Methods of forming semiconductor devices using electrolyzed sulfuric acid (esa)

A method of forming a semiconductor device, the method comprising:

• forming a gate on a silicon substrate, wherein the gate includes a gate insulating layer on the silicon substrate and a gate electrode on the gate insulating layer, and wherein the gate electrode includes a layer of a first metal on the gate insulating layer;
• forming source/drain regions in the silicon substrate on opposite sides of the gate;
• forming a second metal layer on at least one of the source/drain regions, wherein the first and second metal layers comprise different metals;
• reacting the second metal layer with the at least one of the source/drain regions to form a metal silicide on the at least one of the source/drain regions;
• and
• after reacting the metal layer, removing unreacted residue of the second metal layer using an etching solution wherein an etch rate of the second metal layer with respect to the etching solution is significantly greater than an etch rate of the first metal layer with respect to the etching solution.

A method of forming a semiconductor device, the method comprising:

• forming a gate on a substrate, wherein the gate includes a high-k dielectric layer on the substrate and a metal gate electrode on the high-k dielectric layer;
• forming source/drain regions on the substrate on opposite sides of the gate;
• forming a metal layer on at least one of the source/drain regions;
• reacting the metal layer with the at least one of the source/drain regions to form a metal silicide on the at least one of the source/drain regions;
• and
• after reacting the metal layer, removing unreacted residue of the metal layer using electrolyzed sulfuric acid solution.

A method of forming a semiconductor device, the method comprising:

• forming a gate on a silicon substrate;
• forming insulating spacers on sidewalls of the gate;
• forming source/drain regions in the silicon substrate on opposite sides of the gate;
• forming a metal layer on at least one of the source/drain regions;
• performing a first thermal treatment to form a metal silicide on the at least one of the source/drain regions;
• after reacting the metal layer, removing unreacted residue of the metal layer using electrolyzed sulfuric acid solution;
• after removing unreacted residue, performing a second thermal treatment at a temperature exceeding a maximum temperature of the first thermal treatment;
• and
• after performing the second thermal treatment, cleaning a surface of the semiconductor device including the metal silicide using aqua regia.

A method of forming a semiconductor device, the method comprising:

• forming a metal layer on a silicon portion of a substrate;
• reacting the metal layer with the silicon portion to form a metal silicide;
• and
• after reacting the metal layer, removing unreacted residue of the metal layer using electrolyzed sulfuric acid solution, wherein a volume of sulfuric acid in the electrolyzed sulfuric acid solution is in the range of about 70% to about 95% of the total volume of the electrolyzed sulfuric acid solution, wherein a concentration of oxidant in the electrolyzed acid solution is in the range of about 7 g/L to about 25 g/L, and wherein a temperature of the electrolyzed sulfuric acid solution is in the range of about 130 degrees C. to about 180 degrees C.