Solid state image pick-up device equipped with charge...

Details Solid state image pick-up device equipped with charge... Solid state image pick-up device equipped with charge...

1997-09-25

2001-09-04

Garber, Wendy R. (Department: 2612)

Television

Camera, system and detail

Support or housing

C348S294000, C358S493000, C250S239000

Reexamination Certificate

active

06285400

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a solid state image pick-up device and, more particularly, to a solid state image pick-up device equipped with a charge-coupled device having an incident surface alignable with a focal plane.
DESCRIPTION OF THE RELATED ART
A personal computer processes digital video signals, and a digital video recorder is required as a source of the digital video signal representative of an image. An electronic still camera and a digital movie camera are typical examples of the source of digital video signal presently obtainable in the market. The digital video recorder is equipped with a charge-coupled device, and an image is picked up through the charge-coupled device.
FIG. 1
illustrates a typical example of the charge-coupled device incorporated in the prior art digital video recorder. The prior art charge coupled device comprises an array
1
of photo-diodes
1
a
, and the photo-diodes
1
a
converts a photo-radiation carrying an image to electric charge. The amount of electric charge is proportional to the intensity of the photo-radiation. A plurality of vertical shift registers
2
are associated with the columns of photodiodes
1
a
, and transfer transistors
3
are connected between the photo-diodes
1
a
and the vertical shift registers
2
. The transfer transistors
3
concurrently turn on, and the electric charge is provided from the array
1
to the vertical shift registers
2
as charge packets. The charge packets are representative of the image. Though not shown in
FIG. 1
, each of the vertical shift registers
2
has charge transfer electrodes and transfers the charge packets in synchronism with a multi-phase charge transfer signal applied to the charge transfer electrodes.
The prior art charge coupled device further comprises a horizontal shift register
4
and an output circuit
5
connected to the horizontal shift register
4
. The vertical shift registers
2
are connected to the horizontal shift register
4
, and the charge packets read out from each row of photo-diodes
1
a
are transferred from the vertical shift registers
2
to the horizontal shift register
4
. The horizontal shift register
4
also has charge transfer electrodes (not shown), and conveys the charge packets to the output circuit
5
in synchronism with a multi-phase charge transfer signal. The output signal
5
converts the charge packets to a potential signal IMG carrying the image.
The prior art charge coupled device behaves as follows. Assuming now that image-carrying light is incident onto the array
1
of photo-diodes
1
a
, the photo-diodes
1
a
produce electric charge depending upon the intensity of the image-carrying light, and accumulate the electric charge for a sixtieth second. Thereafter, a read-out signal is applied to the gate electrodes of the transfer transistors
3
, and the transfer transistors
3
concurrently turn on. Then, the array
1
supplies the charge packets to the vertical shift registers
2
. The multi-phase charge transfer signal is sequentially supplied to the vertical shift registers
2
, and the vertical shift registers
2
convey the charge packets to the horizontal shift register
4
. The vertical shift registers
2
firstly deliver the charge packets read out from the row of photo-diodes
1
a closest to the horizontal shift register
4
, and the charge packets are corresponding to pixels on a horizontal scanning line. The horizontal shift register
4
successively supplies the charge packets to the output circuit
5
during a horizontal scanning period, and the charge packets read out from the next row are delivered from the vertical shift registers
2
to the horizontal shift register
4
at the end of the horizontal scanning period. In this way, the charge packets are sequentially supplied from the vertical shift registers
2
through the horizontal shift register
4
to the output circuit
5
, and the output circuit
5
converts the charge packets to the potential signal IMG representative of the image.
The image-carrying light is incident onto the array of photo-diodes la through micro-lens
6
as shown in FIG.
2
. Firstly, description is made on the structure of the prior art charge-coupled device. The prior art charge coupled device is fabricated on an n-type semiconductor substrate
10
. A p-type well
11
is defined in a surface portion of the n-type semiconductor substrate
10
. Heavily doped n-type accumulating regions
12
are arrayed in the p-type well
11
, and are overlapped with heavily doped p-type regions
13
. The p-n junctions between the heavily doped p-type regions
13
and the heavily doped n-type accumulating regions
12
form the photo-diodes
1
a.
Heavily doped n-type channel regions
13
are further formed in the p-type well
11
, and are alternated with the columns of heavily doped n-type accumulating regions
12
. Heavily doped p-type channel stopper regions
14
isolate the heavily doped n-type channel regions
13
from the non-associated columns of heavily doped n-type accumulating regions
12
. A thin insulating layer
16
covers the surface of the p-type well
11
, and the charge transfer electrodes
17
of polycrystalline silicon are formed on the thin insulating layer
16
. The heavily doped n-type channel regions
13
, the thin insulating layer
16
and the charge transfer electrodes
17
as a whole constitute the vertical shift registers
2
.
The charge transfer electrodes
17
are covered with inter-level insulating layers
18
, and a photo-shield layer
19
is formed on the inter-level insulating layers
18
. The photo-shield layer
19
prevents the heavily doped n-type channel regions
14
from photo radiation, and allows the image-carrying light LT to fall onto the photo-diodes
1
a
. The photo-shield layers
19
are covered with an insulating layer
20
. Though not shown in
FIG. 2
, the horizontal shift register
4
and the output circuit
5
are further fabricated on the n-type semiconductor substrate
10
.
The insulating layer
20
is covered with a thick transparent resin layer
21
, and the micro-lenses
6
are formed on the top surface of the thick transparent resin layer
21
. The micro-lenses concentrate the image-carrying light LT onto the photo-diodes
1
a
, and the image-carrying light LT is incident through the thick transparent resin layer
21
and the apertures
19
a
formed in the photo-shield layer
19
onto the photo-diodes
1
a
. For this reason, the micro-lenses
6
are located over the apertures
19
a
. The thick transparent resin layer
21
provides the flat surface for the micro-lenses
6
, and regulates the distance between the micro-lenses
6
and the photo-diodes la to the focal length of the micro-lenses
6
.
The digital video recorder is a consumer good, and is expected to reduce the price in the market. For this reason, a small semiconductor chip is used for the prior art charge coupled device. In fact, although the prior art charge coupled device for a quarter inch optical format contains two hundred fifty thousand to three hundred eighty thousand pixels, it fabricated on a semiconductor chip of 4 millimeters by 4.5 millimeters.
On the other hand, the resolution is the most important factor in a printing business, and the prior art charge coupled device contains one million to several million pixels. The minimum pixel occupies an area of 5 microns by 5 microns, and the prior art charge coupled device requires a large semiconductor chip. For example, the video camera DCB-II is manufactured by Ni-hon Scitex ltd., and a charge-coupled device incorporated therein has four million and two hundred thousand pixels fabricated on a semiconductor chip of 30 millimeters by 30 millimeters. Another high-resolution video camera is manufactured by Kodak Japan Corporation as “DCS420”, and has six million pixels fabricated on a semiconductor chip of 18.4 millimeters by 27.6 millimeters.
FIG. 3
illustrates the structure of an example
30
of the prior art video recorder. A semiconductor chip
31
is mounted on an inner flat surface of a package
32
, and the

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