Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Charge transfer device
Reexamination Certificate
2003-09-08
2004-09-21
Ngô, Ngân V. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Charge transfer device
C257S233000, C257S240000, C257S241000
Reexamination Certificate
active
06794692
ABSTRACT:
This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2002-262835 filed in Japan on Sep. 9, 2002, which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solid-state image pick-up device including a plurality of photoelectric converting devices provided like a tetragonal grid in a row direction and a column direction orthogonal thereto over the surface of a semiconductor substrate.
2. Description of the Related Art
A solid-state image pick-up device to be utilized for a digital camera detects a charge corresponding to an image signal by means of a photoelectric converting device. For this reason, in general, it is hard to widen a dynamic range. In order to obtain an image in a wide dynamic range, it is necessary to increase the amount of charges to be detected by the photoelectric converting device. For this purpose, it is necessary to increase the light receiving area of the photoelectric converting device. When the amount of the charges to be detected is increased, however, it is necessary to increase a transfer capacity, that is, a dimension of a charge transfer section. Consequently, there is a problem in that the number of pick-up images cannot be increased.
FIG. 11
shows a schematic structure according to an example of a conventional solid-state image pick-up device. The solid-state image pick-up device in
FIG. 11
serves to convert a light intensity into a charge signal by a plurality of photoelectric converting devices
10
provided like a tetragonal grid, and a detected signal charge is transferred to an output section
40
through a plurality of vertical transfer sections
20
(In
FIG. 11
, one vertical transfer section is surrounded in a broken line) and a horizontal transfer section
30
and a voltage signal
41
corresponding to the signal charge is output from the output section
40
.
The vertical transfer section
20
serves to transfer charges from the photoelectric converting devices
10
in a column direction Y and includes a plurality of vertical transfer channels (not shown) formed on a semiconductor substrate, a plurality of vertical transfer electrodes
101
to
104
formed on the upper layers of the vertical transfer channels, and a charge reading region
21
for reading the charges of the photoelectric converting devices
10
onto the vertical transfer channels (which are typically shown in an arrow of FIG.
11
).
The vertical transfer channels take an almost straight shape extended in the column direction Y toward the side of the photoelectric converting devices
10
, and a region for storing and transferring the charge is partitioned by the vertical transfer electrodes
101
to
104
formed on upper layers thereof. Two vertical transfer electrodes
101
to
104
are provided corresponding to the respective photoelectric converting devices
10
(only any of them corresponding to the photoelectric converting devices for two rows has the designation in
FIG. 11
) and the vertical transfer electrodes having the same positional relationship with the photoelectric converting devices for the same row are electrically connected through electrode wirings
121
and
122
. The vertical transfer electrodes
101
to
104
are formed of polycrystalline silicon.
Vertical transfer pulses having four phases are applied to the vertical transfer electrodes
101
to
104
through terminals
11
to
14
and the charges of the vertical transfer channels are transferred in the column direction Y. The vertical transfer pulse is also applied to transfer electrodes
105
,
106
and
107
between the vertical transfer section
20
and the horizontal transfer section
30
, and the charges for one row which are detected by the photoelectric converting devices
10
for an odd row or the photoelectric converting devices
10
for an even row are sent to the horizontal transfer section
30
. The reading operation of the photoelectric converting devices
10
for the odd row is carried out by superposing a reading pulse on a first-phase pulse to be applied immediately before the start of a vertical charge transfer (a vertical transfer pulse to be applied to the terminal
11
), and the reading operation of the photoelectric converting devices
10
for the even row is carried out by superposing a reading pulse on a third-phase pulse to be applied immediately after the start of the vertical charge transfer (a vertical transfer pulse to be applied to the terminal
13
).
The horizontal transfer section
30
serves to transfer a charge from the vertical transfer section
20
in a row direction X and includes a horizontal transfer channel and a horizontal transfer electrode (which are not shown). Horizontal transfer pulses having two phases are applied to the horizontal transfer electrode through terminals
131
and
132
and the signal charges of the photoelectric converting devices
10
for one row which are sent from the vertical transfer section
20
are transferred to the output section
40
.
Next, description will be given to the driving operation of the solid-state image pick-up device shown in FIG.
11
. Referring to charges stored in the photoelectric converting device
10
corresponding to the intensity of a light incident from a field, first of all, the charges stored in the photoelectric converting devices
10
for the odd row are read onto the vertical transfer channel in response to the reading pulse to be superposed on the first-phase vertical transfer pulse. Then, the charges are transferred in the vertical transfer channel in response to the vertical transfer pulse and are held in the predetermined region of the horizontal transfer channel. Subsequently, when the horizontal transfer pulse is applied, the held charges for one row are sequentially sent to the output section
40
and the voltage signal
41
corresponding to the amount of the charges is output. After such a transfer processing is carried out for all of the photoelectric converting devices
10
for the odd rows, a reading pulse is superposed on the third-phase vertical transfer pulse to read the charges stored in the photoelectric converting devices
10
for the even rows onto the vertical transfer channel, thereby carrying out the same transfer.
In the conventional solid-state image pick-up device shown in
FIG. 11
, a region between the photoelectric converting devices in a vertical direction is utilized as the wiring path of the vertical transfer electrode and an image pick-up device is a useless region. More specifically, the ratio of the area of the photoelectric converting device to play a part in light concentration and charge storage and the area of the vertical transfer channel to play a part in the transfer of a signal charge to an area per pixel has an upper limit. For this reason, it is hard to raise the sensitivity of a pick-up image and a saturation voltage.
When the amount of the signal charge to be detected by the photoelectric converting device is increased, however, it is necessary to increase the channel width of the charge transfer channel. Conventionally, the charge transfer channel is provided on only the side of the photoelectric converting device. Consequently, the light receiving region of the photoelectric converting device becomes rectangle-shaped. In general, a microlens is provided for the light concentration above the photoelectric converting device
10
. If the shape of the light receiving region is rectangular, it is hard to concentrate an incident light in the photoelectric converting device by means of the microlens. Consequently, there is a problem in that shading is increased, resulting in a remarkable reduction in the sensitivity with a small F value.
Patent Document JP-A-5-291552 has described a solid-state image pick-up device in which a charge transfer section has a winding shape between photoelectric converting devices to enlarge a dynamic range. In this solid-state image pick-up device, the photoelectric converting device is to be provided in winding
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