Powering furnaces for crystal growing

Our customer is active in the industry of crystal growing using the Czochralski method. This process allows to produce the basic core materials for the production of semiconductors, microchips, photovoltaic cells and many more high-tech components.

About the Czochralski method

At the beginning of the process, the feed material is placed into a cylindrically shaped crucible. The substance will be heated to hundreds of degrees until it reaches its melting point. In order to heat the furnace, a reliable power supply is needed. After the feed material is completely molten, a seed crystal of few millimeters is dipped into the melt surface. The seed crystal’s rod is slowly pulled upwards and rotated simultaneously. During the growth process, the heating power, the pulling rate and the rotation rate are controlled to extract a large, single-crystal, cylindrical ingot.

The customer’s site counts a series of this kind of furnaces. Some of them are already equipped with a JEMA power supply. One of the furnaces reached its end of life and had to be replaced. The power supply from another supplier was made of two separate cabinets: one being for the transformer and one for the power & control cabinet. Therefore, our customer was looking for a reliable and efficient 50VDC – 2000A power supply. Moreover, the solution had to provide a very stable output. An unstable output current or voltage would lead to impurities and imperfections in the growth process resulting in discarding a costly piece of processed ingot.

JEMA has designed, developed and manufactured a fully customized cabinet delivering 50VDC – 2000A meeting customer’s requirements and beyond.

We provided a control and regulation system that receives the voltage and current settings required for the process. This works as a permanent control loop where the required customer’s parameters are constantly measured and steered if necessary.

Our double star transformer-rectifier converts the three-phase AC power from the grid into a clean and stable DC power supply.

The DC output is precisely measured by current and voltage measuring devices which send the information to a JEMA designed control card.

This card allows the output current to be adjusted according to the customer’s requirements. To do this, the control card constantly sends its regulation signals to the JEMA designed thyristor driver card. This card controls the thyristors and thus adapts the amount of current and voltage supplied by the transformer-rectifier.

Not only did we supply a 50VDC – 2000A cabinet, but we also designed it to fit existing AC and DC power connections. In addition, our engineering team developed a single cabinet instead of two, which reduced the space required at our customer’s premises. Our in-house design and production of the transformer and coils contributed to a compact design. All this leads to a reduction in costs because the system is simpler and better adapted to the existing installation.

The thyristor topology results in a reliable and cost-effective installation that brings performance to our customer and his process. Previous power supply installations and the recent installation of a new power supply show their confidence in the solutions and services that JEMA has to offer.