In the context of stamp and tip-based microscale and nanoscale patterning, various modalities of tips (hard and soft, sharp and rounded, and permeable and impermeable) have been demonstrated over the last fifteen years approximately. The modalities have been described by a variety of names including, for example, microcontact printing, soft lithography, dip-pen-nanolithography, scanning probe contact printing, microstamp patterning, and the like. See, for example, U.S. Pat. Nos. 6,635,311; 6,827,979; and 7,344,756.
In some cases, these tips have been intended to achieve the goal of large-area fabrication of microstructures and nanostructures, without the requirement of a conventional photolithographic mask. Recently, hard silicon tips with a soft backing have been proposed as a preferred means to accomplish this goal. See, for example, Shim, et al., “Hard tip, soft-spring lithography”, Nature, (469) pp 516-520, 2010 and also WO 2010/141,836 (Mirkin et. al., Northwestern Univ.). However, in the context of manufacturable and reliable tip-based patterning, silicon suffers as a tip material because, for example, its crystalline structure leads to fracture at relative low macroscale forces for the lithographic system—forces which can occur even with a soft backing in some embodiments, at least. Silicon tips also experience undesired wear over extended use and become duller. In addition, use of some tip materials of interest may cause fabrication problems. Also, some tips may fall off of their supporting structure.
A need exists for better tip systems and methods for making the same.
Embodiments described herein include articles, methods of making, and methods of using. Kits can also be provided.
For example, one embodiment provides an article comprising: at least one silicon nitride tip array, wherein the tip array is substantially free of cantilevers, at least one handle chip, wherein the tip array is bonded to the at least one handle chip.
Another embodiment provides a method comprising: preparing a silicon nitride tip array which is substantially free of cantilevers, preparing a handle wafer, and bonding the tip array to the handle wafer to form a bonded tip array.
Another embodiment provides an article comprising: at least one elastomeric tip array, wherein the tips of the tip array comprise a surface layer of refractory material.
Another embodiment provides a method comprising: providing at least one mold for a tip array comprising a plurality of mold regions for tips, coating the mold regions for tips with a refractory material, filling the mold regions for tips with an elastomeric material so that elastomeric material is in contact with the refractory material and forms at least one elastomeric tip array, wherein the tips of the tip array comprise a surface layer of refractory material upon removal from the mold.
Elastomeric material, such as a polysiloxane like PDMS (polydimethylsiloxane) also can be a precursor to an elastomeric material including a precursor to a polysiloxane or PDMS.
Another embodiment provides a method comprising: providing the silicon nitride tip arrays as described herein, disposing at least one patterning composition on the tip array, transferring the composition from the tip array to a substrate surface. For example, biological materials like proteins and nucleic acids can be patterned.
Another embodiment provides a method comprising: providing an elastomeric tip array comprising refractory material, as described herein, disposing at least one patterning composition on the tip array, transferring the composition from the tip array to a substrate surface. Again, for example, biological materials like proteins and nucleic acids can be patterned.
In addition, embodiments described herein include modalities of microscale and nanoscale patterning, using either: (A) silicon nitride membranes, with high-density arrays of intentionally either sharp or rounded tips silicon nitride, with a soft/compliant, for example, PDMS backing for contact force management; or, (B) high-density arrays of refractory metal tips (Cr, for example), again backed by, for example, PDMS, Covering an area of approximately 1 cm2, arrays built with these other modalities can be large enough to be effective for manufacturing. They can be hard enough to hold their shape reliably for many cycles. The close spacing of the tips can offer high speed patterning compared to a lower density array. In addition, the shape of the tips in these arrays can be controlled to a high degree, offering high-performance. The hard tips can resist deformation leading to higher fidelity of small printed spots. Compared to soft polymer tips, the spot size can be independent of tip force leading to much more uniform patterns across the printed area. Compared to tips on cantilevers, the tip density can be higher resulting in faster printing of dense patterns. When combined with a precision position system, a lithographic system based on these arrays can achieve at least some of and in some cases many of the requirements. For example, the tips can be relatively stable on their support structure and do not fall off.
All references cited herein are incorporated by reference in their entirety.
Priority U.S. Provisional Patent Application No. 61/487,212, filed May 17, 2011, is hereby incorporated by reference in its entirety including the claims and drawings and examples.
The following references can be used in the practice of the various embodiments described herein including patterning methods and compositions:
Transfer of inks from tips, which can be carried out with use of the tip arrays described herein, are described in technical literature including, for example, U.S. Pat. Nos. 6,635,311; 6,827,979; 7,102,655; 7,223,438; 7,273,636; 7,291,284; 7,326,380; 7,344,756; and 7,361,310. A wide variety of inks can be patterned including inorganic, organic, biological, low molecular weight, polymeric, particulate, and nanostructured materials.
Embodiments described herein can provide hard tip arrays. In one embodiment, hard silicon nitride tip arrays are prepared. In another embodiment, tip arrays comprising surfaces of refractory materials such as chromium can be prepared. In each case, the disadvantage of using silicon tips can be avoided. In particular, silicon tips can be substantially or totally excluded from the tip arrays.
In one embodiment, the tip array is totally free of cantilevers. In one embodiment, the tip array is totally free of silicon tips.
One embodiment provides an article comprising: at least one silicon nitride tip array, wherein the tip array is substantially free of cantilevers, at least one handle chip, wherein the tip array is bonded to the at least one handle chip. In one embodiment, the silicon nitride tip array comprises low stress silicon nitride.
In one embodiment, an article comprises a handle chip; and a silicon nitride membrane bonded to at least a portion of the handle chip. The silicon nitride membrane comprises an array of a plurality of silicon nitride tips extending directly from a surface of the silicon nitride membrane. The silicon nitride membrane can be a monolithic integrated structures wherein the tips are a part of the support structure. This can provide added stability so the tips do not fall off of the support structure.
Handle chips are known in the art. See, for example, US Patent Publication 2011/0268883.
The tips can be adapted to provide for disposing an ink composition on the tip and then transferring the ink from the tip to a substrate. In one embodiment, the tip array is a nanoscopic tip array. If desired, the tips can be surface coated.
Bonding methods are known in the art. In one embodiment, the tip array is anodically bonded to the at least one handle chip.
Materials for making a handle chip are known in the art. In one embodiment, the handle chip is a pyrex handle chip. The handle chip can also be called a support.
In one embodiment, the handle chip comprises at least one hole region. In one embodiment, furthermore, the handle chip comprises at least one hole region, and an elastomeric backing layer for the tip array disposed in the hole region. In one embodiment, for example, the handle chip comprises at least one hole region, and a polysiloxane backing layer for the tip array disposed in the hole region.
In one embodiment, the array of tips is characterized by a tip density of at least 100,000 per square cm. In one embodiment, the array of tips is characterized by a tip density of at least 250,000 per square cm. In one embodiment, the array of tips is characterized by a tip density of at least 1,000,000 per square cm.
In one embodiment, the tips of the tip array are characterized by a tip radius of about 250 nm or less. In one embodiment, the tips of the tip array are characterized by a tip radius of about 100 nm or less. In one embodiment, the tips of the tip array are characterized by a tip radius of about 50 nm or less. In one embodiment, the tips of the tip array are characterized by a tip radius of about 20 nm or less.
In one embodiment, the tip array has an area of at least one square cm. In another embodiment, the tip array has an area of less than one square cm. In one embodiment, the tip array is characterized by a tip spacing of about 1 micron to about 100 microns. In one embodiment, the tip array is characterized by a tip spacing of about 5 microns to about 50 microns. In one embodiment, the tip array is characterized by a tip spacing of about 10 microns to about 30 microns.
In one embodiment, the tip array has a thickness of about 100 nm to about one micron. In one embodiment, the tip array has a thickness of about 400 nm to about 800 nm. In one embodiment, the thickness is about 600 nm.
In one embodiment, the tip array is totally free of cantilevers. In one embodiment, the tip array is totally free of silicon tips.
One embodiment provides a method comprising: preparing a silicon nitride tip array which is substantially free of cantilevers, preparing a handle wafer, and bonding the tip array to the handle wafer to form an bonded tip array.
In one embodiment, the embodiment further comprises the step of dicing the bonded tip array.
In one embodiment, the bonding is an anodical bonding.
In one embodiment, the handle wafer is a pyrex handle wafer.
In one embodiment, the handle wafer comprises at least one hole region.
In one embodiment, the tip array is totally free of cantilevers.
In one embodiment, the tip array is totally free of silicon tips.
In one embodiment, the silicon nitride is low stress silicon nitride.
In one embodiment, the tip array is a square tip array.
In one embodiment, the embodiment further comprises the step of disposing an elastomeric backing in the hole region.
In one embodiment, a method comprises preparing a silicon nitride membrane comprising an array of a plurality of silicon nitride tips extending directly from a surface of the silicon nitride membrane; preparing a handle wafer; and bonding the silicon nitride membrane to at least a portion of the handle wafer to form an bonded tip array.
In one embodiment, the handle wafer comprises at least one hole region, a portion of the silicon nitride membrane extends across the hole region, and the method further comprises the step of disposing an elastomeric backing member in the hole region.
In one embodiment, the handle wafer comprises at least one hole region, a portion of the silicon nitride membrane extends across the hole region, the silicon nitride membrane comprises a plurality of perforations surrounding at least part of the portion of the silicon nitride membrane that extends across the hole region, and the method further comprises disposing an elastomeric backing member in the hole region, and pressing the elastomeric backing member against a back surface of the silicon nitride membrane such that the part of the silicon nitride membrane surrounded by the plurality of perforations separates from a remainder of the silicon nitride membrane and attaches to the elastomeric backing member. An example of this embodiment is illustrated in
The top image of
The tip arrays can be used for patterning and transfer of ink compositions from the tip to a surface. For example,
One embodiment, in addition, provides an article comprising: at least one elastomeric tip array, wherein the tips of the tip array comprise a surface layer of refractory material. Refractory materials and metals are known in the art. In one embodiment, the refractory material has a melting point higher than 2,000° C., or alternatively, higher than 4,000° C.
In one embodiment, an article comprises an elastomeric backing member; and an array of tips disposed on the elastomeric backing member. The tips of the array comprise a refractory material.
In one embodiment, the refractory material is a refractory metal.
In one embodiment, the refractory material is Nb, Mo, Ta, W, Ru, Ti, V, Cr, Zr, Ru, Rh, Hf, Os, or Ir.
In one embodiment, the refractory material is Nb, Mo, Ta, W, or Ru.
In one embodiment, the refractory material is Cr.
In one embodiment, the refractory material is W, diamond, a carbide, or a boride.
In one embodiment, the elastomeric tip array is a polysiloxane tip array.
In one embodiment, the tips of the elastomeric tip array are nanoscopic tips.
In one embodiment, the tips of the refractory material form non-continuous islands, with each island covering each elastomer tip.
In one embodiment, the tip array is a square array.
Another embodiment provides a method comprising: providing at least one mold for a tip array comprising a plurality of mold regions for tips, coating the mold regions for tips with a refractory material, filling the mold regions for tips with an elastomeric material so that elastomeric material is in contact with the refractory material and forms at least one elastomeric tip array, wherein the tips of the tip array comprise a surface layer of refractory material upon removal from the mold.
In one embodiment, the elastomer material is curable to form an elastomeric material.
In one embodiment, the elastomer material is a siloxane.
In one embodiment, the refractory material is a refractory metal.
In one embodiment, the refractory material is Nb, Mo, Ta, W, Ru, Ti, V, Cr, Zr, Ru, Rh, Hf, Os, or Ir.
In one embodiment, the refractory material is Nb, Mo, Ta, W, or Ru.
In one embodiment, the refractory material is Cr.
In one embodiment, the refractory material is W, diamond, a carbide, or a boride.
In one embodiment, the tips of the refractory material are patterned so as to form non-continuous islands, with each island covering each elastomer tip. In one embodiment, the refractory material is coated to a thickness of about 250 nm to about 750 nm, or about 300 nm to about 500 nm, or about 400 nm.
1. Grow 1500 Å silicon oxide
2. Pattern tip mold squares
3. Etch oxide
4. Etch Si tip molds in KOH
5. Grow 5000 Å sharpening oxide (optional)
6. Pattern and etch sharpening oxide (optional)
7. Deposit 600 nm low stress silicon nitride
8. Oxidize silicon nitride
9. Remove nitride from side opposite tip molds
10. Prep Pyrex wafer with through holes (using DRIE in AOE or HF etch or impact grinding or patterned powder blasting)
11. Clean Si and Pyrex wafers
12. Align and anodically bond nitride wafer to Pyrex wafer
13. Dice
14. Etch silicon mold wafer in TMAH or KOH
15. Rinse in DI water and dry
16. Add PDMS to backside of diaphragm (in the hole drilled into Pyrex) to add strength and stiffness to diaphragm (optional)
Procedure for HD tips, Hard tips/soft backing
1. Grow 1500 Å silicon oxide
2. Pattern tip mold squares
3. Etch oxide
4. Etch Si tip molds in KOH
5. Grow 5000 Å sharpening oxide (optional)
6. Pattern and etch sharpening oxide (optional)
7. Deposit antistiction film (optional)
8. Sputter 4000 Åtip material (Cr or other hard material eg Ir, Os, W, Diamond, Carbides, Borides, etc.)
9. Pattern to etch Cr into individual squares in and around each tip mold, but not interconnected
10. Strip resist
11. Dice into pieces
12. Clean
13. Put into mold and cast PDMS or other polymer
There are two options for PDMS steps (14a and 14b):
14a.
14b.
This application claims priority from U.S. Provisional Patent Application No. 61/487,212, filed May 17, 2011, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61487212 | May 2011 | US |