DE2650779C3 - Method for healing crystal lattice damage in silicon crystals doped by neutron radiation - Google Patents

Claims (1)

Claim: Process for healing crystal lattice damage in silicon monocrystals doped by neutron irradiation, in which the silicon crystals are tempered depending on the irradiation conditions in the nuclear reactor and the proportion of carbon in the irradiated silicon, characterized in that with a ratio of thermal to fast neutrons in the nuclear reactor of 1: 1 to 10: 1, the annealing temperature at a carbon content in the irradiated silicon of> 3-10 ¹⁶ atoms / cm ³ to> 1100 ⁰ C, at a carbon content of <3 · ΙΟ ¹⁶ atoms / cm ³ to a value in the range of 750 to 1000 ⁰ C is set, and that with a ratio of thermal to fast neutrons in the nuclear reactor of 10: 1 to 100: I the tempering temperature with a carbon content in the irradiated silicon of> 3 · 10 ^lb atoms / cm ¹ to> 1000 ° C. at a carbon content of <3 · 10 ¹⁶ atoms / cm ^{J is set} to> 750 ³ C. The present invention relates to a method for Healing of crystal lattice damage through neutron radiation doped silicon monocrystals, in which the silicon monocrystals depend on the irradiation conditions and the amount of carbon in the irradiated silicon. Such a method can be found in German patent specification 12 14 789. A process is described here for the production of homogeneously n-doped silicon crystal bodies by irradiation with thermal neutrons, in which the silicon body is heat-treated until the lattice defects caused by the neutron irradiation are eliminated. The duration of the heat treatment depends on the intensity of the previous exposure to the neutrons in the nuclear reactor. The jjweiligc temperature and time is thus on the degree of Kristallgitterver voltage generated upon irradiation determined as a measure of the time and temperature specified for a silicon sample for 24 hours in an oven at 1000 ⁰ C. It has now been found that when out of these Crystals semiconductor components are manufactured, the electrical measured values, in particular the specific electrical resistance, sometimes change during the subsequent diffusion processes. The invention is therefore based on the object to heal the silicon crystals doped by neutron irradiation with regard to their crystal lattice defects suffered during irradiation in such a way that the semiconductor components made from these crystals are reproducible with regard to their electrical parameters Have measured values which must be in agreement with the electrical resistivities measured on the tempered crystal. From the German Offenlegungsschrift 25 16 514 it can be seen that in order to achieve stable measured values the jit tempering gieichiang at at least the same high Temperature as must be carried out for diffusion processes to be carried out later. The invention takes a different approach to obtain stable measurements on neutron-irradiated silicon crystals. _> "> to receive values after tempering and solve the The problem posed by the fact that in the method defined at the outset at a ratio of thermal too fast neutrons in the nuclear reactor from 1: 1 to 10: 1 the annealing temperature at a 'cm ³ cm ⁶ atoms / to> 1100 ⁰ C and at a carbon content of <3 ■ 10 ¹⁶ atoms /' set in carbon content in the irradiated silicon of> 3 x 10 to a value in the range of 750 ° to 1000 ⁰ C, or with a ratio of thermal to fast neutrons im Γ «Nuclear reactor from 10: 1 to 100: 1 the annealing temperature with a carbon content in the irradiated silicon of> 3 · 10'V atoms / cm ³ to> 1000 ° C and with a carbon content of <3 · 10 ' ⁶ atoms / cm'> 750 "C is set. This is the tempering effect ■ regardless of the temperature prevailing during tempering Furnace atmosphere. It was also found that the minimum temperature when tempering crystal wafers with a Thickness <2mm with the same carbon content as with ι, silicon rods compared to the tempering temperature can still be lowered.