EFFECTS OF RESIDUAL IRON CONTAMINATION INTRODUCED DURING WET CHEMICAL PROCESSING ON THIN OXIDE BREAKDOWN AND RELIABILITY CHARACTERISTICS

摘要

The effects of residual iron contamination introduced during wet chemical processing on subsequent thermal oxide characteristics are investigated. Iron concentration is measured using a-diffusion length technique applicable to real-time line monitoring. The density of gate oxide weak spots is given as a function of iron contamination level for oxide thicknesses ranging from 75 to 200A. Reduction of oxide thickness from 20 nm to 10 nm requires a reduction in iron contamination by 100 times. Iron contamination limits concerning gate oxide integrity are established.