Linton Crystal Technologies (LCT) recently applied for a U.S. Letters Patent for its Dynamic Balancing Seed Lift. Patent Application 17/716,487 is the most recent Linton has made to the USPTO for innovations related to the seed lifting and rotating mechanism. The company recently received a patent for its Seed Lifting and Rotating System for Use in Crystal Growth.
“Linton continues to develop solutions for pulling longer and heavier crystals in keeping with emerging industry standards in both solar and semiconductor,” explains Todd Barnum, president and COO of Linton. “Demand for larger ingots has grown in recent years and these larger crystals have created new challenges in the design of growth furnaces. Our engineers are constantly designing ways to maintain crystal quality in the face of these challenges.”
Typically, silicon crystal growing furnaces use a seed crystal suspended above a melt of silicon within the furnace. This seed crystal is lowered to contact the melt, then lifted and rotated in a controlled process via a cable winch system – the seed lift assembly—to grow an ingot of crystallized silicon. Most traditional seed lift mechanisms have a grooved spool that wraps and gathers the seed cable, lifting the crystal. The spool must translate side to side to keep the gathering cable centered to a pulley, which in turn is centered on the growth chambers. Movement of the spool and rotation of the seed lift assembly induce deviations in the center of mass of the seed lift assembly with respect to its axis of rotation, which can cause undesired movement of the cable and thus seed crystal. Any such disturbances can cause defects in the ingot, including its loss of structure. While the ingot can be remelted and regrown, this process is costly.
Linton’s Dynamic Balancing Seed Lift permits the seed lift assembly to operate at a higher level of precision. A dynamic counterweight system uses sensors to detect movement of the seed lift assembly and software controls a motor-driven, movable counterweight to offset these deviations to maintain the center of mass at, or substantially in line with, the axis of rotation. The Dynamic Balance also includes machine monitoring instrumentation for operator and software feedback.
The Dynamic Balancing Seed Lift is available as an option on Linton’s CZ crystal growers at the time of manufacture. Its ease of installation also makes it especially suitable for retrofits.
Linton is the world leader in the design, development and manufacture of equipment for producing monocrystalline ingots for the solar and semiconductor industries. The company specializes in silicon and produces equipment for materials such as germanium and gallium arsenide. They also provide technical support, process engineering support and replacement parts to help clients get businesses off the ground, improve productivity and continue to innovate. Linton has been the exclusive owner of Kayex technology since 2013.