Back-illuminated image sensor

Abstract

The present invention provides a back-illuminated image sensor. Metal traces are provided on the back surface of the back-illuminated image sensor, and the metal traces are used to transmit power signals, ground signals or data signals. The metal traces on the back surface are connected to the power signal line metal, ground signal line metal or data signal line metal on the front surface of the back-illuminated image sensor through vias or trenches, improving the driving ability of the signals and reducing the voltage drop during transmission.

Description

Technical Field

[0001] The present invention relates to the technical field of image sensors, and particularly to a back-illuminated image sensor. Background Art

[0002] A back-illuminated image sensor (BSI CMOS image sensor) transfers the original circuit part between the microlens and the photosensitive semiconductor to the periphery or below of the photosensitive semiconductor based on the technology of the traditional front-illuminated image sensor (FSI CMOS image sensor). First, a photosensitive diode region and metal interconnections are fabricated on the front surface of the semiconductor substrate, then the back surface of the semiconductor substrate is thinned, and the photosensitive diodes are interconnected and led out. A microlens is correspondingly fabricated on the back surface of the semiconductor substrate, so that light can directly enter the photosensitive semiconductor from the back, reducing reflection and greatly improving the light collection efficiency. The entire front surface is left for the photodiodes to achieve the largest possible fill factor. The photosensitive diode region is connected to the metal pads on the back surface of the semiconductor substrate through metal interconnections to realize the transmission of power supply signals, ground signals or data signals of the photosensitive diode region. Summary of the Invention

[0003] The purpose of the present invention is to provide a back-illuminated image sensor to improve the driving ability of signals and reduce the voltage drop during transmission.

[0004] Based on the above considerations, the present invention proposes a back-illuminated image sensor, in which metal traces are arranged on the back surface of the back-illuminated image sensor, and the metal traces are used to transmit power supply signals, ground signals or data signals; the metal traces on the back surface are connected to the power supply signal line metal, ground signal line metal or data signal line metal on the front surface of the back-illuminated image sensor through vias or trenches, improving the driving ability of signals and reducing the voltage drop during transmission.

[0005] Preferably, some of the vias or trenches are arranged in the non-pad area.

[0006] Preferably, some or all of the metal traces on the back surface of the back-illuminated image sensor are connected to the metal pads on the back surface of the back-illuminated image sensor.

[0007] Preferably, the metal traces on the back surface are connected to the power supply signal line, ground signal line or data signal line on the front surface of the back-illuminated image sensor and are connected to the metal pads on the front surface of the back-illuminated image sensor.

[0008] Preferably, the back surface of the back-illuminated image sensor has a pixel array area, and the metal traces on the back surface are arranged outside the pixel array area and there is a spacing between the metal traces and the effective photosensitive pixel area, and the spacing is greater than 5 μm.

[0009] Preferably, the thickness of the metal trace on the back side is greater than 0.1 μm.

[0010] Compared with the prior art, the back-illuminated image sensor of the present invention has the following beneficial effects:

[0011] In the present invention, a metal trace is arranged on the back side of the back-illuminated image sensor, and the metal trace is used to transmit a power signal, a ground signal or a data signal. The metal trace on the back side is connected to the power signal line metal, the ground signal line metal, the ground signal line metal or the data signal line metal on the front side of the back-illuminated image sensor through a through hole or a groove, thereby improving the signal driving capability and reducing the voltage drop during transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] By the drawings and the subsequent appendices to the specification Figure 1 With reference to the specific embodiments used to illustrate certain principles of the present invention, other features and advantages of the present invention will become clear or be more specifically explained.

[0013] Figure 1 A schematic diagram of providing metal wiring on the back side of an image sensor according to an embodiment of the present invention;

[0014] Figure 2 FIG. 1 is a schematic diagram of providing a metal pad on the back side of an image sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0015] In the following specific description of the preferred embodiments, reference will be made to the attached drawings which constitute a part of the present invention. The attached drawings show by way of example specific embodiments that can implement the present invention. The illustrative embodiments are not intended to be exhaustive of all embodiments according to the present invention. It will be appreciated that other embodiments may be utilized, and structural or logical modifications may also be made without departing from the scope of the present invention. Therefore, the following specific description is not restrictive, and the scope of the present invention is limited by the appended claims.

[0016] The present invention provides a back-illuminated image sensor, wherein a metal trace is arranged on the back side of the back-illuminated image sensor, and the metal trace is used to transmit a power signal, a ground signal or a data signal; the metal trace on the back side is connected to the power signal line metal, the ground signal line metal or the data signal line metal on the front side of the back-illuminated image sensor through a through hole or a groove, thereby improving the signal driving capability and reducing the voltage drop during transmission.

[0017] refer to Figure 1 , Figure 2As shown, the back-illuminated image sensor includes a semiconductor substrate (Substrate) 10, which has opposite front and back sides. Photodiodes are fabricated on the front side of the semiconductor substrate 10, and a pixel array region 11 is formed in the substrate 10. Peripheral circuits are formed around the pixel array region 11 to enable signal transmission in the pixel array region 11, such as power signals (AVDD), ground signals (GND), data signals, etc.

[0018] Continue to refer to Figure 1 As shown, metal traces 20 are provided on the back side of the back-illuminated image sensor. The metal traces 20 are used to transmit power signals, ground signals, or data signals. The metal traces 20 on the back side are connected to the power signal line metal, ground signal line metal, or data signal line metal on the front side of the back-illuminated image sensor through vias or trenches 40, and some of the vias or trenches 40 are provided in non-pad regions, that is, regions where no metal pads are provided. The thickness of the metal traces 20 on the back side of the image sensor is greater than 0.1 μm.

[0019] Some or all of the metal traces 20 on the back side of the back-illuminated image sensor are connected to the metal pads 50 on the back side of the back-illuminated image sensor. The metal traces 20 on the back side are connected to the power signal line, ground signal line, or data signal line 30 on the front side of the back-illuminated image sensor and are connected to the metal pads (not shown in the figure) on the front side of the back-illuminated image sensor, enabling the transmission of power signals (AVDD), ground signals (GND), and data signals between the power signal line, ground signal line, or data signal line on the front side and the metal traces on the back side, improving the driving ability of the signals and reducing the voltage drop during transmission.

[0020] The metal traces 20 on the back side are provided outside the pixel array region 11. The pixel array region 11 includes an effective photosensitive pixel region and dummy pixels. There is a spacing between the metal traces 20 on the back side and the effective photosensitive pixel region. For example, the spacing is greater than 5 μm to prevent uneven structures formed on the surface of the filter and microlens on the pixel array region.

[0021] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any case, the embodiments should be regarded as exemplary and non-limiting. In addition, obviously, the term "including" does not exclude other elements and steps, and the term "one" does not exclude a plurality. Multiple elements stated in the apparatus claims can also be implemented by one element. The terms first, second, etc. are used to denote names and do not indicate any specific order.

Claims

1. A back-illuminated image sensor, characterized in that, The back-illuminated image sensor includes a semiconductor substrate, and metal traces are provided on the back surface of the semiconductor substrate of the back-illuminated image sensor; a part of the metal traces on the back surface of the semiconductor substrate are connected to the power signal line, ground signal line or data signal line on the front surface of the semiconductor substrate of the back-illuminated image sensor through vias or trenches, and are connected to the metal pads on the front surface of the back-illuminated image sensor to improve the driving ability of the signal and reduce the voltage drop during transmission. The thickness of the metal traces is greater than 0.1 μm; Moreover, the back-illuminated image sensor includes a pixel array, the pixel array includes an effective photosensitive pixel region and a pseudo-photosensitive pixel region, and there is a spacing greater than 5 μm between the metal traces and the effective photosensitive pixel region.

2. The back-illuminated image sensor according to claim 1, wherein, Some of the vias or trenches are provided in the non-pad area.

3. The back-illuminated image sensor according to claim 1, wherein All the metal traces on the back surface of the back-illuminated image sensor are connected to the metal pads on the back surface of the back-illuminated image sensor.

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