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A study on a CMOS image sensor structure for the reduction of blooming effects

Title
A study on a CMOS image sensor structure for the reduction of blooming effects
Other Titles
CMOS image sensor의 blooming 현상을 해결하기 위한 구조에 대한 연구
Author
전성배
Advisor(s)
김태환
Issue Date
2016-08
Publisher
한양대학교
Degree
Master
Abstract
Recently the demand for CIS devices in the tablet, mobile phone, the automotive and security systems has significantly increased in response to the fact that the unit cost and power consumption of CIS (CMOS Image Sensor) element is greatly reduced. Especially, the demand for high added value, high-resolution products is rapidly increasing. Some of the issues reducing the quality of the image are occurred according to pixel size for high-resolution implementation is reduced. Among the various problems, the dark current is an important factor that greatly affects the lowering of the quality of the image. Dynamic range and fixed pattern noise characteristics is greatly deteriorated by the generation of the dark current, which influences the lowering of the quality of the image. In this study, we established a theoretical models of the phenomenon that is expected to cause the occurrence of dark current such as "current generated in the Si surface", "affected by doping and heat", "current generation in the depletion region.". Based on this model, we can develop a structure of the pixel which can handle the fast market changes and a prediction system of a change in doping and drive environment. For this reason, studies were carried out for the optimization design to reduce noise at the pixel transistor. It was analyzed for what about the impact on other photodiode by the blooming which is one of the causes of the distortion of the image. Since noise such as a dark current becomes large influence on the device when the element is small, research is needed to establish the current state of the theoretical model analyzing the causes.|최근 태블릿, 휴대 전화, 자동차 및 보안 시스템에서 CIS 장치에 대한 수요는 CIS (CMOS 이미지 센서) 소자의 단위 비용이 줄어들고 소비 전력이 크게 감소 된다는 사실 때문에 증가하고 있다. 특히 부가가치가 높은 고해상도 제품에 대한 수요가 급속하게 증가하고 있다. 고해상도 구현을 위하여 화소 크기가 작아짐에 따라 발생하는 화상의 품질을 감소시키는 여러 문제점이 발생하는 상황이다. 다양한 문제 중 암전류 (dark current)는 화질의 저하에 큰 영향을 주는 중요한 요소이다. 암전류의 발생에 의해 동적 범위 (dynamic range)와 고정 패턴 노이즈 (fixed pattern noise) 특성이 크게 저하되어 영상의 품질이 악화된다. 본 연구에서 우리는 암전류의 발생을 유발하는 것으로 예상되는 "실리콘 표면에 서 발생하는 전류", "doping과 열에 의한 영향", "공핍 영역에서의 전류 생성"등의 현상에 대한 이론적 모델을 확립 하고, 이 모델에 기초하여, 화소 트랜지스터에서 잡음을 줄이기 위해 최적화 설계를 수행 하였다. 이것은 화상의 왜곡의 원인 중 하나인 블루밍을 개선하는 것에 많은 도움을 주었다. 포토다이오드에서 빛에 의해 생성된 전자들이 인접한 다른 포토다이오드에 미치는 현상들이 어떻게 일어나는 지에 대해 분석하고, 이를 해결하기 위해 여러 가지 방법을 통해 실험을 하였다. 소자가 작을수록 암전류와 블루밍 등은 장치의 성능에 큰 영향을 끼치는 만큼 이 를 해결하기 위해 원인을 분석하는 연구가 필요하다
Recently the demand for CIS devices in the tablet, mobile phone, the automotive and security systems has significantly increased in response to the fact that the unit cost and power consumption of CIS (CMOS Image Sensor) element is greatly reduced. Especially, the demand for high added value, high-resolution products is rapidly increasing. Some of the issues reducing the quality of the image are occurred according to pixel size for high-resolution implementation is reduced. Among the various problems, the dark current is an important factor that greatly affects the lowering of the quality of the image. Dynamic range and fixed pattern noise characteristics is greatly deteriorated by the generation of the dark current, which influences the lowering of the quality of the image. In this study, we established a theoretical models of the phenomenon that is expected to cause the occurrence of dark current such as "current generated in the Si surface", "affected by doping and heat", "current generation in the depletion region.". Based on this model, we can develop a structure of the pixel which can handle the fast market changes and a prediction system of a change in doping and drive environment. For this reason, studies were carried out for the optimization design to reduce noise at the pixel transistor. It was analyzed for what about the impact on other photodiode by the blooming which is one of the causes of the distortion of the image. Since noise such as a dark current becomes large influence on the device when the element is small, research is needed to establish the current state of the theoretical model analyzing the causes.
URI
http://dcollection.hanyang.ac.kr/jsp/common/DcLoOrgPer.jsp?sItemId=000000094243https://repository.hanyang.ac.kr/handle/20.500.11754/125843
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > NANOSCALE SEMICONDUCTOR ENGINEERING(나노반도체공학과) > Theses (Master)
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