Stock material or miscellaneous articles – All metal or with adjacent metals – Microscopic interfacial wave or roughness
Reexamination Certificate
2000-12-07
2001-12-11
Koehler, Robert R. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Microscopic interfacial wave or roughness
C117S001000, C117S902000, C428S637000, C428S641000, C428S672000, C428S687000, C428S450000, C428S926000
Reexamination Certificate
active
06329070
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a technique for fabricating patterned crystals having two dimensionally periodic surface structures with nanometer-scale spacings.
2. Description of the Background Art
As the demand for smaller and smaller electronic devices, magnetic recording media, etc., has increased, a need has been created for improved fabrication processes for making such devices. Many such devices are or can be typically formed on substrates that have two-dimensional patterns of periodic surface structures that are used for the subsequent formation of the devices. The reduced size demands for the devices require that the spacings between the periodic structures be on the order of less than 100 nm. Unfortunately, previously known techniques for forming nanometer-scale patterns are not commercially feasible. For example, a number of lithographic methods exist that can be used to form these types of patterned structures. These methods include creating patterns in polymers, called resists, using microlithography based on short wavelength UV radiation or electron beams. Patterns can be formed because the solubility of polymers is changed by the imaging radiation, and when exposed to a solvent a portion of the polymer film is removed quickly to create the image. However, producing dimensions on a length-scale of less than 100 nm using these techniques is difficult and can be carried out only using very special imaging tools and materials.
The tremendous success of scanning probe microscopes has opened the way for the development of another fabrication technique known as proximal probe lithography. Very briefly, proximal probe lithography involves the use of a scanning tunneling (STM) or atomic force microscope (AFM). The techniques range from using the STM to define a pattern in a medium which is subsequently replicated in the underlying material, to STM induced materials deposition, and STM and AFM manipulation of nanometer scale structures. However, there is a significant amount of instrumental evolution that needs to take place before these proximal probe techniques can be practical in a high throughput environment. As a result, a need therefore still remains for a technique that can be employed to form nanometer-scale periodic structures and arrays that is simple and commercially practical.
SUMMARY OF THE INVENTION
The present invention fulfills the foregoing need through provision of a technique for fabricating nanometer-scale periodic arrays in which two crystals, each comprised of single crystals of any suitable material, are bonded together misoriented at an angle relative to one another about a common surface normal, thereby forming a bicrystal structure. One of the crystals is selected to be thin, on the order of 5 to 100 nanometers. The presence of the misorientation angle results in the formation of a twist grain boundary between the two crystals that produces periodic stress and strain fields with spacings that are directly related to the misorientation angle, and are in the nanometer-scale range (e.g., from 50 nanometers down to 1.5 nanometers). At small misorientation angles, these stress and strain fields result from the presence of crystal defects, known as dislocations, at the interface between the crystals. Periodic surface structures with spacings that are the same as the spacings of the stress and strain fields can be exposed through a process such as etching. The spacings of these periodic structures are controlled by the misorientation angle used during bonding.
As an example, a thick and a thin gold (
100
) single crystal can be bonded together to form a bicrystal containing a small angle twist grain boundary. Subsequent etching of the thin single crystal exposes pyramidal features having nanometer scale dimensions. The subject technique is also suitable for use with other materials as well, including, for example, silicon and sapphire. The invention can also be used with two different materials bonded together to form a bicrystal that contains a periodic array of misfit dislocations at the interface. Again, by superimposing a twist misorientation, the spacing of the surface features can be varied by selection of the misorientation angle.
REFERENCES:
patent: 4544469 (1985-10-01), Boxall et al.
patent: 4624766 (1986-11-01), Boxall et al.
patent: 5849669 (1998-12-01), Wen
patent: 5981400 (1999-11-01), Lo
patent: WO-01/00522-A2 (2001-01-01), None
F. S. Shieu and S. L. Sass, “Experimental and Theoretical Studies of the Disclocation Structure of NiO-PT Interfaces”, Department of Materials Science and Engineering, Feb. 1990, vol. 38, No. 9, pp. 1653-1667.
A. Bourret, “How to Control the Self-Organization of Nanoparticles by Bonded Thin Layers”, Surface Science 432 (1999), pp. 37-53 (no month given).
Ober Christopher K.
Sass Stephen L.
Suzuki Yuri
Cornell Research Foundation Inc.
Jones Tullar & Cooper PC
Koehler Robert R.
LandOfFree
Fabrication of periodic surface structures with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fabrication of periodic surface structures with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fabrication of periodic surface structures with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2578985