Apparatus and method for the production of ingots
View Patent ↗Apparatus and method for a crucible-less production of silicon ingots, wherein a support with a seed layer and a liquid layer is gradually lowered in a temperature field with a vertical gradient to solidify the liquid layer in a controlled way.
1. An apparatus for the production of ingots, the apparatus comprising:
a chamber to provide a controllable atmosphere, wherein the chamber has a top and a bottom spaced apart from each other in a longitudinal direction;
a support for supporting a seed layer, wherein the support is movable in the longitudinal direction relative to the chamber;
at least one means for controlling a temperature field in a given volume of growth in the chamber, wherein the temperature field has a temperature gradient in the longitudinal direction; and
a feeding apparatus for controllable feeding of material onto the seed layer, wherein the at least one means for controlling the temperature field comprises at least one top heating apparatus arranged above the support for the seed layer, wherein the top heating apparatus is designed to generate a temperature field with a temperature gradient in a direction perpendicular to the longitudinal direction, wherein the gradient in the longitudinal direction is in a range of 100 K/m to 10000 K/m and the gradient in a lateral direction is at most 1 K/cm.
2. An apparatus according to claim 1 , wherein the at least one top heating apparatus comprises at least two heating loops, wherein the at least two heating loops are arranged concentrically, wherein each of the heating loops is connected to a power source providing at least one of a DC power and an AC power, and wherein each of the heating loops is independently controllable.
3. An apparatus according to claim 1 , wherein the at least one means for controlling the temperature field comprises at least one bottom cooling apparatus arranged below a containment tray, which is part of the support for the seed layer.
4. An apparatus according to claim 1 , wherein at least one of said top heating apparatus and a bottom cooling apparatus is designed to control the temperature gradient in the lateral direction in the volume of growth.
5. An apparatus according to claim 1 , further comprising at least one perimeter heater having an inner perimeter matching the shape of an outer perimeter of the seed layer, wherein the perimeter heater comprises an inductive heating coil of one or more turns.
6. An apparatus according to claim 5 , wherein the cross-sectional shape of the seed layer and perimeter heater are rectilinear, having basically straight sides at roughly 90 degrees to one another, rounded corners with a radius of at least 1 mm and the seed layer is laterally positioned to fit within the cross-section of the perimeter heater.
7. An apparatus according to claim 5 , further comprising at least one perimeter cooler having an inner perimeter matching an outer perimeter of the seed layer, wherein the perimeter heater is arranged above the perimeter cooler.
8. An apparatus according to claim 1 , wherein the apparatus is crucibleless.
9. An apparatus according to claim 1 , wherein the lateral temperature gradient is controllable.