METHOD FOR MANUFACTURING FINE-PITCH BUMPS AND STRUCTURE THEREOF
A method for manufacturing fine-pitch bumps comprises providing a silicon substrate; forming a titanium-containing metal layer having a plurality of first zones and a plurality of second zones on the silicon substrate; forming a photoresist layer on the titanium-containing metal layer; patterning the photoresist layer; forming a plurality of copper bumps having a plurality of first top surfaces and a plurality of first ring surfaces; heating the photoresist layer to form a plurality of body portions and removable portions; etching the photoresist layer; forming a plurality of bump protection layers on the titanium-containing metal layer, the first top surface and the first ring surface, each of the bump protection layers comprises a bump coverage portion; plating a plurality of gold layers at the bump coverage portion; eventually, removing the second zones to enable each of the first zones to form an under bump metallurgy layer.
The present invention is generally related to a method for manufacturing fine-pitch bumps, which particularly relates to the method for manufacturing fine-pitch bumps that prevents the copper ions from dissociation.
BACKGROUND OF THE INVENTIONIn structure of fine-pitch bumps, a short phenomenon is easily occurred by a relatively short spacing between two adjacent copper bumps owing to the copper ion dissociated from the copper bump.
SUMMARYThe primary object of the present invention is to provide a method for manufacturing fine-pitch bumps comprising the following steps of providing a silicon substrate having a surface, a plurality of bond pads disposed at the surface and a protective layer disposed at the surface, wherein the protective layer comprises a plurality of openings, and the bond pads are revealed by the openings; forming a titanium-containing metal layer on the protective layer and the bond pads, the titanium-containing metal layer comprises a plurality of first zones and a plurality of second zones located outside the first zones; forming a photoresist layer on the titanium-containing metal layer; patterning the photoresist layer to form a plurality of opening slots corresponded to the first zones of the titanium-containing metal layer; forming a plurality of copper bumps at the first zones of the titanium-containing metal layer, each of the copper bumps comprises a first top surface and a first ring surface; heating the photoresist layer to ream the opening slots of the photoresist layer, and the heat process enables the photoresist layer to form a plurality of body portions and a plurality of removable portions; etching the photoresist layer to remove the removable portions and to reveal the titanium-containing metal layer, and each of the body portions comprises an inner lateral surface; forming a plurality of bump protection layers on the titanium-containing metal layer, the first top surface and the first ring surface of each of the copper bumps, wherein each of the bump protection layers comprises a metallic coverage portion and a bump coverage portion, the bump coverage portion comprises a second top surface and a second ring surface, the first top surface and the first ring surface of each of the copper bumps are covered with the bump coverage portion, the inner lateral surface of each of the body portions and the second ring surface are spaced apart from each other to define a gap; plating a plurality of gold layers at each of the gaps, the second top surface and the second ring surface of each of the bump coverage portions, and each of the gold layers comprises a third top surface; eventually, removing the body portions of the photoresist layer; removing the second zones of the titanium-containing metal layer to enable each of the first zones of the titanium-containing metal layer to form an under bump metallurgy layer located under each of the copper bumps, each of the under bump metallurgy layers comprises a bearing portion located under each of the copper bumps and an extending portion protruded to the first ring surface of each of the copper bumps, and the extending portion of each of the under bump metallurgy layers is covered with the metallic coverage portion of each of the bump protection layers. The bump protection layers and the gold layers being formed on the titanium-containing metal layer, the first top surface and the first ring surface of each of the copper bumps may prevent the copper ions within the copper bumps from dissociation to avoid a short phenomenon, which improves reliability of the fine-pitch bump structure effectively.
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While this invention has been particularly illustrated and described in detail with respect to the preferred embodiments thereof, it will be clearly understood by those skilled in the art that it is not limited to the specific features and describes and various modifications and changes in form and details may be made without departing from the spirit and scope of this invention.
Claims
1. A fine-pitch bump structure at least comprising:
- a silicon substrate having a surface, a plurality of bond pads disposed at the surface and a protective layer disposed at the surface, wherein the protective layer comprised a plurality of openings, and the bond pads are revealed by the openings;
- a plurality of under bump metallurgy layers formed on the bond pads, each of the under bump metallurgy layers comprises a bearing portion and an extending portion;
- a plurality of copper bumps formed on the under bump metallurgy layers, each of the copper bumps comprises a first top surface and a first ring surface, the bearing portion of each of the under bump metallurgy layers is located under each of the copper bumps, and the extending portion of each of the under bump metallurgy layers is protruded to the first ring surface of each of the copper bumps;
- a plurality of bump protection layers formed on the extending portions of the under bump metallurgy layers, the first top surface and the first ring surface of each of the copper bumps, each of the bump protection layers comprises a metallic coverage portion and a bump coverage portion, wherein the bump coverage portion comprises a second top surface and a second ring surface, the first top surface and the first ring surface of each of the copper bumps are covered with each of the bump coverage portions, and each of the extending portions is covered with each of the metallic coverage portions; and
- a plurality of gold layers formed at each of the metallic coverage portions, the second top surface and the second ring surface of each of the bump coverage portions, each the gold layers comprises a third top surface.
2. The fine-pitch bump structure in accordance with claim 1, further comprises a plurality of wettable layers formed on the third top surfaces of the gold layers.
3. The fine-pitch bump structure in accordance with claim 1, wherein each of the metallic coverage portions is protruded to the second ring surface of the bump coverage portion and comprises a first outer lateral surface.
4. The fine-pitch bump structure in accordance with claim 3, wherein each of the gold layers comprises a second outer lateral surface coplanar with the first outer lateral surface of each of the metallic coverage portions.
5. The fine-pitch bump structure in accordance with claim 3, wherein the extending portion of each of the under bump metallurgy layers comprises a third outer lateral surface coplanar with the first outer lateral surface of each of the metallic coverage portions.
Type: Application
Filed: May 28, 2013
Publication Date: Oct 3, 2013
Inventors: Cheng-Hung Shih (Changhua County), Yung-Wei Hsieh (Hsinchu City), Shu-Chen Lin (Pingtung County), Cheng-Fan Lin (Hsinchu County), Hua-An Dai (Kaohsiung City)
Application Number: 13/903,447
International Classification: H01L 23/58 (20060101); H01L 23/498 (20060101);