Process for doping silicon semiconductors using an impregnated refractory dopant source

Claim 2

IN THE PROCESS FOR DOPING A SILICON SEMICONDUCTOR WHEREIN A SILICON SEMICONDUCTOR AND A SOLID DOPANT SOURCE FOR VAPOR PHASE TRANSPORT OF AN N-TYPE DOPANT ARE MAINTAINED IN VAPOR PHASE COMMUNICATION AT A TEMPERATURE AND FOR A TIME SUFFICIENT TO FORM A ZONE OF N-TYPE CONDUCTIVITY IN SAID SEMICONDUCTOR, THE IMPROVEMENT WHEREIN SAID SOLID DOPANT SOURCE COMPRISES A POROUS, INERT, RIGID, DIMENSIONALLY STABLE, REFRACTORY SUPPORT HAVING A VOLUME POROSITY IN THE RANGE OF ABOUT 30 PERCENT TO ABOUT 80 PERCENT AND AN AVERAGE PORE SIZE DIAMETER OF ABOUT 1 MICRON TO ABOUT 10 MICRONS, SAID SUPPORT HAVING BEEN FORMED BY COMPACTING AND SINTERING A REFRACTORY OXIDE POWDER, SAID SUPPORT BEING IMPREGNATED WITH A DOPANT COMPONENT COMPRISNG ALUMINUM METAPHOSPHATE, ARSENIC OXIDE, OR ANTIMONY OXIDE, SAID DOPANT COMPONENT BEING PERCENT IN THE PROPORTION OF AT LEAST ABOUT 20 PARTS BY WEIGHT OF SAID SUPPORT.

Claim 3

The process of claim 1 wherein said powder is alumina.

Claim 4

The process of claim 1 wherein said dopant component is aluminum metaphosphate.

Claim 5

The process of claim 1 wherein said dopant component is arsenic oxide.

Claim 6

The process of claim 1 wherein said dopant component is antimony oxide.

Claim 7

The process of claim 1 wherein said silicon semiconductor is a P-type semiconductor.

Claim 8

The process of claim 1 wherein a carrier gas is used for vapor phase transport of said dopant.

Claim 9

The process of claim 1 wherein said temperature is in the range of about 850*C. to about 1,250*C.

Claim 10

The method of claim 1 wherein said time varies from about 30 minutes to about 5 hours.

Claim 11

The process for diffusing phosphorus into a silicon semiconductor comprising the steps of: positioning at least one silicon semiconductor in a heating chamber; positioning a solid dopant source in said heating chamber in vapor phase communication with, but not in physical contact with, said silicon semiconductor, said dopant source comprising a porous, inert, rigid, dimensionally stable refractory support having a volume porosity in the range of about 30 to about 80 percent and an average pore size diameter of about 1 micron to about 10 microns, said support having been formed by compacting and sintering a refractory oxide powder, said support being impregnated with aluminum metaphosphate, said aluminum metaphosphate being present in the proportion of at least about 20 parts by weight per 100 parts of said support; subjecting said silicon semiconductor and said dopant source to a temperature in the range of 850*C. to about 1,250*C. for a time sufficient to liberate phosphorus oxide vapors from said dopant source; contacting said phosphorus oxide vapors with at least a portion of the surface of said semiconductor for a period of time sufficient to permit diffusion of phosphorus into the surface of said silicon semiconductor to form a phosphorus-enriched zone therein.

Claim 12

The process for diffusing phosphorus into a silicon semiconductor comprising the steps of: positioning at least one silicon semiconductor in a heating chamber; positioning a solid dopant source in said heating chamber in vapor phase communication with, but not in physical contact with, said silicon semiconductor, said dopant source comprising a porous, inert, rigid, dimensionally stable refractory support having a volume porosity in the range of about 30 to about 80 percent and an average pore size diameter of about 1 micron to about 10 microns, said support having been formed by compacting and sintering a refractory oxide powder, said support being impregnated with aluminum metaphosphate, said aluminum metaphosphate being present in the proportion of at least about 20 parts by weight per 100 parts of said support; subjecting said silicon semiconductor and said dopant source to a temperature in the range of 850*C. to about 1,250*C. for a time sufficient to liberate phosphorus oxide vapors from said dopant source; contacting said phosphorus oxide vapors with at least a portion of the surface of said semiconductor for a period of time sufficient to permit diffusion of phosphorus into the surface of said silicon semiconductor to form a phosphorus-enriched zone therein.

Claim 13

The process of claim 10 wherein said silicon semiconductor is a P-type semiconductor.

Claim 14

The process of claim 11 wherein said silicon semiconductor and said dopant source are in the form of wafers.

Claim 15

The process of claim 10 wherein a plurality of dopant source wafers and a plurality of silicon semiconductor wafers are alternately positioned with planar wafer surfaces being substantially parallel and in spaced confronting relationship.

Claim 16

The process of claim 10 wherein a pair of said silicon semiconductor wafers in back-to-back contact are alternately positioned in said substantially parallel, spaced, confronting relationship with planar surfaces of said dopant source wafers.

Claim 17

In the process of forming a P-N junction in a P-type silicon semiconductor and a solid dopant source for vapor phase transport of phosphorus oxide are maintained in vapor phase communication at a temperature and for a time sufficient to form said P-N junction, the improvement wherein said solid dopant source comprises a porous, inert, rigid, dimensionally stable, refractory support having a volume porosity in the range of about 30 to about 80 percent and an average pore size diameter of about 1 micron to about 10 microns, said support having been formed by compacting and sintering a refractory oxide powder, said support being impregnated with aluminum metaphosphate, said aluminum metaphosphate being present in the proportion of at least 20 parts of weight per hundred parts of support, said support being rigid and dimensionally stable during the period of forming said P-N junction.

Claim 18

In the process of forming a P-N junction in a P-type silicon semiconductor and a solid dopant source for vapor phase transport of phosphorus oxide are maintained in vapor phase communication at a temperature and for a time sufficient to form said P-N junction, the improvement wherein said solid dopant source comprises a porous, inert, rigid, dimensionally stable, refractory support having a volume porosity in the range of about 30 to about 80 percent and an average pore size diameter of about 1 micron to about 10 microns, said support having been formed by compacting and sintering a refractory oxide powder, said support being impregnated with aluminum metaphosphate, said aluminum metaphosphate being present in the proportion of at least 20 parts of weight per hundred parts of support, said support being rigid and dimensionally stable during the period of forming said P-N junction.

Claim 19

The process of claim 1 wherein said support has a volume porosity in the range of about 40 to about 60 percent.