Concept and method to create a distinct low-temperature region in a Si melt for growth of a Si single ingot with a large diameter ratio using the noncontact crucible method

Abstract

The noncontact crucible (NOC) method is defined as a growth method to intentionally establish a distinct low-temperature region inside a Si melt. For the NOC growth of a uniform large Si single ingot without contact with the crucible wall, a large and deep low-temperature region must be created in the upper central part of a Si melt to allow natural crystal growth inside it. The novel method to create the low-temperature region has not been disclosed until now. In this paper, the concept and method are clearly shown on the basis of controlling the heat flow from the bottom heater into the Si melt using an insulating plate locally set under the crucible bottom. The effectiveness of such heat-flow control is proved by the growth of several Si single ingots with a large diameter ratio using the NOC method. The effects of the size and thickness of the insulating plate is also shown by the growth of Si single ingots.