Microstructure Observation of “Crystal-Originated Particles” on Silicon Wafers

Abstract

Microstructure shape of “crystal-originated particles” (COP's) on mirror-polished silicon wafers (a) as received, (b) cleaned with NH4OH/H2O2/H2O solution (SC-1), and (c) annealed at high temperature (∼1150° C) in O2/N2 mixture or in H2, were observed using a scanning electron microscope (SEM), transmission electron microscope (TEM) and atomic force microscope (AFM). Elemental analysis of the COP's was also made using TEM-energy dispersion X-ray spectroscope (EDX). The COP was a pyramidal pit with {111} sidewalls, or a vertical cave having some facets of {111}. In a part of the COP, oxygen was detected by TEM-EDX. It was suggested that the microstructure shape of the COP's has been determined until the mirror polishing is finished. The size of the COP becomes larger and the slopes of the COP become gentler after an anneal in 3% O2/N2 at 1150° C for 4 h and removal of the SiO2 layer by HF solution. The depth of the COP becomes shallower, its size larger and its corners rounder by annealing in H2 at 1100° C for 1 min. The COP's disappear by anealing in H2 at 1150° C for 4 h.

Structural inhomogeneity and silicon enrichment of buried SiO2 layers formed by oxygen ion implantation in silicon

“…Typical sizes of the regularly shaped pecipitates in CZ Si range from 0.05 to 0.3 m, 84,87,90 which is in the same range as for the low etch-rate BOX inclusions observed in the present work. The ''crystal originating particles'' observed at the surface of CZ Si wafers by AFM after HF etching also have sizes ranging from 0.12 to 0.3 m. 91 The shape of the low etch rate inclusions in the SIMOX BOX is pyramidal, with a rectangular base and an average top angle of 46°Ϯ1°. Assuming ͑111͒ faces of coesite as determining the pyramidal shape, and b perpendicular to the ͑001͒ interface Si plane, 88 the experimental a/b ratio is found to be 0.57Ϯ0.02.…”

Evolution of flow pattern defects in boron-doped 〈100〉 Czochralski silicon crystals during secco etching procedure

“…It has been clarified that there are three kinds of grown-in defects: crystal originated particles (COP) [5], laser scattering tomography defects (LSTDs) [6], FPDs [7]. The microstructure of COPs and LSTDs was identified as incomplete octahedral void surrounded mainly by {1 1 1} planes [8], and there were SiO x film with several nanometers thickness [9] on the side-walls. The formation and behavior of the void was studied [10,11].…”

New approach to remove crystal originated pits in Czochralski-grown silicon: combination of germanium ion implantation with solid-phase epitaxy

“…(2) Thermal treatment on Cz-Si at high temperature under argon, or hydrogen ambient [7][8][9][10][11][12][13][14]; (3) Growth of epitaxial overlayer on Cz-Si by chemical vapor deposition (CVD) technology [15][16][17][18].…”