Efficiency and thermal stability of Pt gettering in crystalline Si

Abstract

We have investigated the efficiency and the thermal stability of Pt gettering at different sites in crystalline Si. In particular, we compared the gettering performances of heavily n-type doped regions formed by P diffusion, cavities formed after high-temperature annealings of He implanted Si, and damage induced by ion implantation of B, C, or Si. These sites were introduced on one side of wafers containing a uniform Pt concentration in the range 1×1013–5×1014 atoms/cm3. The uniform concentration of Pt was attained by means of Pt implantation followed by a high-temperature thermal process. The gettering efficiency of the different sites was monitored during thermal processes at 700 °C for times ranging from 1 to 48 h. Thermal stability of gettering was investigated with a subsequent thermal process in the temperature range 750–900 °C during which part of the gettered Pt is released in the bulk of the wafer. The kinetics of Pt gettering at the different sites is found to be similar since it is fully dominated by the kick-out diffusion mechanism of the metal impurity. The thermal stability is instead site-dependent and can be described in terms of an effective binding enthalpy of 1.9, 2.6, and 3.0 eV between Pt atoms and cavities, P-doped region, and ion-implantation damage, respectively. The physical meaning of the binding enthalpy is investigated and discussed.

Gettering of Diffused Au and of Cu and Ni Contamination in Silicon by Cavities Induced by High Energy He Implantation

“…Dissolved in the silicon bulk, these impurities can strongly reduce the minority carrier diffusion length. This socalled proximity gettering has been carried out in Si [3,4] by implantation at various energies of different kinds of ions (C , Si etc . The building of a more favorable impurity trapping zone (gettering zone), in a non-active area at the back side of the wafers, by phosphorus diffusion, by introducing near surface defects or by Al/Si alloying has been routinely used to avoid such effects [2].…”

Evolution Of Defects Induced By High Energy He Implantation In Gold-Diffused Silicon

“…With the size reduction of the device structure, it is more and more interesting to create very localised gettering zones at, or just below, the active zone. This so-called proximity gettering have been carried out in Si [3,4] by implantation of different kind of ions (C + , Si + etc…) but there is also a great deal of interest in He or H implantation [5][6][7]. In silicon, He and H segregate into small gas-vacancy complexes which favor bubbles or cavity formation depending on the implantation and on the subsequent heat treatment conditions [8].…”

The influence of diffusion temperature and ion dose on proximity gettering of platinum in silicon implanted with alpha particles at low doses

“…Hereby impurities may be trapped by voids, 1,2 stacking faults, 3 dislocations, 4 or other defects. 5 However, in carrier lifetime engineering the accumulation of impurities can also be desired. Proximity gettering of platinum 6,7 can thus create a localized region of reduced carrier lifetime since platinum is acting as a so-called ''lifetime killer.''…”