Semiconductor device with metal silicide layer and method for manufacturing the same

A semiconductor device, comprising:

• a first electrode;
• a second electrode;
• a semiconductor layer provided between the first electrode and the second electrode, having a first face facing the first electrode and a second face facing the second electrode, and containing silicon (Si);
• a first semiconductor region of n-type provided in the semiconductor layer;
• a second semiconductor region of p-type provided in the semiconductor layer and disposed between the first semiconductor region of n-type and the first face;
• a third semiconductor region of n-type provided in the semiconductor layer and disposed between the second semiconductor region of p-type and the first face;
• a gate electrode provided on the first face side of the semiconductor layer and facing the second semiconductor region of p-type;
• a gate insulating layer provided between the second semiconductor region of p-type and the gate electrode;
• and
• a metal silicide layer provided between the first electrode and the second semiconductor region of p-type and between the first electrode and the third semiconductor region of n-type, including a top surface in contact with the first electrode, a first bottom surface in contact with the third semiconductor region of n-type, and a first side surface in contact with the third semiconductor region of n-type, and containing at least one metal element selected from a group consisting of gold (Au), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt),
• wherein, in a first direction from the first electrode toward the second electrode, an n-type impurity concentration in the third semiconductor region of n-type monotonically decreases from the first bottom surface toward the second electrode,
• the first semiconductor region of n-type contains the at least one metal element,
• the semiconductor layer is single crystal silicon (Si), and
• a thickness of the metal silicide layer in the first direction is equal to or more than 10 nm and equal to or less than 40 nm.