01 Sep 2003
The pick of this week’s patent applications including an efficient way to make photonic crystal circuits.
• Title: Temperature control system for cutaneous photodynamic therapy
Applicant: Spectra Systems Corporation, US
International application number: WO 03/070315
Patent application WO 03/070315 describes a patch that limits temperatures increases in the skin during photodynamic therapy (PDT). The patch contains temperature-sensitive materials that, after reaching a predetermined temperature, change from being transmissive in nature to either scattering, absorbing or reflecting at the wavelengths used for PDT. The authors add that the optical changes are reversible when the materials cool down.
• Title: Process for making photonic crystal circuits using an electron beam and ultraviolet lithography combination
Applicant: University of Delaware, US
International application number: WO 03/071587
The University of Delaware is trying to patent a process for making photonic crystal circuits that combines electron beam and ultraviolet (UV) lithography. “The process is based upon the discovery that some positive UV photoresists are electron-beam sensitive and behave like negative electron-beam photoresists,” say the inventors. They add that their idea combines the speed of UV lithography with the high resolution and control of the electron-beam approach. It also eliminates the need for a photomask.
• Title: Composition for forming anti-reflection coating
Applicant: Nissan Chemical Industries, Japan
International application number: WO 03/071357
A Japanese company is trying to patent an anti-reflection coating that it says can be used during 157nm lithography. The coating comprises a polymer compound containing a halogen atom. “The polymer compound preferably has a halogen atom introduced into the main chain thereof and/or a side chain connected with the main chain,” say the authors. They add that the coating does not intermix with a resist layer.