Single crystal processing by in-situ seed injection

Details Single crystal processing by in-situ seed injection Single crystal processing by in-situ seed injection

1999-07-29

2001-07-24

Hiteshew, Felisa (Department: 1765)

Single-crystal, oriented-crystal, and epitaxy growth processes;

Apparatus

With means for treating single-crystal

C117S200000, C117S900000, C422S245100

Reexamination Certificate

active

06264742

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates generally to semiconductor devices, and more particularly, to an apparatus and method for forming a device such as a spherical-shaped semiconductor crystal.
Conventional integrated circuits, or “chips,” are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface. Once completed, the wafer is then cut into one or more chips and assembled into packages. Although the processed chip includes several layers fabricated thereon, the chip still remains relatively flat.
Manufacturing the wafers requires creating rod-form polycrystalline semiconductor material; precisely cutting ingots from the semiconductor rods; cleaning and drying the cut ingots; manufacturing a large single crystal from the ingots by melting them in a quartz crucible; grinding, etching, and cleaning the surface of the crystal; cutting, lapping and polishing wafers from the crystal; and heat processing the wafers. Moreover, the wafers produced by the above process typically have many defects. These defects can be attributed to the difficulty in making a single, highly pure crystal due to the cutting, grinding and cleaning processes as well as impurities associated with containers used in forming the crystals. These defects become more and more prevalent as the integrated circuits formed on these wafers contain smaller and smaller dimensions.
In co-pending U.S. patent application Ser. No. 08/858,004 filed on May 16, 1997, a method and apparatus for manufacturing spherical-shaped semiconductor integrated circuit devices is disclosed. Although certain manufacturing methods for making spherical shaped crystals are disclosed in the above-referenced application, an improved method of making the spherical shaped crystals, which includes fewer defects and is more manufacturable, is desired.
SUMMARY OF THE INVENTION
The present invention, accordingly, provides an apparatus and method for processing crystals. To this end, one embodiment provides a receiver tube for receiving semiconductor granules. The granules are then directed to a chamber defined within an enclosure. The chamber maintains a heated, inert atmosphere with which to melt the semiconductor granules into a molten mass. A nozzle, located at one end of the chamber, creates droplets from the molten mass, which then drop through a long drop tube. As the droplets move through the drop tube, they form the spherical shaped semiconductor crystals.
In another embodiment, the drop tube is heated with an inductively coupled plasma torch located between the nozzle and the drop tube. The plasma torch melts the droplets, thereby decreasing the number of crystalline directions in the droplet.
In yet another embodiment, spherical shaped crystals are formed from polycrystal granules. The polycrystal granules are melted into a seed and a molten mass. The molten mass then solidifies around the in-situ seed. As a result, the molten mass creates a crystal with crystalline directions identical to those of the seed.
In a further embodiment, polycrystal granules are melted into a molten mass. The molten mass is then brought into contact with a single crystal seed which becomes embedded within the molten mass. The molten mass then solidifies around the in-situ seed, and creates a crystal with crystalline directions identical to those of the seed.
In still another embodiment, before the polycrystal granules are formed into the spherical shaped crystals, they are coated with a nucleating agent. Once coated, the granules are completely melted and then re-solidified. By so doing, the resulting polycrystal granules have fewer crystalline directions, which promotes the ability to form a single crystal seed.
In different embodiments, different structures may be utilized, some of which may not come into physical contact with any of the polycrystal granules, droplets, or other material.


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