Handbook of Silicon Based MEMS Materials and Technologies

21.1. Measuring Oxygen in Silicon

21.1.1. Oxygen in Silicon

Crystalline silicon grown with the Czochralski method contains high concentrations of oxygen, in the range of 5 × 10¹⁷ − 1 × 10¹⁸ atoms per cubic centimeter. Oxygen atoms initially occupy interstitial sites in the crystal lattice. However, due to high-temperature thermal treatments oxygen can agglomerate to form precipitates, which can be quite large clusters of oxygen combined with crystal defects (for details see Chapter 4). Oxygen increases the mechanical strength of silicon substantially, leading to increased resistance to plastic deformation, a particularly important property during high temperature processing. Oxygen precipitates, on the other hand, affect wet etching, causing ...