Gold diffusion method for semiconductor devices of high switching speed

A method of fabricating a semiconductor device capable of high-speed switching operation, which method comprises:

• (a) providing a semiconductor substrate comprising a first region of a first conductivity type exposed at part of a first of a pair of opposite main faces of the substrate, and a second region of a second conductivity type, opposite to the first conductivity type, disposed contiguous to the first region and exposed at the first main face of the substrate so as to surround the first region, the first and second regions creating a pn-junction therebetween;
• (b) forming an insulating covering on the first main face of the semiconductor substrate, the insulating covering having an aperture exposing part of the first semiconductor region;
• (c) forming a layer of gold at least on that part of the first semiconductor region which is exposed through the aperture in the insulating covering;
• (d) causing the diffusion of gold from the gold layer into the semiconductor substrate by heating the semiconductor substrate, with the insulating covering formed thereon, to a first predetermined temperature;
• (e) removing the remaining gold layer from the exposed surface of the first semiconductor region;
• (f) activating the diffused gold by heating the semiconductor substrate to a second predetermined temperature that is higher than the first predetermined temperature;
• and
• (g) forming an electrode in electrical connection to the first semiconductor region.

A method of fabricating a semiconductor device capable of high-speed switching operation, which method comprises:

• (a) providing a semiconductor substrate comprising a first region of a first conductivity type exposed at part a first of a pair of opposite main faces of the substrate, and a second region of a second conductivity type, opposite to the first conductivity type, disposed contiguous to the first region and exposed at the first main face of the substrate so as to surround the first region, the first and second regions creating a pn-junction therebetween, the semiconductor substrate having an insulating covering on the first main face of the semiconductor substrate, the insulating covering having an aperture exposing part of the first semiconductor region;
• (b) forming a layer of gold at least on that part of the first semiconductor region which is exposed through the aperture in the insulating covering;
• (c) causing the diffusion of gold from the gold layer into the semiconductor substrate by heating the semiconductor substrate, with the insulating covering formed thereon, to a first predetermined temperature;
• (d) removing the remaining gold layer from the exposed surface of the first semiconductor region;
• (e) activating the diffused gold by heating the semiconductor substrate to a second predetermined temperature that is higher than the first predetermined temperature;
• and
• (f) forming an electrode in electrical connection to the first semiconductor region.