ANNEALING BEHAVIOR OF FINE-GRAINED ELECTROLESS COPPER-DEPOSITS

An investigation was conducted to examine the low temperature (<300-de grees-C) annealing behavior of two types of fine-grained electroless c opper deposits. Heat-treatment from continuous oven-annealing was comp ared to that from thermal cycling in a fluidized sandbath (FSB) unit. It was found that one of the deposits, referred to as type IV electrol ess copper, showed considerable resistance to recrystallization. Micro scopic and chemical analyses indicated that this electroless copper co ntained a high density of organic inclusions which were effective in p inning grain boundary movement and preventing recrystallization. Type IV electroless cop er also had high gaseous hydrogen content. The FSB experiments showed that this entrapped hydrogen could induce a local p lastic deformation mechanism and cause internal fatiguing in the coppe r during thermal cycling. The other deposit, referred to as type I ele ctroless copper, was relatively free of foreign incorporation. This co pper recrystallized readily upon annealing. The driving force for grai n growth was the surface energy released from elimination of grain bou ndaries.