Modeling of the target surface modification by reactive ion implantation during magnetron sputtering

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Abstract
The erosion rate of an aluminum target bombarded with Ar+ and O2+ ions was simulated using TRIDYN. An abrupt change of the erosion rate is noticed at a critical mole fraction of O2+ ions. This target behavior can also be described by a simple analytical model showing that the abrupt change finds its origin in an avalanche induced by reaction ion implantation. Indeed, by the reduction of the average sputter yield by compound formation, more reactive ions become implanted into the target as the number of implanted ions depends inversely on the average sputter yield. As such, an avalanche situation can develop which finally results in a completely oxidized target. It is also shown that the critical mole fraction depends linearly on the sputter yield of the target material and that target poisoning induced by ion implantation can result in a hysteresis behavior for the target condition.