Characterisation of Cr intermediate layers in Cu–C-system with SIMS method

In the design of new high speed chip generations, the greatest problem is to bleed off process heat during their operation. The installation of heat sinks onto such chips is necessary. A copper–carbon (Cu–C) composite is one possible material. It combines high thermal conductivity with low density and tailorable coefficient of thermal expansion (CTE). Because of low wettability of carbon by copper, a thin layer of chromium (Cr) has to be deposited first to contact copper with the carbon fibers. The optimization of processing parameters was done on vitreous carbon substrates (Sigradur G) as a model for carbon fibers. Onto these substrates, 2 nm chromium and 1 μm copper were deposited. In the later serial fabrication of the composite, a hot pressing step will follow the deposition, which is simulated with a heat treatment of the compound. Secondary ion mass spectrometry (SIMS) investigations were done to obtain information on the depth distribution of the main elements copper, chromium and carbon. Two samples, one as deposited and one subjected to a heat treatment after deposition are compared in this investigation.