Carbon re-incorporation in phosphorus-doped Si1−yCy epitaxial layers during thermal annealing

The carbon-incorporation behavior in phosphorous-doped Si1−yCy/Si (y1 ∼ 0.018, y2 ∼ 0.024) epilayers grown by reduced pressure chemical vapor deposition (RPCVD) has been investigated as a function of annealing temperatures. An abnormal interstitial carbon (Ci) re-incorporation was observed in the initial stage of thermal annealing, introducing an additional tensile strain into the Si1−yCy epilayers. At higher temperature but below β-SiC precipitation threshold, almost complete strain relaxation was found. These strain transitions can be attributed to the competitive behavior between Ci re-incorporation and phosphorus deactivation to kick out the substitutional carbon (Csub) atoms during the post-annealing process. This work demonstrated that Si1−yCy epilayers grown by RPCVD could keep both enhanced carbon incorporation and nonequilibrium phosphorus activation if the thermal budget is well controlled.

► An abnormal strain enhancement was observed in the initial stage of annealing. ► Almost complete strain relaxation was found below β-SiC precipitation threshold. ► The strain transition can be explained by Ci re-incorporation and P deactivation. ► Si1−yCy could reach a maximal strain value if thermal budget is well controlled.