Developed by the University of Illinois at Urbana-Champaign, this suite of six technologies enhances multiple facets of nanolithography and scanning probe microscopy. The suite features multifunctional, active probe arrays that enable nanoscale and microscale printing with multiple fluids, nanotube micromachining techniques for high-resolution probe tips, fluid dispensing systems for multiple probes, and a simple electrostatic actuation method for independently lifting individual probes in a high-density probe array. Used singularly or combined, the technologies each offer unique qualities and benefits that simplify and enhance both nanolithography and scanning probe microscopy.
The methods and materials that these technologies utilize can be applied to all types of scanning probe nanolithography as well as scanning probe microscopy.
- Biotechnology: High-density microarrays or biochips for genomics, toxicology, proteomics, and biological and chemical sensing.
- Semiconductors: Microelectronic components, photomask repair, and direct-write nanolithography.
- Imaging: High throughout scanning probe microscopy, mapping surface characteristics, and detecting surface defects.
Using essentially the same equipment but with varying probes and software, Scanning Probe Microscopy (SPM) with nanoscale probes offers great potential for both nanolithography and imaging. The Nanotip Engineering Suite enhances the functionality of SPM equipment, offering benefits in applications ranging from bioscience to semiconductors. Miniaturization of semiconductor chips could be greatly advanced with the use of scanning probe nanolithography. In genomics and proteomics, biochips containing arrays of dots such as DNA fragments allow researchers to study the vast number of interactions of various proteins on a single chip. Like semiconductor chips, the development of nanoscale scanning probes has great potential benefits for the creation and study of biochips. Current scanning probe nanolithography techniques for creating high-resolution patterning have limitations in both resolution and complexity, and they use inefficient processes.
The Nanotip Engineering Suite eliminates many of those limitations and improves the overall process for nanolithography as well as scanning probe microscopy.
1. Multifunctional Probe Array (TF04157)
Most current scanning probe lithography methods use a single tip or tip array that must be changed if a second "ink" needs to be applied. This probe change also requires calibration in order to maintain alignment and accuracy. Ths step is both time-consuming and inefficient and also often introduces contamination. To address these issues, this technology provides a multifunctional probe array with active probes that can perform direct chemical patterningand imaging sequentially in a singlerun with accurate registration and no need for changing probes. The technology uses actuators to enable individual control of probes for up and down movement as needed. Patterns using different chemicals and ranging from nano- to microscale can be created and then imaged without risk of cross-contamination and while eliminating the inefficiencies of switching probe tips.
- More versatile: An active multiprobe array enables the use of probe tips of differing sizes for generating patterns of differing sizes. Redundant probe tips can also carry different chemicals simultaneously for multi-ink lithography.
- Faster: This technology enables patterning and imaging sequentially in a single run, eliminating the need to change probes and recalibrate.
- Eliminates cross-contamination: By patterning and imaging with different probes within the same array, this technology eliminates the problem of cross-contamination.
- Accurate: Because the tip-to-tip distance in the array is known, accurate registration between patterns is easily achieved.
- Precision control: An integrated thermal actuator allows control to raise or lower individual probes.
2. Probe Fabrication Method and Microcontact Printing Technique (TF02082)
Scanning probe microscopes perform measurements using a probe that has a flexible cantilever beam with a sharp tip attached at the distal end. The fabrication methods for these probes have a number of major drawbacks, including time- sensitive and inefficient processes and difficulty in producing uniform sharpness. Because the cantilevers are made of inorganic thin films, high temperatures and multi-step processes are required to produce them. This new method for probe fabrication and microcontact printing eliminates these problems, while producing either a single probe or an array of probes. It uses an efficient process, lowcost materials, and produces a uniform probe profile. This technology also includes a method for microcontact printing using the fabricated probes described above with integrated elastomeric tips and a commercial scanning probe microscope. This method eliminates the costly and timeconsuming need for a photolithography mask by attaching "inks" to the probe tip and creating patterns with connecting dots. This new technique combines the sub-micrometer accuracy and features of the SPM with the chemical versatility and performance advantages of microcontact printing.
- Lower cost: By utilizing a substrate and sacrificial layer, probes can be fabricated at lower cost than with current fabrication methods. Additionally, the direct microcontact printing technique lowers costs by eliminating the need for a photolithographic mask.
- Improved efficiency: Reusing substrate templates to fabricate additional probes saves time as well as maintains consistent size and sharpness.
- Improved performance: Because the microcontact printing technique combines the features of the SPM with the chemical versatility and performance advantages of microcontact printing, sub-micrometer accuracy is enabled.
3. Machining Nanotube-sized Tips from Multiwalled Nanotubes (TF04162)
This technology uses an electron beam machining process to sharpen boron nitride nanotubes into fine-tipped probes for use in atomic force microscopes for molecular and nanostructure imaging and surface manipulation. The nanotube probes are of high strength, high Young's modulus of elasticity, and provide high aspect ratios.
- High strength: Because they are formed from multi-walled nanotubes, the resulting tips are very strong.
- High aspect ratio: The tip's fine point and nanometer-scale size enable high aspect ratios for viewing at the atomic level, providing a significant improvement.
4. Atomic force Microscopy (AFM) Fluid Dispensing System for Probe Arrays (TF02040)
To meet the need for an arrayed fluid dispensing system for multiple probes, this technology provides fabrication methods for multiple micro-channels connected to an array of fluid wells. This technology allows side-by-side probes to receive individual inks to create high-density arrays, particularly beneficial for studying biochemical substances such as DNA or proteins.
- Multiple Inks: Current technologies for inking nanolithography probes do not allow the placement of unique inks on each probe tip. Individual tip inking allows for application in high-density DNA and protein arrays.
5. Electrostatic Actuators for Controlling Vertical Movement of Probes(TF03110)
Problems with existing electrostatic actuators include complex fabrication methods, low deflection and force generation, large footprints requiring much wafer space and widely spaced probe tips. This design and fabrication method for electrostatic actuators uses the substrate surface as an electrode, simplifying fabrication. It also results in greater deflection and force and a much smaller footprint, enabling ultrahigh density probe arrays with improved performance.
- Simplified fabrication: Because this system includes only one electrode (in the probe), fabrication is greatly simplified.
- Smaller footprint: The electrostatic force and probe stiffness are linear functions of the probe width, making the actuation method highly scalable to very small sizes, potentially enabling ultra-high density probe arrays.
- Better performance: High voltage differences can be applied across the electrodes, resulting in high forces and large deflections.