The performance is several times better than that described for any optical or Electron Beam Lithography (EBL) methods, claims Pavel, highlighting that the written patterns on the resist were successfully transferred to a Si wafer at writing speeds comparable to current industry standards.
In 2012, the company had already demonstrated the direct writing of 2nm width lines through quantum optical lithography using special fluorescent photosensitive glass-ceramics to support quantum multi-photon confinement effects.
Since then, the Storex Technologies has developed a proprietary photoresist material, the QMC-5, which also presents quantum multi-photon confinement effects. Spin coating a 5nm thick photoresist with such properties allows the pattern transfer to silicon through etching after the direct beam writing.
The experiment was carried out at room temperature and atmospheric pressure, using a commercial 650nm laser diode mounted on a specially-built optical pick-up stage. The piezo-controlled optical stage has a 0.6NA (Numerical Aperture) lens that controls the laser to deliver a Gaussian beam of 2µm focus diameter.
“In effect, with its multi-photon containment properties, the specially engineered photoresist material serves as a nanolens, enabling a very high resolution at the centre of the beam”, explained Pavel when interviewed by EE Times Europe .
According to the paper, the quantum optical lithography taking place in the special resist involves a cooperative interaction of many photons. A three-photon process in absorption phase and a 540 photons process as suggested by quantum lithography theory for the writing phase.
This is a real breakthrough as quantum optical lithography puts aside the diffraction limits encountered by traditional optical lithography using masks.
Next on Dr Pavel’s agenda is to determine accurately the resolution at which quantum optical lithography could be pushed at 650nm. “It is a difficult metrological problem to solve, but we would like to find out what the resolution limit we could reach with this approach. Is it in the 5 angstrom or in the 1 angstrom range?” he said.