Improved nanofabrication through guided transient liquefaction

Stephen Y. Chou and Qiangfei Xia

Nature Nanotechnology Vol 3, May 2008, 295-300.

Purpose of the Study

Demonstrate a new approach called self-perfection by liquefaction, which can remove fabrication defects and improve nanostructures post-fabrication.

 

Methods

The self-perfection by liquefaction (SPEL) method involves selectively melting nanostructures for a short period of time (hundreds of nanoseconds) by laser pulse. It also applies a set of boundary conditions (like a flat plate) to guide the flow of the molten material into the desired geometry before solidification.

 

Key findings

1.     Using the open-SPEL method the 3σ line-edge roughness(LER) of 70-nm-wide chromium grating lines was reduced from 8.4 nm to less than 1.5 nm, which is well below the ‘red-zone limit’ of 3 nm discussed in the International Technology Roadmap for Semiconductors.

2.     After guided-SPEL (using a 40 nm gap and a 595 mJ cm^-2 pulse), the width of a silicon line was reduced from 285 nm to 175 nm, while its height increased from 50 nm to 90 nm.

3.     Self-perfection by liquefaction (SPEL) can also be extended to other metals and semiconductors, dielectrics and large-area wafers.

 

Important Definitions

1.     open-SPEL: the nanostructures are located on a substrate without any additional boundary conditions.

2.     guided-SPEL: a flat plate is placed above the nanostructures that are to be improved, with a gap between the plate and the nanostructure.