Imaging devices, camera modules, and fabrication methods thereof

A fabrication method for an imaging device, comprising:

• providing a bottom wafer including a first surface, wherein
• the first surface of the bottom wafer includes a plurality of image sensor chips;
• each image sensor chip including a photosensitive surface and, opposite to the photosensitive surface, a bottom surface;
• the first surface is the photosensitive surface;
• the photosensitive surface includes a sensitive region, a peripheral transition region surrounding the photosensitive region, and an input/output wiring region surrounding the peripheral transition region;
• and
• at least one input/output wiring pad is disposed in the input/output wiring region;
• providing a selective filter wafer, including a second surface and a third surface;
• forming a plurality of retaining walls on the second surface of the selective filter wafer with a number and a size corresponding to a number and a size of the image sensor chips disposed on the first surface of the bottom wafer, respectively, or on the first surface of the bottom wafer in the peripheral transition regions of the plurality of image sensor chips;
• bonding the first surface of the bottom wafer to the second surface of the selective filter wafer, wherein the bottom wafer, the selective filter wafer, and the plurality of retaining walls together form a plurality of closed cavities above the photosensitive region;
• removing a portion of the selective filter wafer located outside of the plurality of retaining walls to expose the input/output wiring region of each image sensor chip and form a selective filter cover corresponding to the image sensor chip;
• cutting the bottom wafer and the selective filter wafer to obtain a plurality of individual imaging devices;
• providing outgoing wires for an imaging device, wherein each outgoing wire includes a lead-in terminal and a lead-out terminal, the lead-in terminal of an outgoing wire is connected to an input/output wiring pad, the lead-out terminal of the out-going wire extends out from the image sensor chip.