Image sensor and formation method thereof

Abstract

The invention relates to an image sensor and a formation method thereof. The method comprises steps that a first semiconductor substrate and a second semiconductor substrate are provided; a reflectionstructure is formed on a front surface of the first semiconductor substrate and / or a front surface of the second semiconductor substrate; the front surface of the first semiconductor substrate and the front surface of the second semiconductor substrate are bonded; a pixel device is formed on a back surface of the first semiconductor substrate or a back surface of the second semiconductor substrate, and the pixel device includes photodiodes; light penetrating at least a part of the photodiodes is reflected by the reflection structure to at least a part of the photodiodes. The method is advantaged in that the transmitted light can be absorbed in a secondary time, and the absorbing capacity of the incident light is enhanced.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to an image sensor and a forming method thereof. Background technique [0002] Image sensors (Image Sensors) are the core components of camera equipment, which realize the image capture function by converting optical signals into electrical signals. Since the CMOS image sensor (CMOS Image Sensor, CIS) has the advantages of low power consumption and high signal-to-noise ratio, it has been widely used in various fields. [0003] Especially in front-side illumination (FSI) CIS, the quantum efficiency of absorbing long-wavelength light is relatively low, because the absorption coefficient of the semiconductor substrate (such as a silicon substrate) decreases with the increase of the wavelength of the incident light, For example, absorbing 700nm light in silicon requires a 5um absorption path. Therefore, when absorbing the long-wave light, most of the light will pas...

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Problems solved by technology

[0003] Especially in front-side illumination (FSI) CIS, the quantum efficiency of absorbing long-wavelength light is relatively low, because the absorption coefficient of the semiconductor substrate (such as a silicon substrate) decreases with the increase of the wavelength of the incident light, For example, absorbing 700nm light in silicon requires a 5um absorption path

Therefore, when absorbing long-wave light, most of the light will pass through the photodiode (Photo Diode, PD) area, resulting in a low absorption rate for long-wave light

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