Siemens Aktiengesellschaft

Joachim Martin

Ernst W Haas

Manfred Schnoeller

Konrad Reuschel

Heinz Mitlehner

Reinhold Kuhnert

Gunter Raab

Manfred Schnoller

Joachim Burtscher

Heinz-Herbert Arndt

Gustav Fischer

A method for manufacturing regions having adjustable uniform doping in silicon crystal wafers by neutron irradiation according to the reaction Si.sup.30 (n,.gamma.) Si.sup.31 .beta..sup.- P.sup.31 includes the steps of covering the silicon crystal wafer with neutron-absorbing materials of different thicknesses during the irradiation, and selecting materials having isotopes having a high absorption cross-section which yield stable isotopes in the nuclear reaction having small or short-lived activity. Suitable isotopes are B.sup.10, Cd.sup.113, Sm.sup.149, Gd.sup.155 and Gd.sup.157. The regions are generated photolithographically. By such specific material selection, very small layer thicknesses can be used and microfine surface zones or areas can be doped with high geometrical precision and large penetration depth. The method is particularly suited for manufacturing power thyristors.

Method for manufacturing regions having adjustable uniform doping in

An apparatus for doping a semiconductor crystalline rod by nuclear or radiogenic reactions comprised of a hollow irradiation housing having axially and rotatably movable rod support means within the chamber thereof and a neutron conductive sleeve connected with the housing and providing communication between a neutron source and the housing chamber. Accurate and controlled doping of a semiconductor crystalline rod mounted on the rod support means within the housing chamber occurs via controlled rod movement in relation to the neutron source.

Apparatus for doping a semiconductor crystalline rod

Si monocrystals of the n-type are produced by zone melting polycrystalline Si rods under conditions sufficient to produce monocrystal rods, measuring the specific conductivity of such monocrystal rods and subjecting such monocrystal rods to a controlled radiation by thermal neutrons based on the measured conductivity to produce a desired degree of n-conductivity in the ultimately attained rods.

Method of producing homogeneously doped n-type Si monocrystals by

A homogeneously doped p-conductive semiconductor material is produced by irradiating a desired semiconductor material with .gamma.-photons which trigger nuclear reactions within such irradiated material to form dopant atoms therein.

Method of producing homogeneously doped p-conductive semiconductor

A semiconductor layer, such as an epitaxial layer on a suitable substrate is subjected to controlled bombardment by neutrons whereby the atoms of the semiconductor layer are converted via nuclear reaction into doping material atoms.

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Erlangen, Germany

Joachim Martin