Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Recrystallized semiconductor material
Reexamination Certificate
2001-05-01
2004-11-02
Tran, Minhloan (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Recrystallized semiconductor material
C257S072000, C257S059000
Reexamination Certificate
active
06812494
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor device comprising a plurality of functional elements arranged on a substrate.
2. Related Background Art
To date, thin film transistors prepared by using an amorphous silicon thin film for functional elements have a wide variety of applications as switching devices including display devices such as liquid crystal panels and organic EL panels as well as optical sensor panels where they are used in combination with PIN photodiodes comprising an amorphous silicon thin film like TFT elements or photoelectric conversion elements (to be referred to as optical sensor elements hereinafter) such as MIS photocapacitors and TFT optical sensors.
In recent years, efforts have been paid to develop medical applications for optical sensor panels. Particularly, indirect-type radiation imaging apparatus adapted to transform radioactive rays into visible light by means of fluorescent substances to indirectly read the obtained optical information by means of an optical sensor panel and direct type radiation imaging apparatus comprising TFT devices and amorphous selenium to directly transform radioactive rays into electric signals have been developed.
FIG. 15
shows an equivalent circuit diagram of an optical sensor panel comprising TFT elements and PIN photodiodes and
FIG. 16
shows a schematic cross sectional view of such an optical sensor panel. In
FIG. 15
, reference numerals
1010
,
1020
and
1030
respectively denote a PIN optical sensor, a TFT and a signal wire, whereas reference numerals
1040
and
1050
respectively denotes a TFT drive wire and a bias wire of the PIN optical sensor.
In
FIG. 16
, reference numerals
2010
,
2020
,
2030
,
2040
,
2050
,
2060
,
2070
and
2080
respectively denote a glass substrate, a gate wire, a gate insulating film, an i-type a-Si layer, an SiN layer, an n+ ohmic contact layer, a source/drain electrode and a sensor lower-electrode whereas reference numerals
2100
,
2110
,
2120
respectively denotes P-, I- and N-type a-Si layers. Reference numeral
2090
denotes a sensor upper-electrode and reference numeral
2130
denotes an SiN protection film.
The incoming beam that is carrying image information is subjected to photoelectric conversion by the PIN optical sensor
1010
and its electric charge is stored in a sensor capacity C
1
. Subsequently, when the TFT
1020
is turned on, the electric charge is distributed to a capacity C
2
formed at the crossing of the signal line
1030
and the TFT drive wire
1040
so that the change in the potential of the signal line
1030
is read and output.
Currently, improvements are required of the above-described optical sensor panels in terms of substrate size and process precision in order to meet the demand for a larger display area and a higher degree of definition. However, any such improvements may inevitably entail a huge amount of investment in plant and equipment and a long introductory pre-operational period so that doubts may be cast on such an idea.
In view of this problem, there have been proposed semiconductor devices adapted to produce a large display area by bonding a plurality of relatively small panels. Such semiconductor devices may be realized by using existing plants and equipment for manufacturing small substrates.
FIG. 17
is a schematic perspective view of a radiation image reading apparatus having a large display area and formed by bonding four optical sensor panels.
FIG. 18
is a schematic cross sectional view of the device of FIG.
17
. In
FIG. 17
, reference numerals
3010
,
3020
,
3050
,
3060
and
3400
respectively denote an optical sensor panel, a base, a fluorescent panel, a flexible substrate and a chassis.
Referring to
FIG. 18
, the base
3020
is used to rigidly hold four optical sensor panels
3010
and typically made of lead that absorbs radioactive rays and protects the electric components arranged therebelow. The sensor panels
3010
are bonded to the base
3020
by way of a first adhesive layer
3030
, while the fluorescent panel
3050
for transforming radioactive rays into visible light is bonded to the sensor panels
3010
by way of a second adhesive layer
3040
. In
FIG. 18
, reference numeral
3070
denotes a printed substrate for driving the sensor panels and reference numeral
3060
denotes a flexible substrate for connecting the printed substrate
3070
and the sensor panels
3010
.
In
FIG. 18
, there are also shown a cabinet
3200
, a lid
3210
, a cover
3230
typically made of lead and adapted to protect the electric components, feets
3240
for rigidly securing the printed substrate
3070
and angles
3250
firmly securing the base
3020
to the cabinet
3200
. Note that the chassis
2400
comprises members denoted by
3200
,
3250
. A sensor unit is formed by firmly securing the radiation sensor
3300
within the chassis.
However, when bonding a plurality of panels in a manner as described above, the precision level of the boundaries and that of the clearances separating them are of vital importance.
FIG. 19
is a schematic plan view of four bonded panels.
FIG. 20
is an enlarged schematic plan view of a central part of the four bonded panels of
FIG. 19
, illustrating the boundaries of the panels. In
FIG. 20
, P denotes the pitch of arrangement of pixels and Pc denotes the distance between the centers of two pixels that belong to different panels and are arranged adjacently relative to each other. In general, correction by way of image processing can properly be carried out, when Pc<2P or the clearance between two panels is made to be less than the size of one pixel. In other words, each sensor panel has to be cut with a margin of several tens of micrometers from the edges of the pixels.
Any attempt for meeting the above requirement is accompanied by the problems as listed below and can end up with a poor manufacturing yield and a poor performance unless they are solved to a satisfactory extent.
1. Some of the pixels of an optical sensor panel can be adversely affected by a cutting operation due to problems such as chipping and/or displacement. Then, the reliability of the sensor panel is lowered after assembling.
FIG. 21
is a schematic plan view of a cut area of a sensor panel comprising a pixel
4010
and a protection film
4020
typically made of SiN. In
FIG. 21
,
4030
denotes a notch formed typically by chipping and
4040
denotes an end facet produced by the cutting. As seen from
FIG. 21
, the protection film
4020
is partly damaged by notches
4030
. As a result, although the sensor panel operates properly in the initial stages, it has been confirmed that its output fluctuates when it is subjected to high temperature and high humidity.
2. Pixels can be destructed by static electricity appearing in the course of assembling of the panels. Normally, insulating items such as glass substrates can become electrically charged with ease when peeled off in a vacuum chuck stage and/or scrubbed by blown air. When the panel is just brought close to an object having an electric potential difference such as a grounded cabinet, an electric discharge occurs to destroy some or all of the pixels of the panel, particularly those arranged at the corners. Then, a poor manufacturing yield can result.
3. A pixel of the assembled sensor panels can be destroyed along the cut edges, particularly at the corners, when static electricity is accumulated to 2 to 3 kV in the course of handling the panels in the assembling process.
SUMMARY OF THE INVENTION
In view of the above identified problems, it is an object of the present invention to provide a semiconductor device with which a panel having a large area or a narrowly margined panel with the circumferential space minimized can be manufactured stably with a high yield.
More specifically, it is a first object of the present invention to provide a semiconductor device provided with a slice check wire for determining the acceptability of the operation of cutting the panels in order to ensure that the panels to be
Mochizuki Chiori
Watanabe Minoru
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Sefer Ahmed N.
Tran Minhloan
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