Columbia University

Technology Ventures

Enhancing the width of polycrystalline grains using a particulate mask and continuous motion sequential lateral solidification

Technology #m02-065

In the field of semiconductor processing, there have been several attempts to use lasers to convert thin amorphous silicon films into polycrystalline films. However, the polycrystalline grains generated by these processes are typically small and of non-uniform size with random microstructure. This method combines a sequence of laser pulses and a particulate mask to controllably and sequentially generate uniform large polycrystalline grains with controlled grain boundary locations. This technology could be utilized for the development of polycrystalline thin film semiconductors for use in higher quality electronic devices, such as flat panel displays.

Continuous motion sequential lateral solidification generates extended grains in a robust and controllable manner

This technology achieves the difficult task of controllably generating large polycrystalline grains with precise grain boundary locations. In this system, a particulate mask with a dot array or diamond array patterned section is placed between the amorphous silicon layer and laser beam. Utilizing the continuous motion sequential lateral solidification technique, the beam is shaped by the mask to irradiate the corresponding portion of thin film. The sample is then translated and the beam is masked again, melting a subsequent portion of the film. Through this process, the grains generated through sequential irradiation are widened in a controlled manner, allowing for generation of large grains with uniform size and structure.

This method was tested experimentally in the laboratory and grain width and orientation was confirmed using electron microscopy techniques.

Lead Inventor:

James S. Im, Ph.D.


  • Semiconductors
  • Thin film transistors
  • High quality electronic devices
  • Flat panel displays


  • Controls the width of grains perpendicular to the direction of primary crystallization
  • Provides well-defined crystallographic orientations
  • Produces large polycrystalline grains with controlled grain boundary locations
  • Results in higher quality polycrystalline silicon
  • Can be used on a variety of materials

Patent Information:

U.S. Patent Issued (US 8,859,436)

Tech Ventures Reference: M02-065

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