Metallographic and electron microscopical analysis of microdefects in Fz‐silicon crystals

Abstract

I n dislocation-free floating-zone silicon crystals two types of microdefects were observed and analyzed by means of optical and electron-microscopical methods. Microdefects of type I occur in swirl-type arrangements throughout the whole wafer and appear as etch hillocks below which one can find second phase particles. Due t o the chemical-iriechanical polishing near the wafer surface microdefects of type I1 are generated which also occiir in spiral arrangements. These defects could be identified t o be plate-like vacancy agglomerates on { l l l } planes.In versetzungsfrcien zonengeschniolzenen Siliziiiri\liristallen wurden zwei Arten von Mikrodefekten beobachtet nnd niit Hilfe optischer und elektronerimikl.oskopischer Methoden analysiert. Mikrodefekte des Typs I treten in swiilartigcn Ariordnungen tlurch die ganze Scheibe hinclurch auf und erscheinen als Atzhiigel, unter drnen man Teilchen einer zweiten Phase finden lrann. Infolge des cheinisch-mechanischen Poliercns wrrden nahe der Scheibenoberfliiche Mikrodefekte des Typs I1 gebildet, die in spiralforinigen Anordnungen auftreten. Diese Defekte konnten als pllttchenformige Lerrstellenttgglomcrate auf { 111)-Flachen itlcntifiziert werden.

Neutralization of Acceptors and Formation of Agglomerates in Silicon Wafers Due to Intrinsic Point Defects Created by Chemomechanical Polishing and by Quenching

“…The formation of structural defects by chemomechanical polishing nearby room temperature is remarkable. Opposite to [13] we found these defects in silicon of p-type, too. With a boron concentration of U x 1013 6111-3 the decrease in the forma- After that agglomerates were formed when sufficient point defects were present.…”

“…Due to quenching [12] agglomerates are also generated as structural defects, which, however, have only been taken into consideration as regards their effect on resistivity. The present paper reports on detailed relevant results of structural defects generated due to chemomechanical polishing (microdefects of type I1 [13]) or quenching. It has been tried to detect intrinsic point defects (vacancies, self-interstitials) as common origin of both the boron neutralizing and the structural defects.…”