The amounts of argon ions trapped during ion beam sputtering deposition, at room temperature, of thin amorphous films of YBaCuO are studied as a function of the sputtering angles with respect to the normal to the target. Experimental results show that the angular distribution of Ar is strongly peaked in the forward direction and is explained by the overlap of two mechanisms : scattering at the surface of the target followed by implantation in the growing film of the Ar primary ions. Sputtering of Ar first caused implantation in the target