Silicide implants

A method, comprising:

• providing a substrate with a source/drain region comprising an epitaxial stack;
• forming a dielectric over the epitaxial stack;
• forming a contact opening in the dielectric to expose the epitaxial stack in the source/drain region;
• and
• forming a metal-containing amorphous layer in a top portion of the epitaxial stack, wherein forming the metal-containing amorphous layer comprises:
• generating metal ions from a metal target;
• accelerating the metal ions towards the epitaxial stack through the contact opening by adjusting a bias voltage applied to the substrate, wherein the accelerated metal ions penetrate the epitaxial stack and disrupt a crystalline structure of the top portion of the epitaxial stack to form the metal-containing amorphous layer
• and deposit a metal layer in the contact opening;
• and
• modulating a thickness of the metal-containing amorphous layer based on the bias voltage applied to the substrate;
• and
• after forming the metal-containing amorphous layer, performing an anneal to form a silicide from the metal layer and the metal-containing amorphous layer.

A method comprising:

• providing a substrate with a source/drain region comprising an epitaxial layer;
• depositing a dielectric layer over the source/drain region;
• etching the dielectric layer to form a contact opening in the dielectric layer to expose a portion of the source/drain region;
• depositing a metal layer in the contact opening to form an amorphous layer in a top surface of the epitaxial layer, wherein the amorphous layer is interposed between the deposited metal layer and the epitaxial layer and comprises a metal;
• depositing a barrier layer over the metal layer;
• and
• after depositing the barrier layer, annealing the substrate to form a silicide between the barrier layer and the epitaxial layer, wherein the amorphous layer is consumed to form a portion of the silicide.