A memory device includes a memory chip including a memory cell array connected to first word lines and first bit lines, first word line bonding pads respectively connected to the first word lines, and first bit line bonding pads respectively connected to the first bit lines, and a peripheral circuit chip, wherein the peripheral circuit chip includes a test cell array connected to second word lines and second bit lines, second word line bonding pads respectively connected to the first word line bonding pads, second bit line bonding pads respectively connected to the first bit line bonding pads, and a peripheral circuit connected to the second word line bonding pads and the second word lines or the second bit line bonding pads and the second bit lines.

A method includes determining a first offset between a first alignment mark on a first side of a first wafer and a second alignment mark on a second side of the first wafer; aligning the first alignment mark of the first wafer to a third alignment mark on a first side of a second wafer, which includes detecting a location of the second alignment mark of the first wafer; determining a location of the first alignment mark of the first wafer based on the first offset and the location of the second alignment mark of the first wafer; and, based on the determined location of the first alignment mark, repositioning the first wafer to align the first alignment mark to the third alignment mark; and bonding the first side of the first wafer to the first side of the second wafer to form a bonded structure.

In an embodiment, a device includes: a first die array including first integrated circuit dies, orientations of the first integrated circuit dies alternating along rows and columns of the first die array; a first dielectric layer surrounding the first integrated circuit dies, surfaces of the first dielectric layer and the first integrated circuit dies being planar; a second die array including second integrated circuit dies on the first dielectric layer and the first integrated circuit dies, orientations of the second integrated circuit dies alternating along rows and columns of the second die array, front sides of the second integrated circuit dies being bonded to front sides of the first integrated circuit dies by metal-to-metal bonds and by dielectric-to-dielectric bonds; and a second dielectric layer surrounding the second integrated circuit dies, surfaces of the second dielectric layer and the second integrated circuit dies being planar.

Alignment of a first wafer bonded to a second wafer can be determined using electrical wafer alignment methods. A wafer stack can be formed by overlaying a second wafer over a first wafer such that second metal bonding pads of the second wafer contact first metal bonding pads of the first wafer. A leakage current or a capacitance measurement step is performed between first alignment diagnostic structures in the first wafer and second alignment diagnostic structures in the second wafer for multiple mating pairs of first semiconductor dies in the first wafer and second semiconductor dies in the second wafer to determine the alignment.

In an embodiment, a method includes: bonding a back side of a first memory device to a front side of a second memory device with dielectric-to-dielectric bonds and with metal-to-metal bonds; after the bonding, forming first conductive bumps through a first dielectric layer at a front side of the first memory device, the first conductive bumps raised from a major surface of the first dielectric layer; testing the first memory device and the second memory device using the first conductive bumps; and after the testing, attaching a logic device to the first conductive bumps with reflowable connectors.

A flip-chip bonding method includes following operations. A wafer is provided with multiple semiconductor dies on an adhesive film held by a frame element. A semiconductor die is lifted up from the wafer by an ejector element. The semiconductor die is picked up with a collector element. The semiconductor die is flip-chipped with the collector element. An alignment check is performed to determine a position of the semiconductor die, so as to determine a process tolerance between a center of the collector element and a center of the semiconductor die. The semiconductor die with the collector element is transferred to a location underneath a bonder element based on the process tolerance of the alignment check. The semiconductor die is picked up from the collector element by the bonder element. The semiconductor die is bonded to a carrier by the bonder element.

A method includes providing a first wafer including a respective set of first metal bonding pads and at least one first alignment diagnostic structure, providing a second wafer including a respective set of second metal bonding pads and a respective set of second alignment diagnostic structures, overlaying the first wafer and the second wafer, measuring at least one of a current, voltage or contact resistance between the first alignment diagnostic structures and the second alignment diagnostic structures to determine an overlay offset, and bonding the second wafer to the first wafer.

A structure of semiconductor device is provided, including a first circuit structure, formed on a first substrate. A first test pad is disposed on the first substrate. A second circuit structure is formed on a second substrate. A second test pad is disposed on the second substrate. A first bonding pad of the first circuit structure is bonded to a second bonding pad of the second circuit structure. One of the first test pad and the second test pad is an inner pad while another one of the first test pad and the second test pad is an outer pad, wherein the outer pad surrounds the inner pad.

A wafer bonding apparatus includes lower and upper stages, lower and upper push rods, a position detection sensor, and processing circuitry. The stages may vacuum suction respective wafers on respective surfaces of the stages based on a vacuum pressure being supplied to respective suction holes in the respective surfaces from a vacuum pump. The push rods are movable through respective center holes in the stages to apply pressure to respective middle regions of the respective wafers. The position detection sensor may generate information indicating a bonding propagation position of the wafers based on detecting at least one wafer through a detection hole in at least one stage. The processing circuitry may process the information to detect the bonding propagation position and cause a change of at least one of a ratio of protruding lengths of the push rods, or a ratio of suction areas of the stages.

A method includes determining a first offset between a first alignment mark on a first side of a first wafer and a second alignment mark on a second side of the first wafer; aligning the first alignment mark of the first wafer to a third alignment mark on a first side of a second wafer, which includes detecting a location of the second alignment mark of the first wafer; determining a location of the first alignment mark of the first wafer based on the first offset and the location of the second alignment mark of the first wafer; and, based on the determined location of the first alignment mark, repositioning the first wafer to align the first alignment mark to the third alignment mark; and bonding the first side of the first wafer to the first side of the second wafer to form a bonded structure.