Semiconductor image sensor incorporating therein optical layer

Details Semiconductor image sensor incorporating therein optical layer Semiconductor image sensor incorporating therein optical layer

2000-06-28

2003-01-28

Dang, Hung Xuan (Department: 2873)

Radiant energy

Photocells; circuits and apparatus

Photocell controlled circuit

C250S208200

Reexamination Certificate

active

06512220

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an image sensor; and, more particularly, to a CMOS image sensor incorporating therein an optical layer for improving an optical efficiency thereof.
DESCRIPTION OF THE PRIOR ART
As is well known, an image sensor is an apparatus for receiving light, i.e., photons, reflected from an object and generating a digital image data. Especially, an image sensor made by a CMOS (complementary metal oxide semiconductor) fabrication technology is called a CMOS image sensor.
In
FIG. 1
, there is shown a cross-sectional view of a unit pixel contained in a conventional CMOS image sensor.
Generally, a unit pixel contained in the conventional CMOS image sensor is divided by a light sensing region
112
for accumulating photons reflected from an object and a peripheral circuit region
114
for transferring the photons to a data processing unit. A photodiode
120
is formed on top of the light sensing region
112
and transistors
130
are formed on top of the peripheral circuit region
114
, to thereby provide a semiconductor structure.
For electrical isolation and electrical interconnection, a plurality of insulating layers
140
,
150
and
160
and metal lines
152
and
162
are formed on the semiconductor structure. Then, a passivation layer
170
is formed on the uppermost insulating layer
160
in order to protect the unit pixel from an exterior.
However, the passivation layer and the insulating layers have been formed with consideration of electrical characteristic and device reliability rather than that of optical transmittance characteristic. As a result, an optical transmittance may be degraded due to a reflectance of the passivation layer and the insulating layers, thereby reducing sensitivity.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a CMOS image sensor incorporating therein an optical layer for improving an optical efficiency thereof.
In accordance with an aspect of the present invention, there is provided a semiconductor image sensor for detecting a light incident thereto, comprising: a semiconductor substrate divided into a light sensing region and a peripheral circuit region; a photodiode formed on top of the light sensing region; at least one transistor formed on top of the peripheral circuit region; at least one insulating layer formed on top of the photodiode and the transistor; and an optical layer formed on the insulating layer to efficiently transmit the light to the photodiode.


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