Growth of Si single bulk crystals inside Si melts by the noncontact crucible method using silica crucibles without coating Si₃N ₄ particles

A noncontact crucible method for reducing stress in Si bulk crystals was proposed. In this method, the Si melt used has a large low-temperature region to ensure natural Si crystal growth inside it. Compared with the conventional growth methods, the present method has several merits such as the convex shape of the growing interface in the growth direction, the possibility of growing large ingots even with the use of a small crucible, and the low O concentration in the ingots because of the small convection in the Si melt due to existence of the large low-temperature region. We have confirmed that by using crucibles without coating Si₃N₄ particles, p-type Si single bulk crystals can be grown inside a Si melt without contacting with the crucible wall. The single bulk crystals grown had low dislocation densities (on the order of 10³/cm²). The diameter of the ingot obtained using a crucible with a 30 cm diameter was 22cm. The O concentration in the present ingots was relatively lower than that in ingots grown by the CZ method. An n-type ingot was grown using a crucible without Si₃N₄ coating. Several Σ3 twin grain boundaries were observed in the cross section of the ingot. The average minority carrier lifetime of an n-type wafer was higher than that for p-type wafers.