Method for pr0duction of alloyed monocrystals or polycrystals of silicon

FIELD: production of solar batteries, integrated circuits and other semiconducting devices.

SUBSTANCE: the invention presents a method of production of alloyed monocrystals or polycrystals of silicon and may be used in production of solar batteries, integrated circuits and other semiconductor devices. The substance of the invention: the method of SUBSTANCE: the invention presents a method of production of alloyed monocrystals or polycrystals of silicon includes preparation of the initial charge consisting of 50 % of silicon alloyed with phosphorus with a specific electrical resistance of 0.8-3.0 Ohm·cm or boron with specific electrical resistance of 1-7 Ohm·cm, its melting-down and consequent growing of crystals from the melt, in which additionally enter elements of IV group from the periodic table by Mendeleyev, in the capacity of which use germanium, titanium, zirconium or hafnium use in concentrations of 1017-7·1019 cm-3. The invention allows to produce chips with high values of life time of minority carrier (LTMC), high homogeneity of electric resistivity (ER) and high concentration of oxygen, with a low concentration of defects and increased thermostability and radiation resistance.

EFFECT: the invention ensures production of chips with high values of LTMC, high homogeneity of ER and high concentration of oxygen, with a low concentration of defects and increased thermostability and radiation resistance.

2 cl, 4 ex, 1 tbl

 

The invention relates to the manufacture of doped single-crystal or polycrystalline silicon, used in the production of solar panels (modules), integrated circuits and other semiconductor devices. The mass production of solar cells requires a reduction in the value of their power. Therefore, the silicon single crystals or polycrystals are made using as charge cheap silicon, for example refined metallurgical silicon, or waste of the production of silicon single crystals. Manufacturer of solar panels on polycrystals gives the lowest cost solar panels. In all cases, the highest coefficient of performance (COP) gives silicon with high values of the lifetime of charge carriers (WINS). To single-crystal silicon for solar cells that are based in space, the quality requirements are much higher. In addition, the silicon should have a high radiation resistance. The single crystal silicon for integrated circuits must have high values URNS, low defect density and high uniformity in the distribution of electrical resistivity (electrical resistivity), and other parameters. All these requirements cannot be solved by optimizing the conditions and modes of cultivation of silicon oriented crystallization. Need new solutions.

Known to the persons receiving silicon, a heavily-doped simultaneously with phosphorus and germanium. (U.S. patent No. 5553566, MCL 30 In 15/04, 10.09.1996). The method does not provide for silicon with high values URNS and low defect density.

A method of obtaining a semiconductor silicon by initial preparation of the mixture, its fusion with subsequent crystal growth from the melt, which impose additional germanium, which is the element of the 4 groups of the periodic table and boron. (US 4631234, MCL H 01 L 21/20, 23.12.1986).

The known method is intended for hardening of silicon and allows you to get the silicon with high values WINS, thermal stability and radiation resistance.

The present invention is directed to obtaining single crystals or polycrystalline silicon n - and p-type conductivity with high values URNS, with high uniformity of resistivity and oxygen concentration, with low defect density and high thermal stability and radiation resistance in post-crystallisation Alte rations period and in the process of manufacturing devices. The use of plates from single crystals or polycrystals in the manufacture of solar cells, integrated circuits and other devices provides increased efficiency and improvement of the parameters of the devices. This technical result is achieved by a method of obtaining a doped single-crystal or poly is kristallov silicon by initial preparation of the mixture, its fusion with subsequent crystal growth from the melt, which impose additional elements 4 groups table Mendeleev, the mixture includes 50% of silicon doped with phosphorus, with electrical resistivity of 0.8-3.0 Ohm·cm, or boron, with specific electrical resistance 1-7 Om·cm, and the group-4 elements of the periodic table use germanium, titanium, zirconium or hafnium in concentrations of 1017-7·1019cm-3in the melt can also be entered germanium with one of the elements of a number of zirconium, hafnium and titanium.

Significant difference between the proposed method to obtain single crystals or polycrystalline silicon is further introduction into the melt of the elements of a number of germanium, titanium, zirconium, hafnium at concentrations of 1017-7·1019cm-3. Additional introduction into the melt of one or two elements from the specified range allows to achieve the technical result - obtaining single crystals or polycrystalline silicon with a uniform distribution of electrical resistivity, concentration of dopants and oxygen, with high values WINS and high thermal stability, radiation resistance and low defect density. Introduction into the melt of elements from the specified range ensures the formation of a melt with razuporyadochennoi structure is, with a reduced interatomic interactions, the properties of which at temperatures of 10-15 To above the crystallization temperature are the same as those of the melts without added elements, overheated relative to the crystallization temperature at 150-200 K.

The choice of the lower limit of the concentration of advanced input elements due to the fact that at smaller values of the positive effect is absent. At the concentrations are additionally introduced into the melt of the items than their upper limit, bullion (crystal) worsens the perfection patterns (increased concentration of various defects, reduced URNS), which leads to lowering the instrument parameters and efficiency.

On the grown single crystals and polycrystals obtained by the proposed method, we measured the electrical resistivity by four-probe method, the concentration of microdefects in standard stain. Measurement of electrical resistivity were performed on washers cut from ingots (crystals) before and after sequential annealing at temperatures of 700 and 1000°for 5 hours in nitrogen atmosphere.

Example No. 1. Were grown silicon single crystals by the Czochralski method at the facility, the Subject-50. The single crystal growth was performed in an argon atmosphere. It overpressure was 15-20 mm Hg. The charge in the crucible of propelling quartz contained waste from the production of single crystals doped with phosphorus with a resistivity of 0.8-3.0 Ohm· see who performed the function of ligatures phosphorus in the amount of 50%, and the raw brand KP-1 - 50%. The total amount of silicon in the charge was 25 kg batch was additionally loaded germanium brand HPP-40 in the amount of 1019cm-3or 3·1019cm-3or 7·1019cm-3. The single crystals with a diameter of 125 mm was grown in the direction of /100/ and a speed of 2.5 mm min. Speed of the single crystals was 15 rpm, and the crucible 5 Rev/min For each of the listed concentrations Germany in the melt was raised by three of the single crystal in the same conditions. For comparison, identical conditions were grown silicon single crystal brand KEF-4.5 out of a melt containing germanium as the analogue of (2·1020cm-3). All of the single crystals with the upper and lower ends cut washers with a thickness of 2 cm, which was annealed at a temperature of 650°30 min, according to widely accepted technologies for removal of termodonte and determine the actual resistivity in single crystals. On the annealed washers were measured electrical resistivity, and the variation of resistivity was calculated by the formula

Where the index “Mach” was defined as its maximum value, and “min” minimum. Samples were measured WINS on installing the microwave relaxometry. The concentration of oxidative packaging defects (TAC) was determined by etching and annealing according to the method of EM is 012.751. Samples from every single crystals were subjected to annealing at a temperature of 450°C in nitrogen atmosphere every hour for 12 h to evaluate thermal stability. All crystals were without dislocations. The results are given in the table.

Example No. 2. The single crystal growth, the measurement of resistivity, WINS determination ODE, ΔWES, evaluation of thermal stability was carried out as in example No. 1. The charge in the crucible contained waste from the production of single crystals, doped with boron, with WES 1-5 Ohm·see 50% of the entire mixture and raw brand KP-1 - the remaining 50%. The total amount of silicon in the crucible was 25 kg batch was additionally introduced germanium in an amount of 3·1019cm-3and zirconium in an amount of 1017cm-3or 5·1017cm-3zirconium and germanium in the amount of 8·1018cm-3or zirconium in an amount of 1018cm-3and germanium 5·1018cm-3. For each pair of added elements were grown on three of the single crystal. In identical conditions has grown silicon crystal brand KDB-10 from the melt with a GE concentration as the similar - 2·1020cm-3. The measurement results are given in the table.

Example No. 3. Conditions for growing single crystals, all measurements were carried out as in example No. 1. As in example No. 2 was additionally introduced two elements in the same concentrations. That is are instead zirconium introduced hafnium. It was grown for each pair of inputs of the three elements of the single crystal. The results of the measurements are shown in the table.

Example No. 4. Grew polycrystalline silicon by the Bridgman method-stockburger, doped with boron with WES 3-5 Ohm·see the Charge consisted of scrub (waste) production of polycrystalline silicon and waste production of monocrystalline silicon doped with boron, which as in example No. 2 was the ligatures. WES monocrystalline silicon was 1-7 Om·see the ratio of the amounts of scrub and waste production of single crystals was 50% to 50%. To the mixture was additionally introduced with germanium concentrations the same as in example No. 1. Raised three polycrystalline ingot with a large monocrystalline areas. They measured the electrical resistivity and WINS the same way as in examples No. 1-3. From the same mixture, but with a concentration of germanium, the concentration of the analogue of (2·1020cm-3) was grown one polycrystal with WES 3-7 Om·see Plate cut from single crystals grown under the conditions described in example No. 2, with a concentration of germanium in the charge 7·1019cm-3and the plate of single crystal analog derived from a mixture with a concentration of Germany 2·1020cm-3was irradiated by fast electrons with an energy of 4 MeV and a dose of 1016cm-2the for 1 h at room temperature. Plate after exposure was not annealed in order. Hall measurements of the plates before and after irradiation showed that the plates of the single crystals with the GE concentration in the charge corresponding to the proposed method, WES has not changed. Decreased only the mobility of charge carriers. The wafers of single crystal analog markedly decreased both these quantities. These data indicate that the increased radiation resistance of single crystals obtained by the proposed method.

As can be seen from the table, and the results presented in the examples No. 1-4, silicon, fabricated by the proposed method differs from analogues with high values URNS, low variation of resistivity in the cross section of the crystals, the low concentration of defects and has a high thermal stability and radiation resistance.

1. The method of obtaining doped single crystals or polycrystalline silicon by initial preparation of the mixture, its fusion with subsequent crystal growth from the melt, which is optionally enter the group-4 elements of the periodic table, characterized in that the mixture comprises 50% of silicon doped with phosphorus, with electrical resistivity of 0.8-3.0 Ohm·cm, or boron, with specific electrical resistance 1-7 Om·see, as well as al the cops 4 groups of the periodic table use germanium, titanium, zirconium or hafnium in concentrations of 1017-7·1019cm-3.

2. The method according to claim 1, characterized in that the melt is injected together with GE, one of the elements of a number of titanium, zirconium, hafnium.



 

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