JVD's main innovation is a novel vapor source: a sonic jet of inert gas in "low" vacuum, ~ 1 torr pressure that transports condensable atoms, molecules, or clusters from a nozzle to a substrate. The jet deposits these species efficiently in a small area, less than the size of a dime. Larger areas, an 8" wafer for example, are coated by imposing a relative 2D motion between substrates and one or more jet sources. This combination of jet sources and relative motion gives JVD great versatility.
A generalized jet source is seen in Figure 1. We have designed a number of jet sources based on different vaporization mechanisms inside the nozzle. A jet source is typically a 3" diameter cylindrical nozzle, with an end plate exit orifice ~ 1 cm in diameter. Ultra high purity Helium or Argon is supplied to the nozzle and exits from it as a jet. Ordinarily, the nozzle pressure Pn is several torr, and the downstream pressure Pd is a torr or less, but the range is wide; in different applications both pressures can be higher or lower. If the ratio Pn/Pd > 2, the flow is "critical", and the jet emerges at the speed of sound, ~105 cm/sec for He. This high purity, high speed gas flow is driven only by mechanical pumps and blowers, a robust technology with fast startup times.
These jet sources are the basis of multiple jet, moving substrate processes for depositing metals, semiconductors, dielectrics, and organics, as well as oxides and nitrides in a "reactive" mode. All these materials can be grown by JVD in different forms: "atomistic" or "nanocluster", multiple-layers, multi-component alloys, and "host-guest" films. Figure 2 and Figure 3 show the relative motion schemes permitting single wafer and batch processing, and Figure 4 shows an example of a complex, multi-layer material. In addition to solder deposition, JVD's range of materials and applications are reviewed in Chapter 18 of the Handbook of Deposition Technologies for Films and Coatings, Third Edition, edited by Peter M. Martin.
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