Direct comparison of ion−damage gettering and phosphorus−diffusion gettering of Au in Si

Abstract

The residual disorder caused by different implanted ions after annealing at elevated temperatures (850−1150 °C) is dependent upon the ion species. The gettering of Au by damaged layers produced by Ar, O, P, Si, As, and B has been quantitatively compared to gettering by phosphorus diffusion. Each individual comparison was made between opposite surfaces of a Si sample by use of Rutherford backscattering. The damage disorder was quantitatively measured by backscattering and structurally studied using electron microscopy. Typically, an ion dose of 10¹⁶/cm² and ion energy of 200 keV were used for implantations. The Au was present in the Si at ’’moderate’’ levels so that solubility in the phosphorus diffused layers was not exceeded. Ar ion−damaged layers were more effective for gettering Au than were phosphorus−diffused layers below ∼1000 °C and equally effective up to 1150 °C. The relative gettering efficiency of the damage produced by other ions studied was less than that of phosphorus diffusion at 1000 °C and was ranked in the order Ar≳O≳P≳Si≳As≳B. In general, the relative gettering efficiency of ion−damaged layers was related to the amount and type disorder after annealing. The initial disorder was of an amorphous nature for 10¹⁶ heavy ions/cm² (As, Si, P, Ar, or O), and the final disorder state was different for different implanted ions after annealing. It is suggested that the disorder (and gettering efficiency) was influenced by size effects of the implanted ion during annealing.