IBM Research details 3D microscopic technique for nanoscale structures, devices

IBM Research details 3D microscopic technique for nanoscale structures, devices
IBM scientists have created a 3D map of the earth so small that 1,000 of them could fit on one grain of salt – important in the field of semiconductors because it could allow patterns and structures as small as 15-nm to be created at greatly reduced cost and complexity.
By Ann Steffora Mutschler, Contributing Editor -- Electronic News, 4/23/2010
IBM reported today that its scientists have created a 3D map of the earth so small that 1,000 of them could fit on one grain of salt – important in the field of semiconductors because it could allow patterns and structures as small as 15-nm to be created at greatly reduced cost and complexity.

The feat was accomplished through a breakthrough technique that uses a tiny, silicon tip with a sharp apex -- 100,000 times smaller than a sharpened pencil – that IBM said opens new prospects for developing nanosized objects in fields such as electronics, future chip technology, medicine, life sciences, and optoelectronics.

IBM’s researchers created several 3D and 2D patterns to demonstrate the technique using different materials for each one as reported in the scientific journals Science and Advanced Materials:

-- A 25-nanometer-high 3D replica of the Matterhorn, a famous Alpine mountain that soars 4,478 m (14,692 ft) high, was created in molecular glass, representing a scale of 1:5 billion.

-- Complete 3D map of the world measuring only 22 by 11 micrometers was "written" on a polymer. At this size, 1,000 world maps could fit on a grain of salt. In the relief, one thousand meters of altitude correspond to roughly eight nanometers (nm). It is composed of 500,000 pixels, each measuring 20 nm2, and was created in only 2 minutes and 23 seconds.

-- 2D nano-sized IBM logo was etched 400-nm-deep into silicon, demonstrating the viability of the technique for typical nanofabrication applications.

-- 2D high-resolution 15-nm dense line patterning.


IBM said the core component of its technique is a tiny, very sharp silicon tip measuring 500-nm in length and only a few nanometers at its apex.

“Advances in nanotechnology are intimately linked to the existence of high-quality methods and tools for producing nanoscale patterns and objects on surfaces. With its broad functionality and unique 3D patterning capability, this nanotip-based patterning methodology is a powerful tool for generating very small structures,” explained physicist Dr. Armin Knoll of IBM Research – Zurich, in a statement.

The tip is similar to that used in atomic force microscopes and is attached to a bendable cantilever that controllably scans the surface of the substrate material with the accuracy of one nanometer--a millionth of a millimeter. By applying heat and force, the nano-sized tip can remove substrate material based on predefined patterns, thus operating like a "nanomilling" machine with ultra-high precision, IBM explained.

Similar to using a milling machine, more material can be removed to create complex 3D structures with nanometer precision by modulating the force or by readdressing individual spots. To create the 3D replica of the Matterhorn, for example, 120 individual layers of material were successively removed from the molecular glass substrate.

Further, the technique achieves resolutions as high as 15-nm, with a potential of going even smaller by using existing methods such as e-beam lithography, which selectively exposes a surface to a beam of electrons, thereby creating patterns in a film, called a resist. The resist serves as a template for transferring the pattern to various materials, for example silicon, by means of etching. It is one of the most versatile and mature methods used today, but it is very costly and complex. With e-beam lithography, it is becoming increasingly challenging to fabricate patterns at resolutions below 30-nm, where the technical limitations of that method are reached, IBM noted.

And, compared to expensive e-beam-lithography tools that require several processing steps and equipment that can easily fill a laboratory, IBM’s tool that can sit on a tabletop, promises improved and extended capabilities at very high resolutions, but at one-fifth to one tenth of the cost and with far less complexity.

The nanotip-based technique also allows the pattern to be assessed directly by using the same tip to create an image of the written structures, as the IBM scientists demonstrated in their experiments.

IBM expects potential applications to range from the fast prototyping of nano-sized devices for future computer chips to the production of well defined micron-sized optical elements like aspheric lenses and lens-arrays for optoelectronics and on-chip optical communication.