Preparing oriented semiconductor monocrystalline rods

Claim 2

IN A METHOD FOR THE PRODUCTION OF A (111)-ORIENTED SEMICONDUCTOR MONOCRYSTALLINE ROD HAVING A SPECIFIC RESISTANCE WHICH DECREASES TOWARD THE CENTER OF SAID ROD WHEREBY A FLOATING MELT ZONE IS POSITIONED TO ANNULARLY ENCOMPASS A (111)-ORIENTED SEMICONDUCTOR STARTING DOPED ROD AND SAID MELT ZONE IS AXIALLY MOVED ALONG SAID STARTING ROD WHICH IS HELD PERPENDICULARLY AT BOTH ITS ENDS, PROCEEDING FROM A (111)-ORIENTED SEED CRYSTAL IN CONTACT WITH ONE END OF SUCH STARTING ROD, THE IMPROVEMENT WHICH COMPRISES, ADJUSTING THE AXIS DISPLACEMENT OF SUCH STARTING ROD IN RESPECT TO THE AXIS OF THE RESOLIDIFIED SEMICONDUCTOR CRYSTAL ROD BEING PRODUCED FROM THE PASSAGE OF SUCH MELT ZONE SO THAT SUCH DISPLACEMENT IS SMALLER THAN 10 PERCENT OF THE DIAMETER OF THE SEMICONDUCTOR CRYSTAL ROD BEING PRODUCED, AXIALLY MOVING SAID MELT ZONE AT A SPEED OF AT LEAST 3.5 MAINTAINING A RATIO BETWEEN THE DIAMETERS OF SAID STARTING MAINTAINING A RATIO BETWEEN THE DIAMETERS OF SAID STARTING ROD TO SAID RESOLIDIFIED ROD GREATER THAN 1:1.

Claim 3

the profile of the interface between said so melted portion and said resolidified portion therebeneath to extend transversely across said resolidified rod radially symmetrically, and concavely, relative to the upper end of said rod, with the apex of said interface being at the axis of said resolidified rod.

Claim 4

the profile of the interface between said so melted portion and said resolidified portion therebeneath to extend transversely across said resolidified rod radially symmetrically, and concavely, relative to the upper end of said rod, with the apex of said interface being at the axis of said resolidified rod.

Claim 5

The process as claimed in claim 1, characterised in that a drawing speed of preferably about 5.5 mm/min is set.

Claim 6

A process for preparing an oriented semi-conductor monocrystalline rod having a specific resistance which drops towards the center thereof comprising the steps of simultaneously and continuously A. positioning generally vertically a generally uniformly cross-sectionally circular starting rod comprised of polycrystalline, semi-conductor material in an inert gasEous atmosphere with the bottom end portion of said starting rod being in contact with a seed crystal therefor, B. positioning a zone of heat annularly about said starting rod said zone of heat being adopted to substantially uniformly heat the portion of said starting rod within said zone of heat to an extent sufficient to uniformly and radially symmetrically melt such portion and to induce conversion of said semi-conductor material from such polycrystalline form to a substantially monocrystalline form upon resolidification of such so melted portion into a resolidified rod, said zone of heat initially being adjacent said bottom end portion, said resolidified rod being likewise generally uniformly cross-sectionally circular, C. moving said zone of heat vertically axially upwardly relative to said starting rod at a substantially uniform rate of at least about 3.5 mm/min. and thereby causing said so melted portion to move similarly upwardly through said starting rod in such uniform and radially symmetrical manner, D. substantially coaxially revolving said starting rod and said resolidified rod such that said starting rod below said so melted portion revolves at a rate of from about 5 to 100 r.p.m. while said resolidified rod above said so melted portion revolves at a rate of from about 0 to 50 r.p.m., E. said positionings, said moving, and said revolving cooperating to cause:

Claim 7

A process for preparing an oriented semi-conductor monocrystalline rod having a specific resistance which drops towards the center thereof comprising the steps of simultaneously and continuously A. positioning generally vertically a generally uniformly cross-sectionally circular starting rod comprised of polycrystalline, semi-conductor material in an inert gasEous atmosphere with the bottom end portion of said starting rod being in contact with a seed crystal therefor, B. positioning a zone of heat annularly about said starting rod said zone of heat being adopted to substantially uniformly heat the portion of said starting rod within said zone of heat to an extent sufficient to uniformly and radially symmetrically melt such portion and to induce conversion of said semi-conductor material from such polycrystalline form to a substantially monocrystalline form upon resolidification of such so melted portion into a resolidified rod, said zone of heat initially being adjacent said bottom end portion, said resolidified rod being likewise generally uniformly cross-sectionally circular, C. moving said zone of heat vertically axially upwardly relative to said starting rod at a substantially uniform rate of at least about 3.5 mm/min. and thereby causing said so melted portion to move similarly upwardly through said starting rod in such uniform and radially symmetrical manner, D. substantially coaxially revolving said starting rod and said resolidified rod such that said starting rod below said so melted portion revolves at a rate of from about 5 to 100 r.p.m. while said resolidified rod above said so melted portion revolves at a rate of from about 0 to 50 r.p.m., E. said positionings, said moving, and said revolving cooperating to cause:

Claim 8

An oriented semi-conductor monocrystalline rod having a specific resistance which drops towards the center of the rod, said rod being produced by the process of claim 3.

Claim 9

The process of claim 3 wherein the axial displacement of said semi-conductor material is not more than about 10 percent of the diameter of said recrystallized rod.

Claim 10

The process of claim 3 wherein said moving is accomplished at a substantially uniform rate of from about 3.5 to 10 mm/min.

Claim 11

The process of claim 3 wherein said moving is accomplished at a substantially uniform rate of about 5.5 mm/min.

Claim 12

The process of claim 3 wherein, in said revolving, said starting rod revolves at a rate of about 20 r.p.m. and said resolidified rod revolves at a rate of about 5 r.p.m.