ES2356600T3 - METHODS THAT USE MICROSCOPE POINTS AS SWEEP PROBES. - Google Patents

Abstract

A nanolithography method comprising: providing a substrate; provide a microscope tip as a scanning probe; coat the tip with a pattern compound; and contacting the coated tip with the substrate so that the compound is applied to the substrate with the help of a means of transport, wherein the means of transport forms a meniscus that closes the gap between the tip and the substrate so that The pattern compound is transported to the substrate by capillary transport, in order to produce a desired pattern.

Description

Field of the Invention

This invention relates to microfabrication and nanofabrication methods. The invention also relates to methods for carrying out atomic force microscope imaging. 5

Background of the invention

Lithographic methods are the center of microfabrication today, nanotechnology and molecular electronics. These methods are often based on the modeling of a resistant film, followed by a chemical etching of the substrate.

The immersion pen technology, where the ink is transported on a sharp object to a paper substrate 10 by means of capillary forces, is approximately 4000 years old. Ewing, The Fountain Pen: A Collector’s Companion (Running Press Book Publishers, Philadelphia, 1997). The transport of molecules on a macro scale has been widely used throughout history.

By means of the present invention, these two disparate but related concepts have been merged, in relation to the scale and transport mechanism, to create "immersion pen" nanolithography (DPN). DPN uses a microscope tip as a scanning probe (SPM) (for example, an atomic force microscope (AFM) tip) as a "pen" or "pen," a solid-state substrate (for example, gold) as "paper", and molecules with a chemical affinity for the solid state substrate as "ink". Capillary transport of molecules from the tip to the solid substrate is used in DPN to directly write patterns that consist of a relatively small collection of molecules in submicroscopic dimensions. twenty

DPN is not the only lithographic method that allows one to directly transport molecules to substrates of interest in a positive printing mode. For example, microcontact printing, which uses an elastomeric seal, can deposit patterns of thiol molecules directly on gold substrates. Xia et al., Angew. Chem. Int. Ed. Engl., 37: 550 (1998); Kim et al., Nature, 376: 581 (1995); Xia et al.,, Science, 273: 347 (1996); Yan et al., J. Am. Chem. Soc., 120: 6179 (1998); Kumar et al., J. Am. Chem. Soc., 114: 9188 (1992). This method is a technique parallel to the DPN, allowing one to deposit a complete pattern or series of patterns on a substrate of interest in one stage. This is an advantage over a serial technique such as DPN, unless one is trying to selectively place different types of molecules at specific sites within a particular type of nanostructure. In this sense, DPN complements microcontact printing and many other existing micro and nanofabrication methods. 30

There are also a variety of negative printing techniques that are based on scanning probe type instruments, electron beams, or molecular feces for standard substrates using monolayers that assemble themselves and other organic materials as resistance layers (i.e., for remove material for further processing or adsorption stages). Bottomley, Anal. Chem., 70: 425R (1998); Nyffenegger et al., Chem. Rev., 97: 1195 (1997); Berggren et al., Science, 269: 1255 (1995); Sondag-Huethorst et al., Appl. Phys. Lett., 64: 285 35 (1994); Schoer et al., Langmuir, 13: 2323 (1997); Xu et al., Langmuir, 13: 127 (1997); Perkins et al., Appl. Phys. Lett., 68: 550 (1996); Carr et al., J. Vac. Sci. Technol. A, 15: 1446 (1997); Lercel et al., Appl. Phys. Lett., 68: 1504 (1996); Sugimura et al., J. Vac. Sci. Technol. A, 14: 1223 (1996); Komeda et al., J. Vac. Sci. Technol. A, 16: 1680 (1998); Muller et al., J. Vac. Sci. Technol. B, 13: 2846 (1995); Kim et al., Science, 257: 375 (1992). However, DPN can supply relatively small amounts of a molecular substance to a substrate in a nanolithographic form that does not have a strength, a seal, complicated processing methods, or sophisticated non-commercial instrumentation.

A problem that has plagued AFM since its invention is the narrow capillary gap formed between an AFM tip and the sample when an experiment is conducted in the air that condenses water from the environment and significantly influences imaging experiments, especially those that They try to achieve a resolution of nanometers or even angstroms. Xu et al., J. Phys. Chem. B, 102: 540 (1998); Binggeli et al., Appl. Phys. Lett, 65: 415 (1994); Fujihira et al., Chem. Lett., 499 (1996); Piner et al., Langmuir, 13: 6864 (1997). This has been shown to be a dynamic problem, and either water will be transported, depending on the relative humidity and the wetting properties of the substrate, from the substrate to the tip or vice versa. In the latter case, metastable patterns, on a nanometric length scale, of very thin layers of water 50 deposited from the tip of the AFM (Piner et al., Langmuir, 13: 6864 (1997)) could be formed. When transported molecules can anchor themselves to the substrate, stable surface structures are formed, resulting in a new type of nanolithography, DPN.

The present invention also overcomes the problems caused by the condensation of water that occurs when an AFM is carried out. In particular, it has been found that the resolution of an AFM is greatly improved when the AFM tip is coated with certain hydrophobic compounds before conducting an AFM.

Summary of the invention 5

As noted above and as claimed in the claims, the invention provides a lithography method referred to as "immersion pen" nanolithography, or DPN. DPN is a direct write nanolithography technique, whereby molecules are supplied to a substrate of interest in a positive printing mode. DPN uses a solid substrate as "paper" and a microscope tip as a scanning probe (SPM) (for example, an atomic force microscope tip (AFM)) as the "pen." The tip is coated with a pattern compound (the "ink"), and the coated tip is contacted with the substrate so that the pattern compound is applied to the substrate to produce a desired pattern. The molecules of the pattern compound are supplied from the tip to the substrate by means of capillary transport. DPN is useful in the manufacture of a variety of micro and nano scale devices. The invention also describes substrates designed by means of DPN and kits for carrying out DPN. fifteen

The invention further describes a method for carrying out imaging with an AFM in air. The method comprises coating an AFM tip with a hydrophobic compound. Then, imaging of the AFM in air is carried out using the coated tip. The hydrophobic compound is selected so as to improve the imaging performed using the AFM tip compared to the imaging with the AFM carried out using an uncoated AFM tip. Finally, the invention describes AFM tips coated with the hydrophobic compounds.

Brief description of the drawings

Figure 1. Schematic representation of a "dip pen" nanolithography (DPN). A water meniscus forms between the tip of the atomic force microscope (AFM) coated with 1-octadecanothiol (ODT) and the gold substrate (Au). The size of the meniscus, which is controlled by relative humidity, affects the transport speed of the ODT, the effective contact area of the tip substrate, and the resolution of the DPN.

Figure 2A Image of the lateral force of a 1 μm by 1 μm square of the ODT deposited on an Au substrate by the DPN. This pattern was generated by scanning the area of 1 μm2 with a scanning speed of 1 Hz for a period of 10 min with a relative humidity of 39%. Then the scan size was increased to 3 μm, and the scan rate increased to 4 Hz during image recording. The faster the 30-speed scanning, the transport of the ODT is avoided.

Figure 2B Image of the lateral force of the resolved lattice of an ODT self-assembly monolayer (SAM) deposited on an Au (111) / mica substrate by DPN. The image has been filtered with a fast fourier transform (FFT), and the FFT of the raw data is shown in the lower right insert. The monolayer was generated by scanning a 1000 Å square area of the Au (111) / mica substrate five times at a speed of 9Hz under a relative humidity of 39%.

Figure 2C Image of the lateral force of a 30 nm wide (3 μm long) line deposited on an Au / mica substrate by means of DPN. The line was generated by scanning the tip in a vertical line several times for five minutes with a scanning speed of 1 Hz.

Figure 2D. Image of the lateral force of a 100 nm line deposited on an Au substrate by means of 40 DPN. The method of depositing this line is analogous to that used to generate the image in Figure 2C, but the writing time was 1.5 minutes. Note that in all images (Figures 2A - 2D), the darkest regions correspond to areas of relatively less friction.

Figure 3A Image of the lateral force of an Au substrate after an AFM tip, which has been coated with ODT, has been in contact with the substrate for 2, 4, and 16 min (from left to right). The relative humidity remained constant at 45%, and the image was recorded with a scanning speed of 4Hz.

Figure 3B Image of the lateral force of 16 points of mercaptohexadecanoic acid (MHDA) on a substrate of Au. To generate the points, an MHDA coated AFM tip was maintained on the Au substrate for 10, 20, and 40 seconds (from left to right). The relative humidity was 35%. Note that the transport properties of MHDA and ODT differ substantially. fifty

Figure 3C Image of the lateral force of an array of points generated by means of DPN. Each point was generated by keeping a tip coated with ODT in contact with the surface for ~ 20 seconds. The writing and recording conditions were the same as in Figure 3A.

3D figure Image of the lateral force of a network based on molecules. Each line, 100 nm wide and 2 μm long, required 1.5 minutes for writing. 5

Figures 4A - B. The oscilloscope registers of the lateral force detector output before the AFM tip was coated with 1-dodecylamine (Figure 4A) and after the tip had been coated with 1-dodecylamine (Figure 4B ). The recording time extends to four scan lines. Since the signal was recorded both during the left and the right scan, the heights of the square waves are directly proportional to the friction. The zero of the Y axis has been changed for clarity. 10

Figures 5A - B. Images of the lateral force showing the water transported to a glass substrate (dark area) by an unmodified AFM tip (Figure 5A) and the result of the same experiment carried out with a tip coated with 1 -dodecylamine (Figure 5B). The height bars are in arbitrary units.

Figure 6A Image of the lateral force of the lattice resolved from a mica surface with a tip coated with 1-dodecylamine. The 2D fourier transform is in the insert. fifteen

Figure 6B Image of the lateral force of the resolved lattice of a self-assembled monolayer of 11-mercapto-1-undecanol. This image has been filtered by a fourier transform (FFT), and the FFT of the raw data is shown in the lower right insert. Scale bars are arbitrary.

Figure 6C Topographic image of water condensation on mica with a relative humidity of 30%. The height bar is 5 Å. twenty

Figure 6D. Image of the lateral force of condensation of water on mica with a relative humidity of 30% (same place as in Figure 6C).

Figure 7A - B. Topographic images of latex spheres, which show no changes before and after modifying the tip with 1-dodecylamine. The height bars are 0.1 μm. Figure 7A was etched with a clean tip, and Figure 7B was etched with the same tip coated with 1-dodecylamine. 25

Figures 8A - B. Images of a surface of Si3N4 coated with 1-dodecylamine molecules, showing a uniform coating. Figure 8A shows the topography of a surface of a Si3N4 wafer that has been coated with 1-dodecylamine molecules, which has similar characteristics as before coating. The height bar is 700 Å. Figure 8B shows the same area recorded in the lateral force mode, which does not show a distinctive variation of friction. 30

Figures 9A - C. Schematic diagrams with lateral force microscopy (LFM) images of molecular points at the nano scale showing the "essential factors" for molding at multiple nanometric scales by means of DPN. The scale bar is 100 nm. Figure 9A shows a first dot pattern of 1,16-mercaptohexadecanoic acid (MHA) of 15 nm in diameter on Au (111) that forms images by means of an LFM with the MHA coated tip used to make the points. Figure 9B shows a Second pattern 35 written by means of DPN using a coordinate for the second pattern calculated based on the LFM image of the first pattern shown in Figure 9A. Figure 9C shows the final pattern that contains both the first and second patterns. The time elapsed between the formation of the two drawings was 10 minutes.

Figures 10A - C. For these figures, the scale bar is 100 nm. Figure 10A shows a first pattern composed of 50 nm wide lines and alignment marks generated with MHA molecules by means of 40 DPN. Figure 10B shows a second pattern generated with ODT molecules. The coordinates of the second pattern were adjusted based on the LFM image of the MHA alignment pattern. The first line drawings were not represented to avoid possible contamination by the second molecules. Figure 10C shows the final results containing interdigitated lines 50 nm wide separated by 70 nm.

Figure 11A Letters drawn by means of DPN with MHA molecules on an amorphous gold surface. The bar 45 of the scale is 100 nm, and the width of the line is 15 nm.

Figure 11B Polygons designed by means of DPN with MHA molecules on an amorphous gold surface. ODT molecules around the polygons were overwritten. The scale bar is 1 μm, and the line width is 100 nm.

Detailed description of the currently preferred modalities

The DPN uses a microscope tip as a scanning probe (SPM). As used herein, the phrases "microscope tip as a scanning probe" and "SPM tip" refer to points used in atomic scale representation, including the atomic force microscope (AFM) tips, the tips of Near field scanning optical microscope (NSOM), scanning tunnel microscope tips (STM), and devices that have 5 similar properties. Many SPM tips are commercially available, and similar devices can be developed using the guidelines provided here.

More preferably, the tip of the SPM is a tip of the AFM. Any tip of the AFM can be used. Suitable AFM tips include those that are commercially available for example with Park Scientific, Digital Instruments and Molecular Imaging. 10

The tips of the NSOM are also preferred. These tips are hollow, and the pattern compounds accumulate in the gaps of the NSOM tips that serve as reservoirs of the pattern compound to produce a type of "fountain pen" for use in DPN. Suitable NSOM tips are available with Nanonics Ltd. and Topometrix.

The tip is preferably one that only fisisorba the pattern compound. As used herein, "fisisorption" means that the patterning compound adheres to the surface of the tip by a means that is not the result of a chemical reaction (ie, no chemisorption or covalent bonding) and can be removed from the surface of the tip with a suitable solvent. The fisisorption of the compounds for molding at the tip can be improved by coating the tip with an adhesion layer and by suitable choice of solvent (when one is used) for the pattern compound. The adhesion layer is a thin uniform layer 20 (<10 nm) of material deposited on the surface of the tip that does not significantly change its shape. It must also be strong enough to tolerate the operation of the AFM (a force of approximately 10 nN). Titanium and chromium form very thin uniform layers on the tips without significantly changing their shape, and are very suitable to be used to form the adhesion layer. The tips may be coated with an adhesive layer by means of vacuum deposition (see Holland, 25 Vacuum Deposition Of Thin Films (Wiley, New York, NY, 1956)), or any other method of forming thin metal films. By "suitable solvent" is meant a solvent that adheres well to the (wet) tips. The suitable solvent will vary depending on the pattern compound used, the type of tip used, whether or not the tip is coated with an adhesive layer, and the material used to form the adhesive layer. For example, acetonitrile adheres well to tips not coated with silicon nitride, making use of an adhesion layer that is unnecessary when acetonitrile is used as the solvent for a pattern compound. In contrast, water does not adhere to tips not coated with silicon nitride. Water does not adhere well to titanium-coated silicon nitride tips, and such coated tips can be used when water is used as a solvent. The fisisorption of aqueous solutions of molding compounds can also be improved by increasing the hydrophilicity of the tips (whether or not they are coated with an adhesive layer). For example, hydrophobicity can be increased by cleaning the tips (for example, with a piranha solution, by means of plasma cleaning, or by cleaning with UV ozone) or by means of etching plasma and oxygen. See Lo et al., Langmuir, 15, 6522-6526 (1999); James et al., Langmuir, 14, 741-744 (1998). Alternatively, a mixture of water and another solvent (for example, a 1: 3 ratio of water: acetonitrile) can be adhered to tips of non-coated silicon nitride, using an adhesion or treatment layer 40 to unnecessarily increase hydrophilicity . The appropriate solvent for a particular set of circumstances can be determined empirically using the guidance provided here.

The substrate can be of any shape and size. In particular, the substrate can be flat or curved. The substrates can be made of any material that can be modified by means of a pattern compound to form stable surface structures (see below). Substrates useful in the practice of the invention include metals (for example, gold, silver, aluminum, copper, platinum, and palladium), metal oxides (for example, oxides of Al, Ti, Fe, Ag, Zn, Zr, In, Sn and Cu), semiconductor materials (for example, Si, CdSe, CdS and CdS coated with ZnS), magnetic materials (for example, ferromagnetite), polymer-coated polymers or substrates, superconducting materials (YBa2Cu3O7-δ), Si , SiO2, glass, AgI, AgBr, HgI2, PbS, PbSe, ZnSe, ZnS, ZnTe, CdTe, InP, In2O3 / SnO2, In2S3, In2Se3, In2Te3, Cd3P2, Cd3As2, InAs, AlAs, GaP, and GaAs. Methods of making such substrates are well known in the art and include evaporation and crackling (metal films), growth of semiconductor crystals (eg, Si, Ge, GaAs), chemical vapor deposition (thin semiconductor films), growth epitaxial (thin crystalline semiconductor films), and thermal contraction (oriented polymers). See, for example, Alcock et al., Canadian Metallurgical Quarterly, 23, 309 (1984); Holland, Vacuum Deposition of Thin Films (Wiley, New York 1956); Grove, Philos. Trans. Faraday Soc., 87 (1852); Teal, IEEE 55 Trans. Electron Dev. ED-23, 621 (1976); Sell, Key Eng. Materials, 58, 169 (1991); Keller et al., Float-Zone Silicon (Marcel Dekker, New York, 1981); Sherman, Chemical Vapor Deposition For Microelectronics: Principles, Technology And Applications (Noyes, Park Ridges, NJ, 1987); Epitaxial Silicon Technology (Baliga, ed., Academic Press, Orlando, Florida, 1986); U.S. Patent No. 5,138,174; Hidber et al., Langmuir, 12, 5209-5215 (1996).

Commercially suitable substrates can also be obtained, for example, with Digital Instruments (gold), Molecular Imaging (gold), Park Scientific (gold), Electronic Materials, Inc. (semiconductor wafers), Silicon Quest, Inc. (semiconductor wafers) , MEMS Technology Applications Center, Inc. (semiconductor wafers), Crystal Specialties, Inc. (semiconductor wafers), Siltronix, Switzerland (silicon wafers), Aleene's, Buellton, CA (biaxially oriented polystyrene sheets), and Kama Corp., Hazelton, PA (thin oriented 5 polystyrene films).

The SPM tip is used to supply a pattern compound to a substrate of interest. Any pattern compound can be used, as long as it is capable of modifying the substrate to form stable surface structures. Stable surface structures are formed by chemisorption of the molecules of the compound for patterning on the substrate or by means of covalent bonding of the molecules of the compounds for pattern with the substrate.

Many suitable compounds are known in the art that can be used as the pattern compound, and the corresponding substrate (s) for the compound (s). For example:

to. Compounds of formula R1SH, R1SSR2, R1SR2, R1SO2H, (R1) 3P, R1NC, R1CN, (R1) 3N, R1COOH, or ArSH can be used to mold gold substrates; fifteen

b. Compounds of formula R1SH, (R1) 3N, or ArSH can be used to mold silver, copper, palladium and semiconductor substrates;

C. Compounds of formula R1NC, R1SH, R1SSR2, or R1SR2 can be used to mold platinum substrates;

d. Compounds of formula R1SH can be used to mold substrates of aluminum, TiO2, SiO2, GaAs and InP;

and. Organosilanes, including compounds of formula R1SiCl3, R1Si (OR2) 3, (R1COO) 2, R1CH = CH2, R1Li or R1MgX, 20 can be used to mold Si, SiO2 and glass substrates;

F. Compounds of formula R1COOH or R1CONHR2 can be used to mold metal oxide substrates;

g. Compounds of formula R1SH, R1NH2, ArNH2, pyrrole, or pyrrole derivatives wherein R1 is attached to one of the carbons of the pyrrole ring, can be used to mold high temperature superconducting cuprates;

h. Compounds of formula R1PO3H2 can be used to mold ZrO2 and In2O3 / SnO2 substrates; 25

i. Compounds of formula R1COOH can be used to mold substrates of aluminum, copper, silicon and platinum;

j. Compounds that are unsaturated, such as azoalkanes (R3NNR3) and isothiocyanates (R3NCS), can be used to mold silicon substrates;

k. Proteins and peptides can be used to mold, gold, silver, glass, silicon, and polystyrene.

In the formulas above: 30

R1 and R2 each have the formula X (CH2) n- and, if a compound is substituted with both R1 and R2, then R1 and R2 may be the same or different;

R3 has the formula CH3 (CH2) n-;

n is 0-30;

Ar is an aryl; 35

X is -CH3, -COOH, -CO2 (CH2) mCH3, -OH, -CH2OH, ethylene glycol, hexa (ethylene glycol), -O (CH2) mCH3, -NH2, -NH (CH2) mNH2, halogen, glucose , maltose, C60 fulerene, a nucleic acid (oligonucleotide, DNA, RNA, etc.), a protein (for example, an antibody or enzyme) or a ligand (for example, an antigen, enzyme substrate or receptor); Y

m is 0 - 30. 40

For a description of pattern compounds and their preparation and use, see Xia and Whitesides, Angew. Chem. Int. Ed, 37, 550-575 (1998) and references cited there; Bishop et al., Curr. Opinion Colloid & Interface Sci., 1, 127-136 (1996); Calvert, J. Vac. Sci. Technol. B, 11, 2155-2163 (1993); Ulman, Chem. Rev., 96: 1533 (1996) (alkanothioles on gold); Dubois et al., Annu. Rev. Phys. Chem., 43: 437 (1992) (alkanothioles on gold); Ulman, An Introduction to Ultrathin Organic Films: From Langmuir-Blodgett to Self-Assembly (Academic, Boston, 1991) 5 (alkanothioles on gold); Whitesides, Proceedings of the Robert A. Welch Foundation 39th Conference On Chemical Research Nanophase Chemistry, Houston, TX, pages 109-121 (1995) (gold-fixed alkanothioles); Mucic et al. Chem. Commun. 555-557 (1996) (describes a method of fixing AND thiol 3 'to gold surfaces); U.S. Patent No. 5,472,881 (oligonucleotide-phosphorothiolate binding to gold surface); Burwell, Chemical Technology, 4, 370-377 (1974) and Matteucci and Caruthers, J. Am. Chem. Soc., 103, 3185-3191 (1981) 10 (oligonucleotide-alkylsiloxane bonding to silica and glass surfaces) ; Record et al., Anal. Chem., 67, 735-743 (linkage of aminoalkylsiloxanes and for similar linkage of mercaptoalkylsiloxanes); Nuzzo et al., J. Am. Chem. Soc., 109, 2358 (1987) (disulfides on gold); Allara and Nuzzo, Langmuir, 1, 45 (1985) (carboxylic acids on aluminum); Allara and Tompkins, J. Colloid Interface Sci., 49, 410-421 (1974) (carboxylic acids on copper); Iler, The Chemistry Of Silica, Chapter 6, (Wiley 1979) (carboxylic acids on silica); Timmons and 15 Zisman, J. Phys. Chem., 69, 984-990 (1965) (carboxylic acids on platinum); Soriaga and Hubbard, J. Am. Chem. Soc., 104, 3937 (1982) (aromatic ring compounds on platinum); Hubbard, Acc. Chem. Res., 13, 177 (1980) (sulfolanes, sulfoxides and other solvents with functions on platinum); Hickman et al., J. Am. Chem. Soc., 111, 7271 (1989) (isonitriles on platinum); Maoz and Sagiv, Langmuir, 3, 1045 (1987) (silanes on silica); Maoz and Sagiv, Langmuir, 3, 1034 (1987) (silanes on silica); Wasserman et al., Langmuir, 5, 1074 (1989) (silanes on silica); 20 Eltekova and Eltekov, Langmuir, 3, 951 (1987) (aromatic carboxylic acids, aldehydes, alcohols and methoxy groups on titanium dioxide and silica); and Lec et al., J. Phys. Chem., 92, 2597 (1988) (rigid phosphates on metals); Lo et al., J. Am. Chem. Soc., 118, 11295-11296 (1996) (fixing pyrroles to superconductors); Chen et al., J. Am. Chem. Soc., 117, 6374-5 (1995) (fixation of amines and thiols to superconductors); Chen et al., Langmuir, 12, 2622-2624 (1996) (fixation of thiols to superconductors); McDevitt et al., U.S. Patent No. 5,846,909 (fixing 25 amines and thiols to superconductors); Xu et al., Langmuir, 14, 6505-6511 (1998) (fixation of amines to superconductors); Mirkin et al., Adv. Mater. (Weinheim, Ger.), 9, 167-173 (1997) (fixation of amines to superconductors); Hovis et al., J. Phys. Chem. B, 102, 6873-6879 (1998) (fixation of olefins and silicon dienes); Hovis et al., Surf. Sci., 402-440, 1-7 (1998) (fixation of olefins and dienes to silicon); Hovis et al., J. Phys. Chem. B, 101, 9581-9585 (1997) (fixation of olefins and dienes to silicon); Hamers et al., J. Phys. Chem. B, 101, 1489-1492 30 (1997) (fixation of olefins and silicon dienes); Hamers et al., U.S. Patent No. 5,908,692 (fixation of olefins and silicon dienes); Ellison et al., J. Phys. Chem. B, 103, 6243-6251 (1999) (fixation of isothiocyanates to silicon); Ellison et al., J. Phys. Chem. B, 102, 8510-8518 (1998) (fixation of azoalkanes to silicon); Ohno et al., Mol. Cryst Liq. Cryst Sci. Technol., Sect. A, 295, 487-490 (1997) (fixation of thiols to GaAs); Reuter et al., Mater. Res. Soc. Symp. Proc., 380, 119-24 (1995) (fixation of thiols to GaAs); Bain, Adv. Mater. (Weinheim, Fed. Repub. Ger.), 35 4, 591-4 (1992) (fixing thiols to GaAs); Sheen et al., J. Am. Chem. Soc., 114, 1514-15 (1992) (fixation of thiols to GaAs); Nakagawa et al., Jpn. J. Appl. Phys, Part 1, 30, 3 759-62 (1991) (fixation of thiols to GaAs); Lunt et al., J. Appl. Phys., 70, 7449-67 (1991) (fixation of thiols to GaAs); Lunt et al., J. Vac. Sci. Technol., B, 9, 2333-6 (1991) (fixation of thiols to GaAs); Yamamoto et al., Langmuir ACS ASAP, web version number Ia990467r (fixing thiols to InP); Gu et al., J. Phys. Chem. B, 102, 9015-9028 (1998) (thiol binding to InP); Menzel et al., Adv. Mater. 40 (Weinheim, Ger.), 11, 131-134 (1999) (fixation of disulfides to gold); Yonezawa et al., Chem. Mater., 11, 33-35 (1999) (fixation of disulfides to gold); Porter et al., Langmuir, 14, 7378-7386 (1998) (fixation of disulfides to gold); Son et al., J. Phys. Chem., 98, 8488-93 (1994) (fixation of nitriles to gold and silver); Steiner et al., Langmuir, 8, 2771-7 (1992) (fixation of nitriles to gold and copper); Solomun et al., J. Phys. Chem., 95, 10041-9 (1991) (fixation of nitriles to gold); Solomun et al., Ber. Bunsen-Ges. Phys. Chem., 95, 95-8 (1991) (fixation of nitriles to gold); Henderson et al., 45 Inorg. Chim. Acta, 242, 115-24 (1996) (fixation of isonitriles to gold); Huc et al., J. Phys. Chem. B, 103, 10489-10495 (1999) (fixation of isonitriles to gold); Hickman et al., Langmuir, 8, 3 57-9 (1992) (fixation of isonitriles to platinum); Steiner et al., Langmuir, 8, 90-4 (1992) (fixation of amines and phospins to gold and fixation of amines to copper); Mayya et al., J. Phys. Chem. B, 101, 9790-9793 (1997) (fixation of amines to gold and silver); Chen et al., Langmuir, 15, 1075-1082 (1999) (carboxylate fixation to gold); Tao, J. Am. Chem. Soc., 115, 4350-4358 (1993) (fixation of 50 carboxylates to copper and silver); Laibinis et al., J. Am. Chem. Soc., 114, 1990-5 (1992) (fixation of thiols to silver and copper); Laibinis et al., Langmuir, 7, 3167-73 (1991) (fixation of thiols to silver); Fenter et al., Langmuir, 7, 2013-16 (1991) (fixation of thiols to silver); Chang et al., Am. Chem. Soc., 116, 6792-805 (1994) (fixation of thiols to silver); Li et al., J. Phys. Chem., 98, 11751-5 (1994) (fixation of thiols to silver); Li et al., Report, 24 pp (1994) (fixation of thiols to silver); Tarlov et al., U.S. Patent No. 5,942,397 (fixation of thiols to silver and copper); Waldeck, et al., PCT application WO / 99/48682 (fixation of thiols to silver and copper); Gui et al., Langmuir, 7, 955-63 (1991) (fixation of thiols to silver); Walczak et al., J. Am. Chem. Soc., 113, 2370-8 (1991) (fixation of thiols to silver); Sangiorgi et al., Gazz. Chim. Ital., 111, 99-102 (1981) (fixation of amines to copper); Magallon et al., Book of Abstracts, 215th ACS National Meeting, Dallas, March 29 - April 2, 1998, COLL-048 (fixation of amines to copper); Patil et al., Langmuir, 14, 2707-2711 (1998) (fixation of amines to silver); Sastry et al., J. Phys. Chem. B, 101, 4954-4958 (1997) (fixation of 60 amines to silver); Bansal et al., J. Phys. Chem. B, 102, 4058-4060 (1998) (fixation of lithium alkyl to silicon); Bansal et al., J. Phys. Chem. B, 102, 1067-1070 (1998) (fixing lithium alkyl to silicon); Chidsey, Book of Abstracts, 214th ACS National Meeting, Las Vegas, NV, September 7 - 11, 1997, I & EC-027 (fixing lithium alkyl to silicon); Song, J. H., Thesis, University of California, San Diego (1998) (fixation of lithium alkyl to silicon dioxide); Meyer et al., J. Am. Chem. Soc., 110, 4914-18 (1988) (fixation of amines to semiconductors); Brazdil et al. J. Phys. Chem., 85, 65

1005-14 (1981) (fixation of amines to semiconductors); James et al., Langmuir, 14, 741-744 (1998) (fixation of proteins and peptides to glass); Bernard et al., Langmuir, 14, 2225-2299 (1998) (protein binding to glass, polystyrene, gold, silver and silicon wafers).

Other compounds known in the art in addition to those listed above, or that are developed or discovered using the guidelines set forth herein or, may also be used as compound 5 for patterning. Currently, alkanothiols and arylthiols are preferred over a variety of substrates and trichlorosilanes over SiO2 substrates (see Examples 1 and 2).

To implement the DPN, the SPM tip is coated with a patterning compound. This can be achieved in a variety of ways. For example, the tip can be coated by means of vapor deposition, by means of direct contact scanning, or by putting the tip in contact with a solution of the pattern compound.

The simplest method of coating the tips is by means of direct contact scanning. The direct contact scan coating is achieved by depositing a drop of a saturated solution of the patterning compound on a solid substrate (eg, glass or silicon nitride; available from Fisher Scientific or MEMS Technology Application Center). After drying, the patterning compound forms a microcrystalline phase on the substrate. To coat the pattern compound on the tip of the SPM, repeated scanning of the tip is made through this microcrystalline phase. Although this method is simple, it does not lead to the best loading of the tip, since it is difficult to control the amount of the pattern compound transferred from the substrate to the tip.

The tips can also be coated by means of vapor deposition. See Sherman, Chemical Vapor 20 Deposition For Microelectronics: Principles, Technology And Applications (Noyes, Park Ridges, NJ, 1987. In summary, a pattern compound (in pure, solid or liquid form, without solvent) is placed on a solid substrate (for example, glass or silicon nitride; obtained from Fisher Scientific or MEMS Technology Application Center), and the tip is placed near (within about 1 - 20 cm, depending on the chamber design) of the patterning compound. then the compound to a temperature at which it evaporates, thus coating the tip with the compound, for example, 1-octadecanothiol vapor can be deposited at 60 ° C. The coating by means of vapor deposition must be carried out in a closed chamber to avoid contamination of other areas.If the pattern compound is one that oxidizes in the air, the chamber must be a vacuum chamber or a nitrogen-filled chamber. tips by means of vapor deposition produces thin and uniform layers of pattern compounds on the tips and produces very reliable results in DPN. 30

Preferably, however, the SPM tip is coated by immersing it in a solution of the patterning compound. The solvent is not critical; All that is required is that the compound be in solution. However, the solvent is preferably one in which the pattern compound is more soluble. Also, the solution is preferably a saturated solution. In addition, the solvent is preferably one that adheres very well to the (wet) tip (coated or uncoated with an adhesive layer) (see above). The tip is maintained in contact with the standard compound solution for a time sufficient for the compound to coat the tip. Such times can be determined empirically. Generally, about 30 seconds to about 3 minutes is enough. Preferably, the tip is dipped into the solution several times, drying the tip each time between each dive. The number of times a tip needs to be immersed in a chosen solution can be determined empirically. Preferably, the tip 40 is blow dried with an inert gas (such as carbon tetrafluoride, 1,2-dichloro-1,1,2,2, -tetrafluoroethane, dichlorodifluoromethane, octafluorocyclobutane, trichlorofluoromethane, difluoroethane, nitrogen, argon or air dehumidified) that does not contain any particles (ie purified) on the tip. Generally, approximately 10 seconds of blowing with the gas at room temperature is sufficient to dry the tip. After immersion (single immersion or the last of multiple immersions), the wet tip 45 can be used to mold the substrate, or it can be dried (preferably as described above) before use. A dry tip provides a low, but stable, transport speed of the pattern compound for a long time (on the order of weeks), while a wet tip allows a high speed of transport of the pattern compound for a short time (approximately 2 - Three hours). A dry tip is preferred for compounds that have a good transport speed under dry conditions 50 (such as the compounds listed above where X = -CH3), while a wet tip is preferred for compounds that have a low transport speed under dry conditions (such as the compounds listed above where X = -COOH).

To carry out a DPN, the coated tip is contacted with a substrate. Both the pattern compound and a means of transport are necessary for a DPN since the pattern formation compound 55 is transported to the substrate by capillary transport (see Figure 1). The means of transport forms a meniscus that closes the gap between the tip and the substrate (see Figure 1). Consequently, the tip is "in contact" with the substrate when it is close enough so that this meniscus is formed. A

Suitable transport medium includes water, hydrocarbons (for example, hexane), and solvents in which the standards compounds are soluble (for example, the solvent used to coat the tip - see above). It is possible to write faster with the tip by means of the use of the transport means in which the pattern compound is more soluble.

Individual tips can be used to write a pattern using an AFM or similar device. As is known in the art, only some tips for STM and NSOM can be used in an AFM, and the tips for STM and NSOM that can be used in an AFM are commercially available. Two or more different compounds can be applied for pattern to the same substrate to form patterns (the same or different) of the different compounds by removing the first tip coated with a first pattern compound and replacing it with another tip coated with a different compound for 10 pattern. Alternatively, a variety of tips can be used in a single device to write a plurality of patterns (the same pattern or different patterns) on a substrate using the same or different pattern compounds. See, for example, U.S. Patent No. 5,666,190, which describes a device comprising multiple overhangs and tips for patterning on a substrate.

When two or more patterns and / or two or more compounds to form patterns (in the same or in different patterns) are applied to a single substrate, a positioning system (registration) is used to align the patterns and / or compounds for patterning with each other and / or in relation to selected alignment marks. For example, two or more alignment marks are applied, which can be represented by normal methods of representation with the AFM to the substrate by means of DPN or other lithographic technique (such as photolithography or electron beam lithography). Alignment marks can be simple shapes, such as a cross or a rectangle. A better resolution is obtained by making the alignment marks using DPN. If DPN is used, alignment marks are preferably made with pattern compounds that form strong covalent bonds with the substrate. The best compound to form alignment marks on gold substrates is 16-mercaptohexadecanoic acid. Alignment marks are represented by normal AFM methods (such as imaging with lateral force AFM, topography imaging of AFM 25 and imaging of AFM in non-contact mode), preferably using an SPM tip coated with a pattern compound for the elaboration of a desired pattern. For this reason, the patterning compounds used to make the alignment marks must not react with the other patterning compounds that are to be used to make the desired patterns and must not be destroyed by the subsequent formation of DPN patterns. Using the data for imaging, the appropriate 30 parameters (position and orientation) can be calculated using simple computer programs (for example, a Microsoft Excel spreadsheet), and the desired pattern (s) deposited on the substrate using the calculated parameters. Virtually an infinite number of patterns and / or compounds can be positioned for patterns using the alignment marks since the system is based on the calculation of positions and orientations in relation to the alignment marks. For best results, the SPM tip positioning system that is used must be stable and have no drift problems. An AFM positioning system that meets these standards is the 100 micron piezoelectric tube scanner available with Park Scientific. It provides stable positioning with nanometric scale resolution.

DPN can also be used in a nanograph format that has a series of micrometric scale wells (or other containers) that contain a plurality of different patterning compounds and rinse solutions adjacent to the substrate. The tip can be dipped into a well containing a pattern compound to coat the tip, and the coated tip is used to apply a pattern to the substrate. The tip is then rinsed by dipping it in a rinsing well or in a series of rinsing wells. The rinsed tip is immersed in another well to be coated with a second pattern compound and then used to apply a pattern to the substrate with the second pattern compound. The patterns are aligned as described in the previous paragraphs. The process of coating the tip with a pattern compound can be repeated, applying a pattern to the substrate with this pattern compound, and rinsing the tip, as many times as desired, and the entire process can be automated using appropriate software.

DPN can also be used to apply a second pattern compound to a first pattern compound that has already been applied to a substrate, either by means of DPN or another method. The second pattern compound is chosen in such a way that it reacts chemically or is stably combined (for example, by hybridization of two complementary strands of nucleic acid) with the first pattern compound. See, for example, Dubois and Nuzzo, Annu. Rev. Phys. Chem., 43, 437-63 (1992); Yan et al., Langmuir, 15, 1208-1214 (1999); Lahiri et al., Langmuir, 15, 2055-2060 (1999); and Huck et al., Langmuir, 15, 6862-6867 (1999). As with a DPN carried out directly on a substrate, both the second pattern compound and a transport medium are required, since the second pattern compound is transported to the first pattern compound by capillary transport (see above). ). A third, a fourth, etc., compounds for pattern formation can be applied to the first pattern compound, or to other pattern compounds, either on the substrate. In addition, additional compounds for pattern formation can be applied to form multiple layers of compounds for

pattern Each of these additional compounds for pattern formation may be the same or different from the other compounds for pattern formation, and each of the multiple layers may be the same or different from the other layers and may be composed of one or more Different compounds for pattern formation.

In addition, DPN can be used in combination with other lithographic techniques. For example, DPN 5 can be used in conjunction with microcontact printing and the other lithographic techniques discussed in the Background section above.

Different parameters affect the resolution of the DPN, and its final resolution is still unclear. First, the grain size of the substrate affects the resolution of the DPN as well as the texture of the paper controls the resolution of the conventional writing. As shown in Example 1 below, DPN has been used to make 30 nm lines of 10 width on a particular gold substrate. This size is the average grain diameter of the gold substrate, and represents the DPN resolution limit on this type of substrate. A better resolution is expected to be obtained using softer substrates (smaller grain size), such as silicon. Actually, using another softer gold substrate, the resolution was increased to 15 nm (see Example 4).

Second, chemisorption, covalent bonding and self-assembly, all act to limit the diffusion of molecules 15 after deposition. In contrast, compounds, such as water, that do not anchor to the substrate, form only metastable patterns of poor resolution (See Piner et al., Langmuir, 13: 6864 (1997)) and cannot be used.

Third, the time and contact of the substrate with the tip and, therefore, the scanning speed influence the resolution of the DPN. Higher scan speeds and a smaller number of traces produce narrower lines.

Fourth, the transport speed of the pattern compound from the tip to the substrate affects the resolution. For example, using water as a means of transport, it has been found that relative humidity affects the resolution of the lithographic process. For example, a line width of 30 nm (Figure 2C) requires 5 minutes to be generated in a relative humidity environment of 34%, while a 100 nm line (Figure 2D) 25 requires 1.5 minutes to be generated. in an environment of relative humidity 42%. It is known that the size of the water meniscus that joins the tip and the substrate depends on the relative humidity (Piner et al., Langmuir, 13: 6864 (1997)), and the size of the water meniscus affects the transport speed of the compound for the formation of patterns towards the substrate. In addition, when a wet tip is used, the water meniscus containing residual solvent is the means of transport, and the transport speed is also affected by the properties of the solvent.

Fifth, the sharpness of the tip also affects the resolution of the DPN. Therefore, it is expected to obtain a better resolution using sharper tips (for example, changing the tips frequently, cleaning the tips before coating them, and fixing sharp structures (such as carbon nanotubes) to the ends of the tips).

In summary, DPN is a simple but powerful method to transport molecules from the tips of the SPM to the 35 substrates with resolutions comparable to those achieved with much more expensive and sophisticated competitive lithographic methods, such as electron beam lithography. DPN is a useful tool for creating and making functional structures at micro and nano scales. For example, DPN can be used in the manufacture of microsensors, microreactors, combinatorial arrangements, micromechanical systems, microanalytical systems, biosurfaces, biomaterials, microelectronic, microoptic, and nanoelectronic devices. See, for example, Xia and Whitesides, Angew. Chem. Int. Ed, 37, 550-575 (1998). DPN must be especially useful for making nano-scale devices prepared in detail using more conventional lithographic methods. See Reed et al., Science, 278: 252 (1997); Feldheim et al., Chem. Soc. Rev., 27: 1 (1998).

The kits for carrying out DPN include one or more substrates and one or more SPM tips. The substrates and tips are those described above. The tips may be coated with a pattern compound or they may not be coated. If the tips are not coated, the kit may also include one or more containers, each with a pattern compound. The compounds for pattern are those described above. Any suitable container, such as a vial, tube or container, can be used. The kit may also include materials for the formation of a solid thin adhesive layer to improve the fisisorption of the patterning compounds as described above (such as a titanium or chrome container), materials useful for coating of the tips with the compounds for standardization (such as solvents for the compounds for standardization or solid substrates for direct contact scanning), and / or materials for carrying out lithography by methods other than the DPN (see Background section and references cited there). Finally, the kit may include other reagents and items useful for carrying out the DPN or any other lithographic method, such as reagents, beakers, vials, etc. 55

As noted above, when an AFM is operated in the air, water condenses between the tip and the surface and is then transported by capillarity while the tip is scanned across the surface. This full capillary, and the capillary force associated with it, significantly impede the operation of the AFM and substantially affect the imaging process.

Surprisingly, it has been found that AFM tips coated with certain hydrophobic compounds 5 exhibit a greater ability to form images of airborne substrates by means of AFM compared to uncoated tips. The reason for this is that hydrophobic molecules reduce the size of the water meniscus formed and effectively reduce friction. Consequently, the resolution of the AFM in the air is increased using a coated tip, compared to the use of an uncoated tip. Therefore, the tips coated with the hydrophobic molecules can be used as a general pretreatment for the tips of the AFM to carry out an AFM in the air.

Hydrophobic compounds useful for coating AFM tips to perform an AFM in the air must form a uniform thin coating on the surface of the tip, they must not covalently bond to the substrate on which the image is being formed or to the tip, they must bond to the tip more strongly than to the substrate, and they must remain solid at the operating temperature of the AFM. Suitable hydrophobic compounds 15 include those hydrophobic compounds described above for use as patterning compounds, as long as such hydrophobic patterning compounds are not used to coat AFM tips that are used to form the image of a corresponding substrate for the compound. for patterning or for coating AFM tips that are made of, or coated with, materials useful as the corresponding substrate for the patterning compound. Preferred hydrophobic compounds for most of the substrates are those having the formula R4NH2, wherein R4 is an alkyl of formula CH3 (CH2) not an aryl, and n is 0-30, preferably 10-20 (see discussion of the compounds for standardization above). Particularly preferred is 1-dodecylamine for the operating temperatures of the AFM below 74 ° F (approximately 23.3 ° C).

The AFM in the air that uses any AFM tip can be improved by coating the AFM tip with the 25 hydrophobic compounds described in the previous paragraph. Suitable AFM tips include those described above for use in DPN.

The tips of the AFM can be coated with hydrophobic compounds in a variety of ways. Suitable methods include those described above for coating the tips of the AFM with patterning compounds for use in DPN. Preferably, the AFM tip is coated with a hydrophobic compound 30 by simply dipping the tip into a solution of the compound for a time sufficient to coat the tip and then dry the coated tip with an inert gas, all as described above for coating. of a tip with a pattern compound.

After coating the tip, the AFM is carried out in the same manner as would be done if the tips were not coated. It has not been considered necessary to make changes in the AFM procedures. 35

Examples

Example 1: "Immersion Pen" Nanolithography With Alcanothiols on a Gold Substrate

The transfer of 1-octadecanothiol (ODT) to gold surfaces (Au) is a system that has been studied extensively. See Bain et al., Angew. Chem. Int. Ed. Engl., 28: 506 (1989); A. Ulman, An Introduction to Ultrathin Organic Films: From Langmuir-Blodgett to Self-Assembly (AcademicPress, Boston, 1991); Dubois et al., Annu. Rev. 40 Phys. Chem., 43: 437 (1992); Bishop et al., Curr. Opin. Coll. Interf. Sci., 1: 127 (1996); Alves et al., J. Am. Chem. Soc., 114: 1222 (1992). The Au that has this molecule moderately stable to the air immobilized on it can be easily differentiated from the unmodified Au by means of lateral force microscopy (LFM).

When an ODM-coated AFM tip is contacted with a sample surface, the ODT flows from the tip to the sample by capillary action, just like an immersion pen (Figure 1). This process has been studied using a conventional AFM tip on thin film substrates that were prepared by thermal evaporation of 300 Å of Polycrystalline Au over mica at room temperature. A Park Scientific Model CP AFM instrument was used to carry out all the experiments. The scanner was enclosed in a glass isolation chamber, and relative humidity was measured with a hygrometer. All humidity measurements have an absolute error of ± 5%. A silicon nitride tip (Park Scientific, Microlever A) 50 was coated with ODT by dipping the overhang in a saturated solution of ODT in acetonitrile for 1 minute. The cantilever was dried blown with compressed difluoroethane before use.

A simple demonstration of the DPN process involved scanning bitmap graphics of a tip that was prepared in this way through a section of 1 μm by 1 μm of an Au substrate (Figure 2A). An image

LFM of this section within a larger scanning area (3 μm by 3 μm) showed two areas of different contrast (Figure 2A). The inner dark area, or region of least lateral force, was a monolayer deposited with ODT, and the lighter outer area was discovered Au.

The formation of high quality self-assembled monolayers (SAM) occurred when the deposition process on Au (111) / mica was carried out, which was prepared by annealing the thin film substrates of Au at 5 300 ° C for 3 hours. Alves et al., J. Am. Chem. Soc., 114: 1222 (1992). In this case, it was possible to obtain a resolved lattice image of a SAM with ODT (Figure 2B). The hexagonal lattice parameter of 5.0 ± 0.2 Å compares well with the reported values for ODT SAMs over Au (111) (Id.) And shows that ODT, instead of some other adsorbate (water or acetonitrile), was transported from the tip to the substrate.

Although the experiments carried out on Au (111) / mica provided important information about the chemical identity of the species transported in these experiments, Au (111) / mica is a poor substrate for DPN. The deep valleys around the small facets of Au (111) make it difficult to draw long contiguous lines (micrometers) with nanometer widths.

Au's annealed substrates are relatively uneven (mean square root of roughness nm 2 nm), but 30 nm lines could be deposited using DPN (Figure 2C). This distance is the average diameter of Au 15 grains of thin film substrates and represents the DPN resolution limit on this type of substrate. The line based on 30 nm molecules prepared on this type of substrate was discontinuous and followed the grain edges of the Au. Smoother and more contiguous lines could be drawn by increasing the width of the line to 100 nm (Figure 2D) or presumably using a softer Au substrate. The width of the line depends on the scanning speed of the tip and the transport speed of the alkanothiol from the tip to the substrate 20 (relative humidity can change the transport speed). Faster sweeping speeds and fewer traces produce narrower lines.

DPN was also used to prepare molecular point features to demonstrate the diffusion properties of the "ink" (Figures 3A and 3B). The ODT coated tip (reference point = 1 nN) was contacted with the Au substrate for a set period of time. For example, ODT points of 0.66 μm, 25 0.88 μm, and 1.6 μm in diameter were generated keeping the tip in contact with the surface for 2, 4, and 16 minutes, respectively (left to right, Figure 3A). The uniform appearance of the points probably reflects a uniform flow of ODT in all directions from the tip to the surface. Opposite contrast images were obtained by deposition of points of a derivative of alkanothiol, 16-mercaptohexadecanoic acid in an analogous form (Figure 3B). This not only provides additional evidence that the molecules are transported from the tip to the surface but also demonstrates the molecular generality of DPN.

Arrangements and networks could be generated in addition to individual lines and points. An arrangement of twenty-five ODT points of 0.46 μm in diameter spaced 0.54 μm (Figure 3C) was generated by keeping an ODT-coated tip in contact with the surface (1 nM) for 20 seconds with a relative humidity of 45% No lateral movement to form each point. A network was generated consisting of eight lines that are cut 2 μm 35 length and 100 nm wide (Figure 3D) sweeping the tip coated with ODT on an Au surface with a scanning speed of 4 μm per second with a force 1 nN for 1.5 minutes to form each line.

Example 2: "Immersion Pen" Nanolithography

A large number of compounds and substrates have been successfully used in DPN. They are listed below in Table 1, together with the possible uses for combinations of compounds and substrates. 40

AFM (Park Scientific) tips were used: The tips were silicon tips, silicon nitride tips, and silicon nitride tips coated with a 10 nm layer of titanium to improve the fisisorption of the patterning compounds. Silicon nitride tips were coated with titanium by vacuum deposition as described in Holland, Vacuum Deposition Of Thin Films (Wiley, New York, NY, 1956). It should be noted that the coating of silicon nitride tips with titanium blunts the tips and decreases the resolution of the DPN. However, titanium coated tips are useful when water is used as a solvent for a standard compound. The DPN carried out with uncoated silicon nitride tips produced the best resolution (as low as approximately 10 nm).

Metal film substrates listed in Table 1 were prepared by vacuum deposition as described in Holland, Vacuum Deposition Of Thin Films (Wiley, New York, NY, 1956). 50 semiconductor substrates were obtained from Electronic Materials, Inc., Silicon Quest, Inc. MEMS Technology Applications Center, Inc., or Crystal Specialties, Inc.

The standards compounds listed in Table 1 of Aldrich Chemical Co. were obtained. The solvents listed in Table 1 of Fisher Scientific were obtained.

The AFM tips were coated with the patterning compounds as described in Example 1 (immersing in a solution of the patterning compound followed by drying with an inert gas), by vapor deposition or by direct contact scanning. The method of Example 1 produced the best results. Also, submerging and drying the tips multiple times the results were further improved.

The tips were coated by vapor deposition as described in Sherman, Chemical Vapor 5 Deposition For Microelectronics: Principles, Technology And Applications (Noyes, Park Ridges, NJ, 1987). In summary, a compound for patterning in pure form (solid or liquid, without solvent) was placed on a solid substrate (eg glass or silicon nitride; obtained from Fisher Scientific or MEMS Technology Application Center) in a closed chamber. For compounds that oxidize in air, a vacuum chamber or a chamber full of nitrogen was used. The AFM tip was positioned approximately 1 - 20 cm from the pattern compound, depending on the distance of the amount of material and the design of the chamber. The compound was then heated to a temperature at which it evaporates, thereby coating the tip with the compound. For example, 1-octadecanothiol vapor can be deposited at 60 ° C. The coating of the tips by means of vapor deposition produced uniform thin layers of patterning compounds on the tips and produced quite reliable results for DPN. fifteen

The tips were coated by direct contact scanning by deposition of a drop of a saturated solution of the patterning compound on a solid substrate (eg glass or silicon nitride; obtained from Fisher Scientific or MEMS Technology Application Center). After drying, the patterning compound formed a microcrystalline phase on the substrate. To load the pattern compound onto the AFM tip, the tip (scan speed ~ 5Hz) was repeatedly scanned through this microcrystalline phase. Although this method was simple, it did not lead to the best loading of the tip, since it was difficult to control the amount of pattern compound transferred from the substrate to the tip.

A DPN was carried out as described in Example 1 using an AFM Park Scientific, Model CP, scan rate 5-10 Hz. The scan times were in the range of 10 seconds to 5 minutes. Prepared patterns include grids, points, letters, and rectangles. The width of the grid lines and the lines that formed the letters were in the range of 15 nm to 250 nm, and the diameters of the individual points in the range of 12 nm to 5 micrometers.

Table 1

 Substratum

 Compound for Pattern Formation / Solvent (s) Potential Applications Comments and References

 Au

 n-octadecanothiol / acetonitrile, ethanol Basic research Study of intermolecular forces. Langmuir, 10, 3315 (1994)

 Engraving resistance for microfabrication

 Recorder: KCN / O2 (pH-14). J. Vac. Sci. Tech. B, 13, 1139 (1995)

 dodecanothiol / acetonitrile, ethanol

 Molecular electronics Thin coating for insulation on gold pieces on a nanometric scale. Superlattices and Microstructures 18, 275 (1995)

 n-hexadecanothiol / acetonitrile, ethanol

 Engraving resistance for microfabrication Recorder: KCN / O2 (pH-14). Langmuir, 15, 300 (1999)

 n-docosanothiol / acetonitrile, ethanol

 Engraving resistance for microfabrication Recorder: KCN / O2 (pH-14). J. Vac. Sci. Technol. B, 13, 2846 (1995)

 11-mercapto-1-undecanol / acetonitrile, ethanol

 Functionalization of the surface Capture of SiO2 groups

 16-mercapto-1-hexadecanoic acid / acetonitrile, ethanol

 Basic research Study of intermolecular forces. Langmuir 14, 1508 (1998)

 Surface Functionalization

 Capture of clusters of SiO2, SnO2. J. Am. Chem. Soc., 114, 5221 (1992)

 octanedithiol / acetonitrile, ethanol

 Basic research Study of intermolecular forces. Jpn J. Appl. Phys. 37, L299 (1998)

 hexanedithiol / acetonitrile, ethanol

 Functionalization of the surface Capture of gold clusters. J. Am. Chem. Soc., 114, 5221 (1992)

 propanoditol / acetonitrile, ethanol

 Basic research Study of intermolecular forces. J. Am. Chem. Soc., 114, 5221 (1992)

 α, α’-p-xyldithiol / acetonitrile, ethanol

 Functionalization of the surface Capture of gold clusters. Science, 272, 323 (1996)

 Molecular electronics

 Making connections on a nanometric scale. Science, 272, 1323 (1996)

 4,4’-biphenyldithiol / acetonitrile, ethanol

 Functionalization of the surface Capture of gold and CdS clusters. Inorganica Chemica Acta 242, 115 (1996)

 terphenyldithiol / acetonitrile, ethanol

 Functionalization of the surface Capture of gold and CdS clusters. Inorganica Chemica Acta 242, 115 (1996)

 terphenyldiisocyanide / acetonitrile, methylene chloride

 Functionalization of the surface Capture of gold and CdS clusters. Inorganica Chemica Acta 242, 115 (1996)

 Molecular electronics Conductive coating on gold clusters on a nanometric scale. Superlattices and Microstructures, 18, 275 (1995)

 DNA / water: acetonitrile (1: 3)

 Gene detection DNA probe to detect biological. J. Am. Chem. Soc. 119, 8916 (1997)

 Ag

 n-hexadecanothiol / acetonitrile, ethanol Engraving resistance for microfabrication Engraver: Fe (NO3) 3 (pH ~ 6). Microelectron Eng., 32, 255 (1996)

 To the

 2-mercaptoacetic acid / acetonitrile, ethanol Surface functionalization Capture of CdS clusters. J. Am. Chem. Soc., 114, 5221 (1992)

 GaAs-100

 n-octadecanothiol / acetonitrile, ethanol Basic research Formation of self-assembled monolayers

 Engraving resistance for microfabrication

 HCl / HNO3 (pH ~ 1). J. Vac. Sci. Technol. B, 11, 2823 (1993)

 TiO2

 n-octadecanothiol / acetonitrile, ethanol Engraving resistance for microfabrication

 SiO2

 16-mercapto-1-hexadecanoic acid / acetonitrile, octadecyltrichlorosilane ethanol Surface functionalization Capture of gold and CdS clusters

 ne (OTS, CH3 (CH2) 17SiCl3) 1.2 nm thick SAM / hexane

 Engraving resistance for microfabrication Recorder: HF / NH4F (pH ~ 2). Appl. Phys. Lett., 70, 1593 (1997)

 APTS, 3- (2-Aminoethylamino) propyltrimethoxysilane / water

 Functionalization of the surface Capture of gold clusters on a nanometric scale. Appl. Phys. Lett. 70, 2759 (1997)

Example 3: Atomic Force Microscope With Coated Tips

As noted above, when an AFM is operated in the air, water condenses between the tip and the surface and is then transported by capillarity while the tip is scanned through the surface. Piner et al., Langmuir 13, 6864-6868 (1997). Notably, this full capillary, and the capillary force associated with it, significantly impede the operation of the AFM, especially when operating in lateral force mode. Noy et al., J. Am. Chem. Soc. 117, 7943-7951 (1995); Wilbur et al., Langmuir 11, 825-831 (1995). In air, the capillary force can be 10 times greater than the chemical bond strength between the tip and the sample. Therefore, the capillary force can substantially affect the structure of ours and the imaging process. To make matters worse, the magnitude of this effect will depend on many variables, including the relative hydrophobicities of the tip and the sample, the relative humidity, and the scanning speed. For these reasons, many groups have chosen to work in solution cells where the effect can be more uniform and reproducible. Frisbie et al., Science 265, 2071-2074 (1994); Noy et al., Langmuir 14, 1508-1511 (1998). This, however, imposes major restrictions on the use of an AFM, and the solvent can affect the structure of the material being converted into images. Vezenov et al., J. Am. Chem. Soc. 119, 2006-2015 (1997). Therefore, other methods that allow the formation of images in the air with the reduced or eliminated capillary effect would be desirable.

This example describes one such method. The method involves the modification of the AFM tips of silicon nitride with a fisisorbide layer of 1-dodecylamine. Such tips improve the ability to make LFM in the air by substantially decreasing the capillary force and providing greater resolution, especially with soft materials. twenty

All data presented in this example were obtained with a Park Scientific Model CP AFM with a combined AFM / LFM head. The cantilevers (model no. MLCT-AUNM) were obtained from Park Scientific and had the following specifications: gold coated micro lever, silicon nitride tip, cantilever A, spring constant = 0.05 N / m. The AFM was mounted in a Park chamber isolated from vibration that had been modified with a dry nitrogen purge line. Also, an electronic hygrometer, placed inside the chamber, was used for 25 humidity measurements (± 5% with a range of 12 ~ 100%). Muscovite green mica was obtained from Ted Pella, Inc.

they obtained the soda lime glass microscope slides from Fisher. Polystyrene spheres with diameters of 0.23 ± 0.002 μm were purchased from Polysciences, and Si3N4 on silicon was obtained from MCNC MEMS Technology Applications Center. 1-Dodecylamine (99 +%) was purchased from Aldrich Chemical Inc., and used without further purification. Acetonitrile (grade A.C.S.) was purchased from Fisher Scientific Instruments, Inc.

Two methods to coat an AFM tip with 1-dodecylamine were explored. The first method involved the saturation of ethanol or acetonitrile with 1-dodecylamine and then the deposition of a small drop of this solution on a glass substrate. After drying, 1-dodecylamine formed a microcrystalline phase on the glass substrate. To load the 1-dodecylamine on the AFM tip, the tip (scanning speed ~ 5 Hz) was repeatedly scanned through this microcrystalline phase. Although this method was simple, it did not lead to the best loading of the tip, since it was difficult to control the amount of 1-dodecylamine transferred from the substrate to the tip. 10

A better method was to transfer dodecylamine directly from the solution to the AFM cantilever. This method involved soaking the overhang of the AFM and the tip in acetonitrile for several minutes in order to remove any residual contaminants on the tip. This tip was then soaked in a solution of 1-dodecylamine / acetonitrile ~ 5 mM for approximately 30 seconds. Then, the tip was blow dried with compressed freon. Repeating this procedure several times typically produced the best results. The 15 1-dodecylamine is fisisorbide, instead of chemisorbide, on the tips of silicon nitride. Actually, you can rinse the tip dodecylamine with acetonitrile as is the case with bulk silicon nitride. Benoit et al. Microbeam and Nanoheam Analysis; Springer Verlag, (1996). Modifying the tip in this way significantly reduces the capillary effect due to condensation of atmospheric water as evidenced by several experiments described below. twenty

First, an oscilloscope, directly connected to the lateral force detector of the AFM, was used to record the lateral force output as a function of time. In this experiment, the frictional force changed direction when the tip was scanned from left to right, compared to right to left. Therefore, the LFM detector output changed polarity each time the scanning direction of the tip changed. If one or more sweeps of the AFM bitmap graph were recorded, the detector output was in the form of a square wave, 25 Figures 4A-B. The height of the square wave is directly proportional to the slip fraction of the tip on the sample and, therefore, friction forces can be compared between an unmodified tip and a glass substrate and between a modified tip and a glass substrate simply by comparing the height of the square waves under ambient conditions and almost identical sweep. The friction force of the sample / tip was at least a factor of at least three for the modified tip than for the unmodified tip. This experiment was repeated on a mica substrate, and a similar reduction in friction was observed. In general, the friction reductions measured in this way and under these conditions were in the range of a factor of three to more than an often smaller factor for the modified tips, depending on the substrate and environmental conditions, such as humidity relative.

Although this experiment showed that treatment with 1-dodecylamine from an AFM tip decreased friction, 35 did not prove that water and capillary force were the key factors. In another experiment, the effects of the 1-dodecylamine coating on water capillarity transport were examined. The details of water transport that involve unmodified tips have been discussed elsewhere. Piner et al., Langmuir 13, 6864-6868 (1997). When an AFM tip was scanned through a sample, it transported water to the sample through capillary action, Figure 5A. After scanning an area of 4 μm x 5 μm of a glass substrate to soda 40 for several minutes, adjacent layers of water were deposited on the substrate and images were formed by means of the LFM increasing the size of the scan. The areas of least friction, where water had been deposited, appeared darker than the unpainted areas, Figure 5A. The same experiment performed with a tip coated with 1-dodecylamine showed no evidence of substantial water transport, Figure 5B. In fact, only random variations of friction were observed. Four. Five

Although these experiments showed that friction could be reduced and that water transport from the tip to the substrate could be inhibited by capillary action by coating the tip with 1-dodecylamine, they did not provide information about the resolution power of the modified tip . Mica is an excellent substrate to evaluate this problem and, in fact, the resolved images of the lattice could be routinely obtained with the modified tips, demonstrating that this modification procedure reduced the frictional force without dulling the tip, Figure 6A. It was possible to determine if the portion of the tip that was involved in imaging was discovered or had a layer of 1-dodecylamine on it. In reality, it is likely that the 1-dodecylamine layer had been mechanically removed from this part of the tip exposing the discovered Si3N4. In any case, the rest of the tip must have had a hydrophobic layer of dodecylamine on it, since the entry of water by capillarity around the point of contact was inhibited, thus reducing the capillary effect (see above).

Although the ability for atomic scale imaging of the AFM was not adversely affected by the 1-dodecylamine coating on the tip, the previous experiment did not provide useful information on the

suitability of the tip to obtain morphology data on a larger scale. In order to obtain such information, images of a sample of monodisperse latex spheres of 0.23 μm in diameter were formed with both modified and unmodified tips. Since the topography recorded by an AFM is a gyrus of the shape of the tip and the shape of the sample, any change in the shape of the tip will be reflected in a change in the topography reflected from the latex spheres. No detectable difference was found in the 5 images taken with modified and unmodified tips, respectively, Figures 7A-B. This shows that the shape of the tip did not change significantly as it would be if a metal coating had evaporated on it. In addition, this suggests that the 1-dodecylamine coating was fairly uniform on the surface of the tip and was sharp enough such that it did not adversely affect the formation of the image at atomic scale. 10

A significant problem is related to the performance of the modified tips in the imaging of soft materials. Typically, it is difficult to determine if a chemically modified tip exhibits improved performance compared to a bare tip. This is because a chemical modification is often an irreversible process that sometimes requires the deposition of an intermediate layer. However, since the modification process reported here was based on fisisorbed layers of 1-dodecylamine, it was possible to compare the performance of a tip before modification, after modification, and after the tip had been washed and 1-dodecylamine would have been removed. Qualitatively, the 1-dodecylamine modified tips always provided significant improvements in the formation of monolayers based on alkanothiols and organic crystals deposited on a variety of substrates. For example, a resolved image of a lattice of a self-assembled hydrophilic monolayer of 11-mercapto-1-undecanol was routinely obtained on an Au surface (111) with a modified tip, Figure 6B. The lattice could not be resolved with the same unmodified tip of the AFM. On this surface, the coated tip showed a reduction in friction of at least a factor of five by means of square wave analysis (see above). It should be noted that, the OH-terminated SAM is hydrophilic and, therefore, has a strong capillary attraction towards a clean tip. The reduction of the capillary force by the modified tip allows the formation of the lattice image. 25

A second example of improved resolution involved imaging surfaces free of stagnant liquid, such as water condensed on mica. It is well known that with humidities between 30 and 40 percent, water has two distinct phases on mica. Hu et al., Science 268, 267-269 (1995). In previous work of this group, a scanning polarization force microscope in non-contact mode (SPFM) was used for imaging these phases. It was found that when a probe tip comes into contact with 30 mica, strong capillary forces caused the water to moisturize the tip and strongly disturb the condensate of water on the mica. To reduce the capillarity effect so that two phases of water could be captured in image, the tip was kept away ~ 20 nm from the surface. Due to this restriction, the image of such phases cannot be captured with a scanning probe technique in contact mode. Figures 6C-D show images of the two phases of water on mica recorded with a humidity percentage of 30 percent with a tip modified with 1-dodecylamine in contact mode. The heights of the features (Figure 6C) corresponded to the friction map (Figure 6D), with higher features having less friction. The quality of the modified tip, which is believed to correlate with the uniformity of the 1-dodecylamine layer on the tip, was important. Only well-modified tips made it possible to capture images of the two water phases, while those less well modified resulted in images of poorer quality. Actually, this was a test so sensitive that it could be used as a diagnostic indicator of the quality of the tips modified with 1-dodecylamine before proceeding with other samples.

In conclusion, this example describes a very simple, but extremely useful, method for making hydrophobic Si3N4 AFM tips. This modification procedure decreases the capillary force and improves the performance of the AFM in the air. Significantly, it does not adversely affect the shape of the tip of the AFM and allows to obtain resolved images of lattices of hydrophilic substrates, including soft materials such as SAMs and even free of standing water, on a solid support. The development of methodology that allows obtaining such information in the air is extremely important since, although solution cells can reduce the effect of capillary force, soft material substrates can be significantly affected by the solvent. Vezenov et al., J. Am. Soc. 119, 2006-2015 (1997). Finally, although it might be possible to make a more hydrophobic AFM tip by first coating it with a metal layer and then forming a derivative of the metal layer with a hydrophobic chemoisorbed organic monolayer, it is difficult to do so without concomitantly dulling the AFM tip.

Example 4: Multi-Component "Immersion Pen" Nanolithography

The inability to align lithographically generated nano-scale patterns composed of chemically distinct materials is a problem that limits the progress of both molecule-based and solid-state nanoelectronics. Reed et al., Science 278, 252 (1997); Feldheim, et al., Chem. Soc. Rev. 27, 1 (1998). The fundamental reasons for this problem are that many lithographic processes: 1) are based on masking or stamping procedures, 2) use resistance layers, 3) are subject to significant drift problems

thermal, and 4) are based on the alignment of patterns based on optics. Campbell, The Science and Engineering of Microelectronic Fabrication (Oxford Press); Chou et al., Appl. Phys. Lett. 67, 3114 (1995); Wang et al., Appl. Phys. Lett. 70, 1593 (1997); Jackman et al., Science 269, 664 (1995); Kim et al., Nature 376, 581 (1995); Schoer et al., Langmuir 13, 2323 (1997); Whelan et al., Appl. Phys Lett. 69, 4245 (1996); Younkin et al., Appl. Phys. Lett. 71, 1261 (1997); Bottomley, Anal. Chem. 70, 425R. (1998); Nyffenegger and Penner, Chem. Rev. 97, 1195 (1997); Berggren, et 5 al., Science 269, 1255 (1995); Sondag-Huethorst et al., Appl. Phys. Lett. 64, 285 (1994); Schoer and Crooks, Langmuir 13, 2323 (1997); Xu and Liu, Langmuir 13, 127 (1997); Perkins, et al., Appl. Phys. Lett. 68, 550 (1996); Carr, et al., J. Vac. Sci. Technol. A 15, 1446 (1997); Sugimura et al., J. Vac. Sci. Techno /. A 14, 1223 (1996); Komeda et al., J. Vac. Sci. Technol. A 16, 1680 (1998); Muller et al., J. Vac. Sci. Technol. B 13, 2846 (1995); and Kim and M. Lieber, Science 257, 375 (1992). 10

With respect to the characteristic of the size, the optical methods based on resistance allow stamping in reproducible form many materials, soft or solid state, in the line width> 100 nm and regime of spatial resolution, while the methods of lithography by beam of electrons allow stamping on a scale of 10-200 nm. In the case of soft lithography, both electron beam lithography and optical methods are based on resistance layers and the filling of the areas recorded with the component molecules. This indirect approach to pattern formation compromises the chemical purity of the structures generated and has limitations on the types of materials that can be molded. In addition, when more than one material is lithographically molded, the optical base pattern alignment methods used in these techniques limit their spatial resolution to approximately 100 nm.

This example describes the generation of multicomponent nanostructures by means of DPN, and demonstrates that patterns of two different soft materials can be generated by means of this technique with almost perfect alignment and 10 nm spatial resolution in an arbitrary manner. These results must open many paths for those interested in molecular-based electronics to generate, align, and connect soft structures with each other and conventional micro-electronic circuitry macroscopically addressable.

Unless otherwise specified, DPN was performed on atomically flat substrates of Au (111) 25 using a conventional instrument (Park Scientific CP model AFM) and overhangs (Park Scientific Microlever A). Atomically flat substrates of Au (111) were prepared by first heating a piece of mica at 120 ° C under vacuum for 12 hours to remove a possible water content and then thermally evaporating 30 nm of gold on the mica surface at 220 ° C at empty. Using atomically flat substrates of Au (111), 15 nm wide lines can be deposited. To prevent problems of piezo tube drift, a 100 30 μm scanner with closed loop scanning control (Park Scientific) was used for all experiments. The pattern compound was coated on the tips as described in Example 1 (immersing them in a solution) or by vapor deposition (for low melting liquids and solids). Vapor deposition was carried out by suspending the silicon nitride overhang in a 100 mL reaction vessel 1 cm above the pattern compound (ODT). The system was closed, heated at 60 ° C for 20 min, and then allowed to cool to room temperature before using the coated tips. SEM analysis of the tips before and after coating by immersion in a solution or by vapor deposition showed that the patterning compound uniformly coated the tips. The uniform coating on the tips allows depositing the pattern compound on a substrate in a controlled manner, as well as obtaining high quality images. 40

Since DPN allows the formation of nanostructure images with the same tool used to form them, there was a tempting perspective of generating elaborate nanostructures of different soft materials with an excellent record. The basic idea to generate multiple patterns in the register by means of DPN is related to analogous strategies to generate multicomponent structures by electron beam lithography that has alignment marks. However, the DPN method has two different advantages, which does not make use of resistors or optical methods to locate alignment marks. For example, using DPN, self-assembled monolayer (SAM) points of 15 nm in diameter of 1,16-mercaptohexadecanoic acid (MHA) can be generated on a facet Au (111) substrate (the same preparation described above for atomic substrates Au planes (111)) keeping a tip coated with MHA in contact (0.1 nN) with the surface of Au (111) for ten seconds (see Figure 9A). By increasing the size of the scan, 50 images are formed after patterning points with the same tip by means of a lateral force microscope (LFM). Since SAM and gold discovered have very different wetting properties, the LFM provides excellent contrast. Wilbur et al., Langmuir 11, 825 (1995). Based on the position of the first pattern, the coordinates of additional patterns can be determined (see Figure 9B), allowing the precise placement of a second MHA point pattern. Note the uniformity of the points (Figure 9A) and that the maximum misalignment of the first pattern with respect to the second pattern is less than 10 nm (see the upper right edge of Figure 9C). The time elapsed between the generation of the data in Figures 9A and 9C was 10 minutes, demonstrating that the DPN, with adequate control over the environment, can be used to mold organic monolayers with a spatial and pattern resolution better than 10 nm under environmental conditions.

This method for standardization with multiple compounds for standardization requires a further modification of the experiment described above. Since images of the MHA SAM dot patterns were formed with a tip coated with a patterning compound, it is likely that a small undetectable amount of patterning compound was deposited while the pictures were being formed. This could significantly affect some applications of the DPN, especially those that have to do with electronic measurements on molecule-based structures. To overcome this problem, micrometric scale alignment marks drawn with an MHA-coated tip (crosshairs on Figure 10A) were used to accurately place nanostructures in a pristine area on the Au substrate. In a typical experiment, an initial pattern of parallel lines of 50 nm composed of MHA and separated 190 nm is prepared (see Figure 10A). This pattern was separated 2 μm from the outer alignment marks. Note that an image of these lines was not taken to avoid contamination of the pattern area. The MHA coated tip was then replaced with an ODT coated tip. This tip was used to locate the alignment marks, and then the previously calculated coordinates were used based on the position of the alignment marks (Figure 10B) to mold the substrate with a second set of parallel 50 nm SAM ODT lines ( see Figure 10C). Note that these lines were placed in an interdigitated manner and with almost perfect registration with respect to the first set of MHA SAM lines (see Figure 10C).

There is a unique capacity of the DPN called "overwrite". Overwriting involves the generation of a soft structure of one type of molding compound and is then filled with a second type of molding compound by scanning bitmap graphics through the original nanostructure. As an additional experiment of a test concept aimed at demonstrating capabilities as a multi-pattern compound, high register, and overwriting of the DPN over moderately large areas, an MHA coated tip was used to generate three geometric structures (a triangle, a square, and a pentagon) with line widths of 100 nm. The tip was then changed to a tip coated with ODT, and an area of 10 μm was overwritten by 8.5 μm that included the original nanostructures with the tip coated with ODT by scanning bitmap graphics 20 times through the substrate (contact force ~ 0.1 nN) (dark areas of Figure 11). Since water was used as a means of transport in these experiments, and the water solubility of the pattern compounds used in these experiments is very low, there was essentially no detectable change between the molecules used to generate the nanostructure and those used to overwrite on exposed gold (see Figure 11).

In summary, the recording capabilities of the high resolution multiple pattern compound of the DPN have been demonstrated. On an atomically flat surface of Au (111), 15 nm patterns were generated with a better spatial resolution at 10 nm. Even on a rough surface such as amorphous gold, the special resolution was better than conventional electron beam and photolithographic lithographic methods for patterning soft materials.

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Claims (33)

1. A nanolithography method comprising: provide a substrate; provide a microscope tip as a scanning probe; coat the tip with a pattern compound; Y contacting the coated tip with the substrate so that the compound is applied to the substrate with the help of a means of transport, wherein the means of transport forms a meniscus that closes the gap between the tip and the substrate so that The pattern compound is transported to the substrate by capillary transport, in order to produce a desired pattern.  2. The method of Claim 1 wherein the substrate is gold and the pattern compound is a protein or peptide or has the formula R1SH, R1SSR2, R1SR2, R1SO2H, (R1) 3P, R1NC, R1CN, (R1) 3N, R1COOH, or ArSH, in 10 where: R1 and R2 each have the formula X (CH2) n- and, if a compound is substituted with both R1 and R2, then R1 and R2 may be the same or different; n is 0-30; Ar is an aryl; fifteen X is -CH3, -COOH, -CO2 (CH2) mCH3, -OH, -CH2OH, ethylene glycol, hexa (ethylene glycol), -O (CH2) mCH3, -NH2, -NH (CH2) mNH2, halogen, glucose , maltose, C60 fulerene, a nucleic acid, a protein, or a ligand; Y m is 0 - 30. 3. The method of Claim 2 wherein the pattern compound has the formula R1SH or ArSH. 4. The method of Claim 3 wherein the standard compound is propanedithiol, hexanedithiol, octanediithol, n-hexadecanothiol, n-octadecanothiol, n-docosanothiol, 11-mercapto-1-undecanol, 16-mercapto-1-hexadecanoic acid , a, a'-p-xyldithiol, 4,4'-biphenyldithiol, terphenyldithiol, or DNA-alkanothiol. 5. The method of Claim 1 wherein the substrate is aluminum, gallium arsenide or titanium dioxide and the pattern compound has the formula R1SH, wherein: R1 has the formula X (CH2) n-; 25 n is 0-30; X is -CH3, -COOH, -CO2 (CH2) mCH3, -OH, -CH2OH, ethylene glycol, hexa (ethylene glycol), -O (CH2) mCH3, -NN2, -NH (CH2) mNH2, halogen, glucose , maltose, C60 fulerene, a nucleic acid, a protein, or a ligand; Y m is 0 - 30. 6. The method of Claim 5 wherein the pattern compound is 2-mercaptoacetic acid or n-30 octadecanothiol. 7. The method of Claim 1 wherein the substrate is silicon dioxide and the pattern compound is a protein or peptide or has the formula R1SH or R1SiCl3, wherein: R1 has the formula X (CH2) n-; n is 0-30; 35 X is -CH3, -COOH, -CO2 (CH2) mCH3, -OH, -CH2OH, ethylene glycol, hexa (ethylene glycol), -O (CH2) mCH3, -NH2, -NH (CH2) mNH2, halogen, glucose , maltose, C60 fulerene, a nucleic acid, a protein, or a ligand; and m is 0-30. 8. The method of Claim 7 wherein the standard compound is 16-mercapto-1-hexadecanoic acid, octadecyltrichlorosilane or 3- (2-aminoethylamino) propyltrimethoxysilane. 5 9. The method of Claim 1 wherein the tip is coated with the pattern compound by contacting the tip with a solution of the pattern compound one or more times. 10. The method of Claim 9 further comprising drying the tip each time it is removed from the patterning compound solution, except the last time so that the tip is wet even when it is brought into contact with the substrate to produce The desired pattern. 10 11. The method of Claim 9 further comprising: rinse the tip after it has been used to apply the pattern to the substrate; coat the tip with a different pattern compound; Y contacting the coated tip with the substrate so that the pattern compound is applied to the substrate in order to produce a desired pattern. fifteen 12. The method of Claim 11 wherein the steps of contacting, coating and washing, are repeated using as many different pattern compounds as necessary for the preparation of the desired pattern (s). 13. The method of Claim 12 further comprising providing a positioning system for aligning a pattern with respect to the other pattern (s). twenty 14. The method of Claim 1 wherein a plurality of tips are provided. 15. The method of Claim 14 wherein each of the plurality of tips is contacted with the same pattern compound. 16. The method of Claim 14 wherein the plurality of tips is contacted with a plurality of pattern compounds. 25 17. The method of Claim 14 wherein each tip produces the same pattern as the other tip (s). 18. The method of Claim 17 further comprising providing a positioning system to align a pattern with respect to the other pattern (s). 19. The method of Claim 14 wherein at least one tip produces a different pattern than that produced by the other tip (s). 30 20. The method of Claim 19, further comprising providing a positioning system to align a pattern with respect to the other pattern (s). 21. The method of Claim 1 wherein the tip is coated with a first pattern compound and is used to apply the first pattern compound to some or all of a second pattern compound that has already been applied to the substrate, being the second pattern compound capable of reacting or stably combining with the first pattern compound. 22. The method of Claim 1 further comprising treating the tip before coating it with the patterning compound to improve the fisisorption of the patterning compound. 23. The method of Claim 22 wherein the tip is coated with a thin solid layer of adhesion to improve the fisisorption of the patterning compound. 40 24. The method of Claim 23 wherein the tip is coated with titanium or chromium to form the solid thin layer of adhesion. 25. The method of Claim 22 wherein the patterning compound is in aqueous solution and the tip is treated to make it hydrophilic for the purpose of improving the fisisorption of the patterning compound. 26. The method of any one of Claims 1-25 wherein the tip is an atomic force microscope tip. 27. The method of any one of claims 1 to 25, wherein the tip is a near-field sweeping optical microscope tip (NSOM) or a scanning tunnel microscope tip (STM). 28. The method of any one of claims 1 to 27, wherein the compound is supplied to the substrate. 29. The method of any one of claims 1 to 28, wherein the tip is used to write the pattern. 30. The method of any one of claims 1 to 29, wherein the tip is a hollow tip. 31. The method of any one of claims 1 to 30, wherein the compound is a protein or peptide. 10 32. The method of any one of claims 1 to 30, wherein the compound is a nucleic acid, preferably an oligonucleotide, a DNA or an RNA. 33. The method of patterning a substrate according to the method of any one of Claims 1-32.