Semiconductor through silicon vias of variable size and method of formation
View Patent ↗A through-silicon via structure is formed by providing a substrate having a first conductive catch pad and a second conductive catch pad formed thereon. The substrate is secured to a wafer carrier. A first etch of a first type is performed on the substrate underlying each of the first and second conductive catch pads to form a first partial through-substrate via of a first diameter underlying the first conductive catch pad and a second partial through-substrate via underlying the second conductive catch pad of a second diameter that differs from the first diameter. A second etch of a second type that differs from the first type is performed to continue etching the first partial through-substrate to form equal depth first and second through-substrate vias respectively to the first and second conductive catch pads.
1. A method, comprising:
providing a substrate having a first conductive catch pad and a second conductive catch pad formed thereon;
securing the substrate to an overlying wafer carrier;
performing a laser etch on the substrate underlying each of the first conductive catch pad and the second conductive catch pad to form a first partial through-substrate via of a first via diameter underlying the first conductive catch pad and a second partial through-substrate via underlying the second conductive catch pad of a second via diameter that differs from the first via diameter by selectively exposing the substrate to a laser to form the second via diameter different from the first via diameter;
performing a reactive ion etch (RIE) on the substrate to continue etching the first partial through-substrate via to form a first through-substrate via to the first conductive catch pad and to continue etching the second partial through-substrate via to form a second through-substrate via to the second conductive catch pad, each of the first through-substrate via and the second through-substrate via having a same depth; and
forming a smaller of the first via diameter and the second via diameter in a digital logic circuit and forming a larger of the first via diameter and the second via diameter in analog circuitry.
2. The method of claim 1 further comprising:
performing a post laser etch clean step; and
performing the reactive ion etch (RIE) as a plasma etch.
3. The method of claim 1 further comprising:
providing the substrate as a silicon substrate.
4. The method of claim 1 further comprising:
forming a third through-substrate via in the substrate to a third conductive catch pad by using both the laser etch and the reactive ion etch, the third through-substrate via having a third via diameter that differs from the first via diameter and the second via diameter.
5. The method of claim 1 further comprising:
providing a layer of photoresist material on the substrate prior to performing the laser etch and etching selected portions of both the photoresist material and the substrate during the laser etch, the photoresist material protecting the substrate during the laser etch.
6. The method of claim 1 further comprising:
implementing the first via diameter to be less than a width of the first conductive catch pad; and
implementing the second via diameter to be less than a width of the second conductive catch pad.
7. A method comprising:
providing a substrate having a first conductive catch pad and a second conductive catch pad formed thereon;
securing the substrate to an overlying wafer carrier;
performing a laser etch on the substrate underlying each of the first conductive catch pad and the second conductive catch pad to form a first partial through-substrate via of a first via diameter underlying the first conductive catch pad and a second partial through-substrate via underlying the second conductive catch pad of a second via diameter that differs from the first via diameter wherein a laser is laterally moved to determine a value of at least one of the first via diameter and the second via diameter; and
performing a reactive ion etch (RIE) on the substrate to continue etching the first partial through-substrate via to form a first through-substrate via to the first conductive catch pad and to continue etching the second partial through-substrate via to form a second through-substrate via to the second conductive catch pad, each of the first through-substrate via and the second through-substrate via having a same depth.
8. A method comprising:
providing a silicon substrate having a first conductive pad and a second conductive pad formed thereon at an upper surface;
forming a dielectric layer overlying and electrically separating the first conductive pad and the second conductive pad;
securing the silicon substrate to an overlying wafer carrier;
performing a laser etch on a lower surface of the silicon substrate underlying each of the first conductive pad and the second conductive pad to form a first partial through-silicon substrate via having a first via diameter and underlying the first conductive pad and a second partial through-silicon substrate via underlying the second conductive pad having a second via diameter that differs from the first via diameter, said performing implemented by laterally moving a laser when forming at least one of the first via diameter or the second via diameter to determine a via diameter value; and
performing a reactive ion etch on the silicon substrate to continue etching the first partial through-silicon substrate via to form a first through-silicon substrate via to the first conductive pad and to continue etching the second partial through-silicon substrate via to form a second through-silicon substrate via to the second conductive pad, each of the first through-silicon substrate via and the second through-silicon substrate via having a same depth.
9. The method of claim 8 further comprising:
forming a photoresist layer on the lower surface of the silicon substrate prior to performing the laser etch and the reactive ion etch, the photoresist material protecting the silicon substrate.
10. The method of claim 8 further comprising:
forming a third through-silicon substrate via in the silicon substrate that is in contact with a third conductive pad at the upper surface of the silicon substrate, the third through-silicon substrate via having a third via diameter that differs from the first via diameter and the second via diameter and having the same depth as the first through-silicon substrate via and the second through-silicon substrate via.
11. The method of claim 10 further comprising:
filling at least a portion of each of the first through-silicon substrate via, the second through-silicon substrate via and the third through-silicon substrate via with conductive material of the same depth.
12. The method of claim 10 further comprising:
implementing the first via diameter to be less than a width of the first conductive pad;
implementing the second via diameter to be less than a width of the second conductive pad; and
implementing the third via diameter to be less than a width of the third conductive pad.
13. The method of claim 8 wherein securing the silicon substrate to an overlying wafer carrier further comprises:
applying an adhesive layer onto the dielectric layer; and
attaching the wafer carrier to the adhesive layer.
14. The method of claim 8 further comprising:
removing the wafer carrier subsequent to formation of the first through-silicon substrate via and the second through-silicon substrate via to permit further processing.