Crystal Growth and Evaluation of Silicon for VLSI and ULSI

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10

Silicon Wafer Preparation for

VLSI and ULSI Processing

10.1 Introduction

Metallic contamination in silicon wafers has harmful effects on device performance and

circuits fabricated with them. It is well established that minor amounts of metals can degrade

thin oxide lm quality, leakage current densities, and minority carrier lifetimes. Fast-diffusing

metal impurities, such as copper, nickel, and palladium, easily precipitate at the wafer sur-

faces, causing small structural defects called S-pits, or, in a higher density, resulting in haze [1].

The formation of the S-pits and surface haze has been correlated with the generation of

oxidation- ...