US Patent Application 18355481. IMAGE SENSOR WITH OVERLAP OF BACKSIDE TRENCH ISOLATION STRUCTURE AND VERTICAL TRANSFER GATE simplified abstract

IMAGE SENSOR WITH OVERLAP OF BACKSIDE TRENCH ISOLATION STRUCTURE AND VERTICAL TRANSFER GATE

Organization Name

Taiwan Semiconductor Manufacturing Company, Ltd.

Inventor(s)

Feng-Chi Hung of Chu-Bei City (TW)

Dun-Nian Yaung of Taipei City (TW)

Jen-Cheng Liu of Hsin-Chu City (TW)

Wei Chuang Wu of Tainan City (TW)

Yen-Yu Chen of Kaohsiung City (TW)

Chih-Kuan Yu of Nantou County (TW)

IMAGE SENSOR WITH OVERLAP OF BACKSIDE TRENCH ISOLATION STRUCTURE AND VERTICAL TRANSFER GATE - A simplified explanation of the abstract

This abstract first appeared for US patent application 18355481 titled 'IMAGE SENSOR WITH OVERLAP OF BACKSIDE TRENCH ISOLATION STRUCTURE AND VERTICAL TRANSFER GATE

Simplified Explanation

The patent application is for an image sensor device.

• The device includes a photodetector and a transfer transistor.
• The transfer transistor has a transfer gate that extends over the frontside of the semiconductor substrate.
• The transfer gate also has a vertical portion that extends to a certain depth below the frontside of the substrate.
• A gate dielectric separates the transfer gate from the substrate.
• The device also includes a backside trench isolation structure that surrounds the photodetector.
• The backside trench isolation structure extends from the backside of the substrate to a depth below the frontside.
• The depth of the backside trench isolation structure is less than the depth of the vertical portion of the transfer transistor.
• This allows for a vertical overlap between the lowermost portion of the transfer transistor and the uppermost portion of the backside trench isolation structure.

Original Abstract Submitted

Some embodiments are directed towards an image sensor device. A photodetector is disposed in a semiconductor substrate, and a transfer transistor is disposed over photodetector. The transfer transistor includes a transfer gate having a lateral portion extending over a frontside of the semiconductor substrate and a vertical portion extending to a first depth below the frontside of the semiconductor substrate. A gate dielectric separates the lateral portion and the vertical portion from the semiconductor substrate. A backside trench isolation structure extends from a backside of the semiconductor substrate to a second depth below the frontside of the semiconductor substrate. The backside trench isolation structure laterally surrounds the photodetector, and the second depth is less than the first depth such that a lowermost portion of the vertical portion of the transfer transistor has a vertical overlap with an uppermost portion of the backside trench isolation structure.