Cavities owing to hydrogen in Si single crystals grown by continuously charging CZ method

The quality of Si single crystals with a diameter of up to 150 mm in the length between 1 m to 1.5 m, grown by continuously charging Czochralski (CCZ) method, is studied and the Possibility of CCZ method is discussed. The profile of interstitial oxygen concentration (O-i) is almost constant along the growth direction. The profile of precipitated O-i exhibits a slight decrease along the first half of the crystal length, and a more remarkable decrease along the latter half. Many pits with a diameter up to 15 mu m are observed on a chemically polished surface of Si CCZ wafer. We believe the origin of these pits is cavities formed during CCZ crystal growth owing to hydrogen contained in raw granular polycrystalline Si. Besides the cavity problem, we have to solve some serious cost problems to apply CCZ method for actual production.