DIELECTRIC RELIABILITY MEASUREMENT METHODS - A REVIEW

Reliability of thin dielectric films such as silicon dioxide grown pn single crystalline silicon is of great importance for integrated circu its of present and future technologies. For the characterization of th e quality of dielectric films, it is essential to have measurement met hods available which can give a measure of dielectric reliability in a relatively short time. Stress biases are usually highly accelerated a nd cause destructive dielectric breakdown. Testing for dielectric reli ability has been performed for more than 30 years, and in that time ma ny different stress methods have been established. This article review s that most common dielectric reliability measurement methods and give s practical guidelines to the reliability engineer in the field of die lectric characterization. The examples and data shown here are mainly from MOS gate oxides. The aim of this review paper is to emphasize adv antages and disadvantages of the various stress methods. Appropriate d ielectric stress methods are pointed out for applications such as proc ess development, process characterization, pocess control and screenin g (burn-in). A broad number of different measurement techniques are de scribed in detail for which the set up of the measurement and its stre ss parameters are clarified. Suitable dielectric test structures and t he determination of the correct voltage and thickness of the dielectri c are discussed; they are essential to determine the electric field ac ross the thin film. The identification of dielectric breakdown and the interpretation and significance of the measurement results are review ed. A good understanding of the stress method and the various measured parameters is essential to draw correct conclusions for the lifetime of the dielectric at operating conditions. The commonly used, basic an alysis techniques for the measurement results are illustrated. Finally , the influence of stress-induced leakage currents on the dielectric r eliability characterization is discussed and other aspects relating to very thin oxides of future technologies are briefly described. The pa per also includes a large bibliography of more than 250 references. (C ) 1998 Elsevier Science Ltd.