Stacked image sensor and forming method thereof

Abstract

The invention provides a stacked image sensor and a forming method thereof. The image sensor is formed by a plurality of wafers which are stacked. The forming method comprises the following steps: A,a photodiode of a pixel unit is formed on the first wafer, and part of transistors constituting a corresponding complete pixel unit are formed; B, the first wafer and the second wafer complete wafer-level bonding; C, the second wafer is thinned; and D, the rest of transistors constituting the corresponding complete pixel unit are formed on the second wafer corresponding to the pixel unit of the first wafer in position, and the rest of transistors constitute the complete pixel unit together with the photodiode, corresponding to the pixel unit, of the first wafer and part of the transistors. According to the stacked image sensor and the forming method thereof, the photodiode and part of the transistors are formed on the first wafer, the other transistors are formed on the second wafer, partof the transistors and the other transistors constitute the complete pixel unit jointly, process selectivity is more diversified, the structural property of the photodiode is improved, the signal transmitting speed is increased, and the overall property of the image sensor is optimized.

Description

technical field [0001] The invention relates to a stacked image sensor and a method for forming the same. Background technique [0002] At present, image sensors have been widely used in various electronic products such as still digital cameras, camera phones, digital video cameras, medical imaging devices (such as gastroscopes), and automotive imaging devices. [0003] In the traditional image sensor manufacturing process, all structures of a complete pixel unit are generally formed on a single wafer, such as photodiodes, transfer transistors, reset transistors, source follower transistors, row selection transistors, etc., due to the mutual influence between each structure, The process selectivity in the manufacturing process is limited. For example, many high-temperature processes cannot be used, and the structural performance of the photodiode cannot be guaranteed. In addition, since each transistor is arranged on the same wafer, the signal transmission speed is limited, ...

AI Technical Summary

Problems solved by technology

[0003] In the traditional image sensor manufacturing process, all structures of a complete pixel unit are generally formed on a single wafer, such as photodiodes, transfer transistors, reset transistors, source follower transistors, row selection transistors, etc., due to the mutual influence between each structure, The process selectivity in the manufacturing process is limited. For example, many high-temperature processes cannot be used, and the structural performance of the photodiode cannot be guaranteed. In addition, since each transistor is arranged on the same wafer, the signal transmission speed is limited, which affects the overall image sensor. performance

Images