.

Referring to FIGS. 5D and 5E , functional material 34 a (e.g., biomaterial) may be deposited on patterned removable layer 50 a . Functional material 34 a may be deposited using techniques such as drop dispense, spin-coating, dip coating, chemical vapor deposition (CVD), physical vapor deposition (PVD), thin film deposition, thick film deposition, and/or the like depending on design considerations. For example, by depositing functional material 34 a using drop dispense techniques, the amount of functional material 34 a deposited on removable layer 50 a may be conserved.

Functional material 34 a may fill in recessions 49 b in removable layer 50 a forming pillars 52 a . In one embodiment, portions of functional material 34 a deposited on removable layer 50 a may be removed to form pillars 52 a . Removal of portions of functional material 34 a provides a crown layer 66 (e.g., substantially planar layer) exposing pillars 52 a . Portions of functional material 34 a may be removed using techniques including, but not limited to, blanket etching, CMP polishing, and/or similar methods. For example, if functional material 34 a is formed of metal, crown layer 66 may be formed by metal etchants including, but not limited to, Cl 2 , BCl 3 , other Chlorine based etchants, and/or the like. It should be noted that the metal etchants are not limited to chlorine based etchants. For example, some metals, such as Tungsten, may be etched using Fluorine based etchants. Crown layer 66 may be formed by etching using an imprinting resist as a mask or by using a hardmask for pattern transfer. For example, crown layer 66 may be formed by using a hardmask formed of materials including, but not limited to, Cr, Silicon Oxide, Silicon Nitride, and/or the like. Alternatively, if functional material 34 a is formed of Silicon based material. Crown layer 66 may be formed by etching Silicon using common Silicon etchants including, but not limited to, CF 4 , CHF 3 , SF 6 , Cl 2 , HBr, other Fluorine, Chlorine and Bromine based etchants, and/or the like. Additionally, crown layer 66 may be etched using an imprint resist as a mask, a hardmask for pattern transfer, or the like. For example, crown layer 66 may be etched using a hardmask formed of materials including, but not limited to, Cr, Silicon Oxide, Silicon Nitride, and/or the like.

In another embodiment, a second template 18 b may be used to form pillars 52 a from functional material 34 a deposited on removable layer 50 a . Template 18 b may be positioned in superimposition with functional material 34 a on removable layer 50 a . Template 18 b may contact functional material 34 a and functional material 34 a may be solidified. Template 18 b may then be separated. It should be noted that template 18 b may optionally include coatings (e.g., FOTS) that aid in separation of template 18 b from solidified functional material 34 a as described herein.

Use of template 18 b may provide a substantially planar edge in solidified functional material 34 a . The surface area between solidified functional material 34 a and template 18 b may be selected such that it is less than the surface area between solidified functional material 34 a and removable layer 50 a . For example, template 18 b may be substantially planar. By reducing the surface area of solidified functional material 34 a and template 18 b as compared to the surface area of solidified functional material 34 a and removable layer 50 a , separation defects of solidified functional material 34 a may be reduced.

Referring to FIG. 5E , solidified functional material 34 a and/or removable layer 50 a may be removed to provide a crown layer 66 . For example, solidified functional material 34 a and/or removable layer 50 a may be removed by blanket etching, CMP polishing, and/or similar methods to provide crown layer 66 (e.g., planarized layer). Pillars 52 a may be positioned in recesses 49 b of removable layer 50 a.

Referring to FIGS. 5E and 5F , pillars 52 a may be released from removable layer 50 a . For example, removable layer 50 a may be subjected a solution that may include, but is not limited to, water (e.g., de-ionized water), organic solvents, inorganic acids (e.g., diluted HF), mild basic components, and/or the like, causing pillars 52 a to be released from multi-layer substrate 70 .

Dimensions provided by the crowning of solidified functional material 34 a and the dimensions provided by removable layer 50 a may define edges of pillars 52 a , and as such, the volume of pillars 52 a . By adjusting these dimensions, pillars 52 a may be constructed having varying shapes and sizes. For example, as illustrated in FIGS. 6A-6C , pillars 52 a may be constructed in shapes including, but not limited to, circular, triangular, rectangular, fanciful, and the like. By controlling the dimensions of removable layer 50 a and planarization of solidified functional material 34 a , shape, accuracy and precision of formation of pillars 52 a may also be controlled. Further, pillars 52 a may be formed using exemplary techniques described in U.S. Ser. No. 12/616,896, which is herein incorporated by references in its entirety.

FIG. 7 illustrates a flow chart of an exemplary method 100 for forming pillars 52 a using an imprint lithography system. Formation of pillars 52 a may include one or more lithography steps (e.g., nano-imprint lithography). In a step 102 , sacrificial material 34 b may be patterned on a multi-layer substrate 70 . For example, sacrificial material 34 b may be patterned using a first imprint lithography process using first template 18 a to provide patterned layer 46 a having features 47 a and 49 a . In a step 104 , features 47 a and 49 a may be used to form features 47 b and 49 b in removable layer 50 a . For example, features 47 a and 49 a may be etched into multi-layer substrate 70 to provide features 47 b and 49 b in removable layer 50 a.

In an optional step, removable layer 50 a may be exposed to UV ozone and/or O 2 plasma. In a step 106 , functional material 34 a (e.g., biomaterial) may be deposited on removable layer 50 a and solidified. In a step 108 , a portion of functional material 34 a may be patterned and/or removed to provide crown surface 66 exposing pillars 52 a . In a step 110 , pillars 52 a may be released from multi-layer substrate 70 .

FIGS. 8A-8E illustrate simplified side views of another embodiment for forming pillars 52 b . Generally, formation of pillars 52 b may comprise one or more imprint lithography steps

Referring to FIG. 8A , sacrificial material 34 b may be deposited on multi-layer substrate 70 b . Sacrificial material 34 b may be formed of materials including, but not limited to, a polymerizable fluid comprising a monomer mixture as described in U.S. Pat. No. 7,157,036 and U.S. Patent Publication No. 2005/0187339, both of which are hereby incorporated by reference herein in their entirety.

Multi-layer substrate 70 b may include a base layer 12 b (e.g., Si), a removable layer 50 b (e.g., SiO 2 ), and an adhesion layer 62 b (e.g., BT20). Base layer 12 b may be similar to substrate 12 described in relation to FIG. 1 . Base layer 12 b may be formed of materials including, but not limited to, fused-silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metal, hardened sapphire, and/or the like.

Removable layer 50 b may be positioned adjacent to base layer 12 b . Removable layer 50 b may be similar to removable layer 50 described in relation to FIG. 3 . For example, removable layer 50 b may release pillars 52 a when subjected a solution including, but not limited to, water (e.g., de-ionized water), organic solvents (e.g., HF), mild basic components, and/or the like.

Functional material 34 a (e.g., Si) may be positioned adjacent to removable layer 50 b . Adhesion layer 62 b (e.g., BT20) may be positioned adjacent to functional material 34 a . During processing of patterned layer 46 b (shown in FIG. 8B ), adhesion layer 62 b may minimize separation distortion by adhering patterned layer 46 b to multi-layer substrate 70 b during separation of template 18 from patterned layer 46 b . In one embodiment, functional material 34 a may be exposed to UV ozone and/or O 2 plasma. Exposure of functional material 34 a to UV ozone and/or O 2 plasma may render adhesion layer 62 b obsolete such that patterned layer 46 b may be formed directly on functional material 34 a without use of adhesion layer 62 b.

Referring to FIG. 8B , features (e.g., 47 c and 49 c ) of patterned layer 46 b may be formed on multi-layer substrate 70 b using template 18 as described in relation to the system 10 and processes described in FIGS. 1 and 2 . It should be noted that patterned layer 46 b may be formed by other nano-lithography techniques including, but not limited to, optical lithography, x-ray lithography, extreme ultraviolet lithography, scanning probe lithography, atomic force microscopic nanolithography, magneto lithography, and/or the like.

Referring to FIG. 8C , features (e.g., 47 c and 49 c ) may be etched in multi-layer substrate 70 b forming features (e.g., 47 d and 49 d ) in functional material 34 a . Exemplary techniques include, but are not limited to, techniques described in U.S. Ser. Nos. 10/396,615 and 10/423,642, both of which are hereby incorporated by reference in their entirety. For example, portions may be removed using techniques including, but not limited to, blanket etching, CMP polishing, and/or similar methods. For example, metal etchants may be used including, but not limited to, Cl 2 , BCl 3 , other Chlorine based etchants, and/or the like. It should be noted that the metal etchants are not limited to chlorine based etchants. For example, some metals, such as Tungsten, may be etched using Fluorine based etchants. Additionally, features (e.g., 47 d and 49 d ) may be formed by etching using an imprinting resist as a mask or by using a hardmask for pattern transfer. For example, features (e.g., 47 d and 49 d ) may be formed by using a hardmask formed of materials including, but not limited to, Cr, Silicon Oxide, Silicon Nitride, and/or the like. Alternatively, Silicon etchants may be used including, but not limited to, CF 4 , CHF 3 , SF 6 , Cl 2 , HBr, other Fluorine, Chlorine and Bromine based etchants, and/or the like. Additionally, features (e.g., 47 d and 49 d ) may be etched using an imprint resist as a mask, a hardmask for pattern transfer, or the like. For example, features (e.g., 47 d and 49 d ) may be etched using a hardmask formed of materials including, but not limited to, Cr, Silicon Oxide, Silicon Nitride, and/or the like.

Referring to FIGS. 8C-8E , sacrificial material 34 b and adhesion layer 62 b (if needed) may be stripped from functional material 34 a . Removable layer 50 b may be subjected to a chemical process (e.g., HF dip) such that functional material 34 a is removed from multi-layer substrate 70 forming one or more pillars 52 b (i.e., functional nanoparticles).