Semiconductor device

Details Semiconductor device Semiconductor device

2002-10-30

2004-11-02

Pham, Long (Department: 2814)

Active solid-state devices (e.g., transistors, solid-state diode

Combined with electrical contact or lead

Die bond

C257S666000, C257S734000, C257S783000

Reexamination Certificate

active

06812579

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION(S)
This application is based on, and claims priority to, JP PA 2001-332482 filed Oct. 30, 2001, the contents of which are incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device in which, when a semiconductor chip is die bonded onto a package, alignment thereof is performed at the same time.
2. Description of the Related Art
As an example of a semiconductor device, a semiconductor photodetector element having a light detecting function will be explained. Examples of semiconductor photodetector elements include an image pick up CCD (charge coupled device), a line sensor (linear image sensor), a range finding module, etc.
Prior art relating to semiconductor photodetector elements will be explained with reference to the drawings.
An example of a semiconductor photodetector element is shown in FIGS.
6
(A) through
6
(C) and includes a semiconductor chip
50
, leads
51
, a package
52
, an adhesive for die bonding
53
, an optical element structure
54
, wires
55
, and a cavity
56
.
On the surface of the semiconductor chip
50
, there is provided a photodetector section
50
a
. The semiconductor chip
50
is die bonded to the package
52
, which is integrally molded with the leads
51
, on a die pad section
52
a
, using an adhesive for die bonding
53
, such as epoxy resin. Electrodes
50
b
on the semiconductor chip
50
and the leads
51
are electrically connected by the wires
55
(for example, gold wires), respectively, and the optical element structure
54
is integrally formed on the package
52
.
The optical element structure
54
is formed of transparent resin or inorganic glass with the whole or a part thereof having a parallel flat plate or a lens that is transparent to specific wavelengths of received light. The cavity
56
inside the package
52
is filled with a gas (for example, air) and/or a liquid (for example, silicone oil) that allows the transmission of the light with the specific wavelengths, thereby providing a light detecting function.
A second example of a semiconductor photodetector element, as shown in FIGS.
7
(A) through
7
(C), is an advanced type of the above-described semiconductor photodetector element.
The semiconductor photodetector element of FIGS.
7
(A) through
7
(C) includes a semiconductor chip
60
having photodetector sections
60
a
at two positions at the left and the right thereof, leads
61
, a package
62
having a die pad section
62
a
, a first optical element structure
63
as a parallel flat plate, wires
64
, and a second optical element structure
65
including a case
65
a
operating as both a case and an iris, a left-hand lens
65
b
, and a right-hand lens
65
c
. The first optical element structure
63
and the package
62
are bonded together by an adhesive. In addition, the second optical element structure
65
and the first optical element structure
63
are bonded together by an adhesive.
An example of a semiconductor light detecting device, which has been published in JP-A-5-240710, is shown in FIGS.
8
(A) through
8
(C). The semiconductor light detecting device is assembled with an image sensor chip
71
on a package
70
with package leads
72
. The image sensor chip
71
and the package leads
72
are electrically connected by bonding wires
73
. On the image sensor chip
71
, there is formed a solder bump
74
at a specified position. A tunable optical band-pass filter
75
is positioned for mounting on the image sensor chip
71
by abutting the solder bump
74
. The tunable optical bandpass filter
75
and the image sensor chip
71
are bonded together by an adhesive
76
, on which a light shielding resin
77
is formed.
An example of a semiconductor light emitting element, which has been published in JP-A-9-8358, is shown in FIGS.
9
(A) and
9
(B). The semiconductor light emitting element of FIGS.
9
(A) and
9
(B) includes a semiconductor chip
80
that has become approximately cube-shaped as the area of semiconductor chip
80
has been downsized, thereby becoming tall and unstable. In particular, a lead
81
is provided with a recess
81
a
in which the bottom of the semiconductor chip
80
is placed. An electrode
80
a
is provided at the top and the bottom of the semiconductor chip
80
, which has a light emitting layer. One electrode
80
a
is die bonded to the lead
81
at the bottom of the semiconductor chip
80
, while the other electrode
80
a
is electrically connected to another lead
82
by a wire
83
. Then, molding with a transparent resin is performed to form a semiconductor light emitting element. An advantage of the semiconductor light emitting element of FIGS.
9
(A) and
9
(B) is that the die bonding of the semiconductor chip
80
to the lead
81
can be easily performed.
In the semiconductor photodetector element having a light detecting function, as shown in FIGS.
6
(A) through
6
(C), the semiconductor chip
50
is mounted on the die pad section
52
a
of the package
52
using a die bonder (not shown). The mounting position of the semiconductor chip
50
to the package
52
depends largely on the performance of the die bonder.
For example, when the semiconductor chip
50
is picked up from a diced wafer by suction of a chuck of the die bonder for mounting on the package
52
, there are variations in the position of the picked up semiconductor chip
50
with respect to the chuck or in the position of the chip when placed on the target package
52
. Therefore, even when the chuck itself is aligned with high-accuracy, there is still a problem in that the position of the semiconductor chip
50
varies when placed on the package
52
.
Moreover, in a die bonder with improved mounting accuracy, the position of the semiconductor chip
50
picked up by the chuck using suction is measured with respect to the position and the direction of the chuck using a measuring method such as image processing, and the position of the package
52
is measured before the semiconductor chip
50
is mounted on the package
52
to minimize misalignment error.
However, the semiconductor chip
50
moves when released from the chuck. Also, when the adhesive for die bonding
53
between the semiconductor chip
50
and the die pad section
52
a
is cured by heat or ultraviolet light, bonding the semiconductor chip
50
to the die pad section
52
a
, there arises a problem in that a shock applied during transfer to a curing processing unit, or nonuniform internal stress of the adhesive for die bonding
53
caused in a curing process, results in a shift in the position of the semiconductor chip
50
. Similar problems exist in the semiconductor photodetector element shown in FIGS.
7
(A) through
7
(C) when mounting the semiconductor chip
60
on the package
62
.
To cope with the shifting produced when the semiconductor chips
50
and
60
are die bonded, or when a lens (not shown) is combined with the optical element structure
54
in FIG.
6
(C), an effective light detecting region of the semiconductor photodetector element is made larger within a margin in anticipation of the shift produced when assembling the semiconductor photodetector element. Thus, the produced shift between the center of the optical system and the center of the light detecting region can be corrected to attain the proper operation.
When the semiconductor photodetector element of FIGS.
7
(A) through
7
(C) is used, for example, as a range finding module, light beams providing scenes identical to each other are projected onto two linear photodetector sections
60
a
on the semiconductor chip
60
using the two convex lenses
65
b
and
65
c
of the second optical element structure
65
, to obtain the distance to the scene using a phase difference between respective projected images. To prevent measuring error in the range finding, the second optical element structure
65
is mounted so that line segments connecting optical centers of the two convex lenses
65
b
and
65
c
to the centers of the respective photodetector sections

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