Three-dimensional stacked image sensors and methods for making three-dimensional stacked image sensors

A method for manufacturing a three-dimensional stacked image sensor, the method comprising:

• attaching a first CCD side of a charge-coupled device (CCD) pixel array wafer to a first carrier side of a first carrier wafer utilizing wafer bonding, wherein the CCD pixel array wafer comprises the first CCD side and a second CCD side positioned opposite the first CCD side, the first carrier wafer comprises the first carrier side and a second carrier side, a plurality of CCD pixels are arranged in a form of a matrix in the first CCD side of the CCD pixel array wafer, and an epitaxial layer is disposed in the second CCD side of the CCD pixel array wafer;
• performing a first thinning procedure on the second CCD side of the CCD pixel array wafer while the CCD pixel array wafer is attached to the first carrier wafer, thereby at least partially exposing the epitaxial layer and forming a thinned surface on the CCD pixel array wafer;
• forming a passivation layer on the thinned surface of the CCD pixel array wafer;
• temporarily bonding a second carrier wafer to the passivation layer;
• performing a second thinning procedure on the second carrier side of the first carrier wafer while the second carrier wafer is bonded to the passivation layer;
• after performing the second thinning procedure, forming through-silicon vias (TSVs) through the first carrier wafer;
• electrically coupling a complementary metal-oxide-semiconductor (CMOS) readout integrated circuit (ROIC) wafer to the CCD pixel array wafer with the TSVs by direct bond interconnect (DBI) such that at least a portion of the CCD pixels are in signal communication with the ROIC wafer;
• and
• debonding the second carrier wafer, thereby forming the three-dimensional stacked image sensor.