Abstract: A method for forming bumps is disclosed. First, a substrate having an adhesive, a barrier, and a wetting layer thereon is provided. Next, a patterned photoresist is formed on the wetting layer, in which the patterned photoresist includes at least one opening for exposing a portion of the wetting layer. Next, a solder is deposited in the opening, and a stripping process is performed to remove the patterned photoresist. Next, a first etchant is utilized to perform a first etching process for etching a portion of the wetting and barrier layers by utilizing the solder as a mask, in which the first etchant is selected from the group consisting of: sulfuric acid, phosphoric acid, ferric chloride, ammonium persulfate, and potassium monopersulfate. Next, a second etchant is utilized to perform a second etching process removing a portion of the adhesive layer, and a reflow process is performed to form a bump.

Abstract: A method of forming a plurality of bumps over a wafer mainly comprises providing the wafer having a plurality of bonding pads formed thereon, forming an under bump metallurgy (UBM) layer over the bonding pads wherein the UBM layer includes an adhesive layer, for example a titanium (Ti) layer or an aluminum (Al) layer, and at least one electrically conductive layer formed on the adhesive layer, removing the portions of the electrically conductive layer located outside the bonding pads, forming a plurality of bumps over the residual portions of the electrically conductive layer disposed above the bonding pads, etching the adhesive layer located outside the bumps, and then reflowing the bumps.

Abstract: A method for forming bumps is disclosed. First, a substrate having an adhesive, a barrier, and a wetting layer thereon is provided. Next, a patterned photoresist is formed on the wetting layer, in which the patterned photoresist includes at least one opening for exposing a portion of the wetting layer. Next, a solder is deposited in the opening, and a stripping process is performed to remove the patterned photoresist. Next, a first etchant is utilized to perform a first etching process for etching a portion of the wetting and barrier layers by utilizing the solder as a mask, in which the first etchant is selected from the group consisting of: sulfuric acid, phosphoric acid, ferric chloride, ammonium persulfate, and potassium monopersulfate. Next, a second etchant is utilized to perform a second etching process removing a portion of the adhesive layer, and a reflow process is performed to form a bump.

Abstract: A method for making UBM (Under Bump Metallurgy) pads and bumps on a wafer is disclosed. Openings are formed in a photoresist layer for forming bumps, a positive liquid photoresist is provided into the openings of the photoresist layer for forming bumps. The positive liquid photoresist is exposed and developed to modify the openings of the photoresist layer. Thus, bumps formed in the modified openings have precise bonding areas on the UBM layer. Using the bumps as a mask, UBM pads under the bumps are formed by etching the UBM layer, so that the reflowed bumps have a uniform height.

Abstract: A method of forming a plurality of bumps over a wafer mainly comprises providing the wafer having a plurality of bonding pads formed thereon, forming an under bump metallurgy (UBM) layer over the bonding pads wherein the UBM layer includes an adhesive layer, for example a titanium (Ti) layer or an aluminum (Al) layer, and at least one electrically conductive layer formed on the adhesive layer, removing the portions of the electrically conductive layer located outside the bonding pads, forming a plurality of bumps over the residual portions of the electrically conductive layer disposed above the bonding pads, etching the adhesive layer located outside the bumps, and then reflowing the bumps.

Abstract: A method for making UBM (Under Bump Metallurgy) pads and bumps on a wafer is disclosed. Openings are formed in a photoresist layer for forming bumps, a positive liquid photoresist is provided into the openings of the photoresist layer for forming bumps. The positive liquid photoresist is exposed and developed to modify the openings of the photoresist layer. Thus, bumps formed in the modified openings have precise bonding areas on the UBM layer. Using the bumps as a mask, UBM pads under the bumps are formed by etching the UBM layer, so that the reflowed bumps have an uniform height.