Methods for Hybrid Wafer Bonding Integrated with CMOS Processing

A method, comprising:

• manufacturing a front-end substrate having a plurality of active devices in the front-end substrate in a first semiconductor process;
• manufacturing a back-end substrate in a second semiconductor process having connections formed in metal layers in dielectric material, wherein the back-end substrate is free from active devices;
• forming a redistribution layer over the front end substrate and the back end substrate, the redistribution layer including metal pads and dielectric material separating the metal pads;
• physically contacting the surfaces of the redistribution layers of the front-end substrate and the back-end substrate;
• and
• performing wafer bonding to form bonds between the front-end and back-end substrates to form an integrated circuit.

A method, comprising:

• forming in a first semiconductor process a front-end substrate comprising at least a portion of a semiconductor wafer and active devices formed within the front-end substrate, and at least one metallization layer, and having a first redistribution layer on an upper surface comprising metal pads and dielectric material between the metal pads;
• forming, in a second semiconductor process different from the first semiconductor process, a back-end substrate comprising a carrier substrate, at least one metallization layer, and having a second first redistribution layer on an upper surface comprising metal pads and dielectric material between the metal pads;
• smoothing the surfaces of the first and second redistribution layers;
• bringing the first and second redistribution layers into contact so that the metal pads of the front-end substrate and the back-end substrate are in physical contact;
• and
• bonding the first and second redistribution layers together.