A rotating pocket heater, also called pocket heater or Kinder heater, holds and rotates a substrate during

vacuum deposition Vacuum deposition is a group of processes used to deposit layers of material atom-by-atom or molecule-by-molecule on a solid surface. These processes operate at pressures well below atmospheric pressure (i.e., vacuum). The deposited layers can r ...

. During rotation, the substrate is sequentially exposed to more than one environment, for example, heat, oxygen, metal vapor, etc. Rotating pocket heaters has been used in reactive evaporation system to create YBa2Cu3O7 layers on planar semiconductor wafers.

Magnesium diboride

The illustration on the right shows an example of a pocket heater being used to deposit a layers of

magnesium diboride Magnesium diboride is the inorganic compound with the formula MgB2. It is a dark gray, water-insoluble solid. The compound has attracted attention because it becomes superconductor, superconducting at 39 K (−234 °C). In terms of its ...

on a substrate. A vertical shaft (32) turns a horizontal disk (30) several hundred rotations per minute (RPM). The illustration shows two of several substrates (14) attached to the underside of the rotating disk. The substrates are attached at their edges, so that most of the undersides of the substrates are exposed to the vapor below. The entire apparatus is enclosed in a chamber kept at low pressure by a vacuum pump. Magnesium diboride (MgB₂) is an ionic solid with superconducting properties. Vapor deposition is difficult, because the vapor pressure of magnesium is much higher than boron. The pocket heater solves this problem by providing a separate environment for each material.

Spying charge

In May 2015,

FBI The Federal Bureau of Investigation (FBI) is the domestic Intelligence agency, intelligence and Security agency, security service of the United States and its principal Federal law enforcement in the United States, federal law enforcement age ...

agents arrested Professor

Xiaoxing Xi Xiaoxing Xi (; born 1957) is a Chinese-born American physicist. He is the Laura H. Carnell Professor and former chair at the Physics Department of Temple University in Philadelphia. In May 2015, the United States Department of Justice arrested hi ...

, chairman of

Temple University Temple University (Temple or TU) is a public state-related research university in Philadelphia, Pennsylvania. It was founded in 1884 by the Baptist minister Russell Conwell and his congregation Grace Baptist Church of Philadelphia then called Ba ...

's physics department, accusing him of sharing schematics of a pocket heater with Chinese scientists. The prosecutors dropped all charges in September 2015 after it was shown that they had misconstrued the evidence and Xi has never shared the diagram of the pocket heater with anyone in China. Rotating pocket heater is not a restricted technology and was first invented by German physicists Berberich, Prusseit, and Kinder. Theva Dunnschichttechnik GmbH of Germany holds the patent for pocket heater.

References

{{reflist Thin film deposition