So Tanaka

Fabrication of arrays of large step‐free regions on Si(001)

In this letter we describe a method for producing large areas of Si(001) surfaces which are (i) free of atomic steps and (ii) arranged in regular patterns on the wafer. The first step is the fabrication of a two‐dimensional grating structure using e‐beam lithography and reactive ion etching. This grating is then annealed within the appropriate temperature window in ultrahigh vacuum to produce the desired array of (001) step‐free regions. We illustrate the success of the method through the use of low‐energy electron microscopy for a few repeat spacings on test structures each extending over a 3×3 mm2 area. Alternative processing steps are discussed as well as application to submicron device technology.

Fabrication of bi‐periodic sinusoidal structures on silicon

We illustrate a method for fabricating bi‐periodic quasi‐sinusoidal structures that are difficult to produce by conventional microfabrication techniques. By annealing bi‐periodic square wave structures in ultra‐high vacuum (UHV), the surface profile becomes quasi‐sinusoidal due to mass transport processes. The method is illustrated by the creation of 4 and 6 μm period structures on Si(001) through annealing at 1100 °C in UHV. Surface profiles are measured by atomic force microscopy (AFM). The structures produced may have applications in electronic or optical devices.

Annealing instabilities in small fabricated structures

Abstract When small fabricated structures are annealed under conditions where significant mass transport can occur, details of the shape can be altered as the material tries to reduce its total surface free-energy. Fluctuations in local surface curvature can lead to instabilities under the right geometrical conditions. In this Letter we describe the development of inhomogeneities in thin columns and ridges which have been fabricated on Si(001) wafer surfaces. We believe these instabilities to be closely related to the “Rayleigh” instability that causes such diverse phenomena as the break-up of fine columns of fluid into drops or the break-up of cylindrical second-phase material in a solid matrix.

Atomic Steps in the Decay of 1- and 2- Dimensional Gratings

This paper contains a brief summary of our experimental results on the characteristics of the evolution during annealing of periodic modulations on surfaces. Most of the work involves 1-dimensional modulations on vicinal surfaces but recent results with 2-dimensional structures are described. Results on Ni and Si are the most extensive. Amplitude-time decay relationships, scaling of rates with fundamental wavenumber and temperature dependencies are discussed. The importance of steps due to the ‘miscut’ from singular planes is emphasized. For surfaces near Si(001) we summarize observations on both the overall modulation decay and the dynamics of the corresponding step arrays. The role of processes other than surface diffusion, in particular volume diffusion and evaporation, in the decay process is addressed. Some preliminary results on morphology changes at silicate glass surfaces are described; in the dimension range investigated viscous flow appears to dominate.