Method For Solidifying A Semiconductor With Adding Charges Of A Doped Semiconductor During The Crystallisation

Abstract

A method for semiconductor solidification which includes steps for: forming a bath of molten semiconductor from a first charge of semiconductor which includes dopants, solidification of the molten semiconductor, and which in addition includes, during solidification, the implementation of one or more steps for the addition of supplementary charges of semiconductor, which also contains dopants, to the molten semiconductor bath. The method has homogeneous resistivity throughout the solidified semiconductor, whilst preventing changes in the type of conductivity over the entire or a very large part of the semiconductor and which does not adversely effect the electrical properties of devices made from the semiconductor that is obtained.

Description

technical field [0001] The present invention relates to a silicon semiconductor solidification method, more specifically, it is a semiconductor solidification method that adds dopant semiconductor feedstock in the crystallization process, which can remove the semiconductor dopant in the semiconductor solidification process Processing is controlled. The invention is particularly applicable to the crystallization of liquid metallurgical silicon in the form of ingots or ribbons for the manufacture of photovoltaic cell substrates. Background technique [0002] During the directional solidification of a semiconductor containing one or more dopants, the dopant concentration changes along the direction of crystallization because the composition of the formed solid is different from that of the liquid (at large Dopant accumulation usually occurs in this liquid in most general cases). In more detail, with the liquid fully mixed, the dopant distribution in the ingot along the direct...

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And if the silicon contains a lot of phosphorous for a given resistivity, the effect will be even more dramatic

[0016] This change in conductivity type was not observed in the n-type ingot, since the concentration of phosphorous was always maintained higher than that of boron, however the difference between these concentrations was greater at the top of the ingot than will be larger from the beginning of the ingot, thus resulting in a non-uniform resistivity that decreases along the height of the ingot

[0017] Therefore, in all cases, most of the ingots were not suitable for use, either because of inhomogeneity in resistivity or because of variations in conductivity type

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