Method of forming a sapphire crystal using a melt fixture including thermal shields having a stepped configuration
First Claim
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1. A method of forming a sapphire single crystal comprising:
- providing a melt fixture comprising;
a crucible;
a die having a length, wherein the die is open to and extends along a length of the crucible; and
a plurality of thermal shields overlying a crucible lid and adjacent to the die, wherein;
each of the thermal shields has a length, a width, and a thickness, wherein length>
width>
thickness;
the thermal shields include a lower thermal shield and an upper thermal shield;
the lower thermal shield is disposed between the crucible lid and the upper thermal shield; and
the upper thermal shield has a length that is shorter and extends along a smaller fraction of the length of the die than a length of the lower thermal shield, such that a combination of the lower and upper thermal shields defines a stepped configuration with respect to the length of the die;
forming a melt in the crucible; and
drawing an as-formed sapphire single crystal sheet from the die.
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Abstract
Various single crystals are disclosed including sapphire. The single crystals have desirable geometric properties, including a width not less than about 15 cm and the thickness is not less than about 0.5 cm. The single crystal may also have other features, such as a maximum thickness variation, and as-formed crystals may have a generally symmetrical neck portion, particularly related to the transition from the neck to the main body of the crystal. Methods and for forming such crystals and an apparatus for carrying out the methods are disclosed as well.
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Citations
20 Claims
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1. A method of forming a sapphire single crystal comprising:
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providing a melt fixture comprising; a crucible; a die having a length, wherein the die is open to and extends along a length of the crucible; and a plurality of thermal shields overlying a crucible lid and adjacent to the die, wherein; each of the thermal shields has a length, a width, and a thickness, wherein length>
width>
thickness;the thermal shields include a lower thermal shield and an upper thermal shield; the lower thermal shield is disposed between the crucible lid and the upper thermal shield; and the upper thermal shield has a length that is shorter and extends along a smaller fraction of the length of the die than a length of the lower thermal shield, such that a combination of the lower and upper thermal shields defines a stepped configuration with respect to the length of the die; forming a melt in the crucible; and drawing an as-formed sapphire single crystal sheet from the die. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification