Kayex Automated Closed-Loop Controls System

Closed-Loop Process Control Utilized within the control loops, the proportional, integral, and derivative (PID) values are driven by a unique control algorithm that was specifically designed by Kayex to enable control of specific crystal growth parameters. The incorporation of these three value elements results in a control system that anticipates crystal growth variations and takes corrective action before they occur.

The Kayex Automated Closed-Loop Controls System utilizes a DOS-based industrial computer and a touch-sensitive interface to provide maximum control over the entire crystal growing process. Sophisticated closed-loop measuring and control devices enhance grower productivity by producing consistent, repeatable crystal growths. The controls system further reduces labor costs by decreasing amount of human operators needed to effectively run a crystal growing manufacturing facility.

Programmed SOP Tables

• Sets specific parameters of crystal growth to pre-determined optimal specifications.
• Saves programs for future crystal growths.

Melt Level Temperature Control Loop

• Monitors melt temperature. If temperature is not optimal, controller signals power supply to adjust accordingly.
• Once optimum melt temperature is determined, control system calibrates that temperature as starting point for future growths – reduces possibility of operator error.

Dip Sensor System

• Senses moment when seed touches silicon melt and begins growth process – operator no longer needed for this task.

Heater Temperature Control Loop

• Monitors heater temperature against heater set point. If corrective action is necessary, controller signals power supply to adjust accordingly.
• Measures actual heater temperature instead of kW output – more reliable measurement because heater variations and aging do not affect temperature reading.

Growth Control Loop

• Heater pyrometer monitors the temperature and compares the desired diameter set point to the average growth rate (pull speed). If corrective action is necessary, controller signals power supply and seed lift motor to adjust accordingly.

Diameter Control Loop

• KrystalVision™ camera continuously measures crystal diameter and sends signal to controller. If corrective actions are necessary, controller sends signal to seed lift motor to adjust accordingly.
• High update rate (measurements taken per second) provides accurate data.

Melt Level Control Loop

• Vertical motion of crucible lift and seed lift maintains melt level position, relative to heater(s).

Pressure Control Loop

• Compares internal chamber pressure level to furnace tank gauge reading. If corrective actions are necessary, controller signals throttle valve position to be adjusted accordingly.