Electron Beam Etching of Chromium Improves Spatial Resolution and Accuracy in Photolithographic Fabrication

Project ID: 1938-AP
Available for non-exclusive licensing

Background

Photolithography is used in the fabrication of semiconductors. The process uses photomasks to selectively expose the material and etch the material. However, as the dimension of microelectronic devices shrink down below 100 nm, shorter wavelength lights—i.e., 157 and 135 nm—will be used for photolithography. The current technology for fabricating and repairing these lithographic photomasks may not meet the future requirements.

Additionally, the current focused ion-beam technology uses metal ions to remove excess chromium spots or lines from the mask. The deposition or implantation of these metal ions will cause transmission loss or reflectivity loss. The loss predicted for these technologies will cause an unacceptable critical dimension shift.

Invention Description

This invention is to replace current focused ion-beam technology with a new method for etching chromium and chromium oxide.This method uses electron-beam irradiation along with selected chemicals directly to remove chromium or chromium oxide film from a solid substrate. The reactions amongst these chemicals results in the formation of volatile chromium compounds and desorption from the solid surface.

Since the etching is controlled by electron-beam irradiation, a high spatial resolution can be reached if highly focused electron beam is applied. Potentially, this method can also be used for etching other material by using different chemicals. For example, carbon film etching has also been realized.

Benefits

High spatial resolution
Prevents transmission loss and reflectivity loss
Nano or micro sized chromium spots and lines can be etched

Features

Reactive chemicals, introduced in gas phase, are decomposed on the surface of the chromium film by electron beam and consequently reacted with chromium or chromium oxide
Does not implant or deposit any other material into the substrate etched, unlike focused ion-beam technology

Market Potential/Applications

Electron beam etching of chromium and chromium oxide, lithographic photomask fabrication and repair, machining metal wires and carbon tubes

Development Stage

Proof of concept

UT Researcher

John M. White, Ph.D., Chemistry and Biochemistry, University of Texas at Austin
Jason Eklund, University of Texas at Austin
Qi Wang, Ph.D., Chemical Engineering, University of Texas at Austin
Yangming Sun, Ph.D., Chemistry and Biochemistry, University of Texas at Austin

OTC Contact Information

Jitendra Jain, Licensing Specialist
jjain@otc.utexas.edu
512-471-9055