Nitrogen effect on oxygen precipitation in Czochralski silicon

Abstract

The nitrogen effect on enhancement of oxygen precipitation in Czochralski-grown silicon wafers has been investigated by means of a preferential chemical etching technique and secondary ion mass spectroscopy. The precipitate enhancement is evident in an oxygen out-diffused region in which oxygen precipitation does not normally occur. Incorporation of the nitrogen atoms in substitutional sites to generate very stable microdefects in Czochralski-grown silicon crystals can explain the nitrogen effect on oxygen precipitation.

Monocrystalline silicon used for integrated circuits: still on the way

“…4 Schematic diagram of the crystal growth furnace used for the EMCZ method (In the figure, Ga melt is the rotating connector between the power supply and the pulling shaft used for the electrode) [16] attracted much attention. It has been reported that the nitrogen doping could lock dislocations to increase mechanical strength [20], generate N-O complexes [21], produce denser crystal originated particles (COPs) with smaller size which can be eliminated at relative low temperature [22] and enhance oxygen precipitation to improve the IG ability of wafers [23]. Figure 5 shows the cross-sectional optical micrographs of conventional silicon and NCz silicon wafers subjected to a Lo-Hi annealing (800uC, 4 h + 1000uC, 16 h) following rapid thermal processing at 1250uC for 50 s in Ar [24].…”

Impurity engineering of Czochralski silicon used for ultra large-scaled-integrated circuits

“…The IG structures for NCZ-Si wafer could be easily achieved by high-low-high temperature (Hi-Lo-Hi) three-step anneal [14], or by hightemperature anneal ramping-up from low temperature [15] or even by single-step high-temperature anneal [16]. Shimura et al [17] have reported that tiny oxygen precipitates might exist in the oxygen out-diffusion zone of NCZ-Si after Hi-Lo-Hi treatments, which would affect the quality of DZ. However, we found that a perfect DZ can be generated in NCZ-Si wafers in suitable annealing conditions [18].…”

Investigation of nitrogen behaviors during Czochralski silicon crystal growth

“…It benefits for the formation of voidfree denuded zone (DZ) in the silicon near-surface and therefore improves the gate oxide integrity (GOI) of metal-oxide-silicon (MOS) devices [3]. Meanwhile, nitrogen can offer numerous heterogeneous nuclei for the formation of oxygen precipitates, acting as the intrinsic gettering (IG) centers in the silicon bulk for surfacial metals [4,5]. These particular properties of nitrogen in silicon are very interesting for microelectronics.…”