Backside illuminated image sensor and manufacturing method thereof

Abstract

The invention provides a backside illuminated image sensor and a manufacturing method thereof. The manufacturing method comprises the steps that a bonding wafer comprising a carrier wafer and a devicewafer is provided, the front face of the device wafer is attached to the carrier wafer, and a reference mark structure is formed in the device wafer; a grounding layer is formed on the back surface of the device wafer and an opening is formed in the grounding layer, the opening is positioned right above the reference mark structure; in a subsequent photoetching process, the reference mark structure can be identified through the opening, so that the patterned functional layer formed on the grounding layer subsequently can take the reference mark structure as an alignment reference, the alignment precision of the functional layer and a graph in a device wafer can be improved, and the performance of the backside illuminated image sensor is improved. The invention also provides the backside illuminated image sensor manufactured by using the manufacturing method of the backside illuminated image sensor.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a back-illuminated image sensor and a manufacturing method thereof. Background technique [0002] figure 1 It is a schematic cross-sectional view of an existing back-illuminated image sensor. refer to figure 1 , in the manufacturing process of the back-illuminated image sensor (BSI), the following steps are included: a) bonding the front surface of the device wafer 120 with a pattern formed inside to the carrier wafer 110 to form a bonded wafer; b) A ground layer 130 is formed on the back side of the device wafer 120, the ground layer 130 includes a dielectric layer 131 and a metal material layer 132 (such as an aluminum metal layer), and a ground mark structure 133 is formed on the ground layer 130; c) on the ground layer 130 The grating isolation layer 140 is formed, and the grating isolation layer 140 is patterned. [0003] During the above-mentioned patterning proc...

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Problems solved by technology

However, in the manufacturing process of the back-illuminated image sensor, the overlay accuracy of the ground layer 130 is likely to change, resulting in the patterned grating isolation layer 140 and the pattern in the device wafer 120 using the ground mark structure 133 as an alignment reference. Alignment accuracy is poor

In order to improve the alignment accuracy of the grating isolation layer and the pattern in the device wafer, engineers usually need to update the compensation value of the overlay accuracy of the grating isolation layer according to the change of the overlay accuracy of the ground layer, which affects the process efficiency

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