Ordering in Thermally Oxidized Silicon

Abstract

We present new evidence and a model for residual ordering of silicon atoms within the oxide of thermally oxidized silicon wafers. X-ray scattering is used to observe the residual order in thermally grown SiO2 on Si(001), (011), and (111) surfaces with thicknesses of 60 to 1000 A, for both on-axis and miscut surfaces. In every case, the scattering position can be predicted using a model which expands the silicon lattice during oxidation without completely disordering it. The amount of expansion and disorder is dependent on the type of oxidation process employed.

Reactions and diffusion of atomic and molecular oxygen in theSiO2network

“…Note that the original structure of the thermal oxide is not completely homogeneous but shows an inclined distribution of the residual order to some extent, depending on its formation process. 20,24 The result obtained indicates that diffusion of atomic oxygen additionally increases the slope of the residual order distribution. In the O-400°C sample, the residual order persists near the interface but is lost near the surface.…”

“…Figure 3 schematically shows the positions of Si atoms in thermally grown 23,24 SiO 2 and explains the concept of the residual order. In Fig.…”

“…The origin of the diffraction peak on which we focus has very recently been clarified to be the residual order of Si atoms within SiO 2 . 23,24 A silicon lattice is expanded during oxidation without completely disordering it. The intensity profile of the residual order peak can be used as a sensitive indicator for monitoring the structural changes of the thermal oxide.…”

Synchrotron X-ray Diffraction Studies of Thermal Oxidation of Si and SiGe

“…1 (2)(3)(4)(11)(12)(13). The intensity of the peaks depends on the thickness of the oxide layer, and the peaks disappear when the oxide layer is removed by etching in HF solution.…”

Metastable ultrathin crystal in thermally grown SiO2 film on Si substrate

“…In contrast, several X-ray diffraction studies suggest that certain thermally grown SiO 2 films contain crystalline domains. [4][5][6][7][8] This crystalline atomic arrangement in SiO 2 films is considered to originate from the parent Si substrate, i.e., residual order. Thus, the results of previous studies on thermally grown SiO 2 films are inconsistent, and the microscopic crystallography of SiO 2 films is still unclear despite the importance of the thermal oxidation process.…”