Apparatus for producing an ingot comprising a crucible body with a lid assembly having a movable core member and method for producing silicon carbide ingot using the apparatus

1. An apparatus for producing an ingot, comprising:

a crucible body comprising an opening and in which raw materials are accommodated;

a lid assembly located at the opening and comprising a portion fixed to the crucible body; and

a seed crystal fixing unit located at a top end of the crucible body or between the crucible body and the lid assembly and comprising a seed crystal,

wherein the lid assembly comprises:

a placement hole comprising open upper and lower ends;

a frame member arranged along a periphery of the opening while surrounding a periphery of the placement hole; and

a core member located in the placement hole and movable upward and downward with respect to the frame member,

wherein the seed crystal fixing unit and the core member meet each other at one or more points and a space is present between the seed crystal fixing unit and the core member, and wherein an outer periphery of a lower surface of the core member is spaced apart from the periphery of the placement hole by a predetermined gap.

2. The apparatus according to claim 1 , wherein an outer peripheral diameter of the core member is less than a peripheral diameter of the placement hole.

3. The apparatus according to claim 1 , wherein the upward and downward movements of the core member eliminate or relieve compressive stress caused by warpage of the seed crystal fixing unit that is generated by rising temperature of the crucible body or its inner part.

4. The apparatus according to claim 1 , wherein the gap is 10 μm or more.

5. The apparatus according to claim 1 , wherein the seed crystal fixing unit comprises i) the seed crystal disposed on a front surface thereof and from which an ingot is grown, and ii) a seed crystal holder in direct contact with a rear surface of the seed crystal and adapted to fix the seed crystal.

6. The apparatus according to claim 1 , wherein an outer peripheral diameter of the core member is 0.7 to 1.2 times greater than a diameter of the seed crystal.

7. The apparatus according to claim 1 , wherein the core member comprises a plate made of graphite.

8. The apparatus according to claim 1 , wherein the frame member comprises a frame body having a predetermined thickness located on an upper end of the opening of the crucible body and an extension connected to the frame body and in contact with an inner periphery of the opening of the crucible body.

9. The apparatus according to claim 1 , wherein the core member comprises a vertical center as an imaginary line passing vertically through a center of the core member and is circular or toroidal in cross section when viewed from a plane perpendicular to the vertical center.

10. The apparatus according to claim 1 , wherein the core member comprises a vertical center as an imaginary line passing vertically through a center of the core member and a horizontal center as an imaginary line perpendicular to the vertical center and dividing the core member into upper and lower portions, and the outer peripheral diameter of one or both of the upper and lower portions gradually decreases toward the corresponding end of the vertical center.

11. A method for producing a single-crystal ingot using the apparatus according to claim 1 , the method comprising:

loading the crucible body with the raw materials, arranging a seed crystal such that a surface of the seed crystal faces the raw materials, and locating the lid assembly on the opening to set up the apparatus; and

applying suitable temperature and pressure conditions to the apparatus to grow an ingot from the seed crystal.

12. The method according to claim 11 , wherein:

in the set-up step, the seed crystal is fixedly arranged on a seed crystal holder and a lower end of the core member is brought into contact with an upper end of the seed crystal holder at one or more points; and

in the growth step, i) the core member removes or relieves thermal stress applied to the seed crystal holder, and ii) the core member moves upward or downward to remove or relieve compressive stress applied to the seed crystal holder such that an ingot is grown from the seed crystal.

13. The method according to claim 11 , wherein:

in the set-up step, the seed crystal is fixedly arranged on a seed crystal holder, a lower end of the core member is brought into contact with an upper end of the seed crystal holder at one or more points, and an outer periphery of a lower surface of the core member is spaced apart from the periphery of the placement hole by a predetermined gap; and

in the growth step, thermal insulation layers formed between an upper surface of a seed crystal fixing unit and the lower surface of the core member are removed by releasing heat from the crucible to the outside through the gap.

14. The method according to claim 11 , wherein the raw materials comprise carbon and silicon and the ingot is a silicon carbide single-crystal ingot whose surface is convex or flat.

15. The method according to claim 11 , wherein the seed crystal comprises a diameter of 4 inches or more.

16. An apparatus for producing an ingot, comprising:

a crucible comprising an opening and in which raw materials are accommodated;

a lid assembly disposed on the crucible, wherein the lid assembly comprises:

a placement hole;

a core member disposed in the placement hole to move up to increase volume in the crucible and move down to decrease volume in the crucible;

a seed crystal fixing unit disposed in the crucible in contact with the core member;

a space disposed between the core member and the seed crystal fixing unit; and

a frame member arranged along a periphery of the opening while surrounding a periphery of the placement hole,

wherein the seed crystal fixing unit and the core member meet each other at one or more points, and

wherein an outer periphery of a lower surface of the core member is spaced apart from the periphery of the placement hole by a predetermined gap.

17. A method of producing a single-crystal ingot using the apparatus according to claim 16 , the method comprising:

disposing raw material in the crucible;

fixing a seed crystal to the seed crystal fixing unit to face the raw material; and

applying temperature and pressure to grow an ingot from the seed crystal, wherein the core member moves up and down in the placement hole in response to one or more of the applying temperature and pressure and the growing of the ingot.