Control of capillary die shaped crystal growth of silicon and germanium crystals

Claim 1

A method of growing a ribbon shaped crystalline body of silicon or germanium so that said body has a selected cross-sectional shape for a selected distance along its length, said material being at least partially reflective to radiation at a preselected wavelength, said method comprising growing and pulling said crystalline body from a growth pool of melt supplied by a capillary die and replenishing said growth pool with melt provided from a reservoir supply of melt, said body and said growth pool of melt forming a solid/liquid interface above said die and said growth pool being characterized by a meniscus which extends from said die and joins said body at said interface to form a solid/liquid/vapor junction at which the liquid surface of said meniscus intersects the solid surface of said body at a predetermined meniscus angle when the growth of said crystalline body is under steady state conditions, said method further comprising: observing preselected points on at least the portion of the surfaces of said body and said meniscus adjacent said junction for the quantity of radiation of said preselected wavelength reflected and emitted from each of said points in a direction substantially perpendicular to the meniscus surface formed at said junction when the growth of said crystalline body is under steady state conditions; determining which of the observed points exhibit a sharp change in the amount of reflected radiation of said preselected wavelength; and controlling the speed at which said body is being pulled or the temperature of said growth pool of melt so as to maintain those points exhibiting said sharp change at a preselected spatial position relative to a predetermined reference position.

Claim 2

A method of growing a ribbon shaped crystalline body of silicon or germanium so that said body has a selected cross-sectional shape for a selected distance along its length, said material being at least partially reflective to radiation at a preselected wavelength, said method comprising growing and pulling said crystalline body from a growth pool of melt supplied by a capillary die and replenishing said growth pool with melt provided from a reservoir supply of melt, said body and said growth pool of melt forming a solid/liquid interface above said die and said growth pool being characterized by a meniscus which extends from said die and joins said body at said interface to form a solid/liquid/vapor junction at which the liquid surface of said meniscus intersects the solid surface of said body at a predetermined meniscus angle when the growth of said crystalline body is under steady state conditions, said method further comprising: observing preselected points on at least the portion of the surfaces of said body and said meniscus adjacent said junction for the quantity of radiation of said preselected wavelength reflected and emitted from each of said points in a direction substantially perpendicular to the meniscus surface formed at said junction when the growth of said crystalline body is under steady state conditions; determining which of the observed points exhibit a sharp change in the amount of reflected radiation of said preselected wavelength; and controlling the speed at which said body is being pulled or the temperature of said growth pool of melt so as to maintain those points exhibiting said sharp change at a preselected spatial position relative to a predetermined reference position.