An all pixel PDAF CMOS image sensor with 0.64μmx1.28μm photodiode separated by self-aligned in-pixel deep trench isolation for high AF performance

Choi, Sungsoo; Lee, Kyung-Ho; Yun, Jungbin; Choi, Sungho; Lee, Seung-Joon; Park, Junghoon; Shim, Eun Sub; Pyo, Junghyung; Kim, Bum Suk; Jung, Minwook; Lee, Yunki; Son, Kyungmok; Jung, Sungmoon; Wang, Tae-Shick; Choi, Young-Dae; Min, Dong-Ki; Im, Joonhyuk; Moon, Cheol; Lee, Duck‐Hyung; Chang, Donghoon

doi:10.23919/vlsit.2017.7998212

Cited by 15 publications

(8 citation statements)

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“…Numerical analysis of the suggested structure was conducted using the finite-difference time-domain (FDTD) method [16]. This method is broadly used for the optical analysis of CMOS image sensors [17]. The pixel pitches were 1.0, 0.9, and 0.8 μm for the small pixel size.…”

Section: Simulation Resultsmentioning

confidence: 99%

High-Sensitivity Pixels with a Quad-WRGB Color Filter and Spatial Deep-Trench Isolation

Kim

2019

Sensors

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The demand for a high-resolution metal-oxide-semiconductor (CMOS) image sensor has increased in recent years, and pixel size has shrunk below 1.0 μm to allow accumulation of numerous pixels in a limited area. However, shrinking the pixel size lowers the sensitivity and increases crosstalk because the aspect ratio is worsened by maintaining the height of the pixel. This work introduces a high-sensitivity pixel with a quad-WRGB (White, Red, Green, Blue) color filter array (CFA), spatial deep-trench isolation (S-DTI), and a spatial tungsten grid (S-WG). The optical performance of the suggested pixel was analyzed by performing 3D optical simulations at 1.0, 0.9, and 0.8 μm pixel pitches as small-sized pixels. The quad-WRGB CFA is compared with the quad-Bayer CFA, and the S-DTI and S-WG are compared with the conventional DTI and WG. We confirmed an improvement in the sensitivity of the suggested pixel using the quad-WRGB CFA with S-DTI and S-WG to a maximum of 58.2%, 67.0%, and 66.3% for 1.0, 0.9, and 0.8 μm pixels, respectively.

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Section: Simulation Resultsmentioning

confidence: 99%

High-Sensitivity Pixels with a Quad-WRGB Color Filter and Spatial Deep-Trench Isolation

Kim

2019

Sensors

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“…In the case of the latest pixels, the deep trench isolation (DTI) and metal grid between each CF and PL have been widely used for eliminating optical crosstalk [ 20 , 21 , 22 ]. Moreover, the quad CF array, 2 × 2 microlens (2 × 2 ML), and in-pixel DTI have emerged as elements of advanced pixels [ 23 , 24 , 25 ]. Therefore, methods for aligning the optical stacks need to be defined according to the pixel structures’ development.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Method of Aligning the Optical Stacks for All Pixels

Hwang

Kim

2023

Sensors

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Reducing performance verification time is significant in product launch and production costs. This is especially true because aligning the optical stacks of off-axis pixels is a time-consuming task, but it is important to maintain sensitivity. In this paper, a numerical method to align the optical stacks of off-axis pixels is suggested in order to reduce performance test time. The components of the numerical method are the optical stack height, refractive index, and chief ray angle in order to calculate the optical stacks’ optimal shift distance. The proposed method was investigated to confirm effectiveness by using optical simulation. The sub-micron backside illumination (BSI) pixels were simulated, having 2 × 2 microlens, quad-color filter array, and in-pixel deep trench isolation (DTI). Moreover, the proposed method was evaluated for various pixel pitches, microlens shapes, and CRAs. As a result, the optical stacks were optimized by using the numerical method and validated via optical simulation. Therefore, the proposed numerical method is expected to help reduce the time and cost.

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“…The electrical crosstalk strongly depends on the structure and electrical properties of the photosensitive area. Deep trench isolation (DTI) [7,8,13,14] and heavy doping isolation [15,16] are employed to resist the electrical crosstalk currently. In smaller pixel cells, the width of the isolation structure also requires a corresponding reduction, which becomes a greater challenge to the process.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent crosstalk effects for image sensors with different isolation structures

et al. 2018

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Photo-generated carriers may diffuse into the adjacent cells to form the electrical crosstalk, which is especially noticeable after the pixel cell size has been scaled down. The electrical crosstalk strongly depends on the structure and electrical properties of the photosensitive areas. In this work, time-dependent crosstalk effects considering different isolation structures are investigated. According to the different depths of photo-diode (PD) and isolation structure, the transport of photo-generated carriers is analyzed with different regions in the pixel cell. The evaluation of crosstalk is influenced by exposure time. Crosstalk can be suppressed by reducing the exposure time. However, the sensitivity and dynamic range of the image sensor need to be considered as well.

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An all pixel PDAF CMOS image sensor with 0.64μmx1.28μm photodiode separated by self-aligned in-pixel deep trench isolation for high AF performance

Cited by 15 publications

References 0 publications

High-Sensitivity Pixels with a Quad-WRGB Color Filter and Spatial Deep-Trench Isolation

High-Sensitivity Pixels with a Quad-WRGB Color Filter and Spatial Deep-Trench Isolation

A Numerical Method of Aligning the Optical Stacks for All Pixels

Time-dependent crosstalk effects for image sensors with different isolation structures

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