Pass through via technology for use during the manufacture of a semiconductor device
A method for forming vias which pass through a semiconductor wafer substrate assembly such as a semiconductor die or wafer allows two different types of connections to be formed during a single formation process. One connection passes through the wafer without being electrically coupled to the wafer, while the other connection electrically connects to a conductive pad. To connect to a pad, a larger opening is etched into an overlying dielectric layer, while to pass through a pad without connection, a narrower opening is etched into the overlying dielectric layer. An inventive structure resulting from the method is also described.
1. A method for forming a semiconductor device, comprising:
forming a first conductive pad having an opening therein, and forming a second conductive pad having an opening therein;
forming a blanket conductive layer within the openings in the first and second conductive pads, wherein the blanket conductive layer is electrically isolated from the first conductive pad and is electrically coupled to the second conductive pad; and
removing a portion of the blanket conductive layer to form a first conductive plug within the opening in the first conductive pad and a second conductive plug within the opening in the second conductive pad.
2. The method of claim 1 further comprising:
forming a dielectric layer comprising a first opening therein having a diameter which is equal to or less than a diameter of the opening in the first pad and a second opening therein having a diameter which is greater than a diameter of the opening in the second pad;
forming the blanket conductive layer within the first and second openings in the dielectric layer; and
removing the portion of the blanket conductive layer to form the first plug within the first opening in the dielectric layer and to form the second plug within the second opening in the dielectric layer.
3. The method of claim 1 further comprising planarizing the blanket conductive layer during the removal of the portion of the blanket conductive layer.
4. The method of claim 1 further comprising:
providing a semiconductor wafer and forming the first and second conductive pads over the semiconductor wafer;
forming the blanket conductive layer within first and second openings in the semiconductor wafer; and
forming the first conductive plug within the first opening of the semiconductor wafer and forming the second conductive plug within the second conductive opening of the semiconductor wafer.
5. The method of claim 4 further comprising electrically isolating the blanket conductive layer from the semiconductor wafer through the use of dielectric spacers within the first and second openings in the semiconductor wafer.
6. The method of claim 2 further comprising forming first and second cross-sectional spacers within the opening of the first conductive pad and within the opening of the second conductive pad prior to forming the blanket conductive layer.
7. A method for forming a semiconductor device comprising:
forming a semiconductor wafer substrate assembly comprising a semiconductor wafer, a first conductive pad having a first opening therein formed over the semiconductor wafer and a second conductive pad having a second opening therein formed over the semiconductor wafer;
forming a dielectric layer having a first opening therein proximate the first pad and a second opening therein proximate the second pad, wherein a diameter of the first opening in the dielectric layer is less than or equal to the diameter of the first opening in the first conductive pad and a diameter of the second opening in the dielectric layer is greater than the diameter of the second opening in the second conductive pad;
subsequent to forming the dielectric layer, etching the semiconductor wafer through the first opening in the first pad to form a first opening in the semiconductor wafer which is continuous with the first opening in the first pad, and etching the semiconductor wafer through the second opening in the second pad to form a second opening in the semiconductor wafer which is continuous with the second opening in the second pad;
forming a first dielectric spacer which is continuous along the first opening in the dielectric layer, the first opening in the first conductive pad and the first opening in the semiconductor wafer, forming a second dielectric spacer along sidewalls which define the second opening the dielectric layer which are discontinuous with the first dielectric spacer, and forming a third dielectric spacer along the second opening in the second pad and the second opening in the semiconductor wafer, and which is discontinuous with the first and second dielectric spacers;
forming a first conductive plug within the first opening in the dielectric layer, the first opening in the first bond pad, and the first opening in the semiconductor wafer, wherein the first conductive plug is electrically isolated from the first conductive pad and contacts the first dielectric spacer; and
forming a second conductive plug within the second opening in the dielectric layer, the second opening in the second bond pad, and the second opening in the semiconductor wafer, wherein the second conductive plug is electrically connected to the second conductive pad and contacts the second and third dielectric spacers.
8. The method of claim 7 wherein the first and second conductive plugs are not exposed at a back side of the semiconductor wafer which is at a semiconductor wafer surface opposite the first and second conductive pads and the method further comprises removing a portion of the back side of the semiconductor wafer to expose the first and second plugs at the back side of the semiconductor wafer surface.
9. The method of claim 7 wherein the semiconductor wafer substrate assembly is a first semiconductor wafer substrate assembly and the method further comprises:
forming a second semiconductor wafer substrate assembly comprising a first conductive plug which is electrically isolated from a first conductive pad through which it passes and a second conductive plug which is electrically connected to a second conductive pad through which it passes;
electrically connecting the first conductive plug of the first semiconductor wafer substrate assembly with one of the first and second plugs of the second semiconductor wafer substrate assembly, and electrically connecting the second conductive plug of the first semiconductor wafer substrate assembly with the other of the first and second plugs of the second semiconductor wafer substrate assembly.
10. The method of claim 7 further comprising:
forming a blanket conductive layer within both the first and second openings in the semiconductor wafer; and
planarizing the blanket conductive layer to form the first and second plugs.
11. The method of claim 10 further comprising planarizing the dielectric layer during the planarizing of the blanket conductive layer to form the first and second plugs.
12. A method for forming a semiconductor device comprising:
forming a first bond pad having a horizontal surface and an opening therethrough having a perimeter defined by a sidewall of the first bond pad and a second bond pad having a horizontal surface and an opening therethrough having a perimeter defined by a sidewall of the second bond pad;
forming a dielectric layer over the first and second bond pads;
using a single etch, etching the dielectric layer from within the perimeter defined by the sidewall of the first bond pad and to expose the horizontal surface of the second bond pad, wherein subsequent to the etch the horizontal surface of the first bond pad remains covered by the dielectric layer;
subsequent to etching the dielectric layer, etching through the openings in the first and second bond pads to etch a semiconductor wafer which underlies the first and second bond pads;
subsequent to etching the semiconductor wafer, forming dielectric spacers within the openings in the first and second bond pads; and
forming a blanket conductive layer within the openings in the first and second bond pads, wherein the blanket conductive layer contacts the second bond pad at the exposed horizontal surface and does not contact the horizontal surface of the first bond pad.
13. The method of claim 12 further comprising planarizing the blanket conductive layer to result in first and second conductive structures, wherein the first conductive structure passes through the opening in the first bond pad and remains electrically isolated from the first bond pad and the second conductive structure passes through the opening in the second bond pad and is electrically connected to the second bond pad.
14. The method of claim 12 wherein the etch through the openings in the first and second bond pads etches completely through the semiconductor wafer.
15. The method of claim 13 further comprising:
during the etch of the semiconductor wafer through the openings in the first and second bond pads, only partially etching through the semiconductor wafer; and
back grinding the semiconductor wafer to expose the first and second conductive structures from a back side of the semiconductor wafer.
16. The method of claim 15 further comprising:
electrically contacting the second conductive structure to pass an electrical signal to the second bond pad; and
electrically contacting the first conductive structure to pass an electrical signal through the first bond pad without making substantial electrical contact with the first bond pad.
17. A semiconductor device comprising:
a semiconductor wafer having first and second openings therein;
a first conductive pad overlying the semiconductor wafer and having an opening therein, and a second conductive pad overlying the semiconductor wafer and having an opening therein;
a single conductive layer which provides a first conductive plug within the first opening in the semiconductor wafer and within the opening in the first conductive pad, and which provides a second conductive plug within the second opening in the semiconductor wafer and within the opening in the second conductive pad, wherein the first conductive plug is electrically isolated from the first conductive pad and the second conductive plug is electrically connected to the second conductive pad;
first and second cross-sectional spacers within the opening in the first conductive pad which separate the first conductive plug from the first conductive pad and third and fourth cross-sectional spacers within the opening in the second conductive pad which separate the second conductive plug from the second conductive pad.
18. The semiconductor device of claim 17 further comprising:
a dielectric layer having a first and second openings therein, wherein the first opening in the dielectric layer overlies the opening the in the first conductive pad and the second opening in the dielectric layer overlies the opening in the second conductive pad, and a diameter of the first opening in the dielectric layer is equal to or less than a diameter of the opening in the first conductive pad and a diameter of the second opening in the dielectric layer is greater than a diameter of the opening in the second conductive pad; and
the first plug is provided within the first opening in the dielectric layer and the second plug is provided within the second opening in the dielectric layer.
19. The semiconductor device of claim 17 further comprising the first and second plugs extending completely through the semiconductor wafer.
20. The semiconductor device of claim 17 wherein the semiconductor wafer is a first semiconductor wafer, and the semiconductor device further comprises:
the first semiconductor wafer having a circuit side with the first and second conductive pads formed on the circuit side of the wafer;
the first semiconductor wafer having a back side opposite the circuit side, wherein the first and second conductive plugs are exposed at both the circuit side and the back side; and
a first conductor which electrically connects the exposed portion of the first plug at the back side of the first semiconductor wafer with a first feature of a second semiconductor wafer, and a second conductor which electrically connects the exposed portion of the second plug at the back side of the first semiconductor wafer with a second feature of the second semiconductor wafer.