Influence of Magnetic Field on Critical Stress and Mobility of Dislocations in Silicon

Abstract

We have found the effect of strong influence of magnetic field treatment on the starting stresses of individual dislocations in Czochralski-grown silicon (CZ-Si). It is shown that the exposure of CZ-Si samples with dislocations at room temperature to magnetic field reduces essentially the starting stresses for dislocation motion. The effect is absent in FZ-Si samples. We suppose that magnetic field causes the singlet-triplet transitions in thermally exited states of oxygen complexes in a dislocation core that changes the state of oxygen already situated on dislocations in such a way that the mean binding energy of oxygen with a dislocation is diminished.

Spin‐resonant change of unlocking stress for dislocations in silicon

“…One can see that exposure in a magnetic field results in significant reduction of unlocking stress τ st (H). This result is in agreement with our previous publication [9] where the reduction of unlocking stress to the half of initial value τ st (0) was observed after exposure of sample in H=20kOe during 2-3 hours.…”

“…The procedure of unlocking stress measurements was quite similar to the one used in [9]. First the dislocations sources were introduced by the Vickers's indentation of ( 111 ) surface and then the dislocation half-loops extending from damaged areas were generated by a four-point bending technique at 600 o C. The parameters were adjusted to generate only one dislocation half-loops from every indentation point.…”

“…In our recent paper [9] we have found that the unlocking stress of individual dislocations measured in Cz-Si at 600 o C can be reduced by more than factor 2 by the exposure of sample to a static magnetic field of about H=20 kOe during 2-3 hour at room temperature. This finding leads us to idea that the magnetic field stimulates some spin-dependent reactions involving oxygen accumulated at dislocation.…”

Transformations of microdefect structure in silicon crystals under the influence of weak magnetic field

“…This specific form of RCs requires a careful choice of an adequate model of the defect structure of the sample and accurate fit of the measured RCs during their treatment. It is known that silicon crystals grown by the Czochralski method contain usually several types of microdefects (oxygen precipitates, stacking faults or dislocation loops of interstitial type) with size distributions from nano-to micrometers [2]. These distributions evolve during thermal treatments at elevated temperatures due to interaction of oxygen impurity and intrinsic point defects.…”

“…Another application of magnetic fields in modern silicon microelectronic industry is to study the interaction of dislocations with impurities such as oxygen or nitrogen [2][3][4][5][6]. This approach is used to lock dislocations in order to prevent their propagation under mechanical stresses arising in technological processes [7,8].…”