The present invention utilizes a barrier layer in the contact hole to react with an S/D region to form a silicide layer. After forming the silicide layer, a directional deposition process is performed to form a first metal layer primarily on the barrier layer at the bottom of the contact hole, so that very little or even no first metal layer is disposed on the barrier layer at the sidewall of the contact hole. Then, the second metal layer is deposited from bottom to top in the contact hole as the deposition rate of the second metal layer on the barrier layer is slower than the deposition rate of the second metal layer on the first metal layer.