Electroplating and electroless plating of conductive materials into openings, and structures obtained thereby
View Patent ↗A through hole ( 114 ) is formed in a wafer ( 104 ) comprising a semiconductor substrate ( 110 ). A seed layer ( 610 ) is sputtered on the bottom surface of the wafer. The seed is not deposited over the through hole's sidewalls adjacent the top surface of the wafer. A conductor ( 810 ) is electroplated into the through hole. In another embodiment, a seed is deposited into an opening in a wafer through a dry film resist mask ( 1110 ). The dry film resist overhangs the edges of the opening, so the seed is not deposited over the opening's sidewalls adjacent the top surface of the wafer. In another embodiment, a dielectric ( 120 ) is formed in an opening in a semiconductor substrate ( 110 ) by a non-conformal physical vapor deposition (PVD) process that deposits the dielectric on the sidewalls but not the bottom of the opening. A seed ( 610 ) is formed on the bottom by electroless plating. A conductor ( 810 ) is electroplated on the seed. In another embodiment, a dielectric ( 2910 ) is formed in the opening to cover the entire surface of the opening. A non-conformal layer ( 120 ) is deposited by PVD over the sidewalls but not the bottom of the opening. The dielectric ( 2910 ) is etched off the bottom with the non-conformal layer ( 120 ) as a mask. A seed ( 610 ) is formed on the bottom by electroless plating. The non-conformal layer can be formed by electroplating. It can be tantalum deposited by electroplating, then anodized. Other embodiments are also provided.
1. A manufacturing method comprising:
forming an opening in a first surface of a body comprising a semiconductor substrate, wherein the opening extends into the semiconductor substrate;
forming a seed for electroplating a conductor into the opening;
electroplating the conductor into the opening, wherein the electroplating is initiated on the seed at a distance from the first surface of the body but not over the opening's sidewalls adjacent the first surface of the body, wherein before the electroplating operation, a through hole is formed in the semiconductor substrate at the location of the opening; and
forming a conductive layer over a second surface of the body;
wherein forming the opening and the through hole comprises:
forming the opening in the first surface of the body such that the opening does not go through the body;
after forming the conductive layer, extending the opening to form the through hole and expose the conductive layer from the first surface of the body;
wherein the seed electrically contacts the conductive layer in the opening;
wherein the method further comprises coupling the conductive layer to an electrical potential for the electroplating operation, wherein during the electroplating operation the seed is coupled to the electrical potential through the conductive layer.
2. The method of claim 1 wherein forming the opening comprises extending the opening into a first surface of the semiconductor substrate, and the electroplating is initiated at a distance from the first surface of the semiconductor substrate but not over the opening's sidewalls adjacent the first surface of the semiconductor substrate.
3. The method of claim 1 wherein the seed is spaced from the first surface of the body.
4. The method of claim 1 wherein forming the opening and the seed comprises:
obtaining the body; and then
forming the seed on the body.
5. The method of claim 1 wherein the body comprises a transistor.
6. The method of claim 1 wherein the body comprises a diode.
7. The method of claim 1 wherein after the electroplating operation a contact pad is present at a second surface of the body at the through hole's location, the contact pad having a first surface facing away from the body, the contact pad's first surface being exposed and comprising at least a portion of the seed and/or the conductor and/or a conductive layer physically contacting the seed and/or the conductor, the contact pad's first surface not being attached to any circuit external to the body.
8. The method of claim 7 further comprising attaching the contact pad's first surface to a circuit located outside of the body.