Analyzing structure loss in Czochralski silicon growth: Root causes investigation through surface examination

Abstract

A considerable proportion of the grown Czochralski Si ingots are remelted due to the generation of dislocations or the so-called structure loss. The assessment of the failed ingots is a crucial step toward achieving higher yield. Nonetheless, characterizing Si ingots poses a challenge attributed to their inherent high brittleness and the elevated concentration of dislocations, further complicating the cutting process. In this work, we utilize a non-destructive method to categorize the failed ingots and reveal the root causes of this failure. This study is performed on roughly 80 industrial monocrystalline silicon ingots that are grown for solar cell applications. Most of these ingots have experienced structure loss during the body growth. Analyzing the surface features reveals major categories of the structure loss ingots. Approximately, 66% of the examined ingots seem to be linked with temperature fluctuations, specifically a sudden drop in the melt temperature, and contamination by foreign particles. It is found that the primary causes can be categorized into four major groups: melt contamination, thermal fluctuations, melt vibration, and variations in growth rate. The primary root causes are identified within a fishbone diagram.