Sub-10nm quantum dots

[wigglieverse]

The wafers were exposed in a Vistec Electron Beam Pattern Generator ...at 100 kV with an aperture of 300 µm (201 pA beam current, 2 nm estimated spot size).
The test patterns consisted of dots and lines with different widths that were written with different pitches and various exposures doses. The structures were all written with a fixed beam step size ...of 1.25 nm.

Depending on the designed linewidth, an exposure is performed by linearly scanning the beam once (1-exel line) or by scanning n adjacent lines (n-exel line). ...Namatsu ...suggested that a higher contrast can be obtained by using KOH-based developer instead of conventional TMAH. ...we report the achievement of 6 nm dots ...with a pitch of 125 nm in the x direction and 100 nm in the y direction in 20 nm HSQ layer on silicon substrates.

Although the pitch is relatively large, this result is important because these are the smallest dots ever written in HSQ. We also investigated the effect of a potassium hydroxide (KOH) aqueous solution developer on the ultimate resolution. ...We believe that by adjusting the development process ...and by refining the exposures strategies, the ultimate resolution than can be achieved with HSQ, can be improved. -Advanced Lithography Journal Mar 2007