Methods of electroless deposition of nickel, methods of forming under bump metallurgy, and constructions comprising solder bumps

A method of electroless deposition of nickels, comprising:

• providing a substrate having an upper surface comprising a first material;
• the first material predominantly comprising aluminum or copper;
• forming a titanium-containing material over the first material;
• forming a palladium-containing material over the titanium-containing material;
• and
• electroless depositing nickel on the palladium-containing material.

A method of electroless deposition of nickel over aluminum-containing materials and copper-containing materials, comprising:

• providing a first substrate and a second substrate in a common semiconductor fabrication facility;
• the first substrate having a copper-containing material, and the second substrate having an aluminum-containing material;
• forming a titanium-containing material over the aluminum-containing material of the second substrate;
• exposing the first substrate to a first palladium-containing solution to form a first palladium-containing layer over the copper-containing material;
• exposing the second substrate to a second palladium-containing solution to form a second palladium-containing layer over the titanium-containing material;
• electroless depositing nickel on the first palladium-containing material to form a first nickel-containing material on the first palladium-containing material;
• and
• electroless depositing nickel on the second palladium-containing material to form a second nickel-containing material on the second palladium-containing material.

A method of forming a solder bump over an aluminum-containing material, comprising:

• forming a titanium-containing material over the aluminum-containing material;
• forming a patterned mask over the titanium-containing material;
• the patterned mask comprising polyamide or a BCB material, and having an opening extending therethrough to the titanium-containing material to expose a portion of the titanium-containing material;
• forming a palladium-containing material on the exposed portion of the titanium-containing material;
• electroless depositing a nickel-containing material on the palladium-containing material;
• forming a gold-containing material on the nickel-containing material;
• and
• forming a solder bump over the gold-containing material.