Studies of the uniformity characteristics of EFG silicon ribbon

Ribbons characterized in this study were grown from two R.F. induction heated stations. Growth atmosphere was argon with hydrogen. The hydrogen was used to suppress arcing in the furnace. Graphite dies used in the growth were thoroughly cleaned and baked in an HC1 atmosphere to remove the heavy metal impurities. The silicon melt was phosphorous and boron doped to obtain 1 Ω-cm, n- and p-type ribbons respectively. Single crystal seeds fabricated from Cz wafers and previously grown ribbons were used as seeds. Typical growth rates were 0.75 to 0.80 inches per minute. The crystallographic orientation and structure of the ribbons was measured along the length, at given intervals, and across the width. The smallest ribbon was twenty feet in length, while the longest ribbon was eighty feet long. Structural studies were performed using the X-ray back reflection h u e technique and preferential chemical etching followed by optical microscopy.