Patent ID: 7538033

Claim:
A method of forming an electrical connection from a first chip, having a contact pad exposed through an opening in a cover glass on the first chip, to a second chip having a first side and a second side, the method comprising: attaching the first side of the second chip to the first chip; etching an annular via having an inner perimeter and an outer perimeter and a thickness in between, wherein the inner perimeter corresponds to a shape and size of an outer perimeter of the contact pad, and wherein the annular via extends from the second side of the second chip, into and through the second chip, and down to the cover glass of the first chip so that the inner perimeter of the annular via substantially corresponds to the outer perimeter of the contact pad on the first chip; filling the annular via with an insulator so that an inner perimeter of the insulator coincides with the inner perimeter of the annular via; removing a volume of semiconductor material from the second chip, wherein the semiconductor material is removed from within the inner perimeter of the insulator, to create a void that extends from the second side of the second chip to the contact pad on the first chip; and filling at least some of the void with a conductive material so that an electrically conductive path is created within the void, wherein the electrically conductive path extends between the contact pad on the first chip and the second side of the second chip.