VERTICAL PULLING AND ZONE MELTING METHOD FOR PRODUCING MONOCRYSTALLINE SILICON

摘要

A vertical pulling and zone melting method for producing mono-crystalline silicon is disclosed, which includes a vertical pulling process and a zone melting process successively. The vertical pulling process includes: feeding material to the silica crucible in a vertical pulling furnace before vacuum pumping and charging argon; heating to melt material and welding seed crystal by dropping the seed crystal after inducting the cooling water; pulling thin neck; making the shoulder larger; equi-dimensional growth; lowering the pulling speed and tailing; stopping heating and taking the crystal rod out of the furnace; shaping, scavenging and corroding the crystal rod. The zone melting process includes feeding the rod and seed crystal into zone melting furnace before vacuum pumping and charging gas; preheating the crystal rod ; welding it with seed crystal; pulling thin neck; making the shoulder larger and equi-dimensional growing; holding the crystal and clamper to clip the crystal; tailing; slowly cooling and shutting down the furnace. The method of the present invention for producing mono-crystalline silicon can overcome the defects of higher oxygen concentration due to vertical pulling process and difficulty in doping special solid elements in mono-crystalline silicon. It decreases the cost and period of producing mono-crystalline silicon by zone melting process, and also solves the problem of short of polycrystal material in producing mono-crystalline silicon by zone melting process.