Migration of uniform fine lines for bodies of semiconductor materials having a (100) planar orientation of a major surface

Claim 1

In an improved method for the migration of a molten zone through a solid body of semiconductor material to form a region comprising the process steps of: a. selecting a body of single crystal semiconductor material having two major opposed surfaces being respectively the top and bottom surface thereof; a preferred crystallographic structure; a planar orientation of (100) for--at least the top surface thereof, a first selective type conductivity; a selected level of resistivity, and a vertical axis substantially aligned with the <100> axis of the crystal structure and which is also substantially perpendicular to the top surface; b. depositing at least one mass of metal on the top surface of the body; c. heating the body and the deposited metal to a preselected elevated temperature sufficient to form a melt of a metal-rich semiconductor material therein; d. establishing a temperature gradient substantially parallel to the vertical axis of the body and the <100> axis of the crystal structure, the surface on which the melt is formed being at the lower temperature, and e. migrating each melt of metal-rich semiconductor material as a molten zone through the solid body of semiconductor material for a sufficient period of time to reach a predetermined depth in the body from the top surface and to form a region of recrystallized semiconductor material of the body having solid solubility of the deposited metal therein having a width equal to the width of the metal deposited for forming the melt, a substantially uniform cross-sectional area and a substantially uniform level of resistivity throughout the entire region, the improvement comprising the steps of depositing the mass of metal of a predetermined thickness t and a predetermined width w which is expressed by the following formula: ##EQU3## wherein: t is the thickness of the metal deposited, d is the width of the recrystallized region of semiconductor material to be formed in situ in the body, x is the solubility of the semiconductor material in the metal to be migrated at a given processing temperature and the width w of the mass of metal is equal to the width d of the recrystallized region.