Television – Camera – system and detail – Optics
Reexamination Certificate
1999-07-14
2003-11-04
Ho, Tuan (Department: 2612)
Television
Camera, system and detail
Optics
C348S315000, C250S208100
Reexamination Certificate
active
06642965
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a solid-state image sensing device for receiving the optical image of an object formed on a light-receiving surface on which photoelectric converters are arranged in a matrix.
A solid-state image sensing device integrally comprises a group of pixels arranged in a matrix with a photoelectric conversion function and accumulation function, and a circuit having a scanning function of sequentially extracting, in time-series, signal charges accumulated in the respective pixels. As such a solid-state image sensing device, there is a MOS image sensing device (CMOS image sensor) having a CMOS (Complementary Metal Oxide Semiconductor) structure in which power consumption is low and peripheral circuits can be monolithically integrated.
As shown in
FIG. 4
, this CMOS image sensor comprises a plurality of photoelectric converters
301
arranged in a matrix to perform photoelectric conversion and charge accumulation. Each photoelectric converter
301
is adjacent to a circuit region
302
for extracting signal charges. The photoelectric converter
301
and circuit region
302
constitute a photoelectric conversion cell
305
.
A power supply line for supplying a power supply voltage or the like to the photoelectric converter
301
and circuit region
302
is laid in a Y-direction wiring region
303
between respective photoelectric conversion cells
305
adjacent in the X direction. A reset signal line for sending a reset signal to the photoelectric converter
301
and circuit region
302
, a selection signal line, and the like are laid in an X-direction wiring region
304
between respective photoelectric conversion cells
305
adjacent in the Y direction. The circuit region
302
is connected to the power supply line via a contact
303
a.
A light-shielding member
310
covers the respective photoelectric conversion cells
305
arranged in a matrix. Openings
311
are formed in the light-shielding member
310
at positions corresponding to the centers of the respective photoelectric converters
301
.
The detailed circuit arrangement of the CMOS image sensor will be described with reference to FIG.
5
.
As the photoelectric converter
301
, a photodiode
401
is used. The photodiode
401
is made up of a p-type well formed in a silicon substrate, and an n-type impurity region formed from the surface of the silicon substrate in the well. When light is incident on the photodiode
401
, electron-hole pairs are produced in the n-type impurity region. In the n-type impurity region, holes move to the p-type well, and only electrons are left. That is, charges are accumulated in the n-type impurity region of the photodiode
401
by irradiation of light. The accumulated charge amount changes depending on the intensity of incident light, and serves as signal charges.
A 1-pixel video signal by signal charges is amplified by a transistor
402
which receives a power supply voltage VDD via a power supply line
411
. The transistor
402
is connected to the power supply line
411
via a contact
411
a
. The contact
411
a
corresponds to the contact
303
a
in FIG.
4
.
The 1-pixel video signal is output from a signal output terminal
431
by selecting a transistor
403
by a signal from a vertical scanning shift register
421
and selecting a transistor
404
by a signal from a horizontal scanning shift register
422
. When a reset signal is input to a transistor
405
, the power supply voltage VDD is input to the photodiode
401
to erase the remaining charges.
The transistors
402
,
403
, and
405
in
FIG. 5
are formed in the circuit region
302
in FIG.
4
. When light is incident on the circuit region
302
, the transistors
402
,
403
, and
405
malfunction. To prevent this, the light-shielding member
310
(
FIG. 4
) covers the circuit region
302
.
Video signals for respective pixels output from the photodiodes
401
arranged in a matrix and amplified by the transistors
402
are sequentially extracted as image signals by the vertical and horizontal scanning shift registers
421
and
422
.
The photoelectric converter
301
and opening
311
shown in
FIG. 4
cannot be excessively downsized in terms of reception of light. For example, the opening
311
cannot be excessively downsized in consideration of the wavelength of light to be received. For this reason, the characteristics of the CMOS image sensor degrade if the integration degree is increased by downsizing the photodiode of the photoelectric converter
301
and the opening
311
.
As shown in
FIGS. 4 and 5
, the power supply line for supplying the power supply voltage VDD need not be prepared for each of adjacent photoelectric conversion cells
305
. That is, as shown in
FIG. 6
, one power supply line
411
is commonly used for photoelectric conversion cells
305
adjacent in the X direction, which can substantially halve the number of power supply lines
411
. As a result, as shown in
FIG. 7
, the power supply line suffices to be arranged every other Y-direction wiring region
303
, and the integration degree can increase. In this case, as shown in
FIG. 6
, circuit regions
302
adjacent in the X direction are connected to the power supply line
411
via a common contact
411
b.
However, if the integration degree is increased by the above method, the pitches between the openings
311
of the photoelectric converters
301
in the X direction become different, and a reproduced image partially shifts from the optical position of an object.
More specifically, as shown in
FIG. 7
, a distance d
1
between openings
311
adjacent in the X direction via the Y-direction wiring region
303
is different from a distance d
2
between openings
311
directly adjacent without the mediacy of the Y-direction wiring region
303
. However, pixels are arranged at an equal pitch in image reproduction, so an accurate image cannot be reproduced.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a solid-state image sensing device capable of obtaining a more accurate image reproduction state with a higher integration degree.
To achieve the above object, according to the present invention, there is provided a solid-state image sensing device comprising a plurality of photoelectric conversion cells which have photoelectric converters for photoelectrically converting optical signals and are arranged in a matrix to accumulate the photoelectrically converted signal charges, the photoelectric converters being adjacent to each other at different pitches in a predetermined direction, a light-shielding member which covers the photoelectric conversion cells arranged in a matrix, and a plurality of openings which are formed in the light-shielding member in correspondence with the photoelectric converters, and pass optical signals to the photoelectric converters, the openings being arranged at an equal interval in a predetermined direction.
REFERENCES:
patent: 5734155 (1998-03-01), Rostoker
patent: 6256066 (2001-07-01), Yukawa et al.
patent: 63-100879 (1988-05-01), None
patent: 6-204450 (1994-07-01), None
patent: 6-283694 (1994-10-01), None
patent: 9-46596 (1997-02-01), None
patent: 1999-0083635 (1999-11-01), None
Nagata Tsuyoshi
Nakashiba Yasutaka
Ho Tuan
McGinn & Gibb PLLC
NEC Electronics Corporation
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