FLASH EVAPORATION FOR HIGH PURITY THIN FILMS
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
In the metallized ceramic polyimide (MCP) process, a thin film of chromium (Cr) or Cr/copper (Cu) blend was found to improve bonding of the Cu to the polyimide. In order to avoid via resistance reliability problems, a high purity film is required. The high rate deposition normally associated with this method is conducive to the fulfillment of these requirements. Low rate blend evaporation from a single source is inadequate because a partitioning is caused by a difference in vapor pressures of the species. In order to maintain a uniform composition throughout metal film, the components must arrive at surface in the proportion of the desired blend. In multisource evaporation, this is accomplished by the controlled evaporation from individual sources.