Etchant and method for forming bumps
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.
1. A method for forming bumps, comprising:
providing a substrate having an adhesive layer, a barrier layer, and a wetting layer thereon;
forming a patterned photoresist on the wetting layer, wherein the patterned photoresist comprises at least one opening for exposing a portion of the wetting layer;
depositing a solder in the opening;
performing a stripping process to remove the patterned photoresist;
utilizing a first etchant to perform a first etching process for removing a portion of the wetting layer and the barrier layer by utilizing the solder as a mask, wherein the first etchant comprises sulfuric acid, phosphoric acid, ferric chloride, and ammonium persulfate;
utilizing a second etchant to perform a second etching process and remove a portion of the adhesive layer; and
performing a reflow process to form a bump.
2. The method of claim 1 , wherein the substrate comprises a wafer.
3. The method of claim 1 further comprising:
disposing at least one bonding pad on the substrate, wherein the bonding pad electrically connects the circuits within the substrate; and
forming a patterned passivation layer on the substrate for exposing a portion of the bonding pad.
4. The method of claim 3 , wherein the opening is located above the bonding pad.
5. The method of claim 1 , wherein the adhesive layer is selected from the group consisting of aluminum, titanium, chromium, and titanium tungsten.
6. The method of claim 1 , wherein the barrier layer is selected from the group consisting of nickel and nickel vanadium.
7. The method of claim 1 , wherein the wetting layer is selected from the group consisting of copper, molybdenum, and platinum.
8. The method of claim 1 , wherein the second etchant is consisting of sulfuric acid and deionized water.
9. A method for forming bumps, comprising:
providing a substrate having an adhesive layer, a barrier layer, and a wetting layer thereon;
forming a patterned photoresist on the wetting layer, wherein the patterned photoresist comprises at least one opening for exposing a portion of the wetting layer;
depositing a solder in the opening;
performing a stripping process to remove the patterned photoresist;
utilizing a first etchant to perform a first etching process for removing a portion of the wetting layer and the barrier layer by utilizing the solder as a mask, wherein the first etchant comprises sulfuric acid, phosphoric acid, ferric chloride, and potassium monopersulfate;
utilizing a second etchant to perform a second etching process and remove a portion of the adhesive layer; and
performing a reflow process to form a bump.
10. The method of claim 9 , wherein the substrate comprises a wafer.
11. The method of claim 9 further comprising:
disposing at least one bonding pad on the substrate, wherein the bonding pad electrically connects the circuits within the substrate; and
forming a patterned passivation layer on the substrate for exposing a portion of the bonding pad.
12. The method of claim 11 , wherein the opening is located above the bonding pad.
13. The method of claim 9 , wherein the adhesive layer is selected from the group consisting of aluminum, titanium, chromium, and titanium tungsten.
14. The method of claim 9 , wherein the barrier layer is selected from the group consisting of nickel and nickel vanadium.
15. The method of claim 9 , wherein the wetting layer is selected from the group consisting of copper, molybdenum, and platinum.
16. The method of claim 9 , wherein the second etchant is consisting of sulfuric acid and deionized water.