Local oxidation induced by inhomogeneous stress on blistered Si surface

Igarashi, Shinichi*; Itakura, Akiko*; Kitajima, Masahiro*; Nakano, Shinsuke*; Muto, Shunsuke*; Tanabe, Tetsuo*; Yamamoto, Hiroyuki; Hojo, Kiichi

By utilizing surface stress to modify surface reaction potential and increase surface reactivity, a technique for the twodimensional patterning of surface chemical reactions may be realized by surface stress modulation. A blister is a local protrusion on a solid surface induced by gas ion irradiation, and is considered to create local stress on surface layers. Si(100) substrate was irradiated with H (incident energy: 10 keV, fluence: 110 ions) at an angle of 30 to the surface normal. Blisters of 1-5 mm in diameter at the base were formed. After the ion irradiation, the substrate was oxidized. Scanning Auger electron microscopy revealed that, compared with the flat surface, the perimeters of the blisters had a higher oxygen intensity whereas the blister tops had a lower oxygen intensity. The stress distribution of the blister was calculated using the finite element method. It was found that the surface layers were stretched laterally at the blisters tops and compressed at theperimeters, relative to the flat surface. There was a clear correspondence between the O distribution and the stress distribution on the surface. Our results indicate that the patterned oxidation of the Si surface can be governed by the application of surface stress.