SU108648A1 - Method for automatic control of the process of growing single crystals from a melt by extrusion (according to Czochralski) - Google Patents

Description

In the overwhelming majority of cases, the growth of crystals is carried out without the use of any complex regulatory cxieiM, and the question of the standardization of crystals has not been successfully resolved. The automatic control of the process of growing single crystals from a melt has significant advantages® using none of the existing methods.

The automatic regulation of the process simplifies the process of obtaining single crystals of 1 of the melt, releasing at this part of the service; allows to obtain strictly permeable on the property) M single crystals with an identical amount of initial materials (Materials; simplifies in many cases the subsequent mechanical processing of single crystals, allows you to grow them with exact sizes; allows | I et to carry out the extraction of p1 distribution of impurities (and neither on the properties of the crystal) under any reproducible crystallization conditions, which helps the fast processing of the necessary regimes to create high quality crystalline triodes.

It is known that the physical properties of crystals depend on the nature of the prg mei entering the crystal, as well as on the nature of its distribution in the crystal. The pattern of distribution of the impurity depends on the nature of the change in the rate of crystallization. The geometrical form of the crystal and the distribution of 1me.h1anicheskih voltages in us depend on the same procedure. In its turn, the speed of the inter- or inter-borrowing depends on the nature of heat transfer at the interface between the liquid and solid phases. The nature of heat transfer depends mainly on the temperature of the heater, on the change in the intensity of the cooling of the crystal as it grows, on the position of the melt level relative to the heater and on the change in the amount of melt as the crystal is drawn.

№ -108648

The effect of changes in the nature of heat transfer at the interface, and, consequently, the rate of crystallization, the caiM crystal best feels, changing its transverse times, the measures and the position of the phase separation interface. If Tenlovtzad becomes more intaih, the crystal diameter increases, and the phase boundary descends into a hundred of melt, and vice versa. The method of automatic regulation of the process of growing m01nocr |; -1stars from a melt serves to obtain production (physical and physical properties (and the geometrical form of mo | Nycrystals.

In this way, the speed, crystallization rate can be reduced to the automaton, automatisation, crystallization of the crystallization rate, the crystal ditch and the position of the border. Such regulation can be carried out using the absorption of the direct beam of radio1IV1 radiation 1 or neutron, depending on the conditions of crystallization and the nature of the substance to be crystallized. The drawing shows the automatic regulation of the single crystals from the melt using the method of extrusion with the admission of the emission of Pa1D1ioactive isotopes.

From the source / radioactive (radiation, having passed through the cooled steel walls 2 of the apparatus, thinned in this place, the openings of the screens and the heater .3, the walls of the crucibles 4, and the melt-crystal interface 5, falls into the AM.wick 6 radio of active radiation.

The received receiver signal is an EoTactric signal, depending on the amount of absorption in the crystal and the melt region, and is formed and amplified by block 7 and transmitted via cable to the input of the electronic converter S, where cf is derived from signals received from an additional device .

An additional device, which is a reference part of the circuit, consists of a radioactive source 9, similar to source 1, an absorber wedge 10 with an arrow, a radiation receiver //, similar to receiver 5, and a shape-ring unit 12.

The difference signal must be modulated, amplified and fed to the actuator /, which changes the position of the core and the ion-ion ion coil 14, which is the sensor of the telemetry system of the secondary device / 5, acting either on the adjusting heating matrix or on the speed of crystal extraction , l / for that and another at the same time. The required diameter of the crystal is set down during the process once by the handle 16 by inserting a specially prepared reference sample 1 10 and is measured on a scale of / 7.

When a clip is drawn out before the onset of crystallization, the difference signal of that IL1I of a different sign acts on: 1 mechanism, (() forced the system to return to the wound by (changing the nature of heat exchange at the melt-crystal interface.

i Using such a device, one can carry out p | eguliro: vapie according to the progrgme's task, remove crystal of any smooth forums, or use it for reproducible production of electric, n-dryrochny (P-n) transitions of the desired quality in semiconductors. To do this, instead of a wedge 10, you need to insert either a crystal of the same substance, but 31a (of this form, or a specially selected (by density) radiation absorber of source 5; then, moving the specified reference forward, you should continuously rotate the crystal or absorber with a speed equal to the speed of drawing a single crystal by means of a drive with a gearbox 18. Any successfully obtained crystal 1 can be a further standard for obtaining a large number of similar crystals.

Subject matter

The method of automatic adjustment of monocrystals proceeding from a melt by the method of stretching (according to Czochralsk), which is controlled by the fact that the nature of heat exchange at the interface between the phases, and subsequently, and the rate of crystallization, is carried out by continuously controlling the diameter of the the crystal by changing the nature of the absorption of radioactive radiation in the crystal and its continuous comparison with the standard, followed by: the effect of M on the temperature: the furnace mode or cKOpoicTb extraction.