Vacancy related crystal defects such as COP/FPD (Crystal Originated Pits/Flow Pattern Defects) can cause near surface problems during device manufacture. Examples of the device problems are poor GOI and current leakage in P-N Junctions. COPs are 0.1-0.2um octahedral shaped voids with walls covered by oxide. FPD is a vacancy cluster related defect exposed by preferential etching. Adding an epitaxial layer can eliminate these defects, although epi growth adds costs. For some device applications, a low defect crystal growth method can be applied to reduce the number of vacancy defects in the near surface device region. Modification of the crystal pulling speed and the cooling rate of the crystal can result in lower vacancy defect levels. This allows for the recombination between vacancies and interstitials, vacancy agglomeration and oxygen control resulting in reduction of surface defects.
SEH is able to provide two different levels of surface defect reduction: Low Defect Crystal and Near Perfect, COP Free Crystal. Both of these products provide a significant reduction in surface defects when compared to the standard CZ crystal. SEH produces near Epi surface quality in a FPD/COP free Polished Wafer with our NPC wafer.
SEH CZ Crystals can provide the following quality levels: