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IBM demos new nanotechnology method to build chip components

Creates nanocrystal memory devices using self assembly technique compatible with conventional semiconductor processing


 

ARMONK, N.Y. -- December 8, 2003 -- IBM today announced it is the first to successfully apply a novel approach in nanotechnology to aid conventional semiconductor processing, potentially enabling continued device miniaturization and chip performance improvements. IBM used a "molecular self assembly" technique that is compatible with existing chip-making tools, making it attractive for applications in future microelectronics technologies because it avoids the high cost of tooling changes and the risks associated with major process changes.

IBM's self-assembly technique leverages the tendency of certain types of polymer molecules to organize themselves. The polymer molecules pattern critical device features that are smaller, denser, more precise, and more uniform than can be achieved using conventional methods like lithography. The use of techniques such as self assembly could ultimately lead to more powerful electronic devices such as microprocessors used in the growing array of computer systems, communications devices, and consumer electronics. IBM expects self-assembly techniques could be used in pilot phases 3-5 years from now.

"Self assembly opens up new opportunities for patterning at dimensions smaller than those in current technologies," said Dr. T.C. Chen, vice president of science and technology at IBM Research. "As components in information technology products continue to shrink toward the molecular scale, self-assembly techniques could be used to enhance lithographic methods."

Nanotechnology is a broad field of science in which materials are manipulated at dimensions which approach the size of individual atoms or molecules. Self assembly is a subset of nanotech that refers to the natural tendency of certain individual elements to arrange themselves into regular nanoscale patterns.

In this instance, IBM researchers used self assembly to form critical features of a semiconductor memory device. The polymer patterns the formation of a dense silicon nanocrystal array which becomes the basis for a variant of conventional FLASH memory. Nanocrystal memories are difficult to fabricate using conventional methods; by using self-assembly, IBM has discovered a much easier method to build conventional semiconductor devices such as FLASH memories. Device processing, including self assembly, was performed on 200 mm diameter silicon wafers using methods fully compatible with existing chip-making tools.

This nanotechnology breakthrough is reported in a paper entitled "Low Voltage, Scalable Nanocrystal FLASH Memory Fabricated by Templated Self Assembly" by K.W. Guarini, C.T. Black, Y. Zhang, I.V. Babich, E.M. Sikorski and L.M. Gignac will be presented by IBM tomorrow at the IEEE International Electron Devices Meeting (IEDM) in Washington, D.C. Continuing its leadership in technology innovation, IBM is presenting 19 papers at IEDM this year, more than any other company.

As part of IBM's efforts to increase its lead in the application of fundamental nanotechnology advancements, such as the molecular self assembly technique announced today, IBM inventors continue to apply for and receive numerous important patents. Included are patents that focus on implementations of nanotechnology in microelectronics, and thus have potential to generate valuable intellectual property licensing agreements in the future. Two recent examples include US6162532: Magnetic storage medium formed of nanoparticles (issued in 2000) and US6358813: Method for Increasing the Capacitance of a Semiconductor Capacitor (issued in 2002). Many additional IBM nanotechnology patent applications are pending approval from the United States Patent and Trademark Office.

More information about IBM's various nanotechnology projects

 
 

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IBM used self assembly to build a nanocrystal FLASH memory device

(a) Step 1: Polymer molecules are made to self assemble into perfect hexagonal arrangements. The sizes of the arrangement are set by the size of the polymer molecules. The dark circular areas are 20 nanometers in diameter and are spaced 40 nanometers apart.

(b) Step 2: IBM used the polymer material as a stencil to reproduce the nanoscale pattern in silicon dioxide, which is more rugged than the polymer and able to withstand higher temperatures. At this stage the polymer material is completely removed.

(c) Step 3: A combination of depositing silicon material and etching leaves silicon nanocrystals embedded within the 20 nanometer regions defined originally by the self assembled polymer.

(d) Dimensions of the hexagonal pattern of the initial polymer (dotted curve) are maintained throughout, as shown by the histogram of the final silicon nanocrystal dimensions (solid curve). The grey curve represents the dimensions of the hexagonal pattern at an intermediate process step.

[ View Self Assembly Animation ]


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Arrays of uniformly-sized 20 nanometer diameter silicon nanocrystals (patterned using self assembly) are embedded between the device gate and silicon substrate. The device operates as a memory by storing charge in the nanocrystals.

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Silicon nanocrystal arrays are formed between the device polysilicon gate and silicon substrate, and are electrically-isolated by control- and program-oxides. The nanocrystal dimensions and positions in our device are defined using self assembly.

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The self assembly process IBM has used to construct our nanocrystal memory devices relies on the natural property that most polymer materials do not mix well (a similar phenomenon to mixing oil and water).


See also:
  ·  Press Resource: IBM Nanotechnology announcement at IEDM



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