Automated Multifunction system for single crystal growth by Czochralski method (Nika-3)

The multifunctional system NIKA-3 is intended for growth of a wide range of refractory oxide single crystals by the Czochralski method, such as sapphire, yttrium aluminum garnet, lithium tantalate, lithium niobate, gadolinium molybdate, langasite, vanadates of rare-earth metals, bismuth silicate, bismuth germinate and many other.

• The direct drive of pulling head actuator screw with application of step motors of NANOSTEP technology with resolution of 500,000 steps per revolution providing absence of micro-accelerations at low pulling speeds;
• Application of long-stroke (550 mm) disc bellows for rod packing;
• New mechanics of crystal weighing system, significantly decreasing the measurement noise at crystal rotation;
• Software for through automation of the process;
• Equipment is complected with transistor generator (IGBT) with output of 40 or 100 kW.

Melting temperature	up to 2200О С
Crucible diameter	up to 150 mm (depending on the growing crystal type)
Mass of growing crystal	up to 5 kg; 10 kg
Range of weight sensor measurement	up to 5 kg; 10 kg
Sensitivity of weight sensor	min. 0.02 g; 0.04 g
Operational stroke of upper rod	550 mm
Rate of upper rod movement:
operational	from 0.1 to 120.0 mm/h
accelerated	from 0.5 to 150.0 mm/min
Rate of upper rod rotation	1-100 rpm
Operational stroke of lower rod	200 mm
Type of converter	transistor (IGBT technology)
Output power of converter	40 kW; 100 kW
Range of frequency converter output power application	from 1 to 100 % of the applied one
Efficiency	min. 93%
Permissible deviation of frequency converter output power from the specified value	± 0,05%
Inert gas pressure in chamber	max. 1,5x105Pa
Limit primary vacuum in the growing vessel with the inducer switched off	max. 2.6 Pa
Consumed power of the installation (without frequency converter)	max. 3 kW
Cooling water pressure	from 200 kPa to 250 kPa

The adaptive (self-adjusting) system of automatic control over the crystal diameter provides for the necessary amount of control and stability throughout the whole growth process. The significant advantage of the ACS is availability of several classes of automatic regulators, such as self-adjusting PID-regulator, incremental regulator, self-adjusting predictor-corrector which, as the practice has shown, provides for the best quality of crystal size (ingot diameter) control. We take into consideration the features of the customer’s process and carry out automation of special processing methods and procedures.

 

We take into consideration the features of the customer’s process and carry out automation of special processing methods and procedures.

 

EZAN develops and implements the top-level automation systems intended for single crystal growth shop production management. The system performs the automatic collection and processing of the technological parameters, the single crystal quality analysis results, performs automatic correlation, determines the combination of optimal technological parameters for the current process, downloads them to the system control computer.